WO2008137084A2

WO2008137084A2 - Diazaquinolones that inhibit prolyl hydroxylase activity

Info

Publication number: WO2008137084A2
Application number: PCT/US2008/005698
Authority: WO
Inventors: Jennifer R. Allen; Kaustav Biswas; Roland Burli; Jennifer E. Golden; Stephanie Mercede; Christopher M. Tegley
Original assignee: Amgen Inc.
Priority date: 2007-05-04
Filing date: 2008-05-02
Publication date: 2008-11-13
Also published as: AU2008248165B2; US20090099171A1; US8097620B2; AU2008248165A1; EP2155746A2; CA2685219A1; WO2008137084A3; CA2685219C

Abstract

Compounds of Formula (I) are useful inhibitors of HIF prolyl hydroxylases. Compounds of Formula I have the following structure where the definitions of the variables are provided herein.

Description

DIAZAQUINOLONES THAT INHIBIT PROLYL HYDROXYLASE

ACTIVITY

CROSS REFERENCES TO RELATED APPLICATIONS

[001] This application claims the benefit of United States Provisional

Application No. 60/927,748, filed on May 4, 2007, which is hereby incorporated by reference in its entirety and for all purposes as if fully set forth herein.

FIELD OF THE INVENTION

[002] The present invention relates to compounds capable of inhibiting prolyl hydroxylases such as HIF prolyl hydroxylases, compounds that modulate HIF levels, compounds that stabilize HIF, compositions comprising the compounds, and methods for their use for controlling HIF levels. The compounds and compositions may be used to treat diseases or conditions modulated by HIF such as ischemia, anemia, wound healing, auto- transplantation, allo-transplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, and inflammatory disorders.

BACKGROUND OF THE INVENTION

[003] The cellular transcription factor HIF (Hypoxia Inducible Factor) occupies a central position in oxygen homeostasis in a wide range of organisms and is a key regulator of responses to hypoxia. The genes regulated by HIF transcriptional activity can play critical roles in angiogenesis, erythropoiesis, hemoglobin F production, energy metabolism, inflammation, vasomotor function, apoptosis and cellular proliferation. HIF can also play a role in cancer, in which it is commonly upregulated, and in the pathophysiological responses to ischemia and hypoxia.

[004] The HIF transcriptional complex comprises an αβ heterodimer:

HIF-β is a constitutive nuclear protein that dimerizes with oxygen-regulated HIF-α subunits. Oxygen regulation occurs through hydroxylation of the HIF-α subunits, which are then rapidly destroyed by the proteasome. In oxygenated cells, the von Hippel-Lindau tumor suppressor protein (pVHL) binds to hydroxylated HIF-α subunits, thereby promoting their ubiquitin dependent proteolysis. This process is suppressed under hypoxic conditions, stabilizing HIF-α and promoting transcriptional activation by the HIF αβ complex. See, e.g., U.S. Patent 6,787,326.

[005] Hydroxylation of HIF-α subunits can occur on proline and asparagine residues and can be mediated by a family of 2-oxoglutarate dependent enzymes. This family includes the HIF prolyl hydroxylase isozymes (PHDs), which hydroxylate Pro 402 and Pro 564 of human HIF lα, as well as Factor Inhibiting HIF (FIH), which hydroxylates Asn 803 of human HIF lα. Inhibition of FIH or the PHDs leads to HIF stabilization and transcriptional activation. See, e.g., Schofield and Ratcliffe, Nature Rev. MoI. Cell Biol., VoI 5, pages 343-354 (2004).

SUMMARY OF THE INVENTION

In one aspect, the invention provides composition of matter that includes at least one compound of Formula I:

I a pharmaceutically acceptable salt thereof, a tautomer thereof, or a pharmaceutically acceptable salt of the tautomer; or a solvate thereof, a chelate thereof, a non-covalent complex thereof, a prodrug thereof, or a mixture of any of the foregoing, wherein:

J, K, L, and M are selected from CR₆ or N, wherein two of J, K, L, and M are N and the other two of J, K, L, and M are CR₆; n is 1 to 6; Ri and R₂ are independently selected in each instance from H, lower alkyl, substituted lower alkyl, lower haloalkyl, or substituted lower haloalkyl, or R] and R₂ can join together to form a 3 to 6 membered ring or a substituted 3 to 6 membered ring;

X is selected from -NR₃-, -O-, or -S-, wherein R₃ is selected from H or lower alkyl;

R₃ is selected from OH, SH, NH_2> lower alkyl, substituted lower alkyl, lower alkoxy, substituted lower alkoxy, or sulfanyl;

R₄ is selected from H, OH, lower alkoxy, SH, NH₂, NHSO₂R₇, or sulfonyl;

R₅ is selected from H, lower alkyl, or substituted lower alkyl; each R₆ is independently selected from H, F, Cl, Br, I, alkyl, substituted alkyl, haloalkyl, perhaloalkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, NRjR₆, C(O)R₇, C(O)OR₈, OR₈, SR₈, SO₂R₈, CN, NO₂, aryl, substituted aryl, arylalkyl, substituted arylalkyl, heteroaryl, substituted heteroaryl, heteroarylalkyl, substituted heteroarylalkyl, heterocyclyl, substituted heterocyclyl, heterocyclylalkyl, substituted heterocyclylalkyl, or -Y-R₉, wherein:

Y is selected from -N(R₎₀)-Z- or -Z-N(Ri₀)-;

Z is selected from C(O), SO₂, alkylene, substituted alkylene, alkenylene, substituted alkenylene, alkynylene, or substituted alkynylene;

R₇ is selected from H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl heterocyclyl, substituted heterocyclyl, aryl, substituted aryl, heteroaryl, or substituted heteroaryl;

R₈ is selected from H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, or substituted alkynyl;

R₉ is selected from H, heterocyclyl, substituted heterocyclyl, aryl, substituted aryl, heteroaryl, or substituted heteroaryl;

Rio is selected from H, lower alkyl, or substituted lower alkyl; and R_d and R_e are independently selected from H, lower alkyl, substituted lower alkyl, lower haloalkyl, or substituted lower haloalkyl, or R_d and R_e can join together to form a 3 to 6 membered ring or a substituted 3 to 6 membered ring.

[006] In some embodiments, M and L are N and J and K are CR₆. In other embodiments, M and K are N and J and L are CR₆. In still further embodiments, J and M are N and K and L are CR₆.

[007] In some embodiments, Ri and R₂ are not both H if X is -NR₃-; R₃ is H; and n is 1.

[008] In some embodiments, n is 1, Ri and R₂ are both H, X is -NR₃-; and R₃ is H.

[009] In some embodiments, at least one of Ri and R₂ is not H. In some such embodiments, at least one of Ri and R₂ is a lower alkyl such as a (Ci- C₄)alkyl. In some such embodiments, one of Ri and R₂ is H and the other of Ri and R₂ is a lower alkyl. In some such embodiments, at least one of Ri and R₂ is a methyl group, and in some such embodiments, the other of Ri and R₂ is a methyl group.

[010] In some embodiment, R₃ is OH.

[011] In some embodiments, R₄ is selected from OH, SH, NH_2>

NHSO₂R₈, or sulfonyl. In some such embodiments, R₄ is OH. [012] In some embodiments, X is -NR_a-. In some such embodiments, X is -NH-.

[013] In some embodiments, at least one instance of R₆ is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted heterocyclyl group. In some such embodiments, at least one instance of R₆ is a heterocyclyl group. In other such embodiments, at least one instance of Re is a heteroaryl group. In other such embodiments, at least one instance of Re is a phenyl or substituted phenyl group.

[014] In some embodiments, at least one instance OfR₆ is independently selected from halo or a moiety substituted with at least one halo. For example, in some embodiments, at least one instance Of R₆ is haloalkyl. In some embodiments, at least one instance of R₆ is a perhaloalkyl. In some such embodiments, the perhaloalkyl is a perfluoroalkyl group such as CF₃.

[015] In some embodiments, n is 1.

[016] In some embodiment, Ri and R₂ are independently chosen from H and lower alkyl. In some such embodiments, Ri and R₂ are both H. In some such embodiments, n is 1.

[017] In some embodiments, n is 1; Rj is H or lower alkyl; R₂ is H; R₃ is OH; R₄ is OH; X is -NR₃-; and R_a is H.

[018] In some embodiments of the compound of Formula I, R₅ is H. In other embodiments, R₅ is a lower alkyl group. In some such embodiments, R₅ is a methyl. In still other embodiments, R₅ is a substituted lower alkyl selected from an arylalkyl, a heteroarylalkyl, a heterocyclylalkyl, a cycloalkylalkyl, a hydroxy alkyl, an alkoxy alkyl, or a haloalkyl.

[019] In some embodiments, the compound of Formula I has the

Formula IA, and the variables have the definitions provided in any of the aspects and embodiments described above.

IA.

[020] In some embodiments, the compound of Formula I has the

Formula IB, and the variables have the definitions provided in any of the aspects and embodiments described above.

IB.

[021] In some embodiments, the compound of Formula I has the

Formula IC, and the variables have the definitions provided in any of the aspects and embodiments described above.

IC.

[022] In some embodiments, the composition of matter is a salt. Such salts may be anhydrous or associated with water as a hydrate. [023] In some embodiments, the composition of matter is a prodrug. In some such embodiments, the composition of matter is a (CfC₆)alkyl ester such as a methyl, ethyl, propyl, butyl, pentyl, or hexyl ester. [024] Also provided herein are pharmaceutical formulations that include at least one pharmaceutically acceptable carrier, excipient or diluent and a therapeutically effective amount of the composition of matter of any of the embodiments described herein. In such embodiments, the composition of matter is present in an amount effective for the treatment of at least one disease selected from ischemia, anemia, wound healing, auto-transplantation, allotransplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder. [025] Further provided are pharmaceutical formulations that include at least one pharmaceutically acceptable carrier, and a therapeutically effective amount of the composition of matter of any of the embodiments described herein in combination with at least one additional compound such as an erythropoiesis stimulating agent or a chemotherapeutic agent. [026] Additionally provided is a method of increasing or stabilizing

HIF levels or activity in a subject by administering to the subject the composition of matter of any of the embodiments described herein. [027] Further provided is a method of treating a condition where it is desired to modulate HIF activity comprising administering to a subject the composition of matter of any of the embodiments described herein. In some such embodiments, the condition is selected from at least one of ischemia, anemia, wound healing, auto- transplantation, allo- transplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

[028] Also provided is a method of treating a hypoxic or ischemic related disorder in a subject comprising administering to a subject the composition of matter of any of the embodiments described herein. [029] Also provided is a method of treating anemia in a subject comprising administering to a subject the composition of matter of any of the embodiments described herein.

[030] Further provided is a method of modulating the amount of HIF in a cell comprising contacting the cell with the composition of matter of any of the embodiments described herein.

[031] Additionally provided is a method of increasing the amount of hemoglobin F in a subject comprising administering to the subject the composition of matter of any of the embodiments described herein. [032] Also provided is a method of modulating angiogenesis in a subject comprising administering to the subject the composition of matter of any of the embodiments described herein. [033] Additionally provided is a method of treating at least one disease in a patient in need of such treatment comprising administering to the patient a therapeutically effective amount of the composition of matter of any of the embodiments described herein. In some such embodiments, the at least one disease is selected from ischemia, anemia, wound healing, auto- transplantation, allo- transplantation, xeno-transplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

[034] Also provided is a method of inhibiting HIF hydroxylation in a subject comprising administering to the subject the composition of matter n of any of the embodiments described herein.

[035] In some embodiments, the HIF PHD inhibitory activity IC₅₀ value of the composition of matter is 40 μM or less. In other embodiments, the HIF

PHD inhibitory activity IC_5O value of the composition of matter is 10 μM or less.

[036] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament.

[037] In some such embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for increasing or stabilizing HIF levels or activity in a subject.

[038] In some such embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for treating a condition where it is desired to modulate HIF activity. In some such embodiments, the condition is selected from at least one of ischemia, anemia, wound healing, auto- transplantation, allo- transplantation, xeno-transplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

[039] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for treating a hypoxic or ischemic related disorder in a subject.

[040] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for modulating the amount if HIF in a cell. In some embodiments, the composition of matter according to any of the embodiments is used to modulate the amount of HIF in a cell.

[041 ] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for modulating angiogenesis in a subject.

[042] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for inhibiting HIF hydroxylation in a subject.

[043] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for treating anemia.

[044] In some embodiments, the composition of matter of any of the embodiments is used in a method for increasing the level of erythropoietin in the blood of a subject.

[045] Other objects, features and advantages of the invention will become apparent to those skilled in the art from the following description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[046] Figure l is a graph illustrating the ratio of fluorescence signal to background generated by the interaction of Eu-VCB with streptavidin-APC- hydroxyprolyl HIF lα peptide.

[047] Figures 2 A and 2B are graphs illustrating the ratio of TR-FRET signal generated by the interaction of Eu-VCB with streptavidin-APC- hydroxyprolyl HIF lα peptide over background signal generated by the interaction of Eu-VCB with streptavidin-APC-HIFlα peptide (nonhydroxylated). Figure 2 A illustrates a 0-125 nM peptide range and Figure 2B illustrates a 0-10 nM peptide range.

[048] Figures 3A and 3B are graphs illustrating VCB binding and TR-

FRET detection for determining HIF PHD2 hydroxylation of a HIF lα peptide. Figure 3A illustrates a time course for the hydroxylation of the HIFlα peptide with increasing amounts of HIF PHD2 enzyme. Figure 3B illustrates initial rates with increasing enzyme concentrations.

DETAILED DESCRIPTION OF THE INVENTION

[049] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the standard deviation found in their respective testing measurements.

[050] As used herein, if any variable occurs more than one time in a chemical formula, its definition on each occurrence is independent of its definition at every other occurrence. If the chemical structure and chemical name conflict, the chemical structure is determinative of the identity of the compound. The compounds of the present disclosure may contain one or more chiral centers and/or double bonds and therefore, may exist as stereoisomers, such as double-bond isomers (i.e., geometric isomers), enantiomers or diastereomers. Accordingly, any chemical structures within the scope of the specification depicted, in whole or in part, with a relative configuration encompass all possible enantiomers and stereoisomers of the illustrated compounds including the stereoisomerically pure form (e.g., geometrically pure, enantiomerically pure or diastereomerically pure) and enantiomeric and stereoisomeric mixtures. Enantiomeric and stereoisomeric mixtures can be resolved into the component enantiomers or stereoisomers using separation techniques or chiral synthesis techniques well known to the skilled artisan. [051] Compounds of Formula I include, but are not limited to, optical isomers of compounds of Formula I, racemates, and other mixtures thereof. In those situations, the single enantiomers or diastereomers, i.e., optically active forms, can be obtained by asymmetric synthesis or by resolution of the racemates. Resolution of the racemates can be accomplished, for example, by conventional methods such as crystallization in the presence of a resolving agent, or chromatography, using, for example a chiral high-pressure liquid chromatography (HPLC) column. In addition, compounds of Formula I include Z- and E- forms (or cis- and trans- forms) of compounds with double bonds. [052] Compounds of the invention may exist in multiple tautomeric forms. These forms are illustrated below as "Tautomer A", "Tautomer B", and "Tautomer C":

Tautomer A Tautomer B

Tautomer C Compounds of the invention are depicted structurally and named as compounds in the "Tautomer A" form. However, it is specifically contemplated that the compounds may also exist in "Tautomer B" or "Tautomer C" form and compounds in "Tautomer B" form or "Tautomer C" form or another tautomeric form are expressly considered to be part of the invention. [053] Compounds of the present disclosure include, but are not limited to, compounds of Formula I and all pharmaceutically acceptable forms thereof. Pharmaceutically acceptable forms of the compounds recited herein include pharmaceutically acceptable salts, solvates, crystal forms (including polymorphs and clathrates), chelates, non-covalent complexes, prodrugs, and mixtures thereof. In certain embodiments, the compounds described herein are in the form of pharmaceutically acceptable salts. As used herein, the term "compound" encompasses not only the compound itself, but also a pharmaceutically acceptable salt thereof, a solvate thereof, a chelate thereof, a non-covalent complex thereof, a prodrug thereof, and mixtures of any of the foregoing. In some embodiments, the term "compound" encompasses the compound itself, pharmaceutically acceptable salts thereof, tautomers of the compound, pharmaceutically acceptable salts of the tautomers, and ester prodrugs such as (Ci-C₄)alkyl esters. In other embodiments, the term "compound: encompasses the compound itself, pharmaceutically acceptable salts thereof, tautomers of the compound, pharmaceutically acceptable salts of the tautomers

[054] As noted above, prodrugs also fall within the scope of chemical entities, for example, ester or amide derivatives of the compounds of Formula I. The term "prodrugs" includes any compounds that become compounds of Formula I when administered to a patient, e.g., upon metabolic processing of the prodrug. Examples of prodrugs include, but are not limited to, acetate, formate, benzoate, carbomethoxy, carboethoxy and like derivatives of functional groups (such as alcohol, carboxylic acid, ether, ester, or amine groups) in the compounds of Formula I. In some embodiments, the prodrugs of the compounds of Formula I are esters such as methyl, ethyl, propyl, butyl, pentyl, and hexyl esters.

[055] The term "solvate" refers to the compound formed by the interaction of a solvent and a compound. Suitable solvates are pharmaceutically acceptable solvates, such as hydrates, including monohydrates and hemi- hydrates.

[056] "Alkyl" refers to a saturated, branched, straight-chain, or cyclic monovalent hydrocarbon group derived by the removal of one hydrogen atom from a single carbon atom of a parent alkane. Typical alkyl groups include, but are not limited to, methyl, ethyl, propyls such as propan-1-yl, propan-2-yl, and cyclopropan-1-yl, butyls such as butan-1-yl, butan-2-yl, 2-methyl-propan-l-yl, 2-methyl-propan-2-yl, cyclobutan-1-yl, tert-butyl, and the like. In certain embodiments, an alkyl group comprises from 1 to 20 carbon atoms. As used herein the term "lower alkyl" refers to an alkyl group comprising from 1 to 6 carbon atoms.

[057] "Alkenyl" refers to an unsaturated branched, straight-chain, or cyclic hydrocarbon group having at least one carbon-carbon double bond derived by the removal of one hydrogen atom from a single carbon atom of a parent alkene. The group may be in either the Z- or E- form (cis or trans) about the double bond(s). Typical alkenyl groups include, but are not limited to, ethenyl; propenyls such as prop-1-en-l-yl, prop-l-en-2-yl, prop-2-en-l-yl (allyl), prop-2-en-2-yl, cycloprop-1-en-l-yl; cycloprop-2-en-l-yl; butenyls such as but-1-en-l-yl, but-l-en-2-yl, 2-methyl-prop-l-en-l-yl, but-2-en-l-yl, but-2-en-l-yl, but-2-en-2-yl, buta-l,3-dien-l-yl, buta-l,3-dien-2-yl, cyclobut-1-en-l-yl, cyclobut-l-en-3-yl, cyclobuta-l,3-dien-l-yl; and the like. In certain embodiments, an alkenyl group has from 2 to 20 carbon atoms and in other embodiments, from 2 to 6 carbon atoms, i.e. "lower alkenyl." [058] "Alkynyl" refers to an unsaturated branched or straight-chain hydrocarbon having at least one carbon-carbon triple bond derived by the removal of one hydrogen atom from a single carbon atom of a parent alkyne. Typical alkynyl groups include, but are not limited to, ethynyl; propynyl; butynyl, 2-pentynyl, 3-pentynyl, 2-hexynyl, 3-hexynyl and the like. In certain embodiments, an alkynyl group has from 2 to 20 carbon atoms and in other embodiments, from 2 to 6 carbon atoms, i.e. "lower alkynyl." [059] "Alkoxy" refers to a radical -OR where R represents an alkyl group as defined herein. Representative examples include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, cyclohexyloxy, and the like. Typical alkoxy groups include from 1 to 10 carbon atoms, from 1 to 6 carbon atoms or from 1 to 4 carbon atoms in the R group. Lower alkoxy groups include (Ci_-6) alkyl groups and, in some embodiments, may include (C_M) alkyl groups. [060] "Alkylene" refers to a divalent saturated hydrocarbon group derived from a parent alkane by removal of two hydrogen atoms. Examples of alkylene group include, but are not limited to, -CH₂-, -CH₂CH₂-, -CH(CH₃)-, -CH₂CH₂CH₂-, -CH₂C(CH₃)(H)-, and the like. [061] "Alkenylene" refers to a divalent unsaturated hydrocarbon group having at least one carbon-carbon double bond derived by the removal of two hydrogen atoms from a parent alkene. The group may be in either the Z- or E- form (cis or trans) about the double bond(s). Examples of alkenylene groups, include, but are not limited to, -CH=CH-, -CH=C(H)CH₂-, ^' CH₂C(H)=C(H)CH₂-, and the like.

[062] "Alkynylene" refers to a divalent unsaturated hydrocarbon group having at least one carbon-carbon triple bond derived by the removal of two hydrogen atoms from a parent alkyne. Example of alkynylene groups, include, but are not limited to, -C≡C-, -CH₂C≡C-, -CH₂C≡CCH₂-. [063] "Aryl" refers to a monovalent aromatic hydrocarbon group derived by the removal of one hydrogen atom from a single carbon atom of a parent aromatic ring system. Aryl encompasses 5- and 6-membered carbocyclic aromatic rings, for example, benzene; bicyclic ring systems wherein at least one ring is carbocyclic and aromatic, for example, naphthalene, indane, and tetralin; and tricyclic ring systems wherein at least one ring is carbocyclic and aromatic, for example, fluorene. For example, aryl includes 5- and 6-membered carbocyclic aromatic rings fused to a 5- to 7-membered heterocyclic ring containing 1 or more heteroatoms chosen from N, O, and S. In certain embodiments, an aryl group can comprise from 6 to 10 carbon atoms. Aryl, however, does not encompass or overlap in any way with heteroaryl, separately defined below. Hence, if one or more carbocyclic aromatic rings is fused with a heterocyclic aromatic ring, the resulting ring system is heteroaryl, not aryl, as defined herein.

[064] "Arylalkyl" or "aralkyl" refers to an acyclic alkyl group in which one of the hydrogen atoms bonded to a carbon atom, typically, but not necessarily, a terminal carbon atom, is replaced with an aryl group. Typical arylalkyl groups include, but are not limited to, benzyl, 2-phenylethan-l-yl, naphthylmethyl, 2-naphthylethan-l-yl, naphthobenzyl, 2-naphthophenylethan- 1 -yl and the like. In certain embodiments, an arylalkyl group can be (C_6-30) arylalkyl, e.g., the alkyl group of the arylalkyl group can be

(C_1-I0) and the aryl moiety can be (C_5-20).

[065] "Arylalkenyl" refers to an alkenyl group in which a bond to one of the hydrogen atoms of the alkenyl group is replaced with a bond to an aryl group.

[066] "Arylalkynyl" refers to an alkynyl group in which a bond to one of the hydrogen atoms of the alkynyl group is replaced with a bond to an aryl group.

[067] "Carbonyl" refers to the radical -C(O) group.

[068] "Carboxy" refers to the radical -C(O)OH.

[069] "Cyano" refers to the radical -CN.

[070] "Cycloalkyl" refers to a saturated or unsaturated cyclic alkyl group. Where a specific level of saturation is intended, the nomenclature

"cycloalkanyl" or "cycloalkenyl" is used. Typical cycloalkyl groups include, but are not limited to, groups derived from cyclopropane, cyclobutane, cyclopentane, cyclohexane, and the like. In certain embodiments, the cycloalkyl group can be C_3-I0 cycloalkyl, such as, for example, C_3-6 cycloalkyl.

[071] "Heterocyclic", "heterocyclo" or "heterocyclyl" refer to a saturated or unsaturated, but non-aromatic, cyclic hydrocarbon group in which one or more carbon atoms (and any associated hydrogen atoms) are independently replaced with the same or different heteroatom and its associated hydrogen atoms, where appropriate. Typical heteroatoms to replace the carbon atom(s) include, but are not limited to, N, O, and S. Typical heterocyclyl groups include, but are not limited to, groups derived from epoxides, imidazolidine, morpholine, piperazine, piperidine, pyrazolidine, pyrrolidine, quinuclidine, tetrahydrofuran, tetrahydropyran and the like. Substituted heterocyclyl also includes ring systems substituted with one or more oxo (=0) or oxide (-0") substituents, such as piperidinyl N-oxide, morpholinyl-N-oxide, 1-oxo-l- thiomorpholinyl and 1,1-dioxo-l-thiomorpholinyl.

[072] "Heterocyclylalkyl" refers to an alkyl group in which one of the hydrogen atoms of the alkyl is replaced with a bond to a heterocyclyl group. Examples of heterocyclylalkyl groups, include, but are not limited to, morpholinylmethyl, morpholinylethyl, tetrahydrofuranylmethyl, piperidinylmethyl, and the like.

[073] "Disease" refers to any disease, disorder, condition, symptom, or indication.

[074] "Halo" or "halogen" refers to a fluoro, chloro, bromo, or iodo group.

[075] "Haloalkyl" refers to an alkyl group in which at least one hydrogen is replaced with a halogen. Thus, the term "haloalkyl" includes monohaloalkyl (alkyl substituted with one halogen atom) and polyhaloalkyl (alkyl substituted with two or more halogen atoms). The term "perhaloalkyl" means, unless otherwise stated, an alkyl group in which each of the hydrogen atoms is replaced with a halogen atom. For example, the term "perhaloalkyl", includes, but is not limited to, trifluoromethyl, pentachloroethyl, 1,1,1-trifluoro- 2-bromo-2-chloroethyl, and the like.

[076] "Heteroaryl" refers to a monovalent heteroaromatic group derived by the removal of one hydrogen atom from a single atom of a parent heteroaromatic ring system. Heteroaryl encompasses 5- to 7-membered aromatic, monocyclic rings containing one or more, for example, from 1 to 4, or in certain embodiments, from 1 to 3, heteroatoms chosen from N, O, and S, with the remaining ring atoms being carbon; and polycyclic ring systems containing one or more, for example, from 1 to 4, or in certain embodiments, from 1 to 3, heteroatoms chosen from N, O, and S, with the remaining ring atoms being carbon and wherein at least one heteroatom is present in an aromatic ring. For example, heteroaryl includes a 5- to 7-membered heteroaromatic ring fused to a 5- to 7-membered cycloalkyl ring or a carbocyclic aromatic ring and a 5- to 7- membered heteroaromatic ring fused to a 5- to 7-membered heterocyclic ring. For fused, bicyclic heteroaryl ring systems wherein only one of the rings contains one or more heteroatoms, the point of attachment may be at the heteroaromatic ring or the carbocyclic ring. When the total number of S and O atoms in the heteroaryl group exceeds 1, those heteroatoms are not adjacent to one another. In certain embodiments, the total number of S and O atoms in the heteroaryl group is not more than 2. In certain embodiments, the total number of S and O atoms in the aromatic heterocycle is not more than 1. Heteroaryl does not encompass or overlap with aryl as defined above. Typical heteroaryl groups include, but are not limited to, groups derived from acridine, arsindole, carbazole, β-carboline, chromane, chromene, cinnoline, furan, imidazole, indazole, indole, indoline, indolizine, isobenzofuran, isochromene, isoindole, isoindoline, isoquinoline, isothiazole, isoxazole, naphthyridine, oxadiazole, oxazole, perimidine, phenanthridine, phenanthroline, phenazine, phthalazine, pteridine, purine, pyran, pyrazine, pyrazole, pyridazine, pyridine, pyrimidine, pyrrole, pyrrolizine, quinazoline, quinoline, quinolizine, quinoxaline, tetrazole, thiadiazole, thiazole, thiophene, triazole, xanthene, and the like. In certain embodiments, the heteroaryl group can be between 5 to 20 membered heteroaryl, such as, for example, a 5 to 10 membered heteroaryl. In certain embodiments, heteroaryl groups can be those derived from thiophene, pyrrole, benzothiophene, benzofuran, indole, pyridine, quinoline, imidazole, oxazole, and pyrazine.

[077] "Heteroarylalkyl" or "heteroaralkyl" refers to an acyclic alkyl group in which one of the hydrogen atoms bonded to a carbon atom, typically a terminal or sp³ carbon atom, is replaced with a heteroaryl group. Where specific alkyl moieties are intended, the nomenclature heteroarylalkanyl, heteroarylalkenyl, and/or heteroarylalkynyl is used. In certain embodiments, the heteroarylalkyl group can be a 6 to 30 membered heteroarylalkyl, e.g., the alkyl moiety of the heteroarylalkyl can include 1 to 10 members and the heteroaryl moiety of the heteroarylalkyl can include from 5 to 20-members. [078] "Sulfonyl" refers to a radical -S(O)₂R where R is an alkyl, substituted alkyl, substituted cycloalkyl, substituted heterocyclyl, substituted aryl, or substituted heteroaryl group as defined herein Representative examples include, but are not limited to, methyl sulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, and the like. [079] "Sulfanyl" refers to a radical -SR where R is an alkyl, substituted alkyl, substituted cycloalkyl, substituted heterocyclyl, substituted aryl, or substituted heteroaryl group as defined herein that may be optionally substituted as defined hereia Representative examples include, but are not limited to, methylthio, ethylthio, propylthio, butylthio, and the like. [080] "Pharmaceutically acceptable" refers to generally recognized for use in animals, and more particularly in humans.

[081] "Pharmaceutically acceptable salt" refers to a salt of a compound that is pharmaceutically acceptable and that possesses the desired pharmacological activity of the parent compound. Such salts include: (1) acid addition salts, formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like; or formed with organic acids such as acetic acid, propionic acid, hexanoic acid, cyclopentanepropionic acid, glycolic acid, pyruvic acid, lactic acid, malonic acid, succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, 3-(4-hydroxybenzoyl) benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, and the like; or (2) salts formed when an acidic proton present in the parent compound either is replaced by a metal ion, e.g., an alkali metal ion, an alkaline earth ion, or an aluminum ion; or coordinates with an organic base such as ethanolamine, diethanolamine, triethanolamine, N- methylglucamine, dicyclohexylamine, and the like.

[082] "Pharmaceutically acceptable excipient," "pharmaceutically acceptable carrier," or "pharmaceutically acceptable adjuvant" refer, respectively, to an excipient, carrier or adjuvant with which at least one compound of the present disclosure is administered. "Pharmaceutically acceptable vehicle" refers to any of a diluent, adjuvant, excipient or carrier with which at least one compound of the present disclosure is administered. [083] "Stereoisomer" refers to an isomer that differs in the arrangement of the constituent atoms in space. Stereoisomers that are mirror images of each other and optically active are termed "enantiomers," and stereoisomers that are not mirror images of one another and are optically active are termed "diastereomers."

[084] "Subject" includes mammals and humans. The terms "human" and "subject" are used interchangeably herein.

[085] "Substituted" refers to a group in which one or more hydrogen atoms are each independently replaced with the same or different substituent(s). Typical substituents include, but are not limited to, -X, -Rn, -OH, =0, -ORn, -SR_{1 1}, -SH, -S, -NR₁₁R₁₂, =NR_π, -CX₃, -CF₃, -CN -NO₂ -S(O)₂R_n, -OS(O₂)OH, -OS(O)₂R_n, -OP(O)(OR_{1 1})(OR₁₂), -C(O)R_n, -C(S)R_n, -C(O)OR_n, -C(O)NR₁₁R₁₂, -C(O)OH, -C(S)OR_n, -NR₁₃C(O)NR_nR₁₂, -NR₁₃C(S)NR₁ ,R₁₂, -NR₁₃C(NR₁ ,)NR, ,R₁₂₅-C(NR₁ ,)NR, ,R₁₂, -S(O)₂NR₁ ,R₁₂, -NR₁₃S(O)₂R_n, -NR₁₃C(O)R₁₁, and -S(O)R_n where each X is independently a halo; each R_n and Ri₂ are independently hydrogen, alkyl, substituted alkyl, alkyl interrupted by one or more -O- or -S- groups, aryl, substituted aryl, arylalkyl, substituted arylalkyl, cycloalkyl, substituted cycloalkyl, heterocyclyl, substituted heterocyclyl, heteroaryl, substituted heteroaryl, heteroarylalkyl, substituted heteroarylalkyl,— NR₁₃R₁₄, -C(O)R₁₃ or -S(O)₂R]₃ or optionally R_n and R₁₂ together with the atom to which R_{1 \} and R₁₂ are attached form one or more heterocyclyl, substituted heterocyclyl, heteroaryl, or substituted heteroaryl rings; and R₁₃ and R₁₄ are independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl, cycloalkyl, substituted cycloalkyl, heterocyclyl, substituted heterocyclyl, heteroaryl, substituted heteroaryl, heteroarylalkyl or substituted heteroarylalkyl, or optionally R₁₃ and Rj₄ together with the nitrogen atom to which R₁₃ and R₁₄ are attached form one or more heterocyclyl, substituted heterocyclyl, heteroaryl, or substituted heteroaryl rings. In certain embodiments, a tertiary amine or aromatic nitrogen may be substituted with on or more oxygen atoms to form the corresponding nitrogen oxide.

[086] "Therapeutically effective amount" refers to the amount of a compound that, when administered to a subject for treating a disease, or at least one of the clinical symptoms of a disease or disorder, is sufficient to affect such treatment for the disease, disorder, or symptom. The "therapeutically effective amount" can vary depending on the compound, the disease, disorder, and/or symptoms of the disease or disorder, severity of the disease, disorder, and/or symptoms of the disease or disorder, the age of the subject to be treated, and/or the weight of the subject to be treated. An appropriate amount in any given instance can be readily apparent to those skilled in the art or capable of determination by routine experimentation.

[087] "Treating" or "treatment" of any disease or disorder refers to arresting or ameliorating a disease, disorder, or at least one of the clinical symptoms of a disease or disorder, reducing the risk of acquiring a disease, disorder, or at least one of the clinical symptoms of a disease or disorder, reducing the development of a disease, disorder or at least one of the clinical symptoms of the disease or disorder, or reducing the risk of developing a disease or disorder or at least one of the clinical symptoms of a disease or disorder. "Treating" or "treatment" also refers to inhibiting the disease or disorder, either physically, (e.g., stabilization of a discernible symptom), physiologically, (e.g., stabilization of a physical parameter), or both, or inhibiting at least one physical parameter which may not be discernible to the subject. Further, "treating" or "treatment" refers to delaying the onset of the disease or disorder or at least symptoms thereof in a subject which may be exposed to or predisposed to a disease or disorder even though that subject does not yet experience or display symptoms of the disease or disorder.

[088] Reference will now be made in detail to embodiments of the present disclosure. While certain embodiments of the present disclosure will be described, it will be understood that it is not intended to limit the embodiments of the present disclosure to those described embodiments. To the contrary, reference to embodiments of the present disclosure is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the embodiments of the present disclosure as defined by the appended claims. In one aspect, the invention provides composition of matter that includes at least one compound of Formula I:

J, K, L, and M are selected from CR₆ or N, wherein two of J, K, L, and M are N and the other two of J, K, L, and M are CR₆; n is 1 to 6;

R] and R₂ are independently selected in each instance from H, lower alkyl, substituted lower alkyl, lower haloalkyl, or substituted lower haloalkyl, or R] and R₂ can join together to form a 3 to 6 membered ring or a substituted 3 to 6 membered ring;

R₃ is selected from OH, SH, NH_2; lower alkyl, substituted lower alkyl, lower alkoxy, substituted lower alkoxy, or sulfanyl;

R₄ is selected from H, OH, lower alkoxy, SH, NH₂, NHSO₂R₇, or sulfonyl;

Y is selected from -N(Ri ₀)-Z- or -Z-N(R]₀)-;

Ri₀ is selected from H, lower alkyl, or substituted lower alkyl; and

R_d and R_e are independently selected from H, lower alkyl, substituted lower alkyl, lower haloalkyl, or substituted lower haloalkyl, or Ra and R_e can join together to form a 3 to 6 membered ring or a substituted 3 to 6 membered ring.

[089] In some embodiments, Ri and R₂ are not both H if X is -NR₃-; R_a is H; and n is 1.

[090] In some embodiments, n is 1, Ri and R₂ are both H, X is -NR₃-; and R₃ is H.

[091] In some embodiments, at least one of Ri and R₂ is not H. In some such embodiments, at least one of Ri and R₂ is a lower alkyl such as a (Cj- C₄)alkyl. In some such embodiments, one of Ri and R₂ is H and the other of Ri and R₂ is a lower alkyl. In some such embodiments, at least one of Ri and R₂ is a methyl group, and in some such embodiments, the other of Ri and R₂ is a methyl group. [092] In some embodiments, M and L are N and J and K are CR₆. In other embodiments, M and K are N and J and L are CR₆. In still other embodiments, J and M are N and K and L are CR₆.

[093] In some embodiment, R₃ is OH.

[094] In some embodiments, R₄ is selected from OH, SH, NH_2;

NHSO₂R₈, or sulfonyl. In some such embodiments, R₄ is OH.

[095] In some embodiments, X is -NR₃-. In some such embodiments, X is -NH-.

[096] In some embodiments, at least one instance of R₆ is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted heterocyclyl group.

In some such embodiments, at least one instance of R₆ is a heterocyclyl group.

In other such embodiments, at least one instance of R₆ is a heteroaryl group. In other such embodiments, at least one instance of R₆ is a phenyl or substituted phenyl group.

[097] In some embodiments, at least one instance OfR₆ is independently selected from halo or a moiety substituted with at least one halo.

For example, in some embodiments, at least one instance Of R₆ is haloalkyl. In some embodiments, at least one instance of R₆ is a perhaloalkyl. In some such embodiments, the perhaloalkyl is a perfluoroalkyl group such as CF₃.

[098] In some embodiments, one instance Of R₆ is selected from -Cl,

-CF₃, -SMe, -OMe, or a group having the formula

or

, wherein the wavy line indicates the point of attachment to the rest of the molecule. In some such embodiments, one of R_O is selected from a

group having the formula

line indicates the point of attachment to the rest of the molecule. [099] In some embodiments, one instance Of R₆ is selected from -Cl,

-CF₃, -SMe, -OMe, or a group having

,wherein the wavy line indicates the point of attachment to the rest of the molecule. In some such embodiments, one of R₆ is selected from a group having the formula

point of attachment to the rest of the molecule.

[0100] In some embodiments, R₆ is a group having the formula

[0101] In some embodiments, R₆ is a group having the formula

[0102] In some embodiments, R₆ is a group having the formula

[0103] In some embodiments, R₆ is a group having the formula

[0104] In some embodiments, R₆ is a group having the formula

[0105] In some embodiments, R₆ is a group having the formula

[0106] In some embodiments, R₆ is a group having the formula

[0107] In some embodiments, R₆ is a group having the formula

[0108] In some embodiments, R₆ is a group having the formula

[0109] In some embodiments, R₆ is a group having the formula

[0110] In some embodiments, R₆ is a group having the formula

[0111] In some embodiments, R₆ is a group having the formula

[01 12] In some embodiments, n is 1.

[0113] In some embodiment, Ri and R₂ are independently chosen from H and lower alkyl. In some such embodiments, Ri and R₂ are both H. In some such embodiments, n is 1.

[0114] In some embodiments, n is 1 ; Ri is H or lower alkyl; R₂ is H; R₃ is OH; R₄ is OH; X is -NR₃-; and R₃ is H.

[01 15] In some embodiments of the compound of Formula I, R₅ is H. In other embodiments, R₅ is a lower alkyl group. In some such embodiments, R₅ is a methyl. In still other embodiments, R₅ is a substituted lower alkyl selected from an arylalkyl, a heteroarylalkyl, a heterocyclylalkyl, a cycloalkylalkyl, a hydroxyalkyl, an alkoxyalkyl, or a haloalkyl.

[0116] In some embodiments, the compound of Formula I has the

IA.

[0117] In some embodiments, the compound of Formula I has the

IB.

[0118] In some embodiments, the compound of Formula I has the

IC.

[0119] In some embodiments, the composition of matter is a salt. Such salts may be anhydrous or associated with one or more molecules of water as a hydrate. [0120] In some embodiments, the composition of matter is a prodrug. In some such embodiments, the composition of matter is a (CfC₆)alkyl ester such as a methyl, ethyl, propyl, butyl, pentyl, or hexyl ester. [0121] In one embodiment, the compound is any one of the Example compounds described herein. Therefore, in some embodiments, the compound is selected from any one or all of those listed below or is a salt thereof, a tautomer thereof, or a salt of the tautomer:

2-(3-chloro-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-3-phenyl-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-3-(thiophen-2-yl)-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(3-cyclopentenyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(3-cyclopentyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(3-cyclohexenyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(5-hydroxy-3-(3-isopropoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(5-hydroxy-3-(4-isopropoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(5-hydroxy-3-(2-isopropoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(methylthio)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(piperidin-l-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-2-methoxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine- 6-carboxamido)acetic acid; 2-(5-hydroxy-8-methyl-2-morpholino-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(trifluoromethyl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(pyrrolidin-l-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(2-methylpiperidin-l-yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(3,4-dihydroquinolin-l(2H)-yl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; or

2-(8-hydroxy-5-methyl-6-oxo-3-phenyl-5,6-dihydropyrido[3,2-ό]pyrazine-7- carboxamido)acetic acid.

[0122] In one embodiment, the compound is any one of the Example compounds described herein. Therefore, in some embodiments, the compound is selected from any one or all of those listed below or is a salt thereof, a tautomer thereof, or a salt of the tautomer:

2-(5-hydroxy-3-(3-isopropoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid; 2-(5-hydroxy-3-(4-isopropoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid; or

2-(5-hydroxy-3-(2-isopropoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid.

[0123] In other embodiments, the compound is selected from any one or all of those listed below or is a salt thereof, a tautomer thereof, or a salt of the tautomer:

2-(5-hydroxy-2-methoxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-

6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-morpholino-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(2-rnethylpiperidin- 1 -yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; or

2-(2-(3,4-dihydroquinolin-l(2H)-yl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid.

[0124] In yet another embodiment, the compound is selected from the following compound or is a salt thereof, a tautomer thereof, or a salt of the tautomer:

[0125] In yet other embodiments, the compound is selected from any one or all of those listed below or is a salt thereof, a tautomer thereof, or a salt of the tautomer: 2-(5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-3-(pyridin-3-yl)-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-3-(thiophen-3-yl)-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid;

4-(6-((carboxymethyl)carbamoyl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazin-3-yl)benzoic acid;

2-(8-benzyl-3-chloro-5-hydroxy-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid;

2-(8-benzyl-5-hydroxy-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid;

6-((carboxymethyl)carbamoyl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido [2,3 -c] pyridazine-3 -carboxylic acid;

2-(2-cyano-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetic acid;

6-((carboxymethyl)carbamoyl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-2-carboxylic acid;

2-(5-hydroxy-2-(isoindolin-2-yl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(benzyloxy)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(8-benzyl-5-hydroxy-7-oxo-2-(trifluoromethyl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(4-phenylpiperazin-l-yl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-3-methoxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid; or

2-(5-hydroxy-8-methyl-7-oxo-3-(piperidin-l-yl)-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid. [0126] In other embodiments, the compound is selected from any one or all of those listed below or is a salt thereof, a tautomer thereof, or a salt of the tautomer:

2-(2-(2-ethylpiperidin-l-yl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(5-ethyl-2-methylpiperidin-l-yl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxarnido)acetic acid;

2-(5-hydroxy-8-methyl-2-(octahydroquinolin-l(2H)-yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(3-fluorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(2-cyclopropylethynyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-cyclopropyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-phenyl-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetic acid;

2-(2-(2-fluorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(4-fluorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(2-morpholinophenyl)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(4-morpholinophenyl)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(furan-3-yl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-2-(2-methoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(4-(piperidin-l-yl)phenyl)-7,8- dihydropyrido [2 ,3 -d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-2-(4-methoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-2-(3-methoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(quinolin-5-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(benzo [b]thiophen-2-yl)-5 -hydroxy- 8-methyl-7-oxo-7, 8-dihydropyrido [2,3 - d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-m-tolyl-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetic acid;

2-(2-(furan-2-yl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(4-chlorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d] pyrimidine-6-carboxamido)acetic acid;

2-(2-(benzo[b]thiophen-3-yl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(naphthalen-2-yl)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-2-(lH-indol-2-yl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(3-chlorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(l-methyl-lH-indol-5-yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(quinolin-4-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(naphthalen-l-yl)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-p-tolyl-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetic acid; 2-(2-(benzofuran-5-yl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(quinolin-3-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-o-tolyl-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetic acid;

2-(2-(benzo[b]thiophen-5-yl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(4-cyanophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(3-morpholinophenyl)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(thiophen-3-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(pyridin-3-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-2-(lH-indol-4-yl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-8-methyl-2-(l -methyl- lH-indol-2-yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; or 2-(5-hydroxy-8-methyl-7-oxo-2-(l-tosyl-lH-indol-3-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid.

[0127] Compounds of the present disclosure can contain one or more chiral centers. Such compounds can be prepared or isolated as pure stereoisomers, i.e., as individual enantiomers or diastereomers, or as stereoisomer-enriched mixtures. All such stereoisomers, and enriched mixtures thereof, are included within the scope of the present disclosure. Pure stereoisomers, and enriched mixtures thereof, can be prepared using, for example, optically active starting materials or stereoselective reagents well- known in the art. Alternatively, racemic mixtures of such compounds can be separated using, for example, chiral column chromatography, chiral resolving agents and the like.

[0128] Also provided herein are pharmaceutical formulations that include at least one pharmaceutically acceptable carrier, excipient, or diluent, and a therapeutically effective amount of the composition of matter any of the embodiments described herein. In such embodiments, the composition of matter is present in an amount effective for the treatment of at least one disease selected from ischemia, anemia, wound healing, auto-transplantation, allotransplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

[0129] Further provided are pharmaceutical formulations that include at least one pharmaceutically acceptable carrier, and a therapeutically effective amount of the composition of matter of any of the embodiments described herein in combination with at least one additional compound such as an erythropoiesis stimulating agent or a chemotherapeutic agent. [0130] Additionally provided is a method of increasing or stabilizing

HIF levels or activity in a subject by administering to the subject the composition of matter of any of the embodiments described herein. [0131] Further provided is a method of treating a condition where it is desired to modulate HIF activity comprising administering to a subject the composition of matter of any of the embodiments described herein. In some such embodiments, the condition is selected from at least one of ischemia, anemia, wound healing, auto- transplantation, allo- transplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

[0132] Also provided is a method of treating a hypoxic or ischemic related disorder in a subject comprising administering to a subject the composition of matter of any of the embodiments described herein. [0133] Also provided is a method of treating anemia in a subject comprising administering to a subject the composition of matter of any of the embodiments described herein. [0134] The compounds of the invention may also be used to prepare medicaments or in methods for stimulating erythropoiesis in a subject. Such methods and medicaments utilize a compound of any of the embodiments of the invention. In such methods, a compound of any of the embodiments is typically administered to a subject such as a human subject in a therapeutically effective amount.

[0135] Further provided is a method of modulating the amount of HIF in a cell comprising contacting the cell with the composition of matter of any of the embodiments described herein.

[0136] Additionally provided is a method of increasing the amount of hemoglobin F in a subject comprising administering to the subject the composition of matter of any of the embodiments described herein.

[0137] Also provided is a method of modulating angiogenesis in a subject comprising administering to the subject the composition of matter of any of the embodiments described herein.

[0138] Additionally provided is a method of treating at least one disease in a patient in need of such treatment comprising administering to the patient a therapeutically effective amount of the composition of matter of any of the embodiments described herein. In some such embodiments, the at least one disease is selected from ischemia, anemia, wound healing, auto- transplantation, allo- transplantation, xeno-transplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

[0139] Also provided is a method of inhibiting HIF hydroxylation in a subject comprising administering to the subject the composition of matter of any of the embodiments described herein.

[0140] In some embodiments, the HIF PHD inhibitory activity IC₅₀ value of the composition of matter is 40 μM or less. In other embodiments, the HIF

PHD inhibitory activity IC₅₀ value of the composition of matter is 10 μM or less. In still other embodiments, the HIF PHD inhibitory activity IC₅₀ value of the composition of matter is 100 nM or less, whereas in others it is 10 nM or less. [0141] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a pharmaceutical formulation or medicament.

[0142] In some such embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for increasing or stabilizing HIF levels or activity in a subject.

[0143] In some such embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for treating a condition where it is desired to modulate HIF activity. In some such embodiments, the condition is selected from at least one of ischemia, anemia, wound healing, auto- transplantation, allo- transplantation, xeno-transplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

[0144] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for treating a hypoxic or ischemic related disorder in a subject.

[0145] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for modulating the amount if HIF in a cell. In some embodiments, the composition of matter according to any of the embodiments is used to modulate the amount of HIF in a cell.

[0146] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for modulating angiogenesis in a subject.

[0147] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for inhibiting HIF hydroxylation in a subject.

[0148] In some embodiments, the composition of matter of any of the embodiments is used in the preparation of a medicament for treating anemia. [0149] In some embodiments, the composition of matter of any of the embodiments is used in a method for increasing the level of erythropoietin in the blood of a subject.

[0150] The phrase "composition of matter" as used herein is intended to encompass the compounds of the invention, pharmaceutically acceptable salts thereof, tautomers thereof, and pharmaceutically acceptable salts of the tautomer. It may also includes solvates, chelates, non-covalent complexes, prodrugs and mixtures of these in addition to a product comprising the specified ingredients (and in the specified amounts, if indicated), as well as any product which results, directly or indirectly, from combination of the specified ingredients in the specified amounts. By "pharmaceutically acceptable" it is meant that the carrier, excipient, or diluent is compatible with the other ingredients of the formulation and is not deleterious to the recipient thereof. [0151] Composition formulation may improve one or more pharmacokinetic properties (e.g., oral bioavailability, membrane permeability) of a compound of the invention (herein referred to as the active ingredient). [0152] Composition formulation may improve one or more pharmacokinetic properties (e.g., oral bioavailability, membrane permeability) of a compound of the invention (herein referred to as the active ingredient). [0153] The pharmaceutical compositions for the administration of the compounds of this invention may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art. All methods include the step of bringing the active ingredient into association with the carrier which constitutes one or more accessory ingredients. In general, the pharmaceutical compositions are prepared by uniformly and intimately bringing the active ingredient into association with a liquid carrier or a finely divided solid carrier or both, and then, if necessary, shaping the product into the desired formulation. In the pharmaceutical composition, the active object compound is included in an amount sufficient to produce the desired effect upon the process or condition of diseases. [0154] The pharmaceutical compositions containing the active ingredient may be in a form suitable for oral use, for example, as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions. Such compositions may contain one or more agents selected from sweetening agents, flavoring agents, coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations. Tablets contain the active ingredient in admixture with other nontoxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets. These excipients may be, for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example, corn starch, or alginic acid; binding agents, for example starch, gelatin or acacia, and lubricating agents, for example magnesium stearate, stearic acid, or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl distearate may be employed. They may also be coated by the techniques described in U.S. Patent Nos. 4,256,108, 4,160,452, and 4,265,874 to form osmotic therapeutic tablets for control release. [0155] Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example, calcium carbonate, calcium phosphate, or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example peanut oil, liquid paraffin, or olive oil.

[0156] Aqueous suspensions contain the active materials in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents, for example sodium carboxymethylcellulose, methylcellulose, hydroxy-propylmethylcellulose, sodium alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia; dispersing or wetting agents may be a naturally-occurring phosphatide, for example lecithin, or condensation products of an alkylene oxide with fatty acids, for example polyoxy-ethylene stearate, or condensation products of ethylene oxide with long chain aliphatic alcohols, for example heptadecaethyleneoxycetanol, or condensation products of ethylene oxide with partial esters derived from fatty acids and a hexitol such as polyoxyethylene sorbitol monooleate, or condensation products of ethylene oxide with partial esters derived from fatty acids and hexitol anhydrides, for example polyethylene sorbitan monooleate. The aqueous suspensions may also contain one or more preservatives, for example ethyl, or n-propyl, p- hydroxybenzoate, one or more coloring agents, one or more flavoring agents, and one or more sweetening agents, such as sucrose or saccharin. [0157] Oily suspensions may be formulated by suspending the active ingredient in a vegetable oil, for example arachis oil, olive oil, sesame oil, or coconut oil, or in a mineral oil such as liquid paraffin. The oily suspensions may contain a thickening agent, for example beeswax, hard paraffin, or cetyl alcohol. Sweetening agents such as those set forth above, and flavoring agents may be added to provide a palatable oral preparation. These compositions may be preserved by the addition of an anti-oxidant such as ascorbic acid. [0158] Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified by those already mentioned above. Additional excipients, for example sweetening, flavoring and coloring agents, may also be present. [0159] The pharmaceutical compositions of the invention may also be in the form of oil-in-water emulsions. The oily phase may be a vegetable oil, for example olive oil or arachis oil, or a mineral oil, for example liquid paraffin or mixtures of these. Suitable emulsifying agents may be naturally-occurring gums, for example gum acacia or gum tragacanth, naturally-occurring phosphatides, for example soy bean, lecithin, and esters or partial esters derived from fatty acids and hexitol anhydrides, for example sorbitan monooleate, and condensation products of the said partial esters with ethylene oxide, for example polyoxyethylene sorbitan monooleate. The emulsions may also contain sweetening and flavoring agents.

[0160] Syrups and elixirs may be formulated with sweetening agents, for example glycerol, propylene glycol, sorbitol or sucrose. Such formulations may also contain a demulcent, a preservative, and flavoring and coloring agents. [0161] The pharmaceutical compositions may be in the form of a sterile injectable aqueous or oleagenous suspension. This suspension may be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents which have been mentioned above. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally acceptable diluent or solvent, for example as a solution in 1,3-butane diol. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose, any bland fixed oil may be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid find use in the preparation of injectables.

[0162] The pharmaceutical compositions may also be administered in the form of suppositories for rectal administration of the drug. These compositions can be prepared by mixing the drug with a suitable non-irritating excipient which is solid at ordinary temperatures but liquid at the rectal temperature and will therefore melt in the rectum to release the drug. Such materials include, for example, cocoa butter and polyethylene glycols. [0163] For topical use, creams, ointments, jellies, solutions, or suspensions, etc., containing the compounds of the invention are employed. As used herein, topical application is also meant to include the use of mouthwashes and gargles.

[0164] The compounds of the invention can be prepared using the general synthetic route shown below in Scheme 1 and described more fully in the Examples. Scheme 1

[0165] The invention is further described by reference to the following examples, which are intended to exemplify the claimed invention but not to limit it in any way.

EXAMPLES

[0166] Unless otherwise stated, all compounds were obtained from commercial sources or were prepared using the methods and experimental procedures described herein. The following abbreviations are used to refer to various reagents and solvents:

AcOH Acetic Acid

ACN Acetonitrile

DCM Dichloromethane

DIPEA Diisopropylethylamine

DMA Dimethylacetamide

DMAP Dimethylaminopyridine

DMF N,N-Dimethylformamide

DMSO Dimethylsulfoxide

EtOAc Ethyl Acetate

EtOH Ethanol

MCPBA meta-Chloroperoxybenzoic acid

MeOH Methanol

TFA Trifluoroacetic acid THF Tetrahydrofuran

TR-FRET Time Resolved-Fluorescence Resonance Energy

Transfer

[0167] Method 1. Preparation of Sodium 3-Chloro-6-

(ethoxycarbony^-S-methyl-T-oxo-V^-dihydropyridoβ_jS-clpyridazin-S- olate.

[0168] (a) Ethyl 3,6-dichloropyridazine-4-carboxylate. To a solution of 3,6-dichloropyridazine-4-carboxylic acid (5.0 g, 26 mmol, commercially available from Aldrich, Milwaukee, WI) in THF (5.0 mL) and EtOH (5.0 mL, 26 mmol) was added DMAP (0.32 g, 2.6 mmol) and n-(3- dimethylaminopropyl)-n'-ethylcarbodiimide hydrochloride (5.0 g, 28 mmol). The reaction was stirred at room temperature for 12 hours. Solvent was removed under reduced pressure to afford an oil. The oil was partitioned between EtOAc and water, and the organic extracts were combined, dried over sodium sulfate, filtered, and concentrated to afford a yellow oil. The crude product was purified by silica gel flash chromatography (10% EtOAc/Hexane) to provide a colorless oil. MS (ESI) m/z: Calculated: 221.0; Observed: 221.0. ¹H NMR (400 MHz, CDCl₃) δ ppm 7.85 (s, 1 H), 4.48 (q, J= 7.24 Hz, 2 H), 1.44 (t, J=7.24 Hz, 3 H).

[0169] (b) Ethyl 6-chloro-3-(methylamino)pyridazine-4-carboxylate.

To a sealed tube was added ethyl 3,6-dichloropyridazine-4-carboxylate (2.0 g, 9 mmol), anhydrous K₂CO₃ (1.0 g, 10 mmol), and 2.0 M MeNH₂ in THF (6 mL, 12 mmol). The tube was sealed, the resulting yellow mixture was stirred at room temperature for 16 hours, and then the solids were collected by filtration and washed with EtOAc to afford a white solid. MS (ESI) m/z: Calculated: 215.6; Observed: 216.1. [0170] (c) Ethyl 6-chIoro-3-(3-ethoxy-N-methyl-3- oxopropanamido)pyridazine-4-carboxylate. To a mixture of ethyl 6-chloro- 3-(methylamino)pyridazine-4-carboxylate (1.6 g, 7.4 mmol) and anhydrous K₂CO₃ (1.3 g, 9.6 mmol) in THF (50.0 mL) was added dropwise propanoic acid, 3-chloro-3-oxo-, ethyl ester (1.1 mL, 8.9 mmol, commercially available from Aldrich, Milwaukee, WI). After stirring the reaction at room temperature for 16 hours, the solids were removed by filtration, and the filtrate was concentrated to afford a dark oil. The crude product was purified by silica gel flash chromatography (40% EtOAc/Hexane) to provide a yellow oil. MS (ESI) m/z: Calculated: 329.7; Observed: 330.0.

[0171] (d) Sodium 3-chloro-6-(ethoxycarbonyl)-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazin-5-olate. To an ice-cooled solution of EtOH (5.0 mL) were added small pieces of sodium metal (0.17 g, 7.3 mmol). The ice bath was removed and the mixture was stirred at room temperature until the sodium was no longer visible. The NaOEt solution was transferred dropwise to a solution of ethyl 6-chloro-3-(3-ethoxy-N-methyl-3- oxopropanamido)pyridazine-4-carboxylate (1.2 g, 3.6 mmol) in EtOH (3 mL). After the addition was complete, the mixture was stirred for an additional 2 minutes, and then the solids were collected by filtration and washed with ether. MS (ESI) m/z: Calculated: 283.7; Observed: 284.0. ¹H NMR (300 MHz, DMSO-d₆) δ ppm 7.84 (s, 1 H), 4.06 (q, J=7.16 Hz, 2 H), 3.54 (s, 3 H), 1.19 (t, J=7.16 Hz, 3 H).

[0172] Method 2. Preparation of 2-(5-Hydroxy-8-methyl-7-oxo-3- phenyl-7,8-dihydropyrido [2,3-c] pyridazine-6-carboxamido)acetic acid.

[0173] (a) Ethyl 5-hydroxy-8-methyl-7-oxo-3-phenyl-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxylate. In a sealed tube was combined sodium 3-chloro-6-(ethoxycarbonyl)-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazin-5-olate (0.50 g, 1.8 mmol), phenyl boronic acid (3.5 mmol, commercially available from Aldrich, Milwaukee, WI), Pd(PPh₃ )₄ (0.20 g, 0.18 mmol), 2.0 M aq. Na₂CO₃ (2.6 mL, 5.3 mmol), and 1,2- dimethoxyethane (10.0 mL, 1.8 mmol). The tube was flushed with argon, sealed, and then heated in an oil bath at 100⁰C for 16 hours. The crude reaction mixture was adsorbed onto silica and purified via flash chromatography (5% to 20% MeOH/CHCl₃).

[0174] (b) tert-Butyl 2-(5-hydroxy-8-methyl-7-oxo-3-phenyl-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetate. In a sealed tube was combined ethyl 5-hydroxy-8-methyl-7-oxo-3-substituted-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxylate (0.57 g, 1.8 mmol), tert-butyl 2- aminoacetate hydrochloride (0.29 g, 1.8 mmol), and N-ethyl-N- isopropylpropan-2-amine (0.31 mL, 1.8 mmol) in dioxane (5.0 mL). The tube was sealed and heated in an oil bath at 100°C for 12 hours. The crude reaction mixture was purified by flash chromatography (100% CHCl₃). [0175] (c) 2-(5-Hydroxy-8-methyl-7-oxo-3-phenyl-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetic acid. A solution of TFA (2 mL) and tert-butyl 2-(5-hydroxy-8-methyl-7-oxo-3-substituted-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetate was stirred at room temperature for 15 minutes and then concentrated under reduced pressure. Ether (5 mL) was added, and the resulting solid was collected by filtration, washed with water (3 x 5 mL) and then washed with ether (2 x 5 mL), and dried under vacuum at 5O⁰C. ¹H NMR (400 MHz, DMSOd₆) δ ppm 10.31 - 10.46 (1 H, m), 8.58 (1 H, s), 8.19 - 8.29 (2 H, m), 7.46 - 7.65 (3 H, m), 4.18 (2 H, d, J=5.5 Hz), 3.87 (3 H, s).

[0176] Method 3. Preparation of 2-(3-Chloro-5-hydroxy-8-methyl-7- oxo-7,8-dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetic acid.

[0177] (a) tert-Butyl 2-(3-chloro-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetate. To a solution of sodium 3-chloro-6-(ethoxycarbonyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazin-5-olate (7.0 g, 23 mmol), tert-butyl 2-aminoacetate hydrochloride (3.8 g, 23 mmol) in dioxane (80 mL) was added N-ethyl-N-isopropylpropan-2- amine (4.0 mL, 23 mmol). The flask was sealed and heated in an oil bath at 90°C for 12 hours. The reaction was filtered while still very warm, and the collected solids were washed with ether. The filtrate was concentrated to afford crude tert-butyl 2-(3-chloro-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetate.

[0178] (b) 2-(3-Chloro-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetic acid. tert-Butyl 2-(3- chloro-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetate (0.140 g, 0.358 mmol) was dissolved in TFA (2 mL) and stirred for 10 minutes. The reaction was concentrated under reduced pressure, and the resulting yellow solid was washed with water (3 x 20 mL) and then washed with ether (2 x 10 mL) and acetone (2 x 10 mL). MS (ESI) m/z: Calculated: 312.7; Observed (M⁺-I): 31 1.1. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 10.24 - 10.46 (m, 1 H), 8.37 (s, 1 H), 4.16 (d, J=5.67 Hz, 2 H), 3.77 (s, 3 H).

[0179] Method 4. Preparation of 2-(3-Cy clopentyl-5-hydroxy-8- methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridaziπe-6-carboxamido)acetic acid.

[0180] (a) tert-Butyl 2-(3-cyc-opentenyl-5-hydroxy-8-methyl-7-oxo-

7,8-dihydropyrido [2,3-c] pyridazine-6-carboxamido)acetate. This compound was prepared according to Method 2 using cycopentenyl boronic acid. [0181] (b) tert-Butyl 2-(3-cycIopentyl-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetate. To a solution of tert-butyl 2-(3-cyclopentenyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetate (0.33 g, 0.82 mmol) (in MeOH (20 mL) was added 10 mol % palladium/carbon. The reaction was flushed with hydrogen three times and then kept under balloon pressure while stirring for 72 hours. After filtering the reaction through celite and washing with DCM, the filtrate was concentrated. The crude mixture was adsorbed onto silica and purified via flash chromatography (2% MeOH/CHCl₃). [0182] (c) 2-(3-Cyclopentyl-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetic acid. tert-Butyl 2-(3- cyclopentyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetate (0.170 g, 0.42 mmol), was combined with silica (2.0 g) and toluene (30 mL) in a sealed tube and heated at 125⁰C for 3 hours. The reaction was cooled, 2.0 g of fresh silica was added, and the reaction was heated at 125°C for 12 hours. After cooling to room temperature, the reaction was filtered and the silica was washed with acetone. The filtrate was concentrated, and the crude reaction mixture was purified by flash chromatography to afford a brown solid. MS (ESI) m/z: Calculated: 346.3; Observed: 347.1. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 10.31 - 10.48 (1 H, m), 8.03 (1 H, s), 4.15 (2 H, d, J=4.9 Hz), 3.80 (3 H, s), 3.48 - 3.59 (1 H, m), 2.06 - 2.19 (2 H, m), 1.65 - 1.92 (6 H, m).

[0183] Table 1. The following table lists compounds which were prepared by the methods described above.

[0184] Method 5. Preparation of 2-(5-Hydroxy-8-methyl-7-oxo-2-

(trifluoromethyl)-7,8-dihydropyrido[2,3-d]pyriinidine-6- carboxamido)acetic acid.

[0185] (a) Ethyl 4-(methylamino)-2-(trifluoromethyl)pyrimidine-5- carboxylate. A mixture of ethyl 4-chloro-2-(trifluoromethyl)pyrimidine-5- carboxylate (1 g, 4 mmol, commercially available from Maybridge), K₂CO₃ (2 g, 12 mmol) and methylamine (2.0M solution in THF(20 mL)) was stirred at room temperature overnight. The reaction mixture was filtered through Celite and concentrated under reduced pressure to give the crude product as a light- peach colored solid. MS m/z: Calculated: 249.19; Observed; 250. [0186] (b) Ethyl 4-(3-ethoxy-N-methyl-3-oxopropanamido)-2-

(trifluoromethyl)pyrimidine-5-carboxylate. To a solution of ethyl 4- (methylamino)-2-(trifluoromethyl)pyrimidine-5-carboxylate (200 mg, 0.80mmol) in DCM (10 mL) were added ethyl malonoyl chloride (0.21 mL, 1.6 mmol) and a suspension of silver cyanide (0.027 mL, 0.8 mmol) in ACN (10 mL). Reaction was stirred at room temperature for 10 days. Another equivalent of AgCN and 1 mL of ethyl malonyl chloride was added, and the reaction was heated at reflux and stirred for 3 days. The solid was filtered off and the filtrate was concentrated to give an orange oil. The yield was approximately 48% as determined LCMS. The product was used in the next step without further purification.

[0187] (c) 5-Hydroxy-8-methyl-7-oxo-2-(trifluoromethyl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxylate. Ethyl 4-(3-ethoxy-N-methyl- 3-oxopropanamido)-2-(trifluoromethyl)pyrimidine-5-carboxylate (140 mg, 0.39 mmol) was diluted in EtOH (10 mL) and then treated with 20 wt% NaOEt (5 mL, 0.39 mmol) at room temperature for 15 minutes. A yellow precipitate was filtered and some solid was recovered but filtrate was cloudy. AcOH was added to the filtrate which was then concentrated under reduced pressure to give an oily solid. Ether was added, and the mixture washed with water and brine and then dried over MgSO₄ and concentrated under reduced pressure to give a yellow oil. The product was used in the next step without further purification. [0188] (d) tert-Butyl 2-(5-hydroxy-8-methyl-7-oxo-2-

(trifluoromethyl)-7,8-dihydropyrido [2,3-d] pyrimidine-6- carboxamido)acetate. A mixture of ethyl 5-hydroxy-8-methyl-7-oxo-2- (trifluoromethyl)-7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylate (140 mg, 0.44 mmol), glycine, 1 , 1 -dimethylethyl ester, DIPEA (0.23 mL, 1.3 mmol) and 1,4-dioxane (10 m) was stirred at 100°C for 4 hours. The mixture was then concentrated under reduced pressure to give a yellow oil. The oil was purified by silica flash chromatography (0-30%EtOAc:Hex) to give a crystalline solid. The solid was washed with ether and decanted to give an initial solid, 34 mg. The filtrate was concentrated under reduced pressure to a yellow solid which was washed with hexane and filtered to give additional solid. Combined yield = 81 mg (46%). MS m/z: Calculated: 402.33; Observed: 403. [0189] (e) 2-(5-Hydroxy-8-methyI-7-oxo-2-(trifluoromethyl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid. A solution of tert-butyl 2-(5-hydroxy-8-methyl-7-oxo-2-(trifluoromethyl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate (81 mg, 0.2 mmol) and TFA (3 mL) was stirred at room temperature for 15 minutes. The mixture was concentrated under reduced pressure to give a white solid. The solid was dried under high vacuum to constant weight to give the title compound, 80 mg (86%). MS m/z: Calculated: 346.22; Observed: 347.

[0190] Method 6. Preparation of tert-Butyl 2-(5-hydroxy-8-methyl-

2-(methylsulfonyl)-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetate.

[0191] (a) Methyl 5-hydroxy-8-methyl-2-(methylthio)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxylate. The title compound was prepared as described in Method 5(a)-5(c) using ethyl 4-chloro-2- (methylthio)pyrimidine-5-carboxylate as the starting material. [0192] (b) tert-Butyl 2-(5-hydroxy-8-methyl-2-(methylthio)-7-oxo-

7,8-dihydropyrido[2,3-d']pyrimidine-6-carboxamido)acetate. A solution of methyl 5-hydroxy-8-methyl-2-(methylthio)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxylate (3 g), glycine tert-butyl ester hydrochloride (3.6 g), DIPEA (6 mL), and 1,4-dioxane (100 mL) was heated to 100°C. After 2 hours, the reaction was concentrated in vacuo and washed with EtOAc. Added water and filtered off undissolved solid to give the title compound (2.3 g). MS m/z: Calculated: 380.42; Observed: 381.

[0193] (c) tert-Butyl 2-(5-hydroxy-8-methyl-2-(methylsulfonyl)-7- oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate. To a solution of tert-butyl 2-(5-hydroxy-8-methyl-2-(methylthio)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate (1 g, 3 mmol) and DCM (50 mL) was added MCPBA (1.3 g, 8 mmol). The reaction was then stirred at room temperature. After 1 hour, the starting material had disappeared and the sulphone and sulfoxide products were observed by LCMS. After 2 more hours, 1 g of MCPBA was added. After another hour, the reaction was determined to be complete by LCMS. The mixture was concentrated under reduced pressure and washed with MeOH and filtered through Celite. The white solid on the Celite was determined to be the product by ¹H NMR. The produce was dissolved in DCM and concentrated under reduced pressure. The resulting solid was dissolved in 3:1 EtOAc/DCM and washed with water and brine, and then dried with MgSO₄ and concentrated under reduced pressure to give 1 g of a white solid MS m/z: Calculated: 412.42; Observed: 413. [0194] Method 7. Preparation of 2-(5-Hydroxy-8-methyl-7-oxo-2-

(piperidin-l-ylJ-TjS-dihydropyridoP^-dlpyrimidine-β-carboxamidoJacetic acid.

[0195] (a) tert-Butyl 2-(5-hydroxy-8-methyl-7-oxo-2-(piperidin-l-yl)-

7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate. A solution of tert-butyl 2-(5-hydroxy-8-methyl-2-(methylsulfonyl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate (100 mg, 0.24 mmol) and THF (5 mL) was treated with piperidine (0.1 mL, 1.2 mmol) and heated to 180°C in a microwave (Biotage) for 10 minutes. The reaction mixture was then concentrated under vacuum and the solid was washed with ether. The white solid was then collected by filtration. The product was used in the next step without further purification.

[0196] (b) 2-(5-Hydroxy-8-methyl-7-oxo-2-(piperidin-l-yl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid. A solution of tert-butyl 2-(5-hydroxy-8-methyl-7-oxo-2-(piperidin-l-yl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxarnido)acetate (101 mg, 0.24 mmol) and TFA (19 μl, 0.24 mmol) was stirred at room temperature. After 30 minutes, the reaction was determined to be complete by LCMS. The reaction was concentrated under reduced pressure to give a yellow oil. Water was added to the residue and a white precipitate formed. The solid was filtered and washed with water. The solid was dried under high-vacuum to give the title compound as a white solid (25 mg). MS m/z: Calculated: 361.35; Observed: 362. ¹H NMR (300 MHz, DMSOd₆) δ ppm 12.90 (1 H, br. s.), 9.97 - 10.32 (1 H, m), 8.88 (1 H, s), 4.03 - 4.13 (2 H, m), 3.91 (4 H, s), 3.49 (3 H, s), 1.47 - 1.76 (6 H, m). [0197] Method 8. Preparation of 2-(5-Hydroxy-2-methoxy-8-methyl-

7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid.

[0198] (a) tert-Buty 1 2-(5-hy droxy-2-methoxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate. To a mixture of tert-butyl 2-(5-hydroxy-8-methyl-2-(methylsulfonyl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate (141 mg, 0.34 mmol) and THF (10 mL) was added ammonia, 2.0M methyl alcohol (3 mL, 5.1 mmol) at 0°C under N₂. The mixture was then stirred at 0°C and warmed to room temperature overnight. LCMS showed no starting material was left and two peaks corresponding to the 7-amino and to the 7-OMe product (ca. 1 :1). The white solid was filtered off and discarded. The filtrate was concentrated under reduced pressure to give the title compound.MS m/z: Calculated: 364.35; Observed: 365.

[0199] (b) 2-(5-Hydroxy-2-methoxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid. A solution of tert-butyl 2-(5-hydroxy-2-methoxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetate (100 mg, 0.27 mmol) and TFA (3 mL) was stirred at room temperature. After 30 minutes, the reaction was determined to be complete by LCMS. The reaction was concentrated under reduced pressure to give a yellow oil. Water was added, and a white precipitate formed. The solid was filtered, washed with water, and then washed with hexane. The product was then dried under high vacuum to provide 50 mg of the produce as an off-white solid (59%). MS m/z: Calculated: 308.25; Observed: 309. [0200] Table 2. The following table lists compounds which were prepared by the methods described above.

[0201] Method 9. Preparation of 2-(8-Hydroxy-5-methyl-6-oxo-3- phenyl-5,6-dihydropyrido[3,2-A]pyrazine-7-carboxamido)acetic acid.

[0202] (a) Methyl 3-aminopyrazine-2-carboxylate 4-oxide. A solution of methyl 3-amino-2-pyrazinecarboxylate (2962 mg, 19.3 mmol) in CHCl₃ (32 mL) was treated with MCPBA (4450 mg, 19.3 mmol). After all the solids had dissolved (5 minutes), the reaction was heated to 70°C. The reaction was removed from the oil bath after 1 hour and chilled in an ice-water bath. The reaction was stored at -20 °C overnight. The precipitate was collected by filtration, washed with diethyl ether (2 x 30 mL) and dried under vacuum, affording 2857 mg (87%) of methyl 3-aminopyrazine-2-carboxylate 4-oxide as a yellow solid. Mass: Calculated: 169.138; Observed: 170.1 (M+H)⁺. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.41 (1 H, d, J=3.5 Hz), 7.85 (1 H, d, J=3.5 Hz), 3.88 (3 H, s).

[0203] (b) Methyl S-amino-S-chloropyrazine-Z-carboxylate. A suspension of methyl 3-aminopyrazine-2-carboxylate 4-oxide (2845 mg, 16.8 mmol) in DMF (25 mL) was treated with phosphorous oxychloride (7839 μl, 84.1 mmol). The reaction was heated at 80°C for 15 minutes. The reaction mixture was poured into an ice-water mixture (200 mL) and allowed to stand at 23⁰C. After 18 hours, the precipitated solid was collected by filtration, washed with water (200 mL) and dried under vacuum, affording 1493 mg (47%) of methyl 3-amino-5-chloropyrazine-2-carboxylate as an off-white solid. Mass: Calculated: 187.584; Observed: 188.0 (M+H)⁺ ; ¹H NMR (400 MHz, MeOH-cL,) δ ppm 7.83 (1 H, s), 3.91 - 3.95 (3 H, m).

[0204] (c) Methyl S-amino-S-phenylpyrazine-Z-carboxylate. Methyl

3-amino-5-chloropyrazine-2-carboxylate (307 mg, 1637 μmol), phenylboronic acid (399 mg, 3273 μmol), tri-t-butylphosphonium tetrafluoroborate (95.0 mg, 327 μmol) and tris(dibenzylideneacetone)dipalladium (0) (150 mg, 164 μmol) were added to an oven-dried round bottom flask, which was purged through vacuum-argon cycles (3x). Potassium fluoride (285 mg, 4910 μmol) was added under argon, followed by THF (5 mL), and the reaction was stirred at 45°C. After 4 hours, the reaction was cooled to 23 °C and was filtered through a silica gel plug. The silica gel was washed with a 10% MeOH/DCM solution (250 mL), and the combined filtrate was concentrated in vacuo and purified on silica gel (eluant: 1% MeOH/DCM) to afford 360 mg (96%) of methyl 3-amino-5- phenylpyrazine-2-carboxylate as a dark brown solid. Mass: Calulated: 229.235; Observed: 230.0 (M+H)⁺ ; ¹H NMR (400 MHz, CDCl₃) δ ppm 8.48 (1 H, s), 8.04 (2 H, dd, J=6.6, 2.8 Hz), 7.44 - 7.58 (3 H, m), 4.02 (3 H, s). [0205] (d) Methyl 3-(methylamino)-5-phenylpyrazine-2-carboxylate.

A solution of methyl 3-amino-5-phenylpyrazine-2-carboxylate (360 mg, 1570 μmol) in DCM (10 mL) was treated with DIPEA (547 μl, 3141 μmol) and trifluoroacetic anhydride (275 μl, 1963 μmol). The reaction stirred under nitrogen at 23°C. After 14 hours, the reaction was diluted with DCM (50 mL) and washed with water (50 mL) and brine (50 mL), dried over MgSOφ and concentrated in vacuo affording methyl 5-phenyl-3-(2,2,2- trifluoroacetamido)pyrazine-2-carboxylate as an orange solid, which was carried forward to the next reaction. A suspension of methyl 5-phenyl-3-(2,2,2- trifluoroacetamido)pyrazine-2-carboxylate (511 mg, 1571 μmol) and potassium carbonate (651 mg, 4713 μmol) in DMF (10 mL) was treated with iodomethane (196 μl, 3142 μmol). The reaction flask was capped with a septum and heated to 65°C. After 4 hours, the reaction was cooled to 23 °C, diluted with EtOAc (75 mL) and washed with water (50 mL) and brine (50 mL), dried over MgSOφ concentrated in vacuo and purified by silica gel chromatography (eluant: 5 - 25 % EtOAc/hexane), affording 221 mg (41%, 2 steps) of methyl 5-phenyl-3- (2,2,2-trifluoro-N-methylacetamido)pyrazine-2-carboxylate as an yellow solid. A solution of methyl 5-phenyl-3-(2,2,2-trifluoro-N-methylacetamido)pyrazine- 2-carboxylate (253 mg, 746 μmol) in MeOH (2 mL) and DCM (2 mL) was treated with sodium methoxide (0.5M solution in MeOH (2983 μl, 1491 μmol)). The reaction was stirred under nitrogen at 23°C. After 90 minutes, the reaction was diluted with brine (25 mL) and extracted with DCM (3 x 25 mL). The combined organic layers were dried (MgSO₄) and concentrated, affording 179 mg (99%) of methyl 3-(methylamino)-5-phenylpyrazine-2-carboxylate as a yellow solid. Mass: Calculated: 243.261 ; Observed: 244.0 (M+H)⁺ _; ¹H NMR (400 MHz, CDCl₃) δ ppm 8.37 (1 H, s), 8.07 - 8.17 (2 H, m), 7.95 (1 H, br. s.), 7.46 - 7.55 (3 H, m), 4.00 (3 H, s), 3.18 (3 H, d, J=4.7 Hz). [0206] (e) Methyl 3-(3-ethoxy-N-methyl-3-oxopropanamido)-5- phenylpyrazine-2-carboxylate. A suspension of methyl 3-(methylamino)-5- phenylpyrazine-2-carboxylate (178 mg, 732 μmol) and potassium carbonate (152 mg, 1098 μmol) in THF (5 mL) was cooled to 0⁰C under nitrogen and treated with ethyl malonoyl chloride (115 μl, 915 μmol) in a dropwise fashion. The reaction was slowly warmed to 23°C. After 19 hours, the reaction was diluted with EtOAc (50 mL) and washed with a saturated ammonium chloride solution (50 mL) and brine (50 mL), dried over MgSOφ and concentrated in vacuo affording 260 mg (99%) of methyl 3-(3-ethoxy-N-methyl-3- oxopropanamido)-5-phenylpyrazine-2-carboxylate as a yellow oil. Mass: Calculated: 357.361 ; Observed: 358.1 (M+H)⁺ [0207] (f) Ethyl 8-hydroxy-5-methyl-6-oxo-3-phenyl-5,6- dihydropyrido[3,2-Λ]pyrazine-7-carboxylate. A solution of methyl 3-(3- ethoxy-N-methyl-3-oxopropanamido)-5-phenylpyrazine-2-carboxylate (260 mg, 728 μmol) in EtOH (5 mL) was treated with freshly prepared sodium ethoxide, 1.0 M in EtOH (728 μl, 728 μmol). The reaction was stirred at 23°C under nitrogen. After 75 minutes, the reaction was filtered. The residue was washed with diethyl ether (25 mL) and dried under vacuum, affording 228 mg (96%) of ethyl 8-hydroxy-5-methyl-6-oxo-3-phenyl-5,6-dihydropyrido[3,2-6]pyrazine-7- carboxylate as an yellow solid. Mass: Calculated: 325.319; Observed: 326.0 (M+H)_, ¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.82 (1 H, s), 8.20 (2 H, d, J=7.0 Hz), 7.50 - 7.60 (3 H, m), 4.09 (2 H, q, J=6.8 Hz), 3.55 (3 H, s), 1.22 (3 H, t, J=6.9 Hz).

[0208] (g) tert-Butyϊ 2-(8-hydroxy-5-methyI-6-oxo-3-phenyl-5,6- dihydropyrido[3,2-Λ]pyrazine-7-carboxamido)acetate. A suspension of ethyl 8-hydroxy-5-methyl-6-oxo-3-phenyl-5,6-dihydropyrido[3,2-ό]pyrazine-7- carboxylate (222 mg, 682 μmol), glycine tert-butyl ester hydrochloride (126 mg, 751 μmol) and DIPEA (238 μl, 1365 μmol) in 1,4-dioxane (5 mL) was heated to 120°C in a sealed vessel. After 15 hours, the reaction was cooled to 23°C and filtered. The crude residue was washed with water (25 mL) and diethyl ether (5 mL), and dried under vacuum, affording 192 mg (69%) of tert-butyl 2-(8- hydroxy-5-methyl-6-oxo-3-phenyl-5,6-dihydropyrido[3,2-6]pyrazine-7- carboxamido)acetate as an yellow solid. Mass: Calculated: 410.423; Observed: 411.1 (M+H)⁺, ¹H NMR (400 MHz, DMSO-d₆) δ ppm 9.00 (1 H, s), 8.25 (2 H, d, J=6.5 Hz), 7.52 - 7.61 (3 H, m), 3.97 (2 H, d, J=I.8 Hz), 3.63 (3 H, s), 1.44 (9 H, s).

[0209] (h) 2-(8-Hydroxy-5-methyl-6-oxo-3-phenyl-5,6- dihydropyrido[3,2-b]pyrazine-7-carboxamido)acetic acid. A solution of tert- butyl 2-(8-hydroxy-5-methyl-6-oxo-3-phenyl-5,6-dihydropyrido[3,2-6]pyrazine- 7-carboxamido)acetate (185 mg, 451 μmol) in TFA (2 mL) was stirred at 23°C. After 30 minutes, the reaction was concentrated in vacuo and diluted with water (20 mL). The precipitated solids were collected by filtration, washed with diethyl ether (10 mL) and dried under vacuum, affording 151 mg (94%) of 2- (8-hydroxy-5 -methyl-6-oxo-3 -phenyl-5,6-dihydropyrido [3 ,2-ό]pyrazine-7- carboxamido)acetic acid as an yellow solid. Mass: Calculated: 354.317; Observed: 355.0 (M+H)⁺ ; ¹H NMR (400 MHz, DMSOd₆) δ ppm 10.34 - 10.53 (1 H, m), 9.35 (1 H, s), 8.33 - 8.40 (2 H, m), 7.58 - 7.67 (3 H, m), 4.12 - 4.20 (2 H, m), 3.77 (3 H, s).

[0210] Method 10. Preparation of tert-Butyl 2-(2-chloro-5-hydroxy-

8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetate.

[0211 ] (a) tert-Butyl 2-(5-hydroxy-8-methyl-2-(methylthio)-7-oxo-

7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate. A solution of methyl 5-hydroxy-8-methyl-2-(methylthio)-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxylate (7.5 g, 27 mmol, Method 6a), glycine t-butyl ester (3.5 g, 27 mmol), DIPEA (9.2 mL, 2 54 mmol) in dry dioxane (300 mL) was heated at 100°C overnight. In order to bring the reaction to completion, 1 equivalent each of glycine /-butyl ester and DIPEA were added after 16 hours. The mixture was then heated for a further 3 hours at 100°C. The solvent was then removed, and the residue was partitioned between CH₂Cl₂ and water. The water phase was extracted three times with CH₂Cl₂, washed with brine, dried over Na₂SO₄ and the solvent removed on the evaporator to obtain the product (9.83 g, 96%) as a yellow-brown solid that was used in the next step without purification. Ci₆H₂₀N₄O₅S (380.4). HPLC (gradient I) R₁ = 3.47 (94). APCI- MS: 381 ([M+H]⁺). ¹H-NMR (DMSO-d₆): δ 10.16 (br s, IH), 9.06 (s, IH), 4.10 (d, J = 5.7, 2H), 3.57 (s, 3H), 2.64 (s, 3H), 1.45 (s, 9H). [0212] (b) tert-Butyl 2-(5-hydroxy-8-methyl-2-(methylsulfonyl)-7- oxo-7,8-dihydropyrido [2,3-d] pyrimidine-6-carboxamido)acetate. To a solution of tert-butyl 2-(5-hydroxy-8-methyl-2-(methylthio)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate (15.7 g, 41.4 mmol) in dry CH₂Cl₂ (600 mL) was added mCPBA (30.6 g, 124 mmol) at 0⁰C. The mixture was stirred at room temperature for 40 minutes. To the reaction mixture, was added an aqueous NaHCO₃ solution,and the water phase was extracted three times with CH₂Cl₂, washed with Na₂S₂O₃, NaHCO₃, brine, dried over Na₂SO₄ and the solvent removed on the evaporator to obtain the product (14.6 g, 86 %) as a light brown solid. C₆H₂₀N₄O₇S (412.4). APCI-MS: 413 ([M+H]⁺), 325 ([M-(t-Bu)+H]⁺). ¹H-NMR (DMSO-d₆): δ 10.16 (br s, IH), 9.49 (s, IH), 4.13 (d, J = 5.8, 2H), 3.66 (s, 3H), 3.51 (s, 3H), 1.45 (s, 9H). [0213] (c) tert-Butyl 2-(2-amino-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate. Ammonia (0.5 M in dioxane, IL, 500 mmol) was added to tert-butyl 2-(5-hydroxy-8-methyl-2- (methylsulfonyl)-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetate (14.6 g, 35 mmol) at O⁰C. The mixture was stirred at room temperature for 1 hour, and then the white solid was filtered off and washed with dioxane and ether. The the product was obtained (H g, 90%) as a white powder. C₅Hi₉N₅O₅ (349.3). APCI-MS: 350 ([M+H]⁺), 294 ([M-(t-Bu)+H]⁺). ¹H-NMR (DMSO-d₆): δ 10.16 (t, J = 5.6, IH), 8.82 (s, IH), 7.71 (s, 2H), 4.05 (d, J = 5.6, 2H), 3.48 (s, 3H), 1.44 (s, 9H).

[0214] (d) tert-Butyl 2-(2-chloro-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido [2,3-d] pyrimidine-6-carboxamido)acetate. To a mixture of tert-butyl 2-(2-amino-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetate (10 g, 26 mmol) in dichloroethane (1.5 1) was added chlorotrimethylsilane (22 ml, 172 mmol). The mixture was stirred 5 minutes at O⁰C and then for 15 minutes at room temperature. The mixture was again cooled to O⁰C and t-butyl-nitrite (24.2 ml, 179 mmol) was added. The resulting solution was stirred at 70°C for 1.5 hours. The reaction was not complete so a second portion of the two reagents were added again following the same procedure as before. After stirring the mixture at 70°C for an additional 1.5 hours, the mixture was cooled to room temperature and quenched with a saturated NaHCO₃ solution. The phases were separated and extracted with more CH₂Cl₂. The combined organic phases were washed with water and brine, dried over Na₂SO₄ and concentrated to yield the product (4.8 g, 44%) as a yellow solid. Ci₅H₁₇ClN₄O₅ (368.8). HPLC (gradient E) R_x = 4.39 (82). APCI- MS: 369 ([M+H]⁺). ¹H-NMR (DMSO-d₆): δ 10.1 1 (br s, IH), 9.20 (s, IH), 4.10 (d, J = 5.8, 2H), 3.56 (s, 3H), 1.43 (s, 9H).

[0215] Method 11. Preparation of 2-(2-(3-Fluorophenyl)-5-hydroxy-

8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid.

[0216] (a) tert-Butyl 2-(2-(3-fluorophenyl)-5-hydroxy-8-methyl-7- oxo-7,8-dihydropyrido [2,3-d] pyrimidine-6-carboxamido)acetate. To a mixture of tert-butyl 2-(2-chloro-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate (lOOmg, 1 eq., Method 10), Pd(dppf)Cl₂ (0.05 eq.), 3-fluorophenylboronic acid (3.0 eq., available from Aldrich (Milwaukee, WI)) in degassed dioxane (4 mL) was added degassed aqueous Na₂CO₃ (2M, 3eq.) in a sealed tube. The mixture was stirred overnight at 80°C. The mixture was then cooled to room temperature and diluted with water. The phases were separated and extracted with more CH₂Cl₂. The combined organic phases were washed with water and brine, dried over Na₂SO₄ and concentrated. The residue was dissolved in DMA and purified on reversed phase HPLC to give the title compound (48 mg, 41%) as as a light brown solid. C_2IH₂₁FN₄O₅ (428.4). APCI-MS: 429 ([M+H]⁺), 373 ([M-(t-Bu)+H]⁺). ¹H- NMR (DMSO-d₆): δ 10.21 (br s, IH), 9.39 (s, IH), 8.40 (d, J = 7.8, IH), 8.25 (d, J = 9.3, IH), 7.66 (q, J = 8.1, IH), 7.49 (dt, J = 8.5, 2.5, IH), 4.13 (d, J = 5.7, 2H), 3.55 (s, 3H), 1.46 (s, 9H).

[0217] (b) 2-(2-(3-FluorophenyI)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid. tert-Butyl 2-(2- (3-fluorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetate (41 mg, 0.096 mmol) was dissolved in CH₂Cl₂ (1 mL) and cooled to 0°C. Trifluoroacetic acid (1 mL) was added and the reaction was stirred at room temperature for 2 hours. The reaction mixture was concentrated, coevaporated with more CH₂Cl₂ and washed with Et₂O to afford the product (30 mg, 67%) as a brown solid. Ci₇Hi₃FN₄O₅ (372.3). HPLC (gradient E) R₁ = 4.37 (96). APCI-MS: 373 ([M+H]⁺). ¹H-NMR (DMSO-d₆): δ 10.21 (br s, IH), 9.40 (s, IH), 8.40 (d, J = 7.7, IH), 8.23 (d, J = 9.3, IH), 7.66 (q, J = 8.0, IH), 7.50 (dt, J = 8.6, 2.6, IH), 4.16 (d, J = 5.6, 2H), 3.75 (s, 3H).

[0218] Method 12. Preparation of 2-(2-Cy clopropyl-5-hydroxy-8- methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid.

[0219] (a) tert-Butyl 2-(2-cyclopropyl-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate. A mixture of tert- butyl 2-(2-chloro-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetate (80 mg, 0.22 mmol, Method 10), cyclopropylboronic acid (186 mg, 2 mmol, available from Aldrich (Milwaukee, WI)), Pd(OAc)₂ (2 mg, 0.01 mol), tricyclohexylphosphine (6 mg, 0.02 mmol), potassium phosphate (161 mg, 0.79 mmol) in degassed toluene (2 mL) and water (0.1 mL) in a sealed tube was stirred overnight at 110°C. The mixture was then cooled to room temperature and diluted with water. The phases were separated and extracted with more CH₂Cl₂. The combined organic phases were then washed with water and brine, dried over Na₂SO₄ and concentrated. The residue was dissolved in DMA and purified on reverse phase HPLC to afford the product (10 mg, 13%) as a brown solid. Ci₈H₂₂N₄O₅ (374.4). HPLC (gradient J) R₁ = 1.51 (96). APCI-MS: 375 ([M+H]⁺), 319 ([M-(r-Bu)+H]⁺). [0220] (b) 2-(2-Cyclopropyl-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid. tert-Butyl 2-(2- cyclopropyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetate (10 mg, 0.027 mmol) was dissolved in CH₂Cl₂ (0.5 mL) and cooled to 0°C. Trifluoroacetic acid (0.5 mL) was added, and the reaction was stirred at room temperature for 2 hours. The reaction mixture was concentrated, coevaporated with more CH₂Cl₂ and washed with CH₂Cl₂ to afford the product (4.3 mg, 34%) as a brown solid. Ci₄Hi₄N₄O₅ (318.3). HPLC (gradient E) R₁ = 2.00 (88). APCI-MS: 319 ([M+H]⁺). ¹H-NMR (DMSO-d₆): δ 10.22 (br s, IH), 9.14 (s, IH), 4.13 (d, J = 5.6, 2H), 3.60 (s, 3H), 1.20-1.16 (m, 4H).

[0221] Method 13. Preparation of 2-(2-(2-CyclopropylethynyI)-5- hydroxy-8-methyl-7-oxo-7,8-dihydropyrido [2,3-d] py rimidine-6- carboxamido)acetic acid.

[0222] (a) tert-Butyl 2-(2-(2-cycIopropylethynyl)-5-hydroxy-8- methyI-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate.

A mixture of tert-butyl 2-(2-chloro-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate (80 mg, 0.22 mmol, Method 10), ethynylcyclopropane (70% in toluene, 92 mg, 1.1 mmol, available from Aldrich (Milwaukee, WI)), Pd(PPh₃)₂Cl₂ (16 mg, 0.02 mol), PPh₃ (12 mg, 0.04 mmol), CuI (8 mg, 0.04 mmol), Et₃N (0.44 mmol) in DMF (1.5 mL) in a tube was stirred 20 minutes at 120°C in a microwave. The mixture was then cooled to room temperature, and diluted with water. The phases were separated and extracted with more CH₂Cl₂. The combined organic phases were washed with water and brine, dried over Na₂SO₄ and concentrated. The residue was dissolved in DMA and purified on reverse phase HPLC to afford the product (20 mg, 23%) as a light brown solid. C₂₀H₂₂N₄O₅ (398.4). APCI-MS: 399 ([M₊H]⁺).

[0223] (b) 2-(2-(2-Cyclopropylethynyl)-5-hydroxy-8-methyl-7-oxo-

7,8-dihydropyrido [2,3-d] pyrimidine-6-carboxamido)acetic acid. tert-Butyl 2-(2-(2-cyclopropylethynyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetate was dissolved in CH₂Cl₂ (0.5 mL) and cooled to 0°C. Trifluoroacetic acid (0.5 mL) was added, and the reaction was stirred at room temperature for 2 hours. The reaction mixture was concentrated, coevaporated with more CH₂Cl₂ and washed with CH₂Cl₂ to afford the product (4.7 mg, 20%) as a light brown solid. Ci₆Hi₄N₄O₅ (342.3). HPLC (gradient E) R₁ = 2 A3 (93). APCI-MS: 343 ([M₊H]⁺).

[0224] Table 3. The following table lists compounds which were prepared by the methods described above.

[0225] Method 14. Preparation of 6-((Carboxymethyl)carbamoyl)-5- hydroxy-S-methyl-T-oxo-T_jS-dihydropyridoβ_jS-clpyridazine-S-carboxylic acid.

[0226] (a) 6-((2-tert-Butoxy-2-oxoethyl)carbamoyl)-5-hydroxy-8- methyI-7-oxo-7,8-dihydropyrido [2,3-c] pyridazine-3-carboxyIic acid. The title compound is prepared by a palladium catalyzed carbonylation reaction of tert-butyl 2-(3-chloro-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetate according to the proecedure of Tsuji, J., Palladium Reagents and catalysts: Innovations in Organic Synthesis Publisher: (Wiley, Chichester, UK), 340-45 (1995).

[0227] (b) 6-((Carboxymethyl)carbamoyI)-5-hydroxy-8-methyl-7- oxo-7,8-dihydropyrido[2,3-c]pyridazine-3-carboxylic acid. The title compound is prepared by acidic deprotection of 6-((2-tert-butoxy-2- oxoethyl)carbamoyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-3-carboxylic acid using TFA according to the procedure described in Method 3(b).

[0228] Method 15. Preparation of 2-(2-cyano-5-hydroxy-8-methyl-

7-oxo-7,8-dihydropy rido [2,3-d] pyrimidine-6-carboxamido)acetic acid.

[0229] (a) tert-Butyl 2-(2-cyano-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetate. The title compound is prepared by reaction of tert-butyl 2-(5-hydroxy-8-methyl-2- (methylsulfonyl)-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetate with sodium cyanide according to the procedure described in Bioorg. Med. Chem. Lett., 17, 6206(2007).

[0230] (b) 2-(2-Cyano-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid. The title compound is prepared by acidic deprotection of tert-butyl 2-(2-cyano-5- hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-6- carboxamido)acetate according to the procedure describedin Method 3(b). [0231] Method 16. Preparation of 6-((carboxymethyl)carbamoyl)-5- hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-2-carboxylic acid. OH O

HO₂C^ΛN^ΛN^ΛO ^H °

[0232] (a) 6-((Carboxymethyl)carbamoyl)-5-hydroxy-8-methyl-7- oxo-7,8-dihydropyrido[2,3-d]pyrimidine-2-carboxylic acid. The title compound is prepared by acidic hydrolysis of the cyano group with accompanying deprotection of tert-butyl 2-(2-cyano-5-hydroxy-8-methyl-7-oxo- 7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxarnido)acetate according to the procedure described in J. Med. Chem., 50, 3229 (2007) and those described in Method 14(a).

[0233] Method 17. Preparation of 2-(5-hydroxy-3-methoxy-8- methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetic acid.

[0234] (a) Methyl 5-hydroxy-3-methoxy-8-methyI-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxylate. The title compound is prepared by reaction of methyl 3-chloro-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxylate with sodium methoxide according the the procedure described in Bioorg. Med. Chem. Lett., 17, 6206 (2007). Alternatively, the title compound is prepared by reaction of methyl 3- chloro-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxylate with ammonia in MeOH solution according to Method 8(a). [0235] (b) tert-Butyl 2-(5-hydroxy-3-methoxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetate. The title compound is prepared from methyl 5-hydroxy-3-methoxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxylate and tert-butyl 2-aminoacetate hydrochloride according to Method 3(a). [0236] (c) 2-(5-Hydroxy-3-methoxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetic acid. The title compound is prepared by deprotection of tert-butyl 2-(5-hydroxy-3-methoxy-8- methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetate using TFA according to Method 3(b).

[0237] Method 18. Preparation of 2-(5-Hydroxy-8-methyl-7-oxo-3-

(piperidin-l-yl)-7,8-dihydropyrido[2,3-c]pyridazine-6-carboxamido)acetic acid.

[0238] (a) Methyl 5-hydroxy-8-methyl-7-oxo-3-(piperidin-l-yl)-7,8- dihydropyrido [2,3-c] pyridazine-6-carboxylate. The title compound is prepared by reaction of methyl 3-chloro-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-6-carboxylate with piperidine according to literature procedures. Alternatively, the title compound is prepared by reaction of methyl 3-chloro-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxylate with piperidine according to Method 7(a).

[0239] (b) tert-Butyl 2-(5-hydroxy-8-methyl-7-oxo-3-(piperidin-l-yl)-

7,8-dihydropy rido [2,3-c] pyridazine-6-carboxamido)acetate. The title compound is prepared by reaction of methyl 5-hydroxy-8-methyl-7-oxo-3-

(piperidin-l-yl)-7,8-dihydropyrido[2,3-c]pyridazine-6-carboxylate and tert-butyl

2-aminoacetate hydrochloride according to Method 3 (a).

[0240] (c) 2-(5-Hydroxy-8-methyl-7-oxo-3-(piperidin-l-yl)-7,8- dihydropyrido [2,3-c] pyridazine-6-carboxamido)acetic acid. The title compound is deprotected by reaction of tert-butyl 2-(5-hydroxy-8-methyl-7- oxo-3-(piperidin-l-yl)-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetate using TFA according to Method 3(b).

[0241] Table 4. The following table lists compounds which are prepared by the methods described above.

[0242] The following are examples of methods that may be used to quantitate HIF PHD activity and the inhibition of HIF PHD activity by compounds of the present invention.

Expression, Purification and Europium Labeling of VCB and Design of an Eu- VCB based TR-FRET Assay for the Detection of Hydroxyprolyl HIF lα Peptides

[0243] The VCB complex is defined as the Von Hippel-Lindau protein

(pVHL), elongin B and elongin C heterotrimeric complex. VCB specifically binds to hydroxyproline residues of HIFl α, initiating polyubiquitinylation of HIF lα and its subsequent proteolytic destruction. In the absence of prolyl hydroxylase activity, VCB does not bind unmodified HIF lα. The VCB complex was expressed in E. coli and purified from the soluble fraction. The amino acid sequences of the three protein components are as follows:

VHL (Amino Acids 54-213)

MHHHHHHEAGRPRPVLRSVNSREPSQVIFCNRSPRVVLPVWLNFDGEPQP YPTLPPGTGRRIHSYRGHLWLFRDAGTHDGLLVNQTELFVPSLNVDGQPIF ANITLPVYTLKERCLQVVRSLVKPENYRRLDIVRSLYEDLEDHPNVQKDL ERLTQERIAHQRMGD (SEQ ID NO: 1)

ElonginB

MDVFLMIRRHKTTIFTDAKESSTVFELKRIVEGILKRPPDEQRLYKDDQLL DDGKTLGECGFTSQTARPQAP ATVGLAFRADDTFEALCIEPFSSPPELPDV MKPQDSGSSANEQAVQ* (SEQ ID NO: 2)

ElonginC (Amino Acids 17-1 12)

MYVKLISSDGHEFIVKREHALTSGTIKAMLSGPGQFAENETNEVNFREIPS HVLSKVCMYFTYKVRYTNSSTEIPEFPIAPEIALELLMAANFLDC (SEQ ID NO: 3) The N-terminus of VHL contains a six histidine affinity tag for purification purposes.

[0244] A VCB-based assay allows a highly sensitive and direct measurement of enzymatic product formation (HIF lα protein or fragments thereof containing a hydroxylated proline residue) and is suitable for high throughput screening.

[0245] For expression in E.coli, VHL 54-213 was cloned into pAMG21

(Plux promoter) between the Ndel-Xhol site. Immediately downstream of this is the ElonginC gene cloned into the Xhol site to SacII. There is a 13 bp spacer between the stop codon of VHL and the initiating codon of ElonginC. The expression plasmid pAMG21 is a 61 18 base pair plasmid that was derived from the expression vector pCFM1656 (ATCC #69576), which in turn can be derived from the expression vector system described in US Patent No. 4,710,473. This design allows for chemical rather than thermal induction of protein expression by substitution of the promoter region, replacing a synthetic bacteriophage lambda pi promoter with a DNA segment containing the LuxR gene and the LuxPR promoter, and affords regulation of expression by the plasmid-encoded LuxR protein, thereby allowing any E.coli strain to serve as host. [0246] ElonginB was cloned into pTA2 (pAC YC 184.1 based vector) under the control of a Lac promoter. Competent E. coli cells were transformed with the pAMG21 - VHL-ElonginC construct. These E.coli cells were rendered competent again prior to transformation with the pTA2-elonginB construct to produce the final E.coli strain containing both plasmid constructs. Induction of protein expression was initiated by the addition of IPTG and N-(3-oxo-hexanoyl)- homoserine lactone (HSL) at 30°C.

[0247] Bacterial cells were lysed by a microfluidizer in aqueous buffer of pH 8.0 and the soluble fraction was separated by centrifugation. The soluble E.coli fraction was subjected to Nickel-NTA chelating chromatography to utilize the six histidine affinity tag located on the pVHL construct. The pooled fractions from the nickel column were applied to a Superdex 200 size exclusion chromatography (SEC) column. The protein eluted as a monomer on SEC, indicating that the three protein components formed a complex in solution. The fractions from the SEC column were pooled and applied to a Q Sepharose anion exchange column for final purification. The purified complex was visualized by SDS-PAGE and the identities of the three protein components were confirmed by N-terminal amino acid sequencing.

[0248] Purified VCB was exchanged into 50 mM sodium carbonate buffer pH 9.2 and labeled with a europium chelate overnight. LANCE™ europium chelate (PerkinElmer, Inc; Eu-W1024 ITC chelate; catalog number is AD0013) was used to label the lysine residues of the VCB complex. The chelate contains an isothiocyanate reactive group that specifically labels proteins on lysine residues (there are fifteen lysine residues in the VCB protein complex). The resulting europylated VCB was purified by desalting columns and quantitated by standard means. The labeling yield was determined to be 6.6 europium groups per one VCB complex.

[0249] Two peptides were produced by SynPep, Inc.: a hydroxyproline modified peptide and an unmodified control peptide. VCB was expected to specifically bind to the hydroxyproline modified peptide (a mimic of enzymatic hydroxylation by prolyl hydroxylase). VCB was not expected to bind to the unmodified peptide. Both peptides were produced with a biotin group at the N- terminus to allow for binding by the streptavidin-labeled fluorescent acceptor allophycocyanin (streptavidin APC; Prozyme, Inc.).

[0250] The sequence of the custom synthesized HIF lα peptides (amino acids 556-575, with methionine residues replaced with alanine residues to prevent oxidation) were as follows:

(unmodified) Biotin-DLDLEALAPYIPADDDFQLR-CONH₂ (SEQ ID NO: 4) (modified) Biotin-DLDLEALA[hyP] YIPADDDFQLR-CONH₂ (SEQ ID NO: 5)

[0251] The peptides were purchased from SynPep as lyophilized solids and were suspended in DMSO for experimental use. The peptides were quantitated according to their absorbance at 280 nm. [0252] Experiments were conducted in 96 well Costar polystyrene plates.

Biotinylated peptides and europylated VCB were suspended in the following buffer: 100 niM HEPES 7.5, 0.1 M NaCl, 0.1% BSA and 0.05% Tween 20. The reagents were allowed to reach equilibrium by shaking for 1 hour before the plates were read on the Discovery Instrument (Packard). The data output is the ratio of the 665 nm and 620 nm emission signal resulting from the 320 nm excitation. [0253] As shown in Figure 1, the specific interaction of europylated VCB with the hydroxyproline modified HIF lα peptide coupled to streptavidin APC generated a fluorescence signal detectable over the background signal. These results demonstrate a fluorescence signal generated by the specific interaction of Eu-VCB with hyp-HIFlα peptide. Each bar represents the data from a single well of a 96 well assay plate. The signal to background ratio was calculated from data from a control plate (unmodified peptide). Eu-VCB concentration was titrated across rows (nM) and streptavidin APC concentrations were titrated down columns. The peptide concentration was fixed at 100 nM.

Detection of Enzvmatically Converted Hydroxyprolyl HIF- lα by HIF PHD2 and Inhibition of HIF PHD2 activity

[0254] Binding of the P564-HIF 1 α peptide to VCB was validated utilizing the homogeneous time-resolved FRET (TR-FRET^') technology. A 17 amino acid (17aa) peptide with an N-terminally labeled biotin molecule corresponding to amino acid sequences 558 to 574 of the HIF lα protein was synthesized in-house (DLEMLAPYIPMDDDFQL (SEQ ID NO: 6)). A second 17aa peptide containing a hydroxylated proline at position 564 was chemically generated to mimic the PHD enzyme converted product form of the protein that is recognized by VCB. The assay was performed in a final volume of 100 μL in buffer containing 50 mM Tris-HCl (pH 8), 100 mM NaCl, 0.05% heat inactivated FBS, 0.05% Tween-20, and 0.5% NaN₃. The optimal signal over background and the linear range of detection was determined by titrating the hydroxylated or unhydroxylated peptide at varied concentrations between 0 and 1 μM with a titration of VCB-Eu at varying concentrations between 0 and 50 nM with 50 nM of streptavidin APC. The binding reagents were allowed to reach equilibrium by shaking for 1 hour before it was read on the Discovery Instrument (Packard). The data output is the ratio of the 665 nm and 620 nm emission signal resulting from the 320 nm excitation.

[0255] HIF PHD2 activity was detected by P564-HIF1 α peptide and VCB binding in the TR-FRET format. HIF PHD2 was assayed at various concentrations between 0 and 40OnM with 3 μM HIF lα peptide in buffer containing 50 mM Tris-HCl (pH 7.5), 100 mM NaCl, 0.05% Tween 20, 2 mM 2- oxoglutarate (2-OG), 2 mM ascorbic acid and 100 μM FeCl₂ in a final volume of 100 μL. The time-course was determined by periodically transferring 2.5 μL of the reaction into 250 μL of 10x TR-FRET buffer containing 500 mM HEPES (pH 7.5), 1 M NaCl, 1% BSA, and 0.5% Tween-20 to terminate the enzyme reaction. 15nM HIF- lα peptide from the terminated reaction was added to 35 nM streptavidin-APC and 1OnM VCB-Eu to a final volume of 100 μL in 1OX TR- FRET buffer. The TR-FRET reagents were placed on a shaker for 1 hour before detection on the Discovery platform.

[0256] As demonstrated in Figures 2A and 2B, there was a dose dependent increase in TR-FRET signal resulting from binding of the hydroxylated-P564- HIF lα peptide to VCB-Eu compared to the unhydroxylated form of the peptide resulting in a 14 fold signal over noise ratio at 125 nM HIF lα peptide. VCB binding to the APC bound peptide permits a FRET transfer between the Eu and APC. The signal was linear to 2 nM peptide with 3.125 nM VCB, but increases to 62.5 nM peptide with 50 nM VCB resulting in a larger linear range. [0257] TR-FRET detection utilizing Eu-labeled VCB is a practical system for determining HIF PHD2 catalytic activity. HIF PHD2 hydroxylation of the HIFl α peptide results in the increase affinity of VCB to the peptide and hence and increased FRET signal. As shown in Figures 3A and 3B, activity was verified with a fairly linear and an increasing TR-FRET signal over time. There was a dose dependant increase in initial rates with increasing HIF PHD2 enzyme concentration up to 400 nM. The initial rates were linear to 100 nM enzyme. [0258] Inhibition of HIF PHD2 activity was quantified utilizing the TR-

FRET technology. HIF PHD2 catalyzes a hydroxyl modification on the proline residue of the P564-HIFlα peptide substrate (Biotin-DLEMLAPYIPMDDDFQL (SEQ ID NO: 7)) resulting in recognition and binding of the europylated Von Hippel-Lindau protein (pVHL), elongin B and elongin C heterotrimeric (VCB-Eu) complex.

[0259] The PHD2 inhibition assay was executed by addition of freshly dissolved FeCl₂ to 178.57 μM (100 μM final concentration) in PHD2 Reaction Buffer containing 30 mM MES, pH 6, 10 mM NaCl, 0.25% Brij-35, 0.01% BSA, and 1% DMSO. 28 μL of the iron solution and 2 μL of inhibitor compounds serially diluted in 100% DMSO (5% DMSO final) were added to black polypropylene 96-well microtiter plates. To that, 10 μL of 10 nM PHD2 (2 nM final) was added to all wells of the plate except for the 8 wells of column 12 (LO control), and allowed to incubate at room temperature on the shaker for one hour. Column 6 was the HI control containing PHD2 enzyme and 5% DMSO vehicle, but no inhibitor compound. To initiate the PHD2 enzymatic reaction, 10 μL of a solution containing 500 nM P564-HIFlα peptide (100 nM final), 10 mM ascorbic acid (2 mM final), and 1.25 μM 2-oxoglutarate (α-ketoglutarate; 0.25 μM final) in PHD2 Reaction Buffer was added to all wells of the plate and allowed to incubate on the shaker at room temperature for one hour.

[0260] The reaction was terminated by addition of 25 μL TR-FRET Buffer

(50 mM TRIS-HCl, pH 9, 100 mM NaCl, 0.05% BSA, and 0.5% Tween-20) containing 150 mM succinate (product inhibitor; 50 mM final), 75 nM streptavidin-APC (25 nM final), and 7.5 nM VCB-Eu (2.5 nM final). The TR- FRET detection reagents were placed on a shaker for 1 hour to reach binding equilibrium before reading on the Discovery platform (PerkinElmer). Europium is excited at 315 nm and phosphoresces at 615nm with a large Stoke's shift. APC, in turn, emits at 655 nm upon excitation at 615 nm. The TR-FRET signal is measured as the ratio of the APC 655 nm signal divided by the internal europium reference 615 nm emission signal. [0261] The POC (percentage of control) was determined by comparing the signal from hydroxylated peptide substrate in the enzyme reaction containing inhibitor compound with that from PHD2 enzyme with DMSO vehicle alone (HI control), and no enzyme (LO control). POC was calculated using the formula: % control (POC) = (cpd - average LO) / (average HI - average LO)* 100. Data (consisting of POC and inhibitor concentration in μM) was fitted to a 4-parameter equation (y = A + ((B-A) / (1 + ((x/C)^ΛD))), where A is the minimum y (POC) value, B is the maximum y (POC), C is the x (cpd concentration) at the point of inflection and D is the slope factor) using a Levenburg-Marquardt non-linear regression algorithm.

[0262] In certain embodiments, compounds of the present invention exhibit a HIF PHD inhibitory activity IC₅₀ value of 40 μM or less. In additional embodiments, compounds of the present invention exhibit a HIF PHD inhibitory activity IC₅₀ value of 10 μM or less and in further embodiments, compounds of the present invention exhibit a HIP PHD inhibitory activity IC_5O value of 5 μM or less.

[0263] The following table includes PHD2 IC₅₀ values obtained using the procedures set forth herein for various Examples compounds described herein.

Table of PHD2 IC₅₀ values of Example Compounds

[0264] All publications and patent applications cited in this specification are hereby incorporated by reference herein in their entireties and for all purposes as if each individual publication or patent application were specifically and individually indicated as being incorporated by reference and as if each reference was fully set forth in its entirety. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

Claims

WHAT IS CLAIMED:

1. A composition of matter, comprising at least one compound of Formula I:

R₁ and R₂ are independently selected in each instance from H, lower alkyl, substituted lower alkyl, lower haloalkyl, or substituted lower haloalkyl, or Ri and R₂ can join together to form a 3 to 6 membered ring or a substituted 3 to 6 membered ring;

R₄ is selected from H, OH, lower alkoxy, SH, NH₂, NHSO₂R₇, or sulfonyl;

R₅ is selected from H, lower alkyl, or substituted lower alkyl; each R₆ is independently selected from H, F, Cl, Br, I, alkyl, substituted alkyl, haloalkyl, perhaloalkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, NR_dR*, C(O)R_7, C(O)OR₈, OR₈, SR₈, SO₂R₈, CN, NO₂, aryl, substituted aryl, arylalkyl, substituted arylalkyl, heteroaryl, substituted heteroaryl, heteroarylalkyl, substituted heteroarylalkyl, heterocyclyl, substituted heterocyclyl, heterocyclylalkyl, substituted heterocyclylalkyl, or -Y-R₉, wherein:

Y is selected from — N(R_JO)-Z- or -Z-N(Ri₀)-;

Ri₀ is selected from H, lower alkyl, or substituted lower alkyl; and

Rd and R_e are independently selected from H, lower alkyl, substituted lower alkyl, lower haloalkyl, or substituted lower haloalkyl, or R_d and R» can join together to form a 3 to 6 membered ring or a substituted 3 to 6 membered ring.

2. The composition of matter according to claim 1, wherein M and L are N and J and K are CR₆.

3. The composition of matter according to claim 1, wherein M and K are N and J and L are CR₆.

4. The composition of matter according to claim 1, wherein J and M are N and K and L are CR₆.

5. The composition of matter according to claim 1, wherein the compound of Formula I is a compound of Formula IA

IA.

6. The composition of matter according to any one of claims 1-5, wherein R₃ is OH.

7. The composition of matter according to any one of claims 1-6, wherein R₄ is OH.

8. The composition of matter according to any one of claims 1-7, wherein X is -NR₃-.

9. The composition of matter according to claim 8, wherein X is

-NH-.

10. The composition of matter according to any one of claims 1-9, wherein at least one instance of R₆ is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted heterocyclyl group.

11. The composition of matter according to claim 10, wherein at least one instance of R₆ is a heterocyclyl group.

12. The composition of matter according to claim 10, wherein at least one instance of R₆ is a heteroaryl group.

13. The composition of matter according to claim 10, wherein at least one instance of R₆ is a phenyl or substituted phenyl group.

14. The composition of matter according to any one of claims 1-13, wherein at least one instance of R₆ is chosen from a halo or a moiety substituted with at least one halo.

15. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

, wherein the wavy line indicates the point of attachment to the rest of the molecule.

16. The composition of matter according to any one of claims 1 -9,

wherein R₆ is a group of formula

wherein the wavy line indicates the point of attachment to the rest of the molecule.

17. The composition of matter according to any one of claims 1 -9,

wherein R₆ is a group of formula

18. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

19. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

20. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

21. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

22. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

23. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

24. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

25. The composition of matter according to any one of claims 1 -9,

wherein R₆ is a group of formula

26. The composition of matter according to any one of claims 1-9,

wherein R₆ is a group of formula

27. The composition of matter according to any one of claims 1 -26, wherein n is 1.

28. The composition of matter according to any one of claims 1-27, wherein Rj and R₂ are independently chosen from H and lower alkyl.

29. The composition of matter according to claim 28, wherein Rj and R₂ are independently chosen from H and methyl.

30. The composition of matter according to claim 28, wherein Ri and R₂ are both H.

31. The composition of matter according to any one of claims 1, 2, 3, 4, or 5, wherein n is 1 ; Rj is H or lower alkyl; R₂ is H; R₃ is OH; R₄ is OH; X is -NR₃-; and R_a is H.

32. The composition of matter according to any one of claims 1-31, wherein R₅ is H.

33. The composition of matter according to any one of claims 1-31, wherein R₅ is lower alkyl.

34. The composition of matter according to claim 33, wherein R₅ is methyl.

35. The composition of matter according to any one of claims 1-31, wherein R₅ is a substituted lower alkyl selected from an arylalkyl, a heteroarylalkyl, a heterocyclylalkyl, a cycloalkylalkyl, a hydroxyalkyl, an alkoxyalkyl, or a haloalkyl.

36. The composition of matter according to claim 1, wherein the at least one compound is selected from one of the following compounds or is a salt thereof, a tautomer thereof, or a salt of the tautomer:

2-(3-cyclopentyl-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid; 2-(3 -cyclohexenyl-5 -hydroxy- 8 -methyl-7-oxo-7 , 8 -dihydropyr ido [2,3- c]pyridazine-6-carboxamido)acetic acid;

2-(5-hydroxy-2-methoxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-d]pyrimidine-

6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(2-methylpiperidin-l-yl)-7-oxo-7,8- dihydropyrido [2,3 -d]pyrimidine-6-carboxamido)acetic acid;

37. The composition of matter according to claim 1, wherein the at least one compound is selected from one of the following compounds or is a salt thereof, a tautomer thereof, or a salt of the tautomer: 2-(5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid;

4-(6-((carboxymethyl)carbamoyl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido [2,3 -c]pyridazin-3 -yl)benzoic acid;

6-((carboxymethyl)carbamoyl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-c]pyridazine-3-carboxylic acid;

6-((carboxymethyl)carbamoyl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-2-carboxylic acid; 2-(5-hydroxy-2-(isoindolin-2-yl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(8-benzyl-5-hydroxy-7-oxo-2-(trifluoromethyl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-8-methyl-7-oxo-2-(4-phenylpiperazin-l-yl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-3-methoxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3-c]pyridazine-6- carboxamido)acetic acid; or

2-(5-hydroxy-8-methyl-7-oxo-3-(piperidin-l-yl)-7,8-dihydropyrido[2,3- c]pyridazine-6-carboxamido)acetic acid.

38. The composition of matter according to claim 1, wherein the at least one compound is selected from one of the following compounds or is a salt thereof, a tautomer thereof, or a salt of the tautomer:

2-(2-(5-ethyl-2-methylpiperidin-l-yl)-5-hydroxy-8-methyl-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-8-methyl-2-(octahydroquinolin-l(2H)-yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; 2-(2-(3-fluorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-2-(2-methoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-8-methyl-7-oxo-2-(4-(piperidin-l-yl)phenyl)-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-2-(4-methoxyphenyl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(benzo[b]thiophen-2-yl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(4-chlorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(2-(3-chlorophenyl)-5-hydroxy-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-8-methyl-2-(l-methyl-lH-indol-5-yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; 2-(5-hydroxy-8-methyl-7-oxo-2-(quinolin-4-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-7-oxo-2-(pyridin-3-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxainido)acetic acid;

2-(5-hydroxy-2-(lH-indol-4-yl)-8-methyl-7-oxo-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid;

2-(5-hydroxy-8-methyl-2-(l -methyl- 1 H-indol-2-yl)-7-oxo-7,8- dihydropyrido[2,3-d]pyrimidine-6-carboxamido)acetic acid; or

2-(5-hydroxy-8-methyl-7-oxo-2-(l-tosyl-lH-indol-3-yl)-7,8-dihydropyrido[2,3- d]pyrimidine-6-carboxamido)acetic acid.

39. The composition of matter according to claim 1 , wherein Ri and R₂ are not both H if X is -NR₃-; R₃ is H; and n is 1.

40. The composition of matter according to claim 1, wherein n is 1, Ri and R₂ are both H, X is -NR₃-; and R₃ is H.

41. The composition of matter according to claim 1, wherein at least one of Ri and R₂ is not H.

42. A pharmaceutical formulation comprising at least one pharmaceutically acceptable excipient, and a therapeutically effective amount of the composition of matter of any one of claims 1-37, 38, 39, 40, or 41.

43. The pharmaceutical formulation of claim 42, wherein the composition of matter is present in an amount effective for the treatment of at least one disease selected from ischemia, anemia, wound healing, auto- transplantation, allotransplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

44. A method of increasing or stabilizing HIF levels or activity in a subject comprising administering to the subject the composition of matter of any one of claims 1-37, 38, 39, 40, or 41.

45. A method of treating a condition where it is desired to modulate HIF activity, comprising administering to a subject the composition of matter according to claim any one of claims 1-37, 38, 39, 40, or 41.

46. The method according to claim 45, wherein said condition is selected from at least one of ischemia, anemia, wound healing, auto- transplantation, allo- transplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

47. A method of treating a hypoxic or ischemic related disorder in a subject comprising administering to a subject the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41.

48. A method of modulating the amount of HIF in a cell, comprising contacting the cell with the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41.

49. A method of treating at least one disease in a patient in need of such treatment comprising administering to the patient a therapeutically effective amount of the composition of matter according to any one of claims 1- 37, 38, 39, 40, or 41.

50. The method according to claim 49, wherein the at least one disease is selected from ischemia, anemia, wound healing, auto- transplantation, allotransplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

51. A method of inhibiting HIF hydroxylation in a subject, comprising administering to the subject the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41.

52. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41 in the preparation of a medicament.

53. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41 in the preparation of a medicament for increasing or stabilizing HIF levels or activity in a subject.

54. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41, in the preparation of a medicament for treating a condition where it is desired to modulate HIF activity.

55. The use of claim 54, wherein the condition is selected from at least one of ischemia, anemia, wound healing, auto- transplantation, allotransplantation, xenotransplantation, systemic high blood pressure, thalassemia, diabetes, cancer, or an inflammatory disorder.

56. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41, in the preparation of a medicament for treating a hypoxic or ischemic related disorder in a subject.

57. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41, in the preparation of a composition for modulating the amount if HIF in a cell.

58. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41, in the modulation of the amount if HIF in a cell.

59. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41, in the preparation of a medicament for modulating angiogenesis in a subject.

60. The use of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41, in the preparation of a medicament for inhibiting HIF hydroxylation in a subject.

61. A method for increasing the amount of erythropoietin in the blood of a subject, comprising: administering a therapeutically effective amount of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41 to the subject.

62. The use of of the composition of matter according to any one of claims 1-37, 38, 39, 40, or 41, in the preparation of a medicament for increasing the amount of erythropoietin in the blood of a subject.

63. The composition of matter according to any one of claim 1-37, 38, 39, 40, or 41 for use in a method for increasing the level of erythropoietin in the blood of a subject.