WO2015038680A1

WO2015038680A1 - Drug conjugates of gga and gga derivatives

Info

Publication number: WO2015038680A1
Application number: PCT/US2014/055039
Authority: WO
Inventors: William Haag; Obsidiana ABRIL-HÖRPEL; Hiroaki Serizawa
Original assignee: Coyote Pharmaceuticals, Inc.
Priority date: 2013-09-11
Filing date: 2014-09-10
Publication date: 2015-03-19

Abstract

This invention relates to conjugates of geranylgeranylacetone (GGA) and GGA derivatives.

Description

DRUG CONJUGATES OF GGA AND GGA DERIVATIVES

Cross-Reference To Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No.

61/876,615 entitled "DRUG CONJUGATES OF GGA AND GGA DERIVATIVES," filed on September 11, 2013; and U.S. Provisional Patent Application No. 61/982,220 entitled "DRUG CONJUGATES OF GGA AND GGA DERIVATIVES," filed on April 21, 2014, and hereby expressly incorporated by reference herein in their entirety.

Field of the Invention

[0002] This invention relates generally to drugs conjugated to geranylgeranyl acetone (GGA) or GGA derivatives and processes for their syntheses.

State of the Art

[0003] Geranylgeranylacetone (GGA) is an acyclic isoprenoid compound with a retinoid skeleton having the formula:

"Other end" "Keto-group"

GGA is a known anti-ulcer drug used commercially and is reported to have neuroprotective and related effects. See, for example, PCT Pat. App. Pub. No. WO 2012/031028 and PCT Pat. App. No. PCT/US2012/027147, each of which is incorporated herein by reference in its entirety. Drug conjugates where the drug is conjugated at the "other end" are attractive because they retain the keto group or a masked or protected form of it and can assist in tissue penetration. However, the alkyl groups present at the "other end" do not provide adequate functionality for conjugating a drug.

SUMMARY OF THE INVENTION [0004] In various aspects, provided herein are GGA derivatives conjugated to a variety of drugs ("GGA conjugates") preferably wherein the keto group or a masked or protected form of it is retained and the drug conjugation occurs at the other end of the GGA derivative. In some embodiments, provided herein are pharmaceutically acceptable salts of the conjugates provided herein. GGA or the GGA derivatives utilized herein are described herein and/or are known to the skilled artisan. The drug (D) can be any drug, preferably one that contains one or more - C0₂H, -OH, -NH₂, and/or -SH, and such other groups that can be covalently conjugated as provided herein.

[0005] In one aspect, provided herein is a compound of formula (1), (2), or (3):

(3)

or a pharmaceutically acceptable salt of each thereof wherein:

L¹ and L² are independently a bond or a linker, which is preferably cleaved in vivo to provide an effective concentration of the drug D;

Z¹ is O, NR¹⁰, or S, wherein R¹⁰ is hydrogen or Ci-C₆ alkyl,

X and Y are each independently OR⁶, SR⁶, or X and Y together with the carbon atom they are attached to form a C=0 moiety or a ring of formula:

wherein each R⁶ is independently Ci-C₆ alkyl, each X¹ and X² are independently O, or S; q is 1 or 2; each X³ is independently Ci-C₆ alkyl; t is 0, 1, 2, or 3, and each R is defined as R³, R⁴, R⁵, and R⁷ herein, and is independently H or Ci-C₆ alkyl; and n is an integer from 0 to 5.

[0006] As will be apparent to the skilled artisan, conjugates provided herein exclude those that have a -O-O- or an -O-S- bond resulting from the D-GGA derivative, D-linker, or a linker GGA- derivative bonding.

[0007] In one embodiment, L¹ is selected from -L-CO-, L-0-, -L-OCO-, -L-CO-, wherein L is preferably a straight or branched chain linker group of 1 to 15 atoms consisting of carbon, nitrogen, oxygen, phosphorus, and sulfur, wherein the number of heteroatoms is preferably no more than 5.

[0008] In one embodiment, each L² independently is selected from -CO-L-CO-, -CO-L-0-, -O- L-CO-, -CO-L-OCO-, and -OCO-L-CO-.

[0009] In some embodiments, L¹ and L² independently is or comprises a Ci-Cio alkylene or Ci- Cio heteroalkylene, C3-C10 cycloalkyl, C₆-Ci₀ aryl, Ci-Ci₀ heteroaryl, or C₂-Ci₀ heterocyclyl moiety, which can be optionally substituted. Certain preferred substituents include Ci-C₆ alkyl, - OH, fluoro, amino, Ci-C₆ alkylamino, or di Ci-C₆ alkylamino, C₃-C₆ cycloalkyl, Ci-Cio heteroaryl, or C₂-Cio heterocyclyl. In some embodiments, L¹ and L² comprise or are part of an amino acid moiety, such as without limitation glutamic acid. In some embodiments, Li or L₂ is a di, tri, tetra, or pentapeptide, preferably comprising 1, more preferably 2, and still more preferably 3 or more naturally occurring amino acids.

[0010] In some embodiments, L₂ is a bivalent Ci-C₃o alkylene group optionally substituted with 1-6 substituents selected from -OH, =0, -C0₂, halo, Ci-C₆ alkyl, Ci-C₆ alkoxy groups, and optionally interrupted with 1-6 groups such as -0-, -S-, -NR⁵CO-, or -NR⁵-, where R⁵ is hydrogen or Ci-C₆ alkyl. In one embodiment, the linker in -CO-.

[0011] In some embodiments, the linker L₂ is

, O , or

g is 1 to 10. In some embodiments, the linker L₂ is

In some embodiments, the linker L₂

[0012] In another embodiment, L², when bonded with Z¹, is a bond, methylene, or carbonyl.

[0013] In certain preferred embodiments, the linker is hydrolyzed in a targeted organ or tissue, and the drug is selectively delivered to those organs or tissues. In certain embodiments, the linker is stable in plasma but is hydrolyzed in CNS tissues. Such conjugates can increase the delivery of drugs to the CNS where the drugs alone are not delivered in concentrations sufficient to the CNS for therapy of CNS disorders.

[0014] In certain preferred embodiments, the linker joins the isoprenyl portion to a carbonyl moiety, or an oxygen, nitrogen, or sulfur atom of the drug.

[0015] In another preferred embodiment, R is methyl. In another preferred embodiment, n is 3-5. In another preferred embodiment, X and Y together with the carbon atom they are attached to form a C=0 moiety.

In another preferred embodiment, the drug conjugated is of formula (1-A):

(1-A) wherein R and D are defined as in formula (1). In some embodiments, R is methyl. [0016] In another preferred embodiment, the drug conjugated is of formula (2 -A) or (2-B):

(2-A) (2-B) wherein R, each Z¹ independently, and D are defined as in formula (2). In some embodiments, R is methyl.

[0017] In another preferred embodiment, the drug conjugated is of formula (3 -A):

(3-A) wherein R, Z¹, and D are defined as in formula (3). In some embodiments, R is methyl

[0018] In some embodiments, conjugated drugs include the following exemplary and non- limiting drugs that are useful for treating the respective indications indicated after each drug: Forteo - osteoporosis; Ceredist (TRH) - ataxia; Byetta (GLP-1) - diabetes; Sandostatin (GHI) - acromegaly; Victoza (GLP-1) - diabetes; Insulin and known modifications thereof— Diabetes; Octreotide—treatment of growth hormone producing tumors etc., Gonal-f (FHS) - infertility; Neupogen (G-CSF) - neutropenia; Kepivance - mucositis in cancer; Natrecor (B type naturietic protein) - congestive heart failure; Calcitonin for hypercalcemia; ACTH for infantile spasms; Oxytocin for premature delivery in pregnancy; Copaxone for multiple sclerosis; Beta-interferon for multiple sclerosis; and Alpha-interferon for viral hepatitis.

[0019] Additional drugs include but are not limited to: antibiotics, such as Vancomycin, Daptomycin, Pristamycin 1A and IB, or Linezolid, etc.; analgesics, such as the aminopyridine, Flupirtine, or opiates such as Morphine or Codeine, etc; and steroidal or non-steroidal antiinflammatory drugs, such as but not limited to dexamethazone and ibuprophen, indomethacin, or naproxen, respectively. [0020] In some embodiments, it is contemplated that that the drug conjugate of GGA or a GGA derivative, forms a micellar or a similarly aggregated structure. Without being bound by theory, it is contemplated that GGA, a GGA derivative, or a GGA-drug conjugate utilized or provided herein can form a micelle or a reverse micelle. A micelle has a hydrolphilic portion exposed to a surrounding aqueous or hydrophilic phase. A reverse micelle has a hydrophobic portion exposed to a surrounding hydrophobic phase. As disclosed herein, both forms can be in equilibrium with each other. It is further contemplated that a conversion of a micelle to a reverse micelle and vice versa can allow a facile transportation of GGA or the GGA derivative, or the drug conjugate of GGA or a GGA derivative from an aqueous phase into the sublingual mucosal layer and further into blood in a short period of time. In the process, the drug within or associated with the micelle migrates from the salivary aqueous environment into blood.

[0021] In another aspect, provided herein is a pharmaceutical composition comprising a conjugate provided herein and at least one pharmaceutically acceptable excipient.

[0022] In other aspects, provided herein are methods for preparing the conjugates provided herein.

DETAILED DESCRIPTION

[0023] It is to be understood that this invention is not limited to particular embodiments described. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0024] It must be noted that as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an excipient" includes a plurality of excipients.

Definitions

[0025] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein the following terms have the following meanings.

[0026] As used herein, the term "comprising" or "comprises" is intended to mean that the compositions and methods include the recited elements, but not excluding others. "Consisting essentially of when used to define compositions and methods, shall mean excluding other elements of any essential significance to the combination for the stated purpose. Thus, a composition consisting essentially of the elements as defined herein would not exclude other materials or steps that do not materially affect the basic and novel characteristic(s) of the claimed invention. "Consisting of shall mean excluding more than trace elements of other ingredients and substantial method steps. Embodiments defined by each of these transition terms are within the scope of this invention.

[0027] The term "about" when used before a numerical designation, e.g., temperature, time, amount, and concentration, including range, indicates approximations which may vary by (+) or ( - ) 10 %, 5 %, or 1 %.

[0028] The term "halo" or "halo group" refers to fluoro, chloro, bromo and iodo.

0029] "Geometrical isomer"" or "geometrical isomers" refer to compounds that differ in the geometry of one or more olefmic centers. "E" or "(E)" refers to the trans orientation and "Z" or "(Z)" refers to the cis orientation.

[0030] Geranylgeranyl acetone (GGA) refers to a compound of the formula:

wherein compositions comprising the compound are mixtures of geometrical isomers of the compound.

[0031] The 5-trans isomer of geranylgeranyl acetone refers to a compound of the formula:

wherein the number 5 carbon atom is in the 5-trans (5E) configuration.

[0032] The 5-cis isomer of geranylgeranyl acetone refers to a compound of the formula:

wherein the number 5 carbon atom is in the 5-cis (5Z) configuration. [0033] 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. Each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0034] As used herein, C_m-C_n, such as Ci-Cio, Ci-C₆, or C₁-C₄ when used before a group refers to that group containing m to n carbon atoms.

[0035] The term "alkyl" refers to monovalent saturated aliphatic hydrocarbyl groups having from 1 to 10 carbon atoms (i.e., C₁-C₁₀ alkyl) or 1 to 6 carbon atoms (i.e., Ci-C₆ alkyl), or 1 to 4 carbon atoms. This term includes, by way of example, linear and branched hydrocarbyl groups such as methyl (CH₃-), ethyl (CH₃CH₂-), n-propyl (CH₃CH₂CH₂-), isopropyl ((CH₃)₂CH-), n- butyl (CH₃CH₂CH₂CH₂-), isobutyl ((CH₃)₂CHCH₂-), sec-butyl ((CH₃)(CH₃CH₂)CH-), t-butyl ((CH₃)₃C-), n-pentyl (CH₃CH₂CH₂CH₂CH₂-), and neopentyl ((CH₃)₃CCH₂-). In some embodiments, the term "alkyl" refers to substituted or unsubstituted, straight chain or branched alkyl groups with Ci-Ci₂, Ci-C₆ and preferably C₁-C₄ carbon atoms. Similarly, alkylene refers to a divalent saturated hydrocarbyl moiety, and heteroalkylene refers to an alkylene moiety where 1-5, preferably, 1-3 carbon atoms are replaced with an oxygen, sulfur, and/or nitrogen atom or an oxidized form of sufur and/or nitrogen atoms.

[0036] The term "cycloalkyl" refers to a monovalent, preferably saturated, hydrocarbyl mono-, bi-, or tricyclic ring having 5-6 ring carbon atoms. While cycloalkyl, refers preferably to saturated hydrocarbyl rings, as used herein, it also includes rings containing 1-2 carbon-carbon double bonds. Nonlimiting examples of cycloalkyl include cyclopentyl, cyclohexyl, and the like. The condensed rings may or may not be non-aromatic hydrocarbyl rings provided that the point of attachment is at a cycloalkyl carbon atom. For example, and without limitation, the following is a cycloalkyl group:

[0037] The term "aryl" refers to a monovalent, aromatic mono- or bicyclic ring having 6-10 ring carbon atoms. Examples of aryl include phenyl and naphthyl. The condensed ring may or may not be aromatic provided that the point of attachment is at an aromatic carbon atom. For example, and without limitation, the following is an aryl group:

[0038] The term "hydrolyzing" refers to adding water across a C-0 and/or a C-S bond, such as hydrolyzing a ketal, a thioketal and the likes to the corresponding ketone. A hydrolyzing is performed using various methods well known to the skilled artisan, non limiting examples of which include acidic hydrolysis. A variety of acids such as protic acids and Lewis acids can be used for the hydrolysis.

[0039] The term "heteroaryl" refers to a monovalent, aromatic mono-, bi-, or tricyclic ring having 2-14 ring carbon atoms and 1-6 ring heteroatoms selected preferably from N, O, S, and P and oxidized forms of N, S, and P, provided that the ring contains at least 5 ring atoms.

Nonlimiting examples of heteroaryl include furan, imidazole, oxadiazole, oxazole, pyridine, quinoline, and the like. The condensed rings may or may not be a heteroatom containing aromatic ring provided that the point of attachment is a heteroaryl atom. For example, and without limitation, the following is a heteroaryl group:

[0040] The term "heterocyclyl" or heterocycle refers to a non-aromatic, mono-, bi-, or tricyclic ring containing 2-10 ring carbon atoms and 1-6 ring heteroatoms selected preferably from N, O, S, and P and oxidized forms of N, S, and P, provided that the ring contains at least 3 ring atoms. While heterocyclyl preferably refers to saturated ring systems, it also includes ring systems containing 1-3 double bonds, provided that they ring is non-aromatic. Nonlimiting examples of heterocyclyl include, azalactones, oxazoline, piperidinyl, piperazinyl, pyrrolidinyl,

tetrahydrofuranyl, and tetrahydropyranyl. The condensed rings may or may not contain a non- aromatic heteroatom containing ring provided that the point of attachment is a heterocyclyl group. For example, and without limitation, the following is a heterocyclyl group:

[0041] The term "oxidizing" or "oxidation" refers to taking one or more electron away from a bond or an atom, preferably taking two electrons away from a bond or an atom. Non-limiting examples of oxidation include conversion of an alcohol to an aldehyde.

[0042] The term "reducing" or "reduction" refers to adding one or more electron across a bond or an atom, preferably adding two electrons to a bond or an atom. Non-limiting examples of reduction include conversion of a carboxylic acid or an ester thereof to an alcohol.

[0043] The term "salt" refers to an ionic compound formed between an acid and a base. When the compound provided herein contains an acidic functionality, such salts include, without limitation, alkai metal, alkaline earth metal, and ammonium salts. As used herein, ammonium salts include, salts containing protonated nitrogen bases and alkylated nitrogen bases. Exemplary, and non-limiting cations useful in pharmaceutically acceptable salts include Na, K, Rb, Cs, NH₄, Ca, Ba, imidazolium, and ammonium cations based on naturally occurring amino acids. When the compounds provided and/or utilized herein contain basic functionality, such salts include, without limitation, salts of organic acids, such as caroboxylic acids and sulfonic acids, and mineral acids, such as hydrogen halides, sulfuric acid, phosphoric acid, and the likes. Exemplary and non-limiting anions useful in pharmaceutically acceptable salts include oxalate, maleate, acetate, propionate, succinate, tartrate, chloride, sulfate, bisulfate, mono-, di-, and tribasic phosphate, mesylate, tosylate, and the likes.

Illustrative Embodiments

[0044] The following conjugates are illustrative and non-limiting embodiments of those provided herein. Certain illustrative drugs, linkers, and GGA derivatives are employed herein. Other drugs, preferably peptide drugs, can be conjugated via these or other linkers, to these or other GGA derivatives following this disclosure. The drugs illustrated herein below, Victoza, insulin and various active variants thereof, and octreotide, can also be conjugated via other linkers to other GGA derivatives following this disclosure. [0045] In a preferred embodiment the conjugate provided herein is:

[0046] In another preferred embodiment, the conjugate provided herein is:

[0047] In another preferred embodiment, the conjugate provided herein is an insulin conjugate:

[0048] In another preferred embodiment, the conjugate provided herein is an insulin conjugate:

 n is 1 ,2, 3, 4, or 5.

[0049] Insulin that can be conjugated according to this invention includes without limitation:

where X¹ is Pro or Lys, Y¹ is Lys or Pro, provided that X¹ and Y¹ are both not the same amino acid residue, and Z¹ is present or is absent, and is Thr when present.

[0050] In another preferred embodiment, the conjugate provided herein is an octreotide conjugate:

Preparation of the Coniugates

[0051] In various aspects, provided herein are processes for preparing the conjugates provided herein. In certain embodiments, the processes employ the following intermediates:

(III)



(X)

(XIV)

(XVIII)

or a salt thereof, wherein the variables in the structures (III)-(XVIV) are defined as in formulas (l)-(3) above.

[0052] In another aspect, the intermediates employed in the processes include compounds of formulas (XXI) -(XIV):

(XXII)

(XXV) or a tautomer or pharmaceutically acceptable salt thereof, wherein n is an integer from 1 to 5, and the remaining variables are defined as in formula (l)-(3) above.

[0053] In one embodiment, X and Y together with the carbon atom they are attached to form a cyclic ketal with two oxygen, two sulfur or one oxygen and one sulfur atom.

[0054] In one embodiment, X and Y together with the carbon atom they are attached to form a dioxolane, oxathiolane, dithiolane, dioxane, oxathiane or a dithiane ring.

[0055] Compound provided herein or intermediates thereto, wherein X and Y together with the carbon atom they are attached to form a cyclic or acyclic ketal or thioketal, can be subjected to an acid hydrolysis to provide a compound wherein X and Y together with the carbon atom they are attached to form a C=0 moiety.

[0056] In one embodiment, the conditions suitable for such hydrolysis include contacting the starting compound of with an acid catalyst in an inert solvent at a suitable temperature. In one embodiment, the acid catalyst utilized in the process is selected from an aqueous acetic acid, formic acid, trifluoroacetic acid, sulfuric acid, hydrochloric acid, methanesulfonic acid, alkyl or aralkylsulfonic acid or a Lewis acid. The acid is preferably used in catalytic amount.

[0057] In another embodiment, the process comprises subjecting a compound of formula (III) to a Schiff-base formation reaction under conditions suitable for forming Schiff-base

compounds.

Schiff-base

formation

(III)

Suitable conditions for Schiff-base formation are well known to the skilled artisan. In some embodiments, an intermediate Schiff-base can be further derivatized to provide the conjugates provided herein.

[0058] A compound of formula (3):

(3)

can be prepared comprising reacting an amine, alcohol, or a thiol with a compound of formula

(3-C):

(3-C) wherein Y is OH, CI, Br, or Ci-C₆ alkoxy under conditions suitable to form an ester, amide, or a thioester. The compound of formula (3-C) is prepared from compounds wherein Y¹ is OMe, which are illustrated herein, and derivatives of such compounds as is well known to the skilled artisan.

[0059] A compound of formula (2):

(2-C) wherein Z¹ is as defined in in formula (2) under conditions suitable to form an ester, amide, a thioester, an ether, a thioether, or a secondary or tertiary amine. The compound of formula (2-C) wherein Z¹ is O is prepared as illustrated herein, and other Z¹ derivatives are prepared by methods well known to a skilled artisan.

[0060] Other intermediates useful in this invention are prepared as follows. In one

embodiment, the process comprises oxidizing a compound of formula (IV) under suitable conditions to produce a compound of formula (III).

(in)

[0061] In one embodiment, the process comprises oxidizing a compound of formula (VIII) under suitable conditions to produce a compound of formula (VII).

(VIII)

(VII)

[0062] In one embodiment process comprises oxidizing a compound of formula (XII) under suitable conditions to produce a compound of formula (XI).

[0063] In one embodiment, the process comprises oxidizing a compound of formula (XVI) under suitable conditions to produce a compound of formula (XV).

(XVI) (XV)

[0064] In some embodiments, conditions suitable for oxidation of compound of formula (IV), (VIII), (XII), (XVI) include, subjecting the compound to Moffatt oxidation. As will be appreciated by one skilled in the art, Moffat oxidation is the reaction of primary and secondary alcohols by dimethyl sulfoxide (DMSO) activated with a carbodiimide, such as

dicyclohexylcarbodiimide (DCC) in presence of an acid to produce an alkoxysulfonium ylide which rearranges to generate aldehydes and ketones, respectively (K. E. Pfitzner and J. G. Moffatt, J. Am. Chem. Soc, 85, 3027 (1963)). Swern Oxidation may also be used, which in some embodiments employs DMSO and oxalyl chloride, at low temperatures, as is well known to the skilled artisan.

[0065] In some embodiments, other methods suitable for oxidation of an alcohol to an aldehyde can be utilized. For example, the alcohol can be oxidized under Parikh-Doering oxidation conditions using DMSO as the oxidant, activated by the sulfur trioxide pyridine complex in the presence of alkylamine base, e.g., triethylamine. In other embodiments, the alcohol compound can be oxidized under Swern oxidation conditions using oxalyl chloride, dimethyl sulfoxide (DMSO) and an organic base, such an alkylamine base, e.g., triethylamine. [0066] In one embodiment, the process comprises reducing a compound of formula (V) under suitable conditions to produce a compound of formula (IV).

[0067] In one embodiment, the process comprises oxidizing a compound of formula (IX) under suitable conditions to produce a compound of formula (VIII).

(IX) (VIII)

[0068] In one embodiment, the process comprises oxidizing a compound of formula (XIII) under suitable conditions to produce a compound of formula (XII).

[0069] In one embodiment, the process comprises oxidizing a compound of formula (XVII) under suitable conditions to produce a compound of formula (XVI).

(XVII) (XVI)

[0070] As will be appreciated by one skilled in the art, suitable reducing agents for the reduction of acid of formula (V), (IX) or (XIII) include reducing hydrides, preferably aluminum hydrides or borohydrides, more preferably metal aluminum hydrides in which the metal is a group I or group II metal such as lithium, sodium, potassium, calcium, magnesium or the like. Particularly preferred metal aluminum hydrides include lithium aluminum hydride (LAH), sodium aluminum hydride, and mixture thereof. The reduction is typically conducted in aprotic solvents such as ethers, e.g. tetrahydrofuran or aromatic hydrocarbons e.g., benzene and toluene, at low to reflux temperature using from about 0.5 to about 3.0 moles of hydride reducing agent per mole of compound of formula (V). In one embodiment, the preferred reducing agent is lithium aluminum hydride. Suitable solvents include dioxane, toluene, diethyl ether, tetrahydrofuran (THF), dipropyl ether and the like. In one embodiment, the preferred solvent is diethyl ether or THF.

[0071] In one embodiment, the process comprises reacting a compound of formula (VI) under suitable conditions to produce a compound of formula (V).

[0072] In one embodiment, the process comprises reacting a compound of formula (X) under suitable conditions to produce a compound of formula (IX).

[0073] In one embodiment, the process for preparing the GGA derivative of formula (XIII) is provided. The process comprises reacting a compound of formula (XIV) under suitable conditions to produce a compound of formula (XIII).

[0074] In some embodiments, suitable conditions include subjecting the allylic alcohol of formula (VI), (X) or (XIV) to Johnson-Claisen rearrangement to give the γ,δ-unsaturated ester of formula (VI). In one embodiment, the compound of formula (V) is condensed with a tri-(Ci- C₆)alkyl orthoacetate and further the intermediate allyl-enol ether is rearranged, without isolation, in the presence of an acid in a reaction inert solvent. The orthoacetate utilized for the process is preferably selected from trimethyl orthoacetate and triethyl orthoacetate. In one embodiment, the orthoacetetate has the formula CH3-CH₂-(OR )₃, where R is Ci-C₆ alkyl. In some embodiments, the acid is a weak acid, preferably a simple carboxylic acid such as a propionic acid or isobutyric acid, or an alkane or arene sulphonic acid e.g., p-toluene sulphonic acid. The process is carried out at an elevated temperature preferably the reflux temperature, under conditions where alcohol generated by the process can be removed from the reaction mixture.

[0075] In one embodiment, the process comprises alkenylating a compound of formula (VII) with R³C(-)=CH₂ under suitable conditions to produce a compound of formula (VI).

[0076] In one embodiment, the process comprises alkenylating a compound of formula (XI) with R⁴C(-)=CH₂ under suitable conditions to produce a compound of formula (X).

[0077] In one embodiment, the process comprises alkenylating a compound of formula (XV) with R⁵C(-)=CH₂ under suitable conditions to produce a compound of formula (XIV).

[0078] R³, R⁴, and R⁵ are as defined herein above. In some embodiments, conditions suitable for the alkenylation of the aldehyde of formulas (VII), (XI), and (XV) include, contacting the compound of formula (VII) with an appropriate organometallic reagent in a reaction inert solvent. The organometallic reagent utilized for the C-alkenylation of carbonyl compounds to the allyl alcohol preferably contain magnesium halides or lithium moieties. Suitable inert solvents utilized in the process will be apparent to one skilled in the art. In one embodiment, the solvent is THF or diethyl ether.

[0079] In one embodiment, the process comprises reacting a compound of formula (XVIII) under suitable conditions to produce a compound of formula (XVII).

(XVIII) (XVII)

[0080] In some embodiments, conditions suitable for ketal, thioketal, or an oxa-thioketal (having an -O-C-S- moiety) formation include, reacting the carbonyl compound of formula (XVIII) with a suitable alcohol, alpha omega diol, a thiol, an alpha omega dithiol, or an omega hydroxy thiol solvent under acidic conditions. In one embodiment, the ester of Formula (XVIII) is reacted with a suitable alcohol such as e.g. , ethylene glycol, mercaptoethanol and

1 ,2-dithioethanol in the presence of a suitable acid catalyst followed by azeotropic removal of water. Suitable acid catalysts include, e.g., strong mineral acids, such as sulfuric, hydrochloric, hydrofluoroboric, hydrobromic acids, p-toluenesulfonic acid, camphorosulfonic acid, methanesulfonic acid, and like. Various resins that contain protonated sulfonic acid groups are also useful as they can be easily recovered after completion of the reaction. Examples of acids also include Lewis acids. For example, boron trifluoride and various complexes of BF₃, such as e.g., BF₃ diethyl etherate. Silica, acidic-alumina, titania, zirconia, various acidic clays, and mixed aluminum or magnesium oxides can be used. Activated carbon derivatives comprising mineral acid, sulfonic acid, or Lewis acid derivatives can also be used.

[0081] In one embodiment, the acid catalyst utilized in the process is selected from an aqueous acetic acid, formic acid, trifluoroacetic acid, sulfuric acid, hydrochloric acid, methanesulfonic acid, alkyl or aralkylsulfonic acid or a Lewis acid.

[0082] In one embodiment, the conjugates prepared according to this invention utilizes 5 -trans GGA derivatives or substantially pure 5 -trans GGA derivatives which are optionally free of the corresponding cis GGA derivatives or are essentially free of cis GGA derivatives. In other embodiments, conjugates prepared according to this invention utilizes 5-cis GGA derivatives or substantially pure 5-cis GGA derivatives which are optionally free of the corresponding trans GGA derivatives or is essentially free of trans GGA derivatives. [0083] The starting materials for the reactions described herein are generally known compounds or can be prepared by known procedures or obvious modifications thereof. For example, many of the starting materials are available from commercial suppliers such as Aldrich Chemical Co. (Milwaukee, Wis., USA), Bachem (Torrance, Calif, USA), Emka-Chemce or Sigma (St. Louis, Mo., USA). Others may be prepared by procedures, or obvious modifications thereof, described in standard reference texts such as Fieser and Fieser's Reagents for Organic Synthesis, Volumes 1 15 (John Wiley and Sons, 1991), Rodd's Chemistry of Carbon

Compounds, Volumes 1 5 and Supplemental (Elsevier Science Publishers, 1989), Organic Reactions, Volumes 1 40 (John Wiley and Sons, 1991), March's Advanced Organic Chemistry, (John Wiley and Sons, 4^th Edition), and Larock's Comprehensive Organic Transformations (VCH Publishers Inc., 1989).

[0084] Levulinic esters, such as methyl levulinate or ethyl levulinate, can be converted to the corresponding ketal (X=Y =0), hemi-thioketal (X= O, Y =S), or dithio-ketal,(X = Y = S), by reacting with ethylene glycol, mercapto ethanol, or ethane- 1,2-dithiol, under acidic conditions that facilitate removal of water. Typical acid catalysts include p-toluenesulfonic acid, or acetic acid and boron trifluoride-etherate. Solvents used for such transformations include benzene, toluene and methylene chloride. Water is removed by azeotropic distillation or by reaction with an ortho-ester such as triethyl ortho-formate or triethyl ortho-acetate. (Reaction 1)

[0085] Conversion of the ketal-ester, from Reaction 1 to the corresponding aldehyde, can be accomplished in a single step shown in Reaction 2 by reduction with a hindered active metal hydride such as di-isobutyl aluminum hydride at reduced temperatures in ether, followed by quenching with ethyl acetate to consume excess reagent. Temperatures for such reactions typically must be kept below -35°C to minimize over-reduction to the alcohol. (Reaction 2)

[0086] Alternatively, the aldehyde, can be prepared in higher yield and greater purity in two separate steps. The first step, Reaction 3, involves complete reduction of the ester to the corresponding alcohol, with a strong reducing agent such as lithium aluminum hydride in diethyl ether or THF. This reduction is followed by oxidation of the alcohol to the aldehyde per Reaction 4, by one of the several methods listed below. (Reaction 4)

[0087] Use of chromium trioxide in pyridine for oxidation of alcohols to aldehydes is reported. Alternatively, this oxidation can be accomplished with dimethyl sulfoxide and any of a variety of dehydrating agents. Published examples include various acid chlorides, acid anhydrides, and carbodiimides.

[0088] These reactions typically require temperatures below -35°C prevent side reactions. The method employing a sulfur trioxide-pyridine complex in the presence of triethylamine can be conducted at room temperature with minimal side reactions. (Reaction 5)

[0089] The aldehyde is reacted with 2-propenyl lithium or its Grignard equivalent, to give an allylic alcohol. This alcohol can be converted to olefmic esters in high yield with high stereoselectivity. (Reaction 6)

[0090] The product is then subjected to the transformations of Reactions 3 through 6 for two additional cycles to yield an ester. This ester is then reduced and oxidized as in Reactions 3 and 4 to give the alcohol in (Reaction 7) and the aldehyde in (Reaction 8).

[0091] Methods for conjugating the GGA derivative-linker portion with a peptide drug, such as insulin can be performed following methods well known to the skilled artisan, such as those described in WO 2009/022006 or US 20140057841. A procedure for conjugating to the Phe-NH₂ group will be apparent to the skilled artisan in view if this disclosure. The compounds can be synthesized following solid phase peptide synthesis protocols well known to the skilled artisan or known by modifications thereof.

[0092] From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention.

[0093] Throughout the description of this invention, reference is made to various patent applications and publications, each of which are herein incorporated by reference in their entirety.

Claims

What is claimed is:

(3)

or a pharmaceutically acceptable salt of each thereof wherein:

Z¹ is O, NR, or S, wherein R is hydrogen or Ci-C₆ alkyl,

wherein each R⁶ is independently Ci-C₆ alkyl, each X¹ and X² are independently O, or S; q is 1 or 2; each X³ is independently Ci-C₆ alkyl; t is 0, 1, 2, or 3, and

each R is defined as R⁷ herein, and is independently H or Ci-C₆ alkyl; and n is an integer from 0 to 5.

2. A compound of claim 1 of formula (1-A):

(1-A)

wherein R and D are defined as in formula (1);

of formula (2-A) or (2-B)

(2-A) (2-B)

wherein R, each Z independently, and D are defined as in formula (2);

or of formula (3 -A):

(3-A)

wherein R, Z , and D are defined as in formula (3).

3. The compound of claim 1 or 2, wherein R is methyl.

4. A pharmaceutical composition comprising a compound of any one of claims 1-3 and at least one pharmaceutically acceptable excipient.