WO2009114313A2

WO2009114313A2 - Methods for synthesizing antiviral compounds

Info

Publication number: WO2009114313A2
Application number: PCT/US2009/035684
Authority: WO
Inventors: Andrew S. Thompson; Hua Cheng; Stanislaw Pikul
Original assignee: International Partnership For Microbicides
Priority date: 2008-03-14
Filing date: 2009-03-02
Publication date: 2009-09-17
Also published as: WO2009114313A3

Abstract

New synthetic methods and intermediates are provided for the synthesis of antiviral compounds.

Description

IPMI-002PC

METHODS FOR SYNTHESIZING ANTIVIRAL COMPOUNDS

Related Applications

This application claims priority to U.S. Provisional Application No. 61/069,452, filed on March 14, 2008, the entire contents of which are hereby incorporated herein by reference.

Background of the Invention

The discovery and development of new therapeutic strategies against HIV has extended and improved the quality of life of infected patients. Thus far, 30 antiretroviral drugs have been approved by the Food and Drug Administration to treat individuals infected with HFV. These drugs fall into three major classes: reverse transcriptase inhibitors, protease inhibitors, and entry inhibitors, including fusion inhibitors. Unfortunately, currently available therapies have several limitations.

For example, as HIV reproduces itself, different strains of the virus emerge, some of which are resistant to antiretroviral drugs. Therefore, doctors recommend patients infected with HIV take a combination of antiretroviral drugs known as highly active antiretroviral therapy (HAART). This strategy, which typically combines at least three effective antiretroviral drugs from at least two different classes, has been shown to effectively suppress the virus when used properly.

Patients taking antiretroviral drugs, however, often have low adherence to complicated drug regimens. The currently recommended HAART regimen involves taking several antiretroviral drugs each day, some of which may require fasting and cause unpleasant side effects such as nausea and vomiting. In addition, antiretroviral drugs may cause more serious medical problems, including metabolic changes such as abnormal fat distribution, abnormal lipid and glucose metabolism, and bone loss. Additional problems associated with current therapies include drug-drug interactions, toxicity, poor tolerability, inconvenient dosing frequency, and food interactions, Thus, simpler, less toxic, and more effective drag regimens would be beneficial.

Entry inhibitors represent the newest generation of antivirals for the treatment of HIV. These inhibitors may prove beneficial for the growing number of HIV-infected individuals who have developed resistance to the currently available reverse transcriptase inhibitors and protease inhibitors. These compounds act by interfering with attachment of HIV gpl20 to either the CD4 T cell receptor or the CCR5/CXCR4, thereby blocking entry of the vims into the host cell (Biia «t al, J, Antinύcrβb, Chemother. 57(4):619 (2006)). Maraviroc and enfuvirtide are currently the only entry inhibitors that have been approved by the Food and Drug Administration (FDA). Thus, new entry inhibitors and efficient and effective methods for synthesizing them are needed in the art.

Summary of the Invention

The present invention provides novel methods for synthesizing entry inhibitors, such as the compounds of formula (IV). The present invention is based, at least in part, on the development of new synthetic methods and intermediates useful for the synthesis of anti-HIV drugs.

In one aspect, the invention provides a method for synthesizing a compound of formula (I):

The method includes contacting a compound of formula (II):

with a compound of formula (III):

under appropriate conditions substantially free of tin, such that a compound of formula (I) is synthesized, wherein R¹ is alkyl and X¹ and X² are each a halogen, a sulfonate, ZnCl, ZnBr, ZnI, MeZn, MgF, MgCl, MgBr, MgI, ZrCp₂Cl, or AlMe₂, provided that at least one of X¹ and X² is a halogen or a sulfonate, and at least one of X¹ and X² is ZnCl, ZnBr, ZnI, MeZn, MgF, MgCl, MgBr, MgI, ZrCp₂Cl, or AlMe₂.

In a further embodiment, the invention also provides compounds of formula

wherein X³ is a halogen.

In yet another embodiment, the invention pertains, at least in part, to compounds of formula (III):

wherein X² is ZnCl, ZnBr, ZnI, MeZn, ZrCp₂Cl, or AlMe₂.

In another further embodiment, the invention also pertains, at least in part, to compositions comprising a compound of formula (IV):

and pharmaceutically acceptable salts thereof; wherein R¹ is alkyl and said composition is substantially free of tin.

In another further embodiment, the invention also provides compounds of formula (I):

wherein R¹ is alkyl. In yet another further embodiment, the invention pertains, at least in part, to compounds of formula (Ha):

wherein R¹ is alkyl and X³ is a halogen.

In yet another further embodiment, the invention pertains, at least in part, to compounds of formula (II):

wherein R¹ is alkyl and X¹ is ZnCl, ZnBr, ZnI, MeZn, ZrCp₂Cl, or AlMe₂.

In another aspect, the present invention provides compounds prepared by the methods described herein.

Other features and advantages of the invention will be apparent from the following detailed description and claims.

Detailed Description of the Invention

The present invention provides novel methods for synthesizing entry inhibitors, such as the compounds of formula (IV). The present invention is based, at least in part, on the development of new synthetic methods and intermediates useful for the synthesis of anti-HIV drugs. In one aspect, the invention provides methods for synthesizing a compound of formula (I):

(D The method comprises contacting a compound of formula (II):

with a compound of formula (III):

under appropriate conditions substantially free of tin such that a compound of formula (I) is synthesized, wherein R¹ is alkyl and X¹ and X² are each a halogen, a sulfonate, ZnCl, ZnBr, ZnI, MeZn, MgF, MgCl, MgBr, MgI, ZrCp₂Cl, or AlMe₂, provided that at least one of X¹ and X² is a halogen or a sulfonate, and at least one of X¹ and X² is ZnCl, ZnBr, ZnI, MeZn, MgF, MgCl, MgBr, MgI, ZrCp₂Cl, or AlMe₂. In a further embodiment, X¹ is chlorine and X² is ZnBr, or, preferably, ZnCl, MgBr or MgCl.

The term "appropriate conditions" includes conditions necessary for the compound of formula (II) and the compound of formula (III) to be coupled to form the compound of formula (I). The appropriate conditions may comprise reagents, solvent, atmosphere composition, time, pressure, catalysts, and other variables known to those of skill in the art that may effect the outcome and yield of a chemical reaction. For example, for the synthesis of certain compounds of formula (I) of the invention, it may be necessary to perform multistep syntheses after or before the coupling to yield the desired compound of formula (I) of the invention. Furthermore, the appropriate conditions may comprise several reaction conditions (optionally with purification of the intermediates) and intermediates. Preferably, the appropriate conditions are substantially free of tin (e.g., less than about 1 ppm of tin) and include those described in the Examples section below. The term "substantially free of tin" refers to reaction conditions which can be determined to comprise about 2% (by weight) or less of tin which may be measured, for example, by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). For example, the reaction conditions (or a composition) may comprise about 1.5% or less, about 1% or less, about 0.5% or less, about 0.1% or less, about 0.01% or less, about 0.001% or less, or about 0.0001% or less of tin. Conditions substantially free of tin are generally considered to be better suited for large scale manufacturing. There are a number of problems associated with coupling reactions including tin. For example, tin reagents useful for these targets can be very expensive (~$60 per gram), are only available in small quantities (100-200 grams) from a limited number of vendors (such as Matrix or Frontier Scientific), and have a lead time of several months. Application of tin-based coupling reagents (e.g., a Stille reaction) is frequently associated with significant purification problems resulting in product contamination with tin-containing byproducts. In addition, tin is a toxic metal which presents difficulties to large scale manufacturing. The appropriate conditions contemplated by the present invention may comprise a palladium catalyst. The term "palladium catalyst" includes catalysts which comprise palladium, wherein palladium is bound by one or more ligands. Furthermore, palladium may be bound by one or more halogen atoms. Palladium may also be bound by one or more alkali metals. Palladium catalysts are known in the art and include, for example, L₂Pd X₂ and L₄Pd, wherein L represents a ligand and X represents a halogen atom. Examples of ligands may include, but are not limited to, triphenylphosphine, triisopropylphosphine, tricyclopentylphosphine, di-te/t-butyl(methyl)phosphine, άi-tert- butyl(o-biphenyl)phosphine, di-cyclohexyl(o-biphenyl)phosphine, tή-tert- butylphosphine, trio-tolylphosphine, tricyclohexylphosphine, trifuran-2-ylphosphine, benzonitrile, acetonitrile, acetate, acetylacetonate (AcAc), bis-dibenzylidine acetone (dba), Bis(2-diphenylphosphinophenyl)ether (DPEphos), 1,2-

Bis(dicyclohexylphosphino)ethane (dcpe). l,3-bis(diphenylphosphino)propane (dppp), 1,2-Bis(diphenylphosphino)ethane (dppe), 2,2'-bis(diphenylphosphino)-l,l'-binaphthyl (BINAP), and diphenylphosphino ferrocene (dppf). Examples of palladium catalysts include, but are not limited to, PdCl₂(dppf)₂,

PdCl₂(PPh₃)₂, PdCl₂(PhCN)₂, PdCl₂(MeCN)₂, Pd[P(o-Tol)₃]₂Cl₂, Pd(PPh₃)₄, Na₂PdCl₄, Li₂PdCl₄, Pd(dba)₂, Pd₂(dba)₃, Pd₂(dba)₃ -CHCl₃, Pd(OAc)₂, Pd[(r-Bu)₃P]₂, Cl₂Pd(DPEphos), Cl₂Pd(dppp), Pd(AcAc)₂ and Cl₂Pd(dppf).

Alternatively, appropriate conditions, as contemplated herein, may comprise a nickel catalyst such as Ni(PPh₃)₄, Ni(PPh₃)₂Cl₂, Ni(PPh₃)₂Br₂, NiBr₂, NiCl₂, Ni(AcAc)₂, Ni(dcpe)₂Cl₂, Ni(dppp)₂Cl₂, and Ni(dppe)₂Cl₂.

Furthermore, the appropriate conditions, as contemplated herein, may include the use of a polar, aprotic solvent such as diethylether, diisopropylether, ditertbutylether, dimethoxyethane (DME), methyl tetrahydrofuran, N-methylpyrrolidone (NMP), acetonitrile, dimethylsulfoxide (DMSO), hexamethylphosphoric triamide (HMPA), N₅N- dimethylformamide (DMF), dimethylacetamide (DMA), N-methylimidazole (NMI), toluene, dioxane or, preferably, tetrahydrofuran (THF). The appropriate conditions include the selection of a temperature such that the desired reaction of the reactants take place. In one embodiment, the reaction temperature is between about 0 ⁰C to about 110 ⁰C, or between about 20 ⁰C to about 90 ⁰C, or between about 40 ⁰C to about 80 ⁰C, or between about 50 ⁰C to about 70 ⁰C, about 60 ⁰C or about 58 ⁰C. Furthermore, the appropriate conditions may include cooling the reaction to about room temperature, as appropriate.

The appropriate conditions may also include the use of additives such as ZnBr₂, ZnCl₂, InCl₃, or diisobutylaluminium hydride (DIBAL-H).

Preferably, the appropriate conditions are selected such that the yield of the compound of formula (I) is at least about 40% or greater, about 50% or greater, about

60% or greater, about 70% or greater, about 75% or greater, about 80% or greater, about 85% or greater, or about 90% or greater.

The term "sulfonate" includes, but is not limited to, triflate, mesylate, tresylate, nonaflate, tosylate, brosylate, and nosylatebesylate. The term "about" refers to within 10%, preferably within 5%, and more preferably within 1% of a given value or range. The term "about" also includes within an acceptable standard error of the mean, when considered by one of ordinary skill in the art.

The term "contacting" includes any interaction between the compounds such that the desired reaction takes place.

The term "alkyl" includes saturated aliphatic groups, including straight-chain alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.), branched-chain alkyl groups (e.g., isopropyl, tert-butyl, isobutyl, etc.), cycloalkyl (alicyclic) groups (e.g., cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl), alkyl substituted cycloalkyl groups, and cycloalkyl substituted alkyl groups. The term alkyl further includes alkyl groups, which can further include oxygen, nitrogen, sulfur or phosphorous atoms replacing one or more carbons of the hydrocarbon backbone. In certain embodiments, a straight chain or branched chain alkyl has 6 or fewer carbon atoms in its backbone (e.g., C₁-C₆ for straight chain, C₃-C₆ for branched chain), and more preferably 4 or fewer. Likewise, preferred cycloalkyls have from 3-8 carbon atoms in their ring structure, and more preferably have 5 or 6 carbons in the ring structure. The term C₁-C₆ includes alkyl groups containing 1 to 6 carbon atoms.

Moreover, the term "alkyl" includes both "unsubstituted alkyls" and "substituted alkyls", the latter of which refers to alkyl moieties having substituents replacing a hydrogen on one or more carbons of the hydrocarbon backbone. Such substituents can include, for example, alkenyl, alkynyl, halogen, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, cyano, amino (including alkylamino, dialkylamino, arylamino, diarylamino, and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfates, alkylsulfinyl, sulfonate, sulfamoyl, sulfonamide, nitro, trifluoromethyl, cyano, azido, heterocyclyl, alkylaryl, or an aromatic or heteroaromatic moiety. Cycloalkyls can be further substituted, e.g., with the substituents described above. An "alkylaryl" or an "arylalkyl" moiety is an alkyl substituted with an aryl (e.g., phenylmethyl (benzyl)). The term "alkyl" also includes the side chains of natural and unnatural amino acids. Unless the number of carbons is otherwise specified, the term "lower alkyl" includes an alkyl group, as defined above, but having from one to five carbon atoms in its backbone structure.

In another embodiment, the invention pertains to a method for synthesizing a compound of formula (III), wherein X² is ZnCl, ZnBr, ZnI, MeZn, ZrCp₂Cl, or AlMe₂, preferably ZnCl. The method comprises contacting a metal reagent with a Grignard reagent of formula (Ilia), under appropriate transmetallating conditions such that a compound of formula (III) is formed. The compound of formula (Ilia) is:

wherein X³ is a halogen.

In yet another embodiment, the invention pertains to a method for synthesizing a compound of formula (II), wherein R¹ is alkyl and X¹ is ZnCl, ZnBr, ZnI, MeZn, ZrCp₂Cl, or AlMe₂. The method comprises contacting a metal reagent with a Grignard reagent of formula (Ha), under appropriate transmetallating conditions such that a compound of formula (II) is formed. The compound of formula (Ha) is:

wherein X³ is a halogen.

The term "transmetallating conditions" includes agents and conditions which allow compounds of formula (III) to be formed. The transmetallating conditions may comprise reagents, solvent, atmosphere composition, time, pressure, catalysts, and other variables known to those of skill in the art that may effect the outcome and yield of a chemical reaction.

For example, the transmetallating conditions, as contemplated by the present invention, include reaction temperatures of between about -78 ⁰C to about 80 ⁰C, or between about -50 ⁰C to about 25 ⁰C, or between about -20 ⁰C to about 0 ⁰C, or between about -15 ⁰C to about -5 ⁰C, or about -10 ⁰C. Furthermore, the transmetallating conditions may include warming the reaction to about room temperature.

Furthermore, the transmetallating conditions, as contemplated by the present invention, may include the use of a polar, aprotic solvent such as diethylether, diisopropylether, ditertbutylether, dimethoxyethane (DME), methyl tetrahydrofuran, N- methylpyrrolidone (NMP), acetonitrile, dimethylsulfoxide (DMSO), hexamethylphosphoric triamide (HMPA), N,N-dimethylformamide (DMF), dimethylacetamide (DMA), N-methylimidazole (NMI), toluene, dioxane or, preferably, tetrahydrofuran (THF). The term "metal reagent," as used herein, includes zinc, zirconium and aluminum compounds such as zinc dust, ZnCl₂, ZnBr₂, ZnI₂, Me₂Zn, Cl₂ZrCp₂. and

AlMe₃.

Furthermore, the transmetallating conditions include using between about 0.2 and 0.8 equivalents, or between about 0.25 and 0.75 equivalents, or between about 0.3 and 0.7 equivalents, or between about 0.35 and 0.65 equivalents, or between about 0.4 and 0.6 equivalents, or between about 0.45 and 0.55 equivalents, or about 0.5 equivalents of the metal reagent, e.g., ZnCl₂, to one equivalent of the compound of formula (Ilia).

The term "Grignard reagent" includes compounds which comprise organomagnesium halides. Examples of Grignard reagents include RMgX, wherein R is alkyl, alkenyl, alkynyl, or aryl, and wherein X is bromine, iodine or, preferably, chlorine. For example, Grignard reagents of the invention may be formed by reacting, for example a compound of formula (III), e.g., iodopyrazine, with alkyl-MgCl.

Examples of alkyl-MgCl which may be used include w-butylmagnesium chloride, tert- butylmagnesium chloride, sec-butylmagnesium chloride, ethylmagnesium chloride, and isopropyl magnesium chloride.

Furthermore, the Grignard reagent may be formed by reacting about one equivalent of, for example, iodopyrazine with between about 0.3 and about 1.7 equivalents, or between about 0.4 and about 1.6 equivalents, or between about 0.5 and about 1.5 equivalents, or between about 0.6 and about 1.4 equivalents, or between about

0.7 and about 1.3 equivalents, or between about 0.8 and about 1.2 equivalents, or between about 0.9 and about 1.1 equivalents, or about one equivalent of alkyl-MgCl. The terms "alkenyl" and "alkynyl" refer to unsaturated aliphatic groups analogous to alkyls, but which contain at least one double or triple carbon-carbon bond respectively. The term "aromatic group" or "aryl group" includes unsaturated and aromatic cyclic hydrocarbons containing one or more rings. Aryl groups may also be fused or bridged with alicyclic or heterocyclic rings that are not aromatic so as to form a polycycle (e.g., tetralin).

In another embodiment, the invention includes compounds of formula (Ilia) wherein X³ is a halogen, such as fluorine, chlorine, bromine, and preferably iodine. In another embodiment, the invention includes compounds of formula (III) wherein X² is ZnCl.

In another embodiment, the invention includes compounds of formula (Ha) wherein X³ is a halogen, such as fluorine, chlorine, bromine, and preferably iodine.

In another embodiment, the invention includes compounds of formula (II) wherein R¹ is alkyl and X¹ is ZnCl. In another embodiment, the invention includes compositions comprising compounds of formula (IV), and pharmaceutically acceptable salts thereof:

wherein R¹ is alkyl and said composition is substantially free of tin. Preferably, the composition of the invention comprises no detectable tin as determined by ICP-MS (e.g., less than about 1 ppm of tin). In another embodiment, the composition includes an acceptable carrier. In a further embodiment, the composition meets FDA requirements for metal content.

The invention also pertains, at least in part, to pharmaceutical compositions comprising an effective amount of a compound of formula (IV) and a pharmaceutically acceptable carrier, wherein the pharmaceutical composition is substantially free of tin. Preferably, the effective amount of the compound of formula (IV) is effective to treat a viral disorder, e.g., HIV. The compounds of formula (IV) are preferably synthesized using the methods and/or intermediates described herein.

The invention also pertains, at least in part, to compositions comprising compounds synthesized using the methods of the invention, e.g., compounds of formulae (I), (IV), and other compounds and intermediates described herein. The language "pharmaceutically acceptable carrier" includes substances capable of being coadministered with the compound(s), and which allow both to perform their intended function, e.g., to treat HIV. Suitable pharmaceutically acceptable carriers include but are not limited to water, salt solutions, alcohol, vegetable oils, polyethylene glycols, gelatin, lactose, amylose, magnesium stearate, talc, silicic acid, viscous paraffin, perfume oil, fatty acid monoglycerides and diglycerides, petroethral fatty acid esters, hydroxymethyl-cellulose, or polyvinylpyrrolidone. The pharmaceutical preparations can be sterilized and if desired mixed with auxiliary agents, e.g., lubricants, preservatives, stabilizers, wetting agents, emulsifiers, salts for influencing osmotic pressure, buffers, colorings, flavorings and/or aromatic substances and the like which do not deleteriously react with the active compounds of the invention.

The compounds of the invention that are basic in nature are capable of forming a wide variety of salts with various inorganic and organic acids. The acids that may be used to prepare pharmaceutically acceptable acid addition salts of the compounds of the invention that are basic in nature are those that form non-toxic acid addition salts, i.e., salts containing pharmaceutically acceptable anions, such as the hydrochloride, hydrobromide, hydroiodide, nitrate, sulfate, bisulfate, phosphate, acid phosphate, isonicotinate, acetate, lactate, salicylate, citrate, acid citrate, tartrate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucaronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate and palmoate [i.e., l,l'-methylene-bis-(2-hydroxy- 3-naphthoate)] salts. Although such salts must be pharmaceutically acceptable for administration to a subject, e.g., a mammal, it is often desirable in practice to initially isolate a compound of the invention from the reaction mixture as a pharmaceutically unacceptable salt and then simply convert the latter back to the free base compound by treatment with an alkaline reagent and subsequently convert the latter free base to a pharmaceutically acceptable acid addition salt. The acid addition salts of the base compounds of this invention are readily prepared by treating the base compound with a substantially equivalent amount of the chosen mineral or organic acid in an aqueous solvent medium or in a suitable organic solvent, such as methanol or ethanol. Upon careful evaporation of the solvent, the desired solid salt is readily obtained. The preparation of other compounds of the invention not specifically described in the foregoing experimental section can be accomplished using combinations of the reactions described above that will be apparent to those skilled in the art. The compounds of the invention and pharmaceutically acceptable salts thereof can be administered via either the oral, parenteral or topical routes. In general, these compounds are most desirably administered in effective dosages, depending upon the weight and condition of the subject being treated and the particular route of administration chosen. Variations may occur depending upon the species of the subject being treated and its individual response to said medicament, as well as on the type of pharmaceutical formulation chosen and the time period and interval at which such administration is carried out. In a preferred embodiment, the compounds prepared by the methods described herein are administered using an intra- vaginal device, such as a vaginal ring; a vaginal suppository; a semi-solid formulation such as a gel, cream, or lotion; or a film. Such formulations are well known in the art and described in, for example, U.S. Patent No. 5,972,372; U.S. Patent No. 6,126,958; U.S. Patent No. 4,596,576; U.S. Patent No. 4,888,074; U.S. Patent No. 4,822,616; and U.S. Patent No. 4,564,362, the entire contents of each of which are incorporated herein by reference.

The pharmaceutical compositions of the invention may be administered alone or in combination with other known compositions for treating HIV in a subject, e.g., a mammal. Preferred mammals include primates, such as humans, chimpanzees, or gorillas; farm animals (e.g. cows, sheep, pigs, horses, goats); lab animals (e.g. rats, mice, monkeys) and pets (e.g. cats, dogs, ferrets). The language "in combination with" a known composition is intended to include simultaneous administration of the composition of the invention and the known composition; administration of the composition of the invention first, followed by the known composition; and administration of the known composition first, followed by the composition of the invention. Any of the therapeutic compositions known in the art for treating HIV can be used in combination with the compounds of the invention.

The compounds of the invention may be administered alone or in combination with pharmaceutically acceptable carriers or diluents by any of the routes previously mentioned, and the administration may be carried out in single or multiple doses. For example, the novel compounds of this invention can be administered advantageously in a wide variety of different dosage forms, i.e., they may be combined with various pharmaceutically acceptable inert carriers in the form of tablets, capsules, lozenges, troches, hard candies, powders, sprays (e.g. aerosols), creams, salves, suppositories, jellies, gels, pastes, lotions, ointments, aqueous suspensions, injectable solutions, elixirs, syrups, and the like. Such carriers include solid diluents or fillers, sterile aqueous media and various non-toxic organic solvents, etc. Moreover, oral pharmaceutical compositions can be suitably sweetened and/or flavored. In general, the therapeutically- effective compounds of this invention are present in such dosage forms at concentration levels ranging from about 5.0% to about 70% by weight.

For intra- vaginal administration, the intra- vaginally administered drug of the invention may be coated onto the intra-vaginal device, impregnated or absorbed into the device, or applied to the device by any suitable means that allows the compound to be attached or bonded to the device, yet which allows the compound to be available for absorption into the vaginal mucosa, as will be clear to those of skill in the art.

For oral administration, tablets containing various excipients such as microcrystalline cellulose, sodium citrate, calcium carbonate, dicalcium phosphate and glycine may be employed along with various disintegrants such as starch (and preferably corn, potato or tapioca starch), alginic acid and certain complex silicates, together with granulation binders like polyvinylpyrrolidone, sucrose, gelatin and acacia. Additionally, lubricating agents such as magnesium stearate, sodium lauryl sulfate and talc are often very useful for tabletting purposes. Solid compositions of a similar type may also be employed as fillers in gelatin capsules; preferred materials in this connection also include lactose or milk sugar as well as high molecular weight polyethylene glycols. When aqueous suspensions and/or elixirs are desired for oral administration, the active ingredient may be combined with various sweetening or flavoring agents, coloring matter or dyes, and, if so desired, emulsifying and/or suspending agents as well, together with such diluents as water, ethanol, propylene glycol, glycerin and various like combinations thereof. The compositions of the invention may be formulated such that the compositions are released over a period of time after administration.

For parenteral administration (including intraperitoneal, subcutaneous, intravenous, intradermal or intramuscular injection), solutions of a therapeutic compound of the present invention in either sesame or peanut oil or in aqueous propylene glycol may be employed. The aqueous solutions should be suitably buffered (preferably pH greater than 8) if necessary and the liquid diluent first rendered isotonic. These aqueous solutions are suitable for intravenous injection purposes. The oily solutions are suitable for intraarticular, intramuscular and subcutaneous injection purposes. The preparation of all these solutions under sterile conditions is readily accomplished by standard pharmaceutical techniques well known to those skilled in the art. For parenteral application, examples of suitable preparations include solutions, preferably oily or aqueous solutions as well as suspensions, emulsions, or implants, including suppositories. Therapeutic compounds may be formulated in sterile form in multiple or single dose formats such as being dispersed in a fluid carrier such as sterile physiological saline or 5% saline dextrose solutions commonly used with injectables.

Additionally, it is also possible to administer the compounds of the present invention topically. Examples of methods of topical administration include transdermal, buccal or sublingual application. For topical applications, the compounds of the invention can be suitably admixed in a pharmacologically inert topical carrier such as a gel, an ointment, a lotion or a cream. Such topical carriers include water, glycerol, alcohol, propylene glycol, fatty alcohols, triglycerides, fatty acid esters, or mineral oils. Other possible topical carriers are liquid petrolatum, isopropylpalmitate, polyethylene glycol, ethanol 95%, polyoxyethylene monolauriate 5% in water, sodium lauryl sulfate 5% in water, and the like. In addition, materials such as anti-oxidants, humectants, viscosity stabilizers and the like also may be added if desired.

For parenteral application, particularly suitable are tablets, dragees or capsules having talc and/or carbohydrate carrier binder or the like, the carrier preferably being lactose and/or corn starch and/or potato starch. A syrup, elixir or the like can be used wherein a sweetened vehicle is employed. Sustained release compositions can be formulated including those wherein the active component is protected with differentially degradable coatings, e.g., by microencapsulation or multiple coatings. It will be appreciated that the actual preferred amounts of active compounds used in a given therapy will vary according to the specific compound being utilized, the particular compositions formulated, the mode of application, or the particular site of administration. Optimal administration rates for a given protocol of administration can be readily ascertained by those skilled in the art using conventional dosage determination tests conducted with regard to the foregoing guidelines.

The present invention also pertains to the use of a compound of formula (IV), for the preparation of a medicament substantially free of tin. The medicament may include a pharmaceutically acceptable carrier and the compound in an effective amount, e.g., an effective amount to treat a HIV. In another embodiment, the present invention provides methods for treating a subject for HIV, by administering to the subject an effective amount of a composition comprising a compound of formula (IV), or a pharmaceutically acceptable salt thereof, such that the subject is treated, wherein the composition is substantially free of tin.

The term "treating" includes the application or administration of a composition or compound of the invention to a subject, or application or administration of a composition or compound of the invention to a cell or tissue from a subject, who has HIV, with the purpose of curing, healing, alleviating, relieving, altering, remedying, ameliorating, preventing, improving, or affecting HIV. The term "treating" refers to any indicia of success in the treatment or amelioration of an injury, pathology or condition, including any objective or subjective parameter such as abatement; remission; diminishing of symptoms or making the injury, pathology or condition more tolerable to the subject; slowing in the rate of degeneration or decline; making the final point of degeneration less debilitating; improving a subject's physical or mental well-being. Treatment may be therapeutic or prophylactic. The treatment or amelioration of symptoms can be based on objective or subjective parameters; including the results of a physical examination.

The term "subject" includes living organisms in which HIV can occur, or which are susceptible to HIV. Examples of subjects include humans, monkeys, deer, cows, rabbits, sheep, goats, mice, rats, and transgenic species thereof. Administration of the compositions or compounds of the present invention to a subject to be treated can be carried out using known procedures, at dosages and for periods of time effective to treat or prevent HIV.

5 This invention is further illustrated by the following examples which should not be construed as limiting.

EXAMPLES

10 Example 1: Synthesis of Iodopyrazine (1) from Chloropyrazine

NaI, HOAc, H₂SO₄, MeCN, f N reflux,4-6h, ca. 58% f Υ

A reaction mixture of chloropyrazine (7.5 ml, 83 mmol), NaI (30.3 g, 202 15 mmol), HOAc (9.6 ml, 168 mmol) and H₂SO₄ (0.5 ml) in MeCN (105 ml) was heated at reflux for 4.5 hours. The solvent was removed and water (120 ml) was added. After the solution was basified with saturated NaHCO₃, it was extracted with dichloromethane (DCM) (2 x 125 ml). The DCM layers were combined, washed with saturated Na₂S₂O₃, brine and dried. The removal of solvent gave crude iodopyrazine as an oil (12.33 g, 20 71%). Analysis by ¹H NMR showed there was less than about 10 mol% of chloropyrazine in the oil. Another batch of chloropyrazine (50 g, 437 mmol) was also converted into crude iodopyrazine (about 65 g) by the same procedure. These two batches of crude iodopyrazine were combined and distillation of the crude iodopyrazine under reduced pressure (about 0.75 torr, bp 47°C) gave pure compound 64 g (60%). 25

¹H-NMR (CDCl₃, 300MHz) 8.40 (dd, /=1.8, 2.4Hz, IH), 8.51 (d, /=2.4Hz,lH), 8.87 (d, /=1.5Hz,lH).

Example 2: Synthesis of Coupled Azaindole (3) from Iodopyrazine (1)

O Q C₄H₃IN₂ = 205.98 C₁₂H₁₀N₄O = 226.23 To a solution of iodopyrazine 1 (45.8 g, 0.222 mol) in tetrahydrofuran (THF) (460 ml) at -18°C, BuMgCl (2 M in THF, 108 ml, 216 mmol) was added dropwise via an addition funnel over 20 minutes. The internal temperature of the resulting suspension was raised to -1O⁰C after addition. The mixture was stirred for another 40 minutes during which time the internal temperature dropped to -18⁰C. Then, ZnCl₂ (0.5 M in THF, 220 mmol) was added via addition funnel over 15 minutes. The NaCl-ice bath was removed after addition and the mixture was warmed up to room temperature over 2 hours and was stirred at room temperature for another 0.5 hours. Chloroazaindole 2 (12.95 g, 71 mmol) and PdCl₂(dppf)2 (5.8 g, 7.1 mmol) were added into the mixture and mixture heated at 58°C for 6 hours, then stirred at room temperature overnight. Analysis by HPLC showed >20:l ratio of product to starting material.

The reaction was quenched with NH₄Cl (36 N aqueous, 25 ml) and the resulting inorganic salt was filtered off and washed with THF. The filtrate was concentrated to about 200 ml and IL of dichloromethane was added. The solution was washed with brine (3x500 ml) and dried (Na₂SO₄). The solution was concentrated and the residue was absorbed onto silica gel (25 g), then put on top of a silica gel (105 g) column and eluted with hexanes and EtOAc(hexanes:EtOAc=3:l to 0:1). Removal of the solvent gave crude coupled azaindole 3 which was then heated in refluxing EtOAc (350 ml) for about 0.5 hours. After an insoluble sparkling dark red solid was filtered off, and EtOAc was removed, a brown solid (14.86 g) was obtained, which was then dissolved in a refluxing solution of hexanes (40 ml) and EtOAc (120 ml). The resulting solution was cooled to room temperature and the product isolated by filtration to give a brown solid 3 (9.56 g, >99% pure by HPLC, 60% yield).

¹H NMR (DMSO-d_6, 300 MHz) (δ, ppm): 4.02(s, 3H), 6.63-6.65(m, IH), 7.56(t, / = 2.7Hz, IH), 8.04(s, IH), 8.64(d, / = 2.7Hz, IH), 8.74-8.75(m, IH), 9.62(d, / = 1.5Hz, IH), 11.78 (br, s, IH); LCMS: m/e 227 (M+H)⁺.

Analysis by ICP-MS showed <1 ppm tin, 1669 ppm iron, 83ppm zinc.

Example 3: Synthesis of Acylated Azaindole (4) from Coupled Azaindole (3)

C₁₂H₁₀N₄O = 226.23 C₁₅H₁₂N₄O₄ = 312.28

3 4

To a solution of dichloromethane and nitromethane (4:1, 200 ml) in a 500 ml 3- neck flask cooled with ice-water bath, was added AlCl₃ (22.3g, 168 mmoles) in portions. Then, 3 (4.75 g, 21.0 mmol) was added into the solution in portions. The internal temperature was raised from 1°C to 6⁰C then back tol°C. ClCOCO₂Me (3.9ml, 41.1 mmoles) was added into the solution dropwise using a syringe in over about 5 minutes. The resulting homogeneous solution was stirred at 0⁰C for 10 minutes and then put in the cold room (about 0⁰C ) for 15 hours without stirring. Analysis by HPLC after 15 hours showed that the ratio of 3:4:5 was 0:92:3. The reaction solution was then poured into cold 25% aqueous NH₄OAc solution (500 ml) in portions. The organic layer was separated and the aqueous layer was extracted with DCM (300 ml, then 2x150 ml). The combined organic layers were washed with brine (2x300 ml) and dried (Na₂SO₄). Removal of solvent in vacuo gave ester 4 as a solid (4.85 g, 74%).

Analysis by ICP-MS showed <1 ppm tin, 1535 ppm iron, 103ppm zinc.

Example 4: Synthesis of Acylated Azaindole (5) from Acylated Azaindole (4)

C₁₅H₁₂N₄O₄ = 312.28 C₁₄H₁₀N₄O₄ = 298.25 4⁵

To suspension of ester 4 (10.00 g, 32.1 mmol) in methanol (150 ml), K₂CO₃ (1

M, 150 ml, 150 mmol) was added. After the reaction mixture was stirred at room temperature for 1 hour methanol was removed in vacuo. The remaining reaction mixture was diluted with water to 1.2 L and washed with MTBE (2x400 ml). The aqueous phase was acidified with HCl (2 M, 185 ml, 370 mmol) to pH=l. The acid 5 (a grey solid) thus formed was filtered off and dried (9.29 g, 97% yield).

Analysis by ICP-MS showed <1 ppm tin, 143 ppm Fe, 96 ppm Zn.

Example 5: Synthesis of Nitrile 6 from l-Boc-4-piperidone

1 ) NaHMDS, THF,

2) TFA, 3)NaHCO₃,

Boc-N >=O ^{4) HCI} . HHCCII

6

NaHMDS (2 M in THF, 8.6 ml, 17.2 mmol) was added into a solution of 1-Boc- 4-piperidone (3.0 g, 14.4 mmol) and benzyl cyanide (2.0 ml, 17.2 mmol) in THF (60 ml) at room temperature. The reaction mixture was heated at 50-60⁰C (oil bath) until benzyl cyanide was consumed (as monitored by HPLC). The reaction was quenched by the addition of methanol (12 ml), and the solvent was removed in vacuo. TFA (30 ml, 402 mmol) was added to the residue and the resulting mixture was stirred at room temperature overnight. Most of the TFA was removed in vacuo and saturated NaHCO₃ (100 ml) was added. The mixture was extracted with EtOAc (80 ml, 3x30 ml). The organic layers were combined and washed with brine, and dried (Na₂SO₄). After removal of the EtOAc, the remaining residue was dissolved in DCM (20 ml). The DCM solution was added dropwise to HCl (0.5 M in ether, 40 ml of 2M diluted to 160 ml with ether) at room temperature to form the hydrochloride salt of nitrile 6. The hydrochloride salt of nitrile 6 was then filtered off and was washed with ether (3x10 ml), and dried to afford 2.75 g of a yellow solid (81% yield).

xample 6: Synthesis of DS003 from Acylated Azaindole 5 and Nitrile 6

5 DS003

A 2 L flask was charged with acid 5 (9.29 g, 31.2 mmol), DIPEA (12.9 ml, 78 mmol), nitrile 6 (7.18 g, 36.3 mmol) and DMF (95 ml) subsequently. HATU (13.66 g, 35.9 mmol) was added the reaction mixture in portions over 10 minutes. The internal temperature rose to 27°C from 19°C. After the reaction mixture was stirred at room temperature for 3.5 hours, analysis by HPLC showed that the starting material was completely consumed. Ethanol (950 ml) was added and the resulting suspension was heated at reflux for lhour. The mixture was then cooled to room temperature and

DS003 was isolated by filtration and washed with ethanol (50 ml). The material was dried on a rotovap at 40-50⁰C then by using an oil pump at room temperature to afford 10.58 g of DS003 (71% yield, >99% purity by HPLC).

¹H NMR (CDCl_3, 300 MHz) (δ, ppm): 2.58-2.65 (m, 2H), 2.91-2.99 (m, 2H), 3.48- 3.51(m, IH), 3.68-3.78 (m, 2H), 3.95-3.99 (m, IH), 4.11 (s, 3H), 7.27-7.46 (m, 5H), 8.16 (d, J = 5.1Hz, IH), 8.21-8.25 (m, IH), 8.60 (s, 2H), 9.82 (d, J = 3.9 Hz, IH), 11.75 (br, IH); LCMS: m/e 479.3 (M+H)⁺.

Analysis by ICP-MS showed <1 ppm tin, 16 ppm Pd, 79 ppm iron, 102 ppm zinc.

EQUIVALENTS

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of the present invention and are covered by the following claims. The contents of all references, patents, and patent applications cited throughout this application are hereby incorporated by reference. The appropriate components, processes, and methods of those patents, applications and other documents may be selected for the present invention and embodiments thereof.

Claims

1. A method for synthesizing a compound of formula (I):

comprising: contacting a compound of formula (II):

with a compound of formula (III):

under appropriate conditions substantially free of tin such that a compound of formula (I) is synthesized, wherein R¹ is alkyl and X¹ and X² are each selected from the group consisting of halogen, a sulfonate, ZnCl, ZnBr, ZnI, MeZn, MgF, MgCl, MgBr, MgI, ZrCp₂Cl, and AlMe₂, provided that at least one of X¹ and X² is a halogen or a sulfonate, and at least one of X¹ and X² is ZnCl, ZnBr, ZnI, MeZn, MgF, MgCl, MgBr, MgI, ZrCp₂Cl, or AlMe₂.

2. The method of claim 1, wherein X¹ is chlorine.

3. The method of claim 1, wherein X is ZnCl.

4. The method of claim 1, wherein X is MgCl or MgBr.

5. The method of claim 1, wherein said appropriate conditions comprise a palladium catalyst.

6. The method of claim 5, wherein said palladium catalyst is L₄Pd or L₂PdCl₂.

7. The method of claim 6, wherein said palladium catalyst is PdCl₂(dppf)₂.

8. The method of claim 1, wherein said appropriate conditions further comprise using tetrahydrofuran.

9. The method of claim 1, wherein said compound of formula (I) is formed at a yield of about 50% or greater.

10. The method of claim 1, wherein said compound of formula (I) is formed substantially free of tin as measured by ICP-MS.

11. The method of claim 3, wherein the compound of formula (III) is formed by contacting a metal reagent with a Grignard reagent of formula (Ilia), under appropriate transmetallating conditions such that a compound of formula (III) is formed, wherein said compound of formula (Ilia) is:

wherein X³ is a halogen.

12. The method of claim 11, wherein said metal reagent is ZnCl₂.

13. The method of claim 12, wherein said appropriate transmetallating conditions comprise using about 0.5 equivalents of ZnCl₂ to one equivalent of the compound of formula (HIb).

14. The method of any one of claims 11-13, wherein said appropriate transmetallating conditions comprise contacting the metal reagent with the compound of formula (HIb) in an appropriate solvent at a temperature of about -10 ⁰C.

15. The method of claim 14, wherein said appropriate transmetallating conditions further comprise warming said conditions to room temperature.

16. The method of claim 14, wherein said appropriate solvent is tetrahydrofuran.

17. The method of claim 11, wherein said Grignard reagent is formed by reacting iodopyrazine with alkyl-MgCl.

18. The method of claim 17, wherein said alkyl-MgCl is nBuMgCl.

19. The method of claim 17, wherein said Grignard reagent is formed by reacting about one equivalent of iodopyrazine with between about 0.5 and 1.5 equivalents of alkyl-MgCl.

20. The method of claim 19, wherein said Grignard reagent is formed by reacting about one equivalent of iodopyrazine with one equivalent of alkyl-MgCl.

21. A compound of formula (Ilia) :

wherein X _r3 is a halogen.

22. The compound of claim 21, wherein X 3 is iodine

23. A compound of formula (III):

wherein X is ZnCl.

24. A composition comprising a compound of formula (IV), and pharmaceutically acceptable salts thereof:

wherein R¹ is alkyl and said composition is substantially free of tin.

25. The composition of claim 24, wherein said compound contains no detectable tin, as determined by ICP-MS.

26. The composition of claim 24, wherein said composition further comprises a pharmaceutically acceptable carrier.

27. The composition of claim 24, wherein said composition meets FDA requirements for metal content.

28. A method for treating a subject for HIV, comprising administering to said subject an effective amount of a composition of claim 24, such that said subject is treated.

29. A compound of formula (IV), and pharmaceutically acceptable salts thereof:

wherein R¹ is alkyl, and said compound is synthesized using the method of any one of claims 1-20.

30. A pharmaceutical composition comprising a compound of claim 29 and a pharmaceutically acceptable carrier.

31. A method for treating a subject for HIV, comprising administering to said subject an effective amount of a compound of claim 29, such that said subject is treated.

32. A compound of formula (I):

wherein R¹ is alkyl and said compound is synthesized using the method of any one of claims 1-20,.

33. A compound of formula (Ha):

wherein R¹ is alkyl and X³ is a halogen.

34. A compound of fo

wherein R¹ is alkyl and X¹ is ZnCl, ZnBr, ZnI, MeZn, ZrCp₂Cl, or AlMe₂.

35. The method of claim 1, wherein the compound of formula (II), wherein R¹ is alkyl and X¹ is ZnCl, ZnBr, ZnI, MeZn, ZrCp₂Cl, or AlMe₂, is formed by contacting a metal reagent with a Grignard reagent of formula (Ha), under appropriate transmetallating conditions such that a compound of formula (II) is formed, wherein said compound of formula (Ha) is:

wherein R¹ is alkyl and X³ is a halogen.