FORM 2 THE PATENTS ACT 1970 (Act 39 of 1970) COMPLETE SPECIFICATION (SECTION 10, rule 13) “PROCESSES FOR THE PREPARATION OF SIMVASTATIN" Glenmark Pharmaceuticals Limited, an Indian Company, registered under the Indian company's Act 1957 and having its registered office at B/2, Mahalaxmi Chambers, 22, Bhulabhai Desai Road Post Box No. 26511 Mumbai- 400 026, India THE FOLLOWING SPECIFICATION DESCRIBES THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119 to Provisional Application No. 60/564,420, filed April 22, 2004 and from Indian Provisional Application No. 480/MUM/2004 filed April 23, 2004 and entitled "PROCESS FOR THE PREPARATION OF SIMVASTATIN", the contents of which are incorporated by reference herein. BACKGROUND OF THE INVENTION 1. Technical Field The present invention generally relates to an improved process for the preparation of 3-hydroxy-3-methylglutaryl-coenzyme A inhibitors and their intermediates. 2. Description of the Related Art The present invention is directed to an improved process for the preparation of 3- hydroxy-3-methylglutaryl-coenzyme A inhibitors and their intermediates, e.g., simvastatin (also known as butanoic acid, 2,2-dimethyl-,l,2,3,7,8,8a-hexahydro-3,7-dimethyl-8-[2- (tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)-ethyl]-l-naphthalenyl ester, [1S- [la,3a,7P,8p(2S*,4S*),-8a(3]]). Simvastatin possesses the following structural formula: Generally, simvastatin is a synthetic lipid-lowering agent that acts as an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMG-CoA Reductase inhibitor). This enzyme catalyzes the conversion of HMG-CoA to mevalonate, an early and rate-limiting step in cholesterol biosynthesis. HMG-CoA reductase inhibitors are commonly referred to as "statins." Statins are therapeutically effective drugs used for reducing low 2 density lipoprotein (LDL) particle concentration in the blood stream of patients at risk for cardiovascular disease. Simvastatin is indicated for use for reducing elevated total cholesterol (total-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (Apo B), and high plasma triglycerides (TG), and to increase high-density lipoprotein cholesterol (HDL-C) in patients with primary hypercholesterolemia (heterozygous familial and nonfamilial) and mixed dyslipidemia (Fredrickson types Ha and IIb4); treating patients with hypertriglyceridemia (Fredrickson type IV hyperlipidemia); treating patients with primary dysbetalipoproteinemia (Fredrickson type III hyperlipidemia), and reducing total-C and LDL-C in patients with homozygous familial hypercholesterolemia as an adjunct to other lipid-lowering treatments (e.g., LDL apheresis). Simvastatin is sold under the trade name ZOCOR®. HMG-CoA reductase inhibitors such as, for example, lovastatin, pravastatin, simvastatin, mevastatin, atorvastatin, cerivastatin, fluvastatin and analogs thereof, may be derived by fermentation or by chemical modification. Lovastatin, pravastatin and mevastatin are natural fermentation products which possess a 2-mefhylbutyrate side chain at the Cs position of their hexahydronapthalene ring. Simvastatin is a semi-synthetic analog of lovastatin having a 2,2-dimethylbutyrate side chain at the C« position. The statins having a 2,2-dimethylbutyrate side chain, e.g. simvastatin, are synthesized because they are not naturally occurring compounds. U.S. Patent No. 4,444,784 ("the '784 patent") discloses simvastatin. The '784 patent further discloses a process for preparing simvastatin by (1) de-esterification of the 2-methylbutylrate side chain; (2) protection of the 4-hydroxy of the pyranone ring; (3) re-esterification to form the desired 2,2-dimethylbutylrate; and (4) deprotection of the 4-hydroxy group. The process of the '784 patent is lengthy and provides poor overall yields. One important aspect in the synthesis of simvastatin is the process of lactonization. Lactonization is a process where the hydroxyl acid loses one molecule of H2O to form an intra-molecular ester, also known as a lactone. Lactonization is an equilibrium process characterized generally, in the case of statins, by equation I: 3 Dihydroxy acid/ammonium salt Lactone + H2O or NH3 B A (I) This reaction is generally catalyzed by an acid. The acidity necessary for this reaction is either inherent in the substrate itself or added by a lactonization agent, such as a strong acid. In order to obtain a high yield of the lactone, the equilibrium of the reaction must be shifted to the right hand side of the equation. The common way of shifting the equilibrium to the right is to remove a reaction product from the reaction mixture. One way of shifting the equilibrium to produce higher yields of lactone is by removing the H2O produced by the reaction through azeotropic distillation. To perform the azeotropic distillation, either the free acid or the ammonium salt is heated in a suitable solvent, for example, toluene, butyl acetate, ethyl acetate, and cyclohexane, to a boiling point that forms an azeotrope mixture of solvent and water. The water, having a lower boiling point, is distilled off first and the reaction equilibrium is shifted to the right hand side towards the formation of lactone. The speed of water (and optionally ammonia) removal may be increased by passing a stream of inert gas through the reaction mixture. The ambient acidity of the statin acid is believed to be responsible for the lactonization reaction at these high temperatures. U.S. Patent No. 5,763,646 discloses a process for the preparation of simvastatin using lovastatin or a mevinolinic acid (the open ring form of lovastatin) salt as a starting material. The lovastatin or mevinolinic acid salt is reacted with an n-alkylamine or a cycloalkylamine of formula RNH2, wherein R is C3-C6, e.g., cyclopropylamine or n-butyl amine, without requiring hydroxyl protection and subsequent deprotection. However, the use of the amine in opening the pyranone ring results in the formation of a lovastatin amide intermediate which may in turn undergo undesired side reaction due to the presence of its amide hydrogen atom. The undesired side reactions may further occur with the methylating agent thereby lowering the overall yield. U.S. Patent No. 6,603,022 discloses a process for the preparation of simvastatin using lovastatin as a starting material. The process involves (a) reacting lovastatin with a secondary 4 amine such as diethylamine, pyrrolidine or piperidine to form an amide intermediate of the formula: wherein R1 and R2 are each independently an alkyl, heteroalkyl, aryl or heteroaryl moiety, or R1 and R2, taken together, form a heterocyclic moiety having 5-8 atoms; wherein each of the foregoing alkyl and heteroalkyl moieties may be linear or branched, substituted or unsubstituted, cyclic or acyclic or saturated or unsaturated, and each of the foregoing heterocyclic, aryl and heteroaryl moieties may be substituted or unsubstituted; (b) methylating the C-8 butyrate side chain of the amide intermediate to form the corresponding 2,2-dimethylbutyrate intermediate, (c) hydrolyzing the 2,2-dimethylbutyrate intermediate to the corresponding free carboxylic acid and (d) effecting lactonization of the carboxylic acid intermediate to form simvastatin. This process is a four step process which includes the necessary step of hydrolyzing the 2,2-dimethylbutyrate intermediate to the corresponding free carboxylic acid prior to lactonization to form simvastatin. Accordingly, there remains a need for improved processes for the preparation of simvastatin and pharmaceutically acceptable salts thereof that requires less steps thereby resulting in a more efficient process. There also remains a need for improved processes for the preparation of simvastatin and pharmaceutically acceptable salts thereof that eliminates and reduces the problems of the prior art on a commercial scale and in a convenient and cost efficient manner. 5 SUMMARY OF THE INVENTION One aspect of the present invention provides improved processes for the preparation of simvastatin and pharmaceutically acceptable salts thereof and its intermediates. The processes include at least the formation of a carboxylic acid amine salt in an aqueous medium, thus avoiding the use of an organic solvent. It also provides for lithiation of the carboxylic acid amine salt to provide the corresponding 2,2-dimethylbutyrate intermediate of the carboxylic acid amine salt and then lactonizing the 2,2-dimethylbutyrate intermediate of the carboxylic acid amine salt to provide simvastatin. The process of the present invention therefore avoids the additional steps required for amide formation and hydroxyl protection and deprotection as required by the prior art. Accordingly, in a first embodiment of the present invention, a process for the preparation of a carboxylic acid amine salt of formula I is provided: (I), the process comprising reacting lovastatin of formula II: HCO - .0 (II) with an amine of formula III: 6 (III) in an aqueous medium to provide the carboxylic acid amine salt of formula I. In accordance with a second embodiment of the present invention, a process for the preparation of simvastatin and pharmaceutically acceptable salts thereof is provided comprising the steps of: (a) providing a carboxylic acid amine salt of formula I: (I). (b) lithiating the carboxylic acid amine salt (I) under suitable conditions to form the corresponding 2,2-dimethylbutyrate intermediate of formula Ila; 7 In accordance with a third embodiment of the present invention, a process for the preparation of simvastatin and pharmaceutically acceptable salts thereof is provided comprising the steps of: (a) providing a carboxylic acid amine salt of formula I: (b) lithiating the carboxylic acid amine salt (I) under suitable conditions to form the corresponding 2,2-dimethylbutyrate intermediate of formula Ila: (c) converting the 2,2-dimethylbutyrate intermediate (Ila) to an ammonium salt of the 2,2-dimethylbutyrate intermediate of formula lib: 8 (d) lactonizing the ammonium salt of the 2,2-dimethylbutyrate intermediate (lib) to provide simvastatin of formula IV: In accordance with a fourth embodiment of the present invention, a process for the preparation of simvastatin and pharmaceutically acceptable salts thereof is provided comprising the steps of: (a) providing a carboxylic acid amine salt of formula I: (b) lithiating the carboxylic acid amine salt (I) under suitable conditions to form the corresponding 2,2-dimethylbutyrate intermediate of formula Ha: 9 (((999 (c) converting the 2,2-dimethylbutyrate intermediate (Ila) to the corresponding free carboxylic acid; and (d) lactonizing the free carboxylic acid intermediate to provide simvastatin of formula IV: In accordance with a fifth embodiment of the present invention, a process for the lactonization of the corresponding free carboxylic acid of the 2,2-dimethylbutyrate intermediate (Ila) is provided comprising reacting the corresponding free carboxylic acid of the 2,2-dimethylbutyrate intermediate (Ila) with a peptide coupling reagent in the presence of an organic solvent. In another aspect of the present invention, a process for the lactonization of the ammonium salt of the 2,2-dimethylbutyrate intermediate (Ila) is provided comprising lactonizing under reflux the ammonium salt of the 2,2-dimethylbutyrate intermediate (Ila) in a mixture of toluene and a polar aprotic solvent to provide simvastatin (IV) having an impurity content of less than about 0.15%. 10 DEFINITIONS The term 'alkyl' as used herein means a straight or branched hydrocarbon chain radical containing carbon and hydrogen atoms of from 1 to about 8 carbon atoms, with no unsaturation, and which is attached to the rest of the molecule by a single bond, e.g., methyl, ethyl, n-propyl, 1-methylethyl (isopropyl), n-butyl, n-pentyl, 1,1-dimethylethyl (t-butyl), and the like. The term "alkenyl" as used herein means an aliphatic hydrocarbon group containing a carbon-carbon double bond and which may be a straight or branched or branched chain having about 2 to about 10 carbon atoms, e.g., ethenyl, 1-propenyl, 2-propenyl (allyl), iso-propenyl, 2-methyl- 1-propenyl, 1-butenyl, 2-butenyl and the like. The term "alkynyl" as used herein means a straight or branched chain hydrocarbyl radicals having at least one carbon-carbon triple bond, and having in the range of about 2 up to about 12 carbon atoms (with radicals having in the range of about 2 up to about 10 carbon atoms being preferred) e.g., ethynyl, propynyl, butynyl and the like. The term "alkoxy" as used herein means an alkyl group as defined above attached via oxygen linkage to the rest of the molecule, i.e., of the general formula -OR , wherein R is an alkyl as defined above. Representative examples of those groups are -OCH3, -OC2H5 and the like. The term "cycloalkyl" as used herein means a non-aromatic mono or multicyclic ring system of about 3 to about 12 carbon atoms such as, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, perhydronapththyl, adamantyl and norbornyl groups bridged cyclic group or sprirobicyclic groups e.g. sprio (4,4) non-2-yl and the like. The term "cycloalkylalkyl" as used herein means a cyclic ring-containing radicals containing in the range of about 3 up to about 8 carbon atoms directly attached to the alkyl group which are then attached to the main structure at any carbon from alkyl group that results in the creation of a stable structure such as, for example, cyclopropylmethyl, cyclobutylethyl, cyclopentylethyl, and the like. The term "cycloalkenyl" as used herein means a cyclic ring-containing radicals containing in the range of about 3 up to about 8 carbon atoms with at least one carbon- 11 carbon double bond such as, for example, cyclopropenyl, cyclobutenyl, cyclopentenyl and the like. The term "aryl" as used herein means an aromatic radicals having in the range of about 6 up to about 14 carbon atoms such as, for example, phenyl, naphthyl, tetrahydronapthyl, indanyl, biphenyl and the like. The term "arylalkyl" as used herein means an aryl group as defined above directly bonded to an alkyl group as defined above, e.g., -CH2C6H5, -C2H5C6H5 and the like. The term "heterocyclic ring" as used herein means a stable 3- to about 15 membered ring radical, which consists of carbon atoms and from one to five heteroatoms selected from the group consisting of nitrogen, phosphorus, oxygen, sulfur and combinations thereof. Suitable heterocyclic ring radicals for use herein may be a monocyclic, bicyclic or tricyclic ring system, which may include fused, bridged or spiro ring systems, and the nitrogen, phosphorus, carbon, oxygen or sulfur atoms in the heterocyclic ring radical may be optionally oxidized to various oxidation states. In addition, the nitrogen atom may be optionally quaternized; and the ring radical may be partially or fully saturated (i.e., heteroaromatic or heteroaryl aromatic). Examples of such heterocyclic ring radicals include, but are not limited to, azetidinyl, acridinyl, benzodioxolyl, benzodioxanyl, benzofurnyl, carbazolyl, cinnolinyl, dioxolanyl, indolizinyl, naphthyridinyl, perhydroazepinyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pyridyl, pteridinyl, purinyl, quinazolinyl, quinoxalinyl, quinolinyl, isoquinolinyl, tetrazoyl, imidazolyl, tetrahydroisouinolyl, piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, 2-oxoazepinyl, azepinyl, pyrrolyl, 4-piperidonyl, pyrrolidinyl, pyrazinyl, pyrimZidinyl, pyridazinyl, oxazolyl, oxazolinyl, oxasolidinyl, triazolyl, indanyl, isoxazolyl, isoxasolidinyl, morpholinyl, thiazolyl, thiazolinyl, thiazolidinyl, isothiazolyl, quinuclidinyl, isothiazolidinyl, indolyl, isoindolyl, indolinyl, isoindolinyl, octahydroindolyl, octahydroisoindolyl, quinolyl, isoquinolyl, decahydroisoquinolyl, benzimidazolyl, thiadiazolyl, benzopyranyl, benzothiazolyl, benzooxazolyl, furyl, tetrahydrofurtyl, tetrahydropyranyl, thienyl, benzothienyl, 12 thiamorpholinyl, thiamorpholinyl sulfoxide thiamorpholinyl sulfone, dioxaphospholanyl, oxadiazolyl, chromanyl, isochromanyl and the like and combinations thereof. The term "heteroaryl" as used herein means a heterocyclic ring radical as defined above. The heteroaryl ring radical may be attached to the main structure at any heteroatom or carbon atom that results in the creation of a stable structure. The heterocyclic ring radical may be attached to the main structure at any heteroatom or carbon atom that results in the creation of a stable structure. The term "heteroarylalkyl" as used herein means a heteroaryl ring radical as defined above directly bonded to alkyl group. The heteroarylalkyl radical may be attached to the main structure at any carbon atom from alkyl group that results in the creation of a stable structure. The term "heterocyclyl" as used herein means a heterocylic ring radical as defined above. The heterocylyl ring radical may be attached to the main structure at any heteroatom or carbon atom that results in the creation of a stable structure. The term "heterocyclylalkyl" as used herein means a heterocylic ring radical as defined above directly bonded to alkyl group. The heterocyclylalkyl radical may be attached to the main structure at carbon atom in the alkyl group that results in the creation of a stable structure. The substituents in the 'substituted alkyl', 'substituted alkoxy', 'substituted alkenyl', 'substituted alkynyl', 'substituted cycloalkyl', 'substituted cycloalkylalkyl', 'substituted cyclocalkenyl', 'substituted arylalkyl', 'substituted aryl', 'substituted heterocyclic ring', 'substituted heteroaryl ring,' 'substituted heteroarylalkyl', 'substituted heterocyclylalkyl ring', 'substituted amino', 'substituted cyclic ring' and 'substituted carboxylic acid derivative' may be the same or different with one or more selected from the group such as hydrogen, hydroxy, halogen, carboxyl, cyano, nitro, oxo (=0), thio(=S), substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted amino, substituted or 13 unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted heterocyclylalkyl ring, substituted or unsubstituted heteroarylalkyl, substituted or unsubstituted heterocyclic ring, substituted or unsubstituted guanidine, -COORx, -C(0)Rx, -C(S)RX, -C(0)NRxRy, -C(0)ONRxRy, -NRxCONRyRz, -N(Rx)SORy, -N(Rx)S02Ry, -(=N-N(Rx)Ry), - NRxC(0)ORy, -NRxRy, -NRxC(0)Rr, -NRxC(S)Ry -NRxC(S)NRyRz, -SONRxRy-, -S02NRxRy-, -ORx, -ORxC(0)NRyRz, -ORxC(0)ORr, -OC(0)Rx, -OC(0)NRxRy, - RxNRyC(0)Rz, -RxORy, -RxC(0)ORy, -RxC(0)NRyRz, -RxC(0)Rx, -RxOC(0)Ry, -SRx, -SORx, -S02Rx, -ON02, wherein RX, Ry and Rz in each of the above groups can be the same or different and can be a hydrogen atom, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted amino, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, 'substituted heterocyclylalkyl ring' substituted or unsubstituted heteroarylalkyl, substituted or unsubstituted heterocyclic ring. DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the use of a carboxylic acid amine salt in the preparation of HMG-CoA reductase inhibitors, e.g., simvastatin, and their intermediates. One aspect of the present invention provides a process for the preparation of a carboxylic acid amine salt of formula I: wherein R1 and R2 may be the same or different and may be hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, 14 substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkylakyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocyclic ring, substituted or unsubstituted heterocyclylalkyl, substituted or unsubstituted heteroarylalkyl, with the proviso that only one of R1 and R2 can be hydrogen, or R1 and R2 together with the nitrogen atom to which they are bonded are joined together to form a heterocyclic ring, the process comprising reacting lovastatin of formula II: wherein R and R have the aforestated meanings; in an aqueous medium, e.g., water. In a preferred embodiment of the present invention, the amine is tert-butylamine, i.e., wherein R1 is hydrogen and R is tert-butyl, or n-butylamine. The reaction of the compound of formula II with the amine can be carried out at a temperature of about 30°C to about 100°C, preferably from about 40°C to about 80°C and more preferably from about 50°C to about 60°C. The time period for the reaction to reach completion can range from about 1 hour to about 24 hours and preferably from about 3 hour to about 6 hours. Generally, the ratio [MOLAR RATIO] of the compound of formula II to the 15 amine of formula III can range from about 1:1.5 to about 1:3.5 and preferably from about 1:2 to about 1:2.2. Another aspect of the present invention is a process for the preparation of simvastatin and pharmaceutically acceptable salts thereof including at least the steps of: (a) providing a carboxylic acid amine salt of formula I; (b) lithiating the carboxylic acid amine salt (I) under suitable conditions to form the corresponding 2,2-dimethylbutyrate intermediate of formula IIa; (c) lactonizing the 2,2-dimethylbutyrate intermediate (Ha) to provide simvastatin (IV). In the first step of this process of the present invention, the carboxylic acid amine salt of formula (II) can be provided as described above or can be provided by methods known in the art. See, e.g., U.S. Patent No. 6,583,295, the contents of which are incorporated by reference herein. For example, the carboxylic acid amine salt can be prepared by converting a sodium salt of lovastatin to the free acid of lovastatin by using phosphoric acid followed by reacting the free acid with a suitable amount of an amine to form an amine salt of lovastatin in ethyl acetate. The amine used in the above salt formation can be, for example, 1,2- dimethylpropylamine, 3-(2-aminoethylamino)- propylamine, N,N'-diisopropyl- ethylenediamine, N,N'-diethyl- ethyl enediamine, N-methyl-1,3- propanediamine, N-methylethylenediamine, secondary-butylamine, tertiary-butylamine, tertiary-amylamine and secondary butylamine. In step (b), the carboxylic acid amine salt (I) is lithiated with one or more lithiating agents under suitable conditions to form the corresponding 2,2-dimethylbutyrate intermediate (Ila). Suitable lithiating agents include, but are not limited to, methyl halides, methyl sulfonates and sulfates, methyl phosphates, methyl carbonates and the like and mixtures 16 thereof. Representative examples of such lithiating agents include, but are not limited to, methyl iodide, methyl bromide, methyl p-toluenesulfonate, methanesulfonate and the like and mixtures thereof. Generally, the lithiating step can be carried out in one or more organic solvents and in the presence of one or more base. Suitable solvents include, but are not limited to, tetrahydrofuran (THF), pyrrolidine, pyrrolidone, Et2O, hexane and the like and mixtures thereof. The base for use herein can be organolithium compounds, alkali metal hydrides and the like and mixtures thereof. Suitable organolithium compounds include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium and the like and mixtures thereof. Suitable alkali metal hydrides include, but are not limited to, potassium hydride, sodium hydride and the like and mixtures thereof. The carboxylic acid amine salt (I) can be lithiated with the one or more lithiating agents at a temperature ranging from about -10°C to about -60°C and preferably from about -25°C to about -45°C. The amount of lithiating agent will ordinarily range from about 2.5 to about 8.0 equivalents and preferably about 3.0 to about 5.0 equivalents with respect to the equivalents of carboxylic acid amine salt (I). The 2,2-dimethylbutyrate intermediate (Ha) is then subjected to lactonization by cyclizing the intermediate under suitable conditions to obtain the desired simvastatin of formula IV. The process of this embodiment is generally shown below in Scheme 1: 17 SCHEME 1 As shown in Scheme 1, the compound of formula II can be converted to a carboxylic acid amine salt (I) using an amine of formula III in an aqueous medium such as water at a temperature ranging from about 40°C to about 80°C. The carboxylic acid amine salt (II) may then be lithiated using, e.g., a strong base, methyl iodide, and pyrrolidine in anhydrous THF, to provide the corresponding 2,2-dimethylbutyrate intermediate (Ha). The corresponding 2,2-dimethylbutyrate intermediate (Ha) may then be lactonized using conventional methods, e.g., azeotropic reflux with toluene, to provide simvastatin (IV). If desired, simvastatin can be coverted to pharmaceutically acceptable salts thereof by known techniques. Yet another aspect of the present invention is a process for the preparation of simvastatin and pharmaceutically acceptable salts thereof including at least the steps of: (a) providing a carboxylic acid amine salt (I); (b) lithiating the carboxylic acid amine salt amine salt (I) to provide the corresponding 2,2-dimethylbutyrate intermediate (Ha); (c) converting the corresponding 2,2-dimethylbutyrate intermediate (Ha) to an ammonium salt of the 2,2-dimethylbutyrate intermediate (lib); and, 18 (d) lactonizing the ammonium salt of the 2,2-dimethylbutyrate intermediate to provide simvastatin (IV). This process is generally shown below in Scheme 2: Toluene/reflux SCHEME 2 As shown in Scheme 2, lovastatin of formula (II) may be converted to a carboxylic acid amine salt (I) as described above. The carboxylic acid amine salt (I) may then be lithiated, e.g., in the presence of a strong base, methyl iodide (Mel) and a pyrrolidine in anhydrous tetrahydrofuran (THF), to provide the corresponding 2,2-dimethylbutyrate intermediate (Ila). The 2,2-dimethylbutyrate intermediate (Ila) may then be neutralized in situ to its free carboxylic acid using a suitable mineral acid, e.g., dilute hydrochloric acid (HCL). The free carboxylic acid may then be isolated using, for example, methanolic ammonia (about 25%), which forms an ammonium salt of the 2,2-dimethylbutyrate intermediate (lib). The ammonium salt of the 2,2-dimethylbutyrate intermediate (lib) may then be lactonized using conventional methods, e.g., azeotropic reflux with toluene, to yield simvastatin (IV). 19 Still yet another aspect of the present invention is a process for the preparation of simvastatin and pharmaceutically acceptable salts thereof including at least the steps of: (a) providing a carboxylic acid amine salt (I); (b) lithiating the carboxylic acid amine salt amine salt (I) to provide the corresponding 2,2-dimethylbutyrate intermediate (Ila); (c) converting the corresponding 2,2-dimethylbutyrate intermediate (Ila) to its free carboxylic acid; and, (d) lactonizing the free carboxylic acid of the 2,2-dimethylbutyrate intermediate to provide simvastatin. This process is generally shown below in Scheme 3: SCHEME 3