NOVELTY - Making pregabalin (I) involves reacting isovaleraldehyde (II) and alkyl cyanoacetate (III); reacting formed 2-cyano-5-methyl-hex-2-enoic acid alkyl ester (IV) with cyanide source; converting 2-isobutylsuccinonitrile (V) to racemic 3-cyano-5-methyl-hexanoic acid (VI) using nitrilase enzyme; treating compound (VI) with alcohol/acidic catalyst to give racemic alkyl 3-cyano-5-methyl-hexanoate (VII); performing enzymatic hydrolysis of compound (VII); and hydrolyzing ester group of obtained (S)-alkyl 3-cyano-5-methyl-hexanoate (VIII) using alkali/alkaline earth metal base to give compound (I).    USE - In the preparation of pregabalin (claimed) for treating several central nervous system disorders including epilepsy, neuropathic pain, anxiety and social phobia.    ADVANTAGE - The method produces Pregabalin (I) in high yield with high chemical and chiral purity; is simple, economical, user-friendly and commercially viable; and is easy to implement on commercial scale, and is to avoid excessive use of reagent(s) and organic solvent(s), which makes the present invention eco-friendly as well. The byproduct formed during the reaction can be reusable and thus recyclable, which makes the process industrially more suitable.    DETAILED DESCRIPTION - Preparation (M1) of a pregabalin compound of formula (I), involves (a) reacting isovaleraldehyde of formula (II) and alkyl cyanoacetate of formula (III) optionally in presence of salts of weak acid and weak base or weak base in a suitable solvent to give 2-cyano-5-methyl-hex-2-enoic acid alkyl ester of formula (IV); (b) reacting the (IV) with a suitable cyanide source in water and/or in an organic solvent to give 2-isobutylsuccinonitrile of formula (V); (c) obtaining optionally the compound (V) by reacting the compound (II) and the compound (III) in presence of suitable cyanide source in water or in an organic solvent in a single step; (d) converting the compound (V) to racemic 3-cyano-5-methyl-hexanoic acid of formula (VI) or its salt with a genetically modified nitrilase enzyme such as Nit 9N562 in water or optionally with an organic co-solvent at appropriate pH and temperature; (e) converting the compound (VI) to racemic alkyl 3-cyano-5-methyl-hexanoate of formula (VII) by treatment with alcohol (R3OH) and acidic catalyst or alkyl halide (R3X) in presence of a base in a suitable solvent or a mixture of solvents of it; (f) obtaining (S)-alkyl 3-cyano-5-methyl-hexanoate of formula (VIII) and (R)-3-cyano-5- methyl-hexanoic acid of formula (X) or its salt by enzymatic enantioselective hydrolysis in water and/or organic solvent from the compound (VII); (g) obtaining optionally the compound (VII) by racemizing unwanted compound (X) or enriched compound (X) in presence of a base in organic solvent; and (h) converting the compound (VIII) to pregabalin (I) by hydrolyzing ester group with suitable alkali or alkaline earth metal base to get followed by hydrogenation optionally in one pot in a solvent selected from water and/or other organic solvents in presence of a suitable hydrogenation catalyst.    R1=linear or branched lower 1-4C alkyl;    R2=cataionic counter ion, H, alkali metal salt, alkaline earth metal salt, ammonium salt, alkyl ammonium salt, or organic amine salt;    R3=linear or branched lower alkyl such as 1-4C or 7-10C aryl or alkyl aryl.