NOVELTY - Preparation (M1) of enantiomerically enriched and/or racemic gamma amino acid (IV) involves i) preparing 5-hydroxy-1,5-dihydro-pyrrol-2-one compound (VII) by reaction of 5-hydroxy-5H-furan-2-one compound (V) with amine compound (VI); ii) preparation of carboxylic acid compound (VIII) through hydrogenation of compound (VII) in presence of noble metal catalysts under hydrogen gas pressure; and iiia) debenzylation of compound (VIII) to obtain compound (IV) carried out in presence of noble metal catalyst under hydrogen gas pressure in the presence of Bronsted acid.    USE - For preparation of enantiomerically enriched and racemic gamma amino acid (claimed) selected from pregabalin and 3-n-propyl-4-aminobutyric acid for treating pain, fibromyalgia, physiological conditions associated with psychomotor stimulants, inflammation, gastrointestinal damage, insomnia, alcoholism and various psychiatric disorders including mania and bipolar disorder.    ADVANTAGE - The method is eco-friendly, green, cost effective, and easy-to-operate industrial-scale synthesis of gamma-amino acids.    DETAILED DESCRIPTION - Preparation (M1) of enantiomerically enriched and/or racemic gamma amino acid of formula (IV) involves i) preparing 5-hydroxy-1,5-dihydro-pyrrol-2-one compound of formula (VII) by reaction of 5-hydroxy-5H-furan-2-one compound of formula (V) with amine compound of formula (VI); ii) preparation of carboxylic acid compound of formula (VIII) through hydrogenation of compound (VII) in presence of noble metal catalysts under hydrogen gas pressure; and iiia) debenzylation of compound (VIII) to obtain compound (IV) carried out in presence of noble metal catalyst under hydrogen gas pressure in the presence of Bronsted acid such as acetic acid, trifluoroacetic acid and/or via catalytic transfer hydrogenation with ammonium formate, or iiib) oxidative debenzylation of compound (VIII) in pressure of N-bromosuccinimide to obtain compound (IV).    R=H or CH3;and    R1=CH3 or CH2OH.    INDEPENDENT CLAIMS are included for following:    (1) preparation (M2) of racemic compound (IV) involving i') preparation of pyrrol-2-one compound of formula (IX) by the reaction of compound (V) with ammonia in alcoholic solvent; and ii) hydrogenation of compound (IX) carried out in presence of noble metal catalyst under hydrogen gas pressure to obtain compounds (IV);    (2) preparation (M3) of 3-hydroxymethyl-hex-2-enoic acid ((S)-1-phenyl-ethyl)-amide (X) involving i'') preparation of 5-hydroxy-1-((S)-phenyl-ethyl)-4-n-propyl-1,5-dihydro-pyrrol-2-one (VIIa) by the reaction of 5-hydroxy-4-n-propyl-5H-furan-2-one (Va) with (S)- alpha -methyl benzyl amine (VIa); ii'') reduction of compound (VIIa) in presence of sodium borohydride to obtain compound (X); and    (3) compound (VII), (VIII) and 3-hydroxymethyl-hex-2-enoic acid ((S)-1-phenyl-ethyl)-amide are new.