Patent ID: 8212072

Claim:
A method of preparing pregabalin which comprises: a) converting a compound of the formula (I) where R is alkyl or substituted alkyl group and the asymmetric carbon C-4 of pyrrolidinone has an (S) configuration, to a tertiary alcohol intermediate of the formula (II): b) dehydration of the tertiary alcohol intermediate of the formula (II) to yield an alkene intermediate: (4S)-4-(2-methylprop-1-enyl)-1-[(1S)-1-phenylethyl]pyrrolidin-2-one IIIa and/or (4R)-4-(2-methylprop-2-enyl)-1-[(1S)-1-phenylethyl]pyrrolidin-2-one IIIb or a mixture thereof: c) conversion of the alkene intermediate of the formula IIIa and/or IIIb to (4S)-4-(2-methylprop-1-enyl)pyrrolidin-2-one IVa and or (4R)-4-(2-methylprop-2-enyl)pyrrolidin-2-one or a mixture thereof d) hydrogenation of lactam of the formula IVa and/or IVb or a mixture thereof to yield pregabalin lactam of the formula (V): e) hydrolyzing the lactam of the formula (V) to yield pregabalin