ano)butyrate (ee = 96%) were synthesised in respectively 43% and 40% overall yields by addition of sodium malonate derivatives onto Boc-dehydroalanine methyl ester followed by regio- and stereoselective hydrolysis of α-methyl ester by α-chymotrypsin. These regio-and stereoselectivities were strongly dependent on the nature of the γ-substituents.