The enantioselective synthesis of L-carnitine and acetyl-L-carnitine hydrochlorides was de-scribed. The asymmetric reduction of ethyl γ-chloroacetoacetate catalyzed by chiral oxazaborolidines enantioselectively gave ethyl R-3-hydroxy-4-chlorobutyrate in good yield and enantioselectivity. In following two steps, such an ester was converted into L-carnitine hydrochloride in 68.3% overall yield with 94.6% ee and acetyl-L-carnitine hydrochloride in 62.6% overall yield with 96.8% ee. Some factors effecting the yield and the enantioselectivity of asymmetric reduction of ethyl γ-chloroacetoacetate were investigated.

Key words: acetyl-L-carnitine, chiral oxazaborolidine, asymmetric reduction, L-carnitine hydrochloride