Enzymatic resolution of a chiral chlorohydrin precursor for (R)-α-lipoic acid synthesis via lipase catalyzed enantioselective transacylation with vinyl acetate

A new and efficient process was developed by lipase-catalyzed transacylation to resolve ethyl 8-chloro-6-hydroxy octanoate (ECHO) to produce an important chiral precursor for the synthesis of (R)-α-lipoic acid. After optimization of biocatalyst, solvent, acyl donor, temperature and enzyme loading, (S)-O-acetylated ECHO was achieved in 94% ee, 35% isolated yield and 38 g L−1 d−1 space-time yield using Novozym 435 as biocatalyst. Subsequently, the enzymatic resolution reaction was successfully repeated for 7 batches, retaining over 40% conversions.