Combination of Novozym 435-catalyzed Enantioselective Hydrolysis and Amidation for the Preparation of Optically Active δ-Hexadecalactone

A new enzymatic method for synthesis of enantiomerically enriched δ-hexadecalactone (3) based on the enzymatic kinetic resolution of N-methyl-5-acetoxyhexadecanamide (1) is described. A combination of lipase-catalyzed hydrolysis and amidation improved enantioselectivity. Lipase-catalyzed amidation was also investigated. Detailed screening of solvents and additive amines was performed. The addition of cyclohexylamine to lipase-catalyzed hydrolysis afforded the best results to give both enantiomers of 3 with more than 90% enantiomeric excess.