Enzymatic Resolution of (+/-)-Menthol Using Transesterification with Methyl (2R)-(+)-2-Chloropropanoate: A Biocatalyzed Reaction Studied by NMR Spectroscopy and Polarimetry for an Advanced Undergraduate Project in Modern Organic Chemistry

Lipase from Candida rugosa is used as an efficient biocatalyst for the kinetic resolution of (+/-)-Menthol. Methyl (2R)-(+)-2-chloropropanoate is chosen as an acyl donor for the transesterification reaction of menthol. Candida rugosa lipase catalyzes this transformation only with the (-)-menthol thus providing the corresponding 2-chloropropanoate with an excellent diastereomeric excess (>94%). This reaction is a part of an integrated laboratory project in stereoselective organic synthesis for advanced undergraduate students in the University of Nantes (France).