Sequential kinetic resolution of (±)-2,3-butanediol in organic solvent using lipase from Pseudomonas cepacia.

Lipase from Pseudomonas cepocia (PCL, Amano FS) catalyzed the enantioselective diacetylation of (±)-23-butanediol in vinyl acetate. Both acetylation steps favored the (R)-enantiomer (E₁ = 12, E₂ = 34), thus the reaction is a sequential kinetic resolution. The enantioselectivities of the two steps reinforced one another because both steps proceeded at comparable rates (S = 3) yielding an overall enantioselectivity of approximately 200. A synthetic-scale resolution starting from 2.7 g of (±)-2,3-butanediol yielded the diacetate ester of (R)-(-)-butanediol with 96% ee (1.6 g, 30% yield) and (S)-(+)-butanediol with 99% ee (0.63 g, 23% yield). This preparation is carried out entirely in organic solvent, thereby avoiding the difficult and low yield extraction of 2,3-butanediol from aqueous aolution.