Lipase-catalysed resolution of gamma- and delta-lactones

Lipase-catalysed stereoselective hydrolysis of a family of saturated gamma- and delta-lactones was investigated. Increasing the chain length from delta-octalactone to delta-dodecalactone leads to higher enantiomeric excess. Best results were found using a lipase from Pseudomonas species (KW51) yielding highest enantiomeric excesses (greater than 99% ee at 50% conversion, E > 100) at short reaction times (10 h) for delta-undecalactone and delta-dodecalactone. In contrast, gamma-lactones were resolved less efficiently. Highest enantioselectivities (70%ee at 50% conversion, E = 11) were found for gamma-nonalactone. Optimum reaction conditions were found at pH 8 and 12.5 degrees C.