摘要:
                                gamma- and delta-Lactones 5, 6, 13, 14, 15 and 16 were synthesized via baker's yeast reduction of the corresponding keto acids 3 ,4 and 9-12.  The enantioselectivity of the reduction is strongly dependent on the nature of the keto acid:  the delta-lactones were always obtained in an ee% higher than the gamma-lactones and ranging from 70% to 100%.