Oxazaborolidine catalyzed enantioselective reductions of cyclic meso-imides
摘要:
A new asymmetric reduction method for meso-imides is reported. Treatment of various imides with a mixture of a chiral oxazaborolidine and BH3 leads to a mixture of cis- and trans-hydroxylactams and, after subsequent ethanolysis, to the corresponding diastereomerically pure trans-ethoxylactams. The enantiomeric excesses were shown to be 75-89% by both chiral HPLC-determinations and conversion of the reduction products into the corresponding, known lactones.