Microwave-Assisted Synthesis of SubstitutedTetrahydropyrans Catalyzed by ZrCl_4and ItsApplication in the Asymmetric Synthesis of exo- andendo-brevicomin

摘要

The ZrCl_4-catalyzed deprotection of 1 ,3-dioxane/dioxa-lane and the simultaneous formation of 6-methoxy-sub-stituted tetrahydropyrans proceeded under microwaveirradiation in good yield. This synthetic methodologywas used for the asymmetric synthesis of (+)-exo- and(+)-endo-brevicomin in 55% overall yield over 4 steps.