High diastereoselective synthesis of spiro-isoxazolonechromans via domino oxa-Michael/1,6-addition reactions of ortho-hydroxyphenylsubstituted para-quinone methides with unsaturated isoxazolones

摘要

A mild Et3N-catalyzed novel domino oxa-Michael/1,6-addition reaction of ortho-hydroxyphenylsubstituted p-QMs and unsaturated isoxazolones is described. Various new spiro-isoxazolonechromans were obtained in good yields (up to 89%) with excellent diastereoselectivities (>99:1 dr). The structure of the new compound 3a was determined by single crystal X-ray analysis. (C) 2019 Elsevier Ltd. All rights reserved.