HFIP-catalyzed highly diastereoselective formal4+2cyclization to synthesize difluorinated multisubstituted chromans using difluoroenoxysilanes as C2 synthons

摘要

A hexafluoroisopropanol(HFIP)-catalyzed highly diastereoselective formal[4+2]cyclization between ortho-hydroxyphenyl para-quinone methides and difluoroenoxysilanes is developed.This tandem protocol provides a simple and straightforward approach to assemble diverse multiply functionalized difluorinated chromans with high to excellent diastereoselectivity by employing difluoroenoxysilane as a new C2 synthon.