Catalytic Chemo-, <i>E</i>/<i>Z</i>-, and Enantioselective Cyclizations of <i>o</i>-Hydroxybenzyl Alcohols with Dimedone-Derived Enaminones

Abstract

A catalytic chemo-, E/Z-, and enantioselective cyclization of o-hydroxybenzyl alcohols with dimedone-derived enaminones has been established, which not only realized a chemoselective C1,2 cyclization of enaminones but also achieved the catalytic asymmetric construction of the biologically important tetrahydroxanthene framework with high E/Z- and enantioselectivities (all >95:5 E/Z, up to 98% yield, 97:3 er). This approach not only represents the first catalytic asymmetric C1,2 cyclization of enaminones with o-hydroxybenzyl alcohols but also provides an efficient strategy for constructing oxygenous heterocyclic frameworks with optical purity.