Enantioselective Photocycloaddition Mediated by Chiral Bronsted Acids:Asymmetric Synthesis of the Rocaglamides

摘要

The genus Aglaia is the source of the rocaglamides,a unique group of natural products featuring a cyclopenta[b]tetrahydroben-zofuran skeleton.We recently reported the synthesis of (+-)-methyl rocaglate 1 using [3+2] dipolar cycloaddition of an oxidopyrylium betaine 2 derived from excited state intramolecular proton transfer (ESIPT) of 3-hydroxyflavone (3-HF) 3 and methyl cinnamate 4.