Efficient synthesis of bibenzyl derivatives bearing pyranyl moieties: First total synthesis of bauhinol D

Abstract

An efficient and general synthesis of bibenzyl derivatives bearing pyranyl rings was achieved by ethylenediamine diacetate-catalyzed reactions of 3,5-dihydroxybibenzyl with αβ-unsaturated aldehydes in moderate yields. These reactions provided naturally occurring compounds 1 and 2 in single step reaction. As an application of this methodology, biologically interesting natural bauhinol D (8) was synthesized by a convergent sequence from readily available benzaldehyde and benzyl phosphonate.