Total synthesis and stereochemical confirmation of 2,5-diaryl-3,4-dimethyl-tetrahydrofuran lignans: (+)-fragransin A(2), (+)-galbelgin, (+)-talaumidin, (-)-saucernetin and (-)-verrucosin

摘要

A new ring closure to tetrasubstituted tetrahydrofurans from the intrantolecular attack of an OMOM ether onto a benzylic mesylate proceeds through a quinonoid intermediate or by direct S(N)2 displacement. The synthesis of diastereomeric biologically active natural lignans is described utilizing this general methodology.