A simple method for the synthesis of 4-aryl-9-oxynaphthofuranone lignans

Abstract

The 9-aryl-4-oxynaphthofuran-1(3H)-one system is generally synthesized in two steps from α-aryl-o-toluic acid derivatives. The method involves a tandem conjugate addition–Dieckmann type condensation between α-lithiated α-aryl-o-toluic acid derivatives and 2-furan-2(5H)-one as a key step followed by simple dehydrogenation or dehydration, and can be applied to the synthesis of two natural lignans (neojusticidin A and neojusticidin B).