Structure and synthesis of the aryltetralin lignans hypophyllanthin and nirtetralin

Abstract

Structures previously suggested for hypophyllanthin, the major aryltetralin lignan constituent of Phyllanthus niruri are shown to be incorrect. The structure r-1-(3,4-dimethoxyphenyl)-6-methoxy-t-2,c-3-bismethoxymethyl-7,8-methylenedioxy-1,2,3,4-tetrahydronaphthalene (5) now proposed is confirmed by an unambiguous synthesis. Synthesis of the congener, nirtetralin, is also described.