A novel biphenyl from the lichen Psoroma contortum

Abstract

The isolation, structural elucidation and synthesis of 1,1'-(2,2'-dihydroxy-4,4',6,6'-tetramethoxy-5,5'- dimethylbiphenyl-3,3'-diyl)bisethanone (contortin) (7), an unusual lichen metabolite probably derived biogenetically by C-C phenolic coupling of two units of C-methylphloroacetophenone, is reported. Spectroscopic data on contortin allowed the structure to be limited to two possibilities, and these were distinguished by total synthesis.