2,4-Di-O-methylgyrophoric acid and 2,4,5-tri-O-methylhiascic acid. New tridepsides from Parmelia damaziana

Abstract

The new tridepsides 2,4-di-O-methylgyrophoric acid (8) and 2,4,5-tri-O- methylhiascic acid (5) in addition to the known metabolites atranorin (9), chloroatranorin (10), ursolic acid (11), 5-O-methylhiascic acid (4) and gyrophoric acid (7) have been isolated from the lichen Parmelia damaziana. The structure of the new tridepsides has been established by total synthesis.