Synthesis of para-olivetol depsides

Abstract

The unambiguous synthesis of the lichen depsides, anziaic, perlatolic, 2'-O-methylanziaic, 2-O- methylperlatolic, 2'-O-methylperlatolic, 4-O-demethylplanaic, planaic, imbricaric and stenosporic acids is reported. Where necessary the phenolic and carboxy groups of the intermediate phenols were protected by O-benzylation until after the depside-ester bond formation had been achieved by treatment with trifluoroacetic anhydride. Catalytic hydrogenolysis of the depside esters so formed subsequently gave the natural acids.