Synthesis of sordidone and thiophanic acid, two chlorine-containing lichen metabolites

Abstract

Sordidone (IV) and thiophanic acid (XVI) are two metabolites isolated from the lichen Lecanora rupicola. Chlorination of 5,7-dihydroxy-2,6-dimethylchromone (III) with sulphuryl chloride gives sordidone. Condensation of dichloroeverninic acid (XIII) with phloroglucinol gave the xanthone (XIV), which by chlorination followed by demethylation, gave thiophanic acid (XVI).