Synthesis of Phenylthiomethyl Substitution Furans by Lewis Acid Catalysed Substitution

Abstract
Two routes to the differentially functionalised trisubstituted furan methyl 4-methyl-2-[(phenylthio)methyl]-3-furoate are presented. One is a direct palladium catalysed annulation which proceeds smoothly in the presence of a thioether and the other depends on a highly chemoselective displacement of a methoxy group by phenylthiotrimethylsilane. The scope and mechanism of the latter transformation was probed with simple model systems.