Synthesis of [1]Benzothieno[3,2-b]furan - A New Fused Benzoheterocyclic System

Abstract

A new heterocyclic compound has been prepared by four step synthesis. The reaction of methyl thiosalicylate I with excess methyl chloroacetate in the presence of potassium carbonate gives methyl 3-[(methoxycarbonyl)methoxy]benzo[b]thiofen-2-carboxylate (II) which on cyclization by action of potassium tert-butoxide gives methyl 3-hydroxy[1]benzothieno[3,2-b]furan-2-carboxylate (III). Its base catalyzed hydrolysis and decarboxylation forms [1]benzothieno[3,2-b]furan-3(2H)-one (IV) whose reduction with NaBH4 gives the title compound.