Synthesis and Reactions of Pyranobenzimidazole-2-thiones from Dehydroacetic Acid

An efficient synthesis of pyranobenzimidazole-2-thiones has been described through reaction of carbon disulfide or thiophosgene with enaminone. The alkylation of pyranobenzimidazole-2-thione in the presence of methyl iodide furnished the desired S-methylated derivatives, and the reaction of pyranobenzimidazole-2-thione with copper (I) iodide and triphenylphosphine gave a dimeric complex [Cu (PPh3) (bzimtH)](2).