Unusual thionation via fragmentation

Abstract

Reaction of 4,4-dichloro-2,6-diphenyl-4,4-dihydropyrane (2) with thiols in the presence of triethylamine gives interesting results. The exclusive formation of 2,6-diphenylpyran-4-thione (3) in the reaction with PhSH through cleavage of C-Ar-S bond is remarkable.