Synthesis of Substituted Thiophenes through Dehydration and Heterocyclization of Alkynols.

A protocol was described for obtaining a variety of substituted thiophenes with functional potential via metal-free dehydration and sulfur cyclization of alkynols with elemental sulfur (S 8 ) or EtOCS 2 K in moderate-to-good yields. The method provides the base-free generation of a trisulfur radical anion (S 3 •- ) and its addition to alkynes as an initiator. This research broadens the applications of S 3 •- in the synthesis of sulfur-containing heterocycles.