Access to Sulfur-Containing Bisheterocycles through Base-Promoted Consecutive Tandem Cyclization/Sulfenylation with Elemental Sulfur.

A convenient and efficient tandem cyclization/sulfenylation of o-alkynyl-phenols/-anilines/enaminones for the synthesis of diverse sulfur-containing bisheterocycles has been developed using stable, odorless, and easy-to-handle elemental S8 as a building block under green chemistry conditions. Notably, a one-step simple base-mediated organic transformation affords a benzofuran (indole or chromone) ring and two C-S bonds. Attractive features of this methodology include the absence of a metal catalyst, mild conditions, good functional group tolerance, and valuable product structures.