Copper-catalyzed tandem arylation–cyclization of 2-alkynylaryl isothiocyanates with diaryliodonium salts: an efficient synthesis of thiochromeno[2,3-b]indoles

Abstract

A catalytic tandem arylation–cyclization approach using 2-alkynylphenyl isothiocyanates with diaryliodonium salts is described. The reaction is performed under mild conditions and thiochromeno[2,3-b]indoles are obtained in moderate to good yields. This tandem protocol involves chemoselective S-arylation, regioselective 5-endo-trig cyclization and Friedel–Crafts-type cyclization processes. Two C–C bonds, one C–S bond, and two heterocyclic rings are formed in a single step. Preliminary mechanistic studies indicate that a carbocation mechanism is involved.