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

摘要

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.