Direct intramolecular C(sp3)–H bond sulfonamidation to synthesize benzosultam derivatives under metal-free conditions

Abstract

Direct C(sp³)–H bond amination has become a hot topic due to its high efficiency in converting the C(sp³)–H bond to the C–N bond. Herein, we report an efficient intramolecular C(sp³)–H bond sulfonamidation under metal-free conditions, which provides a straightforward method for the synthesis of 5-membered cyclic sulfonamides (benzosultams). This protocol avoids the use of metal catalysts, oxidants, and any additives. Mechanistic experiments and DFT calculations revealed that the reaction proceeds through a proton transfer coupled with the S_N2 (PTS_N2) process, which is different from other pathways.