Rh(III)-catalyzed [4+1]-annulation of azobenzenes with α- carbonyl sulfoxonium ylides toward 3-acyl-(2H)-indazoles

A Rh(III) catalyzed [4 + 1] annulation of azobenzenes with alpha- carbonyl sulfoxonium ylides was developed to access 2H-indazoles in moderate to excellent yields with good functional group compatibilities. It proceeded with the sequential insertion of the Rh(III) carbene to the C-H bond and cyclization steps, where sulfoxonium ylides served as efficient and stable carbene precursor. (C) 2018 Published by Elsevier Ltd.