Rhodium(III)‐Catalyzed Direct C‐H Alkylation of 2‐Aryl‐1,2,3‐triazole N‐Oxides with Maleimides

An efficient rhodium(III)‐catalyzed direct C‐H ortho‐alkylation of 2‐aryl‐1,2,3‐triazole N‐oxides has been developed using maleimides as the alkylation reagent. This protocol displays good functional group tolerance, high atom efficiency and avoids the external oxidant. Only mono‐substituted products were obtained. Based on the results of deuterium exchange experiments, the N‐oxide group plays an important role to improve the regioselectivity by increasing the steric hindrance. A novel strategy for rhodium‐catalyzed direct C‐H ortho‐alkylation of 2‐aryl‐1,2,3‐triazole N‐oxides with maleimides was reported. It proceeds with high atom efficiency, free external oxidant, excellent regioselectivity, and convenient on a gram‐scale.