Access to 3-Acyl-(2H)-indazoles via Rh(III)-Catalyzed C–H Addition and Cyclization of Azobenzenes with α-Keto Aldehydes

The rhodium(III)-catalyzed direct C–H functionalization of azobenzenes with ethyl glyoxalate and aryl glyoxals is described. This protocol provides the facile and efficient formation of various C3-acylated-(2H)-indazoles in moderate to high yields.