Synthesis of heteroaryl 1,2-diketones

Reactions of lithiated heteroaryl- (or aryl-) methylbenzo-triazoles 4a-e with heteroaryl (or aryl) esters 5a-f give a-benzotriazolyl ketones 6a-n in average yields of 90-95%. Oxidation of ketones 6a-l in aqueous DMSO in the presence of oxygen and sodium bicarbonate gave heteroaryl- (aryl-) 1,2-ethanediones 7a-I in average yields of 60-80%.