The Formation of Ketones by a Reaction Equivalent to R-+R′COCH2+→R′COCH2R

A general method has been developed for the overall transformation of α- bromo ketones to α-alkyl or α-aryl ketones , with benzotriazole being used as a synthetic auxiliary. α- Benzotriazolyl ketones , when converted into their phenylhydrazones, reacted smoothly with alkyl and aryl Grignard reagents, which displaced benzotriazolate, to give the corresponding α-alkyl or α-aryl hydrazones. In some cases, these hydrolysed directly to the α-alkyl or α-aryl ketones. In each case, the product was treated with 2,4-dinitrophenylhydrazine to isolate the target ketones as the corresponding 2,4-dinitrophenylhydrazones.