Copper-mediated selective C-H activation and cross-dehydrogenative C-N coupling of 2'-aminoacetophenones.

Isatins were obtained by cross-dehydrogenative C-N annulation and dealkylative C-N annulation of 2'-N-aryl/alkylaminoacetophenones and 2'-N,N-dialkylaminoacetophenones respectively in the presence of Cu(OAc)2·H2O/NaOAc/air. However, on reaction with CuBr, 2'-N-benzylaminoacetophenones underwent selective oxidation of an α-methylene group of amine rather than the 2-acetyl group to provide corresponding benzamides exclusively. Base played an important role in selective oxidation by lowering the temperature and time.