Copper-catalyzed site-selective intramolecular amidation of unactivated C(sp³)-H bonds

Abstract

The intramolecular dehydrogenative amidation of aliphatic amides, directed by a bidentate ligand, was developed using a copper-catalyzed sp(3) C-H bond functionalization process. The reaction favors predominantly the C-H bonds of β-methyl groups over the unactivated methylene C-H bonds. Moreover, a preference for activating sp(3) C-H bonds of β-methyl groups, via a five-membered ring intermediate, over the aromatic sp(2) C-H bonds was also observed in the cyclometalation step. Additionally, sp(3) C-H bonds of unactivated secondary sp(3) C-H bonds could be functionalized by favoring the ring carbon atoms over the linear carbon atoms.

Keywords: CH activation; copper; heterocycles; homogeneous catalysis; synthetic methods.