Nitroxyl-Radical-Catalyzed Oxidative Coupling of Amides with Silylated Nucleophiles through N-Halogenation.

A nitroxyl-radical-catalyzed oxidative coupling reaction between amines with an N-protecting electron-withdrawing group (EWG) and silylated nucleophiles was developed to furnish coupling products in high yields, thus opening up new frontiers in organocatalyzed reactions. This reaction proceeded through the activation of N-halogenated amides by a nitroxyl-radical catalyst, followed by carbon-carbon coupling with silylated nucleophiles. Studies of the reaction mechanism indicated that the nitroxyl radical activates N-halogenated amides, which are generated from N-EWG-protected amides and a halogenation reagent, to give the corresponding imines.