Transition-metal-catalyzed alkylations of amines with alkyl halides: Photoinduced, copper-catalyzed couplings of carbazoles

N-alkylations of carbazoles with a variety of secondary and hindered primary alkyl iodides can be achieved by using a simple precatalyst (CuI) under mild conditions (0 °C) in the presence of a Brønsted base; at higher temperature (30 °C), secondary alkyl bromides also serve as suitable coupling partners. A Li[Cu(carbazolide)2] complex has been crystallographically characterized, and it may serve as an intermediate in the catalytic cycle