N-arylation of indoles with aryl halides using copper/glycerol as a mild and highly efficient recyclable catalytic system

A simple, efficient, and inexpensive copper catalyzed protocol has been developed for cross-coupling of indoles with aryl halides by using glycerol as a green recyclable solvent and DMSO as an additive. The reaction was carried out at low catalyst loading furnishing various N-aryl indoles in good to excellent yield. This copper/glycerol mixture was recycled up to four runs without any loss in its catalytic activity.