Palladium-Catalyzed Intramolecular Carbene Insertion into C(sp(3) )-H Bonds.

A palladium-catalyzed carbene insertion into C(sp(3) )-H bonds leading to pyrrolidines was developed. The coupling reaction can be catalyzed by both Pd(0) and Pd(II) , is regioselective, and shows a broad functional group tolerance. This reaction is the first example of palladium-catalyzed C(sp(3) )-C(sp(3) ) bond assembly starting from diazocarbonyl compounds. DFT calculations revealed that this direct C(sp(3) )-H bond functionalization reaction involves an unprecedented concerted metalation-deprotonation step.