Rhodium-Catalyzed Nitrene/Alkyne Metathesis: An Enantioselective Process for the Synthesis of N-Heterocycles.

A chiral dirhodium-carboxylates-catalyzed asymmetric nitrene/alkyne metathesis (NAM) cascade reaction of alkyne-tethered sulfamates has been developed, which provides a general access to the synthesis of tricyclic N-heterocycles in good yields and excellent enantioselectivity. The chiral dirhodium catalyst not only promotes the nitrene/alkyne metathesis (NAM) to generate the key α-imino metal carbene intermediate but also is responsible for the observed asymmetric induction in the terminating [2,3]-sigmatropic rearrangement of oxonium ylide species.