Nitrones have been used for rhodium-catalyzed cyclization CH bond activation and O atom transfer of arylnitrones with alkynes by Chang et al. (J. Am. Chem. Soc. 2015, 137, 4908-4911). Density functional theory method has been used to study the mechanism, regio-, and diastereoselectivity of type reactions. The results elucidated that the reaction pathway for Rh(III)-catalyzed cyclization of N-arylnitrones with alkyne contains a CH bond activation, an alkyne insertion into RhC bond, a reductive elimination to form a Rh(I) complex, an oxidative addition leading to NO cleavage, an imine insertion into the RhC bond, and the final protonolysis to regenerate the products and the active catalyst. The regioselectivity of this reaction with asymmetric alkyne is controlled by the electronic effect in alkyne insertion type instead of steric effects. The distortioninteraction analysis is also used to explain the regioselectivity. The diastereoselectivity is controlled by the imine insertion step. In this step, the sterically less hindered transition state is favored, leading to stereoselective product formation.