Mechanistic Insights into Scandium-Catalyzed Hydroaminoalkylation of Olefins with Amines: Origin of Regioselectivity and Charge-Based Prediction Model

DFT calculations have been carried out on the Sc-catalyzed regioselective hydroaminoalkylation of olefins with amines. It has been revealed that the true active species is an amine-coordinated η2-azametallacyclic complex, and electronic factors play a crucial role in achieving regioselectivity. The charge dispersion and charge alternation account well for the stability of the olefin insertion transition states and products. The charge distribution of 15 olefin substrates used previously in the experimental studies correlates well with the observed regioselectivity and could thus provide a potential model for regioselectivity prediction. The reactivity of different types of C–H bonds was also explored by modeling the reaction of (CH2C6H4NMe2-o)2Sc+ with iPrN(Me)(Et). The suggested reactivity trend for the Sc-catalyzed hydroaminoalkylation follows the order of primary C–H bond > secondary C–H bond > tertiary C–H bond.