Computational Investigation of Scandium-Based Catalysts for Olefin Hydroaminoalkylation and C–H Addition

Great progress has been achieved in the olefin hydroaminoalkylation by using amines, which is an atom-efficient route for the synthesis of alkylated amine derivatives. However, success in the catalytic olefin hydroaminoalkylation with a simple tertiary amine is hitherto very limited. In this study, density functional theory was applied to investigate the hydroaminoalkylation of olefins with tertiary amines, catalyzed by a series of homoleptic tris­(benzyl) scandium complexes. It is found that the catalytic performance can be improved via substitution of electron-withdrawing groups and modifying ligand frameworks to reduce their steric hindrance. In addition, the potential applications of scandium catalysts in the α-C­(sp3)–H alkylation of various heteroatom-containing (P, As, O, S, and Se) substrates were explored. The results suggest that alkyl sulfides and selenides are promising substrates to undergo α-C­(sp3)–H addition to olefins. Importantly, the effects of ligand backbone and substituent on catalytic performance and the different reactivities of the heteroatom-containing substrates were elucidated by frontier orbital, natural charge, topographic steric map, and distortion–interaction analyses, which give considerable insight into catalytic systems. This work provides useful information for developing new olefin hydroaminoalkylation reactions by using simple tertiary amines and for the addition of α-C­(sp3)–H bond of heteroatom-containing substrates to alkenes.