Theoretical Study of Rhodium-Catalyzed Dual C-H Activation to Synthesize C-N Axially Chiral N-Aryloxindoles: Origin of Axial Chirality

The mechanism and origin of axial chirality of the (CpRh)-Rh-X(III)-catalyzed asymmetric dual C-H bond activation reaction were investigated by density functional theory calculations. Theoretical studies indicated that this reaction occurred through C-H bond activation, acetylene insertion, second C-H bond activation, acetylene insertion into the Rh-vinyl bond, and protonation. The first alkyne migratory insertion was the rate-determining step and determined the high enantioselectivity in this reaction. Noncovalent interaction analysis was used to investigate the origin of axial chirality established by the spiro-Cp ligand. Furthermore, the substituent effects of the spiro-Cp ligand were calculated. The origin of axial chirality in this reaction was fully elucidated based on theoretical calculations.