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 CpXRh­(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.