AbstractA mechanistic study of the Cp*Rh(III)‐catalyzed annulative coupling of benzimidates with 4‐acyl‐1‐sulfonyltriazoles by CH activation was performed using density functional M06 method. It was demonstrated that the active catalyst during the coupling process should be the cation [Cp*Rh(OAc)]+ rather than the neutral Cp*Rh(OAc)2 and Zn(OAc)2 as proposed previously by the experimenters. A novel energetically feasible reaction pathway has been revealed theoretically in details. The acetic acid‐mediated cyclization process was confirmed to be the rate‐limiting step with an overall barrier of 24.3 kcal/mol, excluding any importance of the CH cleavage mechanism as supported by the kinetic isotope effect experiments. The major factors responsible for the preferred regioselectivity of N‐pyrimidinylinoles with 4‐acetyl‐1‐sulfonyltriazoles were discussed.