DFT Study on the Factors Determining the Enantioselectivity of Friedel−Crafts Reactions of Indole with N-Acyl and N-Tosylimines Catalyzed by BINOL−Phosphoric Acid Derivatives

DFT methods have been used to study the mechanism and the enantioselectivity of the Friedel-Crafts reaction of indoles with acyl and tosyl imides catalyzed by BINOL-phosphoric acid catalysts. The results are in excellent agreement with the experimental enantioselectivities. The energies of the competing transition structures and, thus, the enantioselectivity are rationalized from calculations on a model system. We propose a simple model to predict the absolute configuration of the products.