Enantioselectivity in Catalytic Asymmetric Fischer Indolizations Hinges on the Competition of π-Stacking and CH/π Interactions

Computational analyses of the first catalytic asymmetric Fischer indolization (J. Am. Chem. Soc. 2011, 133, 18534) reveal that enantioselectivity arises from differences in hydrogen bonding and CH/pi interactions between the substrate and catalyst in the operative transition states. This selectivity occurs despite strong pi-stacking interactions that reduce the enantioselectivity.