In conclusion, we have developed an asymmetric catalytic cyclization of inherently chiral seven-membered rings via SNAr and eight-membered rings via SN2, leveraging a common strategy of substrate preorganization. Both reactions are catalyzed by the same highly congested iminophosphorane catalyst, which shows a remarkable degree of generality across two different rings sizes and two different mechanistic paradigms. Crystallographic analysis and computational modeling revealed an unexpected enantiodivergence between the two substrate classes, as opposite enantiomers of the seven-and eight-membered rings are formed. Computational analysis hints at hydrogen-bonding and substrate-catalyst dipole minimization as governing the transition state assembly, while attractive dispersion interactions appearing to have a large influence on the observed enantioselectivity and enantiodivergence. We believe that the strategies, observations, results and heuristics of this work could inspire and guide future advances in the development of challenging, stereocontrolled cyclizations as well as mechanistically general chiral catalysts.