Enantioselective cyclopropanation reaction using a conformationally fixed pyridinium ylide through a cation–π interaction

Using a chiral pyridinium ylide with a fixed conformation through a cation–π interaction performs enantioselective cyclopropanation of electron-deficient olefins. 1H NMR, X-ray structural analysis and DFT calculations elucidated the self-complexation and the face-to-face arrangement between the pyridinium and the phenyl rings. The absolute configuration of the product was determined after conversion into a bicyclic cyclopropane derivative.