Stereocontrol in intermolecular nucleophilic addition to N-acyliminium ion directed by a bicyclo[2.2.1]heptene or 7-oxabicyclo[2.2.1]heptene group. A novel route to 5-substituted 3-pyrrolin-2-ones of high optical purity

Article abstract of DOI:10.1248/cpb.40.1670

Intermolecular nucleophilic additions to the conformationally rigid, tricyclic pyrrolidinium ion (derived from 2 or 6) took place exclusively from the less-hindered face fused with its bicyclo[2.2.1]heptene or 7-oxobicyclo-[2.2.1]heptene moiety. Retro-Die