Room Temperature Ring-Opening Cyclization Reactions of 2-Vinylaziridines with Isocyanates, Carbodiimides, and Isothiocyanates Catalyzed by [Pd(OAc)₂]/PPh₃

2-Vinylaziridines undergo cycloaddition reactions with various heterocumulenes, in the presence of [Pd(OAc)₂] and PPh₃, at room temperature and 1 atm pressure, regioselectively affording five-membered ring products in moderate to high yields. The mixture of stereoisomers obtained by reactions employing cis-1-butyl-2-vinyl-3-methylaziridine as the reactant provides evidence for a mechanism involving a η³−η¹−η³ interconversion of a (π-allyl)palladium intermediate.