PhI(OAc)2-Mediated Dihalogenative Cyclization of 1,6-Enyne with Lithium Halide.

The dihalogenative cyclization of 1,6-enyne with the assistance of PhI(OAc)2 and lithium halide is presented. A plausible radical mechanism is proposed, which consists of addition of halogen radical to alkene, 5-exo-dig radical cyclization of enyne and halogenation via radical coupling. The alkenyl- and alkyl-halide groups in the resulted pyrrolidine products have been demonstrated to be facile handles for further transformations.