Modular synthesis and transition metal-free alkynylation/alkenylation of Castagnoli-Cushman-derived ,- and ,-heterocyclic vinyl chlorides.

A modular and functional group-tolerant protocol for the transition metal-free coupling of novel ,- and ,-heterocyclic vinyl chlorides with terminal acetylenes and styrenes has been developed, leading to the epimerization-free synthesis of fully carbofunctionalized dihydro-1,4-oxazines/thiazines. Bicyclic morpholines have also been prepared through the interrogation of newly synthesized cross-conjugated dienes in Diels-Alder reactions. The use of environmentally benign reaction media endows the current strategy with a practical advantage.