Nucleophilic Addition of Amides to Haloalkynes: Synthesis of ( Z )-β-Halovinyl Amides as Dual Precursors of Alkylidene Carbenes and Allyl Halides.

Toward a regioselective method for the synthesis of β-halovinyl amides, we developed a transition-metal-free nucleophilic addition reaction of amides to haloalkynes. The regioselective nucleophilic addition was achieved under solvent-free conditions using phosphonates to protonate the intermediate alkylidene carbenoids, thus suppressing their decomposition. Furthermore, we demonstrate that β-halovinyl amides can serve as dual precursors of allyl halides and alkylidene carbenes to obtain functionalized indoles and pyrrolidones.