Selective 1,2-dihalogenation and oxy-1,1-dihalogenation of alkynes by N-halosuccinimides

1,2-Dihalogenation and oxy-1,1-dihalogenation of alkynes by N-halosuccinimides can be selectively realized through using different reaction conditions. α,β-Dihalo alkenes were obtained exclusively using THF as solvent without using any catalyst, while α,α-dihalo ketones were synthesized using a mixed solvent of THF and H₂O in the presence of FeCl₃·6H₂O. Terminal aromatic alkynes are smoothly transformed into α,α-dihalo ketones on water without a catalyst.