Copper-Catalyzed Divergent 1,4-Polyhaloalkylcyanation of 1,3-Enynes.

We report a switchable copper-catalyzed divergent 1,4-polyhaloalkylcyanation of 1,3-enynes to construct a series of polyhalogenated allenes with high chemoselectivity and regioselectivity. The 1,4-dichloromethylcyanation of 1,3-enynes is realized by merging aminoalkyl radical-induced homolytic activation of carbon-halogen bonds with copper catalysis, while employing dtbbpy as ligands enables 1,4-trichloromethylcyanation of 1,3-enynes by hydrogen atom transfer (HAT) reactions of chloroform. Mechanistic investigations indicate that the reactions involve the selective generation of polyhalomethyl radicals by HAT or XAT process.