Copper-Catalyzed Cascade Transformation of Homopropargyl Azides into Trifluoromethylated Nitriles via C-C Cleavage.

A cascade reaction of homopropargyl azides in the presence of a Cu catalyst was achieved, affording 3-(trifluoromethyl)but-3-enenitriles with good yields and excellent regioselectivity. This reaction appears to be the first direct conversion of homopropargyl azides into trifluoromethylated nitriles. Mechanistic studies indicate that the transformation proceeds by addition of a CF3 radical to the alkyne, C-C cleavage by 1,4-aryl radical migration, and nitrile formation. This protocol provides a novel strategy for transforming azides into nitriles via C-C cleavage derived from radical migration.