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.