Stereoselective Intermolecular Nitroaminoxylation of Terminal Aromatic Alkynes: Trapping Alkenyl Radicals by TEMPO

The vinyl radical
is one of the most unstable organic radicals.
It is demonstrated that a nitro radical attacks phenylacetylene and
makes the phenyl ring deconjugated with a double bond so that the
resulting vinyl radical may be stabilized by delocalization to the
phenyl ring’s π orbital and easily trapped by TEMPO.
It is noteworthy that all desired products were obtained in moderate
to good yields in an (E)-configuration.