Abstract
A visible-light-induced photoredox-catalyzed regioselective and
stereoselective C(sp2)-H amination of enamides with
bench-stable and easily accessible N-aminopyridium salts is
developed, affording synthetically and biologically prominent vicinal
1,2-diamine scaffolds in broad substrate scope and excellent functional
group compatibility. The transformation proceeded through a radical
pathway involving the Giese addition of the relatively electrophilic
N-centered amidyl radical species to nucleophilic β-olefinic
position of enamides followed by the ensuing single electron oxidation
and β-H elimination, delivering geometrically-defined
Z-configured β-amino enamides. The operational simplicity,
environmentally friendliness and cost efficiency of this methodology has
paved a new avenue to enrich the arsenal of synthetically crucial
functionalized enamides and their derivatives.