Efficient Reduction of Electron-Deficient Alkenes Enabled by a Photoinduced Hydrogen Atom Transfer

Direct hydrogen atom transfer from a photoredox-generated Hantzsch ester radical cation to electron-deficient alkenes has enabled thedevelopment of an efficient formal hydrogenation under mild, operationally simple conditions. The HAT-driven mechanism, key to circumventthe problems associated with the low electron affinity of alkenes, is supported by experimental and computational studies. The reaction is appliedto a variety of cinnamate derivatives and related structures, irrespective of the presence of electron-donating or electron-withdrawingsubstituents in the aromatic ring and with good functional group compatibility.