Decarboxylative 1,4-Addition of α-Oxocarboxylic Acids with Michael Acceptors Enabled by Direct Excitation of Flavin-Dependent “Ene”-Reductases

We report herein a metal-free method to perform Giese radical addition through photoactivation of flavin-dependent enzymes. The reaction presents a sustainable method to construct carbon–carbon bonds and produce products in water with a broad substrate scope and functional group compatibility under mild blue light irradiation conditions without the cofactor cycle system popularly used. This is the first report of the application of "ene"-reductase to photocatalytic decarboxylation for C–C bond construction reaction.