Photoredox Ni-catalyzed decarboxylative arylation of oxamic acids for amide synthesis

Decarboxylative cross-coupling of oxamic acids with (hetero)aryl halides has been accomplished through the synergistic merger of organic photoredox with nickel catalysis. Readily accessible oxamic acids serve as convenient starting materials that generate the key carbamoyl radicals via organic photoredox-catalyzed decarboxylation. This new, mild, and operationally simple amide synthesis protocol transforms a wide range of oxamic acids, along with (hetero)aryl halides, into the corresponding carbamides in good to excellent yields. This method is easily scalable and applicable to late-stage modification of complex molecules. Mechanistic data are consistent with the proposed reaction mechanism, in which the capture of carbamoyl radicals by ligated Ni(0) species occurs prior to the oxidative addition to an aryl electrophile.