Cobalt-Catalyzed Direct Carbonylative Synthesis of Free (NH)-Benzo[cd]indol-2(1H)-ones from Naphthylamides

A cobalt-catalyzed C-H carbonylation of naphthylamides for the synthesis of benzo[cd]indol-2(1H)-one scaffolds has been developed. The reaction employs a traceless directing group and uses benzene-1,3,5-triyltriormate as the CO source, affording various free (NH)-benzo[cd]indol-2(1H)-ones in moderate to high yields (up to 88%). Using this protocol, the total synthesis of BET bromodomain inhibitors A and B was accomplished as well.