Copper-Catalyzed Annulation Cascades of Alkyne-Tethered α-Bromocarbonyls with Alkynes: An Access to Heteropolycycles.

We here describe a new Cu-catalyzed annulation cascade of alkyne-tethered α-bromocarbonyls with common alkynes for the synthesis of various heteropolycycle frameworks, including 1 H-benzo[ de]quinolin-2(3 H)-ones, 4 H-dibenzo[ de,g]quinolin-5(6 H)-one, and benzo[ de]chromen-2(3 H)-one, which were constructed with high selectivity. This was achieved by two-component annulation cascades, rather than atom-transfer radical cyclization (ATRC), with alkyne-tethered α-bromocarbonyls for one-step accessing heteropolycycles via C-Br bond split, intramolecular cyclization, intermolecular [4 + 2] annulation, and aryl C(sp2)-H functionalization cascades.