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 1H-benzo­[de]­quinolin-2­(3H)-ones, 4H-dibenzo­[de,g]­quinolin-5­(6H)-one, and benzo­[de]­chromen-2­(3H)-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.