Gold(III)-catalyzed bicyclizations of alkylidenecyclopropane-tethered ynones for divergent synthesis of indene and naphthalenone-based polycycles

A gold(III)-catalyzed cascade oxidation/cyclization of alkylidenecyclopropane-tethered ynones for the assembly of diverse polycycles by employing different N-oxides with distinct nucleophilic properties is reported. This protocol enables the synthesis of cyclopentene-fused indenes and cyclobutane-fused naphthalenones in moderate to excellent yields using common starting materials in the presence of 2,6-Cl2-pyridine N-oxide as an indispensable co-ligand of the gold(III) catalyst and 8-Me-quinoline N-oxide as an oxidant, respectively. Notably, compound 3h showed promising antibacterial activity against R. solanacearum (MIC = 2 μg mL−1), and its preliminary antibacterial mechanism was also explored.