Interrupting the [Au]-Catalyzed Nitroalkyne Cycloisomerization: Trapping the Putative α‑Oxo Gold Carbene with Benzo[c]isoxazole

The [Au]-catalyzed nitroalkyne cycloisomerization of 2-alkynylnitro­benzenes leading to anthranils has been interrupted by possible trapping of the postulated intermediate α-oxo gold carbene with an external nucleophile such as benzo­[c]­isoxazole (anthranil). At the outset, this provides a simple synthesis of highly functionalized 3-acyl-(2-formylphenyl)-2H-indazoles with the sequential C–O, C–N, and N–N bond formations. This provides indirect support for the existence of α-oxo gold carbenes in the [Au]-catalyzed internal redox processes of nitroalkynes.