Selective [5 + 1] and [5 + 2] Cycloaddition of Ynamides or Propargyl Esters with Benzo[d]isoxazoles via Gold Catalysis

Benzo­[d]­isoxazoles are found to act as novel nucleophiles to undergo gold-catalyzed [5 + 1] or [5 + 2] cycloaddition reactions with ynamides. The reaction provides a concise and chemoselective access to polysubstituted 2H-benzo­[e]­[1,3]­oxazines or benzo­[f]­[1,4]­oxazepines. In addition, benzo­[d]­isoxazoles can also react with gold-carbene intermediates derived from propargyl esters to afford [5 + 1] annulation products.