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 2 H-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.