Metal-free [2 + 2 + 1] annulation of alkynes, nitriles, and oxygen atoms: iodine(III)-mediated synthesis of highly substituted oxazoles.

The metal-free [2 + 2 + 1] annulation of alkynes, nitriles, and O-atoms for the regioselective assembly of 2,4-disubstituted and 2,4,5-trisubstituted oxazole compounds has been achieved by the use of PhIO with TfOH or Tf2NH. The present reaction could be applied to a facile synthesis of an anti-inflammatory drug.