Exo-Cyclization: Intermolecular Methylene Transfer Sequence in Au-Catalyzed Reactions of O-Homopropargylic Oximes.

The Au-catalyzed reactions of O-homopropaylic oximes afforded the 3-alkenylated isoxazolines in good to high yields. The mechanistic studies suggest that the reaction proceeds through an exo-cyclization followed by intermolecular methylene group transfer. In addition, oligomeric species of the starting material were observed in the reaction mixture by mass spectra, supporting our proposed mechanism, which proceeds through a repeated intermolecular C-C bond forming process.