A novel, general method for the synthesis of nitrile oxides: dehydration of O-silylated hydroxamic acids

[reaction: see text] O-Silylated hydroxamic acids serve as stable, readily accessible, crystalline precursors to nitrile oxides when treated with trifluoromethanesulfonic anhydride and triethylamine. Under these mild conditions in the presence of olefins O-silylated hydroxamic acids afford isoxazoline cycloadducts. This procedure represents a novel, general method for the one-step generation of nitrile oxides, which complements existing protocols.