Catalyst-Free Formation of Nitrile Oxides and Their Further Transformations to Diverse Heterocycles.

The formation of nitrile oxides with diazocarbonyl compounds by nitrosyl transfer from -butyl nitrite under mild conditions and without the use of a catalyst or an additive is reported. This transformation is broadly applicable to the synthesis of furoxans by dimerization and isoxazoles and isoxazolines by cycloaddition. This methodology is also applied for the millimole-scale synthesis of two biologically active compounds. The formation of the nitrile oxide from a diazoacetamide is stable and confirmed experimentally.