Synthesis of 3-Acyl-isoxazoles and Δ<sup>2</sup>-Isoxazolines from Methyl Ketones, Alkynes or Alkenes, and <i>tert</i>-Butyl Nitrite via a Csp<sup>3</sup>–H Radical Functionalization/Cycloaddition Cascade
A novel metal-free tandem Csp3–H bond functionalization of ketones and 1,3-dipolar cycloaddition has been developed. An efficient approach to a variety of oxazole and isoxazoline derivatives is demonstrated using the 1,3-dipolar cycloaddition of alkynes and alkenes to nitrile oxides generated by reactions of methylketones with tert-butyl nitrite. This new protocol provides access to a variety of isoxazolines