A Facile Approach to the Synthesis of 3-Acylisoxazole Derivatives by the Use of Reusable Solid Acid Catalysts

Nitrile oxides were obtained from α-nitro ketones by the use of silica-gel supported sodium hydrogensulfate (NaHSO4/SiO2) or Amberlyst 15 as solid acid catalyst, and then the corresponding 3-acylisoxaszoles were obtained from alkynes via the 1,3-dipolar ([3+2]) cycloaddition. These heterogeneous catalysts are easily separable from the reaction mixture, and reused up to the synthesis. This synthetic method provides a facile, efficient and reusable production of 3-acylisoxazoles.