1,3-Dipolar cycloaddition reaction of aryl nitrile oxides with alkenes using imidazole and pyridine containing reusable polymeric base catalysts

ABSTRACT

Cross-linked poly-1-(4-vinylbenzyl)imidazole and cross-linked poly-4-vinylpyridine have been prepared from respective vinyl monomers using different quantities of divinylbenzene as a cross-linker by radical polymerization. The polymeric bases were characterized by FT-IR, TGA, field emission-scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. Their swelling behavior was also studied. They were used as base catalysts for 1,3-dipolar cycloaddition reaction of aryl nitrile oxides, generated in situ from N-hydroxyimidoyl chloride, with N-phenylmaleimide and ethyl acrylate, to obtain 3-arylisoxazolines. Both the bases gave excellent results. These polymers were reusable, safe to use, and provided good alternative for organic nonreusable bases like pyridine and triethylamine which are hazardous.

GRAPHICAL ABSTRACT

KEYWORDS:

• 1,3-Dipolar cycloaddition
• nitrile oxide
• poly-4-vinylpyridine
• polymeric base catalyst

Acknowledgment

Author Nilesh N. Korgavkar is thankful to the University Grant Commission (UGC), New Delhi, India for UGC/SAP/DRS fellowship.