Microwave Induced 1,3-Depolar Cycloaddition Reactions of Nitrones

Abstract

1,3-Dipolar cycloaddition reactions involving unreactive nitrones have been carried out successfully under microwave irradiations. The reaction of nitrones 1 and alkene 2 proceeded regiospecifically at atmospheric pressure and the corresponding isoxazolidines 3 were obtained in high yields.

Notes

Aliphatic conjugated nitrone and their cycloaddition reactions are least studied because of their intramolecular cyclisation.

In order to determine the reaction rate improvements the thermal reaction were also carried out without microwave energy in the solid state. The reaction proceeds similarly but the completion time is more (3–4 hrs) and the yields are also not satisfactory. Further increasing the reaction time had no significant improvement of yields rather decomposition of products occurred.