Evidence for the intermediacy of arylbenzylnitrenium ions in the thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile

In contrast to the diaryl, dialkyl, alkylaryl, and parent series, nothing is known about the generation and chemical behavior of arylbenzylnitrenium ions. Herein, we report that these species can be generated by a process involving an unprecedented thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile. The products from these reactions are dramatically dependent upon the nature of the nitrone. Most of the observed chemistry originates from the singlet state.