The synthesis of a-carbomethoxy-N-phenylmaleimide(CNPM) was accomplished by way of a Diels-Alder precursor from a-carbomethoxymaleic anhydride and cyclopentadiene, conversion of the anhydride functionality to N-phenylmaleimide, and finally thermolysis. Reactions of this highly electrophilic new olefin with donor olefins were studied. The Diels- Alder product with cyclopentadiene and unstable [2+ 21 cycloadducts with N- ...