Retro-Diels-Alder reaction using bicyclo[2.2.2]octatriene-fused pyrrole during porphyrin synthesis

Porphyrin synthesis using 4,7-etheno-4,7-dihydro-2H-isoindole and tripyrranedicarbaldehyde gave a porphyrin derivative bearing no bicyclo[2.2.2]octatriene moiety as well as the targeted bicyclo[2.2.2]octatriene-fused porphyrin.

The retro-Diels-Alder reaction partially occurred in the preparation of bicyclo[2.2.2]octatriene-fused porphyrins.