The protonated molecules and radical cations of meso-tetraphenylporphyrins with beta-pyrrolic substituents, when formed by fast atom bombardment (FAB) and subjected to high-energy collisions, give rise to unexpected fragment ions. The reaction involves hydrogen migration from the ortho position of the phenyl ring to the a atom of the substituent, with formation of an intramolecular, six-membered ring. The process is analogous to condensed-phase cyclizations described for the same type of compounds. The fragmentation requires the presence of a double bond in the substituent group attached to the pyrrolic ring. A rearrangement process involving anchimeric assistance by the phenyl group (analogous to an ortho effect) is proposed for the formation of these ions.

中文翻译：

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高能碰撞活化引起的β取代的内四苯并卟啉的意外断裂。

当通过快速原子轰击（FAB）形成并受到高能碰撞时，具有β-吡咯基取代基的中四苯基卟啉的质子化分子和自由基阳离子会产生意想不到的碎片离子。该反应涉及氢从苯环的邻位迁移至取代基的原子，并形成分子内六元环。该过程类似于针对相同类型化合物描述的冷凝相环化。断裂需要在与吡咯环相连的取代基中存在双键。对于这些离子的形成，提出了涉及通过苯基的嵌合辅助（类似于邻位效应）的重排过程。