Highly Strained, Fully π‐Conjugated Porphyrin Cyclophanes: Template‐free Synthesis and Global Aromaticity.

Porphyrin‐based nanohoops, nanorings, and cages with fully π‐conjugated structures are highly sought after, but their synthesis remains challenging. Herein, we report the template‐free synthesis of a highly strained, bithiophene‐bridged porphyrin cyclophane (<bold>1</bold>) from a porphyrin quinone via a stereoselective nucleophilic addition followed by intermolecular Yamamoto coupling strategy. X‐ray crystallographic analyses of <bold>1</bold> and its dication <bold>12+</bold> reveal significantly distorted cyclophane‐like geometries, with calculated strain energies of 51.2 and 80.7 kcal/mol, respectively. While the neutral compound <bold>1</bold> exhibits localized aromaticity, the dication <bold>12+</bold> is globally aromatic, with the porphyrin unit displaying weak antiaromaticity. Additionally, the dication <bold>12+</bold> undergoes nucleophilic addition with chloride, relieving strain. This work presents a novel synthetic strategy for highly strained, fully π‐conjugated systems with intriguing electronic properties and chemical reactivity. [ABSTRACT FROM AUTHOR]