# Pyridine Into Pyrrole Transformation Induced Within the Confinement of the Macrocycle

## TL;DR

The paper describes a chemical transformation where a pyridine ring contracts into a pyrrole ring within a macrocycle, revealing unique reactivity and coordination properties.

## Contribution

The novel contribution is the contraction of a six-membered pyridine ring into a pyrrole ring within a porphyrin framework.

## Key findings

- The reversible cleavage of C–O bonds was observed during the transformation.
- Selective demetallation of the outer metal ion was achieved under mild conditions.

## Abstract

The pyridine contracted to form the pyrrole ring. This transformation belongs to a unique class of reactions with the fundamental characteristic of the cleavage of the aromatic structure. By investigating the unusual coordination chemistry of N‐confused pyriporphyrin with silver and gold ions, we observed this process and obtained several complexes that exhibited remarkable reactivity. This includes the reversible cleavage of C–O bonds and the selective demetallation of the outer metal ion.

This work demonstrates the nontrivial reactivity of pyridine incorporated into a porphyrin framework. The most significant achievement is the contraction of the six‐membered ring to a pyrrole ring, which is a phenomenon of great interest to researchers in this field. In addition, under controlled and mild conditions, the reversible formation of C–O bonds and the coordination of the outer gold ion are also observed.