# Facile Synthesis of Polysubstituted Pyridines via Metal-Free [3+3] Annulation Between Enamines and β,β-Dichloromethyl Peroxides

## TL;DR

This paper presents a simple, metal-free method to create complex pyridine compounds using a [3+3] annulation reaction under mild conditions.

## Contribution

A novel metal-free [3+3] annulation strategy for synthesizing polysubstituted pyridines without radical initiators or transition metals.

## Key findings

- The method works under mild conditions with broad substrate scope and excellent functional group tolerance.
- Mechanistic studies reveal a Kornblum–De La Mare rearrangement followed by C-Cl bond cleavage and cyclization.
- The approach provides a practical and efficient route for constructing complex pyridine scaffolds.

## Abstract

Our work introduces a facile and efficient metal-free [3+3] annulation approach for the synthesis of polysubstituted pyridines via the reaction between β-enaminonitriles and β,β-dichloromethyl peroxides. This strategy operates under mild conditions, demonstrating broad substrate scope and excellent functional group tolerance. Mechanistic investigations suggest that the reaction proceeds through a Kornblum–De La Mare rearrangement followed by SNV-type C-Cl bond cleavage and intramolecular cyclization/condensation. By circumventing the need for transition metal catalysts or radical initiators, our method offers practical utility in organic synthesis and provides a new avenue for the rapid construction of complex pyridine scaffolds.