# Rearrangement Cascade Initiated by Nucleophilic Benzyne Attack on 3,6-Di(2-pyridyl)-1,2-diazines

## TL;DR

This paper describes a new one-step chemical reaction that creates complex structures using arynes, offering potential for pharmaceutical and material applications.

## Contribution

A novel aryne-mediated rearrangement cascade to synthesize pyrido[1,2-a]indoles linked to pyridotriazoles is introduced.

## Key findings

- The reaction forms pyrido[1,2-a]indoles and pyridotriazoles via a rearrangement cascade initiated by benzyne.
- Mild reaction conditions and structural confirmation via X-ray and NMR were achieved.
- Electron-deficient substituents improved product stability, while electron-rich ones reduced it.

## Abstract

Aryne intermediates in synthetic organic chemistry offer
versatile
routes to complex heterocyclic structures that are valuable in pharmaceuticals
and materials science. We present a one-step aryne-mediated reaction
to synthesize pyrido[1,2-a]indoles interconnected
through vinylene or 1,2-phenylene linkers to pyridotriazoles using
2-pyridyl-substituted pyridazines and phthalazines as confirmed via
single-crystal X-ray crystallography and NMR spectroscopy. This unexpected
rearrangement proceeds under mild conditions. Considering that five
bonds are broken and three new bonds are formed in the reaction between
3,6-di-2-pyridyl-1,2,4,5-tetrazine and benzyne, the yield of 16% is
fair. Electron-rich substituents on aryne precursors destabilized
the products, while electron-deficient substituents offered some stability
improvements. DFT studies could reveal the mechanism of this rearrangement.