# Synthesis of 2‑Aryl-3-(organoselanyl)‑4H‑benzo[4,5]imidazo[2,1‑b][1,3]thiazines Promoted by N‑Fluorobenzenesulfonimide (NFSI)

## TL;DR

This paper presents a new method to synthesize selenium-containing benzoimidazothiazine compounds using a safe and efficient oxidizing agent.

## Contribution

A novel electrophilic cyclization strategy using NFSI to synthesize selenium-functionalized heterocycles with high yields.

## Key findings

- 16 new selenium-functionalized benzoimidazothiazines were synthesized with yields up to 95%.
- NMR experiments helped identify reaction intermediates and clarify the mechanism.
- The method uses a broad range of substrates and a nonhazardous oxidizing agent.

## Abstract

An approach has been developed for the direct synthesis
of various
selenium-functionalized benzo­[4,5]­imidazo­[2,1-b]­[1,3]­thiazine
derivatives via the electrophilic cyclization reaction between 2-(methylthio)-1-(3-arylprop-2-yn-1-yl)-1H-benzo­[d]­imidazoles and diorganyl diselenides
promoted by N-fluorobenzenesulfonimide (NFSI). This
strategy is used to construct fused heterocyclic scaffolds based on
selenium-functionalized 4H-benzo­[4,5]­imidazo­[2,1-b]­[1,3]­thiazines using NFSI as a stable and nonhazardous
oxidizing agent in the presence of CH3CN at 80 °C.
The protocol allowed a broad substrate scope leading to the synthesis
of 16 novel selenium-functionalized benzo­[4,5]­imidazo­[2,1-b]­[1,3]­thiazines in yields of up to 95%. Furthermore, control
studies, including 1H, 19F, and 77Se NMR experiments, were conducted to identify intermediates, which
contributed to the elucidation of the reaction mechanism.