# Vilsmeier–Haack complex formation by Fe3O4@SiO2@CS@POCl2-x/DMF: an efficient catalyst for conversion of epoxides to β-bromoformates

## TL;DR

A new catalyst efficiently converts epoxides to β-bromoformates using a Vilsmeier–Haack complex under mild conditions.

## Contribution

A magnetic core-shell catalyst enables efficient and regioselective conversion of epoxides to β-bromoformates.

## Key findings

- The catalyst Fe3O4@SiO2@CS@POCl2-x/DMF efficiently forms β-bromoformates from epoxides.
- Removing DMF leads to the formation of vic-dihalide compounds.
- The process is environmentally friendly and simplifies product isolation.

## Abstract

The in situ generation of the Vilsmeier–Haack complex was studied by combining Fe3O4@SiO2@CS@POCl2-x with N,N-dimethylformamide (DMF), demonstrating remarkable efficiency and regioselectivity in transforming epoxides into β-bromoformates. The reported yields were notably high and were achieved under mild reaction conditions. Interestingly, the removal of DMF led to the synthesis of vic-dihalide compounds. The product of this transformation depended on the specific details of how the experiment was done, highlighting how sensitive the process is to different ways of conducting the experiment. The use of a magnetic core-shell catalyst, Fe3O4@SiO2@CS@POCl2-x, facilitates a straightforward work-up procedure, simplifying the isolation of the desired products. Furthermore, the reactions were conducted under clean and neutral conditions, contributing to their environmentally friendly nature.