Vilsmeier-Haack Reagent (Halomethyleneiminium Salt)

Introduction

The Vilsmeier-Haack reagent (halomethyleneiminium salt) formed from the interaction of dialkyl formamides such as DMF with POCl₃ has attracted the attention of synthetic organic chemists since its discovery in 1927. [1] It is one of the most commonly used reagents for the introduction of an aldehydic (CHO) group into aromatic and heteroaromatic compounds. [2]

Some interesting cyclisation reactions have also been reported under Vilsmeier conditions. [3] In addition, certain striking applications eg halogenation, alkylation (methylation) and haloalkylation have been recently reported. [4]

References

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