Abstract

An environmentally benign and practical preparation method for the Vilsmeier-Haack reagent (VH) has been developed by using phthaloyl dichloride with DMF in toluene or 2-chlorotoluene. Phthalic anhydride as the byproduct was recovered in high yield by simple filtration. Some aromatic acids have been transformed into the corresponding acid chlorides in good yields by employing the isolated VH. Treatment of primary or secondary alcohols with VH gave alkyl formates or alkyl chlorides by depending on the reaction conditions.

Highlights

  • We have recently reported a new method for the preparation of the Vilsmeier-Haack reagent (VH) [1,2,3,4,5,6]

  • We show some examples of synthesis of acid chlorides from carboxylic acids, alkyl formates from alcohols, and alkyl chlorides from alcohols using the OPC-VH reagent prepared through the new method

  • We first examined the use of toluene as a solvent for the preparation of the OPC-VH reagent

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Summary

Introduction

We have recently reported a new method for the preparation of the Vilsmeier-Haack reagent (VH) [1,2,3,4,5,6]. Our method obviates the use of toxic reagents such as phosgene, thionyl chloride, or phosphoryl chloride, which are used in the conventional method It involves synthesis of VH reagent from N,N-dimethylformamide (DMF) and phthaloyl dichloride (OPC) in 1,4-dioxane (Scheme 1) [7]. We show some examples of synthesis of acid chlorides from carboxylic acids, alkyl formates from alcohols, and alkyl chlorides from alcohols using the OPC-VH reagent prepared through the new method. Products of these syntheses do have not contaminants such as sulfur or Scheme 1.

An Improved Method for Preparing the OPC-VH Reagent in Aromatic Solvents
Examples of Synthesis of Acid Chlorides Using the OPC-VH Reagent
Synthesis of Alkyl Formates or Alkyl
A CH2Cl2 rt
Experimental
Preparation of OPC-VH Reagent from DMF with OPC in OCT
Representative Example for Method A
Representative Example for Method B
Synthesis of Alkyl Chlorides from Alcohol Using the OPC-VH Reagent

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