Catalyst-Free, Direct, High Regio- and Chemoselective Conversion of Epoxides to Vicinal Haloesters Under Mild, Neutral, and Solvent-Free Conditions

Abstract

A catalyst-free, high regio- and chemoselective method is described for the mild conversion of wide varieties of epoxides directly to their corresponding vicinal haloesters using quaternary ammonium halides R₄N⁺X^- (X equals; Cl, Br, I; R = n-butyl, n-pentyl, n-hexyl) in the presence of an aliphatic or aromatic carboxylic anhydride at room temperature under neutral and solvent-free conditions.

GRAPHICAL ABSTRACT

Keywords:

• Carboxylic anhydride
• catalyst-free
• epoxide
• quaternary ammonium halide
• vicinal haloester

ACKNOWLEDGMENTS

We gratefully acknowledge the support of this work by the Damghan University Research Council.

Notes

^a Molar ratio is related to epoxide: (n-hexyl)₄N⁺Cl^-/ Ac₂O.

^a In all of these reactions, first a mixture of halide salt and carboxylic anhydride was stirred for 15–30 min and then epoxide was added to it.

^b Isolated yields.

^c Yields are based on NMR analysis.

^d The number in parentheses is related to 2-chloro-2-phenylethyl acetate as regioisomeric product.