Versatile and efficient method for synthesis of β-halohydrins via regioselective ring opening reaction of epoxides using cross-linked poly (4-vinylpyridine) supported HCl and HBr under solvent-free conditions

Abstract

Nucleophilic addition to epoxides is an easy step for preparation of several 1, 2-disubstituted products such as vicinal halohydrins. Chlorohydrins and other halohydrins are also versatile intermediates in the synthesis of a vast range of biologically active, natural and synthetic products. In this paper a versatile and efficient method for synthesis of vicinal halohydrins via regioselective ring opening of epoxides by using polymer-supported HCl and HBr under solvent-free conditions is described. The regioselective ring opening of various epoxides is achieved under mild and solvent-free conditions by using cross-linked poly (4-vinylpyridine) supported hydrochloric acid, [P4-VP]HCl and cross-linked poly (4-vinylpyridine) supported hydrobromic acid, [P4-VP]HBr, under heterogeneous conditions. [P4-VP]HCl and [P4-VP]HBr, act as both solid proton source and as nucleophile and consequently, the corresponding β-halohydrine product is prepared. [P4-VP]HCl and [P4-VP]HBr, can be easily regenerated and reused several cycles without their activity changing appreciably.