Rearrangement of epoxides by nickel reagents

Abstract

Epoxides are one of the most versatile intermediates that serve as prominent building block in organic synthesis. Not only are these compounds easily prepared from a variety of starting materials, but also the inherent polarity and strain of their ring makes them susceptible to reaction with a large number of reagents. This work focused on the development of an efficient procedure for the rearrangement of substituted epoxides produced aldehydes and ketones in high to excellent yield. The rearrangement process follows a uniform pattern of hydrogen atom at B-position migration. Regioselectivity for a C-O bond cleavage of eepoxide via Lewis acid promoted was depended on the substitution pattern of epoxides. For the alkyl-substituted epoxides, the reaction furnished bromohydrins in high yield through a predominantly Sn20type mechanism. This procedure is very mild, inexpensive and insensitive to air compared to those catalyzed with other Lewis acid.