Epoxidation by Dimethyldioxirane: Electronic and Steric Effects

Article abstract of DOI:10.1021/jo00250a007

The reaction of dimethyldioxirane (1) with a series of di- and monosubstituted alkenes 2-17 produced the corresponding epoxides in high yield.A kinetic study of the epoxidation of 2-17 by 1 in dried acetone showed the reaction to be of the first order with respect to both alkene and dioxirane.For certain cis/trans-dialkylalkenes, the cis compounds were found to be of ca. 10-fold greater reactivity than the corresponding trans isomers.However, cis/trans pairs of alkenes with phenyl substituents were found to be of similar reactivity.A kinetic study on the reaction of a series of substituted styrenes yielded an excellent LFER with a ρ value of -0.90.Addition of water to dioxirane reactions in acetone increased the observed rates of epoxidation.However, a tertiary allylic alcohol was found to undergo epoxidation slower than expected.The mechanistic implications of the results are discussed.