High-level computational study of the stereoelectronic effects of substituents on alkene epoxidations with peroxyformic acid

A study was conducted on epoxidations of ethylene, propene and isobutene to examine how they are affected by methyl substituents. Results show that the alkene epoxidations proceeded in a concerted way via slightly unsymmetrical transition structures where the differences of carbon-oxygen bond distances at the QCISD/631G level are only 0.021 and 0.044 A. The epoxidation of 1.3-butadiene in a more polarized nature of the double-carbons of alpha,beta-unsaturated systems resulted in an unsymmetrical transition structure where the carbon-oxygen bond distances of 0.305 A at the same level.