Reaction of 3-phenylglycidic esters. Part 2. Stereo- and regio-selectivity in the oxirane ring opening of methyl trans-3-(4-methoxyphenyl)glycidate with various thiophenols and the effects of solvent and temperature

Abstract

The effects of the solvent and temperature on the reaction of the trans-glycidate (1) with various substituted thiophenols (2) in the presence or absence of a catalyst have been investigated. The temperature had a surprisingly large effect on the stereochemistry of the oxirane ring-opening of (1). At room temperature, the erythro-isomer (4)(trans-opening product) was obtained as a major product in the absence of catalyst, while the cis-opening product (3)(threo-isomer) was produced predominantly at higher temperature. On the other hand, in a dipolar aprotic solvent, the regioisomer (5) was formed, the yield increasing with the electron-donating ability of the substituents on (2). The formation of compound (5) may involve single-electron transfer as a key step.