Dioxirane formation in ozonolysis of E- and Z-1,2-dimethoxy-1,2-diphenylethene

Abstract

Addition of ozone to E- or Z-1,2-dimethoxy-1,2-diphenylethene, E- or Z-1, in inert solvents results in formation of ~1 mole of methyl benzoate, ~0.5 and ~0.1 mole of the corresponding oxiranes 2 and dioxetanes 3, respectively, and 0.03 mole of 3,6-dimethoxy-3,6-diphenyl-1,2,4,5-tetroxane 4 at −20 °C. Product distributions vary with starting material, initial concentration, extent of reaction, and temperature. At −70 °C ~0.3 mole of trans-2 and 0.2 mole of cis-and trans-4 are formed from E-1. Addition of E- or Z-1 to solutions of excess ozone results in formation of up to 0.7 mole of (methoxy)phenyldioxirane 5, which is a strong, stereospecific epoxidizing agent.