Selenium catalysed oxidations with aqueous hydrogen peroxide. Part I: epoxidation reactions in homogeneous solution

Several diselenides were synthesised and tested for catalytic activity in e poxidation reactions with aqueous hydrogen peroxide. Bis[3,5-bis(trifluorom ethyl)phenyl] diselenide forms the corresponding 3,5-bis(trifluoromethyl)be nzene seleninic acid (L. Syper and J. Mlochowski, Tetrahedron, 1987, 43, 20 7.) in situ, which is a highly reactive and selective catalyst for the epox idation of olefins in 2,2,2-trifluoroethanol. This is the first selenium co mpound that effectively (substrate to catalyst molar ratio s/c=200) catalys es the formation of sensitive epoxides in nearly quantitative yields.