Preparation of sulphur-containing nitrones from sulphides. Thermal elimination reactions of nitrones

Abstract

The Corey method for oxidation of alcohols, by using N-chlorosuccinimide and a sulphide, has been adapted to prepare, from benzophenone oxime, nitrones bearing cyclic or acyclic alkylthioalkyl groups on nitrogen. Nitrones have been prepared from dimethyl sulphide, diethyl sulphide, ethyl methyl sulphide, benzyl methyl sulphide, thiolan, thiacyclohexane, and 1,4-oxathian. Several sulphides fail to react in this reaction, and reasons are advanced for this. When heated, those nitrones having a β-hydrogen atom on the N-substituent undergo a thermal elimination reaction to form oxime and olefin. Approximate rates of elimination at 111 °C for cyclopentyl, cyclohexyl, thiolan-2-yl, and thiacyclohexan-2-yl nitrones are compared. The cyclopentyl and cyclohexyl nitrones were obtained by thermal ring opening of the isomeric oxaziridines.