Photochemical Reactions of Some Thioparabanates

Abstract

Abstract 1,3-Disubstituted thioparabanates (I) were reduced with ethanol under the action of light to yield 2-mercaptoimidazolidine-4,5-diones (II) with or without 2-(1-hydroxyethyl)-2-mercapto-imidazolidine-4,5-dione (III). It seems that these reactions may be initiated by the n–π* transition of the lone pair in the 2-thiocarbonyl group. When dimethylthioparabanate (Ic) was irradiated with a high-pressure mercury arc in a chloroform solution of amylene, a photocycloaddition product, a trimethylene sulfide (IVa), was obtained.