Reactions of selenium dichloride and dibromide with divinyl sulfone: synthesis of novel four- and five-membered selenium heterocycles

The reactions of selenium dichloride and dibromide with divinyl sulfone leading to novel selenium heterocycles, 2,4-bis(halomethyl)-1,3-thiaselenetane-1,1-diones and 5-halo-2-halomethyl-1,3-thiaselenolane-1,1-diones, have been studied. Under the action of silica gel or pyridine, 5-halo-2-halomethyl-1,3-thiaselenolane-1,1-diones undergo facile regioselective dehydrohalogenation into 5-halo-2-methylene-1,3-thiaselenolane-1,1-diones.