Reaction of dicyano epoxides with thiocyanate ion: route to α-thiocyanato derivatives or to 2-acetylimino-1,3-oxathioles and X-ray crystal structure of 2-acetylimino-4-(4-tolyl)-1, 3-oxathiole-5-carbonitrile

Abstract

β-Aryl dicyano epoxides reacted as synthetic equivalents of ketene dications with KSCN in aq. dimethyl sulfoxide or EtOH, or with NH₄SCN in acetonitrile, to give α-thiocyanato derivatives. When Ac₂O was used as a solvent, the 1,3-oxathiolane intermediates were trapped as 2-acylimino-1,3-oxathioles. This new synthetic route to 1,3-oxathioles was extended to 1,3-oxaselenoles by using KSeCN as the reactant in Ac₂O. The crystal structure of an important intermediate compound, 2-acetylimino-4-(4-tolyl)-1,3-oxathiole-5-carbonitrile, was determined by means of X-ray diffraction.