Preparation of Vinyl Sulphides

Preparation of Vinyl Sulphides.—Improved procedures for certain standard methods have been described in the recent literature. Dehydration of hydroxy-sulphides without rearrangement can be brought about with SOCla and pyridine at 0 °C. Thiophilic addition of PhLi to thioketens R R C=C=S at —78 °C 

Photoaddition of bis(methylthio)acetylene to a thione gives an a-(thiomethoxy-thiocarbonyl) vinyl sulphide R R C=C(CSSMe)SMe. Vinyl sulphides of particular interest, prepared by straightforward methods, include optically active alkyl vinyl sulphides EtCHMe(CH8) SCH=CHj amides R NHCMe= C(SR )CONHPh and 2-pyridyl vinyl sulphides. The novel sulphur-linked squaric acid analogue (23), prepared from the corresponding thiolate anion by 

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