Formation of propanedithioamide and 1,2-dithiole derivatives from reaction of the lithio derivative of 1-phenylthiomethyl-3,5-dimethylpyrazole with PhNCS and coordination behavior of propanedithioamide on tungsten carbonyl

• Reaction of lithio derivative of phenylthiomethyl-3,5-dimethylpyrazole with PhNCS.
• Propanedithioamide and 1,2-dithiole derivatives were obtained.
• The CS bond cleavage induced by alkyllithium was observed.
• (3,5-Dimethylpyrazol-1-yl) carbene was captured.

Treatment of 1-phenylthiomethyl-3,5-dimethylpyrazole with n-butyllithium, and subsequently with phenyl isothiocyanate yielded 2-(3,5-dimethylpyrazol-1-yl)-2-(phenylthio)thioacetanilide, 2-(3,5-dimethylpyrazol-1-yl)thioacetanilide, N,N′-diphenyl-2-(3,5-dimethylpyrazol-1-yl)propanedithioamide and 5-anilino-4-(3,5-dimethylpyrazol-1-yl)-3-phenylimino-1,2-dithia-4-cyclopentene, respectively. Reaction of the propanedithioamide derivative with W(CO)5THF has been investigated, which gave a bis(chelate) tungsten complex through two relatively soft sulfur atoms. All these newly synthesized compounds were characterized by NMR and HRMS spectroscopy (or elemental analysis), and their structures were unambiguously confirmed by X-ray crystallography. Two possible pathways, including a carbanion or a carbene intermediate formed via the CS bond cleavage, have been suggested to explain the formation of propanedithioamide and 1,2-dithiole derivatives.

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