Nickel-Catalyzed Addition of Benzenethiol to Alkynes: Formation of Carbon-Sulfur and Carbon-Carbon Bonds

Ananikov V.P., Zalesskiy S.S., Orlov N.V., Beletskaya I.P., Russ. Chem. Bul. Int. Ed., 2006, 55, 2109-2113.
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Nickel-catalyzed addition of benzenethiol to alkynes leads to alkenyl and dienyl sulfides; the direction of the process can be controlled by varying the PhSH/alkyne ratio. An advanced procedure, which ensures higher yields of 2-phenylsulfanylalkenes, includes gradual addition of alkyne to the other reactants. The structures of conjugated dienyl sulfides formed in the reaction were determined by 2D NMR spectroscopy.

Homogeneous Nickel Catalysts for the Selective Transfer of a Single Arylthio Group in the Catalytic Hydrothiolation of Alkynes

Malyshev D.A., Scott N.M., Marion N., Stevens E.D., Ananikov V.P., Beletskaya I.P., Nolan S.P., Organometallics, 2006, 25, 4462-4470.
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A novel homogeneous catalytic system has been developed for the regioselective hydrothiolation of alkynes based on CpNi(NHC)Cl complexes (NHC = N-heterocyclic carbene). The designed catalyst was efficient for the selective addition of a single ArS group to an alkyne and was suitable for the synthesis of vinylsulfides, without side reactions leading to bis(arylthio)alkenes. Furthermore, this catalytic system allowed for the S−H bond addition to alkynes to be performed with high regioselectivity (up to 31:1) and in good yields (61−87%). A mechanistic study showed that this reaction involved three steps: (1) a nickel-based substitution of chloride for the ArS group, (2) alkyne insertion into the Ni−S bond, and (3) protonolysis of the Ni−C bond. The intermediate CpNi(NHC)(SAr) complexes were unambiguously characterized by X-ray analysis.

An Efficient and Convenient Synthesis of beta-Vinyl Sulfides in Nickel Catalyzed Regioselective Addition of Thiols to Terminal Alkynes Under Solvent Free Conditions

Ananikov V.P., Orlov N.V., Beletskaya I.P., Organometallics, 2006, 25, 1970-1977.
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A new nanosized catalytic system has been developed for convenient preparation of β-vinyl sulfides H2CC(SAr)R with high yields (79−98%) and excellent selectivity (>98:2). Inexpensive and easily available Ni(acac)2 was used as catalyst precursor. Solvent-free conditions were combined with high atom efficiency of the ArSH addition reaction to terminal alkynes (HC⋮C−R) in order to create an environmentally friendly synthetic procedure. The mechanistic study has indicated that catalytic reaction takes place under heterogeneous conditions with alkyne insertion into the Ni−S bond as a key step.