Публикации

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.

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.

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.