Molten State and Solvent Free Systems Studied by NMR Spectroscopy: Addition Reactions Catalyzed by Transition Metal Complexes

Ananikov V.P., Beletskaya I.P., Russ. Chem. Bul. Int. Ed., 2008, 57, 754-760.
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In the present review we address scarcely studied application area of NMR spectroscopy — investigation of molten state and solvent-free systems. In such a case NMR spectra are recorded without a solvent and without magnetic field stabilization on any nucleus. Taking our recent studies of catalytic addition of sulfur- and selenium-containing compounds to alkynes as examples, we describe most important practical aspects of NMR studies and their application for solving important chemical problems.

Stereodefined Synthesis of a New Type of 1,3-Dienes by Ligand-Controlled Carbon-Carbon and Carbon-Heteroatom Bond Formation in Nickel-Catalyzed Reaction of Diaryldichalcogenides with Alkynes

Ananikov V.P., Orlov N.V., Kabeshov M.A., Beletskaya I.P., Starikova Z.A., Organometallics, 2008, 27, 4056-4061.
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We have found that ligand control over the carbon−carbon and carbon−heteroatom bond formation on the nickel center provides an easy and convenient route to symmetrical (minor) and unsymmetrical (major) isomers of sulfur- and selenium-substituted 1,3-dienes. The unsymmetrical product is a new type of 1,4-substituted conjugated diene, which was readily synthesized from alkynes and diaryldichalcogenides. The unique feature of this developed one-pot transformation is total stereodefined synthesis of the diene skeleton, controlling not only the configuration of the double bond but also the s-gauche conformation of the central C−C bond. The mechanistic study revealed the key feature of alkyne insertion into the Ni−E and Ni−C bonds (E = S, Se), which governs the direction of the chemical transformation.

Remarkable Ligand Effect in Ni and Pd Catalyzed Bisthiolation and Bisselenation of Terminal Alkynes: Solving the Problem of Stereoselective Dialkyldichalcogenide Addition to CC Bond

Ananikov V.P., Gayduk K.A., Beletskaya I.P., Khrustalev V. N., Antipin M. Yu., Chem. Eur. J., 2008, 14, 2420-2434.
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We have developed two new catalytic systems based on Ni and Pd complexes to solve the challenging problem of dialkyldichalcogenide (Alk 2E2; E=S, Se) addition to alkynes. A comparative study of two catalytic systems — Ni/PMe2Ph and Pd/PCy2Ph — has revealed that the Ni catalyst is superior with respect to high catalytic activity and more general scope relative to the Pd system. A novel synthetic methodology was developed for the preparation of (Z)-bis(alkylthio)alkenes and (Z)-bis(alkylseleno)alkenes from terminal alkynes with excellent stereoselectivity and high yields.