Publications

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.

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.

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.