G. E. Sal’nikov

Synthesis of 2,3′,4′-tricyanobiphenyl derivatives and tetraphenylphthalocyanines based thereon

The nitration of 2,3′,4′-tricyanobiphenyl with subsequent transformations of the obtained product provided 4-X-2,3′,4′-tricyanobiphenyls (X = NO2, NH2, NHCOCH3, Br, I). The condensation of the initial biphenyl or its 4-X-derivatives (X = NO2, NHCOCH3, Br, I) in the presence of zinc acetate afforded the corresponding zinc complexes of tetra(4-X-2-cyanophenyl)phthalocyanines.

Degenerate rearrangement of long-lived 9-cyclopropyl-9,10-dimethyl-9,10-dihydrophenanthren-9-ylium: Migration of cyclopropyl group

Dynamic NMR study showed that long-lived 9-cyclopropyl-9,10-dimethyl-9,10-dihydrophenanthren-9-yl cation generated from 9-cyclopropyl-9,10-dimethyl-9,10-dihydrophenanthren-9-ol in HSO3F-SO2ClF-CD2Cl2 at −100 to −75°C undergoes fast degenerate 1,2-shift of the cyclopropyl group. The Arrhenius parameters for this process were determined: Ea = 33.7 kJ/mol, log A = 13.0.

Energy barriers to carousel rearrangements of carbocations: Quantum-chemical calculations vs. experiment

By DFT method energy barriers were calculated for carousel rearrangements of bicyclo[3.1.0]hexenyl, cyclobutenyl, and homotropylium cations. A plausible agreement between calculated and experimental findings was found.

Reaction of 10,10-dimethyl-9-trimethylsiloxy-9,10-dihydrophenanthrene-9-carbonitrile with acids

The behavior of 10,10-dimethyl-9-trimethylsiloxy-9,10-dihydrophenanthrene-9-carbonitrile in trifluoromethanesulfonic acid and acid systems CF3SO3H-CD2Cl2, HSO3F-SO2ClF-CD2Cl3, and CF3COOH-CD2Cl2 were studied by NMR spectroscopy. Principal reaction schemes were determined; the first step in these schemes is protonation of the initial compound at the oxygen or nitrogen atom.

Long-Lived 9-Cyano-9,10-dimethylphenanthrenyl Cation. Migration of Cyano Group in Carbocations

Long-lived 9-cyano-9,10-dimethylphenanthrenyl cation was generated in superacidic medium, and its structure was determined by 1H and 13C NMR spectroscopy. The energy barrier to 1,2-shift of the cyano group in 9-cyano-9,10-dimethylphenanthrenyl cation was estimated by NMR and DFT calculations.

Structure of long-lived alkynyl-substituted carbocations of the phenanthrene series and their precursors

According to the NMR data, 9-(R-ethynyl)-9-hydroxy-10,10-dimethyl-9,10-dihydrophenanthrenes (R = H, Me, Ph) in superacid medium (HSO3F-SO2ClF) at low temperature undergo dehydroxylation with formation of the corresponding long-lived 10,10-dimethyl-9-(R-ethynyl)-9,10-dihydrophenanthren-9-yl cations which do not isomerize to 10-(R-ethynyl)-9,10-dimethyl-9,10-dihydrophenanthren-9-ylium. In contrast, longlived 10,10-dimethyl-9-(3,3,3-trifluoroprop-1-yn-1-yl)-9,10-dihydrophenanthren-9-yl cation derived from 9-(3,3,3-trifluoroprop-1-yn-1-yl)-10,10-dimethyl-9,10-dihydrophenanthren-9-ol undergoes partial isomerization to 10-(3,3,3-trifluoroprop-1-yn-1-yl)-9,10-dimethyl-9,10-dihydrophenanthren-9-yl cation.

Chiral schiff bases synthesized from terpenes of pinane series in asymmetric metall complex oxidation of sulfides

The absolute configuration of α-hydroxyaldehyde obtained from verbenol epoxide in the presence of clay was determined. Two new Schiff bases were synthesized from the aldehyde obtained. The compounds can be used as ligands in the asymmetric vanadium-catalyzed oxidation of sulfides to sulfoxides. The structure of initial sulfides significantly affects the value of the enantiomeric excess in the obtained sulfoxides: the highest enantiomeric excess is observed in the oxidation of thioanisole.

Structural nonrigidity of 9,9,10-trimethyland 4,5,9,9,10-pentamethylphenanthrenylium ions

DFT quantum-chemical calculations predicted structural nonrigidity of 9,9,10-trimethyl- and 4,5,9,9,10-pentamethylphenanthrenylium ions. The cross section of the potential energy surface at the nonrigidity coordinate for the first of these ions is symmetric, and for the second, asymmetric. These results were confirmed experimentally: the 13C NMR spectra of 4,5,9,9,10-pentamethylphenanthrenylium showed considerable temperature dependence of chemical shifts which is not typical of 9,9,10-trimethylphenanthrenylium.

Cyclization reactions of long-lived 10,10-dimethyl-9-phenylethynyl-9,10-dihydrophenanthren-9-yl cation

According to the NMR data, long-lived 10,10-dimethyl-9-phenylethynyl-9,10-dihydrophenanthren-9-ylium in acid medium undergoes cyclization whose direction is determined by the acidity of the medium. The cyclization in HSO3F-SbF5 superacid involves the aromatic ring in the phenanthrene core as nucleophilic component and yields 5a,6-dimethyl-4-phenyl-4,5,5a,6-tetrahydroacephenantrylene-4,6-bis(ylium). In trifluoroacetic acid the nucleophilic component is the side-chain phenyl group, and the cyclization product is neutral 8b,14b-dimethyl-8b,14b-dihydrobenzo[g]chrysen-10-yl trifluoroacetate. Both cyclization directions are observed in moderate-strength trifluoromethanesulfonic acid.

Homophenalenyl cations, new representatives of homoaromatic systems

Abstract3b,4-exo,4a,5-Tetramethyl-3b,4,4a,5-tetrahydro-4H-cyclopropa[a]phenalen-5-yl cation and its endo-epimer were proved by NMR method to belong to a new kind of homoaromatic systems: homophenalenyl carbocations.