V. V. Shchepin

Reactions of sodium enolates derived from 6-aryl-3,5,5-trimethyl-2,3,5,6-tetrahydropyrane-2,4-diones with substituted benzenesulfonyl chlorides and arenediazonium salts

Sodium enolates derived from 6-aryl-3,5,5-trimethyl-2,3,5,6-tetrahydropyrane-2,4-diones react with substituted benzenesulfonyl chlorides to give the corresponding O-sulfonation products, 6-aryl-4-(4-R-phenylsulfonyloxy)-3,5,5-trimethyl-5,6-dihydropyrane-2-ones. Reactions of the title compounds with arenediazonium tetrafluoroborates afford 6-aryl-3-arylazo-3,5,5-trimethyl-2,3,5,6-tetrahydropyran-2,4-diones as mixtures of syn and anti isomers.

Spatial Electron Density Distribution of Chlorine Atoms in Molecules of the Series 4-XC6H4MCCl2C(O)C6H5 (M = S and Se)

Abstract The 35Cl NQR frequencies and EFG asymmetry parameters at the 35Cl nuclei have been measured for compounds of the series 4-XC6H4MCCl2C(O)C6H5 (M = S and Se, X = H and CH3) at 77 K. The electron distribution at the Cl atoms in all the compounds studied differs from axial symmetry, and is unequal for the two Cl atoms of the CCl2 group. The results of the measurements imply pσ-electron density nonequivalence of Cl atoms in the CCl2 group of these molecules.

Spatial Electron Density Distribution of Chlorine Atoms in Molecules of the Series Cl2C = CXX'

Abstract The EFG asymmetry parameters at 35Cl nuclei have been measured for polycrystalline compounds of series Cl2C = CHX (X = OR, OCOR) and Cl2C = C(Cl)OCOR at 77 K. For the Cl trans-atoms in molecules Cl2C = CHX, the q values are equal or close to zero. For the Cl cis-atom of these compounds and for all Cl atoms of compounds Cl2C = C(Cl)OCOR, η ~ 6 - 9%. It was shown that the deviation from the axial symmetry of electron distribution of Cl atoms in these compounds is due to the influence not of the geminal, but of a vicinal atom or group directly through the field. The expected p, π -conjugation between the unshared electron pair of halogen and the Ti-electron system of double bond is absent in the molecules studied.