Tetraaryl-1,3-dioxolane-4,5-dimethanols as catalysts for the addition of trimethylsilyl cyanide to benzaldehyde and the oxirane ring

The synthesis of 1,2-, 1,3-, and 1,4-phenylene-bis[(4R,5R)-4,5-di(hydroxydiphenylmethyl)-1,3-dioxolane]s (ortho-, meta-, and para-bis-(R,R)-TADDOLs) and bis[4-{[(4R, 5R)-4,5-di(hydroxydiphenylmethyl)]-1,3-dioxolan-2-yl}phenyl]methane was carried out. The possibilities of the use of these compounds as catalysts for the C-C bond formation in the addition of Me₃SiCN to benzaldehyde and the oxirane ring opening in cyclohexene oxide by Me₃SiCN were investigated. The catalytic activity of different bis-(R, R)-TADDOLs in this series depends on their structure. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1451–1458, August, 2007.     

Catalytic Asymmetric Synthesis of O‐Acetylcyanohydrins from Potassium Cyanide,Acetic Anhydride,and Aldehydes,Promoted by Chiral Salen Complexes of Titanium(IV) and Vanadium(V)

The utility of the chiral [Ti(μ‐O)(salen)]₂ complexes (R)‐ and (S)‐ 1 (H₂salen was prepared from (R,R)‐ or (S,S)‐cyclohexane‐1,2‐diamine and 3,5‐di(tert‐butyl)‐2‐hydroxybenzaldehyde) as catalysts for the asymmetric addition of KCN and Ac₂O to aldehydes to produce O‐acetylcyanohydrins was investigated. It was shown that the complexes were active at a substrate/catalyst ratio of 100 : 1 and produced the O‐protected cyanohydrins with ee in the range of 60–92% at −40°. Other complexes, [Ti₂(AcO)₂(μ‐O)(salen)₂] ((R)‐ 4 ) and [Ti(CF₃COO)₂(salen)] ((R)‐ 5 ), were prepared from (R)‐ 1 by treatment with different amounts of Ac₂O and (CF₃CO)₂O, and their catalytic activities were tested under the same conditions. The efficiency of (R)‐ 4 was found to be even greater than that of (R)‐ 1 , whereas (R)‐ 5 was inactive. The synthesis of the corresponding salen complexes of V^IV and V^V, [V(O)(salen)] ((R)‐ 2 ) and [V(O)(salen)(H₂O)] [S(O)₃OEt] ((R)‐ 3 ), was elaborated, and their X‐ray crystal structures were determined. The efficiency of (R)‐ 3 was sufficient to produce O‐acetyl derivatives of aromatic cyanohydrins with ee in the range of 80–91% at −40°.     

Microscopic theory of superconductivity in MgB<Subscript>2</Subscript>-type systems in a magnetic field: A neighborhood of <Emphasis Type="Italic">H</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis>2</Subscript>

We calculate the upper critical magnetic field H _c2 in the framework of a microscopic superconductivity theory with two energy bands of different dimensions on the Fermi surface with the cavity topology typical of the compound MgB₂ taken into account (an anisotropic system). We assume an external magnetic field parallel to the crystallographic z axis. We obtain analytic formulas in the low-temperature range (T/T_c ≪ 1) and also near the critical temperature ((T-T_c)/T_c ≪ 1). We compare the temperature dependence of H_c2 for a two-band anisotropic system with that of H _c2 ⁰ corresponding to a two-band isotropic system (with Fermi-surface cavities of the same topology). We determine the role of the band-structure anisotropy, the positive curvature of the upper critical field near the critical temperature, and the important role of the ratio v₁/v₂ of the velocities on the Fermi surface in determining H_c2. We also obtain the values of the parameters Δ₁ and Δ₂ along the line of the critical magnetic field. This paper is dedicated to the 90th birthday of Professor D. N. Zubarev __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 154, No. 1, pp. 113–128, January, 2008.     

α-Ferrocenylalkylation of Some Biologically Active Compounds

Russian Journal of Organic Chemistry -     

Action of phosphorus pentasulfide on 5-acetamidothiohydantoins and 4-bromo-5-acetamidopyrazoles

New condensed systems — (5,4-thiazolo)imidazoline-2-thione and pyrazolo[5,4-d]thiazoles -are formed by reaction of phosphorus pentasulfide with 5-acetamidothiohydantoins and 4-bromo-5-acetamido derivatives of pyrazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 932–934, July, 1974.     

Telomerization of propylene with methyl dichloroacetate

Conclusions The telomerization of propylene with methyl dichloroacetate includes chain transfer via the C-H and C-Cl bonds, and leads to the formation of four series of telomers, the methyl esters of chloro-substituted acids of type X[CH(CH₃)CH₂]_nCClYCO₂CH₃ (X, Y=H, Cl), and also of the telomeric esters of the higher alcohols and dichloroacetic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2150–2152, September, 1977.