Utilization of 1-oxa-2,2-(dimesityl)silacyclopentane acetals in the stereoselective synthesis of polyols

We have developed a route for the stereoselective synthesis of 1-oxa-2,2-(dimesityl)silacyclopentane acetals, intermediates in the synthesis of highly functionalized 1,3-diols. This route involves a diastereoselective conjugate addition reaction of a hydrosilyl anion, a subsequent diastereoselective enolate alkylation, and a fluoride-catalyzed intramolecular hydrosilylation reaction to afford the oxasilacyclopentane acetal. A highly selective nucleophilic substitution reaction, followed by oxidation of the C-Si bond, leads to the desired polyol.     

Alkaloids of Liriodendron tulipifera

Tashkent Agricultural Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 587–588, July–August, 1991.     

Computer interactive identification system for polycyclic aromatic hydrocarbons in reversed-phase microcolumn liquid chromatography

Summary A computer interactive identification system is proposed which is based on the relationship between retention and molecular properties such as the size and shape of polycyclic aromatic hydrocarbons (PAHs). This system offers an automatic analytical process for liquid chromatography, providing a reliable identification of the separated components. The identification can be further enhanced by the use of multiple detectors such as a multichannel UV detector. The system can be used for optimization procedures, resulting in a highly automatic complex analytical system.     

Über Oxorhodate der Alkalimetalle: β-LiRhO2

On Oxorhodates of Alkali Metals: β-LiRhO₂ We prepared hitherto unknown β-LiRhO₂ in form of black, cubic single crystals, O⁴–F4₁32, a = 841.27(6) pm, Z = 16. For a first time in case of such metal oxides we find one of the possible variants of order between the NaCl-type with random distribution and the complete ordered types like α-NaFeO₂ as a single crystal (four-circle-diffractometer PW 1100, AgKα, 100 von 109 I₀(hkl), R = 9.10%, R_w = 5.46%). The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, were calculated and discussed.     

High temperature reactions of titanium(IV) oxide with some alkali persulfates and their decomposition products

The solid state reactions between TiO₂ and Na₂S₂O₈ or K₂S₂O₈ have been investigated using TG, DTG, DTA, IR, and X-ray diffraction studies in the range of 20 to 1000°C.It has been shown that TiO₂ reacts stoichiometrically (1 : 1) with Na₂S₂O₈ in the range of 160 and 220°C forming the complex sodium monoperoxodisulfato—titanium(IV) as characterized by IR and X-ray analysis. The new complex then decomposes into the reactants above 190°C.An exothermic reaction has been observed between TiO₂ and molten K₂S₂O₇ at mole ratio 1:2 respectively and higher, in the range of 280 and 350°C. The IR and X-ray analyses have shown the formation of a complex namely, potassium tetrasulfato titanium(IV) for which the formula and structure have been proposed. This complex decomposes at higher temperatures into K₂SO₄ and a mixed sulfate of potassium and titanium. The mixed sulfate melts at 620°C and decomposes into K₂SO₄, TiO₂, and the gaseous SO₃.On the other hand, Na₂S₂O₈ decomposes in a special mode producing a polymeric product of Na₁₀S₉O₃₂. Decomposition of this species occurs after melting at 560°C into Na₂SO₄ and sulfur oxides. The decomposition reaction has been proved to be catalysed by TiO₂ itself.     

Syntheses and degradations of fluorinated heterocyclics III. Perfluoroalkyl and perfluoroalkylether-1,3,4-oxadiazoles

2,5-Bis(perfluoro-n-heptyl)-, 2-perfluoroalkylether-5-perfluoro-n-heptyl-, and 2,5-bisperfluoroalkylether-1,3,4-oxadiazoles were synthesized and characterized. 2,5-Bis(perfluoro-n-heptyl)-1,3,4-oxadiazole was thermally and hydrolytically stable at 325°C; however, in the presence of air, degradation took place at 235°C. The perfluoroalkylether analogue exhibited thermal and hydrolytic stability at 325°C; it was found to be unaffected by Jet-A fuel and air at 235°C. At 325°C in air some degradation occured as evidenced by volatiles production, oxygen consumption, and 96% starting material recovery.     

Complexation of anion exchangers based on polyimines and allyl and epoxy compounds with transition metal cations

Complexation of polymeric anion exchangers with transition metals was studied by polarographic and potentiometric titration techniques.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 10, 2004, pp. 1693–1698.Original Russian Text Copyright © 2004 by Ergozhin, Chalov, Kovrigina, Iskakova, Nikitina.     

New approach to the synthesis of dibenzodithia-and benzothiaazacrown ethers via the aromatization of 2-alkylthio(arylthio)cyclohexanes during bromination

A new scheme for the synthesis of dibenzodithiacrown ethers is proposed based on the use of substituted phenol derivatives as intermediates, prepared by aromatization of 2-alkylthio(arylthio)cyclohexanes during bromination. 1,7-Dithia-8,9,17,18-dibenzo-18-crown-6 and 1,10-dithia-11,12,20,21-dibenzo-21-crow-7 without isomers relative to position of the sulfur atoms have been synthesized, and also new thiadiazamacroheterocycles — 1,4,7-trioxa-10,19-dithia-13,16-diaza-12,17-dioxo-8,9,14,15,20,21-tribenzoheneicosane and 1,4,7,10-tetraoxa-13,22-dithia-16,19-diaza-15,20-dioxo-11,12,17,18,23,24-tribenzotetracosane.M. V. Lomonosov Moscow State University, Moscow 119899. M. V. Lomonosov Moscow State Academy for Fine Chemical Technology, Moscow 117571. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 121–127, January, 1997.     

Elimination of the 4-hydroxyl group of the alkaloids related to morphine—I

Sinomenine, an alkaloid of the Japanese plant Sinomenium acutum, was converted to the 4-phenylether by the Ullmann reaction in a good yield. The Clemmensen reduction of sinomenine-phenylether and of its derivatives gave (+)-3-methoxy-4-phenoxy-N-methyl-Δ^x-morphinan.

Hydrogenation and successive sodium-liquid ammonia reduction of (+)-3-methoxy-4-phenoxy-N-methyl-Δ^x-morphinan gave (+)-3-methoxy-N-methylmorphinan.     

Organic synthesis by means of noble metal complexes—XCIV : Palladium catalyzed hydrosilylation of monoenes and conjugated dienes

Palladium compounds and metallic palladium combined with phosphine are active catalysts of selective hydrosilylation of terminal olefins. Butadiene and trichlorosilane give a 1:1 adduct and trimethylsilane affords a 1:2 adduct. Special features of the palladium catalyzed hydrosilylation reactions are presented.