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101.
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Werner Tochtermann Gunter-Rudolf Schröder Günther Snatzke Eva-maria Peters Karl Peters Hans Georg von Schnering 《欧洲无机化学杂志》1988,121(9):1625-1635
Tetrahydrofurans and Lactones, I. - Synthesis and Reactions of Chiral 2,5-Bridged Tetrahydrofurans - A New Approach to Optically Active γ-Lactones and γ-Bislactones Diels-Alder reaction of 3,4-hexamethylenefuran with acrylic acid gives the carboxylic acid 1a with high endo selectivity. 1a was separated into the enantiomers via the α-phenylethylammonium salts. Comparison of the CD spectra of (−)- 1a and (−)- 3 and the X-ray structural analysis of the camphanoyl derivative (−)- 4b lead to the 1R,2S,4S configuration of (−)- 1a as well. The 2,5-bridged tetrahydrofuran (−)- 5 with all-cis and RSS configuration is obtained by ozonolysis of the ester (−)- 1b . (−)- 5 can be oxidized to the γ-lactone (2R,3S)-(−)- 6 with sodium metaperiodate/potassium permanganate in 22% yield. Hydride reduction of (−)- 6 under various conditions leads to the γ-bislactones (−)- 8 and (−)- 9 or to the bislactol (−)- 10 . (−)- 8 has the same absolute configuration as the naturally occuring (−)-canadensolide. 相似文献
104.
Circular dichroism and optical rotatory dispersion of anisotropic solutions of testosterone propionate in cholesteryl chloride/cholesteryl laurate have been measured with light propagating parallel to the optical axis of the uniaxial system. Comparison of both effects by the Kramers-Kronig relation excludes falsification by interference with linear birefringence and dichroism effects. 相似文献
105.
Hydroxo Compounds. 9. Barium Oxohydroxostannate(II) Ba[SnO(OH)]2 The pale yellow barium hydroxostannate(II), to which different stoichiometries have been assigned in the past, is now identified doubtlessly as Ba[SnO(OH)]2. The compound crystallizes in the monoclinic space group P21 (a = 759.4(2) pm, b = 576.2(1) pm, c = 717.4(2) pm, β = 107.67(2)°, Z = 2, R = 0.038, 645 Ihkl) and exhibits a typical layer structure. Ba[SnO(OH)]2 contains a new structural element in tin(II) chemistry, which is a one dimensional polyanion [SnO(OH)]? with syndiotactical conformation. In the context with the structures of two Na-hydroxostannates(II) which were characterized recently, the polyanion can be looked at as an intermediate condensation product of a (topotactical ?) reaction to SnO which all known hydroxostannates(II) undergo. 相似文献
106.
Lobinger P Jarzina H Roesky HW Singh S Kumar SS Schmidt HG Noltemeyer M Freyhardt HC 《Inorganic chemistry》2005,44(25):9192-9196
A novel synthetic approach is given for the preparation of a metal-organic lanthanide sol-gel precursor solution and its application for the production of coated conductors. Besides all other problems concerning the technical process itself, the key to a successful deposition of oxide layers is the choice of the precursor solution and the understanding of the mechanism of deposition. Moreover, the isolation and characterization of the species involved in the reaction is very important. Regarding the complex process occurring during the formation of the surface layer, it is obvious that the best choice should have a compound already containing the final composition of the layer. Two compounds of composition [Y(OAc)3(H2O)2]2 and [Y(OAc)3]2(H2O) were isolated from their precursor solution and characterized by X-ray structural analysis. A short outlook will give an insight into the possible bonding mechanisms of the surface layer. These experiments were made with the mixed metal-oxide system yttrium-stabilized zirconium oxide, which is widely used as a substrate for superconducting oxides. A study of the structure of hydrated yttrium acetates, by single-crystal X-ray diffraction, infrared spectra, and elemental analysis demonstrates that there are two separate structures for hydrated yttrium acetates, which play a role as an intermediate in the building of ceramic oxide layers for coated conductors. 相似文献
107.
A synthesis of twista-4,9-diene ( 17 ) from tricyclo[4.3.1.03,8]dec-4-en-10-one ( 2 ) is described. 相似文献
108.
Chemistry and Structural Chemistry of Phosphides and Polyphosphides. 27. Bariumdecaphosphide BaP10 Black, reflective crystals of BaP10 are formed by the reaction of BaP3 with red phosphorus at 1 050 K. The absorption edge at 765 nm corresponds to a band gap of 1.62 eV. The compound is resistant to both acids and bases. The thermal decomposition to Ba3P14 and then to BaP3 and other lower phosphides occurs at 725 K. BaP10 crystallizes in the orthorhombic space group Cmc21 (No. 36) with 4 formula units (a = 645.2(1), b = 1 258.9(2), c = 1 192.7(2) pm). The structure (632 reflections hkl; R = 0.019) contains the 2-dimensional infinite polyanion [P102?], which also characterizes the structure of TlP5. It originates through the connection of 1-dimensional pentagonal phosphorus tubes, which corresponds to those in the structure of Hittorf's phosphorus and KP15 (bond lengths P? P = 215.0–224.5 pm). Ba is coordinated by 12 P-atoms with distances of 332.7 pm to 374.3 pm. 相似文献
109.
110.