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851.
Mamoru Hashimoto Nobuko Izuchi Kazunori Sakata 《Journal of heterocyclic chemistry》1988,25(6):1705-1708
A novel macrocycle, 5,14-dihydro-7,16-diethyldipyrazo[b,i][1,4,8,11]tetraazacyclotetradecine, has been synthesized from 1,2-diaminopyrazine and 2-ethyl-3-ethoxyacrolein. The absorption bands appearing in the energy range greater than 20000 cm?1 were attributable to the π → π transitions. The bands in the range of the 20100–23300 cm?1 show more bathochromic shift and greater intensity than those observed for corresponding 5,14-dihydro-7,16-diethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine and/or 5,14-dihydro-7,16-diethyl-(Z)-dipyrido[b,i][1,4,8,11]tetraazacyclotetradecine. The nickel(II), copper(II) and palladium(II) complexes of 5,14-dihydro-7,16-diethyldipyrazo[b,i][1,4,8,11]tetraazacyclotetradecine have been synthesized using a metal template reaction. In 1H and 13C nmr spectra, the signals of annulene skeleton for metal-free ligand and its complexes were found to observe in the lower field than those of the dibenzoanalogue. 相似文献
852.
Examination of the manner of interaction between Pd(0) and allylpalladium(II) complexes, both being involved as key intermediates in Pd-catalyzed allylic coupling, led us to discover a new role for such combinations in affecting the stereochemistry of the transformations. A similar investigation of the system involving Pd(0) and allenyl/propargyl complexes of Pd(II) led to the discovery of dinuclear Pd(I)bond;Pd(I) complexes containing bridging allenyl/propargyl ligands, which exhibited novel structural and reactivity aspects of great synthetic significance. A systematic comparison was made between the structure, stability, and reactivity of allyl and allenyl/propargyl ligands in dinuclear complexes and those in mononuclear counterparts. On the basis of MO calculations, coordination behavior specific to the ligands of the dinuclear complex is attributed to the occurrence of the back-donating interaction from filled Pdbond;Pd bonding orbitals to vacant ligand pi* orbitals. Similar bonding features are the origin of the ready synthesis of novel one-dimensional sandwich complexes composed of conjugated polyene ligands and linear polypalladium chains. A substitutionally labile dipalladium complex reacts with an equimolar amount of trienes or alkynes to give formal [4pi + 2sigma] or [2pi + 2sigma] adducts, respectively, which undergo further unique transformations with additional unsaturated substrates. 相似文献
853.
All of the enantiomers of the title compounds, the components of the pheromone of the olive fruit fly ( Gmelin), were synthesized from ()-malic acid. 相似文献
854.
Microwave spectra of ethylmethylether and its eleven isotopically substituted species were measured. The rs structure of the trans isomer was determined from the observed moments of inertia. Structural parameters of this isomer were roughly equal to those of the reported rs structure for dimethylether and diethylether. The CH2-O bond length was definitely shorter by about 0.01 Å than the CH3-O bond length and the C-C bond length was nearly equal to those of ethylchloride and bromide. The OCH3 group tilted by about 2° 13' towards lone pair electrons of the oxygen atom while no significant tilt angle was found for the CH3C group.Dipole moments of the trans isomer for the normal and two deuterated species were determined by Stark-effect measurements. For the normal species, the dipole moment was μa = 0.146 ± 0.022 D,μb = 1.165 ± 0.020 D and μtotal=1.174 ± 0.022 D making an angle of 7° 5' ± 32' with the b inertial axis. Direction of the dipole moment in the molecule was discussed.From splittings of the observed spectra, barriers to internal rotations of two CH3 groups were obtained in the one-top approximation. They were 2702 ± 7 and 3300 ± 25 cal mol?1 for the OCH3 and CH3C groups, respectively, from the analysis of splittings in the first excited CH3 torsional states. The coupling effects among two tops and the skeletal torsion were briefly discussed. 相似文献
855.
Toshikatsu Koga Kazunori Matsui 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(2):97-102
Hylleraas wave functions composed of the optimally combinedN terms (2 N 20) are presented for two-electron atoms with nuclear chargesZ = 1 (H–), 2(He), 3(Li+), 5(B3+), and 10(Ne8+). The spherically-averaged electron density (r) and electron-pair densityh(r
12) are constructed in a simple and analytical functional form from the 20-term functions. Comparison of several one- and two-electron moments r
k
and r
12
k
shows that the present density functions have near-exact accuracy. 相似文献
856.
The condensation reaction between tetraaza[14]annulene nickel(II) complex and a series of para-substituted benzoyl chlorides gave the corresponding 7,16-dibenzoylated products in 53–98% yields. The mass spectra exhibit molecular ion peaks ascribed to the 7,16-dibenzoylated products. The intense ir band due to the C?O stretching mode in these nickel(II) complexes is present in the 1650–1658 cm?1 range upon the benzoylation. Even though the ligand moiety of these six complexes is changed by benzoylation, the electronic spectra hardly vary. These nickel(II) complexes assume roughly the square-planar coordinations as judged by the ligand-field transition bands. The olefinic proton peaks at the 7- and 16-positions vanish on benzoylation in the proton nmr spectra and the proton signals of the para-substituted benzoyl groups are observed in the 2.4–8.4 ppm region. The results of the carbon-13 nmr spectra are compatible with those for the proton nmr spectra. 相似文献
857.
Tsuchiya T Shimizu T Hirabayashi K Kamigata N 《The Journal of organic chemistry》2002,67(19):6632-6637
The reactions of 18- and 21-membered unsaturated thiacrown ethers, 18-UT-6 and 21-UT-7, with CF(3)COOAg in acetone afforded novel silver(I) complexes Ag(I)(18-UT-6)(CF(3)COO) and Ag(I)(2)(21-UT-7)(CF(3)COO)(2), respectively. The crystal structure of Ag(I)(18-UT-6)(CF(3)COO) shows that the silver atom occupies the cavity of the 18-UT-6 and the geometry around the silver atom has a distorted five-coordinate square pyramidal arrangement. The crystal structure of Ag(I)(2)(21-UT-7)(CF(3)COO)(2) shows that the two silver atoms and all sulfur atoms are nearly coplanar and the two trifluoroacetate groups are located at the opposite sides of the plane. The stoichiometry for the complexation of 15-UT-5, 18-UT-6, and 21-UT-7 with CF(3)COOAg in solution was examined by (1)H NMR measurement. The titration plots of 15-UT-5 and 21-UT-7 show a distinct inflection point at 1:1 and 2:1 metal/macrocycle ratios, respectively, whereas the plot of 18-UT-6 gradually changes at the range of 1:1 to 2:1. From these results, 15-UT-5 and 21-UT-7 were found to show inclusion selectivity for number of silver ions, respectively, whereas 18-UT-6 showed low selectivity for the inclusion number of metals. Comparison of the oxidation and reduction potentials of the silver(I) complexes with those of free macrocycles and CF(3)COOAg revealed that unsaturated thiacrown ethers become difficult to be oxidized by complexation with CF(3)COOAg, and CF(3)COOAg becomes difficult to be reduced by complexation with unsaturated thiacrown ethers. 相似文献
858.
Hiroto Nagaoka Kazunori Ohsawa Takeshi Takata Yasuji Yamada 《Tetrahedron letters》1984,25(47):5389-5392
The bicyclo[5.3.1]undecane derivative 19, which was referred to the A,b ring system of taxane diterpenes, was synthesized by a base-induced fragmentation reaction of the tricyclic diol monomesylate 18 derived highly stereoselectively from 5-methyl-1,3-cyclohexadione. 相似文献
859.
Matsuda T Watanabe K Harada T Nakamura K Arita Y Misumi Y Ichikawa S Ikariya T 《Chemical communications (Cambridge, England)》2004,(20):2286-2287
A novel continuous-flow scCO(2) process for kinetic resolution of racemic alcohols can be performed with an immobilized lipase to lead to a quantitative mixture of the corresponding optically active acetates with up to 99% ee and unreacted alcohols with up to 99% ee, in which the productivity of the optically active compounds was improved by over 400 times compared to the corresponding batch reaction using scCO(2). 相似文献
860.
Direct oxidative cyclization of (eta2:eta2-CH2=CHCH2C6H4CHO)Ni(PR3) to form the nickelacycle and drastic acceleration of the cyclization by the addition of Me3SiOTf were observed. (eta2-PhCHO)Ni(PCy3)2 also reacted with Me3SiOTf to give (eta1:eta1-Me3SiOCH(Ph))Ni(PCy3)OTf. 相似文献