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11.
Shizuko Eguchi Mitsuru Nakayama Shûichi Hayashi 《Journal of mass spectrometry : JMS》1976,11(6):574-581
The doubly charged ion mass spectra of anhydropisatin, 4-methoxyanhydropisatin, 3, 8, 9-trimethoxypterocarpen and 3, 4, 8, 9-tetramethoxypterocarpen were determined, and the fragmentation was explained by assuming that the paired electrons were partially localized in the fragmentations and by comparing the spectra with that of 3-(CD3)-anhydropisatin. Conventional mass spectra of these compounds were very simple, but the doubly charged ion spectra were sufficiently characteristic for the reliable identification. 相似文献
12.
Structures and cytotoxic activity relationship of casearins, new clerodane diterpenes from Casearia sylvestris Sw 总被引:1,自引:0,他引:1
H Morita M Nakayama H Kojima K Takeya H Itokawa E P Schenkel M Motidome 《Chemical & pharmaceutical bulletin》1991,39(3):693-697
Casearins G-R, new cytotoxic clerodane diterpenes have been isolated from the leaves of Casearia sylvestris Sw. (Flacourtiaceae). Their structures have been elucidated by spectroscopic methods and chemical conversions, and their structure-activity relationships have been discussed. 相似文献
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Excitation energies of 123 polycyclic aromatic hydrocarbons were calculated by incorporating the improved method of new-γ for the two-center electron repulsion integral into two semiempirical molecular orbital methods (CNDO/S and INDO/S). This variable method well reproduced experimental excitation energies of them. The average error of the improvement is about 0.162 (CNDO/S) or 0.237 eV (INDO/S) though the average error without the improvement is about 0.541 (CNDO/S) or 0.536 eV (INDO/S). The improvement was useful for the calculations of other organic compounds including hetero atoms, such as organic dye. 相似文献
16.
The treatment of tert-alkyl phenyl thioketones with Lawesson’s reagent (LR) gave two diastereomeric 1,3,2-dithiaphosphetane 2-sulfides in high yields. The structure of one of the major diastereomers was determined by X-ray crystallography. The reaction of 2-adamantanethione with LR yielded the corresponding spiro-1,3,2-dithiaphosphetane 2-sulfide derivative in 87% yield. 相似文献
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18.
Sachiko Yamada Keiko Nakayama Hiroaki Takayama Toshimasa Shinki Tatsuo Suda 《Tetrahedron letters》1984,25(30):3239-3242
(25)-25,26-Dihydroxy-23-oxovitamin D3 was synthesized efficiently and stereoselectively, and it was converted enzymatically to (25)-1α,25,26-trihydroxy-23-oxovitamin D3, a putative metabolite of 1α,25-dihydroxyvitamin D3. The spectral and chemical properties of (25)-25,26-dihydroxy-23-oxovitamin D3 and its 1α,hydroxylated derivative disagree with those reported for the isolated metabolite. 相似文献
19.
Antiviral activity of natural occurring flavonoids in vitro 总被引:2,自引:0,他引:2
Y Tsuchiya M Shimizu Y Hiyama K Itoh Y Hashimoto M Nakayama T Horie N Morita 《Chemical & pharmaceutical bulletin》1985,33(9):3881-3886
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