排序方式: 共有69条查询结果,搜索用时 578 毫秒
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Siva Lakshmi Devi A Srinivasa Rao Y Suresh Y Yogeswar Reddy M Jyothi G Rajababu B Prasad VS Umamaheswar Rao V 《Magnetic resonance in chemistry : MRC》2007,45(5):424-429
We report the complete (1)H and (13)C NMR assignment of impurities of six Lopinavir (2S)-N-[(2S, 4S, 5S)-5-{[2-(2,6-dimethylphenoxy)acetyl]amino}-4-hydroxy-1,6-diphenyl hexan-2-yl]-3-methyl-2-(2-oxo-1,3-diazinan-1-yl)butan- amide. Two of the impurities are regioisomers and GCOSY used to differentiate the two structures. The spectral assignments for all six impurities were achieved by concerted application of one and two-dimensional NMR techniques ((1)H NMR, (13)C NMR, DEPT, GCOSY, GHSQC and GHMBC). 相似文献
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4-Methyl-1, 2, 4-triazoline-3, 5-dione was produced by lead tetraacetate oxidation of 4-methylurazole and allowed to react with phencyclone, 1-The resulting Diels-Alder adduct, 2, has been characterized by one-and two-dimensional 1H and 13C NMR at 300 and 75 MHz, respectively, at ambient temperatures in different solvents. The NMR data are consistent with hindered rotation of the bridgehead unsubstituted phenyl groups about the C(sp2)-C(sp3) bonds, based on numbers of absorption signals in the 1H and 13C NMR aryl region, together with magnetic anisotropic effects in the 1H spectrum. The spectral simplicity suggests further that stereochemistry at the ring junction nitrogens involves only a single isomer or very rapidly interconverting “exo”/“endo” isomers (if the ring junction nitrogens are pyramidalized). 相似文献
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由于谱峰拥挤和重迭、关附庚素的一部分1H和13C谱峰用一般核磁共振方法难于确定归属。本工作采用选择性远程DEPT、一维COSY和-维接力COSY等新技术作了研究,其1H和13C谱峰归属全部得到确定。结果有助于此类化合物的化学结构测定。 相似文献
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Brutscher B 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,167(2):170-184
2D DEPT-H(alpha,beta)C(alpha,beta)(CO)NH and 2D CT-DEPT-HC(CO)NH-TOCSY experiments are presented which allow fast resonance assignment of aliphatic protein side chains. In these 2D reduced-dimensionality experiments, two or three nuclei are frequency labeled in the indirect dimension. DEPT spectral editing reduces the number of correlation peaks detected in each 2D spectrum, and helps in amino-acid-type determination during sequential backbone resonance assignment. Applications are shown for a small 68-residue, and a highly deuterated 167-residue protein. The new experiments complement the set of 2D HNX correlation experiments, previously proposed for fast protein resonance assignment [J. Biomol. NMR, 27 (2003) 57]. 相似文献
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Ramos SS Santos L Almeida P Motherwell WB Costa MC 《Magnetic resonance in chemistry : MRC》2005,43(10):861-863
(13)C NMR chemical shift assignments of five alpha- and beta- epimeric pairs of cholestanes functionalized at C-3 are presented. Empirical increment estimations proved to be a valuable tool for the unequivocal structural elucidation when compared with the chemical shift values of cholestanes derivatized by introduction of N- and S-containing groups at C-3 in equatorial and axial positions. Moreover, the possibility is demonstrated to anticipate the effect of -OC(S)R substituents at neighboring carbon atoms of the ring A backbone. 相似文献
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Orbicoside, a new lanostane glycoside and the first from plants of the Astragalus genus, was isolated from the aerial organs of Astragalus orbiculatus Ledeb. (Leguminosae). It has the structure 23,24-lanost-9(11)-en- 3,7,16,19,23,24,25-heptaol 3-O--D-xylopyranoside. The structure of orbicoside was established using PMR and 13C NMR, which were interpreted using DEPT and 2D NMR spectroscopies 1H-1H COSY, HSQC, and HMBC. 相似文献
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Joseph K. Rugutt Nikolaus H. Fischer Marcus A. Nauman Thomas J. Schmidt Dana K. Berner 《光谱学快报》2013,46(4):711-726
The high field 1H and 13C resonances of obacunone were established by a series of I D and 2D NMR experiments. The 13C-NMR signals of the five tertiary methyl groups and all quatenary carbons were unambiguously assigned. The results confirm the stereochemical assignments at all stereogenic centres. 相似文献