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以连翘苷为原料,依次经水解反应、氯化铝/吡啶催化的去甲基化反应和差向异构化反应,合成了两个连翘脂素去甲基衍生物(1和2),其结构经1H NMR, 13C NMR, 2D NMR(COSY, NOESY, HSQC, HMBC), IR和MS(ESI)确证。经结构解析对比,1和2与连翘苷的大鼠体内次级代谢产物一致。 相似文献
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在鹰爪碱诱导下,2-氯甲基-4,4-二甲基噁唑啉与叔丁基苯基膦硼烷经络合反应,以43%的收率合成了光学纯度大于99%,手性中心在P上的新型手性噁唑啉氮膦配体(3); 3和铱配合物([Ir(cod)Cl]2)经络合反应以55%的收率制得两个新型手性膦噁唑啉铱络合物催化剂(1和2),其结构经1H NMR, 13C NMR, 31P NMR和元素分析表征。考察了1和2对烯烃的不对称氢化反应的催化性能。结果表明:1具有较好的催化能力,收率>92%,但催化剂的手性诱导能力较差(ee≤36%)。 相似文献
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Meng Y Yan BZ Wang HM Hu GF Liu FY Song YG Liu Y 《Magnetic resonance in chemistry : MRC》2004,42(6):564-566
1H and 13C NMR spectra of 8-C-beta-D-[2-O-(E)-p-coumaroyl] glucopyranosyl-2-(2-hydroxy)propyl-7-methoxy-5-methylchromone were completely assigned by 2D NMR observations. Especially the 1H assignments of the glucosyl and hydroxyl protons were achieved by utilizing HMQC, HMBC, 1H-1H COSY and DEPT techniques together with a heavy water exchange 1H NMR experiment. 相似文献
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Li K Wang H Cheng L Zhu H Wang M Wang SL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,84(1):1-5
Tridentate Schiff base (H(2)L) ligand was synthesized via condensation of o-hydroxybenzaldehyde and 2-aminothiophenol. The metal complexes were prepared from reaction of the ligand with corresponding metal salts presence of substituted pyridine in two different solvents (MeOH or MeCN). The ligand and metal complexes were then characterized by using FTIR, TGA, (1)H NMR and (13)C NMR spectroscopies. The FTIR spectra showed that H(2)L was coordinated to the metal ions in tridentate manner with ONS donor sites of the azomethine N, deprotonated phenolic-OH and phenolic-SH. Furthermore, substituted pyridine was coordinated to the central metal atoms. The thermal behavior of the complexes was investigated by using TGA method and dissociations indicated that substituted pyridine and ligand were leaved from coordination. This coordination of the metal complexes was correlated by (1)H NMR and (13)C NMR. Finally, electrochemical behavior of the ligand and a Ni(II) complex were investigated. 相似文献
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Benoit M Profeta M Mauri F Pickard CJ Tuckerman ME 《The journal of physical chemistry. B》2005,109(13):6052-6060
We have computed the (17)O NMR parameters of an amorphous calcium aluminosilicate (CAS) from first-principles. The atomic coordinates of a CAS glass of composition (CaO)(0.21)(Al(2)O (3))(0.12)(SiO (2))(0.67) were obtained by quenching a liquid to room temperature by the means of ab initio molecular-dynamics simulations of the Car-Parrinello type. The structure of the glass is found to be overall in good agreement with diffraction experiments. Some excess nonbridging O (NBO) atoms are found and are compensated by tricluster O atoms, i.e., by 3-fold coordinated O atoms to 4-fold coordinated Al or Si atoms. The glass coordinates were used to compute the (17)O NMR parameters using GGA-DFT and a correction of the Ca 3d orbital energy. The chemical shifts and the electric field gradients were obtained with the gauge including projector augmented-wave (GIPAW) and the projector augmented-wave (PAW) methods, respectively. The simulated 2D-3QMAS NMR spectrum of the CAS glass is in very good agreement with the available experimental data, notably because it takes into account the disorder present in the glass. This agreement further validates our CAS glass model. We show that the oxygen triclusters are not visible in a 2D-3QMAS NMR (17)O spectrum since their NMR parameters overlap with those of the Al-O-Si, Si-O-Si, or Al-O-Al sites. Finally, correlations between the structural characteristics and the values of the NMR parameters are extracted from the calculation with the aim of helping the interpretation of NMR spectra of glasses of similar compositions. 相似文献
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Two novel angular-type furanocoumarin glycosides, peucedanoside A (1) and peucedanoside B (2), along with a known compound apterin (3), were isolated from the roots of Peucedanum praeruptorum Dunn. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments including DEPT, HSQC, HMBC and ROESY. 相似文献
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The new synthesis of 10-bromo-α-chamigrene was achieved as follows;6-methyl-5-heptene-2-one was transformed into corresponding thioacetals,and then successively treated with Cp_2Ti(P(OEt)_3)_2.The intermediate reacted with mono-ketal of cyclohexane-1,4-dione,and gave the carbonyl coupling product.It was then transformed into the key intermediateγ-bisabolene via deketalization,Grignard reaction,dehydration and then furnished the target molecule by polyene cyclization,with total yield 2%. All structures we... 相似文献
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Vimalraj V Vijayalakshmi S Umayaparvathi S Krishnan AR 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(2):670-675
The Fourier transform infrared spectra, 1H NMR and 13C NMR spectra of 2-furoic hydrazide have been recorded. Optimized geometry, frequency and intensity of the vibrational bands of 2-furoic hydrazide were obtained by the density functional theory (DFT) and ab initio levels of theory and also 1H NMR, 13C NMR chemical shifts were calculated using 6-31G+(d,p) basis sets. The theoretical values were compared with experimental values. 相似文献
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Five bis(dimethylsilyl)-m-carborane-siloxane polymers with methyl, phenyl, and 2-cyanoethyl ligands were characterized by (1)H, (11)B, (13)C, and (29)Si nuclear magnetic resonance (NMR) spectroscopy. All relevant chemical shifts are reported, whereas signal assignment was confirmed by 2D NMR spectroscopy. The chemical composition of the polymers was calculated from the (1)H and (29)Si NMR spectra. Only (29)Si NMR spectroscopy was able to quantify the methoxy end group, from which the average molecular weights were calculated. The copolymer Dexsil 300 turned out to have a regular microstructure, whilst the terpolymers Dexsil 400 and Dexsil 410 have only partly regular sequences. (11)B NMR spectroscopy confirmed the m-carborane structure and revealed some low molecular weight impurities. 相似文献
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Chiral recognition mechanism of tris(4-trimethylsilylphenylcarbamate) ( 1) and tris(5-fluoro-2-methylphenylcarbamate) ( 2 ) of cellulose which are effective chiral stationary phases for HPLC were investigated using NMR spectroscopy. The phenylcarbamate derivatives are soluble in chloroform and exhibited chiral discrimination for several enantiomers in NMR as well as in HPLC. Especially, enantiomers of 2,2'-dihydroxy-1,1'-binaphthyl ( 4 ) were distinctly discriminated by 2 in 1H and 13C NMR spectroscopies. The binding geometry and dynamics between 2 and the enantiomers of 4 were investigated on the basis of spin-lattice relaxation time, 1H NMR titrations, and intermolecular NOEs in the presence of 2. These NMR data were fully consistent with the chromatographic elution order. On the basis of these results, combined with molecular modeling, the chiral discrimination mechanism is proposed. 相似文献
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Calladine JA Duckett SB George MW Matthews SL Perutz RN Torres O Vuong KQ 《Journal of the American Chemical Society》2011,133(7):2303-2310
Manganese propane and manganese butane complexes derived from CpMn(CO)(3) were generated photochemically at 130-136 K with the alkane as solvent and characterized by FTIR spectroscopy and by (1)H NMR spectroscopy with in situ laser photolysis. Time-resolved IR spectroscopic measurements were performed at room temperature with the same laser wavelength. The ν(CO) bands in the IR spectra of the photoproducts in propane are shifted to low frequency with respect to CpMn(CO)(3), consistent with formation of CpMn(CO)(2)(propane). The (1)H NMR spectra conform to the criteria for alkane complexes: a high-field resonance for the η(2)-CH protons that shifts substantially on partial deuteration of the alkane and exhibits a coupling constant J(C-H) on (13)C-labeling of ca. 120 Hz. The NMR spectrum of each system exhibits two diagnostic product resonances in the high-field region for the η(2)-CH protons, corresponding to CpMn(CO)(2)(η(2)-C1-H-alkane) and CpMn(CO)(2)(η(2)-C2-H-alkane) isomers. Partial deuteration of the alkane at C1 results in characteristic strong isotopic perturbation of equilibrium of the η(2)-CH resonance of CpMn(CO)(2)(η(2)-C1-H-alkane). With propane-(13)C(1), the η(2)-CH resonance of CpMn(CO)(2)(η(2)-C1-H-alkane) isomer exhibits (13)C satellites with J(C-H) = 119 Hz. The corresponding resonance of CpMn(CO)(2)(η(2)-C2-H-alkane) is identified by use of propane-2,2-d(2). The lifetimes of the (η(2)-C1-H-alkane) isomers of the manganese complexes were determined by NMR spectroscopy as 22 ± 2 min at 134 K (propane) and 5.5 min at 136 K (butane). The corresponding spectra and lifetimes of the CpRe(CO)(2)(alkane) complexes were measured for reference (CpRe(CO)(2)(propane) lifetime ca. 60 min at 161 K; CpRe(CO)(2)(butane) 13 min at 171 K). The lifetimes determined by IR spectroscopy were similar to those determined by NMR spectroscopy, thereby supporting the assignments. These measurements extend the range of alkane complexes characterized by NMR spectroscopy from rhenium and rhodium derivatives to include less stable manganese derivatives. 相似文献
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