共查询到20条相似文献,搜索用时 250 毫秒
1.
A new limonoid named rohituka-15 1,with a known limonoid dregeana-1 2, was isolated from the seed of Aphanamixis polystachya (Meliaceae). The ^13C NMR data assignment of dregeana-1 2 and the structural clucidation of the new compound 1 were based on spectral analysis including ^1H-^1 COSY,HMQC and HMBC experments. 相似文献
2.
CHUNG ILL-Min ALl Mohd CHUN Se-Chul LEE Sun-Joo SAN Ka-Yiu CHRISTIE A. M. Peebles AHMAD Ateeque 《中国化学》2007,25(11):1695-1699
Two new compounds cadin-2-en-1β-ol-1β-D-glucuronopyranoside (1), guaia-l,7-dien-3β,13-diol-13α-D- glucofuranoside (2) along with three known compounds have been isolated from the culture hairy roots of Catharanthus roseus. Their structures have been elucidated with the help of 500 MHz NMR using 1D and 2D spectral methods: viz: ^1H and ^13C NMR, ^1H-^1H COSY, ^1H-^13C HETCOR and DEPT aided by ELMS, FAB-MS, HR-FABMS and IR spectroscopy. 相似文献
3.
Nuclear magnetic resonance (NMR) spectroscopic analysis of metabonome/metabolome has widespread applications in biomedical science researches. However, most of NMR resonances for urinary metabolites remain to be fully assigned. In the present study, human urine samples from two healthy volunteers were pre-treated with C18 solid-phase extraction and the resultant 5 sub-fractions were subjected to one- and two-dimensional NMR studies, including 1H J-Resolved, 1H-1H COSY, 1H-1H TOCSY, 1H-13C HSQC, and HMBC 2D NMR. More than 70 low molecular weight metabolites were identified, and complete assignments of 1H and 13C resonances including many complex coupled spin systems were obtained. 相似文献
4.
GuiBinMA JuliusGLASER 《中国化学快报》2002,13(7):695-698
A novel complex of monomeric thallium (Ⅲ) with the nitrogen donor ligand phenanthroline (phen) has been prepared and characterized by multimuclear NMR(^1H,^13C,^205Tl). The three complexes exist in equilibria in DMSO and acetonitrile solution, which was proved by the ^205Tl NMR spectra. The ^1H and ^13C NMR spectra of tris-phen T1(Ⅲ) complex have been measured, where the spin-spin coupling between T1(I=1/2) and ^13C or ^1H signals were observed with the ^1H and ^13C NMR spectroscopy in acetonitrile. The coupling constants are presented and the chemical shifts of complexes are discussed in detail. 相似文献
5.
In this paper, the effects of temperature from 60 °C to 80 °C and the molar ratios in monomer feed on the copolymerization of α-methylstyrene(AMS) and styrene(St) were studied. The resulting copolymers, designated as PAS, were characterized by FTIR, GPC, NMR and TGA. When the reaction temperature was below 75 °C, the molecular weights increased almost linearly as the evolution of the copolymerization. The phenomenon revealed that AMS could mediate the conventional free radical polymerization having some features of a controlled system. As the AMS/St = 50/50(molar) in feed, the overall fraction of the AMS unit incorporated into the copolymer was as high as 42 mol%, the monomer conversion could be more than 90 wt% and the molecular weights could reach as high as 4400. However, since the styrene is more reactive than AMS, the AMS fraction in copolymer increased with the overall monomer conversion. The 13C-NMR revealed the products were random copolymers which had triads, such as-AMS-AMS-AMS-,-St-AMS-AMS-(-AMS-AMS-St-) and-St-AMS-St-. TGA curves demonstrated that the degradation temperature of the resulting copolymers went down from about 356.9 °C(0 mol% AMS) to 250.2 °C(42 mol% AMS). This behavior demonstrated that there exist weak bonds in the AMScontaining sequences which could be used as potential free radical generators. 相似文献
6.
Ali K.Khalafallah Suleiman A.Suleiman Afifi H.Yousef Nadia A.A.El-kanzi Abou El-Hamd H.Mohamed 《中国化学快报》2009,20(12):1465-1468
In continuation of our chemical investigation on some medicinal plants of the genus Tephrosia,re-investigation of the methylenechloride/methanol(1:1) extract of the air-dried aerial part of Tephrosia apollinea afforded a new prenylated flavonoid 1, in addition to an aromatic ester,a sesquiterpene,a lignan and several known prenylated flavonoids.The structures were established by(~1H NMR,~(13)C NMR,DEPT,~1H-~1H COSY,HMQC,HMBC,NOESY and HRMS).Relative configurations of 9 and 10 were confirmed by X-ray anal... 相似文献
7.
A sensitivity-enhanced IPAP NMR experiment was described in this paper,which separates the ^1H-^15N doublets into two different spectra to alleviate the problem of resonance overlaps and achieve the accurate measurement of J and residual dipolar coupling constants in proteins.This experiment offered 20%-60% sensitivity enhancement over the original IPAP experiment,and therefore produced more measurable resonances.Pulsed field gradient was used for coherence selection.Water-flip-back approach was used for water suppression.The sensitivity-enhanced IPAP experiment was employed in the measurement of ^1JNH and ^1DNH constants of the protein UBC9. 相似文献
8.
The title compound (1) was treated with NaH at room temperature in anhydrous DMF to give a sodium salt (containing nitrogen anion)which could shift the methyl group from oxygen to nitrogen atom to form N-methyl phosphinic acid as the reaction temperature was increased to 120 ℃.Three nitro derivatives containing 5,10-dihydrophenophosphazine ring system were prepared for the investigation on the above reaction mechanism which would be possible regarded as a special inter-molecular substitution.viz.,the nucleophilic nitrogen anion from one molecule of 1 attacked the cabon atom of the O-methyl of another 1.In addition,the chemical structures of seven compounds containing 5,10-dihydrophenophosphazine ring system involved in the experiment were confirmed by IR,^1 H NMR,^31P NMR and mass spectroscopy. 相似文献
9.
Zhi Yong Wei~ 《中国化学快报》2008,19(3):363-366
Copolymerizations of L-lactide (L-LA) and ε-caprolactone (ε-CL) were conducted in bulk using magnesium octoate as a catalyst. The reactivity ratios of L-LA and ε-CL were determined to be rL=23 and rc=0.22, respectively. The sequence analyses of the copolymers were performed on ^13C NMR. An increase in the reaction temperature enhances the role of transesterification and the extent of randomness. 相似文献
10.
Yu Rongmin Li Xian Zhu Tingru Yoshihiro Harigaya Yaeko Konda Masayuki Onda 《高等学校化学研究》1990,6(3):249-253
The Oxytropis, legume genus, is native in the northwest of China, and some of its members have been reported to be toxic to grazing livestock. In the course of studying toxic reason of this legume, a toxic alkaloid was isolated from Oxytropis glabra D C. grown in the Inner Mongolian Autonomous Region. The LD+(50) of (—)-thermopsine(Ⅰ) was shown to be 89.98 mg/kg(in mice). This paper reports an approach to the structure elucidation of(-)-thermopsine by combining 2D NMR[~1H-~1H and ~1H-~(13)C (one-bond and long-range) COSY] and other physicochemical methods. The stereochemistry of compound Ⅰ is also discussed. 相似文献
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牛尾蒿中—新倍半萜结构的确定李瑜,杨立,师彦平(兰州大学应用有机化学国家重点实验室,兰州,730000)关键词牛尾蒿,倍半萜,牛尾蒿酮牛尾蒿(ArtemisiaSubdigitata)是菊科蒿属的一种多年生草本植物,广布于华北、东北、西北和西南等地区... 相似文献
14.
Two novel and two known steroids were isolated respectively from benzene: acetone and ethanolic extracts of the seeds of C. anthelminticum and, identified as (24alpha/R)-Stigmasta-7-en-3-one (1), (24alpha/R)-Stigmasta-7, 9(11)-dien-3-one (2), (24alpha/S)-Stigmasta-5, 22-dien-3beta-ol (3) and (24alpha/S)-Stigmasta-7, 22-dien-3beta-ol (4). The structures were assigned on the basis of their IR, 1H NMR, 13C NMR (DEPT), 2D NMR (1H-1H COSY and 1H-13C COSY), mass spectra, chemical analyses and on comparison with literature values. The novel steroids (1) and (2) were also tested against several human pathogenic bacteria and fungi. 相似文献
15.
da Silva Júnior EN de Souza MC Pinto AV Pinto Mdo C Nogueira CM Ferreira VF Azeredo RB 《Magnetic resonance in chemistry : MRC》2008,46(12):1158-1162
Six new nor-beta-lapachones have been synthesized from reaction of 3-bromo-nor-beta-lapachone with arylamines. These derivatives have potent anticancer properties against several cell lines. Here, we report complete unambiguous assignments of (1)H and (13)C chemical shifts of the new compounds. The assignments were made using a combination of one- and two-dimensional NMR techniques ((1)H, (13)C, (1)H-(1)H COSY, (1)H-(13)C HSQC, and (1)H-(13)C HMBC). 相似文献
16.
采用一维(1D)和二维(2D)核磁共振(NMR)技术对一种抗癫痫活性的化合物1-(2,6-二氟苯甲基)-N-甲基-1H-1,2,3-三唑-4甲酰胺的1H和13C NMR信号进行了归属。 相似文献
17.
Two novel unsaturated E-ring pentacyclic triterpenoid saponins, ilexhainanoside A and ilexhainanoside B, were isolated from the leaves of Ilex hainanensis. 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 (HSQC, HMBC, ROESY and 1H-1H COSY). 相似文献
18.
Ilexpernoside A and ilexpernoside B, two new pentacyclic C(4)-nortriterpenoid saponins, were isolated from the leaves of Ilex pernyi Franch. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the (1)H and (13)C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, (1)H-(1)H COSY and NOESY). 相似文献
19.
Ten phenylpiperazine derivatives were designed and synthesized. The first complete assignments of (1)H and (13)C NMR chemical shifts for these phenylpiperazine derivatives were achieved by means of 1D and 2D NMR techniques, including (1)H-(1)H COSY, HSQC and HMBC spectra. 相似文献