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1.
《Analytical letters》2012,45(6):447-453
Abstract

The basicity (pKa) of a series of para-substituted N-phenylpiperidines has been measured using ultraviolet absorption spectroscopy. A very good correlation was obtained for substituents of known Hammett constants ([sgrave]?) and this has been used to evaluate previously unreported parameters.  相似文献   

2.
A new cyclic peptide, prepatellamide A (1), along with three known cyclic peptides (2)— (4), was isolated from the ascidianLissoclinum patella. The structure of prepatellamide A was determined from one- and two-dimensional1H and13C NMR spectra. The known cyclic peptides were identified as patellamides A (2), B (3) and C (4).  相似文献   

3.
Decomposition of dispiro(diadamantane-1,2-dioxetane) (1) in acetonitrile solutions of EuIII, GdIII, TbIII, PrIII, and CeIII perchlorates was studied by tile chemiluminescence method. The rate constants of decomposition of1 in complexes of composition1 · LnIII and stability constants of these complexes, as well as activation parameters of the decomposition of1 and thermodynamic parameters of the complexation were determined. A correlation between the thermodynamic parameters of complexation and ionic radii of LnIII was found.Translated fromIzvestiya Nauk. Seriya Khimicheskaya, No. 10, pp. 2479–2483, October, 1996.  相似文献   

4.
A new compound, 2,4,6-trihydroxybenzoic acid 4-O-β-D-allopyranoside (1), together with four known compounds, sucrose (2), fructose (3), ecdysterone (4), and β-sitosterol (5) was isolated from the roots of Neocheiropteris palmatopedata (Baker) Christ. The new compound was identified based on extensive spectroscopic studies including HR-ESI-MS, FAB-MS, 1H NMR, 13C NMR, DEPT, 1H–1H COSY, HSQC, HMBC, and NOESY spectra, and the known compounds were identified by their spectroscopic data analysis, comparison with reports in the literature, and co-chromatography with authentic standards. Compounds 2, 3, and 5 were obtained from the Neocheiropteris genus for the first time, and 4 was originally isolated from the plant.  相似文献   

5.
The novel pyrrole alkaloid alhagifoline A (1) together with the two known analogs pyrrolezanthine (2) and pyrrolezanthine-6-methyl ether (3) were isolated from the aerial part of Alhagi sparsifolia. Their structures were established based on spectral (HR-ESI-MS, 1 H and 13C NMR, 1 H–1 H COSY, HSQC, HMBC) data. Compounds 2 and 3 were isolated from the genus Alhagi for the first time.  相似文献   

6.
Roccellatol, a new (2′R,3′S)-erythrityl-2,6-dihydroxy-4-methylbenzoate was isolated along with nine known compounds from the fruticose lichen, Roccella montagnei Bel. em. D.D. Awasthi. The structure of the new compound was elucidated by detailed spectroscopic analysis (1H, 13C, DEPT and HRMS). The present isolation of roccellatol (10) assumes significance as the esters of p-orcellinic acid are rare in lichens. Interestingly, among the known compounds, (+)-montagnetol (9) was now isolated in very large quantity (4.66%).  相似文献   

7.
A novel naphthoquinone (1) was isolated from the methanol extract of P. zeylanica roots in addition to a known compound plumbagin (2). Their structures were determined by UV, IR, MS, 1H, and 13C NMR spectroscopic analysis, including 2D NMR.  相似文献   

8.
Abstract

Two new compounds, namely arteordoyn A (1) and arteordoyn B (2), together with four known compounds, were isolated from the petroleum ether extract of Artemisia ordosica Krasch. The structures elucidation of 1 and 2 were carried out by 1D-NMR (1H and 13C NMR), 2D-NMR (COSY, HSQC, HMBC and NOESY) and HR-ESI-MS spectral analysis.  相似文献   

9.
Abstract

Two new silyl-substituted silolide dianions (11a, 11b) have been synthesized and characterized spectroscopically. Their 1H, 29Si, and 13C NMR spectra show similarities to the known phenyl- and alkyl-substituted analogues. Reaction with ethyl bromide gave the expected diethylsilol. B3LYP/6-31 + G* geometry optimization revealed equalized CC distances, and also NICS values indicate significant aromaticity.

Figures S1—S5 are available online in Supplemental Materials.  相似文献   

10.
By following a previously reported method,1 the synthesis of r-2-alkoxy-cis-4-cis-5-dimethyl-1,3,2-λ3-dioxaphospholanes ligands (1 and 3) was carried out. The purpose of this work is the kinetic study of the inversion barrier at phosphorus for 1 and 3 and the comparison with the already informed dioxaphospholane 2. The kinetic measurements of the thermal isomerization cis-to-trans were performed by 31P NMR spectroscopy, observing a first order kinetics for both compounds. The energy of activation (Ea) for the epimerization of compounds cis-1 and cis-3 was calculated to be 16.0 ± 0.6 and 11.8 ± 0.8 kcal/mol, respectively. The values of the thermodynamic parameters of the transition state (Δ H, Δ S, Δ G) suggest that the inversion at phosphorus not only depends on the spatial requirements of the alkoxy substituent but also on entropic effects. The thermodynamic parameters Δ H°, Δ S°, and Δ G° were also evaluated and they show that the cis isomers are preferred from enthalpic point of view, but entropic effects dominate the equilibrium trans ? cis leading to the entropically favored trans isomers. Furthermore, the results are supported by density functional theory calculations of 14 at the B3LYP/6-31G** level.  相似文献   

11.
Abstract

A wide series of low-coordinated phosphorus (III) compounds including iminophosphines 1, two- 2 or mono-coordinated 3 phosphorus-containing cations, and anion 4, where Mes? = 2,4,6-tris-(tert-butyl)phenyl, has been investigated by 13C, 15N and 31P NMR spectroscopy. The spectral parameters obtained are considered in connection with the ab initio (6–31G?) calculation data of the model compounds.  相似文献   

12.
Abstract

A new tocotrienol, 5-hydroxy-8-methyltocotrienol (1) was isolated from the roots and branches of A. cobbe (L.) Raeusch, together with seventeen known compounds (218). Their structures were elucidated by analysis of spectroscopic data and by comparison of 1H and 13C NMR data with previous literature reports. This is the first phytochemical investigation of the roots and branches of Allophylus cobbe (L.) Raeusch.  相似文献   

13.
A new lactam alkaloid named oleraciamide D (1), indentified as (5R)-4-(3-methoxy-4-hydroxyphenyl)-5-(4-hydroxyphenyl)-5,6-dihydropyridin-2(1H)-one, together with five known compounds, indole-3-aldehyde (2), portulacatone (3), N-trans-feruloyloctopamine (4), N-trans-feruloyl-3′-O-methyldopamine (5) and N-trans-feruloyltyramine (6) were isolated from Potulaca oleracea L. Among them, indole-3-aldehyde (2) was isolated from the medicine for the first time. The structure of the new alkaloid was elucidated via UHPLC-ESI-Q-TOF/MS, 1D NMR and 2D NMR. The five known compounds were established by comparing the 1H-NMR and 13C NMR with the reported literature. Oleraciamide D (1) showed cytotoxicity against SH-SY5Y cells when concentration at 50 uM by CCK-8 method.  相似文献   

14.
A new cadinane sesquiterpenoid glucoside, 2β,7,3-trihydroxycalamenene 3-O-β-d-glucoside (1) together with six known compounds, N-(p-trans-coumaroyl)-N-methyl tyramine (2), Cleomiscosin A (3), 9,12,13-trihydroxy-10,15-heptadecadienoic acid (4), Cytochalasin B (5), Marmesinin (6) and N-(p-trans-coumaroyl) tyramine (7) were obtained from the stem bark of Abelmoschus sagittifolius. The new structure of compound 1 was elucidated by analysing its 1H and 13C-NMR, 1H-1H COSY, HSQC, HMBC, NOESY and HR-ESI-MS spectra. Compounds 1–7 showed moderate cytotoxicity against Hela and HepG-2 human cancer cell lines.  相似文献   

15.
《合成通讯》2013,43(19):3011-3019
The synthesis of the parent oxabridged laticyclic diene, COC-[3]isopolynorbornadiene 5 and the bis(oxabridged) laticyclic diene, CO2C-[4]isopolynorbornadiene 7 have each been achieved in two steps from known starting materials; the hexachloro-derivatives of 5 and 7 are also reported.  相似文献   

16.
通过对采自湛江红树林植物木榄(Bruguiera gymnorrhiza)中化学成分的系统研究, 从中分离得到5个聚二硫化合物. 经现代波谱学分析(IR, 1H NMR, 13C NMR, 2D NMR, MS等), 鉴定其中1个化合物是结构新颖的多聚二硫大环化合物, 命名为木榄八硫醇(neogymnorrhizol, 1), 该化合物是由4个重复的2-羟基-1,3-丙二硫醇基聚合而成的二十元大环分子; 此外还分离得到了4个已知聚二硫化合物, 它们分别为木榄六硫醇(gymnorrhizol, 2a)、新木榄二硫醇(bruguiesulfurol, 3)、木榄二硫醇(brugierol, 4)和异木榄二硫醇(isobrugierol, 5). 其中化合物3的立体化学结构经过X单晶衍射并与文献对照得以确定, 在此基础上重新对化合物45的核磁共振信息进行全归属; 同时修订了文献中对化合物4立体化学结构的表述. 探讨了聚二硫化合物可能的生物合成途径, 分析了化合物15可能的相互间的生源关系; 经体外生物活性测试研究发现, 化合物2a3均对II型糖尿病靶标分子人蛋白酪氨酸磷酸酯酶(hPTP1B)具有显著的抑制活性.  相似文献   

17.
A new sesquiterpenoid quinone, Acyl hibiscone B (1), together with five known compounds, (R)-lasiodiplodin (2), (R)-de-O-methyllasiodiplodin, (3) dibutyl phthalate (4), (R)-9-phenylnonan-2-ol (5) and hibiscone B (6), was obtained from the stem tuber of Abelmoschus sagittifolius. The structure of compound 1 was elucidated by analysing its 1H and 13C NMR, 1H–1H COSY, HSQC, HMBC, NOESY and HR-ESI-MS values. Compound 1 showed significant cytotoxicity against Hela and HepG-2 human cancer cell lines.  相似文献   

18.
Abstract

Sinigrin (1), the most commonly known glucosinolate, is a naturally occurring thiosugar, widely distributed in the botanic family Cruciferae. Sinigrin was first isolated in 1839 from seeds of black mustard in the form of its potassium salt.1 Commercially available sinigrin is obtained by extraction from horseradish.2 So far a number of natural glucosinolates and their analogs have been synthesized.3-10 The only synthesis of compound 1, leading to a crystalline product on the miligram scale, has been reported by Benn and Ettlinger3 (Scheme 1). Their procedure has been applied by Kjaer and Jensen4 for the synthesis of the higher homologue of sinigrin (1), but no information of the overall yield has been provided.  相似文献   

19.
Chemical investigation of the cultures of a sponge-derived fungus Simplicillium sp. YZ-11 led to the isolation of a new minor diketopiperazine alkaloid cyclo-(2-hydroxy-Pro-Gly) (1) and a natural lactone (S)-dihydro-5-[(S)- hydroxyphenylmethyl]-2(3H)-furanone (2), together with five known ergostane-type sterols (37). Their structures were established based on extensive spectroscopic methods (1H and 13C NMR, 1H-1H COSY, HSQC and HMBC) and optical rotation analysis.  相似文献   

20.
Abstract

As members of the family of low-coordinated phosphorus compounds, the phosphinidenes (RP) containing subvalent phosphorus (σ11-P) are of current interest. Until now, no Organophosphiaidene RP (R=Alkyl, Aryl) is known to be stable in the condensed phase. As the results of trapping experiments are questioned, the formation of RP as intermediates is still doubtful [1]. The mass spectrometric decay of some organophosphorus compounds yields radical cations [C6,H5,P]+? m/z 108. For these species structures 1 and 2 are conceivable:  相似文献   

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