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1.
Phytochemical investigation of Symplocos racemosa resulted in the isolation of two new glycosides, symploracemoside ( 1 ) and symplomoside ( 2 ), which are structurally related to the reported benzoylsalireposide ( 3 ) and salireposide ( 4 ). The structure elucidation of the isolated compounds was based primarily on 1D‐ and 2D‐NMR analysis, including COSY, NOESY, HMQC, and HMBC correlations. These glycosides showed inhibitory activity against snake‐venom phosphodiesterase I.  相似文献   

2.
A lignan and two acylphloroglucinols have been isolated from the ethyl acetate soluble fraction of the whole plant of Indigofera hetrantha. Their structures have been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. Compounds 1-3 displayed promising inhibitory potential against enzyme lipoxygenase in concentration-dependent manner.  相似文献   

3.
Three new anthraquinone secondary metabolites were isolated from Symplocos racemosa, a small tree of family symplocaceae. The structures of compounds (13) were elucidated to be 1,4-dihydroxy-6-(ethoxymethyl)-8-propylanthracene-9,10-dione (1), 1,4-dihydroxy-6-(hydroxymethyl)-8-butylanthracene-9,10-dione (2) and 1,4-dihydroxy-6-(hydroxymethyl)-8-propyl anthracene-9,10-dione (3) using their spectral data, i.e. through IR, UV, 1H NMR, 13C NMR and two-dimensional (2D) NMR techniques including heteronuclear multiple quantum coherence, heteronuclear multiple bond correlation and correlation spectroscopy.  相似文献   

4.
A new flavonol glycoside (1) has been isolated from the ethyl acetate soluble fraction of Amberboa ramosa and assigned the structure 5,7,4'-trihydroxy-3,8-dimethoxylflavone 5-O-beta-D-gluco-pyranoside (1). In addition, 6,4'-dihydroxy-3,5,7-trimethoxyflavone (2), 5,7-dihydroxy-4'-methoxyflavone (3) and (23R)-5alpha-cycloart-24-ene-3beta,21,23-triol (4) have also been reported for the first time from this species. The structures were deduced on the basis of 1D and 2D NMR techniques. The compounds 1-3 displayed weak to moderate inhibition against the xanthine oxidase enzyme.  相似文献   

5.
A new dihydrochalcone glucoside, vacciniifolin, along with confusoside, trilobatin and sieboldin were isolated from the leaves of Symplocos vacciniifolia. By the method of spectral analysis, this new compound was elucidated as 2‘,3,4,4‘-tetrahydroxydihydrochalcone 4‘-O-β-D-glu-copyranoside.  相似文献   

6.
Phytochemical investigation is very valuable for the ethnomedicinally important plants Bauhinia racemosa Lam (BR) and Cordia dichotoma Linn (CD) used for the cure of variety of ailments. This study was thus designed for phytochemical investigation of BR bark and CD leaves. Phytoconstituents were isolated from the methanolic extracts of the plants by column chromatography using silica gel as stationary phase. The structures had been established on the basis of their physicochemical and spectral data, i.e. IR, 1H NMR, 13C NMR and MS. Elution of the columns with different solvents furnished six compounds (16) from the methanolic extract of BR bark and three compounds (79) from the methanolic extract of CD leaves which were structurally elucidated. The present phytochemical investigation reported several new compounds useful in increasing the existing knowledge of phytoconstituents from BR bark and CD leaves which is very valuable, as these drugs are used in the Indian traditional systems of medicine.  相似文献   

7.
Rate constants for the reaction of ethyl bromoacetate with three series of substituted naphthoate ions have been measured in an acetone-water mixture (90% v/v). Using σ p values rate constants at 30o correlate well with the Hammett equation yielding ρ=−0.54, −0.19 and −0.25 for (4,1−), (6,1−) and (6,2−) series, respectively. Comparison of these ρ values with those of the reaction of phenacyl bromide reveals the failure of the reactivity-selectivity principle RSP in these reactions. Failure of RSP has been explained in terms of isoselective temperature.  相似文献   

8.
Two new mesogenic homologous series of liquid crystalline cinnamates with substituted ethyl tails, β-methoxyethyl [4-(4'-n-alkoxycinnamoyloxy)benzoates (I) and β-chloroethyl [4-(4'-n-alkoxycinnamoyloxy)benzoates (II), have been synthesized and characterized by a combination of elemental analysis and standard spectroscopic methods. In series I, lower-chain members exhibit nematic mesophase, middle members exhibit enantiotropic nematic as well as smectic A (SmA) mesophases, whereas higher members exhibit only an enantiotropic SmA mesophase. In series II, methoxy to n-butyloxy derivatives exhibit a monotropic nematic mesophase. The SmA mesophase commences from n-propyloxy derivative as monotropic and persists up to the last member synthesized. The mesomorphic properties of present series were compared with each other and with a structurally related mesogenic homologous series to evaluate the effects of substituted ethyl tail and cinnamoyloxy central linkage on mesomorphism.  相似文献   

9.
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11.
Robert Bujok 《Tetrahedron》2010,66(3):698-708
The addition of mono- and dianions of ethyl N-pivaloyl-3-aminocrotonate to substituted nitroarenes, followed by action of silylating or acylating agent, leads to 3-aminoquinoline carboxylic acid derivatives. Hydrolysis and decarboxylation of the latter, carried out efficiently under relatively mild conditions, afford 3-aminoquinolines diversely substituted in the benzo-fused ring.  相似文献   

12.
Two new mesogenic homologous series of liquid crystalline cinnamates with substituted ethyl tails, β‐methoxyethyl [4‐(4′‐n‐alkoxycinnamoyloxy)benzoates (I) and β‐chloroethyl [4‐(4′‐n‐alkoxycinnamoyloxy)benzoates (II), have been synthesized and characterized by a combination of elemental analysis and standard spectroscopic methods. In series I, lower‐chain members exhibit nematic mesophase, middle members exhibit enantiotropic nematic as well as smectic A (SmA) mesophases, whereas higher members exhibit only an enantiotropic SmA mesophase. In series II, methoxy to n‐butyloxy derivatives exhibit a monotropic nematic mesophase. The SmA mesophase commences from n‐propyloxy derivative as monotropic and persists up to the last member synthesized. The mesomorphic properties of present series were compared with each other and with a structurally related mesogenic homologous series to evaluate the effects of substituted ethyl tail and cinnamoyloxy central linkage on mesomorphism.  相似文献   

13.
Abstract

Using various chromatographic separations, three new acylated flavonoid glycosides, namely barringosides G–I (13), were isolated from the water-soluble extract of Barringtonia racemosa branches and leaves. The structure elucidation was performed by extensive analysis of the 1D and 2D NMR and HR-QTOF-MS data. Of the isolated compounds, barringoside I (3) showed moderate inhibitory effects on LPS-induced NO production in RAW264.7 cells with an IC50 of 52.48?±?1.04?µM.  相似文献   

14.
Three new phenolics, (1S,2R)-1-(4'-O-beta-D-glucopyranosyl-3'-methoxyphenyl)-2-(4'-hydroxy-3'-methoxyphenyl)-1,3-propanediol, symplolignanoside A, and 3,4-dimethoxyphenol beta-D-apiofuranosyl(1-->6)-beta-D-glucopyranoside, along with eight known compounds were isolated from the roots of Symplocos caudata Wall. Their structures were elucidated by spectroscopic and chemical methods.  相似文献   

15.
The reaction of acetylenic esters with ethyl bromopyruvate in the presence of tetramethylthiourea led to highly functionalized thiophenes in excellent yields.  相似文献   

16.
The reaction of acetylenic esters with ethyl bromopyruvate in the presence of tetramethylthiourea led to highly functionalized thiophenes in excellent yields. Correspondence: Issa Yavari, Chemistry Department, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.  相似文献   

17.
18.
The stereospecific synthesis of aryloxy and amino substituted E- and Z-ethyl-3-acrylates is of interest because of their potential in the polymer industry and in medicinal chemistry. During work on a copper-catalyzed cross-coupling reaction of ethyl (E)- and (Z)-3-iodoacrylates with phenols and N-heterocycles, we discovered a very simple (nonmetallic) method for the stereospecific synthesis of aryloxy and amino substituted acrylates. To study this long-standing problem on the stereoselectivity of aryloxy and amino substituted acrylates, a series of O- and N-substituted nucleophiles was allowed to react with ethyl (E)- and (Z)-3-iodoacrylates. Screening of different bases indicated that DABCO (1,4-diazabicyclo[2.2.2]octane) afforded successful conversion of ethyl (E)- and (Z)-3-iodoacrylates into aryloxy and amino substituted ethyl acrylates in a stereospecific manner. Herein are the details of this DABCO-mediated stereospecific synthesis of aryloxy and amino substituted E- or Z-acrylates.  相似文献   

19.
The anions of substituted dihydro ethyl benzoates and quinoline are very good hydrogen donors to radicals in liquid ammonia and DMSO. With 4-substituted dihydro ethyl benzoates the rate of hydrogen transfer decreases and excellent yields of products are obtained by 6-exo ring closure reaction followed by reduction.  相似文献   

20.
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