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1.
The isolation and identification of eighteen components from the leaves of Schefflera taiwaniana are presented. Their structures were determined on the basis of spectral data as well as direct comparison with authentic samples. These compounds include two polyacetylenes, one carotenoid‐like, three sesquiterpenes, one diterpene, four triterpenes, two tocopherols, and five alkyl 4‐hydroxycinnamate mixtures. Among these, 4‐hydroxy‐trans‐cinnamic acid docosyl ester and 4‐hydroxy‐cis‐cinnamic acid tetracosyl ester are new compounds. Some of these components exhibit cytotoxic activity. 相似文献
2.
The isolation and identification of twenty-two components from the heartwood of Bauhinia purpurea are described. Their structures were determined on the basis of spectral evidence as well as direct comparison with authentic samples. Those components included six steroids, two triterpenoids, three fatty alcohol, acid and ester, two glycerols, five flavonoids, two phenols, one chromone, and one sugar. Among these, 6′-(β-sitosteryl-3-O-β-glucopyranosidyl)tetraeicosanoate is a new compound. 相似文献
3.
《Journal of heterocyclic chemistry》2017,54(1):531-538
The intermolecular cyclization reactions of N‐tosyl‐ethylenediamine with glyoxal promoted by transition metal acetate at different ratios gave three N‐heterocyclic compounds. The ligand in compound 1 contains one N‐heterocycle, which is formed by a one‐pot three‐component reaction. In compound 2 , two imidazolidine rings and one piperazine ring are fused together to form a tricyclic skeleton by a one‐pot five‐component reaction. Two 1,3,6‐triazabicyclo[3.3.0]octanes are connected by one C–C bond to form the skeleton of 3 , which is constructed from a one‐pot nine‐component reaction. It revealed that the key factor for the preparation of these compounds is the ratio of starting materials, as well as the presence of corresponding transition metal acetates. 相似文献
4.
I. V. Guchik Yu. L. Frolov V. A. Shagun A. V. Vashchenko B. A. Trofimov 《Journal of Structural Chemistry》2004,45(1):41-46
Coordination of dimethylsulfoxide molecules to the sodium and potassium cations was investigated by HF/6-31G(d)//HF/6-31G(d) and DFT(B3LYP/6-31G(d)) quantum-chemical methods. The coordination numbers of Na+ and K+ are found to be five and six, respectively. Thermal effects of complexation were calculated for each stage of the process; these were found to be 197.8, 160.1, 106.9, 88.0, 53.9 [HF/6-31G(d)] and 195.0, 158.5, 108.9, 95.7, 60.0 kJ/mole [B3LYP/6-31G(d)] for Na+ (one to five DMSO molecules, respectively); 146.6, 118.7, 90.2, 68.9, 70.0, 49.0 [HF/6-31G(d)] and 144.0, 117.4, 91.7, 78.9, 78.6, 56.4 kJ/mole [B3LYP/6-31G(d)] for K+ (one to six DMSO molecules, respectively). Structural parameters and charge distributions are given for the complexes. It is shown that solvation of sodium and potassium cations by DMSO molecules is preferable to solvation by water molecules. 相似文献
5.
Philipp Kramer Jennifer Grimmer Michael Bolte Georg Manolikakes 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13190-13193
A novel method for the highly stereoselective synthesis of tetrahydropyrans is reported. This domino reaction is based on a twofold addition of enamides to aldehydes followed by a subsequent cyclization and furnishes fully substituted tetrahydropyrans in high yields. Three new σ‐bonds and five continuous stereogenic centers are formed in this one‐pot process with a remarkable degree of diastereoselectivity. In most cases, the formation of only one out of 16 possible diastereomers is observed. Two different stereoisomers can be accessed in a controlled fashion starting either from an E‐ or a Z‐configured enamide. 相似文献
6.
Synthesis and mesomorphic behavior of nine members of each of the two classes of 6-phenyl- and 2-phenyltetralins and five members of the 2-trans-cyclohexyltetralins are reported. The synthesis of one member of each class is described in detail. Besides the target compounds, more than twenty intermediates showed liquid crystalline properties; their transition temperatures are recorded (see Tables 1-6). 相似文献
7.
Continuous investigation of the CHCl3‐soluble and n‐hexane fractions of the leaves of Litsea acutivena Hayata (Lauraceae) led to the isolation of one new butanolide, acutilactone ( 1 ), one new lactone, 4‐nonacosyl‐dihydrofuran‐2‐one ( 2 ), together with 15 known compounds. The known compounds included one butanolide, one norisoprenoid, one quinone, two steroids, one triterpenoid, one coumarin, two fatty acids, one amide, and five other compounds. The structures of these compounds were determined by means of spectral analyses. 相似文献
8.
《Journal of heterocyclic chemistry》2017,54(1):484-488
A versatile pathway for the synthesis of novel bis(quinazolinon‐4(1H )‐one) derivatives by one‐pot pseudo five‐component condensation of two molecules isatoic anhydrides, two molecules orthoesters, and diamines in high yields and short reaction time is described. The work‐up is easy, and the products are obtained in good‐to‐excellent yields and high purity. 相似文献
9.
Chun‐Li Cao Dr. You‐Yun Zhou Jian Zhou Dr. Xiu‐Li Sun Dr. Yong Tang Prof. Dr. Yu‐Xue Li Dr. Guang‐Yu Li Dr. Jie Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(42):11384-11389
Cyclic ketones react with (E)‐2‐nitroallylic acetates in the presence of catalytic pyrrolidine‐thiourea, which affords bicyclic skeletons with four or five stereocenters in one single reaction with up to 98 % ee in moderate to high yields. The cooperative effects of both enamine and the Brønsted acid are found to be crucial for the high reactivity and enantioselectivity of this cascade reaction, which is demonstrated by both theoretical calculation and experimental data. 相似文献
10.
Renato Galli Markus Dobler Rolf Güller Reto Stahl Hans‐Jürg Borschberg 《Helvetica chimica acta》2002,85(10):3400-3413
Two independent total syntheses of the Aristotelia alkaloid (−)‐serratenone ((−)‐ 1 ) are disclosed, one starting with (−)‐α‐pinene, the other one with (S)‐α‐terpineol. These correlations led to a revision of the originally proposed absolute configuration of the natural product. In the course of systematic investigations of the behavior of the indole alkaloids (+)‐makomakine ((+)‐ 18 ) and (−)‐hobartine ((−)‐ 22 ) towards oxidizing reagents, it was found that treatment with I2 leads to no less than five different products. Depending on the exact reaction conditions, each of them can be obtained as the major component in yields between 40 and 60%. One of these compounds was shown to be identical with the natural product (+)‐11,12‐didehydromakonin‐10‐one ((+)‐ 28 ). 相似文献
11.
Doyle Britton WaylandE. Noland MatthewJ. Pinnow VictorG. YoungJr. 《Helvetica chimica acta》2003,86(4):1175-1192
The crystal structures of five 5,6‐disubstituted benzofurazan 1‐oxides are presented and compared with five previously reported structures: three polymorphs of 5,6‐dichlorobenzofurazan 1‐oxide plus 4,5‐dichloro‐ and 4,5‐dibromophthalic anhydride. All but one of these compounds pack with similar two‐dimensional layers. The benzofurazan oxides all show disorder about a crystallographic twofold or pseudo‐twofold axis. In addition, six complexes of phthalic anhydride and benzofurazan oxides are reported. With the packing in the complexes principally directed by the π complexing, the disorder, invariably found in the uncomplexed benzofurazan oxides, is diminished, and, in two cases, eliminated. 相似文献
12.
Hua Gong Huitong Zhou Jeffrey E. Plowman Jolon M. Dyer Jon G. H. Hickford 《Electrophoresis》2010,31(21):3545-3547
Keratin‐associated proteins (KAPs) are one of the main structural components of the wool fibre. Variation in the KAP genes (KRTAPs) may affect the structure of KAPs and hence wool characteristics. In this study, we used PCR‐SSCP to analyse ovine KRTAP5‐4, a gene encoding a member of the KAP5 family. Five different PCR‐SSCP patterns were detected in the 250 sheep that were analysed. Either one or a combination of two patterns was observed for each sheep, which was consistent with these sheep being either homozygous or heterozygous at this locus. DNA sequencing revealed that these patterns represent five different DNA sequences. One of the sequences was identical to a published ovine KRTAP5‐4 sequence. The remaining four were unique, but shared a high homology with the published ovine KRTAP5‐4 sequence, suggesting that these sequences represent allelic variants of KRTAP5‐4. There were a total of six SNPs and one length polymorphism in the sequences. Of the five SNPs found in the coding region, four were non‐synonymous SNPs and would result in amino acid changes. The length polymorphism would affect the cysteine content of the putative peptide and this along with the SNPs may have an impact on the structure of KAP5‐4, and hence affect wool traits. 相似文献
13.
An efficient cascade process five‐component reaction of isatins and 3‐oxo‐N‐arylbutanamide for the synthesis of 4,4′‐((2‐oxoindoline‐3,3‐diyl)bis(methylene))bis(2‐aryl‐1H‐pyrrolo[3,4‐c]quinoline‐1,3(2H)‐dione) derivatives was reported under mild condition. The advantages of this strategy are easy to obtain raw materials, convenient one‐pot procedure, and simple operation. 相似文献
14.
A. Abdul Ajees S. Parthasarathy S. Manikandan R. Raghunathan 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):473-475
The title compound, C23H15Cl2NO3, crystallizes with two independent molecules in the asymmetric unit. The chromanone moiety consists of a benzene ring fused with a six‐membered heterocyclic ring which adopts a sofa conformation. The five‐membered spiroisoxazoline ring is in an envelope conformation. The p‐chlorophenyl rings bridged by the five‐membered ring are nearly perpendicular to each other. The chromanone moiety of one molecule packs into the cavity formed by the p‐chlorophenyl rings of a second molecule through the formation of C—H?π interactions. The structure is stabilized by weak C—H?O, C—H?Cl and C—H?π interactions. 相似文献
15.
Zhongxing Huang Chengpeng Wang Prof. Dr. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2016,55(17):5299-5303
Described is a new hydrazone‐based exo‐directing group (DG) strategy developed for the functionalization of unactivated primary β C?H bonds of aliphatic amines. Conveniently synthesized from protected primary amines, the hydrazone DGs are shown to site‐selectively promote the β‐acetoxylation and tosyloxylation via five‐membered exo‐palladacycles. Amines with a wide scope of skeletons and functional groups are tolerated. Moreover, the hydrazone DG can be readily removed, and a one‐pot C?H acetoxylation/DG removal protocol was also discovered. 相似文献
16.
Ruta Bariseviciute Justinas Ceponkus Alytis Gruodis Valdas Sablinskas 《Central European Journal of Chemistry》2006,4(4):578-591
Ozonization reaction of simple alkenes was studied by means of FT infrared absorption gas spectroscopy. The reaction was performed
at 95 K in neat films of the reactants. IR absorption spectra of the gaseous products were recorded. The spectra were analyzed
combining experimental results with theoretical calculations performed at B3LYP 6-311++G (3df, 3pd) level. We found that among
all theoretically predicted conformers of propene secondary ozonide, only one which has the O-O half-chair configuration for
the five membered ring and the radical attached in the equatorial position was present in the sample. Samples of 1-butene and 1-heptene secondary ozonides consist from two conformers of very
similar energy (ΔH=0.3 kJ/mol). The most stable conformer for both ozonides is the one with O-O half-chair configuration of the five membered
ring and the radical attached in equatorial position and the aliphatic chain in gauche position. The second stable conformer has the aliphatic chain in anti position. 相似文献
17.
A PDMS/poly(vinylalcohol) (PDMS/PVA) film prepared through a sol–gel process was coated on stir bars for sorptive extraction, followed by liquid desorption and large volume injection–GC–flame photometric detector (LVI–GC–FPD) for the determination of five organophosphorus pesticides (OPPs) (phorate, fenitrothion, malathion, parathion, and quinalphos) in honey. The preparation reproducibility of PDMS/PVA‐coated stir bar ranged from 4.3 to 13.4% (n = 4) in one batch, and from 6.0 to 12.6% (n = 4) in batch to batch. And one prepared stir bar can be used for more than 50 times without apparent coating loss. The significant parameters affecting stir bar sorptive extraction (SBSE) were investigated and optimized. The LODs for five OPPs ranged from 0.013 (parathion) to 0.081 μg/L (phorate) with the RSDs ranging from 5.3 to 14.2% (c = 1 μg/L, n = 6). The proposed method was successfully applied to the analysis of five OPPs in honey. 相似文献
18.
Instabilities of the restricted Hartree–Fock (HF ) state of the two-dimensional extended Hubbard model under doping are studied with the linear response theory employing the linearized Bethe–Salpeter equation. Boundaries of the instabilities for the ordering vectors q = Q ≡ (π, π) and q = Q0 ≡ (0, 0) are given in terms of the interaction strength parameters at various doping levels. With doping, dominant instabilities generally change from ones for q = Q to ones for q = Q0. Broken symmetry phases obtained from the instabilities are also studied and classified using the group-theoretical technique. For q = Q, two more new phases are obtained in addition to the four nonmagnetic and five magnetic phases that have been already derived by one of the authors. For q = Q0, three nonmagnetic and five magnetic phases are obtained. Deriving the explicit forms of the charge current and spin current operators in the HF approximation, charge current and spin current densities in the broken symmetry states are discussed in detail. © 1992 John Wiley & Sons, Inc. 相似文献
19.
This study developed a robust and reliable approach using liquid chromatography– tandem mass spectrometry for the simultaneous determination of five saponins in rat tissues: β‐ecdysterone, chikusetsusaponin IV, ginsenoside Ro, 25S‐inokosterone and chikusetsusaponin IVa. This is the first report on a comparative tissue distribution study of crude and salt‐processed Radix Achyranthes in rats. After one‐step protein precipitation by acetonitrile, the tissue samples were sent to LC–MS/MS for multiple reaction monitoring. The retention times of the five saponins and internal standard were 1.77, 3.14, 3.01, 1.83, 3.26 and 4.77 min. The standard curves showed good linear regression (r2 > 0.9991) in the range of 10.3–1562.5 ng/mL. The intra‐ and inter‐day accuracy and precision were within 15% of the nominal concentration. The recoveries of the five saponins were 92.0–99.9%. Finally, this approach was successfully applied to tissue distribution analysis of the five saponins after oral administration of crude and salt‐processed Radix Achyranthes in rats. The largest concentration of the five saponins was observed in kidney after salt‐processing, which indicated that processing could enhance the bioavailability. 相似文献
20.
M.Iqbal Choudhary SyedGhulam Musharraf MahmudTareqHassan Khan Doaa Abdelrahman Massod Parvez Farzana Shaheen Atta‐ur‐Rahman 《Helvetica chimica acta》2003,86(10):3450-3460
The microbial transformation of (+)‐isolongifolen‐4‐one ( 4 ) by a number of fungi by means of a standard two‐stage fermentation technique afforded (7R)‐12‐hydroxyisolongifolen‐4‐one ( 5 ), (7S)‐13‐hydroxyisolongifolen‐4‐one ( 6 ), (11R)‐11‐hydroxyisolongifolen‐4‐one ( 7 ), (10R)‐10‐hydroxyisolongifolen‐4‐one ( 8 ), and (9R)‐9‐hydroxyisolongifolen‐4‐one ( 9 ) (Scheme). All five metabolites were found to be new, and metabolites 6 and 9 showed potent tyrosinase inhibitory activity (Table 1). The metabolites and their derivatives were characterized on the basis of spectroscopic and single‐crystal X‐ray‐diffraction techniques. 相似文献