共查询到20条相似文献,搜索用时 15 毫秒
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V. V. Sova M. B. Filitova T. N. Makar'eva L. A. Elyakova 《Chemistry of Natural Compounds》1992,28(3-4):275-279
The capacity of certain extracts of marine invertebrates of the Indian and Pacific Oceans for activating -1,3-glucanases has been detected. It has been shown that an individual compound — swinholide A from the spongeTheonella swinhoei — specifically activates -1,3-glucanases of bivlve mollusks. In the presence of swinholide A both the hydrolysis of laminarin by -1,3-glucanase L-IV fromSpisula sachalinensis and the transglycosylation reaction are accelerated.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 316–320, May–August, 1992. 相似文献
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Xiaoyu Chen Pengyu He Siqi Xia Lixin Cui Prof. Dr. Guofu Zhong Prof. Dr. Limin Yang 《Chemical record (New York, N.Y.)》2023,23(7):e202200279
Over the recent decades, due to the special electronic characteristics and diverse reactivities, N-heterocyclic carbene (NHC) has received significant interest in organocatalyzed reactions. The formation of Breslow intermediates by NHC can convert into acyl anion equivalent, enolates, homoenolate, acyl azolium, and vinyl enolate etc., and the cycloaddition reactions of these species has attracted lots of attention. In this review, we focus on the summry of the development of NHC-activation of carbonyl carbon (or imine carbon) in situ, α-, β-, γ-, and beyond, and the cycloaddition reaction of these species. 相似文献
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Synthesis and conformational studies of α-, β-, γ-hybrid peptides containing a pyrrole amino acid (Paa, 1) and a furan amino acid (Faa, 2), namely Boc-β-Phe-Faa-d-Pro-Gly-Paa-β-HGly-Faa-OMe (3) and Boc-Paa-β-Phe-Faa-d-Pro-Gly-Paa-β-HGly-Faa-OMe (4), were carried out and they adopt β-hairpin structures stabilized via inter-strand π-π and hydrogen bonding interactions. 相似文献
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Gerd-Volker Röschenthaler Irene B. Kulik Vadim A. Soloshonok 《Journal of fluorine chemistry》2011,132(10):834-542
Addition of both alkyl phosphites and phosphonate α-carbanions to N-substituted aldimines derived from fluoroalkyl aldehydes presents a convenient method for synthesis of fluoroalkyl α- and β-aminophosphonates in good yield (55-86%) under mild conditions. 相似文献
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A. V. Ruseikina L. A. Solov’ev O. V. Andreev 《Russian Journal of Inorganic Chemistry》2013,58(10):1231-1236
The crystal structure of the EuPrCuS3 complex sulfide synthesized for the first time has been solved by X-ray powder diffraction. Crystals are orthorhombic, space group Pnma. EuPrCuS3 has two polymorphs: the high-temperature phase of Ba2MnS3 structural type with unit cell parameters a = 8.0786(1) Å, b = 4.0288(1) Å, and c = 15.8389(2) Å and the low-temperature phase of BaLaCuS3-isostructural with unit cell parameters a = 11.0819(2) Å, b = 4.0710(1) Å, and c = 11.4459(3) Å. 相似文献
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Dr. Diego Díaz Bautista Dr. Miguel A. Vilchis Reyes Dr. Ever A. Blé González Prof. Dr. Alejandro Bugarin 《European journal of organic chemistry》2023,26(35):e202300404
Lycorane is a pentacyclic core presented in alkaloids isolated from the Amaryllidaceae family of herbaceous flowering plants. Members of this class of natural products have shown to display important biological properties including analgesic, antiviral, and antiproliferative activities. This review presents the known synthetic routes toward α-, β-, γ-, and δ-lycoranes. α-(19 routes), β-(10 routes), γ-(38 routes), and δ-(6 routes). 相似文献
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Kazimierz Chmurski Antony W. Coleman Janusz Jurczak 《Journal of carbohydrate chemistry》2013,32(7):787-796
ABSTRACT The clean one step synthesis of the amphiphilic α-, β-, and γ-cyclodextrins starting from per-(6-bromo-6-deoxy)-α-, -β-, and -γ-cyclodextrins is described. The role of the lipophilic tail is played by various aryl groups (phenyl, p-bromophenyl, p-O-butoxyphenyl, p-pentylphenyl, and o-, m-, and p-nitrophenyl) linked by a thioether bridge to the position C-6 of each glucopyranose unit. The yields of the S-alkylation reactions were very high (85-95%). 相似文献
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Summary We have carried out the synthesis of 2-pyrone-5- and 2-pyrone-6-carboxylic acids using,-dichloro-acrolein. 相似文献
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The cesium fluoride-catalyzed reaction of (trichloromethyl) - trimethylsilane with conjugated nitroalkenes affords β-(trichloromethyl)nitroalkanes. 相似文献
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Sotres J Svensson O Arnebrant T 《Langmuir : the ACS journal of surfaces and colloids》2011,27(3):981-992
Friction force spectroscopy (FFS) has been applied to study the tribological properties of β- and κ-casein layers on hydrophobic substrates in aqueous solutions. Nanometer-sized imaging tips were employed. This allowed exerting and determining the high pressures needed to remove the layers and registering the topographic evolution during this process. Both β- and κ-casein layers showed similar and not particularly high initial frictional responses (friction coefficient of ~1 when measured with a silicon nitride tip). The pressures needed to remove the layers were of the same order of magnitude for both proteins, ~10(8) Pa, but slightly higher for those composed of β-casein. The technique has also shown to be useful in studying the two-dimensional lateral diffusion of the proteins and the wear on the layers they form. 相似文献
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《Comptes Rendus Chimie》2003,6(1):87-90
α- and β-cyclodextrins have easily been converted into basket molecules, the handle being an oligomethylenic chain bridging A and D positions on the primary rim. The size of the handle influences the complexing properties of these cyclodextrins. To cite this article: T. Lecourt et al., C. R. Chimie 6 (2003) 000–000. 相似文献
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Kazuki Tohda Masashi Saito Hiroaki Sakai Daisuke Ishikura Ryota Saito Kaname Sasaki 《Tetrahedron》2018,74(38):5481-5485
Determining the stereochemistry at the anomeric position of glycosides is imperative in chemical synthesis. As for 1,2-cis-β-glycosides such as β-mannosides, 13C-1H coupling constants, 1JCHs, are conventionally used when glycosides are in an ordinary chair conformation. In this work, we searched for appropriate criteria to determine the stereochemistry of products in a recently developed glycosylation reaction using 2,6-lactones. As a result, we found that α-glycosides exhibited vicinal coupling constants of around 3.0?Hz?at the anomeric proton, as well as a long-range coupling between protons at C-1 and C-5, whereas β-glycosides had coupling constants of 1.2?Hz?at most. These figures are expected to be useful for future assignments. In addition, the observations obtained from this study revealed the conformation of glycosides with a 2,6-lactone moiety. 相似文献
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-(2-Arylaminoethoxy)styrenes undergo cyclization in the presence of KOH to giveN-aryl-2-benzyloxazolidines inca. 90 % yield. The structures of the products were confirmed by IR and NMR spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 340–341, February, 1994. 相似文献
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