نتایج جستجو برای: methyl ester
تعداد نتایج: 130453 فیلتر نتایج به سال:
From the aerial parts of Phlomis spinidens, two new flavonol bisglycosides, phlomisflavosides A (1) and B (2), were isolated together with the known compounds, astragalin, isoquercitrin, lamiridoside, phlomoside A, shanzhiside methyl ester, 8-O-acetylshanzhiside methyl ester, phlorigidoside C, rodioloside (=salidroside), forsythoside B, citroside A and lariciresinol-4'-O-beta-D-glucoside. The s...
Through a novel sequence of aminodiene Diels-Alder reactions, amidofurans 18a-c were converted to tricyclic ketones 21a-c in moderate to good yields. Ketone 21a could be converted to Uhlé's ketone (6) by cleaving the tert-butyl carbamate and oxidatively removing the methyl ester. Tricycle 21a readily underwent bromination to give 22. Formation of the corresponding enol triflate 25 followed by c...
In this study, biodiesel production from microalgal oil by microwave-assisted transesterification was carried out to investigate its efficiency. Transesterification reactions were performed by using Chlorella protothecoides oil as feedstock, methanol, and potassium hydroxide as the catalyst. Methanol:oil ratio, reaction time and catalyst:oil ratio were investigated as process parameters affecte...
Neotame is a dipeptide methyl ester derivate. Its chemical structure is N-[N-(3,3dimethylbutyl)-L-α-aspartyl]-L-phenylalanine 1-methyl ester. It is intended for use in food as a sweetener and flavour enhancer. Neotame has a sweetness factor approximately 7000 to 13000 times greater than that of sucrose and approximately 30 to 60 times greater than that of aspartame, depending upon the food appl...
An efficient de novo synthesis of vineomycinone B2 methyl ester has been achieved. The longest linear route required only 14 steps from achiral commercially available starting materials (4.0% overall yield). The key transformations included the de novo asymmetric synthesis of two key fragments, which were joined by a convergent late stage Suzuki's glycosylation for the construction of the aryl ...
Recently biodiesel (fatty acid methyl ester, FAME – in Germany mainly rapeseed oil methyl ester as a neat fuel, which means B100) became an important alternative fuel on the German and the European markets. Approximately 1,200,000 tons were sold in Germany in the year 2004 (VDB, 2004). This is more than 50 % of all biodiesel that is sold in the European Union (Observ’ER, 2004). Today biodiesel ...
Five phenolic compounds, 4-hydroxybenzoic acid methyl ester (1), vanillic acid methyl ester (2), 4-hydroxy benzaldehyde (3), 4-hydroxybenzoic acid (4) and ferulic acid (5), and four flavonoids, 5,5'-dihydroxy-4',6,7-trimethoxyflavanone (6), luteolin (7), vitexicarpin (8) and artemetin (9), were isolated from fruits and leaves of Vitex rotundifolia L. The biological activities of these nine comp...
Kinetic data on potassium release from and killing of Candida albicans by the four polyene antibiotics amphotericin B, amphotericin B methyl ester hydrochloride, nystatin, and nystatin methyl ester hydrochloride are presented. The nystatins were relatively more effective than the amphotericins in causing potassium release rather than killing. These data suggest that the aqueous channels or pore...
Low-temperature ozonation (-78 degrees C) of 2-methyl-1,3-dioxolane (1a) in acetone-d6, methyl acetate, and tert-butyl methyl ether produced both the corresponding acetal hydrotrioxide (3a, ROOOH) and the hemiortho ester (2a, ROH) in molar ratio 1:5. Both intermediates were fully characterized by 1H, 13C, and 17O NMR spectroscopy, and they both decomposed to the corresponding hydroxy ester at h...
Although the pimeloyl moiety was long known to be a biotin precursor, the mechanism of assembly of this C7 α,ω-dicarboxylic acid was only recently elucidated. In Escherichia coli, pimelate is made by bypassing the strict specificity of the fatty acid synthetic pathway. BioC methylates the free carboxyl of a malonyl thioester, which replaces the usual acetyl thioester primer. This atypical prime...
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