نتایج جستجو برای: β keto ester
تعداد نتایج: 218663 فیلتر نتایج به سال:
β-Isocupreidine (β-ICD) catalyzed asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-ketoesters with allenic esters afforded ester-substituted functionalized dihydropyran derivatives in high yields along with high enantioselectivities under mild conditions.
Two new oleanane-type saponins, named oleiferasaponins C₄ (1) and C₅ (2), were isolated from Camellia oleifera Abel. seed cake residue. Their respective structures were identified as 16α-hydroxy-22α-O-angeloyl-23α-aldehyde-28-dihydroxymethylene-olean-12-ene-3β-O-[β-d-galacto-pyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→2)-β-d-galactopyranosy-(1→3)]-β-d-glucopyranosid-uronic acid methyl ester (1) and...
Acetylcholine (ACh) can effect vasodilation by several mechanisms, including activation of endothelial nitric oxide (NO) synthase and prostaglandin (PG) production. In human skin, exogenous ACh increases both skin blood flow (SkBF) and bioavailable NO levels, but the relative increase is much greater in SkBF than NO. This led us to speculate ACh may dilate cutaneous blood vessels through PGs, a...
Cholesterol has been used to monitor artifact generation. Stability differences among cholesterol oxide products (COPs) and cholesterol in thermal and alkaline conditions are theorized. Thus, use of cholesterol may be unsuitable for detection of artifacts generated from COPs. Stability of cholesterol was compared to that of 7-ketocholesterol (7-keto) and β-sitosterol (βS) under various thermal ...
A general and simple procedure to access chiral β'-amino-α,β-enones, in seven steps, from an α,β unsaturated ester has been described. The use of a Horner-Wadsworth-Emmons reaction as a key step for generating the β'-amino-α,β-enones, permits access to a range of substrates under mild conditions and in moderate to high yield.
Lead tetra acetate (Pb(IV) or LTA) oxidation of the esters X —C,,H4—C H(OH ) — COO CH, (X = H, m-NO: , p-N O : , /?;-Cl. /?-Cl. p-Br. p-CH, and p-C:H s) gives corresponding keto esters. The reaction is first order in [Pb(IV)] and second order in [Ester], and is catalysed by pyridine and 2,6-lutidine. The pyridine catalysed reaction is first order each in [Pb(IV)]. [Ester] and [Pyridine]. A kine...
M01A82W, M11A82W and M01A82WS72I are three cytochrome P450 BM3 (CYP102A1) variants. They can catalyze the hydroxylation of testosterone (TES) and norethisterone at different positions, thereby making them promising biocatalysts for steroid hydroxylation. With the aim of obtaining more hydroxylated steroid precursors it is necessary to probe the steroidal substrate diversity of these BM3 variant...
McCord, Gregg R., Jean-Luc Cracowski, and Christopher T. Minson. Prostanoids contribute to cutaneous active vasodilation in humans. Am J Physiol Regul Integr Comp Physiol 291: R596–R602, 2006. First published February 16, 2006; doi:10.1152/ajpregu.00710.2005.— The specific mechanisms by which skin blood flow increases in response to a rise in core body temperature via cutaneous active vasodilat...
Hydroxysteroid dehydrogenases (HSDHs) are from two superfamilies of short-chain dehydrogenase (SDR) and aldo–keto reductase (AKR). The HSDHs were summarized classified according to their structural functional differences. A typical pair enzymes, 7α–hydroxysteroid (7α–HSDH) 7β–hydroxysteroid (7β–HSDH), have been reported before. Molecular docking 7-keto–lithocholic acid(7–KLA) the binary 7β–HSDH...
Both PC-cyclometalated and PCP-pincer type palladium catalysts have recently been found to be robust and efficacious catalysts for the asymmetric P-H addition reaction involving activated olefins. Our studies on the asymmetric P-H addition of diphenylphosphine to malonate ester and α,β,γ,δ-alkylidenemalonate ester revealed for the first time that the catalyst choice can have a dramatic impact i...
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