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Allylic hydroxy phosphonates and their derivatives can be interconverted by using cross metathesis with second generation Grubbs catalyst. The absolute stereochemistry of the starting phosphonate is conserved in the product. Cross metathesis reaction of the acrolein-derived phosphonate 2a yields a series of functionalized allylic hydroxy phosphonates. However, the cross metathesis reaction is often accompanied by competing dimerization and alkene migration reactions leading to a reduction in yield. The cinnamaldehyde- and crotonaldehyde-derived phosphonates 2b and 2c were also examined. In general, the metathesis reactions of phosphonates 2b and 2c are considerably slower than those for phosphonate 2a leading to mixtures. Several hydroxyl-protected derivatives of the phosphonate 2a (methyl carbonate 3a, acetate 4a, N-tosyl carbamate 5a, TBDMS 6a, and acetoacetate 7a) undergo metathesis without competing side reactions to give substituted allylic phosphonates in good to excellent yield. 相似文献
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Anchalee Sirikulkajorn Thawatchai Tuntulani Boosayarat Tomapatanaget Anthony P. Davis 《Tetrahedron》2010,66(37):7423-520
A cholapod receptor possessing urea binding sites at C3, C7, and C12 positions and with an intrinsic chiral structure was synthesized, and the binding abilities toward amino acids in both l- and d- forms (Trp, Phe, Leu, and Ala) were studied using 1H NMR spectroscopy, UV-vis spectroscopy and computer simulation. Changes in 1H NMR spectra of the receptor revealed that complexation with amino acids occurred via hydrogen bonding and CH-π interactions. Binding to tryptophan was especially strong, and was found to be enantioselective (Ka=480 M−1 for l-Trp, 260 M−1 for d-Trp). NOESY and computer simulations were used to investigate the structures of the diastereomeric complexes between the receptor and the tryptophan enantiomers. In the case of l-Trp the carboxylate group bound at the two ureas adjacent to C7 and C12, while d-Trp was positioned closer to the urea adjacent to C3. 相似文献
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Sompong Dhompongsa Anchalee Kaewcharoen Attapol Kaewkhao 《Nonlinear Analysis: Theory, Methods & Applications》2006
Let E be a nonempty bounded closed convex separable subset of a reflexive Banach space X which satisfies the Domínguez–Lorenzo condition, i.e., an inequality concerning the asymptotic radius of a sequence and the Chebyshev radius of its asymptotic center. We prove that a multivalued nonexpansive mapping T:E→2X which is compact convex valued and such that T(E) is bounded and satisfies an inwardness condition has a fixed point. As a consequence, we obtain a fixed-point theorem for multivalued nonexpansive mappings in uniformly nonsquare Banach spaces which satisfy the property WORTH, extending a known result for the case of nonexpansive single-valued mappings. We also prove a common fixed point theorem for two nonexpansive commuting mappings t:E→E and T:E→KC(E) (where KC(E) denotes the class of all compact convex subsets of E) when X is a uniformly convex Banach space. 相似文献
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Pakorn Bovonsombat Rameez Ali Chiraphorn Khan Juthamard Leykajarakul Kawin Pla-on Suraj Aphimanchindakul Natchapon Pungcharoenpong Nisit Timsuea Anchalee Arunrat Napat Punpongjareorn 《Tetrahedron》2010,66(34):6928-181
para-Regioselective bromination of phenol and analogues, promoted by p-toluenesulfonic acid, is achieved in high to excellent yields at room temperature with N-bromosuccinimide. Chlorination with N-chlorosuccinimide and catalysed by p-toluenesulfonic acid also gives para-chlorinated phenol analogues in good yields at room temperature. 相似文献
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Anchalee Rawangkan Kirati Kengkla Sukrit Kanchanasurakit Acharaporn Duangjai Surasak Saokaew 《Molecules (Basel, Switzerland)》2021,26(13)
Influenza is one of the most serious respiratory viral infections worldwide. Although several studies have reported that green tea catechins (GTCs) might prevent influenza virus infection, this remains controversial. We performed a systematic review and meta-analysis of eight studies with 5048 participants that examined the effect of GTC administration on influenza prevention. In a random-effects meta-analysis of five RCTs, 884 participants treated with GTCs showed statistically significant effects on the prevention of influenza infection compared to the control group (risk ratio (RR) 0.67, 95% CIs 0.51–0.89, p = 0.005) without evidence of heterogeneity (I2 = 0%, p = 0.629). Similarly, in three cohort studies with 2223 participants treated with GTCs, there were also statistically significant effects (RR 0.52, 95% CIs 0.35–0.77, p = 0.001) with very low evidence of heterogeneity (I2 = 3%, p = 0.358). Additionally, the overall effect in the subgroup analysis of gargling and orally ingested items (taking capsules and drinking) showed a pooled RR of 0.62 (95% CIs 0.49–0.77, p = 0.003) without heterogeneity (I2 = 0%, p = 0.554). There were no obvious publication biases (Egger’s test (p = 0.138) and Begg’s test (p = 0.103)). Our analysis suggests that green tea consumption is effective in the prophylaxis of influenza infections. To confirm the findings before implementation, longitudinal clinical trials with specific doses of green tea consumption are warranted. 相似文献
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An Ethanol Biosensor Based on Simple Immobilization of Alcohol Dehydrogenase on Fe3O4@Au Nanoparticles
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Anchalee Samphao Kanjana Kunpatee Sanchai Prayoonpokarach Jatuporn Wittayakun Ľubomír Švorc Dalibor M. Stankovic Kristina Zagar Miran Ceh Kurt Kalcher 《Electroanalysis》2015,27(12):2829-2837
An ethanol biosensor based on alcohol dehydrogenase (ADH) attached to Au seeds decorated on magnetic nanoparticles (Fe3O4@Au NPs) is presented. ADH was immobilized on Fe3O4@Au NPs, which were subsequently fixed by a magnet on a carbon paste electrode modified with 5 % (m : m) MnO2. Optimum conditions for the amperometric determination of ethanol with the biosensor were as follows: working potential +0.1 V (vs. Ag/AgCl); supporting electrolyte: 0.1 M phosphate buffer solution at pH 6.8 containing 0.25 mM of the coenzyme (NAD+); working electrode: carbon paste with magnetically attached Fe3O4@Au NPs (0.012 mg ? cm?2 electrode area) with immobilized alcohol dehydrogenase (120 units per cm2 of electrode area). Linearity between signal and concentration was found for the range from 0.1 to 2.0 M ethanol (r2=0.995) with a detection limit of 0.07 M, a sensitivity of 0.02 µA ? mM?1 ? cm?2, a reproducibility of 4.0 % RSD, and a repeatability of 2.7 % RSD. The results for the determination of ethanol in alcoholic beverages showed good agreement with gas chromatography (GC) with recovery of 96.0 – 108.8 %. 相似文献
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Anchalee Thanavaro Christopher D. Spilling 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1583-1586
Treatment of allylic hydroxy phosphonates in aldehyde solution with mercuric trifluoroacetate, followed by the reduction of the organomercurial intermediate, afforded the cyclic acetal derivatives. The reaction displays high diastereo- and regio-selectivity. 31 P NMR studies showed the formation of an intermediate hemiacetal and rapid formation of the organomercurial upon addition of mercuric trifluoroacetate. However, the oxymercuration was reversible, and attempts to remove the excess aldehyde often led to recovery of the starting material. Fortunately, reduction of the organomercurial intermediate with sodium cyanoborohydride in the presence of the aldehyde led to more reproducible yields. 相似文献