- Oxidation of anisoles to p-benzoquinone monoketals catalyzed by a ruthenium complex of 1,4,7-trimethyl-1,4,7-triazacyclononane with tert-butyl hydroperoxide
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A protocol based on [RuIII(Me3tacn)(CF 3CO2)2(H2O)]CF3CO 2 (1, Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) as catalyst and tert-butyl hydroperoxide (TBHP) as oxidant was developed for oxidation of anisoles to p-benzoquinone monoketals. This reaction can be formally considered as regioselective aromatic C-H oxidation. With 2-methoxyanisole as substrate, 3,4-dimethoxy-4-tert-butoxy-2,5-cyclohexadienone can be obtained in up to 82% yield based on 84% substrate conversion.
- Cheung, Wai-Hung,Yip, Wing-Ping,Yu, Wing-Yiu,Che, Chi-Ming
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- Design, synthesis, and preliminary biological evaluation of 3′,4′,5′-trimethoxy flavonoid salicylate derivatives as potential anti-tumor agents
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According to the pharmacophore combination principle, a set of new 3′,4′,5′-trimethoxy flavonoid salicylate derivatives were designed, synthesized, and evaluated for biological activity. The cytotoxicity evaluation revealed that compound 10v exhibited higher potency than 5-Fu against HCT-116 cells. Preliminary biological activity studies showed that compound 10v could inhibit the colony formation and migration of HCT-116 cells. Besides, the Hoechst 33258 staining assay and flow cytometry revealed that treatment with compound 10v induced the apoptosis of HCT-116 cells in a concentration-dependent manner, while it had no effect on their cell cycle. The WB analysis suggested that HIF-1α, tubulin, HK-2, and PFK might be the potential pharmacophore targets of compound 10v. Tubulin was a potential drug target for compound 10v, which was explained by analyzing the crystal structure of compound 10v complexed with tubulin. These results indicated that compound 10v might be a promising anti-tumor agent candidate, deserving further optimization and evaluation.
- Deng, Xiangping,Liu, Renbo,Li, Junjian,Li, Zhongli,Liu, Juan,Xiong, Runde,Lei, Xiaoyong,Zheng, Xing,Xie, Zhizhong,Tang, Guotao
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p. 1874 - 1884
(2019/01/28)
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- Discovery, synthesis, biological evaluation and molecular docking study of (R)-5-methylmellein and its analogs as selective monoamine oxidase A inhibitors
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(R)-5-Methylmellein (5-MM), the major ingredient in the fermented mycelia of the medicinal fungus Xylaria nigripes (called Wuling Shen in Chinese)? was found to be a selective inhibitor against monoamine oxidase A (MAO-A) and might play an important role in the clinical usage of this edible fungus as an anti-depressive traditional Chinese medicine (TCM). Based on the discovery and hypothesis, a variety of (R)-5-MM analogs were synthesized and evaluated in vitro against two monoamine oxidase isoforms (MAO-A and MAO-B). Most synthetic analogs showed selective inhibition of MAO-A with IC50 values ranging from 0.06 to 29 μM, and compound 13aR is the most potent analog with high selectivity (IC50, MAO-A: 0.06 μM; MAO-B: >50 μM). Interestingly, the enzyme kinetics study of 13aR indicated that this ligand seemed to bind in the MAO-A active site according to so-called “tight-binding inhibition” mode. The molecular docking study of 13aR was thereafter performed in order to rationalize the obtained biological results.
- Huang, Chao,Xiong, Juan,Guan, Hui-Da,Wang, Chang-Hong,Lei, Xinsheng,Hu, Jin-Feng
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p. 2027 - 2040
(2019/04/10)
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- The enantioselective Birch-Cope sequence for the synthesis of carbocyclic quaternary stereocenters. Application to the synthesis of (+)-mesembrine
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A synthetic technique for generating carbocyclic quaternary stereocenters with exceptionally high levels of enantioselectivity is described. A sequence of three reactions, enantioselective Birch reduction-allylation, enol ether hydrolysis, and Cope rearrangement, is used to stereoselectively generate chiral quaternary centers on a 2-cyclohexen-1-one ring. The products of the sequence are 4,4-disubstituted-2-carboxamide-2-cyclohexen-1-one structures which are versatile intermediates in complex natural product synthesis. An application of the sequence to the synthesis of (+)-mesembrine illustrates the utility of these intermediates.
- Paul, Tapas,Malachowski, William P.,Lee, Jisun
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p. 4007 - 4010
(2007/10/03)
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- Carboxylation of anisole derivatives with CO and O2 catalyzed by Pd(OAc)2 and molybdovanadophosphates
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Anisole and its homologues were carboxylated under the influence of CO and O2 catalyzed by Pd(OAc)2 combined with molybdovanadophosphates (HPMoV) under mild conditions to give the corresponding carboxylic acids in fair to good yields; for instance, anisole underwent the carboxylation under a mixed gas of CO (0.5 atm) and O2 (0.5 atm) in the presence of Pd(OAc)2 (5 mol%) and H5PMo 10V2O40·nH2O (2 mol%) to form an isomeric mixture of anisic acids in good yield.
- Ohashi, Shinichiro,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 486 - 488
(2008/09/18)
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- Refinement and evaluation of a pharmacophore model for flavone derivatives binding to the benzodiazepine site of the GABAA receptor
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To further develop and evaluate a pharmacophore model previously proposed by Cook and co-workers (Drug Des. Discovery 1995, 12, 193-248) for ligands binding to the benzodiazepine site of the GABAA receptor, 40 new flavone derivatives have been synthesized and their affinities for the benzodiazepine site have been determined. Two new regions of steric repulsive interactions between ligand and receptor have been characterized, and the receptor region in the vicinity of 6- and 3′-substituents has been mapped out. 2′-Hydroxy substitution is shown to give a significant increase in affinity, which is interpreted in terms of a novel hydrogen bond interaction with the previously proposed hydrogen bond-accepting site A2. On the basis of the results of these studies and the refined pharmacophore model, 5′-bromo-2′-hydroxy-6-methylflavone, the highest affinity flavone derivative reported so far (Ki = 0.9 nM), was successfully designed. A comparison of the pharmacophore model with a recently proposed alternative model (Marder; et al. Bioorg. Med. Chem., 2001, 9, 323-335) has been made.
- Kahnberg, Pia,Lager, Erik,Rosenberg, Celia,Schougaard, Jette,Camet, Linda,Sterner, Olov,Nielsen, Elsebet ?stergaard,Nielsen, Mogens,Liljefors, Tommy
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p. 4188 - 4201
(2007/10/03)
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- The effect of an alkoxy group on the kinetic and thermodynamic acidity of benzene and toluene
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2-, 3- and 4-Methoxytoluene can be selectively metalated at an O-adjacent ortho position when butyllithium or tert-butyllithium in the presence of sodium (potassium) tert-butoxide or N,N,N',N'',N''-pentamethyldiethylenetriamine are employed as reagents. In contrast, lithium diisopropylamide or lithium 2,2,6,6-tetramethylpiperidide deprotonate the benzylic α-position of 2- and 3-methoxytoaluene exclusively and of 4-methoxytoluene preferentially. These relative reactivities can be rationalized by an interplay of transition state stabilizing and destabilizing forces (dipole matching and metal coordination vs. lone pair repulsion).
- Schlosser, Manfred,Maccaroni, Paola,Marzi, Elena
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p. 2763 - 2770
(2007/10/03)
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- Pd(O)-CATALYZED ELECTROREDUCTIVE CARBOXYLATION OF ARYL HALIDES, β-BROMOSTYRENE, AND ALLYL ACETATES WITH CO2
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Electroreductive carboxylation of aryl halides, β-bromostyrene, and allyl acetates has been performed in an aprotic solvent saturated with carbon dioxide in the presence of a catalytic amount of PdCl2(Ph3P)2 and/or Pd(Ph3P)4.
- Torii, Sigeru,Tanaka, Hideo,Hamatani, Takeshi,Morisaki, Kazuo,Jutand, Anny,et al.
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p. 169 - 172
(2007/10/02)
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