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51.
Harada H Kazami J Watanuki S Tsuzuki R Sudoh K Fujimori A Tanaka A Tsukamoto S Yanagisawa I 《Chemical & pharmaceutical bulletin》2001,49(5):606-612
In the present article we wish to report the discovery of a novel class of ET(A)-selective endothelin (ET) receptor antagonists through the modification of the ET(A)/ET(B) non-selective antagonist, Ro47-0203 (Bosentan, 1). Replacement of the benzenesulfonamide group of 1 with a 2-phenylethenesulfonamide group gave compound 5a and resulted in improvement in ET(A)-selectivity. Optimization of the alkoxy side chain attached to the core pyrimidine ring yielded the 2-fluoroethoxy derivative (5n) with further improvement of ET(A)-selectivity. [IC50=2.1 nM for ET(A) receptor, ET(B)/ET(A) ratio=1200]. After oral administration, compound 5n inhibited the big ET-1 induced pressor response in pithed rats with a DR2 value of 2.6 mg/kg and also exhibited a potent antagonistic activity in conscious rats. 相似文献
52.
Subir Goswami Prof. Dr. Kenichi Harada Prof. Dr. Mohamed F. El‐Mansy Dr. Rajinikanth Lingampally Prof. Dr. Rich G. Carter 《Angewandte Chemie (International ed. in English)》2018,57(29):9117-9121
The efficient, 12–14 step (LLS) total synthesis of (?)‐halenaquinone has been achieved. Key steps in the synthetic sequence include: (a) proline sulfonamide‐catalyzed, Yamada–Otani reaction to establish the C6 all‐carbon quaternary stereocenter, (b) multiple, novel palladium‐mediated oxidative cyclizations to introduce the furan moiety, and (c) oxidative Bergman cyclization to form the final quinone ring. 相似文献
53.
54.
Thamina Akther Md.Monarul Islam Taisuke Matsumoto Junji Tanaka Pierre Thuéry Carl Redshaw Takehiko Yamato 《Tetrahedron》2018,74(2):329-335
The reductive coupling reaction of 1,4-bis(3-acetyl-5-tert-butyl-2-methoxyphenyl)butane 3 was carried out using TiCl4-Zn in pyridine followed by a McMurry coupling reaction to afford the compounds anti and syn 1,2-dimethyl[2.4]MCP-1-ene 4. Bromination of 4 with BTMA-Br3 in dry CH2Cl2 afforded the interesting compound 1,2-bis-(bromomethyl)-5,15-di-tert-butyl-8,18-dimethoxy[2.4]MCP-1-ene 6 and consecutive debromination with Zn and AcOH in CH2Cl2 solution afforded the stable solid 5,15-di-tert-butyl-8,18-dimethoxy-1,2-dimethylene[2.4]MCP 7 in 89% yield. Compound 7 was conveniently employed in a Diels–Alder reaction with dimethyl acetylenedicarboxylate (DMAD) to provide 2-(3′,6′-dihydrobenzo)-5,15-di-tert-butyl-8,18-dimethoxy[2.4]MCP-4′,5′-dimethylcarboxylate 8 in good yield. Diels–Alder adduct 8 was converted into a novel and inherently chiral areno-bridged compound [2.4]MCP 9 by aromatization. The chirality of the two conformers was characterized by circular dichroism (CD) spectra of the separated enantiomer which are perfect mirror images of each other. 相似文献
55.
Light‐Induced Reversible Reconfiguration of DNA‐Based Constitutional Dynamic Networks: Application to Switchable Catalysis 下载免费PDF全文
Dr. Shan Wang Dr. Liang Yue Zi‐Yuan Li Dr. Junji Zhang Prof. He Tian Prof. Itamar Willner 《Angewandte Chemie (International ed. in English)》2018,57(27):8105-8109
The light‐induced reversible and cyclic reconfiguration of constitutional dynamic networks, consisting of supramolecular nucleic acid structures as constituents and a photoisomerizable trans/cis‐azobenzene‐functionalized nucleic acid as the trigger is demonstrated. In addition, the cyclic photochemical reconfiguration of the constitutional dynamic networks guides the switchable on/off operation of an emerging hemin/G‐quadruplex DNAzyme. 相似文献
56.
[reaction: see text]. Phenylalanine-derived B-aryl-N-tosyloxazaborolidinones selectively activate one of two enantiotopic oxygen atoms in prochiral anti dioxane acetals derived from meso-1,3-diols, leading to enantioselective formation of ring-cleavage products. The reaction is utilized as a key step in asymmetric desymmetrization of meso-1,3-diols. 相似文献
57.
H Harada J Kazami S Watanuki R Tsuzuki K Sudoh A Fujimori T Tokunaga A Tanaka S Tsukamoto I Yanagisawa 《Chemical & pharmaceutical bulletin》2001,49(12):1593-1603
In the previous paper, we described a series of the 2-arylethenesulfonamide derivatives, a novel class of ETA-selective endothelin (ET) receptor antagonists, including the compounds 1a, b. Compound 1a showed excellent oral antagonistic activities and pharmacokinetic profiles, and the monopotassium salt of 1 (YM-598 monopotassium) is in clinical trials. In this paper, we wish to report the investigation of the further details of structure-activity relationships (SARs) of the 2-phenylethenesulfonamide region in 1a. It was found that methyl substitutions at the 2-, 4- and 6-positions of the phenyl group in 1a led to the discovery of the ET(A)/ET(B) mixed antagonist (6s) with an IC50 of 2.2 nM for the ET(A) receptor. We also found that introduction of an ethyl group to the 1-position of the ethenyl group in 1a gave the ET(A) selective antagonist (6u) with an oral endothelin antagonistic activity in rats. 相似文献
58.
Synthesis and in vitro antifungal activities of novel triazole antifungal agent CS-758. 总被引:1,自引:0,他引:1
T Konosu S Oida Y Nakamura S Seki T Uchida A Somada M Mori Y Harada Y Kamai T Harasaki T Fukuoka S Ohya H Yasuda T Shibayama S Inoue A Nakagawa Y Seta 《Chemical & pharmaceutical bulletin》2001,49(12):1647-1650
Synthesis and in vitro antifungal activities of a novel triazole antifungal agent CS-758 (former name, R-120758) are described. The minimum inhibitory concentrations (MICs) of a series of dioxane-triazole compounds related to R-102557 were examined. Variation of the length of the chain between the dioxane ring and the phenyl ring revealed that the linkage with two double bonds is the most preferable. When a cyano group was introduced to the C4 position on the benzene ring, MICs improved further. A fluorine atom was introduced to obtain CS-758. The MICs of CS-758 surpassed those of fluconazole and itraconazole against Candida, Aspergillus and Cryptococcus species. The precursor (E,E)-aldehyde was synthesized stereoselectively from 3-fluoro-4-methylbenzonitrile using the Horner-Wadsworth-Emmons reaction. 相似文献
59.
H Oka Y Ikai N Kawamura K Uno M Yamada K Harada M Uchiyama H Asukabe M Suzuki 《Journal of chromatography. A》1987,393(2):285-296
Analytical methods for eight tetracyclines (TCs) were established using silica gel high-performance thin-layer chromatography (HPTLC), reversed-phase thin-layer chromatography (RP-TLC) and high-performance liquid chromatography (HPLC). Good separations of eight TCs were obtained using chloroform-methanol-5% disodium ethylenediaminetetraacetate solution (65:20:5) (lower layer) and methanol acetonitrile 0.5 M oxalic acid solution (1:1:4) (pH 3.0) on silica gel HPTLC and C8 TLC plates, respectively. A combination of HPTLC and RP-TLC made possible the identification of the eight TCs. Each calibration graph was linear between 0.1 and 1.0 microgram using UV densitometry except for rolitetracycline. For detection reagents, the diazonium salts including Fast Violet B gave variously coloured spots with the eight TCs and good sensitivities were obtained except with minocycline. In HPLC, the simultaneous analysis of the eight TCs on a C8 column was possible using methanol-acetonitrile-0.01 M oxalic acid solution (1:1.5:7) adjusted to pH 3.0 as the mobile phase. A linear relationship was obtained between 1.0 and 10 ng using the usual sample preparation except for rolitetracycline. The direct determination of rolitetracycline was possible using tetrahydrofuran, dimethyl sulphoxide and the mobile phase as solvents for preparation of the sample. For the determination of residual rolitetracycline, it was effective to measure the amount of rolitetracycline as tetracycline by HPLC, HPTLC and RP-TLC after conversion of rolitetracycline to tetracycline by incubating for 5 min in methanol at 50 degrees C. 相似文献
60.