- One-Pot Synthesis of 3-Aryl-5-amino-1,2,4-thiadiazoles from Imidates and Thioureas by I2-Mediated Oxidative Construction of the N–S Bond
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A simple and practical method for the one-pot synthesis of 3-aryl-5-amino-1,2,4-thiadiazoles from imidates and thioureas has been developed. The protocol proceeds through sequential base-mediated nucleophilic addition-elimination reactions and an I2-mediated oxidative coupling for the N–S bond formation. The approach employes readily available and nontoxic substrates and a simple workup to provide 3-aryl-5-amino-1,2,4-thiadiazoles that have a free or substituted amino group.
- Chai, Ling,Lai, Zhenzhen,Xia, Qiangqiang,Yuan, Jiangpei,Bian, Qilong,Yu, Mingjian,Zhang, Wenkai,Xu, Yuanqing,Xu, Hao
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p. 4338 - 4344
(2018/08/31)
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- Copper-Catalyzed Aerobic Oxidative [3+2] Annulation for the Synthesis of 5-Amino/Imino-Substituted 1,2,4-Thiadiazoles through C-N/N-S Bond Formation
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A copper-catalyzed aerobic oxidative annulation reaction of 2-aminopyridine/amidine with isothiocyanate has been reported. This strategy involving C-N/N-S bond formations provides various 5-amino/imino-substituted 1,2,4-thiadiazole derivatives under a Cu/O2 catalytic system. This method has demonstrated high reactivity, mild reaction conditions, and a broad substrate scope. Furthermore, the synthetic utilities of the approach are demonstrated by further modifications.
- Yu, Wentao,Huang, Yubing,Li, Jianxiao,Tang, Xiaodong,Wu, Wanqing,Jiang, Huanfeng
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p. 9334 - 9343
(2018/07/30)
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- Facile synthesis of substituted 5-amino- And 3-amino-1,2,4-thiadiazoles from a common precursor
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[Chemical Equation Presented] A novel approach to the synthesis of substituted 5-amino- and 3-amino-1,2,4-thiadiazoles beginning from a common precursor has been achieved. Derivatization by palladium-catalyzed Suzuki-Miyaura coupling enables the rapid pre
- Wehn, Paul M.,Harrington, Paul E.,Eksterowicz, John E.
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scheme or table
p. 5666 - 5669
(2010/03/01)
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- Pyrimidine benzamide-based thrombopoietin receptor agonists
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A series of pyrimidine benzamide-based thrombopoietin receptor agonists is described. The lead molecule contains a 2-amino-5-unsubstituted thiazole, a group that has been associated with idiosyncratic toxicity. The potential for metabolic oxidation at C-5 of the thiazole, the likely source of toxic metabolites, was removed by substitution at C-5 or by replacing the thiazole with a thiadiazole. Potency in the series was improved by modifying the substituents on the pyrimidine and/or on the thiazole or thiadiazole pendant aryl ring. In vivo examination revealed that compounds from the series are not highly bioavailable. This is attributed to low solubility and poor permeability.
- Reiter, Lawrence A.,Subramanyam, Chakrapani,Mangual, Emilio J.,Jones, Christopher S.,Smeets, Marc I.,Brissette, William H.,McCurdy, Sandra P.,Lira, Paul D.,Linde, Robert G.,Li, Qifang,Zhang, Fangning,Antipas, Amy S.,Blumberg, Laura C.,Doty, Jonathan L.,Driscoll, James P.,Munchhof, Michael J.,Ripp, Sharon L.,Shavnya, Andrei,Shepard, Richard M.,Sperger, Diana,Thomasco, Lisa M.,Trevena, Kristen A.,Wolf-Gouveia, Lilli A.,Zhang, Liling
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p. 5447 - 5454
(2008/03/11)
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- Photoinduced molecular rearrangements. The photochemistry of 1,2,4-oxadiazoles in the presence of sulphur nucleophiles. Synthesis of 1,2,4-thiadiazoles
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The photochemistry of some 1,2,4-oxadiazoles in the presence of sulphur nucleophiles has been investigated. Irradiation of the 5-amino-3-phenyl- and 3,5-diphenyl-1,2,4-oxadiazole at λ = 254 nm in methanol in the presence of sodium hydrogen sulphide or thiols gave a photo-induced redox reaction at the ring O-N bond, leading to the corresponding N-substituted benzamidines. By contrast, irradiation of the 5-amino-3-phenyl-1,2,4-oxadiazole in the presence of thioureas or thiocarbamates, essentially gave 3-phenyl-5-substituted 1,2,4-thiadiazoles, which presume an N-S bond formation between the ring-photolytic species and the sulphur nucleophile. In turn, irradiation of the same 5-amino-3-phenyl-1,2,4-oxadiazole in the presence of thioamides again afforded the redox reaction; in addition, amounts of 3-phenyl-5-substituted-1,2,4-thiadiazoles were also formed. Some mechanistic considerations are reported and synthetic methodologies leading to 1,2,4-thiadiazoles are emphasized.
- Vivona, Nicolo,Buscemi, Silvestre,Asta, Stefano,Caronna, Tullio
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p. 12629 - 12636
(2007/10/03)
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- Heterocyclyl-azo-phenyl dyes having a cationic group linked through a branched alkylene chain to the nitrogen atom of the coupling component radical
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Compounds of the formula STR1 in which R1 signifies a substituted thiazole, thiadiazole, isothiazole, oxadiazole or thiophene radical, R2 signifies hydrogen or an optionally substituted hydrocarbon radical, R3 signifies hydrogen or an optionally substituted alkyl radical, R4 signifies hydrogen or an alkyl radical which is unsubstituted or substituted by an aryl radical, K≈ signifies an ammonium, cycloimmonium, hydrazinium, aminoxide or optionally substituted etherified hydroxyammonium group, An? signifies an anion, n signifies 1, 2 or 3, and the ring B is unsubstituted or monosubstituted, provided that at least one of R3 and R4 is other than hydrogen, and provided that the molecule does not contain a water-solubilizing group. The compounds are useful as basic azo dyes, for dyeing and printing polyacrylonitrile, acrylonitrile copolymers, polymers of asymmetrical dicyanoethylene, polyamides and polyesters modified to contain acid groups, leather, cellulosic materials and paper and for the mass coloration of plastics. The dyes are well-soluble in water, have good salt compatability and give level dyeings having good fastness to light, wet treatments, heat treatments and solvents.
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