- Novel Conjugated s-Tetrazine Derivatives Bearing a 4H-1,2,4-Triazole Scaffold: Synthesis and Luminescent Properties
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A series of new symmetrical s-tetrazine derivatives, coupled via a 1,4-phenylene linkage with a 4H-1,2,4-triazole ring, were obtained. The combination of these two rings in an extensively coupled system has significant potential applications, mainly in op
- ?wiatkowski, Marcin,Kudelko, Agnieszka,Maj, Anna
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- α-Imino Iridium Carbenes from Imidoyl Sulfoxonium Ylides: Application in the One-Step Synthesis of Indoles
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Imidoyl sulfoxonium ylides are presented for the first time as potential precursors to generate α-imino metal-carbene intermediates and applied in direct C-H functionalization reactions catalyzed by [Ir(cod)Cl]2 (4 mol %) to provide 2-substituted indoles (up to 70% yield) in just one step. This class of sulfur ylide is successfully obtained from imidoyl chloride and dimethylsulfoxonium methylide (23 new examples in 45-85% yield) or by imino group formation from the corresponding β-keto sulfoxonium ylides and anilines in the presence of TiCl4 as a Lewis acid (9 examples in 33-94% yield).
- Burtoloso, Antonio C. B.,Caiuby, Clarice A. D.,De Jesus, Matheus P.
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p. 7433 - 7445
(2020/06/27)
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- Silver(II) oxide-mediated synthesis of 2,4-diarylquinazolines
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A single-pot procedure for the synthesis of 2,4-diarylquinazolines is described which involves a silver oxide-mediated C–H activation/C–N bond formation process. The generality of this method with respect to substituent effects is presented along with studies leading to process optimization. Mechanistic investigations provide support for the involvement of radical intermediates in the reaction process.
- Cheung, Wing,Patch, Raymond J.,Player, Mark R.
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supporting information
p. 2368 - 2371
(2018/05/25)
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- One-pot synthesis of polyfunctionalized quinolines: Via a copper-catalyzed tandem cyclization
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An efficient one-pot approach for the synthesis of polyfunctionalized quinolines was developed via a sequence of copper-catalyzed coupling reaction/propargyl-allenyl isomerization/aza-electrocyclization. Easily available starting materials, mild conditions, and a wide substrate scope make this approach potentially useful.
- Chen, Dianpeng,Sun, Xuejun,Shan, Yingying,You, Jinmao
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supporting information
p. 7657 - 7662
(2018/11/02)
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- Transition Metal-Free Visible Light-Driven Photoredox Oxidative Annulation of Arylamidines
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A fast catalytic synthesis of multisubstituted quinazolines from readily available amidines via visible light-mediated oxidative C(sp3)-C(sp2) bond formation has been established. This reaction is a metal-free oxidative coupling catalyzed by a photoredox organocatalyst. The protocol features low catalyst loading (1 mol %).
- Shen, Zi-Chao,Yang, Pan,Tang, Yu
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p. 309 - 317
(2016/01/15)
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- Efficient synthesis of tertiary acyclic amides by the Chapman rearrangement of aryl benzimidates in ionic liquids
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The Chapman rearrangement of aryl N-arylbenzimidates to tertiary acyclic amides is accelerated in ionic liquids and proceeds at lower temperatures as 120-190°C.
- Epishina, Margarita A.,Kulikov, Alexander S.,Ignat'Ev, Nikolai V.,Schulte, Michael,Makhova, Nina N.
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p. 126 - 128
(2015/04/14)
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- Solvent/oxidant-switchable synthesis of multisubstituted quinazolines and benzimidazoles via metal-free selective oxidative annulation of arylamidines
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A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp3)-C(sp2) and C(sp 2)-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp3C-H/sp2C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.
- Lin, Jian-Ping,Zhang, Feng-Hua,Long, Ya-Qiu
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supporting information
p. 2822 - 2825
(2014/06/23)
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- 5-Imino-1,2,4-thiadiazoles: First small molecules As substrate competitive inhibitors of glycogen synthase kinase 3
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Cumulative evidence strongly supports that glycogen synthase kinase-3 (GSK-3) is a pathogenic molecule when it is up-dysregulated, emerging as an important therapeutic target in severe unmet human diseases. GSK-3 specific inhibitors might be promising effective drugs for the treatment of devastating pathologies such as neurodegenerative diseases, stroke, and mood disorders. As GSK-3 has the ability to phosphorylate primed substrates, small molecules able to bind to this site should be perfect drug candidates, able to partially block the activity of the enzyme over some specific substrates. Here, we report substituted 5-imino-1,2,4-thiadiazoles as the first small molecules able to inhibit GSK-3 in a substrate competitive manner. These compounds are cell permeable, able to decrease inflammatory activation and to selectively differentiate neural stem cells. Overall, 5-imino-1,2,4-thiadiazoles are presented here as new molecules able to decrease neuronal cell death and to increase endogenous neurogenesis blocking the GSK-3 substrate site
- Palomo, Valle,Perez, Daniel I.,Perez, Concepcion,Morales-Garcia, Jose A.,Soteras, Ignacio,Alonso-Gil, Sandra,Encinas, Arantxa,Castro, Ana,Campillo, Nuria E.,Perez-Castillo, Ana,Gil, Carmen,Martinez, Ana
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experimental part
p. 1645 - 1661
(2012/04/04)
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- Synthesis and Biological Evaluation of 2,3,5-Substituted [1,2,4]Thiadiazoles as Allosteric Modulators of Adenosine Receptors
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A number of 2,3,5-substituted [1,2,4]thiadiazole analogues of SCH-202676 (N-(2,3-diphenyl-[1,2,4]thiadiazole-5(2H)-ylidene)methanamine, 7a) were synthesized and tested as potential allosteric modulators of adenosine receptors. All compounds were capable of displacing the binding of the radiolabeled agonist [3H]CCPA to human A1 adenosine receptors, whereas modest and varying effects were observed on the binding of [3H]DPCPX, a radiolabeled antagonist for this receptor subtype. Four compounds, 7a (SCH-202676), 7k (LUF5792), 71 (LUF5794), and 8e (LUF5789), were selected for more detailed characterization. They all proved allosteric inhibitors of agonist binding, with 7k being most potent, whereas their effects on antagonist binding were more ambiguous. Subsequently, experiments were done on human adenosine A2A and A3 receptors. Compounds 7a and 7l displayed peculiar displacement characteristics of both radiolabeled agonist and antagonist binding to A2A receptors, whereas 7a showed some activity on A3 receptors.
- Van Den Nieuwendijk, Adrianus M. C. H.,Pietra, Daniele,Heitman, Laura,G?bly?s, Anikó,IJzerman, Adriaan P.
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p. 663 - 672
(2007/10/03)
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- N-arylbenzonitrilium ions. Photochemical generation and effect of substituents in the phenyl rings on lifetimes in water and reactivity with azide ion
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Nitrilium ions Ar-C≡N+-Ar′ have been studied by laser flash photolysis in aqueous solutions containing 20% acetonitrile. The cations were generated by photoheterolysis of benzimidate esters Ar-CZ=N-Ar′ (Z = -OC6H4-4-CN) with 4-cyanophenoxide as the photochemical leaving group. Rate constants for the reaction with water (kw), azide ion (kaz) and hydroxide (kOH) were measured. The cation Ph-C≡N+-Ph is only 50-fold shorter lived in water compared to Ph-C≡N+-iPr (2); thus the effect of replacing an N-alkyl group with N-phenyl is modest. These two cations are also shown to have similar lifetimes to iminium analogs, e.g. Ph-CH=N+ (Me)-Ph. Thus, addition of water to analogous sp and sp2 hybridized systems occurs at a similar rate, and the increased steric access to the nitrilium plays at most a modest role. For the series where substituents in Ar′ were varied with Ar equal to phenyl, the Hammett plot for log kw correlated with σ, with ρ = - 1.4. For the series where Ar was varied, the data correlated much better with σ+, although ρ+ was only -0.6. This remarkably small effect of substituents in Ar constrasts with the effects seen in benzylic carbocations, but is consistent with the nitrilium structure, with most of the positive charge located on the nitrogen. Rate constant ratios kaz:kw, including the N-alkylnitrilium ion 2, are constant at ~104, with values of kaz well below the diffusion limit, even for the most reactive nitrilium ions. This is very different behaviour from that of carbocations and arylnitrenium ions of similar lifetimes in water. For these cations the rate constants kaz would be at or at least approaching the diffusion limit.
- Ruane, Patrick H.,Ahmed, Abid R.,McClelland, Robert A.
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p. 312 - 317
(2007/10/03)
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- Syntheses and basicity of 4-(N,N-dimethylamino)-2-arylquinazolines
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The reaction of substituted N-phenylbenzimidoyl chlorides with N,N-dimethylcyanamide in the presence of titanium tetrachloride has yielded seven 4-(N,N-dimethylamino)-2-arylquinazolines substituted on the phenyl ring with electron donating or withdrawing groups. pKa values have been determined for these compounds and analyzed in conjunction with the Hammertt σ constants to observe the influence of these phenyl substituents upon the basicity of 4-(N,N-dimemylamino)-2-arylquinazolines. The σ value, single crystal X-ray analysis and 15N-nmr spectra give evidence about the preferential site of protonation in such systems.
- Zielinski, Wojciech,Kudelko, Agnieszka,Holt, Elizabeth M.
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p. 1201 - 1209
(2007/10/03)
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- N'-Substituted N-Acyl- and N-Imidoyl-thioureas: Preparation and Conversion of N',N'-Disubstituted Compounds into 2-(N,N-Disubstituted Amino)thiazol-5-yl Ketones
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Known methods were developed to give convenient general procedures for preparing N-acyl-N'-mono- and -N',N'-disubstituted thioureas from acid chlorides, and related N-imidoyl thioureas from imidoyl chlorides.In the products from three acid chlorides and ammonium thiocyanate the acyl isothiocyanates did not appear to be accompained by the isomeric thiocyanates.Treatment of N-(anilino)benzylidene-N',N'-disubstituted thioures with chloroacetone in the presence of triethylamine leads to 5-acetyl-4-phenyl-2-(N,N-disubstituted amino)thiazoles.In contrast, the corresponding N-benzoyl thioureas form only small amounts of these compounds; the main products are the 5-benzoyl-4-methyl isomers, and this unexpected outcome requires a revision of the literature.It is thought that formation of the 5-benzoyl-4-methylthiazoles involves N-C(4) fission of a cyclic intermediate to give an open-chain intermediate in which nucleophilic attack can occur at either the acetyl or the benzoyl group.One of the latter intermediates was generated directly from 2-acetyl-2-bromoacetophenone and N-methyl-N-phenylthiourea, and found to give the 5-benzoyl-4-methyl- and 5-acetyl-4-phenyl-thiazoles as the major and minor products, respectively.
- Brindley, Jocelyn C.,Caldwell, Jennifer M.,Meakins, G. Denis,Plackett, Simon J.,Price, Susan J.
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p. 1153 - 1158
(2007/10/02)
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