- The palladium catalysed biaryl cross-coupling of pyridazine triflates
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The scope of trifluoromethanesulfonic acid 6-methyl-pyridazine-3-yl ester as a coupling partner for biaryl synthesis via palladium catalysed Suzuki and Stille coupling conditions is reported.
- Aldous,Bower,Moorcroft,Todd
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- Inherent vs Apparent Chemoselectivity in the Kumada-Corriu Cross-Coupling Reaction
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The Kumada-Corriu reaction is a powerful tool for C-C bond formation, but is seldom utilized due to perceived chemoselectivity issues. Herein, we demonstrate that high-yielding couplings can occur in the presence of many electrophilic and heterocyclic functional groups. Our strategy is mechanically based, matching oxidative addition rates with the rate of syringe pump addition of the Grignard reagent. The mechanistic reason for the effectiveness of this strategy is uncovered by continuous-infusion ESI-MS studies.
- Hua, Xiye,Masson-Makdissi, Jeanne,Sullivan, Ryan J.,Newman, Stephen G.
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supporting information
p. 5312 - 5315
(2016/11/02)
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- Thulium Triflate Catalyzed Hydration of 2-Substituted 4-Alkynones
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We report on a facile synthetic route for the preparation of substituted 1,4-diketones by thulium triflate mediated hydration of substituted 4-alkynones in MeNO2 at 25 °C for five hours. The products were obtained in moderate to high yields.
- Chang,Cheng
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supporting information
p. 1931 - 1935
(2016/08/09)
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- In(OTf)3-mediated synthesis of substituted pyridazines
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In(OTf)3 (4c)-mediated one-pot (4+2) cyclocondensation of γ-alkynones 3 with N2H4(aq) in dioxane affords substituted pyridazines 5 in good yields via a sequential desulfonative or dehydrogenative aromatization. The facile
- Chang, Meng-Yang,Lu, Yi-Ju,Cheng, Yu-Chieh
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p. 6840 - 6845
(2015/08/24)
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- From N-sulfonyl,C-homoallyl-hydrazones to pyrazole and pyridazine (N 2)-heterocycles: The ultimate aromatization process
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Isomeric six- and five-membered (N2)-aromatics, 6-methylpyridazines and 5-vinylpyrazoles, which energetic topological aromaticity is comparable to that of benzene, are shown to be efficiently produced by sequential isomerization-elimination processes from the corresponding 6-methylidene-1,4,5,6-tetrahydropyridazines and 5-vinylpyrazolines, respectively. The latter precursors are available from the same N-sulfonyl,C-homoallyl-hydrazone substrates by a suitable choice of previously reported conditions for Pd-catalyzed CH-oxidative C,N-ring closing processes. The generality of these cyclization, isomerization, and aromatization reactions, for which detailed mechanisms are proposed, provides a systematic access to wide ranges of 3,4,6-trisubstituted 6-methyl-1,4-dihydropyridazines and 6-methylpyridazines, and their 3,4,5-trisubstituted 5-vinylpyrazole isomers.
- Mboyi, Cleve Dionel,Duhayon, Carine,Canac, Yves,Chauvin, Remi
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p. 4957 - 4968
(2014/07/07)
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- Palladium-catalyzed cross-coupling reaction of functionalized aryl- and heteroarylbismuthanes with 2-halo(or 2-Triflyl)azines and -diazines
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The palladium-catalyzed cross-coupling of highly functionalized organobismuthanes with 2-halo(or 2-triflyl)pyridines, -pyrimidines, -pyrazines, and -pyridazines is reported. The reaction tolerates numerous functional groups, including aldehydes. The synthesis of a shelf-stable (formylphenyl)bismuth reagent and its use in a cross-coupling reaction is also described. The palladium-catalyzed cross-coupling of highly functionalized organobismuthanes with 2-halo(or 2-triflyl)pyridines, -pyrimidines, -pyrazines, and -pyridazines is reported. The reaction tolerates numerous functional groups, including aldehydes. The synthesis of a shelf-stable (formylphenyl)bismuth reagent and its use in cross-coupling reactions is also described. Copyright
- Petiot, Pauline,Gagnon, Alexandre
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supporting information
p. 5282 - 5289
(2013/09/02)
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- Cushing's syndrome: Development of highly potent and selective CYP11B1 inhibitors of the (pyridylmethyl)pyridine type
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Potent and selective CYP11B1 inhibitors could be promising therapeutics for the treatment of Cushing's syndrome. Optimization of Ref 1 (5-((1H-imidazol-1- yl)methyl)-2-phenylpyridine) led to compound 44 (5-((5-methylpyridin-3-yl) methyl)-2-phenylpyridine) with a 50-fold improved IC50 value of 2 nM toward human CYP11B1 and an enhanced inhibition of the rat enzyme (IC 50 = 2440 nM) compared to Ref 1 (IC50 > 10000 nM). Furthermore, selectivities over CYP11B2, CYP17, and CYP19 were observed, as well as satisfying metabolic stability not only in human and rat plasma but also in liver S9 fraction. Investigation of cytotoxicity and inhibition of hepatic CYP2A6 and CYP3A4 showed that 44 fulfills first safety criteria and can be considered for further in vivo evaluation in rats.
- Emmerich, Juliette,Hu, Qingzhong,Hanke, Nina,Hartmann, Rolf W.
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supporting information
p. 6022 - 6032
(2013/09/02)
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- Unexpected C-C bond cleavage: A route to 3,6-diarylpyridazines and 6-arylpyridazin-3-ones from 1,3-dicarbonyl compounds and methyl ketones
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An unexpected C-C bond cleavage has been revealed in the absence of metal. This observation has been exploited to develop an efficient approach toward 3,6-diarylpyridazines and 6-arylpyridazin-3-ones from simple and commercially available 1,3-dicarbonyl compounds and methyl ketones.
- Gao, Qinghe,Zhu, Yanping,Lian, Mi,Liu, Meicai,Yuan, Jingjing,Wu, Anxin,Yin, Guodong
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p. 9865 - 9870,6
(2012/12/12)
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- Preparation of functionalized aryl- and heteroarylpyridazines by nickel-catalyzed electrochemical cross-coupling reactions
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(Chemical Equation Presented) A general efficient electrochemical method for the preparation of aryl- and heteroarylpyridazines in a nickel-catalyzed cross-coupling reaction of 3-chloro-6-methoxypyridazine and 3-chloro-6- methylpyridazine with a range of functionalized aryl or heteroaryl halides is reported.
- Sengmany, Stephane,Leonel, Eric,Polissaint, Frantz,Nedelec, Jean-Yves,Pipelier, Muriel,Thobie-Gautier, Christine,Dubreuil, Didier
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p. 5631 - 5636
(2008/02/09)
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- Synthesis and reactions of haloazodienes. A new and general synthesis of substituted pyridazines
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The reaction of dihalohydrazones with Hunig's base gives 1-carbethoxy-3-phenyl-4-haloazodienes in-situ, which were found to combine with a variety of electron rich olefins to yield halo-substituted tetrahydropynidazines. These haloazodiene cyclizations are best characterized as inverse electron demand, 4 + 2 hetero Diels-Alder reactions that maintain a high degree of regio- and stereochemical control. The chloro-substituted tetrahydropyridazines that are formed give high yields of substituted pyridazines upon treatment with base. The sequence of a chloroazodiene cyclization to a tetrahydropyridazine followed by an aromatization constitutes a new and general synthesis of substituted pyridazines. In contrast to the haloazodiene cyclizations, the novel cyclization reactions of the in-situ generated 1-carbethoxy-3-phenyl-4,4-dichloroazodiene were found to give N-aminopyrroles and pyridazines when combined with acyclic enamines. However, reactions with cyclic enamines gave the N-aminopyrroles, pyridazines, a dihydropyridazine as products as well as the noncyclized enamine intermediates. The noncyclized enamines could be converted to the N-aminopyrroles simply upon heating to higher temperatures, indicating a stepwise mechanism. The examples described here are the first reported cyclization reactions for dichloroazodienes.
- South, Michael S.,Jakuboski, Terri L.,Westmeyer, Mark D.,Daniel
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p. 8921 - 8934
(2007/10/03)
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- Synthesis and reactions of chloroazodienes. A new and general synthesis of pyridazines
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The reaction of dichlorohydrazones with Hunig's base gives 4-chloroazodienes, which were found to combine with a variety of electron rich olefins to yield chloro-substituted tetrahydropyridazines. These chloroazodiene cyclizations are best characterized a
- South, Michael S.,Jakuboski, Terri L.
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p. 5703 - 5706
(2007/10/02)
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- A NOVEL CYCLIZATION REACTION OF OXIDODIAZOALKANES: FORMATION OF PYRAZOLES AND PYRIDAZINES
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The thermal decomposition of dialkali metal salts of β- and γ-hydroxyketone tosylhydrazones in refluxing DME produced pyrazoles and pyridazines, respectively.
- Harada, Toshiro,Akiba, Eiji,Oku, Akira
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p. 655 - 656
(2007/10/02)
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- 1,4,5,6-Tetrahydropyridazines by Cycloaddition of Enol Ethers to Azoalkenes and their Aromatisation to Pyridazines.
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Transient azoalkenes generated from acyl- and 4-tolylsulphonyl-hydrazones of α-haloacetophenones and of ethyl bromopyruvate are intercepted by cycloaddition to enol ethers, giving 6-alkoxy-1,4,5,6-tetrahydropyridazines (2). 6-Alkoxy-3-aryl-1,4,5,6-tetrahydropyridazines are converted by reaction with sodium ethoxide into 3-arylpyridazines (3).
- Clarke, Simon J.,Gilchrist, Thomas L.
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p. 3371 - 3389
(2007/10/02)
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