- NaBH4-TMEDA and a palladium catalyst as efficient regio- and chemoselective system for the hydrodehalogenation of halogenated heterocycles
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The pair NaBH4-TMEDA as hydride source and a palladium catalyst in THF prove to be an efficient system for the hydrodehalogenation of halogenated heterocycles with one or more heteroatoms. In general, Pd(OAc) 2-PPh3 rapidly hydrodehalogenates reactive halo-heterocycles such as bromo-pyridines, -quinolines, -thiophenes, -indoles, -imidazoles, etc., at room temperature in very good yields, whereas in most cases PdCl2(dppf) reduces less reactive halides such as chloro-pyridines, -quinolines, -pyrimidines and bromo-indoles, -benzofurans, etc. Moreover, PdCl2(tbpf) shows to be even more active removing the 2- and 5-chlorine from both thiophene and thiazole rings. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene and nitrile substituents. Moreover, with a proper selection of the catalyst it is also possible to obtain a good control in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.
- Chelucci, Giorgio,Figus, Susanna
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p. 191 - 209
(2014/07/21)
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- Exploring the orthosteric binding site of the γ-aminobutyric acid type a receptor using 4-(Piperidin-4-yl)-1-hydroxypyrazoles 3- or 5-imidazolyl substituted: Design, synthesis, and pharmacological evaluation
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A series of 4-(piperidin-4-yl)-1-hydroxypyrazole (4-PHP) 3- or 5-imidazolyl substituted analogues have been designed, synthesized, and characterized pharmacologically. All analogues showed binding affinities in the low micro- to low nanomolar range at nat
- Krall, Jacob,Jensen, Claus H.,S?rensen, Troels E.,Nielsen, Birgitte,Jensen, Anders A.,Sander, Tommy,Balle, Thomas,Fr?lund, Bente
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supporting information
p. 6536 - 6540
(2013/09/23)
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- A general, practical palladium-catalyzed cyanation of (hetero)aryl chlorides and bromides
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Playing it safe: The nontoxic cyanide source K4[Fe(CN) 6]×3 H2O can be used for the cyanation of (hetero)aryl halides. The application of palladacycle catalysts prevents poisoning during catalyst formation, thereby allowing for low catalyst loadings, fast reaction times, and wide heterocyclic substrate scope.
- Senecal, Todd D.,Shu, Wei,Buchwald, Stephen L.
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supporting information
p. 10035 - 10039
(2013/10/01)
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- Room-temperature hydrodehalogenation of halogenated heteropentalenes with one or two heteroatoms
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The pair NaBH4-TMEDA as a hydride source and catalytic PdCl 2(dppf) in THF prove to be an efficient system for the hydrodehalogenation of bromo(chloro)-heteropentalenes with one or two heteroatoms, while Pd(OAc)2/PPh3 is able to reduce reactive haloheteropentalenes, and PdCl2(tbpf) allows the removal of the 2-chlorine from a thiophene ring. The reaction conditions tolerate various functional groups, allowing highly chemoselective reactions in the presence of halide, ester, alkyne, alkene, and nitrile substituents and also showing good efficiency in the regioselective hydrodehalogenation of a variety of polyhalogenated substrates.
- Chelucci, Giorgio,Baldino, Salvatore,Ruiu, Andrea
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p. 9921 - 9925,5
(2012/12/12)
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- Novel and potent 3-(2,3-dichlorophenyl)-4-(benzyl)-4H-1,2,4-triazole P2X7 antagonists
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Structure-activity relationship (SAR) studies were conducted around early tetrazole-based leads 3 and 4. Replacements for the tetrazole core were investigated and the pendant benzyl substitution was reoptimized with a triazole isostere. Triazole-based P2X
- Carroll, William A.,Kalvin, Douglas M.,Perez Medrano, Arturo,Florjancic, Alan S.,Wang, Ying,Donnelly-Roberts, Diana L.,Namovic, Marian T.,Grayson, George,Honore, Prisca,Jarvis, Michael F.
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p. 4044 - 4048
(2008/02/08)
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- Alkylation, Acylation and Silylation of Azoles
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Performing alkylation, acylation and silylation reactions in separate deprotonation and nucleophilic displacement steps allows for better control of reaction conditions and facilitates problem handling in these processes.In the alkylation of azoles the alkylating agents and solvents possess individual reaction capabilities which seem to be approximately additive.Monoalkylation occurs if the sum of the normalized reaction potentials is equal or larger than the pKa value of the azole.Dialkylation is avoided by keeping the sum of the normalized reaction potentials below the pKa value of the alkylazole.The applicability of these principles is demonstrated by the development of effective procedures for the methylation, benzylation, acetylation, methoxycarbonylation and trimethylsilylation of azoles.
- Begtrup, Mikael,Larsen, Peter
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p. 1050 - 1057
(2007/10/02)
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- Azoles. Part 6. A Convenient Synthesis of Polysubstituted Imidazoles from 1-Protected 2,4,5-Tribromoimidazoles
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Starting from 1-benzyl-2,4,5-tribromoimidazole 'one-pot' methods are described for the synthesis of 1-benzyl-4,5-dibromo-2-methylthioimidazole (1) (72percent), 1-benzyl-4-bromo-2,5-bis(methylthio)imidazole (3) (72percent), 1-benzyl-2,4,5-tris(methylthio)i
- Iddon, Brian,Khan, Nazir
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p. 1453 - 1456
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF 4(5)-MONO-, 4,5-DI-, AND 2,4,5-TRI-SUBSTITUTED IMIDAZOLES
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A procedure is described for the stepwise introduction of substituents (hydrogen included) into the imidazole ring by FGI of the bromine atoms in 1-protected 2,4,5-tribromo-imidazoles in the order 2-5-4 using halogen-metal exchange techniques.
- Iddon, Brian,Khan, Nazir
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p. 1635 - 1638
(2007/10/02)
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