- Transition-metal-free decarboxylative halogenation of 2-picolinic acids with dihalomethane under oxygen conditions
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A convenient and efficient method for the synthesis of 2-halogen-substituted pyridines is described. The decarboxylative halogenation of 2-picolinic acids with dihalomethane proceeded smoothly via N-chlorocarbene intermediates to afford 2-halogen-substituted pyridines in satisfactory to excellent yields under transition-metal-free conditions. This new type of decarboxylative halogenation is operationally simple and exhibits high functional-group tolerance.
- Zhang, Xitao,Feng, Xiujuan,Zhang, Haixia,Yamamoto, Yoshinori,Bao, Ming
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supporting information
p. 5565 - 5570
(2019/10/22)
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- An improved method for the bromination of metalated haloarenes via lithium, zinc transmetalation: A convenient synthesis of 1,2-dibromoarenes
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A facile protocol for the synthesis of 1,2-dibromoarenes is described. A standard ortho-lithiation/bromination procedure, when applied to bromoarenes, resulted in poor yields of the corresponding 1,2-dibromoarenes (13-62% yield). However, transmetalation
- Menzel, Karsten,Fisher, Ethan L.,DiMichele, Lisa,Frantz, Doug E.,Nelson, Todd D.,Kress, Michael H.
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p. 2188 - 2191
(2007/10/03)
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- Recommendable routes to trifluoromethyl-substituted pyridine- and quinolinecarboxylic acids
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As part of a case study, rational strategies for the preparation of all ten 2-, 3-, or 4-pyridinecarboxylic acids and all nine 2-, 3-, 4-, or 8-quinolinecarboxylic acids bearing trifluoromethyl substituents at the 2-, 3-, or 4-position were elaborated. The trifluoromethyl group, if not already present in the precursor, was introduced either by the deoxygenative fluorination of suitable carboxylic acids with sulfur tetrafluoride or by the displacement of ring-bound bromine or iodine by trifluoromethylcopper generated in situ. The carboxy function was produced by treatment of organolithium or organomagnesium intermediates, products of halogen/metal or hydrogen/ metal permutation, with carbon dioxide. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Cottet, Fabrice,Marull, Marc,Lefebvre, Olivier,Schlosser, Manfred
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p. 1559 - 1568
(2007/10/03)
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- Synthesis of novel halopyridinylboronic acids and esters. Part 2: 2,4, or 5-Halopyridin-3-yl-boronic acids and esters
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This paper describes a general method for the synthesis and the isolation of novel 2,4, or 5-halopyridin-3-yl-boronic acids and esters 4, 7, 10, 13, 15. These compounds are prepared taking into account a regioselective halogen-metal exchange using nBuLi or a regioselective ortho-lithiation using lithium diisopropylamide and subsequent quenching with triisopropylborate starting from appropriate mono or dihalopyridines. All substrates studied to date provided a single regioisomeric boronic acid or ester product. Additionally, these compounds have been found to undergo Pb-catalyzed coupling with a range of arylhalides and authorize a strategy to produce new pyridines libraries.
- Bouillon, Alexandre,Lancelot, Jean-Charles,Collot, Valerie,Bovy, Philippe R.,Rault, Sylvain
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p. 3323 - 3328
(2007/10/03)
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