- Three chloro(trifluoromethyl)pyridines as model substrates for regioexhaustive functionalization
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As a further test of the concept of regioexhaustive functionalization, 2-chloro-6-(trifluoromethyl)pyridine, 2-chloro-5-(trifluoromethyl)pyridine and 3-chloro-4-(trifluoromethyl)-pyridine were each converted into the three possible carboxylic acids 2, 4, 6, 8, 10, 12, 16, 17 and 20. This was achieved by employing several, but not all of the organometallic "tool-box methods": transformation of a more basic organometallic species into a less basic isomer by transmetalation-equilibration, site discriminating deprotonation with lithium N,N-diisopropylamide or lithium 2,2,6,6- tetramethylpiperidide, regio-divergent iodine migration and steric screening of acidic positions by a bulky trialkylsilyl group. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Cottet, Fabrice,Schlosser, Manfred
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p. 3793 - 3798
(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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- New strategies in the synthesis of regioselectively trifluoromethyl- and trifluoromethoxy-substituted arenes as building blocks for biologically active molecules
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Regioisomerically pure trifluoromethyl- and trifluoromethoxy-substituted aromatic and heteroaromatic aldehydes and carboxylic acids are valuable building blocks for the synthesis of biologically active molecules. They have been prepared by employing moder
- Leconte, Stephane,Ruzziconi, Renzo
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p. 167 - 172
(2007/10/03)
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