- Copper-catalyzed trifluoromethylation of alkoxypyridine derivatives
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The trifluoromethylation of aromatic and heteroaromatic cores has attracted considerable interest in recent years due to its pharmacological relevance. We studied the extension of a simple copper-catalyzed trifluoromethylation protocol to alkoxy-substituted iodopyridines and their benzologs. The trifluoromethylation proceeded smoothly in all cases, and the desired compounds were isolated and characterized. In the trifluoromethylation of 3-iodo-4-methoxyquinoline, we observed a concomitant O-N methyl migration, resulting in the trifluoromethylated quinolone as a product. Overall, the described procedure should facilitate the broader use of copper-catalyzed trifluoromethylation in medicinal chemistry.
- Farkas, Emese,Gyorfi, Nandor,Kotschy, Andras,Nemet, Norbert,Novak, Zoltan,Weber, Csaba
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- Deprotometalation of substituted pyridines and regioselectivity-computed CH acidity relationships
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A series of methoxy- and fluoro-pyridines have been deprotometalated in tetrahydrofuran at room temperature by using a mixed lithium-zinc combination obtained from ZnCl2·TMEDA (TMEDA=N,N,N′,N′-tetramethylethylenediamine) and LiTMP (TMP=2,2,6,6-tetramethylpiperidino) in a 1:3 ratio, and the metalated species intercepted by iodine. Efficient functionalization at the 3 position was observed from 4-methoxy, 2-methoxy, 2,6-dimethoxy, 2-fluoro and 2,6-difluoropyridine, and at the 4 position from 3-methoxy and 2,3-dimethoxypyridine. Interestingly, clean dideprotonation was noted from 3-fluoropyridine (at C2 and C4) and 2,6-difluoropyridine (at C3 and C5). The obtained regioselectivities have been discussed in light of the CH acidities of the substrates, determined both in the gas phase (DFT B3LYP and G3MP2B3 levels) and in THF solution. In the case of methoxypyridines, the pKa values have also been calculated for complexes with LiCl and LiTMP.
- Hedidi, Madani,Bentabed-Ababsa, Ghenia,Derdour, A?cha,Halauko, Yury S.,Ivashkevich, Oleg A.,Matulis, Vadim E.,Chevallier, Floris,Roisnel, Thierry,Dorcet, Vincent,Mongin, Florence
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p. 2196 - 2205
(2016/04/09)
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- Potassium-alkyl magnesiates: Synthesis, structures and Mg-H exchange applications of aromatic and heterocyclic substrates
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Using structurally well-defined dipotassium-tetra(alkyl)magnesiates, a new straightforward methodology to promote regioselective Mg-H exchange reactions of a wide range of aromatic and heteroaromatic substrates is disclosed. Contacted ion pair intermediates are likely to be involved, with K being the key to facilitate the magnesiation processes. This journal is
- Baillie, Sharon E.,Bluemke, Tobias D.,Clegg, William,Kennedy, Alan R.,Klett, Jan,Russo, Luca,De Tullio, Marco,Hevia, Eva
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supporting information
p. 12859 - 12862
(2014/12/11)
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- Computed CH acidity of biaryl compounds and their deprotonative metalation by using a mixed lithium/Zinc-TMP base
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With the aim of synthesizing biaryl compounds, several aromatic iodides were prepared by the deprotonative metalation of methoxybenzenes, 3-substituted naphthalenes, isoquinoline, and methoxypyridines by using a mixed lithium/zinc-TMP (TMP=2,2,6,6-tetramethylpiperidino) base and subsequent iodolysis. The halides thus obtained, as well as commercial compounds, were cross-coupled under palladium catalysis (e.g., Suzuki coupling with 2,4-dimethoxy-5-pyrimidylboronic acid) to afford various representative biaryl compounds. Deprotometalation of the latter compounds was performed by using the lithium/zinc-TMP base and evaluated by subsequent iodolysis. The outcome of these reactions has been discussed in light of the CH acidities of these substrates, as determined in THF solution by using the DFT B3LYP method. Except for in the presence of decidedly lower pKa values, the regioselectivities of the deprotometalation reactions tend to be governed by nearby coordinating atoms rather than by site acidities. In particular, azine and diazine nitrogen atoms have been shown to be efficient in inducing the reactions with the lithium/zinc-TMP base at adjacent sites (e.g., by using 1-(2-methoxyphenyl)isoquinoline, 4-(2,5-dimethoxyphenyl)-3-methoxypyridine, or 5-(2,5-dimethoxyphenyl)-2,4-dimethoxypyrimidine as the substrate), a behavior that has already been observed upon treatment with lithium amides under kinetic conditions. Finally, the iodinated biaryl derivatives were involved in palladium-catalyzed reactions. Copyright
- Kadiyala, Raghu Ram,Tilly, David,Nagaradja, Elisabeth,Roisnel, Thierry,Matulis, Vadim E.,Ivashkevich, Oleg A.,Halauko, Yury S.,Chevallier, Floris,Gros, Philippe C.,Mongin, Florence
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supporting information
p. 7944 - 7960
(2013/07/05)
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- Alkali-metal mediated zincation of N-heterocyclic substrates using the lithium zincate complex, (THF)Li(TMP)Zn(tBu)2 and applications in in situ cross coupling reactions
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This study investigates the ability of the mixed-metal reagent [Li(TMP)Zn(tBu)2] 1 to promote direct Zn-H exchange reactions (zincations) of a wide range of N-heterocyclic molecules. The generated metallated intermediates from these reactions are intercepted with I2 and some of them are also employed as precursors in Pd-catalysed Negishi cross-coupling applications. A comparison with recent precedents in metallation chemistry reveals that for some of these heterocycles, 1 allows improved conversions, under milder conditions and in certain cases, even gives unique regioselectivities.
- Blair, Victoria L.,Blakemore, David C.,Hay, Duncan,Hevia, Eva,Pryde, David C.
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supporting information; experimental part
p. 4590 - 4594
(2011/09/30)
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- New Synthesis of Orelline by Metalation of Methoxypyridines
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A new total synthesis in five steps of alkaloid Orelline is reported.The methodology involves metalation of methoxypyridines to afford 2-halo-3,4-dimethoxypyridine on which an homocoupling reaction is performed to build the 2,2'-bipyridyl structure of the
- Trecourt, Francois,Mallet, Marc,Mongin, Olivier,Gervais, Bruno,Queguiner, Guy
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p. 8373 - 8380
(2007/10/02)
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- N-acyldihydropyridones as synthetic intermediates. Synthesis of (±)-septicine and (±)-tylophorine
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The indolizidine alkaloids (±)-septicine and (±)-tylophorine were prepared from N-acyldihydropyridone 7 in five and six steps, respectively.
- Comins, Daniel L.,Morgan, Lawrence A.
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p. 5919 - 5922
(2007/10/02)
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