- Synthesis and spectroscopic characterization of group 4 post-metallocenes bearing (σ-aryl)-2-phenolate-6-pyridyl and -isoquinolinyl auxiliaries
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A new series of group 4 bis(benzyl) complexes supported by (σ-aryl)-2-phenolate-6-pyridyl [O,C,N] ligands have been prepared, and all derivatives have been characterized by multinuclear NMR spectroscopy. In the 1H NMR spectrum of the Ti derivative where [N] = (ortho-F)-substituted isoquinolinyl, one of the two CH2 resonances is observed as a doublet of doublets (collapsing to a normal d upon 19F-decoupling), whereas the [1H,19F]-HMQC correlation spectrum reveals a strong crosspeak for this dd resonance only, thus indicating the presence of intramolecular C-H·F-C interactions. [1H,19F]-HMBC experiments have been performed which reveal a significant scalar component for this coupling and confirm that the interactions are genuine. The contrasting NMR spectral patterns for the (ortho-F)-pyridyl Hf analogue, which exhibits two sets of non-identical doublet of doublets for the methylene resonances, have been rationalized. The activities of the isoquinolinyl-based Ti-[O,C,N] catalysts for ethylene polymerization are superior to those of pyridyl-based congeners.
- Lo, Jerry C.Y.,So, Loi-Chi,Chan, Michael C.W.
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supporting information
p. 15905 - 15913
(2015/09/15)
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- Efficient and scalable synthesis of pyridine sulfonamides
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Short-step and scalable transformations from 2,6-dibromopyridine to 6-bromopyridine-2-sulfonamide by means of halogen-metal exchange and subsequent reaction with sulfuryl chloride followed by amidation are established. Application of the method for the synthesis of various pyridine sulfonamides is also described. Georg Thieme Verlag Stuttgart - New York.
- Emura, Takashi,Yoshino, Hitoshi,Tachibana, Kazutaka,Shiraishi, Takuya,Honma, Akie,Mizutani, Akemi,Muraoka, Terushige
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experimental part
p. 1117 - 1120
(2011/06/20)
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- TMSCH2Li-LiDMAE: a new nonnucleophilic reagent for C-2 lithiation of halopyridines
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A new superbasic reagent has been discovered by combining TMSCH2Li and LiDMAE in hexane. This reagent was found highly efficient for the C-2 lithiation of sensitive chloro- and fluoropyridines. The metallation occurred chemo- and regioselectively at 0 °C avoiding the nucleophilic addition or substrate degradation commonly obtained with other alkyllithiums even at lower temperatures.
- Doudouh, Abdelatif,Gros, Philippe C.,Fort, Yves,Woltermann, Christopher
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p. 6166 - 6171
(2007/10/03)
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- Synthesis of novel halopyridinylboronic acids and esters. Part 4: Halopyridin-2-yl-boronic acids and esters are stable, crystalline partners for classical Suzuki cross-coupling
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This paper describes some methods for the synthesis and the isolation of novel 5 or 6-halopyridin-2-yl-boronic acids and esters 3, 4, 7. These compounds are prepared via a regioselective halogen-metal exchange using n-butyllithium and subsequent quenching with triisopropylborate starting from appropriate dihalopyridines. All substrates studied to date provided a single regioisomeric boronic acid or ester product. Additionally, these compounds have been found to undergo Pd-catalysed coupling with arylhalides and authorise a strategy to produce new pyridines libraries.
- Bouillon, Alexandre,Lancelot, Jean-Charles,Santos, Jana Sopkova De Oliveira,Collot, Valérie,Bovy, Philipppe R.,Rault, Sylvain
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p. 10043 - 10049
(2007/10/03)
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- Trifluoromethyl-substituted pyridines through displacement of iodine by in situ generated (trifluoromethyl)copper
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A literature method reported for iodobenzene and congeners was successfully extended to the pyridine series. 2-Iodopyridines can be converted into 2-(trifluoromethyl)pyridines almost quantitatively. In contrast, yields are moderate at best if 3- and 4-iodopyridines or 2-bromopyridines are used as the starting materials. WILEY-VCH Verlag GmbH 2002.
- Cottet, Fabrice,Schlosser, Manfred
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p. 327 - 330
(2007/10/03)
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- Unusual C-6 lithiation of 2-chloropyridine-mediated by BuLi-Me2N(CH2)2OLi. New access to 6-functional-2-chloropyridines and chloro-bis-heterocycles
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Formula Presented The reaction of 2-chloropyridine with alkylithium generally results in nucleophilic addition leading to the loss of chlorine atom while exclusive directed ortho metalation is obtained using LDA. Herein it is shown that the BuLi-Me2
- Choppin, Sabine,Gros, Philippe,Fort, Yves
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p. 803 - 805
(2007/10/03)
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- Substituent Effect on the Chlorination of 2-Alkoxypyridines to give 2-Chloropyridines under Vilsmeier-Haack Conditions
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Various substituted 2-alkoxypyridines were converted into the corresponding 2-chloropyridines in 28-91% yields by use of POCl3 and DMF, in which the methyl, halogen, ester and nitro groups displayed an activating effect; in contrast, an amino group exhibited a deactivating effect.
- Lai, Long-Li,Lin, Pen-Yuan,Wang, Jy-Shih,Hwu, Jih Ru,Shiao, Min-Jen,Tsay, Shwu-Chen
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p. 194 - 195
(2007/10/03)
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- A Convenient Synthesis of Halogenated 2-Chloropyridines by Transformation of Halogenated 2-Methoxypyridines under Vilsmeier-Haack Conditions
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Several halogenated 2-chloropyridines 2a-2h were conveniently synthesized by transformation of halogenated 2-methoxypyridines 1a-1h under Vilsmeier-Haack conditions in a yield of 50-71percent.
- Shiao, Min-Jen,Shyu, Li-Ming,Tarng, Kai-Yih,Ma, Ying-Tsun
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p. 2971 - 2977
(2007/10/02)
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