- 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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- Deprotonation of fluoro aromatics using lithium magnesates
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Activated fluoro aromatics are deprotonated using lithium magnesates. 3-Fluoropyridine was deprotonated on treatment with 1/3 equiv of Bu 3MgLi in THF at -10°C. The lithium arylmagnesate formed was either trapped with electrophiles or involved
- Awad, Ha?an,Mongin, Florence,Trécourt, Fran?ois,Quéguiner, Guy,Marsais, Francis,Blanco, Fernando,Abarca, Belén,Ballesteros, Rafael
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p. 6697 - 6701
(2007/10/03)
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- Heterocyclic compounds useful as oxido-squalene cyclase inhibitors
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This invention concerns heterocyclic derivatives of formula (I) which are useful in inhibiting oxido-squalene cyclase, processes for their preparation and pharmaceutical compositions containing them. The present invention is also concerned with heterocycl
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- Synthesis of 3-alkylfuropyridines via palladium-catalyzed cyclization of iodopyridinyl allyl ethers
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The palladium-catalyzed cyclization of iodopyridinyl allyl ethers derived from dihalopyridines and sodium allyl alkoxide provides furo[2,3-b]-pyridines, furo[3,2-c]pyridines, and furo[2,3-c]pyridines.
- Cho, Sung Yun,Kim, Sung Soo,Park, Kyung-Ho,Kang, Seung Kyu,Choi, Joong-Kwon,Hwang, Ki-Jun,Yum, Eul Kgun
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p. 1641 - 1652
(2007/10/03)
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- REGIOSELECTIVE ORTHO-LITHIATION OF HALOPYRIDINES. SYNTHESES OF ORTHO-DISUBSTITUTED PYRIDINES AND A CONVENIENT GENERATION OF 3,4-PYRIDYNE
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The regioselective ortho-lithiation of 3-chloro- (4), 3-fluoro- (7), 3-bromo- (10), 2-chloro- (22), and 4-chloropyridine (25) with lithium diisopropylamide affords, after quenching with various electrophiles, the corresponding ortho-disubstituted pyridine
- Gribble, Gordon W.,Saulnier, Mark G.
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p. 151 - 169
(2007/10/02)
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- Connection between metalation and cross-coupling strategies. A new convergent route to azacarbazoles
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New convergent synthesis of azacarbazoles through metalation, cross-coupling reaction and intramolecular substitution via (2-aminobenzene)boronic acid and ortho-fluoroiodopyridines.
- Rocca, Patrick,Marsais, Francis,Godard, Alain,Queguiner, Guy
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- Regioselective ortho lithiation of halopyridines
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Regioselective ortho lithiation of 2-, 3-, and 4-halopyridines is achieved with lithium diisopropylamide (-78°, tetrahydrofuran) to afford, upon quenching with electrophilic reagents, 2,3- and 3,4-disubstituted pyridines in good to excellent yield.
- Gribble, Gordon W.,Saulnier, Mark G.
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p. 4137 - 4140
(2007/10/02)
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