- A concise and efficient synthesis of tetrahydroquinoline alkaloids using the phase transfer mediated Wittig olefination reaction
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The present study describes the total synthesis of 1,2,3,4-tetrahydroquinoline alkaloids (±)-galipinine, (±)-cuspareine, (±)-galipeine and (±)-angustureine, in three steps and high yields (78%, 76%, 74%, and 66%, respectively) from common aldehyde and the ylide respectives. The key step of this approach is based on an unusual Wittig reaction by using the phase transfer medium (aq. NaOH/CH2Cl2 1:1 or t-BuOK/t-BuOH/CH2Cl2 1:1), affording olefinic intermediates in high yields.
- Diaz-Mu?oz, Gaspar,Isidorio, Raquel Geralda,Miranda, Izabel Luzia,de Souza Dias, Gabriel Nunes,Diaz, Marisa Alves Nogueira
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- Manganese catalyzed C-alkylation of methylN-heteroarenes with primary alcohols
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C-Alkylations of nine different classes of methyl-substitutedN-heteroarenes, including quinolines, quinoxalines, benzimidazoles, benzoxazoles, pyrazines, pyrimidines, pyridazines, pyridines, and triazines are disclosed. A bench stable earth-abundant Mn(i)-complex catalyzed the chemoselective hydrogen-transfer reaction utilizing a diverse range of primary alcohols as the non-fossil fuel-derived carbon source. The diversifiedN-heteroarenes (41 examples) were isolated in high yields and selectivities. Water is produced as the sole byproduct, making the protocol environmentally benign.
- Jana, Akash,Kumar, Amol,Maji, Biplab
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supporting information
p. 3026 - 3029
(2021/03/29)
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- Boric acid catalyzed chemoselective reduction of quinolines
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Boric acid promoted transfer hydrogenation of substituted quinolines to synthetically versatile 1,2,3,4-tetrahydroquinolines (1,2,3,4-THQs) was described under mild reaction conditions using a Hantzsch ester as a mild organic hydrogen source. This methodology is practical and efficient, where isolated yields are excellent and reducible functional groups are well tolerated in the N-heteroarene moiety. The reaction parameters and tentative mechanistic pathways are demonstrated by various control experiments and NMR studies. The present work can also be scaled up to obtain gram quantities and the utility of the developed process is illustrated by the transformation of 1,2,3,4-THQs into a series of biologically important molecules including the antiarrhythmic drug nicainoprol.
- Adhikari, Priyanka,Bhattacharyya, Dipanjan,Das, Animesh,Konwar, Monuranjan,Nandi, Sekhar,Sarmah, Bikash Kumar
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supporting information
p. 1214 - 1220
(2020/02/22)
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- One-Pot, Tandem Wittig Hydrogenation: Formal C(sp3)-C(sp3) Bond Formation with Extensive Scope
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A one-pot, tandem Wittig hydrogenation of aldehydes with stabilized ylides is reported, representing a formal C(sp3)-C(sp3) bond construction. The tandem reaction operates under mild conditions, is high yielding, and is broad in scope. Chemoselectivity for olefin reduction is observed, and the methodology is demonstrated in the synthesis of lapatinib analogues and a formal synthesis of (±)-cuspareine. Early insights suggest that the chemoselectivity observed in the reduction step is due to partial poisoning of the catalyst, after step one, thus adding to the power of the one-pot procedure.
- Devlin, Rory,Jones, David J.,Mcglacken, Gerard P.
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supporting information
p. 5223 - 5228
(2020/07/14)
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- Synergistic Chemo/Biocatalytic Synthesis of Alkaloidal Tetrahydroquinolines
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The power of complementary chemocatalytic and biocatalytic transformations is demonstrated in the asymmetric synthesis of 2-substituted tetrahydroquinolines. A series of racemic tetrahydroquinolines were synthesized through a convergent one-pot Rh(I)-catalyzed addition/condensation sequence of alkyl vinyl ketones and aminophenylboronic acids. The resulting tetrahydroquinolines were thereafter shown to be substrates for the flavin-dependent enzyme cyclohexylamine oxidase, and preparative-scale deracemizations have been demonstrated on these high-value targets.
- Cosgrove, Sebastian C.,Hussain, Shahed,Turner, Nicholas J.,Marsden, Stephen P.
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p. 5570 - 5573
(2018/05/25)
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- QUINOLINE DERIVATIVES AS ANTI-CANCER AGENTS
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Quinoline derivatives showing anticancer activities against cancer cell lines of hepatocellular carcinoma (Hep3B), lung carcinoma (A549), esophageal squamous cell carcinoma (HKESC-1, HKESC-4 and KYSE150). The quinoline derivatives have a backbone structure of the following formulas:
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Page/Page column 12
(2012/07/13)
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- Catalytic hydrogenation with frustrated lewis pairs: Selectivity achieved by size-exclusion design of lewis acids
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Catalytic hydrogenation that utilizes frustrated Lewis pair (FLP) catalysts is a subject of growing interest because such catalysts offer a unique opportunity for the development of transition-metal-free hydrogenations. The aim of our recent efforts is to further increase the functional-group tolerance and chemoselectivity of FLP catalysts by means of size-exclusion catalyst design. Given that hydrogen molecule is the smallest molecule, our modified Lewis acids feature a highly shielded boron center that still allows the cleavage of the hydrogen but avoids undesirable FLP reactivity by simple physical constraint. As a result, greater latitude in substrate scope can be achieved, as exemplified by the chemoselective reduction of α,β-unsaturated imines, ketones, and quinolines. In addition to synthetic aspects, detailed NMR spectroscopic, DFT, and 2H isotopic labeling studies were performed to gain further mechanistic insight into FLP hydrogenation. Copyright
- Eroes, Gabor,Nagy, Krisztina,Mehdi, Hasan,Papai, Imre,Nagy, Peter,Kiraly, Peter,Tarkanyi, Gabor,Soos, Tibor
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p. 574 - 585
(2012/03/08)
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- Synthesis of alkaloids of Galipea officinalis by alkylation of an α-amino nitrile
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A new synthetic approach directed towards the synthesis of naturally occurring 2-alkyl-tetrahydroquinolines is described. The C-C bonds in the α position relative to the nitrogen atom were formed by the reversal of the polarity of the C=N bond of α-amino nitrile 6, which was prepared electrochemically from 1-(phenylethyl)-tetrahydroquinoline. A NaBH 4-mediated reductive decyanation process furnished benzylic amines 16a-d as mixtures of diastereomers (50-60% de). The catalytic hydrogenolysis of these amines was performed in the presence of Pearlman's catalyst to give the tetrahydroquinolines 17a-d in yields ranging from 70% to 95%. Methylation of the free nitrogen atom afforded the title compounds 1-4 in 70-90% yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Shahane, Saurabh,Louafi, Fadila,Moreau, Julie,Hurvois, Jean-Pierre,Renaud, Jean-Luc,Van De Weghe, Pierre,Roisnel, Thierry
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experimental part
p. 4622 - 4631
(2009/05/07)
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- An efficient catalytic system for the hydrogenation of quinolines
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A new catalytic system ([Ru(p-cymene)Cl2]2/I2) has been developed for the hydrogenation of quinoline derivatives with high reactivity. For the 2-methyl-quinoline, the hydrogenation reaction can proceed smoothly at an S/C of 20,000/1 with complete conversion. The iodine additive is important for the reactivity.
- Lu, Sheng-Mei,Han, Xiu-Wen,Zhou, Yong-Gui
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p. 3065 - 3069
(2008/02/02)
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- A SIMPLE REGIOSELECTIVE PREPARATION OF 2- OR 3-SUBSTITUTED QUINOLINE DERIVATIVES VIA DIALKYLQUINOLYLBORANES
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Various quinoline derivatives possessing a substituent at the 2- or 3-position were prepared by the reaction of dialkylquinolylboranes and organic bromides in the presence of a palladium catalyst.
- Ishikura, Minoru,Oda, Izumi,Terashima, Masanao
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p. 2375 - 2386
(2007/10/02)
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