3295-64-5Relevant academic research and scientific papers
Homogeneous Catalytic Hydrogenation. 2. Selective Reduction of Polynuclear Heteroaromatic Compounds Catalyzed by Chlorotris(triphenylphosphine)rhodium(I)
Fish, Richard H.,Tan, John L.,Thormodsen, Arne D.
, p. 4500 - 4505 (1984)
The selective reduction of polynuclear heteroaromatic nitrogen compounds such as quinoline, 1, 5,6-benzoquinoline, 2, 7,8-benzoquinoline, 3, acridine, 4, phenanthridine, and in one case, a sulfur heterocyclic compound, benzothiophene, 6, with chlorotris(triphenylphosphine)rhodium(I), (Ph3P)3RhCl, provided under rather mild hydrogenation conditions the corresponding saturated nitrogen and sulfur heterocyclic analogues of the above-mentioned compounds in reasonable conversion rates and total percent yields.In addition, compounds that inhibit the initial rate of hydrogenation of 1 in the conversion to 1,2,3,4-tetrahydroquinoline, 10, include pyridine, 7, 3-methylpyridine, 8, and 10 itself.These results are indicative of electronic effects in these competitive hydrogenation reactions, while 2-methylpyridine, 9, slightly reduces the rate of hydrogenation of 1, implicating a steric effect at the metal center.It was also observed that substrate 6, indole, 11, pyrrole, 12, carbazole, 13, thiophene, 14, dibenzothiophene, 15, and p-cresol, 16, enhanced the initial rate of hydrogenation of 1 to 10 by an average factor of >1.5.The substitution of deuterium gas for hydrogen gas in the reduction of 1 provided information on the reversibility of the hydrogenation step, stereoselectivity in the reduction of the 3,4-double bond, and the implication of cyclometalation reactions which caused the exchange of H for D at the 8-position and possibly the 2-position.Similar deuteration data with compound 5 strengthened the concept of dehydrogenation in the hydrogenation step and in fact provided independent evidence for the facile dehydrogenation of 1,9,9,10-tetradeuterio-9,10-dihydrophenanthridine, 19, catalyzed by (Ph3P)3RhCl. 1H NMR and IR experiments also verify some of the postulated mechanistic aspects of these selective hydrogenation reactions.
Photocyclization of benzalcycloalkanone oximes. A photoannulation route to quinolines
Olsen
, p. 5235 - 5238 (1991)
Photolysis of benzalcycloalkanone oxime derivatives in acidic methanol produces quinoline derivatives in good yields. A three step quinoline annulation of cyclic ketones is described.
Mild and efficient copper-catalyzed oxidative cyclization of oximes with 2-aminobenzyl alcohols at room temperature: synthesis of polysubstituted quinolines
Liu, Yan-Yun,Wei, Yang,Huang, Zhi-Hui,Liu, Yilin
supporting information, p. 659 - 666 (2021/02/06)
A simple and efficient ligand-free Cu-catalyzed protocol for the synthesis of polysubstituted quinolinesviaoxidative cyclization of oxime acetates with 2-aminobenzyl alcohols at room temperature has been developed. The presented approach provides a new synthetic pathway leading to polysubstituted quinolines with good functional group tolerance under mild conditions. Moreover, this transformation can be applied for the preparation of quinolines on a gram scale. Oxime acetates serve as the internal oxidants in the reactions, thus making this method very attractive.
Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines
Singh, Anshu,Maji, Ankur,Joshi, Mayank,Choudhury, Angshuman R.,Ghosh, Kaushik
, p. 8567 - 8587 (2021/06/30)
Base-metal catalystsCo1,Co2andCo3were synthesized from designed pincer ligandsL1,L2andL3having NNN donor atoms respectively.Co1,Co2andCo3were characterized by IR, UV-Vis. and ESI-MS spectroscopic studies. Single crystal X-ray diffraction studies were investigated to authenticate the molecular structures ofCo1andCo3. CatalystsCo1,Co2andCo3were utilized to study the dehydrogenative activation of alcohols forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines. Under optimized reaction conditions, a broad range of substrates including alcohols, anilines and ketones were exploited. A series of control experiments forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines on the basis of control experiments and detection of reaction intermediates.
Direct synthesis of ring-fused quinolines and pyridines catalyzed byNNHY-ligated manganese complexes (Y = NR2or SR)
Han, Mingyang,Lin, Qing,Liu, Qingbin,Liu, Song,Ma, Ning,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Yan, Xiuli
, p. 8026 - 8036 (2021/12/27)
Four cationic manganese(i) complexes, [(fac-NNHN)Mn(CO)3]Br (Mn-1-Mn-3) and [(fac-NNHS)Mn(CO)3]Br (Mn-4) (whereNNHis a 5,6,7,8-tetrahydro-8-quinolinamine moiety), have been synthesized and evaluated as catalysts for the direct synthesis of quinolines and pyridines by the reaction of a γ-amino alcohol with a ketone or secondary alcohol;NNHS-ligatedMn-4proved the most effective of the four catalysts. The reactions proceeded well in the presence of catalyst loadings in the range 0.5-5.0 mol% and tolerated diverse functional groups such as alkyl, cycloalkyl, alkoxy, chloride and hetero-aryl. A mechanism involving acceptorless dehydrogenation coupling (ADC) has been proposed on the basis of DFT calculations and experimental evidence. Significantly, this manganese-based catalytic protocol provides a promising green and environmentally friendly route to a wide range of synthetically important substituted monocyclic, bicyclic as well as tricyclicN-heterocycles (including 50 quinoline and 26 pyridine examples) with isolated yields of up to 93%.
[(PPh3)2NiCl2]-Catalyzed C-N bond formation reaction via borrowing hydrogen strategy: Access to diverse secondary amines and quinolines
Donthireddy,Pandey, Vipin K.,Rit, Arnab
, p. 6994 - 7001 (2021/06/09)
Commercially available [(PPh3)2NiCl2] was found to be an efficient catalyst for the mono-N-alkylation of (hetero)- A romatic amines, employing alcohols to deliver diverse secondary amines, including the drug intermediates chloropyramine (5b) and mepyramine (5c), in excellent yields (up to 97%) via the borrowing hydrogen strategy. This method shows a superior activity (TON up to 10000) with a broad substrate scope at a low catalyst loading of 1 mol % and a short reaction time. Further, this strategy is also successful in accessing various quinoline derivatives following the acceptorless dehydrogenation pathway.
Ruthenium complex and preparation method thereof and catalytic application
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Paragraph 0104-0106; 0133-0134, (2021/01/24)
The invention discloses a ruthenium complex and a preparation method thereof and catalytic application. The ruthenium complex is reported for the first time. Research finds that the ruthenium complexhas the activity of catalytically synthesizing quinazoline and derivatives thereof or catalytically synthesizing quinoline and derivatives thereof. When the ruthenium complex provided by the inventionis used for catalytic synthesis of quinazoline and derivatives thereof or quinoline and derivatives thereof, the ruthenium complex has the advantages of mild reaction conditions, wide substrate range, high catalytic product yield and good functional group tolerance, and is significantly superior to the prior art.
Bioinspired Radical-Mediated Transition-Metal-Free Synthesis of N-Heterocycles under Visible Light
K. Bains, Amreen,Ankit, Yadav,Adhikari, Debashis
, p. 324 - 329 (2020/11/30)
A redox-active iminoquinone motif connected with π-delocalized pyrene core has been reported that can perform efficient two-electron oxidation of a class of substrates. The design of the molecule was inspired by the organic redox cofactor topaquinone (TPQ), which executes amine oxidation in the enzyme, copper amine oxidase. Easy oxidation of both primary and secondary alcohols happened in the presence of catalytic KOtBu, which could reduce the ligand backbone to its iminosemiquinonate form under photoinduced conditions. Moreover, this easy oxidation of alcohols under aerobic condition could be elegantly extended to multi-component, one-pot coupling for the synthesis of quinoline and pyrimidine. This organocatalytic approach is very mild (70 °C, 8 h) compared to a multitude of transition-metal catalysts that have been used to prepare these heterocycles. A detailed mechanistic study proves the intermediacy of the iminosemiquinonate-type radical and a critical hydrogen atom transfer step to be involved in the dehydrogenation reaction.
Pincerlike manganese complex and preparation method thereof, related ligand and preparation method thereof, catalyst composition and application
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Paragraph 0144; 0145; 0147-0151, (2021/07/31)
The invention discloses a pincerlike manganese complex, a preparation method thereof, a ligand for preparation, a preparation method of the ligand, a catalyst composition taking the complex as an active component and application of the catalyst composition. According to the pincerlike manganese complex, a cycloalkyl ring is introduced into a ligand framework, and by regulating and controlling the cyclic tension, flexibility and steric hindrance of the cycloalkyl ring, the reactivity and stability of the manganese metal center can be effectively adjusted, and the catalytic activity and substrate applicability of a manganese metal system are remarkably improved. The catalyst composition taking the pincerlike manganese complex as an active component has the advantages of high catalyst activity, wide substrate application range, mild reaction conditions and the like in the process of preparing quinoline or pyridine derivatives by catalyzing dehydrogenation coupling reaction of o-amino aromatic alcohol or gamma-amino alcohol, ketone or secondary alcohol; and the synthesis advantages of low cost and stable performance are embodied, the operation is simple, and the yield is high.
Enantioselective Synthesis of Tetrahydroquinolines via One-Pot Cascade Biomimetic Reduction?
Zhao, Zi-Biao,Li, Xiang,Chen, Mu-Wang,Wu, Bo,Zhou, Yong-Gui
, p. 1691 - 1695 (2020/11/03)
A novel and efficient protocol for the synthesis of chiral tetrahydroquinoline derivatives with excellent enantioselectivities and high yields has been developed through one-pot cascade biomimetic reduction. The detailed reaction pathway includes the acid-catalyzed and ruthenium-catalyzed formation of aromatic quinoline intermediates and biomimetic asymmetric reduction.
