6457-30-3Relevant academic research and scientific papers
Non-electronic aromatic ring activation by simple steric repulsion between substituents in 1-methylquinolinium salt systems
Iwai, Kento,Yokoyama, Soichi,Asahara, Haruyasu,Nishiwaki, Nagatoshi
, p. 50 - 57 (2020/01/21)
A systematic study of non-electronic activation of an aromatic ring was performed using a series of 8-substituted 1-methylquinolinium salts. As the 8-substituent became bulkier, the quinoline framework was distorted by steric repulsion between substituents at the 1- A nd 8-positions. This was accompanied by lack of coplanarity, which brought about dearomatization. Consequently, quinolinium ions possessing a bulky 8-substituent exhibited high reactivity undergoing nucleophilic addition at the 2-position efficiently. We demonstrate that the activation was achieved sterically and not electronically.
Molybdenum-Catalyzed Deoxygenation of Heteroaromatic N-Oxides and Hydroxides using Pinacol as Reducing Agent
Rubio-Presa, Rubén,Fernández-Rodríguez, Manuel A.,Pedrosa, María R.,Arnáiz, Francisco J.,Sanz, Roberto
supporting information, p. 1752 - 1757 (2017/05/22)
A molybdenum-catalyzed deoxygenation of pyridine N-oxides and N-hydroxybenzotriazoles, as well as other azole N-oxides, has been developed using pinacol as an environmentally friendly oxo-acceptor. The only by-products are acetone and water making the process a convenient alternative to established protocols in terms of waste generation. The reaction is highly chemoselective and a variety of functional groups are tolerated. The processes are usually very clean allowing the isolation of the pure deoxygenated products after a simple extraction in most cases. (Figure presented.).
METHOD OF PREPARING SILYLATIVE-REDUCED N-HETEROCYCLIC COMPOUND USING ORGANOBORON CATALYST
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Paragraph 237; 238; 239; 240, (2016/06/06)
Provided is a method of preparing a silylative-reduced N-heterocyclic compound by reducing an N-heteraromatic compound including a sp2 hybridized nitrogen atom while simultaneously introducing a silyl group into a beta-position with respect to a nitrogen atom of the N-heteroaromatic compound, using a silane compound, in the presence of an organoboron catalyst.
Highly Enantioselective Direct Synthesis of Endocyclic Vicinal Diamines through Chiral Ru(diamine)-Catalyzed Hydrogenation of 2,2′-Bisquinoline Derivatives
Ma, Wenpeng,Zhang, Jianwei,Xu, Cong,Chen, Fei,He, Yan-Mei,Fan, Qing-Hua
supporting information, p. 12891 - 12894 (2016/10/04)
An asymmetric hydrogenation of 2,2′-bisquinoline and bisquinoxaline derivatives, catalyzed by chiral cationic ruthenium diamine complexes, was developed. A broad range of chiral endocyclic vicinal diamines were obtained in high yields with excellent diastereo- and enantioselectivity (up to 93:7 dl/meso and >99 % ee). These chiral diamines could be easily transformed into a new class of chiral N-heterocyclic carbenes (NHCs), which are important but difficult to access.
Boron-catalyzed silylative reduction of quinolines: Selective sp3 C-Si bond formation
Gandhamsetty, Narasimhulu,Joung, Seewon,Park, Sung-Woo,Park, Sehoon,Chang, Sukbok
supporting information, p. 16780 - 16783 (2015/01/09)
A silylative reduction of quinolines to synthetically versatile tetrahydroquinoline molecules involving the formation of a C(sp3)-Si bond exclusively β to nitrogen is described. Triarylborane is a highly efficient catalyst (up to 1000 turnovers), and silanes serve as both a silyl source and a reducing reagent. The present procedure is convenient to perform even on a large scale with excellent stereoselectivity. Mechanistic studies revealed that the formation of a 1,4-addition adduct is rate-limiting while the subsequent C(sp3)-Si bond-forming step from the 1,4-adduct is facile.
Gold-catalyzed oxidative rearrangement involving 1,2-acyl migration: Efficient synthesis of functionalized dihydro-γ-carbolines from α-(2-indolyl) propargylic alcohols and imines
Wang, Lu,Xie, Xin,Liu, Yuanhong
supporting information, p. 13302 - 13306 (2014/01/06)
Smooth moves with a nifty side step: A gold-catalyzed transformation of α-(2-indolyl) propargylic alcohols with imines in the presence of the oxidant 8-isopropylquinoline N-oxide provided rapid access to highly functionalized dihydro-γ-carbolines (see scheme). The reaction mechanism is proposed to involve intermolecular trapping of an α-carbonyl gold carbenoid intermediate, followed by cyclization and a novel gold-assisted 1,2-acyl migration.
Nickel-catalyzed reductive coupling of aryl halides with secondary alkyl bromides and allylic acetate
Wang, Shulin,Qian, Qun,Gong, Hegui
supporting information; experimental part, p. 3352 - 3355 (2012/08/08)
A room-temperature Ni-catalyzed reductive method for the coupling of aryl bromides with secondary alkyl bromides has been developed, providing C(sp 2)-C(sp3) products in good to excellent yields. Slight modification of this protocol allows efficient coupling of activated aryl chlorides with cyclohexyl bromide and aryl bromides with allylic acetate.
Gold-catalyzed highly regioselective oxidation of C-C triple bonds without acid additives: Propargyl moieties as masked α,β-unsaturated carbonyls
Lu, Biao,Li, Chaoqun,Zhang, Liming
supporting information; experimental part, p. 14070 - 14072 (2011/01/04)
Gold-catalyzed intermolecular oxidations of internal alkynes have been achieved with high regioselectivities using 8-alkylquinoline N-oxides as oxidants and in the absence of acid additives. Synthetically versatile α,β-unsaturated carbonyls are obtained in good to excellent yields and with excellent E-selectivities. A range of functional groups such as THP, MOMO, N3, OTBS, and N-Boc are tolerated. This reaction allows α,β-unsaturated carbonyls to be masked as propargyl moieties, thus offering a practical solution to compatibility issues with these functional groups likely encountered in syntheses of complex structures.
Selectivity in the Hydrogenation of 6- and 8-Substituted-quinolines
Hoenel, Michael,Vierhapper, Friedrich W.
, p. 1933 - 1939 (2007/10/02)
Quinoline (1) and the 6- or 8-substituted-quinolines (2)-(14) (R = Me, Pri, But, Ph, OMe, OH, CF3, or F) were hydrogenated catalytically on platinum under either weakly basic (solvent MeOH) or strongly acidic (solvent CF3CO2H) conditions.In methanol the only product was the corresponding 1,2,3,4-tetrahydro-compound.In trifluoroacetic acid, compounds hydrogenated in the benzene ring were isolated as major products; both electron-withdrawing and electron-donating substituents at C-6 or C-8 cause (sometimes drastic) reduction in yield.The products were characterized by their 1H and 13C n.m.r. spectra.
Rhodium(I) Complexes of 8-Methyl-, 8-Ethyl-, and 8-Isopropyl-quinolines and Realated 2-Substituted Derivatives
Deeming, Antony J.,Rothwell, Ian P.
, p. 1259 - 1264 (2007/10/02)
The complexes have been prepared from on adding unidentate L (8-methyl-, -ethyl-, or -isopropyl-quinoline) or bidentate L (1,10-phenantroline or quinoline-2-carboxaldehide-N-methylimine). 8-Alkyl-substitution of the latter ligand gives the complexes as isomers with uni- and bi-dentate L respectively with relative stabilities of the unidentate form depending on the 8-substituent in the order Pri > Et > Me.Unidentate L is also favoured by replacing PPh3 by P(C6H11)3 but bidentate co-ordination is found using AsPh3 or PMe2Ph.Equilibrium constants for chloro-bridge cleavage of by 8-substituted and 2,8-disubstituted quinolines are reduced by increasing the size of the 8-susbtituent and even more by further introduction of a 2-methyl group.The contributions of distortions in the co-ordination to these changes in equilibrium constants are discussed.
