- Selective synthesis of 2-indolyl-3-oxoindolines or 2-(2-aminophenyl)quinolines through Cu(II)- or Bi(III)-catalyzed tunable dimerizations of 2-alkynylanilines
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A novel and selective synthesis of 2-indolyl-3-oxoindolines or 2-(2-aminophenyl)quinolines through tunable dimerizations of 2-alkynylanilines is presented. Mechanistically, the formation of 2-indolyl-3-oxoindolines involves a Cu(OAc)2/O2-promoted intramolecular cyclization of 2-alkynylaniline to give the required indole and 3H-indol-3-one intermediates followed by the indolylation of 3H-indol-3-one. On the other hand, the formation of 2-(2-aminophenyl)quinolines is believed to go through a Bi(OTf)3/MesCO2H-catalyzed intermolecular N-nucleophilic addition between two 2-alkynylaniline molecules to give an enamine intermediate followed by its intramolecular C-nucleophilic addition/annulation. Notable features of these new methods include easily obtainable substrates, economical catalysts and oxidant, controllable selectivity, and high versatility toward diverse products.
- Jia, Ruixue,Li, Bin,Zhang, Xinying,Fan, Xuesen
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supporting information
p. 6810 - 6815
(2020/09/15)
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- Unveiling reactive metal sites in a Pd pincer MOF: Insights into Lewis acid and pore selective catalysis
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A porous Zr metal-organic framework, 1-PdBF4 [Zr6O4(OH)4(OAc)2.4{(PNNNP)Pd(MeCN)}2.4(BF4)2.4; PNNNP = 2,6-(HNPAr2)2C5H3N; Ar = p-C6H4CO2-], has been synthesized via postsynthetic oxidative I-/BF4- ligand exchange using NOBF4. 1-PdBF4 enjoys markedly superior catalytic activity and recyclability to its trifluoracetate-exchanged analogue, 1-PdTFA, for the intramolecular cyclization of o-alkynyl anilines and the carbonyl-ene cyclization of citronellal. Moreover, 1-PdBF4 demonstrates a rare example of pore selective catalysis for the cyclization of 2-ethynyl aniline.
- Reiner, Benjamin R.,Kassie, Abebu A.,Wade, Casey R.
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supporting information
p. 9588 - 9595
(2019/07/09)
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- Tunable synthesis of indolo[3,2- c]quinolines or 3-(2-Aminophenyl)Quinolines via aerobic/anaerobic dimerization of 2-alkynylanilines
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In this paper, an unprecedented selective synthesis of indolo[3,2-c]quinoline or 3-(2-aminophenyl)quinoline derivatives through Rh(III)-catalyzed stepwise dimerization of 2-alkynylanilines under aerobic or anaerobic conditions is presented. Notably, hexafluoroisopropanol is found to be a crucial solvent and promoter for the success of these reactions. In addition, the utility of the products thus obtained was showcased by their facile transformations into the pharmaceutically and photophysically significant naphthyridine derivatives.
- Jia, Ruixue,Li, Bin,Liang, Rong,Zhang, Xinying,Fan, Xuesen
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supporting information
p. 4996 - 5001
(2019/07/03)
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- Synthesis of 2-substituted quinazolines by CsOH-mediated direct aerobic oxidative cyclocondensation of 2-aminoarylmethanols with nitriles in air
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By using air as the superior oxidant, a highly atom-efficient synthesis of 2-substituted quinazolines is developed by a CsOH-mediated direct aerobic oxidative reaction of the readily available and stable 2-aminoarylmethanols and nitriles. Effectively working as the promoter in the alcohol oxidation, nitrile hydration, and cyclocondensation steps, CsOH is the best base for the reaction. A similar method can also be extended to the synthesis of substituted quinolines starting from methyl ketones instead of nitriles.
- Yao, Song,Zhou, Kaijing,Wang, Jiabing,Cao, Hongen,Yu, Lei,Wu, Jianzhang,Qiu, Peihong,Xu, Qing
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supporting information
p. 2945 - 2951
(2017/07/24)
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- Revisiting the Gold-Catalyzed Dimerization of 2-Ethynylanilines: A Room-Temperature and Silver-Free Protocol for the Synthesis of Multifunctional Quinolines
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A room temperature and silver-free protocol for the formation of quinolines from 2-ethynylanilines through a dimerization event was achieved using a dinuclear gold catalyst, Au2(BIPHEP)(NTf2)2. The reaction is inherently modular, allowing for the incorporation of peripheral substituents at any site of the quinoline product. The reaction is readily applied to other heterocyles also as exemplified by the preparation of naphthyridines. Competition reactions to determine the reactivity of dissimilar alkynes demonstrated that the product ratio of dimerization vs intermolecular addition is rather dependent on the electronic nature of aryl substituent on the alkynes. However, control experiments with substrates possessing internal alkynes resulted in cycloisomerization instead of expected dimerization, which is indicative of possible steric influence of the alkyne terminus in the reaction outcome.
- Praveen, Chandrasekar,Perumal
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p. 855 - 864
(2016/03/15)
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- A Ruthenium Catalyst with Unprecedented Effectiveness for the Coupling Cyclization of - Amino Alcohols and Secondary Alcohols
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The ruthenium complex (8-(2-diphenylphosphinoethyl)aminotrihydroquinolinyl)(carbonyl)(hydrido)ruthenium chloride exhibited extremely high efficiency toward the coupling cyclization of -amino alcohols with secondary alcohols. The corresponding products, pyridine or quinoline derivatives, are obtained in good to high isolated yields. On comparison with literature catalysts whose noble-metal loading with respect to -amino alcohols reached 0.5-1.0 mol % for Ru and a record lowest of 0.04 mol % for Ir, the current catalyst achieves the same efficiency with a loading of 0.025 mol % for Ru. The mechanism of acceptorless dehydrogenative condensation (ADC) was proposed on the basis of DFT calculations; in addition, the reactive intermediates were determined by GC-MS, NMR, and single-crystal X-ray diffraction. The catalytic process is potentially suitable for industrial applications.
- Pan, Bing,Liu, Bo,Yue, Erlin,Liu, Qingbin,Yang, Xinzheng,Wang, Zheng,Sun, Wen-Hua
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p. 1247 - 1253
(2016/02/18)
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- Regioselective Synthesis of C-3-Functionalized Quinolines via Hetero-Diels-Alder Cycloaddition of Azadienes with Terminal Alkynes
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A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-functionalized quinolines from azadienes (in situ generated from 2-aminobenzyl alcohol) and terminal alkynes through [4 + 2] cycloaddition has been developed. An unprecedented reaction of 2-aminobenzyl alcohol with 1,3- and 1,4-diethynylbenzene provided the C-3 tolylquinolines via [4 + 2] HDA and oxidative decarboxylation. The -NH2 group directed mechanistic approach was well supported by the control experiments and deuterium-labeling studies and by isolating the azadiene intermediate. The reactivity and selectivity of unprotected azadiene in metal-free base-assisted hetero-Diels-Alder reaction is exploited to quickly assemble an important class of C-3-functionalized quinolines, which are difficult to access.
- Saunthwal, Rakesh K.,Patel, Monika,Verma, Akhilesh K.
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p. 6563 - 6572
(2016/08/16)
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- Metal-free aerobic one-pot synthesis of substituted/annulated quinolines from alcohols via indirect Friedl?nder annulation
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Metal-free, operationally simple, and highly efficient one-pot aerobic process for the synthesis of functionalized/annulated quinolines is devised from easily available 2-aminobenzyl alcohol/2-aminobenzophenones and alkyl/aryl alcohols for the first time. The process involves two sequential reactions, namely in situ aerial oxidation of alcohols to the corresponding aldehydes/ketones followed by Friedl?nder annulation.
- Anand, Namrata,Koley, Suvajit,Ramulu, B. Janaki,Singh, Maya Shankar
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supporting information
p. 9570 - 9574
(2015/09/28)
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- A Sc(OTf)3-catalyzed cascade reaction of o-aminoacetophenone with methanamine: Construction of dibenzo[b,h][1,6]naphthyridine derivatives
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An unexpected Sc(OTf)3-catalyzed and air-mediated cascade reaction of o-aminoacetophenones with methanamines was discovered as an efficient synthetic approach to a novel class of fluorescent fused-four-ring dibenzo[b,h][1,6]naphthyridine derivatives. Two possible mechanisms of the reaction were proposed. The photophysical properties of the dibenzo[b,h][1,6]naphthyridine 1a were initially considered. This journal is
- Mao, Dan,Tang, Jun,Wang, Wenbo,Liu, Xin,Wu, Shengying,Yu, Jianjun,Wang, Limin
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supporting information
p. 2122 - 2128
(2015/03/05)
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- Synthesis of polysubstituted analogues of the 4-methyl-2-phenylquinoline
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A simple and convenient synthetic method for the direct synthesis of a series of polysubstituted analogues of the putative antifungal agent 4-methyl-2-phenylquinoline, a mimic of the natural bioactive 4-methoxy-2-phenylquinoline is reported.
- Al-Qahtani,Al-Turki,Khan,Mousa,Alkhathlan
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p. 6055 - 6058
(2013/07/26)
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- Dimerization of ethynylaniline to a quinoline derivative using a ruthenium/gold heterobimetallic catalyst
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Dimerization of 2-ethynylaniline in the presence of the Ru/Au complexes CpRu(PPh3)Cl(μ-dppm)AuCl or CpRu(PPh3)I(μ-dppm)AuI results in formation of a quinoline derivative. Monometallic model compounds for the Ru and Au centers did not catalyze the dimerization reaction. This transformation proceeds in higher yield in the absence of solvent.
- Shelton, Phillip A.,Hilliard, Casie R.,Swindling, Michael,McElwee-White, Lisa
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experimental part
p. 160 - 166
(2010/09/11)
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- Single bifunctional ruthenium catalyst for one-pot cyclization and hydration giving functionalized indoles and benzofurans
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Chemical equation Presented Bifunctional is more than twice as fun! At low loading, catalyst 1 (see scheme) can form two important heterocycle classes, apparently by attack of XH on a vinylidene intermediate. Aza- and nitroindoles can be formed, and all N-protecting groups tested (alkyl, allyl, sulfonyl) were tolerated. The newly formed ring can be deuterated in one step, and for substrates with two terminal alkynes, cyclization can be followed by hydration, making this catalyst uniquely versatile.
- Nair, Reji N.,Lee, Paul J.,Rheingold, Arnold L.,Grotjahn, Douglas B.
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supporting information; experimental part
p. 7992 - 7995
(2010/09/18)
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- Microwave-promoted syntheses of quinazolines and dihydroquinazolines from 2-aminoarylalkanone O-phenyl oximes
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(Chemical Equation Presented) A wide range of biologically active compounds contain the quinazoline ring system. A new free-radical-based method of making functionalized quinazolines is described, which relies on microwave-promoted reactions of O-phenyl oximes with aldehydes. A small set of 2-aminoaryl alkanone O-phenyl oximes was prepared and shown to produce dihydroquinazolines when mixed with an aldehyde in toluene and subjected to microwave heating. When ZnCl2 was included in the reaction mixture, fully aromatic quinazolines were produced in high yields by a rapid and convenient process. The method worked well with alkyl, aryl, and heterocyclic aldehydes and for a variety of substituents in the benzenic part of the molecule. Similar reactions employing ketones instead of aldehydes were less efficient. Although some dihydroquinazolines did form, they were accompanied by several byproducts. Surprisingly, in each case, one of the byproducts was a quinoline derivative, and a plausible mechanism to account for this rearrangement is proposed.
- Portela-Cubillo, Fernando,Scott, Jackie S.,Walton, John C.
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supporting information; experimental part
p. 4934 - 4942
(2009/12/01)
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- Gold(III) Chloride catalyzed intermolecular dimerization of 2-ethynylanilines: Synthesis of substituted quinolines
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An unprecedented gold(III)-catalyzed intermolecular dimerization of 2-ethynylanilines possessing terminal triple bond offers a general synthetic pathway to a wide range of highly substituted quinolines.
- Praveen,Jegatheesan,Perumal
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experimental part
p. 2795 - 2800
(2010/03/03)
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- InBr3-promoted divergent approach to polysubstituted indoles and quinolines from 2-ethynylanilines: Switch from an intramolecular cyclization to an intermolecular dimerization by a type of terminal substituent group
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(Chemical Equation Presented) Use of a 2-ethynylaniline having an alkyl or aryl group on the terminal alkyne selectively produced a variety of polyfunctionalized indole derivatives in moderate to excellent yields via indium-catalyzed intramolecular cyclization of the corresponding alkynylaniline. In contrast, employment of a substrate with a trimethylsilyl group or with no substituent group on the terminal triple bond, exclusively afforded polysubstituted quinoline derivatives in good yields via indium-promoted intermolecular dimerization of the ethynylaniline. This indium catalytic system successfully accommodated the intramolecular cyclization of other arylalkyne skeletons involving a carboxylic acid and an amide group.
- Sakai, Norio,Annaka, Kimiyoshi,Fujita, Akiko,Sato, Asuka,Konakahara, Takeo
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p. 4160 - 4165
(2008/09/21)
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- Direct synthesis of polysubstituted quinoline derivatives by InBr 3-promoted dimerization of 2-ethynylaniline derivatives
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InBr3 promotes the dimerization of 2-ethynylaniline derivatives containing an unsubstituted terminal carbon leading to the production of polysubstituted quinoline derivatives in good yield.
- Sakai, Norio,Annaka, Kimiyoshi,Konakahara, Takeo
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p. 3653 - 3655
(2007/10/03)
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- Preparation and Synthetic Applications of Iminophosphoranes Derived from o-Substituted Arylazides: Preparation of PyrazoloIndazole, 4H-3,1-Benzoxazine and Quinoline Derivatives. Crystal structure of 2--4-methylquino
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The Staudinger reaction of several ortho-substituted arylazides with triphenylphosphine has been studied.The reaction product is found to be strongly dependent on the nature of the ortho-substituent.The Aza Wittig-type reaction of iminophosphorane derived
- Molina, Pedro,Conesa, Carlota,Alias, Asuncion,Arques, Antonio,Velasco, Maria D.,et al.
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p. 7599 - 7612
(2007/10/02)
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