- Polar Effects in Free-Radical Reactions. Selectivity and Reversibility in the Homolytic Benzylation of Protonated Heteroaromatic Bases
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The homolytic benzylation of protonated 4-cyanopyridine, quinoline, 2-methyl- and 4-methylquinoline, isoquinoline, and quinoxaline is investigated.The great influence of the polar effect and of the reversibility of the addition of the benzyl radical on the reaction selectivity is discussed.It is put forward the hypothesis that the HSAB principle can be extended to free-radical reactions when the polar effect is the dominant factor.
- Minisci, Francesco,Vismara, Elena,Morini, Giampiero,Fontana, Francesca,Levi, Silvio,et al.
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- Mild Condition for the Deoxygenation of α-Heteroaryl-Substituted Methanol Derivatives
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A mild condition via PPh3/I2/imidazole for the deoxygenation of substituted methanol derivatives has been identified. This metal-free process was found to proceed well on secondary or tertiary alcohols substituted with one or two heteroaryl groups, and it tolerates acid-sensitive heterocycles. This condition works for methanol derivatives substituted with 2-pyridyl, 4-pyridyl, or other heterocyclic groups, allowing the negative charge formed during the reaction to resonate to a nitrogen atom. Methanol derivatives substituted with 3-pyridyl or heterocyclic groups that do not allow the negative charge formed during the reaction to resonate to a nitrogen atom will not undergo deoxygenation under this condition.
- Meng, Na,Yu, Wensheng,Suzuki, Takao,Chen, Maofen,Qi, Zhiqi,Hu, Bin,Bao, Jianming,Debenham, John S.,Mazzola, Robert,Duffy, Joseph L.
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p. 5560 - 5567
(2021/05/04)
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- A Metal- and Azide-free Oxidative Coupling Reaction for the Synthesis of [1,2,3]Triazolo[1,5-a]quinolines and their Application to Construct C?C and C-P Bonds, 2-Cyclopropylquinolines and Imidazo[1,5-a]quinolines
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An iodine-promoted one-pot cascade oxidative annulation reaction has been developed for the synthesis of [1,2,3]triazolo[1,5-a]quinolines from methyl azaarenes and N-tosylhydrazines. The reaction has a broad substrate scope and can be easily scaled up to gram-scale. 1,2,3-Triazoles are an important skeletal structure for the construction of C?C and C?P bonds, 2-cyclopropylquinolines and imidazo[1,5-a]quinolines, for which different synthetic applications were explored. (Figure presented.).
- Shang, Zhi-Hao,Zhang, Zhen-Xiao,Weng, Wei-Zhao,Wang, Yu-Fei,Cheng, Tian-Wei,Zhang, Qiu-Yi,Song, Li-Qun,Shao, Tian-Qi,Liu, Kai-Xuan,Zhu, Yan-Ping
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p. 490 - 496
(2020/12/07)
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- Acylation of 2-benzylpyridine N-oxides and subsequent in situ [3,3]-sigamatropic rearrangement reaction
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An effective method for the acylation of 2-benzylpyridine N-oxides and their fast in situ [3,3]-sigmatropic rearrangement was reported. This transformation has a wide substrate scope under mild conditions, giving moderate to excellent yields. The application for the synthesis of chiral phenyl-2-pyridylmethanol products was briefly explored. Furthermore, an interesting example of tandem substitution and in situ [3,3]-sigamatropic rearrangement of 2-benzylpyridine N-oxide with benzenecarboximidoyl chloride was reported.
- Antilla, Jon C.,Jing, Hua-qing,Li, Hong-liang
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supporting information
(2020/09/22)
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- Catalytic Selective Metal-Free Cross-Coupling of Heteroaromatic N-Oxides with Organosilanes
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A metal-free, regioselective C-H functionalization of heteroaromatic N-oxides has been developed. The method enables the synthesis of various benzylated and alkynylated N-heterocycles in a transition-metal-free manner employing organosilanes as coupling partners. The unanticipated reactivity has been exploited for the synthesis of a number of symmetrical disubstituted acetylenes from ethynyltrimethylsilane via carbon-silicon bond metathesis.
- Puthanveedu, Mahesh,Polychronidou, Vasiliki,Antonchick, Andrey P.
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p. 3407 - 3411
(2019/05/10)
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- Photocatalyzed ortho-Alkylation of Pyridine N-Oxides through Alkene Cleavage
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A photocatalyzed reaction of pyridine N-oxides with alkenes gives ortho-alkylated pyridines with cleavage of the carbon–carbon double bond. Benzyl and secondary alkyl groups are incorporated at the ortho position of pyridines in one pot.
- Zhou, Wang,Miura, Tomoya,Murakami, Masahiro
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supporting information
p. 5139 - 5142
(2018/05/30)
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- Palladium-Catalyzed Arylation of Benzylic C-H Bonds of Azaarylmethanes with Aryl Sulfides
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Benzylic C-H arylation of azaarylmethanes with aryl sulfides has been developed by using a Pd-NHC catalyst and an amide base. Various azaarylmethanes and aryl sulfides were involved in the reaction to afford the corresponding diarylmethanes in good to excellent yields. Moreover, triarylmethane synthesis was accomplished through iterative arylations of 2- or 4-methylpyridine with two different aryl sulfides.
- Gao, Ke,Yamamoto, Keita,Nogi, Keisuke,Yorimitsu, Hideki
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supporting information
p. 2956 - 2960
(2017/10/06)
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- Synthesis of 2-Substituted Quinolines via Rhodium(III)-Catalyzed C–H Activation of Imidamides and Coupling with Cyclopropanols
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An efficient synthesis of 2-substituted quinolines from readily available cyclopropanols and imidamides has been developed, where the cyclopropanol acts as a C3 synthon. With the assistance of a bifunctional imidamide directing group, the reaction occurred via sequential C–H/C–C cleavage and C–C/C–N bond formation. (Figure presented.).
- Zhou, Xukai,Qi, Zisong,Yu, Songjie,Kong, Lingheng,Li, Yang,Tian, Wan-Fa,Li, Xingwei
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p. 1620 - 1625
(2017/05/22)
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- Traceless Directing-Group Strategy in the Ru-Catalyzed, Formal [3 + 3] Annulation of Anilines with Allyl Alcohols: A One-Pot, Domino Approach for the Synthesis of Quinolines
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A unique, ruthenium-catalyzed, [3 + 3] annulation of anilines with allyl alcohols in the synthesis of substituted quinolines is reported. The method employs a traceless directing group strategy in the proximal C-H bond activation and represents a one-pot Domino synthesis of quinolines from anilines.
- Kumar, Gangam Srikanth,Kumar, Pravin,Kapur, Manmohan
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p. 2494 - 2497
(2017/05/24)
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- Base metal-catalyzed benzylic oxidation of (aryl)(heteroaryl)methanes with molecular oxygen
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The methylene group of various substituted 2- and 4-benzylpyridines, benzyldiazines and benzyl(iso)quinolines was successfully oxidized to the corresponding benzylic ketones using a copper or iron catalyst and molecular oxygen as the stoichiometric oxidant. Application of the protocol in API synthesis is exemplified by the alternative synthesis of a precursor to the antimalarial drug Mefloquine. The oxidation method can also be used to prepare metabolites of APIs which is illustrated for the natural product papaverine. ICP-MS analysis of the purified reaction products revealed that the base metal impurity was well below the regulatory limit.
- Sterckx, Hans,De Houwer, Johan,Mensch, Carl,Herrebout, Wouter,Tehrani, Kourosch Abbaspour,Maes, Bert U.W.
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supporting information
p. 144 - 153
(2016/04/05)
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- Palladium-catalyzed approach for the general synthesis of (E)-2-arylmethylidene-N-tosylindolines and (E)-2-arylmethylidene-N-tosyl/ nosyltetrahydroquinolines: Access to 2-substituted indoles and quinolines
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A facile and efficient method for the synthesis of (E)-2-arylmethylidene-N- tosylindolines and (E)-2-arylmethylidene-N-tosyl/nosyltetrahydroquinoline variants has been developed through palladium-catalyzed cyclocondensation of aryl iodides with readily available 1-(2-tosylaminophenyl)prop-2-yn-1-ols and their higher homologues, respectively. The proposed reaction mechanism invokes the operation of trans-aminopalladation during cyclization (5/6-exo-dig), which ensures exclusive (E)-stereochemistry in the products. The method is fast, operationally simple, totally regio- and stereoselective, and versatile enough to access a variety of 2-substituted indoles and quinolines. The reactions proceeded efficiently with a wide variety of substrates and afforded the corresponding products in moderate to excellent yields.
- Chowdhury, Chinmay,Das, Bimolendu,Mukherjee, Sanjukta,Achari, Basudeb
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p. 5108 - 5119
(2012/07/14)
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- Direct arylation/alkylation/magnesiation of benzyl alcohols in the presence of grignard reagents via Ni-, Fe-, or Co-catalyzed sp3 C-O Bond activation
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Direct application of benzyl alcohols (or their magnesium salts) as electrophiles in various reactions with Grignard reagents has been developed via transition metal-catalyzed sp3 C-O bond activation. Ni complex was found to be an efficient catalyst for the first direct cross coupling of benzyl alcohols with aryl/alkyl Grignard reagents, while Fe, Co, or Ni catalysts could promote the unprecedented conversion of benzyl alcohols to benzyl Grignard reagents in the presence of nhexylMgCl. These methods offer straightforward pathways to transform benzyl alcohols into a variety of functionalities.
- Yu, Da-Gang,Wang, Xin,Zhu, Ru-Yi,Luo, Shuang,Zhang, Xiao-Bo,Wang, Bi-Qin,Wang, Lei,Shi, Zhang-Jie
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p. 14638 - 14641
(2012/11/07)
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- Palladium-catalyzed decarboxylative couplings of 2-(2-Azaaryl)acetates with aryl halides and triflates
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Pd-catalyzed decarboxylative cross-couplings of 2-(2-azaaryl)acetates with aryl halides and triflates have been discovered. This reaction is potentially useful for the synthesis of some functionalized pyridines, quinolines, pyrazines, benzoxazoles, and benzothiazoles. Theoretical analysis shows that the nitrogen atom at the 2-position of the heteroaromatics directly coordinates to Pd(II) in the decarboxylation transition state.
- Shang, Rui,Yang, Zhi-Wei,Wang, Yan,Zhang, Song-Lin,Liu, Lei
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supporting information; experimental part
p. 14391 - 14393
(2010/12/19)
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- Highly enantioselective iridium-Catalyzed hydrogenation of 2-Benzylquinolines and 2-Functionalized and 2,3-disubstituted quinolines
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The enantioselective hydrogenation of 2-benzylquinolines and 2-functionalized and 2,3-disubstituted quinohnes was developed by using the [Ir(COD)Cl]2/bisphosphine/I2 system with up to 96% ee. Moreover, mechanistic studies revealed the hydrogenation mechanism of quinoline involves a 1,4-hydride addition, isomerization, and 1,2-hydride addition, and the catalytic active species may be a Ir(III) complex with chloride and iodide.
- Wang, Da-Wei,Wang, Xiao-Bing,Wang, Duo-Sheng,Lu, Sheng-Mei,Zhou, Yong-Gui,Li, Yu-Xue
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supporting information; experimental part
p. 2780 - 2787
(2009/08/08)
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- Sc(OTf)3-catalyzed direct alkylation of quinolines and pyridines with alkanes
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The Sc(OTf)3-catalyzed C-C bond formation by direct alkylation of quinolines and pyridines using simple alkanes was developed. Various alkanes reacted with quinolines and pyridines to give the corresponding alkylation products in 50-91% yields
- Deng, Guojun,Li, Chao-Jun
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supporting information; experimental part
p. 1171 - 1174
(2009/08/07)
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- Palladium-catalyzed cross-coupling of B-Benzyl-9-borabicyclo[3.3.1]nonane to furnish methylene-linked biaryls
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(Chemical Equation Presented) Benzylboranes are noticeably uncommon partners within Suzuki-Miyaura coupling reactions. B-Benzyl-9-BBN was successfully coupled to a range of aryl/heteroaryl bromides, chlorides, and triflates to give pharmacologically important methylene-linked biaryl structures. Activated, deactivated, and sterically hindered substrates were successfully coupled in high yield using Pd(PPh3)4 or Pd(OAc)2 with SPhos as the catalyst system.
- Flaherty, Alice,Trunkfield, Amy,Barton, William
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p. 4975 - 4978
(2007/10/03)
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- Cobalt-catalyzed cross-coupling reaction of chloropyridines with grignard reagents
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Treatment of 2-chloropyridine with benzylmagnesium chloride in the presence of a catalytic amount of cobalt(II) acetylacetonate in dioxane afforded the corresponding cross-coupling product in excellent yield. Trimethylsilylmethyl and phenyl Grignard reagents also participated in similar cross-coupling reactions.
- Ohmiya, Hirohisa,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1240 - 1241
(2007/10/03)
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- N-Heteroarylphosphonates, Part II. Synthesis and reactions of 2- and 4- phosphonatoquinolines and related compounds
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We extend our synthetic method for the efficient preparation of dialkoxyphosphoryl- and phosphonio-disubstituted pyridines to include the preparation of other phosphonato substituted N-heterocycles. The key to the success of this method lies in the employment of cationic N- (trifluoromethylsulfonyl)heteroarylium triflates that are activated towards nucleophilic attack. The P(O)(OR)2 group can be transformed into the P(S)(OR)2 functionality. We report first attempts to substitute the P(O)(OR)2 moiety with C-nucleophiles. In addition to our synthetic results, the X-ray structures of two (dimethoxyphosphoryl)trifluoromethanesulfonyldihydro-N-heteroarenes are discussed. We also give complete carbon (13C) and phosphorus (31P)-NMR spectra of a series of 2- and 4-phosphonic ester substituted heteroaryl compounds and their dihydro analogs.
- Haase, Mirko,Guì?nther, Wolfgang,Goì?rls, Helmar,Anders, Ernst
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p. 2071 - 2081
(2007/10/03)
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- FORMATION OF PHENYL SUBSTITUTED HETEROAROMATICS BY LIGAND COUPLING IN THE REACTION BETWEEN HETEROARYL SULFOXIDES WITH PHENYL GRIGNARD REAGENT
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In the reaction of heteroaryl alkyl sulfoxides with phenylmagnesium bromide, phenyl group was found to couple predominantly with 2-quinolyl group and 2-pyrimidinyl group.
- Oae, Shigeru,Takeda, Takashi,Wakabayashi, Shoji
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- Hypoglycemic thiazolidinediones
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Hypoglycemic 5-[1-(5,6,7,8-tetrahydro-2-napthyl-; 1,2,3,4-tetrahydro-6-quinolyl-; 2-indanyl-; and 2-indolyl)alkyl]thiazolidine-2,4-dione derivatives, pharmaceutically acceptable salts thereof, and a method for their use in the treatment of hyperglycemic mammals.
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- OCCURRENCE OF LIGAND COUPLING IN THE REACTIONS OF VARIOUS SULFOXIDES WITH GRIGNARD REAGENTS
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Ligand coupling reactions take place not only between benzyl and 2-pyridyl groups and two 2-pyridyl groups in the treatment of benzyl, alkyl and aryl 2-pyridyl sulfoxides with Grignard reagents, but also between such groups as p-benzenesulfonylphenyl, 4-pyridyl, 2-quinolyl and 2-pyrimidyl, and the benzyl group.There are cases in which ligand exchange precedes ligand coupling, especially with 2-heteroaryl groups.In addition, even some alkyl groups were found to couple with the 2-pyridyl group.The ease of coupling seems to be associated with the electronegativity of the coupling carbon atom of the ligand, when one compares the 13C NMR chemical shifts.
- Kawai, Tsutomu,Kodera, Yoichi,Furukawa, Naomichi,Oae, Shigeru,Ishida, Masahiro,et al.
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p. 139 - 148
(2007/10/02)
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- Studies on Tertiary Amine Oxides. LXXX.1) Reaction of Quinoline 1-oxide with Phenylacetic Anhydride
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Treatment of quinoline 1-oxide (1) with phenylacetic acid and acetic anhydride in boiling benzene for 10 h gave benzaldehyde (2), quinoline (3), 2-benzylquinoline (4), 2-benzoylquinoline (5), phenyl-di(2-quinolyl)carbinol (6), di(2-quinolyl) ketone (7), and N-(2-quinolyl)-2-benzylidene-1,2-dihydroquinoline (8) in small yields.The reaction of 1 with phenylacetic anhydride in boiling benzene for 10 h afforded 1,3-diphenyl-1-(2-quinolyl)acetone (9) and dibenzyl ketone (10) together with small amounts of 2, 3, and 5.Further, it was found that phenylacetic anhydrideundergoes decarboxylative coupling upon heating with tertiary amines to give 10.The mechamisms of these reactions are discussed. Keywords --- nucleophilic reaction; oxidative decarboxylation; decarboxylative coupling; benzaldehyde; 2-benzylquinoline; phenyl-di(2-quinolyl)carbinol; N-(2-quinolyl)-2-benzylidene-1,2-dihydroquinoline; 1,3-diphenyl-1-(2-quinolyl)acetone; dibenzyl ketone
- Funakoshi, Kazuhisa,Mizuoka, Masae,Wada, Kazuko,Saeki, Seitaro,Hamana, Masatomo
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p. 3886 - 3891
(2007/10/02)
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- NEW DIHYDROQUINOLINES SYNTHESIS VIA TERTIARY AZIDES
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When applied to tertiary alcohols of the indane series, the SCHMIDT reaction allows the synthesis of dihydroquinolines substituted on the -2 position.The latter are aromatised in the corresponding quinolines using triphenylmethyl perchlorate.
- Adam, Gerard,Andrieux, Jean,Plat, Michel M.
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p. 3609 - 3612
(2007/10/02)
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- CONVERSION OF HETEROCYCLIC N-OXIDES INTO α-ALKYLATED HETEROCYCLES. TRIMETHYLSILANOL AS LEAVING GROUP -IV.
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Aromatic heterocyclic N-oxides are readily converted into α-alkylated heterocycles by allyl-or benzyltrimethylsilane and fluoride ion.
- Vorbrueggen, Helmut,Krolikiewicz, Konrad
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p. 889 - 890
(2007/10/02)
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