- Cobalt-catalyzed direct alkenylation of 2-methylquinolines with aldehydes via C(sp3)-H functionalization in water
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The direct C(sp3)-H alkenylation of 2-methylquinolines with aldehydes as a simple methodology to afford 2-alkenylated quinolines is reported. In the presence of catalytic CoCl2 in water, the economically and ecologically sound transformation is proposed to proceed via the direct benzylic addition to the aldehyde followed by an elimination step to provide 2-alkenylated quinolines in good to excellent yield of up to 95%. Georg Thieme Verlag Stuttgart New York.
- Jamal, Zaini,Teo, Yong-Chua
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- NH4I-mediated sp3 C-H cross-dehydrogenative coupling of benzylamines with 2-methylquinoline for the synthesis of E-2-styrylquinolines
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Without any metal catalyst, a simple and efficient method for the synthesis of E-2-styrylquinolines through sp3 C-H cross-dehydrogenative coupling of benzylamines with 2-methylquinolines mediated by NH4I under air is successfully developed. The oxidative olefination proceeded through deamination and sp3 C–H bond activation. A plausible mechanism is proposed for the construction of E-2-styrylquinolines.
- Huang, Bin,Li, Xue,Liao, WeiBo,Wang, JiangWei,Zhang, YuanYuan
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p. 903 - 910
(2021/07/17)
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- Deaminative Olefination of Methyl N-Heteroarenes by an Amine Oxidase Inspired Catalyst
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We explored the bioinspired o-quinone cofactor catalyzed aerobic primary amine dehydrogenation for a cascade olefination reaction with nine different methyl N-heteroarenes, including pyrimidines, pyrazines, pyridines, quinolines, quinoxolines, benzimidazoles, benzoxazoles, benzthiazoles, and triazines. An o-quinone catalyst phd (1,10-phenanthroline-5,6-dione) combined with a Br?nsted acid catalyzed the reaction. N-Heteroaryl stilbenoids were synthesized in high yields and (E)-selectivities under mild conditions using oxygen (1 atm) as the sole oxidant without needing transition-metal salt, ligand, stoichiometric base, or oxidant.
- Thorve, Pradip Ramdas,Maji, Biplab
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supporting information
p. 542 - 547
(2021/01/26)
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- Nickel(II)-Catalyzed Selective (E)-Olefination of Methyl Heteroarenes Using Benzyl Alcohols via Acceptorless Dehydrogenative Coupling Reaction
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An efficient catalytic protocol for the synthesis of selective (E)-olefins by the newly synthesized nickel complexes via greener acceptorless dehydrogenative coupling methodology is presented. Two nickel(II) N, S chelating complexes were structurally characterized with the aid of spectral and single crystal X-ray diffraction methods. Olefination of 2-methylheteroarenes with benzyl alcohols via acceptorless dehydrogenative coupling is achieved by inexpensive nickel(II) catalysts. The present olefination protocol is simple and furnishes the desired 2-alkenylheteroarenes in 35 h and yields in the range of 40–93 %. The dehydrogenative coupling reaction proceeds via the generation of an aldehyde intermediate and produces water and hydrogen as sole by-products. The wide substrate scope of this catalytic reaction covered the synthesis of drug intermediates.
- Balamurugan, Gunasekaran,Ramesh, Rengan
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- NaCl as Catalyst and Water as Solvent: Highly E-Selective Olefination of Methyl Substituted N-Heteroarenes with Benzyl Amines and Alcohols
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Oxidative coupling of benzylamines and alcohols with methyl substituted N-heteroarenes such as quinolines and quinoxalines has been achieved using chloride, a sea abundant anion as the catalyst for practical synthesis of a wide range of E-disubstituted olefins in aqueous medium. Detailed mechanistic studies and control experiments were carried out to deduce the reaction mechanism which indicated that in situ formed ClO2- is the active form of the catalyst. We have successfully carried out a 1 g scale reaction using this methodology, and five pharmaceutically relevant conjugated olefins were also synthesized by this method in moderate to good yields.
- Hazra, Susanta,Tiwari, Vikas,Verma, Ashutosh,Dolui, Pritam,Elias, Anil J.
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supporting information
p. 5496 - 5501
(2020/07/14)
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- Iron/TEMPO-catalyzed direct aerobic oxidative coupling of methyl-mubstituted N-heteroazaarenes with alcohols
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A novel direct oxidative coupling of methyl-substituted N-heteroazaarenes with alcohols has been developed to construct olefins under mild condition. The reaction is catalyzed by Fe(NO3)3·9H2O/TEMPO with oxygen as terminal oxidant. A variety of E-disubstituted olefins bearing diverse functional groups could be obtained selectively in moderate to excellent yields. The reaction is environmentally friendly and ligand-free.
- Zhang, Zhiguang,Ma, Yantao,Dai, Siwei,Li, Ling,Zhang, Yong,Li, Hao
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supporting information
(2020/04/21)
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- Nickel-Catalyzed Direct Alkenylation of Methyl Heteroarenes with Primary Alcohols
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An efficient nickel-catalyzed acceptorless dehydrogenative coupling of methyl-substituted heteroarenes with primary alcohols is achieved using an in situ generated complex of inexpensive NiBr2 and readily available 8-aminoquinoline picolinic amide ligand. The protocol is operationally simple and scalable and furnishes a series of high-value 2-alkenylheteroarenes in good yields (up to 88percent) with exclusive E-selectivity. The reaction proceeds with the release of water and molecular hydrogen, which was analyzed through gas chromatography to validate the reaction mechanism. ?
- Baidya, Mahiuddin,Ramakrishna, Isai,Ramalingam, Bose Muthu
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p. 9819 - 9825
(2019/08/26)
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- Nickel-catalysed direct α-olefination of alkyl substituted N-heteroarenes with alcohols
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Catalytic α-olefination of alkylheteroarenes with primary alcohols via dehydrogenative coupling is presented. A simple nickel catalyst system stabilised by readily available nitrogen ligands enables a series of interesting E-configured vinylarenes (confirmed by X-ray crystal-structure analysis) to be synthesised in good to excellent yields with olefin/alkane selectivity of >20:1. Hydrogen and water are generated as byproducts and quantitative determination of H2 was performed.
- Das, Jagadish,Vellakkaran, Mari,Banerjee, Debasis
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supporting information
p. 7530 - 7533
(2019/07/04)
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- Direct Alkenylation of 2-Methylquinolines with Aldehydes through Synergistic Catalysis of 1,3-Dimethylbarbituric Acid and HOAc
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An efficient and practical direct alkenylation of 2-methylquinolines with aldehydes has been achieved through a novel synergistic organocatalysis. The HOAc- activated 2-methylquiolines undergo a Michael addition to 1,3-dimethylbarbituric acid-activated aldehydes, followed by a retro-Michael addition to release 1,3-dimethylbarbituric acid and the target products. The transformation produced various 2-alkenylquinolines with good to excellent yields and featured mild reaction conditions, atom- and step-economy, good functional group tolerance, and operational simplicity. (Figure presented.).
- Liang, En,Wang, Junqi,Wu, Yinrong,Huang, Liangbin,Yao, Xingang,Tang, Xiaodong
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supporting information
p. 3619 - 3623
(2019/07/10)
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- Manganese-Catalyzed Direct Olefination of Methyl-Substituted Heteroarenes with Primary Alcohols
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Herein, we present the first catalytic direct olefination of methyl-substituted heteroarenes with primary alcohols through an acceptorless dehydrogenative coupling. The reaction is catalyzed by a complex of the earth-abundant transition metal manganese that is stabilized by a bench-stable NNN pincer ligand derived from 2-hydrazinylpyridine. The reaction is environmentally benign, producing only hydrogen and water as byproducts. A large number of E-disubstituted olefins were selectively obtained with high efficiency.
- Barman, Milan K.,Waiba, Satyadeep,Maji, Biplab
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supporting information
p. 9126 - 9130
(2018/07/25)
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- Synthesis of (E)-2-Alkenylazaarenes via Dehydrogenative Coupling of (Hetero)aryl-fused 2-Alkylcyclic Amines and Aldehydes with a Cobalt Nanocatalyst
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To date, the synthesis of (E)-2-alkenylazaarenes via the condensation of 2-methyl N-heteroarenes with aldehydes or their equivalents has been well demonstrated. However, the direct formation of such a class of useful compounds from extensively distributed 2-alkylcyclic amine motifs remains an unresolved goal. Herein, by employing the nitrogen-silica-doped carbon (Vulcan XC-72R) as the support, we have developed a low-loading cobalt nanocatalyst (Co/N-Si-C). The combination of such a catalyst with p-nitrobenzoic acid and molecular O2 exhibits excellent catalytic performance towards the dehydrogenative coupling of (hetero)aryl-fused 2-alkylcyclic amines with aldehydes to afford the (E)-2-alkenylazaarenes. In the reaction, effective capture of the partially dehydrogenated cyclic amine motifs appears to be the key strategy to address the issue of the chemoselectivity. The developed catalytic transformation proceeds with the merits of broad substrate scope, good functional group tolerance, high atom-efficiency, use of an earth-abundant and reusable cobalt catalyst and molecular O2 as a green oxidant, which offers an important basis for the direct conversion of inert cyclic amine units into the functional frameworks.
- Zhou, Changjian,Tan, Zhenda,Jiang, Huanfeng,Zhang, Min
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p. 2887 - 2892
(2018/05/03)
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- Iodine-Catalyzed Direct C-H Alkenylation of Azaheterocycle N-Oxides with Alkenes
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An efficient and regioselective alkenylation of azaheterocycle N-oxides with alkenes catalyzed by iodine under metal- and external oxidant-free reaction conditions has been developed. A variety of (E)-2-styrylazaheterocycles have been produced in moderate
- Zhang, Zhenhao,Pi, Chao,Tong, Heng,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 440 - 443
(2017/02/10)
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- Lanthanum Pentafluorobenzoate-Catalyzed Aerobic Oxidative Olefination of Benzylamines with 2-Methylquinoline through Deamination and C-H Bond Functionalization
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An efficient direct aerobic oxidative olefination of the methyl groups of 2-methylquinolines with benzylamines in the presence of a rare-earth-metal Lewis acid catalyst to give 2-styrylquinolines was successfully developed. Preliminary mechanistic studies revealed that the oxidative olefination reaction proceeds through a Lewis acid-catalyzed 2-methylquinoline-aldehyde condensation and an amine-aldehyde condensation.
- Mao, Dan,Zhu, Xiaoyan,Hong, Gang,Wu, Shengying,Wang, Limin
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supporting information
p. 2481 - 2484
(2016/10/21)
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- Direct alkenylation of alkylazaarenes with aldehydes through C(sp3)-H functionalization under catalytic InCl3 activation
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Under the influence of InCl3 as a Lewis acid catalyst, a methodology on the C(sp3)-H functionalization of alkylazaarenes has been demonstrated through the activation of benzylic C-H bonds towards their addition reaction with the appropriate electrophiles. This methodology was chiefly applied in the direct alkenylation of primary and secondary benzylic C-H bonds of alkylazaarenes with aldehydes. A variety of alkenyl products were afforded in generally good yields including the starting alkenyl intermediate used in the synthesis of montelukast and other related molecules.
- Jamal, Zaini,Teo, Yong-Chua,Lim, Gina Shiyun
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p. 2132 - 2138
(2016/04/19)
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- C(sp3)-H functionalization of methyl azaarenes: a calcium-catalyzed facile synthesis of (E)-2-styryl azaarenes and 2-aryl-1,3-bisazaarenes
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Alkaline earth (Ca2+) catalyzed sp3 C-H functionalization of methyl azaarenes for the synthesis of biologically important (E)-2-styryl azaarenes, 2-aryl-1,3-bisazaarenes and 3,3-bisazaarenyl indolinones has been described. Initially methyl azaarenes react with aryl aldehydes to give β-hydroxy derivatives, which undergo Ca(II) catalyzed thermodynamic elimination to give the styryl azaarenes in a single step. Similarly it may undergo SN1 reaction to give 2-aryl-1,3-bisazaarenes and 3,3-bisazaarenyl indolinones (if isatin used as the electrophile). This green synthetic methodology enjoys the simple reaction procedures, solvent free conditions, step economy, substrate diversity and high yields of the products in short time.
- Yaragorla, Srinivasarao,Singh, Garima,Dada, Ravikrishna
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supporting information
p. 5924 - 5929
(2015/11/02)
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- Metal-free oxidative olefination of primary amines with benzylic C-H bonds through direct deamination and C-H bond activation
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An oxidative olefination reaction between aliphatic primary amines and benzylic sp3 C-H bonds has been achieved using N-bromosuccinimide as catalyst and tert-butyl hydroperoxide as oxidant. The olefination proceeds under mild metal-free conditions through direct deamination and benzylic C-H bond activation, and provides easy access to biologically active 2-styrylquinolines with (E)-configuration. This journal is the Partner Organisations 2014.
- Gong, Liang,Xing, Li-Juan,Xu, Tong,Zhu, Xue-Ping,Zhou, Wen,Kang, Ning,Wang, Bin
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supporting information
p. 6557 - 6560
(2014/08/18)
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- Iron-catalyzed C(sp3)-H functionalization of methyl azaarenes: A green approach to azaarene-substituted α- Or β-hydroxy carboxylic derivatives and 2-alkenylazaarenes
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Bioactive azaarene-substituted lactic acids, β-hydroxy esters, 3-hydroxy-2H-indol-2-ones, and 2-alkenylazaarenes were prepared in moderate-to-excellent yields via C(sp3)-H functionalization of methyl azaarenes with carbonyl compounds in the presence of iron(ii) acetate as an inexpensive, nontoxic, efficient catalyst. The application of this atom-, step-economic, and environmentally friendly method was demonstrated by a gram-scale synthesis of 3-[(E)-2-(7-chloroquinolin-2-yl)vinyl]benzaldehyde, a key intermediate of leukotriene receptor antagonist (Montelukast).
- Pi, Danwei,Jiang, Kun,Zhou, Haifeng,Sui, Yuebo,Uozumi, Yasuhiro,Zou, Kun
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p. 57875 - 57884
(2015/01/08)
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- Oxidative olefination of secondary amines with carbon nucleophiles
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An unprecedented olefination reaction of secondary amines with carbon nucleophiles has been developed through C-N/C-H functionalization under metal-free oxidative conditions. In the presence of a stoichiometric amount of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), a range of secondary N-alkylanilines smoothly underwent oxidative olefination with 2-alkylazaarenes, acetophenone, and malononitrile to give structurally diverse polysubstituted alkenes in moderate to excellent yields with excellent (E) selectivity. Preliminary mechanistic studies revealed that the oxidative olefination reaction proceeds through amine oxidation followed by imine olefination. A range of secondary N-alkylanilines smoothly underwent DDQ-promoted oxidative olefination with 2-alkylazaarenes, acetophenone, and malononitrile to give structurally diverse alkenes in moderate to excellent yields with excellent (E) selectivity. Mechanistically, the reaction proceeds through amine oxidation followed by imine olefination (DDQ = 2,3-dichloro-5,6-dicyano-1,4-benzoquinone). Copyright
- Zhang, Yong-Gang,Xu, Jing-Kun,Li, Xi-Ming,Tian, Shi-Kai
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supporting information
p. 3648 - 3652
(2013/07/19)
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- Iron-catalyzed direct alkenylation of 2-substituted azaarenes with N -sulfonyl aldimines via C-H bond activation
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A novel iron-catalyzed alkenylation of 2-substituted azaarenes through sp3 C-H bond activation has been developed. A favorable E2-elimination is proposed as a key step to cleavage of C-H and C-N bonds for the construction of a C=C bond in high stereoselectivity. This transformation represents an efficient way to synthesize 2-alkenylated azaarenes from simple starting materials.
- Qian, Bo,Xie, Pan,Xie, Yinjun,Huang, Hanmin
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supporting information; experimental part
p. 2580 - 2583
(2011/06/25)
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