- Annulation of β-Enaminonitriles with Alkynes via RhIII-Catalyzed C-H Activation: Direct Access to Highly Substituted 1-Naphthylamines and Naphtho[1,8- bc]pyridines
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A Cp?RhIII-catalyzed oxidative annulation of β-enaminonitriles with alkynes was reported to achieve selective synthesis of polysubstituted 1-naphthylamines and naphtho[1,8-bc]pyridines via multiple C-H activations. Assisted by a naphthylamine NH2 group, 1-naphthylamines were also readily cyclized to produce naphtho[1,8-bc]pyridines. In addition, the obtained naphtho[1,8-bc]pyridine derivatives exhibit intense fluorescence in the solid state.
- Wang, Haili,Xu, Hong,Li, Bin,Wang, Baiquan
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- Ruthenium-Catalyzed meta-Selective C?H Nitration of Biologically Important Aryltetrazoles
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The first example of tetrazole-directed meta-selective C?H nitration is described. This transformation provided a straightforward approach for the synthesis of biologically important m-nitroaryltetrazoles in moderate to excellent yields with good functional group compatibility. In addition, new metallo-β-lactamase inhibitors were obtained by further transformation of the synthesized m-nitroaryltetrazoles. (Figure presented.).
- Chen, Jian,Huang, Tianle,Gong, Xinrui,Yu, Zhu-Jun,Shi, Yuesen,Yan, Yu-Hang,Zheng, Yang,Liu, Xuexin,Li, Guo-Bo,Wu, Yong
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supporting information
p. 2984 - 2989
(2020/06/08)
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- Palladium-Catalyzed Late-Stage Direct Arene Cyanation
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Methods for direct benzonitrile synthesis are sparse, despite the versatility of cyano groups in organic synthesis and the importance of benzonitriles for the dye, agrochemical, and pharmaceutical industries. We report the first general late-stage aryl C–H cyanation with broad substrate scope and functional-group tolerance. The reaction is enabled by a dual-ligand combination of quinoxaline and an amino acid-derived ligand. The method is applicable to direct cyanation of several marketed small-molecule drugs, common pharmacophores, and organic dyes. Benzonitriles are some of the most versatile building blocks for organic synthesis, in particular in the pharmaceutical industry, but general methods to make them by direct C–H functionalization are unknown. In this issue of Chem, Ritter and coworkers describe a late-stage aryl C–H cyanation with broad substrate scope and functional-group tolerance, enabled by a palladium-dual-ligand catalyst system. The reaction may serve for the late-stage modification of drug candidates. Aryl nitriles constitute an important class of organic compounds that are widely found in natural products, pharmaceuticals, agricultural chemicals, dyes, and materials. Moreover, nitriles are versatile building blocks to access numerous other important molecular structure groups. However, no general method for direct aromatic C–H cyanation is known. All approaches to date require either an appropriate directing group or reactive electron-rich substrates, such as indoles, which limit their synthetic applications. Here we describe an undirected, palladium-catalyzed late-stage aryl C–H cyanation reaction for the synthesis of complex aryl nitriles that would otherwise be more challenging to produce. The wide substrate scope and good functional-group tolerance of this reaction provide direct and quick access to structural diversity for pharmaceutical and agrochemical development.
- Zhao, Da,Xu, Peng,Ritter, Tobias
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supporting information
p. 97 - 107
(2019/01/21)
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- Rhodium-catalyzed synthesis of 1-(acylamino)isoquinolines through direct annulative coupling of 3-aryl-1,2,4-oxadiazoles with alkynes
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A Rh(III)-catalyzed direct annulative coupling of 3-aryl-1,2,4-oxadiazoles with alkynes through coordination-assisted CH activation is developed, providing a facile route to 1-(acylamino)isoquinolines. The oxadiazole ring acts as a directing group as well as an internal oxidant.
- Nishii, Yuji,Bachon, Anne-Katrin,Moon, Sanghun,Bolm, Carsten,Miura, Masahiro
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supporting information
p. 1347 - 1349
(2017/08/14)
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- Cobalt(III)-Catalyzed Oxadiazole-Directed C-H Activation for the Synthesis of 1-Aminoisoquinolines
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Aromatic heterocycles have been identified as effective directing groups (DGs) in C-H functionalization but can be retained as undesired bulky substituents in the final products. Herein, we report a Co(III)-catalyzed 1-aminoisoquinoline synthesis strategy based on oxadiazole-directed aromatic C-H coupling with alkynes and a subsequent redox-neutral C-N cyclization reaction. This labile N-O bond-based protocol has allowed the toleration of a broad range of functional groups.
- Yang, Fan,Yu, Jiaojiao,Liu, Yun,Zhu, Jin
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supporting information
p. 2885 - 2888
(2017/06/07)
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- Manganese-Catalyzed ortho-C?H Alkenylation of Aromatic N?H Imidates with Alkynes: Versatile Access to Mono-Alkenylated Aromatic Nitriles
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So far, the direct C?H alkenylation of aromatic nitriles with alkynes has not been achieved. Herein, we discribe the first manganese-catalyzed C?H alkenylation of aromatic N?H imidates to access mono-alkenylated aromatic nitriles. The reaction is accelerated by the presence of a catalytic amount of sodium pivalate. This protocol is also highlighted by the simple catalytic system, good compatibility of functional groups, and excellent mono-/dialkenylation selectivity as well as E/Z stereoselectivity. (Figure presented.).
- Yang, Xiaoxu,Jin, Xiqing,Wang, Congyang
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supporting information
p. 2436 - 2442
(2016/08/16)
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- Rhodium-catalyzed olefination of aryl tetrazoles via direct C-H bond activation
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Rh(III)-catalyzed direct olefination reaction via aromatic C-H bond activation is described using tetrazole as the directing group. This reaction provides a straightforward way for the synthesis of ortho-alkenyl aryl tetrazoles. Various functional groups tolerate the reaction conditions and afford the corresponding products in moderate to excellent yields.
- Wang, Liang,Wu, Wenting,Chen, Qun,He, Mingyang
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supporting information
p. 7923 - 7926
(2015/01/09)
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- Manganese-catalyzed dehydrogenative [4+2] annulation of N-H imines and alkynes by C-H/N-H activation
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Described herein is a manganese-catalyzed dehydrogenative [4+2] annulation of N-H imines and alkynes, a reaction providing highly atom-economical access to diverse isoquinolines. This transformation represents the first example of manganese-catalyzed C-H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition-metal-catalyzed C-H activation. Mechanistic studies revealed the five-membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle.
- He, Ruoyu,Huang, Zhi-Tang,Zheng, Qi-Yu,Wang, Congyang
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supporting information
p. 4950 - 4953
(2014/05/20)
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- The synthesis and structures of deuterium-labeled 5-substituted 1H-tetrazoles
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The synthesis and crystal structures of deuterium-labeled 5-substituted 1H-tetrazoles, 5-[2H5]phenyl-1H-tetrazole (I), 5-[ 2H7]tolyl-1H-tetrazole (II), and 5-[2H 7]benzyl-1H-tetrazole (III)
- Zhao, Hong
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p. 293 - 296
(2008/12/22)
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- Retro-Diels-Alder fragmentation of 2,5,6-triphenyl-3,4-didehydropyridine generated by flash vacuum pyrolysis at 900°C
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2,5,6-Triphenyl-3,4-didehydropyridine, generated by FVP of the corresponding 3,4-dicarboxylic anhydride (6) at 900°C/0.02 mm, undergoes mainly retro-Diels-Alder cleavage to 1,4-diphenylbutadiyne and benzonitrile.
- Brown,Choi,Eastwood
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p. 3787 - 3790
(2007/10/02)
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- A Linear Free Energy Relationship for an Equilibrium Isotope Effect
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The solution electron affinities of a series of monosubstituted phenyl-d5 benzenes relative to their perprotiated analogues were measured via electron paramagnetic resonance studies.The equilibrium constant for the electron transfer X-C6H5.- + X-C6D5 X-C6H5 + X-C6D5.-, where X = H, C6D5, CN, NO2, OCH3, tert-butyl, was found to be less than unity for all cases.However, this equilibrium constant is closer to unity for those systems where the substituent is electron withdrawing in nature, and it deviates further from unity for those systems that have an electron-donating group as the substituent.A linear free energy relationship was found, and the positive ρ value (0.34) is presumably due to the fact that there is a smaller excess charge and spin density from the antibonding electron in the area of the molecule where isotopic substitution takes place, for those systems where the ? value of the substituent is positive.
- Stevenson, Gerald R.,Wehrmann, Glenn C.,Reiter, Richard C.
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p. 901 - 905
(2007/10/02)
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