- Coupling of Challenging Heteroaryl Halides with Alkyl Halides via Nickel-Catalyzed Cross-Electrophile Coupling
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Despite their importance, the synthesis of alkylated heterocycles from the cross-coupling of Lewis basic nitrogen heteroaryl halides with alkyl halides remains a challenge. We report here a general solution to this challenge enabled by a new collection of ligands based around 2-pyridyl-N-cyanocarboxamidine and 2-pyridylcarboxamidine cores. Both primary and secondary alkyl halides can be coupled with 2-, 3-, and 4-pyridyl halides as well as other more complex heterocycles in generally good yields (41 examples, 69% ave yield).
- Hansen, Eric C.,Li, Changfeng,Yang, Sihang,Pedro, Dylan,Weix, Daniel J.
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- Micelle enabled C(sp2)-C(sp3) cross-electrophile coupling in waterviasynergistic nickel and copper catalysis
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A robust and sustainable C(sp2)-C(sp3) cross-electrophile coupling was developedvianickel/copper synergistic catalysis under micellar conditions. This protocol provided a general method to access alkylated arenes with good to excellent yields on a very large scale.
- Ye, Ning,Wu, Bin,Zhao, Kangming,Ge, Xiaobin,Zheng, Yu,Shen, Xiaodong,Shi, Lei,Cortes-Clerget, Margery,Regnier, Morgan Louis,Parmentier, Michael,Gallou, Fabrice
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supporting information
p. 7629 - 7632
(2021/08/09)
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- A Practical Method for Continuous Production of sp3-Rich Compounds from (Hetero)Aryl Halides and Redox-Active Esters
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A practically useful coupling reaction between aromatic halides and redox-active esters was realized by nickel catalysis through the use of a packed zinc bed column in continuous flow. Multiple reuse of the column showed a negligible decrease in efficiency, affording high space/time yields. A wide range of substrates, including a number of heteroaryl halides and polyfunctional materials were coupled in generally good yields. Longer-time and larger-scale experiments further demonstrates the robustness of the system.
- Watanabe, Eiichi,Chen, Yiding,May, Oliver,Ley, Steven V.
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supporting information
p. 186 - 191
(2019/12/24)
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- Direct arylation of strong aliphatic C–H bonds
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Despite the widespread success of transition-metal-catalysed cross-coupling methodologies, considerable limitations still exist in reactions at sp3-hybridized carbon atoms, with most approaches relying on prefunctionalized alkylmetal or bromide coupling partners1,2. Although the use of native functional groups (for example, carboxylic acids, alkenes and alcohols) has improved the overall efficiency of such transformations by expanding the range of potential feedstocks3–5, the direct functionalization of carbon–hydrogen (C–H) bonds—the most abundant moiety in organic molecules—represents a more ideal approach to molecular construction. In recent years, an impressive range of reactions that form C(sp3)–heteroatom bonds from strong C–H bonds has been reported6,7. Additionally, valuable technologies have been developed for the formation of carbon–carbon bonds from the corresponding C(sp3)–H bonds via substrate-directed transition-metal C–H insertion8, undirected C–H insertion by captodative rhodium carbenoid complexes9, or hydrogen atom transfer from weak, hydridic C–H bonds by electrophilic open-shell species10–14. Despite these advances, a mild and general platform for the coupling of strong, neutral C(sp3)–H bonds with aryl electrophiles has not been realized. Here we describe a protocol for the direct C(sp3) arylation of a diverse set of aliphatic, C–H bond-containing organic frameworks through the combination of light-driven, polyoxometalate-facilitated hydrogen atom transfer and nickel catalysis. This dual-catalytic manifold enables the generation of carbon-centred radicals from strong, neutral C–H bonds, which thereafter act as nucleophiles in nickel-mediated cross-coupling with aryl bromides to afford C(sp3)–C(sp2) cross-coupled products. This technology enables unprecedented, single-step access to a broad array of complex, medicinally relevant molecules directly from natural products and chemical feedstocks through functionalization at sites that are unreactive under traditional methods.
- Perry, Ian B.,Brewer, Thomas F.,Sarver, Patrick J.,Schultz, Danielle M.,DiRocco, Daniel A.,MacMillan, David W. C.
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- Iron-Catalyzed Isopropylation of Electron-Deficient Aryl and Heteroaryl Chlorides
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Traditional methods for the preparation of secondary alkyl-substituted aryl and heteroaryl chlorides challenge both selectivity and functional group tolerance. This contribution describes the use of statistical design of experiments to develop an effective procedure for the preparation of isopropyl-substituted (hetero)arenes with minimal isopropyl to n-propyl isomerization. The reaction tolerates electronically diverse aryl chloride coupling partners, with excellent conversion observed for strongly electron-deficient aromatic rings, such as esters and amides. Electron-rich systems, including methyl- and methoxy-substituted aryl chlorides, were found to be less reactive. Furthermore, the reaction was found to be most successful when heteroaryl chlorides were submitted to the cross-coupling protocol. By mapping substituent effects on reaction selectivity, we were able to show that electron-deficient aryl chlorides are essential for efficient coupling, and use electronic structure calculations to predict the likelihood of successful coupling through the estimation of the electron affinity of each aryl chloride. Moderate isolated yields were achieved with selected aryl chlorides, and moderate to good isolated yields were obtained for all the heteroaryl chlorides coupled. Excellent selectivity was observed when a 2,6-dichloroquinoline was used, allowing mono-substitution on a challenging substrate. (Figure presented.).
- Sanderson, James N.,Dominey, Andrew P.,Percy, Jonathan M.
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p. 1007 - 1017
(2017/03/27)
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- Remote Oxidation of Aliphatic C-H Bonds in Nitrogen-Containing Molecules
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Nitrogen heterocycles are ubiquitous in natural products and pharmaceuticals. Herein, we disclose a nitrogen complexation strategy that employs a strong Bronsted acid (HBF4) or an azaphilic Lewis acid (BF3) to enable remote, non-directed C(sp3)-H oxidations of tertiary, secondary, and primary amine- and pyridine-containing molecules with tunable iron catalysts. Imides resist oxidation and promote remote functionalization.
- Howell, Jennifer M.,Feng, Kaibo,Clark, Joseph R.,Trzepkowski, Louis J.,White, M. Christina
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supporting information
p. 14590 - 14593
(2015/12/08)
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- Efficient cross-coupling of secondary alkyltrifluoroborates with aryl chlorides-reaction discovery using parallel microscale experimentation
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Microscale parallel experimentation was used to discover three catalyst systems capable of coupling secondary organotrifluoroborates with sterically and electronically demanding aryl chlorides and bromides. The ensuing results represent the first comprehensive study of alkylboron coupling to aryl chlorides and, in particular, using secondary alkylboron partners. A ligand-dependent β-hydride elimination/reinsertion mechanism was implicated in the cross-coupling of more hindered substrates, leading to isomeric mixtures of coupled products in some cases. Copyright
- Dreher, Spencer D.,Dormer, Peter G.,Sandrock, Deidre L.,Molander, Gary A.
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supporting information; body text
p. 9257 - 9259
(2009/02/02)
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- Thioformamide derivatives
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Thioformamide compounds of formula (I) are disclosed in which R is alkyl, Y is methylene, ethylene or a direct bond, A is optionally substituted phenyl or pyridyl, R1 is hydrogen and R2 is N-alkylsulphonyl-, N-phenylsulphonyl-N'-alky
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- Thioformamide derivatives
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Thioformamide derivatives of the formula: STR1 wherein: R represents alkyl; A represents an optionally substituted phenyl or heteroaromatic group; R1 represents hydrogen, alkyl, cyano, carboxyl, formyl, carbamoyl, alkoxycarbonyl or a group --(C
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- Reactions of 1,4-Bis(trimethylsilyl)-1,4-dihydropyridines with Carbonyl Compounds: A New Method for Regioselective Synthesis of 3-Alkylpyridines
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A new method for the alkyl group introduction at the 3-position of pyridines is described: Reductive disilylation of pyridine, its 2-methyl, 3-methyl, and 4-methyl derivatives affords the corresponding 1,4-disilyl-1,4-dihydropyridines.Tn the presence of a catalytic amount of tetrabutylammonium fluoride, these dihydropyridines smoothly react with a variety of aldehydes and ketones to give 3-alkylpyridines.
- Tsuge, Otohiko,Kanemasa, Shuji,Naritomi, Toshio,Tanaka, Junji
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p. 1497 - 1504
(2007/10/02)
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- PHOTOCHEMICAL GENERATION OF ALIPHATIC RADICALS FROM BENZOPHENONE OXIME ESTERS: SIMPLE SYNTHESIS OF ALKYLBENZENES AND ALKYLPYRIDINES
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Photolysis of benzophenone oxime esters, prepared with aliphatic carboxylic acids and benzophenone oxime, in benzene and pyridine generates various primary, secondary and tertiary aliphatic radicals selectively, and corresponding alkylbenzenes and alkylpyridines are produced in good yields, respectively.
- Hasebe, Masato,Tsuchiya, Takashi
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p. 3239 - 3242
(2007/10/02)
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- REGIOSELECTIVE ALKYL GROUP INTRODUCTION AT THE 3-POSITION OF PYRIDINE VIA 1,4-BIS(TRIMETHYLSILYL)-1,4-DIHYDROPYRIDINE
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The reaction of 1,4-bis(trimethylsilyl)-1,4-dihydropyridine with aldehydes and ketones in the presence of tetrabutylammonium fluoride offers a convenient method for the preparation of 3-alkylpyridines.
- Tsuge, Otohiko,Kanemasa, Shuji,Naritomi, Toshio,Tanaka, Junji
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p. 1255 - 1258
(2007/10/02)
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