- Equivalent Loading of Directed Arenes in Pd(II)-Catalyzed Oxidative Cross-Coupling of Aryl C-H Bonds at Room Temperature
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The unsymmetrical biaryls (Ar1-Ar2) produced by the catalytic cross-couplings of aryl halides (Ar1-halo) with aryl metallics (Ar2-M) in the loading ratio of 1:1 are popular in chemical synthesis. In contrast, there has been less precedence on the same biaryls produced effectively from two normal aryl C-H bonds with equivalent loading. Here, we report that, in a palladium/oxidant/acid catalytic system at room temperature, one arene (Ar1-H, 1 equiv) can highly selectively couple with the other one (Ar2-H, 1 equiv) to afford the target Ar1-Ar2 just by controlling the directing groups and the substituted groups on their phenyl rings. The utility of this one-one cross-coupling is also demonstrated by synthesis of a few bioactive molecules.
- Mei, Chong,Zhao, Mengdi,Lu, Wenjun
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p. 2714 - 2733
(2021/02/01)
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- Room temperature clickable coupling electron deficient amines with sterically hindered carboxylic acids for the construction of amides
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A method for the synthesis of difficult-to-access amides was developed through the coupling of sterically hindered carboxylic acids and electron deficient amines via SO2F2-mediated dehydration. The method feathers with broad substrate scope, mild conditions, excellent functional group compatibility and high yields.
- Liu, Jing,Wang, Shi-Meng,Qin, Hua-Li
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supporting information
(2020/11/13)
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- Exogenous Photosensitizer-, Metal-, and Base-Free Visible-Light-Promoted C-H Thiolation via Reverse Hydrogen Atom Transfer
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Visible-light-driven, intramolecular C(sp2)-H thiolation has been achieved without addition of a photosensitizer, metal catalyst, or base. This reaction induces the cyclization of thiobenzanilides to benzothiazoles. The substrate absorbs visible light, and its excited state undergoes a reverse hydrogen-atom transfer (RHAT) with 2,2,6,6-tetramethylpiperidine N-oxyl to form a sulfur radical. The addition of the sulfur radical to the benzene ring gives an aryl radical, which then rearomatizes to benzothiazole via RHAT.
- Xu, Ze-Ming,Li, Hong-Xi,Young, David James,Zhu, Da-Liang,Li, Hai-Yan,Lang, Jian-Ping
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supporting information
p. 237 - 241
(2019/01/10)
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- Photocatalytic Oxidative C-H Thiolation: Synthesis of Benzothiazoles and Sulfenylated Indoles
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We report studies on the photocatalytic formation of C-S bonds to form benzothiazoles via an intramolecular cyclization and sulfenylated indoles via an intermolecular reaction. Cyclic voltammetry (CV) and density functional theory studies suggest that benzothiazole formation proceeds via a mechanism that involves an electrophilic sulfur radical, while the indole sulfenylation likely proceeds via a nucleophilic sulfur radical adding into a radical cationic indole. These conditions were successfully extended to several thiobenzamides and indole substrates.
- Aceves, Ernesto Millan,Albright, Samuel T.,Cedano, Mario R.,Dinh, Andrew N.,Gustafson, Jeffrey L.,Nguyen, Ashley D.,Smith, Diane K.
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supporting information
p. 1648 - 1655
(2019/08/26)
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- A para-C–H Functionalization of Aniline Derivatives via In situ Generated Bulky Hypervalent Iodinium Reagents
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A practical para-C-H functionalization of aniline derivatives has been developed using an in situ generated bulky hypervalent iodinium reagent. Para-iodo, bromo, chloro, nitro, trifluormethyl aniline derivatives can be obtained efficiently, in many cases in 10 min in a transition metal-free manner. Medicinal chemicals or intermediates can be purified without column chromatography or recrystallization, which significantly reduces the waste and simplifies the work-up process.
- Tian, Chao,Yao, Xu,Ji, Weizhe,Wang, Qian,An, Guanghui,Li, Guangming
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supporting information
p. 5972 - 5979
(2018/11/23)
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- Palladium(II)-Catalyzed Oxidative Homo- and Cross-Coupling of Aryl ortho -sp2 C-H Bonds of Anilides at Room Temperature
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The preparation of secondary 2,2'-bisanilides has been successfully achieved through an oxidative coupling of aryl ortho-sp2 C-H bonds of anilides in the presence of catalytic Pd(OAc)2 and K2S2O8 as an oxidant in MsOH/CF3CO2H (TFA) at room temperature (25 °C). The aromatic rings of anilides substituted by various electron-donating or electron-withdrawing groups are tolerant in these coupling reactions.
- Mei, Chong,Lu, Wenjun
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p. 4812 - 4823
(2018/04/26)
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- Oxidative C?H/C?H Cross-Coupling Reactions between N-Acylanilines and Benzamides Enabled by a Cp*-Free RhCl3/TFA Catalytic System
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By making use of a dual-chelation-assisted strategy, a completely regiocontrolled oxidative C?H/C?H cross-coupling reaction between an N-acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step-economic and highly efficient pathway to 2-amino-2′-carboxybiaryl scaffolds from readily available substrates. A Cp*-free RhCl3/TFA catalytic system was developed to replace the [Cp*RhCl2]2/AgSbF6 system generally used in oxidative C?H/C?H cross-coupling reactions between two (hetero)arenes (Cp=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl3/TFA system avoids the use of the expensive Cp* ligand and AgSbF6. As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield.
- Shi, Yang,Zhang, Luoqiang,Lan, Jingbo,Zhang, Min,Zhou, Fulin,Wei, Wenlong,You, Jingsong
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supporting information
p. 9108 - 9112
(2018/07/25)
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- Zwitterionic-Salt-Catalyzed Site-Selective Monobromination of Arenes
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A zwitterionic-salt-catalyzed electrophilic monobromination of arenes with high regioselectivity has been developed. Under mild reaction conditions, a wide range of monobrominated aromatic compounds can be obtained in excellent yields. The reaction can be operated using an extremely low catalyst loading (0.05 mol %) with the inexpensive brominating agent N-bromosuccinimide. The versatility of this catalytic protocol has been demonstrated by the scale-up reaction with a 0.01 mol % catalyst loading to provide the selectively halogenated compound in quantitative yield.
- Xiong, Xiaodong,Tan, Fei,Yeung, Ying-Yeung
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supporting information
p. 4243 - 4246
(2017/08/23)
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- Combining Eosin y with Selectfluor: A Regioselective Brominating System for Para-Bromination of Aniline Derivatives
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A mild, metal-free, and absolutely para-selective bromination of aniline derivatives has been developed in excellent yields, wherein the organic dye Eosin Y is employed as the bromine source in company with Selectfluor. Neither air nor moisture sensitive, this facile reaction proceeds smoothly at room temperature and completes within a short time. Mechanistic studies indicate a radical pathway; therefore, the existence of an in situ generated brominating reagent, "Selectbrom", is postulated, which may reasonably account for the unique regioselectivity for the para-bromination of N-acyl- as well as N-sulfonylanilines.
- Huang, Binbin,Zhao, Yating,Yang, Chao,Gao, Yuan,Xia, Wujiong
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supporting information
p. 3799 - 3802
(2017/07/26)
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- Rhodium(III)-catalysed, redox-neutral C(sp2)-H alkenylation using pivalimide as a directing group with internal alkynes
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In the presence of [RhCp?Cl2]2, N-pivaloyl anilines react with internal alkynes to give the corresponding 2-alkenylpivalimides under redox neutral conditions through C-H activation. This redox neutral hydroarylation, which does not require an external organic acid, unlocks a regioselective synthetic route to 2-alkenyl anilines and is generally applicable to diversely substituted electron rich and electron poor pivalimides.
- Kathiravan, Subban,Nicholls, Ian A.
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supporting information
p. 1 - 4
(2016/12/23)
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- A unified strategy for silver-, base-, and oxidant-free direct arylation of C-H bonds
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Here, we report a dual catalytic approach for room temperature direct arylation of C-H bonds with aryldiazonium salts as a simple aryl group donor, also working as an internal oxidant via C-N2 bond cleavage. This unified strategy has been achieved by the synergistic combination of visible-light metal-free photoredox and palladium catalysis under silver-, base- and/or additive-free conditions. The broad substrate scope, functional group tolerance, excellent regioselectivity and redox-neutral conditions of this process make it attractive for the effective synthesis of a wide range of important N-heterocyclic commodities such as dibenzo[b,d]azepine, carbazole and phenanthridine.
- Sahoo, Manoj K.,Midya, Siba P.,Landge, Vinod G.,Balaraman, Ekambaram
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supporting information
p. 2111 - 2117
(2017/07/24)
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- Amine Activation: Synthesis of N-(Hetero)arylamides from Isothioureas and Carboxylic Acids
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A novel method for N-(hetero)arylamide synthesis based on rarely explored amine activation, rather than classical acid activation, is reported. The activated amines are easily prepared using a three-component reaction with commercial reagents. The new method shows a broad scope including challenging amides not (efficiently) accessible via classical protocols.
- Zhu, Yan-Ping,Sergeyev, Sergey,Franck, Philippe,Orru, Romano V. A.,Maes, Bert U. W.
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supporting information
p. 4602 - 4605
(2016/09/28)
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- Palladium-Catalysed Synthesis of α-(Trifluoromethyl)styrenes by Means of Directed C-H Bond Functionalization
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We report the first introduction of 2-bromo-3,3,3-trifluoropropene (BTP) by directed C-H bond functionalization. The developed method gives straightforward access to α-(trifluoromethyl)styrene derivatives without prior prefunctionalization of the substrates. This palladium-catalysed transformation was applied to a broad range of substrates, and the corresponding trifluoromethylated products were obtained in good yields. This approach represents an alternative pathway to the classical method previously used to access such molecules.
- Zhao, Qun,Besset, Tatiana,Poisson, Thomas,Bouillon, Jean-Philippe,Pannecoucke, Xavier
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- Imidazolium Salt Catalyzed para -Selective Halogenation of Electron-Rich Arenes
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A highly para-selective halogenation of arenes bearing coordinating groups in the presence of a dimidazolium salt as a catalyst is reported. A series of electron-rich p-haloarenes were prepared in good yields and good to excellent selectivities. We also propose a plausible mechanism for the catalytic reaction.
- Chen, Jie,Xiong, Xiaoyu,Chen, Zenghua,Huang, Jianhui
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supporting information
p. 2831 - 2834
(2015/12/18)
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- PYRAZOLE-BASED COMPOUND AND ORGANIC LIGHT EMITTING DEVICE USING THE SAME
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The present invention relates to a pyrazole-based compound and an organic light emitting device comprising the same. The organic light emitting device comprises a positive electrode, a negative electrode, and one or more organic layers formed between the positive electrode and the negative electrode, wherein the organic layers comprise the pyrazole-based compound.COPYRIGHT KIPO 2015
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Paragraph 0106-0109
(2016/10/08)
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- Comparative Catalytic Activity of Group 9 [CpMIII] Complexes: Cobalt-Catalyzed C-H Amidation of Arenes with Dioxazolones as Amidating Reagents
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A procedure for the [CpCoIII]-catalyzed direct C-H amidation of arenes with dioxazolone has been developed. This reaction proceeds under straightforward and mild conditions with a broad range of substrates, including anilides. A comparative study on the catalytic activity of Group 9 [{CpMCl2}2] complexes revealed the unique efficiency of the cobalt catalyst. Pick of the bunch: A variety of arenes, including anilides, underwent direct C-H amidation with dioxazolones in the presence of a cobalt catalyst with a Cp? ligand under mild and straightforward reaction conditions (see scheme; Piv=pivaloyl). A comparative study of Group 9 [CpMIII] complexes revealed the unique ability of the cobalt catalyst to promote this transformation efficiently.
- Park, Juhyeon,Chang, Sukbok
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supporting information
p. 14103 - 14107
(2016/01/25)
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- CuCl-catalyzed ortho trifluoromethylation of arenes and heteroarenes with a pivalamido directing group
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The CuCl catalyzed direct trifluoromethylation of sp2 C-H bonds has been realized, using the Togni reagent as the CF3 source. This reaction achieves the goal of regio-selectively converting C-H into C-CF 3 with ecological and readily available starting materials.
- Cai, Shangjun,Chen, Chao,Sun, Zelin,Xi, Chanjuan
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supporting information
p. 4552 - 4554
(2013/06/04)
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- Facile amide bond formation from carboxylic acids and isocyanates
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Chemical equations presented. A wide variety of carboxylic acids in the form of their salts condense with aryl isocyanates at room temperature with loss of carbon dioxide to give the corresponding amides in high yield. Application of the reaction to acyl isocyanates gives unsymmetric imides. The reaction is compatible with hydroxyl groups and both Fmoc and Boc protecting groups for amines and is applicable to aliphatic, aromatic, and heteroaromatic acids.
- Sasaki, Kaname,Crich, David
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supporting information; experimental part
p. 2256 - 2259
(2011/06/22)
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- Trifluoromethyl-promoted homocamptothecins: Synthesis and biological activity
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The homocamptothecin (hCPT) represents a new class of topoisomerase inhibitor which combines enhanced plasma stability and strong antitumor activity. Fluorine imparts desirable characteristics to drugs by modulating both the pharmacokinetics and pharmacodynamic properties of a drug. Therefore, in an attempt to improve the antitumor activity of homocamptothecins, seven new 7-trifluoromethylated homocamptothecin derivatives were prepared by proline-catalyzed Friedlander annulation. The antitumor activity in vitro and in vivo on cancer cell lines, and inhibitory properties of topoisomerase I-mediated DNA cleavage of compounds 6c and 8b were evaluated. Several of these trifluoromethylated hCPT derivatives (such as 6a, 6b and 6c) possessed higher in vitro antitumor activity than topotecan (TPT). Especially, the compound 6c showed effective in vivo antitumor activity comparable to that of TPT.
- Zhu, Lingjian,Miao, Zhenyuan,Sheng, Chunquan,Guo, Wei,Yao, Jianzhong,Liu, Wenfeng,Che, Xiaoying,Wang, Wenya,Cheng, Pengfei,Zhang, Wannian
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experimental part
p. 2726 - 2732
(2010/08/07)
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- An alternative route for synthesis of o-trifluoroacetylanilines as useful fluorine-containing intermediates
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A series of o-trifluoroacetyl aniline derivatives were synthesized in three steps. In this method, we first utilized trifluoroacetic anhydride to introduce trifluoroacetyl group to the ortho position of aniline with higher yield than that of some previously reported methods. In addition, the procedure is shown to be highly regiospecific. This type of compounds can be used as the key intermediates in the preparation of a variety of inhibitors of HIV reverse transcriptase which is an important pharmacological target of many anti-AIDS agents.
- Zhu, Lingjian,Miao, Zhenyuan,Sheng, Chunquan,Yao, Jianzhong,Zhuang, Chunlin,Zhang, Wannian
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experimental part
p. 800 - 804
(2010/09/04)
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- Oxidizing hair coloring agents containing 2,5-diamino-1-phenylbenzene derivatives and novel 2,5-diamino-1-phenylbenzene derivatives
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The object of the present patent application are agents for the oxidative coloring of keratin fibers, particularly hair, based on a developer-coupler combination, characterized in that they contain as the developer at least one 2,5-diamino-1-phenylbenzene derivative of general formula and novel 2,5-diamino-1-phenylbenzene derivatives of formula (I) wherein at least one of the R1 to R10 radicals is different from hydrogen.
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