- Efficient copper catalysts for C[sbnd]H bond arylation under microwave heating: Direct access to multi-substituted pivanilides
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We herein describe a parallel comparison between homogeneous and heterogeneous copper catalysts for microwave-assisted direct C[sbnd]H bond arylation. These catalytic systems feature enhanced catalytic activities, unique bulky ligand/base effects, mild co
- Yang, Hyun Ji,Mathew, Bijoy P.,Oh, Dong Gun,Myung, Kyungjae,Kwak, Ja Hun,Hong, Sung You
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- Benzylidene succinimides as 3C synthons for the asymmetric tandem Mannich reaction/transamidation of cyclic trifluoromethyl ketimines to obtain F3C-containing polycyclic dihydroquinazolinones
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By taking advantage of benzylidene succinimides as a new class of 3C synthons, a highly diastereo- and enantioselective tandem Mannich reaction/transamidation has been established by reacting them with cyclic trifluoromethylN-acyl ketimines. Using aCinchonaalkaloid-derived squaramide as the catalyst, the tandem reaction proceeded smoothly under mild conditions and afforded a range of F3C-containing chiral polycyclic dihydroquinazolinones with excellent results (up to 99% yield, all cases >20?:?1 dr, up to 99% ee).
- Zhang, Xia-Yan,Dou, Pei-Hao,Lu, Wen-Ya,You, Yong,Zhao, Jian-Qiang,Wang, Zhen-Hua,Yuan, Wei-Cheng
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supporting information
p. 2927 - 2930
(2021/03/23)
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- Metal-free transamidation of benzoylpyrrolidin-2-one and amines under aqueous conditions
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N-Acyl lactam amides, such as benzoylpyrrolidin-2-one, benzoylpiperidin-2-one, and benzoylazepan-2-one reacted with amines in the presence of DTBP and TBAI to afford the transamidated products in good yields. The reactions were conducted under aqueous conditions and good functional group tolerance was achieved. Both aliphatic and aromatic primary amines displayed good activity under metal-free conditions. A radical reaction pathway is proposed.
- Joseph, Devaneyan,Lee, Sunwoo,Park, Myeong Seong
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supporting information
p. 6227 - 6232
(2021/07/28)
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- Ligand-free copper-catalyzed direct amidation of diaryliodonium salts using nitriles as amidation reagents
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An efficient and practical methodology for the synthesis of N-arylamides has been developed via copper-catalyzed amidation of diaryliodonium salts with nitriles. Various substituted aryl nitriles and aliphatic nitriles could be applied in the reaction, providing a series of N-arylated amides in moderate to good yields. This procedure provides an alternative route for the synthesis of various N-arylamides. A proposed mechanism based on control experiments is also presented.
- Cheng, Hui-cheng,Guo, Penghu,Ji, Hong-bing,Ma, Jiao-li,Zhang, Yang,Zhou, Lichao,Zhou, Xuming
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supporting information
(2021/04/19)
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- Preparation method of N-aryl amide compound
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The invention discloses a preparation method of an N-aryl amide compound, which comprises the following steps: (1) putting diaryliodonium salt and Cu(OAc)2 into a Schlenk tube provided with a magneticstirring rod; (2) sequentially adding DCE, H2O and nitrile by using an injector, sealing the Schlenk tube, and stirring for reaction at 80 DEG C; (3) cooling the obtained solution to room temperature, and performing extraction with EtOAc; and combining organic layers, performing washing with saline water, and performing drying with anhydrous Na2SO4; and (4) removing volatile matters in vacuum, and purifying residues through column chromatography to obtain the N-aryl amide compound. Through a large number of experiments, a substrate with a simple structure is screened, the reaction conditionsare mild, the yield is high, the pollution is small, and the application prospect is wide.
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Paragraph 0040-0045
(2020/07/13)
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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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- General rhodium-catalyzed oxidative cross-coupling reactions between anilines: Synthesis of unsymmetrical 2,2′-diaminobiaryls
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Described herein is a dual chelation-assisted RhCl3-catalyzed oxidative C-H/C-H cross-coupling reaction of aniline derivatives. The highlight of this methodology is the chemo- and regioselective cross-coupling between electronically similar substrates, which represents a highly challenging task in oxidative Ar-H/Ar-H cross-coupling reactions. Furthermore, this Cp?-free catalytic reaction tolerates a range of functional groups and requires only a low molar ratio of coupling partners. These features expedite the synthesis of unsymmetrical 2,2′-diaminobiaryls.
- Shi, Yang,Liu, Jiahui,Yang, Yudong,You, Jingsong
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supporting information
p. 5475 - 5478
(2019/05/16)
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- Acyl-Directed ortho-Borylation of Anilines and C7 Borylation of Indoles using just BBr3
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Indoles are privileged heterocycles found in many biologically active pharmaceuticals and natural products. However, the selective functionalization of the benzenoid moiety in indoles in preference to the more reactive pyrrolic unit is a significant challenge. Herein we report that N-acyl directing groups enable the C7-selective C?H borylation of indoles using just BBr3. This transformation shows some functional-group tolerance and notably proceeds with C6 substituted indoles. The directing group can be readily removed in situ and the products isolated as the pinacol boronate esters. Acyl-directed electrophilic borylation can be extended to carbazoles and anilines with excellent ortho selectivity. 4-amino-indoles are amenable to this process, with acyl group installation and directed electrophilic C?H borylation enabling selective formation of C5-BPin-indoles.
- Iqbal, Saqib A.,Cid, Jessica,Procter, Richard J.,Uzelac, Marina,Yuan, Kang,Ingleson, Michael J.
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supporting information
p. 15381 - 15385
(2019/10/22)
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- Amidation of Aryl Chlorides Using a Microwave-Assisted, Copper-Catalyzed Concurrent Tandem Catalytic Methodology
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A concurrent tandem catalytic (CTC) methodology has been developed for the amidation of aryl chlorides where the aryl chloride is first converted to an aryl iodide via halogen exchange and the aryl iodide is subsequently transformed into the aryl amide. A variety of aryl chlorides were converted to aryl amides in up to 85% isolated yield using 20 mol % CuI, 60 mol % N,N′-cyclohexane-1,2-diamine, 2.2 equiv of K2CO3, and 1.05-1.5 equiv of amide in acetonitrile at 200 °C after 0.75-1 h. The same copper/ligand system served as multifunctional catalyst for both steps of the concurrent catalytic process with iodide present in substoichiometric amounts. Mechanistic studies were consistent with CTC amidation occurring via a nonradical mechanism. Kinetic modeling was conducted to investigate the effect of competitive direct amidation of an aryl chloride or aryl bromide on the formation of product over time during a CTC amidation reaction.
- Chang, Raymond K.,Clairmont, Brice P.,Lin, Shirley,MacArthur, Amy H. Roy
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supporting information
p. 4448 - 4454
(2019/11/13)
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- Highly Chemoselective, Transition-Metal-Free Transamidation of Unactivated Amides and Direct Amidation of Alkyl Esters by N-C/O-C Cleavage
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The amide bond is one of the most fundamental functional groups in chemistry and biology and plays a central role in numerous processes harnessed to streamline the synthesis of key pharmaceutical and industrial molecules. Although the synthesis of amides is one of the most frequently performed reactions by academic and industrial scientists, the direct transamidation of tertiary amides is challenging due to unfavorable kinetic and thermodynamic contributions of the process. Herein, we report the first general, mild, and highly chemoselective method for transamidation of unactivated tertiary amides by a direct acyl N-C bond cleavage with non-nucleophilic amines. This operationally simple method is performed in the absence of transition metals and operates under unusually mild reaction conditions. In this context, we further describe the direct amidation of abundant alkyl esters to afford amide bonds with exquisite selectivity by acyl C-O bond cleavage. The utility of this process is showcased by a broad scope of the method, including various sensitive functional groups, late-stage modification, and the synthesis of drug molecules (>80 examples). Remarkable selectivity toward different functional groups and within different amide and ester electrophiles that is not feasible using existing methods was observed. Extensive experimental and computational studies were conducted to provide insight into the mechanism and the origins of high selectivity. We further present a series of guidelines to predict the reactivity of amides and esters in the synthesis of valuable amide bonds by this user-friendly process. In light of the importance of the amide bond in organic synthesis and major practical advantages of this method, the study opens up new opportunities in the synthesis of pivotal amide bonds in a broad range of chemical contexts.
- Li, Guangchen,Ji, Chong-Lei,Hong, Xin,Szostak, Michal
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supporting information
p. 11161 - 11172
(2019/08/07)
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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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- 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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- An Annulative Synthetic Strategy for Building Triphenylene Frameworks by Multiple C?H Bond Activations
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C?H activation is a versatile tool for appending aryl groups to aromatic systems. However, heavy demands on multiple catalytic cycle operations and site-selectivity have limited its use for graphene segment synthesis. A Pd-catal- yzed one-step synthesis of functionalized triphenylene frameworks is disclosed, which proceeds by 2- or 4-fold C?H arylation of unactivated benzene derivatives. A Pd2(dibenzylideneacetone)3 catalytic system, using cyclic diaryliodonium salts as π-extending agents, leads to site-selective inter- and intramolecular tandem arylation sequences. Moreover, N-substituted triphenylenes are applied to a field-effect transistor sensor for rapid, sensitive, and reversible alcohol vapor detection.
- Mathew, Bijoy P.,Yang, Hyun Ji,Kim, Joohee,Lee, Jae Bin,Kim, Yun-Tae,Lee, Sungmin,Lee, Chang Young,Choe, Wonyoung,Myung, Kyungjae,Park, Jang-Ung,Hong, Sung You
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supporting information
p. 5007 - 5011
(2017/04/24)
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- Insights into the Mechanism of Anodic N-N Bond Formation by Dehydrogenative Coupling
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The electrochemical synthesis of pyrazolidine-3,5-diones and benzoxazoles by N-N bond formation and C,O linkage, respectively, represents an easy access to medicinally relevant structures. Electrochemistry as a key technology ensures a safe and sustainabl
- Gieshoff, Tile,Kehl, Anton,Schollmeyer, Dieter,Moeller, Kevin D.,Waldvogel, Siegfried R.
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p. 12317 - 12324
(2017/09/12)
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- Palladium-Catalyzed, ortho-Selective C-H Halogenation of Benzyl Nitriles, Aryl Weinreb Amides, and Anilides
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A palladium-catalyzed, ortho-selective C-H halogenation methodology is reported herein. The highlight of the work is the highly selective C(sp2)-H functionalization of benzyl nitriles in the presence of activated C(sp3)-H bond, which results in good yields of the halogenated products with excellent regioselectivity. Along with benzyl nitriles, aryl Weinreb amides and anilides have been evaluated for the transformation using aprotic conditions. Mechanistic studies yield interesting aspects with respect to the pathway of the reaction and the directing group abilities.
- Das, Riki,Kapur, Manmohan
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p. 1114 - 1126
(2018/06/18)
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- A Cross-Coupling Approach to Amide Bond Formation from Esters
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A palladium-catalyzed cross-coupling between aryl esters and anilines is reported, enabling access to diverse amides. The reaction takes place via activation of the C-O bond by oxidative addition with a Pd-NHC complex, which enables the use of relatively non-nucleophilic anilines that otherwise require stoichiometric activation with strong bases in order to react. High yields of aromatic, aliphatic, and heterocyclic products are obtained. A range of activated esters are evaluated in the presence and absence of catalyst, demonstrating that the catalytic methodology substantially increases the types of electrophiles that can be utilized for amide bond formation in the absence of harsh bases.
- Ben Halima, Taoufik,Vandavasi, Jaya Kishore,Shkoor, Mohanad,Newman, Stephen G.
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p. 2176 - 2180
(2017/08/09)
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- Silver-promoted decarboxylative amidation of α-keto acids with amines
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A general and effective method for the synthesis of amides through decarboxylative amidation of α-keto acids with amines has been developed. The reaction proceeded smoothly to afford the corresponding amide products in good yield under air and shows excellent functional group tolerance. In addition, the protocol can be further applied in the synthesis of heterocyclic compounds like benzimidazoles.
- Xu, Xiao-Lan,Xu, Wen-Tao,Wu, Ji-Wei,He, Jian-Bo,Xu, Hua-Jian
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supporting information
p. 9970 - 9973
(2016/11/06)
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- Catalyst-Free Singlet Oxygen-Promoted Decarboxylative Amidation of α-Keto Acids with Free Amines
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A novel catalyst-free decarboxylative amidation of α-keto acids with amines under mild conditions has been developed. Advantages of the new protocol include avoidance of metal catalysts and high levels of functional group tolerance. In addition, the reaction can be scaled up and shows high chemoselectivity. Preliminary mechanistic studies suggest that singlet oxygen, generated from oxygen under irradiation, is the key promoter for this catalyst-free transformation.
- Xu, Wen-Tao,Huang, Bei,Dai, Jian-Jun,Xu, Jun,Xu, Hua-Jian
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supporting information
p. 3114 - 3117
(2016/07/14)
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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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- Synthesis of Quinazolines from N,N′-Disubstituted Amidines via I2/KI-Mediated Oxidative C-C Bond Formation
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An I2/KI-promoted oxidative C-C bond formation reaction from C(sp3)-H and C(sp2)-H bonds has been used to construct quinazoline skeletons from N,N′-disubstituted amidines. The required substrates are readily prepared from the corresponding acyl chlorides, anilines, and alkyl/benzylamines by sequential amidation, chlorination, and amination reactions. Under the optimal oxidative cyclization conditions, all these amidines were conveniently transformed into the expected products in moderate to good yields. This practical and environmentally benign approach works well with crude amidine intermediates and can also be carried out on a gram scale.
- Lv, Zhigang,Wang, Bingnan,Hu, Zhiyuan,Zhou, Yiming,Yu, Wenquan,Chang, Junbiao
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supporting information
p. 9924 - 9930
(2016/11/02)
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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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- Sulphuric acid immobilized on silica gel (H2SO4-SiO2) as an eco-friendly catalyst for transamidation
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A novel method of transamidation of carboxamides with amines by using catalytic amounts of H2SO4-SiO2 has been developed under solvent free conditions. The transamidation is compatible with a wide range of aromatic, heteroaromatic, aliphatic, cyclic/acyclic primary or secondary amines. The metal/solvent-free conditions represent a significant improvement over other existing methods as the reaction can be performed in open air conditions and no column purification is required. The versatility of this methodology was further demonstrated by synthesizing the commercially available drug procainamide.
- Rasheed,Rao, D. Nageswar,Reddy, A. Siva,Shankar, Ravi,Das, Parthasarathi
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p. 10567 - 10574
(2015/02/05)
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- Synthesis of secondary amides from N-Substituted amidines by tandem oxidative rearrangement and isocyanate elimination
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In this work an efficient tandem process transforming N-substituted amidines into secondary amides has been described. The process involves N-acylurea formation by reaction of the substrate with bis(acyloxy)(phenyl)-λ3-iodane followed by isocyanate elimination. The periodinane reagents are obtained from the commercially available phenyl-iodine(III) diacetate [PhI(OAc)2, (PIDA)] by ligand exchange with carboxylic acids. The N-substituted amidine substrates are easily synthesized from readily available nitriles. The method is applicable for secondary amide synthesis, based on both aliphatic and (hetero)aromatic amines, including challenging amides consisting of sterically hindered acids and amines. Moreover, the protocol allows one to combine steric bulk with electron deficiency in the target amides (aniline based). Such compounds are difficult to synthesize efficiently based on classical condensation reactions involving carboxylic acids and amines. Overall, the synthetic protocol transforms a nitrile into a secondary amide in both aliphatic and (hetero)aromatic systems.
- Debnath, Pradip,Baeten, Mattijs,Lefvre, Nicolas,Van Daele, Stijn,Maes, Bert U. W.
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supporting information
p. 197 - 209
(2015/03/03)
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- A highly efficient Pd-catalyzed decarboxylative ortho-arylation of amides with aryl acylperoxides
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An efficient Pd-catalyzed decarboxylative ortho-arylation of amides with aryl acylperoxides was developed. A variety of anilides reacted with aryl acylperoxides to afford the corresponding ortho-arylation products, and N-methoxyarylamides generated phenanthridinones. This journal is
- Li, Dengke,Xu, Ning,Zhang, Yicheng,Wang, Lei
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supporting information
p. 14862 - 14865
(2014/12/11)
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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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- Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether as coupling reagent for peptide synthesis
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Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether (4) was prepared by treatment of 2-hydroxy-4,6-dimethoxy-1,3,5-triazine with 2-chloro-4,6-dimethoxy-1,3,5- triazine in 61% yield. Ether 4, isoelectronic with pyrocarbonates, was found capable to activate carboxylic acids in the presence of 1,4-diazabicyclo[2.2.2] octane (DABCO) to yield, under mild reaction conditions, superactive triazine esters. Versatility of this new coupling reagent was confirmed by condensation of lipophilic and sterically hindered carboxylic acids with amines in 71-98% yield, and by synthesis of peptides, including those containing Aib-Aib sequence, in solution with high yield and high enantiomeric purity. Copyright
- Jastrzabek, Konrad,Bednarek, Przemyslaw,Kolesinska, Beata,Kaminski, Zbigniew J.
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p. 952 - 961
(2013/07/28)
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- Mild C - H halogenation of anilides and the isolation of an unusual palladium(I)-palladium(II) species
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Reducing the load: A facile palladium-catalyzed ortho-selective bromination and chlorination of anilides occurs under aerobic conditions at room temperature when N-halosuccinimides (NXS) are used in the presence of p-toluenesulfonic acid (PTSA). The orthopalladated PTSA complex is not only catalytically competent but also undergoes a reductive process to yield an unusual PdI-PdII tetramer (see structure; Pdgreen, Ored, Syellow, Cgray). Copyright
- Bedford, Robin B.,Haddow, Mairi F.,Mitchell, Charlotte J.,Webster, Ruth L.
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supporting information; experimental part
p. 5524 - 5527
(2011/07/31)
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- Copper-catalyzed dehydrogenative cross-coupling reactions of N-para-tolylamides through successive C-H activation: Synthesis of 4H-3,1-benzoxazines
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A novel annulation reaction of readily available tolylamides was catalyzed by Cu(OTf)2 in the presence of Selectfluor and water through successive intermolecular C-H activated dehydrogenative cross-coupling reactions of benzylic methyl C(sp3)-H and aromatic C(sp2)-H bonds, and subsequent intramolecular C-O bond formation (see scheme). Copyright
- Xiong, Tao,Li, Yan,Bi, Xihe,Lv, Yunhe,Zhang, Qian
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supporting information; experimental part
p. 7140 - 7143
(2011/09/12)
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- Palladium-catalyzed oxidative C-H bond acylation of acetanilides with benzylic alcohols
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An efficient and clean method to construct C-C bonds has been developed via the acylation reaction of acetanilides with benzylic alcohols using tert-butyl hydroperoxide (TBHP) as oxidant catalyzed by palladium acetate in the presence of triflic acid (TfOH). The acylation reactions exhibit excellent reactivities, and up to 95% yield of the corresponding aryl ketone could be obtained under the optimal conditions. Copyright
- Yuan, Yu,Chen, Duanteng,Wang, Xiaowei
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p. 3373 - 3379
(2012/02/03)
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- Remote amide-directed palladium-catalyzed benzylic C-H amination with N-fluorobenzenesulfonimide
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An unprecedented remote amide-directed palladium-catalyzed intermolecular highly selective benzylic C-H amination with N-fluorobenzenesulfonimide is developed, which represents the first direct benzylic C-H amination with a non-nitrene nitrogen source. This methodology provides a novel approach to circumvent the common ortho aromatic C-H selectivity in directed palladium catalyzed C-H functionalization.
- Xiong, Tao,Li, Yan,Lv, Yunhe,Zhang, Qian
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supporting information; experimental part
p. 6831 - 6833
(2010/10/21)
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- Solvent-free aromatic C-H functionalisation/halogenation reactions
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The solvent-free, palladium-catalysed reaction of anilides with CuCl 2 in the presence or absence of copper acetate yields ortho-chlorinated anilides in good to excellent yields, even on a large scale (100 mmol). By contrast, the equivalent reactions with copper bromide, either solvent free or in 1,2-dichloroethane, in the presence or absence of palladium, under air or inert conditions, gave the products of simple electrophilic bromination. Mechanistic studies highlighted the involvement of palladacyclic intermediates, one of which was characterised crystallographically, which undergo subsequent reaction with copper(ii) chloride to yield the chlorinated anilide products.
- Bedford, Robin B.,Engelhart, Jens U.,Haddow, Mairi F.,Mitchell, Charlotte J.,Webster, Ruth L.
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supporting information; experimental part
p. 10464 - 10472
(2011/01/05)
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- Infrared spectra of N-aryl substituted amides 2/4-XC6H 4NHCOR (R = H, CH3-iXi, C6H 5 or C6H5Cl; X = H, Cl or CH3 and i = 0, 1, 2 or 3)
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Several N-(aryl)-substituted amides of the general formula, 2/4-XC 6H4NHCOR (where X = H, Cl or CH3 and R = H, CH3, CH2CH3, CH(CH3)2, C(CH3)3, C6H5 or C6H 5Cl) are prepared, characterised and their infrared spectra measured in the solid state and analysed. Generally chloro substitution in the side chain increases the C=O absorptions, while that of methyl groups lower the wave numbers. Amides with trimethyl substituted side chains absorb at higher wavenumbers. But the N-H and C-N stretching vibrations do not show particular trends on side chain substitution. This may be due to the fact that the spectra were recorded in the solid state and the compounds may crystallise in different forms in the solid state. The intercorrelations of C=O and N-H absorption frequencies of all the amides have been made. The correlations are reasonably linear with some exceptions for the reasons stated above.
- Gowda, B. Thimme,Jyothi,Jayalakshmi,Damodara
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p. 564 - 568
(2007/10/03)
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- Carbanionically Induced -Migrations of ?- and Coordinatively Unsaturated Groups
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According to a general reaction scheme, o-lithioaryl esters 4a,b, amides 13a,b 17b, and amidines 39b of non-enolizable carboxylic acids as well as a corresponding diphenylphosphinic amide 51b react under mild conditions to give the intensely coloured lithium derivatives of o-acylphenoles 6a,b and o-acylarenamines 15a,b, 18a, 41a, 52a, which are finally hydrolyzed to the neutral products 7a,b, 14a,b, 18b, 41b, 52b, respectively.The lithiated precursors of the rearrangement are mostly prepared by halogen/metal exchange reactions.In the case of N,N-di-p-tolylpivalamide 33 such a -rearrangement also could be induced by direct metalation of the educt.With N-methyl-N-phenylpivalamide (29), however, exclusive metalation of the N-methyl group occurs, followed by -migration of the pivaloyl group.Silyl groups, too, can undergo analogous -shifts, as was demonstrated by the rearrangement of the o-lithiated N-(trimethylsilyl)aniline 63b to the o-(trimethylsilyl)anilines 65a,b.When a benzoyl and sulfonyl group can compete for the -shifts, as in the N-tosylated benzamide 47b, only the benzoyl group migrates.However, the migration tendency of the trimethylsilyl group equals that of the benzoyl group as was shown with the N-silylated benzamide 66b.
- Hellwinkel, Dieter,Laemmerzahl, Frank,Hofmann, Gunter
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p. 3375 - 3405
(2007/10/02)
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