- Anomalous dual fluorescence of benzanilide
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The absorption and fluorescence spectra of benzanilide and N-methylbenzanilide have been investigated in solution and low-temperature glasses and assigned with the aid of ZINDO calculations. The anomalous dual fluorescence observed by previous workers has been assigned to the two lowest singlet states of benzanilide. The lower energy n,π* state is populated by excitation in the long-wavelength tail of the absorption band. Its fluorescence is readily detected in low-temperature glasses and at room temperature in aromatic solvents. Large NMR solvent-induced shifts provide evidence for ground-state complex formation of benzanilide with aromatic solvents. The higher energy π,π* state is populated by excitation of an allowed transition. It undergoes twisting about the amide C-N bond to form a fluorescent twisted intramolecular charge-transfer state with a maximum of 520 nm in benzene solution. In rigid glasses twisting to form the twisted charge-transfer state cannot occur, and the π,π* state undergoes internal conversion to the lower energy n,π* state.
- Lewis, Frederick D.,Long, Timothy M.
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- Simple and convenient synthesis of tertiary benzanilides using dichlorotriphenylphosphorane
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Various tertiary benzanilide derivatives were effectively synthesized from substituted benzoic acid and N-monoalkylated aniline using dichlorotriphenylphosphorane in chloroform. Yields were generally high, even when an electron-withdrawing group substituted the aromatic ring of aniline, or when an electron-donating group substituted the aromatic ring of benzoic acid. Allyl, Boc, MPM and the Z group were unaffected under these conditions.
- Azumaya, Isao,Okamoto, Takako,Imabeppu, Fumiaki,Takayanagi, Hiroaki
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- Pd-Catalyzed Double-Decarbonylative Aryl Sulfide Synthesis through Aryl Exchange between Amides and Thioesters
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We report the palladium-catalyzed double-decarbonylative synthesis of aryl thioethers by an aryl exchange reaction between amides and thioesters. In this method, amides serve as aryl donors and thioesters are sulfide donors, enabling the synthesis of valuable aryl sulfides. The use of Pd/Xantphos without any additives has been identified as the catalytic system promoting the aryl exchange by C(O)-N/C(O)-S cleavages. The method is amenable to a wide variety of amides and sulfides.
- Bie, Fusheng,Cao, Han,Liu, Chengwei,Liu, Xuejing,Shi, Yijun,Szostak, Michal,Zhou, Tongliang
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supporting information
p. 8098 - 8103
(2021/10/25)
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- PCl3-mediated transesterification and aminolysis of tert-butyl esters via acid chloride formation
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A PCl3-mediated conversion of tert-butyl esters into esters and amides in one-pot under air is developed. This novel protocol is highlighted by the synthesis of skeletons of bioactive molecules and gram-scale reactions. Mechanistic studies revealed that this transformation involves the formation of an acid chloride in situ, which is followed by reactions with alcohols or amines to afford the desired products.
- Wu, Xiaofang,Zhou, Lei,Li, Fangshao,Xiao, Jing
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p. 491 - 497
(2021/01/20)
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- Carboxylic Acid Deoxyfluorination and One-Pot Amide Bond Formation Using Pentafluoropyridine (PFP)
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This work describes the application of pentafluoropyridine (PFP), a cheap commercially available reagent, in the deoxyfluorination of carboxylic acids to acyl fluorides. The acyl fluorides can be formed from a range of acids under mild conditions. We also demonstrate that PFP can be utilized in a one-pot amide bond formation via in situ generation of acyl fluorides. This one-pot deoxyfluorination amide bond-forming reaction gives ready access to amides in yields of ≤94%.
- Brittain, William D. G.,Cobb, Steven L.
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supporting information
p. 5793 - 5798
(2021/08/01)
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- Direct Amidation of Esters by Ball Milling**
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The direct mechanochemical amidation of esters by ball milling is described. The operationally simple procedure requires an ester, an amine, and substoichiometric KOtBu and was used to prepare a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of active pharmaceutical ingredients (APIs) and agrochemicals as well as the gram-scale synthesis of an active pharmaceutical, all in the absence of a reaction solvent.
- Barreteau, Fabien,Battilocchio, Claudio,Browne, Duncan L.,Godineau, Edouard,Leitch, Jamie A.,Nicholson, William I.,Payne, Riley,Priestley, Ian
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supporting information
p. 21868 - 21874
(2021/09/02)
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- Chromium-catalyzed ligand-free amidation of esters with anilines
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Amides are important structural motifs in pharmaceutical and agrochemical chemistry because of the intriguing biological active properties. We report here the amidation of commercially available esters with anilines that was promoted by low-cost and air-stable chromium(III) pre-catalyst combined with magnesium, providing access to amides. This reaction occurs without the use of external ligands in a simple operation. Mechanistic studies indicate that a reactive aminated Cr species responsible for the amidation can be considered, which may be formed by reaction of low-valent Cr with aniline followed by reduction with hydrogen evolution.
- Chen, Changpeng,Ling, Liang,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 762 - 766
(2021/04/14)
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- CuO-decorated magnetite-reduced graphene oxide: a robust and promising heterogeneous catalyst for the oxidative amidation of methylarenes in waterviabenzylic sp3C-H activation
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A magnetite-reduced graphene oxide-supported CuO nanocomposite (rGO/Fe3O4-CuO) was preparedviaa facile chemical method and characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Brunauer-Emmett-Teller (BET) analysis, vibrating-sample magnetometry (VSM), and thermogravimetric (TG) analysis. The catalytic activity of the rGO/Fe3O4-CuO nanocomposite was probed in the direct oxidative amidation reaction of methylarenes with free amines. Various aromatic and aliphatic amides were prepared efficiently at room temperature from cheap raw chemicals usingtert-butyl hydroperoxide (TBHP) as a “green” oxidant and low-toxicity TBAI in water. This method combines the oxidation of methylarenes and amide bond formation into a single operation. Moreover, the synthesized nanocomposites can be separated from the reaction mixtures using an external magnet and reused in six consecutive runs without a noticeable decrease in the catalytic activity.
- Ebrahimi, Edris,Khalafi-Nezhad, Ali,Khalili, Dariush,Rousta, Marzieh
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p. 20007 - 20020
(2021/11/12)
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- Palladium-Catalyzed Desulfurative Hiyama Coupling of Thioureas to Achieve Amides via Selective C-N Bond Cleavage
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Palladium-catalyzed Hiyama coupling of active thioureas via selective C-N bond cleavage is reported. Notably, the new approach employed active thioureas as coupling partners in the presence of arylsilanes to give amides in good yield. Further, this strategy, which utilized CuF 2as a key oxidant and activator, afforded various amide products under mild conditions and an easy to handle procedure without extra base.
- He, Zhanyu,Yan, Chu,Zhang, Mei,Irfan, Majeed,Wang, Zijia,Zeng, Zhuo
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supporting information
p. 705 - 710
(2021/10/25)
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- Iron-catalyzed oxidative amidation of acylhydrazines with amines
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A new approach for amide bond formation via a mild and efficient Iron-catalyzed cross-coupling reaction of acylhydrazines and amines using TBHP as oxidant is described. This protocol is compatible with a wide range of amines and acylhydrazines. In addition, the synthetic application of the reaction is presented.
- Wang, Yi-Jie,Zhang, Guo-Yu,Shoberu, Adedamola,Zou, Jian-Ping
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- Nickel-Catalyzed Oxidative Transamidation of Tertiary Aromatic Amines with N -Acylsaccharins
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The use of tertiary amines as surrogates for secondary amines has prominent advantages in terms of stabilization and ease of handling. A Ni-catalyzed transamidation of N -acylsaccharins with tertiary aromatic amines is reported. By using tert -butyl hydroperoxide as the terminal oxidant, this reaction permits selective cleavage of the C(sp 3)-N bonds of unsymmetrical tertiary aromatic amines depending on the sizes of the alkyl substituents.
- Liu, Shengzhang,Yang, Lingyun,Tao, Jiasi,Yu, Weijie,Wang, Tao,Fu, Junkai
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supporting information
p. 1642 - 1646
(2021/06/21)
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- Cu(I)–N-heterocyclic carbene-catalyzed base free C–N bond formation of arylboronic acids with amines and azoles
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A new N-heterocyclic carbene (NHC) precursor of imidazolium chloride and its corresponding Cu(I)–NHC complex 1 was synthesized. The complex 1 was found to be a highly effective catalyst for Chan-Evans-Lam coupling of arylboronic acid with amines and azoles (including imidazole, pyrazole and triazole), without addition of base at room temperature. Various substituents on three substrates can be tolerated, giving the desired coupling products in good to excellent yields (62–94%). The method is practical and offers an alternative to the corresponding copper-catalyzed Chan-Evans-Lam process for the construction of C–N bonds.
- Zhang, Maoyuan,Xu, Zengbing,Shi, Dabin
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- Regio- And Stereoselective (S N2) N -, O -, C - And S -Alkylation Using Trialkyl Phosphates
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Bimolecular nucleophilic substitution (S N 2) is one of the most well-known fundamental reactions in organic chemistry to generate new molecules from two molecules. In principle, a nucleophile attacks from the back side of an alkylating agent having a suitable leaving group, most commonly a halide. However, alkyl halides are expensive, very harmful, toxic and not so stable, which makes them problematic for laboratory use. In contrast, trialkyl phosphates are inexpensive, readily accessible and stable at room temperature, under air, and are easy to handle, but rarely used as alkylating agents in organic synthesis. Here, we describe a mild, straightforward and powerful method for nucleophilic alkylation of various N -, O -, C - and S -nucleophiles using readily available trialkyl phosphates. The reaction proceeds smoothly in excellent yield, and quantitative yield in many cases, and covers a wide range of substrates. Further, the rare stereoselective transfer of secondary alkyl groups has been achieved with inversion of configuration of chiral centers (up to 98% ee).
- Banerjee, Amit,Hattori, Tomohiro,Yamamoto, Hisashi
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supporting information
(2021/06/16)
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- Preparation of alkylated compounds using the trialkylphosphate
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[Problem] trialkylphosphate strong base used reaction agent, a carboxylic acid, a ketone, an aldehyde, amine, amide, thiol, ester or Grignard reagent to a variety of substrates, and/or high efficiency to generate a highly stereoselective alkylation reaction, the alkylated compounds capable of producing new means. [Solution] was used as the alkylating agent in the alkylation of compound trialkylphosphate, strongly basic reaction production use. [Drawing] no
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Paragraph 0184-0185
(2021/11/02)
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- Manganese Catalyzed Direct Amidation of Esters with Amines
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The transition metal catalyzed amide bond forming reaction of esters with amines has been developed as an advanced approach for overcoming the shortcomings of traditional methods. The broad scope of substrates in transition metal catalyzed amidations remains a challenge. Here, a manganese(I)-catalyzed method for the direct synthesis of amides from a various number of esters and amines is reported with unprecedented substrate scope using a low catalyst loading. A wide range of aromatic, aliphatic, and heterocyclic esters, even in fatty acid esters, reacted with a diverse range of primary aryl amines, primary alkyl amines, and secondary alkyl amines to form amides. It is noteworthy that this approach provides the first example of the transition metal catalyzed amide bond forming reaction from fatty acid esters and amines. The acid-base mechanism for the manganese(I)-catalyzed direct amidation of esters with amines was elucidated by DFT calculations.
- Fu, Zhengqiang,Wang, Xinghua,Tao, Sheng,Bu, Qingqing,Wei, Donghui,Liu, Ning
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p. 2339 - 2358
(2021/02/03)
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- A practical and sustainable protocol for direct amidation of unactivated esters under transition-metal-free and solvent-free conditions
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In this paper, a NaOtBu-mediated synthesis approach was developed for direct amidation of unactivated esters with amines under transition-metal-free and solvent-free conditions, affording a series of amides in good to excellent yields at room temperature. In particular, an environmentally friendly and practical workup procedure, which circumvents the use of organic solvents and chromatography in most cases, was disclosed. Moreover, the gram-scale production of representative products3a,3wand3auwas efficiently realized by applying operationally simple, sustainable and practical procedures. Furthermore, this approach was also applicable to the synthesis of valuable molecules such as moclobemide (a powerful antidepressant), benodanil and fenfuram (two commercial agricultural fungicides). These results demonstrate that this protocol has the potential to streamline amide synthesis in industry. Meanwhile, quantitative green metrics of all the target products were evaluated, implying that the present protocol is advantageous over the reported ones in terms of environmental friendliness and sustainability. Finally, additional experiments and computational calculations were carried out to elucidate the mechanistic insight of this transformation, and one plausible mechanism was provided on the basis of these results and the related literature reports.
- Chen, Cheng,Cheng, Hua,Du, Min-Chen,Qian, Liang,Qin, Xin,Sang, Wei,Yao, Wei-Zhong,Yuan, Ye,Zhang, Rui
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supporting information
p. 3972 - 3982
(2021/06/17)
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- Copper-catalyzed Goldberg-type C-N coupling in deep eutectic solvents (DESs) and water under aerobic conditions
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An efficient and selectiveN-functionalization of amides is first reportedviaa CuI-catalyzed Goldberg-type C-N coupling reaction between aryl iodides and primary/secondary amides run either in Deep Eutectic Solvents (DESs) or water as sustainable reaction media, under mild and bench-type reaction conditions (absence of protecting atmosphere). Higher activities were observed in an aqueous medium, though the employment of DESs expanded and improved the scope of the reaction to include also aliphatic amides. Additional valuable features of the reported protocol include: (i) the possibility to scale up the reaction without any erosion of the yield/reaction time; (ii) the recyclability of both the catalyst and the eutectic solvent up to 4 consecutive runs; and (iii) the feasibility of the proposed catalytic system for the synthesis of biologically active molecules.
- Cicco, Luciana,Hernández-Fernández, Jose A.,Salomone, Antonio,Vitale, Paola,Ramos-Martín, Marina,González-Sabín, Javier,Presa Soto, Alejandro,Perna, Filippo M.,Capriati, Vito,García-álvarez, Joaquín
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supporting information
p. 1773 - 1779
(2021/03/14)
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- Homoleptic Bis(trimethylsilyl)amides of Yttrium Complexes Catalyzed Hydroboration Reduction of Amides to Amines
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Homoleptic lanthanide complex Y[N(TMS)2]3 is an efficient homogeneous catalyst for the hydroboration reduction of secondary amides and tertiary amides to corresponding amines. A series of amides containing different functional groups such as cyano, nitro, and vinyl groups were found to be well-tolerated. This transformation has also been nicely applied to the synthesis of indoles and piribedil. Detailed isotopic labeling experiments, control experiments, and kinetic studies provided cumulative evidence to elucidate the reaction mechanism.
- Ye, Pengqing,Shao, Yinlin,Ye, Xuanzeng,Zhang, Fangjun,Li, Renhao,Sun, Jiani,Xu, Beihang,Chen, Jiuxi
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supporting information
p. 1306 - 1310
(2020/02/22)
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- Rh-Catalyzed Base-Free Decarbonylative Borylation of Twisted Amides
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We report the rhodium-catalyzed base-free decarbonylative borylation of twisted amides. The synthesis of versatile arylboronate esters from aryl twisted amides is achieved via decarbonylative rhodium(I) catalysis and highly selective N-C(O) insertion. The method is notable for a very practical, additive-free Rh(I) catalyst system. The method shows broad functional group tolerance and excellent substrate scope, including site-selective decarbonylative borylation/Heck cross-coupling via divergent N-C/C-Br cleavage and late-stage pharmaceutical borylation.
- Bie, Fusheng,Liu, Xuejing,Shi, Yijun,Cao, Han,Han, Ying,Szostak, Michal,Liu, Chengwei,Liu, Xuejing,Szostak, Michal,Liu, Chengwei
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p. 15676 - 15685
(2020/11/13)
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- Copper-Catalyzed Radical N-Demethylation of Amides Using N-Fluorobenzenesulfonimide as an Oxidant
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An unprecedented N-demethylation of N-methyl amides has been developed by use of N-fluorobenzenesulfonimide as an oxidant with the aid of a copper catalyst. The conversion of amides to carbinolamines involves successive single-electron transfer, hydrogen-atom transfer, and hydrolysis, and is accompanied by formation of N-(phenylsulfonyl)benzenesulfonamide. Carbinolamines spontaneously decompose to N-demethylated amides and formaldehyde, because of their inherent instability.
- Yi, Xuewen,Yi, Xuewen,Lei, Siyu,Liu, Wangsheng,Che, Fengrui,Yu, Chunzheng,Liu, Xuesong,Wang, Zonghua,Zhou, Xin,Zhang, Yuexia
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supporting information
p. 4583 - 4587
(2020/05/05)
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- Facile amidation of esters with aromatic amines promoted by lanthanide tris (amide) complexes
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The development of catalysts capable of catalyzing amidation of esters with amines to construct amides under mild conditions is of great importance. Compared to aliphatic amines, the direct catalytic amidation of esters with less nucleophilic aromatic amines is rather difficult. Employing simple lanthanide tris (amide) complexes Ln[N (SiMe3)2]3(μ-Cl)Li (THF)3 as the catalysts, it was found a broad range of aromatic amines and esters were efficiently converted into various amides in good yields under mild conditions. A plausible mechanism for this transformation was experimentally supported as starting from an amide exchange reaction between the lanthanide tris (amide) complex and the substrate amine.
- Li, Zhao,Guo, Chenjun,Chen, Jue,Yao, Yingming,Luo, Yunjie
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- Palladium-Catalyzed Desulfurative Amide Formation from Thioureas and Arylboronic Acids
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The development of the reactivity on carbene complexes would lead to the creation of novel synthetic strategies. We discovered herein the Pd-catalyzed desulfurative amide formation involved Suzuki-Miyaura coupling reaction, notably the Pd complex was generated in situ from thioureas, Ag salt and Pd catalyst. Silver salt was essential for the construction of this type of carbenes from available and stable thioureas and well participated in the catalytic cycle. We report a method for the synthesis of arylamides from arylboronic acids, which greatly enriched the application of thiourea chemistry and expanded the application of the Suzuki-Miyaura coupling.
- Su, Jianke,Li, Wendong,Li, Xin,Xu, Jian,Song, Qiuling
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p. 5664 - 5668
(2020/10/02)
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- Ultrafast amidation of esters using lithium amides under aerobic ambient temperature conditions in sustainable solvents
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Lithium amides constitute one of the most commonly used classes of reagents in synthetic chemistry. However, despite having many applications, their use is handicapped by the requirement of low temperatures, in order to control their reactivity, as well as the need for dry organic solvents and protective inert atmosphere protocols to prevent their fast decomposition. Advancing the development of air- and moisture-compatible polar organometallic chemistry, the chemoselective and ultrafast amidation of esters mediated by lithium amides is reported. Establishing a novel sustainable access to carboxamides, this has been accomplished via direct C-O bond cleavage of a range of esters using glycerol or 2-MeTHF as a solvent, in air. High yields and good selectivity are observed while operating at ambient temperature, without the need for transition-metal mediation, and the protocol extends to transamidation processes. Pre-coordination of the organic substrate to the reactive lithium amide as a key step in the amidation processes has been assessed, enabling the structural elucidation of the coordination adduct [{Li(NPh2)(OCPh(NMe2))}2] (8) when toluene is employed as a solvent. No evidence for formation of a complex of this type has been found when using donor THF as a solvent. Structural and spectroscopic insights into the constitution of selected lithium amides in 2-MeTHF are provided that support the involvement of small kinetically activated aggregates that can react rapidly with the organic substrates, favouring the C-O bond cleavage/C-N bond formation processes over competing hydrolysis/degradation of the lithium amides by moisture or air.
- Bole, Leonie J.,Fairley, Michael,García-Alvarez, Joaquín,Hevia, Eva,Kennedy, Alan R.,Main, Laura,Mulks, Florian F.,O'Hara, Charles T.
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p. 6500 - 6509
(2020/07/15)
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- Two-step continuous flow synthesis of amide via oxidative amidation of methylarene
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A green and efficient method for the synthesis of amides has been developed through oxidative amidation between methylarenes with amines in a two-step continuous flow system. This method integrates methylarene oxidation and amide formation into a single operation which is usually accomplished separately. Oxidation with tert-butyl hydroperoxide (TBHP) as “green” oxidant, the synthesis of amides under mild reaction conditions in continuous flow system and the utilization of methylarenes as starting material make this methodology novel and environment friendly. The practical value of this method is highlighted through the synthesis of high-profile pharmaceutical agents, acetylprocainamide.
- Fang, Zheng,Guo, Kai,He, Wei,Liu, Chengkou,Shi, Tingting,Yang, Yuhang,Yang, Zhao,Zhang, Zhimin
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supporting information
(2020/02/28)
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- Selective Methylation of Amides, N-Heterocycles, Thiols, and Alcohols with Tetramethylammonium Fluoride
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We herein disclose the use of tetramethylammonium fluoride (TMAF) as a direct and selective methylating agent of a variety of amides, indoles, pyrroles, imidazoles, alcohols, and thiols. The method is characterized by operational simplicity, wide scope, and ease of purification. Our computational studies suggest a concerted methylation-deprotonation as the preferred reaction pathway.
- Cheng, Hong-Gang,Pu, Maoping,Kundu, Gourab,Schoenebeck, Franziska
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supporting information
p. 331 - 334
(2019/12/30)
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- 3,6-Di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) catalysed metal-free amide bond formation from thioacids and amines at room temperature
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A 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) catalysed efficient, mild and metal-free method has been developed for direct amide bond synthesis from simple thioacids and amines as starting materials. This methodology is useful for aromatic, aliphatic, and heteroaromatic thioacids as well as primary, secondary, heterocyclic, and even functionalized amines. A wide substrates scope, operationally mild conditions, and acylation of amines without affecting other functional groups such as alcohols, esters, carbodithioates, among others make this strategy very attractive and practical.
- Samanta, Suvendu,Ray, Shounak,Bhaduri, Samanka Narayan,Samanta, Partha Kumar,Biswas, Papu
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supporting information
(2020/08/10)
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- Buchwald-Hartwig cross-coupling of amides (transamidation) by selective N-C(O) cleavage mediated by air- And moisture-stable [Pd(NHC)(allyl)Cl] precatalysts: Catalyst evaluation and mechanism
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The Pd-NHC-catalyzed acyl-type Buchwald-Hartwig cross-coupling of amides by N-C(O) cleavage (transamidation) provides a valuable alternative to the classical methods for amide synthesis. Herein, we report a combined experimental and computational study of the Buchwald-Hartwig cross-coupling of amides using well-defined, air- and moisture-stable [Pd(NHC)(allyl)Cl] precatalysts. Most crucially, we present a comprehensive evaluation of a series of distinct Pd(ii)-NHC precatalysts featuring different NHC scaffolds and throw-away ligands for the synthesis of functionalized amides that are not compatible with stoichiometric transition-metal-free transamidation methods. Furthermore, we present evaluation of the catalytic cycle by DFT methods for a series of different Pd(ii)-NHC precatalysts. The viability of accessing NHC-supported acyl-palladium(ii) amido complexes will have implications for the design and development of cross-coupling methods involving stable amide electrophiles.
- Li, Guangchen,Zhou, Tongliang,Poater, Albert,Cavallo, Luigi,Nolan, Steven P.,Szostak, Michal
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p. 710 - 716
(2020/02/25)
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- An efficient synthesis of benzothiazole using tetrabromomethane as a halogen bond donor catalyst
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An efficient and mild protocol has been developed for the synthesis of 2-substituted benzothiazole under solvent- and metal-free conditions using CBr4 as the catalyst. This process involves the activation of a thioamide through halogen bond formation between the sulphur atom of the thioamide and bromine atom of the CBr4 molecule. The presence of halogen-bonding interaction between N-methylthioamides and tetrabromomethane has been demonstrated with several control experiments, spectroscopic analysis and density functional theory (DFT). This methodology has a wide substrate scope for the synthesis of both 2-alkyl and 2-aryl substituted benzothiazoles.
- Kazi, Imran,Sekar, Govindasamy
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p. 9743 - 9756
(2019/12/02)
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- KMnO4-mediated oxidative C[sbnd]N bond cleavage of tertiary amines: Synthesis of amides and sulfonamides
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KMnO4-mediated oxidative C[sbnd]N bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.
- Zhang, Zhang,Liu, Yong-Hong,Zhang, Xi,Wang, Xi-Cun
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p. 2763 - 2770
(2019/04/10)
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- Frustrated Lewis Pair Catalyzed Hydrogenation of Amides: Halides as Active Lewis Base in the Metal-Free Hydrogen Activation
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A method for the metal-free reduction of carboxylic amides using oxalyl chloride as an activating agent and hydrogen as the final reductant is introduced. The reaction proceeds via the hydrogen splitting by B(2,6-F2-C6H3)3 in combination with chloride as the Lewis base. Density functional theory calculations support the unprecedented role of halides as active Lewis base components in the frustrated Lewis pair mediated hydrogen activation. The reaction displays broad substrate scope for tertiary benzoic acid amides and α-branched carboxamides.
- Sitte, Nikolai A.,Bursch, Markus,Grimme, Stefan,Paradies, Jan
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supporting information
p. 159 - 162
(2019/01/04)
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- Clickable coupling of carboxylic acids and amines at room temperature mediated by SO2F2: A significant breakthrough for the construction of amides and peptide linkages
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The construction of amide bonds and peptide linkages is one of the most fundamental transformations in all life processes and organic synthesis. The synthesis of structurally ubiquitous amide motifs is essential in the assembly of numerous important molecules such as peptides, proteins, alkaloids, pharmaceutical agents, polymers, ligands and agrochemicals. A method of SO2F2-mediated direct clickable coupling of carboxylic acids with amines was developed for the synthesis of a broad scope of amides in a simple, mild, highly efficient, robust and practical manner (>110 examples, >90% yields in most cases). The direct click reactions of acids and amines on a gram scale are also demonstrated using an extremely easy work-up and purification process of washing with 1 M aqueous HCl to provide the desired amides in greater than 99% purity and excellent yields.
- Wang, Shi-Meng,Zhao, Chuang,Zhang, Xu,Qin, Hua-Li
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p. 4087 - 4101
(2019/04/30)
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- Selective C?N Bond Cleavage of N-Acylisatins: Towards High Performance Acylation/Arylation/Transamination Reagents
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New multipurpose arylation/acylation/transamination reagents, N-acylisatins, have been developed by selective ‘inside-outside’ C?N bond cleavage under different catalytic conditions. As activated amides, N-acylisatins undergo Rh-catalyzed C?H arylation and Pd-catalyzed acylation by cleavage outside the C?N bond, and the desired biaryls and diaryl ketones were obtained in good to excellent yields. Generally, the combination of N-acylisatins with amines leads to a ring-opening reaction and formation of transamination products in a predictable manner through inside C?N bond cleavage. Interestingly, treatment of N-acylisatins with amines lead to unexpected outer-ring transamination products when CsF is added, which shows that CsF can favor the outside C?N bond cleavage path. Notably, this work presents a new strategy for multiple chemical transformations of a single amide to achieve various products by selective C?N bond cleavage. (Figure presented.).
- Xiong, Li,Deng, Rong,Liu, Tingting,Luo, Zhongfeng,Wang, Zijia,Zhu, Xiao-Feng,Wang, Hui,Zeng, Zhuo
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supporting information
p. 5383 - 5391
(2019/11/03)
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- Amide Synthesis from Thiocarboxylic Acids and Amines by Spontaneous Reaction and Electrosynthesis
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Amide bond formation is one of the most important basic reactions in chemistry. A catalyst-free approach for constructing amide bonds from thiocarboxylic acids and amines was developed. The mechanistic studies showed that the disulfide was the key intermediate for this amide synthesis. Thiobenzoic acids could be automatically oxidized to disulfides in air, thioaliphatic acids could be electro-oxidized to disulfides, and the resulting disulfides reacted with amines to give the corresponding amides. By this method, various amides could be easily synthesized in excellent yields without using any catalyst or activator. The successful synthesis of bioactive compounds also highlights the synthetic utility of this strategy in medicinal chemistry.
- Tang, Li,Matuska, Jack H.,Huang, Yu-Han,He, Yan-Hong,Guan, Zhi
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p. 2570 - 2575
(2019/06/13)
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- Catalyst-Free, Metal-Free, and Chemoselective Transamidation of Activated Secondary Amides
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A simple protocol, which is catalyst-free, metal-free, and chemoselective, for transamidation of activated secondary amides in ethanol as solvent under mild conditions is reported. A wide range of amines, amino acids, amino alcohols, and the substituents, which are problematic in catalyzed transamidation, are tolerated in this methodology. The transamidation reaction was successfully extended to water as the medium as well. The present methodology appears to be better than the other catalyzed transamidations reported recently.
- Ramkumar, Rajagopal,Chandrasekaran, Srinivasan
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p. 921 - 932
(2019/02/10)
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- Method for selective N-methylation of secondary amide
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The invention relates to a method for selective N-methylation of secondary amide. The method is characterized in that the secondary amide is in an organic solvent N, N-dimethyl formamide or dimethyl sulfoxide, trifluoroacetic acid methyl ester serves as a methylation reagent, and reaction is performed in the presence of sodium hydride, potassium tert-butoxide or sodium methylate, so as to obtain aselective N-methylated product. The method has the characteristics that generally a trifluoroacetylation product is produced when the trifluoroacetic acid methyl ester is reacted with amine compounds, however a N-methylated product can be selectively obtained when the trifluoroacetic acid methyl ester is reacted with secondary amide; the method is simple to operate, low in cost, mild in reactionconditions and high in selectivity, and avoids the use of hypertoxic methylation reagents, such as dimethyl sulfate and methyl iodide.
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Paragraph 0011
(2019/03/08)
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- Well-Defined, Air-Stable, and Readily Available Precatalysts for Suzuki and Buchwald-Hartwig Cross-coupling (Transamidation) of Amides and Esters by N-C/O-C Activation
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A general class of well-defined, air-stable, and readily available Pd(II)-NHC precatalysts (NHC = N-heterocyclic carbene) for Suzuki and Buchwald-Hartwig cross-coupling of amides (transamidation) and esters by selective N-C/O-C cleavage is reported. Since these precatalysts are highly active and the easiest to synthesize, the study clearly suggests that [Pd(NHC)(acac)Cl] should be routinely included during the development of new cross-coupling methods. An assay for in situ screening of NHC salts in this cross-coupling manifold is presented.
- Zhou, Tongliang,Li, Guangchen,Nolan, Steven P.,Szostak, Michal
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supporting information
p. 3304 - 3309
(2019/05/10)
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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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- Amide Bond Formation Catalyzed by Recyclable Copper Nanoparticles Supported on Zeolite Y under Mild Conditions
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A series of catalysts based on supported copper nanoparticles have been prepared and tested in the amide bond formation from tertiary amines and acid anhydrides, in the presence of tert-butyl hydroperoxide as an oxidant. Copper nanoparticles on zeolite Y (CuNPs/ZY) was found to be the most efficient catalyst for the synthesis of amides, working in acetonitrile as solvent, under ligand- and base-free conditions in air. The products were obtained in good to excellent yields and in short reaction times. The CuNPs/ZY system also exhibited higher catalytic activity than some commercially available copper and iron sources and it was reused in ten reaction cycles without any further pre-treatment. This methodology has been successfully scaled-up to a gram scale with no detriment to the yield.
- Moglie, Yanina,Buxaderas, Eduardo,Mancini, Agustina,Alonso, Francisco,Radivoy, Gabriel
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p. 1487 - 1494
(2019/02/16)
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- Organic ligand-free carbonylation reactions with unsupported bulk Pd as catalyst
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Herein, surprising results for bulk Pd-catalyzed carbonylation reactions are presented. Three types of carbonylation reactions can be realized efficiently under organic ligand-free conditions, namely, hydroaminocarbonylation of olefins, aminocarbonylation of aryl iodides and oxidative carbonylation of amines, which almost cover all the known mechanisms in carbonylation reactions. Notably, the bulk Pd catalyst system exhibited better catalytic activity than the classical homogeneous PdCl2/(2-OMePh)3P catalyst system. This study will create a momentous and new field of green carbonylation reactions.
- Liu, Shujuan,Wang, Hongli,Dai, Xingchao,Shi, Feng
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supporting information
p. 3457 - 3462
(2018/08/06)
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- Selective N-Monoalkylation of Amide Derivatives with Trialkyl Phosphates
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A highly selective and easily handled monoalkylation of primary amide derivatives by using trialkyl phosphates as alkylating reagents in cyclopentyl methyl ether (CPME) was developed. Various monoalkylated amide derivatives were efficiently synthesized by changing the alkyl moiety (e.g., methyl, ethyl, butyl, or benzyl) of the trialkyl phosphate. These phosphate reagents are relatively stable and easily available, and CPME is a useful solvent in process chemistry.
- Asai, Shota,Ban, Kazuho,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 322 - 325
(2017/10/31)
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- Direct Synthesis of Amides from Oxidative Coupling of Benzyl Alcohols and N-substituted Formamides Using a Co–Al Based Heterogeneous Catalyst
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Present work reports the direct synthesis of amides from oxidative coupling of benzyl alcohols with various N-substituted formamides using a cobalt-hydrotalcite (Co-HT) derived catalyst. The Co-HT derived catalysts (Co-HT-2, Co-HT-3 and Co-HT-4 having Co2+/Al3+ molar ratio in the catalyst preparation mixture as 1/1, 2/1 and 3/1 respectively) were prepare following a co-precipitation method and characterized well by powder XRD, XPS, FEG-SEM, EDS, DTG–TGA, FT-IR and N2 physisorption measurements. A range of functional amides were obtained in good yields from oxidative coupling of various substituted benzyl alcohols and a range of N-substituted formamides using Co-HT-3 catalyst and oxidant TBHP. Mechanistic investigation suggests that the amidation reaction is associated with the formation and coupling of radical species. Furthermore, the Co-HT derived catalyst was easily recoverable and recyclable with retained high catalytic activity towards the oxidative coupling of benzyl alcohol with DMF. Graphical Abstract: [Figure not available: see fulltext.].
- Subhedar, Dnyaneshwar D.,Gupta, Shyam Sunder R.,Bhanage, Bhalchandra M.
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p. 3102 - 3111
(2018/08/21)
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- An organocatalyst bound α-aminoalkyl radical intermediate for controlled aerobic oxidation of iminium ions
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A catalyst bound α-aminoalkyl radical intermediate from iminium is developed to control its formation and reactivity with aerobic oxygen. The influence of the catalyst was demonstrated via the ease of radical intermediate formation and its subsequent reactivity, including the first catalyst-controlled enantioselective aerobic oxidation with a chiral phosphite catalyst.
- Motaleb, Abdul,Bera, Asish,Maity, Pradip
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supporting information
p. 5081 - 5085
(2018/07/29)
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- Cross-Dehydrogenating Coupling of Aldehydes with Amines/R-OTBS Ethers by Visible-Light Photoredox Catalysis: Synthesis of Amides, Esters, and Ureas
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A straightforward synthesis of amides, ureas, and esters is reported by visible-light cross-dehydrogenating coupling (CDC) of aldehydes (or amine carbaldehydes) and amines/R-OTBS ethers by photoredox catalysis. The reaction is found to be general and high yielding. A plausible mechanistic pathway has been proposed for these transformations and is supported by appropriate controlled experiments.
- Pandey, Ganesh,Koley, Suvajit,Talukdar, Ranadeep,Sahani, Pramod Kumar
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supporting information
p. 5861 - 5865
(2018/09/21)
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- Iridium-Catalyzed Reductive Strecker Reaction for Late-Stage Amide and Lactam Cyanation
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A new iridium-catalyzed reductive Strecker reaction for the direct and efficient formation of α-amino nitrile products from a broad range of (hetero)aromatic and aliphatic tertiary amides, and N-alkyl lactams is reported. The protocol exploits the mild and highly chemoselective reduction of the amide and lactam functionalities using IrCl(CO)[P(C6H5)3]2 (Vaska's complex) in the presence of tetramethyldisiloxane, as a reductant, to directly generate hemiaminal species able to undergo substitution by cyanide upon treatment with TMSCN (TMS=trimethylsilyl). The protocol is simple to perform, broad in scope, efficient (up to 99 % yield), and has been successfully applied to the late-stage functionalization of amide- and lactam-containing drugs, and naturally occurring alkaloids, as well as for the selective cyanation of the carbonyl carbon atom linked to the N atom of proline residues within di- and tripeptides.
- Fuentes de Arriba, ángel L.,Lenci, Elena,Sonawane, Mahendra,Formery, Odilon,Dixon, Darren J.
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supporting information
p. 3655 - 3659
(2017/03/21)
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- Interception of amide ylides with sulfonamides: Synthesis of (: E)- N -sulfonyl amidines catalyzed by Zn(OTf)2
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Through the interception of amide ylides with sulfonamides, we herein report the first general example of an intermolecular condensation reaction between sulfonamides and amides. Beyond formamides, this approach was successfully applied to a variety of lactams and linear amides, giving rise to a broad array of (E)-N-sulfonyl amidines.
- Chen, Jijun,Long, Wenhao,Fang, Shangwen,Yang, Yonggang,Wan, Xiaobing
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supporting information
p. 13256 - 13259
(2017/12/26)
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- A Manganese Pre-Catalyst: Mild Reduction of Amides, Ketones, Aldehydes, and Esters
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A new (N-phosphinoamidinate)manganese complex is shown to be a useful pre-catalyst for the hydrosilative reduction of carbonyl compounds, and in most cases at room temperature. The Mn-catalyzed reduction of tertiary amides to tertiary amines, with a useful scope, is demonstrated for the first time by use of this catalyst, and is competitive with the most effective transition-metal catalysts known for such transformations. Ketones, aldehydes, and esters were also successfully reduced under mild conditions by using this new Mn catalyst.
- Kelly, Colin M.,McDonald, Robert,Sydora, Orson L.,Stradiotto, Mark,Turculet, Laura
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supporting information
p. 15901 - 15904
(2017/12/13)
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- Ligand-free Pd(0)/SiO2-catalyzed aminocarbonylation of aryl iodides to amides under atmospheric CO pressure
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An efficient and facile route for CO-based carbonylation of aryl iodides with amines to synthesize amides has been established by using SiO2 supported Pd(0) as the catalyst in a mild basic environment (K2CO3). This ligand-free heterogeneous reaction model can afford amide products in good to excellent yields (up to 99%) under atmospheric CO pressure and moderate temperature. The supported catalyst also displayed a broad substrate scope, good functional group tolerance and good recyclability. These features render the as-provided carbonylation approach sustainable and applicable in organic synthesis.
- Hu, Qinhua,Wang, Lele,Wang, Chen,Wu, Yubin,Ding, Zhengxin,Yuan, Rusheng
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p. 37200 - 37207
(2017/08/09)
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- A high-efficient method for the amidation of carboxylic acids promoted by triphenylphosphine oxide and oxalyl chloride
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A effective amidation reaction of carboxylic acids with various amines promoted by triphenylphosphine oxide and oxalyl chloride under mild and neutral conditions has been developed. The feature of this procedure was the using and recycling of triphenylphosphine oxide at room temperature in 0.5?h. Furthermore a plausible mechanism also be deduced with the help of 31P NMR spectroscopy.
- Jiang, Lixue,Yu, Jing,Niu, Fanfan,Zhang, Derundong,Sun, Xiaoling
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- A General Method for Two-Step Transamidation of Secondary Amides Using Commercially Available, Air- and Moisture-Stable Palladium/NHC (N-Heterocyclic Carbene) Complexes
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The first general method is reported for transamidation of secondary carboxamides catalyzed by Pd-NHC (NHC = N-heterocyclic carbene) complexes. Commercially available, air- and moisture-stable (NHC)Pd(R-allyl)Cl complexes can effect C-N cross-coupling of a wide range of N-Boc and N-Ts amides, obtained by selective amide N-functionalization, with non-nucleophilic anilines and sterically hindered amines in very good yields. The first use of versatile Pd-NHC complexes as catalysts is represented for transition-metal-catalyzed C(acyl)-N amination of amides by N-C activation.
- Meng, Guangrong,Lei, Peng,Szostak, Michal
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p. 2158 - 2161
(2017/04/27)
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- Pd-PEPPSI: A general Pd-NHC precatalyst for Buchwald-Hartwig cross-coupling of esters and amides (transamidation) under the same reaction conditions
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Amides are of fundamental interest in many fields of chemistry involving organic synthesis, chemical biology and biochemistry. Here, we report the first catalytic Buchwald-Hartwig coupling of both common esters and amides by highly selective C(acyl)-X (X = O, N) cleavage to rapidly access aryl amide functionality via a cross-coupling strategy. Reactions are promoted by versatile, easily prepared, well-defined Pd-PEPPSI type precatalysts, and proceed in good to excellent yields and with excellent chemoselectivity for the acyl bond cleavage. The method is user friendly because it employs commercially-available, moisture- and air-stable precatalysts. Notably, for the first time we demonstrate selective C(acyl)-N and C(acyl)-O cleavage/Buchwald-Hartwig amination under the same reaction conditions, which allows for streamlining amide synthesis by avoiding restriction to a particular acyl metal precursor. Of broad interest, this study opens the door to using a family of well-defined Pd(ii)-NHC precatalysts bearing pyridine "throw-away" ligands for the selective C(acyl)-amination of bench-stable carboxylic acid derivatives.
- Shi, Shicheng,Szostak, Michal
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supporting information
p. 10584 - 10587
(2017/09/29)
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- Carbonylative Tertiary Amide Synthesis from Aryl Iodides and Tertiary Amines via Oxidant-Free C?N Bond Cleavage Catalyzed by Palladium(II) Chloride in Polyethylene Glycol/Water
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In this work, we have described the carbonylative synthesis of amides from aryl iodides and tertiary amines as an aminal source via oxidant-free C(sp3)?N bond cleavage using in situ formation of palladium(0) nanoparticles from palladium(II) chloride in polyethylene glycol 400/water. Notably, these reactions were performed under base-free, ligand-free conditions and do not require any oxidant for the C?N bond cleavage. The developed protocol offers the selective N-dealkylation of tertiary amines in a polyethylene glycol/water solvent system. Numerous symmetrical and unsymmetrical aliphatic, alicyclic, benzyl, as well as aromatic tertiary amines with aryl iodides were well tolerated and afforded the desired products in good yields. Furthermore, the in situ generation of palladium(0) nanoparticles in the polyethylene glycol 400 was confirmed by TEM, FEG-SEM, EDS and XRD techniques, which strongly indicate that the palladium nanoparticles are highly active species and the reaction proceeds through the classical palladium(0)/palladium(II) pathway. Additionally, the syntheses can be easily scaled up and the catalytic system can be recycled up to five times without loss of its catalytic activity and selectivity. (Figure presented.).
- Mane, Rajendra S.,Bhanage, Bhalchandra M.
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p. 2621 - 2629
(2017/08/16)
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- Selective Reductive Removal of Ester and Amide Groups from Arenes and Heteroarenes through Nickel-Catalyzed C?O and C?N Bond Activation
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An inexpensive nickel(II) catalyst and a hydrosilane were used for the efficient reductive defunctionalization of aryl and heteroaryl esters through a decarbonylative pathway. This versatile method could be used for the removal of ester and amide functional groups from various organic molecules. Moreover, a scale-up experiment and a synthetic application based on the use of a removable carboxylic acid directing group highlight the usefulness of this reaction.
- Yue, Huifeng,Guo, Lin,Lee, Shao-Chi,Liu, Xiangqian,Rueping, Magnus
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supporting information
p. 3972 - 3976
(2017/03/27)
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