- Suzuki-Miyaura Cross-Coupling of Amides using Well-Defined, Air-Stable [(PR3)2Pd(II)X2] Precatalysts
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A versatile method for the Suzuki-Miyaura cross-coupling of amides using highly active, well-defined, and air-stable Pd?phosphine precatalysts is reported. Most notably, the method represents the first example of using practical and operationally-simple Pd(II)?phosphine precatalysts in the emerging amide bond cross-coupling manifold. The reactions are efficient at 0.10 mol% loading, furnishing biaryl ketones with high chemoselectivity for N?C(O) bond cleavage. This versatile method enables for the first time to achieve Pd?phosphine-catalyzed cross-coupling of amides at ppm loading. This C?N cross-coupling can be used to efficiently furnish pharmaceutical intermediates by orthogonal Pd-catalyzed cross-couplings. We fully expect that operationally-simple [(PR3)2Pd(II)X2] precatalysts as effective triggers for N?C(O) cross-coupling will be of broad synthetic and catalytic interest. (Figure presented.).
- Li, Guangchen,Ma, Siyue,Szostak, Michal,Zhou, Tongliang
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supporting information
(2020/05/26)
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- A Nickel-Catalyzed Carbonyl-Heck Reaction
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The use of transition-metal catalysis to enable the coupling of readily available organic molecules has greatly enhanced the ability of chemists to access complex chemical structures. In this work, an intermolecular coupling reaction that unites organotriflates and aldehydes is presented. A unique catalyst system is identified to enable this reaction, featuring a Ni0 precatalyst, a tridentate Triphos ligand, and a bulky amine base. This transformation provides access to a variety of ketone-containing products without the selectivity- and reactivity-related challenges associated with more traditional Friedel–Crafts reactions. A Heck-type mechanism is postulated, wherein the π bond of the aldehyde takes the role of the olefin in the insertion/elimination steps.
- Vandavasi, Jaya Kishore,Hua, XiYe,Halima, Hamdi Ben,Newman, Stephen G.
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p. 15441 - 15445
(2017/11/10)
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- Pd-PEPPSI: A General Pd-NHC Precatalyst for Suzuki-Miyaura Cross-Coupling of Esters by C-O Cleavage
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The Suzuki-Miyaura cross-coupling of aryl esters by selective C-O bond cleavage represents a powerful methodology in organic synthesis. Here, we report that versatile, easily prepared, well-defined Pd-PEPPSI type precatalysts serve as highly reactive catalysts for the direct Suzuki-Miyaura cross-coupling of esters. Sterically and electronically diverse aryl esters couple with arylboronic acids in good to excellent yields using a single, operationally simple protocol. Kinetic studies demonstrate that the cross-coupling of aryl esters proceeds with rates similar to the cross-coupling of amides. This study strongly supports the use of well-defined Pd(II)-NHC precatalysts bearing pyridine throw-away ligands for the selective C(acyl) cleavage of bench-stable carboxylic acid derivatives. Considering the modular scaffold of Pd-NHC precatalysts, we envision that the method will be of general interest for the development of new catalysts for C-O cleavage reactions.
- Shi, Shicheng,Lei, Peng,Szostak, Michal
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p. 3784 - 3789
(2017/10/13)
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- N-Methylamino Pyrimidyl Amides (MAPA): Highly Reactive, Electronically-Activated Amides in Catalytic N-C(O) Cleavage
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Despite recent progress in catalytic cross-coupling technologies, the direct activation of N-alkyl-N-aryl amides has been a challenging transformation. Here, we report the first Suzuki cross-coupling of N-methylamino pyrimidyl amides (MAPA) enabled by the controlled nN → πAr conjugation and the resulting remodeling of the partial double bond character of the amide bond. The new mode of amide activation is suitable for generating acyl-metal intermediates from unactivated primary and secondary amides.
- Meng, Guangrong,Lalancette, Roger,Szostak, Roman,Szostak, Michal
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p. 4656 - 4659
(2017/09/12)
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- Suzuki-Miyaura Cross-Coupling of N-Acylpyrroles and Pyrazoles: Planar, Electronically Activated Amides in Catalytic N-C Cleavage
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The formation of C-C bonds from amides by catalytic activation of the amide bond has been thus far possible by steric distortion. Herein, we report the first example of a general Pd-catalyzed Suzuki-Miyaura cross-coupling of planar amides enabled by the combination of (i) electronic-activation of the amide nitrogen in N-acylpyrroles and pyrazoles and (ii) the use of a versatile Pd-NHC catalysis platform. The origin and selectivity of forming acylmetals, including the role of twist, are discussed.
- Meng, Guangrong,Szostak, Roman,Szostak, Michal
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p. 3596 - 3599
(2017/07/15)
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- Palladium-Catalyzed suzuki?Miyaura cross-Coupling of amides via site-Selective n?C bond cleavage by cooperative catalysis
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Palladium-catalyzed Suzuki?Miyaura cross-coupling of primary benzamides enabled by a merger of site-selective N,N-di-Boc-activation and cooperative catalysis via N?C bond cleavage for the synthesis of biaryl ketones is reported. We present the synergistic combination of Lewis base and palladium catalysis as a concept to activate inert amide N?C bonds. The mild reaction conditions provide a direct route to structurally diverse ketones. The reaction tolerates a wide range of electrophilic functional groups. Considering the fundamental importance of primary amides as pharmaceutical and synthetic intermediates, the strategy has a potential for developing a diverse array of valuable amide N?C bond functionalization reactions by the synergistic merger of Lewis base and organometallic catalysis.
- Meng, Guangrong,Shi, Shicheng,Szostak, Michal
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p. 7335 - 7339
(2018/05/22)
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- Palladium-catalyzed Suzuki-Miyaura coupling of amides by carbon-nitrogen cleavage: General strategy for amide N-C bond activation
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The first palladium-catalyzed Suzuki-Miyaura cross-coupling of amides with boronic acids for the synthesis of ketones by sterically-controlled N-C bond activation is reported. The transformation is characterized by operational simplicity using bench-stable, commercial reagents and catalysts, and a broad substrate scope, including substrates with electron-donating and withdrawing groups on both coupling partners, steric-hindrance, heterocycles, halides, esters and ketones. The scope and limitations are presented in the synthesis of >60 functionalized ketones. Mechanistic studies provide insight into the catalytic cycle of the cross-coupling, including the first experimental evidence for Pd insertion into the amide N-C bond. The synthetic utility is showcased by a gram-scale cross-coupling and cross-coupling at room temperature. Most importantly, this process provides a blueprint for the development of a plethora of metal catalyzed reactions of typically inert amide bonds via acyl-metal intermediates. A unified strategy for amide bond activation to enable metal insertion into N-C amide bond is outlined (Scheme 1).
- Meng, Guangrong,Szostak, Michal
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supporting information
p. 5690 - 5707
(2016/07/06)
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- Reversed-polarity synthesis of diaryl ketones via palladium-catalyzed cross-coupling of acylsilanes
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Acylsilanes serve as acyl anion equivalents in a palladium-catalyzed cross-coupling reaction with aryl bromides to give unsymmetrical diaryl ketones. Water plays a unique and crucial activating role in these reactions. High-throughput experimentation techniques provided successful reaction conditions initially involving phosphites as ligands. Ultimately, 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane was identified as giving a longer-lived catalyst with higher turnover numbers. Its use, in conjunction with a palladacycle precatalyst, led to optimal reaction rates and yields. Scope and limitations of this novel method are presented along with initial mechanistic insight.
- Schmink, Jason R.,Krska, Shane W.
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p. 19574 - 19577
(2012/01/13)
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- Pd(0)/C-catalyzed cross-couplings of acyl chlorides with triarylbismuths as atom-efficient sub-stoichiometric multi-coupling reagents
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Aromatic and hetero-aromatic acyl chlorides were efficiently cross-coupled with triarylbismuths as atom-efficient nucleophilic organometallic coupling reagents in sub-stoichiometric amounts using catalytic Pd(0)/C. Thus, the coupling reactions of various triarylbismuths with a variety of acyl chlorides furnished a plethora of both symmetrical/unsymmetrical aromatic and hetero-aromatic ketones in high yields.
- Rao, Maddali L.N.,Jadhav, Deepak N.,Venkatesh, Varadhachari
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experimental part
p. 4268 - 4271
(2009/10/26)
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- Method for acylation or sulphonylation of an aromatic compound
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The present invention relates to a process for the acylation or sulphonylation of an aromatic compound. More particularly, the invention relates to a process for the acylation or sulphonylation of an activated or deactivated aromatic compound. The invention is applied to the preparation of aromatic ketones or sulphones. The process for the acylation or sulphonylation of an aromatic compound which consists in reacting at least one aromatic compound with an acylating or sulphonylating agent, in the presence of a Friedel-Crafts catalyst is characterized in that the acylation or sulphonylation reaction is carried out in liquid phase under microwave irradiation.
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Page column 22,23
(2008/06/13)
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- Benzoylation of arenes using envirocat EPZG catalyst and microwave irradiation
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Benzoylations of several benzene, naphthalene and thiophene derivatives with benzoyl chloride or benzoie anhydride, catalyzed with EPZG catalyst and in the absence of solvents were studied under microwave irradiation (MWI). Reasonable to good yields of products were achieved in short times.
- Veverkova, Eva,Goyov, Battsengel,Mitterpach, Robert,Toma, Stefan
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p. 644 - 650
(2007/10/03)
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- Acylation of 2-Methoxynaphthalene with Acyl Clorides in the Presence of a Catalytic Amount of Lewis Acids
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The regiochemistry of the reaction of 2-methoxynaphthalene 1 with benzoyl chloride 2a using a catalytic amount of Lewis acid is strongly influenced by the identity of the acid catalyst employed as well as by the reaction temperature.By using InCl3, FeCl3, SnCl4 or ZnCl2 and heating at 160 deg C, 2-benzoyl-6-methoxynaphthalene 4a is selectively produced along with 1-benzoyl-7-methoxynaphthalene 5a, while in the case of AlCl3, SbCl5 or TiCl4, 1-benzoyl-2-methoxynaphthalene 3a is the major product. 2-Acyl-6-methoxynaphthalenes 4b-e can be selectively obtained using InCl3 and the corresponding acyl chlorides 2b-e in place of 2a.In the presence of a stoichiometric amount of InCl3, the reaction of 1 with 2a also gives 4a as the predominant product along with 5a even at 50 deg C.This reaction appears to involve isomerisation of 3a to 4a and 5a.
- Pivsa-Art, Sommai,Okuro, Kazumi,Miura, Masahiro,Murata, Satoru,Nomura, Masakatsu
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p. 1703 - 1708
(2007/10/02)
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