- Exploring the coordination chemistry of 1-benzoyl-4,5-dihydro-3,5- bis(trifluoromethyl)-1H-pyrazol-5-ol to copper
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The coordination chemistry of the ligand 1-benzoyl-4,5-dihydro-3,5- bis(trifluoromethyl)-1H-pyrazol-5-ol (1a) has been recently investigated. In dependency of the metal (e.g., nickel, zinc, molybdenum) and the added co-ligand (phosphanes, pyridines, amine
- Someya, Chika I.,Inoue, Shigeyoshi,Enthaler, Stephan
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- CuBr-catalysed oxidative desulfurisation of thiobenzamides
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An efficient oxidative desulfurisation of thioamides by CuBr/TBHP is reported. Thioamides containing alkyl or aryl on the nitrogen undergo desulfurisation and give amides with good yields. Thioamides not containing substituent on the nitrogen undergo desulfurisation and give 1,2,4-thiadiazoles in moderate to good yields.
- Cheng, Dongping,Sun, Ruirui,Yan, Jizhong
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- Molecular rearrangement of 1-substituted 3-aminoquinoline-2,4-diones in their reaction with urea and nitrourea synthesis and transformations of reaction intermediates
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1-Substituted 3-alkyl/aryl-3-amino-1H,3H-quinoline-2,4-diones (6) react with nitrourea to give 3-ureido-1H,3H-quinoline-2,4-diones (10), 9b-hydroxy-3,3a,5,9b-tetrahydro-1H-imidazo[4,5-c]quinoline-2,4-diones (11), and 3,3a-dihydro-5H-imidazo[4,5-c]quinoline-2,4-diones (12). Compounds 11 were dehydrated to 12 by the action of phosphorus pentoxide. All three types of compounds rearrange in boiling acetic acid to give three different types of products of molecular rearrangement. A proposed reaction mechanism is discussed.
- Klasek, Antonin,Lyoka, Antonin,Holcapek, Michal,Kovar, Michal,Hoza, Ignac
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- Gas-phase formation of protonated benzene during collision-induced dissociation of certain protonated mono-substituted aromatic molecules produced in electrospray ionization
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Protonated benzene, C6H+7, has been studied extensively to understand the structure and energy of a protonated organic molecule in the gas phase. The formation of C6H+7 is either through direct protonation of benzene, i.e., chemical ionization, or through fragmentation of certain radical cations produced from electron ionization or photon ionization. We report a novel observation of C6H+7 as a product ion formed in the collision-induced dissociation (CID) of protonated benzamide and related molecules produced via electrospray ionization (ESI). The formation of C6H+7 from these even-electron precursor ions during the CID process, which has not been previously reported, is proposed to occur from the protonated molecules via a proton migration in a five-membered ring intermediate followed by the cleavage of the mono-substituent C-C bond and concurrent formation of an ion-molecule complex. This unique mechanism has been scrutinized by examining some deuterated molecules and a series of structurally related model compounds. This finding provides a convenient mean to generate C6H+7, a reactive intermediate of considerable interest, for further physical or chemical investigation. Further studies indicate that the occurrence of C6H+7 in liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) appears to be a rather common phenomenon for many compounds that contain 'benzoyl-type' moieties. Hence, the observation of the C6H+7 ion in LC/ESI-MS/MS can be used as an informative fragmentation pathway which should facilitate the identification of a great number of compounds containing the 'benzoyl-type' and similar structural features. These compounds are frequently present in food and pharmaceutical products as leachable impurities that require strict control and rapid elucidation of their identities.
- Li, Min,Lin, Mingxiang,Rustum, Abu M.
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- Facile synthesis of phosphaamidines and phosphaamidinates using nitrilium ions as an imine synthon
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Readily accessible nitrilium triflates are convenient imine building blocks for the expedient synthesis of a novel class of 1,3-P,N ligands as demonstrated for the reaction with primary phosphanes. This procedure allows variation of all substituents. X-ray crystal structures are reported for nitrilium ions, phosphaamidines, and three phosphaamidinate complexes. The lithium phosphaamidinate is N coordinated and its reaction with [AuCl(tht)] (tht=tetrahydrothiophene) gives a unique P-bridged gold trimer, while a P,N-bidentate complex results from [{RhCl(cod)}2]. The nitrilium ion methodology allows extension of the 1,3-P,N motive to bis(imino)phosphanes, which are the neutral phosphorus analogues of the valuable β-diketiminate ligand.
- Van Dijk, Tom,Burck, Sebastian,Rong, Mark K.,Rosenthal, Amos J.,Nieger, Martin,Slootweg, J. Chris,Lammertsma, Koop
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- AMINE-BORANES AS BIFUNCTIONAL REAGENTS FOR DIRECT AMIDATION OF CARBOXYLIC ACIDS
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The present invention generally relates to a process for selective and direct activation and subsequent amidation of aliphatic and aromatic carboxylic acids to afford an amide R3CONR1R2. That the process is capable of delivering gaseous or low-boiling point amines provides a major advantage over existing methodologies, which involves an intermediate of triacyloxyborane-amine complex [(R3CO2)3—B—NHR1R2]. This procedure readily produces primary, secondary, and tertiary amides, and is compatible with the chirality of the acid and amine involved. The preparation of known pharmaceutical molecules and intermediates has also been demonstrated.
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Paragraph 0008-0009; 0063-0064
(2022/03/04)
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- Photocatalysis in Aqueous Micellar Media Enables Divergent C-H Arylation and N-Dealkylation of Benzamides
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Photocatalysis in aqueous micellar media has recently opened wide avenues to activate strong carbon-halide bonds. So far, however, it has mainly explored strongly reducing conditions, restricting the available chemical space to radical or anionic reactivity. Here, we demonstrate a controllable, photocatalytic strategy that channels the reaction of chlorinated benzamides via either a radical or a cationic pathway, enabling a chemodivergent C-H arylation or N-dealkylation. The catalytic system operates under mild conditions with methylene blue as a photocatalyst and blue LEDs as the light source. Factors determining the reactivity of substrates, their selectivity, and preliminary mechanistic studies are presented.
- Cybularczyk-Cecotka, Martyna,Predygier, J?drzej,Crespi, Stefano,Szczepanik, Joanna,Giedyk, MacIej
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p. 3543 - 3549
(2022/03/27)
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- Weak base-promoted selective rearrangement of oxaziridines to amidesviavisible-light photoredox catalysis
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The selective rearrangement of oxaziridines to amidesviaa single electron transfer (SET) pathway is unexplored. In this study, we present a weak base-promoted selective rearrangement of oxaziridines to amidesviavisible-light photoredox catalysis. The developed method shows excellent functional group tolerance with a broad substrate scope and good to excellent yields. Furthermore, control experiments and density functional theory (DFT) calculations are performed to gain insight into the reactivity and selectivity.
- Park, Jin,Park, Sehoon,Jang, Gwang Seok,Kim, Ran Hui,Jung, Jaehoon,Woo, Sang Kook
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supporting information
p. 9995 - 9998
(2021/10/06)
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- Photocatalyzed Triplet Sensitization of Oximes Using Visible Light Provides a Route to Nonclassical Beckmann Rearrangement Products
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Oximes are valuable synthetic intermediates for the preparation of a variety of functional groups. To date, the stereoselective synthesis of oximes remains a major challenge, as most current synthetic methods either provide mixtures of E and Z isomers or furnish the thermodynamically preferred E isomer. Herein we report a mild and general method to achieve Z isomers of aryl oximes by photoisomerization of oximes via visible-light-mediated energy transfer (EnT) catalysis. Facile access to (Z)-oximes provides opportunities to achieve regio- and chemoselectivity complementary to those of widely used transformations employing oxime starting materials. We show an enhanced one-pot protocol for photocatalyzed oxime isomerization and subsequent Beckmann rearrangement that enables novel reactivity with alkyl groups migrating preferentially over aryl groups, reversing the regioselectivity of the traditional Beckmann reaction. Chemodivergent N- or O- cyclizations of alkenyl oximes are also demonstrated, leading to nitrones or cyclic oxime ethers, respectively.
- Zhang, Xiao,Rovis, Tomislav
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p. 21211 - 21217
(2021/12/27)
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- A case study of Pd?Pd intramolecular interaction in a benzothiazole based palladacycle; catalytic activity toward amide synthesisviaan isocyanide insertion pathway
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An acetate bridge benzothiazolepalladacycle containing a rare metallophilic intramolecular Pd?Pd interaction was synthesized and thoroughly characterized. The synthesized benzothiazolepalladacycle directly anchored on SBA-15 to form an efficient heterogen
- Loni, Masood,Balmohammadi, Yaser,Dadgar Yeganeh, Reza,Imani, Kaveh,Notash, Behrouz,Bazgir, Ayoob
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supporting information
p. 3290 - 3297
(2021/02/26)
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- Photochemical Activation of Aromatic Aldehydes: Synthesis of Amides, Hydroxamic Acids and Esters
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A cheap, facile and metal-free photochemical protocol for the activation of aromatic aldehydes has been developed. Utilizing thioxanthen-9-one as the photocatalyst and cheap household lamps as the light source, a variety of aromatic aldehydes have been activated and subsequently converted in a one-pot reaction into amides, hydroxamic acids and esters in good to high yields. The applicability of this method was highlighted in the synthesis of Moclobemide, a drug against depression and social anxiety. Extended and detailed mechanistic studies have been conducted, in order to determine a plausible mechanism for the reaction.
- Nikitas, Nikolaos F.,Apostolopoulou, Mary K.,Skolia, Elpida,Tsoukaki, Anna,Kokotos, Christoforos G.
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p. 7915 - 7922
(2021/05/03)
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- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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p. 5022 - 5037
(2021/05/04)
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- Development of a triazinedione-based dehydrative condensing reagent containing 4-(dimethylamino)pyridine as an acyl transfer catalyst
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A new triazinedione-based reagent, (N,N′-dialkyl)triazinedione-4-(dimethylamino)pyridine (ATD-DMAP) was developed for the operationally simple dehydrative condensation of carboxylic acids. This reagent comprises an ATD core and DMAP as the leaving group, which is liberated into the reaction system to accelerate acyl transfer reactions. Upon adding ATD-DMAP to a mixture of carboxylic acids and alcohols in the presence of an amine base, the corresponding esters were formed rapidly at room temperature. Moreover, dehydrative condensation between carboxylic acids and amines using ATD-DMAP proceeded in high yield.
- Liu, Jie,Fujita, Hikaru,Kitamura, Masanori,Shimada, Daichi,Kunishima, Munetaka
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supporting information
p. 4712 - 4719
(2021/06/11)
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- Ammonia-borane as a Catalyst for the Direct Amidation of Carboxylic Acids
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Ammonia-borane serves as an efficient substoichiometric (10%) precatalyst for the direct amidation of both aromatic and aliphatic carboxylic acids. In situ generation of amine-boranes precedes the amidation and, unlike the amidation with stoichiometric amine-boranes, this process is facile with 1 equiv of the acid. This methodology has high functional group tolerance and chromatography-free purification but is not amenable for esterification. The latter feature has been exploited to prepare hydroxyl- and thiol-containing amides.
- Ramachandran, P. Veeraraghavan,Hamann, Henry J.
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supporting information
p. 2938 - 2942
(2021/05/04)
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- Method for preparing amide from carboxylic acid under irradiation of blue light by taking iridium and cobalt complexes as catalysts
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The invention relates to a method for preparing amide from carboxylic acid under the irradiation of blue light by taking iridium and cobalt complexes as catalysts, and belongs to the field of chemistry. The method comprises the following step of: by taking R substituted carboxylic acid and R1' and R2' substituted amines as raw materials, triphenylphosphine as a deoxidizing agent, [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 as a photocatalyst and Co(dmgH)(dmgH2)Cl2 as a metal complex catalyst, reacting in dichloromethane in an inert atmosphere and under the irradiation of blue light to obtain an amide compound, wherein R is an aryl group, a heteroaryl group, a protected amino group, a substituted alkyl group, a substituted aryl group or a substituted protected amino group, R1' is a hydrogen group, a substituted alkyl group, a phenyl group or a substituted phenyl group, and R2' is a hydrogen group, a substituted alkyl group, a phenyl group or a substituted phenyl group.
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Paragraph 0077-0078
(2021/05/12)
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- Crystal structure of 1-(2,4,6-trichlorobenzoyloxy) benzotriazole (TCB-OBt): observation of uncommon intermolecular oxygen-oxygen interaction and synthetic application in amidation
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Herein, we investigated the supramolecular assembly of a modified Yamaguchi reagent TCB-OBt. Interestingly, each molecule is interconnected through novel chalcogen-chalcogen (O?O) interaction, π-π stacking, and aromatic C-H?O interaction. Hirshfeld surface analysis confirmed the existence of uncommon O?O interactions. A well-organized supramolecular layer structure and helical arrangement were observed in the crystal structure. TCB-OBt crystallized in the O-substituted desmotropic form. DFT calculations suggest that the O-substituted form is more stable than theN-substituted form (TCB-(N)-OBt). Morphology analysis indicates the formation of a fantastically well organized, continuous block-shaped system. Furthermore, the designed reagent works as an efficient activating reagent for amide bond formation with good yields under mild reaction conditions. Use of this reagent avoided intractable acid chlorides, and this new mixed-anhydride-based reagent may further be applicable for many other organic transformations.
- Dolai, Gobinda,Giri, Rajat Subhra,Mandal, Bhubaneswar,Roy, Sayanta,Sen, Srijit
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p. 19804 - 19811
(2021/11/12)
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- Regioselective Synthesis of 2° Amides Using Visible-Light-Induced Photoredox-Catalyzed Nonaqueous Oxidative C-N Cleavage of N, N-Dibenzylanilines
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A visible-light-driven photoredox-catalyzed nonaqueous oxidative C-N cleavage of N,N-dibenzylanilines to 2° amides is reported. Further, we have applied this protocol on 2-(dibenzylamino)benzamide to afford quinazolinones with (NH4)2S2O8 as an additive. Mechanistic studies imply that the reaction might undergo in situ generation of α-amino radical to imine by C-N bond cleavage followed by the addition of superoxide ion to form amides.
- Neerathilingam, Nalladhambi,Bhargava Reddy, Mandapati,Anandhan, Ramasamy
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p. 15117 - 15127
(2021/10/25)
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- Synthesis of Benzoisoselenazolones via Rh(III)-Catalyzed Direct Annulative Selenation by Using Elemental Selenium
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Isoselenazolone derivatives have attracted significant research interest because of their potent therapeutic activities and indispensable applications in organic synthesis. Efficient construction of functionalized isoselenazolone scaffolds is still challenging, and thus new synthetic approaches with improved operational simplicity have been of particular interest. In this manuscript, we introduce a rhodium-catalyzed direct selenium annulation by using stable and tractable elemental selenium. A series of benzamides as well as acrylamides were successfully coupled with selenium under mild reaction conditions, and the obtained isoselenazolones could be pivotal synthetic precursors for several organoselenium compounds. Based on the designed control experiments and X-ray absorption spectroscopy measurements, we propose an unprecedented selenation mechanism involving a highly electrophilic Se(IV) species as the reactive selenium donor. The reaction mechanism was further verified by a computational study.
- Xu-Xu, Qing-Feng,Nishii, Yuji,Uetake, Yuta,Sakurai, Hidehiro,Miura, Masahiro
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supporting information
p. 17952 - 17959
(2021/11/16)
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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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- Zirconium Oxide-Catalyzed Direct Amidation of Unactivated Esters under Continuous-Flow Conditions
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A sustainable and environmentally benign direct amidation reaction of unactivated esters with amines has been developed in a continuous-flow system. A commercially available amorphous zirconium oxide was found to be an efficient catalyst for this reaction. While the typical amidation of esters with amines requires a stoichiometric amount of a promoter or metal activator, the present continuous-flow method enabled the direct amidation reaction under additive-free conditions with an extensive diversity towards various functional groups. High yields of the products were obtained with a nearly equimolar proportion of starting materials to reduce byproduct formation, which renders this process applicable for use in a sequential-flow system. (Figure presented.).
- Rashed, Md. Nurnobi,Masuda, Koichiro,Ichitsuka, Tomohiro,Koumura, Nagatoshi,Sato, Kazuhiko,Kobayashi, Shū
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p. 2529 - 2535
(2021/02/01)
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- Titanium and Cobalt Bimetallic Radical Redox Relay for the Isomerization of N -Bz Aziridines to Allylic Amides
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Herein a bimetallic radical redox-relay strategy is employed to generate alkyl radicals under mild conditions with titanium(III) catalysis and terminated via hydrogen atom transfer with cobalt(II) catalysis to enact base-free isomerizations of N-Bz aziridines to N-Bz allylic amides. This reaction provides an alternative strategy for the synthesis of allylic amides from alkenes via a three-step sequence to accomplish a formal transpositional allylic amination.
- Wood, Devin P.,Guan, Weiyang,Lin, Song
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supporting information
p. 4213 - 4220
(2021/08/10)
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- Catalyst-free synthesis of phenanthridinesviaelectrochemical coupling of 2-isocyanobiphenyls and amines
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Catalyst free synthesis of 6-aryl phenanthridines and amides through an electrochemical reaction is reported in this study. The coupling reaction proceeds by the cathodic reduction ofin situformed diazonium ions, which are formed from anilines and an alkyl nitrite. The generated aryl radical diazonium ions coupled from isocyanides furnished the desired products in good yields. This cascade reaction was conducted in an undivided cell equipped with an RVC as the anode and Pt as the cathode usingnBu4NBF4as the electrolyte at room temperature. A series of detailed mechanistic studies have also been performed, including a radical clock experiment and cyclic voltammetry analysis.
- Malviya, Bhanwar Kumar,Singh, Karandeep,Jaiswal, Pradeep K.,Karnatak, Manvika,Verma, Ved Prakash,Badsara, Satpal Singh,Sharma, Siddharth
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p. 6367 - 6378
(2021/04/16)
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- Practical one-pot amidation of N -Alloc-, N -Boc-, and N -Cbz protected amines under mild conditions
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A facile one-pot synthesis of amides from N-Alloc-, N-Boc-, and N-Cbz-protected amines has been described. The reactions involve the use of isocyanate intermediates, which are generated in situ in the presence of 2-chloropyridine and trifluoromethanesulfonyl anhydride, to react with Grignard reagents to produce the corresponding amides. Using this reaction protocol, a variety of N-Alloc-, N-Boc-, and N-Cbz-protected aliphatic amines and aryl amines were efficiently converted to amides with high yields. This method is highly effective for the synthesis of amides and offers a promising approach for facile amidation.
- Hong, Wan Pyo,Tran, Van Hieu,Kim, Hee-Kwon
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p. 15890 - 15895
(2021/05/19)
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- Metal-free Photocatalytic Intermolecular anti-Markovnikov Hydroamination of Unactivated Alkenes
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The development of photocatalytic intermolecular hydroamination reaction between N-aminated dihydropyridines and unactivated alkenes is reported. Metal-free co-catalysts, rhodamine 6G and thiophenol, in presence of visible light are used to initiate the process. The transformation shows a broad substrate scope, both alkenes and amidyl radical can act as coupling partners. The radical strategy provides excellent anti-Markovnikov selectivity and regioselectivity in diene substrates.
- Li, Juncheng,Wang, Ting,Zhao, Gaoyuan
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supporting information
p. 2650 - 2654
(2021/06/25)
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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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- Oxidative Amidation of Amines in Tandem with Transamidation: A Route to Amides Using Visible-Light Energy
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A methodology is reported for preparing amides using amines as an acyl source. The protocol involves the visible-light-promoted oxidative amidation of amines with pyrazole to synthesize N-acyl pyrazoles followed by transamidation. By combining photoredox catalysis with oxoammonium cations in the presence of sodium persulfate as a terminal oxidant, the N-acyl pyrazoles could be prepared efficiently and effectively using blue LEDs. The transamidation step was performed without the need to purify the N-acyl pyrazole intermediate, and a range of amides were generated in good to excellent yields.
- Nandi, Jyoti,Vaughan, Matthew Z.,Sandoval, Arturo León,Paolillo, Joshua M.,Leadbeater, Nicholas E.
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p. 9219 - 9229
(2020/08/14)
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- Direct synthesis of secondary amides from ketones through Beckmann rearrangement using O-(mesitylsulfonyl)hydroxylamine
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The Beckmann rearrangement is a versatile method for the preparation of secondary amides from ketones via oxime intermediates and has been widely used in the synthesis of bioactive natural products and pharmaceuticals. Herein, we have developed a highly efficient direct method for the preparation of secondary amides and lactams from ketones using O-(mesitylsulfonyl)hydroxylamine (MSH). The reactions proceed rapidly at room temperature under mild condition without requiring any additive, and tolerate multiple functional groups. A simple aqueous work-up often furnished the products in excellent yield with high purity.
- Chandra, Dinesh,Verma, Saumya,Pandey, Chandra Bhan,Yadav, Ajay K.,Kumar, Puneet,Tiwari, Bhoopendra,Jat, Jawahar L.
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supporting information
(2020/03/23)
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- Organophotoredox-Mediated Amide Synthesis by Coupling Alcohol and Amine through Aerobic Oxidation of Alcohol
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The combination of an organic photocatalyst [4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6 dicyanobenzene) or 5MeOCzBN (2,3,4,5,6-pentakis(3,6-dimethoxy-9 H-carbazol-9-yl)benzonitrile)], quinuclidine, and tetra-n-butylammonium phosphate (hydrogen-bonding catalyst) was employed for amide bond formations. The hydrogen-bonded OH group activated the adjacent C?H bond of alcohols towards hydrogen atom transfer (HAT) by a radical species. The quinuclidinium radical cation, generated through single-electron oxidation of quinuclidine by the photocatalyst, employed to abstract a hydrogen atom from the α-C?H bond of alcohols selectively due to a polarity effect-produced α-hydroxyalkyl radical, which subsequently converted to the corresponding aldehyde under aerobic conditions. Then the coupling of the aldehyde and an amine formed a hemiaminal intermediate that upon photocatalytic oxidation produced the amide.
- Samanta, Samya,Shah, Sk. Sheriff,Shee, Maniklal,Singh, Amit Kumar,Singh, N. D. Pradeep,Venkatesh, Yarra
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- Copper(II)-Photocatalyzed N-H Alkylation with Alkanes
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We report a practical method for the alkylation of N-H bonds with alkanes using a photoinduced copper(II) peroxide catalytic system. Upon light irradiation, the peroxide serves as a hydrogen atom transfer reagent to activate stable C(sp3)-H bonds for the reaction with a broad range of nitrogen nucleophiles. The method enables the chemoselective alkylation of amides and is utilized for the late-stage functionalization of N-H bond containing pharmaceuticals with good to excellent yields. The mechanism of the reaction was preliminarily investigated by radical trapping experiments and spectroscopic methods.
- Donabauer, Karsten,K?nig, Burkhard,Narobe, Rok,Yakubov, Shahboz,Zheng, Yi-Wen
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p. 8582 - 8589
(2020/09/23)
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- Graphene oxide: A convenient metal-free carbocatalyst for facilitating amidation of esters with amines
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Herein, we report a graphene oxide (GO) catalyzed condensation of non-activated esters and amines, that can enable diverse amides to be synthesized from abundant ethyl esters forming only volatile alcohol as a by-product. GO accelerates ester to amide conversion in the absence of any additives, unlike other catalysts. A wide range of ester and amine substrates are screened to yield the respective amides in good to excellent yields. The improved catalytic activity can be ascribed to the oxygenated functionalities present on the graphene oxide surface which forms H-bonding with the reactants accelerating the reaction. Improved yields and a wide range of functional group tolerance are some of the important features of the developed protocol.
- Patel, Khushbu P.,Gayakwad, Eknath M.,Shankarling, Ganapati S.
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p. 2661 - 2668
(2020/02/20)
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- Synthetic method for preparing amide compounds through co-catalysis of niobium pentachloride and ionic liquid
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The invention relates to a synthetic method for preparing amide compounds through co-catalysis of niobium pentachloride and ionic liquid. The preparation method is characterized by comprising the following steps: weighing organic carboxylic acid, organic amine, niobium pentachloride, ionic liquid and a molecular sieve, adding the materials into a reactor, adding an organic solvent, and reacting for 6-24 hours at the reaction temperature of 70-110 DEG C to obtain a corresponding amide product. The molar ratio of the organic carboxylic acid to the organic amine to the niobium pentachloride to the ionic liquid is 1:(1-3):(0.01-1):(0.05-1); wherein the mass ratio of the organic carboxylic acid to the molecular sieve is 1: (0.2-1). According to the method, the substrate range is expanded, the reaction yield is high (95% or above), the catalyst dosage is small, the atom economy is high, the catalyst is cheap and easy to obtain, the production cost can be greatly reduced, and the method is suitable for industrial production.
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Paragraph 0056-0058
(2020/07/13)
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- Tris(o-phenylenedioxy)cyclotriphosphazene as a Promoter for the Formation of Amide Bonds between Aromatic Acids and Amines
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The atom-efficient formation of amide bonds has emerged as a top-priority research field in organic synthesis, as amide bonds constitute the backbones of proteins and represent an important structural motif in drug molecules. Currently, the increasing demand for novel discoveries in this field has focused substantial attention on this challenging subject. Herein, the degradable 1,3,5-triazo-2,4,6-triphosphorine (TAP) motif is presented as a new condensation system for the dehydrative formation of amide bonds between diverse combinations of aromatic carboxylic acids and amines. The underlying reaction mechanism was investigated, and potential catalyst intermediates were characterized using 31 P NMR spectroscopy and ESI mass spectrometry.
- Movahed, Farzaneh Soleymani,Sawant, Dinesh N.,Bagal, Dattatraya B.,Saito, Susumu
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p. 3253 - 3262
(2020/11/02)
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- An unprecedented cobalt-catalyzed selective aroylation of primary amines with aroyl peroxides
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A novel and facile cobalt-catalyzed selective aroylation of primary amines with aroyl peroxides was developed for the synthesis of aryl amides. It was unprecedented that C[sbnd]N bond formation product was selectively generated without the common N[sbnd]O bond formation product. Aroyl peroxides act as the sole aroylation reagent without additional base or oxidant. The reactions proceeded under mild conditions and showed broad substrates scope with a series of primary amines and aroyl peroxides.
- Li, Dong,Li, Jiale,Li, Juanjuan,Yuan, Songdong,Zhang, Qian
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supporting information
(2020/09/16)
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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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- 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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- Visible-light-induced Beckmann rearrangement by organic photoredox catalysis
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A facile and general strategy for efficient direct conversion of oximes to amides using an inexpensive organic photocatalyst and visible light is described. This radical Beckmann rearrangement can be performed under mild conditions. Various alkyl aryl ketoximes and diaryl ketoximes can be effectively converted into the corresponding amides in excellent yields.
- Tang, Li,Wang, Zhi-Lv,Wan, Hai-Lan,He, Yan-Hong,Guan, Zhi
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supporting information
p. 6182 - 6186
(2020/09/01)
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- An Electrochemical Beckmann Rearrangement: Traditional Reaction via Modern Radical Mechanism
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Abstract: Electrosynthesis as a potential means of introducing heteroatoms into the carbon framework is rarely studied. Herein, the electrochemical Beckmann rearrangement, i. e. the direct electrolysis of ketoximes to amides, is presented for the first time. Using a constant current as the driving force, the reaction can be easily carried out under neutral conditions at room temperature. Based on a series of mechanistic studies, a novel radical Beckmann rearrangement mechanism is proposed. This electrochemical Beckmann rearrangement does not follow the trans-migration rule of the classical Beckmann rearrangement.
- Tang, Li,Wang, Zhi-Lv,He, Yan-Hong,Guan, Zhi
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p. 4929 - 4936
(2020/08/21)
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- Nickel-catalyzed reductive amidation of aryl-triazine ethers
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The reaction of activated phenolic compounds, 2,4,6-triaryloxy-1,3,5-triazine (aryl-triazine ethers), with various isocyanates or carbodiimides in the presence of a nickel pre-catalyst resulted in the synthesis of aryl amides in good to excellent yields.
- Heravi, Majid M.,Panahi, Farhad,Iranpoor, Nasser
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supporting information
p. 1992 - 1995
(2020/02/22)
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- Triethyl Phosphite/Benzoyl Peroxide Mediated Reductive Dealkylation of O-Benzoylhydroxylamines: A Cascade Synthesis of Secondary Amides
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A new triethyl phosphite/benzoyl peroxide (BPO) mediated system has been developed for the synthesis of secondary amides with good to excellent yields in a single step. This unprecedented cascade process involves sequential reduction of N–O bond and benzoylation followed by dealkylation of N–C bond of O-benzoylhydroxylamines (O-BHA). The methodology is versatile as it tolerates a variety of aromatic and aliphatic O-BHA as substrates to access secondary amides.
- Aegurla, Balakrishna,Mandle, Ram D.,Shinde, Prasad G.,Parit, Ratan S.,Kamble, Sanjay P.,Sudalai, Arumugam,Senthilkumar, Beeran
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supporting information
p. 4235 - 4238
(2020/07/04)
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- Amine-Mediated Bond Cleavage in Oxidized Lignin Models
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Introducing amines/ammonia into lignin cracking will allow novel bond cleavage pathways. Herein, a method of amines/ammonia-mediated bond cleavage in oxidized lignin β-O-4 models was studied using a copper catalyst at room temperature, demonstrating the effect of the amine source on the selectivity of products. For primary and secondary aliphatic amines, lignin ketone models underwent oxidative Cα?Cβ bond cleavage and Cα?N bond formation to generate aromatic amides. For ammonia, the competition between oxygen and ammonia determined the selectivity between Cα?N and Cβ?N bond formation, generating amides and α-keto amides, respectively. For tertiary amines, the lignin models underwent oxidative Cα?Cβ bond cleavage to benzoic acids. Control experiments indicated that amines act as nucleophiles attacking at the Cα or Cβ position of the oxidized β-O-4 linkage to be cleaved. This study represents a novel example that the breakage of oxidized lignin model can be regulated by amines with a copper catalyst.
- Li, Hongji,Liu, Meijiang,Liu, Huifang,Luo, Nengchao,Zhang, Chaofeng,Wang, Feng
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p. 4660 - 4665
(2020/07/04)
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- Pyridine-Enabled C-N Bond Activation for the Rapid Construction of Amides and 4-Pyridylglyoxamides by Cooperative Palladium/Copper Catalysis
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A pyridine-enabled C-N bond activation of peptidomimetics employing cooperative palladium/copper catalysis in water is developed. Diverse amides and 4-pyridylglyoxamides are simultaneously synthesized through two steps from commercially available materials in a rapid, environmentally friendly, and high atom-economical manner.
- Song, Liangliang,Claessen, Sander,Van Der Eycken, Erik V.
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p. 8045 - 8054
(2020/07/15)
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- Amine-boranes as Dual-Purpose Reagents for Direct Amidation of Carboxylic Acids
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Amine-boranes serve as dual-purpose reagents for direct amidation, activating aliphatic and aromatic carboxylic acids and, subsequently, delivering amines to provide the corresponding amides in up to 99% yields. Delivery of gaseous or low-boiling amines as their borane complexes provides a major advantage over existing methodologies. Utilizing amine-boranes containing borane incompatible functionalities allows for the preparation of functionalized amides. An intermolecular mechanism proceeding through a triacyloxyborane-amine complex is proposed.
- Choudhary, Shivani,Hamann, Henry J.,Ramachandran, P. Veeraraghavan
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supporting information
(2020/11/13)
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- Cycloisomerization of Olefins in Water
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Preparative reactions that occur efficiently under dilute, buffered, aqueous conditions in the presence of biomolecules find application in ligation, peptide synthesis, and polynucleotide synthesis and sequencing. However, the identification of functional
- Chen, Jason S.,Chun, Yuge,Dang, Vuong Q.,Dushin, Russell G.,Green, Samantha A.,Matos, Jeishla L. M.,Paegel, Brian M.,Piotrowski, David W.,Richardson, Paul,Shenvi, Ryan A.
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supporting information
p. 12998 - 13003
(2020/06/02)
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- N-acylcarbazole as a selective transamidation reagent
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N-acylation reaction offers an opportunity to develop an efficient synthesis of amide group-containing molecules. We found that N-acyl carbazoles showed remarkable selectivity in transamidation. Sterically less hindered primary amines are selectively acylated with N-acyl carbazoles without any additives. Various functional groups such as alcohol, phenol, indole, and aniline moieties are tolerated under mild conditions. The synthetic utility was displayed in one-pot synthesis of an N-acyl polyamine natural product. The terminal amines of spermidine were selectively benzoylated with N-benzoyl carbazole, followed by acetylation reaction accomplished the total synthesis in a highly efficient manner.
- Kang, Bubwoong,Kuse, Masaki,Okamura, Hironori,Sakai, Asumi,Satoh, Tetsuya,Shinada, Tetsuro,Yasuno, Yoko
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p. 993 - 999
(2020/09/22)
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- Nickel/briphos-catalyzed transamidation of unactivated tertiary amides
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The transamidation of tertiary amides was achieved via nickel catalysis in combination with briphos ligands. N-Methyl-N-phenylbenzamide derivatives reacted with primary amines in the presence of NiCl2/briphos L4 to provide the transamidated products in moderate to good yields. Primary aromatic amines delivered higher product yields than aliphatic amines.
- Kim, Hyunwoo,Lee, Sunwoo,Shin, Taeil,Yang, Dahyeon
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supporting information
p. 6053 - 6057
(2020/10/27)
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- Tert -Butyl nitrite promoted transamidation of secondary amides under metal and catalyst free conditions
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A mild and efficient method is demonstrated for the transamidation of secondary amides with various amines including primary, secondary, cyclic and acyclic amines in the presence of tert-butyl nitrite. The reaction proceeds through the N-nitrosamide intermediate and provides the transamidation products in good to excellent yields at room temperature. Moreover, the developed methodology does not require any catalyst or additives.
- Sureshbabu, Popuri,Azeez, Sadaf,Chaudhary, Priyanka,Kandasamy, Jeyakumar
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supporting information
p. 845 - 850
(2019/01/30)
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- Synthesis of Amides by Mild Palladium-Catalyzed Aminocarbonylation of Arylsilanes with Amines Enabled by Copper(II) Fluoride
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A general Pd-catalyzed synthesis of amides by oxidative aminocarbonylation of arylsilanes under mild conditions was accomplished for the first time. The reaction is promoted by a commercially available copper(II) fluoride, which acts as a dual silane activator and mild oxidant, enabling highly efficient aminocarbonylation of versatile arylsilanes at atmospheric CO pressure. The reaction is tolerant of a wide range of arylsilanes and various sensitive halide functional groups as well as a broad scope of amines are compatible with this oxidative process using cheap CO. A significant aspect involves the increased efficiency by the catalyst system. The reaction represents a segue into the powerful Pd-catalyzed oxidative transformations of organosilanes.
- Zhang, Jin,Hou, Yanyan,Ma, Yangmin,Szostak, Michal
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p. 338 - 345
(2019/01/10)
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- Secondary/tertiary amide compound and synthesis method thereof
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The invention discloses a secondary/tertiary amide compound and a synthesis method thereof. The method comprises the following steps: adding arylsilane and an amine compound, a catalyst and an additive to a solvent, introducing CO under a certain pressure, carrying out a carbonylation reaction, and carrying out separation and purification to obtain the secondary/tertiary amide. The method for preparing the secondary/tertiary amide by the carbonylation reaction has the advantages of concision, high efficiency, directness in the reaction, high atom economy, and wide sources and good stability ofa substrate. The reaction system of the invention does not require inert gas protection, and has mild conditions, and the target product is easy to separate and the yield reaches up to 92% under optimized reaction conditions.
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Paragraph 0109; 0110; 0111; 0112; 0114
(2019/01/21)
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- FeCl2·4H2O catalyzed ritter reaction with nitriles and halohydrocarbons
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An efficient and inexpensive synthesis of N-substituted amides from the Ritter reaction of nitriles with various halohydrocarbons catalyzed by FeCl2·4H2O is described. FeCl2·4H2O economically efficiently catalyzed the Ritter reaction under solvent-free conditions. A range of halohydrocarbons (benzyl, tert-butyl and sec-alkyl halohydrocarbons) were coupled with nitriles to provide the corresponding amides in high to excellent yields.
- Feng, Cheng-Liang,Yin, Gui-Bo,Yan, Bin,Chen, Jun-Qing,Ji, Min
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p. 345 - 353
(2019/02/12)
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- A Diaminopropane Diolefin Ru(0) Complex Catalyzes Hydrogenation and Dehydrogenation Reactions
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New ruthenium (0) complexes with a cooperative diolefin diaminopropane (DAP) or the dehydrogenated iminopropenamide ligand (IPA) were synthesized for comparison with their diaminoethane (DAE)/ diazadiene (DAD) ruthenium analogues. These DAP/IPA complexes are efficient catalysts in dehydrogenation reactions of alkaline aqueous methanol which proceeds under mild conditions (T=70 °C) and of higher alcohols, forming the corresponding carbonate and carboxylates, respectively. The scope of the reaction includes an example of a 1,2-diol as model for biomass derived alcohols. Their catalytic applications are extended to the atom-efficient dehydrogenative coupling of alcohols and amines to amides. The reaction proceeds without any additives and is applicable to the synthesis of formamides from methanol. Moreover, DAP/IPA complexes catalyze the hydrogenation of a series of esters, lactone, ketone, activated olefin, aldehyde and imine substrates. The diaminopropane Ru catalyst exhibits higher activity compared to the dehydrogenated β-ketiminate (IPA) and previously studied DAD/DAE based catalysts. We present studies on their stoichiometric reactivity with relevance to their possible catalytic mechanisms and the isolation and full characterization of key reaction intermediates.
- Casas, Fernando,Trincado, Monica,Rodriguez-Lugo, Rafael,Baneerje, Dipshikha,Grützmacher, Hansj?rg
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p. 5241 - 5251
(2019/11/16)
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- Generation of alkyl radicals from alkylsilyl peroxides and their applications to C-N or C-O bond formations
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This article describes a novel method for the generation of alkyl radicals from alkylsilyl peroxides and their applications to the Cu-catalyzed mono-N-alkylation of amides or arylamines, and to the O-alkylation of carboxylic acids. The use of alkylsilyl peroxides as alkyl radical sources includes the following synthetic advantages: i) various alkylsilyl peroxides can be readily synthesized from the corresponding alcohols and be stored at bench, and ii) a variety of alkyl radicals can be generated efficiently under mild conditions.
- Sakurai, Shunya,Kato, Terumasa,Sakamoto, Ryu,Maruoka, Keiji
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p. 172 - 179
(2018/12/11)
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- Hexacoppergermsesquioxanes as complexes with N-ligands: Synthesis, structure and catalytic properties
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A simple and versatile strategy of synthesis of cage metallagermaniumsesquioxanes is demonstrated for isolation of Cu6-based phenylgermsesquioxanes 1–6. Structure of newly synthesized coppergermsesquioxanes was established by single-crystal X-ray diffraction analysis. General principle of these cages’ topology implies the presence of two linear Cu3 fragments, coordinated by three pairs of ligands. These are: (i) cyclic germsesquioxanes [PhGeO1,5]5, products 1–6, (ii) 1,10-phenanthrolines, (1, 3–5) or 2,2’-bipyridines, (2, 6), (or and (iii) OX species (X = H, 1–2, CH3, 3, H and C2H5O, 4, HCO, 5, CH3CO, 6). Appearance of non-expected species (formiate for 5, acetate for 6), resulted from corresponding alcohols used as reaction media, points at easyness of oxidation processes in the conditions of such self-assembling reactions. Catalytic tests showed high activity of complexes 1 and 2 as precatalysts in homogeneous oxidations of alkanes (cyclohexane, methylcyclohexane, n-heptane, cis-1,2-dimethylcyclohexane with hydrogen peroxide in acetonitrile solution. Hydroxyl radicals take part in the reaction. The same complexes catalyze oxidation of alcohols (cyclohexanol, 2-heptanol, 1-phenylethanol) to corresponding ketones with tert-butyl hydroperoxide in almost 100% yield. With the addition of various alkyl ammonium salts, complex 2 could also furnish corresponding amides in high yield.
- Kulakova, Alena N.,Korlyukov, Alexander A.,Zubavichus, Yan V.,Khrustalev, Victor N.,Bantreil, Xavier,Shul'pina, Lidia S.,Levitsky, Mikhail M.,Ikonnikov, Nikolay S.,Shubina, Elena S.,Lamaty, Frédéric,Bilyachenko, Alexey N.,Shul'pin, Georgiy B.
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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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- Graphene Oxide: A Metal-Free Carbocatalyst for the Synthesis of Diverse Amides under Solvent-Free Conditions
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An environmentally friendly, inexpensive, carbocatalyst, graphene oxide (GO) promoted efficient, metal-free transamidation of various carboxamides with aliphatic, cyclic, and aromatic amines is demonstrated. The protocol is equally applicable to phthalimide, urea, and thioamide determining its adaptability. The oxygenated functionalities such as carbonyl (?C=O), epoxy (?O?), carboxyl (?COOH) and hydroxyl (?OH), present on graphene oxide surface impart acidic properties to the catalyst. The graphene oxide being heterogeneous in nature, work efficiently under solvent-free reaction conditions providing desired products in good to excellent yields. The one-pot synthesis of 2,3-Dihydro-5H-benzo[b]-1,4-thiazepin-4-one moiety by GO catalyzed Aza Michael addition followed by intramolecular transamidation is also described. A plausible reaction mechanistic pathway involving H-bonding is discussed. The graphene oxide can be recycled and reused up to five cycles without much loss in catalytic activity. (Figure presented.).
- Patel, Khushbu P.,Gayakwad, Eknath M.,Patil, Vilas V.,Shankarling, Ganapati S.
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supporting information
p. 2107 - 2116
(2019/03/26)
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