- Highly economical and direct amination of sp3carbon using low-cost nickel pincer catalyst
-
Developing more efficient routes to achieve C-N bond coupling is of great importance to industries ranging from products in pharmaceuticals and fertilizers to biomedical technologies and next-generation electroactive materials. Over the past decade, improvements in catalyst design have moved synthesis away from expensive metals to newer inexpensive C-N cross-coupling approaches via direct amine alkylation. For the first time, we report the use of an amide-based nickel pincer catalyst (1) for direct alkylation of amines via activation of sp3 C-H bonds. The reaction was accomplished using a 0.2 mol% catalyst and no additional activating agents other than the base. Upon optimization, it was determined that the ideal reaction conditions involved solvent dimethyl sulfoxide at 110 °C for 3 h. The catalyst demonstrated excellent reactivity in the formation of various imines, intramolecularly cyclized amines, and substituted amines with a turnover number (TON) as high as 183. Depending on the base used for the reaction and the starting amines, the catalyst demonstrated high selectivity towards the product formation. The exploration into the mechanism and kinetics of the reaction pathway suggested the C-H activation as the rate-limiting step, with the reaction second-order overall, holding first-order behavior towards the catalyst and toluene substrate.
- Brandt, Andrew,Rangumagar, Ambar B.,Szwedo, Peter,Wayland, Hunter A.,Parnell, Charlette M.,Munshi, Pradip,Ghosh, Anindya
-
p. 1862 - 1874
(2021/01/20)
-
- Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
-
We report the tetramethyl ammonium hydroxide catalyzed oxidative coupling of amines and alcohols for the synthesis of imines under metal-free conditions by utilizing oxygen from air as the terminal oxidant. Under the same conditions, with ortho-phenylene diamines and 2-aminobenzenethiols the corresponding benzimidazoles and benzothiazoles were obtained. Quinoxalines were obtained from ortho-phenylene diamines and 1-phenylethane-1,2-diol, the conditions were then extended to the synthesis of quinoline building blocks by reaction of 2-amino benzyl alcohols either with 1-phenylethan-1-ol or acetophenone derivatives. The formation of C?N, C?S and C?C bonds was achieved under metal-free conditions. A broad range of amines (aromatic, aliphatic, cyclic and heteroaromatic) as well as benzylic alcohols including heteroaryl alcohols reacted smoothly and provided the desired products. The mild reaction conditions, commercially available catalyst, metal-free, good functional-group tolerance, broad range of products (imines, benzimidazoles, benzothiazoles, quinoxalines and quinolines) and applicability at gram scale reactions are the advantages of the present strategy.
- Adimurthy, Subbarayappa,Badhani, Gaurav,Joshi, Abhisek
-
p. 6705 - 6716
(2021/12/31)
-
- One-Pot Construction of Diverse β-Lactam Scaffolds via the Green Oxidation of Amines and Its Application to the Diastereoselective Synthesis of β-Amino Acids
-
In this study, a simple one-pot construction of β-lactam scaffolds was successfully achieved via 4,6-dihydroxysalicylic acid-catalyzed organocatalytic oxidation of amines to imines using molecular oxygen. Although some imines are highly unstable and difficult to isolate by conventional methods, the organocatalytic oxidation of amines described herein, followed by their direct reaction with acyl chlorides in the presence of a base, afforded a series of new β-lactam derivatives with excellent cis selectivity, which could not be synthesized and isolated by previously reported methods. Thus, this one-pot protocol will be one of the powerful methods applicable to the synthesis of various potential drug candidates and functional molecules. Furthermore, the subsequent hydrolysis of these β-lactams successfully afforded the corresponding β-amino acids as almost single diastereomers in up to 99% yields.
- Yamamoto, Yuki,Kodama, Shintaro,Nishimura, Riku,Nomoto, Akihiro,Ueshima, Michio,Ogawa, Akiya
-
p. 11571 - 11582
(2021/08/20)
-
- Manganese-Catalyzed Selective Hydrogenative Cross-Coupling of Nitriles and Amines to Form Secondary Imines
-
Manganese complexes with tridentate PNN ligands have been synthesized as catalysts for hydrogenative cross-coupling reaction of nitriles and amines to form secondary imines. This reaction afforded a variety of unsymmetrical secondary imines in good yields with excellent selectivity. Investigation of catalyst intermediates indicated that an amido manganese complex may be the active catalyst species for this reaction. (Figure presented.).
- Li, Xiao-Gen,Zhou, Qi-Lin
-
supporting information
p. 3471 - 3475
(2021/04/29)
-
- Single Atomically Anchored Cobalt on Carbon Quantum Dots as Efficient Photocatalysts for Visible Light-Promoted Oxidation Reactions
-
Generation of efficient light-induced charge separation inside the photocatalyst is an essential factor for a high catalytic efficiency. The usual immobilization of metal or metal oxide particles on semiconductor photocatalysts offers an uncontrolled assembly of active sites during the reaction. The introduction of single metal atoms on photocatalysts can lead to extremely high atomic utilization and precise active sites. However, this approach is limited because of the lack of suitable photosensitizers for single atom immobilization. Here, we have designed photocatalytic carbon quantum dots with anchoring sites for single cobalt atoms in a defined Co-N4 structure via facile pyrolysis of vitamin B12. Carbon dots functioned as both light-harvesting antenna and support for the cobalt atom with high atom loadings up to 3.27 wt %. This new photocatalytic material demonstrated enhanced visible light absorption, efficient charge separation, and reduced electrochemical impedance, while single Co atoms acted as the active site with strong oxidative ability. As a result, the photocatalysts showed excellent visible light-promoted photocatalytic efficiency with oxygen evolution rates up to 168 μmol h-1 g-1 via water oxidation, imine formation with high conversion (~90%) and selectivity (>99%), and complete photodegradation of organic dyes.
- Wang, Qin,Li, Jin,Tu, Xianjun,Liu, Hongbo,Shu, Miao,Si, Rui,Ferguson, Calum T. J.,Zhang, Kai. A. I.,Li, Run
-
p. 734 - 743
(2020/02/04)
-
- Visible light photocatalytic aerobic oxidative synthesis of imines from alcohols and amines on dye-sensitized TiO2
-
A general visible light photocatalytic protocol for the synthesis of imines via a two-step one-pot route on alizarin red S (ARS)-sensitized TiO2 was uncovered. This efficient synthesis protocol involves one step of the highly selective formation of aldehydes from the oxidation of alcohols with O2 on ARS-sensitized TiO2 photocatalyst, and a subsequent step of condensation of newly formed aldehydes with various amines on TiO2 to afford imines in one pot. Anatase TiO2 provides a versatile platform for catalytic amounts of ARS (0.67 mol%) to facilitate the electron transfer from dye traversing its conduction band to O2 under green LED irradiation. Moreover, the Lewis acid sites of TiO2 can promote the formation of imines from aldehydes and amines in very high isolated yields. We took advantage of both the photocatalytic and catalytic properties of TiO2 to significantly expand the scope of imines. Our work suggests that the synthetic applications of TiO2 photocatalysis can be achievable under mild conditions by exploring the excellent functionalities of TiO2.
- Xu, Hui,Shi, Ji-Long,Hao, Huimin,Li, Xia,Lang, Xianjun
-
p. 128 - 135
(2019/01/04)
-
- Metal-free aerobic oxidative coupling of amines in dimethyl sulfoxide via a radical pathway
-
Metal-free oxidative coupling of amines is achieved simply by heating their dimethyl sulfoxide (DMSO) solution under oxygen as oxidant without any other catalysts or additives, accompanied by the formation of an equimolar amount of dimethyl sulfone (DMSO2). EPR experiments indicate that the reaction proceeds via a radical pathway. DMSO may play a triple role as solvent, radical initiator and co-reductant.
- Lin, Mu,Wang, Zikuan,Fang, Huayi,Liu, Lianghui,Yin, Haolin,Yan, Chun-Hua,Fu, Xuefeng
-
p. 10861 - 10864
(2016/02/05)
-
- Visible-Light-Driven Oxidative Coupling Reactions of Amines by Photoactive WS2 Nanosheets
-
Visible-light-driven photocatalysis has been emerging as an efficient and sustainable approach for chemical transformation in organic reactions, in which photostable and cost-effective photosensitizers are required to trigger and promote it. Monolayer WS
- Raza, Faizan,Park, Jung Hyun,Lee, Hye-Rim,Kim, Hye-In,Jeon, Su-Ji,Kim, Jong-Ho
-
p. 2754 - 2759
(2016/07/06)
-
- Oxygen-mediated formation of MoSx-doped hollow carbon dots for visible light-driven photocatalysis
-
It is of great interest to modulate the photocatalytic activity of nanomaterials by varying their composition at the atomic scale and their nanostructure. Herein, we demonstrate a bottom-up approach for the synthesis of MoSx-doped hollow carbon
- Park, Jung Hyun,Raza, Faizan,Jeon, Su-Ji,Yim, Dabin,Kim, Hye-In,Kang, Tae Woog,Kim, Jong-Ho
-
supporting information
p. 14796 - 14803
(2016/10/07)
-
- Recyclable hydrotalcite catalysts for alcohol imination via acceptorless dehydrogenation
-
Here we report that hydrotalcite-like materials (HTs) are active heterogeneous catalysts for alcohol imination, which proceeds through acceptorless alcohol dehydrogenation. The catalytic activity of a series of Mg-Al hydrotalcites doped with Fe3+, Zn2+, Ni2+, Cr3+ and Cu2+ is dependent on their composition, and Fe : Mg : Al HT yields up to 92% imine under mild conditions. Impregnation of Fe : Mg : Al HT with Pd0 resulted in an enhancement of activity for acceptorless dehydrogenation, but a decrease in the isolated yield of imine in a loading-dependent manner. This is attributed to the Pd loading-dependent retention of imine and aldehyde on the catalysts. The substrate scope for alcohol imination and recyclability of the catalysts is discussed.
- Bain, John,Cho, Philip,Voutchkova-Kostal, Adelina
-
p. 2271 - 2280
(2015/04/22)
-
- Catalytic coupling of nitriles with amines to selectively form imines under mild hydrogen pressure
-
Imines are selectively formed by coupling of nitriles and amines under mild hydrogen pressure. The reaction is catalyzed by a bipyridine-based PNN Ru(ii) pincer complex and proceeds under mild, neutral conditions at 4 bar of H 2.
- Srimani, Dipankar,Feller, Moran,Ben-David, Yehoshoa,Milstein, David
-
supporting information
p. 11853 - 11855
(2013/01/16)
-
- Metal-free aerobic oxidative coupling of amines to imines
-
Oxidative coupling of primary amines to imines is achieved with high to moderate yields by refluxing suspensions of amines and water under one atmosphere dioxygen without any additives. Tandem acid-free aza Diels-Alder reactions for synthesis of N-alkyl-4-pyridones are also accomplished. The Royal Society of Chemistry 2011.
- Liu, Lianghui,Zhang, Siyu,Fu, Xuefeng,Yan, Chun-Hua
-
supporting information; experimental part
p. 10148 - 10150
(2011/11/04)
-
- Base induced carbon-nitrogen (C=N) double bond migration in Schiff bases
-
Various Schiff bases have been prepared to study base induced carbon-nitrogen double bond migrations. Schiff bases derived from aliphatic aldehydes display highest selectivity. Hydrolysis of the resulting rearranged Schiff base provides an entry to make amines from aldehydes. The reaction has possible practical application.
- Gangadasu,Narender,China Raju,Jayathirtha Rao
-
p. 2598 - 2600
(2007/10/03)
-
- Preparation de nouveaux β-aminoacides a longue chaine et leur conversion en carboxybetaines bicatenaires F-alkylees
-
The synthesis of amphoteric F-alkylated bitailed surfactants derived from new β-aminoacid intermediates is described. N-alkyl N-benzyl amines or N-alkyl N-methyl amines are added to acrylic acid. The β-amino acids obtained are quaternized by 2-F-alkyl ethyl acetates or thioacetate bromides to produce the F-alkylated double-chain carboxybetaines.
- Enjalbert,Bassilana,Krier,Szoenyi,Cambon
-
p. 145 - 152
(2007/10/03)
-
- Sodium borohydride on wet clay: Solvent-free reductive amination of carbonyl compounds using microwaves
-
A solvent-flee reductive amination of carbonyl compounds by wet montmorillonite K 10 clay supported sodium borohydride is described; microwave irradiation facilitates the procedure.
- Varma, Rajender S.,Dahiya, Rajender
-
p. 6293 - 6298
(2007/10/03)
-