38407-00-0Relevant academic research and scientific papers
Base-Free Oxidative Coupling of Amines and Aliphatic Alcohols to Imines over Au–Pd/ZrO2 Catalyst under Mild Conditions
Cui, Wenjing,Jia, Meilin,Sagala,Wang, Jiang
, p. 958 - 967 (2021/06/06)
Abstract: The base-free synthesis of imines from amines and aliphatic alcohols over Au–Pd alloy catalysts under ambient conditions was developed. A series of Au–Pd/ZrO2 bimetallic catalysts with varying metal loadings and Au?:?Pd molar ratios were prepared and their catalytic performance was investigated. The 3.0?wt?% Au–Pd/ZrO2 alloy catalyst with Au?:?Pd molar ratio of 1?:?1 showed the best catalytic performance. Under air atmosphere, various imines were obtained from coupling of amines and aliphatic alcohols without any additives or promoters. The performance of alloy NPs was superior to that of monometallic catalysts due to the synergistic effect which was demonstrated by TEM, XPS, and UV–Vis characterization. Our work suggested this transformation differed slightly from those reactions between amine and benzyl alcohol and a possible mechanism was proposed. Moreover, the Au–Pd/ZrO2 catalyst could be easily separated and reused for at least five successive runs with high catalytic activity.
Manganese(III) Porphyrin-Catalyzed Dehydrogenation of Alcohols to form Imines, Tertiary Amines and Quinolines
Azizi, Kobra,Akrami, Sedigheh,Madsen, Robert
, p. 6439 - 6446 (2019/04/26)
Manganese(III) porphyrin chloride complexes have been developed for the first time as catalysts for the acceptorless dehydrogenative coupling of alcohols and amines. The reaction has been applied to the direct synthesis of imines, tertiary amines and quinolines where only hydrogen gas and/or water are formed as the by-product(s). The mechanism is believed to involve the formation of a manganese(III) alkoxide complex which degrades into the aldehyde and a manganese(III) hydride species. The latter reacts with the alcohol to form hydrogen gas and thereby regenerates the alkoxide complex.
MANGANESE BASED COMPLEXES AND USES THEREOF FOR HOMOGENEOUS CATALYSIS
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, (2017/09/05)
The present invention relates to novel manganese complexes and their use, inter alia, for homogeneous catalysis in (1) the preparation of imine by dehydrogenative coupling of an alcohol and amine; (2) C-C coupling in Michael addition reaction using nitriles as Michael donors; (3) dehydrogenative coupling of alcohols to give esters and hydrogen gas (4) hydrogenation of esters to form alcohols (including hydrogenation of cyclic esters (lactones) or cyclic di-esters (di- lactones), or polyesters); (5) hydrogenation of amides (including cyclic dipeptides, lactams, diamide, polypeptides and polyamides) to alcohols and amines (or diamine); (6) hydrogenation of organic carbonates (including polycarbonates) to alcohols or hydrogenation of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (7) dehydrogenation of secondary alcohols to ketones; (8) amidation of esters (i.e., synthesis of amides from esters and amines); (9) acylation of alcohols using esters; (10) coupling of alcohols with water and a base to form carboxylic acids; and (11) preparation of amino acids or their salts by coupling of amino alcohols with water and a base. (12) preparation of amides (including formamides, cyclic dipeptides, diamide, lactams, polypeptides and polyamides) by dehydrogenative coupling of alcohols and amines; (13) preparation of imides from diols.
Direct Synthesis of Amides by Dehydrogenative Coupling of Amines with either Alcohols or Esters: Manganese Pincer Complex as Catalyst
Kumar, Amit,Espinosa-Jalapa, Noel Angel,Leitus, Gregory,Diskin-Posner, Yael,Avram, Liat,Milstein, David
supporting information, p. 14992 - 14996 (2017/10/25)
The first example of base-metal-catalysed synthesis of amides from the coupling of primary amines with either alcohols or esters is reported. The reactions are catalysed by a new manganese pincer complex and generate hydrogen gas as the sole byproduct, thus making the overall process atom-economical and sustainable.
Green Oxidation of Amines to Imines Based on the Development of Novel Catalytic Systems Using Molecular Oxygen or Hydrogen Peroxide
Marui, Kuniaki,Nomoto, Akihiro,Akashi, Haruo,Ogawa, Akiya
, p. 31 - 42 (2015/12/26)
Amines are transformed into the corresponding imines by environmentally benign catalytic oxidation reactions. Gaseous oxygen or hydrogen peroxide is used as the oxidant, and water is the only byproduct. When a vanadium complex is used as the catalyst in an ionic liquid, the amine oxidation successfully proceeds with recycling of the catalyst. Amine oxidation with hydrogen peroxide as an oxidant in water is also attained by using copper(II) sulfate as catalyst. In addition, photoinduced oxidation of amines to imines is conducted by using oxygen as the oxidant in the presence of a zinc-chlorin complex as catalyst.
Synthesis of imines from amines in aliphatic alcohols on Pd/ZrO2 catalyst under ambient conditions
Cui, Wenjing,Zhaorigetu, Bao,Jia, Meilin,Ao, Wulan,Zhu, Huaiyong
, p. 2601 - 2604 (2014/01/06)
Synthesis of imines from amines and aliphatic alcohols (C 1-C6) in the presence of base on supported palladium nanoparticles has been achieved for the first time. The catalytic system shows high activity and selectivity in open air at room temperature.
Metal-Ligand cooperation on a diruthenium platform: Selective imine formation through acceptorless dehydrogenative coupling of alcohols with amines
Saha, Biswajit,Wahidurrahaman,Daw, Prosenjit,Sengupta, Gargi,Bera, Jitendra K.
, p. 6542 - 6551 (2014/06/09)
Metal-metal singly-bonded diruthenium complexes, bridged by naphthyridine-functionalized N-heterocyclic carbene (NHC) ligands featuring a hydroxy appendage on the naphthyridine unit, are obtained in a single-pot reaction of [Ru2(CH3COO)2(CO)4] with 1-benzyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (BIN-HBr) or 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (PIN-HBr), TlBF4, and substituted benzaldehyde containing an electron-withdrawing group. The modified NHC-naphthyridine-hydroxy ligand spans the diruthenium unit in which the NHC carbon and hydroxy oxygen occupy the axial sites. All the synthesized compounds catalyze acceptorless dehydrogenation of alcohols to the corresponding aldehydes in the presence of a catalytic amount of weak base 1,4-diazabicyclo[2.2.2]octane (DABCO). Further, acceptorless dehydrogenative coupling (ADHC) of the alcohol with amines affords the corresponding imine as the sole product. The substrate scope is examined with 1 (BIN, p-nitrobenzaldehyde). A similar complex [Ru2(CO) 4(CH3COO)(3-PhBIN)][Br], that is devoid of a hydroxy arm, is significantly less effective for the same reaction. Neutral complex 1 a, obtained by deprotonation of the hydroxy arm in 1, is found to be active for the ADHC of alcohols and amines under base-free conditions. A combination of control experiments, deuterium labeling, kinetic Hammett studies, and DFT calculations support metal-hydroxyl/hydroxide and metal-metal cooperation for alcohol activation and dehydrogenation. The bridging acetate plays a crucial role in allowing β-hydride elimination to occur. The ligand architecture on the diruthenium core causes rapid aldehyde extrusion from the metal coordination sphere, which is responsible for exclusive imine formation. Ligand lends a hand: Metal-hydroxy/hydroxide and metal-metal cooperation is demonstrated for acceptorless dehydrogenation of alcohols to give aldehydes. The ligand architecture ensures rapid extrusion of the aldehyde from the metal core, resulting in the formation of the corresponding imine as the sole coupled product with amines (see scheme; DABCO=1,4-diazabicyclo[2.2.2]octane).
Modular, efficient synthesis of asymmetrically substituted piperazine scaffolds as potent calcium channel blockers
Borzenko, Andrey,Pajouhesh, Hassan,Morrison, Jerrie-Lynn,Tringham, Elizabeth,Snutch, Terrance P.,Schafer, Laurel L.
supporting information, p. 3257 - 3261 (2013/06/27)
A novel approach to the synthesis of substituted piperazines and their investigation as N-type calcium channel blockers is presented. A common scaffold exhibiting high activity as N-type blockers is N-substituted piperazine. Using recently developed titanium and zirconium catalysts, we describe the efficient and modular synthesis of 2,5-asymmetrically disubstituted piperazines from simple amines and alkynes. The method requires only three isolation/purification protocols and no protection/deprotection steps for the diastereoselective synthesis of 2,5-dialkylated piperazines in moderate to high yield. Screening of the synthesized piperazines for N-type channel blocking activity and selectivity shows the highest activity for a compound with a benzhydryl group on the nitrogen (position 1) and an unprotected alcohol-functionalized side chain.
General, green, and scalable synthesis of imines from alcohols and amines by a mild and efficient copper-catalyzed aerobic oxidative reaction in open air at room temperature
Tian, Haiwen,Yu, Xiaochun,Li, Qiang,Wang, Jianxin,Xu, Qing
supporting information, p. 2671 - 2677,7 (2012/12/12)
A general, green, and scalable synthesis of the useful imines and a,b-unsaturated imines is successfully achieved by a low-loading and powerful, mild and efficient copper-catalyzed aerobic oxidative reaction of alcohols and amines in the open air at room temperature under base- and dehydrating reagent-free conditions. This practical reaction can use air as the economic and green oxidant, tolerates a wide range of substrates, can afford high yields of the target imines on a large scale, and produces water as the only by-product, and thus being the best imination method as yet using alcohols and amines directly.
Rapid synthesis of carbohydrate derivatives, including mimetics of C-linked disaccharides and C-linked aza disaccharides, using the hetero-Diels-Alder reaction
Burland, Peter A.,Coisson, David,Osborn, Helen M. I.
supporting information; experimental part, p. 7210 - 7218 (2011/02/22)
In this work we demonstrate the value of performing a hetero-Diels-Alder reaction (HDAR) between Danishefsky's diene and a range of aldehydes or imines, under microwave irradiation. By using a range of aldehydes and imines, including those derived from carbohydrates, access to functionalized 2,3-dihydro-4H- pyran-4-ones or 2,3-dihydro-4-pyridinones in good to excellent synthetic yields is possible. A particular strength of the methodology is its ability to access mimetics of C-linked disaccharides and C-linked aza disaccharides, targets of current therapeutic interest, in a rapid, convenient, and diastereoselective manner. The effect of high pressure on the HDARs involving carbohydrate-derived aldehydes and imines is also explored, with enhancement in yields occurring for the aldehyde substrates. Finally, HDARs using carbohydrate derived ketones, enones, and enals are described under a range of conditions. Optimum results were obtained under high-pressure conditions, with highly functionalized carbohydrate derivatives being afforded, in good yields, in this way.
