- One-Pot Bioelectrocatalytic Conversion of Chemically Inert Hydrocarbons to Imines
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Petroleum hydrocarbons are our major energy source and an important feedstock for the chemical industry. With the exception of combustion, the deep conversion of chemically inert hydrocarbons to more valuable chemicals is of considerable interest. However, two challenges hinder this conversion. One is the regioselective activation of inert carbon-hydrogen (C-H) bonds. The other is designing a pathway to realize this complicated conversion. In response to the two challenges, a multistep bioelectrocatalytic system was developed to realize the one-pot deep conversion from heptane to N-heptylhepan-1-imine under mild conditions. First, in this enzymatic cascade, a bioelectrocatalytic C-H bond oxyfunctionalization step based on alkane hydroxylase (alkB) was applied to regioselectively convert heptane to 1-heptanol. By integrating subsequent alcohol oxidation and bioelectrocatalytic reductive amination steps based on an engineered choline oxidase (AcCO6) and a reductive aminase (NfRedAm), the generated 1-heptanol was successfully converted to N-heptylhepan-1-imine. The electrochemical architecture provided sufficient electrons to drive the bioelectrocatalytic C-H bond oxyfunctionalization and reductive amination steps with neutral red (NR) as electron mediator. The highest concentration of N-heptylhepan-1-imine achieved was 0.67 mM with a Faradaic efficiency of 45% for C-H bond oxyfunctionalization and 70% for reductive amination. Hexane, octane, and ethylbenzene were also successfully converted to the corresponding imines. Via regioselective C-H bond oxyfunctionalization, intermediate oxidation, and reductive amination, the bioelectrocatalytic hydrocarbon deep conversion system successfully realized the challenging conversion from inert hydrocarbons to imines that would have been impossible by using organic synthesis methods and provided a new methodology for the comprehensive conversion and utilization of inert hydrocarbons.
- Chen, Hui,Tang, Tianhua,Malapit, Christian A.,Lee, Yoo Seok,Prater, Matthew B.,Weliwatte, N. Samali,Minteer, Shelley D.
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p. 4047 - 4056
(2022/02/10)
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- Oxidative coupling of primary amines to imines catalyzed by CoCl2·6H2O
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A high-performance, readily available and eco-friendly cobalt catalyst has been suggested for the first time for the additive-free oxidative coupling of primary amines to imines. Different substituted benzylamine and heteroaryl methanamine compounds could be transformed into their corresponding imines in good to excellent yields over this catalyst. Meanwhile, it has been demonstrated that this catalyst can also afford the oxidative coupling of various benzylamines with o-phenylenediamine to produce benzimidazole derivatives in medium to good yields.
- Huang, Longjiang,Li, Xiufen,Lian, Chengxi,Wang, Hui,Zhang, Chaoying,Zhao, Yingchun
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- Rhodium-Catalyzed Anti-Markovnikov Hydroamination of Aliphatic and Aromatic Terminal Alkynes with Aliphatic Primary Amines
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Anti-Markovnikov hydroamination of both aliphatic and aromatic terminal alkynes with primary amines was achieved using an 8-quinolinolato rhodium catalyst to form aldimines and enamines in high yields. This catalytic system realized high functional group tolerance including hydroxy, bromo, cyano, and thioester groups.
- Kakiuchi, Fumitoshi,Kochi, Takuya,Morimoto, Yoshihiko
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p. 13143 - 13152
(2021/09/28)
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- Cooperative Syngas Production and C?N Bond Formation in One Photoredox Cycle
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Solar-driven syngas production by CO2 reduction provides a sustainable strategy to produce renewable feedstocks. However, this promising reaction often suffers from tough CO2 activation, sluggish oxidative half-reaction kinetics and undesired by-products. Herein, we report a function-oriented strategy of deliberately constructing black phosphorus quantum dots-ZnIn2S4 (BP/ZIS) heterostructures for solar-driven CO2 reduction to syngas, paired with selectively oxidative C?N bond formation, in one redox cycle. The optimal BP/ZIS heterostructure features the enhanced charge-carrier separation and enriched active sites for cooperatively photocatalytic syngas production with a tunable ratio of CO/H2 and efficient oxidation of amines to imines with high conversion and selectivity. This prominent catalytic performance arises from the efficient electronic coupling between black phosphorus quantum dots and ZnIn2S4, as well as the optimized adsorption strength for key reaction intermediates, as supported by both experimental and theoretical investigations. We also demonstrate a synergistic interplay between CO2 reduction and amine dehydrogenation oxidation, rather than simply collecting these two single half-reactions in this dual-functional photoredox system.
- Han, Chuang,Li, Yue-Hua,Li, Jing-Yu,Qi, Ming-Yu,Tang, Zi-Rong,Xu, Yi-Jun
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supporting information
p. 7962 - 7970
(2021/03/01)
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- Uniform Cu/chitosan beads as a green and reusable catalyst for facile synthesis of iminesviaoxidative coupling reaction
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A nonprecious metal and biopolymer-based catalyst, Cu/chitosan beads, has been successfully prepared by using a software-controlled flow system. Uniform, spherical Cu/chitosan beads can be obtained with diameters in millimeter-scale and narrow size distribution (0.78 ± 0.04 mm). The size and morphology of the Cu/chitosan beads are reproducible due to high precision of the flow rate. In addition, the application of the Cu/chitosan beads as a green and reusable catalyst has been demonstrated using a convenient and efficient protocol for the direct synthesis of iminesviathe oxidative self- and cross-coupling of amines (24 examples) with moderate to excellent yields. Importantly, the beads are stable and could be reused more than ten times without loss of the catalytic performance. Furthermore, because of the bead morphology, the Cu/chitosan catalyst has greatly simplified recycling and workup procedures.
- Bunchuay, Thanthapatra,Chantiwas, Rattikan,Chutimasakul, Threeraphat,Intanin, Apichai,Na Nakhonpanom, Pakamon,Tantirungrotechai, Jonggol,Tirdtrakool, Warinda
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p. 21009 - 21018
(2020/06/22)
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- Nitrogen-Doped Carbon-Supported Nickel Nanoparticles: A Robust Catalyst to Bridge the Hydrogenation of Nitriles and the Reductive Amination of Carbonyl Compounds for the Synthesis of Primary Amines
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An efficient method was developed for the synthesis of primary amines either from the hydrogenation of nitriles or reductive amination of carbonyl compounds. The reactions were catalyzed by nitrogen-doped mesoporous carbon (MC)-supported nickel nanoparticles (abbreviated as MC/Ni). The MC/Ni catalyst demonstrated high catalytic activity for the hydrogenation of nitriles into primary amines in high yields (81.9–99 %) under mild reaction conditions (80 °C and 2.5 bar H2). The MC/Ni catalyst also promoted the reductive amination of carbonyl compounds for the synthesis of primary amines at 80 °C and 1 bar H2. The hydrogenation of nitriles and the reductive amination proceeded through the same intermediates for the generation of the primary amines. To the best of our knowledge, no other heterogeneous non-noble metal catalysts have been reported for the synthesis of primary amines under mild conditions, both from the hydrogenation of nitriles and reductive amination.
- Zhang, Yangmin,Yang, Hanmin,Chi, Quan,Zhang, Zehui
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p. 1246 - 1255
(2019/03/07)
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- Table salt as a catalyst for the oxidation of aromatic alcohols and amines to acids and imines in aqueous medium: Effectively carrying out oxidation reactions in sea water
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A simple, efficient, sustainable and economical method for the oxidation of alcohols and amines has been developed based on chloride, a sea abundant anionic catalyst for the practical synthesis of a wide range of carboxylic acids, ketones and imines. Oxidation of aromatic alcohols was carried out using NaCl (20 mol%) as the catalyst, NaOH (50 mol%) and aq. TBHP (4 equiv.) as the oxidant in 55-92% isolated yields. Oxidation of aromatic amines to imines was achieved by using only 20 mol% of NaCl and aq. TBHP (4 equiv.) in 32-93% isolated yields. The chlorine species formed during the reaction as the active oxidation catalyst has been identified as ClO2- for alcohols and ClO-/ClO2- for amines by control experiments. This method is mostly free from chromatographic purification, which makes it suitable for large-scale synthesis. We have scaled up to 30 gram scale the synthesis of carboxylic acids and imines in good yields and have also carried out efficiently this new method using filtered sea water as the solvent and catalyst.
- Hazra, Susanta,Kushawaha, Ajay Kishor,Yadav, Deepak,Dolui, Pritam,Deb, Mayukh,Elias, Anil J.
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supporting information
p. 1929 - 1934
(2019/04/29)
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- A simple and general route to prepare functional mesoporous double-metal oxy(hydroxide)
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The design and synthesis of functional mesoporous metal oxide materials while retaining their original morphology has still remained challenging over the past few decades. Herein, a simple and general route without using any surfactant has been developed to fabricate one-, two- and three-dimensional (1D, 2D and 3D) mesoporous double-metal oxy(hydroxides) from their corresponding metal hydroxides through the topotactic transformation and selective etching strategy. Taking ZnSn(OH)6 3D nanocubes as an example, after solvothermal treatment, ZnSn(OH)6 was successfully converted into worm-like mesoporous Zn0.7SnO2.4(OH)0.6 3D nanocubes with a large specific surface area of 369 m2 g?1 and pore size of 3.41 nm, and the shape of the nanocubes was maintained. This topotactic transformation is achieved by one-step solvothermal treatment in ethanol through solvothermal partial dehydration of a metal hydroxide precursor. Besides, ethanol serves as a weak reducing agent, and abundant oxygen vacancies are generated for mesoporous Zn0.7SnO2.4(OH)0.6, which is responsible for the enhancement of catalytic performance. The as-prepared mesoporous nanocatalysts show excellent activity and stability towards highly selective visible-light photocatalytic aerobic oxidation of amines to imines with a conversion of over 90% and selectivity over 94%. Notably, this method is also successfully applied to other double-metal hydroxides such as CuSn(OH)6 1D nanorods and CoAl-layered double hydroxide (LDH) 2D nanosheets, and mesoporous CuSn0.5O1.7(OH)0.48 and Co2Al0.5O2.5(OH)0.48 materials with large surface areas are obtained, while retaining their original morphology. Therefore, this promising strategy reported here is believed to be a universal approach to fabricate various other mesoporous metal oxy(hydroxides) with a large specific surface area and abundant oxygen vacancies, which could find a wide range of potential applications in photocatalysis, electrocatalysis, energy conversion and storage and so on.
- Jiang, Yi-Fan,Jiang, Nan,Liang, Kuang,Yuan, Cheng-Zong,Fang, Xiao-Xiang,Xu, An-Wu
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supporting information
p. 7932 - 7938
(2019/03/29)
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- Cultivation of a Cu/HMPC catalyst from a hyperaccumulating mustard plant for highly efficient and selective coupling reactions under mild conditions
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Cu-containing activated carbon (eco-catalyst, Cu/HMPC, where 'C' defines 'carbon') was derived from a metal-hyperaccumulating mustard plant (HMP) by a simple chemical activation method. Transmission electron microscopy/selected area diffraction (HRTEM/SAED) results revealed that the Cu/HMPC has mainly three types of morphology [sheet-like morphology (2D), hollow-spheres (3D) and needle-like structures (1D)] which are interconnected. HRTEM-SAED, Raman and X-ray photoelectron spectroscopy (XPS) results confirmed the existence of Cu oxide species in Cu/HMPC. Content of Cu in Cu/HMPC was determined to be 1.03 wt%. The quality of graphitization in Cu/HMPC was discussed by using Raman and XRD results. The BET surface area of Cu/HMPC was determined to be 620.8 m2 g-1. The Cu/HMPC actively transformed a wide range of amines to imines under very mild reaction conditions. The catalyst Cu/HMPC gave products in excellent yields (98-61%) with very high TON/TOF values (1512/339-833/35 h-1). To the best of our knowledge, this is the most efficient Cu-based heterogeneous eco-catalyst for the synthesis of imines among those reported to date. The Cu can be recovered from used Cu/HMPC by a simple HCl treatment. Versatility, heterogeneity and reusability of Cu/HMPC were tested. A possible mechanism has been proposed.
- Gopiraman, Mayakrishnan,Wei, Kai,Zhang, Ke-Qin,Chung, Ill-Min,Kim, Ick Soo
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p. 4531 - 4547
(2018/02/09)
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- Dual modification of TiNb2O7 with nitrogen dopants and oxygen vacancies for selective aerobic oxidation of benzylamine to imine under green light
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TiNb2O7 powder was prepared by a simple hydrothermal method and subsequent heat treatment. Vo-N-TiNb2O7 was generated by NH3 and ethanol dual treatments. The NH3 treatment produced a new N 2p orbital band above the O 2p valence band and oxygen vacancy (Vo) levels were formed by the ethanol treatment. The photocatalytic performance of modified Vo-N-TiNb2O7 towards selective aerobic oxidation reactions under green light (475-600 nm, peaked at 525 nm) was measured. It exhibits a high conversion of benzylamine (above 90%) at 80 °C over 24 h with selectivity for N-benzylidenebenzylamine greater than 95% under green light, which is much better than the unmodified and mono-modified TiNb2O7. It is suggested that the dual modification alter the electronic band structure of TiNb2O7 and result in a narrower band gap which should be responsible for the enhanced photocatalytic activity.
- Yu, Zhuobin,Waclawik, Eric R.,Wang, Zhijian,Gu, Xianmo,Yuan, Yong,Zheng, Zhanfeng
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supporting information
p. 4607 - 4615
(2017/03/11)
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- Facile Synthesis and Isolation of Secondary Amines via a Sequential Titanium(IV)-Catalyzed Hydroamination and Palladium-Catalyzed Hydrogenation
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An atom economical and catalytic route for the synthesis of aryl- and alkyl-substituted secondary amines has been developed. Using a bis(amidate)bis(amido)titanium(IV) precatalyst, the hydroamination of terminal alkynes with a range of amines results in the selective formation of the anti-Markovnikov product. The crude enamine/imine mixtures are effectively hydrogenated using palladium on carbon (Pd/C) and H2 to afford the corresponding secondary amine in excellent yields. Simple work-up procedures allow for the isolation of pure compounds while avoiding purification via column chromatography.
- Lui, Erica K. J.,Schafer, Laurel L.
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supporting information
p. 713 - 718
(2016/03/09)
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- Visible light induced green transformation of primary amines to imines using a silicate supported anatase photocatalyst
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Catalytic oxidation of amine to imine is of intense present interest since imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. However, considerable efforts have been made to develop efficient methods for the oxidation of secondary amines to imines, while little attention has until recently been given to the oxidation of primary amines, presumably owing to the high reactivity of generated imines of primary amines that are easily dehydrogenated to nitriles. Herein, we report the oxidative coupling of a series of primary benzylic amines into corresponding imines with dioxygen as the benign oxidant over composite catalysts of TiO2 (anatase)-silicate under visible light irradiation of λ > 460 nm. Visible light response of this system is believed to be as a result of high population of defects and contacts between silicate and anatase crystals in the composite and the strong interaction between benzylic amine and the catalyst. It is found that tuning the intensity and wavelength of the light irradiation and the reaction temperature can remarkably enhance the reaction activity. Water can also act as a green medium for the reaction with an excellent selectivity. This report contributes to the use of readily synthesized, environmentally benign, TiO2 based composite photocatalyst and solar energy to realize the transformation of primary amines to imine compounds.
- Zavahir, Sifani,Zhu, Huaiyong
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p. 1941 - 1954
(2015/02/05)
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- Tert-Butyl hydroperoxide (TBHP)-mediated oxidative self-coupling of amines to imines over a α-MnO2 catalyst
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We here demonstrate a simple, efficient and eco-friendly protocol for the direct synthesis of imines from amines via a facile α-MnO2 catalyzed-procedure at rt. Up to 13 benzylic, heterocyclic, and normal aliphatic imines were synthesized with 95-99% selectivity at 82-99% conversion. the Partner Organisations 2014.
- Zhang, Zhe,Wang, Feng,Wang, Min,Xu, Shutao,Chen, Haijun,Zhang, Chaofeng,Xu, Jie
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supporting information
p. 2523 - 2527
(2014/05/06)
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- Cu(I)/TEMPO-catalyzed aerobic oxidative synthesis of imines directly from primary and secondary amines under ambient and neat conditions
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By catalyst and condition screening, a simple Cu(I)/TEMPO-catalyst system was found to be an active and highly effective catalyst for the aerobic oxidation of amines to imines in open air at room temperature under neat conditions. This new method provided a mild, efficient, and practical alternative for the synthesis of the useful imines directly from primary and secondary amines.
- Huang, Bo,Tian, Haiwen,Lin, Shoushuai,Xie, Meihua,Yu, Xiaochun,Xu, Qing
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supporting information
p. 2861 - 2864
(2013/06/05)
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- Acceptorless photocatalytic dehydrogenation for alcohol decarbonylation and imine synthesis
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It has come to light: Renewed interest in conversions of highly oxygenated materials has motivated studies of the organometallic-catalyzed photocatalytic dehydrogenative decarbonylation of primary alcohols into alkanes, CO, and H2 (see scheme). Methanol, ethanol, benzyl alcohol, and cyclohexanemethanol are readily decarbonylated. The photocatalysts are also active for amine dehydrogenation to give N-alkyl aldimines and H2.
- Ho, Hung-An,Manna, Kuntal,Sadow, Aaron D.
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supporting information; experimental part
p. 8607 - 8610
(2012/09/11)
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- Selective cross-coupling of amines by alumina-supported palladium nanocluster catalysts
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Al2O3-supported Pd nanoclusters with an average particle size of 1.8 nm act as a reusable catalyst for the selective cross-coupling of amines. The reaction is a structure-sensitive reaction, demanding coordinatively unsaturated Pd atoms on a metallic nanocluster. The support also affects the activity, an amphoteric oxide (Al2O 3) is most effective. The Royal Society of Chemistry.
- Shimizu, Ken-Ichi,Shimura, Katsuya,Ohshima, Keiichiro,Tamura, Masazumi,Satsuma, Atsushi
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supporting information; experimental part
p. 3096 - 3100
(2011/12/04)
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- PROCESS FOR PREPARING AMINES FROM ALCOHOLS AND AMMONIA
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The present invention provides novel ruthenium based catalysts, and a process for preparing amines, by reacting a primary alcohol and ammonia in the presence of such catalysts, to generate the amine and water. According to the process of the invention, primary alcohols react directly with ammonia to produce primary amines and water in high yields and high turnover numbers. This reaction is catalyzed by novel ruthenium complexes, which are preferably composed of quinolinyl or acridinyl based pincer ligands.
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Page/Page column 26; 32
(2010/04/03)
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- One-pot AgOAc-mediated synthesis of polysubstituted pyrroles from primary amines and aldehydes: Application to the total synthesis of purpurone
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A simple and efficient method for the synthesis of 1,3,4-trisubstituted or 3,4-disubstituted pyrroles has been developed. The reaction represents the first time that pyrroles are synthesized directly from readily available aldehydes and amines (anilines)
- Li, Qingjiang,Fan, Aili,Lu, Zhiyao,Cui, Yuxin,Lin, Wenhan,Jia, Yanxing
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supporting information; experimental part
p. 4066 - 4069
(2010/11/16)
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- Selective synthesis of primary amines directly from alcohols and ammonia
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(Chemical Equation Presented) Air stable and waterproof: Selective and efficient synthesis of primary amines directly from alcohols and ammonia is achieved under mild conditions (see scheme). The reaction is homogenously catalyzed by a novel air-stable ruthenium pincer complex and can proceed in toluene or even in the absence of solvent or "on water".
- Gunanathan, Chidambaram,Milstein, David
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supporting information; experimental part
p. 8661 - 8664
(2009/05/15)
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- A study of the complexation of bis(m-phenylene) crown ethers and secondary ammonium ions
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Two macrocycles, bis(m-phenylene)-26-crown-8 (1) and bis(m-phenylene)-32-crown-10 (2), were combined with several linear components, dibenzyl- (3·PF6), di-n-butyl- (4·PFe), and diphenethyl(5·PF6) ammonium hexafluorophosphate salts. The smaller macrocycle 1 was shown not to complex effectively with any of the ammonium salts in solution by 1H NMR, but 1:1 complexes were shown to exist in the "gas phase" as [1:3], [1:4], and [1:5] by high-resolution fast atom bombardment mass spectrometry (HRFABMS) and electrospray ionization mass spectrometry (ESIMS). The X-ray crystal structure of macrocycle 1 is reported. The larger macrocycle 2 did form 1:2 complexes with the ammonium salts in solution, which were observed as well in the solid and gas phases. X-ray crystal structures of the pseudorotaxanes [2:(3)2]·2PF6 and [2:(5)2]·2PF6 were determined and are discussed. The pseudorotaxanes are stabilized by hydrogen bonding between the ammonium hydrogens of the linear salt unit and the oxygens of the crown ether macrocycle. Secondary stabilization also occurs by edge-to-face π stacking.
- Bryant, William S.,Guzei, Ilia A.,Rheingold, Arnold L.,Merola, Joseph S.,Gibson, Harry W.
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p. 7634 - 7639
(2007/10/03)
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