共查询到20条相似文献,搜索用时 15 毫秒
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Lang X Ma W Zhao Y Chen C Ji H Zhao J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(9):2624-2631
Imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. Selective oxidation of amines into their corresponding imines with dioxygen is one of the most-fundamental chemical transformations. Herein, we report the oxidation of a series of benzylic amines into their corresponding imines with atmospheric dioxygen as the oxidant on a surface of anatase TiO(2) under visible-light irradiation (λ>420 nm). The visible-light response of this system was caused by the formation of a surface complex through the adsorption of a benzylic amine onto the surface of TiO(2). From the analysis of products of specially designed benzylic amines, we demonstrated that a highly selective oxygenation reaction proceeds via an oxygen-transfer mechanism to afford the corresponding carbonyl compound, whose further condensation with an amine would generate the final imine product. We found that when primary benzylic amines (13 examples), were chosen as the substrates, moderate to excellent selectivities for the imine products were achieved (ca. 38-94%) in moderate to excellent conversion rates (ca. 44-95%). When secondary benzylic amines (15 examples) were chosen as the substrates, both the corresponding imines and aldehydes were detected as the main products with moderate to high conversion rates (ca. 18-100%) and lower selectivities for the imine products (ca. 14-69%). When tribenzylamine was chosen as the substrate, imine (27%), dibenzylamine (24%), and benzaldehyde products (39%) were obtained in a conversion of 50%. This report can be viewed as a prototypical system for the activation of C-H bonds adjacent to heteroatoms such as N, O, and S atoms, and oxofuctionalization with air or dioxygen as the terminal oxidant under visible-light irradiation using TiO(2) as the photocatalyst. 相似文献
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A new method for benzylic alkoxylation and hydroxylation of 3-methoxy-estra-1,3,5(10)-trienes (I) is described. 9α- and 9β-methoxy- and 9α- and 9β-hydroxy-3-methoxy-estra-1,3,5(10)-trienes (II and III) were prepared by electrochemical oxidation in a methanolic or aqueous solvent supporting electrolyte (SSE). 相似文献
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Pd-Catalyzed aerobic oxidation of different amines was systematically examined for the first time. A PdCl2/PPh3 system was successfully developed to catalyze the aerobic oxidation of several types of amines including Ar-CH2NHPh, Ar-CH2NHOMe, and Ar-CH2NHMs with high yields. Theoretical studies showed a remarkable difference in the energy barriers of β-hydride elimination between an alcohol and various amines. 相似文献
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Selective aerobic oxidation of activated alcohols into acids or aldehydes in ionic liquids 总被引:1,自引:0,他引:1
Selective aerobic oxidation of activated primary alcohols into acids or aldehydes has been developed in ionic liquids. Under optimal conditions, various alcohols could be selectively converted into their corresponding acids or aldehydes in good to excellent yields. The newly developed catalytic systems could also be recycled and reused for three runs without any significant loss of catalytic activity. 相似文献
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Taniguchi T Zaimoku H Ishibashi H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(15):4307-4312
A mild and practical oxyarylation of alkenes by oxidative radical addition has been developed by using aerobic oxidation of hydrazine compounds. The use of a catalytic amount of potassium ferrocyanide trihydrate (K4[Fe(CN)6]?3 H2O) and water accelerated this radical reaction to give peroxides or alcohols from simple alkenes in good yields. The environmentally friendly and economical radical reactions were achieved at room temperature in the presence of iron catalyst, oxygen gas, and water. A method involving aniline as a radical precursor is also described. 相似文献
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Jianxin Zhai Baowen Zhou Haihong Wu Shuaiqiang Jia Mengen Chu Shitao Han Wei Xia Mingyuan He Buxing Han 《Chemical science》2022,13(16):4616
Design of active catalysts for chemical utilization of methane under mild conditions is of great importance, but remains a challenging task. Here, we prepared a Ag/AgCl with SiO2 coating (Ag/AgCl@SiO2) photocatalyst for methane oxidation to carbon monoxide. High carbon monoxide production (2.3 μmol h−1) and high selectivity (73%) were achieved. SiO2 plays a key role in the superior performance by increasing the lifetime of the photogenerated charge carriers. Based on a set of semi in situ infrared spectroscopy, electron paramagnetic resonance, and electronic property characterization studies, it is revealed that CH4 is effectively and selectively oxidized to CO by the in situ formation of singlet 1O2via the key intermediate of COOH*. Further study showed that the Ag/AgCl@SiO2 catalyst could also drive valuable conversion using real sunlight under ambient conditions. As far we know, this is the first work on the application of SiO2 modified Ag/AgCl in the methane oxidation reaction.The Ag/AgCl@SiO2 catalyst exhibits excellent photocatalytic activity in selective aerobic oxidation of methane to carbon monoxide with high selectivity, and extended real light simulation feasibility shows potential in practical application. 相似文献
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The strained double bond of cyclopropenylcarbinols undergoes a facile oxidation reaction to lead to unsaturated carbonyl derivatives. The distribution of the formed products depends on the relative stability of carbon-centered radical species, and the Sharpless kinetic resolution leads to enantiomerically pure Baylis-Hillman enal adducts. 相似文献
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Selective oxidation of alcohols to the corresponding carbonyl compounds is one of the most fundamental reactions in organic synthesis. Traditional methods for this transformation generally rely on stoichiometric amount of oxidants represented by Cr(VI) or DMSO reagents, though their synthetic utility is encumbered by unpleasant waste materials. From ecological and atom-economic viewpoints, catalytic aerobic oxidation is much more advantageous because molecular oxygen is ubiquitous and the byproduct is basically non-toxic water or hydrogen peroxide. On the other hand, phenol derivatives undergo oxidative coupling, forming C-C or C-O bond, through radical intermediates coupled with an electron-transfer process. Molecular oxygen is also well known to serve as electron acceptor in this reaction. Thus, a variety of transition metal complexes have so far been examined for aerobic oxidations of alcohols and phenols, and high catalytic activities have been achieved in some cases. However, stereo- and chemo-selective aerobic oxidations are still limited in number and are of current interest. Presented in this paper is our recent studies on catalytic aerobic oxidations with photoactivated nitrosyl ruthenium-salen complexes, including asymmetric oxidation of secondary alcohols to ketones (kinetic resolution), enantioselective oxidative coupling of 2-naphthols to binaphthols and oxygen-radical bicyclization of 2,2'-dihydroxystilbene, chemoselective oxidation of primary alcohols to aldehydes and diols to lactols, and asymmetric desymmetrization of meso-diols to lactols. 相似文献
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Aerobic oxidation of a number of diaryl and arylalkyl carbinols to ketones was promoted by Na in THF at room temperature with up to 99% yield. This new oxidation method is also selective with good efficiency for the oxidation of benzylic secondary alcohols but not for a primary alcohol or nonbenzylic secondary alcohols. Under nitrogen, a catalytic amount of Ni or transition metal halides such as CoCl3, FeCl3, and NiCl3 in combination with Na was also found to conduct a dehydrogenation of a secondary alcohol to the corresponding ketone in high yield at room temperature. 相似文献
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Wang Chang-Cheng Zhang Guo-Xiang Zuo Zhi-Wei Zeng Rong Zhai Dan-Dan Liu Feng Shi Zhang-Jie 《中国科学:化学(英文版)》2021,64(9):1487-1492
Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry. Presently, the industrial manufacture of benzoic acids and benzene polycarboxylic acids(BPCAs) is mainly based on the deep oxidation of polyalkyl benzene, which is somewhat suffering from environmental and economical disadvantage due to the formation of ozone-depleting Me Br and corrosion hazards of production equipment. In this report, photo-induced deep aerobic oxidation of(poly)alkyl benzene to benzene(poly)carboxylic acids was developed. CeCl_3 was proved to be an efficient HAT(hydrogen atom transfer) catalyst in the presence of alcohol as both hydrogen and electron shuttle. Dioxygen(O_2) was found as a sole terminal oxidant. In most cases, pure products were easily isolated by simple filtration, implying large-scale implementation advantages.The reaction provides an ideal protocol to produce valuable fine chemicals from naturally abundant petroleum feedstocks. 相似文献
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A variety of tertiary, secondary and primary organonitrogen compounds have been efficiently and selectivity oxidized to their corresponding N-oxides, nitrones, and nitro compounds with molecular oxygen using methyltrioxorhenium as catalyst. 相似文献
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Maeda Y Kakiuchi N Matsumura S Nishimura T Kawamura T Uemura S 《The Journal of organic chemistry》2002,67(19):6718-6724
A catalytic system consisting of vanadium oxyacetylacetonate [VO(acac)(2)] and 3 A molecular sieves (MS3A) in acetonitrile works effectively for the aerobic oxidation of propargylic alcohols [R(1)CH(OH)Ctbd1;CR(2)] to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Although the reactivity of alpha-acetylenic alkanols (R(1) = alkyl) is lower compared to that of the alcohols of R(1) = aryl, alkenyl, and alkynyl, the use of VO(hfac)(2) as a catalyst and the addition of hexafluoroacetylacetone improve the product yield in these cases. A catalytic cycle involving a vanadium(V) alcoholate species and beta-hydrogen elimination from it has been proposed for this oxidation. 相似文献
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Pandi MuthupandiGovindasamy Sekar 《Tetrahedron letters》2011,52(6):692-695
Zn(II)-DABCO complex is used as an efficient catalyst for the aerobic oxidation of benzoins to benzils in the presence of molecular oxygen. Usage of chiral zinc complex as catalyst resulted in enantioselective oxidative kinetic resolution of racemic benzoin to yield enantiomerically enriched benzoins. 相似文献
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Benzoins are simply oxidized to benzils in excellent yields with a catalytic amount of triarylstibanes under an aerobic condition. This catalytic oxidation is heteroatom-specific in the antimony compound and no reaction take place with other group 15 reagents such as triphenylphosphane, -arsane and -bismuthane. The reaction should involve an oxidation-reduction cycle between stibane Sb(III) and stiborane Sb(V) under air. 相似文献
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S. Yu. Men’shikov Yu. V. Mishina Yu. V. Mikushina A. A. Ostroushko 《Russian Journal of Applied Chemistry》2008,81(1):52-54
The catalytic activity exhibited in turpentine oxidation at elevated pressure by cobalt coordination compounds, some transition metal compounds, in particular, polyoxometallate with spherical nanoclusters (Mo132), vanadium oxide bronze, and cobalt complexes immobilized on AN-241 anion exchanger was studied. 相似文献
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Shibuya M Osada Y Sasano Y Tomizawa M Iwabuchi Y 《Journal of the American Chemical Society》2011,133(17):6497-6500
5-Fluoro-2-azaadamantane N-oxyl (5-F-AZADO) realizes a simple, organocatalytic aerobic alcohol oxidation system that has a wide scope under mild conditions at ambient pressure and temperature and is weakly acidic and halogen- and transition-metal-free. The oxoammonium nitrate (5-F-AZADO(+)NO(3)(-)) works as a bifunctional catalyst of 5-F-AZADO and NO(x) that enables the catalytic aerobic oxidation of alcohols by itself (a metal-salt-free system). 相似文献