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All total 623 Articles be foundFlash vacuum pyrolysis of 3-oxo-2-arylhydrazonopropanals and related derivatives
Ibrahim, Yehia A,Kaul, Kamini,Al-Awadi, Nouria A
, p. 10171 - 10176 (2001)
Flash vacuum pyrolysis (FVP) of 3-oxo-2-arylhydrazonopropanals at 500°C and 0.02 Torr yielded the corresponding derivatives of anilines, N-formylanilines, N-benzoylanilines and benzoylnitriles. Similar FVP of phenylhydrazonomalononitrile, phenylhydrazonoa
Palladium-catalysed N,N'-disubstituted urea synthesis by oxidative carbonylation of amines under CO and O2 at atmospheric pressure
Giannoccaro, Potenzo
, p. 271 - 278 (1987)
N,N'-disubstituted ureas have been obtained in good yields by reaction of aromatic and aliphatic primary amines in alcohol solution with CO and O2 under mild conditions (70-90 deg C, 1 atm) and in the presence of catalytic amounts of PdCl2 or a palladium(II) complex.Under more drastic temperature and pressure conditions carbamate esters were obtained instead.In the aniline carbonylation, the catalysis involves the following reactions: .Reaction (1) occurs at room temperature but more drastic conditions (70-90 deg C) are necessary for reaction (2).The influence of onium salts, such as PhNH3+X- (X=Cl, I) or CuCl2, on the catalytic activity has also been studied and the best results obtained with CuCl2.A side reaction involving carbon monoxide oxidation was almost suppressed when the reactions were carried out in alcohol, but enhanced when THF or dimethoxypropane was used as solvent.
Oxygen activation by iron(III)-porphyrin/NaBH4/Me4N·OH system as cytochrome P-450 model. Oxygenation of olefin, N-dealkylation of tertiary amine, oxidation of sulfide, and oxidative cleavage of ether bond
Mori,Santa,Higuchi,Mashino,Hirobe
, p. 292 - 295 (1993)
Oxygenation of olefin, N-dealkylation of tertiary amine, oxidation of sulfide, and oxidative cleavage of ether bond were conducted with tetraphenylporphyrinatoiron(III) (Fe3+TPPCl), NaBH4, Me4N·OH, and molecular dioxygen in benzene-methanol solution. Fe3+TPPCl, NaBH4, and molecular dioxygen were essential for these reactions and the yields were decreased when Me4N·OH was absent. Olefins were converted to alcohols, which were not produced from the corresponding epoxides under the same conditions. In styrene oxygenation, an electron-donating substituent on the substrate decreased the reactivity, whereas in N,N-dimethylaniline demethylation, it enhanced the reactivity. Despite the use of the same reagents, the key intermediates of these two reactions are different. Fe2+TPP-σ-alkyl complexes produced from Fe3+TPPCl, olefin, and NaBH4 were identified as intermediates under anaerobic conditions. Fe2+TPP-σ-alkyl complex reacted with molecular dioxygen to give oxygenated products. Examination of the relative reactivities of p-substituted N,N-dimethylanilines in the NaBH4 reaction system revealed first, that the demethylation proceeded via one-electron abstraction, and second, that the reactive species of the demethylation reactions seems to be an iron-oxenoid.
Redox inactive metal ion triggered N-dealkylation by an iron catalyst with dioxygen activation: A lesson from lipoxygenases
Zhang, Jisheng,Wang, Yujuan,Luo, Nengchao,Chen, Zhuqi,Wu, Kangbing,Yin, Guochuan
, p. 9847 - 9859 (2015)
Utilization of dioxygen as the terminal oxidant at ambient temperature is always a challenge in redox chemistry, because it is hard to oxidize a stable redox metal ion like iron(iii) to its high oxidation state to initialize the catalytic cycle. Inspired by the dioxygenation and co-oxidase activity of lipoxygenases, herein, we introduce an alternative protocol to activate the sluggish iron(iii) species with non-redox metal ions, which can promote its oxidizing power to facilitate substrate oxidation with dioxygen, thus initializing the catalytic cycle. In oxidations of N,N-dimethylaniline and its analogues, adding Zn(OTf)2 to the [Fe(TPA)Cl2]Cl catalyst can trigger the amine oxidation with dioxygen, whereas [Fe(TPA)Cl2]Cl alone is very sluggish. In stoichiometric oxidations, it has also been confirmed that the presence of Zn(OTf)2 can apparently improve the electron transfer capability of the [Fe(TPA)Cl2]Cl complex. Experiments using different types of substrates as trapping reagents disclosed that the iron(iv) species does not occur in the catalytic cycle, suggesting that oxidation of amines is initialized by electron transfer rather than hydrogen abstraction. Combined experiments from UV-Vis, high resolution mass spectrometry, electrochemistry, EPR and oxidation kinetics support that the improved electron transfer ability of iron(iii) species originates from its interaction with added Lewis acids like Zn2+ through a plausible chloride or OTf- bridge, which has promoted the redox potential of iron(iii) species. The amine oxidation mechanism was also discussed based on the available data, which resembles the co-oxidase activity of lipoxygenases in oxidative dealkylation of xenobiotic metabolisms where an external electron donor is not essential for dioxygen activation.
First gold(I) complex-catalyzed oxidative carbonylation of amines for the syntheses of carbamates
Shi,Deng
, p. 443 - 444 (2001)
At 200 °C and 5 MPa of initial total pressure, the oxidative carbonylation of amines for the synthesis of the corresponding carbamates by Au(I) complexes as catalysts was conducted with excellent conversion and selectivity.
Carbamate synthesis from amines and dialkyl carbonate over inexpensive and clean acidic catalyst-Sulfamic acid
Wang, Bo,He, Jing,Sun, Run Cang
, p. 794 - 797 (2010)
Sulfamic acid has been proved to be the most efficient and recyclable catalyst in carbamate synthesis from alkylamine and dialkyl carbonate. High selectivity, cost-efficiency and simple product separation were the advantageous features obtained in this process. Sulfamic acid could be reused several times and keep its initial activity in the recycle runs. In addition, sulfamic acid has also exhibited the potential catalytic ability for alkylation of aromatic amines.
Heterocyclization of iminium salts from some β-amino-β-lactams and their gem-difunctional derivatives
Nisole,Uriac,Huet,Toupet
, p. 1081 - 1098 (1992)
β-Amino-β-lactams and their gem-difunctional derivatives of two series (1-benzoazepine and linear analog) lead stereospecifically to two types of heterocycles in strong acidic medium. Iminium ions and benzylic carbocations are proposed as reactive intermediates.
Selective electrocatalytic oxidation of N-alkyl-N-methylanilines to N-alkylformanilides using nitroxyl radical
Kashiwagi,Anzai
, p. 324 - 326 (2001)
Electrocatalytic oxidation of N-alkyl-N-methylanilines was studied using 4-benzoyloxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl as a nitroxyl radical. The reaction with N-alkyl-N-methylanilines led to direct formation of N-alkylformanilides in the presence of H2O in reaction media in adequate conversion (>75.8%), high current efficiency (>89.2%) and high selectivity (>93.8%).
The design, synthesis and evaluation of selenium-containing 4-anilinoquinazoline hybrids as anticancer agents and a study of their mechanism
An, Baijiao,Zhang, Shun,Hu, Jinhui,Pan, Tingting,Huang, Ling,Tang, Johnny Cheuk-On,Li, Xingshu,Chan, Albert S. C.
, p. 4701 - 4714 (2018)
Inhibition of tubulin polymerization is one of the significant strategies in the treatment of cancer. Inspired by the excellent antitumor activity of EP128495 and the beneficial biological activities of selenium compounds, a series of new selenium-containing 4-anilinoquinazoline hybrids were synthesized and evaluated as tubulin polymerization inhibitors. An anti-proliferative activity assay showed that most of the compounds inhibited human sensitive cancer cells at low nanomolar concentrations. A mechanism study revealed that the optimal compound 5a disrupted microtubule dynamics, decreased the mitochondrial membrane potential and arrested HeLa cells in the G2/M phase, finally resulting in cellular apoptosis.
Selective mono-N-methylation of nitroarenes with methanol catalyzed by atomically dispersed NHC-Ir solid assemblies
Chen, Jiangbo,Chen, Zhe-Ning,Tu, Tao,Wang, Jiaquan,Wen, Daheng,Wu, Jiajie,Xu, Xin,Zheng, Qingshu
, p. 337 - 344 (2020)
A series of N-heterocyclic carbene-iridium (NHC-Ir) coordination assemblies based on bis-pyrenoimidazolium salts are prepared, and shown to function as efficient solid molecular catalysts in selective mono-N-methylation of nitroarenes with methanol under mild conditions. The atomically dispersed active Ir(I) centers and the large π-conjugation rings endow the solid catalysts with an exceptionally high activity and selectivity for a broad substrate scope. Such solid NHC-Ir coordination assemblies are robust, which can be easily recovered and reused more than 10 runs without significant loss of their catalytic activity and selectivity. When combined with a subsequent formylation using the same solid catalysts under ambient conditions, this novel protocol can afford diverse formamides in excellent yields, further highlighting the applicability of the present solid catalysts for an efficient diversification of nitroarenes to a broad number of functional amines.
Catalysis of Anilide Ethanolysis by Barium- and Strontium - Ethoxide Pairs and Their Complexes with 18-Crown-6
Cacciapaglia, Roberta,Di Stefano, Stefano,Kelderman, Erik,Mandolini, Luigi,Spadola, Francesco
, p. 6476 - 6479 (1998)
The metal-bound ethoxide species that are quantitatively formed upon mixing equimolar amounts of Me4NOEt and alkaline-earth (Ba, Sr) metal salt in ethanol solution are more reactive than free ethoxide in the cleavage of simple activated amides (e.g. N-methyl-2,2,2-trifluoroacetanilide) lacking any donor group for binding to the metal ion. It is suggested that a metal-coordinated solvent molecule acts as a general acid catalyst for expulsion of the aniline leaving group in the rate-determining step. The position of the proton in the transition state is strongly dependent upon structural variations in the aniline portion, as suggested by the magnitude of kinetic solvent isotope effects. Enhanced catalysis is observed upon addition of equimolar amounts of 18-crown-6, which is tentatively interpreted on the basis of the notion that ion pairing is weakened upon cation binding to a crown ether. Important differences concerning metal ion effects in amide vs ester cleavage are pointed out and discussed on the basis of results obtained upon structural modifications of the substrates.
Reaction of Aluminium Hydride-Triethylamine Complex with Selected Organic Compounds Containing Representative Functional Groups
Cha, Jin Soon,Brown, Herbert C.
, p. 3974 - 3979 (1993)
The addition of triethylamine to a solution of aluminium hydride in tetrahydrofuran (THF), which was prepared by the addition of a calculated amount of hydrogen chloride in diethyl ether to solutions of sodium aluminium hydride in THF, provides very stable solutions of aluminium hydride-triethylamine complex (AHTEA).The reducing power of AHTEA complex in tetrahydrofuran toward 59 selected organic compounds containing representative functional groups under practical conditions (tetrahydrofuran, room temperature, the quantitative amount of reagent to compound) has been investigated.In this way, we have established that quantitative reduction of various organic functionalities can be readily achieved using the calculated quantity of AHTEA to avoid the use of excess reagent.This permits ready use of the aluminium hydride reagent in organic synthesis with high convenience and efficiency, with the possibility of an improved selectivity than that of aluminium hydride itself in tetrahydrofuran.
Oxoiminium Ions for N-Demethylation: 1-Oxo-2,2,6,6,-tetramethylpiperidinium Chloride
Hunter, Duncan H.,Racok, Julie S.,Rey, Allan W.,Ponce, Yolanda Zea
, p. 1278 - 1281 (1988)
In an attempt to assess the synthetic utylity of oxoiminium ions as oxidizing agents and to delineate their reaction mechanisms, we reacted 1-oxo-2,2,6,6-tetramethylpiperidinium chloride (1) with several N,N-dialkylanilines.With N,N-dimethylaniline the only basic product was N-nethylaniline while N- methylformanilide was the only neutral product.The relative amounts of base and neutral product proved to be sensitive to the amount of water present in the reaction medium.With N-alkyl-N-methylanilines, the basic products were N-alkylanilines from exlusive loss of the N-methyl group.The neutral products were the N-alkylformanilides.The alkyl groups studied were ethyl, n-butyl, isopropyl, and benzyl.With N-tert-butyl-N-methylaniline, there was no observed reaction, and N,N-diethylaniline was found to be significantly less reactive than N,N-dimethylaniline.This study has shown that 1 is selective in N-demethylation of anilines in the presence of other alkyl groups either on the same nitrogen or on separate nitrogens.These results have been interpreted in terms of important steric interactions resulting from formation of an adduct en route to an intermediate iminium ion.
N -Methylation of ortho -substituted aromatic amines with methanol catalyzed by 2-arylbenzo [d] oxazole NHC-Ir(iii) complexes
Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhou, Quan,Lin, Yue-Jian,Hou, Xiu-Feng
, p. 5072 - 5082 (2019)
Seven new chelated cyclometalated Ir complexes of ABON,P, ABON,O, and ABON,C(carbene) based on a rigid and tunable 2-arylbenzo[d]oxazole backbone have been prepared for the N-methylation of amines. Among these three coordinated modes, ABON,C(carbene)-chelated iridium-based catalysts exhibited good performance in the monomethylation of aromatic amines with methanol (MeOH) as the green methylation reagent. The steric-modified synthesis of ABON,C(carbene) complexes was described. The most active ABON,C(carbene) complex with marginal steric hindrance as a catalyst was obtained from the benzoxazole ring without a substituent and methyl group of the benzimidazole ring on the N-heterocyclic carbene (NHC) ligand. A variety of amines including para- and meta-substituted aromatic amines, as well as heterocyclic amines, were formulated as suitable substrates. Importantly, this catalyst considerably promoted the yield of the N-methylation of ortho-substituted aromatic amines. Controlled kinetic experiments and deuterium-labeling reactions of these ortho-substituted amines were conducted under optimized conditions. On the basis of the experimental results, a plausible mechanism was proposed.
Reduction of hydrazines, azo and azoxy compounds, and amine N-oxides with the NiCl2·2H2O-Li-DTBB (cat.) combination
Alonso, Francisco,Radivoy, Gabriel,Yus, Miguel
, p. 8673 - 8678 (2000)
The NiCl2·2H2O/Li/DTBB (10 mol%) combination allows the reduction of aromatic hydrazines 1 (to amines), azo compounds 2 (to primary amines), azoxy compounds 3 (to azo compounds or to primary amines, depending on the reaction conditions) or amine N-oxides 4 (to tertiary amines), under mild reaction conditions (THF, room temperature). (C) 2000 Elsevier Science Ltd.
Selective monomethylation of primary amines with simple electrophiles
Lebleu, Thomas,Ma, Xiaolu,Maddaluno, Jacques,Legros, Julien
, p. 1836 - 1838 (2014)
Direct monomethylation of primary amines with methyl triflate was achieved with high selectivity (up to 96%). The key point of this single methyl transfer stems from the use of HFIP as the solvent that interferes with amines and avoids overmethylation.
Synthesis of N-Methylaniline and N,N-Dimethylaniline with Methanol over Alumina Catalyst
Matsuhashi, Hiromi,Arata, Kazushi
, p. 2605 - 2606 (1991)
Alumina catalysts prepared by different methods were used for the synthesis of N-methylaniline and N,N-dimethylaniline from aniline and methanol.Al2O3 catalysts prepared from isopropoxide and nitrate showed high activity and JRC-ALO-1 and JRC-ALO-3 supplied by the Catalysis Society of Japan showed low activity.The highest selectivity for N,N-dimethylaniline was 82.8percent with 90.1percent aniline conversion.The catalytic activity of Al2O3 was not poisoned by pyridine and CO2.
Surface species formed during aniline methylation on zeolite H-Y investigated by in situ MAS NMR spectroscopy
Ivanova, Irina I.,Pomakhina, Elena B.,Rebrov, Alexander I.,Hunger, Michael,Kolyagin, Yuryi G.,Weitkamp, Jens
, p. 375 - 381 (2001)
Aniline alkylation with methanol on zeolite H-Y has been studied using in situ 13C MAS NMR spectroscopy under batch conditions. To clarify the main reaction pathways, the conversion of methanol as well as the interaction of aniline with surface methoxy groups were investigated under similar conditions. Methanol-13C and methyl iodide-13C were used as labeled reactants. Co -adsorption of aniline and methanol-13C on zeolite H-Y led to strongly adsorbed aniline molecules, assigned to aniline H-bonded to zeolite Bronsted acid sites, and three types of methanol species of different mobility: mobile methanol molecules with a liquid-like characteristics and two types of rigid methanol species with solid-like characteristics attributed to a methanol adsorption complex with aniline and surface methoxy groups, respectively. Among all the methanol species observed, only surface methoxy groups were shown to be responsible for aniline alkylation which takes place at temperatures from 373 to 523 K. The formation of surface methoxy groups was found to be a limiting step of the overall reaction. The primary alkylation product is N-methylaniline. Toluidines and N-methyltoluidines are formed at temperatures from 523 to 623 K after complete conversion of methanol to N-methylaniline. Therefore, isomerization or disproportionation of N-methylaniline was proposed to account for their formation.
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Coats,Katritzky
, p. 1836 (1959)
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Deactivation of heterogeneous hydrogenation catalysts by alcoholic solvents
Singh, Utpal K.,Krska, Shane W.,Sun, Yongkui
, p. 1153 - 1156 (2006)
Hydrogenations using supported metal catalysts are ubiquitous in organic chemistry; yet often times there is a lack of knowledge of key subtle mechanistic features of these reactions that can spell the difference between success or failure in a given synthetic application. Herein we detail an unexpected deactivation of certain heterogeneous hydrogenation catalysts caused by the typical solvent of choice for such reactions, simple aliphatic alcohols. This phenomenon was found to be general for several classes of substrates using either Raney Ni or supported Pd-catalysts. The characteristics of this phenomenon, including the reversibility of the catalyst deactivation upon exposure to air, are consistent with literature reports of alcohol decomposition on metal surfaces forming adsorbed CO.
Scandium ion-enhanced oxidative dimerization and N -demethylation of N, N -dimethylanilines by a non-heme iron(IV)-oxo complex
Park, Jiyun,Morimoto, Yuma,Lee, Yong-Min,You, Youngmin,Nam, Wonwoo,Fukuzumi, Shunichi
, p. 11612 - 11622 (2011)
Oxidative dimerization of N,N-dimethylaniline (DMA) occurs with a nonheme iron(IV)-oxo complex, [FeIV(O)(N4Py)]2+ (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), to yield the corresponding dimer, tetramethylbenzidine (TMB), in acetonitrile. The rate of the oxidative dimerization of DMA by [FeIV(O)(N4Py)]2+ is markedly enhanced by the presence of scandium triflate, Sc(OTf)3 (OTf = CF3SO3-), when TMB is further oxidized to the radical cation (TMB?+). In contrast, we have observed the oxidative N-demethylation with para-substituted DMA substrates, since the position of the C-C bond formation to yield the dimer is blocked. The rate of the oxidative N-demethylation of para-substituted DMA by [FeIV(O) (N4Py)]2+ is also markedly enhanced by the presence of Sc(OTf) 3. In the case of para-substituted DMA derivatives with electron-donating substituents, radical cations of DMA derivatives are initially formed by Sc3+ ion-coupled electron transfer from DMA derivatives to [FeIV(O)(N4Py)]2+, giving demethylated products. Binding of Sc3+ to [FeIV(O)(N4Py)]2+ enhances the Sc3+ ion-coupled electron transfer from DMA derivatives to [Fe IV(O)(N4Py)]2+, whereas binding of Sc3+ to DMA derivatives retards the electron-transfer reaction. The complicated kinetics of the Sc3+ ion-coupled electron transfer from DMA derivatives to [FeIV(O)(N4Py)]2+ are analyzed by competition between binding of Sc3+ to DMA derivatives and to [FeIV(O)(N4Py)] 2+. The binding constants of Sc3+ to DMA derivatives increase with the increase of the electron-donating ability of the para-substituent. The rate constants of Sc3+ ion-coupled electron transfer from DMA derivatives to [FeIV(O)(N4Py)]2+, which are estimated from the binding constants of Sc3+ to DMA derivatives, agree well with those predicted from the driving force dependence of the rate constants of Sc3+ ion-coupled electron transfer from one-electron reductants to [FeIV(O)(N4Py)]2+. Thus, oxidative dimerization of DMA and N-demethylation of para-substituted DMA derivatives proceed via Sc3+ ion-coupled electron transfer from DMA derivatives to [FeIV(O)(N4Py)]2+.
P(III)/P(V)-Catalyzed Methylamination of Arylboronic Acids and Esters: Reductive C-N Coupling with Nitromethane as a Methylamine Surrogate
Li, Gen,Qin, Ziyang,Radosevich, Alexander T.
, p. 16205 - 16210 (2020)
The direct reductive N-arylation of nitromethane by organophosphorus-catalyzed reductive C-N coupling with arylboronic acid derivatives is reported. This method operates by the action of a small ring organophosphorus-based catalyst (1,2,2,3,4,4-hexamethylphosphetane P-oxide) together with a mild terminal reductant hydrosilane to drive the selective installation of the methylamino group to (hetero)aromatic boronic acids and esters. This method also provides for a unified synthetic approach to isotopically labeled N-methylanilines from various stable isotopologues of nitromethane (i.e., CD3NO2, CH315NO2, and 13CH3NO2), revealing this easy-to-handle compound as a versatile precursor for the direct installation of the methylamino group.
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Grandjean et al.
, p. 207,210 (1976)
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Substituted tetraphenyl porphyrin catalyzed oxidative N-dealkylation of tertiary amine using molecular oxygen
Agarwal, Dau. D.,Bhat, Daisy
, p. 689 - 693 (2016)
Oxidative N-dealkylation of NN-dimethylaniline catalyzed by substituted tetraaryl porphyrin complexes of iron and manganese with molecular oxygen, gave a mixture of dealkylated, monooxygenated and dimerised compounds as products. Presence of substituents on the catalyst effects nature and yield of products formed. One electron transfer route [E T) predominated over H-atom abstraction [HAT] in most of the reactions.
Alkylation of aniline with methanol in the presence of FeCl 3·6H2O in carbon tetrachloride
Khusnutdinov,Bayguzina,Aminov
, p. 1447 - 1450 (2013)
The reaction of aniline with methanol in the presence of FeCl 3·6 H2O in carbon tetrachloride leads to the formation of N-methyl- and N,N-dimethylanilines and 4,4′-methylenebis(N,N- dimethylaniline).
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Fischer
, p. 4295 (1968)
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CuCl2-catalyzed one-pot formation of tetrahydroquinolines from N-methyl-N-alkylanilines and vinyl ethers in the presence of t-butylhydroperoxide
Yang, Xianghua,Xi, Chanjuan,Jiang, Yanfeng
, p. 978 - 987 (2006)
Tetrahydroquinoline skeletons can be formed by a CuCl2-catalyzed one-pot reaction of N-methyl-N-alkylanilines and vinyl ethers in the presence of t-butylhydroperoxide.
An Efficient Metal-Free Method for the Denitrosation of Aryl N-Nitrosamines at Room Temperature
Chaudhary, Priyanka,Korde, Rishi,Gupta, Surabhi,Sureshbabu, Popuri,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
, p. 556 - 561 (2018)
A simple and practical method for the denitrosation of aryl N-nitrosamines to secondary amines is reported under metal-free conditions using iodine and triethylsilane. Several reduction-susceptible functional groups such as alkene, alkyne, nitrile, nitro, aldehyde, ketone and ester were found to be very stable during the denitrosation, which is remarkable. Broad substrate scope, room temperature reactions and excellent yields are the additional features of the current methodology. (Figure presented.).
Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2for consecutiveN-methylation of amines
Das, Arpan,Maji, Subir,Mandal, Swadhin K.
, p. 12174 - 12180 (2021)
A mesoionic N-heterocyclic olefin (mNHO) was introduced as a metal-free catalyst for the reductive functionalization of CO2leading to consecutive doubleN-methylation of primary amines in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN). A wide range of secondary amines and primary amines were successfully methylated under mild conditions. The catalyst sustained over six successive cycles ofN-methylation of secondary amines without compromising its activity, which encouraged us to check its efficacy towards doubleN-methylation of primary amines. Moreover, this method was utilized for the synthesis of two commercially available drug molecules. A detailed mechanistic cycle was proposed by performing a series of control reactions along with the successful characterisation of active catalytic intermediates either by single-crystal X-ray study or by NMR spectroscopic studies in association with DFT calculations.
One-pot photo-reductive N-alkylation of aniline and nitroarene derivatives with primary alcohols over Au-TiO2
Stibal, David,Sa, Jacinto,Bokhoven, Jeroen A. Van
, p. 94 - 98 (2013)
We report the photo-catalytic N-alkylation of aniline by Au-TiO 2. We successfully alkylate aniline with several primary alcohols. The combined selectivities of mono- and di-alkylated products were always in excess of 70% and dependent on the alkylating alcohol used. A one-pot reaction from nitrobenzene was found to be possible with several substrates. Preliminary experiments showed that this approach could be adopted for the production of lactams using terminal amino-alcohols. The Royal Society of Chemistry 2013.
N-Methylation of amine and nitro compounds with CO2/H2 catalyzed by Pd/CuZrOx under mild reaction conditions
Cui, Xinjiang,Zhang, Yan,Deng, Youquan,Shi, Feng
, p. 13521 - 13524 (2014)
An active Pd/ZrCuOx catalyst was prepared for the reductive amination of CO2. The N-methylation of amines and nitro compounds with CO2/H2 can be realized with up to 97% yield under relatively mild reaction condi
Photocatalytic degradation of michler's ketone in water by Uv light illumination using TiO2 photocatalyst: Identification of intermediates and the reaction pathway
Lu, Chung-Shin,Mai, Fu-Der,Wu, Yi-Chin,Yao, I-Chun,Hsu, Peng-Yueh,Chen, Chiing-Chang
, p. 729 - 740 (2009)
The TiO2/UV photocatalytic degradation ofMichler's Ketone (MK) has been investigated in aqueous heterogeneous suspensions. Results obtained show rapid and complete oxidation of MK after 24-h, and more than 97.5% of MK was mineralized after a 32-h exposure
Distinguishing Rate-Limiting Electron versus H-Atom Transfers in Cu 2(O2)-Mediated Oxidative N-Dealkylations: Application of Inter- versus Intramolecular Kinetic Isotope Effects
Shearer, Jason,Zhang, Christiana Xin,Hatcher, Lanying Q.,Karlin, Kenneth D.
, p. 12670 - 12671 (2003)
Copper-dioxygen adducts are important biological oxidants. To gain a better understanding of the underlying chemistries of such species, we report on a series of Cu2II-O2 complexes, [{CuII(MePY2)R-}2(O2)](B(C6F5)4)2 (1R-) (where (MePY2)R- is a 4-pyridyl substituted bis[2-(2-(4-R-pyridyl)ethyl]methylamine; R- = H, MeO, Me2N; Zhang, C. X.; et al. J. Am. Chem. Soc. 2003, 125, 634-635), which readily oxidize exogenous substrates. In this study, we explore the mechanism by which 1R- facilitates the oxidative N-dealkylation of para-substituted N,N-dimethylanilines (R-DMA; R = MeO, Me, H, CN). In the case of 1H, the linear free-energy correlation plot (ρ = -2.1) and intramolecular deuterium kinetic isotope effect (KIEintra, using p-R-(C6H4)-N(CH3)(CD3)) profile suggest that R-DMA oxidation occurs through rate-limiting electron transfer (ET). This mechanism was further enforced by comparison of KIEintra versus the intermolecular KIE (KIEinter, using p-R-(C6H4)-N(CH3)2 versus p-R-(C6H4)-N(CD3)2). It was found that KIEinter intra, suggesting an ET process. In the case of both 1MeO and 1Me2N, the KIEintra profile and linear free-energy correlation plots (ρ = -0.49 and -0.99 for 1Me2N and 1MeO with especially poor fitting for the latter) are inconclusive in distinguishing between a rate-limiting ET or hydrogen atom transfer (HAT) pathway. Comparisons of KIEinter versus KIEintra demonstrate a switch in mechanism from ET to HAT for 1Me2N and 1MeO oxidation of R-DMA as R-DMA is made less reducing. In the case of 1Me2N, MeO-DMA and Me-DMA are oxidized via a rate-limiting ET (KIEinter intra), while H-DMA and CN-DMA are oxidized through a HAT pathway (KIEinter ≈ KIEintra). For 1MeO, oxidation occurs through an ET pathway for MeO-, Me-, and H-DMA (KIEinter intra), while CN-DMA is oxidized though a HAT process (KIEinter ≈ KIEintra). Copper complex attributes, which may contribute to the mechanistic observations, are suggested. Copyright
A Highly Dispersed Copper Nanoparticles Catalyst with a Large Number of Weak Acid Centers for Efficiently Synthesizing the High Value-Added 3-Methylindole by Aniline and Biomass-Derived Glycerin
Sun, Pinghui,Lin, Shuyi,Guo, Huimei,Su, Jianhui,Shi, Lei
, p. 463 - 477 (2021)
Abstract: An excellent catalyst with a large number of weak acid centers and highly dispersed copper nanoparticles embedded in mesoporous SBA-15 carrier was successfully constructed for the purpose of efficient conversion of aniline with biomass-derived glycerin to the high value-added 3-methylindole, in which the catalyst of Cu/SBA-15 was modified with Al2O3, La2O3 and CoO in sequence. The modified carrier and the copper-based catalysts were studied by scanning electron microscopy and energy-dispersive X-ray (SEM–EDX) spectroscopy, nitrogen physical adsorption, ammonia temperature programmed desorption (NH3-TPD), hydrogen temperature programmed reduction (H2-TPR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric and differential thermal analysis (TG–DTA) and inductively coupled plasma (ICP) emission spectroscopy. The research found that the Cu/CoO/La2O3/Al2O3/SBA-15 catalyst exhibited a very good catalytic performance with 3-methylindole yield up to 73.3% and selectivity reaching 86.4%. Besides, only a 3.9% yield decreased after the catalyst was circulated seven times. The characterizations revealed that Al2O3 could enhance the polarity of the carrier, thereby the interaction between the active component and the composite carrier was strengthened and the dispersion of copper was increased significantly. Adding La2O3 to Cu/SBA-15-Al2O3 could weaken the acidity and inhibit the formation of carbon deposits. CoO promoter could increase the number of weak acid centers, which was conducive to a good dispersion of active component and the high selectivity of 3-methylindole. Furthermore, the reaction pathway of gas-phase synthesis of 3-methylindole from glycerin and aniline on Cu/CoO/La2O3/Al2O3/SBA-15 was explored. Graphic Abstract: [Figure not available: see fulltext.]
Continuous acid-catalyzed methylations in supercritical carbon dioxide: Comparison of methanol dimethyl ether and dimethyl carbonate as methylating agents
Gooden, Peter N.,Bourne, Richard A.,Parrott, Andrew J.,Bevinakatti, Han S.,Irvine, Derek J.,Poliakoff, Martyn
, p. 411 - 416 (2010)
The development of high-yielding, "greener" chemistry-based routes for the continuous synthesis of methyl ethers are reported in this study. Ethers have been efficiently produced using a methodology which eliminates the use of toxic alkylating agents and reduces the waste generation that is characteristic of traditional etherification processes. For the first time it is shown that the use of acidic heterogeneous catalysts can successfully achieve etherification when using scCO2 as a reaction medium. Furthermore, the relative efficiencies of three alternative methylating agents, dimethyl carbonate, dimethyl ether and MeOH, have been compared and contrasted for the methylation of 1-octanol. Dimethyl carbonate has proven to be the superior methylating agent, demonstrating higher conversion and selectivity. Successful methylation of secondary alcohols, diols, carboxylic acids and amines using dimethyl carbonate in supercritical carbon dioxide has also been shown. Substrate structure was found to influence the temperature required to maximize the yield of the desired product, substrates with multiple hydroxyl groups requiring the highest temperatures.
Deprotection of sulfonamides using iodotrimethylsilane
Sabitha, Gowravaram,Subba Reddy,Abraham, Sunny,Yadav
, p. 1569 - 1570 (1999)
The deprotection of sulfonamides is achieved under neutral conditions by reaction with iodotrimethylsilane in acetonitrile at reflux.
Ruthenium-Catalyzed N-Alkylation and N-Benzylation of Aminoarenes with Alkohols
Watanabe, Yoshihisa,Tsuji, Yasushi,Ige, Hitoshi,Ohsugi, Yukihiro,Ohta, Tetsuo
, p. 3359 - 3363 (1984)
Aminoarenes were readily converted into secondary and tertiary amines by the reaction at 150-180 deg C with primary alcohols in the presence of a catalytic amount (1 mol percent based on the aminoarene) of a ruthenium complex.Dichlorotris(triphenylphosphine)ruthenium was the most effective catalyst precursor.Secondary amines were obtained in excellent yields when aminoarenes reacted with an equimolar amount of alcohols.With excess alcohols, tertiary amines were obtained predominantly.Kinetic measurements revealed that the rate had zero-order dependence on aminoarene concentration and first-order dependence on alcohol concentration and initial concentration of the ruthenium catalyst.From the kinetic features, the possible catalytic cycle, which includes the nucleophilic attack of the aminoarene on aldehyde intermediate, was postulated.
Investigation of supported Zn(OAc)2 catalyst and its stability in N-phenyl carbamate synthesis
Li, Fang,Li, Wenbo,Li, Jing,Xue, Wei,Wang, Yanji,Zhao, Xinqiang
, p. 355 - 362 (2014)
Zn(OAc)2 was found to give excellent catalytic performance for methyl N-phenyl carbamate (MPC) synthesis from aniline and dimethyl carbonate (DMC). However, after being used for only once it tended to lose activity because of the formation of ZnO by the reaction of Zn(OAc)2 and methanol. Zn(OAc)2/SiO2 was prepared by incipient impregnation and it gave excellent catalytic performance in MPC synthesis, on which aniline conversion and MPC yield were 98.1% and 93.8%, respectively. And Zn(OAc)2/SiO2 was found to be more stable than Zn(OAc)2 during the reaction. When Zn(OAc)2/SiO 2 was used for the fifth time, aniline conversion and MPC yield were found to be 64.3% and 38.1%, respectively. The Zn(OAc)2/SiO 2 catalyst was characterized by TG-DTA, ICP, FTIR, XRD and XPS. The characterization results suggested that the deactivation of Zn(OAc) 2/SiO2 was also due to the formation of ZnO and there were two reasons for the improved stability of Zn(OAc)2/SiO2 catalyst. One was the formation of the Si-O-Zn bonds in Zn(OAc) 2/SiO2 catalyst, which increased the steric hindrance of Zn and consequently retarded the reaction between Zn(OAc)2 and methanol. The other cause was the dehydration between methanol and the hydroxyl group on the SiO2 surface, which reduced the chance of a reaction between methanol and Zn(OAc)2.
N-(α-Aminoalkyl)benzotriazoles: Novel "Nonstabilized" α-Aminocarbanion Synthons
Katritzky, Alan R.,Qi, Ming,Feng, Darning,Nichols, Daniel A.
, p. 4121 - 4124 (1997)
C-Benzotriazole bonds were selectively transformed to give the corresponding α-aminocarbanions when N-(α-aminoalkyl)benzotriazoles were reacted with either Li/LiBr or SmI2 in the presence of representative electrophiles. The ranges of applicability of the two reagents complement each other, and together the two protocols provide a general route from readily available crystalline starting materials to a variety of "nonstabilized" α-aminocarbanions that can be trapped in moderate to good yields.
Reductive monoalkylation of aromatic amines via amidine intermediates
Zhang, Jianxing,Chang, Hui-Min,Kane, Robert R.
, p. 643 - 645 (2001)
The convenience and efficiency of using amidines as intermediates in the reductive monoalkylation of aromatic amines has been demonstrated. This monoalkylation can be performed as either a two-step synthesis or a one-pot procedure. Several examples are presented which clearly demonstrate the utility of this new method for the methylation or ethylation of aromatic amines, including unprotected nucleosides.
Absolute kinetics of aminium radical reactions with olefins in acetonitrile solution
Wagner, Brian D.,Ruel, Géraldine,Lusztyk, Janusz
, p. 13 - 19 (1996)
Photolysis of N-nitrosamines in acidic acetonitrile produces aminium radical cations via protonation of the initially-formed aminyl radicals. The kinetics of these species can be monitored by transient UV spectroscopy via their absorption band which is found at ca. 300 nm in the case of the piperidinium radical, for example. By measuring the aminium radicals' lifetimes as a function of the concentration of added olefin, absolute values for the bimolecular rate constants for the addition reactions were obtained. In the case of the piperidinium radical, these rate constants varied from 6 M-1 s-1 for acrylonitrile to 1.1 ± 0.1 × 109 M-1 s-1 for 1,1-diphenylethylene and generally increased with decreasing ionization potential of the olefin, thus confirming the electrophilic nature of the piperidinium radical. The rate constants for analogous reactions of diethylaminium radicals were 1.5-25 times smaller indicating the importance of steric factors in aminium radical additions to olefins. The rate constant for the intramolecular 1,5-addition of the secondary aminium radical cation to an unactivated double bond is estimated to be ca. 1 × 106 s-1, but the intramolecular addition rate constant increases to >1 × 108 s-1 upon the phenyl substitution at the olefinic terminus.
Enhanced N-demethylase activity of cytochrome c bound to a phosphate-bearing synthetic bilayer membrane
Hamachi, Itaru,Fujita, Akio,Kunitake, Toyoki
, p. 8811 - 8812 (1994)
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A general and convenient procedure for the synthesis of N- alkylarylamines and N-alkylheteroarylamines by electrophilic amination of cuprates with N-alkylhydroxylamines
Bernardi, Paolo,Dembech, Pasquale,Fabbri, Gaia,Ricci, Alfredo,Seconi, Giancarlo
, p. 641 - 643 (1999)
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Synthesis and structure of [Et3NH][Fe(HL)2] [H3L = L -2-(3,5-Di-tert-butyl-2-hydroxybenzylamino)succinic acid] and its catalytic activity towards efficient photodegradation of dyes in the presence of H2O2
Dasgupta, Sohaham,Atta, Sanghamitra,Singh, N. D. Pradeep,Deb, Dibakar,Kassel, W. Scott,Bhattacharjee, Manish
, p. 5125 - 5134 (2014)
A new biogenic potentially tetradentate ligand, L-2-(3,5-di-tert-butyl-2-hydroxybenzylamino)succinic acid, has been synthesized. Upon reaction with FeCl3 in the presence of triethylamine, it afforded the complex [Et3NH][Fe(HL)2] (1). The complex was structurally characterized and was used for homogeneous photocatalytic degradation of methylene blue (MB), malachite green (MG), crystal violet (CV) and rhodamine B (RhB) under visible-light irradiation in aqueous solution in the presence of H2O2.
Methylation of secondary amines with dialkyl carbonates and hydrosilanes catalysed by iron complexes
Zheng, Jianxia,Darcel, Christophe,Sortais, Jean-Baptiste
, p. 14229 - 14232 (2014)
Methylation of secondary amines was achieved using dimethyl carbonate or diethyl carbonate as the C1 source under the catalysis of well-defined half-sandwich iron complexes bearing an N-heterocyclic carbene ligand. The reaction proceeded under mild conditions in the presence of hydrosilanes as the reductants, and the amines were obtained with good to excellent isolated yields. This journal is
Co(acac)3/BMMImCl as a base-free catalyst system for clean syntheses of N,N′-disubstituted ureas from amines and CO2
Li, Jian,Guo, Xiaoguang,Wang, Liguo,Ma, Xiangyuan,Zhang, Qinghua,Shi, Feng,Deng, Youquan
, p. 1534 - 1540 (2010)
A base-free catalyst system Co(acac)3/BMMImCl was developed for the carbonylation of amines with CO2. 45%2-81% isolated yields for N,N-dialkylureas and 6%2-23% isolated yields for N,N-diarylureas were obtained. The catalyst system was recovered and reused without significant loss in activity. In this catalyst system, the base catalyst and chemical dehydrant were efficiently avoided. Different reaction conditions were also discussed and a postulated mechanism was proposed.
Zinc oxide surface: a versatile nanoplatform for solvent-free synthesis of diverse isatin derivatives
Kothandapani, Jagatheeswaran,Ganesan, Asaithampi,Mani, Ganesh Kumar,Kulandaisamy, Arockia Jayalatha,Rayappan, John Bosco Balaguru,Selva Ganesan, Subramaniapillai
, p. 3472 - 3475 (2016)
Multicomponent reactions performed on the surface of nanostructured zinc oxide gave 3,3-bis(indolyl)indolin-2-one and xanthene derivatives with excellent yields. Both Lewis acidic (Zn2+) and basic (O2?) sites on the surface of zinc oxide were utilized to perform the aforementioned transformations. The significance of surface catalysis was further proved by performing the experiment with surface masked zinc oxide. The developed zinc oxide nanocatalyst was reusable up to five times without significant loss in its activity.
A new route to N-aromatic heterocycles from the hydrogenation of diesters in the presence of anilines
Shi, Yiping,Kamer, Paul C. J.,Cole-Hamilton, David J.,Harvie, Michelle,Baxter, Emma F.,Lim, Kate J. C.,Pogorzelec, Peter
, p. 6911 - 6917 (2017)
The hydrogenation of dicarboxylic acids and their esters in the presence of anilines provides a new synthesis of heterocycles. [Ru(acac)3] and 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) gave good to excellent yields of the cyclic amines at 220 °C. When aqueous ammonia was used with dimethyl 1,6-hexadienoic acid, ?-caprolactam was obtained in good yield. A side reaction involving alkylation of the amine by methanol was suppressed by using diesters derived from longer chain and branched alcohols. Hydrogenation of optically pure diesters (dimethyl (R)-2-methylbutanedioate and dimethyl (S)-2-methylbutanedioate) with aniline afforded racemic 3-methyl-1-phenylpyrrolidine in 78% yield.
Mono-N-methylation of primary amines with alkyl methyl carbonates over Y faujasites. 2. Kinetics and selectivity
Selva, Maurizio,Tundo, Pietro,Perosa, Alvise
, p. 9238 - 9247 (2002)
In the presence of a Na-exchanged Y faujasite, the reaction of primary aromatic amines 1 with 2-(2-methoxyethoxy)methylethyl carbonate [MeO(CH2)2O(CH2)2 OCO2Me, 2a] yields the corresponding mono-N-methyl derivatives ArNHMe with selectivity up to 95%, at substantially quantitative conversions. At 130°C, the reaction can be run under diffusion-free conditions and is strongly affected by the solvent polarity: for instance, in going from xylene (εr = 2.40) to triglyme (εr = 7.62) as the solvent, the pseudo-first-order rate constant for the aniline (1a) disappearance shows a 5-fold decrease. In DMF (εr = 38.25), the same reaction does not occur at all. Competitive adsorption of the solvent and the substrate onto the catalytic sites accounts for this result. The behavior of alkyl-substituted anilines ZC6H4NH2 [Z = p-Me, p-Et, p-Pr, p-(n-Bu) (1b-e); Z = 3,5-di-tert-butyl- and 2,4,6-tri-tert-butylanilines (1f,g)] and p-alkoxyanilines p-ZC6H4NH2 [Z = OMe, OEt, OPr, O-n-Bu (1b′-e′)] clearly indicates a steric effect of ring substituents: as diffusion of the amine into the catalytic pores is hindered, the reaction hardly proceeds and the mono-N-methyl selectivity (SM/D) drops as well. Moreover, the strength of adsorption of the amine onto the catalyst influences the rate and the selectivity as well: the reaction of p-anisidine and p-toluidine - despite the higher nucleophilicity of these compounds - is slower and even less selective with respect to aniline. From a mechanistic viewpoint, the intermediacy of carbamates ArN(Me)CO2R [R = MeO-(CH2)2O(CH2)2] is suggested. At 90°C, the reaction of benzylamine (7) - a model for aliphatic amineswith dimethyl carbonate shows that the reaction outcome can be improved by tuning the amphoteric properties of the catalyst: in going from CsY to the more acidic LiY zeolite, methylation is not only more selective (SM/D ratio increases from 77% to 84%) but even much faster (CsY, conversion of 36% after 22 h; LiY, conversion of 43% after 7 h).
Electrochemical hydrodefluorination of fluoroaromatic compounds
Wu, Wen-Bin,Li, Mei-Li,Huang, Jing-Mei
, p. 1520 - 1523 (2015)
The BH4-- promoted electrochemical hydrodefluorination of fluoroaromatic compounds was reported. Using platinum as electrodes in an undivided cell, the electrolysis was carried out at constant current at room temperature under air without the need of pretreatment of the solvent. This reaction could proceed smoothly on both nonactivated monofluoroarenes and perfluoroarenes with high yields and good selectivities.
Green and chemo selective amine methylation using methanol by an organometallic ruthenium complex
Abbasi, Alireza,Dindar, Sara,Nemati Kharat, Ali
, (2021/11/16)
Herein a green and convenient catalytic N-methylation of aniline and n-hexylamine using methanol as a dual methylation agent and solvent has been investigated. A new ruthenium carbonyl complex was synthesized and applied as a homogeneous catalyst in methylation reaction. The solid-state structure of the complex was determined by X-ray crystallographic analysis which indicate xantphos ligand bonded to ruthenium (II) as a tridentate pincer ligand by two P donor and one O atom. The catalytic system showed excellent conversion and selectivity toward N-methylaniline, and N,N-hexyldimethylamine at 140°C.
Electronically tuneable orthometalated RuII–NHC complexes as efficient catalysts for C–C and C–N bond formations via borrowing hydrogen strategy
Illam, Praseetha Mathoor,Rit, Arnab
, p. 67 - 74 (2022/01/19)
The catalytic activities of a series of simple and electronically tuneable cyclometalated RuII–NHC complexes (2a–d) were explored in various C–C/N bond formations following the borrowing hydrogen process. Slight modifications in the ligand backbone were noted to tune the activities of these complexes. Among them, the complex 2d featuring a 1,2,4-triazolylidene donor with a 4-NO2–phenyl substituent displayed the highest activity for the coupling of diverse secondary and primary alcohols with a low catalyst loading of 0.01 mol% and a sub-stoichiometric amount of inexpensive KOH base. The efficacy of this simple system was further showcased in the challenging one-pot unsymmetrical double alkylation of secondary alcohols using different primary alcohols. Moreover, the complex 2d also effectively catalyses the selective mono-N-methylation of various aromatic and aliphatic primary amines using methanol to deliver a range of N-methyl amines. Mechanistically, the β-alkylation reaction follows a borrowing hydrogen pathway which was established by the deuterium labelling experiment in combination with various control experiments. Intriguingly, in situ1H NMR and ESI-MS analyses evidently suggested the involvement of a Ru–H species in the catalytic cycle and further, the kinetic studies revealed a first order dependence of the reaction rate on the catalyst as well as the alcohol concentrations.
Copper(i)-catalysed intramolecular hydroarylation-redox cross-dehydrogenative coupling ofN-propargylanilines with phosphites
Li, Guangzhe,Yu, Guo,Wang, Chengdong,Morita, Taiki,Zhang, Xuhai,Nakamura, Hiroyuki
supporting information, p. 113 - 116 (2021/12/29)
Intramolecular hydroarylation-redox cross-dehydrogenative coupling ofN-propargylanilines with phosphite diesters proceeded in the presence of Cu(i)-catalysts (20 mol%) to selectively give 2-phosphono-1,2,3,4-tetrahydroquinolines in good yields with 100% atomic utilization. P-H and two C-H bonds are activated at once and these hydrogen atoms are trapped by a propargylic triple bond in the molecule.
Additive-free selective methylation of secondary amines with formic acid over a Pd/In2O3 catalyst
Benaissa, Idir,Cantat, Thibault,Genre, Caroline,Godou, Timothé,Pinault, Mathieu
, p. 57 - 61 (2022/01/19)
Formic acid is used as the sole carbon and hydrogen source in the methylation of aromatic and aliphatic amines to methylamines. The reaction proceeds via a formylation/transfer hydrogenation pathway over a solid Pd/In2O3 catalyst without the need for any additive.
K2S2O8-induced site-selective phenoxazination/phenothiazination of electron-rich anilines
Lei, Aiwen,Wang, Pengjie,Wang, Shengchun,Wang, Xiaoyu,Yi, Hong,Zhang, He,Zhang, Heng
supporting information, p. 147 - 151 (2022/01/19)
By just using cheap K2S2O8 as the oxidant at room temperature in the air, the phenoxazination/phenothiazination of electron-rich anilines to construct or modify triarylamine derivatives has been established. This method demonstrates complete para-selective amination under catalyst-free conditions and its simplicity and efficiency lead to good performance in flow-chemistry synthesis.
