- Flash vacuum pyrolysis of 3-oxo-2-arylhydrazonopropanals and related derivatives
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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
- Ibrahim, Yehia A,Kaul, Kamini,Al-Awadi, Nouria A
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- Palladium-catalysed N,N'-disubstituted urea synthesis by oxidative carbonylation of amines under CO and O2 at atmospheric pressure
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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.
- Giannoccaro, Potenzo
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- 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
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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.
- Mori,Santa,Higuchi,Mashino,Hirobe
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- Redox inactive metal ion triggered N-dealkylation by an iron catalyst with dioxygen activation: A lesson from lipoxygenases
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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.
- Zhang, Jisheng,Wang, Yujuan,Luo, Nengchao,Chen, Zhuqi,Wu, Kangbing,Yin, Guochuan
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- First gold(I) complex-catalyzed oxidative carbonylation of amines for the syntheses of carbamates
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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.
- Shi,Deng
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- Carbamate synthesis from amines and dialkyl carbonate over inexpensive and clean acidic catalyst-Sulfamic acid
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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.
- Wang, Bo,He, Jing,Sun, Run Cang
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- Heterocyclization of iminium salts from some β-amino-β-lactams and their gem-difunctional derivatives
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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.
- Nisole,Uriac,Huet,Toupet
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- Selective electrocatalytic oxidation of N-alkyl-N-methylanilines to N-alkylformanilides using nitroxyl radical
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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%).
- Kashiwagi,Anzai
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- The design, synthesis and evaluation of selenium-containing 4-anilinoquinazoline hybrids as anticancer agents and a study of their mechanism
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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.
- An, Baijiao,Zhang, Shun,Hu, Jinhui,Pan, Tingting,Huang, Ling,Tang, Johnny Cheuk-On,Li, Xingshu,Chan, Albert S. C.
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- Selective mono-N-methylation of nitroarenes with methanol catalyzed by atomically dispersed NHC-Ir solid assemblies
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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.
- Chen, Jiangbo,Chen, Zhe-Ning,Tu, Tao,Wang, Jiaquan,Wen, Daheng,Wu, Jiajie,Xu, Xin,Zheng, Qingshu
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- Catalysis of Anilide Ethanolysis by Barium- and Strontium - Ethoxide Pairs and Their Complexes with 18-Crown-6
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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.
- Cacciapaglia, Roberta,Di Stefano, Stefano,Kelderman, Erik,Mandolini, Luigi,Spadola, Francesco
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- Reaction of Aluminium Hydride-Triethylamine Complex with Selected Organic Compounds Containing Representative Functional Groups
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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.
- Cha, Jin Soon,Brown, Herbert C.
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- Oxoiminium Ions for N-Demethylation: 1-Oxo-2,2,6,6,-tetramethylpiperidinium Chloride
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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.
- Hunter, Duncan H.,Racok, Julie S.,Rey, Allan W.,Ponce, Yolanda Zea
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- N -Methylation of ortho -substituted aromatic amines with methanol catalyzed by 2-arylbenzo [d] oxazole NHC-Ir(iii) complexes
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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.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhou, Quan,Lin, Yue-Jian,Hou, Xiu-Feng
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- Reduction of hydrazines, azo and azoxy compounds, and amine N-oxides with the NiCl2·2H2O-Li-DTBB (cat.) combination
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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.
- Alonso, Francisco,Radivoy, Gabriel,Yus, Miguel
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- Selective monomethylation of primary amines with simple electrophiles
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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.
- Lebleu, Thomas,Ma, Xiaolu,Maddaluno, Jacques,Legros, Julien
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- Synthesis of N-Methylaniline and N,N-Dimethylaniline with Methanol over Alumina Catalyst
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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.
- Matsuhashi, Hiromi,Arata, Kazushi
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- Surface species formed during aniline methylation on zeolite H-Y investigated by in situ MAS NMR spectroscopy
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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.
- Ivanova, Irina I.,Pomakhina, Elena B.,Rebrov, Alexander I.,Hunger, Michael,Kolyagin, Yuryi G.,Weitkamp, Jens
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- Deactivation of heterogeneous hydrogenation catalysts by alcoholic solvents
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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.
- Singh, Utpal K.,Krska, Shane W.,Sun, Yongkui
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- Scandium ion-enhanced oxidative dimerization and N -demethylation of N, N -dimethylanilines by a non-heme iron(IV)-oxo complex
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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+.
- Park, Jiyun,Morimoto, Yuma,Lee, Yong-Min,You, Youngmin,Nam, Wonwoo,Fukuzumi, Shunichi
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- P(III)/P(V)-Catalyzed Methylamination of Arylboronic Acids and Esters: Reductive C-N Coupling with Nitromethane as a Methylamine Surrogate
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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.
- Li, Gen,Qin, Ziyang,Radosevich, Alexander T.
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- Substituted tetraphenyl porphyrin catalyzed oxidative N-dealkylation of tertiary amine using molecular oxygen
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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.
- Agarwal, Dau. D.,Bhat, Daisy
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- Alkylation of aniline with methanol in the presence of FeCl 3·6H2O in carbon tetrachloride
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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).
- Khusnutdinov,Bayguzina,Aminov
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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
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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.
- Yang, Xianghua,Xi, Chanjuan,Jiang, Yanfeng
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- An Efficient Metal-Free Method for the Denitrosation of Aryl N-Nitrosamines at Room Temperature
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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.).
- Chaudhary, Priyanka,Korde, Rishi,Gupta, Surabhi,Sureshbabu, Popuri,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
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- Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2for consecutiveN-methylation of amines
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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.
- Das, Arpan,Maji, Subir,Mandal, Swadhin K.
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- One-pot photo-reductive N-alkylation of aniline and nitroarene derivatives with primary alcohols over Au-TiO2
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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.
- Stibal, David,Sa, Jacinto,Bokhoven, Jeroen A. Van
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- N-Methylation of amine and nitro compounds with CO2/H2 catalyzed by Pd/CuZrOx under mild reaction conditions
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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
- Cui, Xinjiang,Zhang, Yan,Deng, Youquan,Shi, Feng
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- Photocatalytic degradation of michler's ketone in water by Uv light illumination using TiO2 photocatalyst: Identification of intermediates and the reaction pathway
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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
- Lu, Chung-Shin,Mai, Fu-Der,Wu, Yi-Chin,Yao, I-Chun,Hsu, Peng-Yueh,Chen, Chiing-Chang
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- Distinguishing Rate-Limiting Electron versus H-Atom Transfers in Cu 2(O2)-Mediated Oxidative N-Dealkylations: Application of Inter- versus Intramolecular Kinetic Isotope Effects
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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
- Shearer, Jason,Zhang, Christiana Xin,Hatcher, Lanying Q.,Karlin, Kenneth D.
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- 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
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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.]
- Sun, Pinghui,Lin, Shuyi,Guo, Huimei,Su, Jianhui,Shi, Lei
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- Continuous acid-catalyzed methylations in supercritical carbon dioxide: Comparison of methanol dimethyl ether and dimethyl carbonate as methylating agents
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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.
- Gooden, Peter N.,Bourne, Richard A.,Parrott, Andrew J.,Bevinakatti, Han S.,Irvine, Derek J.,Poliakoff, Martyn
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- Deprotection of sulfonamides using iodotrimethylsilane
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The deprotection of sulfonamides is achieved under neutral conditions by reaction with iodotrimethylsilane in acetonitrile at reflux.
- Sabitha, Gowravaram,Subba Reddy,Abraham, Sunny,Yadav
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- Ruthenium-Catalyzed N-Alkylation and N-Benzylation of Aminoarenes with Alkohols
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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.
- Watanabe, Yoshihisa,Tsuji, Yasushi,Ige, Hitoshi,Ohsugi, Yukihiro,Ohta, Tetsuo
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- Investigation of supported Zn(OAc)2 catalyst and its stability in N-phenyl carbamate synthesis
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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.
- Li, Fang,Li, Wenbo,Li, Jing,Xue, Wei,Wang, Yanji,Zhao, Xinqiang
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- N-(α-Aminoalkyl)benzotriazoles: Novel "Nonstabilized" α-Aminocarbanion Synthons
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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.
- Katritzky, Alan R.,Qi, Ming,Feng, Darning,Nichols, Daniel A.
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- Reductive monoalkylation of aromatic amines via amidine intermediates
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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.
- Zhang, Jianxing,Chang, Hui-Min,Kane, Robert R.
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- Absolute kinetics of aminium radical reactions with olefins in acetonitrile solution
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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.
- Wagner, Brian D.,Ruel, Géraldine,Lusztyk, Janusz
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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
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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.
- Dasgupta, Sohaham,Atta, Sanghamitra,Singh, N. D. Pradeep,Deb, Dibakar,Kassel, W. Scott,Bhattacharjee, Manish
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- Methylation of secondary amines with dialkyl carbonates and hydrosilanes catalysed by iron complexes
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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
- Zheng, Jianxia,Darcel, Christophe,Sortais, Jean-Baptiste
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- Co(acac)3/BMMImCl as a base-free catalyst system for clean syntheses of N,N′-disubstituted ureas from amines and CO2
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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.
- Li, Jian,Guo, Xiaoguang,Wang, Liguo,Ma, Xiangyuan,Zhang, Qinghua,Shi, Feng,Deng, Youquan
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- Zinc oxide surface: a versatile nanoplatform for solvent-free synthesis of diverse isatin derivatives
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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.
- Kothandapani, Jagatheeswaran,Ganesan, Asaithampi,Mani, Ganesh Kumar,Kulandaisamy, Arockia Jayalatha,Rayappan, John Bosco Balaguru,Selva Ganesan, Subramaniapillai
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- A new route to N-aromatic heterocycles from the hydrogenation of diesters in the presence of anilines
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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.
- Shi, Yiping,Kamer, Paul C. J.,Cole-Hamilton, David J.,Harvie, Michelle,Baxter, Emma F.,Lim, Kate J. C.,Pogorzelec, Peter
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- Mono-N-methylation of primary amines with alkyl methyl carbonates over Y faujasites. 2. Kinetics and selectivity
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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).
- Selva, Maurizio,Tundo, Pietro,Perosa, Alvise
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- Electrochemical hydrodefluorination of fluoroaromatic compounds
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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.
- Wu, Wen-Bin,Li, Mei-Li,Huang, Jing-Mei
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- Green and chemo selective amine methylation using methanol by an organometallic ruthenium complex
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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.
- Abbasi, Alireza,Dindar, Sara,Nemati Kharat, Ali
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- Electronically tuneable orthometalated RuII–NHC complexes as efficient catalysts for C–C and C–N bond formations via borrowing hydrogen strategy
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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.
- Illam, Praseetha Mathoor,Rit, Arnab
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- Copper(i)-catalysed intramolecular hydroarylation-redox cross-dehydrogenative coupling ofN-propargylanilines with phosphites
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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.
- Li, Guangzhe,Yu, Guo,Wang, Chengdong,Morita, Taiki,Zhang, Xuhai,Nakamura, Hiroyuki
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p. 113 - 116
(2021/12/29)
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- Additive-free selective methylation of secondary amines with formic acid over a Pd/In2O3 catalyst
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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.
- Benaissa, Idir,Cantat, Thibault,Genre, Caroline,Godou, Timothé,Pinault, Mathieu
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- K2S2O8-induced site-selective phenoxazination/phenothiazination of electron-rich anilines
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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.
- Lei, Aiwen,Wang, Pengjie,Wang, Shengchun,Wang, Xiaoyu,Yi, Hong,Zhang, He,Zhang, Heng
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supporting information
p. 147 - 151
(2022/01/19)
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- Electrocatalytic Oxidative Hydrofunctionalization Reactions of Alkenes via Co(II/III/IV) Cycle
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Here we disclose a general Co(II/III/IV) electrocatalytic platform for alkene functionalization. Driven by electricity, a set of the oxidative hydrofunctionalization reactions via hydrogen atom transfer were demonstrated without the need for stochiometric chemical oxidants. The scope of the reactions encompasses hydroalkoxylation, hydroacyloxylation, hydroarylation, semipinacol rearrangement, and deallylation. Mechanistic studies and stereochemical evidence support an ECEC process involving an electrochemically generated organocobalt(IV) intermediate. This work presents an example of reactivity space expansion in electrocatalysis in the VB12-system by going beyond the common oxidation states of Co(I/II/III).
- Yang, Fan,Nie, Yi-Chen,Liu, Han-Yuan,Zhang, Lei,Mo, Fanyang,Zhu, Rong
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p. 2132 - 2137
(2022/02/10)
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- Unreactive C-N Bond Activation of Anilines via Photoinduced Aerobic Borylation
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Unreactive C-N bond activation of anilines was achieved by photoinduced aerobic borylation. A diverse range of tertiary and secondary anilines were converted to aryl boronate esters in moderate to good yields with wide functional group tolerance under simple and ambient photochemical conditions. This transformation achieved the direct and facile C-N bond activation of unreactive anilines, providing a convenient and practical route transforming widely available anilines into useful aryl boronate esters.
- Ji, Shuohan,Luo, Lu,Qin, Shengxiang,Yin, Chunyu,Zhang, Hua
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supporting information
(2021/12/27)
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- Nanosized CdS as a Reusable Photocatalyst: The Study of Different Reaction Pathways between Tertiary Amines and Aryl Sulfonyl Chlorides through Visible-Light-Induced N-Dealkylation and C-H Activation Processes
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It has been found that the final products of the reaction of sulfonyl chlorides and tertiary amines in the presence of cadmium sulfide nanoparticles under visible light irradiation are highly dependent on the applied reaction conditions. Interestingly, with the change of a reaction condition, different pathways were conducted (visible-light-induced N-dealkylation or sp3 and sp2 C-H activation) that lead to different products such as secondary amines and various sulfonyl compounds. Remarkably, all of these reactions were performed under visible light irradiation and an air atmosphere without any additive or oxidant in benign solvents or under solvent-free conditions. During this study, the CdS nanoparticles as affordable, heterogeneous, and recyclable photocatalysts were designed, successfully synthesized, and fully characterized and applied for these protocols. During these studies, intermediates resulting from the oxidation of tertiary amines are trapped during the photoinduced electron transfer (PET) process. The reaction was carried out efficiently with a variety of substrates to give the corresponding products at relatively short times in good to excellent yields in parallel with the use of the visible light irradiation as a renewable energy source. Most of these processes are novel or are superior in terms of cost-effectiveness, safety, and simplicity to published reports.
- Firoozi, Somayeh,Hosseini-Sarvari, Mona
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p. 2117 - 2134
(2021/02/05)
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- Catalyst-free photoinduced selective oxidative C(sp3)-C(sp3) bond cleavage in arylamines
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Due to the directional nature of sp3-hybridized orbitals and the absence of π-orbitals, the oxidative cleavage of the kinetically and thermodynamically stable C(sp3)-C(sp3) bond is extremely difficult and remains scarcely explored. In this work, under the double argument of quantum mechanics (QM) computations and meticulous experiments on our well-designed C-C single bond cleavage mechanism, we discovered a means of photoinduced selective oxidative C(sp3)-C(sp3) bond cleavage in arylamines, easily achieved by simple visible light irradiation using O2as a benign oxidant under very mild conditions. The utility of our methodology was demonstrated by the C(sp3)-C(sp3) bond cleavage in morpholine/piperazine arylamines with excellent functional group tolerance. Importantly, our methodology is noteworthy, not only in that it does not require any catalysts, but also in that it provides valuable possibilities for the scalable functionalization of clinical drugs and natural products.
- Duan, Wentao,Lian, Qi,Wang, Songping,Wei, Wentao,Zhou, Jingwei
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supporting information
p. 3261 - 3267
(2021/05/21)
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- Copper-Catalyzed Cascade N-Dealkylation/N-Methyl Oxidation of Aromatic Amines by Using TEMPO and Oxygen as Oxidants
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A novel tandem N-dealkylation and N-methyl aerobic oxidation of tertiary aromatic amines to N-arylformamides using copper and TEMPO has been developed. This methodology suggested an alternative synthetic route from N-methylarylamines to N-arylformamides.
- Li, Dianjun,Wang, Shihaozhi,Yang, Jiale,Yang, Jinhui
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supporting information
p. 6768 - 6772
(2021/12/31)
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- A nonheme peroxo-diiron(iii) complex exhibiting both nucleophilic and electrophilic oxidation of organic substrates
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The complex [FeIII2(μ-O2)(L3)4(S)2]4+(L3= 2-(4-thiazolyl)benzimidazole, S = solvent) forms upon reaction of [FeII(L3)2] with H2O2and is a functional model of peroxo-diiron intermediates invoked during the catalytic cycle of oxidoreductases. The spectroscopic properties of the complex are in line with those of complexes formed with N-donor ligands. [FeIII2(μ-O2)(L3)4(S)2]4+shows both nucleophilic (aldehydes) and electrophilic (phenol,N,N-dimethylanilines) oxidative reactivity and unusually also electron transfer oxidation.
- Browne, Wesley R.,Giorgi, Michel,Kaizer, József,T?r?k, Patrik,Unjaroen, Duenpen,Viktória Csendes, Flóra
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supporting information
p. 7181 - 7185
(2021/06/11)
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- Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
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The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
- Liu, Xin,Werner, Thomas
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p. 10590 - 10597
(2021/08/20)
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- Selective N-formylation of amines catalysed by Ag NPs festooned over amine functionalized SBA-15 utilizing CO2 as C1 source
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N-formylation of amines using CO2 as C1 source has been an uphill transformation in the catalysis research as it involves the utilization of abundant thermodyanamically stable and kinetically inert CO2 to form the N-formylated products, which are potential intermediates for the synthesis of valuable chemicals. Previously various noble as well as non-noble metal nanoparticles have been employed for N-formylation of amines. However, herein for the first time we explored N-formylation reaction under lenient conditions utilizing silver nanoparticles, which are decorated over amine functionalized periodically ordered 2D-hexagonal SBA-15 material, serving as a robust heterogeneous catalyst. The AgNPs@SBA-15-NH2 has been intensively characterized by powder XRD, Brunauer-Emmett-Teller (BET), FEG-TEM, SEM, XPS, TGA, CO2-TPD, FTIR and UV–vis spectroscopic analyses. This supported AgNPs material showed remarkable catalytic activity for N-formylation over a wide range of amines under 0.5 MPa CO2 pressure and at mild temperature (35 °C) conditions. In addition, this AgNPs@SBA-15-NH2 material exhibited high chemical stability and reusability, suggesting its promising future in the CO2 fixation reactions.
- Azad, Shiyana,Bal, Rajaram,Bhattacharjee, Sudip,Bhaumik, Asim,Chongdar, Sayantan
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- Novel hybrid conjugates with dual estrogen receptor α degradation and histone deacetylase inhibitory activities for breast cancer therapy
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Hormone therapy targeting estrogen receptors is widely used clinically for the treatment of breast cancer, such as tamoxifen, but most of them are partial agonists, which can cause serious side effects after long-term use. The use of selective estrogen receptor down-regulators (SERDs) may be an effective alternative to breast cancer therapy by directly degrading ERα protein to shut down ERα signaling. However, the solely clinically used SERD fulvestrant, is low orally bioavailable and requires intravenous injection, which severely limits its clinical application. On the other hand, double- or multi-target conjugates, which are able to synergize antitumor activity by different pathways, thus may enhance therapeutic effect in comparison with single targeted therapy. In this study, we designed and synthesized a series of novel dual-functional conjugates targeting both ERα degradation and histone deacetylase inhibiton by combining a privileged SERD skeleton 7-oxabicyclo[2.2.1]heptane sulfonamide (OBHSA) with a histone deacetylase inhibitor side chain. We found that substituents on both the sulfonamide nitrogen and phenyl group of OBHSA unit had significant effect on biological activities. Among them, conjugate 16i with N-methyl and naphthyl groups exhibited potent antiproliferative activity against MCF-7 cells, and excellent ERα degradation activity and HDACs inhibitory ability. A further molecular docking study indicated the interaction patterns of these conjugates with ERα, which may provide guidance to design novel SERDs or PROTAC-like SERDs for breast cancer therapy.
- Zhao, Chenxi,Tang, Chu,Li, Changhao,Ning, Wentao,Hu, Zhiye,Xin, Lilan,Zhou, Hai-Bing,Huang, Jian
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- Method for realizing N-alkylation by using alcohols as carbon source under photocatalysis
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The invention discloses a method for realizing N-alkylation by using alcohols as a carbon source under photocatalysis, and belongs to the technical field of catalytic synthesis. Alcohol, a substrate raw material and a catalyst are placed in a reaction device, ultraviolet and/or visible light irradiation is carried out in an inert atmosphere, after the irradiation is finished, solid-liquid separation is carried out to remove the catalyst, and an N-alkylation product can be obtained through extraction, distillation and purification, wherein the substrate raw material comprises any one of an amine compound, an aromatic nitro compound or an aromatic nitrile compound, the alcohol comprises any one or more of soluble primary alcohols, and the catalyst is metal oxide/titanium dioxide or metal sulfide/titanium dioxide. The method is simple and easy to operate, can be used for efficient photocatalysis one-pot multi-step hydrogenation N-alkylation reaction, and is mild in reaction condition, high in chemical selectivity of N-alkylamine, good in catalyst stability and easy to recycle.
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Paragraph 0048-0099
(2021/03/13)
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- Additive-freeN-methylation of amines with methanol over supported iridium catalyst
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An efficient and versatile zinc oxide-supported iridium (Ir/ZnO) catalyst was developed to catalyze the additive-freeN-methylation of amines with methanol. Mechanistic studies suggested that the high catalytic reactivity is rooted in the small sizes (1.4 nm) of Ir nanoparticles and the high ratio (93%) of oxidized iridium species (IrOx, Ir3+and Ir4+) on the catalyst. Moreover, the delicate cooperation between the IrOxand ZnO support also promoted its high reactivity. The selectivity of this catalyticN-methylation was controllable between dimethylation and monomethylation by carefully tuning the catalyst loading and reaction solvent. Specifically, neat methanol with high catalyst loading (2 mol% Ir) favored the formation ofN,N-dimethylated amine, while the mesitylene/methanol mixture with low catalyst loading (0.5 mol% Ir) was prone to producing mono-N-methylated amines. An environmentally benign continuous flow system with a recycled mode was also developed for the efficient production ofN-methylated amines. With optimal flow rates and amine concentrations, a variety ofN-methylamines were produced with good to excellent yields in this Ir/ZnO-based flow system, providing a starting point for the clean and efficient production ofN-methylamines with this cost-effective chemical process.
- Liu, Xiang,Loh, Teck-Peng,Qiang, Wenwen,Wang, Jing,Ye, Sen,Zhu, Longfei
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p. 3364 - 3375
(2021/06/06)
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- Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source
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Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp3)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.
- Biswas, Nandita,Srimani, Dipankar
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supporting information
p. 10544 - 10554
(2021/07/31)
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- N-Methylation of Amines with Methanol in the Presence of Carbonate Salt Catalyzed by a Metal-Ligand Bifunctional Ruthenium Catalyst [(p-cymene)Ru(2,2′-bpyO)(H2O)]
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A ruthenium complex [(p-cymene)Ru(2,2′-bpyO)(H2O)] was found to be a general and efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate salt. Moreover, a series of sensitive substituents, such as nitro, ester, cyano, and vinyl groups, were tolerated under present conditions. It was confirmed that OH units in the ligand are crucial for the catalytic activity. Notably, this research exhibited the potential of metal-ligand bifunctional ruthenium catalysts for the hydrogen autotransfer process.
- Liu, Peng,Tung, Nguyen Thanh,Xu, Xiangchao,Yang, Jiazhi,Li, Feng
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p. 2621 - 2631
(2021/02/27)
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- Recyclable covalent triazine framework-supported iridium catalyst for the N-methylation of amines with methanol in the presence of carbonate
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An iridium complex Cp*Ir@CTF, which is synthesized by the coordinative immobilization of [Cp*IrCl2]2 on a functionalized covalent triazine framework (CTF), was found to be a general and highly efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate. Under environmentally benign conditions, a variety of desirable products were obtained in high yields with complete selectivities and functional group friendliness. Furthermore, the synthesized catalyst could be recycled by simple filtration without obvious loss of catalytic activity after sixth cycle. Notably, this research exhibited the potential of covalent triazine framework-supported transition metal catalysts for hydrogen autotransfer process.
- Liu, Peng,Yang, Jiazhi,Ai, Yao,Hao, Shushu,Chen, Xiaozhong,Li, Feng
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p. 281 - 290
(2021/03/26)
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- Simple RuCl3-catalyzed N-Methylation of Amines and Transfer Hydrogenation of Nitroarenes using Methanol
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Methanol is a potential hydrogen source and C1 synthon, which finds interesting applications in both chemical synthesis and energy technologies. The effective utilization of this simple alcohol in organic synthesis is of central importance and attracts scientific interest. Herein, we report a clean and cost-competitive method with the use of methanol as both C1 synthon and H2 source for selective N-methylation of amines by employing relatively cheap RuCl3.xH2O as a ligand-free catalyst. This readily available catalyst tolerates various amines comprising electron-deficient and electron-donating groups and allows them to transform into corresponding N-methylated products in moderate to excellent yields. In addition, few marketed pharmaceutical agents (e. g., venlafaxine and imipramine) were also successfully synthesized via late-stage functionalization from readily available feedstock chemicals, highlighting synthetic value of this advanced N-methylation reaction. Using this platform, we also attempted tandem reactions with selected nitroarenes to convert them into corresponding N-methylated amines using MeOH under H2-free conditions including transfer hydrogenation of nitroarenes-to-anilines and prepared drug molecules (e. g., benzocaine and butamben) as well as key pharmaceutical intermediates. We further enable one-shot selective and green syntheses of 1-methylbenzimidazole using ortho-phenylenediamine (OPDA) and methanol as coupling partners.
- Sarki, Naina,Goyal, Vishakha,Tyagi, Nitin Kumar,Puttaswamy,Narani, Anand,Ray, Anjan,Natte, Kishore
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p. 1722 - 1729
(2021/04/19)
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- Ruthenium(ii) complexes with N-heterocyclic carbene-phosphine ligands for theN-alkylation of amines with alcohols
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Metal hydride complexes are key intermediates forN-alkylation of amines with alcohols by the borrowing hydrogen/hydrogen autotransfer (BH/HA) strategy. Reactivity tuning of metal hydride complexes could adjust the dehydrogenation of alcohols and the hydrogenation of imines. Herein we report ruthenium(ii) complexes with hetero-bidentate N-heterocyclic carbene (NHC)-phosphine ligands, which realize smart pathway selection in theN-alkylated reactionviareactivity tuning of [Ru-H] species by hetero-bidentate ligands. In particular, complex6cbwith a phenyl wingtip group and BArF?counter anion, is shown to be one of the most efficient pre-catalysts for this transformation (temperature is as low as 70 °C, neat conditions and catalyst loading is as low as 0.25 mol%). A large variety of (hetero)aromatic amines and primary alcohols were efficiently converted into mono-N-alkylated amines in good to excellent isolated yields. Notably, aliphatic amines, challenging methanol and diamines could also be transformed into the desired products. Detailed control experiments and density functional theory (DFT) calculations provide insights to understand the mechanism and the smart pathway selectionvia[Ru-H] species in this process.
- Huang, Ming,Li, Yinwu,Lan, Xiao-Bing,Liu, Jiahao,Zhao, Cunyuan,Liu, Yan,Ke, Zhuofeng
-
supporting information
p. 3451 - 3461
(2021/05/03)
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- Efficient methylation of anilines with methanol catalysed by cyclometalated ruthenium complexes
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Cyclometalated ruthenium complexes4-10allow the effective methylation of anilines with methanol to selectively giveN-methylanilines. This hydrogen autotransfer procedure proceeds under mild conditions (60 °C) in a practical manner (NaOH as base). Mechanistic investigations suggest an active homogenous ruthenium complex and β-hydride elimination of methanol as the rate determining step.
- Piehl, Patrick,Amuso, Roberta,Spannenberg, Anke,Gabriele, Bartolo,Neumann, Helfried,Beller, Matthias
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p. 2512 - 2517
(2021/04/22)
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- Biobased Spiroimides from Itaconic Acid and Formamides: Molecular Targets for a Novel Synthetic Application of Renewable Chemicals
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Spiroimides exhibit a wide range of biological activities, such as anticonvulsant, antiarrhythmic, and antihyperglycemic activities. Herein, a novel synthetic application of renewable chemicals, itaconic acid and formamides, is described. Proper exploitation of the reactivity of itaconic acid and formamide allows for the development of an efficient synthetic approach for the production of several new biobased spiroimides, spiro[dihydroquinolin-2-one-succinimides] and spiro[indolin-2-one-glutarimides], in excellent overall yields (up to 98%).
- Hornink, Milene Macedo,Lopes, Alice Uva,Andrade, Leandro Helgueira
-
supporting information
p. 296 - 308
(2020/11/09)
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- CO2-tuned highly selective reduction of formamides to the corresponding methylamines
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We herein describe an efficient, CO2-tuned and highly selective C-O bond cleavage of N-methylated formanilides. With easy-to-handle and commercially available NaBH4 as the reductant, a variety of formanilides could be turned into the desired tertiary amines in moderate to excellent yields. The role of CO2 has been investigated in detail, and the mechanism is proposed on the basis of experiments.
- Chao, Jianbin,Guo, Zhiqiang,Pang, Tengfei,Wei, Xuehong,Xi, Chanjuan,Yan, Leilei
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supporting information
p. 7534 - 7538
(2021/10/12)
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- Minimization of Back-Electron Transfer Enables the Elusive sp3 C?H Functionalization of Secondary Anilines
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Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N-Dialkyl-derivatives enable radical generation α to the N-atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back-electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence of an exogenous alkylamine. This approach synergistically aids aniline SET oxidation and then accelerates the following deprotonation. In this way, the generation of α-anilinoalkyl radicals is now possible and these species can be used in a general sense to achieve divergent sp3 C?H functionalization.
- Zhao, Huaibo,Leonori, Daniele
-
supporting information
p. 7669 - 7674
(2021/03/08)
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- Electrochemical Reductive N-Methylation with CO2Enabled by a Molecular Catalyst
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The development of benign methylation reactions utilizing CO2 as a one-carbon building block would enable a more sustainable chemical industry. Electrochemical CO2 reduction has been extensively studied, but its application for reductive methylation reactions remains out of the scope of current electrocatalysis. Here, we report the first electrochemical reductive N-methylation reaction with CO2 and demonstrate its compatibility with amines, hydroxylamines, and hydrazine. Catalyzed by cobalt phthalocyanine molecules supported on carbon nanotubes, the N-methylation reaction proceeds in aqueous media via the chemical condensation of an electrophilic carbon intermediate, proposed to be adsorbed or near-electrode formaldehyde formed from the four-electron reduction of CO2, with nucleophilic nitrogenous reactants and subsequent reduction. By comparing various amines, we discover that the nucleophilicity of the amine reactant is a descriptor for the C-N coupling efficacy. We extend the scope of the reaction to be compatible with cheap and abundant nitro-compounds by developing a cascade reduction process in which CO2 and nitro-compounds are reduced concurrently to yield N-methylamines with high monomethylation selectivity via the overall transfer of 12 electrons and 12 protons.
- Rooney, Conor L.,Wu, Yueshen,Tao, Zixu,Wang, Hailiang
-
supporting information
p. 19983 - 19991
(2021/12/01)
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- Synthesis of N-Alkyl Anilines from Arenes via Iron-Promoted Aromatic C-H Amination
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We report both an intermolecular C-H amination of arenes to access N-methylanilines and an intramolecular variant for the synthesis of tetrahydroquinolines. A newly developed, highly electrophilic aminating reagent was key for the direct synthesis of unprotected N-methylanilines from simple arenes. The reactions display a broad functional group tolerance and employ catalytic amounts of a benign iron salt under mild reaction conditions.
- Falk, Eric,Gasser, Valentina C. M.,Morandi, Bill
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supporting information
p. 1422 - 1426
(2021/03/08)
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- Method for protecting sulfonyl of deamination amine
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The invention discloses a method for removing sulfenyl protection of amine. The method comprises the following steps: dissolving N - sulfonyl-protected amine and a base in a reaction solvent, then adding diphenylphosphine to uniformly mix and maintain 90 °C. When TCL detection reaction is complete, a recrystallization method or an extraction separation method is adopted to obtain the target product. The method disclosed by the invention adopts diphenylphosphine as an extraction reagent, is good in reaction activity, high in selectivity and wide in application range, and can replace the use of a hazardous reagent under the basic heating condition. Prodrug research and development and industrial production are of great significance.
- -
-
Paragraph 0045-0047
(2021/11/03)
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- Sulfated polyborate: A dual catalyst for the reductive amination of aldehydes and ketones by NaBH4
-
An efficient, quick, and environment-friendly one-pot reductive amination of aldehydes or ketones was developed. In ethanol at 70 °C, a imination catalyzed by sulfated polyborate and further reduced by sodium borohydride yields various amines. The present method has many significant benefits, including a shorter reaction time, excellent yields, and a hassle-free, straightforward experimental process. The reaction has a wide range of applications due to its flexibility, including secondary amine for reductive amination.
- Ganwir, Prerna,Chaturbhuj, Ganesh
-
-
- Photoinduced Hydroarylation and Cyclization of Alkenes with Luminescent Platinum(II) Complexes
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Photoinduced hydroarylation of alkenes is an appealing synthetic strategy for arene functionalization. Herein, we demonstrated that aryl radicals generated from electron-deficient aryl chlorides/bromides could be trapped by an array of terminal/internal aryl alkenes in the presence of [Pt(O^N^C^N)] under visible-light (410 nm) irradiation, affording anti-Markovnikov hydroarylated compounds in up to 95 % yield. Besides, a protocol for [Pt(O^N^C^N)]-catalyzed intramolecular photocyclization of acrylanilides to give structurally diverse 3,4-dihydroquinolinones has been developed.
- Cheng, Hanchao,Lam, Tsz-Lung,Liu, Yungen,Tang, Zhou,Che, Chi-Ming
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supporting information
p. 1383 - 1389
(2020/11/30)
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- Self-Immolative System for Disclosure of Reactive Electrophilic Alkylating Agents: Understanding the Role of the Reporter Group
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The development of stable, efficient chemoselective self-immolative systems, for use in applications such as sensors, requires the optimization of the reactivity and degradation characteristics of the self-immolative unit. In this paper, we describe the effect that the structure of the reporter group has upon the self-immolative efficacy of a prototype system designed for the disclosure of electrophilic alkylating agents. The amine of the reporter group (a nitroaniline unit) was a constituent part of a carbamate that functioned as the self-immolative unit. The number and position of substituents on the nitroaniline unit were found to play a key role in the rate of self-immolative degradation and release of the reporter group. The position of the nitro substituent (meta- vs para-) and the methyl groups in the ortho-position relative to the carbamate exhibited an influence on the rate of elimination and stability of the self-immolative system. The ortho-methyl substituents imparted a twist on the N-C (aromatic) bond leading to increased resonance of the amine nitrogen's lone pair into the carbonyl moiety and a decrease of the leaving character of the carbamate group; concomitantly, this may also make it a less electron-withdrawing group and lead to less acidification of the eliminated β-hydrogen.
- Chippindale, Ann M.,Gavriel, Alexander G.,Hayes, Wayne,Khurana, Gurjeet S.,Leroux, Flavien,Lewis, Viliyana G.,Russell, Andrew T.,Sambrook, Mark R.
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p. 10263 - 10279
(2021/08/16)
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- Visible light-induced N-methyl activation of unsymmetric tertiary amines
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In the presence of methylene group, selective N-methyl activation of tertiary amines has been accomplished with the aid of visible light using organic photocatalyst under air. This protocol explores numerous aliphatic and aromatic substituted tetra-hydroquinoline analogues from various tertiary amines and maleimides. Furthermore, this approach was applied to activate the methyl group of N-methyl carbazole to generate the biologically active molecule.
- Perumal, Gopi,Kandasamy, Mohanraj,Ganesan, Balaji,Govindan, Karthick,Sathya, Harsha,Hung, Min-Yuan,Chandru Senadi, Gopal,Wu, Ya-Ching,Lin, Wei-Yu
-
supporting information
(2021/01/09)
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- Aza-Matteson Reactions via Controlled Mono-and Double-Methylene Insertions into Nitrogen-Boron Bonds
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Boron-homologation reactions represent an efficient and programmable approach to prepare alkylboronates, which are valuable and versatile synthetic intermediates. The typical boron-homologation reaction, also known as the Matteson reaction, involves formal carbenoid insertions into C-B bonds. Here we report the development of aza-Matteson reactions via carbenoid insertions into the N-B bonds of aminoboranes. By changing the leaving groups of the carbenoids and altering Lewis acid activators, selective mono- and double-methylene insertions can be realized to access various α- and β-boron-substituted tertiary amines, respectively, from common secondary amines. The derivatization of complex amine-containing bioactive molecules, diverse functionalization of the boronate products, and sequential insertions of different carbenoids have also been achieved.
- Xie, Qiqiang,Dong, Guangbin
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p. 14422 - 14427
(2021/09/29)
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- Visible light-induced oxidative: N -dealkylation of alkylamines by a luminescent osmium(vi) nitrido complex
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N-Dealkylation of amines by metal oxo intermediates (MO) is related to drug detoxification and DNA repair in biological systems. In this study, we report the first example of N-dealkylation of various alkylamines by a luminescent osmium(vi) nitrido complex induced by visible light. This journal is
- Cheng, Shun-Cheung,Jin, Xin-Xin,Ko, Chi-Chiu,Lau, Kai-Chung,Lau, Tai-Chu,Luo, Li-Juan,Man, Wai-Lun,Pan, Yi,Peng, Min,Xiang, Jing,Yiu, Shek-Man
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p. 14494 - 14498
(2021/11/17)
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- Photocatalytic synthesis of unsymmetrical thiourea derivativesviavisible-light irradiation using nitrogen-doped ZnO nanorods
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An efficient, mild, and environmentally friendly route has been developed for the synthesis of unsymmetrical thiourea derivatives in moderate yields by the reaction of tertiary aromatic and aliphatic amines with phenyl-iso-thiocyanate in the presence of N-ZnO as a photocatalyst under visible-light irradiation. This method provides a pathway to activate the tertiary aromatic and aliphatic aminesviaC-N bond cleavage.
- Koohgard, Mehdi,Sarvestani, Abdollah Masoudi,Hosseini-Sarvari, Mona
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p. 14505 - 14512
(2020/09/21)
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- SELF-IMMOLATIVE SYSTEMS
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The present invention is concerned with self-immolative recognition and/or responsive systems for electrophilic compounds, especially alkylating agents, which systems may comprise disclosure or detection of the alkylating agent. The present invention is especially concerned with non-protic triggered self-immolative systems, molecules, and methods, and in particular for detection of non- protic electrophilic agents, and especially alkylating agents, for example alkyl or benzylic halides, which may be found in pesticides or fumigants, or chemical warfare agents.
- -
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Page/Page column 22; 23
(2020/05/28)
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- Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
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p. 3514 - 3523
(2020/10/09)
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- Manganese-Catalyzed One-Pot Conversion of Nitroarenes into N-Methylarylamines Using Methanol
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A manganese-catalyzed one-pot conversion of nitroarenes into N-methylarylamines has been developed. This transfer hydrogenation method employs a well-defined bench stable Mn PN3P pincer precatalyst in combination with methanol as both the reductant and the C1 source. A selection of commercially available nitroarenes was converted into N-methylarylamines in synthetically useful yields.
- Mast, Nicolas,Morrill, Louis C.,Reed-Berendt, Benjamin G.
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supporting information
(2020/03/03)
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- N-Methylation of Amines with Methanol in Aqueous Solution Catalyzed by a Water-Soluble Metal-Ligand Bifunctional Dinuclear Iridium Catalyst
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The N-methylation of amines with methanol in aqueous solution was proposed and accomplished by using a water-soluble metal-ligand bifunctional dinuclear iridium catalyst. In the presence of [(Cp*IrCl)2(thbpym)][Cl]2 (1 mol %), a range of desirable products were obtained in high yields under environmentally benign conditions. Notably, this research exhibited the potential of transition metal-catalyzed activation of methanol as a C1 source for the construction of the C-N bond in aqueous solution.
- Han, Xingyou,Li, Feng,Liu, Peng,Meng, Chong,Tung, Nguyen Thanh
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p. 5815 - 5824
(2020/05/26)
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- Ruthenium(II) Complexes of Heteroditopic N-Heterocyclic Carbene Ligands: Efficient Catalysts for C-N Bond Formation via a Hydrogen-Borrowing Strategy under Solvent-Free Conditions
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Both imidazol-2-ylidene (ImNHC) and 1,2,3-triazol-5-ylidene (tzNHC) have evolved to be elite groups of N-heterocyclic carbene (NHC) ligands for homogeneous catalysis. To develop efficient ruthenium(II)-based catalysts incorporating these ligands for C-N bond-forming reactions via hydrogen-borrowing methodology, we utilized chelating ligands integrated with ImNHC and mesoionic tzNHC donors connected via a CH2 spacer with a diverse triazole backbone. The synthesized ruthenium(II) complexes 3 are found to be highly efficient for C-N bond formation across a wide range of primary amine and alcohol substrates under solvent-free conditions, and among all of the complexes studied here, catalyst 3a with a mesityl substituent displayed maximum activity. To our delight, catalyst 3a is also effective for the selective mono-N-methylation of various anilines utilizing methanol as a coupling partner, known to be relatively more difficult than other alcohols. Furthermore, complex 3a also delivers various substituted quinolines successfully via the reaction of 2-aminobenzyl alcohol with several secondary alcohols. Importantly, catalyst 3a exhibited the highest activity among the reported ruthenium(II) complexes for both the N-benzylation of aniline [achieving a turnover number (TON) of 50000] and the realization of quinoline 8a by reacting 2-aminobenzyl alcohol with 2-phenylethanol (attaining a TON of 30000).
- Donthireddy,Mathoor Illam, Praseetha,Rit, Arnab
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supporting information
p. 1835 - 1847
(2020/01/31)
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- CATIONIC RUTHENIUM COMPLEX, AND PRODUCTION METHOD THEREFOR AND USE THEREOF
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The present invention provides a novel cationic ruthenium complex which is easy to produce and handle and can be procured at a relatively low cost and a production method for the ruthenium complex, a method for producing an alcohol or the like using the ruthenium complex as a catalyst, a method for producing a carbonyl compound using the ruthenium complex as a catalyst, and a method for producing a N-alkylamine compound using the ruthenium complex as a catalyst. The present invention pertains to a ruthenium complex represented by general formula (1): [RuX(CO)2(PNP)]Y (wherein, X represents a monovalent anionic monodentate ligand, Y represents a counter anion, PNP represents a tridentate ligand, and CO represents carbon monoxide), a production method for the ruthenium complex, a catalyst containing the ruthenium complex, and a production method for various organic compounds using the catalyst.
- -
-
Paragraph 0235-0236
(2020/04/24)
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- Comparison of the effect of N-methyl and N-aryl groups on the hydrolytic stability and electronic properties of betalain dyes
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Betalains are antioxidant secondary metabolites that emerged as safe color additives for food and cosmetics, fluorescent dyes, and redox mediators. Herein, we describe the semisynthesis of N-methyl phenylbetalain (mepBeets) and N-aryl phenylbetalain (dipBeets) dyes and compare the effect of the structure on their hydrolytic stability and electronic properties. Eight model compounds were semisynthesized by coupling betalamic acid with either N-methyl anilines or N-aryl anilines in ethyl acetate using p-toluenesulfonic acid as catalyst. The presence of electron-withdrawing substituents in the aryl moiety of mepBeets and dipBeets results in faster hydrolysis, lower anodic potentials and increased fluorescence quantum yields compared to the corresponding unsubstituted parent compounds. The results are rationalized by considering the charge distribution in the 1,7-diazaheptamethinium chromophore and are useful for the development of new hydrolytically stable betalain dyes with tunable redox and optical properties.
- Bastos, Erick Leite,Dochev, Stefan,Esteves, Larissa Cerrato,Mattioli, Renan Rodini,Pioli, Renan Moraes
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-
- Photon-initiated heterogeneous redox couples for methylation of anilines under mild conditions
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Methylation of anilines has drawn a lot of attention due to their valuable applications and directly using methanol as a methylation reagent is of great advantage. Photon-initiated heterogeneous catalysis of this methylation process meets the requirements of green chemistry. Herein we show that balanced redox zones within carbon nitride supported Pd nanoparticles boost the selectivity of methylation of anilines under mild conditions.
- Zhang, Bing,Gao, Hua,Wang, Wei
-
supporting information
p. 4433 - 4437
(2020/08/10)
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- Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
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Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
- ?tv?s, Sándor B.,Kappe, C. Oliver
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p. 1800 - 1807
(2020/02/27)
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- ZINC-IMIDAZOLE COMPLEX MIXED CATALYST AND METHOD FOR PRODUCING METHYL N-PHENYL CARBAMATE USING THE SAME
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Disclosed is a zinc-imidazole complex mixed catalyst. Also disclosed are a method for preparing the zinc-imidazole complex mixed catalyst and a method for producing a methyl N-phenyl carbamate in high yield with high selectivity in the presence of the catalyst. The zinc-imidazole complex mixed catalyst can be reused due to its high reaction stability. In addition, the use of the zinc-imidazole complex mixed catalyst leads to a marked improvement in the production yield of a methyl N-phenyl carbamate with high selectivity.
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-
Paragraph 0077-0078; 0089-0090
(2020/03/09)
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- Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor
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Novel approaches for N- and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KOtBu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KOtBu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.
- Heredia, Micaela D.,Guerra, Walter D.,Barolo, Silvia M.,Fornasier, Santiago J.,Rossi, Roberto A.,Budén, Mariá E.
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supporting information
p. 13481 - 13494
(2020/12/15)
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- EffectiveN-methylation of nitroarenes with methanol catalyzed by a functionalized NHC-based iridium catalyst: a green approach toN-methyl amines
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Compound [IrBr(CO)2(κC-tBuImCH2PyCH2OMe)] featuring a flexible pyridine/OMe functionalized NHC ligand κ1C coordinated efficiently catalyzes the selectiveN-monomethylation of nitroarenes using methanol as both the reducing agent and the C1 source. A range of functionalized nitroarenes including heterocyclic or sterically hindered derivatives have been efficiently converted to the correspondingN-monomethyl amines in good yields at low catalyst loadings using sub-stoichiometric amounts of Cs2CO3as a base. Mechanistic investigations support a borrowing-hydrogen mechanism in which methanol acts as the hydrogen source and methylating agent. Further, the hydrogen transfer reduction of nitrobenzene to aniline under optimized reaction conditions should proceed through a direct mechanism involving nitrosobenzene andN-phenylhydroxylamine intermediates.
- González-Lainez, Miguel,Jiménez, M. Victoria,Passarelli, Vincenzo,Pérez-Torrente, Jesús J.
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p. 3458 - 3467
(2020/06/17)
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- Synthesis of: N -methylated amines from acyl azides using methanol
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The transformation of acyl azide derivatives into N-methylamines was developed using methanol as the C1 source via the one-pot Curtius rearrangement and borrowing hydrogen methodology. Following this protocol, various functionalised N-methylated amines were synthesized using the (NNN)Ru(ii) complex from carboxylic acids via an acyl azide intermediate. Several kinetic studies and DFT calculations were carried out to support the mechanism and also to determine the role of the Ru(ii) complex and base in this transformation.
- Chakrabarti, Kaushik,Dutta, Kuheli,Kundu, Sabuj
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p. 5891 - 5896
(2020/08/21)
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