- Synthesis of 4-functionalized indoles via benzyne cyclization of N-(2- lithioallyl)-2-fluoroanilines
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Treatment of N-(2-bromoallyl)-N-methyl-2-fluoroaniline with tert- butyllithium affords 1,3-dimethyl-4-lithioindole, via intramolecular addition to a tethered benzyne intermediate. Further reaction with electrophiles leads to 4-functionalized 3-methylindol
- Barluenga, Jose,Fananas, Francisco J.,Sanz, Roberto,Fernandez, Yolanda
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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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- Iodine-Promoted Metal-Free Cyclization and O/S Exchange of Acrylamides with Thiuram: One-Step Synthesis of Quinolino-2-thiones
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A one-step cyclization and O/S exchange reaction of readily available acrylamides in the presence of iodine and thiuram has been developed. The reaction provides an efficient approach for the synthesis of highly important heterocycle quinolino-2-thiones with diverse substitution patterns.
- Jiao, Jing,Wang, Cheng,Xiao, Fangtao,Zhang, Zhipeng
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supporting information
(2022/04/07)
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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 0048-0056; 0058
(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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- 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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- Selective N -monomethylation of primary anilines with the controllable installation of N -CH2D, N -CHD2, and N -CD3units
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The selective N-monomethylation of primary anilines was realized by the use of the Me3N-BH3/N,N-dimethylformamide (DMF) system as the methyl source. This method also allows for the controllable introduction of N-CH2D, N-CHD2, and N-CD3 units with high lev
- Meng, Jing,Wang, Yi-Feng,Wang, Zhijuan,Xia, Hui-Min,Xu, Ai-Qing,Zhang, Feng-Lian
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supporting information
p. 4922 - 4926
(2020/07/30)
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- Highly Efficient Binuclear Copper-catalyzed Oxidation of N,N-Dimethylanilines with O2
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A binuclear copper-salicylate complex, [Cu(Sal)2(NCMe)]2 (Sal=salicylate), was found to be an active catalyst for the oxidation of N,N-dimethylanilines by O2, affording the corresponding N-methyl-N-phenylformamides as major products. The reactions were carried out with a O2 balloon and the S/C (substrate/catalyst ratio) of the model reaction could be up to 1×105, providing a practical and highly efficient catalytic protocol for accessing N-methyl-N-phenylformamides.
- Liu, Yuxia,Yan, Yonggang,Xue, Dong,Wang, Zhongfu,Xiao, Jianliang,Wang, Chao
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p. 2221 - 2225
(2020/03/23)
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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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p. 337 - 344
(2020/07/03)
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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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- Iron-Catalyzed Regioselective α-C-H Alkylation of N-Methylanilines: Cross-Dehydrogenative Coupling between Unactivated C(sp3)-H and C(sp3)-H Bonds via a Radical Process
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The iron-catalyzed α-C-H alkylation of N-methylanilines without any directing group by cross-dehydrogenative coupling between unactivated C(sp3)-H and C(sp3)-H bonds has been established for the first time, which provides a good complement to C(sp3)-H activation reactions and expands the field of Fe-catalyzed C-H functionalizations. Many different C(sp3)-H bonds in cyclic alkanes, cyclic ethers, and toluene derivatives can be used as coupling partners. Mechanistic investigations including the radical reaction process, the main role of various reagents, and the kinetic isotope effect experiment were also described.
- Li, Ze-Lin,Sun, Kang-Kang,Wu, Peng-Yu,Cai, Chun
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p. 6830 - 6839
(2019/06/14)
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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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p. 5072 - 5082
(2019/04/17)
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- Photoinduced Cross-Coupling of Amines with 1,2-Diiodobenzene and Its Application in the Synthesis of Carbazoles
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A facile and efficient process for the preparation of various tertiary aminobenzenes and carbazole derivatives via photoinduced cross-coupling of amines with 1,2-diiodobenzene is reported. Mechanistic investigations indicate that the transformation proceeds via nucleo-philic addition of an amine to the benzyne intermediate accompanied with a proton transfer process, followed by an oxidative cyclization of the generated diphenylamine to furnish the corresponding carbazole products.
- Zhao, Xinxin,Chen, Ming,Huang, Binbin,Yang, Chao,Gao, Yuan,Xia, Wujiong
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supporting information
p. 2981 - 2989
(2018/05/15)
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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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p. 4701 - 4714
(2018/07/03)
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- Synthesis and Biological Evaluation of Selenium-Containing 4-Anilinoquinazoline Derivatives as Novel Antimitotic Agents
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Twenty-eight novel selenium-containing 4-anilinoquinazoline derivatives were designed, synthesized, and evaluated as antiproliferative agents. Most of them had significant in vitro activities, particularly for compounds 23a, 25a, and 25d, which also exhibited the most potent antitumor activities against cisplatin-resistant cell lines and the doxorubicin-resistant cell lines, good selectivity toward normal cells, and obvious inhibitory effect on migration of A549 cell lines. Further mechanistic studies revealed that 23a, 25a, and 25d induce G2/M phase arrest and apoptosis in A549 cells, which was associated with a collapse of the mitochondrial membrane potential, alterations in the expression of some cell cycle-related and apoptosis-related proteins, and increasing the intracellular ROS level. Finally, compounds 23a, 25a, and 25d also effectively inhibited the tumor growth in the A549 xenograft model without obvious hints of toxicity. Taken together, these in vitro and in vivo results suggest that 23a, 25a, and 25d may be promising microtubule-stabilizing agents and can be used as a promising lead for the development of new antitumor agents.
- An, Baijiao,Wang, Bo,Hu, Jinhui,Xu, Shaoyu,Huang, Ling,Li, Xingshu,Chan, Albert S. C.
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p. 2571 - 2588
(2018/03/26)
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- Electronic effect of substituents on anilines favors 1,4-addition to: Trans -β-nitrostyrenes: Access to N -substituted 3-arylindoles and 3-arylindoles
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A simple and an efficient method for the regioselective synthesis of N-alkyl/aryl/H 3-arylindole derivatives from N-substituted anilines and trans-β-nitrostyrenes has been described using 10 mol% of bismuth(iii) triflate as a catalyst in acetonitrile at 80 °C. The present protocol profits from the formation of new C-C and C-N bonds, broad substrate scope and moderate to good yields.
- Gattu, Radhakrishna,Bhattacharjee, Suchandra,Mahato, Karuna,Khan, Abu T.
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supporting information
p. 3760 - 3770
(2018/05/30)
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- Efficient and versatile catalytic systems for the n-methylation of primary amines with methanol catalyzed by n-heterocyclic carbene complexes of iridium
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Efficient and versatile catalytic systems were developed for the N-methylation of both aliphatic and aromatic primary amines using methanol as the methylating agent. Iridium complexes bearing an Nheterocyclic carbene (NHC) ligand exhibited high catalytic performance for this type of transformation. For aliphatic amines, selective N,N-dimethylation was achieved at low temperatures (50-90 °C). For aromatic amines, selective N-monomethylation and selective N,N-dimethylation were accomplished by simply changing the reaction conditions (presence or absence of a base with an appropriate catalyst). These findings can be used to develop methods for synthesizing useful amine compounds having N-methyl or N,N-dimethyl moieties.
- Toyooka, Genki,Tuji, Akiko,Fujita, Ken-Ichi
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p. 4617 - 4626
(2019/02/01)
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- Ruthenium(II)-NNN-Pincer-Complex-Catalyzed Reactions Between Various Alcohols and Amines for Sustainable C?N and C?C Bond Formation
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An air and moisture stable 2-hydroxypyridine based bifunctional ruthenium NNN-pincer complex catalyzed efficient (TON=42840) N-alkylation of amines under mild conditions. Surprisingly, with cyclic secondary amines this methodology selectively produced only amides. Notably, N-methylation of several amines was achieved by using methanol as a green methylating agent. Furthermore, with lower catalyst loading (0.2 mol%) and shorter reaction time (6 h) numerous substituted quinolines were synthesized from 2-aminobenzyl alcohols and secondary alcohols. The effectiveness of this protocol was further extended by successfully synthesizing 2-alkylaminoquinolines in a one-pot fashion from amino alcohol, aliphatic nitriles, and alcohols. Gram scale synthesis of various compounds was also investigated to demonstrate the synthetic applicability of this methodology. (Figure presented.).
- Maji, Milan,Chakrabarti, Kaushik,Paul, Bhaskar,Roy, Bivas Chandra,Kundu, Sabuj
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supporting information
p. 722 - 729
(2018/01/01)
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- Rhodium catalyzed regioselective arene homologation of aryl urea via double C–H bond activation and migratory insertion of alkyne
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A convenient rhodium catalyzed oxidative arene homologation of aniline derivatives with symmetrical or unsymmetrical alkynes using Cu(OAc)2as oxidant is described. Urea group is shown to be effective as a directing group for initial ortho C–H activation. Two migratory insertion events of alkyne into Rh–C bond occur successively, both with complete regioselectivity. This method is particularly useful for synthesis of polyarenes with different substituents, which has not been reported with conventional protocol. A mechanism has been proposed to explain the observed data.
- Wang, Yan,Zhou, Hao,Xu, Ke,Shen, Mei-Hua,Xu, Hua-Dong
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supporting information
p. 92 - 96
(2017/01/12)
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- Tandem Transformation of Nitro Compounds into N-Methylated Amines: Greener Strategy for the Utilization of Methanol as a Methylating Agent
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A simple air- and moisture-stable, highly efficient ruthenium NNN pincer complex is reported for the first time to catalyze the tandem transformation of various aromatic and aliphatic nitro compounds into the corresponding N-methylated amines in up to 98 % yield by using methanol as a green methylating agent. Gram-scale reactions of challenging nitro substrates demonstrated the practical application aspects of this catalytic system. Importantly, the N-methylamine moiety could be smoothly introduced to various complex molecular structures without using any expensive palladium/phosphine/amine-based cross-coupling reactions.
- Paul, Bhaskar,Shee, Sujan,Chakrabarti, Kaushik,Kundu, Sabuj
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p. 2370 - 2374
(2017/06/13)
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- N-Methylation of Amines with Methanol Catalyzed by a Cp?Ir Complex Bearing a Functional 2,2′-Bibenzimidazole Ligand
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A new type of Cp?Ir complex bearing a functional 2,2′-bibenzimidazole ligand was designed, synthesized, and found to be a highly effective and general catalyst for the N-methylation of a variety of amines with methanol in the presence of a weak base (0.3 equiv of Cs2CO3).
- Liang, Ran,Li, Shun,Wang, Rongzhou,Lu, Lei,Li, Feng
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supporting information
p. 5790 - 5793
(2017/11/10)
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- Palladium-catalyzed oxidative carbonylation of aromatic C-H bonds of N -alkylanilines with CO and alcohols for the synthesis of o -aminobenzoates
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A Pd(II)-catalyzed C-H monocarbonylation of N-alkylanilines for the synthesis of o-aminobenzoates has been developed. Various aliphatic alcohols and phenol were tolerated in the reaction to afford the corresponding o-aminobenzoates in good yields under mild balloon pressure of CO.
- Chen, Ming,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
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p. 1258 - 1263
(2015/01/30)
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- Catalytic methylation of aromatic amines with formic acid as the unique carbon and hydrogen source
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A novel methodology is presented for the direct methylation of amines, using formic acid as a unique source of carbon and hydrogen. Based on ruthenium(II) catalysts, the formation of the N - CH3group proceeds via an efficient formylation/transfer hydrogenation pathway.
- Savourey, Solne,Lefvre, Guillaume,Berthet, Jean-Claude,Cantat, Thibault
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supporting information
p. 14033 - 14036
(2015/02/19)
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- General and efficient method for direct N-monomethylation of aromatic primary amines with methanol
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The direct N-monomethylation of aromatic primary amines, including arylamines, arylsulfonamides and amino-azoles, using methanol as a methylating agent has been accomplished in the presence of a [CpIrCl2]2/NaOH system. From both synthetic and environmental points of view, the reaction is highly attractive because of low catalyst loading, broad substrate scope and excellent selectivities.
- Li, Feng,Xie, Jianjiang,Shan, Haixia,Sun, Chunlou,Chen, Lin
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p. 8645 - 8652
(2015/03/05)
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- A facile and practical copper powder-catalyzed, organic solvent-and ligand-free ullmann amination of aryl halides
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A facile and practical method that the copper powder-catalyzed Ullmann amination of aryl halides with aqueous methylamine under organic solvent-and ligand-free condition at 100 °C and in air gave N-arylamines as sole products in good to excellent yields. The presence of a small amount of air is essential. Other aliphatic primary amines show good to very high reactivity. Secondary amines and aniline are not reactive. Sensitive substituents (i.e., CHO, MeCO, CN and Cl) are tolerable in the reaction.
- Jiao, Jiao,Zhang, Xi-Ru,Chang, Ning-Hui,Wang, Jie,Wei, Jun-Fa,Shi, Xian-Ying,Chen, Zhan-Guo
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supporting information; experimental part
p. 1180 - 1183
(2011/04/24)
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- A facile protocol for the synthesis of mono-N-methyl anilines via formimidate intermediates
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A general procedure for the preparation of mono-N-methyl anilines has been developed with excellent yields. This protocol relies on a NaBH3(OAc) reduction of formimidate intermediates that are quantitatively generated by treatment of primary substituted anilines with triethyl orthoformate under the catalysis of MCM-41-SO3H mesoporous zeolite. The newly developed procedure was facile, efficient, and environmentally benign.
- Sun, Nan,Wang, Shuai,Mo, Weimin,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
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experimental part
p. 7142 - 7148
(2010/09/14)
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- N-methylanilines from benzylic azides
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Benzylic azides are converted into N-methylanilines efficiently in the presence of a Bronsted or Lewis acid and Et3SiH. The combination of SnCl4/Et3SiH and 4-n-butylbenzyl azide appears to form an aminodiazonium trichlorostannate(II), which undergoes the rearrangement to an iminium salt that is then reduced to N-methyl-4-n-butylaniline by Et3SiH.
- Lopez, Francisco J.,Nitzan, Dov
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p. 2071 - 2074
(2007/10/03)
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- 2,4-diaminopyridopyrimidine Inhibitors of Dihydrofolate Reductase from Pneumocystis carinii and Toxoplasma gondii
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Six previously unknown 2,4-diamino-6-(anilinomethyl)- and 2,4-diamino-6-pyridopyrimidines (5-10) were synthesized from 2,4-diamino-6-(bromomethyl)pyridopyrimidine hydrobromide (11*HBr) by treatment with the appropriate aniline or N-methylaniline in dimethylformamide at room temperature, with or without NaHCO3 present.Compounds 5-10 were tested as inhibitors of dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, and rat liver as a part of a larger effort directed toward the discovery of lipophilic nonclassical antifolates combining high enzyme selectivity and high potency.Of the six analogues tested, the most potent and selective against T. gondii DHFR was 2,4-diamino-6-pyridopyrimidine (7), which had an IC50 of 0.0047 μM against this enzyme as compared with 0.026 μM against the rat liver enzyme.The potency of 7 against T. gondii DHFR was similar to that of trimetrexate (TMQ, 1) and piritrexim (PTX, 2) but was >500-fold greater than that of trimethoprim (TMP, 3).However, while 7 was more selective than either TMQ (19*) or PTX (63*) against this enzyme, its selectivity in comparison with TMP was 8-fold lower. 2,4-Diamino-6-pyridopyrimidine (6) was 17-fold less active than 7 and was also less selective. 2,4-Diamino-6-pyridopyrimidine (10) had an IC50 of 0.022 μM against P. carinii DHFR and was comparable in potency to TMQ and PTX.The species selectivity of 10 for P. carinii versus rat liver DHFR was greater than that of either TMQ (21-fold) or PTX (31-fold).On the other hand, even though 10 was slightly more active than TMQ against the P. carinii enzyme, its selectivity was 7-fold lower than that of TMP.Thus, the goal of combining high enzyme binding activity, which is characteristic of the fused-ring compounds TMQ and PTX, with high selectivity for T. gondii and P. carinii DHFR versus rat liver DHFR, which is characteristic of the monocyclic compound TMP, remained unmet in this limited series.
- Rosowsky, Andre,Forsch, Ronald A.,Queener, Sherry F.
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p. 2615 - 2620
(2007/10/03)
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- Reactions of Carbonyl Compounds in Basic Solutions. Part 14. The Alkaline Hydrolysis of Substituted N-Methylformanilides, N-Methylacetanilides, 1- Phenylazetidin-2-ones, 1-Phenyl-2-pyrrolidones, and 1-Phenyl-2-piperidones
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The rate coefficients for the alkaline hydrolysis of a series of substituted 1-phenylazetidin-2-ones, -2-pyrrolidones, and -2-piperidones, and N-methylacetanilides and N-methylformanilides in aqueous dimethyl sulphoxide and in aqueous dioxane or water have been measured at several temperatures.The reactions were first order in substrate and, for the lactams and acetanilides, first order in base and, for the formanilides, both first and second order in base.Hammet reaction constants and activation parameters have been evaluated for each system.The relative reactivity,salt, solvent and solvent isotope effects have been examined.The following mechanisms for the reactions are suggested.For the β-lactams, the bathway appears to be the rate determining attack by hydroxide and, for the γ- and δ-lactams and acetanilides, rate determining fission of the carbon-nitrogen link, which follows equilibrium addition of the base.The formanilides appear to form a tetrahedral intermediate with hydroxide which can collapse to product via rate-determining water- or base- catalysis.
- Bowden, Keith,Bromley, Keith
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p. 2103 - 2109
(2007/10/02)
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- One-Pot Monomethylation of Substituted Anilines by Phase Transfer Catalyst
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A one-pot monomethylation of substituted anilines (1) by phase transfer catalysis has been developed.The primary amino function of 1 is protected by treatment with formic acid to give N-formylanilines (2) which are methylated in situ with dimethyl sulphate in the presence of tetrabutylammonium hydrogen sulphate, anhyd.K2CO3 and powdered NaOH.The resultant N-formyl-N-methylanilines (3) on deformylation by boiling with water furnish N-methyl-anilines (4) in high yields with >95percent purity.
- Sharma, V. K.,Kumar, A.,Agarwal, K. P.
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- Basic Hydrolysis of Some Alkyl and Phenyl N-Aryl-N-methylcarbamates.
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Rate constants for the basic hydrolysis of methyl, ethyl and phenyl N-aryl-N-methylcarbamates in the presence and absence of micelles of cetyltrimethylammonium bromide are reported.Hammett plots for the methyl aand ethyl carbamates were curved, and this is explained by consideration of the competition between C-N and C-OR bond breaking for decomposition of the tetrahedral intermediate.In one case (p-nitro-substituted), rate-determining formation of the tetrahedral intermediate is suggested, whereas for other compounds rate-determining C-N bond breaking or C-OR bond bre aking is proposed.Micellar catalysis for each of the reactions is reported, and large catalysis (x 50) was observed for compounds where C-N bond breaking was kinetically significant.This is compared with results in the literature for amide and ester hydrolysis.Whereas, for ester hydrolysis, loss of alkoxide ion from the tetrahedral intermediate is favoured over loss of hydroxide ion, in carbamate hydrolysis, loss of hydroxide ions is favoured.A possible reason for this reversal of nucleofugicity of OH- and OR- is proposed.
- Broxton, Trevor J.
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p. 2203 - 2209
(2007/10/02)
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- Hydrogenation of halogen-substituted aromatic nitro compounds
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This invention relates to the hydrogenation of halogen-substituted aromatic nitro compounds and in particular provides a novel catalyst for use in such processes. In more detail a catalyst suitable for use in the hydrogenation of halogen-substituted aromatic nitro compounds substantially without simultaneous dehalogenation comprises one or more metals from the group consisting of platinum, palladium, rhodium, iridium, ruthenium and osmium supported on or impregnated into a carrier material comprising carbon activated with phosphoric acid or a salt thereof.
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- N-DEMETHYLATION OF N,N-DIMETHYLANILINES BY PHOTOEXCITED 3-NITROCHLOROBENZENE
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The title reaction proceeds via initial electron transfer (rather than hydrogen atom transfer) from the amine to the photoexcited nitro compound, as demonstrated by methoxy substitution in the substrate and absence of CH3/CD3-discrimination.
- Doepp, Dietrich,Heufer, Joerg
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p. 1553 - 1556
(2007/10/02)
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- Kinetics and Mechanism of the Hydrolysis of Anilide Acetals
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A kinetic study of the hydrolysis of anilide acetals ArC(OMe)2NMeAr' is reported.At high pH (>10) a pH independent C-O cleavage reaction is observed producing methanol and benzimidatonium ion; the latter is further hydrolyzed to amide and ester products.Substituent and solvent effects support a simple ionizaiton mechanism with a transition state near the ion.At pH + catalysis attributable to pre-equilibrium protonation followed by rate-determining cleavage.Estimation of the pKa of the protonated anilide acetal (-1) provides an estimate of its rate of C-N cleavage (ca.108 s-1) which is near the diffusion limit.At pH 7 there is a change in the rate-determining step in product formation in this C-N cleavage reaction, and what is observed kinetically is the decomposition of the hemiorthoester ArC(OMe)2OH, the product of hydration of the dialkoxy carbocation.The principal piece of evidence for the changeover is the observation that the rate constants in acid solution are independent of the aniline moiety of the anilide acetal.
- McClelland, Robert A.,Patel, Geeta
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p. 6908 - 6911
(2007/10/02)
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- Formation of superoxide radical anion in the horseradish peroxidase-catalysed oxidation of three aromatic tertiary amines with hydrogen peroxide
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The horseradish peroxidase-catalysed oxidation of aromatic tertiary amines with hydrogen peroxide to give a secondary amine and an aldehyde occurs through the co-occurrence of the usual reaction with H2O2 and a free radical chain reaction which depends upon oxygen concentration. The intervention of superoxide radical anion is demonstrated by the reduction of cytochrome cIII and the dismutation catalysed by superoxide dismutase.
- Galliani, Guido,Rindone, Bruno
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- Substituent Effects on the Basic Methanolysis of a Series of Substituted N-Methyl-p-toluanilides
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The rate of basic methanolysis of a series of substituted N-methyl-p-toluanilides (1) has been measured at 373 K.A Hammett plot of these results resulted in a straight line (ρ 3.1 r 0.998) indicative of reaction by solvent-assisted bond breaking (mechanism B) throughout the series.The revelance of these results to previous results for the basic hydrolysis of N-methyl-p-toluanilides (1) and basic methanolysis of N-methylbenzanilides (2) is discussed.
- Broxton, Trevor J.,Duddy, Neil W.
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p. 903 - 906
(2007/10/02)
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