- Green and chemo selective amine methylation using methanol by an organometallic ruthenium complex
-
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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- Additive-freeN-methylation of amines with methanol over supported iridium catalyst
-
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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- Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
-
Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
- An, Duk Keun,Jaladi, Ashok Kumar,Kim, Hyun Tae,Yi, Jaeeun
-
-
- Dimethylamination of Primary Alcohols Using a Homogeneous Iridium Catalyst: A Synthetic Method for N, N-Dimethylamine Derivatives
-
A new catalytic system for N,N-dimethylamination of primary alcohols using aqueous dimethylamine in the absence of additional organic solvents has been developed. The reaction proceeds via borrowing hydrogen processes, which are atom-efficient and environmentally benign. An iridium catalyst bearing an N-heterocyclic carbene (NHC) ligand exhibited high performance, without showing any deactivation under aqueous conditions. In addition, valuable N,N-dimethylamine derivatives, including biologically active and pharmaceutical molecules, were synthesized. The practical application of this methodology was demonstrated by a gram-scale reaction.
- Jeong, Jaeyoung,Fujita, Ken-Ichi
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p. 4053 - 4060
(2021/03/09)
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- Method for preparing tertiary amine organic compound by decomposing substituted formamide under mild condition
-
The invention discloses a method for preparing tertiary amine organic compounds by decomposing substituted formamide under mild conditions, which comprises the following steps: heating and stirring aldehydes serving as a reaction substrate, substituted formamide serving as a solvent, a reducing agent and an amination reagent, Ti-based oxide/hydroxide serving as a catalyst and a small amount of water serving as an auxiliary agent to generate the corresponding tertiary amine compound. Hydrogen is not needed in the reaction process. The method can be suitable for various aldehydes including aromatic aldehydes, fatty aldehydes and the like, and has the characteristics of high conversion rate and single product, and the tertiary amine compound can be simply, efficiently and safely synthesized without using hydrogen and noble metals in the reaction, so that the method has remarkable economic effects and application prospects.
- -
-
Paragraph 0031-0033; 0049
(2021/06/13)
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- Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
-
The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
- Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
-
supporting information
p. 6207 - 6227
(2021/05/06)
-
- Efficient hydrogenation of aliphatic amides to amines over vanadium-modified rhodium supported catalyst
-
This work presents a highly efficient catalytic hydrogenation system developed for the selective transformation of tertiary N,N-dimethyldodecanamide and secondary azepan-2-one amides to the corresponding amines. Industrial hydrogenation catalysts Pd/Al2O3, Pt/Al2O3 and Rh/Al2O3 were modified with vanadium (V) or molybdenum (Mo) species as oxophilic centres. The modified catalysts were prepared by deposition of V or Mo precursor on supported catalysts via impregnation method. The catalysts were characterized by ICP-OES, XRD, XPS, H2-TPR, FTIR, CO-chemisorption, TEM, SEM-EDX and TGA. Modified Rh-V/Al2O3 catalyst displayed the best performance affording high yield and selectivity >95 % to the desired tertiary and secondary amines at moderate reaction conditions of T H2 0 sites and oxophilic Vδ+ sites in the bimetallic Rh-V/Al2O3 catalyst were determined to be beneficial for the selective dissociation of C[dbnd]O bond of the carboxamides into the desired amines.
- Hernandez, Willinton Y.,Kusema, Bright T.,Pennetier, Alex,Streiff, Stéphane
-
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- Photon-initiated heterogeneous redox couples for methylation of anilines under mild conditions
-
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
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p. 4433 - 4437
(2020/08/10)
-
- Scalable synthesis of salt-free quaternary ammonium carboxylate catanionic surfactants
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Surfactants in commercial products commonly contain catanionic mixtures thus many studies of aqueous surfactant mixtures have been carried out. However, hardly any studies have been dedicated to pure catanionic surfactants often termed salt-free catanionic surfactants. One of the difficulties is in acquirement of samples with required purity due to difficult separation of these compounds from inorganic salts. In this work we present an alternative method of synthesis using dimethyl carbonate as the alkylating agent in order to obtain alkyl trimethylammonium alkanecarboxylates with medium alkyl chain lengths (6-10).
- ?tanfel, Ur?a,?ener, Bo?tjan,Be?ter-Roga?, Marija,Ko?mrlj, Janez,Medo?, ?iga,Virant, Miha
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p. 270 - 275
(2020/04/01)
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- The selective reductive amination of aliphatic aldehydes and cycloaliphatic ketones with tetragonal zirconium dioxide as the heterogeneous catalyst
-
A selective reductive amination of aliphatic aldehydes and cycloaliphatic ketones is achieved with tetragonal zirconium dioxide (t-ZrO2) as the catalyst. With N, N-dimethyl formamide (DMF) as the solvent, low-molecular-weight amine source and reductant, a more than 99 percent yield of N, N-dimethylpentan-1-amine or N, N-dimethyl cyclohexanamine was obtained when n-pentanal or cyclohexanone was used as the substrate. Particularly, the crystallographic structures exhibit a significant effect on catalytic performance where the tetragonal crystalline was preferable to monoclinic one during the reductive amination reaction. In addition, the recycling experiments of catalysts indicate that t-ZrO2 still kept a high catalytic activity even after being reused five times. From the result of DFT calculations, it is concluded that the crystalline of zirconium dioxide is closely related to the charge transferring rate between the catalyst and the adsorbed reactant. Finally, based on the experiment phenomena and simulation result, a possible reaction mechanism is proposed for the reductive amination of cyclohexanone.
- Bai, Peng,Li, Jiacong,Tong, Xinli,Wang, Shun,Zhang, Haigang,Zhang, Ming
-
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- N-Methylation of amines and nitroarenes with methanol using heterogeneous platinum catalysts
-
We report herein the selective N-methylation of amines and nitroarenes with methanol under basic conditions using carbon-supported Pt nanoparticles (Pt/C) as a heterogeneous catalyst. This method is widely applicable to four types of N-methylation reactions: (1) N,N-dimethylation of aliphatic amines under N2, (2) N-monomethylation of aliphatic amines under 40 bar H2, (3) N-monomethylation of aromatic amines under N2, and (4) tandem synthesis of N-methyl anilines from nitroarenes and methanol under 2 bar H2. All these reactions under the same catalytic system showed high yields of the corresponding methylamines for a wide range of substrates, high turnover number (TON), and good catalyst reusability. Mechanistic studies suggested that the reaction proceeded via a borrowing hydrogen methodology. Kinetic results combined with density functional theory (DFT) calculations revealed that the high performance of Pt/C was ascribed to the moderate metal–hydrogen bond strength of Pt.
- Jamil, Md.A.R.,Touchy, Abeda S.,Rashed, Md. Nurnobi,Ting, Kah Wei,Siddiki, S.M.A. Hakim,Toyao, Takashi,Maeno, Zen,Shimizu, Ken-ichi
-
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- Method for preparing tertiary amine organic compounds by using substituted formamide
-
The invention discloses a method for preparing tertiary amine organic compounds by using substituted formamide. According to the method, aldehyde is used as a reaction substrate, substituted formamideis used as a solvent, reducing agent and aminating agent, a metal oxide/hydroxide is added as a catalyst, and a small amount of water is added as an auxiliary agent; heating and stirring are carriedout so as to form corresponding tertiary amine compounds; and a reaction can be conducted only through heating without hydrogen and a reducing agent. The method of the invention is applicable to various aldehydes including aromatic aldehydes, fatty aldehydes, etc., and has the characteristics of few by-products and high product yield; and hydrogen is not used in the reaction, and the use of a noble metal hydrogenation catalyst is avoided, so the method has remarkable technical and economic effects and application prospects.
- -
-
Paragraph 0023-0025; 0029-0031; 0039-0041; 0045-0047
(2019/01/24)
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- Synthesis of β-Chiral Amines by Dynamic Kinetic Resolution of α-Branched Aldehydes Applying Imine Reductases
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Imine reductases (IREDs) allow the one-step preparation of optically active secondary and tertiary amines by reductive amination of ketones. Until now, mainly α-chiral amines have been prepared by this route. In this study, we explored the possibility of synthesizing β-chiral amines, a class of compounds which is also frequently found as structural motif in pharmaceuticals but much more challenging to prepare due to the following reasons: (i) The aldehyde substrate already contains the chiral center and needs to be racemized to enable full conversion. (ii) Because the intermediate imine bears the stereo center two carbon atoms remote to the imine nitrogen, it is more challenging to achieve high enantioselectivity compared to α-chiral amine synthesis. For investigating the proof of concept, we first confirmed that different IREDs are able to convert a variety of α-branched aldehydes when combined with five different amine substrates. The IRED from Streptomyces ipomoeae was a suitable enzyme facilitating the dynamic kinetic resolution of 2-phenylpropanal and a substituted 2-methyl-3-phenylpropanal: the corresponding N-methylated β-chiral amines were obtained with '95 % conversion and 78 and 95 %ee. Other amines were formed with low to moderate enantiomeric excess. This exemplifies the potential of IREDs for the one-step synthesis of secondary β-chiral amines, but also the challenge to identify highly selective enzymes for a desired amine product.
- Matzel, Philipp,Wenske, Sebastian,Merdivan, Simon,Günther, Sebastian,H?hne, Matthias
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p. 4281 - 4285
(2019/08/20)
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- Selective formylation or methylation of amines using carbon dioxide catalysed by a rhodium perimidine-based NHC complex
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Carbon dioxide can play a vital role as a sustainable feedstock for chemical synthesis. To be viable, the employed protocol should be as mild as possible. Herein we report a methodology to incorporate CO2 into primary, secondary, aromatic or alkyl amines catalysed by a Rh(i) complex bearing a perimidine-based NHC/phosphine pincer ligand. The periminide-based ligand belongs to a class of 6-membered NHC ligand accessed through chelate-assisted double C-H activation. N-Formylation and -methylation of amines were performed using a balloon of CO2, and phenylsilane as the reducing agent. Product selectivity between formylated and methylated products was tuned by changing the solvent, reaction temperature and the quantity of phenylsilane used. Medium to excellent conversions, as well as tolerance to a range of functional groups, were achieved. Stoichiometric reactions with reactants employed in catalysis and time course studies suggested that formylation and methylation reactions of interest begin with hydrosilylation of CO2 followed by reaction with amine substrates.
- Lam, Raphael H.,McQueen, Caitlin M. A.,Pernik, Indrek,McBurney, Roy T.,Hill, Anthony F.,Messerle, Barbara A.
-
supporting information
p. 538 - 549
(2019/02/14)
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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
-
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
-
supporting information
p. 722 - 729
(2018/01/01)
-
- Efficient and versatile catalytic systems for the n-methylation of primary amines with methanol catalyzed by n-heterocyclic carbene complexes of iridium
-
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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- The sustainable heterogeneous catalytic reductive amination of lignin models to produce aromatic tertiary amines
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A novel heterogeneous catalytic process for efficient reductive amination is developed in the presence of heterogeneous zirconium-based catalysts, in which N,N-dimethylformamide is used as the solvent, low-molecular-weight amine source and reductant. Aromatic tertiary amines have been produced from lignin-derived aromatic aldehydes via the mild Leuckart reaction with ZrO2 or ZrO(OH)2 as catalysts, for instance, a 95.8% yield of N,N-dimethyl-1-(3,4,5-trimethoxyphenyl)methanamine in a 100% selectivity is obtained from the reductive amination of 3,4,5-trimethoxybenzaldehyde under mild conditions.
- Zhang, Haigang,Tong, Xinli,Liu, Zonghui,Wan, Jun,Yu, Linhao,Zhang, Zhenya
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p. 5396 - 5400
(2018/11/20)
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- Selective synthesis of mono- and di-methylated amines using methanol and sodium azide as C1 and N1 sources
-
A Ru(ii) complex mediated synthesis of various N,N-dimethyl and N-monomethyl amines from organic azides using methanol as a methylating agent is reported. This methodology was successfully applied for a one-pot reaction of bromide derivatives and sodium azide in methanol. Notably, by controlling the reaction time several N-monomethylated and N,N-dimethylated amines were synthesized selectively. The practical applicability of this tandem process was revealed by preparative scale reactions with different organic azides and synthesis of an anti-vertigo drug betahistine. Several kinetic experiments and DFT studies were carried out to understand the mechanism of this transformation.
- Chakrabarti, Kaushik,Mishra, Anju,Panja, Dibyajyoti,Paul, Bhaskar,Kundu, Sabuj
-
supporting information
p. 3339 - 3345
(2018/07/29)
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- Tandem Transformation of Nitro Compounds into N-Methylated Amines: Greener Strategy for the Utilization of Methanol as a Methylating Agent
-
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)
-
- Preparation method of N-methylamine compound
-
The invention discloses a preparation method of a N-methylamine compound. The preparation method comprises the following steps: under an inertia organic solvent or solvent-free condition and under a support-type nano-sized gold catalyst effect, a primary amine compound or a secondary amine compound is subjected to a N-methylation reaction with carbon dioxide and hydrogen to obtain the product. The preparation method takes CO2 as a methyl source, takes hydrogen as a reducing agent, and takes the support-type nano-gold as a catalyst, and has the advantages that process is simple, catalyst activity is high, reaction rate is fast, the catalyst recovery and utilization are convenient, the application scope of a substrate is wide, the production cost is low, the benifit is high, the post-treatment is simple, repeatability is good, safe performance is high, and environmental protection is achieved, and the method is adapted to industrial production.
- -
-
Paragraph 0094; 0095; 0096; 0097; 0098
(2017/08/19)
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- Photometric Characterization of the Reductive Amination Scope of the Imine Reductases from Streptomyces tsukubaensis and Streptomyces ipomoeae
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Imine reductases (IREDs) have emerged as promising enzymes for the asymmetric synthesis of secondary and tertiary amines starting from carbonyl substrates. Screening the substrate specificity of the reductive amination reaction is usually performed by time-consuming GC analytics. We found two highly active IREDs in our enzyme collection, IR-20 from Streptomyces tsukubaensis and IR-Sip from Streptomyces ipomoeae, that allowed a comprehensive substrate screening with a photometric NADPH assay. We screened 39 carbonyl substrates combined with 17 amines as nucleophiles. Activity data from 663 combinations provided a clear picture about substrate specificity and capabilities in the reductive amination of these enzymes. Besides aliphatic aldehydes, the IREDs accepted various cyclic (C4–C8) and acyclic ketones, preferentially with methylamine. IR-Sip also accepted a range of primary and secondary amines as nucleophiles. In biocatalytic reactions, IR-Sip converted (R)-3-methylcyclohexanone with dimethylamine or pyrrolidine with high diastereoselectivity (>94–96 % de). The nucleophile acceptor spectrum depended on the carbonyl substrate employed. The conversion of well-accepted substrates could also be detected if crude lysates were employed as the enzyme source.
- Matzel, Philipp,Krautschick, Lukas,H?hne, Matthias
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p. 2022 - 2027
(2017/10/07)
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- Efficient and Selective N-Methylation of Nitroarenes under Mild Reaction Conditions
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Herein, we report a straightforward protocol for the preparation of N,N-dimethylated amines from readily available nitro starting materials using formic acid as a renewable C1 source and silanes as reducing agents. This tandem process is efficiently accomplished in the presence of a cubane-type Mo3PtS4 catalyst. For the preparation of the novel [Mo3Pt(PPh3)S4Cl3(dmen)3]+ (3+) (dmen: N,N′-dimethylethylenediamine) compound we have followed a [3+1] building block strategy starting from the trinuclear [Mo3S4Cl3(dmen)3]+ (1+) and Pt(PPh3)4 (2) complexes. The heterobimetallic 3+ cation preserves the main structural features of its 1+ cluster precursor. Interestingly, this catalytic protocol operates at room temperature with high chemoselectivity when the 3+ catalyst co-exists with its trinuclear 1+ precursor. N-heterocyclic arenes, double bonds, ketones, cyanides and ester functional groups are well retained after N-methylation of the corresponding functionalized nitroarenes. In addition, benzylic-type as well as aliphatic nitro compounds can also be methylated following this protocol.
- Pedrajas, Elena,Sorribes, Iván,Guillamón, Eva,Junge, Kathrin,Beller, Matthias,Llusar, Rosa
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p. 13205 - 13212
(2017/09/12)
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- Diisobutylaluminum borohydride: An efficient reagent for the reduction of tertiary amides to the corresponding amines under ambient conditions
-
A synthetically simple mixed metal hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], is easily generated from a 1:1 mixture of borane-dimethylsulfide (BMS) and diisobutylaluminum hydride (DIBAL). The reduction of tertiary amides using (iBu)2AlBH4 is complete within five minutes under ambient conditions and the product tertiary amines were isolated in 70–99% yields by a simple acid-base extraction. This new methodology, reported herein, works well for reduction of tertiary aliphatic and aromatic amides as well as lactams to the corresponding amines and product isolation and purification does not require column chromatography.
- Snelling, Rachel A.,Amberchan, Gabriella,Resendez, Angel,Murphy, Chris L.,Porter, Lauren,Singaram, Bakthan
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p. 4073 - 4077
(2017/09/28)
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- N-Alkyl Interstitial Spacers and Terminal Pendants Influence the Alkaline Stability of Tetraalkylammonium Cations for Anion Exchange Membrane Fuel Cells
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Current performance targets for anion exchange membrane (AEM) fuel cells call for greater than 95% alkaline stability for 5000 h at temperatures of up to 120 °C. Using this target temperature of 120 °C, we provide an incisive 1H nuclear magnetic resonance-based alkaline degradation method to identify the degradation products of n-alkyl spacer tetraalkylammonium cations in various AEM polymers and small molecule analogues. The operative alkaline degradation mechanisms and rates on benzyltrimethylammonium-, n-alkyl interstitial spacer-, and n-alkyl terminal chain-cations are compared in several architectures. Our findings indicate that benzyltrimethylammonium and n-alkyl terminal pendant cations are significantly more labile than an n-alkyl interstitial spacer cation. Additionally, we found that the alkaline stability of an n-alkyl interstitial spacer cation is enhanced when it is combined with an n-alkyl terminal pendant. At 120 °C, an inverse trend was observed in the overall stability of AEM poly(styrene) and AEM poly(phenylene oxide) samples compared to what has been shown at 80 °C. Follow-up small molecule studies suggest that at 120 °C, a 1,4-elimination degradation mechanism may be activated on styrenic AEM polymers capable of forming hyperconjugated resonance hybrids.
- Nu?ez, Sean A.,Capparelli, Clara,Hickner, Michael A.
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p. 2589 - 2598
(2016/06/01)
-
- Fluoride-Catalyzed Methylation of Amines by Reductive Functionalization of CO2with Hydrosilanes
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An effective and inexpensive organocatalyst tetrabutylammonium fluoride (TBAF) was developed for the reductive functionalization of CO2with amines to selectively afford formamides or methylamines by employing hydrosilanes. Hydrosilanes with different substituents show discriminatory reducing activity. Thus, the formation of formamides and further reduction products, that is, methylamines could be controlled by elegantly tuning hydrosilane types. Formamides were obtained exclusively under an atmospheric pressure of CO2with triethoxysilane. Using phenylsilane as a reductant, methylamines were attained with up to 99 % yield at 50 °C coupled to a complete deoxygenation of CO2. The crucial intermediate silyl formate in the formylation step was identified and thereby a tentative mechanism involving the fluoride-promoted hydride transfer from the hydrosilane to CO2/formamide was proposed. Striking features of this metal-free protocol are formylation and methylation of amines by reductive functionalization of CO2with hydrosilanes and mild reaction conditions.
- Liu, Xiao-Fang,Ma, Ran,Qiao, Chang,Cao, Han,He, Liang-Nian
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p. 16489 - 16493
(2016/11/09)
-
- Direct Methylation of Amines with Carbon Dioxide and Molecular Hydrogen using Supported Gold Catalysts
-
The N-methylation of amines with CO2 and H2 is an important step in the synthesis of bioactive compounds and chemical intermediates. The first heterogeneous Au catalyst is reported for this methylation reaction with good to excellent yields. The average turnover frequency (TOF) based on surface Au atoms is 45 h-1, which is the highest TOF value ever reported for the methylation of aniline with CO2 and H2. Furthermore, the catalyst is tolerant toward a variety of amines, which includes aromatic, aliphatic, secondary, and primary amines. Preliminary mechanistic studies suggest that the N-alkyl formamide might be an intermediate in the N-methylation of amine process. Moreover, through a one-pot process, it is possible to convert primary amines, aldehydes, and CO2 into unsymmetrical tertiary amines with H2 as a reductant in the presence of the Au catalyst.
- Du, Xian-Long,Tang, Gao,Bao, Hong-Liang,Jiang, Zheng,Zhong, Xin-Hua,Su, Dang Sheng,Wang, Jian-Qiang
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p. 3489 - 3496
(2015/11/02)
-
- Supramolecular Ga4L612- cage photosensitizes 1,3-rearrangement of encapsulated guest via photoinduced electron transfer
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The K12Ga4L6 supramolecular cage is photoactive and enables an unprecedented photoreaction not observed in bulk solution. Ga4L612- cages photosensitize the 1,3-rearrangement of encapsulated cinnamylammonium cation guests from the linear isomer to the higher energy branched isomer when irradiated with UVA light. The rearrangement requires light and guest encapsulation to occur. The Ga4L612- cage-mediated reaction mechanism was investigated by UV/vis absorption, fluorescence, ultrafast transient absorption, and electrochemical experiments. The results support a photoinduced electron transfer mechanism for the 1,3-rearrangement, in which the Ga4L612- cage absorbs photons and transfers an electron to the encapsulated cinnamylammonium ion, which undergoes C-N bond cleavage, followed by back electron transfer to the cage and recombination of the guest fragments to form the higher energy isomer.
- Dalton, Derek M.,Ellis, Scott R.,Nichols, Eva M.,Mathies, Richard A.,Dean Toste,Bergman, Robert G.,Raymond, Kenneth N.
-
supporting information
p. 10128 - 10131
(2015/09/01)
-
- Reductive amination using a combination of CaH2 and noble metal
-
Amines were prepared by a reductive amination reaction in the presence of calcium hydride and Pt/C. The in situ formation of water seems to be the key to activate CaH2 to reduce the intermediate imine.
- Guyon, Carole,Da Silva, Eric,Lafon, Romain,Mtay, Estelle,Lemaire, Marc
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p. 2292 - 2298
(2015/02/05)
-
- Methylformate as replacement of syngas in one-pot catalytic synthesis of amines from olefins
-
A new general approach for the one-pot hydroaminomethylation of olefins using methylformate as formylating agent instead of synthesis gas (syngas) has been proposed. Herein we report that a Ru-Rh catalytic system demonstrates high activity in a tandem conversion of a series of n-alkenes into amines using methylformate with yields 58-92% (6 h). The selectivity for the normal amine reached 96% with catalysis by the Ru carbonyl complex Ru3(CO) 12, with an overall yield of 55% with respect to amine in this instance. The addition of the Rh complex to Ru catalytic system, sharply increased the hydroaminomethylation rate of both the terminal and internal alkenes and increased the yield of amines to 82-93% (6-12 h). The Royal Society of Chemistry.
- Karakhanov, Eduard,Maksimov, Anton,Kardasheva, Yulia,Runova, Elena,Zakharov, Roman,Terenina, Maria,Kenneally, Corey,Arredondo, Victor
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p. 540 - 547
(2014/02/14)
-
- General catalytic methylation of amines with formic acid under mild reaction conditions
-
A general catalytic protocol for the methylation of amines has been developed applying, for the first time, formic acid as the C1 building block and silanes as reducing agents. A broad range of aromatic and aliphatic, both primary and secondary, amines has been converted to the corresponding tertiary amines including [N-13C]-labelled drugs in good to excellent yields under mild conditions. Methylation made easy: A general catalytic protocol for the methylation of amines has been developed applying, for the first time, formic acid as the C1 building block and silanes as reducing agents. A broad range of aromatic and aliphatic, both primary and secondary, amines has been converted to the corresponding tertiary amines, including [N-13C]-labelled drugs, in good to excellent yields at mild conditions (see scheme; dppp=(1,3-bis(diphenylphosphino)propane)).
- Sorribes, Ivan,Junge, Kathrin,Beller, Matthias
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supporting information
p. 7879 - 7883
(2014/07/07)
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- Highly selective hydroaminomethylation of internal alkenes to give linear amines
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The application of phenoxa-phosphino-modified Xantphos-type ligands (1-9) in the rhodium-catalyzed hydroaminomethylation of internal olefins to give linear amines is reported. Excellent chemo- and regioselectivities have been obtained through the use of 0.1 mol % [Rh(cod)2]BF4/0.4 mol% xantphenoxaphos (1), providing a practical and environmentally attractive synthetic route for the preparation of amines from internal alkenes. For the first time, both functionalized internal olefins and mixtures of internal and terminal olefins have been converted highly selectively into linear amines. Investigations of the effects of the calculated natural bite angles of ligands on hydroaminomethylation shows that the regioselectivity for the linear product follows a similar trend to that seen in the hydroformylation of internal alkenes with the aid of these ligands. Hydroaminomethylation and each of its individual steps were monitored by high-pressure infrared spectroscopy. The results suggest that hydroaminomethylations take place by a sequential isomerization/hydroformylation/amination/hydrogenation pathway.
- Ahmed, Moballigh,Bronger, Raymond P. J.,Jackstell, Ralf,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.,Beller, Matthias
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p. 8979 - 8988
(2007/10/03)
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- Synthesis of N,N-dimethylamines via Barbier-Grignard-type electrophilic amination
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Aryl Grignard reagents react with N,N-dimethyl O-(mesitylenesulfonyl)- hydroxylamine in THF under Barbier conditions at room temperature and give N,Ndimethylanilines with high yields in a 2-h reaction. The amination yield of in situ Grignard reagents were not lower than those of preformed aryl Grignard reagents. In situ cycloalkyl-, allyl-, and benzylmagnesium bromides did not react with N,Ndimethyl O-(mesitylenesulfonyl)hydroxylamine, except that amination of in situ n-hexylmagnesium bromide resulted in a medium yield. Grignard-Barbier-type amination of aryl bromides with N,N-dimethyl O-(mesitylenesulfonyl)hydroxylamine provides a new alternative route for the synthesis of N,N-dimethylanilines. Copyright Taylor & Francis Group, LLC.
- Erdik, Ender,Ates, Selma
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p. 2813 - 2818
(2007/10/03)
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- Cyclopentadienyl RuII Complexes as Highly Efficient Catalysts for the N-Methylation of Alkylamines by Methanol
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The ruthenium(II) half-sandwich complex [RuCl(η5-C5H5)(PPh3)2] (1) catalyses the reaction between methanol and alkylamines RNH2 or R1R2NH to afford RN(CH3)2 and R1R2NCH3 products, respectively. The reaction is quantitative and generally fast, at the methanol reflux temperature, for a wide spectrum of substrates. Starting form primary amines, the stepwise formation of RN=CH2, RNHCH3, and RN(CH3)2 has been observed. Both PPh3 and Cl- dissociation from 1 are key-steps in forming the effective catalytic species. The catalytic activity of several half-sandwich neutral or cationic complexes (2-15) related to 1 is also discussed.
- Zotto, Alessandro Del,Baratta, Walter,Sandri, Mauro,Verardo, Giancarlo,Rigo, Pierluigi
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p. 524 - 529
(2007/10/03)
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- Amines made easily: A highly selective hydroaminomethylation of olefins
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A highly chemo- and regioselective hydroaminomethylation of simple as well as functionalized α-olefins using a cationic rhodium precatalyst together with Xantphos as ligand is reported. Studies of the influence of ligands and reaction conditions led to an unprecedented selective hydroaminomethylation procedure. The novel procedure constitutes an economically attractive and environmentally favorable synthesis of secondary and tertiary aliphatic amines.
- Ahmed, Moballigh,Seayad, Abdul Majeed,Jackstell, Ralf,Beller, Matthias
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p. 10311 - 10318
(2007/10/03)
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- Hydroaminomethylation of olefins using a rhodium carbene catalyst
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Hydroaminomethylation of terminal as well as internal aliphatic and aromatic olefins with various amines is described in the presence of [Rh(cod)(Imes)Cl] as a catalyst. In general good to excellent yields and high chemoselectivity were obtained in THF at 85-105°C using 0.1 mol% of catalyst.
- Seayad, Abdul Majeed,Selvakumar, Kumaravel,Ahmed, Moballigh,Beller, Matthias
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p. 1679 - 1683
(2007/10/03)
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- Regioselective dealkylation of 2-alkoxybenzoic acid and its amide derivatives with aliphatic amines
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The methoxy group of o-anisic acid was cleaved with aliphatic amines in aprotic dipolar solvents. This cleavage reaction was especially smooth when piperazine in dimethylacetamide was used. This method was applicable to a variety of dealkylations of o-alkoxybenzoic acid and ist amide derivatives with high regio-selectivity.
- Nishioka, Hiroyasu,Nagasawa, Masaaki,Yoshida, Kiyoshi
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p. 243 - 246
(2007/10/03)
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- Molecular addition compounds. 15. Synthesis, hydroboration, and reduction studies of new, highly reactive tert-butyldialkylamine-borane adducts
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Two series of tert-butyldialkylamines have been prepared and examined for borane complexation. The complexing ability of each amine in the two series examined decreases in the order shown. First series: t- BuN(CH2CH2)2O 1a > t-BuNEt2 1b > t-BuNPr(n)21c > t-BuN(CH2CH2OMe)2 1d >> t-BuNBu(i)2 1e. Second series: t-BuNBu(i)Me 2a > t-BuNPr(i)Me 2b > t- BuNBu(i)Et 2c > t-BuNBu(i)Pr(n) 2d >>t-BuNPr(i)Et 2e. The reactivity of the corresponding borane adducts toward 1-octene increases in the reverse order. The following amines form highly reactive liquid borane adducts hydroborating 1-octene in tetrahydrofuran at room temperature in less than 1 h: t- BuN(CH2CH2OMe)2, t-BuNBu(i)Et, and t-BuNPr(i)Me. The limit of borane complexation among the amines examined is reached for t-BuNBu(i)2 exchanging borane neither with BMS nor with BH3-THF. Among the various borane adducts prepared, the more promising borane adducts, t-Bu(CH3OCH2CH2)2N-BH3 (7), t-BuMePr(i)N-BH3 (8), and t-BuEtBu(i)N-BH3 (9), were selected for complete hydroboration and reduction studies. Hydroboration studies with the new, highly reactive trialkylamine-borane adducts 7-9 and representative olefins, such as 1-hexene, styrene, β-pinene, cyclopentene, norbornene, cyclohexene, 2-methyl-2-butene, α-pinene, and 2,3-dimethyl-2-butene, in tetrahydrofuran, dioxane, tert-butyl methyl ether, n-pentane, and dichloromethane, at room temperature (22 ± 3°C) were carried out. The reactions are faster in dioxane, requiring 1-2 h for the hydroboration of simple, unhindered olefins to the trialkylborane stage. Moderately hindered olefins, such as cyclohexene and 2-methyl-2-butene, give the corresponding dialkylboranes rapidly, with further slow hydroboration. However, the more hindered olefins, α-pinene and 2,3-dimethyl-2-butene, give stable monoalkylboranes very rapidly, with further hydroboration proceeding relatively slowly. The hydroborations can also be carried out conveniently in other solvents, such as THF, tert-butyl methyl ether, and n-pentane. A significant rate retardation is observed in dichloromethane. Regioselectivity studies of 1-hexene and styrene using these amine-borane adducts show selectivities similar to that of BH3-THF. The rates and stoichiometry of the reaction of t-BuMePr(i)N-BH3 in tetrahydrofuran with selected organic compounds containing representative functional groups were also examined at room temperature. The reductions of esters, amides, and nitriles, which exhibit a sluggish reaction at room temperature, proceed readily under reflux conditions in tetrahydrofuran and dioxane and without solvent (at 85-90°C). The carrier amines can be recovered by simple acid-base manipulations in good yield and readily recycled to make the borane adducts.
- Brown, Herbert C.,Kanth, Josyula V. B.,Dalvi, Pramod V.,Zaidlewicz, Marek
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p. 6263 - 6274
(2007/10/03)
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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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p. 3974 - 3979
(2007/10/02)
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- Base-promoted elimination reactions of acetaldehyde N-alkyl-N,N-dimethylhydrazonium salts. A convenient synthesis of N,N-dimethylalkylamines
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The title reaction was utilized for efficient conversion of S(N)2-reactive alkyl halides to the corresponding N,N-dimethylalkylamines.
- Smith,Marcucci,Tingue
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p. 381 - 389
(2007/10/02)
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- SELECTIVE CONVERSION OF PRIMARY AMINES INRO N,N-DIMETHYLALKYL- OR N,N-DIALKYLMETHYL-AMINES WITH METHANOL AND RuCl2(Ph3P)3
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N,N-dimethylalkyl- or N,N-dialkylmethyl-amines are selectively obtained from the reaction between aliphatic amines and methanol at 180 deg C for 7 h in the presence of RuCl2(Ph3P)3 catalyst.
- Arcelli, Antonio,Khai, Bui-The,Porzi, Gianni
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- THE HOMOGENEOUSLY CATALYSED SYNTHESIS OF N-METHYLDIALKYLAMINES FROM N-METHYL AND N,N-DIMETHYLALKYLAMIMES
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N-Methyl and N,N-dimethylalkylamines are converted into N-methyldialkylamines in good yields when heated at 180 deg C in the presence of a catalytic amount of RuCl2(Ph3P)3.
- Arcelli, Antonio,Bui-The-Khai,Porzi, Gianni
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p. C31 - C34
(2007/10/02)
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