- Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
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Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
- An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
-
supporting information
p. 2876 - 2894
(2021/02/01)
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- Dirhodium-Catalyzed Chemo-and Site-Selective C-H Amidation of N, N-Dialkylanilines
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A method for dirhodium-catalyzed C(sp 3)-H amidation of N, N-dimethylanilines was developed. Chemoselective C(sp 3)-H amidation of N-methyl group proceeded exclusively in the presence of C(sp 2)-H bonds of the electron-rich aromatic ring. Site-selective C(sp 3)-H amidation proceeded exclusively at the N-methyl group of N-methyl-N-Alkylaniline derivatives with secondary, tertiary, and benzylic C(sp 3)-H bonds α to a nitrogen atom.
- Chen, Gong,Arai, Kenta,Morisaki, Kazuhiro,Kawabata, Takeo,Ueda, Yoshihiro
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supporting information
p. 728 - 732
(2021/01/18)
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- Preparation method of N-alkylated derivative of primary amine compound
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The invention relates to a preparation method of an N-alkylated derivative of a primary amine compound. The method comprises the following steps: uniformly mixing a primary amine compound, an alcohol compound and a catalyst in a reactor, and heating to react for a period of time to generate an N-alkylated substituted tertiary amine compound; wherein the catalyst is a copper-cobalt bimetallic catalyst, and the carrier of the catalyst is Al2O3. According to the method, alcohol is adopted as an alkylating reagent and is low in price and easy to obtain, a byproduct is water, no pollution is caused to the environment, and the overall reaction atom economy is high; the catalyst is simple in preparation method, low in cost, high in reaction activity and good in structural stability; meanwhile, by using the copper-cobalt bimetallic catalyst, the use of strong base additives can be avoided, and the requirement on reaction equipment is low; and the reaction post-treatment is convenient, and the catalyst can be recycled and is environment-friendly.
- -
-
Paragraph 0021; 0047
(2021/07/09)
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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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- Nickel-Catalyzed Amination of Aryl Chlorides with Amides
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A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.
- Li, Jinpeng,Huang, Changyu,Wen, Daheng,Zheng, Qingshu,Tu, Bo,Tu, Tao
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supporting information
p. 687 - 691
(2021/01/09)
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- Photocatalytic Water-Splitting Coupled with Alkanol Oxidation for Selective N-alkylation Reactions over Carbon Nitride
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Photocatalytic water splitting technology (PWST) enables the direct use of water as appealing “liquid hydrogen source” for transfer hydrogenation reactions. Currently, the development of PWST-based transfer hydrogenations is still in an embryonic stage. Previous reports generally centered on the rational utilization of the in situ generated H-source (electrons) for hydrogenations, in which photogenerated holes were quenched by sacrificial reagents. Herein, the fully-utilization of the liquid H-source and holes during water splitting is presented for photo-reductive N-alkylation of nitro-aromatic compounds. In this integrate system, H-species in situ generated from water splitting were designed for nitroarenes reduction to produce amines, while alkanols were oxidized by holes for cascade alkylating of anilines as well as the generated secondary amines. More than 50 examples achieved with a broad range scope validate the universal applicability of this mild and sustainable coupling approach. The synthetic utility of this protocol was further demonstrated by the synthesis of existing pharmaceuticals via selective N-alkylation of amines. This strategy based on the sustainable water splitting technology highlights a significant and promising route for selective synthesis of valuable N-alkylated fine chemicals and pharmaceuticals from nitroarenes and amines with water and alkanols.
- Xu, Yangsen,Zhang, Zhaofei,Qiu, Chuntian,Chen, Shaoqin,Ling, Xiang,Su, Chenliang
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p. 582 - 589
(2020/12/09)
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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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p. 12174 - 12180
(2021/09/28)
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- Borane-Trimethylamine Complex as a Reducing Agent for Selective Methylation and Formylation of Amines with CO2
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We report herein that a borane-trimethylamine complex worked as an efficient reducing agent for the selective methylation and formylation of amines with 1 atm CO2 under metal-free conditions. 6-Amino-2-picoline serves as a highly efficient catalyst for the methylation of various secondary amines, whereas in its absence, the formylation of primary and secondary amines was achieved in high yield with high chemoselectivity. Mechanistic studies suggest that the 6-amino-2-picoline-borane catalytic system operates like an intramolecular frustrated Lewis pair to activate CO2.
- Zhang, Yanmeng,Zhang, He,Gao, Ke
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p. 8282 - 8286
(2021/10/25)
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- Mn-Catalyzed Selective Double and Mono-N-Formylation and N-Methylation of Amines by using CO2
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Functionalization of amines by using CO2 is of fundamental importance considering the abundance of amines and CO2. In this context, the catalytic formylation and methylation of amines represent convenient and successful protocols for selective CO2 utilization as a C1 building block. This study represents the first example of selective catalytic double N-formylation of aryl amines by using a dinuclear Mn complex in the presence of phenylsilane. This robust system also allows for selective formylation and methylation of amines under a range of conditions.
- Huang, Zijun,Jiang, Xiaolin,Zhou, Shaofang,Yang, Peiju,Du, Chen-Xia,Li, Yuehui
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p. 3054 - 3059
(2019/04/10)
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- Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic N-Oxides
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A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
- Kim, Kyu Dong,Lee, Jun Hee
-
supporting information
p. 7712 - 7716
(2019/01/03)
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- Application of Silicon-Initiated Water Splitting for the Reduction of Organic Substrates
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The use of water as a donor for hydrogen suitable for the reduction of several important classes of organic compounds is described. It is found that the reductive water splitting can be promoted by several metalloids among which silicon shows the best efficiency. The developed methodologies were applied for the reduction of nitro compounds, N-oxides, sulfoxides, alkenes, alkynes, hydrodehalogenation as well as for the gram-scale synthesis of several substrates of industrial importance.
- Gevorgyan, Ashot,Mkrtchyan, Satenik,Grigoryan, Tatevik,Iaroshenko, Viktor O.
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p. 375 - 382
(2018/06/04)
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- Ni-Catalyzed Cross-Coupling of Dimethyl Aryl Amines with Arylboronic Esters under Reductive Conditions
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Herein, we reported a successful Suzuki-Miyaura coupling of dimethyl aryl amines to forge biaryl skeleton via Ni catalysis in the absence of directing groups and preactivation. This transformation proceeded with high efficiency in the presence of magnesium. Preliminary mechanism studies demonstrated dual roles of magnesium: (i) a reductant that reduced Ni(II) species to active Ni(I) catalyst; (ii) a unique promoter that facilitated the Ni(I)/Ni(III) catalytic cycle.
- Cao, Zhi-Chao,Xie, Si-Jun,Fang, Huayi,Shi, Zhang-Jie
-
supporting information
p. 13575 - 13579
(2018/10/24)
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- Fluorescence of Cyclopropenium Ion Derivatives
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The synthesis of cyclopropenium-substituted amino compounds and analysis of their photophysical properties is described. Systematic structural modifications of these derivatives lead to measurable and predictable changes in molar extinction coefficients, quantum yields, and Stokes shifts. Using time-dependent density functional theory (TD-DFT) calculations, the origin of these trends was traced to internal charge transfer (ICT) coupled with ensuing structural reorganization for select naphthalene functionalized derivatives. Associated with this structural reorganization was an inward gearing of the cyclopropenium ring and twisting of the peri-NMe2 group into coplanarity with the naphthalene ring system. Further, reinforcement of an intramolecular H-bond (IMHB) in the excited state of these derivatives alludes to the importance of photoinduced H-bonding in this new class of cyclopropenium based fluorophores.
- Belding, Lee,Guest, Matt,Le Sueur, Richard,Dudding, Travis
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p. 6489 - 6497
(2018/06/01)
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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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- Deoxygenation of tertiary amine N-oxides under metal free condition using phenylboronic acid
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A simple and efficient method for the deoxygenation of amine N-oxides to corresponding amines is reported using the green and economical reagent phenylboronic acid. Deoxygenation of N,N-dialkylaniline N-oxides, trialkylamine N-oxides and pyridine N-oxides were achieved in good to excellent yields. The reduction susceptible functional groups such as ketone, amide, ester and nitro groups are well tolerated with phenylboronic acid during the deoxygenation process even at high temperature. In addition, an indirect method for identification and quantification of tert-amine N-oxide is demonstrated using UV–Vis spectrometry which may be useful for drug metabolism studies.
- Gupta, Surabhi,Sureshbabu, Popuri,Singh, Adesh Kumar,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
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supporting information
p. 909 - 913
(2017/02/15)
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- Catalyst-free N-methylation of amines using CO2
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Recently, utilizing CO2 as a methylation reagent to construct functional chemicals has attracted significant attention. However, the conversion of CO2 is still a challenge due to its inherent inertness. In this study, we have developed a catalyst-free N-methylation of amines to prepare numerous methylamines using CO2 as a methyl source. By utilizing 2 eq. PhSiH3 as the reductant, amines could undergo N-methylation under 1 atm of CO2 in DMF at 90 °C. Aliphatic and aromatic amines were compatible, generating the desired products in up to 95% yield.
- Niu, Huiying,Lu, Lijun,Shi, Renyi,Chiang, Chien-Wei,Lei, Aiwen
-
supporting information
p. 1148 - 1151
(2017/02/05)
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- Preparation method by using amine and imine nitrogen methylation and application thereof
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The invention discloses a preparation method by using amine and imine nitrogen methylation and application thereof. The preparation method comprises the following steps: A, adding an active carbon loaded platinum catalyst into a Schlenk tube, and after vacuumizing to replace argon, adding a solvent; B, under protection of argon, separately adding phenylsilane, an initial raw material and formic acid; C, stirring the whole reaction system at a certain temperature to react; and D, after reaction, adding ethyl acetate into the system to dilute, stopping the reaction by using a sodium hydroxide aqueous solution, performing extraction with ethyl acetate, separating out an organic phase, drying and filtering the organic phase, and performing rotatable evaporation to remove the solvent. Column chromatography is performed on residues by using ethyl acetate/petroleum ether mixed solvent to obtain a target product, wherein the ethyl acetate and petroleum ether are different in proportion. According to the application of the method in isotope labeled drug synthesis, the dosage of a catalyst is extremely low, the cost is quite low, and the method is suitable for large-scaled production, can be suitable for amine and imine with different substituents, and suitable for realizing methylation conveniently on nitrogen atoms in a natural product structure to prepare drug molecules.
- -
-
Paragraph 0081; 0082; 0083; 0084; 0085; 0086
(2017/08/10)
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- Reductive Umpolung of Carbonyl Derivatives with Visible-Light Photoredox Catalysis: Direct Access to Vicinal Diamines and Amino Alcohols via α-Amino Radicals and Ketyl Radicals
-
Visible-light-mediated photoredox-catalyzed aldimine-aniline and aldehyde-aniline couplings have been realized. The reductive single electron transfer (SET) umpolung of various carbonyl derivatives enabled the generation of intermediary ketyl and α-amino radical anions, which were utilized for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols. Anilines can be coupled with aldimines or aldehydes in a visible-light-mediated photoredox-catalyzed process. Reductive single electron transfer (SET) umpolung of the carbonyl derivatives leads to the generation of intermediary ketyl and α-amino radical anions, which were used for the synthesis of unsymmetrically substituted 1,2-diamines and amino alcohols.
- Fava, Eleonora,Millet, Anthony,Nakajima, Masaki,Loescher, Sebastian,Rueping, Magnus
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supporting information
p. 6776 - 6779
(2016/06/09)
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- C8-H bond activation vs. C2-H bond activation: From naphthyl amines to lactams
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Pd-catalyzed selective amine-oriented C8-H bond functionalization/N-dealkylative carbonylation of naphthyl amines has been achieved. The amine group from dealkylation is proposed to be the directing group for promoting this process. It represents a straightforward and easy method to access various biologically important benzo[cd]indol-2(1H)-one derivatives.
- Shi, Renyi,Lu, Lijun,Xie, Hangyu,Yan, Jingwen,Xu, Ting,Zhang, Hua,Qi, Xiaotian,Lan, Yu,Lei, Aiwen
-
supporting information
p. 13307 - 13310
(2016/11/17)
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- Highly Twisted N,N-Dialkylamines as a Design Strategy to Tune Simple Aromatic Hydrocarbons as Steric Environment-Sensitive Fluorophores
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The steric-environment sensitivity of fluorescence of 9,10-bis(N,N-dialkylamino)anthracenes (BDAAs) was studied experimentally and theoretically. A new design strategy to tune simple aromatic hydrocarbons as efficient aggregation-induced emission (AIE) luminogens and molecular rotors is proposed. For a variety of BDAAs, prominent Stokes shifts and efficient solid-state fluorescence were observed. Calculations on BDAA-methyl suggested that in the ground state (S0) conformations, the pyramidal amine groups are highly twisted, so that their lone-pair orbitals cannot conjugate with the anthracene π orbitals. Fluorescence takes place from the S1 minima, in which one or both amine groups are planarized. The stability of the S1 excited state minima as well as destabilization of the S0 state is the origin of large Stokes shift. Experimental measurement of the nonadiabatic transition rate suggests that para disubstitution by dialkylamino (or strongly electron-donating) groups is a key for fast internal conversion. Minimum energy conical intersection (MECI) between S1 and S0 states was found to have a Dewar-benzene like structure. Although this can be reached efficiently in liquid phase for fast internal conversion, a large amplitude motion is required to reach this MECI, which is prohibited in the solid state and caused efficient AIE. This strategy is used to find experimentally that naphthalene analogues are also efficient AIE luminogens. The flexibility of alkyl chains on amino groups is also found to be important for allowed charge-transfer transition. Thus, three points [(1) highly twisted N,N-dialkylamines, (2) substitution at the para positions, (3) with flexible alkyl groups] were proposed for activation of small aromatic hydrocarbons.
- Sasaki, Shunsuke,Suzuki, Satoshi,Sameera,Igawa, Kazunobu,Morokuma, Keiji,Konishi, Gen-Ichi
-
supporting information
p. 8194 - 8206
(2016/07/16)
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- Methylation of aromatic amines and imines using formic acid over a heterogeneous Pt/C catalyst
-
We describe here a commercially available Pt/C catalyst capable of catalyzing the methylation of anilines and aromatic imines with formic acid in the presence of a hydrosilane reductant. Both primary aniline and secondary aniline can be methylated. The advantage of this newly described method includes operational simplicity, high TON, ready availability of the catalyst, and also good functional group compatibility.
- Zhu, Lei,Wang, Lian-Sheng,Li, Bojie,Li, Wei,Fu, Boqiao
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p. 6172 - 6176
(2016/08/19)
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- Direct N-alkylation of aromatic amines using a microflow reactor: Enhancement of selectivity and reactivity
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A simple and highly atom-economical method for the direct N-alkylation of aromatic amines by using a microflow reactor was developed to overcome the problem of over-alkylation. In the developed method, high-yield conversion (up to 100%) was achieved in a relatively short reaction time. The ratio of mono- to di-benzylated products (3.57:1) was higher than that achieved with batch reactions conducted in a 1 L scale flask (0.87:1). The structural features of the microflow reactor meant that short-chain alkyl halides could be converted into products with high reactivity and selectivity under superheating conditions, although their boiling point was much lower than the reaction temperature. This method was successfully applied to the synthesis of a range of secondary amines including an intermediate of indobufen synthesis.
- Choi, Yong-Sung,Kim, Yoon-Jung,Shen, Liu-Lan,Lee, Yong Sup,Jeong, Jin-Hyun
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supporting information
p. 970 - 974
(2015/04/27)
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- Metal-free functionalization of N, N-dialkylanilines via temporary oxidation to N, N-dialkylaniline N-oxides and group transfer
-
A simple set of protocols for the controlled elaboration of anilines is reported allowing access to a diverse array of aminophenols, aminoarylsulfonates, alkylated anilines, and aminoanilines in 29-95% yield in a single laboratory operation from easily isolable, bench-stable N,N-dialkylaniline N-oxides. The introduction of new C-O, C-C, and C-N bonds on the aromatic ring is made possible by a temporary increase in oxidation level and excision of a weak N-O bond.
- Lewis, Robert S.,Wisthoff, Michael F.,Grissmerson,Chain, William J.
-
supporting information
p. 3832 - 3835
(2014/08/05)
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- Cu(ii)-catalyzed C-H (SP3) oxidation and C-N cleavage: Base-switched methylenation and formylation using tetramethylethylenediamine as a carbon source
-
Base-switched methylenation and formylation using tetramethylethylenediamine (TMEDA) as a carbon source have been achieved under mild conditions, catalyzed by CuCl2, with atmospheric oxygen as oxidant. Bisindolylmethanes, diphenylmethanes and 3-formylindoles were synthesized with excellent regioselectivity and good yield.
- Zhang, Lei,Peng, Chen,Zhao, Dan,Wang, Yue,Fu, Hai-Jian,Shen, Qi,Li, Jian-Xin
-
supporting information; experimental part
p. 5928 - 5930
(2012/07/27)
-
- Solid-phase synthesis of unfunctionalized arenes via the traceless cleavage of sulfonate linkers
-
The hydrogenolysis of polymer-bound arenesulfonates by 2-propylmagnesium chloride was performed through reductive cleavage of the C-S bond in the presence of a nickel catalyst. The reaction underwent in the highest efficiency by adding 15 equiv of the nucleophile in two additions with dppfNiCl2 in THF. Various unfunctionalized naphthalene, biphenyl, and stilbene derivatives were produced in good yields by the traceless sulfonate linker system at room temperature.
- Kim, Chul-Bae,Cho, Chul-Hee,Jo, Min Jy,Park, Kwangyong
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scheme or table
p. 3655 - 3659
(2012/01/12)
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- Ti(O-i-Pr)4/Me3SiCl/Mg-mediated reductive cleavage of sulfonamides and sulfonates to amines and alcohols
-
A low-valent titanium generated in situ from Ti(O-i-Pr)4, Me3SiCl, and Mg powder in THF reacted with aryl- and alkyl-sulfonamides of aryl and alkyl amines in a reductive N-S/S-O/S-C bond cleaving pathway to provide the corresponding amines and hydrocarbons (and thiols) derived from the sulfonyl moiety. The reagent could also cleave sulfonates to the corresponding alcohols.
- Shohji, Noriaki,Kawaji, Tsuyoshi,Okamoto, Sentaro
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supporting information; experimental part
p. 2626 - 2629
(2011/07/08)
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- Iron-catalyzed synthesis of glycine derivatives via carbon-nitrogen bond cleavage using diazoacetate
-
Treatment of tertiary amines with diazoacetate in the presence of a catalytic amount of an iron salt, FeCl3, in ethanol gave glycine derivatives. In this reaction, a carbon-nitrogen single bond of the amine was cleaved. The Royal Society of Chemistry 2010.
- Kuninobu, Yoichiro,Nishi, Mitsumi,Takai, Kazuhiko
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supporting information; experimental part
p. 8860 - 8862
(2011/02/28)
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- Tert -Amino Effect in peri -Substituted Naphthalenes: Syntheses of Naphthazepine and Naphthazonine Ring Systems
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Novel straightforward syntheses of naphtho-fused azepines and benzazonine via tert-amino effect are described. Starting from 1-naphthylamine, 8-N,N-dialkylaminonaphthalene-1-carbaldehydes could be obtained in two steps. The aldehyde was prepared by a Suzuki reaction of 8-bromonaphthalene-1- carbaldehyde with ortho-pyrrolidinophenylboronic acid. Treatment of aldehydes with active methylene compounds afforded naphthazepines and novel benzazonine ring system, respectively, through rearrangement of isolable vinyl intermediates or benzo[de]quinolinium derivatives or without isolation of any intermediates. A mechanistic investigation supports an intramolecular hydride transfer for the ring closure to azepine or azonine. Our results indicate that the tert-amino effect may provide a valuable approach to the synthesis of ortho- and peri-fused aza-ring systems.
- F?ldi, ágota Anna,Ludányi, Krisztina,Bényei, Attila Csaba,Mátyus, Péter
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scheme or table
p. 2109 - 2113
(2010/10/04)
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- SnCl2 mediated efficient N,N-dialkylation of azides to tertiary-amine via potential stannaimine intermediate
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A base free one-pot conversion of azides to N,N-dialkylamine is described. A two-step reaction pathway has been postulated invoking the intermediacy of stannaimine. This new carbon-nitrogen bond formation strategy adds to the repertoire of tin(II) chemistry.
- Roy, Ujjal Kanti,Roy, Sujit
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p. 1525 - 1530
(2007/10/03)
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- Facile preparation of polymer-supported methyl sulfonate and its recyclable use for methylation of carboxylic acids and amines
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A simple and efficient one-pot procedure for the preparation of polymer-supported methyl sulfonate from the reaction of polymer-supported sulfonic acid with trimethyl orthoacetate was achieved, and it could be successfully used for efficient methylation of carboxylic acids, phosphonic acids, sulfinic acids, amines, thiol, and phenol. Moreover, the polymer reagent could be recovered, regenerated, and reused easily for the same reactions. Georg Thieme Verlag Stuttgart.
- Yoshino, Tomonori,Togo, Hideo
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p. 517 - 519
(2007/10/03)
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- A simple and effective procedure for the N-permethylation of amino-substituted naphthalenes
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A wide range of amino-substituted naphthalenes can be N-permethylated by the system Me2SO4/Na2CO3/ H2O(alcohols) with good to excellent yields. Steric hindrance does not prevent the reaction. Some amines with electron-withdrawing groups, especially at nonconjugated positions, are also alkylated. The procedure allows the combination of a reduction (catalytic or by tin dichloride in acidic media) and a methylation in a one-pot process. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Sorokin, Vladimir I.,Ozeryanskii, Valery A.,Pozharskii, Alexander F.
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p. 496 - 498
(2007/10/03)
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- Synthesis, structure, and reactivity of disilanes containing one neutral [4 + 2]-coordinate silicon center
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[4 + 2]-Coordinate disilanes containing two 8-dimethylamino-1-naphthyl (8-Me2N-1-Np) groups on the same silicon atom, (8-Me2N-1-Np)2XSi-SiMe3, where X = F, OH, OEt, and H, are prepared. The X-ray structures of t
- Tamao, Kohei,Asahara, Masahiro,Kawachi, Atsushi,Toshimitsu, Akio
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p. 479 - 486
(2007/10/03)
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- 1-Benzyl-1-azonia-4-azabicyclo[2.2.2]octane tetrahydroborate (BAAOTB) as a selective reducing agent
-
1-Benzyl-1-azonia-4-azabicyclo[2.2.2]octane tetrahydroborate (BAAOTB) 1 generated as white solid from commercially available DABCO and sodium borohydride is found to be a selective and versatile reducing agent. The reagent in t-butanol is very useful for reduction of imines, enamines, oximes, reductive amination of aldehydes and ketones and reductive methylation of amines.
- Hajipour,Mohammadpoor-Baltork,Rahi
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p. 239 - 242
(2007/10/03)
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- 1,8-Disubstituted naphthalenes by directed metalation and subsequent lithium-manganese exchange, including copper catalysis
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Directed lithiation of 1-dimethylamino- and 1-methoxynaphthalene, followed by Li-Mn exchange and reaction with electrophiles, provides regioselective syntheses of previously unknown racemic thioamides 2, 11 and 12, and ketones 5-8.
- Kiefl,Mannschreck
-
p. 1033 - 1037
(2007/10/02)
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- Conformational Studies by Dynamic NMR. 37. Monitoring the Stereomutations of Symmetric Amines by Means of a Chiral Auxiliary Agent
-
The chiral auxiliary agent (R)-l-2,2,2-trifluoro-1-(9-anthryl)ethanol was used to monitor the exchange between the enantiotopomers of symmetric amines lacking diastereotopic probes.The free energies of activation for stereomutations involving both C-N rotation and N-inversion processes were measured by line-shape simulation of the low-temperature NMR spectra.The effect of the chiral alcohol upon the barriers has also been evaluated, thus allowing one to compare these data with those of other amines where the stereomutations had been detected in achiral environment.The existence of steric deceleration for the exchange between enantiotopomers related by torsion and of steric acceleration for enantiotopomers related by N-inversion has been also verified.The highest N-inversion barrier observed in a simple noncyclic trialkyl amine (8.6 kcal mol-1 for Me2NEt) could thus be measured.
- Casarini, D.,Davalli, S.,Lunazzi, L.,Macciantelli, D.
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p. 4616 - 4619
(2007/10/02)
-
