Relevant articles and documents
All total 113 Articles be found
All total 113 Articles be found-
Downie et al.
, p. 3951 (1975)
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Photochemical Reaction of N,N-Dimethylanilines with N-Substituted Maleimides Utilizing Benzaldehyde as the Photoinitiator
Nikitas, Nikolaos F.,Theodoropoulou, Maria A.,Kokotos, Christoforos G.
, p. 1168 - 1173 (2021)
Photoorganocatalysis constitutes a powerful domain of photochemistry and organic synthesis. The scaffold of pyrrolo[3,4-c]quinolinoles exhibits interesting and potent inhibition against various enzymes, making them really promising pharmaceutical targets. Herein, we describe a photochemical methodology for the reaction of N,N-dimethylanilines with N-substituted maleimides, utilizing benzaldehyde as the photoinitiator. A variety of substituted N,N-dimethylanilines and N-substituted maleimides were converted into the corresponding adducts in moderate to high yields.
Deoxygenation of Tertiary Amine Oxides with Carbon Disulfide
Yoshimura, Toshiaki,Asada, Kaoru,Oae, Shigeru
, p. 3000 - 3003 (1982)
Reduction of various tertiary amine oxides with carbon disulfide was examined and kinetic experiments were carried out.Trialkylamine oxides and N,N-dialkylarylamine N-oxides were readily reduced by CS2 to give the corresponding tertiary amines in good yields, while heteroaromatic amine N-oxides such as picoline N-oxide were not affected.The oxygen atom in the N-oxide was found to be transferred to CO2 upon mass spectral analysis of the gas evolved.The kinetic experiments were carried out following the UV spectra of N,N-dimethylaniline N-oxide in CH3CN containing much excess of CS2 and the rate was found to be of 2nd order in the N-oxide and CS2.Activation parameters (ΔH=55.7 kJ mol-1, ΔS=-78.2 J K-1 mol-1 at 20 deg C) are characteristic of a normal bimolecular reaction.The logarithms of the rate constants for para-substituted N,N-dimethylaniline N-oxides are nicely correlated with Hammett ? values and a small negative ρ value (ρ=-0.2) was obtained.The rate of reaction was faster in polar aprotic solvents than in nonpolar or protic solvents.These observations seem to suggest that the reaction proceeds via an initial nucleophilic attack of the N-oxide oxygen at carbon disulfide followed by the rate-determining N-O bond fission to give the tertiary amine.
Selective utilization of methoxy groups in lignin for: N -methylation reaction of anilines
Mei, Qingqing,Shen, Xiaojun,Liu, Huizhen,Liu, Hangyu,Xiang, Junfeng,Han, Buxing
, p. 1082 - 1088 (2019)
The utilization of lignin as a feedstock to produce valuable chemicals is of great importance. However, it is a great challenge to produce pure chemicals because of the complex structure of lignin. The selective utilization of specific groups on lignin molecules offers the possibility of preparing chemicals with high selectivity, but this strategy has not attracted attention. In this work, we propose a protocol to produce methyl-substituted amines by the selective reaction of the methoxy groups of lignin and aniline compounds. It was found that LiI in the ionic liquid 1-hexyl-3-methylimidazolium tetrafluoroborate could catalyze the reaction efficiently and the selectivity to the N-methylation product could be as high as 98%. Moreover, the lignin was not depolymerized in the reaction. As it was rich in hydroxyl groups, the residual material left over after the reaction was used as an efficient co-catalyst for the cycloaddition of epoxy propane with CO2, using KI as the catalyst.
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Pedersen et al.
, p. 4211,4212 (1973)
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Traceless Directing-Group Strategy in the Ru-Catalyzed, Formal [3 + 3] Annulation of Anilines with Allyl Alcohols: A One-Pot, Domino Approach for the Synthesis of Quinolines
Kumar, Gangam Srikanth,Kumar, Pravin,Kapur, Manmohan
, p. 2494 - 2497 (2017)
A unique, ruthenium-catalyzed, [3 + 3] annulation of anilines with allyl alcohols in the synthesis of substituted quinolines is reported. The method employs a traceless directing group strategy in the proximal C-H bond activation and represents a one-pot Domino synthesis of quinolines from anilines.
1,4-Dioxane-Tuned Catalyst-Free Methylation of Amines by CO2 and NaBH4
Guo, Zhiqiang,Zhang, Bo,Wei, Xuehong,Xi, Chanjuan
, p. 2296 - 2299 (2018)
A catalyst-free reductive functionalization of CO2 with amines and NaBH4 was developed. The N-methylation of amines was carried out with CO2 as a C1 building block and 1,4-dioxane as the solvent. Notably, the six-electron reduction of CO2 to form the methyl group occurred simultaneously with formation of the C?N bond to give the N-methylated amine.
N-methylation of aromatic amines and N-heterocycles under acidic conditions with the TTT (1,3,5-trioxane-triethylsilane-trifluoroacetic acid) system
Popp, Tobias A.,Bracher, Franz
, p. 3333 - 3338 (2015)
A novel reductive N-methylation protocol under acidic conditions with the TTT (1,3,5-trioxane-triethylsilane-trifluoroacetic acid) system is disclosed. This method is highly specific for aromatic amines and several N-heterocycles (indoles and annulated analogues, phenoxazine, phenothiazine), insensitive to steric hindrance, and compatible with a wide range of functional groups. Further the N-methylation step can be combined with an in situ N-Boc deprotection. Compounds in which the nucleophilicity of the NH group is eliminated by protonation under the reaction conditions (aliphatic amines, azaarenes of noteworthy basicity) are inert. In several examples, it was demonstrated that the TTT system is complementary to other N-methylation protocols.
Selenium-catalyzed carbonylation of nitroarenes to symmetrical 1,3-diarylureas under atmospheric pressure
Wang, Xiaofang,Lu, Shiwei,Yu, Zhengkun
, p. 929 - 932 (2004)
Selenium-catalyzed carbonylation of nitrobenzene and substituted nitroarenes with CO under atmospheric pressure afforded symmetrical 1,3-diarylureas in yields up to 94%. A mechanism has been proposed to demonstrate the formation of symmetrical ureas.
Convenient dimethylamino amination in heterocycles and aromatics with dimethylformamide
Agarwal, Anu,Chauhan, Prem M. S.
, p. 2925 - 2930 (2004)
A convenient dimethylamino amination of various heterocyclic and aromatic compounds having activated chloro group has been carried out in good yields using dimethyl formamide (DMF).
Methylation of aromatic amines and imines using formic acid over a heterogeneous Pt/C catalyst
Zhu, Lei,Wang, Lian-Sheng,Li, Bojie,Li, Wei,Fu, Boqiao
, p. 6172 - 6176 (2016)
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.
Metal-free protodeboronation of electron-rich arene boronic acids and its application to ortho -functionalization of electron-rich arenes using a boronic acid as a blocking group
Ahn, Su-Jin,Lee, Chun-Young,Kim, Nak-Kyoon,Cheon, Cheol-Hong
, p. 7277 - 7285 (2014)
The metal-free thermal protodeboronation of various electron-rich arene boronic acids was studied. Several reaction parameters controlling this protodeboronation, such as solvent, temperature, and a proton source, have been investigated. On the basis of these studies, suitable reaction conditions for protodeboronation of several types of electron-rich arene boronic acids were provided. On the basis of this protodeboronation, a new protocol for the synthesis of ortho-functionalized electron-rich arenes from these boronic acids was developed using the boronic acid moiety as a blocking group in the electrophilic aromatic substitution reaction, followed by the removal of the boronic acid moiety via thermal protodeboronation. Mechanistic studies suggested that this protodeboronation might proceed via the complex formation of a boronic acid with a proton source, followed by the carbon-boron bond fission through σ-bond metathesis, to afford the corresponding arene compound and boric acid.
Catalyst-free N-methylation of amines using CO2
Niu, Huiying,Lu, Lijun,Shi, Renyi,Chiang, Chien-Wei,Lei, Aiwen
, p. 1148 - 1151 (2017)
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.
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Hodgson,Nicholson
, p. 470,474 (1941)
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4-N,N-Dimethylaminophenyl azide photooxidation: effect of conditions on the reaction pathway. Ring contraction of benzene to cyclopentadiene due to a strongly electron-donating substituent
Chainikova, Ekaterina,Khursan, Sergey,Lobov, Alexander,Erastov, Alexey,Khalilov, Leonard,Mescheryakova, Ekaterina,Safiullin, Rustam
, p. 4661 - 4665 (2015)
Abstract Depending on the reaction conditions employed, the photooxidation of 4-N,N-dimethylaminophenyl azide led to the formation of 4-N,N-dimethylaminonitrosobenzene and 4-N,N-dimethylaminonitrobenzene or (5Z)-2-(dimethylamino)-5-(hydroxyimino)cyclopenta-1,3-diene-1-carbaldehyde.
Synthesis of dihydroquinazolines from 2-aminobenzylamine: N3-aryl derivatives with electron-withdrawing groups
Gruber, Nadia,Díaz, Jimena E.,Orelli, Liliana R.
, p. 2510 - 2519 (2018)
The sequential N-functionalization of 2-aminobenzylamine (2-ABA) followed by cyclodehydration allowed for a straightforward and efficient synthesis of 3,4-dihydroquinazolines with N-aryl substituents bearing electron-withdrawing groups. The sequence involves an initial SNAr displacement, N-acylation and MW-assisted ring closure. Remarkably, the uncatalyzed N-arylation of 2-ABA led to the monosubstitution product using equimolar amounts of both reagents. The individual steps were optimized achieving good to excellent overall yields of the desired heterocycles, avoiding additional protection and deprotection steps. A mechanistic interpretation for the cyclodehydration reaction promoted by trimethylsilyl polyphosphate (PPSE) is also proposed on the basis of literature data and our experimental observations.
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Evans,Williams
, p. 1199 (1939)
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Catalytic alternative of the Ullman reaction
Hassan, Jwanro,Penalva, Vincent,Lavenot, Laurence,Gozzi, Christel,Lemaire, Marc
, p. 13793 - 13804 (1998)
Symmetrical functionalized biaryls and biheterocycles could be obtained in good yield via homocoupling of aryl halides by using Pd(OAc)2 as catalyst with base and isopropanol. This alternative of the Ullmann reaction has proved to be compatible with sensitive functional groups.
Base-oxidant promoted metal-free N-demethylation of arylamines
Botla, Vinayak,Barreddi, Chiranjeevi,Daggupati, Ramana V,Malapaka, Chandrasekharam
, p. 1469 - 1473 (2016)
A metal-free oxidative N-demethylation of arylamines with triethylamine as a base and tert-butyl hydroperoxide (TBHP) as oxidant is reported in this paper. The reaction is general, practical, inexpensive, non-toxic, and the method followed is environmentally benign, with moderate to good yields. [Figure not available: see fulltext.]
New nitronate σ complexes and the mechanism of nucleophilic aromatic photosubstitution para to a nitro group
Wubbels, Gene G.,Johnson, Kandra M.
, p. 1451 - 1454 (2006)
Photolysis of 4-nitroanisole with aliphatic amines gives mainly N-substituted 4-nitroanilines. Reactions of this type have been widely attributed to a geminate radical mechanism. We questioned this interpretation and have searched for and found by NMR spectroscopy a new class of stable nitronate adducts generated under the reaction conditions. The adducts imply that photosubstitution by amines para to the nitro group occurs by meta σ complex formation followed by an unprecedented sigmatropic rearrangement.
Borane-Trimethylamine Complex as a Reducing Agent for Selective Methylation and Formylation of Amines with CO2
Zhang, Yanmeng,Zhang, He,Gao, Ke
supporting information, p. 8282 - 8286 (2021/10/25)
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.
Photoassisted Charge Transfer Between DMF and Substrate: Facile and Selective N,N-Dimethylamination of Fluoroarenes
Ansari, Tharique N.,Sharma, Sudripet,Bora, Pranjal P.,Ogulu, Deborah,Parmar, Saurav,Gallou, Fabrice,Kozlowski, Pawel M.,Handa, Sachin
, p. 2704 - 2709 (2021/06/09)
A reversible Van der Waals complex formation between the electron-deficient fluorinated aromatic ring and N,N-dimethylformamide (DMF) molecules followed by light irradiation resulted in charge transfer (CT) process. The complex was stabilized by ammonium formate and further decomposed to form the C?N bond. Control experiments revealed that the simultaneous SNAr pathway also contributes to product formation. This methodology is mild, metal-free, and effective for the amination of a variety of substrates. The reproducibility of this methodology was also verified on gram-scale reactions. The CT states were supported by control UV/Vis spectroscopy and computational studies.
