63674-11-3Relevant academic research and scientific papers
Phosphine-Free Well-Defined Mn(I) Complex-Catalyzed Synthesis of Amine, Imine, and 2,3-Dihydro-1 H-perimidine via Hydrogen Autotransfer or Acceptorless Dehydrogenative Coupling of Amine and Alcohol
Das, Kalicharan,Mondal, Avijit,Pal, Debjyoti,Srivastava, Hemant Kumar,Srimani, Dipankar
supporting information, p. 1815 - 1825 (2019/04/30)
The application of nontoxic, earth-abundant transition metals in place of costly noble metals is a paramount goal in catalysis and is especially interesting if the air- and moisture-stable ligand scaffold is used. Herein, we report the synthesis of amines/imines directly from alcohol and amines via hydrogen autotransfer or acceptorless dehydrogenation catalyzed by well-defined phosphine-free Mn complexes. Both imines and amines can be obtained from the same set of alcohols and amines using the same catalyst, only by tuning the reaction conditions. The amount and nature of the base are found to be a highly important aspect for the observed selectivity. Both the primary and secondary amines have been employed as substrates for the N-alkylation reaction. As a highlight, we showed the chemoselective synthesis of resveratrol derivatives. Furthermore, the Mn-catalyzed dehydrogenative synthesis of structurally important 2,3-dihydro-1H-perimidines has also been demonstrated. Density functional theory calculations were also carried out to model the reaction path and to calculate the reaction profile.
H2 Activation by Non-Transition-Metal Systems: Hydrogenation of Aldimines and Ketimines with LiN(SiMe3)2
Elliott, Daniel C.,Marti, Alex,Mauleón, Pablo,Pfaltz, Andreas
, p. 1918 - 1922 (2019/01/16)
In recent years, H2 activation at non-transition-metal centers has met with increasing attention. Here, a system in which H2 is activated and transferred to aldimines and ketimines using substoichiometric amounts of lithium bis(trimethylsilyl)amide is reported. Notably, the reaction tolerates the presence of acidic protons in the α-position. Mechanistic investigations indicated that the reaction proceeds via a lithium hydride intermediate as the actual reductant.
Electrochemical Approach for Direct C-H Phosphonylation of Unprotected Secondary Amine
Huang, Min,Dai, Jie,Cheng, Xu,Ding, Mengning
supporting information, p. 7759 - 7762 (2019/10/11)
Direct α-phosphonylation of an unprotected secondary amine in a single step is of practical importance to amino phophophates. However, this protocol is limited due to the high redox barrier of unprotected amine. In this paper, we report C-H phosphonylation of an unprotected secondary amine via an electrochemical approach in the presence of catalytic carboxylate salt. This metal-free and exogenous oxidant-free method furnishes diverse target molecules with satisfactory yield under mild reaction conditions. Successful application of the protocol in a gram-scale experiment demonstrates the potential utility for further functionalization.
Synthesis of Symmetric and Unsymmetric Secondary Amines from the Ligand-Promoted Ruthenium-Catalyzed Deaminative Coupling Reaction of Primary Amines
Arachchige, Pandula T. Kirinde,Lee, Hanbin,Yi, Chae S.
, p. 4932 - 4947 (2018/05/08)
The catalytic system generated in situ from the tetranuclear Ru-H complex with a catechol ligand (1/L1) was found to be effective for the direct deaminative coupling of two primary amines to form secondary amines. The catalyst 1/L1 was highly chemoselective for promoting the coupling of two different primary amines to afford unsymmetric secondary amines. The analogous coupling of aniline with primary amines formed aryl-substituted secondary amines. The treatment of aniline-d7 with 4-methoxybenzylamine led to the coupling product with significant deuterium incorporation on CH2 (18% D). The most pronounced carbon isotope effect was observed on the α-carbon of the product isolated from the coupling reaction of 4-methoxybenzylamine (C(1) = 1.015(2)). A Hammett plot was constructed from measuring the rates of the coupling reaction of 4-methoxyaniline with a series of para-substituted benzylamines 4-X-C6H4CH2NH2 (X = OMe, Me, H, F, CF3) (ρ = -0.79 ± 0.1). A plausible mechanistic scheme has been proposed for the coupling reaction on the basis of these results. The catalytic coupling method provides an operationally simple and chemoselective synthesis of secondary amine products without using any reactive reagents or forming wasteful byproducts.
Copper-catalyzed ligand free ring-opening amination of gem-fluorohalocyclopropanes – An efficient route toward 2-fluoroallylamines
Novikov, Maxim A.,Ibatov, Yaroslav A.,Volchkov, Nikolai V.,Lipkind, Maria B.,Semenov, Sergei E.,Nefedov, Oleg M.
, p. 58 - 72 (2017/01/18)
Ring-opening amination of gem-chlorofluoro- and gem-bromofluorocyclopropanes with secondary alkyl, aryl amines or hydroxylamines catalyzed by copper(I) or copper(II) compounds with no additional ligands affords tertiary 2-fluoroallylamines or hydroxylamines in moderate to excellent yields. The reaction pathway involves isomerization of gem-fluorohalocyclopropanes to 2-fluoroallyl halides followed by in situ nucleophilic substitution of a halide by an N-nucleophile. The p-methoxyphenyl (PMP) protective group is efficient in the preparation of secondary 2-fluoroallylamines by this method. Primary 2-fluoroallylamines can only be obtained by a stepwise protocol including CuX-catalyzed isomerization of gem-fluorohalocyclopropanes to 2-fluoroallylic halides followed by amination.
Visible light-induced intramolecular dearomative cyclization of α-bromo-N-benzyl-alkylamides: Efficient construction of 2-azaspiro[4.5]decanes
Hu, Bei,Li, Yuyuan,Dong, Wuheng,Ren, Kai,Xie, Xiaomin,Wan, Jun,Zhang, Zhaoguo
supporting information, p. 3709 - 3712 (2016/03/05)
An efficient intramolecular dearomative cyclization via visible light-induced photoredox catalysis allows for a highly regioselective dearomative cyclization of α-bromo-N-benzyl-alkylamides to construct 2-azaspiro[4.5]decanes in the presence of an iridium catalyst.
Palladium nanoparticles stabilised by cinchona-based alkaloids in glycerol: Efficient catalysts for surface assisted processes
Reina,Pradel,Martin,Teuma,Gómez
, p. 93205 - 93216 (2016/10/11)
Palladium nanoparticles (PdNPs) were synthesised and fully characterised, both in solution and the solid state, using naturally-occurring cinchona-based alkaloids in neat glycerol. These nano-systems were stable under reaction conditions, finding applications in hydrogenation and hydrodehalogenation processes, as a result of their surface-like behaviour. Their reactivity was improved in relation to that involving PdNPs stabilised by phosphines and also by Pd/C as a heterogenous catalyst, mainly in terms of recyclability. In particular, the colloidal palladium catalyst stabilised by quinidine was highly efficient to promote the hydrodechlorination of aromatic compounds under low dihydrogen pressure. These original catalysts found applications in the synthesis of secondary and tertiary amines including N-substituted anilines, by means of one-pot tandem Pd-catalysed methodologies under smooth conditions. In all of these processes, glycerol performed a crucial function as a liquid support for the immobilisation of nanoparticle-based catalysts, allowing both the stabilisation of the nano-catalysts and easy recycling of the catalytic phase.
Chemoselective deprotection of N-allylic amines using DDQ
Kumar, Pradeep,Cherian, Shijo K.,Jain, Ruchi,Show, Krishanu
supporting information, p. 7172 - 7176 (2015/01/09)
A highly chemoselective and simple method for the deprotection of N-allylic amines using DDQ has been developed. The use of DDQ in dichloromethane-water provides a mild and efficient one-step deallylation of a wide variety of orthogonally protected tertiary amine derivatives.
Rapid and efficient access to secondary arylmethylamines
Fleury-Brégeot, Nicolas,Raushel, Jessica,Sandrock, Deidre L.,Dreher, Spencer D.,Molander, Gary A.
, p. 9564 - 9570 (2012/08/28)
Ammoniomethyl trifluoroborates are very powerful reagents that can be used to access biologically relevant aryl- and heteroaryl-methylamine motifs via Suzuki-Miyaura cross-couplings. Until now, this method was limited to the production of tertiary and primary amines. The synthesis of a large array of secondary ammoniomethyltrifluoroborates has been achieved through a one step nucleophilic substitution reaction on the potassium bromomethyltrifluoroborate. Smooth cross-coupling conditions have been designed, based on the use of an aminobiphenyl palladium precatalyst, to couple these trifluoroborates efficiently with aryl bromides. This strategy offers a new way to access biologically relevant motifs and allows, with the previously developed methods, access to all three classes of aminomethylarenes. Secondary ammoniomethyltrifluoroborates can be easily synthesized by nucleophilic substitution on potassium bromomethyltrifluoroborate. These reagents have then been used in Suzuki-Miyaura cross-couplings with aryl bromides, offering an effective access to the aminomethylarene structural motif. This new method provides an interesting alternative to the reductive amination procedure (see scheme). Copyright
Direct reductive amination of aldehydes using lithium-arene(cat.) as reducing system. A simple one-pot procedure for the synthesis of secondary amines
Nador, Fabiana,Moglie, Yanina,Ciolino, Andrés,Pierini, Adriana,Dorn, Viviana,Yus, Miguel,Alonso, Francisco,Radivoy, Gabriel
experimental part, p. 3156 - 3160 (2012/08/08)
A simple one-pot procedure for the direct reductive amination of aldehydes using lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) or a polymer supported naphthalene as reducing system is described. The direct reductive amination of a variety of aldehydes with primary amines was achieved simply by adding a mixture of the corresponding carbonyl compound and the amine, over a solution of the lithium arenide in THF at room temperature. For most of the substrates tested the main reaction products were the secondary amines along with variable amounts of the corresponding alcohol and/or imine products. Theoretical DFT calculations have been applied in order to explain the differences in reactivity observed for aromatic substrates.
