- Copper-catalyzed aerobic oxidation of amines to imines under neat conditions with low catalyst loading
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The copper (I)-catalyzed direct synthesis of imines from amines under mild aerobic conditions is described. The method is applicable for the synthesis of various imines from corresponding amines such as benzylic, aliphatic, cyclic secondary, heteroaromatic species and the oxidative condensation of benzylamines with anilines extends the scope of the CuCl catalytic system. Noteworthy, solvent-free procedure, air as a benign oxidant, and the cheap and easy availability of the catalyst are the vital advantages of the method. Copyright
- Patil, Rajendra D.,Adimurthy, Subbarayappa
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- Trans-Symmetric Dynamic Covalent Systems: Connected Transamination and Transimination Reactions
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The development of chemical transaminations as a new type of dynamic covalent reaction is described. The key 1,3-proton shift is under complete catalytic control and can be conducted orthogonally to, or simultaneous with, transimination in the presence of an amine to rapidly yield two-dimensional dynamic systems with a high degree of complexity evolution. The transamination-transimination systems are proven to be fully reversible, stable over several days, compatible with a range of functional groups, and highly tunable. Kinetic studies show transamination to be the rate-limiting reaction in the network. Furthermore, it was discovered that readily available quinuclidine is a highly potent catalyst for aldimine transaminations. This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element. Constant exchange: The development of chemical transaminations as a new type of dynamic covalent reactions is described (see figure). This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element.
- Schaufelberger, Fredrik,Hu, Lei,Ramstr?m, Olof
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supporting information
p. 9776 - 9783
(2015/06/30)
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- C-C bond formation and related reactions at the CNC backbone in (smif)FeX (smif = 1,3-di-(2-pyridyl)-2-azaallyl): Dimerizations, 3 + 2 cyclization, and nucleophilic attack; Transfer hydrogenations and alkyne trimerization (X = N(TMS)2, dpma = (Di-(2-pyridyl-methyl)-amide))
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Molecular orbital analysis depicts the CNCnb backbone of the smif (1,3-di-(2-pyridyl)-2-azaallyl) ligand as having singlet diradical and/or ionic character where electrophilic or nucleophilic attack is plausible. Reversible dimerization of (smif)Fe{N(SiMe3)2} (1) to [{(Me3Si)2N}Fe]2(μ-κ3, κ3-N,py2-smif,smif) (2) may be construed as diradical coupling. A proton transfer within the backbone-methylated, and o-pyridine-methylated smif of putative (bMe2 oMe2smif)FeN(SiMe3)2 (8) provides a route to [{(Me3Si)2N}Fe]2(μ- κ4,κ4-N,py2,C-(bMe, bCH2,oMe2(smif)H))2 (9). A 3 + 2 cyclization of ditolyl-acetylene occurs with 1, leading to the dimer [{2,5-di(pyridin-2-yl)-3,4-di-(p-tolyl-2,5-dihydropyrrol-1-ide)}FeN(SiMe 3)2]2 (11), and the collateral discovery of alkyne cyclotrimerization led to a brief study that identified Fe(N(SiMe 3)2(THF) as an effective catalyst. Nucleophilic attack by (smif)2Fe (13) on tBuNCO and (2,6-iPr 2C6H3)NCO afforded (RNHCO-smif)2Fe (14a, R = tBu; 14b, 2,6-iPrC6H3). Calculations suggested that (dpma)2Fe (15) would favorably lose dihydrogen to afford (smif)2Fe (13). H2-transfer to alkynes, olefins, imines, PhNNPh, and ketones was explored, but only stoichiometric reactions were affected. Some physical properties of the compounds were examined, and X-ray structural studies on several dinuclear species were conducted.
- Frazier, Brenda A.,Williams, Valerie A.,Wolczanski, Peter T.,Bart, Suzanne C.,Meyer, Karsten,Cundari, Thomas R.,Lobkovsky, Emil B.
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p. 3295 - 3312
(2013/05/08)
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- PROCESS FOR PREPARING AMINES FROM ALCOHOLS AND AMMONIA
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The present invention provides novel ruthenium based catalysts, and a process for preparing amines, by reacting a primary alcohol and ammonia in the presence of such catalysts, to generate the amine and water. According to the process of the invention, primary alcohols react directly with ammonia to produce primary amines and water in high yields and high turnover numbers. This reaction is catalyzed by novel ruthenium complexes, which are preferably composed of quinolinyl or acridinyl based pincer ligands.
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Page/Page column 24; 31; 32
(2010/04/03)
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