- Practical and regioselective amination of arenes using alkyl amines
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The formation of carbon–nitrogen bonds for the preparation of aromatic amines is among the top five reactions carried out globally for the production of high-value materials, ranging from from bulk chemicals to pharmaceuticals and polymers. As a result of this ubiquity and diversity, methods for their preparation impact the full spectrum of chemical syntheses in academia and industry. In general, these molecules are assembled through the stepwise introduction of a reactivity handle in place of an aromatic C–H bond (that is, a nitro group, halogen or boronic acid) and a subsequent functionalization or cross-coupling. Here we show that aromatic amines can be constructed by direct reaction of arenes and alkyl amines using photocatalysis, without the need for pre-functionalization. The process enables the easy preparation of advanced building blocks, tolerates a broad range of functionalities, and multigram scale can be achieved via a batch-to-flow protocol. The merit of this strategy as a late-stage functionalization platform has been demonstrated by the modification of several drugs, agrochemicals, peptides, chiral catalysts, polymers and organometallic complexes.
- Ruffoni, Alessandro,Juliá, Fabio,Svejstrup, Thomas D.,McMillan, Alastair J.,Douglas, James J.,Leonori, Daniele
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p. 426 - 433
(2019/05/01)
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- Tolane liquid crystals with piperidine, 3,3,4,4,5,5-hexafluoropiperidine as end group: Synthesis and properties
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A series of new tolane liquid crystals with piperidine and 3,3,4,4,5,5-hexafluoropiperidine as their terminal groups were synthesized via Sonagashira reaction by using Pd(PPh3)2Cl2/CuI as the catalyst. Their structures were modified by varying the terminal N-heterocycles and/or the length of the alkyl/alkoxy chains on the benzene ring. Most of these new compounds exhibit Smectic B or G mesophases, good thermal stabilities and high clearing points. The molecule C2H5O6F with 3,3,4,4,5,5-hexafluoropiperidine as the end group has a broader HOMO-LUMO energy gap and higher oxidation potential than piperidine derivative C2H5O6H. The result indicates that the oxidation resistance of the tolane liquid crystals was improved by introducing the terminal fluorinated piperidine.
- Zhu, Dezhao,Hong, Fengying,Zhang, Hong,Xia, Zhengce,Wu, Hongxiang,Jiang, Qiwei,Wang, Hui,Zeng, Zhuo
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- Fluorocarbon and hydrocarbon N-heterocyclic (C5-C7) imidazole-based liquid crystals
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By using three synthetic protocols, a series of fluorocarbon and hydrocarbon N-heterocyclic imidazolebased liquid crystals (LCs) and related imidazolium-based ionic liquid crystals (ILCs) have been prepared. The ring size of the N-heterocycle and the length of the N-terminal chain (on the imidazolium unit in the ILCs) were modified, and the influence of these structural parameters on liquid-crystal phases was investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). These new ILCs exhibit a disordered smectic phase (SmA), good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence relative to imidazole-based LCs. These encouraging results have led us to believe these fluorocarbon and hydrocarbon N-heterocyclic imidazole-based LCs and related imidazolium-based ILCs could be used as new liquid-crystalline materials.
- Chen, Hongren,Hong, Fengying,Shao, Guang,Hang, Deyu,Zhao, Lei,Zeng, Zhuo
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p. 3418 - 3430
(2015/01/09)
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- Copper-catalyzed amination of arylboronates with N,N-dialkylhydroxylamines
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A tolerant coupling: The title reaction has been developed to deliver arylamines (see scheme; Bz=benzoyl, dppbz=1,2-bis(diphenylphosphino)benzene). The catalysis is based on electrophilic, umpolung amination and enables the use of secondary acyclic amines. Various functional groups are tolerated, thus opening up a new substrate class for the Chan-Lam-type coupling.
- Matsuda, Naoki,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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p. 3642 - 3645
(2012/05/20)
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- Cu-Al hydrotalcite: An efficient and reusable ligand-free catalyst for the coupling of aryl chlorides with aliphatic, aromatic, and N(H)-heterocyclic amines
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Copper-aluminum hydrotalcite catalysts were effectively used in the coupling of aryl chlorides with aliphatic, aromatic, and N(H)-heterocyclic amines to afford the corresponding N-alkylated/arylated amines in excellent yields. The catalyst was quantitatively recovered from the reaction by simple filtration and reused for a number of cycles with almost consistent activity. Georg Thieme Verlag Stuttgart.
- Sreedhar,Arundhathi,Linga Reddy,Amarnath Reddy,Lakshmi Kantam
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experimental part
p. 2517 - 2522
(2010/03/24)
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- Microwave-assisted amination from aryl triflates without base and catalyst
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(Equation presented) Aryl triflates are effectively converted to the corresponding anilines under microwave irradiation in 1-methyl-2-pyridone (NMP) without base and catalyst. Aryl triflates substituted with both electron-poor and electron-rich groups give good to excellent yields. It is noteworthy that the halogenated aryl triflates can chemoselectively react with amines to afford halogenated anilines.
- Xu, Gang,Wang, Yan-Guang
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p. 985 - 987
(2007/10/03)
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- First synthesis and electrogenerated chemiluminescence of novel p-substituted phenyl-2-quinolinylethynes
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A series of p-substituted phenyl-2-quinolinylethynes as blue-green emitters were synthesized using a modified Sonogashira coupling reaction and their electrogenerated chemiluminescence properties are reported.
- Elangovan, Arumugasamy,Chen, Ting-Yu,Chen, Chih-Yuan,Ho, Tong-Ing
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p. 2146 - 2147
(2007/10/03)
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- Copper-catalyzed amination of aromatic halides with 2-N,N-dimethylaminoethanol as solvent
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A copper-catalyzed amination of aromatic halides under mild conditions using N,N-dimethylaminoethanol as solvent is described. We have studied this reaction in some detail varying the copper source, base, water content and other parameters including the scope of useful amine and aromatic halide structures. A variety of 4-halo-N,N-cycloalkylanilines and 2-N,N-cycloalkylaminothiophenes were synthesized for further elaboration into chromophores for optoelectronic applications.
- Lu, Zhikuan,Twieg, Robert J.,Huang, Songping D.
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p. 6289 - 6292
(2007/10/03)
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- Synthesis, Structure, and Spectral Behavior of Donor-Acceptor Substituted Biphenyls
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Reaction of the activated halonitrobenzenes 2a-f with the bis- and tris(dialkylamino)benzenes 1a-e affords, via a direct nucleophilic substitution, the highly substituted biphenyls 3a-o; the lesser substituted biphenyls 5 and 6 were prepared by an Ullmann reaction.All these biphenyls are deeply colored; the dark red color can be assigned to an intramolecular charge transfer.A crystal structure determination was carried out for 2,4,6-tripyrrolidino-2',4',6'-trinitrobiphenyl (3a): space group C2/c, a = 16.071 (2) Angstroem, b = 14.545 (1) Angstroem, c = 20.177 (2) Angstroem, β = 91.361 (9)deg, Z = 8 (temperature ca. 120 K).The dihedral angle between the two arene rings was found to be only 52.5 deg, despite the four bulky substituents in the o,o'-positions.With this far-from-orthogonal torsional angle about the biphenyl linkage, the strong intramolecular charge transfer from the ? system of the donor into the ? system of the acceptor arene becomes easily understandable.A PPP calculation with the torsional angles taken from the X-ray structure analysis satisfactorily reproduces the experimental absorption spectrum of 3a.The shift of the long-wavelength absorption between the individual biphenyls 3a-o, 5, and 6 likewise is accounted for satisfactorily by the calculation; it depends primarily on the intrinsic donor strength of the different NR2 moieties (pyrrolidino > dimethylamino > piperidino > morpholino).The 1H NMR spectra (in dilute solution) likewise mirror this gradation in NR2 donor capacity; they also show that steric hindrance at the biphenyl linkage is mainly the result of interaction between the o-dialkylamino groups and the C6 skeleton of the acceptor arene.This is borne out by the crystal structure analysis.
- Effenberger, Franz,Agster, Wolfgang,Fischer, Peter,Jogun, Kurt H.,Stezowski, John J.,et al.
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p. 4649 - 4658
(2007/10/02)
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