- Increasing the Activity of Copper Guanidine Quinoline Catalysts: Substitution at the Quinoline Backbone Leads to Highly Active Complexes for ATRP
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Copper bromide complexes with the ligands TMG6NO2qu, TMG6Brqu, TMG6Methoxyqu, TMG6NMe2qu, TMG6EHOqu and TMG6dBAqu were examined regarding their activity in atom transfer radical polymerization (ATRP). The ligands were inspired by 1,1,3,3-tetramethyl-2-(quinolin-8-yl)guanidine (TMGqu) and the substituents have been chosen with a large range between electron withdrawing and donating abilities. The donor properties of the ligands can be strongly influenced and further highly active catalysts based on these systems can be obtained. The ligands with strong donating moieties were in addition modified by alkyl groups to increase the solubility in apolar monomers like styrene. CuI and CuII bromide complexes were crystallised and the structural data correlated to the different substituents and the catalyst activity. The electrochemical potentials E1/2, the equilibrium constants KATRP and rate constants kact and kdeact were determined. Polymerizations of styrene were conducted in solution whereas the catalyst based on TMG6EHOqu shows a good solubility and performance in bulk.
- Kr?ckert, Konstantin W.,Mannsperger, Johannes S.,R?sener, Thomas,Hoffmann, Alexander,Herres-Pawlis, Sonja
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supporting information
p. 832 - 842
(2021/03/31)
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- A novel construction of acetamides from rhodium-catalyzed aminocarbonylation of DMC with nitro compounds
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Dimethyl carbonate (DMC), an environment-friendly compound prepared from CO2, shows diverse reactivities. In this communication, an efficient procedure using DMC as both a C1 building block and solvent in the aminocarbonylation reaction with nitro compounds has been developed. W(CO)6acts both a CO source and a reductant here.
- Bao, Zhi-Peng,Miao, Ren-Guan,Qi, Xinxin,Wu, Xiao-Feng
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supporting information
p. 1955 - 1958
(2021/03/02)
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- Visible-light-induced Beckmann rearrangement by organic photoredox catalysis
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A facile and general strategy for efficient direct conversion of oximes to amides using an inexpensive organic photocatalyst and visible light is described. This radical Beckmann rearrangement can be performed under mild conditions. Various alkyl aryl ketoximes and diaryl ketoximes can be effectively converted into the corresponding amides in excellent yields.
- Tang, Li,Wang, Zhi-Lv,Wan, Hai-Lan,He, Yan-Hong,Guan, Zhi
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supporting information
p. 6182 - 6186
(2020/09/01)
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- A one pot protocol to convert nitro-arenes into: N-aryl amides
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A two-step one pot, experimentally simple protocol, based on readily available and inexpensive reagents allowed the conversion of nitro-arenes directly to N-aryl amides. A metal-free reduction of the nitro group, mediated by trichlorosilane, followed by the addition of an anhydride afforded the corresponding N-aryl carboxyamide, that was isolated after a simple aqueous work up in good-excellent yields. When the methodology was applied to the reaction with γ-butyrolactone, the desired N-aryl butanamide derivative was obtained, featuring a chlorine atom at the γ-position, a functionalized handle that can be used for further synthetic manipulation of the reaction product. Such an intermediate has already been employed as a key advanced precursor of pharmaceutically active compounds.
- Massolo, Elisabetta,Pirola, Margherita,Puglisi, Alessandra,Rossi, Sergio,Benaglia, Maurizio
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p. 4040 - 4044
(2020/02/04)
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- An Electrochemical Beckmann Rearrangement: Traditional Reaction via Modern Radical Mechanism
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Abstract: Electrosynthesis as a potential means of introducing heteroatoms into the carbon framework is rarely studied. Herein, the electrochemical Beckmann rearrangement, i. e. the direct electrolysis of ketoximes to amides, is presented for the first time. Using a constant current as the driving force, the reaction can be easily carried out under neutral conditions at room temperature. Based on a series of mechanistic studies, a novel radical Beckmann rearrangement mechanism is proposed. This electrochemical Beckmann rearrangement does not follow the trans-migration rule of the classical Beckmann rearrangement.
- Tang, Li,Wang, Zhi-Lv,He, Yan-Hong,Guan, Zhi
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p. 4929 - 4936
(2020/08/21)
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- COMPOSITION FOR PREVENTING OR TREATING HAIR LOSS INCLUDING BENZENE DIAMINE DERIVATIVE
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Provided are a compound represented by the following Formula I, or a solvate, stereoisomer, or pharmaceutically acceptable salt thereof, and a composition for preventing or treating hair loss, the compound including the compound as an active ingredient:
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Paragraph 0057; 0068-0069
(2019/04/14)
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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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- Direct synthesis of N-arylamides via the coupling of aryl diazonium tetrafluoroborates and nitriles under transition-metal-free conditions
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The direct synthesis of N-arylamides via the coupling of aryl diazonium tetrafluoroborates and nitriles under transition-metal-free conditions has been developed. The reported protocol is practical and represents an efficient method to produce functionalized amides in moderate to good yields.
- Xiong, Biquan,Wang, Gang,Xiong, Tao,Wan, Liming,Zhou, Congshan,Liu, Yu,Zhang, Panliang,Yang, Changan,Tang, Kewen
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supporting information
p. 3139 - 3142
(2018/07/13)
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- Selective Oxidative Coupling Reaction of Isocyanides Using Peroxide as Switchable Alkylating and Alkoxylating Reagent
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A switchable oxidative coupling reaction of isocyanide and peroxide has been disclosed. In the presence of iron catalyst, the coupling reaction affords N-arylacetamides in good yields. By simply replacing the iron with copper catalyst, another different coupling reaction takes place in which peroxide can serve as alkoxylating source. This protocol represents a new fundamental coupling of two basic chemicals involving C?C and C?O bond-forming process. The unusual reactivity of an isocyano group in a radical reaction acting formally as an amidoyl synthon has also been well established. The experiment outcome reveals that aromatic isocyanides are particularly compatible reaction partners in present coupling reaction, whereas no desired products are observed when aliphatic isocyanides are used. (Figure presented.).
- Zhang, Xinglu,Liu, Zhiqiang,Gao, Yu,Li, Feng,Tian, Yaming,Li, Chunju,Jia, Xueshun,Li, Jian
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supporting information
p. 272 - 277
(2017/11/13)
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- Ligand-directed selective protein modification based on local single-electron-transfer catalysis
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A photocatalyst ([Ru(bpy)3]2+) bound to a protein ligand was essential for the title method. Local single-electron transfer from the catalyst resulted in the formation of tyrosyl radicals. N′-Acetyl-N,N- dimethyl-1,4-phenylenediamine was used as the tyrosyl radical trapping agent and used in a radical addition to afford selective modification of the target protein. Copyright
- Sato, Shinichi,Nakamura, Hiroyuki
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supporting information
p. 8681 - 8684
(2013/09/12)
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- One-pot synthesis of N,N-dimethylanilines from nitroarenes with skeletal Cu as chemoselective catalyst
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A range of N,N-dimethylanilines were synthesized with excellent yields in one-pot by the hydrogenation and alkylation of nitroarenes with H2 and HCHO over quenched skeletal Cu catalyst, which provides a facile, economical, and environmentally benign alternative methodology for C-N bonds formation.
- Rong, Zeming,Zhang, Wenjun,Zhang, Peng,Sun, Zhuohua,Lv, Jinkun,Du, Wenqiang,Wang, Yue
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p. 115 - 118
(2013/09/02)
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- An efficient catalytic method for the Beckmann rearrangement of ketoximes to amides and aldoximes to nitriles mediated by propylphosphonic anhydride (T3P)
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An efficient method for the Beckmann rearrangement of ketoximes to amides mediated by a catalytic amount (15 mol %) of propylphosphonic anhydride (T3P) is described. Aldoximes underwent second order Beckmann rearrangement to provide the corresponding nitriles in excellent yields on reacting with T3P (15 mol %) at room temperature. The main advantages of this environmentally friendly protocol include procedural simplicity, and particularly ease of isolation of the products.
- Augustine, John Kallikat,Kumar, Rajesha,Bombrun, Agnes,Mandal, Ashis Baran
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scheme or table
p. 1074 - 1077
(2011/03/22)
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- Using phenyl cations as probes for establishing electrophilicity - Nucleophilicity relations
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(Chemical Equation Presented) N,N-Dimethyl-4-aminophenyl cation is used as an electrophilic probe for determining the relative reactivity of nucleophiles. The singlet state (11) of this cation is completely unselective (reaction rates with benzene, MeCN, and trifluoroethanol within a factor of 5). The corresponding triplet (31) does not react with alcohols and MeCN. The rates of reaction of the latter intermediate with 23 π, σ, and n nucleophiles are measured by competition experiments and found to vary over only 2 orders of magnitude over a range of 22 units of the nucleophilicity parameter N introduced by Mayr. As far as one can judge with the considerable scatter of the data, fitting the data of both amines and π nucleophiles is possible only by using a modified Mayr's equation: log k = s(E + eN) with e = 0.33. The reduced dependence on N is explained by the fact that in the case of diradicalic triplet 31 interaction with the nucleophile involves a half-filled (σ) orbital, which is empty in singlet 11. It is suggested that Mayr's equation can be extended to quite diverse reactions, but a scaling factor of e 1 may have to be introduced in some cases, according to the electronic structure of the electrophilic probe used.
- Dichiarante, Valentina,Fagnoni, Maurizio,Albini, Angelo
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p. 1282 - 1289
(2008/09/16)
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- (Sensitized) photolysis of diazonium salts as a mild general method for the generation of aryl cations. Chemoselectivity of the singlet and triplet 4-substituted phenyl cations
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(Chemical Equation Presented) The photolysis of a series of 4-X-benzenediazonium tetrafluoroborates is studied in MeCN. Loss of nitrogen occurs from the singlet excited state with X = H, t-Bu, and NMe2 and leads to the singlet aryl cation. This adds to the solvent yielding the corresponding acetanilides. With other substituents, ISC competes with (X = Br, CN) or overcomes (X = COMe, NO2) fragmentation and the aryl cation is formed in part or completely in the triplet state. In neat MeCN, this either abstracts hydrogen from the solvent (in most cases inefficiently) or undergoes intersystem crossing to the more stable singlet that reacts as above. In the presence of π nucleophiles (allyltrimethylsilane or benzene), the triplet aryl cation is efficiently trapped giving substituted allylbenzenes and biphenyls, respectively. By triplet sensitization by xanthone, the triplet cation and the products from it are obtained from the whole series considered. The direct or sensitized photodecomposition of diazonium fluoroborates, substituted with both electron-donating and -withdrawing substituents, in the presence of alkenes and arenes offers an access to an alternative arylation procedure.
- Milanesi, Silvia,Fagnoni, Maurizio,Albini, Angeld
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p. 603 - 610
(2007/10/03)
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- Cationic arylation through photo(sensitised) decomposition of diazonium salts. Chemoselectivity of triplet phenyl cations
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The photodediazoniation of some 4-X-phenyldiazonium tetrafluoborates in MeCN leads to the singlet phenyl cations (X = H, tert-butyl, NMe2, CN), which add to the solvent yielding the corresponding acetanilides. Triplet sensitisation, however, leads to the triplet phenyl cation, which is reduced in neat solvent and is trapped by π nucleophiles (allyltrimethylsilane and benzene), resulting in an ionic analogue of the Meerwein or Gomberg arylations. With the 4-nitro derivative intersystem crossing prevails over dediazoniation from the singlet and with the 4-cyano competes with it, so that in those cases the triplet phenyl cation is formed also upon direct irradiation.
- Milanesi, Silvia,Fagnoni, Maurizio,Albini, Angelo
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p. 216 - 217
(2007/10/03)
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- Intramolecular electron transfer across amino acid spacers in the picosecond time regime. Charge-transfer interaction through peptide bonds
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For a series of alanine-based peptides having 1-3 amino acid residues as spacers, the chromophore, pyrenesulfonyl (Pyr), has been attached at the N-terminus and an electron donor, dimethyl-1,4-benzenediamine (DMPD), covalently bound at the C-terminus. Evidence for an intramolecular charge-transfer interaction involving the electron donor and acceptor groups has been obtained from absorption spectra. Intramolecular electron transfer involving the end groups, Pyr (electron acceptor) and DMPD (electron donor) has been confirmed by ultrafast pump-probe methods. The radical-ion pair states that are generated on Ti/sapphire laser excitation at 400 nm decay in the picosecond to nanosecond time domain and generally show multiexponential decay kinetics. These rates of charge recombination are among the fastest yet observed involving electron transfer between terminal groups for peptide oligomers. The falloff of rate constants for ion pair recombination is irregular in terms of the through-bond distance that separates Pyr and DMPD groups for the various peptide links; i.e., back electron transfer remains fast for the tripeptide, Pyr-Ala-Ala-Ala-DMPD, despite an average through-bond distance between photoactive groups that reaches 18 Aì?. Molecular modeling studies show that the peptides are free to adopt conformations in essentially random fashion, without showing evidence for long range ordering of the peptide chain. ? 1999 American Chemical Society.
- Jones II, Guilford,Lu, Lily N.,Fu, Hongning,Farahat, Catie W.,Oh, Churl,Greenfield, Scott R.,Gosztola, David J.,Wasielewski, Michael R.
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p. 572 - 581
(2007/10/03)
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- Borohydride reductions in dichloromethane: A convenient, environmentally compatible procedure for the methylation of amines
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The combination of zinc chloride and sodium borohydride in dichloromethane is used to effect reductive aminations of formaldehyde with a variety of primary and secondary amines containing potentially acid-sensitive functional groups in good to excellent yields.
- Bhattacharyya
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p. 2061 - 2069
(2007/10/02)
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- Use of Zinc Borohydride in Reductive Amination: An Efficient and Mild Method for N-Methylation of Amines
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An efficient method for the reductive methylation of amines using paraformaldehyde, zinc chloride and zinc borohydride is described.
- Bhattacharyya, Sukanta,Chatterjee, Arindam,Duttachowdhury, Shiti, Kantha
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- SYNTHETIC METHODS. PART 23. REARRANGEMENT OF SOME HYDROXAMIC ACIDS INTO AMIDES. A SELF-CONDENSATION LEADING TO DISPROPORTIONATION
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Pyruvic acids have been shown to react with p-nitroso-N,N-dimethylaniline (1) to produce p-dimethyl-aminoacetanilides (3) via the corresponding hydroxamic acids (4).Three such intermediates (4a, c, d) have been isolated and their structure proved by n.m.r. and mass spectroscopy and elemental analysis.Solutions of the hydroxamic acids (4) have been shown to undergo concentration-dependent self-condensation and disproportionation leading to the amides (3) and acids (5).Rational pathways for these transformations are discussed.Spectral correlations permit differentiation between the amides (3) and the corresponding hydroxamic acids (4).
- Hassner, Alfred,Ruse, Margareta,Gottlieb, Hugo E.,Cojocaru, Miriam
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p. 733 - 738
(2007/10/02)
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