- Selective N-acetylation with concurrent S-oxidation of o-amino thiol at ambient conditions over Ce doped ZnO composite nanocrystallites
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The oxidative S–S coupling of thiol to disulfide is an imperative chemical transformation in the domain of biological processes and also finds numerous chemical applications. The CeO2 and ZnO are significant catalysts for oxidation of thiol to disulfide and N-acetylation of amines respectively. Dithiobis(phenylene)bis(benzyldeneimine) moiety containing N-acetyl and disulfide functional groups is a potential antimicrobial agent with Leishmanicidal and antihyperlipidemic activities. Herein, we report a synchronized catalytic application of Ce doped ZnO (Ce-ZnO) and CeO2-Ce-ZnO composites for selective synthesis of Dithiobis(phenylene)bis(benzyldeneimine) from o-amino thiol. The Ce-ZnO samples were synthesized by simple co precipitation method by calcination of hydroxide precursors at 400 °C to get 0–10% Ce-ZnO nanocrystallites. The formation of CeO2-Ce-ZnO composite material was observed beyond 1.5% Ce concentration. The synthesized materials were well characterized by IR, XRD, DRS spectroscopy and SEM-EDS analysis. The application of Ce doped ZnO as an efficient catalyst towards the selective N-acetylation and concurrent S-oxidation of o-amino thiol to afford Dithiobis(phenylene)bis(benzyldeneimine) at ambient temperature in acetonitrile was deliberated. Among all screened catalysts, the maximum selectivity was found for 7.5% Ce-ZnO as CeO2-Ce-ZnO composite catalyst. Lewis acidic property of catalyst supported probable mechanism for achieved dual transformations. Also, the 7.5% Ce-ZnO catalyst has demonstrated a versatile S–S coupling ability for variety of thiol substrates with excellent stability.
- Jagtap, Rohidas,Sakate, Sachin,Pardeshi, Satish
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- Synthesis of acetamides via oxidative C–C bond cleavage of ketones catalyzed by Cu-immobilized magnetic nanoparticles
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Copper supported on magnetite nanoparticles modified with environmentally friendly ligand tricine was devised for synthesis of acetamides via C–C oxidative cleavage of ketones with amines. The catalyst was characterized using different techniques, including Fourier transform infrared, X-ray diffraction, scannin electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, and energy dispersive x-ray spectroscopy. The protocol showed relatively high yields of acetamide products. Furthermore, the magnetic recovery of the catalyst rendered the overall process fast and efficient. It was used in the reaction for six consecutive cycles with negligible loss of catalytic activity. This research is the first report of application of magnetic nanocatalysts for synthesis of acetamides from ketones of low activity through a C–C bond cleavage strategy.
- Yazdani, Elahe,Pazoki, Farzane,Salamatmanesh, Arefe,Nejad, Masoume Jadidi,Miraki, Maryam Kazemi,Heydari, Akbar
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- Synthesis of diverse libraries of carboxamides via chemoselective N-acylation of amines by carboxylic acids employing Br?nsted acidic IL [BMIM(SO3H)][OTf]
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Chemoselective N-acylation of amines with carboxylic acids as acyl electrophiles and Br?nsted acidic IL [BMIM(SO3H)][OTf] as promoter is reported under both thermal and microwave irradiation to produce libraries of carboxamides in good to excellent yields after a simple workup. The protocol is compatible with structurally diverse 1° and 2° amines and works in the presence of sensitive functional groups such as thiols and phenols. The potential for recycling and reuse of the IL is also demonstrated.
- Savanur, Hemantkumar M.,Malunavar, Shruti S.,Prabhala, Pavankumar,Sutar, Suraj M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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supporting information
(2019/09/30)
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- Citric acid stabilized on the surface of magnetic nanoparticles as an efficient and recyclable catalyst for transamidation of carboxamides, phthalimide, urea and thiourea with amines under neat conditions
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Abstract: Citric acid-coated magnetic nanoparticles (Fe3O4–CA NPs) were successfully prepared and characterized. This magnetic nanocatalyst was employed as an efficient, recyclable, and environmentally benign heterogeneous catalyst for the transamidation of carboxamides, phthalimide, urea and thiourea with amines. Several derivatives of formylated and transamidated products were synthesized in good to excellent yields in the presence of this catalytic system. And, the catalyst could be easily separated from the reaction mixture using an external magnet and can be reused six times without any significant loss in its catalytic activity. Graphical abstract: [Figure not available: see fulltext.].
- Arefi, Marzban,Kazemi Miraki, Maryam,Mostafalu, Ramin,Satari, Mohammad,Heydari, Akbar
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p. 393 - 400
(2019/01/28)
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- Manganese-mediated acetylation of alcohols, phenols, thiols, and amines utilizing acetic anhydride
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Manganese(II) chloride-catalyzed acetylation of alcohols, phenols thiols and amines with acetic anhydride is reported. This method is environment-friendly and economically viable as it involves inexpensive, relatively benign catalyst, mild reaction condition, and simple workup. Acetylation is performed under the solvent-free condition at ambient temperature and acetylated products obtained in good to excellent yields. Primary, secondary heterocyclic amines, and phenols with various functional groups are smoothly acetylated in good yields. This method exhibits exquisite chemoselectivity, the amino group is preferentially acetylated in the presence of a hydroxyl/thiol group.
- Jain, Isha,Sharma, Ramandeep,Malik, Payal
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supporting information
p. 2952 - 2960
(2019/09/13)
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- Additive-free chemoselective acylation of amines
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Aliphatic and aromatic amines are efficiently acylated by acetic, pivalic, benzoic, phthalic, or maleic anhydrides in ethyl acetate at room temperature. Under the same experimental conditions, amino alcohols are chemoselectively acylated at the amino group.
- Temperini, Andrea,Terlizzi, Raffaella,Testaferri, Lorenzo,Tiecco, Marcello
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experimental part
p. 295 - 302
(2010/03/30)
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- Regioselective syntheses of 2- and 4-formylpyrido[2,1-b]benzoxazoles
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o-Acetaminophenols (2) reacted with Vilsmeier reagent under Meth-Cohn conditions to yield 2-formylpy-rido[2,l-6]benzoxazoles (5) unexpectedly besides the known compounds 2-(benzoxazol-2′-yl)-3-dimethylaminoacroleins (4). Refluxing 4 in acetic anhydride gave 4-formylpyrido[2,l-6]benzoxazoles (6), an isomer of 5. Both 5a and 6a were structurally characterized by X-ray crystallography. A mechanism for the formation of 5 involving sequential chlorination, dimerization, intramolecular elimination of HC1 to form the oxazole ring, formylation twice, and regioselective intramolecular nucleophilic cyclization to construct the pyridone ring is proposed.
- Li, Ke-Lai,Du, Zong-Bo,Guo, Can-Cheng,Chen, Qing-Yun
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supporting information; experimental part
p. 3286 - 3292
(2009/09/08)
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- Design, syntheses, and characterization of dioxo-molybdenum(vi) complexes with thiolate ligands: Effects of intraligand NH...S hydrogen bonding
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Presence of the hydrogen bonding near a metal center can influence the properties of the complex. Here, we describe changes in redox and spectral properties in discrete dioxo-molybdenum centers coordinated by a single thiolato ligand that can support an intra-ligand hydrogen bond. We have utilized thiophenolato ligands that can harbor hydrogen bonding between the thiophenolato sulfur with an amide functionality creating either a five- or a six-membered ring. Methylation of the amide functionality removes the NH...S hydrogen bonding thus providing a basis for understanding the effect of hydrogen bonding. These thiophenolato ligands have been used in synthesizing dioxo-MoVI complexes of type Tp*MoO2(S-o-RC6H4), where R = CONHMe (11), CONMe2 (12), NHCOMe (13), and N(Me)COMe (14). The complexes have been characterized by NMR, infrared, and UV-visible spectroscopy. Spectroscopic data clearly indicate the presence of hydrogen bonding in both 11 and 13, and stronger in 13, where hydrogen bonding stabilizes a five-membered ring. All complexes exhibit a MoVI/MoV redox couple and redox potentials are modulated by the nature of H-bonding. Compound 14 with the electron-releasing N(Me)COMe group has the highest reduction potential and is more difficult to reduce. The Royal Society of Chemistry.
- Sengar, Raghvendra S.,Miller, Jonathan J.,Basu, Partha
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p. 2569 - 2577
(2008/09/20)
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- Chemoselective acylation of amines in aqueous media
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Amines are efficiently acylated by both cyclic and acyclic anhydrides by dissolving them in an aqueous medium with the help of a surfactant, sodium dodecyl sulfate (SDS). Cyclic and acyclic anhydrides react with equal ease with an amine, and amines with various stereo-electronic factors react at the same rates with an anhydride. Chemoselective acylation of amines in the presence of phenols and thiols and of thiols in the presence of phenols has been achieved. No acidic or basic reagents are used during the reaction. No Chromatographic separation is required for isolation of the acylated products. Reactions in a neutral aqueous medium, easy isolation of products, and innocuous by-products make the present method a green chemical process. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Naik, Sarala,Bhattacharjya, Gitalee,Talukdar, Bandana,Patel, Bhisma K.
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p. 1254 - 1260
(2007/10/03)
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- Solid phase synthesis of benzothiazolyl compounds
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2-Aminobenzenethiol, bound through its thiol function to the 2-chlorotrityl (Clt)-, trityl (Trt)-, 4-methyltrityl (Mtt)- and 4-methoxytrityl (Mmt)-resins, was acylated at the amino-function by aliphatic and aromatic acids. The obtained 2-N-acyl-aminobenzenethiols were cleaved from the resin by treatment with trifluoroacetic acid solutions in dichloromethane. The 2-N-acyl-aminobenzenethiols released from the resin were cyclised to the corresponding 2-substituted benzothiazoles, by standing in a solution of dithiothreitol in DMF or methanol for 1-3 h at room temperature.
- Mourtas, Spyros,Gatos, Dimitrios,Barlos, Kleomenis
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p. 2201 - 2204
(2007/10/03)
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