- The Fragmentation of 5- and 3-Substituted Thiophene-2-carboxamides Under Electron Impact
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The 70 eV electron impact mass spectra of twelve 5- and 3-substituted thiophene-2-carboxamides are discussed with the aid of exact mass measurements and labelling experiments.All mass spectra exhibit pronounced molecular ions.Some isomeric 5- and 3-substituted title compounds can be differentiated by mass spectrometry.The fragmentation is influenced by a strong 'ortho-effect' which activates the NH3 elimination.In the other cases the most important fragmentation is NH2. loss, followed by CO elimination.
- Occhipinti, Salvatore,Alberghina, Gaetano,Fisichella, Salvatore,Puglisi, Orazio,Ceraulo, Leopoldo
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- Preparation method of thieno[2,3-c]pyridine-7(6h)-ketone
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The invention discloses a preparation method of thieno[2,3-c]pyridine-7(6h)-ketone, belonging to a thienopyridine compound. According to the technical key points, the preparation method comprises thefollowing operation steps of: adding 3-methylthiophene-2-formamide to tetrahydrofuran, then adding DMF-DMA, completely reacting after carrying out heating reflux for 2 to 3 hours, boiling off the tetrahydrofuran and the DMF-DMA under reduced pressured to obtain an oily matter; then adding the oily matter to the tetrahydrofuran, adding alkali in batches, carrying out heating reflux for 1.5-3 hourstill completely reacting, boiling off the tetrahydrofuran, adding 400 to 500ml of water and stirring for 1-2 hours, filtering and drying to obtain the thieno[2,3-c]pyridine-7(6h)-ketone. The preparation method has the beneficial effects that raw materials have relatively low price, the operation steps are simple, and the safety performance in the preparation process is improved.
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- Stable and reusable nanoscale Fe2O3-catalyzed aerobic oxidation process for the selective synthesis of nitriles and primary amides
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The sustainable introduction of nitrogen moieties in the form of nitrile or amide groups in functionalized molecules is of fundamental interest because nitrogen-containing motifs are found in a large number of life science molecules, natural products and materials. Hence, the synthesis and functionalization of nitriles and amides from easily available starting materials using cost-effective catalysts and green reagents is highly desired. In this regard, herein we report the nanoscale iron oxide-catalyzed environmentally benign synthesis of nitriles and primary amides from aldehydes and aqueous ammonia in the presence of 1 bar O2 or air. Under mild reaction conditions, this iron-catalyzed aerobic oxidation process proceeds to synthesise functionalized and structurally diverse aromatic, aliphatic and heterocyclic nitriles. Additionally, applying this iron-based protocol, primary amides have also been prepared in a water medium.
- Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Sohail, Manzar,Sharif, Muhammad,Kalevaru, Narayana V.,Jagadeesh, Rajenahally V.
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supporting information
p. 266 - 273
(2018/01/12)
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- Highly efficient synthesis of primary amides: Via aldoximes rearrangement in water under air atmosphere catalyzed by an ionic ruthenium pincer complex
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The transformation of aldoximes to primary amides has been evaluated using pincer ruthenium complexes a-c, among which the ionic Ru catalyst a proved to be the most efficient in water under air atmosphere. A variety of (hetero)arene aldoximes proceeded smoothly to afford amides in high yields with good functional group compatibilities. Furthermore, a direct synthetic route of amides from aldehydes, hydroxylamine hydrochloride and sodium carbonate was also described with broad substrates including conjugated and aliphatic aldehydes. This protocol is operationally simple and proceeds with a low catalyst loading (0.5 mol%).
- Yang, Fa-Liu,Zhu, Xinju,Rao, Dun-Kang,Cao, Xiao-Niu,Li, Ke,Xu, Yan,Hao, Xin-Qi,Song, Mao-Ping
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p. 37093 - 37098
(2016/05/24)
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- Ruthenium(II) complexes bearing pyridine-functionalized N-heterocyclic carbene ligands: Synthesis, structure and catalytic application over amide synthesis
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A series of four imidazolium salts was synthesized by the reaction of 2-bromopyridine with 1-substituted imidazoles. These imidazolium salts (1a–d) were successfully employed as ligand precursors for the syntheses of new ruthenium(II) complexes bearing neutral bidentate ligands of N-heterocyclic carbene and pyridine donor moiety. The NHC-ruthenium(II) complexes (3a–d) were synthesized by reacting the appropriately substituted pyridine-functionalized N-heterocyclic carbenes with Ag2O forming the NHC–silver bromide in situ followed by transmetalation with [RuHCl(CO)(PPh3)3]. The new complexes were characterized by elemental analyses and spectroscopy (IR, UV-Vis,1H,13C,31P-NMR) as well as ESI mass spectrometry. Based on the spectral results, an octahedral geometry was assigned for all the complexes. The complexes were shown to be efficient catalysts for the one-pot conversion of various aldehydes to their corresponding primary amides with good to excellent isolated yields using NH2OH.HCl and NaHCO3. The effects of solvent, base, temperature, time and catalyst loading were also investigated. A broad range of amides were successfully synthesized with excellent isolated yields using the above optimized protocol. Notably, the complex 3a was found to be a very efficient and versatile catalyst towards amidation of a wide range of aldehydes. [Figure not available: see fulltext.]
- Nirmala, Muthukumaran,Viswanathamurthi, Periasamy
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p. 1725 - 1735
(2017/03/08)
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- Direct oxidative esterification of alcohols and hydration of nitriles catalyzed by a reusable silver nanoparticle grafted onto mesoporous polymelamine formaldehyde (AgNPs@mPMF)
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A nitrogen-rich mesoporous organic polymer was synthesized as a novel support. A silver nanoparticle was synthesized and grafted onto it. The prepared catalyst (AgNPs@mPMF) was characterized by powder X-ray diffraction (XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectrometry (EDS), thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (DRS), N2 adsorption, Raman spectroscopy and EPR study. The catalytic activity was evaluated for the oxidative esterification reaction of alcohols and hydration of nitriles. The oxidative esterification reaction was carried out for various activated alcohols giving excellent yields of the corresponding ester products. The catalyst was also efficient in the hydration of nitriles. Both reactions were optimized by varying the bases, temperatures and solvents. The catalyst can be facilely recovered and reused six times without a significant decrease in its activity and selectivity.
- Ghosh, Kajari,Iqubal, Md. Asif,Molla, Rostam Ali,Mishra, Ashutosh,Kamaluddin,Islam, Sk Manirul
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p. 1606 - 1622
(2015/04/27)
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- Polymer-anchored Ru(II) complex as an efficient catalyst for the synthesis of primary amides from nitriles and of secondary amides from alcohols and amines
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A polymer-anchored ruthenium(II) catalyst was synthesized and characterized. Its catalytic activity was evaluated for the preparation of primary amides from aqueous hydration of nitriles in neutral condition. A range of nitriles were successfully converted to their corresponding amides in good to excellent yields. The catalyst was also effective in the preparation of secondary amides from the coupling of alcohols and amines. The catalyst can be facilely recovered and reused six times without a significant decrease in its activity.
- Islam, Sk Manirul,Ghosh, Kajari,Roy, Anupam Singha,Molla, Rostam Ali
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p. 900 - 907
(2015/02/19)
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- Transition metal-free synthesis of primary amides from aldehydes and hydroxylamine hydrochloride
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Primary aromatic amides can be synthesized from aldehydes and hydroxylamine hydrochloride in the presence of Cs2CO3. Various aromatic aldehydes (include some heteroaromatic aldehydes) are able to generate the corresponding aromatic amides in moderate to excellent yields.
- Wang, Wei,Zhao, Xue-Mei,Wang, Jing-Li,Geng, Xin,Gong, Jun-Fang,Hao, Xin-Qi,Song, Mao-Ping
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supporting information
p. 3192 - 3194
(2014/05/20)
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- Green halogenation of aromatic heterocycles using ammonium halide and hydrogen peroxide in acetic acid solvent
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The green generation of X+ (X = Br, I) using hydrogen peroxide in aqueous acetic acid allows access to aromatic heterocyclic halides in yields and purities comparable to syntheses employing N-bromosuccinimide. In activated and unsubstituted thiophene rings, regioselectivity is quantitative for positions α to the sulfur; pyrroles also give quantitative reactions, at least initially. Deactivated rings, including furans and thiazoles, as well as thiophenes with strongly electron-withdrawing groups showed little to no reactivity under the conditions investigated. The reaction shows remarkable functional group tolerance (to alcohol, nitro, alkyl, halo, and carbonyl groups), as shown through reaction with substituted phenols. In all bromination reactions, reaction yields and regiochemistry were very similar to reactions involving N-bromosuccinimide in tetrahydrofuran solvent.
- D'Aleo, Danielle N.,Allard, Sheena R.,Foglia, Cassandra C.,Parent, Shawna L.M.,Rohr, David J.,Gottardo, Christine,MacKinnon, Craig D.
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p. 679 - 683
(2013/08/23)
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