- Unprecedented Dearomatized Spirocyclopropane in a Sequential Rhodium(III)-Catalyzed C?H Activation and Rearrangement Reaction
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An unprecedented dearomatized spirocyclopropane intermediate was discovered in a sequential Cp*RhIII-catalyzed C?H activation and Wagner–Meerwein-type rearrangement reaction. How the oxidative O?N bond is cleaved and the role of HOAc were uncov
- Wang, Xiaoming,Li, Yingzi,Knecht, Tobias,Daniliuc, Constantin G.,Houk,Glorius, Frank
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- 1-8H-pyrano[3,2-g]benzoxazol-8-ones from 7-methoxyimino-4-methylchromene-2,8-dione
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7-Methoxyimino-4-methylchromene-2,8-dione 3, easily prepared from the quinone 1 reacts thermally with methylaromatics 5(a-g), benzyl derivatives 13(a-c), halo derivatives 14(a-c) to give mainly oxazolocoumarins. Products 8(a-d) are obtained from 5(a-d), 13(a-c). Compound 9 is obtained from 5(a-c) and 13(a-c), compounds 15(a-c) are obtained from 14(a-c), the aminophenol 10 and coumarin 16 are obtained from 5f and 14c respectively, while coumarin 12 is obtained from 5g. The reaction of 3 with N-methyl-aniline and N,N-dimethylbenzylamine gives compound 10 and 8a respectively.
- Nicolaides, Demetrios N.,Bezergiannidou-Balouctsi, Catherine,Litinas, Konstantinos E.,Malamidou-Xenikaki, Elizabeth,Mentzafos, Demetrios,Terzis, Aris
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- Ethyl 2-Cyano-2-(2-nitrobenzenesulfonyloxyimino) Acetate (ortho-NosylOXY)-Mediated Double Beckmann Rearrangement of Ketoximes under Microwave Irradiation: A Mechanistic Perception
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A method for Beckmann rearrangement using ethyl 2-cyano-2-(2-nitrobenzenesulfonyloxyimino) acetate (o-NosylOXY) under microwave irradiation is reported. Ketoximes (19 examples) are converted to the corresponding amides/lactams with 69–97% yields in ~10 minutes without any Lewis acid or co-catalyst. This is an example of halogen-free organocatalytic Beckmann rearrangement. Nuclear magnetic resonance (NMR)- and high-resolution mass spectrometry (HRMS)-based detailed mechanistic investigation suggest that o-NosylOXY acts as an initiator. Such initiators are reported before based on density functional theory (DFT) calculations. However, we report here the HRMS signatures of two transient intermediates, the nitrilium ion and the nitrilium ion's dimeric species. Rigorous NMR-based investigation of the reaction mechanism is performed. Our results indicate that the reported Beckmann rearrangement proceeds via two consecutive rearrangements. (Figure presented.).
- Dev, Dharm,Kalita, Tapasi,Mondal, Tanmay,Mandal, Bhubaneswar
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p. 1427 - 1435
(2021/01/04)
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- Synthesis method of 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane
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The invention discloses a synthesis method of 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, which comprises the following steps: acetylating o-aminophenol serving as a starting material to obtain o-acetamidophenol, condensing the o-acetamidophenol with hexafluoroacetone trihydrate to obtain 2, 2-bis (3-acetamido-4-hydroxyphenyl) hexafluoropropane, and finally deacetylating to obtain the 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane. The synthetic route does not need catalytic hydrogenation or nitration, and compared with the existing route for synthesizing 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, the synthetic route provided by the invention has the advantages of higher safety, more environmental friendliness, lower production cost and basically equivalent yield, thereby being more suitable for industrial mass production.
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Paragraph 0030-0032; 0037-0039
(2021/04/29)
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- Antimalarial Benzimidazole Derivatives Incorporating Phenolic Mannich Base Side Chains Inhibit Microtubule and Hemozoin Formation: Structure-Activity Relationship and in Vivo Oral Efficacy Studies
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A novel series of antimalarial benzimidazole derivatives incorporating phenolic Mannich base side chains at the C2 position, which possess dual asexual blood and sexual stage activities, is presented. Structure-activity relationship studies revealed that the 1-benzylbenzimidazole analogues possessed submicromolar asexual blood and sexual stage activities in contrast to the 1H-benzimidazole analogues, which were only active against asexual blood stage (ABS) parasites. Further, the former demonstrated microtubule inhibitory activity in ABS parasites but more significantly in stage II/III gametocytes. In addition to being bona fide inhibitors of hemozoin formation, the 1H-benzimidazole analogues also showed inhibitory effects on microtubules. In vivo efficacy studies in Plasmodium berghei-infected mice revealed that the frontrunner compound 41 exhibited high efficacy (98% reduction in parasitemia) when dosed orally at 4 × 50 mg/kg. Generally, the compounds were noncytotoxic to mammalian cells.
- Dziwornu, Godwin Akpeko,Coertzen, Dina,Leshabane, Meta,Korkor, Constance M.,Cloete, Cleavon K.,Njoroge, Mathew,Gibhard, Liezl,Lawrence, Nina,Reader, Janette,Van Der Watt, Mari?tte,Wittlin, Sergio,Birkholtz, Lyn-Marie,Chibale, Kelly
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supporting information
p. 5198 - 5215
(2021/05/06)
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- Paracetamol and other acetanilide analogs as inter-molecular hydrogen bonding assisted diamagnetic CEST MRI contrast agents
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Paracetamol and a few other acetanilide derivatives are reported as a special class of diamagnetic Chemical Exchange Saturation Transfer (diaCEST) MRI contrast agents, that exhibit contrast only when the molecules form inter-molecular hydrogen bonding mediated molecular chains or sheets. Without the protection of the hydrogen bonding their contrast producing labile proton exchanges too quickly with the solvent to produce any appreciable contrast. Through a number of variable temperature experiments we demonstrate that under the conditions when the hydrogen bond network breaks and the high exchange returns back, the contrast drops quickly. The well-known analgesic drug paracetamol shows 12% contrast at a concentration of 15 mM at physiological conditions. With the proven safety track-record for human consumption and appreciable physiological contrast, paracetamol shows promise as a diaCEST agent forin vivostudies.
- Chakraborty, Subhayan,Peruncheralathan,Ghosh, Arindam
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p. 6526 - 6534
(2021/02/21)
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- The mechanism of organic radical oxidation catalysed by gold nanoparticles
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Metal nanoparticles can catalyze reactions involving organic free radicals. From the first studies focused on the catalytic reduction of water by free radicals until today, the catalytic oxidation of organic radicals has not received attention. In this work, we present the results on the catalytic activity of gold nanoparticles in the oxidation of 2-propanol to acetone and acetanilide hydroxylation during water radiolysis. A detailed reaction mechanism of α-hydroxyisopropyl radical oxidation is discussed, explaining the increase in acetone formation by ca. 340% in the presence of gold nanoparticles. In the case of acetanilide hydroxylation in the presence of nanoparticles, a strong effect of oxygen in the reaction mechanism was observed: The increase in the oxygen concentration from 0 to 1.22 mM leads to a 40-fold decrease in hydroxylation product formation. This observation is unexpected since, in the absence of gold nanoparticles, oxygen stimulates hydroxylation reactions. We propose that in the presence of both oxygen and nanoparticles, oxygen attaches first to acetanilide OH-Adducts, and then nanoparticles catalyze the oxidation of peroxyl type radicals, which does not lead to the formation of hydroxylation products.
- Denisov, Sergey A.,Mostafavi, Mehran,Shcherbakov, Viacheslav
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p. 26494 - 26500
(2021/12/13)
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- An Environmentally Benign, Catalyst-Free N?C Bond Cleavage/Formation of Primary, Secondary, and Tertiary Unactivated Amides
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Herein, we report an operationally simple, cheap, and catalyst-free method for the transamidation of a diverse range of unactivated amides furnishing the desired products in excellent yields. This protocol is environmentally friendly and operates under extremely mild conditions without using any promoter or additives. Significantly, this strategy has been implied in the chemoselective synthesis of a pharmaceutical molecule, paracetamol, on a gram-scale with excellent yield. We anticipate that this universally applicable strategy will be of great interest in drug discovery, biochemistry, and organic synthesis.
- Kumar, Vishal,Dhawan, Sanjeev,Girase, Pankaj Sanjay,Singh, Parvesh,Karpoormath, Rajshekhar
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p. 5627 - 5639
(2021/11/11)
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- Copper-free Sandmeyer-type Reaction for the Synthesis of Sulfonyl Fluorides
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A copper-free Sandmeyer-type fluorosulfonylation reaction is reported. Utilizing Na2S2O5 and Selectfluor as the sulfur dioxide and fluorine sources, respectively, aryldiazonium salts were transformed into sulfonyl fluorides. The one-pot direct synthesis of sulfonyl fluorides from aromatic amines was also realized via in situ diazotization. The practicality of this method was demonstrated by the broad functional group tolerance, gram-scale synthesis, and late-stage fluorosulfonylation of natural products and pharmaceuticals.
- Zhong, Tao,Pang, Meng-Ke,Chen, Zhi-Da,Zhang, Bin,Weng, Jiang,Lu, Gui
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supporting information
p. 3072 - 3078
(2020/04/10)
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- An organocatalytic C-C bond cleavage approach: A metal-free and peroxide-free facile method for the synthesis of amide derivatives
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A facile organocatalytic approach has been devised towards the synthesis of amide derivatives using 1,3-dicarbonyls as easily available acyl-sources under peroxide-free reaction conditions. This transformation was accomplished by the cleavage of the C-C bond in the presence of TEMPO as an organocatalyst and excludes the use of transition-metals and harsh reaction conditions. A broad range of substrates with diverse functional groups were well tolerated and delivered the products in high yields.
- Vodnala, Nagaraju,Gujjarappa, Raghuram,Polina, Saibabu,Satheesh, Vanaparthi,Kaldhi, Dhananjaya,Kabi, Arup K.,Malakar, Chandi C.
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supporting information
p. 20940 - 20944
(2020/12/31)
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- Method for preparing N-(3-acetyl-2-hydroxyphenyl)acetamide
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The invention relates to the technical field of organic synthesis and medicine, and provides a method for preparing N-(3-acetyl-2-hydroxyphenyl)acetamide. According to the method, 2-aminophenol is adopted as an initial raw material, amidogen acetylation and a methylation reaction of phenolic hydroxyl groups are firstly carried out, then bromination on benzene rings is carried out, acetyl is introduced, reductive debromination is finally carried out, a target product is obtained, and the total yield reaches up to 41.7%. In the process of generating a compound E through a compound D, the compound D is subjected to ether bond cracking, and can react with acetylchloride to generate phenolic ester, and then a rearrangement reaction occurs. According to the method, the raw material is wide in source and easy to obtain, the path can be industrialized easily, fewer impurities are generated, the yield is high, and the purity of the target product is effectively improved.
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Paragraph 0036; 0038-0039; 0049; 0051-0052
(2019/07/04)
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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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- Synthesis of Emissive Heteroacene Derivatives via Nucleophilic Aromatic Substitution
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A synthetic approach for preparing a variety of heterocyclic tetrahydropentacene derivatives via nucleophilic aromatic substitution reactions of bidentate nucleophiles and tetrafluoroterephthalonitrile was developed. X-ray crystallography of several products revealed that the compounds containing oxygen and nitrogen heteroatoms are highly planar and engage in π-stacking, while the compounds containing sulfur are bent and do not stack as effectively. The compounds were also highly emissive, and the heteroatom had a significant impact on the emission and electrochemical properties.
- Hiscock, Lana K.,Yao, Chengzhang,Skene,Dawe, Louise N.,Maly, Kenneth E.
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p. 15530 - 15537
(2019/11/19)
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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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- Metal-free formal synthesis of phenoxazine
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A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.
- Kervefors, Gabriella,Becker, Antonia,Dey, Chandan,Olofsson, Berit
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supporting information
p. 1491 - 1497
(2018/07/05)
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- Design and Synthesis of Novel Deuterated Ligands Functionally Selective for the γ-Aminobutyric Acid Type A Receptor (GABAAR) α6 Subtype with Improved Metabolic Stability and Enhanced Bioavailability
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Recent reports indicate that α6β2/3γ2 GABAAR selective ligands may be important for the treatment of trigeminal activation-related pain and neuropsychiatric disorders with sensori-motor gating deficits. Based on 3 functionally α6β2/3γ2 GABAAR selective pyrazoloquinolinones, 42 novel analogs were synthesized, and their in vitro metabolic stability and cytotoxicity as well as their in vivo pharmacokinetics, basic behavioral pharmacology, and effects on locomotion were investigated. Incorporation of deuterium into the methoxy substituents of the ligands increased their duration of action via improved metabolic stability and bioavailability, while their selectivity for the GABAAR α6 subtype was retained. 8b was identified as the lead compound with a substantially improved pharmacokinetic profile. The ligands allosterically modulated diazepam insensitive α6β2/3γ2 GABAARs and were functionally silent at diazepam sensitive α1β2/3γ2 GABAARs, thus no sedation was detected. In addition, these analogs were not cytotoxic, which render them interesting candidates for treatment of CNS disorders mediated by GABAAR α6β2/3γ2 subtypes.
- Knutson, Daniel E.,Kodali, Revathi,Divovi?, Branka,Treven, Marco,Stephen, Michael R.,Zahn, Nicolas M.,Dobri?i?, Vladimir,Huber, Alec T.,Meirelles, Matheus A.,Verma, Ranjit S.,Wimmer, Laurin,Witzigmann, Christopher,Arnold, Leggy A.,Chiou, Lih-Chu,Ernst, Margot,Mihovilovic, Marko D.,Savi?, Miroslav M.,Sieghart, Werner,Cook, James M.
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p. 2422 - 2446
(2018/03/26)
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- Determination of critical micellar concentration of homologous 2-alkoxyphenylcarbamoyloxyethyl-morpholinium chlorides
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The critical micellar concentrations of selected alkyloxy homologues of local anesthetic 4-(2-[(2-alkoxyphenyl)carbamoyl]oxy ethyl)morpholin-4-ium chloride with nc = 2, 4, 5, 6, 7, 8, and 9 carbons in alkyloxy tail were determined by absorption spectroscopy in the UV–vis spectral region with the use of a pyrene probe. Within the homologous series of the studied amphiphilic compounds, the ln(cmc) was observed to be dependent linearly on the number of carbon atoms nc in the hydrophobic tail: ln(cmc) = 0.705–0.966 nc. The Gibbs free energy, necessary for the transfer of the methylene group of the alkoxy chain from the water phase into the inner part of the micelle at the temperature of 25?C and pH ≈ 4.5–5.0, was found to be ?2.39 kJ/mol. The experimentally determined cmc values showed good correlations with the predicted values of the bulkiness of the alkoxy tail expressed as the molar volume of substituent R, as well as with the surface tension of the compounds.
- Stopková, Lenka,Inová, Jana Gali,Uchtová, Zuzana,Márik, Jozef ?i,Andriamainty, Fils
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- Chiral N,N Ligands Enabling Palladium-Catalyzed Enantioselective Intramolecular Heck–Matsuda Carbonylation Reactions by Sequential Migratory and CO Insertions
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Unprecedented enantioselective intramolecular Heck carbonylation reactions of arenediazonium salts were enabled by a chiral N,N ligand. This reaction constitutes the first enantioselective Heck carbonylation that proceeds through migratory insertion followed by CO insertion. The enantioenriched functionalized dihydrobenzofurans were obtained in good to high yields and enantiomeric ratios of up to 98:2 under mild and operationally simple reaction conditions.
- Carmona, Rafaela C.,K?ster, Otto D.,Correia, Carlos Roque Duarte
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supporting information
p. 12067 - 12070
(2018/09/11)
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- Dibasic derivatives of phenylcarbamic acid against mycobacterial strains: Old drugs and new tricks?
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In order to provide a more detailed view on the structure–antimycobacterial activity relationship (SAR) of phenylcarbamic acid derivatives containing two centers of protonation,1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium oxalates (1a–d)/dichlorides (1e–h) as wellas1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(di-propylammonio)propyl]azepanium oxalates (1i–l)/dichlorides (1m–p; alkoxy = butoxy to heptyloxy) were physicochemically characterized by estimation of their surface tension (γ; Traube’s stalagmometric method), electronic features (log ε; UV/Vis spectrophotometry) and lipophilic properties (log kw; isocratic RP-HPLC) as well. The experimental log kw dataset was studied together with computational logarithms of partition coefficients (log P) generated by various methods based mainly on atomic or combined atomic and fragmental principles. Similarities and differences between the experimental and in silico lipophilicity descriptors were analyzed by unscaled principal component analysis (PCA). The in vitro activity of compounds 1a–p was inspected against Mycobacterium tuberculosis CNCTC My 331/88 (identical with H37Rv and ATCC 2794, respectively), M. tuberculosis H37Ra ATCC 25177, M. kansasii CNCTC My 235/80 (identical with ATCC 12478), the M. kansasii 6509/96 clinical isolate, M. kansasii DSM 44162, M. avium CNCTC My 330/80 (identical with ATCC 25291), M. smegmatis ATCC 700084 and M. marinum CAMP 5644, respectively. In vitro susceptibility of the mycobacteria to reference drugs isoniazid, ethambutol, ofloxacin or ciprofloxacin was tested as well. A very unique aspect of the research was that many compounds from the set 1a–p were highly efficient almost against all tested mycobacteria. The most promising derivatives showed MIC values varied from 1.9 μM to 8 μM, which were lower compared to those of used standards, especially if concerning ability to fight M. tuberculosis H37Ra ATCC 25177, M. kansasii DSM 44162 or M. avium CNCTC My 330/80. Current in vitro biological assays and systematic SAR studies based on PCA approach as well as fitting procedures, which were supported by relevant statistical descriptors, proved that the compounds 1a–p represented a very promising molecular framework for development of ‘non-traditional’ but effective antimycobacterial agents.
- Malík, Ivan,Csollei, Jozef,Solovi?, Ivan,Pospísilová, Sárka,Michnová, Hana,Jampílek, Josef,?ízek, Alois,Kapustíková, Iva,?urillová, Jana,Pechá?ová, Mária,Stola?íková, Ji?ina,Pecher, Daniel,Oravec, Michal
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supporting information
(2018/10/05)
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- Ruthenium(II)-Catalyzed Regioselective C-8 Hydroxylation of 1,2,3,4-Tetrahydroquinolines
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Ru(II)-catalyzed chelation-assisted highly regioselective C8-hydroxylation of 1,2,3,4-tretrahydroquinolines has been developed. Various 1,2,3,4-tetrahydroquinolines underwent smooth C8-H hydroxylation with cheap and safe K2S2O8 as the oxidant and oxygen source to furnish the corresponding products in good to excellent yields with high tolerance of the functional groups. The choice of a readily installable and removable N-pyrimidyl directing group is the key to catalysis. Mechanistic studies suggest the involvement of a six-membered ruthenacycle intermediate in the catalytic cycle. The method can also be extended to the direct hydroxylation of other (hetero)arene C-H bonds.
- Chen, Changjun,Pan, Yixiao,Zhao, Haoqiang,Xu, Xin,Luo, Zhenli,Cao, Lei,Xi, Siqi,Li, Huanrong,Xu, Lijin
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supporting information
p. 6799 - 6803
(2018/11/21)
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- Eco-friendly, catalyst and solvent-free, synthesis of acetanilides and N-benzothiazole-2-yl-acetamides
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An expeditious and green synthesis of acetamides in a solvent-free simple way is described, without catalyst or additives, and in good yield by an instantaneous reaction of anilines or 2-aminothiazoles and acetic anhydride without external heating, and with simple purification. Sixteen substituted acetanilides and four N-benzothiazole-2-yl-acetamides were formed, but aliphatic amines of low molecular weight were not as effective as aromatic ones, and only cyclohexylamine and the enaminone ethyl 3-amino-2-butenoate afforded the corresponding acetamides in good yield.
- Cunha, Silvio,De Santana, Louren?o L. B.
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p. 1137 - 1144
(2017/05/01)
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- Method for preparing pranlukast key intermediate 3-amino-2-hydroxyacetophenone
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The invention provides a method for preparing a pranlukast key intermediate 3-amino-2-hydroxyacetophenone. The method takes 2-aminophenol as an initial raw material, 2-aminophenol and acetic anhydride are subjected to a synthesis reaction in water to obtain 2-acetaminophenol, then 2-acetamido-4-bromophenol is prepared by 2-ace-taminophenol and NBS under room temperature, 2-hydroxy-3-amino-5-bromoacetophenone is prepared by a Hoesch reaction, finally 2-hydroxy-3-amino-5-bromoacetophenone is dissolved in ethanol, and a Pd/C is added for catalytic hydrogenation and bromine removal to obtain the 3-amino-2-hydroxyacetophenone. The raw materials have the advantages of low cost, easy acquisition, diversified raw material selection, easy realization of production technology, and easy control, the purity of the final product is high, no dangerous process is generated, the equipment is simple, the synthesis route is novel, the synthesis route is short, the production power is increased, and production processing cost is reduced.
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Paragraph 0015
(2017/09/26)
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- Cp?Rh(III)/Bicyclic Olefin Cocatalyzed C-H Bond Amidation by Intramolecular Amide Transfer
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A bicyclic olefin was discovered as a cocatalyst in a Cp?Rh(III)-catalyzed C-H bond amidation proceeding by an intramolecular amide transfer in N-phenoxyacetamide derivatives. Combining experimental and theoretical studies, we propose that the olefin promotes a Rh(III) intermediate to undergo oxidative addition into the O-N bond to form a Rh(V) nitrenoid species and subsequently direct the nitrenoid to add to the ortho position. The amide directing group plays a dual role as a cleavable coordinating moiety as well as an essential coupling partner for the C-H amidation. This methodology was successfully applied to the late-stage diversification of natural products and a marketed drug under mild conditions.
- Wang, Xiaoming,Gensch, Tobias,Lerchen, Andreas,Daniliuc, Constantin G.,Glorius, Frank
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p. 6506 - 6512
(2017/05/17)
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- Chitosan supported Zn(II) mixed ligand complexes as heterogeneous catalysts for one-pot synthesis of amides from ketones via Beckmann rearrangement
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Chitosan supported Zn(II) mixed ligand complexes have been synthesized and characterized by FT-IR, UV–Vis, TGA, XRD, FESEM, EDX, AAS and Elemental Analysis. These complexes have been found to be efficient and recyclable heterogeneous catalysts for the one-pot synthesis of amides via Beckmann rearrangement. All three complexes can be easily filtered out from the reaction medium and reused up to five times without significant loss of catalytic activity. The reported protocol is economical and novel in the sense that amides can be easily synthesized in only one-step. All products were obtained as white to off-white crystalline solids and fully characterized by 1H NMR, FT-IR and Mass Spectra.
- Anuradha,Kumari, Shweta,Layek, Samaresh,Pathak, Devendra D.
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p. 368 - 373
(2016/11/03)
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- Radical Beckmann Rearrangement and Its Application in the Formal Total Synthesis of Antimalarial Natural Product Isocryptolepine via C-H Activation
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The Beckmann rearrangement of ketoximes, mediated by ammonium persulfate-dimethyl sulfoxide as a reagent, has been achieved under neutral conditions. Based on the radical trapping and 18O-labeling experiments, the transformation follows a mechanism involving a radical pathway. The scope and generality of the developed protocol has been demonstrated by 19 examples. The developed protocol and Pd-catalyzed intramolecular double C-H activation were used as key steps in the formal total synthesis of antimalarial natural product isocryptolepine.
- Mahajan, Pankaj S.,Humne, Vivek T.,Tanpure, Subhash D.,Mhaske, Santosh B.
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supporting information
p. 3450 - 3453
(2016/07/26)
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- Fragmentation of Protonated N-(3-Aminophenyl)Benzamide and Its Derivatives in Gas Phase
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An ion of m/z 110.06036 (ion formula [C6H8NO]+; error: 0.32 mDa) was observed in the collision induced dissociation tandem mass spectrometry experiments of protonated N-(3-aminophenyl)benzamide, which is a rearrangement product ion purportedly through nitrogen-oxygen (N–O) exchange. The N–O exchange rearrangement was confirmed by the MS/MS spectrum of protonated N-(3-aminophenyl)-O18-benzamide, where the rearranged ion, [C6H8NO18]+ of m/z 112 was available because of the presence of O18. Theoretical calculations using Density Functional Theory (DFT) at B3LYP/6-31?g(d) level suggest that an ion-neutral complex containing a water molecule and a nitrilium ion was formed via a transition state (TS-1), followed by the water molecule migrating to the anilide ring, eventually leading to the formation of the rearranged ion of m/z 110. The rearrangement can be generalized to other protonated amide compounds with electron-donating groups at the meta position, such as, –OH, –CH3, –OCH3, –NH(CH3)2, –NH-Ph, and –NHCOCH3, all of which show the corresponding rearranged ions in MS/MS spectra. However, the protonated amide compounds containing electron-withdrawing groups, including –Cl, –Br, –CN, –NO2, and –CF3, at the meta position did not display this type of rearrangement during dissociation. Additionally, effects of various acyl groups on the rearrangement were investigated. It was found that the rearrangement can be enhanced by substitution on the ring of the benzoyl with electron-withdrawing groups. [Figure not available: see fulltext.]
- Zu, Chengli,Mukhopadhyay, Sukrit,Hanley, Patrick S.,Xia, Shijing,Bell, Bruce M.,Grigg, David,Gilbert, Jeffrey R.,O’Brien, John P.
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p. 917 - 926
(2016/05/02)
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- LIGANDS SELECTIVE TO ALPHA 6 SUBUNIT-CONTAINING GABAA RECEPTORS ANS THEIR METHODS OF USE
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Provided herein are novel pyrazoloquinolinone compounds and method of using such compounds to treat disorders such as neuropsychiatric disorders with sensorimotor gating deficits, such as schizophrenia, tic disorders, attention deficit hyperactivity disorder, obsessive compulsive disorder, panic disorder, Huntington's disease and nocturnal enuresis;depression; temporomandibular myofascial pain; disorders of trigeminal nerve, such as trigeminal neuralgia and trigeminal neuropathy; migraine; and tinnitus.
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Paragraph 00135
(2016/12/22)
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- Synthesis method of 2-hydroxyl-4-bromobenzoic acid
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The present invention discloses a synthesis method of 2-hydroxyl-4-bromobenzoic acid, and belongs to the technical field of organic synthesis. According to the synthesis method disclosed by the present invention, the synthesis method comprises the following steps: using phenol as a raw martial; firstly adding nitric acid and sulfuric acid to generate 2-nitrophenol; then adding HCl and zinc powder to synthesize 2-amino phenol; heating in a water bath and adding CH3COCH to further generate 2-acetamidophenol; next, adding FeBr3 and Br2, and adding CaO2 and triiron tetroxide after the reaction is cooled; and thus generating the 2-hydroxyl-4-bromobenzoic acid disclosed by the present invention after the 2-acetamidophenol is changed into the 2-hydroxyl-4-bromobenzoic acid. The embodiment demonstrates that the synthesis method disclosed by the present invention is not only simple in operation and mild in reaction but also free of pollution, so that the product yield is higher than 89%, and the purity reaches more than 92%.
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- N-Acyl-N-(4-chlorophenyl)-4-nitrobenzenesulfonamides: Highly selective and efficient reagents for acylation of amines in water
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A variety of N-acyl-N-(4-chlorophenyl)-4-nitrobenzenesulfonamides (1a-e) were synthesized in one pot from 4-chloroaniline under solvent-free conditions and have been developed as chemoselective N-acylation reagents. Selective protection of primary amines in the presence of secondary amines, acylation of aliphatic amines in the presence of aryl amines, and monofunctionalization of primary-secondary diamines as well as selective N-acylation of amino alcohols using these reagents are described. All of the acylation reactions were carried out in water as a green solvent. High stability and easy preparation of these acylating reagents are other advantages of this method.
- Ebrahimi, Sara,Saiadi, Safoura,Dakhilpour, Simin,Mirsattari, Seyed Nezamoddin,Massah, Ahmad Reza
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- Beckmann rearrangement of oximes using doped silica gel complex
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A new complex of perchloric acid absorbed on silica gel (doped silica gel) and dichloromethane was found to be very effective for converting ketoximes into their corresponding amides or lactams with excellent conversion via the Beckmann rearrangement. This method offers significant advantages such as efficiency and mild reaction conditions with shorter reaction time.
- Umanadh,Reddy, N. Srinivasa,Mukkanti, Khagga,Omprakash
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p. 1209 - 1211
(2015/02/19)
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- Copper-promoted sandmeyer difluoromethylthiolation of aryl and heteroaryl diazonium salts
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An efficient copper-promoted difluoromethylthiolation of aryl and heteroaryl diazonium salts is described. The reaction is conducted under mild reaction conditions and various functional groups were compatible. In addition, reactions of heteroaryl diazonium salts such as pyridyl, quinolinyl, benzothiazolyl, thiophenyl, carbazolyl, and pyrazolyl diazonium salts occurred smoothly to afford the medicinally important difluoromethylthiolated heteroarenes. Furthermore, a more practical one-pot direct diazotization and difluoromethylthiolation protocol was developed, and it converts the aniline derivatives into difluoromethylthiolated arenes. The utility of the method is demonstrated by difluoromethylthiolation of a number of natural products and drug molecules. A dose of salt: The title reaction is conducted under mild reaction conditions and various functional groups are compatible. (Hetero)aryl diazonium salts reacted smoothly to afford the medicinally important difluoromethylthiolated (hetero)arenes. A practical one-pot direct diazotization and difluoromethylthiolation protocol was developed for aniline derivatives to generate difluoromethylthiolated arenes.
- Wu, Jiang,Gu, Yang,Leng, Xuebing,Shen, Qilong
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supporting information
p. 7648 - 7652
(2015/06/25)
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- Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
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2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
- Rajan
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p. 287 - 291
(2015/01/30)
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- Palladium catalyzed Csp2-H activation for direct aryl hydroxylation: The unprecedented role of 1,4-dioxane as a source of hydroxyl radicals
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A novel strategy for direct aryl hydroxylation via Pd-catalysed Csp2-H activation through an unprecedented hydroxyl radical transfer from 1,4-dioxane, used as a solvent, is reported with bio relevant and sterically hindered heterocycles and various acyclic functionalities as versatile directing groups.
- Seth, Kapileswar,Nautiyal, Manesh,Purohit, Priyank,Parikh, Naisargee,Chakraborti, Asit K.
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supporting information
p. 191 - 194
(2015/01/09)
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- Keggin-type Bronsted dodecatungstophosphoric acid: A quasi homogenous and reusable catalyst system for liquid phase Beckmann rearrangement
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A variety of ketoximes, prepared from corresponding ketones, undergo Beckmann rearrangement using H3PW12O40 (DTPA) in acetonitrile under reflux to yield N-substituted amides and lactams in good to excellent yields (72-96%). The present method provides an efficient, clean, eco-friendly, and simple synthesis. The catalyst is cheap, moisture tolerant, recoverable, and reusable without much loss of its activity.
- Kaur, Gagandeep,Rajput, Jaspreet Kaur,Arora, Priya,Devi, Nisha
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p. 1136 - 1140
(2014/02/14)
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- Self-catalyzed direct amidation of ketones: A sustainable procedure for acetaminophen synthesis
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High yielding amination of ketones and benzaldehyde in acid-less conditions has been conducted on several ketones to achieve amides and nitriles. The reactivity of the selected substrates showed to depend on both oximation and Beckmann rearrangement reaction rates. Oximation allows the in-situ production of hydrochloric acid that enables Beckmann rearrangement of the oxime to form the corresponding amide or nitrile. It is noteworthy that, using this one-pot synthetic approach, N-acetyl-4-aminophenol (acetaminophen drug), can be easily synthesized starting from 4-hydroxy-acetophenone in high yield. Acetanilide and ε-caprolactam can be also efficiently synthesized employing this synthetic procedure.
- Rancan, Elia,Aricò, Fabio,Quartarone, Giuseppe,Ronchin, Lucio,Tundo, Pietro,Vavasori, Andrea
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- One-pot oximation-Beckmann rearrangement of ketones and aldehydes to amides of industrial interest: Acetanilide, caprolactam and acetaminophen
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High yielding one-pot oximation-Beckmann rearrangement of ketones to amides in ktrifluoroacetic acid has been conducted on several ketones and aldehydes. The substrate reactivity showed to depend on both oximation and Beckmann rearrangement reaction rate. In this synthetic procedure, trifluoroacetic acid acts as solvent, acid catalyst and organocatalyst and can be easily recycled.
- Aricò, Fabio,Quartarone, Giuseppe,Rancan, Elia,Ronchin, Lucio,Tundo, Pietro,Vavasori, Andrea
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- Self-catalyzed direct amidation of ketones: A sustainable procedure for acetaminophen synthesis
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High yielding amination of ketones and benzaldehyde in acid-less conditions has been conducted on several ketones to achieve amides and nitriles. The reactivity of the selected substrates showed to depend on both oximation and Beckmann rearrangement reaction rates. Oximation allows the in-situ production of hydrochloric acid that enables Beckmann rearrangement of the oxime to form the corresponding amide or nitrile. It is noteworthy that, using this one-pot synthetic approach, N-acetyl-4-aminophenol (acetaminophen drug), can be easily synthesized starting from 4-hydroxy-acetophenone in high yield. Acetanilide and ε-caprolactam can be also efficiently synthesized employing this synthetic procedure.
- Rancan, Elia,Aricò, Fabio,Quartarone, Giuseppe,Ronchin, Lucio,Tundo, Pietro,Vavasori, Andrea
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- Tailoring atropisomeric maleimides for stereospecific [2 + 2] photocycloaddition-photochemical and photophysical investigations leading to visible-light photocatalysis
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Atropisomeric maleimides were synthesized and employed for stereospecific [2 + 2] photocycloaddition. Efficient reaction was observed under direct irradiation, triplet-sensitized UV irradiation, and non-metal catalyzed visible-light irradiation, leading to two regioisomeric (exo/endo) photoproducts with complete chemoselectivity (exclusive [2 + 2] photoproduct). High enantioselectivity (ee > 98%) and diastereoselectivity (dr > 99:1%) were observed under the employed reaction conditions and were largely dependent on the substituent on the maleimide double bond but minimally affected by the substituents on the alkenyl tether. On the basis of detailed photophysical studies, the triplet energies of the maleimides were estimated. The triplet lifetimes appeared to be relatively short at room temperature as a result of fast [2 + 2] photocycloaddition. For the visible-light mediated reaction, triplet energy transfer occurred with a rate constant close to the diffusion-limited value. The mechanism was established by generation of singlet oxygen from the excited maleimides. The high selectivity in the photoproduct upon reaction from the triplet excited state was rationalized on the basis of conformational factors as well as the type of diradical intermediate that was preferred during the photoreaction.
- Kumarasamy, Elango,Raghunathan, Ramya,Jockusch, Steffen,Ugrinov, Angel,Sivaguru
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supporting information
p. 8729 - 8737
(2014/07/07)
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- DIHYDRO 1,4-BENZOXAZINES AND METHOD OF SYNTHESIZING THE SAME USING SULFONIUM SALTS
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Exemplary embodiments of the present invention relate to benzoxazines having various N-protecting groups. An R1 functional group is at least one selected from the group consisting of H and a halogen, an R2 functional group is at least one selected from the group consisting of H, an amide, or a carbamate, and a Z functional group is at least one selected from the group consisting of a phenyl, substituted phenyl group, methyl, and t-butyl group. The exemplary embodiments provide compounds with benzoxazines having various cleavable protecting groups such as amides and carbamates.
- -
-
Paragraph 0058-0060
(2014/11/11)
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- Trifluoromethylation of arenediazonium salts with fluoroform-derived CuCF3 in aqueous media
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A new protocol has been developed for trifluoromethylation of arenediazonium salts with moisture-sensitive CuCF3 (from fluoroform) in aqueous media. The reaction is governed by a radical mechanism, tolerates a broad variety of functional groups, and is applicable to the synthesis of complex, polyfunctionalized molecules. This journal is the Partner Organisations 2014.
- Lishchynskyi, Anton,Berthon, Guillaume,Grushin, Vladimir V.
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supporting information
p. 10237 - 10240
(2014/08/18)
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- Arylative cyclization of 2-isocyanobiphenyls with anilines: One-pot synthesis of 6-arylphenanthridines via competitive reaction pathways
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A transition-metal-free method for the synthesis of C6 phenanthridine derivatives by arylative cyclization of 2-isocyanobiphenyls with arylamines in one pot was developed. Mechanistic studies suggest that electrophilic aromatic substitution (SEAr) of a nitrilium intermediate and homolytic aromatic substitution (HAS) of an imidoyl radical intermediate are two competitive reaction pathways involved in the annulation step.
- Xia, Zhonghua,Huang, Jinbo,He, Yimiao,Zhao, Jiaji,Lei, Jian,Zhu, Qiang
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supporting information
p. 2546 - 2549
(2014/05/20)
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- Cyclizing radical carboiodination, carbotelluration, and carboaminoxylation of aryl amines
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Radical carboiodination of various aryl amines is reported. Aryl diazonium salts, generated in situ from the corresponding aryl amines, are reacted with Bu4NI to provide the corresponding aryl radicals which undergo 5-exo or 6-exo cyclization. Iodine abstraction eventually affords the carboiodinated products in good to excellent yields. If TEMPO is added, the cascade provides the cyclized carboaminoxylation products. Running the reaction in the presence of PhTeTePh affords the phenyltellurated cyclized products.
- Hartmann, Marcel,Studer, Armido
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supporting information
p. 8180 - 8183
(2014/08/18)
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- Synthesis of benzoxazoles from 2-aminophenols and β-diketones using a combined catalyst of br?nsted acid and copper iodide
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Cyclization reactions of 2-aminophenols with β-diketones catalyzed by a combination of Br?nsted acid and CuI are presented. Various 2-substituted benzoxazoles were obtained through these reactions. Different substituents such as methyl, chloro, bromo, nitro, and methoxy on 2-aminophenol are tolerated under the optimized reaction conditions.
- Mayo, Muhammad Shareef,Yu, Xiaoqiang,Zhou, Xiaoyu,Feng, Xiujuan,Yamamoto, Yoshinori,Bao, Ming
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p. 6310 - 6314
(2014/07/21)
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- Amidation of phenol derivatives: A direct synthesis of paracetamol (acetaminophen) from hydroquinone
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A direct synthesis of paracetamol (acetaminophen) from hydroquinone has been developed using ammonium acetate as an amidating agent. The reaction proceeds in acetic acid at elevated temperatures without any metallic catalyst. Under these conditions, paracetamol was obtained with high yield and selectivity (>95%). The reaction has also been carried out on the multi-gram scale (44 g of hydroquinone) and a potential process has been proposed based on the recycling of the solvent and by-products. This amidation protocol has also been extended to other phenol derivatives. This journal is the Partner Organisations 2014.
- Joncour, Roxan,Duguet, Nicolas,Metay, Estelle,Ferreira, Amadeo,Lemaire, Marc
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supporting information
p. 2997 - 3002
(2014/06/10)
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- Divergent reactivities of o-haloanilides with CuO nanoparticles in water: A green synthesis of benzoxazoles and o-hydroxyanilides
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In the present study, three divergent reaction paths emerged when o-haloanilides were subjected to CuO nanoparticles in water. o-Halo (I, Br) phenylbenzamides in the presence of CuO nanoparticles and Cs2CO 3 in water at 100 °C provided o-hydroxyphenyl benzamides as the major product. However, a complete change in selectivity was observed in the presence of an organic base/ligand (TMEDA), giving 2-arylbenzoxazole as the exclusive product. The above selectivities were not clearly distinct when the corresponding alkylamides were treated either in the presence or absence of the ligand. A number of o-halophenyl alkylamides provided either exclusively o-dehalogenated products or a mixture of o-dehalogenated and o-hydroxylated products, but none gave 2-alkylbenzoxazoles. In addition to the above selectivities, the use of an environmentally friendly solvent (water) and base, and the recyclability of the catalyst make this procedure a benign alternative to the existing methods for the synthesis of these molecules, viz. o-hydroxybenzamides and o-arylbenzoxazoles.
- Khatun, Nilufa,Guin, Srimanta,Rout, Saroj Kumar,Patel, Bhisma K.
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p. 10770 - 10778
(2014/03/21)
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- A novel silver nanoparticle embedded mesoporous polyaniline (mPANI/Ag) nanocomposite as a recyclable catalyst in the acylation of amines and alcohols under solvent free conditions
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A mesoporous polyaniline/silver (mPANI/Ag) nanocomposite has been prepared using mesoporous organic polymer polyaniline with silver nitrate via radical polymerization of aniline monomer in the presence of hydrochloric acid. The mPANI/Ag nanocomposite has been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectra (EDX), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible absorption spectra (UV-vis). The XRD patterns indicated that the crystalline phase of Ag is cubic. TEM images show that the Ag nanoparticles are well dispersed in the mesoporous polyaniline matrix. The mPANI/Ag acts as an efficient heterogeneous nanocatalyst in the acylation of substituted amines and alcohols using acetic acid. The catalyst is air-stable, inexpensive, easy to prepare and can be reused several times without a significant decrease in activity and selectivity. This journal is
- Mandi, Usha,Roy, Anupam Singha,Banerjee, Biplab,Islam, Sk. Manirul
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p. 42670 - 42681
(2015/02/19)
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- Stannous chloride dihydrate-mediated efficient access to secondary and primary amides from oximes
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Highly selective, efficient and expeditious Beckmann rearrangement of a wide range of ketoximes to secondary amides (20 examples) has been accomplished using stoichiometric amount of stannous chloride dihydrate in the presence of nucleophilic additive, tetra-n-butylammonium iodide (TBAI) (10 moI%) and 4 ? MS in dry acetonitrile at reflux temperature. Aldoximes delivered primary amides through intermediacy of nitriles upon heating with an equimolar amount of SnCl2·2H2O and DBU in dry toluene at reflux in good to acceptable yields (12 examples). Utilization of mild Lewis acid, inexpensive rack reagents and procedural simplicity including easy isolation of products are key advantageous features of the protocol.
- Ganguly, Nemai C.,Nayek, Subhasis,Chandra, Sumanta
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p. 1695 - 1702
(2014/01/17)
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- Copper-promoted sandmeyer trifluoromethylation reaction
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A copper-promoted trifluoromethylation reaction of aromatic amines is described. This transformation proceeds smoothly under mild conditions and exhibits good tolerance of many synthetically relevant functional groups. It provides an alternative approach for the synthesis of trifluoromethylated arenes and heteroarenes. It also constitutes a new example of the Sandmeyer reaction.
- Dai, Jian-Jun,Fang, Chi,Xiao, Bin,Yi, Jun,Xu, Jun,Liu, Zhao-Jing,Lu, Xi,Liu, Lei,Fu, Yao
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supporting information
p. 8436 - 8439
(2013/07/19)
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- Cesium carbonate mediated aryl triflate esters' deprotection
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A variety of diversely substituted aryl triflate esters were efficiently deprotected to the parent phenols by exposure to cesium carbonate in toluene. This procedure proved highly compatible with existing functional groups.
- Green, Alice E.,Agouridas, Vangelis,Deniau, Eric
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supporting information
p. 7078 - 7079
(2013/12/04)
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- H2O2-mediated oxidative formation of amides from aromatic amines and 1,3-diketones as acylation agents via C-C bond cleavage at room temperature in water under metal-free conditions
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1,3-Diketones, as novel acylation agents, reacted with aromatic amines promoted by commercially available H2O2 (30% aq.) as the sole oxidant at room temperature under metal-free conditions in water, leading to a novel and rapid amide bond formation strategy. The reported method is high-yielding, simple and mild, and is the first example of the use of 1,3-diketones as acylation agents via C-C bond cleavage.
- Sun, Xi,Wang, Min,Li, Pinhua,Zhang, Xiuli,Wang, Lei
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supporting information
p. 3289 - 3294
(2013/12/04)
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- HF-Pyridine: A versatile promoter for monoacylation/sulfonylation of phenolic diols and for direct conversion of t-butyldimethylsilyl ethers to the corresponding acetates
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Monoacylation and trifluoromethanesulfonylation of phenolic diols were achieved by the aid of HF-pyridine, whereas diacylation occurred with pyridine alone. Furthermore, HF-pyridine was found to promote the direct conversion of t-butyldimethylsilyl ethers to the corresponding acetates.
- Michigami, Kyosuke,Yoshimoto, Kazuya,Hayashi, Masahiko
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scheme or table
p. 138 - 139
(2012/03/09)
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