- Using hydrogen bonding to control carbamate C-N rotamer equilibria
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In chloroform solution, the syn/anti rotamer ratios for AT-(2-pyridyl)carbamates, 3, and JV-phenylcarbamates, 4, are close to 0.05. Addition of the double hydrogen bonding acetic acid moderately stabilizes the syn rotamer of 4, but has no measurable effec
- Moraczewski, Alexei L.,Banaszynski, Laura A.,From, Aaron M.,White, Courtney E.,Smith, Bradley D.
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- Radical Hydrodehalogenation of Aryl Halides with H2 Catalyzed by a Phenanthroline-Based PNNP Cobalt(I) Complex
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Radical hydrodehalogenation of aryl halides (Ar-X; X = Cl, Br, I) is achieved in the presence of atmospheric pressure H2 as a H-atom donor using a Co(I) catalyst bearing a phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline). The reaction proceeds under mild conditions (1 atm H2) and is applicable to aryl bromides and aryl chlorides with various functional groups. A mechanistic study revealed that the PNNP-Co complex underwent facile H-H cleavage and facilitated a H-atom transfer. This process is mediated by a long-range metal-ligand cooperation of the PNNP-Co system, which includes the dearomatization/aromatization sequence of the phenanthroline ligand backbone. A radical clock experiment demonstrated the Ar-X bond cleavage via a radical mechanism. Further kinetic study supported that the rate-determining step includes electron transfer from the Co center to the substrate, affording a radical pair ArX?- and an odd-electron metal-halide complex [Co(II) + ArX?-]? as a transition state.
- Iizuka, Kosuke,Ishizaka, Yusuke,Jheng, Nai-Yuan,Minami, Yasunori,Naganawa, Yuki,Nakajima, Yumiko,Sekiguchi, Akira
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p. 2320 - 2329
(2022/02/16)
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- Thiamine hydrochloride as a recyclable organocatalyst for the efficient and chemoselective N-tert-butyloxycarbonylation of amines
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Thiamin hydrochloride promoted highly efficient and ecofriendly approach has been described for the chemoselective N-tert-butyloxycarbonylation of amines under solvent-free conditions at ambient temperature. The demonstrated approach has been applicable for the N-Boc protection of variety of aliphatic, aryl, heteroaryl amines. The chemoselective protection of amino group occurs in chiral amines and amino alcohol without racemization in high yield. Thiamin hydrochloride is stable, economical, easy to handle and environmentally friendly.
- Ingale, Ajit P.,Garad, Dnyaneshwar N.,Ukale, Dattatraya,Thorat, Nitin M.,Shinde, Sandeep V.
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supporting information
p. 3791 - 3804
(2021/11/04)
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- Ultrasound promoted environmentally benign, highly efficient, and chemoselective N-tert-butyloxycarbonylation of amines by reusable sulfated polyborate
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The sulfated polyborate catalyzed an efficient and chemoselective N-tert-butyloxycarbonylation of amines under ultrasonic irradiation is developed. A broad substrate scope has been demonstrated for N-Boc protection of various primary/secondary amines. It allows converting several aliphatic/aryl/heteroaryl amines, amino alcohol, aminoester, and chiral amines to their N-Boc-protected derivatives under solvent-free conditions with excellent yields. The protocol has several advantages such as easy catalyst, and product isolation, short reaction time, excellent yields, outstanding chemoselectivity, and catalyst recyclability, among others. This makes the process practicable, economical, and environmentally benign.
- Pise, Ashok S.,Ingale, Ajit P.,Dalvi, Navnath R.
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supporting information
p. 3768 - 3780
(2021/10/26)
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- Sulfated tungstate: A highly efficient, recyclable and ecofriendly catalyst for chemoselective N-tert butyloxycarbonylation of amines under the solvent-free conditions
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Sulfated tungstate catalyzed an efficient and ecofriendly protocol has been described for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions at room temperature. The variety of functionalized aliphatic, aromatic and heteroaromatic amines efficiently undergoes the N-tert-butyloxycarbonylation under the developed protocol. The aminoalcohol, aminophenol, aminoester as well as various chiral amines underwent the chemoselective N-Boc protection under the optimized reaction condition. The rapid reaction rate, mild conditions, very good functional group tolerance, excellent yield, solvent-free, easy recovery products and excellent catalyst recyclability are the advantages of this protocol. This makes the protocol feasible, economical and environmentally benign.
- Ingale, Ajit P.,Shinde, Sandeep V.,Thorat, Nitin M.
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supporting information
p. 2528 - 2543
(2021/07/02)
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- Nanoceria as an efficient and green catalyst for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions
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Nanocerium oxide mediated an efficient and green protocol has been described for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions at ambient temperature. Various aliphatic, aromatic and heteroaromatic amines were protected using developed protocol and several functional groups such as alcohol, phenol and ester were well tolerated under these conditions. The rapid reaction rate, mild conditions, very good functional group tolerance, excellent yield, solvent-free, easy recovery products and excellent catalyst recyclability are the advantages of this protocol. This makes the protocol feasible, economical and environmentally benign.
- Garad, Dnyaneshwar N.,Ingale, Ajit P.,Shinde, Sandeep V.,Ukale, Dattatraya
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supporting information
p. 1656 - 1668
(2021/04/05)
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- Solvent-freeN-Boc deprotection byex situgeneration of hydrogen chloride gas
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An efficient, scalable and sustainable method for the quantitative deprotection of thetert-butyl carbamate (N-Boc) protecting group is described, using down to near-stoichiometric amounts of hydrogen chloride gas in solvent-free conditions. We demonstrate theex situgeneration of hydrogen chloride gas from sodium chloride and sulfuric acid in a two-chamber reactor, introducing a straightforward method for controlled and stoichiometric release of HCl gas. The solvent-free conditions allow deprotection of a wide variety ofN-Boc derivatives to obtain the hydrochloride salts in quantitative yields. The procedure obviates the need for any work-up or purification steps providing an uncomplicated green alternative to standard methods. Due to the solvent-free, anhydrous conditions, this method shows high tolerance towards acid sensitive functional groups and furnishes expanded functional group orthogonality.
- De Borggraeve, Wim M.,Gilles, Philippe,Van Mileghem, Seger,Verschueren, Rik H.
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supporting information
p. 5782 - 5787
(2021/07/12)
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- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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supporting information
p. 5022 - 5037
(2021/05/04)
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- In-Cell Generation of Anticancer Phenanthridine Through Bioorthogonal Cyclization in Antitumor Prodrug Development
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Pharmacological inactivation of antitumor drugs toward healthy cells is a critical factor in prodrug development. Typically, pharmaceutical chemists graft temporary moieties to existing antitumor drugs to reduce their pharmacological activity. Here, we re
- Maslah, Hichem,Skarbek, Charles,Gourson, Catherine,Plamont, Marie-Aude,Pethe, Stéphanie,Jullien, Ludovic,Le Saux, Thomas,Labruère, Rapha?l
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supporting information
p. 24043 - 24047
(2021/10/07)
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- Identification and Profiling of a Novel Diazaspiro[3.4]octane Chemical Series Active against Multiple Stages of the Human Malaria Parasite Plasmodium falciparum and Optimization Efforts
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A novel diazaspiro[3.4]octane series was identified from a Plasmodium falciparum whole-cell high-throughput screening campaign. Hits displayed activity against multiple stages of the parasite lifecycle, which together with a novel sp3-rich scaffold provided an attractive starting point for a hit-to-lead medicinal chemistry optimization and biological profiling program. Structure-activity-relationship studies led to the identification of compounds that showed low nanomolar asexual blood-stage activity (50 nM) together with strong gametocyte sterilizing properties that translated to transmission-blocking activity in the standard membrane feeding assay. Mechanistic studies through resistance selection with one of the analogues followed by whole-genome sequencing implicated the P. falciparum cyclic amine resistance locus in the mode of resistance.
- Le Manach, Claire,Dam, Jean,Woodland, John G.,Kaur, Gurminder,Khonde, Lutete P.,Brunschwig, Christel,Njoroge, Mathew,Wicht, Kathryn J.,Horatscheck, André,Paquet, Tanya,Boyle, Grant A.,Gibhard, Liezl,Taylor, Dale,Lawrence, Nina,Yeo, Tomas,Mok, Sachel,Eastman, Richard T.,Dorjsuren, Dorjbal,Talley, Daniel C.,Guo, Hui,Simeonov, Anton,Reader, Janette,Van Der Watt, Mari?tte,Erlank, Erica,Venter, Nelius,Zawada, Jacek W.,Aswat, Ayesha,Nardini, Luisa,Coetzer, Theresa L.,Lauterbach, Sonja B.,Bezuidenhout, Belinda C.,Theron, Anjo,Mancama, Dalu,Koekemoer, Lizette L.,Birkholtz, Lyn-Marie,Wittlin, Sergio,Delves, Michael,Ottilie, Sabine,Winzeler, Elizabeth A.,Smith, Dennis,Fidock, David A.,Street, Leslie J.,Basarab, Gregory S.,Duffy, James,Chibale, Kelly
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supporting information
p. 2291 - 2309
(2021/03/01)
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- Integrating Hydrogen Production and Transfer Hydrogenation with Selenite Promoted Electrooxidation of α-Nitrotoluenes to E-Nitroethenes
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Developing an electrochemical carbon-added reaction with accelerated kinetics to replace the low-value and sluggish oxygen evolution reaction (OER) is markedly significant to pure hydrogen production. Regulating the critical steps to precisely design electrode materials to selectively synthesize targeted compounds is highly desirable. Here, inspired by the surfaced adsorbed SeOx2? promoting OER, NiSe is demonstrated to be an efficient anode enabling α-nitrotoluene electrooxidation to E-nitroethene with up to 99 % E selectivity, 89 % Faradaic efficiency, and the reaction rate of 0.25 mmol cm?2 h?1 via inhibiting side reactions for energy-saving hydrogen generation. The high performance can be associated with its in situ formed NiOOH surface layer and absorbed SeOx2? via Se leaching-oxidation during electrooxidation, and the preferential adsorption of two -NO2 groups of intermediate on NiOOH. A self-coupling of α-carbon radicals and subsequent elimination of a nitrite molecule pathway is proposed. Wide substrate scope, scale-up synthesis of E-nitroethene, and paired productions of E-nitroethene and hydrogen or N-protected aminoarenes over a bifunctional NiSe electrode highlight the promising potential. Gold also displays a similar promoting effect for α-nitrotoluene transformation like SeOx2?, rationalizing the strategy of designing materials to suppress side reactions.
- Chong, Xiaodan,Liu, Cuibo,Wang, Changhong,Yang, Rong,Zhang, Bin
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supporting information
p. 22010 - 22016
(2021/09/02)
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- Copper-Catalyzed Coupling of Amines with Carbazates: An Approach to Carbamates
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A new approach for the preparation of carbamatesviathe copper-catalyzed cross-coupling reaction of amines with alkoxycarbonyl radicals generated from carbazates is described. This environmentally friendly protocol takes place under mild conditions and is compatible with a wide range of amines, including aromatic/aliphatic and primary/secondary substrates.
- Wang, Song-Ning,Zhang, Guo-Yu,Shoberu, Adedamola,Zou, Jian-Ping
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p. 9067 - 9075
(2021/07/19)
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- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
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Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
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p. 1653 - 1665
(2021/06/17)
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- Interrupted aza-Wittig reactions using iminophosphoranes to synthesize 11C-carbonyls
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A direct CO2-fixation methodology couples structurally diverse iminophosphoranes with various nucleophiles to synthesize ureas, carbamates, thiocarbamates, and amides, and is amenable for 11C radiolabeling. This methodology is practical, as demonstrated by the synthesis of >35 products and isolation of the molecular imaging radiopharmaceuticals [11C]URB694 and [11C]glibenclamide. This journal is
- Ismailani, Uzair S.,Munch, Maxime,Mair, Braeden A.,Rotstein, Benjamin H.
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supporting information
p. 5266 - 5269
(2021/06/06)
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- Base-Mediated Generation of Ketenimines from Ynamides: [3+2] Annulation with Azaallyl Anions
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Under basic conditions and heat, ynamides can serve as precursors to ketenimines, whose synthetic potential is often hampered by their difficulty of access. Herein, we report that they can undergo a [3+2] cycloaddition with 2-azaallyl anions, obtained from benzylimines under the same reaction conditions. This reaction between two highly reactive intermediates, both generated in situ from bench stable starting materials, gives access to various nitrogen-rich heterocycles. The reaction usually proceeds with excellent diastereoselectivity, in favor of the cis adduct. Deuteration experiments and DFT calculations helped rationalize the regio- and stereoselectivity of the process as well as the formation of side products. (Figure presented.).
- D'Hollander, Agathe C. A.,Romero, Eugénie,Vijayakumar, Kamsana,Le Houérou, Camille,Retailleau, Pascal,Dodd, Robert H.,Iorga, Bogdan I.,Cariou, Kevin
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supporting information
p. 2903 - 2908
(2021/04/21)
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- Linear Hydroaminoalkylation Products from Alkyl-Substituted Alkenes
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The regioselective conversion of alkyl-substituted alkenes into linear hydroaminoalkylation products represents a strongly desirable synthetic transformation. In particular, such conversions of N-methylamine derivatives are of great scientific interest, because they would give direct access to important amines with unbranched alkyl chains. Herein, we present a new one-pot procedure that includes an initial alkene hydroaminoalkylation with an α-silylated amine substrate and a subsequent protodesilylation reaction that delivers linear hydroaminoalkylation products with high selectivity from simple alkyl-substituted alkenes. For that purpose, new titanium catalysts have been developed, which are able to activate the α-C?H bond of more challenging α-silylated amine substrates. In addition, a direct relationship between the ligand structure of the new catalysts and the obtained regioselectivity is described.
- Warsitz, Michael,Doye, Sven
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supporting information
p. 15121 - 15125
(2020/10/23)
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- Highly efficient chemoselective N-tert butoxycarbonylation of aliphatic/aromatic/heterocyclic amines using diphenylglycoluril as organocatalyst
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An efficient approach for the Chemoselective N-tert-butoxycarbonylation of a variety of amines using diphenylglycoluril as organocatalyst has been described. For the first time, a plausible mechanism for the N-tert-butoxycarbonylation has been proposed using density functional theory (DFT) calculations supported by NMR studies. The reusability of the organocatalyst and observation of the desired N-Boc protected amines being formed without the formation of side products like urea, oxazolidinone, isocyanate, and N, N-di-Boc derivatives makes the present protocol desirable.
- Awasthi, Amardeep,Mukherjee, Anagh,Singh, Mandeep,Rathee, Garima,Vanka, Kumar,Chandra, Ramesh
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- Method for preparing amine compound by alkali-catalyzed decarboxylation (by machine translation)
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The method is simple and convenient (reaction conditions ;), more stable,atom utilization rate, by-products are only carbon dioxide pollution, and the yield can reach. suitable for industrial production Curtis; and the method, Lossen is suitable for industrial production . The method disclosed by the invention is simple and convenient to operate under the action of a base as, rearrangement, rearrangement reaction of an alkyl, aryl or heterocyclic aromatic carboxylic acid or an ester and hydroxylamine compound, 90%. (by machine translation)
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- Nickel-Catalyzed Synthesis of N-(Hetero)aryl Carbamates from Cyanate Salts and Phenols Activated with Cyanuric Chloride
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A simple and efficient domino reaction has been designed and employed for the one-pot synthesis of N-(hetero)aryl carbamates through the reaction between alcohols and in-situ produced (hetero)aryl isocyanates in the presence of a nickel catalyst. The phenolic C?O bond was activated via the reaction of phenol with cyanuric chloride (2,4,6-trichloro-1,3,5-triazine (TCT)) as an inexpensive and readily available reagent. This strategy provides practical access to N-(hetero)aryl carbamates in good yields with high functional groups compatibility.
- Dindarloo Inaloo, Iman,Esmaeilpour, Mohsen,Majnooni, Sahar,Reza Oveisi, Ali
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p. 5486 - 5491
(2020/09/04)
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- ERBB/BTK INHIBITORS
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Disclosed are compounds inhibiting ErbBs (e. g., EGFR or Her 2), especially mutant forms of ErbBs, and BTK, pharmaceutically acceptable salts, hydrates, solvates or stereoisomers thereof and pharmaceutical compositions comprising the compounds. The compou
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Page/Page column 86; 60
(2019/08/26)
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- Identification of 5-Substituted 2-Acylaminothiazoles That Activate Tat-Mediated Transcription in HIV-1 Latency Models
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The persistent reservoir of cells latently infected with human immunodeficiency virus (HIV)-integrated proviral DNA necessitates lifelong suppressive antiretroviral therapy (ART). Epigenetic targeted compounds have shown promise as potential latency-reversing agents; however, these drugs have undesirable toxicity and lack specificity for HIV. We utilized a novel HEK293-derived FlpIn dual-reporter cell line, which quantifies specific HIV provirus reactivation (LTR promoter) relative to nonspecific host cell gene expression (CMV promoter), to identify the 5-substituted 2-acylaminothiazole hit class. Here, we describe the optimization of the hit class, defining the functionality necessary for HIV gene activation and for improving in vitro metabolism and solubility. The optimized compounds displayed enhanced HIV gene expression in HEK293 and Jurkat 10.6 latency cellular models and increased unspliced HIV RNA in resting CD4+ T cells isolated from HIV-infected individuals on ART, demonstrating the potential of the 2-acylaminothiazole class as latency-reversing agents.
- Nguyen, William,Jacobson, Jonathan,Jarman, Kate E.,Jousset Sabroux, Helene,Harty, Leigh,McMahon, James,Lewin, Sharon R.,Purcell, Damian F.,Sleebs, Brad E.
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supporting information
p. 5148 - 5175
(2019/05/28)
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- Organic/inorganic Fe3O4@MCM-41@Zr-piperazine: An impressive magnetite nanocatalyst for N-Tert-Butoxycarbonylation of amines
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Fe3O4@MCM-41@Zirconium magnetic nanoparticles modified with piperazine (Fe3O4@MCM-41@Zr-piperazine), as a newly reported catalyst, shows excellent catalytic activity in N-tertbutoxycarbonylation of amines under the mild and solvent-free conditions. Accordingly, different derivatives of N-tert-butylcarbamates owning diverse aliphatic, aromatic and heteroaromatic amines were prepared efficiently. Good performance of this method for the majority of used complex or acidsensitive substrates and facile separation of this nanocatalyst due to its superparamagnetic nature from the reaction mixture via an external magnetic field for several times are the most important striking features of this protocol.
- Pourhasan-Kisomi, Reyhaneh,Shirini, Farhad,Golshekan, Mostafa
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p. 3859 - 3870
(2019/05/08)
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- Synthesis of cis-β-Amidevinyl Benziodoxolones from the Ethynyl Benziodoxolone-Chloroform Complex and Sulfonamides
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The synthesis of cis-β-amidevinyl benziodoxolones from the ethynyl benziodoxolone-chloroform complex and sulfonamides is reported. Evidence indicates that highly reactive unsubstituted ethynyl benziodoxolone undergoes Michael addition of sulfonamides, including sterically demanding acyclic amino acid derivatives. The synthesis of selectively deuterated cis-β-amidevinyl benziodoxolones and investigation of ethynyl-λ3-iodane reactivity are also described.
- Shimbo, Daisuke,Shibata, Atsushi,Yudasaka, Masaharu,Maruyama, Toshifumi,Tada, Norihiro,Uno, Bunji,Itoh, Akichika
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supporting information
p. 9769 - 9773
(2019/11/28)
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- Lewis Base Promoted, Direct 1,4-Conjugate Addition to Quinone Imine Ketals: Efficient Access to Unsymmetrical Diaryl Sulfones
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An alternative approach with eco-friendliness and high efficiency for the preparation of unsymmetrical diaryl sulfones has been developed. The strategy takes advantage of the reaction of sulfonyl hydrazides with quinone imine ketals catalyzed by DABCO (triethylenediamine) in ethanol. This transformation proceeds via a Lewis base promoted, direct 1,4-conjugate addition/sulfonylation/alcohol elimination reaction sequence. The protocol provides an efficient approach to access an array of diverse unsymmetrical diaryl and heterodiaryl sulfones, aryl alkyl sulfones and aryl vinyl sulfones in good to excellent yields.
- Liu, Teng,Liu, Jianjun,Shen, Xianfu,Xu, Jianbin,Nian, Beifang,He, Ni,Zeng, Shunqun,Cheng, Feixiang
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p. 1365 - 1376
(2019/03/08)
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- Tert-Butyl(3-cyano-4,6-dimethylpyridin-2-yl)carbonate as a green and chemoselective N-tert-butoxycarbonylation reagent
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The use of tert-butyl(3-cyano-4,6-dimethylpyridin-2-yl)carbonate as a chemoselective tert-butoxycarbonylation reagent for aromatic and aliphatic amines has been demonstrated. To gain insight into this reaction, in situ React IR technology was used to confirm the effectivity and chemoselectivity of this novel Boc reagent. The reaction was carried out chemoselectively in high yield under mild, environment-friendly conditions and was completed quickly within 1 hour. Simultaneously, the Boc carrier was easily recyclable, and has great application prospects for industrial production.
- Du, Fangyu,Zhou, Qifan,Fu, Yang,Zhao, Hanqi,Chen, Yuanguang,Chen, Guoliang
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supporting information
p. 6549 - 6554
(2019/05/04)
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- Nickel-Catalyzed Kumada Coupling of Boc-Activated Aromatic Amines via Nondirected Selective Aryl C-N Bond Cleavage
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A nickel-catalyzed Kumada coupling of aniline derivatives was developed by selective cleavage of aryl C-N bonds under mild reaction conditions. Without preinstallation of an ortho directing group on anilines, the cross-coupling reactions of Boc-protected aromatic amines with aryl Grignard reagents afforded unsymmetric biaryls. Mechanistic studies by DFT calculations revealed that the nickel-mediated C-N bond cleavage is the rate-limiting step.
- Zhang, Zheng-Bing,Ji, Chong-Lei,Yang, Ce,Chen, Jie,Hong, Xin,Xia, Ji-Bao
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p. 1226 - 1231
(2019/02/14)
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- A new bifunctional heterogeneous nanocatalyst for one-pot reduction-Schiff base condensation and reduction-carbonylation of nitroarenes
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In this work, synthesis of Pd-NHC-γ-Fe2O3-n-butyl-SO3H and its activity as a bifunctional heterogeneous nanocatalyst containing Pd-NHC and acidic functional groups, are described. This newly synthesized nanomagnetic catalyst is fully characterized by different methods such as FT-IR, XPS, TEM, VSM, ICP and TG analysis. At first, the catalytic activity of Pd-NHC-γ-Fe2O3-n-butyl-SO3H is evaluated for the reduction of nitroarenes in aqueous media using NaBH4 as a clean source of hydrogen generation at ambient temperature. Using the promising results obtained from the nitroarene reduction, this catalytic system is used for two one-pot protocols including reduction-Schiff base condensation and reduction-carbonylation of various nitroarenes. In these reactions the in situ formed amines are further reacted with aldehydes to yield imines or carbonylated to amides. The desired products are obtained in good to high yields in the presence of Pd-NHC-γ-Fe2O3-n-butyl-SO3H as a bifunctional catalyst. The catalyst is reused with the aid of a magnetic bar for up to six consecutive cycles without any drastic loss of its catalytic activity.
- Sobhani, Sara,Chahkamali, Farhad Omarzehi,Sansano, José Miguel
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p. 1362 - 1372
(2019/01/24)
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- Synthesis of Sterically Congested Carbamates of Carbohydrates through Organic Base Catalysis
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4,6-O-Benzylidene acetal protected α-methoxy D-glucose and D-glucosamine are useful building blocks for the syntheses of carbohydrate derivatives and functional molecular assemblies. In this research, we have developed a general method for the preparation of C-3 carbamate derivatives of densely functionalized glucose and glucosamine with isocyanates using organic bases as catalysts. Without a suitable catalyst, the C-3 hydroxy group of the glucosamine derivative could not be converted into the corresponding carbamates when treated with isocyanates. Several organic bases were screened as the catalysts for the reactions, and we discovered that 5.0 molpercent of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was an effective catalyst for the carbamoylation reaction. A library of both alkyl and aryl carbamate derivatives of the two sterically congested carbohydrates have been effectively synthesized using the current method.
- Chen, Anji,Wang, Dan,Samankumara, Lalith P.,Wang, Guijun
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supporting information
p. 2897 - 2908
(2019/07/22)
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- A Fe3O4?SiO2/Schiff Base/Pd Complex as an Efficient Heterogeneous and Recyclable Nanocatalyst for One-Pot Domino Synthesis of Carbamates and Unsymmetrical Ureas
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A palladium-catalyzed domino method for the direct synthesis of carbamates and ureas has been developed by using readily available and economical starting materials (aryl halide, carbon monoxide, sodium azide, amines and alcohols) in a one-pot approach. The domino process underwent carbonylation, Curtius rearrangement, and nucleophilic addition. This protocol provides a step-economical and highly efficient reaction to access the wide range of valuable carbamates, symmetrical and unsymmetrical ureas with high yields under remarkable mild reaction conditions that are important factors in pharmaceutical science, biochemistry and agricultural industries. Furthermore, the magnetically recoverable nanocatalyst (Fe3O4?SiO2/Pd(II)) can be conveniently and swiftly recycled using external magnet and reused at least for seven times without noticeable loss of its catalytic activity.
- Inaloo, Iman Dindarloo,Majnooni, Sahar
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p. 6359 - 6368
(2019/11/05)
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- Carbon dioxide utilization in the efficient synthesis of carbamates by deep eutectic solvents (DES) as green and attractive solvent/catalyst systems
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A green and eco-friendly solvent/catalyst system based on a deep eutectic solvent (DES) was devised and developed for the simple synthesis of carbamates through three-component coupling of amines, alkyl halides and carbon dioxide (CO2). It was found that choline chloride:zinc(ii) chloride ([ChCl][ZnCl2]2) was very proficient and effective for the activation and utilization of CO2 in carbamate formation reactions from a wide scope of amines. Surprisingly, this strategy provides the desired carbamates under atmospheric CO2 pressure at room temperature. In particular, both aromatic and aliphatic amines were effective and demonstrated excellent yields. Besides, the [ChCl][ZnCl2]2 exhibited very high stability and also could be reused for at least five consecutive cycles without any significant loss of activity. It is worth noting that this is the first solvent/catalyst system which can be recycled successfully from the reaction mixture.
- Dindarloo Inaloo, Iman,Majnooni, Sahar
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p. 11275 - 11281
(2019/07/31)
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- An Fe3O4@SiO2/Schiff base/Cu(ii) complex as an efficient recyclable magnetic nanocatalyst for selective mono: N-arylation of primary O-alkyl thiocarbamates and primary O-alkyl carbamates with aryl halides and arylboronic acids
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An efficient, convenient and novel method for the selective mono N-arylation of primary O-alkyl thiocarbamates and primary O-alkyl carbamates with aryl halides and arylboronic acids in the presence of a recyclable magnetic Cu(ii) nanocatalyst is described. A variety of mono N-arylated O-alkyl thiocarbamates and O-alkyl carbamates were prepared in good to excellent yields with a broad range of aryl coupling partners. The magnetic nanocatalyst can be easily recovered with an external magnetic field and reused at least five times without noticeable leaching or loss of its catalytic activity. This cost-effective and eco-friendly methodology has some other advantages, such as easy preparation of the catalyst, simple workup procedure, and easy purification, which makes this protocol interesting for the users in various fields of pharmacology and biotechnology systems.
- Sardarian, Ali Reza,Dindarloo Inaloo, Iman,Zangiabadi, Milad
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p. 8557 - 8565
(2019/06/14)
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- Nickel-catalyzed N-arylation of amines with arylboronic acids under open air
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In this study, a well-defined, novel NHC-Ni complex was developed and used to catalyze the N-arylation of alkyl- and arylamines with arylboronic acids in a rare version of Chan-Lam coupling. Although the same coupling using copper catalysts has been widely studied, the nickel-catalyzed version is rare and normally requires 10–20 mol% catalyst loading. This novel NHC-Ni complex in combination with 4,4′-dimethyl-2,2′-bipyridine, however, proved to be an effective catalyst that lowered the required catalyst loading to only 2.0 mol%.
- Ando, Shin,Hirota, Yurina,Matsunaga, Hirofumi,Ishizuka, Tadao
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supporting information
p. 1277 - 1280
(2019/04/10)
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- Chemoselective: N-tert -butyloxycarbonylation of amines in glycerol
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A catalyst-free, efficient and green protocol has been developed for the chemoselective N-Boc protection of amines by using glycerol as a solvent at room temperature. A variety of functionalized amines, such as aliphatic, aromatic as well as heteroaromatic were protected using the developed protocol. N-tert-Butyloxycarbonylation derivatives were formed without the formation of isocyanate, urea, N,N-di-t-Boc, or oxazolidinone as side products. The operational simplicity, cleaner reaction, rapid reaction convergence, functional group tolerance, excellent yield, high selectivity, catalyst-free feature and solvent recyclability are the distinct advantages of this protocol. Owing to these merits, this protocol is feasible, economical and environmentally benign.
- Ingale, Ajit P.,More, Vishal K.,Gangarde, Uddhav S.,Shinde, Sandeep V.
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supporting information
p. 10142 - 10147
(2018/06/18)
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- Aminolithiation–arylation consecutive cyclization of N-(2-fluorophenyl)methylaminoalkylstyryls giving aryl-substituted pyrido[1,2-b]isoquinolines
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Aminolithiation–arylation tandem cyclization of N-(2-fluorophenyl)methylaminoalkylstyryls proceeded smoothly to give hexahydro-2H-pyrido[1,2-b]isoquinoline using a stoichiometric amount of n-BuLi with high trans selectivity. The arylation reaction was highly accelerated by the addition of HMPA. Both pyrido- and pyrrolo-[1,2-b]isoquinoline were successfully constructed by this tandem reaction.
- Yamamoto, Yasutomo,Nakanishi, Yasue,Yamada, Ken-ichi,Tomioka, Kiyoshi
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supporting information
p. 5309 - 5318
(2018/06/11)
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- One-pot synthesis of polyfunctionalized quinolines: Via a copper-catalyzed tandem cyclization
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An efficient one-pot approach for the synthesis of polyfunctionalized quinolines was developed via a sequence of copper-catalyzed coupling reaction/propargyl-allenyl isomerization/aza-electrocyclization. Easily available starting materials, mild conditions, and a wide substrate scope make this approach potentially useful.
- Chen, Dianpeng,Sun, Xuejun,Shan, Yingying,You, Jinmao
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supporting information
p. 7657 - 7662
(2018/11/02)
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- Ureas as safe carbonyl sources for the synthesis of carbamates with deep eutectic solvents (DESs) as efficient and recyclable solvent/catalyst systems
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A simple, efficient and eco-friendly one-pot synthesis of primary, N-mono- and N-disubstituted carbamates is developed from ureas. The corresponding carbamates were produced at 120 °C, within 18 h, and in the presence of a deep eutectic solvent as a recyclable catalytic system. The catalyst can be reused for several runs without any reduction in its activity. To demonstrate the utility of this approach, a wide variety of alcohols and phenols were studied to find a vast range of carbamate derivatives in moderate to high yields.
- Dindarloo Inaloo, Iman,Majnooni, Sahar
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p. 13249 - 13255
(2018/08/21)
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- Base-Mediated Intramolecular Decarboxylative Synthesis of Alkylamines from Alkanoyloxycarbamates
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A general and effective method for the synthesis of alkylamine via intramolecular decarboxylation of alkanoyloxycarbamates is described. The alkanoyloxycarbamates are readily prepared with alkyl carboxylic acids and hydroxylamine. The reaction shows a broad range of substrates (primary and secondary alkyl) with functional tolerance, and the corresponding products were obtained in good yields under mild conditions.
- Li, Peihe,Ma, Nuannuan,Wang, Zheng,Dai, Qipu,Hu, Changwen
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p. 8233 - 8240
(2018/05/31)
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- Electron transfer-induced reduction of organic halides with amines
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Reduction of a variety of organo halides was examined by using amines as a sacrificial hydrogen source. UV light-induced reduction of vinyl and aryl halides with triethylamine proceeded smoothly to give the corresponding reduced products. High temperature heating also caused the reduction and DABCO (1,4-diazabicyclo[2.2.2]octane) also served as a good reducing reagent.
- Fukuyama, Takahide,Fujita, Yuki,Miyoshi, Hayato,Ryu, Ilhyong,Kao, Shih-Chieh,Wu, Yen-Ku
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supporting information
p. 5582 - 5585
(2018/06/04)
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- Selective Synthesis of Secondary Arylcarbamates via Efficient and Cost Effective Copper-Catalyzed Mono Arylation of Primary Carbamates with Aryl Halides and Arylboronic Acids
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Abstract: An efficient, selective and cost-effective procedure has been developed for mono N-arylation of primary alkyl and benzyl carbamates with aryl iodides and bromides by incorporating CuI as an inexpensive and commercially available catalyst. Despite previous reports on C–N coupling reactions, this process does not need expensive ligands and takes advantage of readily available and inexpensive ethylenediamine (EDA) as the ligand. Reaction times were relatively short and related N-arylated carbamates were obtained in excellent yields. Interestingly, replacing CuI with Cu(OAc)2 allowed us to use arylboronic acids as coupling partner for this reaction. All products are well characterized by 1H- and 13C-NMR, MS, melting point, IR and CHNS techniques.
- Sardarian, Ali Reza,DindarlooInaloo, Iman,Zangiabadi, Milad
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p. 642 - 652
(2018/01/11)
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- N-Arylation of Carbamates through Photosensitized Nickel Catalysis
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A highly efficient method of visible light mediated Ni(II)-catalyzed photoredox N-arylation of Cbz-amines/Boc-amines with aryl electrophiles at room temperature is reported. The methodology provides a common access to a wide variety of N-aromatic and N-heteroaromatic carbamate products that find use in the synthesis of several biologically active molecules and provides a distinct advantage over traditional palladium-catalyzed Buchwald reaction.
- Reddy, Leleti Rajender,Kotturi, Sharadsrikar,Waman, Yogesh,Ravinder Reddy, Vudem,Patel, Chirag,Kobarne, Ajinath,Kuttappan, Sasikumar
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p. 13854 - 13860
(2018/10/31)
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- An efficient one-pot synthesis of N,N′-disubstituted phenylureas and N-aryl carbamates using hydroxylamine-O-sulfonic acid
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We have developed an efficient one-pot method for the microwave-assisted synthesis of ureas and carbamates via a proposed Lossen rearrangement. Herein we report the first examples of the direct conversion of benzoyl chlorides into N,N′-disubstituted ureas and N-aryl carbamates using hydroxylamine-O-sulfonic acid as reagent. Using our general method, we have produced 11 examples of N,N′-disubstituted phenylureas in yields up to 95% using various substituted anilines, and primary and secondary amines. Additionally, we were able to generate a series of N-aryl carbamates in moderate yields using primary, secondary and tertiary alcohols.
- Bao, Jennifer,Kuik, Dale,Tranmer, Geoffrey K.
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supporting information
p. 5546 - 5553
(2018/06/12)
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- Harnessing Cascade Suzuki-Cyclization Reactions of Pyrazolo[3,4-b]pyridine for the Synthesis of Tetracyclic Fused Heteroaromatics
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Numerous procedures have been described for the functionalization of pyrazolo[3,4-b]pyridine, mainly involving nucleophilic substitutions at the C-4 position or esterifications/amidations at the C-5 position. In this paper, we describe a robust, easy to implement protocol for the Suzuki cross-coupling reaction of chloroarene 2, followed by in-situ lactonization to provide chromenopyrazolopyridines. The extension of the scope of the reaction to fused naphthyridinones is also reported. This strategy gave access to 10 original pyrazolopyridine-containing tetracyclic compounds.
- Lavrard, Hubert,Popowycz, Florence
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supporting information
p. 600 - 608
(2017/02/05)
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- [TPA][Pro] ionic liquid as efficient reaction medium for N-tert-Boc protection of amines
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A facile and efficient N-tert-Boc protection of amines is described by the reaction of various primary, secondary, benzylic and aryl amines with di-tert-butyl dicarbonate in the ionic liquid [TPA][Pro] at room temperature. All the N-tert-butylcarbamates are afforded in excellent yields. A catalyst-free method was developed and the ionic liquid [TPA][Pro] can be recovered and reused for several times without loss of its activity.
- Vijaya Durga,Rambabu,Srinivasa Reddy,Hari Babu
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p. 1313 - 1316
(2017/05/02)
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- Efficient and expeditious chemoselective BOC protection of amines in catalyst and solvent-free media
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A green and eco-friendly route for the almost quantitative BOC protection of a large variety of aliphatic and aromatic amines, amino acids, and amino alcohols is reported in catalyst and solvent-free media under mild reaction conditions. The products were confirmed by 1H, 13C NMR, IR spectroscopy, and in some cases, elemental analysis. This protocol does not require any water quenches, solvent separations, and purification steps, such as recrystallization and column chromatography.
- Viswanadham, Balaga,Mahomed, Abdul S.,Friedrich, Holger B.,Singh, Sooboo
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p. 1355 - 1363
(2017/02/15)
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- Preparation, characterization and application of 1,4-disulfopiperazine-1,4-diium chloride ([Piper-(SO3H)2]·2Cl) as an efficient dicationic ionic catalyst for the N-Boc protection of amines
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In this work, 1,4-disulfopiperazine-1,4-diium chloride ([Piper-(SO3H)2]·2Cl), as a novel Br?nsted acidic ionic catalyst is synthesized and characterized using a series of techniques including FT-IR, TGA, DTA, SEM, pH analysis and Hammett acidity function. This substance can significantly catalyze the N-Boc protection of amines without solvent interference at room temperature. The advantages of this manner are chemoselectivity, short reaction times, suitable yields, excellent yields of the products, without solvent interference and ease of preparation as well as reusability of the catalyst.
- Koodehi, Tahereh Ghauri,Shirini, Farhad,Goli-Jolodar, Omid
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p. 443 - 456
(2017/01/10)
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- Sustainable and chemoselective N-Boc protection of amines in biodegradable deep eutectic solvent
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Abstract: A green and practical approach for the chemoselective N-tert-butyloxycarbonylation of structurally diverse amines with di-tert-butyl dicarbonate (Boc2O) is described. Selective N-Boc protection was achieved in excellent yields in urea-choline chloride deep eutectic solvent (DES) as the most promising environmentally benign and cost-effective solvent under mild reaction condition. DES can protect various aromatic and aliphatic amines using Boc2O in good to excellent yields in short reaction times without any side products. Graphical abstract: [Figure not available: see fulltext.].
- Azizi, Najmedin,Shirdel, Fatemeh
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p. 1069 - 1074
(2017/05/12)
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- Iridium-Catalyzed Highly Regioselective Azide-Ynamide Cycloaddition to Access 5-Amido Fully Substituted 1,2,3-Triazoles under Mild, Air, Aqueous, and Bioorthogonal Conditions
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A highly regioselective method to access 5-amido fully substituted 1,2,3-triazoles by iridium-catalyzed azide-ynamide cycloaddition under mild, air, aqueous, and bioorthogonal conditions is reported. The excellent regioselectivities may derive from the strong coordination between the carbonyl oxygen of ynamide and the -acidic iridium. Since the iridium ion is insensitive to oxygen/water and exhibits low cytotoxicity, it could catalyze this reaction in both organic and biological environments efficiently. Preparation in gram-scale and application in carbohydrates highlight this method.
- Song, Wangze,Zheng, Nan
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supporting information
p. 6200 - 6203
(2017/11/24)
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- 1,3,4-OXADIAZOLE DERIVATIVE COMPOUNDS AS HISTONE DEACETYLASE 6 INHIBITOR, AND THE PHARMACEUTICAL COMPOSITION COMPRISING THE SAME
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The present invention relates to novel compounds having histone deacetylase 6 (HDAC6) in-hibitory activity, stereoisomers thereof or pharmaceutically acceptable salts thereof, the use thereof for the preparation of therapeutic medicaments, pharmaceutical compositions containing the same, a method for treating diseases using the composition, and methods for preparing the novel compounds. The novel compounds, stereoisomers thereof or pharmaceutically acceptable salts thereof according to the present invention have histone deacetylase (HDAC) inhibitory activity and are effective for the prevention or treatment of HDAC6-mediated diseases, including infectious diseases; neoplasms; endocrine, nutritional and metabolic diseases; mental and be-havioral disorders; neurological diseases; diseases of the eye and adnexa; cardiovascular diseases; respiratory diseases; digestive diseases; diseases of the skin and subcutaneous tissue; diseases of the musculoskeletal system and connective tissue; or congenital malformations, de? formations and chromosomal abnormalities.
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Paragraph 2933-2935
(2017/02/28)
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- Copper nanoparticles catalyzed N-H functionalization: An efficient solvent-free N-tert-butyloxycarbonylation strategy
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A chemoselective transformation of amines to their tert-butyloxycarbonyl (Boc) protected derivatives (NBoc) is described using Cu-NPs under solvent-free conditions. Simple method, rapid reaction rate, mild conditions, tolerance of a wide range of functional groups, excellent yield, ease recovery and high catalytic turnover are the salient features of this approach. tert-Butyloxycarbonylation of chiral amino acid esters and amino alcohols were performed without racemization.
- Deb, Barnali,Debnath, Sudipto,Deb, Anindita,Maiti, Dilip K.,Majumdar, Swapan
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supporting information
p. 629 - 633
(2017/01/25)
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- Catalytic Reductions and Tandem Reactions of Nitro Compounds Using in Situ Prepared Nickel Boride Catalyst in Nanocellulose Solution
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A mild and efficient method for the in situ reduction of a wide range of nitroarenes and aliphatic nitrocompounds to amines in excellent yields using nickel chloride/sodium borohydride in a solution of TEMPO-oxidized nanocellulose in water (0.01 wt %) is described. The nanocellulose has a stabilizing effect on the catalyst, which increases the turnover number and enables low loading of nickel catalyst (0.1-0.25 mol % NiCl2). In addition, two tandem protocols were developed in which the in situ formed amines were either Boc-protected to carbamates or further reacted with an epoxide to yield β-amino alcohols in excellent yields.
- Prathap, Kaniraj Jeya,Wu, Qiong,Olsson, Richard T.,Dinér, Peter
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supporting information
p. 4746 - 4749
(2017/09/23)
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