- Modular Regiospecific Synthesis of Nitrated Fatty Acids
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Endogenous nitrated fatty acids are an important class of signaling molecules. Herein a modular route for the efficient and regiospecific preparation of nitrooleic acids as well as various analogues is described. The approach is based on a simple set of alkyl halides as common building blocks and a Henry reaction/Burgess dehydration sequence for the formation of the key nitroalkene moiety.
- Hock, Katharina J.,Grimmer, Jennifer,G?bel, Dominik,Gasaya, George Gichogo T.,Roos, Jessica,Maucher, Isabelle V.,Kühn, Benjamin,Fettel, Jasmin,Maier, Thorsten J.,Manolikakes, Georg
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- Novel cytotoxic amphiphilic nitro-compounds derived from a synthetic route for paraconic acids
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A series of precursors for bioactive paraconic acids (PA) were synthesized and their cytotoxicity assessed on human cells in vitro. Two amphiphilic nitro-containing precursors, Nitro-C15-EED and the butanolide Nitro-C12-GBL, were cytotoxic at the micromolar scale, with higher activity on tumor HeLa cells than on HEK-293T of non-tumor origin. The structure of these molecules is simple but different from reported bioactive nitro compounds. Nitro-C12-GBL was generally more cytotoxic, but after short-term (2 h) exposure both compounds reached maximum cytotoxicity. At 72 h post-treatments of HeLa cells the final dose-response for Nitro-C12-GBL (LC50 = 21.9 μmol L?1) was close to that for Nitro-C15-EED (LC50 = 25.3 μmol L?1), corresponding to LC50s ~ 3–3.6 times lower than those on HEK-293T. Short-term treatments with 50 μmol L?1 of these compounds promoted comparable outcomes, reducing tumor cells viability up to 27–36% of the controls and preserving ~70% of HEK-293T viability at 72 h post-treatments. Reduced cytotoxicity was observed in cultures continuously exposed to the compounds for longer periods (24–72 h), especially on tumor cells, underlining short-term treatments as alternatives to antiproliferative strategies. Due to their amphiphilic nature, these compounds show spontaneous surface activity and adsorption onto Langmuir monolayers of dipalmitoyl phosphatidyl choline (DPPC), especially Nitro-C12-GBL. The effects on DPPC monolayers are indicative of a possible physiological action that depends on the interaction with the cell membranes. Coarse-grained molecular dynamics indicate that individualized molecules of Nitro-C15-EED and the less toxic PA precursors are susceptible to trapping into phospholipid films. In contrast, Nitro-C12-GBL consistently forms large aggregates with outward polar domains, which could favor interaction with phospholipid polar heads of biological membranes.
- Ribeiro, Talita A.,Machado-Ferreira, Erik,Guimar?es, Lohaine F.,Cavaleiro, Jéssica,Britto, Alan Messala A.,Redua, Nátaly,de Souza, Lucas Miguel Pereira,Pimentel, André S.,Picciani, Paulo H.S.,Oliveira, Osvaldo N.,Barreto, Cléber Bonfim,Soares, Carlos Augusto G.
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- Ozone-Mediated Amine Oxidation and Beyond: A Solvent-Free, Flow-Chemistry Approach
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Ozone is a powerful oxidant, most commonly used for oxidation of alkenes to carbonyls. The synthetic utility of other ozone-mediated reactions is hindered by its high reactivity and propensity to overoxidize organic molecules, including most solvents. This challenge can largely be mitigated by adsorbing both substrate and ozone onto silica gel, providing a solvent-free oxidation method. In this manuscript, a flow-based packed bed reactor approach is described that provides exceptional control of reaction temperature and time to achieve improved control and chemoselectivity over this challenging transformation. A powerful method to oxidize primary amines into nitroalkanes is achieved. Examples of pyridine, C-H bond, and arene oxidations are also demonstrated, confirming the system is generalizable to diverse ozone-mediated processes.
- Skrotzki, Eric A.,Vandavasi, Jaya Kishore,Newman, Stephen G.
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supporting information
p. 14169 - 14176
(2021/06/30)
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- Chiral Pool/Henry/Enzymatic routes to acetogenin synthons
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Enantio specific and enantioselective approaches to the natural (16 R,19R)- and the unnatural (16S,19S)- THF core of the bioactive acetogenin annonacin are described which utilizes both a chiral pool synthesis and enzymatic transformations. In the antipodal (2S,5S) THF series derived from D-(+)-glucosamine, the semi-protected THF aldehyde synthon allows for two-directional synthetic elaboration through a Henry reaction with a lipid-like nitroalkane. The resulting nitroalcohol having the unnatural (2S,5S)-THF core was oxidized to the corresponding a-nitroketone using a modified Collins oxidation. The intermediate a-nitroketone has potential for the preparation of the C15-C32 core and analogues through subsequent removal of the nitro group and reduction of the carbonyl.
- Qayed, Wesam S.,Luzzio, Frederick A.
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supporting information
p. 622 - 630
(2015/11/09)
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- Facile reduction of nitroarenes into anilines and nitroalkanes into hydroxylamines via the rapid activation of ammonia· borane complex by supported gold nanoparticles
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Gold nanoparticles supported on titania catalyse, even at a ppm loading level, the quantitative reduction of nitroarenes into anilines and nitroalkanes into alkylhydroxylamines by the ammonia× borane complex. No dehalohalogenation was seen in the case of chloro- or bromonitroarenes, while ester, cyano, or carboxylic acid functionalities also remain intact. The nitroarene to aniline reduction pathway does not require nitrosoarenes as intermediate products. Copyright
- Vasilikogiannaki, Eleni,Gryparis, Charis,Kotzabasaki, Vasiliki,Lykakis, Ioannis N.,Stratakis, Manolis
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supporting information
p. 907 - 911
(2013/05/08)
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- Sequential continuous flow processes for the oxidation of amines and azides by using HOF·MeCN
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The generation and use of the highly potent oxidising agent HOF·MeCN in a controlled single continuous flow process is described. Oxidations of amines and azides to corresponding nitrated systems by using fluorine gas, water and acetonitrile by sequential gas-liquid/liquid-liquid continuous flow procedures are reported. Oxidation in flow: The oxidation of amines and azides to the corresponding nitrated systems by using fluorine gas, water and acetonitrile by sequential gas-liquid/liquid-liquid continuous flow procedures are reported. Copyright
- McPake, Christopher B.,Murray, Christopher B.,Sandford, Graham
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scheme or table
p. 312 - 319
(2012/06/15)
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- Alternative method for the reduction of aromatic nitro to amine using TMDS-iron catalyst system
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The system 1,1,3,3-tetramethyldisiloxane (TMDS)/Fe(acac)3 is reported here as a new method to obtain amines from aromatic nitro compounds. Amines are synthetized in a straightforward step and are isolated as hydrochloride salts with good to excellent yields. This system has shown a good selectivity toward aryl-chloride, aryl-bromide, ester, carboxylic acid, and cyano groups. The reduction of alkylnitro compounds was unfortunately not possible using this method, only a mixture of mono and dialkylated amine was obtained.
- Pehlivan, Leyla,Métay, Estelle,Laval, Stéphane,Dayoub, Wissam,Demonchaux, Patrice,Mignani, Gérard,Lemaire, Marc
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scheme or table
p. 1971 - 1976
(2011/04/22)
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- Scope and mechanistic insights into the use of tetradecyl(trihexyl) phosphonium bistriflimide: A remarkably selective ionic liquid solvent for substitution reactions
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A survey of substitution reactions conducted in a phosphonium bistriflimide ionic liquid is presented. The results demonstrate high selectivity favoring substitution over typically competitive elimination and solvolytic processes even when challenging secondary and tertiary electrophiles are employed. The first reports of Kornblum substitution reactions in an ionic liquid are described that proceed with very high chemoselectivity in favor of nitro over nitroso products and elimi nation side products. The structure-reactivity study indicates that these reactions proceed through a narrow spectrum of pathways ranging from straight SN2 to a preassociation pathway along a saddle point that approaches the SN1 limit. The barrier to the formation of dissociated carbocations is attributed to the structural features of this ionic liquid that favor intervention of the associated nucleophile over dissociation, also preventing cross over to E1 processes. The lack of any basic entity in the phosphonium bistriflimide ionic liquid appears to prevent any potential base-mediated elimination reactions, which makes this a highly selective medium for use in general substitution reactions.
- McNulty, James,Nair, Jerald J.,Cheekoori, Sreedhar,Larichev, Vladimir,Capretta, Alfredo,Robertson
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p. 9314 - 9322
(2007/10/03)
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- Synthesis of nitroalkanes from alkylhalides under mild and nonaqueous conditions by using polymer supported nitrites
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Alkyl halides are efficiently converted to their corresponding nitroalkanes under mild and nonaqueous conditions by using polymer supported nitrites. The polymeric reagent is regenerable.
- Zarchi, Mohammad Ali Karimi,Zarei, Amin
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p. 309 - 311
(2007/10/03)
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