- Iron-Catalyzed Nucleophilic Addition Reaction of Organic Carbanion Equivalents via Hydrazones
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Earth-abundant and well-defined iron complexes are found to be cheap and effective catalysts for a series of "umpolung" nucleophilic additions of hydrazones. The new catalytic system not only maintains the broad substrate scope of an earlier expensive ruthenium system but also attains chemoselectivity of different kinds of carbonyl groups. Furthermore, the iron catalyst enables this reaction at ambient temperature.
- Li, Chen-Chen,Dai, Xi-Jie,Wang, Haining,Zhu, Dianhu,Gao, Jian,Li, Chao-Jun
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supporting information
p. 3801 - 3805
(2018/07/25)
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- Controlling Plasma Stability of Hydroxamic Acids: A MedChem Toolbox
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Hydroxamic acids are outstanding zinc chelating groups that can be used to design potent and selective metalloenzyme inhibitors in various therapeutic areas. Some hydroxamic acids display a high plasma clearance resulting in poor in vivo activity, though they may be very potent compounds in vitro. We designed a 57-member library of hydroxamic acids to explore the structure-plasma stability relationships in these series and to identify which enzyme(s) and which pharmacophores are critical for plasma stability. Arylesterases and carboxylesterases were identified as the main metabolic enzymes for hydroxamic acids. Finally, we suggest structural features to be introduced or removed to improve stability. This work thus provides the first medicinal chemistry toolbox (experimental procedures and structural guidance) to assess and control the plasma stability of hydroxamic acids and realize their full potential as in vivo pharmacological probes and therapeutic agents. This study is particularly relevant to preclinical development as it allows obtaining compounds equally stable in human and rodent models.
- Hermant, Paul,Bosc, Damien,Piveteau, Catherine,Gealageas, Ronan,Lam, Baovy,Ronco, Cyril,Roignant, Matthieu,Tolojanahary, Hasina,Jean, Ludovic,Renard, Pierre-Yves,Lemdani, Mohamed,Bourotte, Marilyne,Herledan, Adrien,Bedart, Corentin,Biela, Alexandre,Leroux, Florence,Deprez, Benoit,Deprez-Poulain, Rebecca
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supporting information
p. 9067 - 9089
(2017/11/14)
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- Sunlight-driven trifluoromethylation of olefinic substrates by photoredox catalysis: A green organic process
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The principles and utility of photoredox catalysis in organic synthesis are described. After a brief description of the features of the two types of catalytic photoredox processes following the reductive quenching cycle (RQC) and the oxidative quenching cycle (OQC), the discussion is focused on organic transformations based on OQC, in particular the trifluoromethylation of olefinic substrates with electrophilic trifluoromethylating reagents furnishing solvolytic addition products and substitution products. It is concluded that catalytic photoredox systems are green from the point of view of harmfulness, safety, and energy source (visible light, including sunlight). Future prospects of photoredox catalysis will be also discussed.
- Akita, Munetaka,Koike, Takashi
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p. 742 - 751
(2015/07/15)
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- Fluorine transfer to alkyl radicals
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The development of new synthetic technologies for the selective fluorination of organic compounds has increased with the escalating importance of fluorine-containing pharmaceuticals. Traditional methods potentially applicable to drug synthesis rely on the use of ionic forms of fluorine (F - or F+). Radical methods, while potentially attractive as a complementary approach, are hindered by a paucity of safe sources of atomic fluorine (F?). A new approach to alkyl fluorination has been developed that utilizes the reagent N-fluorobenzenesulfonimide as a fluorine transfer agent to alkyl radicals. This approach is successful for a broad range of alkyl radicals, including primary, secondary, tertiary, benzylic, and heteroatom-stabilized radicals. Furthermore, calculations reveal that fluorine-containing ionic reagents are likely candidates for further expansion of this approach to polar reaction media. The use of these reagents in alkyl radical fluorination has the potential to enable powerful new transformations that otherwise would take multiple synthetic steps.
- Rueda-Becerril, Montserrat,Chatalova Sazepin, Claire,Leung, Joe C. T.,Okbinoglu, Tulin,Kennepohl, Pierre,Paquin, Jean-Francois,Sammis, Glenn M.
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supporting information; experimental part
p. 4026 - 4029
(2012/04/10)
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- CARBOXYLIC DERIVATIVES FOR USE IN THE TREATMENT OF CANCER
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The invention provides novel compounds of formula (I), wherein: R1 is a radical derived from one of the known ring systems; R2 is a phenyl radical optionally substituted; Xn represents a birradical selected from the group consisting of: -(CH2)1-4-, (C2-C4)-alkenyl, (C2-C4)alkynyl, -S-(CH2)1-3-#, and -(CH2)1-3-O-#; wherein the symbol # indicates the position at which Xn is attached to R1; Yn is a birradical selected from the group consisting of: -(CH2)2-4-, -S-(CH2)1-3#, and -O-(CH2)1-3-#,; where in the symbol # indicates the position at which Yn is attached to R2; and R3 is a radical selected from the group consisting of: -OR4. The compounds of formula (I) are useful in the treatment of cancer
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Page/Page column 24-25
(2009/07/25)
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- Free radical-promoted conjugate addition of activated bromo compounds using titanocene(III) chloride as the radical initiator
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Free radical-promoted conjugate addition of activated bromo compounds to α,β-unsaturated ketones and reactive α,β-unsaturated esters has been described using titanocene(III) chloride (Cp2TiCl) as the radical initiator. Cp2TiCl was prepared in situ from commercially available Cp2TiCl2 and activated zinc dust in THF.
- Mandal, Samir Kumar,Jana, Samaraesh,Roy, Subhas Chandra
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p. 6115 - 6117
(2007/10/03)
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- Radical cyanocarbonylation using alkyl allyl sulfone precursors
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Acyl cyanides have been prepared by the three-component coupling reactions comprised of alkyl allyl sulfones, carbon monoxide, and p-tolylsulfonyl cyanide under tin-free radical reaction conditions. Georg Thieme Verlag Stuttgart.
- Kim, Sangmo,Cho, Chang Ho,Kim, Sunggak,Uenoyama, Yoshitaka,Ryu, Ilhyong
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p. 3160 - 3162
(2007/10/03)
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- Free radical-mediated carboxylation by radical reaction of alkyl iodides with methyl oxalyl chloride
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Free radical-mediated carboxylation is achieved by treatment of alkyl iodides with methyl oxalyl chloride and bis(tributyltin) in benzene at 350 nm to afford the corresponding acid chlorides as a major product along with a small amount of the methyl esters.
- Kim, Sunggak,Jon, Sang Yong
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p. 7317 - 7320
(2007/10/03)
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- Chromium(II)-Mediated Intermolecular Free-Radical Carbon-Carbon Bond Formation
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Chromium(II) complexes are found to be effective mediators for intermolecular free-radical C-C bond formation.Thus, Cr(en)2(2+) species react with alkyl halides to generate the corresponding alkyl radicals which are readily trapped with electron-deficient alkenes to afford the coupling products.Key Words: Radicals / Bond formation, C-C / Chromium(II) complexes
- Tashtoush, Hasan I.,Sustmann, Reiner
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p. 287 - 289
(2007/10/02)
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- Selective Mono- and Bis(alkoxycarbonylation)s of Olefins Catalyzed by Palladium in the Presence of Cu(I) or Cu(II) Chloride under Remarkably Mild Conditions. Application to the Synthesis of γ-Butyrolactone Derivatives
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Palladium-catalyzed mono- and bis(alkoxycarbonylation)s of the olefins were controlled by the use of copper(II) and copper(I) chloride, respectively, in alcohol under normal pressure of carbon monoxide and oxygen at room temperature without any other additives. 3-Buten-1-ols gave the corresponding γ-butyrolactones and 2-oxotetrahydrofuran-3-acetic acid esters, respectively, in high yields.
- Toda, Shiho,Miyamoto, Masanori,Kinoshita, Hideki,Inomata, Katsuhiko
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p. 3600 - 3606
(2007/10/02)
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- Selective Mono- and Dicarbonylation of Terminal Olefins Catalyzed by Pd-C in the Presence of Cu(II) or Cu(I) Chloride under Mild Conditions
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Pd-C can catalyze the carbonylation of terminal olefins with normal pressure of carbon monoxide at room temperature.The corresponding mono- and diesters (succinates) were selectively formed in excellent yields using Cu(II) and Cu(I) chloride, respectively, in alcohol.
- Inomata, Katsuhiko,Toda, Shiho,Kinoshita, Hideki
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p. 1567 - 1570
(2007/10/02)
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- Catalytic Hydrogenolysis of Methyl 2-Siloxycyclopropanecarboxylates: Investigations Regarding Chemoselectivity, Regioselectivity, and Stereoselectivity
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Alkyl-substituted methyl 2-(trimethylsiloxy)cyclopropanecarboxylates 8a - 8f are opened by hydrogen in the presence of palladium on carbon affording 4-oxoalkanoic esters 10a - 10e by desilylation. 2-Phenyl-substituted cyclopropanes 8g - 8j, however, provide 4-phenylbutanoic esters 13g - 13j under these conditions.Formation of 13j is not stereoselective.Here the primary cyclopropane cleavage is followed by hydrogenolysis of the benzylic C-O bond.This subsequent reaction can be suppressed in the case of 8g by poisoning the catalyst with triethylamine; otherwise the tert-butyldimethylsiloxy compounds 11g - 11i have to be used.Butanoic esters 14h and 14i, respectively, are formed as mixtures of diastereomeres, which is another indication for nonstereoselective hydrogenolysis of cyclopropanes.Whereas slow desilylation by hydrogen was observed with the 3-phenyl-substituted cyclopropane derivative 8k, the vinylcyclopropane 8m in part suffers cleavage of the 1-3 bond of the three-membered ring.Regio- and stereoselectivity of the hydrogenolysis of the donor-acceptor-substituted cyclopropanes 8 and 11 are discussed.
- Brueckner, Christiane,Reissig, Hans-Ulrich
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p. 617 - 626
(2007/10/02)
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