- Photoredox-Catalyzed Dehydrogenative Csp3-Csp2Cross-Coupling of Alkylarenes to Aldehydes in Flow
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Executing photoredox reactions in flow offers solutions to frequently encountered issues regarding reproducibility, reaction time, and scale-up. Here, we report the transfer of a photoredox-catalyzed benzylic coupling of alkylarenes to aldehydes to a flow chemistry setting leading to improvements in terms of higher concentration, shorter residence times, better yields, ease of catalyst preparation, and enhanced substrate scope. Its applicability has been demonstrated by a multi-gram-scale reaction using high-power light-emitting diodes (LEDs), late-stage functionalization of selected active pharmaceutical ingredients (APIs), and also a photocatalyst recycling method.
- Griffiths, Oliver M.,Esteves, Henrique A.,Chen, Yiding,Sowa, Karin,May, Oliver S.,Morse, Peter,Blakemore, David C.,Ley, Steven V.
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p. 13559 - 13571
(2021/10/01)
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- Homobenzylic Oxygenation Enabled by Dual Organic Photoredox and Cobalt Catalysis
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Activation of aliphatic C(sp3)-H bonds in the presence of more activated benzylic C(sp3)-H bonds is often a nontrivial, if not impossible task. Herein we show that leveraging the reactivity of benzylic C(sp3)-H bonds to achieve reactivity at the homobenzylic position can be accomplished using dual organic photoredox/cobalt catalysis. Through a two-part catalytic system, alkyl arenes undergo dehydrogenation followed by an anti-Markovnikov Wacker-type oxidation to grant benzyl ketone products. This formal homobenzylic oxidation is accomplished with high atom economy without the use of directing groups, achieving valuable reactivity that traditionally would require multiple chemical transformations.
- McManus, Joshua B.,Griffin, Jeremy D.,White, Alexander R.,Nicewicz, David A.
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supporting information
p. 10325 - 10330
(2020/07/27)
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- Ni-Catalyzed β-Alkylation of Cyclopropanol-Derived Homoenolates
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Metal homoenolates are valuable synthetic intermediates which provide access to β-functionalized ketones. In this report, we disclose a Ni-catalyzed β-alkylation reaction of cyclopropanol-derived homoenolates using redox-active N-hydroxyphthalimide (NHPI) esters as the alkylating reagents. The reaction is compatible with 1°, 2°, and 3° NHPI esters. Mechanistic studies imply radical activation of the NHPI ester and 2e β-carbon elimination occurring on the cyclopropanol.
- Mills, L. Reginald,Zhou, Cuihan,Fung, Emily,Rousseaux, Sophie A. L.
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supporting information
p. 8805 - 8809
(2019/11/03)
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- Anti-Markovnikov Oxidation of β-Alkyl Styrenes with H2O as the Terminal Oxidant
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Oxygenation of alkenes is one of the most straightforward routes for the construction of carbonyl compounds. Wacker oxidation provides a broadly useful strategy to convert the mineral oil into higher value-added carbonyl chemicals. However, the conventional Wacker chemistry remains problematic, such as the poor activity for internal alkenes, the lack of anti-Markovnikov regioselectivity, and the high cost and chemical waste resulted from noble metal catalysts and stoichiometric oxidant. Here, we describe an unprecedented dehydrogenative oxygenation of β-alkyl styrenes and their derivatives with water under external-oxidant-free conditions by utilizing the synergistic effect of photocatalysis and proton-reduction catalysis that can address these challenges. This dual catalytic system possesses the single anti-Markovnikov selectivity due to the property of the visible-light-induced alkene radical cation intermediate.
- Zhang, Guoting,Hu, Xia,Chiang, Chien-Wei,Yi, Hong,Pei, Pengkun,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 12037 - 12040
(2016/09/28)
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- Addressing challenges in palladium-catalyzed cross-couplings of aryl mesylates: Monoarylation of ketones and primary alkyl amines
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Mor(DalPhos) for Me(sylates): Described are the first examples of ketone mono-α-arylation and primary aliphatic amine monoarylation employing aryl methanesulfonate coupling partners. A range of functionalized aryl mesylates were employed with dialkyl ketones, and also with primary and secondary amines as well as the otherwise challenging coupling partners acetone and methylamine. Ad=adamantyl. Copyright
- Alsabeh, Pamela G.,Stradiotto, Mark
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supporting information
p. 7242 - 7246
(2013/07/26)
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- Two distinct classes of novel pyrazolinecarboxamides as potent cannabinoid CB1 receptor agonists
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The synthesis and SAR of 3-alkyl-4-aryl-4,5-dihydropyrazole-1-carboxamides 1-23 and 1-alkyl-5-aryl-4,5-dihydropyrazole-3-carboxamides 24-27 as two novel cannabinoid CB1 receptor agonist classes were described. The target compounds elicited high
- Lange, Jos H.M.,Attali, Amos,Van Der Neut, Martina A.W.,Wals, Henri C.,Mulder, Arie,Zilaout, Hicham,Duursma, Ate,Van Aken, Hans H.M.,Van Vliet, Bernard J.
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experimental part
p. 4992 - 4998
(2010/10/05)
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- Formation of α-hydroxyketones via irregular Wittig reaction
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Αddition reactions of (1-methoxyalkyl)triphenylphosphonium ylides, derived from the corresponding Wittig salts and n-BuLi, to aldehydes were investigated. It was revealed that the betaine LiX complexes, the primary adducts, were converted to α-hydroxyketones, prior to the formation of oxaphosphetanes, by addition of aqueous NH4Cl at low temperature.
- Okada, Hideki,Mori, Tomonori,Saikawa, Yoko,Nakata, Masaya
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supporting information; experimental part
p. 1276 - 1278
(2009/09/05)
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- 4,5-Dihydro-(1H)-pyrazole derivatives as cannabinoid CB1 receptor modulators
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This invention is directed to 4,5-dihydro-(1H)-pyrazole(pyrazoline) derivatives as cannabinoid CB1 receptor modulators, to pharmaceutical compositions containing these compounds, to methods for the preparation of these compounds, methods for pr
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Page/Page column 10
(2010/11/27)
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- Facile synthesis of ketones from 1,1-disilylethenes via oxidation of gem-disilylalkanes
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The oxidation of gem-disilylalkanes, which can be derived from 1,1-disilylethene, alkyllithiums and alkyl halides, affords the corresponding ketones.
- Inoue, Atsushi,Kondo, Junichi,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 114 - 115
(2007/10/03)
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- C-H and C-C bond activation of primary amines through dehydrogenation and transimination
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Matrix presented Dehydrogenation and subsequent transimination of primary amines offer a new pathway for C-H bond activation, ortho-alkylation, and C-C bond activation to afford a variety of ketones in the reaction of 1-alkene by a cocatalyt system of Rh(I) and 2-amino-3-picoline.
- Jun, Chul-Ho,Chung, Kwan-Yong,Hong, Jun-Bae
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p. 785 - 787
(2007/10/03)
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- Substituted 2-Pyrones, 2-Pyridones, and Other Congeners of Elasnin as Potential Agents for the Treatment of Chronic Obstructive Lung Diseases
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Several congeners of elasnin (I) have been synthesized and shown to inhibit human leukocyte elastase (HLE).The C-3 alkyl substituted 2-pyrones 11 and 12 were found to be most inhibitors of the enzyme.These compounds are highly specific in their inhibitory
- Groutas, William C.,Stanga, Michael A.,Brubaker, Michael J.,Huang, Tien L.,Moi, Min K.,Carroll, Robert T.
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p. 1106 - 1109
(2007/10/02)
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- NOVEL SYNTHESIS OF INTERNAL ALKENYLDIALKYLBORANE BY THE REACTION OF 1-HALO-1-ALKENYLDIALKYLBORANE WITH GRIGNARD REAGENT.
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To synthesize internal alkenyldialkylboranes, coupling reactions were carried out by using 1-halo-1-alkenyldialkylboranes and Grignard reagents. Hydrogen peroxide oxidation and protonolysis with acetic acid of the reaction product revealed that internal (E)-alkenyldialkylborane was formed in 60-90% yield.
- Arase,Hoshi,Masuda
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p. 209 - 213
(2007/10/02)
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- Enamines and iminium salts from amino-acids
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Distillation of ω-carboxyalkyl lactams from soda-lime leads to the formation of bicyclic enamines or imines with concomitant loss of carbon dioxide and water.Monoamides of dicarboxylic acids afford cyclic ketones.A mechanistic rationale is presented and it is concluded that the reaction is a variant of the classical Ruzicka cyclization of dicarboxylic acids.The method allows the regiospecific formation of iminium salts of bicyclic nitrogen heterocycles.
- McHintosh, John M.,Pillon, Lilianna Z.,Acquaah, Samuel O.,Green, James R.,White, Graham S.
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p. 2016 - 2021
(2007/10/02)
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- Formation and Reactions of 1-Phenyl-2-propanone Dianion and Related Systems with Electrophilic Reagents
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1-Phenyl-2-propanone, 1,1-diphenyl-2-propanone, and 1-(4-methoxyphenyl)-2-propanone were converted to their dicarbanions 3, 4, and 31, respectively, and their reactions with a number of electrophilic reagents were examined.All three dianions gave a mixture of C-1 and C-3 alkylation products when treated with alkyl halides of higher reactivity, while only C-1 alkylations occurred when alkyl halides of lower reactivity were used.It was also found that the 1,1-diphenyl-2-propanone and the 1-(4-methoxyphenyl)-2-propanone dianions 4 and 31 gave a higher ratio of C-1/C-3 alkylation products than the 1-phenyl-2-propanone dianion 3.When dianion 3 was reacted with p-anisaldehyde and a number of protonating agents, electrophilic attack occurred exclusively at the C-3 position.The trends observed are analyzed, and mechanisms are proposed to account for the results obtained.
- Trimitsis, G. B.,Hinkley, J. M.,TenBrink, R.,Faburada, A. L.,Anderson, R.,et al.
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p. 2957 - 2962
(2007/10/02)
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