- Radical Hydroarylation of Functionalized Olefins and Mechanistic Investigation of Photocatalytic Pyridyl Radical Reactions
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We report the photoredox alkylation of halopyridines using functionalized alkene and alkyne building blocks. Selective single-electron reduction of the halogenated pyridines provides the corresponding heteroaryl radicals, which undergo anti-Markovnikov addition to the alkene substrates. The system is shown to be mild and tolerant of a variety of alkene and alkyne subtypes. A combination of computational and experimental studies support a mechanism involving proton-coupled electron transfer followed by medium-dependent alkene addition and rapid hydrogen atom transfer mediated by a polarity-reversal catalyst.
- Seath, Ciaran P.,Vogt, David B.,Xu, Zihao,Boyington, Allyson J.,Jui, Nathan T.
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p. 15525 - 15534
(2018/11/23)
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- Nucleophilic addition of arylmethylzinc reagents (ArCH2ZnCl) to formaldehyde: An easy access to 2-(hetro)arylethyl alcohols
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The selective addition of arylmethylmagnesium halides with formaldehyde giving arylethyl alcohols is extremely challenging. To circumvent the difficulties, in the current communication, we have reported on the nucleophilic addition of benzyl zinc reagents derived from inexpensive and abundant benzyl chlorides to paraformaldehyde. The reaction investigated herein is hitherto unknown and was found to be selective, operationally simple, atom- and step-economical and high yielding to deliver phenethyl alcohols utilized as key perfumery ingredients in 60–83% yields. After successful establishment of the reaction condition, the reaction was also scaled up successfully to deliver a large-scale preparation of the phenethyl alcohol.
- Bhatt,Samant,Pednekar, Suhas
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supporting information
p. 968 - 974
(2017/05/04)
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- Discovery of Potent Human Glutaminyl Cyclase Inhibitors as Anti-Alzheimer’s Agents Based on Rational Design
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Glutaminyl cyclase (QC) has been implicated in the formation of toxic amyloid plaques by generating the N-terminal pyroglutamate of β-amyloid peptides (pGlu-Aβ) and thus may participate in the pathogenesis of Alzheimer’s disease (AD). We designed a library of glutamyl cyclase (QC) inhibitors based on the proposed binding mode of the preferred substrate, Aβ3E?42. An in vitro structure-activity relationship study identified several excellent QC inhibitors demonstrating 5- to 40-fold increases in potency compared to a known QC inhibitor. When tested in mouse models of AD, compound 212 significantly reduced the brain concentrations of pyroform Aβ and total Aβ and restored cognitive functions. This potent Aβ-lowering effect was achieved by incorporating an additional binding region into our previously established pharmacophoric model, resulting in strong interactions with the carboxylate group of Glu327 in the QC binding site. Our study offers useful insights in designing novel QC inhibitors as a potential treatment option for AD.
- Hoang, Van-Hai,Tran, Phuong-Thao,Cui, Minghua,Ngo, Van T. H.,Ann, Jihyae,Park, Jongmi,Lee, Jiyoun,Choi, Kwanghyun,Cho, Hanyang,Kim, Hee,Ha, Hee-Jin,Hong, Hyun-Seok,Choi, Sun,Kim, Young-Ho,Lee, Jeewoo
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p. 2573 - 2590
(2017/04/03)
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- (N -Phosphinoamidinate)Iron pre-catalysts for the room temperature hydrosilylation of carbonyl compounds with broad substrate scope at low loadings
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The synthesis and structural characterization of three-coordinate iron(II) and cobalt(II) complexes supported by new N-phosphinoamidinate ligands is reported, along with the successful application of these complexes as precatalysts for the challenging room-temperature hydrosilylation of carbonyl compounds to afford alcohols upon workup. Under the rigorous screening conditions employed (0.015 mol % Fe) for the reduction of acetophenone, the well-defined iron(II) amido precatalyst 2b, featuring bulky N-2,6- diisopropylphenyl and di-tert-butylphosphino moieties within the N-phosphinoamidinate ligand, exhibited exceptional catalytic performance. Further experimentation revealed that the yield achieved in the hydrosilylation of acetophenone employing 2b was unaltered when conducting reactions in the absence of light, in the presence of excess mercury, or under solvent-free conditions. Notably, precatalyst 2b was found to exhibit the broadest substrate scope reported to date for such room-temperature iron-catalyzed carbonyl hydrosilylations en route to alcohols, enabling the chemoselective reduction of structurally diverse aldehydes and ketones, as well as for the first time esters, at remarkably low loadings (0.01-1.0 mol % Fe) and using only 1 equiv of phenylsilane reductant.
- Ruddy, Adam J.,Kelly, Colin M.,Crawford, Sarah M.,Wheaton, Craig A.,Sydora, Orson L.,Small, Brooke L.,Stradiotto, Mark,Turculet, Laura
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supporting information
p. 5581 - 5588
(2013/11/06)
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- Tetrazole excitatory amino acid receptor antagonists
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The present invention provides novel tetrazole derivatives useful as excitatory amino acid receptor antagonists and in treating a variety of associated nervous system disorders.
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- Method of regulating the immune response with pyridine derivatives
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A series of 4-(2-carboxymethylthiomethyl)pyridines and related compounds, and their pharmaceutically acceptable salts, are disclosed as having immunoregulatory activity. Preferred compounds include 4-(2-carboxymethylthiomethyl)pyridine [alternatively named 2-(4-picolylthio)acetic acid] and (C1 -C4)alkyl esters thereof, and 4-(1-formylmethylthiomethyl)-pyridine [alternatively named 2-(4-picolylthio)acetaldehyde] and bis(C1 -C4)alkyl or cyclic acetals thereof. These acids, esters, aldehydes and acetals also have utility as intermediates in the synthesis of the corresponding 4-(2-hydroxyethylthiomethyl)pyridines.
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- Certain pyridine methylthio acetaldehyde derivatives and non-cyclic and cyclic acetals thereof
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A series of 4-(2-carboxymethylthiomethyl)pyridines and related compounds, and their pharmaceutically acceptable salts, are disclosed as having antiinflammatory and immunoregulatory activity. Preferred compounds include 4-(2-carboxymethylthiomethyl)pyridine [alternatively named 2-(4-picolylthio)acetic acid] and (C1 -C4)alkyl esters thereof, and 4-(1-formylmethylthiomethyl)pyridine [alternatively named 2-(4-picolylthio)-acetaldehyde] and bis(C1 -C4)alkyl or cyclic acetals thereof. These acids, esters, aldehydes and acetals also have utility as intermediates in the synthesis of the corresponding 4-(2-hydroxyethylthiomethyl)pyridines.
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- Structural Factors Affecting the Basicity of ω-Pyridylalkanols, ω-Pyridylalkanamides and ω-Pyridylalkylamines
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The present paper describes the preparation by conventional methods (when not available commercially) and the pKa-determination of the α-, β- and γ-isomers of pyridylethanamide, 3-pyridylpropanamide, 4-pyridylbutanamide, 5-pyridylpentanamide, pyridylmethanol, 2-pyridylethanol, 3-pyridylpropanol, 4-pyridylbutanol, 5-pyridylpentanol, pyridylmethylamine, 2-pyridylethylamine, 3-pyridylpropylamine, 4-pyridylbutylamine, and 5-pyridylpentylamine.While a field effect accounts for many variations in pKa as a function of chain length, marked inductive effects are operative in some methyl and ethyl homologs.The pKa-decreasing influence of an intramolecular H-bond is also apparent in some lower homologs belonging to the α-series.
- Mayer, Joachim M.,Testa, Bernard
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p. 1868 - 1884
(2007/10/02)
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