Yazar "Kariuki, Benson M." seçeneğine göre listele

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    [1,3]-Dipolar cycloaddition of N-aryl sydnones to benzothiophene 1,1-dioxide, 1-cyclopropylprop-2-yn-1-ol and 1-(prop-2-ynyl)-1H-indole
    (Pergamon-Elsevier Science Ltd, 2014) Dürüst, Yaşar; Sağırlı, Akın; Kariuki, Benson M.; Knight, David W.
    [1,3]-Dipolar cycloadditions of N-aryl sydnones to benzothiophene 1,1-dioxide, 1-cyclopropylprop-2-yn-1-ol and 1-(prop-2-ynyl)indole gave fused pyrazole derivatives when carried out in refluxing toluene. While the first two dipolarophiles gave single regioisomers, this indolic derivative gave mixtures, the ratios of which appeared to be controlled by the phenyl substituents. Their structures were identified in the usual manner, supported by single crystal X-ray diffraction measurements. (C) 2014 Elsevier Ltd. All rights reserved.
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    Base-promoted new C-C bond formation: an expedient route for the preparation of thiazolo- and imidazolo-pyridinones via Michael addition
    (Pergamon-Elsevier Science Ltd, 2014) Yıldırım, Muhammet; Çelikel, Derya; Evis, Naciye; Knight, David W.; Kariuki, Benson M.
    Base-catalyzed one-pot cyclocondensation reactions of acryloyl and cinnamoyl chlorides with beta-nitroenamine derivatives have been performed under mild conditions and target 7-substituted thiazolo-[3,2-alpha] or imidazolo-[1,2-alpha]pyridin-5-one derivatives were prepared successfully in moderate to good yields. The cyclization reactions may proceed via Michael addition followed by iminoketene-amide tautomerization in view of the products formed. (C) 2014 Elsevier Ltd. All rights reserved.
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    Novel sydnone derivatives carrying azidomethyl-1,2, 4-oxadiazole unit and their 1,3-dipolar cycloadditions
    (Taylor & Francis Inc, 2017) Dürüst, Yaşar; Yıldız, Elif; Karakuş, Hamza; Kariuki, Benson M.
    A series of 1,2,4-oxadiazolymethyl sydnones carrying azido group were synthesized and subjected to react with a variety of alkenic and acetylenic dipolarophilic reagents; N-phenyl maleimide, phenyl vinyl sulfone, and phenyl propiolic acid. All the new products are identified by spectral/physical data including high-resolution mass measurements and X-ray diffraction data.
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    A rapid and efficient protocol for the synthesis of novel nitrothiazolo [3,2-c]pyrimidines via microwave-mediated Mannich cyclisation
    (Pergamon-Elsevier Science Ltd, 2014) Yıldırım, Muhammet; Çelikel, Derya; Dürüst, Yaşar; Knight, David W.; Kariuki, Benson M.
    Several 6-substituted-8-nitrothiazolo[3,2-c]pyrimidine derivatives have been obtained very efficiently by a multicomponent cyclisation of 2-(nitromethylene)thiazolidine, formaldehyde and various aliphatic or aromatic amines in water, using both microwave irradiation and conventional heating. Reaction yields were considerably higher and the reaction times very much reduced using microwave heating when compared to conventional heating, resulting in the definition of a rapid and efficient synthetic protocol. (C) 2014 Elsevier Ltd. All rights reserved.
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    Reaction of heterocyclic enamines with nitrile oxide and nitrilimine precursors
    (Royal Soc Chemistry, 2010) Altuğ, Cevher; Dürüst, Yaşar; Elliott, Mark C.; Kariuki, Benson M.; Rorstad, Tillique; Zaal, Mark
    Alkylidenepyrrolidines 1, 21, 24 and 26 undergo reactions with nitrile oxides and nitrilimines or their precursors to give a range of novel heterocyclic compounds. With alkylidenepyrrolidine ester 1, nitrolic acids give products in which the liberated nitrous acid reacts with the alkylidenepyrrolidine, followed by two cycloadditions to give adducts 3. In contrast, hydroximoyl chlorides give isoxazoles 10, presumably by cycloaddition/elimination. With hydrazonyl chlorides, simple acylation of the alkylidenepyrrolidine occurs to give compounds 17. With sulfonyl alkylidenepyrrolidines 24 and 26, cycloaddition onto the imine tautomer is the preferred pathway, with a stereoselective reaction taking place in the latter case.
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    Some reactions of 2-(4-substitutedphenyl)-2-(n-methyl-n-4-substitutedbenzamido) acetic acids
    (Taylor & Francis Inc, 2018) Dürüst, Yaşar; Karakuş, Hamza; Kariuki, Benson M.; Knight, David W.
    In situ generated 2,4-diaryl substituted munchnones from 2-(4-substitutedphenyl)-2-(N-methyl-N-4-substitutedbenzamido)acetic acids react with acetic anhydride in the presence of 2-nitromethylene thiazolidine, which is most likely acting as a base, and unexpectedly undergo a Dakin-West type reaction and a concurrent autoxidation reaction leading to the formation of (E)-1-(N,4-dimethylbenzamido)-1-(4-fluorophenyl)prop-1-en-2-yl acetate, 4-substitutedphenyl-N-methyl-N-(4-substitutedbenzoyl) benzamides and p-substituted benzoic acids. In addition, a novel and efficient access to N-acyl urea derivatives is described by the reaction between 2-(4-substitutedphenyl)-2-(N-methyl-N-4-substitutedbenzamido)acetic acids and cyclohexyl, isopropyl carbodiimides in the presence of a base. The structures of all new products were identified on the basis of NMR and IR spectra, along with X-ray diffraction data and HRMS measurements. [GRAPHICS] .
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    Tandem nitrosation/cycloaddition of heterocyclic enamines using nitrolic acids
    (Pergamon-Elsevier Science Ltd, 2009) Altuğ, Cevher; Dürüst, Yaşar; Elliott, Mark C.; Kariuki, Benson M.
    The reaction of alkylidenepyrrolidines with nitrolic acids gives rise to the formation of novel 3,7a-disubstituted (1,2,4-oxadiazol-5-yl)-5,6,7,7a-tetrahydropyrrolo[1,2-d][1,2,4]oxadiazoles. A plausible mechanism for this reaction is proposed, which features nitrosation of the enamine by the nitrous acid that is liberated from the nitrolic acid. (C) 2009 Elsevier Ltd. All rights reserved.