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Öğe Cycloaddition of Enamines with 1,4-Dimethoxy-2-butyne and 2-Butyne-1,4-diol Mediated by Titanium Tetrachloride(Taylor & Francis Inc, 2018) Uludağ, Nesimi; Yarapsanlı, Yeşim; Asutay, Oktay; Gümüş, Mustafa Kemal[No Abstract Available]Öğe Facile synthesis of the azocino[4,3-b]indole framework of strychnopivotine and other Strychnos alkaloids(Springer, 2016) Uludağ, Nesimi; Yılmaz, Recep; Asutay, Oktay; Çolak, NakiA new synthetic route to the 1,5-methanoazocino[4,3-b]indole is described. The aim of the present study is to provide a tetracyclic skeleton for the synthesis of pentacyclic Strychnos alkaloids (tubifolidine and strychnopivotine). Starting from a carbazole derivative, the ring closure was achieved by an intramolecular aldol reaction. The final product was obtained in 45% in the overall yield over 7 steps.Öğe Imidazolidin-1-oles, N-2-aminoethyl nitrones and 1,2,5-oxadiazinanes. A novel ring-chain tautomerism(Pergamon-Elsevier Science Ltd, 2007) Coşkun, Necdet; Asutay, OktayImidazolin-3-oxides I were reduced with NaBH4 in THF at reflux to give the corresponding 2,3,5-triarylimidazolidin-l-oles 2, which are proved to be in a ring-chain-ring tautomeric equilibrium with N-2-aminoethyl nitrones 3 and 3,5,6-triphenyl-1,2,5-oxadiazinanes 4. The ratios of the ring and chain form are determined by the substituent at the reaction centre and can be described by the equation logK(x) = p sigma(+) + logK(x=H). These are the first examples of a novel three-component ring-chain-ring tautomeric equilibrium characterized by a Hammett-type equation. The stability of the ring form was favoured by electron-withdrawing substituents. Treatment of the equilibrium mixture of 2, 3 and 4 with phenylisocyanate in refluxing toluene gives selectively the corresponding O-carbamoylated imidazolidines 5; cis-5 was shown to isomerize to trans-5 on heating. (C) 2007 Elsevier Ltd. All rights reserved.Öğe New Route to 20-Deethyldasycarpidone by Ring-Closure with DDQ(Taylor & Francis Inc, 2014) Uludağ, Nesimi; Sanda, Mustafa; Asutay, Oktay; Coşkun, Necdet[No Abstract Available]Öğe Reactions of Methyl Acetylenecarboxylate with Heterocyclic Enamines: [2+2] Cycloadditions in Polar and Non-Polar Solvents(Asian Journal Of Chemistry, 2014) Uludağ, Nesimi; Asutay, Oktay; Yakup, MedetIn this study, enamines of cyclic ketones reacting with methyl acetylenecarboxylate to produce intermadiate cyclobutene adducts have been isolated. Reactions of methyl acetylenecarboxylate with enamines derived from cyclobutene adducts and ring expansion products were described.Öğe Selective oxidative deoximation with anhydrous Ce(IV) sulfate(Pergamon-Elsevier Science Ltd, 2015) Asutay, Oktay; Hamarat, Nilufer; Uludağ, Nesimi; Coşkun, NecdetAnhydrous Ce(SO4)(2) in chloroform selectively converts oximes into the parent carbonyl compounds in good yields. Hammett correlations helped to indicate a plausible mechanism for the above reaction. The formation of 1-(dinitromethyl)benzene was assumed to be a product of isonitroso hydrogen reaction with arylaldoximes. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Selective reduction of 1,4-diarylimidazoline-3-oxides to imidazolidin-1-ols and hydroxylamine derivatives(Springer Wien, 2010) Asutay, Oktay; Coşkun, NecdetC-2-unsubstituted imidazoline-3-oxides were reduced with NaBH4 in THF to give the corresponding trans-3,5-diarylimidazolidin-1-ols, while under the same conditions C-2-substituted derivatives gave the corresponding ring-chain-ring tautomers. Treatment of the crude reaction mixture from the reduction of C-2-unsubstituted imidazoline-3-oxides with a MeOH-H2O mixture provided reductive C-N bond cleavage to give hydroxylamines, while under the same conditions ring-chain-ring tautomers remained unchanged.
