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    Acid Catalyzed One-pot Three-component Biginelli-type Synthesis of Some New Symmetrical Bis 3,4-dihydropyrimidin-2(1H)-ones/thiones
    (Wiley, 2018) Gulten, Sirin; Arslan, Ezgi
    Biologically important 21 new symmetrical bis 3,4-dihydropyrimidin-2(1H)-ones/thiones were synthesized by reacting 4,4 '-diaminodiphenyl ether/4,4 '-ethylenedianiline with tert-butyl acetoacetate to produce diphenyl ether-bridged bis beta-keto amide/diphenyl ethane-bridged bis beta-keto amide then treated with urea or thiourea and an appropriate aldehyde with either a catalytic amount of p-TSA center dot H2O or conc. HCl in ethanol afforded the title compounds.
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    Fast and Efficient One-Pot Three-Component Synthesis of Some 1,2,3,4-Tetrahydro-6-methyl-N-phenyl-5-pyrimidinecarboxamide Derivatives via Biginelli Condensation Reaction
    (Bentham Science Publ Ltd, 2020) Gulten, Sirin; Gezerl, Ufuk; Gundogan, Elmas Aksanli
    Tetrahydropyrimidine (THPM) synthesis has an enormous importance in organic chemistry and especially in pharmaceutical applications. Pyrimidines are the most active class of N-containing heterocyclic compounds and have different biological properties. The heterocyclic ring system with a thio group occupy a unique position in medicinal chemistry. This type of compounds play an important role in synthetic drugs and in biological processes. Dihydropyrimidinethione derivatives occur widely in nature. Several modifications of TIIPM-5-carboxamides have attracted considerable interest of medicinal chemists due to their pharmacological and therapeutic properties. A series of 1,2,3,4-tetrahydro-2-pyrimidinone/thione derivatives bearing a phenylcarbamoyl group at C-5 position were synthesized by one-pot three-component Biginelli condensation reaction. The reaction of acetoacetanilide as the 1,3-dicarbonyl component with various aromatic aldehydes and urea/thiourea in the presence of a catalytic amount of p-toluenesulfonic acid monohydrate (PTSA.H2O) or concentrated HCl as an efficient catalyst leads to Biginelli compounds. We have prepared eight THPM 5-carboxamide derivatives, four of them are new compounds. Their structures were confirmed by spectroscopic techniques and elemental analysis. These compounds have potential applications in organic synthesis and medicinal chemistry. We have synthesized a series of THPM-5-carboxamides by simple and efficient three-component Biginelli condensation reaction. Significant benefits of the present procedure include: a) application of inexpensive, non-toxic, environmentally friendly and easily available catalysts, b) the reactions are easy to carry out without high temperature and the workup is very simple, c) the required reaction times are relatively short (30-80 min with HCl and 8-24 h with PTSA.H2O), d) compatibility with various functional groups, e) the products are isolated in good to excellent yields (50-95%).
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    Magnesium Bromide and Magnesium Chloride Hexahydrate Catalyzed One-Pot Synthesis of Dihydropyrimidines via Biginelli Reaction under Solvent-Free Conditions
    (Wiley, 2013) Gulten, Sirin
    Biologically important 12 new important 3,4-dihydropyrimidin-2-(1H)-ones (-thiones) were synthesized with in one-pot three-component Biginelli reaction from the corresponding aromatic aldehydes (5-methyl-2-thiophenecarboxaldehyde and 2-chloro-5-nitrobenzaldehyde), -keto esters (ethylacetoacetate, allylacetoacetate, and t-butylacetoacetate), and urea/thiourea in the presence of catalytic amount of magnesium bromide and magnesium chloride hexahydrate as nontoxic, inexpensive, and easily available catalysts under solvent-free conditions at 80 and 100 degrees C. Compared with the catalyst-free three-component Biginelli reaction conditions, this method consistently has the advantage of short reaction time (45100 min) and good to excellent yields (7591%).
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    Nickel Chloride Hexahydrate Catalyzed Multicomponent Biginelli's Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones and Thiones
    (Wiley, 2017) Gulten, Sirin
    An efficient protocol is reported for the one-pot three-component Bignelli synthesis of a series of 3,4-dihydropyrimidine-2(1H)-ones and thiones in good yields (66-90%) from the aldehydes (4-benzyloxybenzaldehyde, 5-bromovanilin, 4-formyl-1-cyclohexene, and trans-cinnamaldehyde), -keto esters (ethyl acetoacetate, allyl acetoacetate, and t-butyl acetoacetate), and urea/thiourea in ethanol, using nickel chloride hexahydrate as a catalyst.
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    Synthesis of Fused Six-Membered Lactams to Isoxazole and Isoxazoline by Sequential Ugi Four-Component Reaction and Intramolecular Nitrile Oxide Cyclization
    (Amer Chemical Soc, 2020) Gulten, Sirin
    The advanced organic chemistry experiments describe the preparation of fused six-membered lactams to isoxazole and isoxazoline by employing Ugi four-component reaction (U-4CR) and intramolecular nitrile oxide cyclization (INOC) synthetic sequence. The experiments were carried out in 28 h (overnight for U-4CR) and 2 h (for INOC) using commercially available starting materials. The two-step reaction involves the in situ imine formation in the one-pot multicomponent reaction and in situ nitrile oxide formation in the INOC. The experiments are useful in the organic chemistry curriculum for the introduction of a onepot multicomponent reaction and 1,3-dipolar cycloaddition reactions.
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    The Synthesis and Characterization of Solvatochromic Maleimide-Fused N-Allyl- and N-Alkyl-Substituted 1,4-Dithiines and Diels-Alder Reactions with Anthracene
    (Wiley-Blackwell Publishing, Inc, 2010) Gulten, Sirin
    A simple and facile access to new solvatochromic maleimide-fused N-allyl- and N-alkyl-substituted 1,4-dithiines from the corresponding N-substituted succinamic acid derivatives in one-pot with oxidation by thionyl chloride is described. The Diels-Alder reaction of these 1,4-dithiines with anthracene has been investigated. The 1,4-dithiine derivatives react smoothly with anthracene via charge-transfer complexes to form the Diels-Alder adducts in excellent yields.
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    Two step synthesis of potential bioactive compound N-allyl-1,4-dithiine by thionyl chloride
    (Prous Science, Sa, 2007) Gulten, Sirin
    [Anstract Not Available]
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    Use of temporary tethers in the intramolecular [2+2] photocycloaddition reactions of tetrahydrophthalimide derivatives
    (Pergamon-Elsevier Science Ltd, 2007) Gulten, Sirin; Sharpe, Andrew; Baker, James R.; Booker-Milburn, Kevin I.
    The intramolecular [2+2] photocycloaddition reactions of a series of alkenols tethered to ethanolamine, L-(+)-valinol and R-(-)-2-phenylglycinol derived 3,4,5,6-tetrahydrophthalimides via a carbonate or silicon linkage have been examined. These [2+2] photocycloadditions gave the corresponding cyclobutanes in high yield with complete endo control in all cases and with diastereoselectivities as high as 8:1 with the chiral tethers. The cleavage of the temporary tethers by either desilylation or hydrolysis provided the endo diols. Cleavage of the ethanolamine linkage by reduction/hydrolysis precipitated an acid-catalysed fragmentation/ring expansion sequence to generate complex tricyclic lactones. (C) 2007 Elsevier Ltd. All rights reserved.