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    Asymmetric transfer hydrogenation of acetophenone derivatives with novel chiral phosphinite based ?6-p-cymene/ruthenium(II) catalysts
    (Elsevier Science Sa, 2011) Aydemir, Murat; Meric, Nermin; Baysal, Akin; Turgut, Yilmaz; Kayan, Cezmi; Seker, Sevil; Togrul, Mahmut
    Enantioselective reduction of prochiral ketones to optically active secondary alcohols is an important subject in synthetic organic chemistry because the resulting chiral alcohols are extremely useful, biologically active compounds. The new chiral ligands (2R)-2-[benzyl{(2-((diphenylphosphanyl)oxy)ethyl)}amino]butyldiphenylphosphinite, 1 and (2R)-2-[benzyl{(2-((dicyclohexylphosphanyl)oxy)ethyl)}amino]butyldicyclohexylphosphinite, 2 and the corresponding ruthenium(II) complexes 3 and 4 have been prepared. The structures of these complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. P-31-{H-1} NMR, DEPT, H-1-C-13 HETCOR or H-1-H-1 COSY correlation experiments were used to confirm the spectral assignments. These ruthenium(II) ephosphinite complexes have been used as catalysts for the asymmetric transfer hydrogenation of acetophenone derivatives. Under optimized conditions, aromatic ketones were reduced in good conversions and in moderate to good enantioselectivities (up to 85% ee). (C) 2011 Elsevier B. V. All rights reserved.
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    A facile synthesis of amide-based receptors under microwave conditions: investigation of their anion recognition properties by experimental and computational tools
    (Springer, 2017) Ozturk, Gulsen; Subari, Salih; Seker, Sevil; Togrul, Mahmut; Kocakay, Safak Ozhan; Ercan, Selami; Pirinccioglu, Necmettin
    Two novel amide-based receptors were synthesized under microwave irradiation. Their chemical structures were confirmed by IR, H-1 NMR, C-13 NMR, and elemental analysis. The binding properties of these amide-based receptors to various anions (H2PO4-, HSO4-, C6H5CO2-, CH3CO2-, ClO4-, F-, Cl-, and Br-) were examined by UV titration in THF at 20 degrees C. The results indicated that the receptors form 1: 1 complexes with anions and they have the strongest affinity for fluoride (F-) among the anions considered. Molecular dynamics calculations by AMBER and quantum mechanical calculations performed at the B3LYP and M062X levels of theory using the 6-31 + g(d,p) basis set provided models for the complexation mode between the receptors and anions and yielded binding energies for the complexes.
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    Öğe
    Synthesis of rigid and C2-symmetric 18-crown-6 type macrocycles bearing diamide-diester groups: enantiomeric recognition for ?-(1-naphthyl) ethylammonium perchlorate salts
    (Pergamon-Elsevier Science Ltd, 2010) Baris, Deniz; Seker, Sevil; Hosgoren, Halil; Togrul, Mahmut
    A series of rigid and chiral C-2-symmetric 18-crown-6 type macrocycles (S,S)-4, (S,S)-5, (S,S)-6 and (R,R)-2 bearing diamide-ester groups were synthesized. The binding properties of these macrocycles were examined for ot-(1-naphthypethylammonium perchlorates salts by an 1H NMR titration method. Taking into account the host employed, important differences were observed in the Ka values of (R)- and (S)-enantiomers of guests for macrocycles (S,S)-4 and (S,S)-6, Ks/KR = 3.6, and Ks/KR = 0.1 (KR/Ks = 10.3).6.,6,G= 3.19 and Delta Delta G= -5.77 kJ mol(-1), respectively. The results indicated excellent enantioselectivity of macrocyclic (S,S)-6 towards the enantiomers of alpha-(1-naphthyl)ethylammonium perchlorate salts. (C) 2010 Elsevier Ltd. All rights reserved.
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    Synthesis of rigid and C2-symmetric pyridino-15-crown-5 type macrocycles bearing diamide-diester functions: enantiomeric recognition for chiral primary organoammonium perchlorate salts
    (Pergamon-Elsevier Science Ltd, 2014) Seker, Sevil; Baris, Deniz; Arslan, Nevin; Turgut, Yilmaz; Pirinccioglu, Necmettin; Togrul, Mahmut
    Four novel C-2-symmetric macrocyclic compounds with a pyridine function and possessing amide and ester lingeages were prepared. The enantiomeric discrimination abilities of these macrocycles against alpha-phenylethylammonium and alpha-(1-naphthyl)ethylammonium perchlorate salts were measured by standard H-1 NMR titration techniques in DMSO-d(6). A binding constant ratio of 31 (Kbind(S)/Kbind(R)) for two enantiomers of alpha-(1-naphthyl)ethylammonium salt with the macrocyclic host (S,S)-4 bearing phenyl arms was observed, which corresponds to an enantiomeric discrimination of approximately 94%. Molecular dynamic calculations were performed for some of the supramolecular complexes to in order to gain insight into the mode of molecular recognition between the macrocyclic compounds and ammonium salts; these results were consistent with experimental observations, which may be relevant to those in biochemical processes occurring in organisms. (C) 2014 Elsevier Ltd. All rights reserved.