Ertan Sahin

Diastereoselective control through hydrogen bonding in the aziridination of the chiral allylic alcohols by acetoxyaminoquinazolinone.

A high diastereoselectivity (up to >99:1) is found for the aziridinations of chiral allylic alcohols with acetoxyaminoquinazolinone (Q-NHOAc). The selectivity is explained in terms of hydrogen bonding between the hydroxy functionality of the allylic alcohol and the remote carbonyl group of the quinazolinone.

The Design and Cytotoxic Evaluation of Some 1-Aryl-3-isopropylamino-1-propanone Hydrochlorides towards Human Huh-7 Hepatoma Cells

A series of 1‐aryl‐3‐isopropylamino‐1‐propanone hydrochlorides 1 and a related heterocyclic analog 2 as candidate antineoplastic agents were prepared and the rationale for designing these compounds is presented. A specific objective in this study is the discovery of novel compounds possessing growth‐inhibiting properties of hepatoma cells. The compounds in series 1 and 2 were prepared and their structures established unequivocally. X‐ray crystallography of two representative compounds 1d and 1g were achieved. Over half of the compounds are more potent than 5‐fluorouracil which is an established drug used in treating liver cancers. QSAR evaluations and molecular modeling studies were undertaken with a view to detecting some physicochemical parameters which govern cytotoxic potencies. A number of guidelines for amplification of the project have been formulated.

Synthesis and paroxonase activities of novel bromophenols

Three novel bromophenols 10–12 were synthesized. Acylation of veratrole (4) with 2,3-dimethoxy benzoic acid (5) gave a kown diarylmethanone 6. Bromination of 6 with different equivalents of molecular bromine afforded new di and tribrominated compounds 7–9 which were converted to their corresponding bromophenols 10–12 via O-demethylation with BBr3. Paraoxonase-1 (PON1) was purified from human serum with approximately 42% and 3584 U × mg−1 specific activity. The synthesized compounds 6–12 showed inhibitory effects on paraoxonase-1 (PON1) which is an organophosphate (OP) hydrolyser and an antioxidant bioscavenger enzyme. IC50 values were determined in the range of 0.123–1.212 mM. Graphical abstract

Enantioselective synthesis of cyclic, quaternary oxonitriles.

Quaternary oxonitriles are stereoselectively generated from the union of five-, six-, and seven-membered 2-chloroalkenecarbonitriles with chiral alcohols via a Claisen rearrangement. The strategy rests on a new conjugate addition-elimination of allylic alkoxides to 2-chlorocycloalkenecarbonitriles to afford substituted 2-alkoxyalkenenitriles. Subsequent thermolysis unmasks a cyclic oxonitrile while selectively forming a new quaternary center with enantiomeric ratios typically greater than 9:1. The overall alkylation strategy addresses the challenge of enantioselectively generating hindered, quaternary centers while simultaneously installing ketone, nitrile, and olefin functionalities.

Polyfluorinated Pd(II)-3,5-di-tert-butylsalicylaldimenes complexes: synthesis, structure, spectroscopy, redox behaviors and catalytic activity.

A series of new polyfluorinated palladium(II) complexes (7-12) of N-polyfluorophenyl-3,5-di-tert-butylsalicylaldimines (1-6) have been synthesized. They were characterized by analytical, spectroscopic (UV/Vis, IR, (1)H NMR, and ESR), electrochemical methods and their chemical oxidation and hydrogenation catalytic activity were studied. The X-ray crystal structure analysis of bis[N-(3,5-di-tert-butylsalicylidene)-F5Ph]Pd(II) (12) revealed a slightly distorted square-planar trans-PdN2O2 geometry around the palladium center. The UV/Vis and EPR results indicate that chemical oxidation of 7-10 by Ce(IV) in CHCl3 generates relatively stable Pd(II)-phenoxyl radical complexes (g=2.0044-2.0062). The results of chemical and electrochemical oxidation of 1-12, as well as the catalytic activity of 7-10 complexes in the hydrogenation of PhNO2 were presented.

Synthesis, antimicrobial activity and acid dissociation constants of methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives

In this study, a series of polysubstituted methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives were designed and synthesized by the cyclization reaction of methyl 1-(benzoylcarbamothioyl)-5,5-diphenylpyrrolidine-2-carboxylates and 2-bromo-1-(4-substituted phenyl)ethanones in 70-96% yield. The starting pyrrolidine derivatives were synthesized via a 1,3-dipolar cycloaddition reaction in 83-88% yield. The stereochemistry of one of these methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives was characterized by a single crystal X-ray diffraction study and the acid dissociation constants of these compounds were determined. An antimicrobial screening was performed against different bacterial and fungal strains and against the M. tuberculosis H37Rv strain. Interesting antibacterial activity was observed for two compounds against the A. baumannii strain with MIC values of 31.25 µg/mL (Ampicillin: 125 µg/mL) and against the M. tuberculosis H37Rv strain with MIC values of 0.98-1.96 µg/mL (Isoniazid: 0.98 µg/mL, Ethambutol: 1.96 µg/mL). Therefore, these structures can be considered as good starting points for the development of new powerful antimycobacterial agents.

Copper(II) 2-Benzoylbenzoate Complexes Containing 2-Pyridilmethanol and 2-Pyridilethanol: Synthesis, Crystal Structures, Spectroscopic, and Thermal Properties

Two new copper(II) complexes, [Cu(bba)2(pymet)2] 1 and [Cu(bba)2(pyet)2] 2, have been synthesized and characterized by elemental analysis, thermal analysis, UV-Vis, and IR spectroscopic techniques. Single-crystal X-ray analysis of 1 and 2 revealed that the geometries are octahedral. 1 crystallizes in the monoclinic crystal system with space group P21/n, while 2 crystallizes in the triclinic crystal system with the space group P-1. 2-benzoylbenzoic acid ligand behaves as a monodentate, while 2-pyridilmethanol and 2-pyridilethanol ligands act as a bidentate in two complexes. Thermal analysis show that two decomposition stages of the investigated complex 1 and 2, stable up to ∼160°C.

Synthesis and X-ray crystal structures of three new terpyridine-based Pb(II) complexes, cytotoxicity studies of {[Pb(ttpy)(μ-AcO)]2}(SCN)2

Synthesis and X-ray crystal structures of three new terpyridine-based Pb(II) complexes, {[Pb(ttpy)(μ-AcO)]2}(SCN)2 (1) (ttpy = 4′-tolyl-2,2′:6′,2″-terpyridine), [Pb(Clphtpy)(AcO)(ClO4)] (2), and [Pb(Clphtpy)(SCN)2] (3) (Clphtpy = 4′-(4-chlorophenyl)-2,2′:6′,2″-terpyridine), are described. The synthesized materials have been characterized, also, by CHN elemental analysis, 1H NMR, and IR spectroscopy. The structural analyses showed that, in the solid state, the coordination number of Pb(II) in 1, 2, and 3 are six, seven, and five, respectively. In the complexes, the lone-pair electrons of Pb(II) are stereochemically active and the coordination geometry of Pb(II) is hemidirected. The structures of the three complexes were compared and the effect of counter ion is described. The antibacterial activity of 1 and previously reported {[Pb(ttpy)(μ-AcO)]2}(PF6)2 (1A) and {[Pb(ttpy)(μ-AcO)I]2} (1B) were tested by minimum inhibitory concentration method to investigate the effect of counter ions on biological activity of the compounds. Also, cytotoxicity test was assessed using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay to determine the maximum non-toxic concentration of ttpy, Pb(II), and their complexes to HepG2 cells. Effective lead detoxification was observed for 1, 1A, and 1B. Graphical Abstract

Spectroscopic and structural studies of 6,6′-bis(N-methylhydrazine)-2,2′-bipyridine and its mononuclear copper(II) complex

The tetradentate ligand, 6,6′-bis(N-methylhydrazine)-2,2′-bipyridine (L) and its mononuclear copper(II) complex [Cu(L)](ClO4)2] (1) have been synthesized and characterized. The crystal structures of L and 1 have been determined by single-crystal X-ray diffraction. Both crystallize in the centrosymmetric monoclinic space group with crystallographic inversion symmetry. The ligand adopts a planar transoid configuration in the solid state. In 1, the Cu(II) is six-coordinate octahedral, defined by N4O2 donors from ligand and two perchlorates. The molecular units are connected by intermolecular H-bonds between the hydrazino group of the one unit and coordinated perchlorate of the neighboring two units via N–H ··· O to furnish a 2-D network. Coordinated perchlorates also form an intramolecular H-bond with hydrazine influencing the crystal packing.

Synthesis of the 3,5-diphenyl-1H-pyrazole and cytogenetic and oxidative alterations after exposure of cultured human whole blood cells

Abstract The 3,5-diphenyl-1H-pyrazole was obtained by condensation reaction of dibenzoylmethane and thiosemicarbazide in acetic acid under conventional heating and microwave irradiation method. The structure of the 3,5-diphenyl-1H-pyrazole confirmed by IR, 1H, and 13C NMR and X-ray diffraction and the geometry optimization was carried out using density functional theory (DFT) methods at B3LYP/6-31G, 6-31G(d), 6-31G(d, p), 6-311G(d, p), 6-311G(2d, 2p), 6-31+G(d, p), 6-311++G(d, p) levels. In addition, cytotoxic and oxidative effects were investigated in cultured human peripheral blood cells.