Engin Kendi

Synthesis and hypnotic activity of new 4-thiazolidinone and 2-thioxo-4,5-imidazolidinedione derivatives.

Conveniently accessible 4‐[(2‐(3,4‐dimethoxyphenyl)ethyl]‐3‐thiosemicarbazide (2) was converted to new 1‐substituted benzylidene/furfurylidene‐4‐[2‐(3,4‐dimethoxyphenyl)ethyl]‐3‐thiosemicarbazides (3) which furnished 2‐(substituted benzylidene/furfurylidene)hydrazono‐3‐[2‐(3,4‐dimethoxyphenyl)ethyl]thiaz‐olidin‐4‐ones (4) and 1‐(substituted benzylidene/furfurylidene)‐amino‐3‐[2‐(3,4‐dimethoxyphenyl)ethyl]‐2‐thioxo‐4,5‐imidazol‐idinediones (5) on reaction with chloroacetic acid and oxalyl chloride, respectively. The structure of 5 was confirmed by X‐ray diffraction studies performed on 5a. 4 and 5 were evaluated for their potentiating effects on pentobarbital induced hypnosis. Most of the compounds caused remarkable increases in pentobarbital sleeping time.

New pyrazoline bearing 4(3H)-quinazolinone inhibitors of monoamine oxidase : Synthesis, biological evaluation, and structural determinants of MAO-A and MAO-B selectivity

A new series of pyrazoline derivatives were prepared starting from a quinazolinone ring and evaluated for antidepressant, anxiogenic and MAO-A and -B inhibitory activities by in vivo and in vitro tests, respectively. Most of the synthesized compounds showed high activity against both the MAO-A (compounds 4a-4h, 4j-4n, and 5g-5l) and the MAO-B (compounds 4i and 5a-5f) isoforms. However, none of the novel compounds showed antidepressant activity except for 4b. The reason for such biological properties was investigated by computational methods using recently published crystallographic models of MAO-A and MAO-B. The differences in the intermolecular hydrophobic and H-bonding of ligands to the active site of each MAO isoform were correlated to their biological data. Compounds 4i, 4k, 5e, 5i, and 5l were chosen for their ability to reversibly inhibit MAO-B and MAO-A and the availability of experimental inhibition data. Observation of the docked positions of these ligands revealed interactions with many residues previously reported to have an effect on the inhibition of the enzyme. Among the pyrazoline derivatives, it appears that the binding interactions for this class of compounds are mostly hydrophobic. All have potential edge-to-face hydrophobic interactions with F343, as well as pi-pi stacking with Y398 and other hydrophobic interactions with L171. Strong hydrophobic and H-bonding interactions in the MAO recognition of 4i could be the reason why this compound shows selectivity toward the MAO-B isoform. The very high MAO-B selectivity for 4i can be also explained in terms of the distance between the FAD and the compound, which was greater in the complex of MAO-A-4i as compared to the corresponding MAO-B complex.

Synthesis of some 1-(2-naphthyl)-2-(imidazole-1-yl)ethanone oxime and oxime ether derivatives and their anticonvulsant and antimicrobial activities.

In this study, oxime and oxime ether derivatives of anticonvulsant nafimidone [1-(2-naphthyl)-2-(imidozole-1-yl)ethanone] were prepared as potential anticonvulsant compounds. Nafimidone oxime was synthesized by the reaction of nafimidone and hydroxylamine hydrochloride. O-Alkylation of the oxime by various alkyl halides gave the oxime ether derivatives. Anticonvulsant activity of the compounds was determined by maximal electroshock (MES) and subcutaneous metrazole (scMet) tests in mice and rats according to procedures of the Antiepileptic Drug Development (ADD) program of the National Institutes of Health (NIH). In addition to anticonvulsant evaluation, compounds were also screened for possible antibacterial and antifungal activities because of the structural resemblance to the azole antifungals, especially to oxiconazole. All compounds were evaluated against three human pathogenic fungi and four bacteria using the microdilution method. Most of the compounds exhibited both anticonvulsant and antimicrobial activities; the O-alkyl substituted compounds (2, 3, 4 and 5) were found to be more active than the O-arylalkyl substituted compounds in both screening paradigms.

Intramolecular hydrogen bonding and tautomerism in N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine

N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine (C16H12N2O) was studied by elemental analysis, IR, 1H NMR, and UV–visible techniques and X-ray diffraction methods. The UV–visible spectrum of the compound was investigated in solutions effect polarity. The polarity of the some solvents was modifierly the additional (CF3COOH) and [(C2H5)3N]. The compound is in tautomeric equilibrium (phenol-imine O–H···N and keto-amine O···H–N forms) in polar and nonpolar solvents. The keto-amine form is observed in basic solutions of DMSO, ethanol, chloroform, benzene, cyclohexane, and in acidic solutions of chloroform and benzene, but not in acidic solutions of DMSO and ethanol. The compound crystallizes in the monoclinic, space group P21/a with a = 7.010(5) Å, b = 13.669(4) Å, c = 12.764(4) Å, β = 101.23(4)°, V = 1199.6(10) Å3, Z = 4, Dc = 1.375 g/cm3, μ(Mo Kα) = 0.088 mm−1, R = 0.045 for 1658 reflections [I > 2σ(I)]. The title compound is not planar two Schiff base moieties A [C1–C11, O1] and B [N1, C12, C13, N2, C14, C15, C16] are inclined at an angle of 27.4(1)° reflecting mainly the twist about C12–N1 [C11–C12–N1–C13, 29.7(2)°]. There is a strong intramolecular hydrogen bond (O–H···N) of 2.529(2) Å.

THE CRYSTAL AND MOLECULAR STRUCTURE OF TWO BENZIMIDAZOLE DERIVATIVES : 1-(PHENYLMETHYL)-2-(4-METHOXYPHENYLMETHYL)-1H-BENZIMIDAZOLE-5-CARBOXYLIC ACID ( I) AND 1,2-DI-(PHENYLMETHYL)-1H-BENZIMIDAZOLE-5-CARBOXYLIC ACID (II)

Abstract The crystal structures of C23H20N2O3 (I) and C22H18N2O2 (II) have been determined by single-crystal X-ray diffraction. These two compounds crystallise in the monoclinic space groups, P 2 1 c and C 2 c . The structures have been determined by direct methods and refined to R, 0.041 (I) and 0.070 (II). The benzimidazole ring systems in (I) and (II) are planar. The phenyl rings attached to N1 and C2 in (I) are planar and make dihedral angles of 88.5(1) and 103.8(1)° with the benzimidazole ring systems. Corresponding angles in (II) are 95.0(2) and 105.1(2)°.

Structure and Conformation of 4,4′-Bipyridine

Abstract The title compound has been investigated by x-ray analysis and AM1 semi-empirical quantum mechanical method. The geometry of the two molecules in the asymmetric unit is different in terms of the torsion angle θ [C4-C5-C6-C10] between the two pryidne rings which is -34.1 (2)° and -17.9 (2)° in molecule I and II respectively. The conformation of the energy profile showed that the minimum energy conformation has the torsion angle θ near 35°. The crystal structure is stabilized by C-H … N hydrogen bonds.

The structure of 1-(p-fluorophenylmethyl)-2-(4-methyl-1-piperazinyl)-1H-benzimidazole hydrogen fumarate

The crystal and molecular structure of the title compound has been determined by X-ray analysis. The 1-(p-fluorophenylmethyl)-2-(4-methyl-1-piperazinyl)-1H-benzimidazole ion cocrystallizes with fumaric acid, (C19H22N4F+·C4H3O4−), in space group P-1 with cell dimensions a = 9.938(1), b = 10.131(1), c = 12.712(1) Å, α = 86.57(1), β = 69.41(2), and γ = 67.22(2)°. The piperazine N4 atom is protonated and contacts the deprotonated O atom of the fumarate anion through a hydrogen bond. The benzimidazole ring is nearly planar and makes a dihedral angle of 111.25(12)° with the fluorophenyl ring. The piperazine ring adopts a chair conformation.

The structure of N-(1H-benzo[d]imidazol-2-ylmethyl)-N-(2,6-dichlorophenyl)amine

The N-(1H-benzo[d]imidazol-2-ylmethyl)-N-(2,6-dichlorophenyl)amine, C14H11N3Cl2, Mr = 292.17, crystallizes in the orthorhombic space group Pbca with unit cell parameters a = 10.707(2), b = 9.615(2), c = 25.944(6) Å. The benzimidazole ring system is planar and makes a dihedral angle of 77.8(1)° with the phenyl ring. The structure is stabilized by an N–H···N hydrogen bond.

6-Benzylidene-2-(2-chlorophenyl)thiazolo[3,2-b]-1,2,4-triazol-5(6H)-one

In the title compound, C 17 H 10 ClN 3 OS, the fused thiazolo[3,2-b]-1,2,4-triazole system is almost planar. The phenyl substituents are planar within experimental error and make dihedral angles of 16.5 (1) and 10.9(1)° with the thiazolo-triazole system. There are three intramolecular hydrogen-bond interactions of types C-H...N, C-H...O and C-H...S.

Crystal Structure of N,N'-Bis(dodecyl)diaza- 18-crown-6 Complexed Sodium Perchlorate

The crystal structure of a new complex of a diaza-crown ether having two side arms has been determined from X-ray diffraction data. The compound crystallizes in space group P1 with cell dimensions a = 9.982(1), b = 10.685(1), c = 20.376(2)Å, α = 81.09(1), β = 80.92(1), γ = 88.43(1)0, Z = 2. The structure has been solved by direct methods and refined to the final R value of 0.053 for 3458 observed reflections and 424 parameters. The diaza-18-crown-6 ligand adopts an approximate D3d conformation. The Na+ ion is held inside the molecular cavity of this macroring ligand and a ClO-4 oxygen coordinates with Na+. The average Na–-O (18-crown-6) and Na–-N bond lengths are 2.426(4) and 2.786(5)Å, respectively; the Na–-O (ClO-4) bond length is 2.472(4)Å. The mean cavity radius is 1.10 Å and the N⋅N nonbonding distance is 4.605(6)Å.