Coordination chemistry of oxovanadium(V) complexes with active Schiff bases: synthetic,spectral, and antimicrobial approach

The Schiff bases, 3-(indolin-2-one)hydrazinecarbothioamide (L¹H), 3-(indolin-2-one)hydrazinecarboxamide (L²H), 5,6-dimethyl-3-(indolin-2-one)hydrazinecarbothioamide (L³H), and 5,6-dimethyl-3-(indolin-2-one)hydrazinecarboxamide (L⁴H), have been synthesized by the condensation of ¹ H-indol-2,3-dione and 5,6-dimethyl-1H-indol-2,3-dione with the corresponding hydrazinecarbothioamide and hydrazinecarboxamide, respectively. The complexes of oxovanadium and ligands have been characterized by elemental analyses, melting points, conductance measurements, molecular weight determinations, and IR, ¹H NMR and UV spectral studies. These studies showed that the ligands coordinated to the oxovanadium in a monobasic bidentate fashion through oxygen or sulfur and the nitrogen donor system. Thus, penta-and hexacoordinated environment around the vanadium atom has been proposed. All the complexes and their parent organic moieties have been screened for their biological activity on several pathogenic fungi and bacteria and were found to possess appreciable fungicidal and bactericidal properties. The article was submitted by the authors in English.     

Structural tautomerism of 4-acylpyrazolone schiff bases and crystal structure of 5-methyl-2-phenyl-4-{1-[(pyridin-2-ylmethyl)-amino]-ethylidene}-2,4-dihydro-pyrazol-3-one

The Schiff base derivatives prepared from 4-acetyl-5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one and alkyl amines are shown to remain exclusively in the amine-one(I) tautomeric form in chloroform solutions at room temperature using a combination of ¹H, ¹³C, APT, COSY, HMQC, and HMBC NMR spectroscopic methods. The crystal structure of 5-methyl-2-phenyl-4-{1-[(pyridin-2-ylmethyl)-amino]-ethylidene}-2,4-dihydro-pyrazol-3-one showed that this 4-acylpyrazolone Schiff base stays in the amine-one(I) form in the solid state as well, and the solid state structure supports the fact that strong hydrogen bonding between amine hydrogen and the pyrazolone C₃ carbonyl oxygen helps to stabilize the amine-one(I) tautomer.     

Mass spectral fragmentation pattern of 5-methyl-4-[(phenylamino)methylene]-2,4-dihydro-3h-pyrazol-3-one and its 2-methyl and 2-phenyl derivatives

The mass spectral fragmentation patterns of 5-methyl-4-[(phenylamino)methylene]-2,4-dihydro-3H-pyrazol-3-one and its 2-methyl and 2-phenyl derivatives have been elucidated. The principal initial fragmentation route involves rupture of the exocyclic CH-NH bond. Minor routes involve loss of H, OH and C₆H₅ from the molecular ion and rupture of the pyrazolone ring.     

An anomalous acylation of an aminobenzenesulfonamide

Acylation of 2-amino-4-chlorobenzenesulfonamide by 2-acetoxyisobutyryl chloride under acidic conditions unexpectedly gave 6-chloro-3-methyl-4H-1,2,4-benzothiadiazine 1,1-dioxide and 8-ehloro-2,2,3a-trimethyl-3a,4-dihydrooxazolo[2,3-b] [1,2,4]benzothiadiazin-1-one 5,5-dioxide, the skeletons of which incorporate the carbon atom of the acetoxyl carbonyl group of the acid chloride.     

Copper(II) complex compounds with 1-phenyl-3-methyl-4-azopyrazol-5-one derivatives. The crystal and molecular structure of Cu(C17H15N4O)2 · 0.222H2O

Seven new copper(II) complexes with 1-phenyl-3-methyl-4-azopyrazol-5-one were synthesized and isolated in the crystalline state. The crystal and molecular structure of the complex Cu(C₁₇H₁₅N₄O)₂ · 0.222H₂O was studied by X-ray diffraction. The organic ligand is coordinated to copper in the anionic form in the bidentate chelating mode through the oxygen atom of the pyrazolone moiety and one nitrogen atom of the azo group. As a first approximation, the copper(II) coordination polyhedron (CP) is a tetrahedrally distorted square. The copper CP is completed to an extended tetragonal pyramid (4+1) by the Cu?N(1) contact (3.072 ?) with the pyrazole nitrogen of the neighboring molecule.     

Synthesis of 3- and 4-(β-D-ribofuranosyl)-s-triazolo[2,3-a] pyrimid-7-one,isomers of inosine containing a bridgehead nitrogen atom

The first synthesis of a purine nucleoside analog containing a bridgehead nitrogen atom is here reported. The direct glycosylation of the trimethylsilyl derivative of s-triazolo[2,3-a] pyrimid-7-one has been shown to give 3-(β-D-ribofuranosyl)-s-triazolo[2,3-a]pyrimid-7-one (V) and 4-(β-D-ribof'uranosyl)-s-lriazolo[2,3-α]pyrimid-7-one (VII). The nueleoside V may he considered a close analog of inosine in which the nitrogen N₁ and C₅ of inosine have been interchanged. Bro-minalion of the tri-O-acelyl derivative IV gave, after deblocking, 6-bromo-3-(β-D-ribofurnaosyl)-s-triazolo[2,3-a] pyrimid-7-one (IX). Structural assignments of the nucleosides were made on the basis of comparison of the ultraviolet absorption spectral characteristics with 3-methyl-s-triazolo-[2,3-a]pyrimid-7-one (XI) and 4-methyl-s-lriazolo[2,3-a Jpyrimid-7-one (XII) prepared by a standard procedure from 7-methoxy-s-triazolo(2,3-a] pyrimidine (X).     

The photochemistry of α,β-acetylenic ketones. II. Formation of furan derivatives

The photochemical reactions of α,β-acetylenic ketones have been examined. Irradiation of 1-p-substituted phenyl-2-propyn-1-ones 2–4 in primary alcohols gave 2,5-disubstituted furans 2a–4c. The formation of furans can be explained in terms of cyclization, followed by dehydration of the 1:1-adduct of acetylenic ketone and alcohol, which was formed initially by hydrogen atom abstraction from alcohol by the excited acetylenic ketone. Irradiation of 1-p-tolyl-2-propyn-1-one ( 2 ) in ethanol-d₁ yielded 2-methyl-5-p-tolylfuran ( 2b ) containing no deuterium. This result was consistent with a mechanism that involves hydrogen atom abstraction from alcohol by the carbon of triple bond rather than abstraction by carbonyl oxygen.     

Furopyridines. XVIII. Photocycloaddition of furo[2,3-c]pyridin-7(6H)-one with acrylonitrile

The photocycloaddition of furo[2,3-c]pyridin-7(6H)-one ( 1 ) and its N-mefhyl derivative ( 1-Me ) to acrylonitrile has been studied. The structures of the photoadducts isolated by colum chromatography were determined by the nuclear magnetic resonance spectroscopy and single crystal X-ray analysis. The cyclo-addition of 1 afforded an adduct 2 at the carbonyl oxygen and 8-cyano-8,9-dihydrofuro[d]azocin-7(6H)-one ( 3 ), and the addition of 1-Me the N-methyl derivative 3-Me of 3 , (9S*)-9-cyano-6-methyl-3a,7a-dihydro-3a,7a-ethanofuro[2,3-c]pyridin-7(6H)-one ( 4 ), (2S*, 2aR*, 7bR*)- ( 5 ) and (1R*, 2aS*, 7bS*)-2-cyano-3-methyl-4-oxo-1,2,2a,3,4,7b-hexahydrocyclobuta[e]furo[2,3-c]pyridine ( 6 ).     

Dihydrofuro[2,3-h]coumarin-9-one - Synthon in the Synthesis of 6-Substituted Angelicins

6-Aminocoumarin-9-one was obtained by the reduction of 6-phenylazo-4-methyldihydrofuro[2,3-h]coumarin-9-one, and its diazotization, N-acylation, and N-formylation were realized. The diazo group at position 6 was substituted by chlorine atom and azide group and was reduced to hydrazino group. The synthesized 6-substituted 4-methyldihydrofuro[2,3-h]coumarin-9-ones were converted into the corresponding angelicins by reduction of the carbonyl group of the dihydrofuran ring and subsequent dehydration of the obtained alcohol and also by acylation with the fixed enolic form of the dihydrofuranone ring.     

Synthesis and characterization of a hydrazone ligand containing antipyrine and its transition metal complexes

The coordination chemistry of N′-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)methylene)-2-hydroxybenzohydrazide with copper(II), nickel(II), cobalt(II), manganese(II), zinc(II), palladium(II), iron(III), ruthenium(III), uranyl(VI), and titanium(IV) has been studied. The ligand and its complexes was characterized by elemental and thermal analyses, magnetic moments and conductivity measurements as well as spectroscopic techniques such as infrared, mass spectra, nuclear magnetic resonance, electron spin resonance and electronic absorption spectra. The spectral data showed that the ligand is monobasic tridentate coordinated via the enolic carbonyl oxygen of the hydrazide moiety, azomethine nitrogen and pyrazolone oxygen atoms.     

Dodecanoyl isothiocyanate and N′-(2-cyanoacetyl) dodecanehydrazide as precursors for the synthesis of different heterocyclic compounds with interesting antioxidant and antitumor activity

Dodecanoyl isothiocyanate 1 was utilized for the construction of thioureido, 2-thioxo-2,3-dihydroquinazolin-4(1H)-one, benzo[d]-1,3-thiazin-4(H)-one and 3-amino quinazolin-4(3H)-one derivatives 2, 3, 4, and 5 respectively. However, N′-(2-cyanoacetyl) dodecanehydrazide 6 was also used as a key starting material for the construction of a variety of new pyrazolone, pyrazole, thiadiazole, pyridazine, chromeno[2,3-c]pyrazole, and dithiolane derivatives 7, 9, 12, 15, 18, and 20, respectively. The newly synthesized compounds were characterized by elemental analyses and spectral data (IR, ¹H NMR, and mass spectra). Some of the newly synthesized compounds bearing heterocyclic moieties were tested for antioxidant activity as reflected in their ability to inhibit oxidation in rat brain and kidney homogenates using 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) inhibition. Also, in vitro anticancer activity was examined using the standard (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) (MTT) method against a panel of two human tumor cell lines namely; hepatocellular carcinoma HepG2 and mammary gland breast cancer MCF-7. Compounds 12 and 16b exhibited the highest activities as antioxidant and antitumor agents. Meanwhile, compounds 7 and 20 showed moderate activities and the rest of the tested compounds showed weak activities.     

A study of the spectra and acidity of 4,5-dihydro-1H-benz[g]indazol-7-ol and 2,3a,4,5-tetrahydro-7-hydroxy-3a-methyl-3H-benz[g]indazol-3-one

The synthesis of 2,3a,4,5-tetrahydro-7-hydroxy-3H-benz[g]indazol-3-one is recorded for the first time. Infrared, pmr, and uv spectral analysis of this pyrazolone and of 4,5-dihydro-1H-benz[g]indazol-7-ol strongly support the presence of one tautomer in each case. Measurements of pK_a values are in agreement with the proposed tautomeric structures based upon comparisons with simpler model systems. The data are taken in aqueous solution since the compounds are soluble at 10^?5 M and the results may more closely approximate that for the structure under physiological conditions.     

Thermal and photochemical reaction of isoxazolone with indole-2,3-dione derivatives

The reaction of indole-2,3-dione derivatives with five membered heterocycle, viz isoxazolone under ther mal as well as photochemical conditions is described. While under refluxing ethanol these conditions afforded 2,3-dihydro-3-(5′-oxo-3′-phenylisoxazolidyl)indol-2-one 3 and a spiro product 2′,3′-dihydro-3,7-diphenylspiro[diisoxazolo[4,5-e:4,5-b]pyran-8,3′-indol]-2′-one 4 , the uv light induced irradiation mainly produced 4,5-dioxo-3-phenylisoxazolo[5,4-b][1]benzazepine 5 and 3-phenylisoxazolo[5,4-b]quinoline-4-carboxylic acid 6 . The products have been characterised on the basis of spectral data and elemental analyses.     

Microwave versus ultrasound assisted synthesis of some new heterocycles based on pyrazolone moiety

Different pyrazolone derivatives were prepared by microwave irradiation and ultrasound assisted methods besides the traditional ones. They were used for synthesis of some derivatives of spiropiperidine-4,4′-pyrano[2,3-c]pyrazole, dihydropyrano[2,3-c]pyrazole, pyrazole-4-carbothioamide, 4-(2-oxo-1,2-diphenylethylidene)-1H-pyrazol-5(4H)-one, azopyrazole, arylmethylenebis-1H-pyrazol-5-ol and araylidene-1H-pyrazol-5(4H)-one via reactions with different reagents applying the ultrasound method in some cases.     

1-苯基-3-甲基-4-萘乙酰基-吡唑啉酮-5 (PMNAP)缩2-氨基苯并咪唑(2-AB)席夫碱及其过渡金属配合物的合成、光谱表征与质谱鉴定

在非水溶剂中合成出一种新型席夫碱试剂(H2L): 1-苯基-3-甲基-4-萘乙酰基-吡唑啉酮-5 (PMNAP)缩2-氨基苯并咪唑(2-AB)及其过渡金属铜、铅、镍和钴配合物. 由元素分析、综合滴定和质谱数据推测出配合物的组成为ML•H2O, 通过红外光谱、紫外光谱、热重谱和核磁共振氢谱对配体和配合物进行了结构表征, 同时建立了合成体系的液相色谱分离和质谱鉴定方法, 在线得到了配体共存的三种异构体和目标配合物及其相应的质谱信息. 综合各种分析结果显示: 配体在测试条件下以酮式和烯醇式结构共存, 配位时酮式可能转化为烯醇式结构, 按去质子的方式以吡唑啉酮环羟基和H2O上的两个O原子以及亚胺基上的N原子和苯并咪唑环上的含氢N原子与中心离子成键, 配合物的配位数为4.     

Copper(II) complexes of 2-carbamoylethyl derivatives of linear diamines. Crystallographic evidence for amido oxygen binding prior to deprotonation of amide nitrogens

There has been considerable interest in the coordination chemistry of linear and macrocyclic amides⁽¹⁾. Deprotonation of the amide nitrogen is known to occur with various metal ions and the sites of coordination are generally considered to be the carbonyl oxygen prior to deprotonation and the amide nitrogen after deprotonation. However, oxygen binding has generally been inferred from indirect evidence^(2,3). We now report the results of some studies on the interaction of copper(II) with a series of 2-carbamoylethyl derivatives of linear diamines, namelyN,N′-bis(2-carbamoylethyl)ethylenediamine (1),N,N,N′,N′-tetrakis(2-carbamoylethyl)ethylenediamine (2)N,N′-bis(2-carbamoylethyl)trimethylenediamine (3) andN,N,N′,N′-tetrakis(2-carbamoylethyl)trimethylenediamine (4) which confirm carbonyl oxygen binding prior to amide deprotonation.     

Etude des composés d'addition des acides de Lewis - XXXV. Note sur les composés d'addition entre amides et,respectivement, PdCl2 et PtCl2

The adducts of dimethylformamide, diethylformamide, dimethylacetamide and diethylacetamide with PdCl₂ and PtCl₂ have been prepared and the IR. spectra of the compounds in nujol mull or in CH₂Cl · CH₂Cl solution are studied. The lowering of the carbonyl frequency (amide I) shows that the metal is linked by a dative bond to the amide oxygen atom acting as a donor; the lowering is about 33 to 59 cm^?1. The decrease of the frequency of the carbonyl group vibration, observed in these cases as for other addition compounds of Lewis acids, is due to an intramolecular electronic displacement in the direction of the amid oxygen atom.     

Reactions of Quinazoline Alkaloids and their Derivatives with Electrophilic Reagents

Nitration of deoxypeganine (DOP), deoxyvasicinone (DOV), 2,3-tetramethylene-, 2,3-pentamethylene-, and 3,4-dihydroquinazol-4-ones and their 1,2-dihydro derivatives was studied. It was shown that the reaction pathway changed depending on the presence of a carbonyl on C-4 and an N=C bond in these compounds. Only the H atom on C-6 was subject to nitration if both functional groups were present, for example DOV and its homologs. Substitution of the H atom of either the 6-position (DOP, 1,2-dihydro-DOV, and their homologs) or the 6- and 8-positions simultaneously (DOP and its homologs) was enhanced if one of these functional groups was missing depending on the substrate:nitrating agent ratio. The bromination and nitration reactions of 1,2-dihydro-DOV and its analogs in a 1:2 ratio were accompanied by oxidation of the N¹H-CH bond with formation of 6,8-dibromo- and 6,8-nitro-DOV and their homologs. The difference in the behavior of these compounds was due to the different nucleophilicity of the benzene rings in them. The reaction of 1,2-dihydro-DOV and its homologs with isocyanates and p-nitro- and p-methylbenzoic acid chlorides was studied. 6-Nitro- and 6,8-dinitro-DOP and 6,8-dibromo- and 6,8-dinitro-DOV and their homologs and 6-bromo- and 6-nitro-1,2,3,4-tetrahydro-2,3-polymethylenequinazol-4-ones and their 1-alkyl(aryl)-carbamoyl and p-nitro(methyl)-benzoyl derivatives were synthesized. The molecular structures of 1-ethyl-and 1-(o-chlorophenyl)-carbamoyl-1,2-dihydrodeoxyvasicinones and 6,8-dinitro-2,3pentamethylene-3,4-dihydroquinazol-4-one were established. UDC 547.944/945 547.856.1 Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 387-393, July-August, 2008. Original article submitted May 5, 2008.     

Synthesis of 3-amino-4-methyl-6-trifluoromethylthieno[2,3-b]pyridine-2-carboxanilide and its crystal and molecular structure

4-Methoxy-1,1,1-trifluoropent-3-en-2-one reacts with cyanothioacetamide to give 3-cyano-4-methyl-6-trifluoromethylpyridine-2(1H)-thione, which was transformed into 3-amino-4-methyl-6-trifluoromethylthieno[2,3-b]pyridine-2-carboxanilide by the reaction with chloroacetanilide. The crystal and molecular structure of the amide obtained was studied by X-ray analysis. Translated fromIzvestiya Akademii Nauk Seriya Khimicheskaya, No. 4, pp. 701–703, April, 1998.     

Five-Membered 2,3-Dioxo Heterocycles: XLVI. Reaction of 5-Aryl-4-quinoxalinyl-2,3-dihydrofuran-2,3-diones with Aldehydes and Ketones. Molecular and Crystalline Structure of 5-(3-p-Tolylquinoxalin-2-yl)-4H-1,3-dioxine- 2-spiro-2'-adamantan-4-one

Aroyl(quinoxalinyl)ketenes generated by thermolysis of 5-aryl-4-(3-arylquinoxalin-2-yl)-2,3-di-hydrofuran-2,3-diones act as dienes in [4 + 2]-cycloaddition at the carbonyl group of aldehydes and ketones to afford 2-substituted 6-aryl-5-(3-arylquinoxalin-2-yl)-4H-1,3-dioxin-4-ones. The structure of 5-(3-p-tolylquino-xalin-2-yl)-4H-1,3-dioxine-2-spiro-2'-adamantan-4-one was proved by X-ray analysis.