Synthesis and cytotoxic activity of derivatives of the <Emphasis Type="Italic">tert</Emphasis>-butyl ester of 7<Emphasis Type="Italic">Z</Emphasis>-acetylmethylene-3-methyl-3-cephem-4-carboxylic acid

The condensation of the acetylmethylene group in the tert-butyl esters of 7Z-acetylmethylene-3-methyl-3-cephem-4-carboxylic acid and 7Z-acetylmethylene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid and in 7Z-acetylmethylene-3-methylene-1,1-dioxo-3-cephem with arylmethoxyamines and O-alkylation of the tert-butyl ester of 7Z-(2-hydroxyimino)propylidene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid using substituted benzyl bromides as well as pyridylmethyl chlorides gave arylmethoxyimino and pyridylmethoxyimino derivatives of these compounds in the syn and anti isomeric forms. The Vilsmaier reagent was used to introduce the N,N-dimethylaminomethylene group at C-2 of the cephem system in the tert-butyl esters of 7Z-[2-(arylmethoxyimino)propylidene]-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid. Subsequent transformation of the N,N-dimethylaminomethylene cephems using hydroxylamine led to 3Z-[2-(anti-arylmethoxyimino)propylidene]-tert-butoxycarbonylmethyl-4-(5-methyl-4-isoxazolylsulfonyl)- azetidin-2-ones. Condensation of the acetyl group in the tert-butyl ester of 7Z-acetylmethylene- 3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid with 4-bromophenylhydrazine gave a cephem with a 2-(4-bromophenylhydrazono)propylidene group at C-7. Acylation of the tert-butyl ester of 7Z-(2-hydroxyimino)propylidene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid by 2-bromobenzoyl chloride gave a cephem with a 2-(2-bromo-benzoyloxyimino)propylidene group at C-7. Biological screening of these products towards to malignant and normal cells in vitro showed that their antitumor activity and cytotoxic selectivity towards to malignant and normal cells depend on the structure and configuration of the arylmethoxyimino and pyridylmethoxyimino groups in the 7-alkylidene substituent as well as on the presence or absence of N,N-dimethylaminomethylene and carboxyl groups, respectively, at C-2 and C-4 of the cephem system.     

Quinolone Analogs 13: Synthesis of Novel 1,1′‐(2‐Methylenepropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) and Related Compounds

The reaction of the 4‐hydroxyquinoline‐3‐carboxylate 6 with pentaerythritol tribromide gave the 1,1′‐(2‐methylenepropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 11 , whose reaction with bromine afforded the 1,1′‐(2‐bromo‐2‐bromomethylpropane‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 12 . Compound 12 was transformed into the (Z)‐1,1′‐(2‐acetoxymethylpropene‐1,3‐diyl)di(4‐quinolone‐3‐carboxylate) 13 or (E)‐1,1′‐[2‐(imidazol‐1‐ylmethyl)propene‐1,3‐diyl]di(4‐quinolone‐3‐carboxylate) 14 . Hydrolysis of the dimer (Z)‐ 13 or (E)‐ 14 with potassium hydroxide provided the (E)‐1,1′‐(2‐hydroxymethylpropene‐1,3‐diyl)di(4‐quinolone‐3‐carboxylic acid) 15 or (Z)‐1,1′‐[2‐(imidazol‐1‐ylmethyl)propene‐1,3‐diyl]di(4‐quinolone‐3‐carboxylic acid) 16 , respectively. The nuclear Overhauser effect (NOE) spectral data supported that those hydrolysis resulted in the geometrical conversion of (Z)‐ 13 into (E)‐ 15 or (E)‐ 14 into (Z)‐ 16 .     

Synthesis of 3-Substituted Dialkyl 2-Aroyl-2-ethylcyclopropane-1,1-dicarboxylates by the Reformatsky Reaction

1-Aryl-2,2-dibromobutan-1-ones react with zinc and dialkyl arylmethylene- or isobutylidenemalonates to give dialkyl 2-aroyl-3-phenyl(isopropyl)-2-ethylcyclopropane-1,1-dicarboxylates which are formed mainly as Z isomers.     

Straightforward Preparation of (2E,4Z)-2,4-Heptadien-1-ol and (2E,4Z)-2,4-Heptadienal

Abstract

A concise synthesis of (2E,4Z)-2,4-heptadien-1-ol and (2E,4Z)-2,4-heptadienal is presented. Commercially available (Z)-2-penten-1-ol was converted to ethyl-(2E,4Z)-2,4-heptadienoate by reaction with activated MnO₂ and (carboethoxymethylene)triphenylphosphorane in the presence of benzoic acid as a catalyst. Ethyl-(2E,4Z)-2,4-heptadienoate was converted to (2E,4Z)-2,4-heptadien-1-ol with LiAlH₄. The alcohol was partially oxidized to (2E,4Z)-2,4-heptadienal with MnO₂. The title compounds are male-specific, antennally active volatile compounds from the Saltcedar leaf beetle, Diorhabda elongata Brulle (Coleoptera: Chrysomelidae) and have potential use in the biological control of the invasive weed saltcedar (Tamarix spp).     

Studies on the Stereochemistry of 2-(Nitromethylidene)-Heterocycles

The ¹H-NMR spectra of 2-(nitromethylidene)pyrrolidine ( 7 ), 1-methyl-2-(nitromethylidene)imidazolidind ( 10 ) and 3-(nitromethylidene)tetrahydrothiazine ( 11 ) in CDCl₃ and (CD₃)₂SO indicate that these compounds have the intramolecularly H-bonded structures (Z)- 7 , (E)- 10 and (Z)- 11 while the N-methyl derivative 8 of 7 is (E)-configurated in both solvents. 1-Benzylamino-1-(methyltio)-2-nitroehtylene ( 13 ), an acylic model, has the H-bonded configuration (E)- 13 in CDCl₃ and in (CD₃)₂SO. 2-(Nitromethylidene)thiazolidine ( 3 ) has the (E)-configuration in CDCl₃ but exists in (CD₃)₂SO as a mixture of (Z)- and (E)-isomers with the former predominating. Both species are detected to varying proportions in a mixture of the two solvents. ¹⁵N-NMR spectroscopy of 3 ruled out unambiguously the nitronic acid structure 6 and the nitromethyleimine structure 5 . The N-methyl derivative 4 of 3 is (Z)-configurated in (CD₃)₂SO. Comparison of the olefinic proton shifts of (Z)- 3 and (Z)- 4 with those of analogues and also of 1,1-bis(methylti)-2-nitroethylene ( 12 ) shows decreased conjugation of the lone pair of electrons of the ring N-atom in (Z)- 3 and (Z)- 4 . This is also supported by ¹³C-NMR studies. Plausible explanations for the phenomenon are offered by postulating that the ring N-atoms are pyramidal in (Z)- 3 and (Z)- 4 and planar in other cases or, alternatively, that the conjugated nitroenamine system gets twisted due to steric interaction between the NO₂-group and the ring S-atom. Single-crystal X-ray studies of 3 and 8 show that the former exists in the (Z)-configuration and the latter in (E)-configuration; the ring N-atom in the former has slightly more pyramidal character than in the latter.     

Synthesis,crystal structure,and electrochemistry of [Co{(Me-sal)2dien}(N3)] and [Co{(Me-sal)2dpt}(N3)]

The structure, spectroscopic, and electrochemical properties of [Co{(Me-sal)₂dien}(N₃)] and [Co{(Me-sal)₂dpt}(N₃)], where (Me-sal)₂dien = 2,2′-[1,1′-(3-azapentane-1,5-diyldinitrilo)diethylidyne] diphenolate and (Me-sal)₂dpt = 2,2′-[1,1′-(4-azapentane-1,7-diyldinitrilo)diethylidyne] diphenolate, have been investigated. These complexes have been characterized by elemental analyses, IR, UV–Vis, and ¹H-NMR spectroscopy. The crystal structures of these complexes have been determined by X-ray diffraction. Complex 1 crystallizes in the triclinic space group P 1, with a = 7.8443(4) Å, b = 11.0660(5) Å, c = 11.6216(6) Å, α = 73.360(1)°, β = 76.965(1)°, γ = 84.436(1)° and Z = 2. Complex 2 crystallizes in the monoclinic space group P2₁/n, with a = 12.1985(13) Å, b = 10.9332(12) Å, c = 15.2808(16) Å, β = 76.965(1)° and Z = 4. The coordination geometry around cobalt(III) in both complexes is a distorted octahedron. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile indicates that the first reduction corresponding to Co^III–Co^II is electrochemically irreversible, accompanied by dissociation of the axial Co–N(N₃) bond. The second reduction step of Co(II/I) leads to decomposition of the complex. These observations are rationalized based on the structure-function relations.     

Synthesis and cytotoxic activity of derivatives of 6<Emphasis Type="Italic">Z</Emphasis>-acetylmethylenepenicillanic acid <Emphasis Type="Italic">tert</Emphasis>-butyl ester

The sulfoxide of 6Z-[2-(methoxyimino)propylidene]penicillanic acid tert-butyl ester and the sulfones of 6Z-[2-(hydroxyimino-, methoxyimino-, benzyloxyimino-, 2-bromo- and 4-bromobenzyloxyimino)-propylidene]penicillanic acid in the syn and anti forms have been synthesized by the condensation of the sulfoxide and sulfone of 6Z-acetylmethylenepenicillanic acid tert-butyl ester with hydroxylamine, methoxyamine, benzyloxyamine, 2-bromo- and 4-bromobenzyloxyamines. The syn and anti isomers of 3Z-(2-methoxyiminopropylidene)-4R-(benzothiazolyl-2-dithio)-2-oxoazetidinyl-1R-(2-propenyl)acetic acid tert-butyl ester were obtained by opening of the thiazolidine ring in 6Z-[2-(methoxy-imino)propylidene]-1-oxopenicillanic acid tert-butyl ester with 2-mercaptobenzothiazole. The 3Z-(2-methoxyiminopropylidene)-4R-(methylsulfonyl)-2-oxoazetidinyl-1-(2-propylidene)acetic acid tert-butyl ester was synthesized by the interaction of 1,8-diazobicyclo[5.4.0]undec-7-ene and methyl iodide with 6Z-[2-(methoxyimino)propylidene]-1,1-dioxopenicillanic acid tert-butyl ester. A dependence of the cytotoxic effect in relation to cancer and normal cells in vitro on the structure of the substituent in position 6 and the syn and anti isomerism of the oxyimino group was established for the synthesized compounds.     

Stereo- and Enantioselective Synthesis of Propionate-Derived Trisubstituted Alkene Motifs

We report a new method for constructing propionate-derived trisubstituted alkene motifs in a stereoselective manner. 1-Substituted 1,1-di(pinacolatoboryl)-(E)-alk-2-enes are generated in situ from 1-substituted 1,1-di(pinacolatoboryl)alk-3-enes through ruthenium(II)-catalyzed double-bond transposition. These species undergo a chiral phosphoric acid catalyzed allylation reaction of aldehydes to produce the E isomers of anti-homoallylic alcohols. On the other hand, the corresponding Z isomers of anti-homoallylic alcohols are obtained when a dimeric palladium(I) complex is employed as the catalyst for this double-bond transposition. Thus, both E and Z isomers can be synthesized from the same starting materials. A B−C(sp²) bond remaining with the allylation product undergoes the Suzuki–Miyaura cross-coupling reaction to furnish a propionate-derived trisubstituted alkene motif in a stereo-defined form. The present method to construct the motifs with (E)- and (Z)-alkenes are successfully applied to the syntheses of (+)-isotrichostatic acid, (−)-isotrichostatin RK, and (+)-trichostatic acid, respectively.     

Synthesis and Properties of Copper,Mercury, and Silver (2-Naphthyl)acetylenides

(Z)-2-Naphthylacetylene was synthesized by the reaction of (Z)-3-(2-naphthyl)-3-chloropropenal (prepared from 2-acetylnaphthalene) with aqueous NaOH in dioxane. The reactions of 2-naphthylacetylene with CuCl, [Ag(NH₃)₂]NO₃, and K₂[HgI₄] gave copper, silver, and mercury 2-naphthylacetylenides, respectively. Silver naphthylacetylenide reacts with iodine to give the iodoethynyl derivative, which readily takes up bromine across the triple bond.     

Stereoselective Double Friedel-Crafts Acylation of trans-μ-(2,3,6,7-Tetramethylidenebicyclo[3.2.1]octane)bis(tricarbonyliron). Crystal Structure of trans-μ-{(1RS,2RS,3SR,5RS,6SR,7SR)-C,2,3,C-η:C,6,7,C-η-[(Z,Z)-1,1′-(3,7-Dimethylidenebicyclo[3.2.1]octane-2,6-diylidene)di(2-propanone)]}bis(tricarbonyliron)

The Friedel-Crafts mono and double acylations of trans-μ-[(1RS,2RS,3SR,5RS,6SR,7SR)-C,2,3,C-η:C,6,7,C-η-(2,3,6,7-tetramethylidenebicyclo[3.2.1]octane)]bis(tricarbonyliron) ( 4 ) are highly stereoselective and yield trans-μ-{(1RS,2RS,3SR,5RS,6SR,7RS)-C,2,3,C-η :C,6,7,C-η-[(Z)-1-(3,6,7-trimethylidenebicyclo[3.2.1]-oct-2-ylidene)-2-propanone]}bis(tricarbonyliron) ( 5 ) and trans-μ-{(1RS,2RS,3SR,5RS,6SR,7SR)-C,2,3,C-η :C,6,7,C-η-[(Z,Z)-1,1′-(3,7-dimethylidenebicyclo [3.2.1] octane-2,6-diylidene)di(2-propanone)]}bis(tricarbonyliron) ( 6 ) whose structure has been established by single-crystal X-ray diffraction.     

Uncommon Heterocyclization into a Pyrazole System of <Emphasis Type="Italic">Z</Emphasis>-3-(2-Naphthyl)-3-chloro-2-propenal Semicarbazone and Thiosemicarbazone

By reaction of Z-3-(2-naphthyl)-3-chloro-2-propenal with semicarbazide hydrochloride and thiosemicarbazide the corresponding semicarbazone and thiosemicarbazone were obtained that underwent a heterocyclization into a pyrazole system with elimination of amide moieties and with migration of the naphthyl fragment into the position 4 of the pyrazole ring. The alkylation of 4-(2-naphthyl)pyrazole synthesized with 2-nitropentachloro-1,3-butadiene afforded 1,1-bis[4-(2-naphthyl)-pyrazol-1-yl]-2-nitrotrichloro-1,3-butadiene.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 753–755.Original Russian Text Copyright © 2005 by Vashkevich, Potkin, Kozlov.     

Synthesis of 2,N,N‐Trisubstituted 1H‐Indole‐1‐carbothioamides from 2‐(Acylmethyl)phenyl Isocyanides

A convenient procedure for the synthesis of 2,N,N‐trisubstituted 1H‐indole‐1‐carbothioamides from 2‐(acylmethyl)phenyl isocyanides has been developed. Thus, these isocyanides are converted into (Z)‐ [1‐alkyl (or phenyl)‐2‐(2‐isothiocyanatophenyl)ethenyl] 1,1‐dimethylethyl carbonates via an easy two‐step sequence. Treatment with secondary amines gave thiourea intermediates which afforded with CF₃COOH (TFA) the desired products in fair‐to‐good yields.     

Synthesis,Structure, and Biological Activity of (2Z)-2-[(2,4-Dinitrophenyl)hydrazinylidene]butanedioic Acid Esters

Dialkyl (2Z)-2-[(2,4-dinitrophenyl)hydrazinylidene]butanedioates have been synthesized by reaction of dialkyl (2Z)-2-hydroxybut-2-enedioates with 2,4-dinitrophenylhydrazine, and their structure has been studied by IR and ¹H NMR spectroscopy, mass spectrometry, and X-ray analysis.

     

A new bis(azine) tetradentate ligand and its transition metal complexes: Synthesis,characterisation, and extraction properties

A new bis(bidentate) azine ligand was prepared by linking (1Z,1′Z)-1,1′-{butane-1,4-diylbis[oxybenzene-4,1-diyl(1Z)ethyl-1-ylidene]}dihydrazine to salicylaldehyde. Two kinds of binuclear copper(II) and nickel(II) complexes with different stoichiometries were prepared. Reaction of bis(azine) ligand with Cu(II) and Ni(II) acetate at a 1: 1 mole ratio gave double-stranded binuclear bis(azine) complexes with stoichiometry [M(L)(H₂O)₂]₂ containing [M(II)N₂O₂] centres while at a 2: 1 mole ratio, reaction of Cu(II) and Ni(II) chloride with bis(azine) resulted in dinuclear metal complexes with the general stoichiometry [M₂(L)Cl₂(H₂O)₂]. Structures of the bis(azine) ligand and its complexes were identified by elemental analysis, IR and UV-VIS spectra, magnetic susceptibility measurements, TGA, and powder XRD. Extraction properties of the bis(azine) ligand towards some transition metal cations and dichromate anions were also reported. It was found that the bis(azine) ligand does not extract cations but it has high extraction ability towards dichromate anions.     

Five-membered 2,3-dioxo heterocycles: LVII. Recyclization of 3-pivaloylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones by the action of o-phenylenediamine. Crystalline and molecular structure of 3-[3,3-dimethyl-2-oxo-1-(3-oxo-3,4-dihydroquinoxalin-2-yl)butyl]-1-phenylquinoxalin-2(1H)-one

3-[(Z)-3,3-Dimethyl-2-oxobutylidene]-3,4-dihydroquinoxalin-2(1H)-one and its 1-phenyl-substituted analog reacted with oxalyl chloride to give the corresponding 3-pivaloylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones. Reactions of the latter with o-phenylenediamine led to the formation of 3,3′-(3,3-dimethyl-2-oxobutane-1,1-diyl)di[quinoxalin-2(1H)-ones]. Original Russian Text ? K.S. Bozdyreva, Z.G. Aliev, A.N. Maslivets. 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 4, pp. 612–616. For communication LVI, see [1].     

Enantioselective Synthesis of (E)-δ-Boryl-Substituted anti-Homoallylic Alcohols Using Palladium and a Chiral Phosphoric Acid

(E)-δ-Boryl-substituted anti-homoallylic alcohols are synthesized in a highly diastereo- and enantioselective manner from 1,1-di(boryl)alk-3-enes and aldehydes. Mechanistically, the reaction consists of 1) palladium-catalyzed double-bond transposition of the 1,1-di(boryl)alk-3-enes to 1,1-di(boryl)alk-2-enes, 2) chiral phosphoric acid catalyzed allylation of aldehydes, and 3) palladium-catalyzed geometrical isomerization from the Z to E isomer. As a result, the configurations of two chiral centers and one double bond are all controlled with high selectivity in a single reaction vessel.     

Eine Synthese methylierter Epoxyhydroazulenone durch intramolekulare [4 + 3]-Cycloaddition einer aus 1,1-Dichloro-6-(3-methylfur-2-yl)hexan-2-on erzeugten Oxyallyl-Zwischenstufe

A synthesis of Methylated Epoxyhydroazulenones by Intramolecular [4 + 3] Cycloaddition of an Oxyallyl Intermediate, Generated from 1,1-Dichloro-6-(3-methyl-2-furyl)hexan-2-one (Z)-3-Methylpent-2-en-4-yn-1-ol ( 7 ) was transformed to 2-(4-chlorobutyl)-3-methylfuran ( 4b ) and 2-(but-3-enyl)-3-methylfuran ( 10a ) by C-alkylation and 5-exo-dig cyclization. The Grignard derivative formed from 4b gave 1,1-dichloro-6-(3-methylfur-2-yl)hexan-2-onc ( 1b ) on reaction with dichloroacetyl chloride. This dichloromethyl ketone undergoes a base-induced cyclization to form diastereoisomeric 7-chloro-1,2,3,6,7,8a-hexahydro-4-methyl-8H-3a,6-epoxyazulen-8-ones ( 3bα and 3bβ ) by way of an intramolecular [4+3] cycloaddition of an oxyallyl intermediate 2b. By dechlorination and hydrogenation of 3bβ , the tricyclic hydroepoxyazulenones 18 and 19 have been synthesized.     

Azimine. V.. Untersuchungen zur stereoisomerie an der N(2), N(3)-bindung von 2, 3-dialkyl-1-phthalimido-aziminen

Azimines. V. Investigation on the Stereoisomerism Around the N (2), N (3) Bond in 2, 3-Dialkyl-1-phthalimido-azimines 2, 3-(cis-1, 3-Cyclopentylene)-1-phthalimido-azimine ( 7 ) and isomerically pure (2 Z)- and (2 E)-2, 3-diisopropyl-1-phthalimido-azimine ( 9a and 9b ) were prepared by the addition of phthalimido-nitrene ( 1 ) to 2, 3-diazabicyclo [2.2.1]hept-2-ene ( 6 ) and to (E)- and (Z)-1, 1′-dimethylazoethane ( 8a and 8b ), respectively. Comparison of their UV. spectra with those of two stereoisomeric azimines of known configuration, namely (1 E, 2 Z)- and (1 Z, 2 E)-2, 3-dimethyl-1-phthalimido-azimine ( 5a and 5b ), reveals that 2, 3-dialkyl-1-phthalimido-azimines with (2 Z)-configuration are characterized by a shoulder at about 258 nm (? ≈? 14,000) and those with (2 E)-configuration by a maximum at 270–278 nm (? ≈? 10,000). The (2 E)-azimine 9b isomerizes under acid catalysis as well as thermally and photochemically into the more stable (2 Z)-isomer 9a . Under the last two conditions the isomerization is accompanied by a slower fragmentation with loss of nitrogen into N, N′-diisopropyl-N, N′-phthaloylhydrazine ( 4 , R = iso-C₃H₇). The same fragmentation was also observed on thermolysis and photolysis of the (2 Z)-isomer 9a . The kinetic parameters for the thermal isomerization of 9b (they fit first-order plots) and for the fragmentation of 9a and 9b were determined by ¹H-NMR. spectroscopy in benzene, trichloromethane and acetonitrile. In the photolysis of 9a or 9b the fragmentation is accompanied by dissociation into the azo compounds 8a or 8b and the nitrene 1 , the latter being subject to trapping by cyclohexene. With the azimine 7 , an analogous thermal fragmentation was observed to give N, N′-(cis-1, 3-cyclo-pentylene)-N, N′-phthaloylhydrazine ( 15 ), but more energetic conditions were required than with 9 . Photolysis of 7 led exclusively to dissociation into the azo compound 6 and the nitrene 1 , perhaps because the fragmentation of 7 is prevented by ring strain.     

Preparation of silyl-protected γ-hydroxylated α,β-unsaturated acetylenic ketones and their reactions with some nucleophiles

A number of 5-siloxylated 1,1-diethoxy-3-alkyn-2-ones were prepared from the corresponding ketals. The t-butyldiphenylsiloxy derivatives were stable, whereas the trimethylsilyl analogs were unstable. The former compounds were reacted with diethylamine, lithium dimethylcuprate, and 1,3-propanedithiol and gave Michael adducts in good to very good yields. The amine and cuprate gave the conjugated alkenones, the former in a stereospecific manner (Z), the latter stereospecifically (E) in one case but otherwise stereoselectively with an E preponderance. With the dithiol bisaddition occurred, and the corresponding 1,3-dithiane was obtained in excellent yield. Attempts to make 1,3-dithianes from 1,3-propanedithiol and 1,1-diethoxy-4-diethylaminoalk-3-en-2-ones failed.     

Synthesis of a functionalized tetrahydro-1,4-thiazepine in water as the solvent and theoretical investigation of its tautomeric structures

Reaction of sodium 2,2-dicyanoethene-1,1-bis(thiolate) with 2-chloroethylamine hydrochloride in water afforded the novel (Z)-5-amino-7-thioxo-2,3,4,7-tetrahydro-1,4-thiazepine-6-carbonitrile. The molecular geometry of the most stable tautomeric structure was investigated with DFT and AIM at the B3LYP level of theory using the standard 6-31G** basis set. Correspondence: Mehdi Bakavoli, Department of Chemistry, School of Science, Ferdowsi University, 91775-1436 Mashhad, Iran.