Design,Synthesis, and Antimicrobial Evaluation of some Novel Pyridine,Coumarin, and Thiazole Derivatives

Treatment of 2‐cyano‐N′‐(1‐(pyridin‐2‐yl)ethylidene)acetohydrazide 1 with aromatic/heterocyclic aldehydes 2a–f gave arylidene derivatives 3a–f . Polysubstituted pyridine derivatives 4a,b were prepared either from reaction of arylidene 3a,b with malononitrile or from reaction of acetohydrazide 1 with arylidenemalononitrile 5a,b . Cyclocondensation of acetohydrazide 1 with salicylaldehyde derivatives and acetylacetone furnished pyrido‐coumarins 6,7 and 2‐pyridone‐3‐carbonitrile 8, respectively. In addition, pyrido‐thiazoles 13 and 15 were obtained through reaction of 2‐(1‐(pyridin‐2‐yl)ethylidene)hydrazinecarbothioamide 11 with hydrazonyl chlorides and α‐haloketones, respectively. The structures of synthesized compounds were elucidated with spectral and elemental data. The antimicrobial activity of the synthesized compounds was studied.     

Synthesis and characterization of chelate polymers containing etheric diphenyl ring in the backbone: thermal,optical, electrochemical,and morphological properties

A novel Schiff base, 4‐bromo‐2‐[(2‐[(5‐bromo‐2‐hydroxyphenyl)methylene]amino‐5‐nitrophenyl)iminomethyl]phenol (M1) was synthesized from the reaction of 5‐brom‐salicylaldehyde with 4‐nitro‐o‐phenylenediamine. Schiff base–metal complex was synthesized from the reaction of 4‐bromo‐2‐[(2‐[(5‐bromo‐2‐ hydroxyphenyl)methylene]amino‐5‐nitrophenyl)iminomethyl]phenol (M1) with copper (II) acetate monohydrate [(CH₃COO)₂ Cu · H₂O] salt. Poly‐ (M1‐Cu‐TDP) was synthesized from the reaction of M1‐Cu with 4,4′‐dithiodiphenol (TDP). Poly(M1‐Cu‐PDP) was synthesized from the reaction of M1‐Cu with 4,4′‐propane‐2,2‐diyldiphenol (PDP). Poly(M1‐Cu‐HDP) was synthesized from the reaction of M1‐Cu with 4,4′‐(1,1,1,3,3,3‐hexafluoropropane‐2,2‐di‐yl)diphenol (HDP). The structures of the synthesized monomer and chelate polymers were confirmed by FT‐IR, UV–Vis, ¹H‐ and ¹³C‐NMR, and elemental analysis. The characterization was made by TGA‐DTA, DSC, size exclusion chromatography, cyclic voltammetry, and solubility tests. Also, surface morphologies of chelate polymers were investigated by scanning electron microscope. Copyright © 2009 John Wiley & Sons, Ltd.     

Iridium‐Catalyzed Intramolecular Asymmetric Allylic Dearomatization Reaction of Benzoxazoles,Benzothiazoles, and Benzimidazoles

An iridium‐catalyzed intramolecular asymmetric allylic dearomatization reaction of benzoxazoles, benzothiazoles, and benzimidazoles was developed. The reaction was found to be compatible with a wide range of five‐membered‐ring electron‐deficient heteroaromatic compounds and furnished the corresponding dearomatized heterocycles in high yield with excellent enantioselectivity.     

Brominated Trihalomethylenones as Versatile Precursors to 3‐Ethoxy, ‐Formyl, ‐Azidomethyl, ‐Triazolyl,and 3‐Aminomethyl Pyrazoles

5‐Bromo[5,5‐dibromo]‐1,1,1‐trihalo‐4‐methoxy‐3‐penten[hexen]‐2‐ones are explored as precursors to the synthesis of 3‐ethoxymethyl‐5‐trifluoromethyl‐1H‐pyrazoles from a cyclocondensation reaction with hydrazine monohydrate in ethanol. 3‐Ethoxymethyl‐carboxyethyl ester pyrazoles were formed as a result of a substitution reaction of bromine and chlorine by ethanol. The dibrominated precursor furnished 3‐acetal‐pyrazole that was easily hydrolyzed to formyl group. In addition, brominated precursors were used in a nucleophilic substitution reaction with sodium azide to synthesize the 3‐azidomethyl‐5‐ethoxycarbonyl‐1H‐pyrazole from the reaction with hydrazine monohydrate. These products were submitted to a cycloaddition reaction with phenyl acetylene furnishing the 3‐[4(5)‐phenyl‐1,2,3‐triazolyl]5‐ ethoxycarbonyl‐1H‐pyrazoles and to reduction conditions resulting in 3‐aminomethyl‐1H‐pyrazole‐5‐carboxyethyl ester. The products were obtained by a simple methodology and in moderate to good yields.     

一种新光致变色二芳基乙烯化合物的合成、光致变色反应动力学、荧光和结构研究

The photochromic diarylethene, 1,2-bis[2-methyl-5-（3-trifluoromethylphenyl）-3-thienyl]perfluorocyclopentene （BMTTP）, was synthesized and its photochromic kinetics, fluorescence and X-ray structure were investigated. This compound underwent a photochromic reaction both in solution and the single crystalline phase. Its cyclization/cycloreversion process was determined to be zeroth/first order reaction, respectively, and this is the first report on the cyclization/cycloreversion reaction order. In addition, its fluorescence property was also discussed.     

Synthesis,Characterization and Polymerization of a Novel Glycidyl Phosphinate

With the aim to obtain flame‐retardant epoxy resins, a new glycidyl phosphinate, 9‐(9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide)‐2,3‐epoxypropyl (DOPO‐Gly) was synthesized via a two‐step synthesis. The subsequent reaction of DOPO‐Gly with BF₃·Et₂O resulted in a polyether with a pendant bulky phosphorylated group. Likewise, the reaction with phthalic acid anhydride gave the expected dihydroxy ester. However, the reaction with tertiary or primary amines led to isomerization and no polymer was obtained.     

meso‐Free Corroles: Syntheses,Structures, Properties,and Chemical Reactivities

5,10‐Bis(pentafluorophenyl)corrole ( 5 ) and 5,15‐bis(pentafluorophenyl)corrole ( 9 ) have been synthesized as meso‐free corroles by rational synthetic routes. Both the structures of these corroles have been unambiguously revealed by X‐ray diffraction analysis and their optical and electrochemical properties have been studied. Chlorination and oxidative dimerization of 5 and 9 have been explored, which revealed a marked different reactivity of the free meso‐positions in 5 and 9 . 10‐Chlorinated corrole 11 was effectively prepared by the reaction of 9 with Palau‘chlor in the presence of 1 % pyridine whereas 5‐chlorinated corrole 12 was obtained in a trace amount from similar chlorination of 5 . 5,5′‐Linked corrole dimer 13 was produced by reaction of 5 with AgNO₂ in a good yield, whereas 10,10′‐linked corrole dimer 14 was formed in a moderate yield by the reaction of 9 with [bis(trifluoroacetoxy)iodo]benzene. Observed large electronic interaction between the two corroles in 13 as compared with that in 14 has been ascribed mainly to conformational flexibility of the former, which allows more coplanar conformation.     

Synthesis,Reactions, and Spectral Characterization of New Fused Pyrazolothienopyridine and Pyrazolopyrrolopyridine Systems

4‐Oxo‐1‐phenyl‐4,7‐dihydropyrazolo[3,4‐b ]pyridine‐5‐carbonitrile compound ( 4 ) was prepared by the reaction of 5‐amino‐3‐methyl‐1‐phenyl pyrazole ( 1 ) with ethyl 2‐cyano‐3‐ethoxyacrylate followed by cyclization using diphenyl ether. The pyrazolopyridinone compound 4 was converted to the chloropyrazolopyridine 5 by the reaction with phosphorus oxychloride. Compound 5 was used as a starting material to synthesize 3‐amino‐4‐substituted pyrazolothienopyridine derivatives 10a–f and ethyl‐3‐aminopyrazolopyrrolopyridine‐2‐carboxylate 21 , which were used as a versatile precursors for synthesis of poly‐fused heterocyclic compounds.     

The Biginelli Reaction with an Imidazolium–Tagged Recyclable Iron Catalyst: Kinetics,Mechanism, and Antitumoral Activity

The present work describes the synthesis, characterization, and application of a new ion‐tagged iron catalyst. The catalyst was employed in the Biginelli reaction with impressive performance. High yields have been achieved when the reaction was carried out in imidazolium‐based ionic liquids (BMI ? PF₆, BMI ? NTf₂, and BMI ? BF₄), thus showing that the ionic‐liquid effects play a role in the reaction. Moreover, the ion‐tagged catalyst could be recovered and reused up to eight times without any noticeable loss in activity. Mechanistic studies performed by using high‐resolution electrospray‐ionization quadrupole‐time‐of‐flight mass (HR‐EI‐QTOF) spectrometry and kinetic experiments indicate only one reaction pathway and rule out the other two possibilities under the development conditions. The theoretical calculations are in accordance with the proposed mechanism of action of the iron catalyst. Finally, the 37 dihydropyrimidinone derivatives, products of the Biginelli reaction, had their cytotoxicity evaluated in assays against MCF‐7 cancer cell linages with encouraging results of some derivatives, which were virtually non‐toxic against healthy cell linages (fibroblasts).     

Chemistry of Phosphonium Ylides. Part 39: Facile Synthesis of Aziridine,Pyridine, Pyrolotriazole Chromenones and Azaphosphinin Chromenones as Antitumor Agents

The reaction of 4‐azido‐2‐oxo‐2H‐chromene‐3‐carbaldehyde with the active nucleophilic phosphacumulenes yielded the corresponding phosphanylidene‐aziridines and chromeno‐pyrolo‐triazoles. On the other hand, the reaction of the allylic phosphonium ylide, hexaphenylcarbodiphosphorane with the azido compound, was also undertaken. In this case, the phosphanylidene‐chromeno‐triazinone was obtained. Further assessment of these new compounds against (breast: MCF‐7 and liver: HPEG2) human solid tumor cell lines is necessary.     

A mechanistic investigation of the three‐component radical photoinitiator system Eosin Y spirit soluble,N‐methyldiethanolamine,and diphenyliodonium chloride

Photo‐DSC and in situ, time‐resolved, laser‐induced, steady‐state fluorescence spectroscopy were used to study the initiation mechanism of the three‐component system: Eosin Y spirit soluble (EYss), N‐methyldiethanolamine, and diphenyliodonium chloride. Kinetic studies based on photo‐DSC revealed that the fastest polymerization occurred when all three components were present (the next fastest was with the dye/amine pair, and the slowest was with the dye/iodonium pair). However, the laser‐induced fluorescence experiments showed that the pairwise reaction between the eosin and iodonium bleaches the dye much more rapidly than does the reaction between the eosin and amine. We concluded that although a direct eosin/amine reaction can produce active radicals in the three‐component system, this reaction is largely overshadowed by the eosin/iodonium reaction, which does not produce active radicals as effectively. We proposed that the amine reduces the oxidized dye radical formed in the eosin/iodonium reaction back to its original state as well as the simultaneous production of an active initiating amine‐based radical. Because of the difference in the pairwise reaction rates for eosin/amine and eosin/iodonium, it is likely that this regeneration reaction was the primary source of active radicals in the three‐component eosin/amine/iodonium system. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 715–723, 2001     

The First Cyclopentadienylalkylphosphane Nickel Chelates: Synthesis,Structures, and Reactions

The first cyclopentadienylalkylphosphane nickel chelate complexes are reported. The anionic ligand obtained by reaction of spiro[2.4]hepta‐4,6‐diene with lithium di‐tert‐butylphosphide was treated with NiCl₂ to yield [η⁵:κ¹‐(di‐tert‐butylphosphanylethyl)cyclopentadienyl]chloronickel(II). From this complex, some acetonitrile‐stabilized cationic complexes were obtained by reaction with the respective silver salts in acetonitrile. Methyl‐ and alkynylnickel chelates were prepared by reaction of the chloronickel complex with methyllithium and by copper‐mediated coupling with terminal alkynes, respectively. Some of the complexes prepared were investigated by X‐ray crystallography or cyclic voltammetry. The alkynylnickel chelates undergo cycloaddition reactions with ethoxycarbonylisothiocyanate or tetracyanoethylene, and the cyclobutenes obtained undergo ring opening to the corresponding dienes. The study includes an NMR spectroscopic investigation of the two conformers of one of these dienes.     

Synthesis,molecular and crystal structure,and properties of 10‐propylthio‐5,10‐dihydrophenarsazine

10‐Propylthio‐5,10‐dihydrophenarsazine 2 was obtained by the reaction of 10‐chloro‐5,10‐dihydrophenarsazine 1 with propanethiol in the presence of triethylamine under mild conditions. The structure of 2 was established by X‐ray single crystal diffraction. The reaction of 2 with 2,4‐bis(ethylthio)‐1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide 3 at room temperature affords a novel route to S‐10(5,10‐dihydrophenarsazine) S′‐ethyl‐S″‐propyltetrathiophosphate 4 . © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:287–291, 2000     

Synthesis of New 1,3,4‐Oxadiazol,Thiadiazole, 1,2,4‐Triazole,and Arylidene Hydrazide Derivatives of 4‐Oxo‐1,4‐dihydroquinoline with Antimicrobial Evaluation

A series of substituted 1,3,4‐oxadiazole, 1,2,4‐triazole, and 1,3,4‐thiadiazole derivatives of the substituted 3‐carboethoxy‐1,4‐dihydro‐4‐oxoquinoline have been synthesized through the reaction of the key intermediate thiosemicarbazide derivatives with different reagents. N′‐Arylidene‐4‐oxo‐1,4‐dihydroquinoline‐3‐carbohydrazides were also synthesized through the condensation reaction of the corresponding hydrazides with the appropriate aldehydes. Antimicrobial activity of some of the synthesized compounds was evaluated.     

Synthesis of Pyridazinones through the Copper(I)‐Catalyzed Multicomponent Reaction of Aldehydes,Hydrazines, and Alkynylesters

The copper‐catalyzed multicomponent cyclization reaction, which combined aldehydes, hydrazines, and alkynylesters, was applied in the synthesis of pyridazinones. The reaction was regioselective and gave only six‐membered pyridazinones in the complete absence of five‐membered pyrazoles or a regioisomeric mixture. During this investigation, the use of 2‐halobenzaldehyde as the starting material, under identical reaction conditions, gave 6‐(2‐ethoxyphenyl)pyridazinones after sequential Michael addition/1,2‐addition/Ullmann cross‐coupling reactions.     

Dendronized Anionic Gold Nanoparticles: Synthesis,Characterization, and Antiviral Activity

Anionic carbosilane dendrons decorated with sulfonate functions and one thiol moiety at the focal point have been used to synthesize water‐soluble gold nanoparticles (AuNPs) through the direct reaction of dendrons, gold precursor, and reducing agent in water, and also through a place‐exchange reaction. These nanoparticles have been characterized by NMR spectroscopy, TEM, thermogravimetric analysis, X‐ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, elemental analysis, and zeta‐potential measurements. The interacting ability of the anionic sulfonate functions was investigated by EPR spectroscopy with copper(II) as a probe. Different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups for complexation by copper(II). Toxicity assays of AuNPs showed that those produced through direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV‐1 infection was higher in the case of dendronized AuNPs than in dendrons.     

Azide telechelics chain extended by click reaction: Synthesis,characterization, and cross‐linking

Azide telechelics of poly(dimethylsiloxane) (PDMS), polypropylene oxide (PPO), and polyethylene oxide (PEO) were synthesized from the corresponding epoxy telechelics and characterized. These oligomeric azides were chain extended by reaction with bispropargyl ether of bisphenol A (BPEBA) through a copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) reaction. PDMS manifested a faster reaction in contrast to PPO or PEO. The chain‐extended polymers underwent cross‐linking above 170°C through thermal cleavage of residual (terminal) azide groups. This was manifested in their rheograms and was further substantiated by FTIR and NMR spectroscopic analyses. Dynamic mechanical analyses of the cross‐linked polymers exhibited characteristic transitions of hard and soft segments, implying microphase separation in the system. Microscopic evaluation of the thermally cross‐linked sample revealed a porous morphology with microsized to nanosized pores.     

Cycloaddition of Aroyl Isothiocyanate: A Novel Synthesis of Triazine,Oxazine, Pyrimidine,and Pyridine Derivatives

A simple and direct synthetic methodology for a novel series of azines and their annulated systems was performed. Heterocyclization of acyl isothiocyanate 2 with urea or malononitrile gave s‐triazine 4 and 1,3‐oxazine 7 derivatives, respectively. The reaction of heteroallene 1 with acetylacetone tolerated 2‐thioxopyridine derivative 9 . The latter compound underwent heterocyclization with urea, hydrazine hydrate, or phenyl hydrazine to give the annulated pyridines 10 – 12 . Pyrimidinethione 14 was resulted from reaction of acylisothiocyanate with enamine 13 . Condensation of compound 14 with hydrazine hydrate, phenyl hydrazine, urea, and 3‐nitrobenzaldehyde in the presence of ethyl cyanoacetate or sodium hydroxide afforded 15 – 20 , respectively.     

Efficient Synthesis of Tetrahydroquinolines from the Reaction of Aldehyde,Aniline, and Alkene under the In Situ Redox of SnCl2 and FeCl3

A highly efficient three‐component Povarov reaction for the synthesis of tetrahydroquinoline derivatives was reported. The reaction of aldehyde, aniline, and alkene was carried out in the presence of Sn(IV), which was generated in situ from the redox reaction of SnCl₂ and FeCl₃, to afford tetrahydroquinoline derivatives in good to excellent yields. This discovery showed a sharp difference from the direct use of unstable SnCl₄. Both aliphatic and aromatic aldehydes could be applied for the synthesis of the heterocycle in the reaction. The structure of the product 6‐chloro‐4‐methyl‐4‐neopentyl‐2‐propyltetrahydroquinoline and 6‐bromo‐4‐methyl‐4‐neopentyl‐2‐propyltetrahydroquinoline was confirmed by X‐ray diffraction analysis.     

Density functional computations of the cyclopropanation of ethene catalyzed by iron (II) carbene complexes Cp(CO)(L)FeCHR,L = CO,PMe3, R = Me,OMe, ph,CO2Me

Density functional theory has been used to study the Fe‐catalyzed cyclopropanation of Fe‐carbene complexes with ethene. All the intermediates and transition states were optimized completely at the B3LYP/6‐31+G(d,p) level. Calculation results confirm that the cyclopropanation of Fe‐carbene complexes with ethene involves the two reaction paths I and II . In the reaction path I , the double bond of ethene attacks directly on the carbene carbon of Fe‐carbene complexes to generate the cyclopropane. In the reaction path II , ethene substitution for PMe₃ or CO in the Fe‐carbene complexes leads to the complexes M2 ; and the attack of one carbon of ethene on the carbene carbon results in the complexes M3 with a Fe? C? C? C four‐membered ring, and then generates the cyclopropane via the elimination reaction. For Fe‐carbene complexes A , C , D , E , and H , the main reaction mode is the reaction path I ; for Fe‐carbene complexes B , F , and G , the main reaction mode is the reaction path II . © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008