Peculiar reaction of N2‐acyl derivatives of 2‐aryl‐5‐hydrazino‐1,3‐oxazole‐4‐carbonitriles with the lawesson reagent

Easily accessible N²‐acyl derivatives of 2‐aryl‐5‐hydrazino‐1,3‐oxazole‐4‐carbonitriles react peculiarly with the Lawesson reagent. In addition to thionation, the reaction involves a recyclization to afford new substituted 2‐(5‐amino‐1,3‐thiazol‐4‐yl)‐1,3,4‐thiadiazoles. Their structure is corroborated spectroscopically and by the X‐ray diffraction method. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:782–785, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20413     

3/4‐phenylene bisheterocycles from ring transformation reaction of sydnone derivatives: Synthesis of 3‐[3/4‐heterocyclyl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones from 3/4‐acetylphenylsydnones and their biological properties

The bifunctional 3/4‐[acetyl]phenylsydnones 1a, 1b were subjected to a one‐pot ring conversion to 3‐[3/4‐acetyl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 2a, 2b , which on further bromination yielded the 3‐[3/4‐bromoacyl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 3a, 3b . Reaction of these compounds with thiourea yielded the 3‐[3/4‐(2‐aminothiazol‐4‐yl)]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 4a, 4b . The other thiazole derivatives 5a, 5b–7a, 7b were prepared by using thiosemicarbazide, thioacetamide, and thiobenzamide, respectively. In another reaction of the bromoacetyl compounds ( 3a, 3b ) with 2‐aminopyridine and 2‐aminothiazole, the fused biheterocyclic compounds 3‐[3/4‐imidazo‐[1,2‐a]pyridine‐2‐yl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 8a, 8b and 3‐[3/4‐imidazo‐[2,1‐b]‐thiazol‐6‐yl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 9a, 9b were obtained. The 3‐[3/4‐(benzofuran‐2‐carbonyl)]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 10a, 10b were obtained by treatment of compounds 3a, 3b with o‐hydroxy benzaldehyde. Most of these compounds exhibited antifungal activity greater than the reference drugs used. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:50–54, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20255     

Luminescent copoly(aryl ether)s with new electron‐transporting bis(3‐(trifluoromethyl)phenyl)‐1,3,4‐oxadiazole or bis(3‐(trifluoromethyl)phenyl)‐4‐(4‐hexyloxyphenyl)‐4H‐1,2,4‐triazole segments

To investigate the effect of trifluoromethyl groups in enhancing electron affinity of aromatic oxadiazole and triazole chromophores, we prepared four new copoly(aryl ether)s ( P1 – P4 ) consisting of bis(3‐(trifluoromethyl) phenyl)‐1,3,4‐oxadiazole (ETO) or bis(3‐(trifluoromethyl)phenyl)‐4‐(4‐hexyloxyphenyl)‐4H‐1,2,4‐triazole (ETT) segments and hole‐transporting segments [2,5‐distyrylbenzene (HTB) or bis(styryl)fluorine (HTF)]. Molecular spectra (absorption and photoluminescence) and cyclic voltammetry were used to investigate their optical and electrochemical properties. The emissions of P1 – P4 are dominated by the hole‐transporting fluorophores with longer emissive wavelengths around 442–453 nm via efficient excitation energy transfer. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of P1 – P4 , estimated from electrochemical data, are ?5.15, ?5.18, ?5.30, ?5.27, ?3.39, ?3.49, ?3.36, and ?3.48 eV, respectively. The LUMO levels of ETO and ETT segments are significantly reduced to ?3.39～?3.36 eV and ?3.48～?3.49 eV, respectively, as compared with ?2.45 eV of P5 containing a 2,5‐diphenyl‐1,3,4‐oxadiazole segment. Moreover, electron and hole affinity can be enhanced simultaneously by introducing isolated hole‐ and electron‐transporting segments in the backbone. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5900–5910, 2004     

Synthesis of some new benzofuran‐based thiophene, 1,3‐oxathiole and 1,3,4‐oxa(thia)diazole derivatives

Treatment of 3‐(3‐methylbenzofuran‐2‐yl)‐3‐oxopropanenitrile ( 1 ) with phenyl isothiocyanate afforded the thioacetanilide derivative 3 , which when reacted with α‐haloketones, α‐halodiketones, and hydrazonoyl chlorides gives thiophene, 1,3‐oxathiole, and 1,3,4‐thiadiazole derivatives 6a,b, 10a,b and 14a–g , respectively. Treatment of 3‐methyl‐2‐benzofurancarboxylic acid hydrazide ( 15 ) with benzaldehyde followed by bromine afforded the 1,3,4‐oxadiazole derivative 18 . Treatment of the acid hydrazide 15 with phenyl isothiocyanate gave the thiosemicarbazide 20 . Compound 20 could be converted into 1,3,4‐oxadiazole, 1,2,4‐triazole‐3‐thione, and 1,3,4‐thiadiazole derivatives 21, 22 , and 23 , respectively. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:294–300, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20298     

Antibacterial and Antifungal Activities of 2‐(substituted ether)‐5‐(1‐phenyl‐5‐(trifluoromethyl)‐1H‐pyrazol‐4‐yl)‐1,3,4‐oxadiazole Derivatives

By replacing the amide bond into 1,3,4‐oxadiazole moiety, a series of 1‐phenyl‐5‐(trifluoromethyl)‐1H‐pyrazole derivatives bearing 1,3,4‐oxadiazole were synthesized and evaluated their antibacterial and antifungal activity. The bioassay results revealed that compounds 7a and 7b showed the strongest antibacterial activity toward pathogen Xanthomonas oryzae pv. oryzae with the EC50 values of 15.0 and 6.4 µg/mL, respectively; compound 6a exhibited comprehensive antifungal activity toward six kinds of fungi; compound 6f could selectively inhibit the growth of Sclertinia sclerotiorum and Rhizoctonia solani with the inhibition rates of 82.5 and 80.3% at the concentrate of 100 µg/mL, respectively; compound 7b exerted good antifungal activity toward Fusarium oxysporum, Cytospora mandshurica, and Rhizoctonia solani with the inhibition rates of 70.8, 69.5, and 71.5%, respectively. The results suggested that this kind of compounds could be further studied as promising antimicrobial agents.     

Construction of a combinatorial library of 2‐(4‐oxo‐4H‐1‐benzopyran‐3‐yl)‐4‐thiazolidinones by microwave‐assisted one‐pot parallel syntheses

A one‐pot liquid‐phase combinatorial synthesis of 2‐(4‐oxo‐4H‐1‐benzopyran‐3‐yl)‐4‐thiazolidinones bearing diverse substituents at the 3‐position under microwave irradiation was successfully performed using 3‐formyl chromone, primary amine, and mercaptoacetic acid as reactants. Compared to an identical library generated by conventional parallel synthesis, the microwave‐assisted parallel synthesis approach dramatically decreased the reaction time from an average of 9 h to 5 min, and substantially increased the product yields. The coupling of microwave technology with liquid‐phase combinatorial synthesis constitutes a novel and particularly attractive avenue for the rapid generation of structurally diverse libraries. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:381–389, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20309     

Synthesis and antifungal activity of novel 5‐substituted 4‐(1,3,4‐thiadiazol‐2‐yl)benzene‐1,3‐diols

5‐Substituted (amine, alkyl, aryl, heterocyclic) 4‐(1,3,4‐thiadiazol‐2‐yl)benzene‐1,3‐ diols were synthesized, and their antifungal properties were examined. The compounds were obtained by the one‐pot reaction of sulfinylbis((2,4‐dihydroxyphenyl)methanethione) with hydrazides or thiosemicarbazides. Their structures were identified from elemental, IR, ¹H NMR, and MS spectra analyses. The activities of the derivatives against five phytopathogenic fungi in vitro were measured. Moderate fungicidal effect of the compounds under consideration was found. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:533–540, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20645     

Synthesis and antibacterial activity of novel series of 2‐(p‐tolyloxy)‐3‐(5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazol‐2‐yl)quinoline

A new series of 2‐(p‐tolyloxy)‐3‐(5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazol‐2‐yl)quinoline were synthesized from oxidative cyclization of N′‐((2‐(p‐tolyloxy)quinoline‐3‐yl)methylene)isonicotinohydrazide in DMSO/I₂ at reflux condition for 3–4 h. The structures of the new compounds were confirmed by elemental analyses as well as IR, ¹H‐NMR, and mass spectral data. All the synthesized compounds were screened for their antibacterial activities against various bacterial strains. Several of these compounds showed potential antibacterial activity. J. Heterocyclic Chem., (2011).     

Syntheses and antimicrobial activities of 4‐aryl‐5‐phenylimino‐3‐S‐(hepta‐O‐acetyl lactosyl)‐1,2,4‐thiadiazolines

A series of 4‐aryl‐5‐phenylimino‐3‐S‐(hepta‐O‐acetyl lactosyl)‐1,2,4‐thiadiazolines have been synthesized by the interaction of S‐(hepta‐O‐acetyl lactosyl)‐1‐arylisothiocarbamides and S‐chloro‐N‐phenyl isothiocarbamoyl chloride. The title compounds were characterized on the basis of elemental analysis and IR, NMR, mass spectral studies. The title compounds exhibited comparable antimicrobial activities against pathogens such as E. coli, S. aureus, P. vulgaris, S. typhi, A. niger, and Candida guilliermondii. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:390–392, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20310     

Synthesis of novel N‐alkyl/aryl‐N′‐(4‐arylthiazol‐2‐yl)‐N″‐xylosyl guanidines

The reaction of 2,3,4‐tri‐O‐acetyl‐β‐D‐xylopyranosyl isothiocyanate ( 1 ) and 2‐amino‐4‐arylthiazoles ( 2 ) gave xylosylthioureas 3 . These thiourea derivatives reacted with alkyl/aryl amine in the presence of HgCl₂ to give a new series of N‐alkyl/aryl‐N″‐(4‐arylthiazol‐2‐yl)‐N″‐xylosyl guanidines 4 . Some of the synthesized guanidines were screened for their biological activity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:688–694, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20379     

A one‐pot efficient four‐component reaction for the synthesis of 2‐(arylamino)‐2‐(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)propyl benzoate (or acetate) derivatives

Reactions of (N‐isocyanimino) triphenylphosphorane with 2‐oxopropylbenzoate (or acetate) in the presence of aromatic carboxylic acids and primary amines proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4‐oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:692–698, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20735     

The Synthesis of 2‐(Chromon‐2/3‐yl)‐3‐(5‐thione‐4‐hydro‐1,3,4‐thiadiazol‐2‐yl)‐4‐oxo‐thiazolidine

2‐Formylchromones and 3‐formylchromones as the first materials singly reacted with 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole to give the corresponding Schiff bases, which on cyclocondensation with mercapto‐acetic acid in 1,4‐dioxane yielded target compounds named 4‐oxo‐thiazolidines. The structures of all the synthetic compounds were confirmed by elemental analysis and IR, ¹H NMR, LC‐MS (ESI) spectral data.     

In(OTf)3催化下水相合成2-(3,4,5-三甲氧基苯基)-5-[(5-烷硫基-1,3,4-噁二唑-2-基)硫甲基]-1,3,4-噻二唑类衍生物

以2-巯基-5-(3,4,5-三甲氧基苯基)-1,3,4-噻二唑为原料,经醚化、酰肼化、闭环、硫醚化四步反应合成了10个2-(3,4,5-三甲氧基苯基)-5-[(5-烷硫基-1,3,4-噁二唑-2-基)硫甲基]- 1,3,4-噻二唑类衍生物。通过元素分析、IR、MS、1H NMR和 13C NMR对目标化合物进行了表征。采用In(OTf)3催化下40 oC水相合成目标化合物,具有反应条件温和、合成收率高、催化剂可循环使用等特点。     

Regioregular poly[3‐(4‐alkoxyphenyl)thiophene]s

An easy synthetic procedure for soluble poly[3‐(4‐alcoxyphenyl)thiophene]s is reported. The polymers present a high regioregularity degree as determined by both UV–vis spectra and ¹H and ¹³C NMR analysis. Furthermore, X‐ray powder diffraction analysis performed on films of the polymers suggests a π‐stacked packing structure of the macromolecules. Electrical characterization was performed on one of the synthesized polythiophenes on both undoped and doped (with FeCl₃ or iodine) films. The conductivity and charge‐carrier mobility were assessed by current–voltage and field effect measurements. Well‐structured polymer films were obtained simply via spin coating from chloroform solutions and without the need of further processing, unlike other regioregular polythiophenes reported in the literature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1758–1770, 2007     

Synthesis of Novel 1‐(5‐(Benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3H)‐ylidene)‐thiourea/urea Derivatives and Evaluation of Their Antimicrobial Activities

A new series of 1‐(5‐(benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3H)‐ylidene)‐thiourea/urea derivatives ( 1a – j ) were designed and synthesized. For the first time, (i) a new process was developed for N‐methylation of 1,3,4‐thiadiazole moiety using dimethyl carbonate an environmentally benign reagent in presence of N,N,N′,N′‐tetramethylethylenediamine and (ii) the sulfide was selectively oxidized to sulfoxide in higher yield by using chlorine (g) in aqueous acetic acid media under mild reaction condition. The synthesized compounds ( 1a – j ) were investigated for their antimicrobial activities. The tested compounds ( 1a – j ) were exhibited moderate to excellent antibacterial activities against both Gram‐positive and Gram‐negative bacterial strains. The same compounds exhibited good antifungal activities against selected fungal strains. Particularly, the compounds 1b , 1d , 1h , and 1i were proved to be promising leads exhibiting both antibacterial and antifungal activities compared with standard drugs, ciprofloxacin, and fluconazole. The presence of 1,3,4‐thiadiazole moiety has a significant role in the display of antimicrobial activity. In addition, the presence of both sulfinyl and thiourea or urea functionalities has enhanced the activity as per obtained antimicrobial activity data.     

Synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]‐pyrimidine‐6‐carboxamides

Possible approaches to synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]pyrimidine‐6‐carboxamides 4 have been discussed. It is shown that the preferable approach is cyclization of 2‐iminocoumarin‐3‐carboxamides 1 , utilizing 5‐amino‐3‐methyl‐N²‐arylthiophene‐2,4‐dicarboxamides 2 as binucleophilic reagents. The proposed procedure allowed us to easily obtain 4 in two stages, using common reagents. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:341–346, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20303     

Microwave‐assisted synthesis and anti‐HIV activity of new benzenesulfonamides bearing 2,5‐disubstituted‐1,3,4‐oxadiazole moiety

New benzenesulfonamides, most of which are chiral, incorporating 1,3,4‐oxadiazole, and selected amino acid entities have been synthesized, using the microwave irradiation method. Most of the synthesized compounds were tested against HIV activity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:425–431, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20316     

ZnII and CuII complexes generated from 5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione

A new 1,3,4‐oxadiazole‐containing bispyridyl ligand, namely 5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione (L), has been used to create the novel complexes tetranitratobis{μ‐5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione}zinc(II), [Zn₂(NO₃)₄(C₁₄H₁₂N₄OS)₂], (I), and catena‐poly[[[dinitratocopper(II)]‐bis{μ‐5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione}] nitrate acetonitrile sesquisolvate dichloromethane sesquisolvate], {[Cu(NO₃)(C₁₄H₁₂N₄OS)₂]NO₃·1.5CH₃CN·1.5CH₂Cl₂}_n, (II). Compound (I) presents a distorted rectangular centrosymmetric Zn₂L₂ ring (dimensions 9.56 × 7.06 Å), where each Zn^II centre lies in a {ZnN₂O₄} coordination environment. These binuclear zinc metallocycles are linked into a two‐dimensional network through nonclassical C—H...O hydrogen bonds. The resulting sheets lie parallel to the ac plane. Compound (II), which crystallizes as a nonmerohedral twin, is a coordination polymer with double chains of Cu^II centres linked by bridging L ligands, propagating parallel to the crystallographic a axis. The Cu^II centres adopt a distorted square‐pyramidal CuN₄O coordination environment with apical O atoms. The chains in (II) are interlinked via two kinds of π–π stacking interactions along [01]. In addition, the structure of (II) contains channels parallel to the crystallographic a direction. The guest components in these channels consist of dichloromethane and acetonitrile solvent molecules and uncoordinated nitrate anions.     

Synthesis and tuberculostatic activity of novel N′‐methyl‐4‐(pyrrolidin‐1‐yl)picolinohydrazide and N′‐methylpyrimidine‐2‐carbohydrazide derivatives

The synthesis of N′‐methyl‐4‐(pyrrolidin‐1‐yl)picolinohydrazide and N′‐methyl‐pyrimidine‐2‐carbohydrazide derivatives ( 5a and 5b ) was carried out. These compounds were used as starting materials to obtain methyl N′‐methylhydrazinecarbodithioates 6a and 6b , which, on reaction with either triethylamine or hydrazine, gave corresponding 1,3,4‐oxadiazioles 7a and 7b or 1,2,4‐triazoles 9a and 9b with the free NH₂ group at the N‐4 position, respectively. Compounds 8a – e , particularly containing cyclic amines at N‐4 of the 1,2,4‐triazole ring, were also obtained. Synthesized compounds were tested in vitro for their activity against Mycobacterium tuberculosis. The structure–activity relationship analysis for obtained compounds was done. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:223–230, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21008