Synthesis of 1,2,4- and 1,3,4-oxadiazoles from 1-aryl-5-methyl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazole-4-carbonyl chlorides

5-Substituted 2-(1-aryl-5-methyl-1H-1,2,3-triazol-4-yl)-1,3,4-oxadiazoles were synthesized by reaction of 1-aryl-5-methyl-1H-1,2,3-triazole-4-carbonyl chlorides with the corresponding 5-substituted 1H-tetrazoles. 5-Methyl-1-phenyl-1H-1,2,3-triazole-4-carbonyl chloride reacted with N′-hydroxybenzimidamides to give 3-aryl-5-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-1,2,4-oxadiazoles. Reactions of 4-(5-methyl-1H-1,2,3-triazol-1-yl)benzoic acid with N′-hydroxybenzimidamides resulted in the formation of 3-aryl-5-[4-(5-methyl-1H-1,2,3-triazol-1-yl)phenyl]-1,2,4-oxadiazoles.     

Synthesis and Spectral Characterization of Some Novel Thiazolyl-Pyrazoline Derivatives Containing 1,2,3-Triazole Moiety

Abstract

A series of novel 3-aryl-5-(2-aryl-1,2,3-triazol-4-yl)-1-(4-aryl-2-thiazoyl)-pyrazolines 6a–6r were synthesized using 2-aryl-4-formyl-1,2,3-triazoles 1a,b as the starting materials. Thus, reacting 1a,b with 1-arylethanones 2a–2c gave 1-aryl-3-(2-aryl-1,2,3-triazol-4-yl)-2-propen-1-ones 3a–3f. The reaction of the latter with thiosemicarbazide afforded 3-aryl-5-(2-aryl-1,2,3-triazol-4-yl)-1-thiocarbamoyl-pyrazolines 4a–4f, which condensed with 2-bromo-1-arylethanones 5a–5c to afford the target compounds 6a–6r. The chemical structures of the compounds were verified by means of their IR, ¹H NMR, ESI-MS spectroscopic data, and elemental analysis.

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GRAPHICAL ABSTRACT     

Synthesis of [5-(1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-4-yl)-1,3,4-oxadiazol-2-yl]pyridines

2-, 3-, and 4-[5-(1-Aryl-5-R-1H-1,2,3-triazol-4-yl)-1,3,4-oxadiazol-2-yl]pyridines were synthesized from the corresponding 1-aryl-5-R-1H-1,2,3-triazole-4-carbonyl chlorides and 2-, 3-, and 4-(1H-tetrazol-5-yl)-pyridines.     

Synthesis of 1-(1-aryl-1H-1,2,3-triazol-4-yl)-β-carboline derivatives

Reaction of 5-methyl-1-aryl-1H-1,2,3-triazole-4-carbocylic acid chlorides with tryptamine derivatives afforded substituted 1-aryl-N-[2-(1H-indol-3-yl)ethyl]-5-methyl-1H-1,2,3-triazole-4-carboxamides. At heating these compounds in toluene in the presence of POCl₃ and P₂O₅ Bischler-Napieralski cyclization occurs giving 1-(1-aryl-5-methyl-1H-1,2,3-triazol-4-yl)-4,9-dihydro-3H-β-carbolines that can be transformed into β-carboline and tetrahydro-β-carboline derivatives.     

新型N-(5-烷基-1,3,4-噻二唑-2-基)-11[(杂芳基)甲基]-5-甲基-1H-1,2,3-三唑基-4-甲酰胺的合成与生物活性

为了寻找新型高效低毒的农药先导化合物,采用1-[(杂芳基)甲基]-5-甲基-1H-1,2,3-三唑基-4-甲酰氯与2-氨基-5-烷基-1,3,4-噻二唑的缩合反应,合成了8种未见文献报道的目标化合物,其结构经IR,1H NMR和元素分析确证,部分化合物还经MS的进一步证实.初步的生物活性测试结果表明,部分目标化合物在100 mg/L浓度下对双子叶植物(油菜)显示出中等的除草活性和一定程度的杀虫活性(250 mg/L).     

新型N-(5-烷基-1,3,4-噻二唑-2-基)-1-[(杂芳基)甲基]-5-甲基-1H-1,2,3-三唑基-4-甲酰胺的合成与生物活性

为了寻找新型高效低毒的农药先导化合物, 采用1-[(杂芳基)甲基]-5-甲基-1H-1,2,3-三唑基-4-甲酰氯与2-氨基-5-烷基-1,3,4-噻二唑的缩合反应, 合成了8种未见文献报道的目标化合物, 其结构经IR, 1H NMR和元素分析确证, 部分化合物还经MS的进一步证实. 初步的生物活性测试结果表明, 部分目标化合物在100 mg/L浓度下对双子叶植物(油菜)显示出中等的除草活性和一定程度的杀虫活性(250 mg/L).     

Synthesis of heterocycles. Part VI. Synthesis and antimicrobial activity of some 4-amino-5-aryl-1,2,4-triazole-3-thiones and their derivatives

4-Amino-5-aryi-1,2,4-triazole-3-thiones I react with acid chlorides to yield 4-acylamino-5-aryl-1,2,4-triazole-3-thiones II. Compounds I also react with methylene iodide, chloroacetonitrile and methyl bromoacetate to give bis-(4-amino-5-aryl-1,2,4-triazol-3-ylthio)methanes III, 4-amino-5-aryl-3-cyanomethylthio-1,2,4-triazoles IV and 4-amino-5-aryl-3-carbomethoxymethylthio-1,2,4-triazoles V, respectively. Compounds V react with hydrazine hydrate to give the corresponding acid hydrazides VI which in turn condenses with acid chlorides and aldehydes to afford respectively 1-[(4-amino-5-aryl-1,2,4-triazol-3-ylthio)acetyl]-2-aroylhydrazines VII and aryl methylene (4-amino-5-aryl-1,2,4-triazol-3-ylthio)acethydrazones VIII. The antimicrobial activities of the above compounds were screened against different strains of bacteria and fungi.     

Synthesis of heterocycles based on arylation products of unsaturated compounds: XVII. Arylation of 2-acetylfuran and synthesis of 3-R-6-(5-aryl-2-furyl)-7<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazines

Reaction of 2-acetylfuran with arenediazonium chlorides under Meerwein reaction conditions led to the formation of 5-aryl-2-acetylfurans. The bromination of these compounds gave 2-bromo-1-(5-aryl-2-furyl)-ethanones that reacted with 4-amino-4H-5-R-1,2,4-triazole-3-thiols to form 3-R-6-(5-aryl-2-furyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines.     

Synthesis and Herbicidal Activity of O,O-Dialkyl(phenyl)-N-{1-[(6-chloropyridin-3-yl)methyl]-4-cyano-1H-1,2,3-triazol-5-yl}-1-amino-1-substitutedbenzyl-phosphonates

Abstract

A series of novel α-amino phosphonate derivatives containing both pyridine and 1,2,3-triazole moieties 4 were synthesized via a multi-step reaction. First, the condensation of 5-amino-1-[(6-chloropyridin-3-yl) methyl]-4-cyano-1H-1,2,3-triazole with various aromatic aldehydes in the presence of magnesium perchlorate afforded imines 3 in moderate yields; second, imines 3 reacted with dialkyl phosphites or triphenyl phosphite to give the title compounds 4 in moderate to good yields. Their structures were elucidated by spectroscopic data (IR, ¹H NMR, ³¹P NMR, ESI-MS) and elemental analysis. The preliminary bioassay (in vitro) indicated that some of the title compounds 4 possessed moderate herbicidal activities against dicotyledonous plants (Brassica campestris L) at a concentration of 100 mg/L. However, compounds 4 did not exhibit herbicidal activities against Brassica campestris L at a concentration of 10 mg/L.

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GRAPHICAL ABSTRACT      

UNPRECEDENTED OUTCOME OF BASE-PROMOTED NEBER REARRANGEMENT OF O-MESYLOXIME OF 2-ARYL-1,2,3,4-TETRAHYDRO-1-METHYLSUL FONYL-4-QUINOLONE- SYNTHESIS OF 4-AMINO-2-ARYLQUINOLINES

Abstract

O-Mesyloximes derived from 2-aryl-1,2,3,4-tetrahydro-1-methylsulfonyl-4-quinolones react with sodium ethoxide in ethanol to afford the 4-amino-2-arylquinolines in high yield. No traces of the 3-amino-2-aryl-4-quinolones expected from the Neber rearrangement of the substrates were detected or isolated from the reaction mixture. The structures of the products were determined using a combination of ¹H NMR, ¹³C NMR, IR and mass spectroscopic techniques.     

A One-Pot Synthesis of Functionalized 2,3-Dihydrothiazoles from Isothiocyanates,Primary Alkylamines,and Phenacyl Bromides

Abstract

A simple, one-pot synthesis of N-(4-aryl-3-alkylthiazol-2(3H)-ylidene)anilines and N-(4-aryl-3-alkylthiazol-2(3H)-ylidene)benzamides via the reaction of primary alkylamines, α-bromoketones, and phenylisothiocyanate or benzoylisothiocyanate is described.

GRAPHICAL ABSTRACT     

SYNTHESIS AND REACTIONS OF TRIPHENYLPHOSPHONIMINOGLYOXALIC ACID ANILIDE ARYLHYDRAZONES

Abstract

A series of α-azidoglyoxatic acid anilide arylhydrazones 2 were prepared and converted to the corresponding phosphonimines 6 by reaction with triphenylphosphine. Treatment of the latter with acyl chlorides yielded the phosphonium salts 9 which afforded, upon treatment with triethylamine, 1, 5-disubstituted 1H-1, 2, 4-triazole-3-carboxylic acid anilides 11. Acid hydrolysis of 6 yielded the amidrazones 8.     

Microwave-Assisted Direct Synthesis of 4H-1,2,4-Benzothiadiazine 1,1-Dioxide Derivatives

Abstract

We describe a rapid and convenient methodology for the preparation of diverse 3-aryl and 3-trifluoromethyl 4H-1,2,4-benzothiadiazine-1,1-dioxides in a one-pot microwave-promoted reaction between 2-aminobenzenesulfonamides and benzaldehydes, trifluoroacetic acid or benzoic acids.

GRAPHICAL ABSTRACT      

Transaminations of enaminones:A Synthesis of tricyclic,N-aryl, 1,2,3-triazole-fused pyridones

1-Phenylmethyl- and 1-(4-methoxyphenylmethyl)-5-chloro-1,2,3-triazole-4-carbonyl chlorides acylated the pyrrolidine enamines of cyclopentanone and cyclohexanone, and the resulting enaminones underwent transaminations with aryl amines under acidic conditions. The products then cyclized under basic conditions to linearly fused, tricyclic 3-phenylmethyl- and 3-(4-methoxyphenylmethyl)-4-aryl-8-oxo-4,5,6,7-tetrahydrocyclopenta[6]-1,2,3-triazolo[4,5-e]pyridines, and to 5,6,7,8-tetrahydro-4-aryl-3H-1,2,3-triazolo[4,5-b]quinolin-9(4H)-ones. Similar transaminations afforded the related 8-phenyl- and 8-(3-chlorophenyl)-1,5,7,8-tetrahydro-1-(phenylmethyl)-4H-thieno[3,4-e]-1,2,3-triazolo[4,5-b]pyridin-4-ones. Phase-transfer and catalytic hydrogenolyses of some of these intermediates furnished 4-aryl-8-oxo-4,5,6,7-tetrahydrocyclopenta[b]-1,2,3-triazolo[4,5-e]pyridines and 4-aryl-5,6,7,8-tetrahydro-3H,2,3-triazolo[4,5-b]quinoline-9-(4H)-ones. The 3-(4-methoxyphenylmethyl)-4-aryl intermediates were sterically crowded. Two protons from the methoxyphenylmethylphenylmethylgroups were dramatically shielded because of anisotropic effects exerted by the 4-aryl substituents.     

Synthesis and Antimicrobial Activity of Some New 5-(3-Chloro-1-Benzothiophen-2-YL)-1,3,4-Oxadiazole-2-Thiol and Their Derivatives

Abstract

3-Chloro-1-benzothiophene-2-carbonylchloride 1 was made to reacts with hydrazine hydrate afforded 3-chloro-1-benothiophene-2-carbohydrazide 2 in good yield. 5-(3-chloro-1-benzothiophen-2-yl)-1,3,4-oxadiazole-2-thiol 4 was synthesized from 3-chloro-1-benzothiophene-2-carbohydrazide 2. Mannich bases, alkyl halide, and acid chlorides derivatives were then prepared. Compound 4 on condensation with chloroacetone in the presence of NaOH as base and ethanol as solvent gave 1-{[5-(3-chloro-1-benzo[b]thiophen-2-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}propan-2-on 6. Condensation of compound 6 with various aromatic aldehydes afforded a series of chalcones 7a–h. The structures of all the synthesized compounds were confirmed by spectral data and have been screened for antibacterial activity.

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GRAPHICAL ABSTRACT      

Synthesis of 1,4,5-trisubstituted-1,2,3-triazoles via coupling reaction of diaminomaleonitrile with aromatic diazonium salts

A mild procedure for the preparation of 2-(5-amino-1-aryl-1H-1,2,3-triazol-4-yl)-2-iminoacetonitriles and 2-(5-amino-1-aryl-1H-1,2,3-triazol-4-yl)-2-oxoacetonitriles was achieved by the reaction of diaminomaleonitrile and phenyl/substituted phenyl diazonium chlorides. 4-Nitrophenyl diazonium chloride afforded 2-amino-3-(3-(4-nitrophenyl)triaz-1-en-1-yl)maleonitrile. Triazole iminoacetonitrile and maleonitrile derivatives were reacted further with excess acetone and benzaldehyde with a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene to yield 5-(5-imino-2,2-dimethyl-2,5-dihydrooxazol-4-yl)-3-aryl-3H-1,2,3-triazol-4-amine and (E)-N-benzylidene-5-(5-imino-2-aryl-2,5-dihydrooxazol-4-yl)-3-aryl-3H-1,2,3-triazol-4-amine, respectively. Two competitive reactions, i.e., nucleophilic substitution and nucleophilic addition, were observed when triazole oxoacetonitrile and maleonitrile derivatives were reacted with hydroxylamine hydrochloride in the presence of sodium acetate.     

Synthesis of heterocycles from arylation products of unsaturated compounds: XVIII. 5-Arylfuran-2-carboxylic acids and their application in the synthesis of 1,2,4-thiadiazole, 1,3,4-oxadiazole,and [1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazole derivatives

Arylation of furan-2-carboxylic acid or its methyl ester with arenediazonium chlorides in the presence of copper(II) chloride gave the corresponding 5-arylfuran-2-carboxylic acids or methyl 5-arylfuran-2-carboxylates. 5-Arylfuran-2-carbonyl chlorides reacted with potassium thiocyanate and then with 5-methyl-1,2-oxazol-3-amine to give 5-aryl-N-[3-(2-oxopropyl)-1,2,4-thiadiazol-5-yl]furan-2-carboxamides as a result of recyclization of intermediate isoxazolylthiourea derivatives. The reactions of 5-arylfuran-2-carbonyl chlorides with 5-(2-furyl)-1H-tetrazole involved opening of the tetrazole ring with elimination of nitrogen molecule and led to the formation of 2-(5-arylfuran-2-yl)-5-(2-furyl)-1,3,4-oxadiazoles. 3-Substituted 6-(5-arylfuran-2-yl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles were obtained by condensation of 5-arylfuran-2-carboxylic acids with 5-substituted 4-amino-4H-1,2,4-triazole-3-thiols in phosphoryl chloride.     

Investigation on the Ring-Opening Reactions of 3-(1H-1,2,4-Triazol-1-yl)1,5-benzothiazepines with Arylonitrile Oxides

Abstract

Novel ring opening compounds, (Z)-2-((Z)-((E)-1,3-diaryl-2-(1H-1,2,4-triazol-1-yl)allylidene)amino)aryl N-hydroxybenzimidothioates 4a–r, were obtained from the reaction of 2,4-diaryl-3-(1H-1,2,4-triazol-1-yl)-2,5-dihydro-1,5-benzothiazepines 3a–f and arylonitrile oxides. The structure of these products has been elucidated by spectroscopic analysis and, in one case, X-ray crystallographic analysis. According to the result, it was presumed that this reaction did not proceeded through 1,3-dipolar cycloaddition reaction.

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GRAPHICAL ABSTRACT