Modification of biologically active amides and amines with fluoro-containing heterocycles 5. Fluoro-containing heterocyclic derivatives of 2-amino-1,3,4-thiadiazoles

An approach to modification of biologically active 2-amino-1,3,4-thiadiazoles with fluoro-containing five-membered heterocycles was proposed. The approach involves reactions of imines (generated in situ from 2-amino-1,3,4-thiadiazoles and methyl trifluoropyruvate) with 1,3-binucleophiles such as 6-aminouracils, 6-aminothiouracils, N-substituted 3-aminocyclohexenones, N-substituted ureas, N-substituted benzamidines, and 3-aminocrotononitrile.     

Carbon suboxide and some of its reactions

The reaction of carbon suboxide with a number of 2-amino-1,3,4-thiadiazoles has given the corresponding pyrimido[1,2-b]-1,3,4-thiadiazoles     

Solid-phase synthesis of substituted 1,3,4-thiadiazoles

Two novel and facile syntheses strategies for the synthesis of substituted 1,3,4-thiadiazoles on solid support are described based on a resin-bound thiosemicarbazide: (a) treatment with aldehydes to form immobilised thiosemicarbazones, and oxidative cyclodehydration with iron(III) chloride forms resin-bound 1,3,4-thiadiazoles; and (b) treatment with di-(2-pyridyl)thionocarbonate affords immobilised 1,3,4-thiadiazole-2-thione which is selectively mono-S-alkylated to yield resin-bound 2-alkylthio-1,3,4-thiadiazoles. Acidic cleavage with trifluoroacetic acid yields the products from both studies in good yield and excellent purity.     

Reactivity of 2-amino-1,3,4-thiadiazoles. Methylation reactions of some 2-amino-5-benzoyl-1,3,4-thiadiazoles

Methylation reactions of 2-amino-5-benzoyl-1,3,4-thiadiazoles 1a-d are reported as a function of alkylating agents (methyl iodide, dimethyl sulfate-potassium carbonate, diazomethane, dimethyl-sulfate-sodium methoxide). Methylation occurs at both the ring nitrogen in position 3 and the exocyclic nitrogen atom.     

Synthesis and mass-spectrometric study of 2-amino- and 2-chloro-5-aryl-1,3,4-thiadiazoles

The cyclization of aldehyde thiosemicarbazones with ferric chloride yielded 2-amino-5-aryl-1,3,4-thiadiazoles, forming 2-chloro-5-aryl-1,3,4-thiadiazoles in the Sandmeyer reaction. The mass-spectrometric behavior of the 2-amino- and 2-chloro-5-aryl-1,3,4-thiadiazoles was studied; the typical routes of fragmentation characteristic of each group of compounds were found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1416–1419, October, 1986.     

A novel series of 2,5-disubstituted 1,3,4-thiadiazoles as potential anticonvulsant agent

<正>In pursuit for better antiepileptic drug and the importance of semicarbazones and 2,5-disubstituted 1,3,4-thiadiazoles as anticonvulsant pharmacophore,a series of novel N-({5-[(6-methyl-1-benzofuran-3-y1)methyl]-1,3,4-thiadiazol-2-yl}carbamothioyl) -2/3/4-substitutedbenzamide were designed,synthesized and evaluated for their anticonvulsant activity.The findings of the present studies confirmed that the pharmacophore model with four binding sites is crucial for anticonvulsant activity. Structure-activity relationships among synthesized compounds were also established.     

Reactivity of 2-amino-1,3,4-thiadiazoles. Nucleophilic behaviour of some 2-amino-1,3,4-thiadiazoles: Model compounds

The ambident nucleophilic behaviour of some 2-amino-5-H-1,3,4-thiadiazoles in alkylation, acylation and nitrosation reaction has been verified. The structures assigned to the 2-amino-1,3,4-thiadiazoles ( 1a-i ) and to the Δ²-1,3,4-thiadiazolines ( 2a-e ) agree with the spectral data.     

2-芳酰氨基-5-苄基-1,3,4-噻二唑上亚甲基与4-二甲氨基苯甲醛加成反应

本文报道了2-芳酰氨基-5-苄基-1,3,4-噻二唑(1a～l)与4-二甲氨基甲醛在EtONa/EtOH体系中反应得到12种新的2-芳酰氨基-5-[1'-苯基-2'-羟基(4'-二甲氨基苯乙基)]-1,3,4-噻二唑(2a～l) .     

2-芳酰氨基-5-苄基-1,3,4-噻二唑上亚甲基与4-二甲氨基苯甲醛加成反应

1,3,4—噻二唑杂环化合物具有广泛的生物活性,如调节植物生长,杀菌,除草,杀虫等。因此它的合成及其反应引起了化学家的兴趣。Elmoghayar等报道了2—芳酰氨基—5—氰甲基—1,3,4—噻二唑中活泼亚甲基与苯甲醛的反应生成2—芳酰氨基—5—(1＇—氰基苯乙烯基)—1,3,4     

Synthesis ofβ-chloroethylamino derivatives in the 1,3,4-thiadiazole series. I

A study is made of the hydroxyethylation of some 2-amino-5-aryl-1,3,4-thiadiazoles and replacement of the hydroxyl group in the hydroxyethylation products by chlorine, as well as of condensation of p-[di(β-chloroethyl)amino]phenylacetyl chloride with the 2-amino-5-aryl-1,3,4-thiadiazoles.     

肼类衍生物在五元唑类杂环合成中的应用进展

简要概述了肼类衍生物的结构及反应活性,总结了近十年来肼类衍生物分别在合成五元唑类杂环如吡唑、噻唑、1,3,4-噁二唑、1,3,4-噻二唑以及三唑类化合物,及其相关的稠杂环如吡唑并某环、s-三唑[3,4-b][1,3,4]-噻二唑、s-三唑[3,4-b][1,3,4]-噻二嗪,以及含有1,2,4-三唑的稠杂环化合物等合成中的应用进展.     

1H, 13C, 15N and 19F NMR study of acetylation products of heterocyclic thiosemicarbazones

Novel 2-acetylamino-4-acetyl-5-aryl(heteryl)-1,3,4-thiadiazolines, 2-acetylamino-5-aryl(heteryl)-1,3,4-thiadiazoles, and some of their salts were prepared and studied by multinuclear 1H, 13C, 15N, 19F and 2D NMR spectroscopy. The acetylation of thiosemicarbazones is accompanied by ring closure to form the corresponding 1,3,4-thiadiazolines and 1,3,4-thiadiazoles. 15N NMR spectroscopy is a unique method for the identification of thiadiazole pyridinium salts.     

Synthesis and application of 2-arylazo-5-[styryl-4-(β-cyano/-carbethoxy-β-cyanoethenyl)]-1,3,4-thiadiazoles

A novel efficient synthesis of 2-arylazo-5-[styryl-4-(β-cyano/carbethoxy-β-cyanoethenyl)]-1,3,4-thiadiazoles was achieved by the condensation of 2-arylazo-5-methyl-1,3,4-thiadiazoles with 4-(β-cyano-β-carbethoxyethenyl)benzaldehyde or 4-(β,β-biscyanoethenyl)benzaldehyde in the presence of acetic anhydride.     

SYNTHESIS OF 2-AROYLAMINO-5-ARYLOXYMETHYL-1,3,4-THIADIAZOLES UNDER LIQUID-LIQUID PHASE TRANSFER CATALYSIS

2-Aroylamino-5-aryloxymethyl-1,3,4-thiadiazoles (I _1–20 ) are synthesized by the condensation of 2-amino-5-aryloxymethyl-1,3,4-thiadiazoles with aroyl chlorides in the presence of PEG-400 phase transfer catalyst.     

An efficient synthesis of styryl 1,3,4-thiadiazoles using Lawesson’s reagent and Propylphosphonic anhydride-precursors for bis heterocycles

The compounds styryl 1,3,4-thiadiazoles were prepared adopting one and two step methodologies to optimize the yield of the products. The two-step methodology via benzohydrazide followed by treatment with Lawesson’s reagent in the presence of Propylphosphonic anhydride and triethylamine produced styryl 1,3,4-thiadiazoles in excellent yields. The olefin moiety in these compounds is utilized to develop pyrazole and isoxazole rings by 1,3-dipolar cycloaddition methodology followed by oxidation.     

Chemistry of amidrazones—II : Synthesis and cyclisation of 1-thioacylamidrazones

1-Thioaroylamidrazones are formed by the action of carboxymethyl dithioates on unsubstituted amidrazones; they are cyclised by acids to 2,5-disubstituted 1,3,4-thiadiazoles. 1-(Ethoxythiocarbonyl)amidrazones are similarly accessible by the use of ethoxythiocarbonylthioacetic acid. They yield 3-ethoxy (or hydroxy)-5-substituted-1,3,4-thiadiazoles under the influence of acids, but are cleaved into smaller fragments by alkalis.     

Synthesis of 2-(N-formyl)-5-aryl/aryloxymethyl-1,3,4-thiadiazoles with potential bioactivity in PEG-400

<正>An environmental benign procedure for synthesis of 2-(N-formyl)-5-aryl/aryloxymethyl-1,3,4-thiadiazoles has been developed by reaction of 2-amino-5-aryl/aryloxymethyl-1,3,4-thiadiazoles with formic acid in PEG-400.The key advantages of this protocol are the shorter reaction time,higher yields,lower cost,simple workup,and environment-friendly compared to conventional organic solvent reaction.The present method does not involve any hazardous organic solvent or catalyst.     

1,3,4-噻二唑衍生物合成及其生物活性研究进展

1,3,4-噻二唑是含有N、S杂原子的五元杂环化合物,具有多种生物活性。目前,1,3,4-噻二唑及其衍生物广泛用于生物、医药等领域,尤其在抗菌、抗肿瘤、抗癌等方面的研究已取得重大突破。由于1,3,4-噻二唑结构的特殊性以及优越的生物活性,对其进行研究有重要意义。本文主要概述了近年来1,3,4-噻二唑衍生物的几种合成方法以及其在抗菌、抗肿瘤、抗癌方面的研究进展。     

One-pot synthesis of 1,3,4-thiadiazoles using Vilsmeier reagent as a versatile cyclodehydration agent

A simple and efficient synthetic method for the one-pot synthesis of 1,3,4-thiadiazoles utilizing Vilsmeier reagent was developed. In this method carboxylic acids and hydrazine were converted to 1,3,4-thiadiazoles in the presence of Vilsmeier reagent and Lawesson's reagent. The influence of the thionation reagent, solvent, temperature and time, in this reaction was discussed. The developed methodology for 1,3,4-thiadiazole synthesis has the advantage of simplicity, ambient reaction conditions, easy purification and good to excellent yield of products.     

含有1H-1,2,4-三唑咪唑[2,1-b]-1,3,4-噻二唑、S-三唑[3,4-b]-1,3,4-噻二唑衍生物的合成及生物活性

合成了18个含有1H-1,2,4-三唑的咪唑[2,1-b]-1,3,4-噻二唑以及S-三唑[3,4-b]-1,3,4-噻二唑的稠杂环衍生物,经元素分析及谱学表征,探讨2,5,6-三取代咪唑[2,1-b]-1,3,4-噻二唑的可能生成机制.对大肠杆菌、绿脓杆菌、枯草杆菌等初步抑菌试验证明,多数化合物表现了较好的抑菌活性.