A Novel and Expedient Approach to New Thiazoles, Thiazolo[3,2-a]pyridines, Dihydrothiophenes, and Hydrazones Incorporating Thieno[2,3-b]thiophene Moiety

This paper reports details about the synthesis of a series of novel functionalized symmetrical bis-heterocyclic compounds containing a thieno[2,3-b]thiophene motif. Bis-thiazole derivatives 2, 3a-c and thiazolo[3,2-a]pyridine derivatives 4a-c are achieved. The hitherto unknown dihydrothiophene derivatives 6a-dvia bis-pyridimium salt 5 are obtained. Additionally, the novel hydrazonothieno[2,3-b]thiophene derivatives 10a-c are obtained via bis-tosylacetylthieno[2,3-b]thiophene derivative 9. All compounds are characterized by (1)H-, (13)C-NMR, GCMS, IR, and UV-vis spectrometry. These compounds represent a new class of sulfur and nitrogen containing heterocycles that should also be of interest as new materials.     

A Facile and Convenient Synthesis of some Novel Hydrazones, Schiff's Base and Pyrazoles Incorporating Thieno[2,3-b]thiophenes

A facile and convenient synthesis of some novel hydrazones, schiff's base and pyrazoles from thieno[2,3-b]thiophene derivatives 1 have been achieved in high yields assisted by microwave and classical methods. The structures of all the title compounds have been elucidated by elemental analysis, IR, MS, (1)H-NMR and (13)C-NMR. Generally, these findings represent a new class of sulfur and nitrogen moieties that should also be of interest as new materials.     

Synthesis and Antimicrobial Studies of Some Novel Bis-[,,]thiadiazole and Bis-thiazole Pendant to Thieno[2,3-b]thiophene Moiety

The synthetic utility of 3,3'-(3,4-dimethylthieno[2,3-b]thiophene-2,5-diyl)bis (3-oxopropanenitrile) (1) in the synthesis of some novel bis-[1,3,4-thiadiazole] 6a-g and bis-thiazole 10 and 13 derivatives with thieno[2,3-b]thiophene moiety is reported. Antimicrobial evaluation of some selected examples from the synthesized products was carried out and showed promising results.     

2-Arylamino-thiophen-3-carbonsäurederivate

2-Arylamino-thiophene-3-carboxylic Acid Derivatives The title compounds 3 are synthesized by reaction of 2-amino-thiophene-3-carboxylic acid derivatives 1 with anilines. The nucleophilic 5-position in 3 allowed the synthesis of 5-aryliden-Δ³-thiolen-2-one-imines 5 , 6 and the oxidative coupling to yield the azo compound 7 . 1-Aryl-thieno-[2,3-d]pyrimid-4-ones 9 , the thieno[2,3-b]chinolin-4-one 10 and the 4-chloro thieno[2,3-b]chinolines 10 , 11 can be obtained from 3 .     

两个含硫杂环化合物的合成及结构表征

报道了两个新的含硫杂环化合物萘并［２，１－ｂ］噻吩和萘并［２，１－ｄ］噻吩的合成，用元素分析、红外光谱、核磁共振谱及质谱表征产物的结构。     

Synthesis of Acenaphtho[3, 4-b]thiophene: An Aceanthrylene Isoster

The synthesis of a novel thiophene isoster of aceanthrylene is reported. The sequence involves, a newly observed regiospecific condensation of oxalylchloride to naphtho[2,3-b]thiophene. Reduction of the quinone and dehydrogenation gave the title compound in 28% overall yield. The proton nmr signals of the title compounds were assigned on the basis of COSY and NOE difference spectroscopy. Its isolectronic nature with aceanthrylene is seen in the similarity of the UV spectra.     

Thieno[3,2-b]thiophene as π-bridge at different acceptor systems for electrochromic applications

Benzoselenadiazole, quinoxaline and thieno[3,2-b]thiophene are the units preferred in conducting polymers due to their electrochemical properties. There are no reports in the literature on polymers containing both moieties. In this study, novel benzoselenadiazole, quinoxaline and thieno[3,2-b]thiophene based monomers; 4-(3a,6a-dihydrothieno[3,2-b]thiophen-2-yl)-7-(thieno[3,2-b]thiophenyl)benzo[c][1,2,5]selenadiazole (BSeTT) and 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-dibromo-2,3-dihydroquinoxaline (QTT) were synthesized via Stille Coupling and polymerized electrochemically. These polymers were characterized in terms of their spectroelectrochemical and electrochemical properties by cyclic voltammetry and UV–Vis–NIR spectroscopy. Spectroelectrochemistry analysis of PBSeTT revealed an electronic transition at 525 nm corresponding to π–π* transition with a band gap of 0.93 eV whereas PQTT revealed electronic transitions at 440 and 600 nm corresponding to π–π* transitions with a band gap of 1.30 eV. Electrochromic investigations showed that PBSeTT has gray color PQTT switching between green and gray. Switching time of the polymers was evaluated by a kinetic study upon measuring the percent transmittance (%T) at the maximum contrast point.     

2-Mercapto-4,6-disubstituted nicotinonitriles: versatile precursors for novel mono- and bis[thienopyridines]

A series of novel thieno[2,3-b]pyridines were prepared from the reaction of the appropriate bromoacetylbenzofurans or bromoacetylbenzothiazole with the corresponding pyridinethione derivatives in ethanolic sodium ethoxide at reflux. Moreover, new bis(thieno[2,3-b]pyridine) derivatives have also been synthesized by the reaction of the appropriate bis-bromoacetyl derivatives with the corresponding pyridinethiones in the presence of sodium ethoxide. Attempts to synthesize the target bis(thieno[2,3-b]pyridine) derivatives by bis-alkylation of the corresponding (thieno[2,3-b]pyridin-2-yl)(hydroxyphenyl)methanone with the appropriate dihaloalkanes using a mild base were unsuccessful.     

3-Amino-furo[2.3-b]pyridine

3-Amino-furo[2,3-b]pyridines The reaction of the 3-cyano-2-pyridones 1 with α-halogen carbonyl compounds yields 2-alkoxy-pyridines 2 which can be cyclized in the presence of sodium ethoxide to form 3-amino-furo[2,3-b]pyridines 3 . From 4,6-dimethyl-3-cyano-2-pyridone, mixtures of N- and O-alkylated compounds are obtained which by cyclization in addition to 3-amino-furopyridines 6 yield indolizinones 7 . From 3 , pyridofuro-pyrimidines 9 can be synthesized.     

Synthesen mit 1,3-Dithietanen. XIV. Ringumwandlungen von substituierten Dihydropyrazolo[5, 1-b]thiazolcarbonsäureestern

Syntheses with 1,3-Dithietanes. XIV. Ring Transformations of Substituted Dihydropyrazolo [5,1-b]thiazolecarboxylates Dihydropyrazolo[5,1-b]thiazolecarboxylates 2 react with aliphatic amines to give dihydrothiazolo[2,3-g][1,2,4]triazepinecarboxylates 4 . Compounds 2c , d and o-phenylenediamine, o-amino-phenols or o-amino-thiophenol afford substituted ethyl benzimidazol-, benzoxazol- or benzothiazol-2-yl-acetates 6 . Hydrazine hydrate and compounds 2 yield derivatives of ethyl pyrazolidin-4-yliden-4-thiazoline-5-carboxylates 8 .     

3-Amino-thieno[2,3-b]furane und 3-Amino-thieno[3,2-b]furane

3-Amino-thieno[2,3-b]furans and 3-Amino-thieno[3,2-b]furans The O-alkylation of 2-hydroxy-thiophene-3-carbonitriles ( 1 ) with α-bromocarbonyl compounds yields the 2-alkoxy-thiophene-3-carbonitriles ( 2a–f ) among them 2-benzoylmethoxy-thiophene-3-carbonitriles ( 2a–c ) which undergo Thorpe-Ziegler-cyclization to form the 3-amino-2-benzoyl-thieno[2,3–b]furans ( 3 ) in low yields. The 2-acyl-3-amino-thieno[3,2–b]furans and ethyl 3-amino-thieno[3,2–b]furan-2-carboxylates ( 6 ) are synthesized in similar manner from 3-hydroxy-thiophene-2-carbonitriles ( 4 ) and α-halogencarbonyl compounds via 3-acylmethoxy- and 3-ethoxycarbonylmethoxy-thiophene-2-carbonitriles ( 5 ) with high yields.     

Chemistry of the Hexahydropyrrolo[2,3-b]indoles: configuration, conformation, reactivity, and applications in synthesis

The stereoselective formation of 2-endo-substituted hexahydropyrrolo[2,3-b]indoles from 2-substituted tryptamine derivatives, especially tryptophan, is discussed. Parallels are drawn with the formation of related heterocyclic systems, such as the hexahydrofurano[2,3-b]benzofurans, in which the thermodynamic preference of a substituent at the 2-position is also for the endo-configuration. Functionalization of tryptophan-derived hexahydropyrroloindoles at positions 2-, 3-, and 3a- is discussed with special emphasis on the 2-position, at which both radical and nucleophilic reactions take place preferentially on the endo-face of the diazabicyclo[3.3.0]octane system. The kinetic and thermodynamic preference for the 2-endo-position is considered in terms of the minimization of torsional strain, and parallels are drawn to the Woerpel model for the reactivity of analogous five-membered cyclic oxacarbenium ions. The use of the tryptophan-derived hexahydro[2,3-b]pyrroloindoles in the stereocontrolled synthesis of amino acids and alkaloids is presented.     

Quinoxaline derivatives as long wavelength photosensitizers in photoinitiated cationic polymerization of diaryliodonium salts

The present paper is focused on visible light initiated cationic polymerizations. Photoinitiated polymerization of representative vinyl ether and oxirane monomers using two quinoxaline derivatives; namely (2-(2,3-dihydrobenzo [b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b]-[1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7yl) quinoxaline) (DBQEd) and 2,3,5,8-tetra(thiophen-2-yl)quinoxaline (TTQ) are studied. Novel dyes based on the quinoxaline skeleton are employed as efficient photosensitizers in cationic photopolymerizations. Polymerizations were initiated at room temperature upon irradiation with long-wavelength UV and visible lights in the presence of diphenyliodonium hexafluorophosphate (Ph₂I⁺PF₆^?). The progress of the polymerizations was monitored by optical pyrometry (OP). Solar irradiation is also employed to carry out the cationic polymerization of a diepoxide monomer in the presence of air.     

3,4-二甲基-2,5-二甲酸乙酯噻吩[2,3-b]并噻吩选择性酰肼化

以乙酰丙酮和二硫化碳为原料合成出3,4-二甲基-2,5-二甲酸乙酯噻吩,它在不同溶剂中与过量水合肼反应,得到不同的产物:在乙醇中回流24 h,以66%的产率得到单酰肼化产物3,4-二甲基-噻吩[2,3-b]并噻吩-2-甲酸乙酯-5-甲酰肼;以DMF为溶剂80℃反应得到的主要产物是3,4-二甲基-2,5-噻吩[2,3-b...     

2,3-Heterokondensierte Thiophene aus substituiertem 2-Aminothiophen-3-thiol

2,3-Heterocondensed Thiophenes from Substituted 2-Aminothiophen-3-thiole Ethyl 5-amino-4-mercapto-3-methyl-thiophen-2-carboxylate ( 2 ), obtainable from the appropriate thienylthiocyanate 1 by reduction, undergoes reactions in analogy to the 2-aminobenzenthiole. Thus, with formic acid or trimethylorthoacetat the thieno [2,3-d]thiazoles 4 and 5 are formed. Aromatic aldehydes yield the thieno[2,3-d]thiazolines ( 6 ) which can be dehydrogenated by sulphur to form 9 . From carbon disulfide and 2 the thieno[2,3-d]thiazol-2-thione ( 7 ) is formed. With phenacylbromide or ethyl bromoacetate 2 can be converted into the thieno[3,2-b] thiazine derivatives 11 or 12 . Diazotation of 2 yields the thieno[2,3-d]1,2,3-thiadiazole derivative ( 14 ).     

吡啶并吡嗪/咪唑杂环化合物的合成研究

以2,3-二氨基吡啶或2,3,5,6-四氨基吡啶盐酸盐等为原料合成了吡啶并吡嗪、吡啶并咪唑及吡啶并二咪唑氮杂环衍生物。探讨了反应条件对产物收率的影响,初步确定了优化反应条件。对2,3-二甲基吡啶并吡嗪及2,3-二乙基吡啶并吡嗪的合成,氯化铵-甲醇体系具有明显的催化效果。使用4,5-二羟基咪唑烷-2-酮代替乙二醛与2,3-二氨基吡啶反应,可显著提高吡啶并吡嗪的合成收率;对于吡啶并咪唑和2-甲基吡啶并咪唑的合成,以2,3-二氨基吡啶与原甲酸三乙酯或原乙酸三甲酯为原料,在磷钼酸催化下反应,收率达50%以上;对于吡啶并[2,3-b:5,6-b']二咪唑和2,6-二甲基吡啶并[2,3-b:5,6-b']二咪唑的合成,分别以2,3,5,6-四氨基吡啶盐酸盐与原甲酸三乙酯和原乙酸三甲酯为原料在磷钼酸催化下反应,收率可达68.7%和66.5%。     

2,6-双-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑吡啶类衍生物的合成及抗菌活性

芳香羧酸酯化、肼解、成盐、环化成3-芳基-4-氨基-5-巯基-1,2,4-三唑与2,6-吡啶二甲酸在相转移催化剂四丁基碘化铵和POCl3作用下,高产率制得8种标题化合物,并利用IR、1HNMR、MS和元素分析对目标化合物的结构进行了表征.初步的抗菌实验表明,部分目标化合物表现出较好的抑菌活性.     

The effect of co-initiator structure on photoinitiating efficiency of photoredox couples composed of quinoline[2,3-b]-1H-imidazo[1,2-a]pyridinium bromide and phenoxyacetic acid or N,N-dimethylaniline derivatives.

Summary  Two groups of electron donors (phenoxyacetic acid derivatives, PAADs, and the family of N,N-dimethylaniline derivatives DMADs) in combination with quinoline[2,3-b]-1H-imidazo[1,2-a]pyridinium bromide (QIPB) were applied as photoinitiator for free radical polymerization induced with UV emission of an argon-ion laser (351 and 361 nm). Analysis of the data obtained for the initial time of photoinitiated polymerization indicates that both, the rate of electron transfer process between QIPB and tested co-initiators as well as the structure of obtained free radical can affect the overall photoinitiation ability of tested photoredox pairs.     

Synthesis of 2 and 6-triazolylthiazolo[4,5-b]quinoxaline derivatives and their application as fluorescent disperse dyes

Synthesis of 2-triazolylthiazolo[4,5-b]quinoxaline derivatives was achieved by diazotisation of 2-aminothiazolo[4,5-b]quinoxaline and its 6-nitro derivative using orthophosphoric acid and sodium nitrite with a trace of nitric acid, coupling with suitable aromatic amines and subsequent cyclisation of the resulting ortho amino azo compounds. Diazotisation of 2,6-diaminothiazolo[4,5-b]quinoxaline with concentrated hydrochloric acid and sodium nitrite and subsequent coupling and cyclisation resulted in the 6-triazolylthiazolo[4,5-b]quinoxaline derivatives. These compounds were applied on polyester as fluorescent disperse dyes.     

咪唑并[2,1-b]噻唑衍生物的合成及生物活性进展

根据环上取代基的不同咪唑并[2,1-b]噻唑衍生物具有多种多样的生物活性。通过对咪唑并[2,1-b]噻唑衍生物合成方法的不同进行分类,综述了近年来咪唑并[2,1-b]噻唑衍生物的合成及其生物活性,结果表明在咪唑并噻唑环上引入药理活性基团会增强其生物活性。咪唑并[2,1-b]噻唑环一般由Hanzstch方法合成,近年来也出现了一些新的合成方法,如Sonogashira、Suzuki反应和金属催化芳基化,对这些新方法合成咪唑并噻唑环及其衍生物也进行了综述。