IN-SITU SYNTHESES OF ALKYLLITHIUM COMPOUNDS UNDER ULTRASONIC IRRADIATION

Abstract

The syntheses of organometallics such as alkyllithium compounds are performed. Furan and thiophene derivatives were prepared. Parameters which influence the yield have been optimized. The more important were the physical states of lithium and its sodium content and the nature of the substrate.     

Complex Formation of Cyclodextrins with Various Thiophenes and their Polymerization in Water: Preparation of Poly-pseudo-rotaxanes containing Poly(thiophene)s

Cyclodextrins (α-CD, β-CD and 2,6-di-O-dimethyl-β-CD (DM-β-CD)) were found to form inclusion compounds with thiophenes (thiophene (T), bithiophene (2T)) in water and in crystalline states. The structures of α-CD–T, β-CD–2T, and DM-β-CD–2T inclusion complexes were determined by X-ray crystallography. DM-β-CD forms a 1:1 cage type complex with 2T. In contrast, β-CD formed 2:3 (CD:guest) complexes with thiophene and α-CD formed 2:3 complexes, both of the channel type. These inclusion complexes were found to polymerize by FeCl₃ in the inclusion compounds in water. The products were formed poly-pseudo-rotaxane between cyclodextrins and poly(thiophene) characterized by IR, ¹H-NMR and ¹³C CP/MAS NMR. The molecular weights of the poly-pseudo-rotaxanes with poly(thiophene) were determined by the MALDI-TOF mass spectra to be 3000–5000. In comparison between poly-pseudo-rotaxane (DM-β-CD–poly(thiophene)), authentic poly(thiophene) and the washed DM-β-CD–poly(thiophene) which was washed with DMF to dethread DM-β-CD, these poly-pseudo-rotaxane was characterized by Raman, UV–vis and fluorescence spectra. The maximum emission band of DM-β-CD–poly(thiophene) shifted to a shorter wavelength. The hypsochromic shift was derived from poly-pseudo-rotaxane with DM-β-CD.     

HIGH TEMPERATURE REACTIONS OF HYDROGEN SULFIDE AND THIOLS WITH ORGANIC COMPOUNDS

Abstract

The high temperature reaction of hydrogen sulfide with chloro- and bromosubstituted aromatic and heteroaromatic compounds is a convenient method for synthesis of the corresponding thiols and sulfides. The reaction of hydrogen sulfide with ortho-dihalosubstituted aromatic compounds may be directed toward the formation of thianthrene or dibenzo thiophene and their derivatives. The high temperature reaction of thiophenol with chloro- and bromoderivatives of aromatic and heteroaromatic compounds affords the corresponding mixed sulfides. The reaction with ortho-substituted halogen derivatives leads to formation of the sulfur heterocycles of the thianthrene, thioxanthene and dibenzothiophenene series.

The high temperature reaction of hydrogen sulfide with vinyl chloride gives vinylthiol and thiophene. Hydrogen sulfide initiates pyrolytic transformations of thiophene, aniline and benzaldehyde into dithienyls, 5.10-dihydrophenazine and stilbene, respectively. The reaction mechanism has been discussed.     

Synthesis and antimicrobial evaluation of some novel dithiolane,thiophene, coumarin,and 2-pyridone derivatives

Novel 2-cyano-N-[1-(naphtha-2-yl)ethylidene] acetohydrazide 1 was utilized as key intermediate for the synthesis of some new dithiolane, thiophene, coumarin, 2-pyridone, and other related products containing a hydrazide moiety. Newly synthesized compounds were characterized by elemental analyses and spectral data (IR, ¹H NMR and mass spectra). The antimicrobial activity of the synthesized compounds was evaluated.     

A One-Pot Synthesis of Thiophenes and Their Annulated Derivatives With Potential Pharmaceutical Interest

The reaction of 2-cyanomethylene benzo[d]imidazole (1) with carbon disulphide in basic DMF solution gave the di-potassium disulphide salt (3). The reaction of the latter with the α -halocarbonyl compounds 4 and 13 afforded the thiophene derivatives 5 and 14, respectively. The latter products were used to synthesize annulated products with potential pharmaceutical interest.     

SYNTHESE DE DERIVES DU THIOPHENE SUBSTITUES EN POSITION 2 ET 5

Abstract

Six new potentially active drugs derivatives of 2.5-disubstituted thiophene are synthesized by a multistep procedure based on the reactivity of a sulfur carbanions: compounds 2, 3, 4 and 8 are symmetrical, substituted by identical functional groups, and compounds 10, 14 are non symmetrical.     

New isothiocyanato liquid crystals containing thieno[3,2-b]thiophene central core

New isothiocyanato liquid crystal (LC) materials based on thieno[3,2-b]thiophene core have been synthesised and characterised. Their mesomorphic and physical properties were evaluated. The results indicate that most of the new compounds exhibit only enantiotropic smectic A phases with high clearing points, and the difluorinated compounds (A3 and A6), in particular, also display a stable nematic phase with low melting points. Compared with the corresponding biphenyl and thiophene-phenyl analogues, these thieno[3,2-b]thiophene-based compounds possess increased birefringence (the highest value found to be 0.40) and mesogenic phase intervals. These new thieno[3,2-b]thiophene-based LCs exhibit a high birefringence and a high clearing point and are of potential use as components of high birefringence mixtures.     

NOVEL HALOGENATION OF THIOPHENES WITH BENZENESELENINYL CHLORIDE AND ALUMINUM HALIDE

Abstract

In the presence of aluminum halide, benzeneseleninyl chloride is an efficient Regioselective halogenating reagent for heterocyclic compounds such as thiophene, 2methylthiophene. 3-methylthiophene, 2,5-dimethylthiophene, and furan. In the case of pyrrole, no halogenated product was obtained. A plausible reaction mechanism involving a positive halogen intermediate is proposed.     

Utility of 3-Chlorobenzothiophene-2-Carbonylisothiocyanate for the Synthesis of Some Novel Biheterocycles of Expected Biological Activity

The behavior of 3-chlorobenzothiophene-2-carbonylisothiocyanate 2 towards nitrogen nucleophiles such as primary amines, substituted hydrazines, aryl hydrazines, glycine, anthranilic acid; sulfur nucleophiles such as thioglycolic acid; and oxygen nucleophiles such as substituted phenols has been investigated and found that it proceeds via isothiocyanate heterocyclization to furnish noncondensed heterocyclic compounds containing thiourea, triazole, oxazole, thiazole, and benzoxazole nuclei besides the benzo[b]thiophene nucleus. The structures of the newly synthesized compounds were elucidated on the basis of IR, ¹H NMR, and mass spectral data of the compounds, and they have been screened for antimicrobial, analgesic, and anti-inflammatory activities.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis and Evaluation of Polyfunctionally Substituted Heterocyclic Compounds Derived from 2-Cyano-N-(5-pentadecyl-1,3,4-thiadiazol-2-yl)acetamide

Reaction of 5-pentadecyl-1,3,4-thiadiazol-2-amine 2 with ethyl cyanoacetate gave 2-cyano-N-(5-pentadecyl-1,3,4-thiadiazol-2-yl)acetamide 3, which was used to synthesize different heterocyclic derivatives with coumarin, pyrazole, thiazole, pyridine, pyrimidine, and thiophene rings. Propoxylation of these compounds by using 5 mol of propylene oxide produced nonionic surface active agents. Antimicrobial and surface activities were evaluated.     

Transformation of Thiophene Derivatives into Compounds of Other Series

Abstract

Thiophene derivatives undergo some reductive transformations giving rise to numerous aliphatic, carbocyclic as well as to other heterocyclic systems. One type of these transformations includes as the first step the action of a reducing agent on thiophene compounds giving dihydro- or tetrahydrothiophene derivatives, and subsequent cleavage of the latter with another agent. While the use of catalytic hydrogenation in the thiophene series is essentially limited, there are now other methods - electrochemical reduction and ionic hydrogenation-leading to dihydro- and tetrahydrothiophenes, respectively. The other approach which is more widely used includes formally one-step reductive cleavage of thiophene rings with the scission of one or both C-S bonds. The most important methods of this type are reductive desulfurization with Raney nickel and the reductive cleavage by the action of alkali metals in liquid ammonia. In these processes thiophene plays the role of a “building block” the aromatic nature of which allows comparatively simple construction of a carbon skeleton bearing necessary substituents, the latter are retained or modified under the conditions of reductive cleavage; moreover during the cleavage new substituents may be originated creating exceptionally rich synthetic possibilities.     

Novel Bis-arylPheDOT Synthons for Electrochromic Polymers

Two terthiophenes incorporating the synthon 3,4-(1,2-phenylenedioxy)thiophene (PheDOT) have been developed. Specifically, 2,5-bisthienyl-3,4-(1,2-phenylenedioxy)thiophene (BTh-PheDOT 1) and 2,5-bisethylenedioxythienyl-3,4-(1,2-phenylenedioxy)thiophene (BEDOT-PheDOT 2) were electropolymerized to form electroactive polymer films (P1 and P2) that switched between two highly colored states with the more electron-rich EDOT derivative P2 observed to switch at a lower potential. Additionally, both P1 and P2 displayed moderate to low optical bandgaps of 1.8 and 1.6 eV, respectively. Crystal structures of BTh-PheDOT showed the monomer to be nearly planar with π -stacking observable between monomers. These findings demonstrate the potential of PheDOT as an electroactive synthon for the formation of well-ordered systems.     

An Efficient Synthesis of New Substituted Spiro Pyrazolethieno,Pyrimidinethieno, and Benzodiazepinethieno Pyridazine Derivatives with Biological Activities

3-Ethyl 2-amino-4-methyl-5-phenyl thiophene carboxylate 1 was used as a starting material to synthesize 2a,b via coupling with malononitrile or acetyl acetone, respectively. When heated, under reflux in sodium ethoxide solution, 2a,b give 3a,b. On the other hand, when compounds 3a,b were heated under reflux in ethanol with hydrazine hydrate, thiourea, or 1,1-phenylenediamine hydrochloride and a catalytic amount of piperidine 4a,b, 5a,b and 6a,b, were produced, respectively. The new compounds were tested for their antimicrobial activity. Compounds 2a–6b showed antibacterial activities, and 2a,2b and 4b showed antifungal activities.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Studies on 2-Aminothiophenes: Synthesis,Transformations, and Biological Evaluation of Functionally-Substituted Thiophenes and Their Fused Derivatives

Abstract

Heterocyclic enamines1 reacted with ethyl acetoacetate to afford the corresponding amide derivatives2. Treatment of2 with carbon disulphide yielded the dipotassium salts3which reacted in-situ with a variety of α -haloketones to give the respective substituted thiophenes5,8, and13. The reactivity of the latter products towards various chemical reagents was studied to yield their fused thiophene derivatives7,10,12, and14, respectively. Some representative compounds were tested for antimicrobial activity.     

Regioselective synthesis of 2,4-disubstituted thiophenes

A highly regioselective route was established to 2-aryl-, 2-cyclohexyl-, and 2-(2-arylethyl)4-alkylthiophenes, which are potential candidates as liquid crystalline compounds of low viscosity. The key synthetic intermediates, 2-substituted-4-(chloromethyl)thiophenes 6, 14, and 20 were prepared respectively from the reactions of β, γ-epoxycarbonyl compounds 5, 13, and 19 with Lawesson's reagent in the presence of a catalytic amount of p -toluenesulfonic acid. The epoxycarbonyl compounds were obtained from the TiCl₄-mediated reactions of 2-(chloromethyl)-3-(trimethylsliyl)propene (10) with acid chlorides followed by epoxidation with m-chloroperoxybenzoic acid, or from prior epoxidation followed by oxidation with pyridinium dichromate of homoallylic alcohols 3. The homoallylic alcohols 3 were synthesized from the reactions of 2-(chloromethyl)-3-(trichlorosilyl)propene (2) with aldehydes in N, N-dimethylformamide. Copper (I) catalysed cross-coupling reactions of 2-substituted-4-(bromomethyl)thiophenes (which were prepared by transhalogenation of 2-substituted-4- (chloromethyl)thiophenes with NaBr in acetone) with Grignard reagents afforded 2,4-disubstituted thiophenes. Using this method, eleven 2,4-disubstituted thiophenes were synthesized and their potentials as liquid crystalline compound of low viscosity were examined. The synthesized 2-(4-cyanophenyl)-4-pentylthiophene was observed to have a lower melting point than the corresponding 2,5-disubstituted thiophene. This observation is consistent with the expectation from the basis of molecular linearity which can affect the viscosity and/or melting point of crystalline compounds.     

Benzo[b] thiophene derivatives. XIV. Derivatives of naphtho[1,8-c] thiophene

In the course of our efforts to synthesize the sulfur isostere of lysergic acid, we have prepared a number of derivatives of the little known naphtho[1,8-bc]thiophene ring system. Two previously reported compounds, 2-bromo-3,4-dihydro-5-oxo-5H-naphtho[1,8-bc]thiophene and 2-bromo-5-hydroxy-3,4-dihydro-5H-naphtho[1,8-bc] thiophene have been obtained pure for the first time, and the syntheses and spectral data of eighteen new compounds are presented. The new compounds include alcohols, ketones, and halogen derivatives of partially reduced naphtho-[1,8-bc] thiophene, as well as the sulfones of several of these compounds.     

两个三(邻溴苄基)锡羧酸酯的合成、结构及抗肿瘤活性

合成了2个有机锡羧酸酯化合物三(邻溴苄基)锡噻吩2-甲酸酯(1)和三(邻溴苄基)锡肉桂酸酯(2).通过元素分析、红外光谱、核磁共振谱(1H、13C和119Sn)、差热分析、X射线单晶衍射方法对1和2进行了结构表征,对其结构进行了量子化学从头计算.结果 显示,化合物1和2均为单锡核结构,锡原子均为四配位的畸变四面体构型....     

Crystal structure and reactivity of 2-chloro-3,5-dinitrothiophene and of 2-phenylsulphonyl-3,5-dinitrothiophene with nucleophiles

The geometry obtained by a crystal structure determination of the title compounds, as compared with that of the analogous benzene derivatives, along with results of ab initio calculations, is used to interpret the different S_NAr reactivities in some thiophene and benzene compounds. The smaller rotation of the nitro groups with respect to the aromatic rings observed in thiophene derivatives should be considered a relevant factor in the higher reactivity in the thiophene series.     

A Convenient One-Pot Synthesis of Some New 3-(2-Phenyl-6-(2-thienyl)-4-pyridyl)hydroquinolin-2-ones Under Microwave Irradiation and Their Antimicrobial Activities

A series of 3-(2-phenyl-6-(2-thienyl)-4-pyridyl)hydroquinolin-2-ones 4a–o were synthesized in high yields by a one–pot cyclocondensation reaction under Kröhnke's reaction conditions using 2-chloro-3-formyl quinoline 1a–c, 2-acetyl thiophene 2, and various N-phenacylpyridinium bromides 3a–e in a mixture of ammonium acetate and acetic acid by microwave irradiation. All the compounds have been characterized by elemental analysis, FT-IR, ¹H NMR, and ¹³C NMR spectral analysis. These compounds have been screened for their antimicrobial activities.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.