Ether thiophene

Compounds Used fob Coupling Benzene Toluene Nitrobenzene Methyl benzoate Phenol ethers Thiophene Pyridine... 

Benzylic halides and diphenyl ether on heating with sulfur afford ether thiophenes (6), benzothiophenes (7) (the Veronkov reaction) or phenothiazole (8) (Scheme 3). 

Addition of hydrazines to 1,3-difunctional compounds is one of the most common methods employed for the preparation of pyrazoles. For example, several synthesis of pyrazoles have been reported where azide reagents are added to a,P-unsaturated systems. Reactions of trifluoroacetyl enol ether (thiophene) 1 with hydrazines afforded 3-(2-furyl) or 3-(2-thienyl)pyrazoles 2 <05S2744>. A regiospecific one-pot synthesis of trifluoromethyl-substituted heteroaryl pyrazolyl ketones has also been disclosed <05JHC631, 05JHC1055>. 1,3,5-... 

M.K. Madhra, A.K. Salunke, S. Banerjee, S. Prabha, Synthesis and properties of fluorinated polyimides, 2. Derived from novel 2,6-l (5(3 -trifluoromethyl- 7-aminobiphenyl ether)pyridine and 2,5-i> 5(3 -trifluoromethyl-p-aminobiphenyl ether)thiophene, Macromol. Chem. Phys. 203 (9) (2002) 1238-1248. 

Novel diamine monomers such as l,3-bis[3 -trifluoromethyl-4 (4 -aminobenzoxy)benzyl]benzene (TABB) [104], 4,4-bis[3 -trifluoromethyl-4 (4-amino benzoxy)benzyl]biphenyl (TABBP) [104], 2,6-bis(3 -trifluoromethyl-p-aminobiphenyl ether)pyridine (TABP) [105], 2,5-bis(3 -trifluoromethyl-p-aminobiphenyl ether)thiophene (TABT) [105], 4,4 -bis(aminophenoxy)-3,3 -trifluoromethyl terphenyl (ATFT) [106], 2,2 -bis(4 -cyanobiphenyl-4-yloxy)-4,4 -diaminobiphenyl (CBO) [107], PFMB [108], 4,4-bis(p-aminophenoxymethyl)- -cyclohexene (CHEDA) [109], 2,2-bis(4 -aminophenoxy)-4,4,6,6-bis[spiro(2 ,2 -dioxy-l ,l -biphenylyl)] cyclotriphosphazene (geminal diamine, GDA) [110] were synthesized to prepare PEIs. 

CH3CH2)2S. a colourless liquid with an ethereal odour when pure usually it has a strong garlic-like odour b.p. 92°C. Prepared by the action of KHS on ethyl chloride or potassium ethyl sulphate. When heated at 400-500°C it forms thiophene. 

Endo adducts are usually favored by iateractions between the double bonds of the diene and the carbonyl groups of the dienophile. As was mentioned ia the section on alkylation, the reaction of pyrrole compounds and maleic anhydride results ia a substitution at the 2-position of the pyrrole ring (34,44). Thiophene [110-02-1] forms a cycloaddition adduct with maleic anhydride but only under severe pressures and around 100°C (45). Addition of electron-withdrawiag substituents about the double bond of maleic anhydride increases rates of cycloaddition. Both a-(carbomethoxy)maleic anhydride [69327-00-0] and a-(phenylsulfonyl) maleic anhydride [120789-76-6] react with 1,3-dienes, styrenes, and vinyl ethers much faster than tetracyanoethylene [670-54-2] (46). 

The classical structures of pyrrole, furan and thiophene (31) suggest that these compounds might show chemical reactions similar to those of amines, ethers and thioethers (32) respectively. On this basis, the initial attack of the electrophile would be expected to take place at the heteroatom and lead to products such as quaternary ammonium and oxonium salts, sulfoxides and sulfones. Products of this type from the heteroaromatic compounds under consideration are relatively rare. 

Competitive metallation experiments with IV-methylpyrrole and thiophene and with IV-methylindole and benzo[6]thiophene indicate that the sulfur-containing heterocycles react more rapidly with H-butyllithium in ether. The comparative reactivity of thiophene and furan with butyllithium depends on the metallation conditions. In hexane, furan reacts more rapidly than thiophene but in ether, in the presence of tetramethylethylenediamine (TMEDA), the order of reactivity is reversed (77JCS(P1)887). Competitive metallation experiments have established that dibenzofuran is more easily lithiated than dibenzothiophene, which in turn is more easily lithiated than A-ethylcarbazole. These compounds lose the proton bound to carbon 4 in dibenzofuran and dibenzothiophene and the equivalent proton (bound to carbon 1) in the carbazole (64JOM(2)304). 

Friedel-Crafts cyclization benzo[i]thiophenes from, 4, 873 Ethanol, 2-(4-imidazolyl)-synthesis, 5, 484 Ethanol, (S)-l-phenyl-synthesis, 1, 434 Ethanol, 2-phenyl-isochroman synthesis from, 3, 788 Ether, allyl pyridyl... 

D. ci - -Thiabicyclo[4 .. Q]nonan S,S-Dioxide [Benzo[c]thiophene 2,2-dioxide, cis-octahydro-]. A solution of the sulfide (43.0 g., 0.303 mole) in 11. of ether is cooled to 0° and treated dropwise while magnetically stirred with 1.01. of 0.65iV ethereal monoperphthalic acid (0.65 mole). The mixture is kept overnight at 0°, after which time the precipitated phthalic acid is separated by filtration and the filtrate concentrated with a rotary evaporator. Bulb-to-bulb distillation of the residual oil at 0.05-0.1 mm. affords the sulfone as a eolorless liquid (48.5-50 g., 92-95%) (Note 11). This product is crystallized from ether-hexane to give a colorless solid, m.p. 39-41° (Note 12). 

A solution of 85.8 g (0.2 moles) of 3/ -acetoxy-27-norchoIest-5-en-25-one in 500 ml of anhydrous thiophen-free benzene is added to a Grignard solution prepared from 24.3 g (1 g-atom) of magnesium and 149 g (1.05 moles) of freshly distilled methyl iodide in 575 ml of anhydrous ether. The mixture is refluxed for 3 hr and allowed to stand overnight. After cooling to 5° the complex is decomposed by the slow addition of 200 ml of ice water and 400 ml of 50% acetic acid solution, and steam distilled until no more oil passes over. The residual product is filtered, washed with water and dried at 80°. Crystallization from methanol gives 70 g (87%) of cholest-5-ene-3)5,25-diol mp 179.5-181°. The analytical sample melts at 181.5-182.5° [a]o —39° (CHCI3). 

It now seems definitely proved that the thiothiophthene (86) rearranged reversibly to a thiophene (87) under the influence of alkali and not to a thiepin derivative, The dimethyl ether of (87) has been oxidized to 4-methylsulfonyl-2-thiophenecarboxylic acid (88)... 

Procedures have been worked out which increased the yield of 2-bromothiophene to 78% on direct bromination in acetic acid-ether mixtures and to 67% in carbon tetraehlorided With the mild brominating agent, dioxane dibromide, quantitative yields of 2-bromothiophene are obtained. A very convenient procedure for the iodination of thiophenes consists of the acid-catalyzed (HzSOi) reaction with iodine and HIO3, giving 2-iodothiophene in 75% yieldd In contrast to the HgO method, all the iodine is utilized. 

The chloromethylation of 2,6-dimethyl- and 2,5-diethyl-thiophene both with chlorodimethyl ether and formaldehyde and hydrochloric acid gives a mixture of mono- and di-chloromethylated product. " The former reagent gives the larger proportion of monochloromethyl-ated product. " If the chloromethylation is carried out in the presence of zinc chloride, (120) and (121) are obtained. ... 

Nucleophilic substitution has been used for the preparation of many thiophenes. For instance, 2-phenylthio-3,4-dinitro-5-piperidino-thiophene (155) has been prepared " through stepwise reaction of (150) with different nucleophiles. Nitrothienols and derivatives of them have been obtained from halogenated nitrothiophenes. " Allyl ethers have been prepared by the reaction of 5-chJoro-4-nitro-2-acetylthiophene, 3-nitro-2-chlorothiophene, and 2-nitro-3-bromothio-... 

The UV spectrum of 5-phenyl-3 hydroxythiophene is very similar to that of its methyl ether in alcoholic solution, indicating that it exists largely in the enol form in this solvent. The same coincidence of the wavelength maxima was also obtained for 5-phenyl-2-hydroxy-thiophene and its methyl ether. In chloroform solution, the maxima were shifted toward longer wavelengths, suggesting that the tautomeric equilibrium in this solvent is displaced more toward the keto form. ... 

Two different sets of experimental conditions have been used. Buu-Hoi et al. and Hansen have employed the method introduced by Papa et using Raney nickel alloy directly for the desulfurization in an alkaline medium. Under these conditions most functional groups are removed and this method is most convenient for the preparation of aliphatic acids. The other method uses Raney nickel catalysts of different reactivity in various solvents such as aqueous ammonia, alcohol, ether, or acetone. The solvent and activity of the catalyst can have an appreciable influence on yields and types of compounds formed, but have not yet been investigated in detail. In acetic anhydride, for instance, desulfurization of thiophenes does not occur and these reaction conditions have been employed for reductive acetylation of nitrothiophenes. Even under the mildest conditions, all double bonds are hydrogenated and all halogens removed. Nitro and oxime groups are reduced to amines. 

From simple ethers of the thiophene series, such as (230), aliphatic ethers such as (231) have been obtained by desulfurization in ether. ... 

In this way isopentyl pentyl ether, heptyl pentyl ether, and 4,5-bis-methoxymethyI-2,2-dimethylheptane were also prepared from the appropriate thiophene derivatives. ... 

A solution of 2 grams of A -19-norandrosten-3,17-dione and 0.4 gram of pyridine hydrochloride in 50 cc of benzene free of thiophene was made free of moisture by distilling a small portion 4 cc of absolute alcohol and 4 cc of ethyl orthoformate were added and the mixture was refluxed during 3 hours. 5 cc of the mixture were then distilled and after adding an additional 4 cc of ethyl orthoformate the refluxing was continued for 2 hours longer. The mixture was evaporated to dryness under vacuum and the residue was taken up in ether, washed, dried and evaporated to dryness. The residue was crystallized from... 

A mixture of 10.3 g of thiophene-20 -methylacetic acid [prepared by process of Bercot-Vat-teroni, et al.. Bull. Soc. Chim. (1961) pp. 1820-211, 11.10 g of benzoyl chloride and a suspension of 23.73 g of aluminum chloride in 110 cc of chloroform was allowed to stand for 15 minutes and was then poured into a mixture of ice and hydrochloric acid. The chloroform phase was extracted with a 10% aqueous potassium carbonate solution and the aqueous alkaline phase was acidified with N hydrochloric acid and was then extracted with ether. The ether was evaporated off and the residue was crystallized from carbon tetrachloride to obtain a 54% yield of 5-benzoyl-thiophene-20 -methylacetic acid melting at 83°C to 85°C. The... 

The mixture was cooled in ice and a solution of 2-chloro-3-chloromethy I thiophene (8.8 mmol) in dry tetrahydrofuran was added. The mixture was heated at 70°C for 3 hours and allowed to stir at room temperature overnight. The solvent was removed under vacuum and the residue stirred with dry ether (200 ml). The ether solution was filtered through Celite and saturated with hydrogen chloride gas to precipitate an oil which was solidified by trituration with ether and ethyl acetate. The solid product was collected and recrystallized from a mixture of acetone and diisopropyl ether to give the product, melting point 168°C to 170°C. 

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