Thiophen 2-chloro

Benzo[i]thiophene, 6-/-butyl-3-methyl-synthesis, 4, 880 Benzo[6]thiophene, 2-chloro-... 

This method is based on the known reactivity of the 2-position of thiophene so that the desired 2-thiophenethiol may be prepared in good yield by direct substitution of thiophene. 2-Chloro-5-thiophenethiol may also be prepared by this method in 59% yield from 2-chlorothiophene.7... 

Thiophene, bromotetrahydromethyl-pyrolysis, 3, 902 Thiophene, 5-t-butyl-2-methyl-dealkylation, 4, 800 Thiophene, chloro-polymerization, 4, 758 reaction with n-butyllithium, 4, 831 synthesis, 4, 835, 882, 933 Thiophene, 2-chloromercurio-reactions... 

The use of free-radical reactions for this mode of ring formation has received rather more attention. The preparation of benzo[Z)]thiophenes by pyrolysis of styryl sulfoxides or styryl sulfides undoubtedly proceeds via formation of styrylthiyl radicals and their subsequent intramolecular substitution (Scheme 18a) (75CC704). An analogous example involving an amino radical is provided by the conversion of iV-chloro-iV-methylphenylethylamine to iV-methylindoline on treatment with iron(II) sulfate in concentrated sulfuric acid (Scheme 18b)(66TL2531). 

Benzo[6]thiophene, 7-chloro-3-methyl-electrophilic substitution, 4, 798... 

Benzo[b]thiophene, 3-chloro-2-phenyl-synthesis, 4, 116 Benzo[6]thiophene, 2-cyano-synthesis, 4, 921 Benzo[6]thiophene, 3-cyano-synthesis, 4, 922... 

Benzo[b]thiophene-2-carbonyl chloride, 3-chloro-synthesis, 4, 870, 889... 

Benzo[b]thiophene-2,3-quinone, 5-chloro-oxidation, 4, 824 Benzothiophenes, 4, 863-934 biological activity, 4, 911-913 intramolecular acylation, 4, 761 mass spectrometry, 4, 739 metabolism, 1, 242 phosphorescence, 4, 16 reactivity, 4, 741-861 spectroscopy, 4, 713-740 structure, 4, 713-740 substituents reactivity, 4, 796-839... 

Phenanthro[l,2-d][l,2,3]selenadiazole, 10,11 dihydro- H NMR, 6, 348 synthesis, 6, 353 Phenanthro[b]thiophenes synthesis, 4, 914 Phenanthro[4,5-bcd]thiophenes synthesis, 4, 883, 907, 914 Phenanthro[9,10-ej[l, 2,4]triazines synthesis, 3, 434 Phenarsazin synthesis, 1, 561 Phenazine dyes, 3, 196-197 nitration, 3, 177 UV Spectra, 2, 127 Phenazine, 3-amino-2-hydroxy-in colour photography, 1, 374 Phenazine, 1-chloro-nucleophilic substitution, 3, 164-165 5-oxide... 

The reduction of the C— Br and C—1 group moments from 1.10 and 0.90 in bromo- and iodo-benzene to about 0.80 and 0.50 in 2-bromo- and 2-iodo-thiophene has been ascribed to the larger weight of resonance forms such as (8) and (9) in the thiophene series. The chlorine, nuclear, quadrupole, resonance frequencies of chloro-substituted thiophenes are much higher than those of the corresponding benzene derivatives. This has been ascribed to a relayed inductive effect originating in the polarity of the C—S o-bond in thiophenes. The refractive indices, densities, and surface tension of thiophene, alkyl- and halo-thiophenes, and of some other derivatives have been... 

Sulfonation with sulfur trioxide, pyridine sulfur trioxide, pyridine bis-sulfur trioxide, and dioxane sulfur trioxide, which are useful sul-fonating agents for acidophobic substances, have been applied to the thiophene seriesd At room temperature the 2-monosulfonic acid (isolated as the barium salt) is obtained in 86% yield. Higher temperatures lead to a disulfonic acid. However, sulfonation with chloro-sulfonic acid appears to be more convenient,as the sulfonyl chloride obtained can be used directly for the preparation of derivatives. 

Dichlorothiophene can also be used for the synthesis of 3-substituted thiophenes, since it can be smoothly acylated and chloro-methylated in the 3-position, and the halogens can then be readily removed at the appropriate stage. 3-Thenylsuccinic acid (28) has thus been obtained by treating 2,6-dichloro-3-thenylsuccinic acid with sodium amalgam. 2-Bromo-3-thenylbromide can be utilized in a similar way. ... 

With weakly directing — I + M-substituents such as the halogens, the a-directing power of the ring sulfur dominates and substitution appears to occur exclusively in the 5-position. 2-Chloro-, 2-bromo-, and 2-iodo-thiophene are sulfonated both with chlorosulfonic aeid and in the 5-position. In the chlorination of chloro-... 

Such eliminations do not occur with chloro compounds. 2,5-Dichlorothiophene undergoes AlCU-catalyzed sulfonylation with ben-zenesulfonyl chloride. Attempts to extend this reaction to thiophene, 2,5-dimethylthiophene, and 2-chloro-5-iodothiophene resulted in the formation of intractable tars even with other catalysts. Sul-fones of this type are often prepared in much better yields by using thiophenesulfonyl chlorides and benzenes in the Friedel-Crafts reaction. ... 

Radicaloid substitution has not been extensively studied in the thiophene series. Molecular orbital calculations indicate that substitution should occur in the a-position. This has been found to be the case in the Gomberg-Bachmann coupling of diazohydroxides with thiophenes which has been used for the preparation of 2-(o-nitro-phenyl) thiophene, 2-(p-toluyl) thiophene, " " and 2-(p-chloro-phenyl)thiophene. " Coupling in the /8-position has been used for the preparation of 1,3-dimethyl-4,5-benzisothionaphthene (148) from 2-amino-tt-(2,5-dimethyl-3-thienyl)cinnamic acid (149). A recent investigation describes the homolytic phenylation of 2- and 3-phenyl-... 

There is an early report that thiophene reacts at the 3-position in phenylation with benzenediazonium chloride and aluminum trichloride, but in the Gomberg reaction thiophene has been found to substitute mainly at the 2-position both with p-tolyl and with p-chloro-phenyl radicals.Bcnzothiazole is phenylated at the 2-position in low yield by dibenzoyl peroxide a small quantity of the 4-isomcr is also obtained. ... 

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. 

There have been a number of different synthetic approaches to substituted PTV derivatives proposed in the last decade. Almost all focus on the aromatic ring as the site for substitution. Some effort has been made to apply the traditional base-catalyzed dehydrohalogenation route to PTV and its substituted analogs. The methodology, however, is not as successful for PTV as it is for PPV and its derivatives because of the great tendency for the poly(u-chloro thiophene) precursor spontaneously to eliminate at room temperature. Swager and co-workers attempted this route to synthesize a PTV derivative substituted with a crown ether with potential applications as a sensory material (Scheme 1-26) [123]. The synthesis employs a Fager condensation [124] in its initial step to yield diol 78. Treatment with a ditosylate yields a crown ether-functionalized thiophene diester 79. This may be elaborated to dichloride 81, but pure material could not be isolated and the dichloride monomer had to be polymerized in situ. The polymer isolated... 

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