Spectroscopic study of organosilicon derivatives of thiophene

Substituents in disubstituted thiophenes have an additive effect on the chemical shifts of the ring hydrogen atoms. The electronic effects of organosilicon substituents are transmitted via inductive and conjugation (d-p interaction) mechanisms. The effect of d-p interaction in the Si-ring bond is absent for Si(OC₂H₅) and SiF₃ substituents.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenli, No. 11, pp. 1483–1488, November, 1972.     

Spectroscopic study of organosilicon derivatives of thiophene

The IR spectra of organosilicon derivatives of thiophene were investigated. A comparison of the results with the literature data made it possible to isolate the characteristic absorption bands of the substituted thiophene ring and to reveal some regularities in the IR spectra of thienylsilanes. The inductive constants of substituted thienyl groups were calculated from the experimental(Si-Cl) values. An analysis of the values shows that electron-donor substituents X lower the acceptor capacity of the thienyl substituent as a whole, while electron-acceptor substituents increase it.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 477–481, April, 1974.     

Spectroscopic study of organosilicon derivatives of thiophene

It is shown that the chemical shifts of hydrogen atoms in the 3 position of the thiophene ring in the PMR spectra of 2-substituted thiophenes are linearly associated with the Hammett _n substituent constants. On the basis of this, it was concluded that silyl substituents in 2-silylthiophenes have electron-acceptor character. It was established that the degree of d–p conjugation between the d orbitals of the silicon atom and the p electrons of the thiophene ring depends on the nature of the other three substituents attached to the silicon atom. The data from the IR spectra of organosilylthiophenes that contain a Si-H bond also attest to the presence of d–p conjugation in these compounds.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 911–915, July, 1972.     

Functional thiophene derivatives

The thiocyanation of 5-acylaminothiophenes gives 4-thiocyanato derivatives, the intramolecular cyclization of which gives 2-acylaminothieno[2,3-d]thiazoles.See [1] for communication VIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1204–1205, September, 1974.     

Functional derivatives of thiophene

5-Tosylamino-2,3-dialkylthiophenes, which are alkylated to the corresponding 5-alkyl (tosyl)-amino derivatives, were synthesized from 2-amino-3-carbethoxy-4,5-dialkylthiophenes by tosylation and subsequent decarboxylation.See [1] for communication XV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 204–206, February, 1977.     

Functional derivatives of thiophene

A method is proposed for the synthesis of isatin analogs — 4,5-dioxothieno[2,3-b] pyrroles and 5,6-dioxothieno[3,2-b]pyrroles — by reaction of oxalyl chloride with amino-substituted α-amino- and Β-aminothiophene. The thiosemicarbazones of 4-ary1-5,6-dioxothieno[3,2-b]pyrroles were synthesized. n]mis|See [1] for communication X.     

Organodimagnesium derivatives of thiophene

It was established that 2,5-dibromo-3-R-4-arylthiophenes form organodimagnesium compounds in ether with the accompaniment of dibromoethane. It is shown that because of steric hindrance, only 2-ethoxalyl-3-R-4-arylthiophenes are formed in the reaction of the organodimagnesium compounds with diethyl oxalate. It was established that the bromomagnesiumethoxycarbinolates obtained from the indicated thiophenes and bromomagnesium ethoxide have high thermal stabilities. The IR and PMR Spectra of the synthesized compounds were studied.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 754–757, June, 1982.     

Functional derivatives of thiophene

2-Aryl-4-oxothieno[2,3-d]oxazine derivatives were synthesized. Opening of the oxazine ring to give 2-benzamidothiophene-3-carboxylic acid hydrazide derivatives is observed when these compounds are treated with hydrazine hydrate.See [1] for Communication 17.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 45–46, January, 1980.     

Functional derivatives of thiophene

A method is proposed for the synthesis of 5-acylamino-2,3-dimethylthiophene-4-carbaldehydes and 5-acylamino-2,3-tetramethylenethiophene-4-carbaldehydes by the formylation of the corresponding thiophenes using the Vilsmeier reaction. From the formyl derivatives obtained, previously unaccessible derivatives of thieno[2,3-b]pyridine, thieno[2,3-d]pyrimidine, and thieno[3′,2′∶5,6]pyrido[2,3-d]-pyrimidine have been synthesized.     

Functional derivatives of thiophene

The nitration of 3-ethoxycarbonyl-4-hydroxy-2-methyl- and 4-chloro-3-ethoxycarbonyl-2-methylthiophenes has given the corresponding 5-nitro derivatives of thiophene. The 4-chloro-3-ethoxycarbonyl-2-methylthiophene was synthesized by the decarboxylation of 3-chloro-4-ethoxycarbonyl-5-methylthiophene-2-carboxylic acid, which is formed by the oxidation of 3-chloro-4-ethoxycarbonyl-5-methylthiophene-2-carbaldehyde.For Communication IV, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1024–1025, August, 1973.     

Functional derivatives of thiophene

Acyl derivatives of substituted β-thienylhydrazines were obtained by reaction of 2-methyl-3-carbethoxy-4-hydroxythiophene with acyl hydrazines. Hydrolysis of the products gave a thienylhydrazine derivative and its hydrochloride.     

Functional derivatives of thiophene

A preparative method for the synthesis of thienobenzothiazines — phenothiazine analogs-was worked out on the basis of 2-methyl-3-carbethoxythiophene derivatives and nitroarenesulfenyl chlorides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 741–745, June, 1973.     

Functional derivatives of thiophene

The derivatives obtained by reaction of o-halonitrothiophenes with cyanoacetic and acetoacetic esters were converted to thieno[2,3-b]- and thieno[3,2-b]pyrroles by reductive cyclization.See [1] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1628–1630, December, 1973.     

Synthesis of some thiophene derivatives

The synthesis of thiopene derivatives from diacetylenic hydrocarbons has been described [1]. We have examined for the first time the reaction of diacetylenic diesters with hydrogen sulfide and with NaHS. The diacetylenic diesters react readily with hydrogen sulfide or NaHS in acetone at pH 9–10 to give 2,5-disubstituted thiopheries (see Table 1).Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 713–714, May, 1970.     

Enthalpy of formation of thiophene derivatives

The enthalpy of formation in the gas phase has been calculated for 21 carbonyl compounds of the thiophene series with the aid of the PM3, MINDO, AM1, and MNDO semiempirical quantum-chemical methods. Comparison of them with experimental data showed that the best linear correlation was achieved with the PM3 method. The latter in conjunction with a developed linear regression equation has been used to predict the enthalpy of formation of 22 carboxylic acids and ketones of the thiophene series.     

Synthesis of novel c-hetero-fused thiophene derivatives

An efficient synthesis of novel 5-(4-nitrophenyl)-2-benzoxazol-2-yl-c-hetero-fused thiophenes was achieved by the condensation of 5-(4-nitrophenyl)-2-benzoxazol-2-yl-3,4-dichlorothiophene with ethylene glycol, ethylenediamine, substituted thioamides and 2-mercaptobenzimidazole using sodium carbonate in refluxing dimethyl formamide.     

Mannich reactions of annulated thiophene derivatives

Aminoalkylation reactions were applied to two annulated thiophene derivatives to successfully prepare mono- and bis-substituted Mannich bases. Compounds were characterized by NMR, FT-IR, and HRMS.