Synthesis of 2-carbethoxybenzofuran derivatives

A mixture of 3-formyl and 3-acetoxymethyl derivatives is formed in the oxidation of 2-carbethoxy-3-methyl-7-ethylbenzofuran with selenium dioxide. Reduction with lithium aluminum hydride gives 2,3-dihydroxymethyl derivatives, which are converted to 2,3-diformyl derivatives by successive oxidation. A number of derivatives of 3-methyl-7-ethylbenzofurancarboxylic acid were obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 756–759, June, 1987.     

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.     

Synthesis of 5,6,7,8-tetrahydro-5-oxopyrido[2,3-d]pyrimidine-6-carbonitriles and -6-carboxylic acid esters

Dieckmann ring closure reactions of 4-[(2-cyanoethyl)substituted amino]-2-phenyl-5-pyrimidinecarboxylates (Ha-f) afforded several 5,6,7,8-tetrahydro-5-oxo-2-phenylpyrido[2,3-d]pyrimidine-6- carbonitriles (IIIa-f). The open-chain intermediates (IIa-f) were prepared by dechloroamination of 5-carbethoxy-4-chloro-2-phenylpyrimidine (1a) with several 3-substituted amino- propionitriles. Alkylation of the sodium salt of 5,6,7,8-tetrahydro-8-methyl-5-oxo-2-phenyl-pyrido[2,3-d]pyrimidine-6- carbonitrile (IIIa) with methyl iodide in DMF resulted in methylation at C-6 to afford IV. Tosylation of IIIa in pyridine gave the corresponding tosyl ester (V) of the enolic form. Oxidative dehydrogenation at the 6,7-position resulted when IIIa reacted with thionyl chloride, affording 5,8-dihydro-8-methyl-5-oxo-2-phenylpyrido[2,3-d]pyrimidine-6- carbonitrile (VII). Dechloroamination of la or 5-carbethoxy-4-chloro-2-methylthiopyrimidine (Ib) with ethyl 3-ethylaminopropionate followed by Dieckmann cyclization of the resulting open-chain intermediates gave the corresponding ethyl 5,6,7,8-tetrahydro-5-oxopyrido[2,3-d]pyrimidine-6-carboxylates IX'a and IX'b, respectively. These exist predominately in the enol form and undergo alkylation and oxidation reactions similar to IIIa.     

Diethyl ethoxymethylenemalonate in triheterocycles: A new synthesis of pyrido[3,2-e]pyrimido[1,2-c]pyrimidines

Diethyl ethoxymethylenemalonate was used for the novel synthesis of the triheterocyclic 3-carbethoxy-9,ll-disubstituted-4-oxo-4H-pyrido[3,2-e]pyrimido[1,2-c]pyrimidines from 4-aminopyrido[2,3-d]pyrim-idines via thermal cyclization of the intermediate ethyl 2-carbethoxy-3-[5,7-disubstituted-4-amino-pyrido[2,3-d]pyrimidin-4-yl]acrylates. The alkaline hydrolysis of 3-carbethoxy-4-oxo-4H-pyrido[3,2-e]-pyrimido[1,2-c]pyrimidines was performed to give corresponding acid derivatives.     

Synthesis and properties of 1-aryl-1,4-dihydro-2,7-dimethyl-4-oxopyrido[2,3-d]pyrimidine-6-carboxylic acids and their derivatives

Acetylation of 2-arylamino-5-carbethoxy-6-methylnicotinonitriles gave N-acetyl-2-arylamino-5-carbethoxy-6-methylnicotinonitriles, which, under the influence of hydrogen chloride, are cyclized to 1-aryl-1,4-dihydro-6-carbethoxy-2,7-dimethyl-4-oxopyrido[2,3-d]pyrimidines. The latter can be converted to the corresponding carboxylic and hydroxamic acids, as well as to acetylation products 1-aryl-2-acetonyl-1,4-dihydro-6-carbethoxy-7-methyl-4-oxopyrido [2,3-d]pyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 535–539, April, 1992.     

Vilsmeier formylation of 2-methyl-3 -carbethoxy-5-methoxy- and 2-methyl-5-methoxyindoles

The corresponding 6- and 3-formyl derivatives were obtained by formylation of 2-methyl-3-carbethoxy-5-methoxy- and 2-methyl-5-methoxyindole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 339–341, March, 1971.     

Synthesis and some transformations of halogen-substituted o-quinones in the benzofuran series

The corresponding 6-halo-substituted o-quinones were obtained by the action of nitric acid on 2-methyl(phenyl)-3-carbethoxy-4,6-dihalo-5-hydroxybenzofurans, whereas 2-methyl-3-carboxy-4,6-dibromo-5-hydroxybenzofuran is converted to the 4,6-dinitro derivative under similar conditions. The action of nitric acid on 2-methyl-3-carbethoxy-4-chloro-5-hydroxybenzofuran leads to replacement of the hydrogen in the 6 position by a nitro group. The reduction of o-quinones to the corresponding dihydroxy derivatives and reactions of quinones with amines are described.     

2-Bromomethyl derivatives of benzofuran and indole and their reactions with some nucleophilic reagents

The corresponding 2-bromomethyl derivatives of benzofuran and indole were obtained by bromination of 2-methyl-3-carbethoxy-5-methoxybenzofuran and 1,2-dimethyl-3-earbethoxy-5-methoxyindole with N-bromosuccinimide. A number of alkyl(aryl)thiomethyl and dialkylaminomethyl derivatives were obtained by reaction of the 2-bromomethyl derivatives with nucleophilic reagents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 308–311, March, 1973.     

Derivatives of condensed pyrimidine,pyrazine, and pyridine systems

Reaction of 2-mercapto-3-amino-5,6-dimethyl- and 2-mercapto-3-amino-5,6-diphenylpyrazines withα-halo acid esters gave 2-carbethoxy-3-aminopyrazines, which are converted by the action of sodium ethoxide to 5,6-dimethyl- and 5,6-diphenylpyrazino[2,3-b]-[1,4]thiazin-6-ones. The latter are more conveniently obtained from 2-chloro-3-amino-5,6-dimethyl- and 2-chloro-3-amino-5,6-diphenylpyrazines and thioglycolic acid. 5,6-Dihydropyrazinothiazine is formed by reduction of 5,6-dimethyl pyrazino[2,3-b][1,4]thiazin-6-one, whereas the 2,3-dimethyl-5-amino-6-sulfonic acid and its N-oxide are formed by oxidation.     

Synthesis of furo[2,3-f]- and furo[3,2-e]indole derivatives

Two compounds — the diethylamides of 1,2-dimethyl-3-carbethoxy-6-carboxyfuro[2,3-f]- and 1,2-dimethyl-3-carbethoxy-5-carboxvfuro[3,2-e]indoles — are formed in the reaction of 1,2-dimethyl-3-carbethoxy-5-hydroxyacetic acid (I) with dimethylformamide and phosphorus oxychloride as a result of subsequent intramolecular cyclization of the intermediates. This constitutes evidence for formylation of the starting acid in the 6 and 4 positions. Formylation of the ethyl ester of acid I gives only the 6-formyl derivative, the intramolecular cyclization of which under the influence of sodium ethoxide gives 1,2-dimethyl-3,6-dicarbethoxyfuro[2,3-f]-indole. Hydrolysis of the latter with alcoholic alkali gives the corresponding dicarboxylic acid. The structures of the synthesized compounds were confirmed by the PMR, IR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 766–769, June, 1977.     

The chemistry of a ketene-sulfur dioxide adduct

We have demonstrated the formation of a reactive species from ketene and sulfur dioxide and have investigated some of its reactions. The 3 + 2 ← 5 cycloaddition reactions of this intermediate with benzylideneaniline and its derivatives gave the corresponding 2,3-diphenylthiazolidin-4-one 1,1-dioxides. The reduction of 2,3-diphenylthiazolidin-4-one 1,1-dioxide with lithium aluminum hydride yielded the corresponding thiazolidine. Aniline and its derivatives reacted with the ketene-sulfur dioxide adduct to give thioaceto-1,3-dianilide 3-oxide. o-Phenylenediamine gave [2,1,5]benzothiadiazepin-4-one 2-oxide, a derivative of a new ring system, [2,1,5]benzothiadiazepine. o-Aminophenol yielded [1,2,5]benzothiazepin-4-one 2-oxide.     

Synthesis of 2-carbethoxy-3-methyl-4-hydroxybenzofuran derivatives

A number of 2-.carbethoxy-3-methylbenzofuran derivatives were synthesized. A 5,5-gem-dibromo derivative was obtained in the bromination of 2-carbethoxy-3-methyl-4-oxo-4, 5,6,7,tetrahydrobenzofuran. Dehydrobromination of this, dibromo derivative gave 2-carbethoxy-3-methyl-4-hydroxy-5-bromobenzofuran. Depending on the structure of the starting compound and the brominating agent, the bromine in the bromination of 2-carbethoxy-3-methyl-4-hydroxy- and 4-acetoxybenzofurans with bromine and N-bromosuccinimide is incorporated either in the methyl group or in 5 and 7 positions of the benzofuran ring. The nitration of 2-carbethoxy-3-methyl-4-hydroxybenzofuran and its bromo derivative leads to 5-nitro- and 5,7-dinitrobenzofuran derivatives. The structures of the synthesized benzofuran derivatives were established by means of the PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 27–29, January, 1980.     

Thieno[2,3-d]pyrimidines. I. A new method for the preparation of esters and amides of thieno[2,3-d] pyrimidine-6-carboxylic acids

A novel method for the preparation of esters and amides of thieno[2,3-d]pyrimidine-6-carb-oxylic acids was described. A typical example was the direct formation of ethyl 5-amino-2-methylthiothieno[2,3-d]pyrimidine-6-earboxylate(IIIa) from 4-chloro-2-methylthio-5-pyrimidine-carbonitrile (Ia) and ethyl mercaptoacetate in refluxing ethanol containing sodium carbonate. Displacement of the methylthio group in IIIa by various amines gave the corresponding amino derivatives. The reactions of IIIa and related compounds with acetylating agents such as acetic anhydride or chloroacetyl chloride gave various products. Treatment of 5-carbethoxy-4-chloro-2-phenylpyrimidine(IV) with methyl mercaptoacetate afforded the dechloro intermediate diester Va, which cyclized on reaction with sodium ethoxide to form methyl 5-hydroxy-2-phenylthieno-[2,3-d]pyrimidine-6-carboxylate (Vla). The synthesis was expanded to include the preparation of various new 2,4,5-trisubstituted thieno[2,3-d]pyrimidine-6-carboxylic acid esters and amides (Charts I-V).     

4,5-Dioxo-and 4-oxo-2,3-diaryl-5-diazo-6,6-dimethyl-4,5,6,7-tetrahydroindazoles

The oxidation of 2,3-diphenyl-, 3-(4-chlorophenyl)-2-phenyl-, 3-(4-dimethylaminophenyl)-2-phenyl-, 3-(4-methoxyphenyl)-2-phenyl-, 2-phenyl-3-(3-pyridyl)-, 3-phenyl-2-(2-pyridyl)-, and 3-(4-dimethylaminophenyl)-6,6-dimethyl-4-oxo-2-(2-pyridyl)-4,5,6,7-tetrahydroindazoles using H₂SeO₃ in acetic acid in the presence of sulfuric acid gave the corresponding 4,5-dioxo derivatives. Reaction of these with tosylhydrazine gave 4-oxo-5-tosylhydrazino derivatives which were decomposed by alkali to give the corresponding 2,3-diaryl-5-diazo-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1829–1833, December, 2005     

Condensed Thienopyrimidines. 19. Study of the Heterocyclization of 2-Hydrazino-6,6-dimethyl-5,6-dihydro-8H-pyranothieno[2,3-d]pyrimidin-4-one

Novel condensed pyrano[4',3':4,5]thieno[3,2-e]triazolo[3,4-b]pyrimidine derivatives have been synthesized from 2-amino-3-carbethoxy-5,5-dimethyl-4,5-dihydro-7H-thieno[2,3-c]pyran.     

Donnees complementaires sur la chimie des phosphacymantrenes

We have systematically studied the acylation reaction of 3,4-dimethylphosphacymantrene 3 which yields the corresponding 2-acyl derivatives. The CO → CH₂ reduction of these acyl derivatives is performend by AlCl₃ + LiAlH₄. The CO → CH(OH) conversion is performed by NaBH₄. Various attempts to obtain the 2-carboxy acid derivative of 3 by degradative oxidation of the corresponding 2-acetyl derivative in basic medium have failed. However, the 2-carbethoxy-3,4-dimethylphosphacymantrene 12 has been obtained in low yield by reaction of the corresponding 1-phenylphosphole sulfide with Mn₂(CO)₁₀. The P → Fe(CO)₄ complex of 3 has been prepared by reaction of 3 with Fe(CO)₄ THF. Upon complexation the CP couplings within the ring disappear and a strong deshielding of the phosphorus atom is observed.     

Synthesis of substituted thienothiazoles

The action of sulfur monochloride on 2-amino-3-carboxy-5-phenylthiophene or 2-amino5-phenylthiophene hydrochloride gave 5-phenylthieno[2,3-d]-2-thioniathiazole chloride, which is converted to the corresponding hydrate on treatment with water. Heating of the thionium salt or its hydrate with carbon disulfide in an aqueous alcohol solution of aklaki gave 2-mercapto-5-phenylthieno[2,3-d]thiazole, which under the influence of dialkyl sulfates or on oxidation with potassium permanganate in alkaline media is converted, respectively, to S-alkyl derivatives or a 5-phenylthieno[2,3-d]thiazole-2-sulfonic acid salt. 2-Sulfo-3-alkylthieno[2,3-d]thiazolium betaines are obtained by heating the latter with alkylating agents. 2-Hydroxy-thieno[2,3-d]thiazoles were synthesized by hydrolysis of thienothiazole-2-sulfonic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 477–480, April, 1979.     

Synthesis of 2-selenothieno[2,3-d]pyrimidine derivatives

Intramolecular cyclization of 2-(N-acylselenoureido)-3-carbethoxy-4,5,6,7-tetrahydrobenzo[b]thiophenes in alkaline media leads to the formation of the potassium salt (I) of 2-seleno-4-oxo-3,4,5,6,7,8-hexahydrobenzo[b]thieno[2,3-d]pyrimidine, acidification of which yielded the corresponding base in free form. Some pyrimidine compounds containing a selenium atom in the side chain were obtained by reaction of potassium salt I with halo derivatives (ClCH₂CH₂COOCH₃ and ClCH₂CH₂OH).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 753–754, June, 1977.     

Synthesis of noval benzoylated indoles

It has been shown that Friedel-Crafts p-nitrobenzoylation of 2,2-dicarbethoxybis(5-indoyl)methane occurs at the bridging group. From the products of p-nitrobenzoylation of 2-carbethoxy-5-methylindole, 2-carbethoxy-5-hydroxy-indole and 2,7-dicarbethoxy-1H,6H-pyrrolo[2,3-e]indole there were obtained corresponding amines and an oxime.Iv. Dzhavakhishvili State University, Tbilisi 380028. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1202–1205, September, 1994. Original article submitted September 15, 1994.     

Synthesis of thieno[2,3-d]thia[1]pyrano[4,3-b]pyrrole derivatives

It is shown that 2-methyl-3-carbethoxy-4H,8H,5,6-dihydrothieno[2,3-d]thia[1]pyrano [4,3-b]pyrrole and 8-methyl-9-carbethoxy-10H,5,6-dihydrothieno[2,3-d]thia[1]chromeno[4,3-b]pyrrole and their S,S-dioxides, respectively, are obtained in the reaction of 2-methyl-3-carbethoxy-4-thienylhydrazine with tetrahydro-4-thiopyrone, tetrahydro-4-thiopyrone S, S-dioxide, 4-thiochromanone, and 4-thiochromanone S,S-dioxide in the presence of an acid catalyst.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 195–196, February, 1979.