Investigations in the imidazole series

A number of 2-acyl(2-acyl-3-alkyl)imidazo[2,1-b]thiazoles and previously unknown 2-acyl-(2-acyl-3-alkyl)imidazolino[2,1-b]thiazoles were obtained by the reaction of 2-acylmethylmercapto derivatives of imidazole and imidazoline with acylating agents.See [1] for communication XLVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 389–392, March, 1971.     

Investigations in the imidazole series

2,3-Dihydro derivatives of naphth[1,2-d]imidazo[3,2-b]imidazole were synthesized by the reaction of 2-chloro-3-(-haloalkyl)naphth[1,2-d]imidazole with ammonia and primary amines and by the reaction of 2-chloro-3-(-hydroxyaIkyl)naphth[1,2-d]imidazole with ammonia and amines with subsequent cyclization of the resulting 2-amino(alkylamino, arylamino)-3-(-hydroxyalkyl)naphth[1,2-d]imidazoles under the influence of thionyl chloride or phosphorus oxychloride. Dihydro derivatives of the condensed naphth[1,2-d]imidazo[3,2-b]imidazole system have not been described in the literature.See [1] for communication LX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1125–1127, August, 1971.     

Investigations in the imidazole series

Cyclization of 2--oxoalkylthio- and 2--oxoaralkylthiobenzimidazoles and the reaction of 2-mercaptobenzimidazoles with -halogenoketones in the absence of bases has given a number of derivatives of thiazolo[3, 2-a]benzimidazole, cyclopentenothiazolo[3, 2-a]benzimidazole, and tetrahydrobenzothiazolo[3, 2-a]benzimidazole.For part XXXVI, see [6].     

Investigations in the imidazole series

The catalytic dechlorination of 1-alkyl-5-chloro-, 1-alkyl-4-chloro-, and 1-alkyl(aralkyl)-2-alkyl(aryl)-5-chloroimidazoles in the presence of Raney nickel, which makes it possible to simplify the synthesis of a number of 1-alkyl- and 1-alkyl(aralkyl)-2-alkyl(aryl)imidazoles, was investigated.See [1] for communication LXXV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 820–822, June, 1972.     

Investigations in the imidazole series

The synthesis of derivatives of 2,3-dihydropyrrolo[1,2-a]imidazole from 1,2-dialkylimidazolines or 1,2-diarylkylimidazolines and phenacyl bromides with subsequent heating of the 1,2-disubstituted 3-phenacyl-imidazolinium bromides in aqueous or ethanolic solution in the presence of bases has been effected.For part XXXVIII, see [7].     

Investigations in the imidazole series

Imidazo[1,2-a]imidazole derivatives were synthesized by the reaction of 1-acylmethyl-2-bromo-4,5-diphenylimidazoles with ammonia and primary amines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1243–1247, September, 1971.     

Investigations in the imidazole series

Purinyl(theophyllinyl)-8-mercapto aldehydes and their acetals were synthesized by the reaction of 8-thio derivatives of purine and theophylline with -halo aldehydes and their acetals. The IR spectra demonstrated that the indicated aldehydes exist in the solid state as tautomeric forms — 3-hydroxy derivatives of thiazolino[2,3-f]purines(xanthines). Dehydration of the latter gave thiazolo[2,3-f]purine, 6,8-dimethylthiazolo[2,3-f]xanthine, and their 2-alkyl-substituted derivatives. The structures of the three-ring compounds were established by reductive desulfuration to 7-alkyl-substituted purines and theophyllines.See [1] for communication LXXVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 996–999, July, 1972.     

Investigations in the imidazole series

The reaction of 2-aminobenzothiazole and its 6-substituted derivatives with-bromomethyl alkyl (aryl, heteryl) ketones was investigated in detail. Under mild conditions, 3-acylmethyl-2-iminobenzothiazolines were isolated. Their structures were established, and their properties and the conditions for cyclization to imidazo[2,1-b]benzothiazole derivatives were studied.See [1] for communication LXXVII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1271–1274, September, 1972.     

Investigations in the imidazole series LXXIV. Electrophilic substitution reactions in the pyrrolo[1,2-a]imidazole series

The formylation, acetylation, hydroxymethylation, azo coupling, nitrosation, nitration, and chloromercuration of pyrrolo[1,2-a]imidazole derivatives were studied. The PMR spectra were used to establish that all of these reactions proceed at the 5 position or, if it is occupied, at the 7 position of the two-ring system. When the 5 and 7 positions are free, the formation of 5,7-disubstituted pyrrolo[1,2-a]imidazoles is possible.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 405–409, March, 1972.     

Investigations in the imidazole field

It has been established that various inorganic and organic bases can be used for the cyclization of 1,2-dialkyl-3-(-oxoalkyl[aralkyl])benzimidazolium halides into derivatives of pyrrolo[1,2-a]benzimidazole. The action of strong bases on quaternary benzimidazolium salts gives O-betaines—intermediates in the closure of the pyrrole ring.For part XL, see [1].     

Investigations in the imidazole series LXIII. Synthesis of imidazo[1,2-a]imidazole derivatives from 2-aminoimidazoles

A number of imidazo[1,2-a]imidazole derivatives were synthesized by the reaction of 1-methyl-2-aminoimidazole with-bromoketones. The intermediate 1-methyl-3-acylmethyl-2-iminoimidazolines were isolated, and the conditions for their cyclization to imidazo-[l,2-a]imidazole derivatives were studied.See [1] for communication LXII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1692–1694, December, 1971     

Research in the imidazole series

The hydrolysis of 7-cyano derivatives of pyrrolo[1,2-a]imidazole in 85–90% sulfuric acid at 100°C gives amides of pyrroloimidazole-7-carboxylic acids. Under more severe conditions, the resulting carboxylic acids are decarboxylated to the corresponding pyrroloimidazole derivatives with a free 7 position.See [1] for communication XC.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1658–1659, December, 1976.     

Studies in the imidazole series

By quaternization of 1-alkyl(aryl, aralkyl)-2-methyl-4, 5-diarylimidazoles with -bromo ketones and by subsequent cyclization of the quaternary salts of imidazole, a number of arylpyrrolo[1,2-a]imida~ zoles were obtained. A study was made of the effect of different bases on the process of cyclization and the yield of pyrroloimidazole derivatives. The structure was established of certain intermediate products of the reaction involving the closure of the pyrrole ring.For Part XXXVI, see [11].     

Studies in the imidazole series

Imidazo[1,2-f]xanthine derivatives were synthesized by the reaction of 8-methylmercaptotheophylline with-haloketones and subsequent heating of the 7-acylalkyl-8-methylmercaptotheophyllines with ammonia and primary amines.See [1] for communication LIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 686–688, May, 1971.     

Research in the imidazole series

It was established that the reaction of 8-theophylline with α-halo ketones gives 8-acylalkylthiotheophyllines or their cyclization products-thiazolo[2,3-f]xanthine derivatives — depending on the conditions used to carry out the reaction and the structure of the halo ketones. Derivatives of two new heterocyclic systemscy-clopentathiazolo[2,3-f]purine and benzothiazolo[2,3-f]purine-were synthesized from 2-bromocyclopentadienone and cyclohexanone. The structure and the conditions for the cyclization of 8-acylalkylthiotheophyllines to three(four)-ring compounds were studied. The structure of the thiazolo[2.3-f]xanthines was proved by reductive desulfuration to 1,3,7-trialkylxanthines.     

Research in the imidazole series

The Mannich reaction in the 6-aryl-7-cyanopyrrolo[1,2-a] imidazole series was studied, and the corresponding 5-dialkylaminomethyl derivatives of this heterocycle were obtained.See [1] for communication LXXXIX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1552–1553, November, 1976.     

Studies in the imidazole series

Methods were developed for the synthesis of dihydro and tetrahydro derivatives of imidazo-[1,2-a]- and imidazo[1,2-c]pyrimidine and imidazo[2,1-b]-5-quinazolone from 2-amino- and 4-aminopyrimidines, 2-amino-4-quinazolones, and -haloethanols or 1,2-dihaloethanes. Dihydroimidazo[1,2-c]quinazoline, which was also obtained by cyclization of 4-(-hydroxyethylamino)-quinazoline, was synthesized by reaction of 4-chloroquinazoline with -haloethylamines.See [1] for communication LXXXV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 834–836, June, 1976.     

Research in the imidazole series

The synthesis of 9-acyl- and 8-alkyl-9-acyl-substituted naphth[1,24,5]imidazo[2,1-b]thiazoles was accomplished by the reaction of 2-acylmethylthionaphth[1,2-d]imidazole with acylating agents and of 2-mercaptonaphth[1,2-d]imidazole with 3-chloro-2,4-pentanedione.See [1] for communication LXVII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 30–32, January, 1972.     

Research in the imidazole series

The reduction of pyrrolo[1,2-a]imidazole-2-one and pyrrolo[1,2-a]benzimidazole derivatives, which leads to the formation of 2,3-dihydropyrrolo[1,2-a]imidazole derivatives and derivatives of the previously unknown 1,2,3,3a-tetrahydropyrrolo[1,2-a]benzimidazole, was studied. A method was developed for the preparation of 5- and 7-amino derivatives of pyrrolo[1,2-a]imidazole by reduction of the corresponding nitroso- and arylazo-substituted pyrrolo[1,2-a]-imidazoles.See [1] for communication XCI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 225–228, February, 1977.     

Research in the imidazole series

2-Alkyl(aryl, hetaryl)-6,8-dimethylthiazolo[2,3-f]xanthines were synthesized from 8-bromotheophylline and -halo ketones with subsequent replacement of the bromine atom by sulfur and cyclization of the resulting 7-acylmethyl-8-thiotheophyllines under the influence of dehydrating agents.See [1] for communication LXXXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1121–1123, August, 1975.