Synthesis of some 3-substituted quino[3,2-c][1,8]naphtyridines. A new heterocyclic ring system

Isatoic acid reacts with 7-mcthyl-2,3-dihydro-1,8-naphthyridin-4(1H) one ( 8 ) to give 3-methyl-5,6-dihvdroquino[3,2-c][1,8]naphthyriclin-7-carboxylic acid ( 9a ), which was transformed into the 3-methylquino[3,2-c][1,8]naphthyridine ( 7a ) by refluxing with copper chromite in quinoline. The same product ( 7a ) was also obtained by aromatization of the 3-methyl-5,6-dihydroquino-[3,2-c][1.8]naphthvridine ( 10a ), prepared by condensation of the ketone ( 8 ) and o-aminobenzaldehyde. Other 3-substituted quino[3,2-c][1,8]naphthyridines ( 7b,c,d,e ), which contain a new heterocyclic, ring structure, have been prepared using o-aminobenzaldehyde and 7-sub-stituted-2,3-dihv dro-1,8-naphthyridin-4(1H) ones ( 12 and 13 ) as starting materials. Also, the preparation of the parent nucleus ( 7f ) is described.     

Synthesis of some 3-Methyl-11H-indolo[3,2-c] [1,8]naphthyridines. A New heterocyclic ring system

Some derivatives of 11H-indolo[3,2-c] [1,8]naphthyridine, a new heterocyclic system, have been prepared using the Fischer indole synthesis on the appropriately phenylhydrazones. The preparation of some substituted 5,6-dihydro-11H-indolo[3,2-c][1,8]naphthyridines is also described.     

Synthesis of some 3,7-disubstituted quino[3,2-c][1,8]naphthyridines

The preparation of some 3,7-disubstituted-5,6-dihydroquino[3,2-c][1,8]naphthyridines ( 6 ) by the condensation of 7-substituted-2,3-dihydro-1,8-naphthyridin-4-(1H)ones ( 5 ) with o-aminoacetophenone or o-aminobenzophenone is described. All the 5,6-dihydroderivatives 6 were transformed into the fully aromatic compounds 7 by heating with nitrobenzene. Only a few quino[3,2-c][1,8]naphthyridines were previously described.     

Pyrrolo[3,2-c][1,2,5]benzotriazocine: A new ring system

A nucleophilic substitution reaction in the pyrrole series, achieved by a neutral nucleophile, led to the key intermediate 7 which by reduction and successive diazotization afforded the new ring system pyrrolo[3,2-c][1,2,5]benzotriazocine 9 in good yield.     

Synthesis of some benzo[b][1,8] and [1,5]naphthyridines

A series of carboxylic acid derivatives of the title compounds have been prepared as precursors of potential anti-tumor compounds, by annulation of 2-methylcyclohexanone to the appropriate aminopyridinecarboxaldehyde followed by aromatization and oxidation of the methyl group.     

Synthesis of pyrrolo[2,1-c][1,4]benzoxazepines. 1. A novel heterocyclic ring system

The synthesis of a novel pyrrolo[2,1-c][1,4]benzoxazepine ring system (II) by a nucleophilic aromatic fluoride displacement-cyclization is described. Aminoalkyl derivatives were prepared by either the Mannich reaction, or Vilsmeier formylation to provide the 3-formyl derivative which was further elaborated.     

Synthesis of 4H-furo[3,2-b]indole derivatives A new heterocyclic ring system

4H-Furo[3,2-b]indole (III) was prepared from deoxygenation of 2-(2-nitrophenyl)furan (II) with triethyl phosphite and thermolysis of 2-(2-azidophenyl)furan (VI). 4H- or 4-alkylfuro [3,2-b]indole-2-carboxaldehydes (VIII, IXa-c) were obtained by Vilsmeier formylation of the corresponding furo[3,2-b]indoles (III, VIIa-c). 4H-Furo[3,2-b]indole-2-carboxaldehyde (VIII) was submitted to the Cannizzaro, Wittig and reduction reactions. The Shiff's bases were obtained by the reaction of 4-ethylfuro[3,2-b]indole-2-carboxaldehyde (IXb) with amines. J. Heterocyclic Chem., 14, 975 (1977)     

Synthesis of derivatives of a new heterocyclic system — 1,2,3,4-tetrahydrobenzofuro[3,2-c]pyridine

Derivatives (Iva–f) of the heretofore unknown 1,2,3,4-tetrahydrobenzofuro[3,2-c]pyridine heterocyclic system were synthesized by the cyclization of aryl ethers of the oximes of piperidones (IIIa–f) under acid conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1469–1472, November, 1971.     

Synthesis of pyrano[3,4-c]thieno[3,2-e][1,2,4]triazolo[4,3-a]pyridines,representatives of a new fused heterocyclic system

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Synthesis of thieno[3,4-c] and thieno[3,2-c][2,1]benzothiazepines

Starting from [4,3-c] and [3,2-c] methyl chlorosulfonylthiophenecarboxylates the synthesis of ketones 7 and 8 is described. These compounds are the first two representatives of the new thieno[3,4-c] and thieno-[3,2-c][2,1]benzothiazepine ring systems. The formation of methyl 3-chlorosulfonylthiophene-2-carboxy-late is also revised.     

6H-indeno[1,2-b]pyrido[3,2-e]pyrazines. A new heterocyclic ring system

Condensation of 1,2-indanedione and 1,2,3-indanetrione hydrate (ninhydrin) with 2,3-diamino-pyridines gave a number of compounds belonging to the hitherto unknown 6H-indeno[1,2-b]-pyrido[3,2-e]pyrazine ring system. The unsymmetrical nature of the reactants can theoretically result in isomeric ring closure products. Assignment of the 6H- ring system was based upon the identity of 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one obtained from 2,3-diaminopyridine and ninhydrin with material prepared by unequivocal synthesis. The direction of cyclization of ninhydrin and 1,2-indanedione with the diamines was shown to be the same by reduction of the indenopyridopyrazinones to the corresponding indenopyridopyrazines. Some physical, chemical, and tumor growth-inhibitory properties of the products are reported.     

Synthesis of some 2,3-Dihydro-11bH-thiazolo[3,2-d][1,4]benzoxazepin-5-(6H)one derivatives. A new heterocyclic ring system

Condensation of (S)-penicillamine methyl or ethyl ester hydrochloride with salicylaldehyde and its C-5 derivatives, provided the diastereomeric thiazolidine derivatives 1 and 2 . The resulting amino function was acylated to afford the amides 3 and 4. Cyclization of the latter led to the 2,3-dihydro-11bH-thiazolo[3,2-d]-[1,4]benzoxazepin-5-(6H)ones 5 and 6. Conformational data for these heterocyclic compounds are discussed.     

Synthesis of some novel 7-substituted [1,3,4]thiadiazolo[3,2-c][1,3,5]thiadiazine-6,6-dioxides with antifungal evaluation against rice pathogens

Synthesis of a new series of novel [1,3,4]thiadiazolo[3,2-c][1,3,5]thiadiazine-6,6-dioxide by [4 + 2] cycloaddition reaction of 3-benzylidineamino[1,3,4]thiadiazole with sulfene generated in situ from methanesulfonyl chloride in the presence of triethylamine is described. The novel compounds thus synthesized were screened for their antifungal activity against two fungal species, namely Rhizoctonia solani and Dreschslera oryzae. Carbendazim was the standard used for the evaluation of antifungal activity.     

Reduction of 12-acetylaminoindolo[1,2-c]quinazolines. Preparation of derivatives of the new heterocyclic system indolo[3,2-d][1,3]benzodiazepine

Reduction of derivatives of 12-acetylaminoindolo[1,2-c]quinazoline yielded the corresponding 12-acetylamino-5,6-dihydroindolo[1,2-c]quinazolines, recyclization of which under the influence of dilute hydrochloric acid led to the formation of derivatives of the hitherto unknown system indolo[3,2-d][1,3]benzodiazepine.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 668–673, May, 1988.     

Pyrrolopyridazines. II. Synthesis of the novel pyrrolo[3,2-c]pyridazine ring system

The first derivatives of the pyrrolo[3,2-c]pyridazine ring system, ethyl pyrrolo[3,2-c]pyridazine-6-carboxylate 2-oxide (5) and ethyl 3-chloro-6-methylpyrrolo[3,2-c]pyridazine-7-glyoxalate 1-oxide ( 12 ), were obtained in good yields from the cyclization of 4-ethoxymethyl-eneamino-3-methylpyridazine 1-oxide (3) and 3-chloro-5-(α-ethoxyethylideneamino)-6-methylpyridazine 1-oxide (14, R ? Cl, R₁ ? OMe), respectively, with diethyl oxalate and potassium ethoxide in ether.     

Synthesis,structure and reactivity of imidazo[1,2-a][1,8]naphthyridines

The synthesis and reactivity of imidazo[1,2-a][1,8]naphthyridines are reported. Electrophilic substitution reactions were studied and the site of the reaction was established with the aid of high-field ¹H and ¹³C nmr spectra. The experimental C-1 position reaction was correlated with a CNDO/2 calculations.     

Synthesis and rearrangements of 7H-pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]-and 7h-pyrrolo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines

7H-Pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines were synthesized by the reactions of 2-ethoxymethyleneamino-1H-pyrrole-3-carbonitriles with acid hydrazides and by the reactions of aminoiminopyrimidines (prepared based on the above-mentioned carbonitriles) with acid chlorides. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1438–1443, August, 2006.     

Synthesis of pyrido[3,2-e]pyrrolo[2,1-c][1,2,4]triazines from pyrido[3,2-e][1,2,4]triazine derivatives

In carrying on our interest in heteropolycyclic structures with biological activities, we projected the preparation of compounds containing the pyrido[3,2-e][1,2,4]triazine or pyrido[2,3-b][1,4]triazepine systems. The established synthetic approach for the preparation of latter system led to the triazine derivatives 5a-f while a new bicyclic triazepine structure 6 is accomplished with difficulty. In expanding the pyridotriazine structure, we obtained derivatives of a new tricyclic structure, 5-substituted-6a-ethyloxycarbonyl-5,6,6a,7-tetrahydropyrido[2,3-e]pyrrolo[2,1-c][1,2,4]triazin-9(8H)-ones 8 in which the triazine ring is fused with a pyrrole nucleus. Compounds 5a-f and 8a,b will be tested as potential CNS depressant, antiinflammatory, analgesic and antibacterial agents.