Pyrrolo[2,1-c][1,4]benzodiazepines. Synthesis of new cyclic amidines and fused[a]triazolo,tetrazolo and oxadiazolo derivatives

We report the practical synthesis of new cyclic amidines from thiolactams and the preparation of fused[a]triazolo, tetrazolo and oxadiazolo derivatives via hydrazidines and oximes, in the pyrrolo[2,1-c]-[1,4]benzodiazepine series.     

Thiazolo[4,3-c][1,4]benzodiazepines. I. Synthesis of amidine derivatives

Reactivity of 1,2,3,10,11,11a-hexahydro-5H-thiazolo[4,3-c][1,4]benzodiazepin-5-one-11-thione and 1,2,3,10,11,11a-hexahydro-5H-thiazolo[4,3-c][1,4]benzodiazepine-5,11-dithione was evaluated against various amines. The synthetic pathways involved in these reactions which led to new thiazolo[4,3-c]-[1,4]benzodiazepine amidines are described.     

Synthesis of triazolo[4,3-d], tetrazolo[1,5-a] -and quinazolino[3,2-d] [1,4] benzodiazepines

Treatment of 5-methylmercapto-1,4-benzodiazepine (I) with hydrazine hydrate gave the 5-hydrazino derivative (II, R = H) which, in turn, was conveniently cyclized to the title compounds. Another method for the synthesis of triazolo [4,3-d] [1,4] benzodiazepines (III) is also described.     

Synthesis of substituted furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines and furo[3,2-e]tetrazolo[1,5-c]pyrimidines

A series of substituted furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines and furo[3,2-e]tetrazolo[1,5-c]pyrimidines were obtained from reactions of substituted 2-dimemylamino-4-hydrazmofuro[2,3-d]pyrimidines with orthoesters or sodium nitrite in acetic acid, respectively.     

Synthesis of 5H-tetrazolo[5,1-c][1,4]benzodiazepines

A three step synthesis of 5H-tetrazolo[5,1-c][1,4]benzodiazepin-11-ones 8a-d via the reaction of a substituted benzyl azide and ethyl cyanoformate is described. The derived lactams are converted to the corresponding 11-thiones 9a-d and, through the S-methylated derivatives, to the 11-amino analogs 11a-f. All of the described compounds are representatives of a novel ring system.     

Synthesis of novel imidazo[1,2-a]pyrrolo[2,1-c][1,4]benzodiazepines and pyrimido[1,2-a]pyrrolo[2,1-c][1,4]benzodiazepines

Several 1 1-amino-5H-pyrrolo[2,1-c][1,4]benzodiazepines have been used as starting material to prepare a number of derivatives of 9H-imidazo[1,2-a]pyrrolo[2,1-c][1,4]benzodiazepines and 10H-pyrimido[1,2-a]pyrrolo[2,1-c][1,4]benzodiazepines. The imidazole nucleus was built by reaction of amidines with ethyl bromopyruvate or aminoacetaldehyde dimethylacetal. Several derivatives of imidazo[1,2-a]pyrrolo[2,1-c][1,4]benzodiazepine have been prepared by formylation of the pyrrole ring followed by formation of thioamides. Condensation of 11-amino-5H-pyrrolo[2,1-c][1,4]benzodiazepines with diethyl ethoxymethylenemalonate afforded intermediate diesters which were transformed into the corresponding 10H-pyrimido[1,2-a]pyrrolo[2,1-c]-benzodiazepines.     

Synthesis,reactions, and antimicrobial activity of some novel pyrazolo[3,4-d]pyrimidine,pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine,and pyrazolo[4,3-e][1,2,4]triazolo[3,4-c]pyrimidine derivatives

Treatment of N-phenyl-substituted benzenecarbo-hydrazonoyl chlorides 1a - d with malononitrile in sodium ethoxide solution gave 5-amino-4-cyanopyrazole derivatives 2 - 5 . Compounds 2 - 5 were converted to formidate derivatives 6 - 9 upon treatment with TEOF in acetic anhydride. The reaction of the latter products 6 - 9 with hydrazine hydrate gave imino-amino derivatives 10 - 13 , which was converted to hydrazino derivatives 14 - 17 by refluxing with hydrazine hydrate. Hydrazino as well as imino-amino derivatives undergo condensation, cyclization, and cycloaddition reactions to give pyrazolo[3,4-d]pyrimidine 18 - 21 , pyrazolo[4,3-e][1,2,4]triazolo-[3,4-c]pyrimidine 22 - 27 , and pyrazolo[3′,4′:4,5]pyrimido[1,6-b][1,2,4]triazine 42 - 44 derivatives. Antimicrobial studies are performed using two Gram-positive bacteria and two Gram-negative bacteria. Data indicated that compounds 5 , 28D , 29B , and 31D are exploring elevated antibacterial effects against all strains tested. Compound 28D is the most promising antibacterial agent against the delicate bacterial strain Bacillus subtilis and Pseudomonas aeruginosa with high effectiveness (low minimum inhibitory concentration [MIC] value) 40 and 60 μg/mL, respectively.     

2-Azidopyrrolo[2,1-c][1,4]benzodiazepines. Synthesis of the first cyclic amidine derivatives

We report the practical synthesis of the new 5-azidopyrrolo[2,1-c][1,2,4]triazolo[4,3-a][1,4]benzo-diazepin-8-one and 11-alkylamino-2-azidopyrrolo[2,1-c][1,4]benzodiazepines via the corresponding hydroxy compounds.     

New [g]-fused [1,2,4]triazolo[1,5-c]pyrimidines: Synthesis of pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidine,pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine and [1,2,4]triazolo[1,5-c]pteridine derivatives

A number of 2-aryl-substituted pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidines and [1,2,4]triazolo[1,5-c]pteridines 11,12a,b,e , their corresponding 5-carbonyl derivatives 7,8a,b,e and some pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidin-5-ones 7,8c,d have been synthesized, according to different pathways. The new tricyclic heterocycles were prepared with the aim of studying their possible benzodiazepine receptors affinity.     

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 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 Substituted 5,6-Dihydro-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepines

A one-pot synthetic approach to the novel 5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepines by thermal cyclization of 4-acylhydrazino-2,3-dihydro-1H-1,5-benzodiazepines is described.     

The synthesis of [1]benzothieno[2,3-c]quinolines, [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline,and [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline

Photocyclization of 3-chloro-N-phenylbenzo[b]thiophene-2-carboxamide 10 afforded [1]benzothieno[2,3-c]-quinolin-6(5H)-one 11 which was chlorinated to 6-chloro[1]benzothieno[2,3-c]quinoline 12 followed by dechlorination to give [1]benzothieno[2,3-c]quinoline 5 . A series of 6-substituted alkoxy and thioalkoxy[1]benzothieno[2,3-c]quinoline derivatives were prepared along with the N-methyl quaternary salt 13 of 5 . 6-Chloro[1]-benzothieno[2,3-c]quinoline 12 was converted into 6-hydrazino[1]benzothieno[2,3-c]quinoline 23 which upon treatment with formic acid yielded [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline 6 . Treatment of 23 with nitrous acid resulted in [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline 7 . Compounds 6 and 7 are novel heterocyclic ring systems.     

Synthesis of arylamino-substituted pyrazolo[3,4-d][1,2,4]triazolo[4,3-a]pyrimidinones,pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinones,and their thermal isomerization

The reaction of 1-(4-oxo-1-R-5H-pyrazolo[3,4-d]pyrimidin-6-yl)-4-arylthiosemicarbazides with methyl iodide gave rise to 1,2,4-triazolo-pyrazolopyrimidinones of linear structure, and with dicyclohexylcarbodiimide the products had angular and linear structure. The heating of compounds obtained higher than their melting point resulted in their isomerization into 7-aryl-amino-1-R-1,8-dihydro-4H-pyrazolo[3,4-d]-[1,2,4]triazolo[1,5-a]pyrimidin-4-ones.     

New Facile Route to Synthesize Furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidine and Furo[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine Derivatives

A new facile route for synthesis of 3-(aryl)-8,9-diphenylfuro[3,2-e][1,2,4]triazolo pyrimidines derivative from the same starting material, 2-amino-4,5-diphenylfuran-3-carbonitrile, has been developed through heterocyclization of the corresponding arylidene-hydrazono-5,6-diphenylfuro[2,3-d]pyrimidine and N-(arylmethylene)-4-imino-5,6-diphenylfuro[2,3-d]pyrimidin-3(4H)-amine under refluxing condition with acetic anhydride followed by air oxidation. The products were obtained in good yield with an easy workup along with the purification of products by a nonchromatographic method. This general synthetic procedure can be extended to the preparation of a wide range of isomeric triazoles using 2-amino 3-carbonitrile bifunctional derivatives.     

New polyazaheterocycles. 9-Methyl-di-s-triazolo[4,3-a:4,3-c]pyrimidine and 9-methyl-s-triazolo[4,3-c]tetrazolo[1,5-a]pyrimidine

9-Methyl-di-s-triazolo[4,3-a:4,3-c]pyrimidine and 9-methyl-s-triazolo[4,3-c]tetrazolo[1,5-a]pyrimidine have been synthetized from 4-hydrazino-7-methyl-s-triazolo[4,3-c]pyrimidine. Structural assignments based on nmr, ir and chemical manipulations are discussed.     

Pyrazoles as building blocks in heterocyclic synthesis: Synthesis of pyrazolo [3,4-d]pyrimidine, pyrazolo[3,4-e][1,4]diazepine, pyrazolo [3,4-d][1,2,3]triazine and pyrolo [4,3-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives

Several new pyrazolo[3,4-d]pyrimidine, pyrazolo[3,4-e][1,4]diazepine, pyrazolo[3,4-d][1,2,3]triazine and pyrolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives were prepared by the reaction of the corresponding 5-amino-pyrazole-4-carbonitrile derivative with different organic reagents under different reaction conditions. Using IR, ¹H NMR, and mass spectra we have characterized all new compounds.     

Studies on mechanisms of the rearrangement of thieno[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines into thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines

Recyclization of thieno[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines was studied experimentally and theoretically by B3LYP/6-31G** calculations in the gas phase and in solution (EtOH). The experimentally observed characteristic features of the isomerization (the possibility of the Dimroth rearrangement occurring by the ANRORC mechanism and high energy barriers in acid-catalyzed reactions) were confirmed by quantum chemical calculations. Substituents in the triazole ring were found to play the principal role in the rearrangement. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2164–2171, December, 2006.     

Synthesis and anticonvulsant activities of 5-(2-Chlorophenyl)-7H-pyrido[4,3-f][1,2,4]triazolo[4,3-a][1,4]diazepines

A group of 5-(2-chlorophenyl)-10-(substituted)-7H-pyrido[4,3-f][1,2,4]triazolo[4,3-a][1,4]diazepines 7a-c were synthesized by the acid catalyzed reaction of 5-(2-chlorophenyl)-2-hydrazino-3H-pyrido[3,4-e]-[1,4]diazepine ( 6 ) with either trimethyl orthoformate, triethyl orthoacetate or triethyl orthobenzoate, respectively. 5-(2-Chlorophenyl)-7H-pyrido[4,3-f][1,2,4]triazolo[4,3-a][1,4]diazepine ( 7a ) and 5-(2-chlo-rophenyl)-10-methyl-7H-pyrido[4,3-f][1,2,4]triazolo[4,3-a][1,4]diazepine ( 7b ) exhibited good anticonvulsant activity in the subcutaneous metrazol anticonvulsant screen which serves as a model for absence (petit mal) epilepsy.