Studies on the synthesis and interconversion of isomeric triazolotheinopyrimidines. Part II. Effect of 5-substituents on the dimroth rearrangement of 1,2,4-triazolo[4,3-c]thieno[3,2-e]pyrimidines

The triazolothienopyrimidines obtained by the cyclization of 4-hydrazino-2-phenylthieno[2,3-d]pyrimidines with triethyl orthoformate or formic acid presumed to be the triazolo[2,3-c] isomers are now assigned the 5-phenyl-1,2,4-triazolo[4,3-c]thieno[3,2-e]pyrimidine structure. While these [4,3-c]triazoles resist isomerization under acidic conditions, they undergo isomerization to 5-phenyl-1,2,4-triazolo[2,3-e]thieno[3,2-e]pyrimidines under basic conditions.     

Derivatives of Condensed Thienopyrimidimines. 13. Synthesis and Structure of Pyrano[4',3':4,5]thieno[3,2-e]-1,2,4-triazolo[2,3-c]pyrimidines

Methods for the synthesis of 5-substituted 10,10-dimethyl-10,11-dihydro-8H-pyrano[4',3':4,5]thieno[3,2-e]-1,2,4-triazolo[2,3-c]pyrimidines have been developed. An X-ray crystallographic study of 5-(2-ethoxymethylhydrazino)-10,10-dimethyl-10,11-dihydro-8H-pyrano[4',3':4,5]thieno[3,2-e]-1,2,4-triazolo[2,3-c]pyrimidine has been carried out.     

Thienopyrimidines. VII. Reactions of the 4-hydrazinothieno[2,3-d]pyrimidines

The cyclization reactions of the 4-hydrazinothieno[2,3-d]pyrimidines give s-triazolo[1,2-c]-thieno[3,2-e]pyrimidines and tetrazolo[1,5-c]thieno[3,2-e]pyrimidines.     

Synthesis of 5H-Triazolo[1,5-d]- and 5H- Tetrazolo- [1,5-d]thieno[3,2-f]-1,4-diazepin-6(7H)-ones

5H-Triazolo[1,5-d]- and 5H-tetrazolo[1,5-d]thieno[3,2-f]-1,4-diazepin-6(7H)-ones have been obtained by the base catalysed ring expansion reaction of 5-chloromethyl-1,2,4-triazolo[1,5-c]- and 5-chloromethyltetrazolo- [1,5-c]thieno[3,2-e]pyrimidines. The required thienopyrimidine derivatives were synthesized from 2-amino-3-triazolyl- and 2-amino-3-tetrazolylthiophenes by acylation, followed by dehydrative cyclization.     

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.     

On triazoles. X. The reaction of 5-amino-1,2,4-triazoles with tetrahydrothiophene β-keto esters

Three novel ring systems, namely the thieno[3,4-d]-1,2,4-triazolo[1,5-a]pyrimidine, the thieno[3,4-e]-1,2,4-triazolo[1,5-a]pyrimidine and the thieno[3,2-d]-1,2,4-triazolo[1,5-a]pyrimidine were synthesised. The structure of compounds obtained was proved with the help of their uv and cmr spectra using model compounds prepared for this purpose.     

A convenient synthesis for some new pyrido[3′,2′:4,5]thieno-[3,2-d]pyrimidine derivatives with potential biological activity

Ready, convenient synthesis for 8-cyano-7-ethoxy-4-oxo-9-phenyl-2-substituted-1,2,3,-4-tetrahydropyrido-[3′,2′:,4,5]thieno[3,2-d]pyrimidines 5 , 8-cyano-7-ethoxy-4-oxo-9-phenyl-2-substituted-3,4-dihydropyrido[3′,2-: 4,5]thieno[3,2-d]pyrimidines 6 , 4-chloro-8-cyano-7-ethoxy-9-phenyl-2-substitutedpyrido[3′,2′:4,5]thieno[3,2-4 -pyrimidines 7 and 8-cyano-7-ethoxy-2-(2′-nitrophenyl)-9-phenyl-4-substitutedpyrido[3′,2′:4,5]thieno[3,2- d ]pyrimidines 8-18 from 2-chloro-3,5-dicyano-6-ethoxy-4-phenylpyridine 1 via 3,5-dicyano-6-ethoxy-2-mercapto-4-phenylpyridine 2 and aminocarboxamide 4 are reported. In addition, the reaction of hydrazino derivative 12 with reagents such as formic acid and triethyl orthoformate yielded the fused tetraheterocyclic 8-cyano-9- ethoxy-5-(2′-nitrophenyl)- 7-phenylpyrido[3′,2′:4,5]thieno[2,3-e]-1, 2,4-triazolo[4,3-c]pyrimidine system 19 .     

On triazoles XXIII [1]. The reaction of 5-amino-1,2,4-triazoles with thiacyclohexane β-oxo esters [2]

Six novel isomeric ring systems, namely the thiopyrano[4,3-d]-1,2,4-triazolo[1,5-a]pyrimidine, the thiopyrano[3,4-e]-1,2,4-triazolo[1,5-a]pyrimidine, the thiopyrano[3,4-d]-1,2,4-triazolo[1,5-a]pyrimidine, the thiopyrano[4,3-e]-1,2,4-triazolo[1,5-a]pyrimidine, the thiopyrano[3,2-d]-1,2,4-triazolo[1,5-a]pyrimidine and the thiopyrano[2,3-e]-1,2,4-triazolo[1,5-a]pyrimidine were synthesised. Spectroscopical evidence was given for the structure of compounds obtained.     

Reaction of 1-hetaryl-4-phenylthiosemicarbazides with <Emphasis Type="Italic">N,N′</Emphasis>-dicyclohexylcarbodiimide

1,2,4-Triazolo[3,4-b][1,3]benzothiazole, 1,2,4-triazolo[4,3-a]pyrimidine, and thieno[3,2-e][1,2,4]-triazolo[4,3-a]pyrimidine derivatives were synthesized by reactions of 1-hetaryl-4-phenylthiosemicarbazides with N,N′-dicyclohexylcarbodiimide.     

Synthesis and structure of some thienopyrimidine derivatives

A series of substituted thieno[2,3-d]pyrimidines was synthesized starting from ethyl-2-amino-4-isopropylthiophene-3-carboxlate. Reaction of 2-hydrazino-5-isopropyl-thieno[2,3-d]pyrimidin-4(3H)-one and its 3-methyl analogue with different reagents afforded thieno[2,3-d]triazolo[4,3-a]pyrimidines and thieno[3,2-e]triazolo[4,3-a]pyrimidines, beside open chain derivatives. Correspondence: Atef A. Hamed, Department of Chemistry, Faculty of Science, Menoufia University, Shebin El Koam, Egypt.     

Synthesis of tetracyclic thienotriazolopyridines based on hydrazine derivatives of fused pyridinethiones

A method for the synthesis of hydrazine derivatives of fused pyridinethiones based on alicyclic and heterocyclic ketones has been developed. Successive heterocyclization of these hydrazine derivatives was carried out in order to obtain new derivatives of tricyclic triazolo[4,3-a]pyridines, tetracyclic thieno[3,2-e][1,2,4]triazolo[4,3-a]pyridines, as well as a new heterocyclic system of thieno[2,3-c][1,2,4]triazolo[3,4-a]-2,7-naphthyridine.

     

Intramolecular 4+2 cycloaddition of thieno[2,3-e][1,2,4]triazines: routes towards condensed thieno[2,3-b]pyridines

Synthetic approaches towards new condensed thienopyridine ring systems including furo[2,3-b]thieno[3,2-e]pyridines, bisthieno[2,3-b:3′,2′-e]pyridines, 5H-chromeno[2,3-b]thieno[3,2-e]pyridines, 5H-benzo(f)chromeno[2,3-b]thieno[3,2-e]pyridines have been achieved by application of intramolecular 4+2 cycloaddition reactions of suitably designed thieno[2,3-e][1,2,4]triazines tethered with alkene or alkyne terminals.     

Gas-phase thermolysis of thieno[3,2-e][1,2,4]triazines. Interesting routes towards heterocyclic ring systems

Gas-phase thermolysis of thieno[3,2-e][1,2,4]triazines gave benzonitrile, isothiazole, pyrimidine, [1]benzothieno[2,3-d]pyrimidine and thieno[3,2-d]thiazole derivatives. A mechanism of these pyrolytic transformation was proposed. Two new and efficient syntheses of the starting thieno[3,2-e][1,2,4]triazines were reported.     

Synthesis,Reactions, and Antimicrobial Evaluation of Some Polycondensed Thienopyrimidine Derivatives

Some novel indeno[2,1-b]thiophenes, indeno[1′,2′:4,5]thieno[2,3-d][1,2,3]triazines, indeno[1′,2′:4,5]thieno[2,3-d]pyrimidines, indeno[1′,2′:4,5]thieno[2,3-d][1,3]thiazolo[3,2-a]pyrimidines, and indeno[1′,2′:4,5]thieno[2,3-d][1,2,4]triazolo[4,3-a]pyrimidines 2–16 were prepared starting with 2-aminoindeno[2,1-b]thiophene-3-carboxylic acid amide ( 1 ). Furthermore, the antimicrobial evaluation of the prepared products showed that many of them revealed promising antimicrobial activity.     

Condensed Pyridopyrimidines. 7. Synthesis of Condensed Triazolo[4,3-c]- and Tetrazolo[1,5-c]pyrimidines

Novel dihydro-5H-pyrano[3',4':5',6']pyrido[2,3-d]-1,2,4-triazolo[4,3-c]pyrimidines and 1,2,3,4-tetrazolo[1,5-c]pyrimidines have been synthesized from 2-amino-3-cyano-7,7-dimethyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine.     

Synthesis of 2,8-disubstituted 1,2,4-triazolo[5,1-i]purines

This paper describes the preparation of 2-aryl-8-fluorobenzyl-1,2,4-triazolo[5,1-i]purines 2 , starting from 2-aryl-7,8-diamino-1,2,4-triazolo[1,5-c]pyrimidines 9 . Our synthetic procedure represents the first example of a feasible approach for the synthesis of 2,8-disubstituted triazolo[5,1-i]purines. New syntheses of 5-amino-3-arylpyrimido[5,4-e]1,2,4-triazines 12 and 8-fluorobenzyl-6-hydrazinopurines 15 are also reported.     

Synthese neuer Derivate des 2-Amino-4,5,6,7-tetrahydro-benzo[b]thiophen-3-carbonitrils: basische Substitutions-produkte und anellierte Thieno-[1,2,4]-triazolo-pyrimidine

A group of N-substituted 2-aminoacylamino-4,5,6,7-tetrahydro-benzo[b]thiophene-3-carbonitriles (1) was prepared from 2-amino-4,5,6,7-tetrahydro-benzo[b]thiophen-3-carbonitrile (A ¹).Cyclisation reactions usingA ¹ and N-heterocyclic analogues thereof (A ² andB ³) as starting materials gave derivatives of the following two new heterocyclic ring systems: [1]benzo-thieno[3,2-e][1,2,4]-triazolo[2,3-c]pyrimidine (B) and pyrido-[4,34,5]thieno[3,2-e][1,2,4-triazolo][2,3-c]pyrimidine (C).

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Unserem verehrten Lehrer, Herrn o. Prof. Dr.O. Hromatka, in Dankbarkeit zum 70. Geburtstag gewidmet.     

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.     

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 of 5-Thioxo-hexahydrobenzo[b]thiopheno[2,3-d]-1,2,4-triazolo[1,5-c]pyrimidines and Related Compounds Based on Cyclocondensations of 2-Isothiocyanato-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene

5-Thioxo-4,6,8,9,10,11-hexahydro-benzo[b]thiopheno[2,3-d]-1,2,4-triazolo[1,5-c]pyrimidines and related compounds were prepared based on cyclizations of 2-isothiocyanato-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene with aminoketones and carboxylic hydrazides.