Synthesis and Antimicrobial Activity of Some New 5-Arylazothiazole,Pyrazolo[1,5-a] Pyrimidine, [1,2,4]Triazolo[4,3-a]Pyrimidine,and Pyrimido[1,2-a]Benzimidazole Derivatives Containing the Thiazole Moiety

1-(2-(4,5-Dihydro-3-(4-methyl-2-phenylthiazol-5-yl)-5-phenylpyrazol-1-yl)-4-substituted thiazol-5-yl)-2-phenyldiazene were synthesized from hydrazonoyl halides and 3-(4-methyl-2-phenyl-1,3-thiazol-5-yl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide in ethanolic triethylamine. Also, pyrazolo[5,1-a]pyrimidines, 2,3,6-trisubstituted pyridines, and pyrazolo[3,4-d]pyridazines were obtained from sodium salt of 3-hydroxy-1-(4-methyl-2-phenylthiazol-5-yl)prop-2-en-1-one and different heterocyclic amines. All structures of the newly synthesized compounds were elucidated by elemental analysis, spectral data, and alternative synthetic route whenever possible. The newly synthesized compounds were tested towards different microorganisms.

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Reactions of 4-methylidenedioxolan-2-ones with 2-methyltryptamines. Synthesis of core analogs of aurantioclavine

4-Hydroxy-4,5,5-trimethyl-3-[2-(2-methyl-7-R-1H-indol-3-yl)ethyl]-1,3-oxazolidin-2-ones (R = H or Alk), which were synthesized from 4-methylidene-1,3-dioxolan-2-one and substituted 2-methyltryptamines, undergo intramolecular amidoalkylation when treated with polyphosphoric acid. First representatives of a new heterocyclic system, viz., oxazolo[3",4":1,2]azepino[5,4,3-cd]indole, which are core analogs of aurantioclavine, were prepared.     

Investigation of the preparation of pyrimidine isocyanates

Uracil-5-yl isocyanate and 1,3-dimethyluracil-5-yl isocyanate were prepared from the corresponding new carboazides. 1,3-Dimethyluracil-5-ylmethyl isocyanate obtained from the chloro compound and silver cyanate, was polymerized with an anionic initiator to the cyclic trimer. Attempts to isolate uracil-6-yl isocyanate, 1,3-dimethyluracil-6-yl isocyanate, pyrimidinyl-4-isocyanate, and 2,6-dichloropyrimidinyl-4-isocyanate were unsuccessful. Ethyl carbamate derivatives were made from all new azides and isocyanates. Other new pyrimidine derivatives included N,N'-bis(pyrimidine-4-carbonyl)hydrazine, N,N'-bis(1,3-dimethyluracil-5-yl)urea, N,N'-bis(1,3-dimethyluracil-6-yl)urea and N,N'-bis(2,5,6-trichloro-4-pyrimidinyl)oxamide.     

Synthesis of Some New Thiazoles and Pyrazolo[1,5-a]pyrimidines Containing an Antipyrine Moiety

Ethyl 2-{2-[4-(2,3-dimethyl-5-oxo-1-phenyl-3-(pyrazolin-4-yl)]-2-cyano-1-(phenylamino)vinylthio}-acetate, 2-[4-(2,3-dimethyl-5-oxo-1-phenyl-(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]2-(4-oxo-3-phenyl-(1,3-thiazoilidin-2-ylidene))ethanenitrile, 2-[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]-2-(4-methyl-3-phenyl(1,3-thiazolin-2-ylidene))ethanenitrile, 2-(5-acetyl-4-methyl-3-phenyl(1,3-thiazolin-2-ylidene))-2-[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]ethanenitrile, and ethyl 2-(cyano(4-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)thiazol-2-yl)methylene)-2,3-dihydro-4-methyl-3-phenylthiazole-5-carboxylate were synthesized by treatment of 2-(4-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)thiazol-2-yl)-3-mercapto-3-(phenylamino)-acrylonitrile with appropriate halo ketones or halo esters. Also, 4-{2-[5,7-dimethyl-2-(phenylamino)(7a-hydropyrazolo[1,5-a]pyrimidin-3-yl](1,-thiazol-4-yl)}-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one derivatives were synthesized via reaction of 4-{2-[5-amino-3-(phenylamino)pyrazolin-4-yl](1,3-thiazol-2-yl)}-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one with β-diketone or β-keto ester. All synthesized compound were established by elemental analysis, spectral data, and alternative synthesis whenever possible.     

Halocyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">de</Emphasis>]isoquinoline-1,3(2<Emphasis Type="Italic">H</Emphasis>)-dione

Cyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione by the action of iodine, bromine, or sulfuryl chloride gave 2-(2-{4-[4,5-dihydro-5-(halomethyl)-thiazol-2-yl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione hydrohalides which were converted into 2-{2-[4-(5-methylthiazol-2-yl)piperazin-1-yl]ethyl}-1H-benzo[de]isoquinoline-1,3(2H)-dione.     

New 7-substituted quinolone antibacterial agents. II. The synthesis of 1-ethyl-1,4-dihydro-4-oxo-7-(pyrazolyl,isoxazolyl, and pyrimidinyl)-1,8-naphthyridine and quinolone-3-carboxylic acids

Synthetic methods for the construction of certain aromatic heterocyclic side chains for the quinolone anti-bacterials have been provided. In particular a series of 7-(pyrazol-3 or 4-yl, 4- or 5-isoxazolyl and 4- or 5-pyrimidinyl)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine and quinoline-3-carboxylic acids have been prepared. All of the heterocycles were prepared from masked 1,3-dicarbonyl derivatives of nalidixic acid ( 9,17 ) or 7-acetyl-1-ethyl-1,4-dihydro-4-oxo-3-quinoline carboxylic acids ( 8 ). These masked 1,3-dicarbonyl derivatives were prepared by the use of t-butoxy-bis-dimethylaminomethane on the activated methyls of 9,19 and 8 . The pyrimidinyl analogs, substituted with a 2-amino or a 2-aminomethyl moiety, were the only derivatives with substantial antibacterial activity.     

Synthesis and microbial screening of 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives

The present investigation describe the synthesis of 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives. Quinolin-8-ol was transformed by five step synthetic procedures into 8-Benzyloxy-5-(2-bromo-acetyl)-1H-quinolin-2-one. Subsequently, 8-Benzyloxy-5-(2-bromo-acetyl)-1H-quinolin-2-one condensed with 1,3-Diphenyl-1H-pyrazole-4-carbothioic acid amide in the presence of acetonitrile to afford 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives. Synthesized compounds were screened for their antimicrobial activity against gram-positive and gram-negative bacteria. Most of the synthesized compounds are found to be active against tested bacterial strains and fungal strain.     

Synthesis of pyrrolo[1,2-a]quinoxalines by 1,3-dipolar cycloaddition reaction. An additional reaction mechanism via an aziridine intermediate

The reaction of the 2-substituted 6-chloroquinoxaline 4-oxides 1a or 1b with 2-fold molar amount of methyl propiolate resulted in the 1,3-dipolar cycloaddition reaction to give 8-chloro-1,3-bismethoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 4a or 8-chloro-1,3-bismethoxycarbonyl-4-(morpholin-4-yl)pyrrolo-[1,2-a]quinoxaline 4b , respectively. Compound 4a or 4b was transformed into 8-chloro-3-methoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 5a or 8-chloro-3-methoxycarbonyl-4-(morpholin-4-yl)pyrrolo[1,2-a]-quinoxaline 5b , respectively. The structure of 4a,b was confirmed by the NOE measurement among the C₁ -H , C ₂-H and C ₉-H proton signals of 5a,b . An additional reaction mechanism was proposed for the ring transformation of isoxazolo[2,3-a]quinoxalines into pyrrolo[1,2-a]quinoxalines.     

Synthesis and Reactions of 5-Amino-3-(3-methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-7-phenyl-7 H -thiazolo[3,2- a ]pyrimidine-6-carbonitrile

5-Amino-3-(3-methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-7-phenyl-7H-thiazolo[3,2-a]pyrimidine-6-carbonitrile was synthesized via the reaction of 4-(2-aminothiazol-4-yl)-3-methyl-1-phenyl-2-pyrazolin-5-one with benzylidene malononitrile and was then transformed to related fused heterocyclic systems. The antifungal and antibacterial studies revealed in some cases excellent biocidal properties.     

Synthesis and Reactions of 5-Amino-3-(3-methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-7-phenyl-7<Emphasis Type="Italic">H</Emphasis>-thiazolo[3,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-6-carbonitrile

Summary. 5-Amino-3-(3-methyl-5-oxo-1-phenyl-2-pyrazolin-4-yl)-7-phenyl-7H-thiazolo[3,2-a]pyrimidine-6-carbonitrile was synthesized via the reaction of 4-(2-aminothiazol-4-yl)-3-methyl-1-phenyl-2-pyrazolin-5-one with benzylidene malononitrile and was then transformed to related fused heterocyclic systems. The antifungal and antibacterial studies revealed in some cases excellent biocidal properties.     

Studies on the synthesis of heterocyclic compounds. Part IV. Further investigation of the pschorr reaction with some pyrazole derivatives

Thermal decomposition of the diazonium sulfate derived from N-methyl-(1-phenyl-3-methylpyrazol-5-yl)-2-aminobenzamide afforded products formulated as 1-phenyl-3-methyl[2]benzopyrano[4,3-c]pyrazol-5-one (yield 10%), 1,4-dimethyl-3-phenylpyrazolo[3,4-c]isoquinolin-5-one (yield 10%), N-methyl-(1-phenyl-3-methylpyrazol-5-yl)-2-hydroxybenzamide (yield 8%) and 4′-hydroxy-2,3′-dimethyl-1′-phenylspiro[isoindoline-1,5′-[2]-pyrazolin]-3-one (yield 20%). Decomposition of the diazonium sulfate derived from N-methyl-(1,3-diphenylpyrazol-5-yl)-2-aminobenzamide gave products formulated as 7,9-dimethyldibenzo[e,g]pyrazolo[1,5-a][1,3]-diazocin-10-(9H)one (yield 8%), 4-methyl-1,3-diphenylpyrazolo[3,4-c]isoquinolin-5-one (yield 7%) and 4′-hydroxy-2-methyl-1′,3′-diphenylspiro[isoindoline-1,5′-[2]pyrazolin]3-one (yield 10%). The spiro compounds 6a,b underwent thermal and acid-catalysed conversion into the hitherto unknown 2-benzopyrano[4,3-c]pyrazole ring system 7a,b in good yield. Analytical and spectral data are presented which supported the structures proposed.     

Synthesis of fluoroquinoxalin-2(1<Emphasis Type="Italic">H</Emphasis>)-one derivatives containing substituents in the pyrazine and benzene fragments

6,7-Difluoroquinoxalin-2-one reacted with indoles, 5,5-dimethylcyclohexane-1,3-dione, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, resorcinol, and pyrogallol on heating in acetic acid to give products of hydrogen substitution in the heterocyclic fragment. Heating of 6,7-difluoro-3-(1H-indol-3-yl)quinoxalin-2(1H)-ones with N-methylpiperazine gave the corresponding 7-(4-methylpiperazin-1-yl) derivatives.     

Azines and azoles: CXXVI. First example of a novel heterocyclic system: Pyrimido[1,6-<Emphasis Type="Italic">a</Emphasis>][1,5]benzodiazepines

4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones readily undergo acylation at the N¹ atom of the benzodiazepine system by the action of acetic anhydride. Heating of the acetylated products in boiling dimethylformamide leads to the formation of 75–93% of the corresponding 7-acetyl-6-R-6,7-dihydropyrimido[1,6-a][1,5]benzodiazepine-1,3-diones that are derivatives of hitherto unknown fused heterocyclic system, pyrimido[1,6-a][1,5]benzodiazepine. 4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones are converted into 1-(2-aminophenyl)-6-(2-R-vinyl)uracils on heating in boiling DMF.     

Bildung von 5,6-Dihydro-1,3(4H)-thiazin-4-carbonsäure-estern aus 4-Allyl-1,3-thiazol-5(4H)-onen

Formation of Methyl 5,6-Dihydro-l, 3(4H)-thiazine-4-carboxyiates from 4-Allyl-l, 3-thiazol-5(4H)-ones . The reaction of N-[1-(N, N-dimethylthiocarbamoyl)-1-methyl-3-butenyl]benzamid ( 1 ) with HCl or TsOH in MeCN or toluene yields a mixture of 4-allyl-4-methyl-2-phenyl-1,3-thiazol-5(4H)-one ( 5a ) and allyl 4-methyl-2-phenyl-1,3-thiazol-2-yl sulfide ( 11 ; Scheme 3). Most probably, the corresponding 1,3-oxazol-5(4H)-thiones B are intermediates in this reaction. With HCl in MeOH, 1 is transformed into methyl 5,6-dihydro-4,6-dimethyl-2-phenyl-1,3(4H)-thiazine-4-carboxylate ( 12a ). The same product 12a is formed on treatment of the 1,3-thiazol-5(4H)-one 5a with HCl in MeOH (Scheme 4). It is shown that the latter reaction type is common for 4-allyl-substituted 1,3-thiazol-5(4H)-ones.     

Benzo-1,2,3,4-tetrazine 1,3-dioxides annulated with tetraazapentalene systems

Thermolysis of 7-azido-6-(2H-1,2,3-triazol-2-yl)-1,2,3,4-benzotetrazine 1,3-dioxide and 7-azido-6-(1H-1,2,3-triazol-1-yl)-1,2,3,4-benzotetrazine 1,3-dioxide gives rise to the new heterocyclic systems: 6,10-dehydro-6H,10H-[1,2,3]triazolo[1′,2′:2,3][1,2,3]triazolo[4,5-g]-[1,2,3,4]benzotetrazine 2,4-dioxide and 6,8-dehydro-6H,8H-[1,2,3]triazolo[1′,2′:1,2][1,2,3]-triazolo[4,5-g][1,2,3,4]benzotetrazine 2,4-dioxide, respectively, their thermal stability and spectral properties have been studied.     

Five-Membered 2,3-Dioxo Heterocycles: XLVI. Reaction of 5-Aryl-4-quinoxalinyl-2,3-dihydrofuran-2,3-diones with Aldehydes and Ketones. Molecular and Crystalline Structure of 5-(3-p-Tolylquinoxalin-2-yl)-4H-1,3-dioxine- 2-spiro-2'-adamantan-4-one

Aroyl(quinoxalinyl)ketenes generated by thermolysis of 5-aryl-4-(3-arylquinoxalin-2-yl)-2,3-di-hydrofuran-2,3-diones act as dienes in [4 + 2]-cycloaddition at the carbonyl group of aldehydes and ketones to afford 2-substituted 6-aryl-5-(3-arylquinoxalin-2-yl)-4H-1,3-dioxin-4-ones. The structure of 5-(3-p-tolylquino-xalin-2-yl)-4H-1,3-dioxine-2-spiro-2'-adamantan-4-one was proved by X-ray analysis.     

Impact of Geometric Parameters,Charge, and Lipophilicity on Bioactivity of Armed Quinoxaline,Benzothiaole, and Benzothiazine: Pom Analyses of Antibacterial and Antifungal Activity

Abstract

A series of four different armed heterocyclic candidates; 1-(2-methyl-2,3-dihydro-1,3-benzothiazol-2-yl)acetone (2), 1-(3-methyl-4H-1,4-benzothiazin-2-yl)ethanone (3), 2-[(2-aminophenyl)dithio]aniline (4), and 3-hydroxy-3-methyl-4-(3-methyl-2-quinoxalinyl)-2-butanone (5) have been prepared and their microbial activities were evaluated. A correlation of the structure and activities relationships of these compounds with respect to molecular modeling, Lipinski Rule of Five, drug likeness, toxicity profiles, and other physico-chemical properties of drugs are described and verified experimentally.     

Synthesis of 3-[4-(1-Benzofuran-2-yl)-1,3-thiazol-2-yl]-2-(4-aryl)-1,3-thiazolidin-4-one Derivatives as Biological Agents

A protocol for the synthesis of 3-[4-(1-benzofuran-2-yl)-1,3-thiazol-2-yl]-2-(4-aryl)-1,3-thiazolidin-4-one derivatives (5a–e) has been developed from 1-(1-benzofuran-2-yl)-2-bromoethanone (2),which served as a key intermediate for the synthesis of the title compounds. The reaction of compound 2 with thiourea furnished 4-(1-benzofuran-2-yl)-1,3-thiazol-2-amine 3, which upon further reaction with various aromatic aldehydes, gave Schiff bases 4a–e. These Schiff bases, when treated with thioacetic acid in the presence of catalytic amount of anhydrous ZnCl₂, yielded thiazolidinone derivatives 5a–e. All the newly synthesized compounds have been characterized by analytical and spectral data and screened for their antimicrobial and analgesic activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

A new facile synthesis of 5-arninopyridazine-4-carboxylic acid

Hofmann rearrangement of 5-carbamylpyridazine-4-carboxylic acid ( 6 ), obtained from pyrida-zine-4,5-dicarboxylic acid ( 3 ) through the corresponding anhydride ( 5 ), afforded 5-aminopyrida-zine-4-carboxylic acid ( 1 ) in good yield. Compound 1 cyclised with benzoyl chloride in pyridine to give 2-phenylpyridazino[ 4 ,5-d]-1,3-oxazin-4-one ( 7 ), a new heterocyclic ring system. J. Heterocyclic Chem., 14, 1099 (1977)     

Benzo-1,2,3,4-tetrazine 1,3-dioxides annulated with tetraazapentalenes

New heterocyclic system, viz., 8,12-dehydro-8H,12H-[1,2,3]triazolo[2′,1′:1,2][1,2,3]triazolo-[4,5-f][1,2,3,4]benzotetrazine 2,4-dioxide, has been synthesized by thermolysis of 5-azido-6-(1,2,3-triazol-2-yl)benzotetrazine 1,3-dioxide, and its thermal stability and spectral properties have been studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 186–188, January, 2008.