A REGIOSPECIFIC SYNTHESIS OF 1-HETEROCYCLIC SUBSTITUTED 1,2,4-TRIAZOLES VIA ADDITION REACTION OF 1,2,4-TRIAZOLE WITH FUNCTIONALIZED CARBODIIMIDE

ABSTRACT

The reaction of 1,2,4-triazole with functionalized carbodiimide 2 or 6 under solid K₂CO₃ provide a convenient and regiospecific route to 1-(2-imidazolonyl)-1,2,4-triazole 4 or 1-(2-quinazolonyl)-1,2,4-triazole 8.     

Regioselective annelation of 3-(prop-2-ynylsulfanyl)-1,2,4-benzotriazine to thiazolo[2,3-c][1,2,4]benzotriazine

Summary Thiosemicarbazide reacted with 1,2-diaminobenzene to give 1,2-dihydro-3-thioxo-1,2,4-benzotriazine (1) in fairly good yield in a solvent free reaction under microwave irradiation.1 was condensed with prop-2ynyl bromide in the presence of sodium methoxide to afford the corresponding 3-(prop-2-ynylsulfanyl)-1,2,4-benzotriazine (5). Transformation of5 to 3-methylidene-2,3-dihydro-9H-thiazolo[2,3-c][1,2,4]benzotriazine (6) was performed in the presence of a palladium salt.

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Regioselektive Anellierung von 3-(prop-2-inylsulfanyl)-1,2,4-benzotriazin zu Thiazolo[2,3-c][1,2,4]benzotriazin

Zusammenfassung Thiosemicarbazid reagierte mit 1,2-Diaminobenzol ohne Lösungsmittel und unter Bestrahlung mit Mikrowellen in guter Ausbeute zu 1,2-Dihydro-3-thioxo-1,2,4-benzotriazin (1), welches in Gegenwart von Natriummethoxid mit Prop-2-inylbromid zum entsprechenden 3-(Prop-2-inylsulfanyl)-1,2,4-benzotriazin (5) kondensiert wurde. Die Umsetzung von5 zu Methyliden-2,3-dihydro-9H-thiazolo[2,3-c] [1,2,4]benzotriazin (6) gelang unter Palladiumkatalyse.

     

Synthesis of fused 1,2,4-triazines as potential antimicrobial and antitumor agents

5-Benzylidene-3-(p-chlorophenyl)-2-aminothiocarbonyl-1,2,4-triazine (2) was prepared via condensation of oxazolinone (1) with thiosemicarbazide. Fused 1,2,4-triazine derivatives (3, 4 and 9) were synthesized from the reaction of compound 2 with ω-bromomethyl aryl ketones, ethyl chloroacetate, and acetic anhydride. Treatment of 4 with acetic anhydride and aromatic aldehydes yielded the corresponding acetyl, diacetyl derivatives (6 and 7) and 7-benzylidene-5-(p-chlorophenyl)-4-thioxo-3-arylidene-1,2,4-triazino [2,1-a]-1,2,4-triazine-1,8-diones (8). The electron impact mass spectra of both the above series of compounds have also been recorded and their fragmentation pattern is discussed. All synthesized fused 1,2,4-triazine derivatives were primary in vitro screened for their antimicrobial and antitumor activity.

     

Convenient Synthesis of Some 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines Bearing 3-Methylthio{7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl}moiety as Possible Antimicrobial Activity

4-Amino-4H-3-methylthio{7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl}-1,2,4-triazole-5thi-ol (1) was condensed with various substituted aromatic aldehydes or acid chlorides to yield a series of arylideneamines 2 or aroylamines 3. These were easily cyclized to the corresponding 6-aryl-3-methylthio7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl-1,2,4-triazolo [3,4-b]-1,3,4-thiadiazoles (4) on treatment with palladium-on-charcoal or phosphorus oxychloride. Compounds 4 were also prepared directly via the reaction of 1 with aromatic carboxylic acids in the presence of phosphorus oxychloride. Cyclocondensation of 1 with a variety of two-carbon cyclizing reagents, namely chloroacetone, pyruvic acid, benzoylformic acid, and benzoin led to the formation of 3-methylthio{7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl}-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines (5?8). Some of the newly synthesized compounds were tested for their antibacterial and antifungal activity against a variety of microorganisms.     

ONE-POT SYNTHESIS OF 1,2,4-TRIAZINES

ABSTRACT

1,2,4-Triazines have been prepared from the one-pot condensation reaction of acid hydrazide (1), ammonium acetate and dicarbonyl compounds (2) on the surface of silica gel in the presence of triethylamine under microwave irradiation.     

Studies in the field of pyridazine compounds, 20. 6H-1,2,4-Triazino[4,3—b]1,2,4-triazolo[3,4—f]pyridazine,a novel angular ring system

The novel ring system, 6H-1,2,4-triazino[4,3—b]1,2,4-triazolo[3,4—f]-pyridazine was prepared either by ring closure of1-(1-ethoxycarbonylethylene)-2-(1,2,4-triazolo[4,3—b]pyridazinyl-6)-hydrazine derivatives (4, 5, 7) in polyphosphoric acid or of a hydrazine15 derived from pyridazino-1,2,4-triazine under the action of triethyl orthoformate. Compound8 showed a positive inotropic effect.

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Über Pyridazinring enthaltende Verbindungen, 20. 6H-1,2,4-Triazino[4,3—b]1,2,4-triazolo[3,4—f]pyridazin, ein neues angulares Ringsystem

Zusammenfassung Das neue Ringsystem 6H-1,2,4-Triazino[4,3—b]1,2,4-triazolo[3,4—f]-pyridazin wurde entweder durch Ringschluß der1-(1-Ethoxycarbonylethylen)-2-(1,2,4-triazolo[4,3—b]pyridazinyl-6)-hydrazin-Derivate(4, 5, 7) 4, 5, 7 in Polyphosphorsäure, oder aus einem von Pyridazino-1,2,4-triazin abgeleiteten Hydrazin15 durch Ringschluß mit Orthoameisensäuretriethylester hergestellt. Verbindung8 zeigte einen positiven inotropen Effekt.

     

New approaches to synthesis of tris[1,2,4]triazolo[1,3,5]triazines

Thermal cyclization of 3-R-5-chloro-1,2,4-triazoles (R = Cl, Ph) afforded 2,6,10-tri-R- tris[1,2,4]triazolo[1,5-a:1′,5′c:1″,5″-e][1,3,5]triazines 5 (R = Ph) and 7 (R = Cl). These compounds are first representatives of this class of heterocycles, whose structures were unambiguously established. Treatment of these compounds with nucleophiles (H₂O/NaOH, NH₃) results in the triazine ring opening to give compounds consisting of three 1,2,4-triazole rings linked in a chain. For example, treatment of cyclic compound 5 with aqueous alkali affords 3-phenyl-1-3-phenyl-1-(3-phenyl-1H-1,2,4-triazol-5-yl)-1,2,4-triazol-5-yl-1H-1,2,4-triazol-5-one. Treatment of 3,7,11-triphenyltris[1,2,4]triazolo[4,3-a:4′,3′c:4″,3″-e][1,3,5]triazine (2) with HCl/SbCl₅ leads to the triazine ring opening giving rise to 5-(3-chloro-5-phenyl-1,2,4-triazol-4-yl)-3-phenyl-4-(5-phenyl-1H-1,2,4-triazol-3-yl)-1,2,4-triazole. Thermal cyclization of the latter produces 3,7,10-triphenyltris[1,2,4]triazolo[1,5-a:4′,3′c:4″,3″-e][1,3,5]triazine (13). Thermolysis of both cyclic compound 2 and cyclic compound 13 is accompanied by the Dimroth rearrangement to yield 3,6,10-triphenyl-tris[1,2,4]triazolo[1,5-a:1′, 5′-c:4″,3″-e][1,3,5]triazine (14). Compounds 13 and 14 are the first representatives of cyclic compounds with this skeleton. ¹³C NMR spectroscopy allows the determination of the isomer type in a series of tris[1,2,4]triazolo[1,3,5]triazines.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 706–712, March, 2005.     

SYNTHESES AND REACTIVITY OF SOME 1,2,4-THIADIAZOLOAZINES AND 1,2,4-THIADIAZOLOAZOLES

Abstract

Recently, we have prepared a number of N-ethoxycarbonyl-N′-(2-azinyl)thioureas, which could be cyclized by oxidation into derivatives of 1,2,4-thiadiazolo/2,3-a/azines.     

Synthesis of 5-Mercaptoalkylthiopyrazolyl-and 3-Mercaptoalkylthioisoxazolyl)-1,2,4-triazoles by Ring Chain Transformation

Cyclic α-oxo-α-(1,2,4-triazolyl)ketene S,S-acetals 1a-e react with hydrazine affording the substituted pyrazolyl-1,2,4-triazoles 3a-e. With hydroxylamine hydrochloride under basic conditions the substituted isoxazolyl-1,2,4-triazoles 5a-c are obtained.     

An unequivocal synthesis of some substituted 1,2,4-triazolo[1,5-a]pyrimidines

An unequivocal synthesis of 5-chloro-7-methyl- (8) and 7-methyl-1,2,4-triazolo[1,5-a]pyrimidine (10) from 2-amino-4-chloro-6-methylpyrimidine (5) through the corresponding amidine6 and formamide oxime7 was developed. It was unambigously shown by comparison of the chemical shifts and the magnitude of coupling constants that the compounds obtained by condensation of 3-amino-1,2,4-triazole (12) and ethyl acetoacetate (13) and some further transformations are isomeric 5-methyl substituted 1,2,4-triazolo[1,5-a]pyrimidines1,9, and11.

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Eine eindeutige Synthese einiger substituierter 1,2,4-Triazolo[1,5-a]pyrimidine

Zusammenfassung Es wurde ein eindeutiger Syntheseweg für 5-Chlor-7-methyl- (8) und 7-Methyl-1,2,4-triazolo[1,5-a]pyrimidin (10) ausgehend von 2-Amino-4-chlor-6-methylpyrimidin (5) über das entsprechende Amidin6 und das Formamidoxim7 entwickelt. Durch Vergleich von chemischen Verschiebungen und Kopplungskonstanten konnte eindeutig gezeigt werden, daß die Verbindungen, die bei der Kondensation von 3-Amino-1,2,4-triazol (12) and Ethylacetoacetat (13), sowie einige weitere Transformationsprodukte, isomere 5-Methylsubstituierte 1,2,4-Triazolo[1,5-a]pyrimidine sind (1,9,11).

     

Synthesis of some substituted triazolo[4,3-b][1,2,4]triazines as potential anticancer agents

The synthesis of some 3-substituted amino-6,7-diphenyl-1,2,4-triazolo[4,3-b][1,2,4]triazines (15) by cyclodesulfurisation of the corresponding N-(5,6-diphenyl-1,2,4-triazin-3-yl)-N-[substituted thio (carbamoyl)]hydrazines (3) using dicyclohexylcarbodiimid (DCC) and mercuric chloride is described. Moreover, trials to prepare 3-substituted amino-7-hydroxy-6-methyl-1,2,4-triazolo[4,3-b][1,2,4]triazines were not successful.

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Synthese einiger substituierter Triazolo[4,3-b][1,2,4]-triazine als potentielle Antikrebswirkstoffe

Zusammenfassung Es wird die Synthese einiger 3-substituierter Amino-6,7-diphenyl-1,2,4-triazolo[4,3-b][1,2,4]-triazine (15) mittels Cyclodesulfurisierung der entsprechenden N-(5,6-Diphenyl-1,2,4-triazin-3-yl)-N-[subst.thio(carbamoyl)]-hydrazine (3) unter Verwendung von Dicyclohexylcarbodiimid (DDQ) beschrieben. Versuche zur Herstellung von 3-substituierten Amino-7-hydroxy-6-methyl-triazolo[4,3-b][1,2,4]-triazinen schlugen fehl.

     

Synthesis,Antibacterial, and Antifungal Activities of Imidazo[2,1-c][1,2,4]triazoles and 1,2,4-Triazolo[4,3-a]pyrimidinones

A straightforward method has been developed for the synthesis of 1-phenyl-imidazo [2,1-c][1,2,4]triazole derivatives 5a–j and 1-phenyl-[1,2,4]triazolo[4,3-a]pyrimidinones derivatives 6a–g starting from 5-amino-1-phenyl[1,2,4]triazole and p-toluenesulfonic acid (PTSA). This methodology affords a number of 1-phenyl-imidazo [2,1-c][1,2,4]triazoles 5a–j and 1-phenyl-[1,2,4]triazolo[4,3-a]pyrimidinones 6a–g in reasonable yields and short reaction times. The structures of all new compounds were elucidated using infrared, ¹H and ¹³C NMR, and high-resolution mass spectrometry. Some of the newly synthesized compounds were screened for their antimicrobial activity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications ^® for the following free supplemental resource(s): Full experimental and spectral details.]     

Reaktionen vonN-Sulfinylverbindungen mit dem 1,2,4-Trithia-3,5-diborolan-Ringsystem und Substitutionsreaktionen am 1,2,4-Trithia-3,5-diborolan und 1,2-Dithia-4-aza-3,5-diborolidin

The reaction of trimethylsilyl- and pentafluorophenyl-N-sulfinylamine respectively with 3,5-dihalogeno-1,2,4-trithia-3,5-diborolanes yields the 1,2-dithia-4-aza-3,5-diborolidines1-3.Tert-butyl-N-sulfinylamine and 3,5-dimethyl-1,2,4-trithia-3,5-diborolane react analogous. OtherN-sulfinylamines however split the disulfane bridge in 3,5-dimethyl-1,2,4-trithia-3,5-diborolane and the 1,4-dithia-2-aza-3,5-diborolidines5A-7(A) are formed. Besides of boroxines, cyclo-2,4,6-trimethyl-1,3-dioxa-5-aza-2,4,6-triboranes and cyclo-2,4,6-trimethyl-1-oxa-3,5-diaza-2,4,6-triboranes are formed as byproducts,8–10 have been isolated. In 1,2,4-trithia-3,5-diborolanes and 1,2-dithia-4-aza-3,5-diborolidines the bromo-atoms can be substituted by alkyl (13, 14), by amino (15–20) and by isothiocyanato groups. The compounds were characterised analytically and spectroscopically (MS; NMR:¹H,¹¹B,¹⁹F,²⁹Si; IR).

     

New 1,2,4-triazine-containing podands: synthesis and properties

A method of one-step C-C coupling of 1,5-bis(2,6-dimethylphenoxy)-3-oxapentane (1a) and 1,8-bis(2,6-dimethylphenoxy)-3,6-dioxaoctane (1b) with 3-methylthio- (2) and 3-amino-1,2,4-triazine (3) and 3-aryl-1,2,4-triazin-5-one (6-8) has been described. The reaction of compounds 1a,b with compounds 2 and 3 in the presence of trifluoroacetic acid results in the addition of the dimethylphenoxy group to the unsubstituted C(5) carbon atom of the triazine ring. The reactions of triazinones 6-8 with compounds 1a,b in a mixture of trifluoroacetic acid and organic anhydrides are accompanied by the acylation of the nitrogen atom adjacent to the reaction center and affords bis[(3-R-1-acyl-5-oxo-1,4,5,6-tetrahydro-1,2,4-triazin-6-yl)-2,6-dimethylphenoxy]-3-oxapentane or -3,6-dioxaoctane. The obtained adducts can smoothly be oxidized under mild conditions to form more stable products of nucleophilic hydrogen substitution in the triazine ring. The extraction and transport of Ca²⁺ and Mg²⁺ cations through an organic membrane by the compounds synthesized are discussed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2210–2215, October, 2004.     

Cascade cyclization reactions of 3,4,5-triamino-1,2,4-triazole with aromatic aldehydes and cycloalkanones

A three-component condensation of 3,4,5-triamino-1,2,4-triazole (1) with aromatic aldehydes 2a–f and dimedone (3) or cyclohexanone (8) afforded partially hydrogenated 9-aryl-[1,2,4]triazolo[5,1-b]quinazolin-8-ones. The structure of 2-amino-6,6-dimethyl-3-(4-nitrobenzylidene)amino-9-(4-nitrophenyl)-5,6,7,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazolin-8-one (4e) was confirmed by X-ray diffraction data. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1178–1182, July, 2006.     

Synthesis and Antimicrobial Properties of New Thiosemicarbazide, 1,2,4-Triazole,and 1,3,4-Thiadiazole Derivatives of Sulfanylacetic Acid

Abstract

1,2,4-triazole and 1,3,4-thiadiazole derivatives are still considered a viable lead structure for the synthesis of more efficient antimicrobial agents having a broad spectrum of activity. This study presents the synthesis and antimicrobial evaluation of a new series of substituted 1,2,4-triazole and 1,3,4-thiadiazole derivatives. Reaction of 4-phenyl-5-(pyridin-3-yl)-4H-1,2,4-triazole-3-thione with ethyl bromoacetate yields the corresponding ethyl acetate (1). In the subsequent reaction with 100% hydrazine hydrate, the hydrazide (2) was obtained, which was converted with isothiocyanates to new acyl derivatives of thiosemicarbazide (3a–l). The cyclization of these compounds in alkaline media resulted in the formation of new derivatives of 1,2,4-triazole (4a–i), whereas in acidic media new derivatives of 1,3,4-thiadiazole (5a,b,g) were obtained. All synthesized compounds were screened for their in vitro antimicrobial activities.     

Focused microwave irradiation-assisted synthesis of N-cyclohexyl-1,2,4-oxadiazole derivatives with antitumor activity

A facile synthesis of 3,5-disubstituted 1,2,4-oxadiazole derivatives under focused microwave irradiation (FMWI) is reported. Arylamidoximes 1a–i and dicyclohexylcarbodiimide (DCC) were carried out in DMF under FMWI to obtain 1,2,4-oxadiazoles 2a–i in 61–81% yields. All compounds exhibited antiproliferative activities in vitro against three human cancer cell lines HCT-116, PC-3, and SNB-19.     

RING-TRANSFORMATION FROM ISOTHIAZOLE TO 1,2,4-THIADIAZOLE - POSSIBLE INTERMEDIACY OF π-SULFURANE

Abstract

5-Amino-3-methyl- and 5-amino-3-phenylisothiazoles (3a and 3b) afforded 1 : 1 adducts with aromatic nitriles and imidates. On the basis of their spectral data and the structure of hydrolysis products, the adducts were identified as 3-substituted 5-(2-aminovinyl)-1,2,4-thiadiazole derivatives (2a-g), where ring transformation took place from isothiazole to 1,2,4-thiadiazole.     

Synthesis of 2-alkyl-1,2,4-benzotriazin-3(2h)-ones and 2-alkyl-1,4-dihydro-1,2,4-benzotriazin-3(2h)-ones

A preparative method for the synthesis of 2-alkyl-1,2,4-benzotriazin-3(2H)-ones 3 was developed. The method involves treatment with sodium cyanate of 2-alkylbenzotetrazinium tetrafluoroborates, which exist in solutions in equilibrium with o-(alkylazo)aryldiazonium tetrafluoroborates. Reduction of compounds 3 with zinc in acetic acid afforded 2-alkyl-1,4-dihydro-1,2,4-benzotriazin-3(2H)-ones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 346–349, February, 2006.     

THE SYNTHESIS OF 15N LABELED 6-NITRO-1,2,4-TRIAZOLO- [5,1-c][1,2,4]TRIAZIN-7-ONE

A general method for inclusion of the ¹⁵N label into the position 1 of 6-nitro-1,2,4-triazolo[5,1-c][1,2,4]triazin-7-one by using K¹⁵NO₃ has been developed.