Some 1-aroyl-4,4-dialkylsemicarbazides and their cyclization to afford 5-aryl-1,3,4-oxadiazol-2(3H)-ones

Some 1-aroyl-4,4-dialkylsemicarbazides have been prepared by reacting aroylhydrazides with dimethyl- or diethyl-carbamoyl chloride. In boilingDMF they lose dimethylamine or diethylamine to give 5-aryl-1,3,4-oxadiazol-2(3H)-ones.

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Einige 1-Aroyl-4,4-dialkylsemicarbazide und ihre Cyclisierung zu 5-Aryl-1,3,4-oxadiazol-2(3H)-onen (Kurze Mitteilung)

Zusammenfassung Es wurden mittels Reaktion von Aroyl-hydraziden mit Dimethyl- oder Diethyl-carbamidsäure-chlorid einige 1-Aroyl-4,4-dialkylsemicarbazide dargestellt. Diese verlieren in kochendemDMF Dimethylamin bzw. Diethylamin und geben 5-Aryl-1,3,4-oxadiazol-2(3H)-one.

     

A facile retro-ene reaction of 5-(methoxyamino)-3-aryl-1,3,4-oxadiazol-2(3H)-ones

5-(N-Methoxy-N-methyl)amino-3-aryl-1,3,4-oxadiazol-2(3H)-ones 3 undergo a heteroretro-ene reaction in refluxing methanol in which the leaving enophile is formaldehyde. The resulting 5-(methylimino)-3-aryl-1,3,4-oxadiazolidin-2-one 4 may be viewed as a kinetic product which tautomerizes to the more stable 5-(methylamino)-3-aryl-1,3,4-oxadiazol-2(3H)-one 5 as the thermodynamic product. Comparison of calculated reaction energies reveals that the presence of the heterocyclic ring facilitates the retro-ene reaction, but the expulsion of formaldehyde is predicted to be highly exothermic even in its absence.     

Synthesis of 3-acylamino-2-oxazolidinone derivatives through cyclic transformations of 5-aryl (or benzyl)-1,3,4-oxadiazol-2(3H)-one derivatives

New 3-acylamino-2-oxazolidinone derivatives 3 were obtained in good yields by reaction of 5-aryl (or benzyl)3-(2-hydroxyethyl)1,3,4-oxadiazol-2(3H)ones 1 with sodium ethylate. Treatment of ethyl 5-aryl-2-oxo-1,3,4-oxadiazole-3(2H)-acetates 7 with aromatic aldehydes in the presence of sodium ethylate or sodium hydride afforded 3-acylamino-5-aryl-4-ethoxycarbonyl-2-oxazolidinone derivatives as two trans- 5 and cis- 6 racemics. Only RS,SR-racemates were obtained with acetophenone under the same conditions.     

Synthesis of obtusinin and 7-(3′-hydroxymethylbut-2′-enyloxy)-6-methoxy-2H-1-benzopyran-2-one

Obtusinin (1) has been synthesised by the reaction of 6-methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-one (3) with OsO₄. Synthesis of 7-(3-hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-one (2) has been achieved by the regiospecific oxidation of3 with SeO₂ followed by reduction of the formed aldehyde with KBH₄.

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Synthese von Obtusinin und 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on

Zusammenfassung Obtusinin (1) wurde über 6-Methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-on (3) mit OsO₄ synthetisiert. Die Darstellung von 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on (2) wurde mittels regioselektiver Oxidation von3 mit SeO₂, gefolgt von Reduktion des gebildeten Aldehyds mit KBH₄, bewerkstelligt.

     

Cyclic transformations of 5-aryl(or benzyl)-3-(2-bromoethyl- 1,3,4-oxadiazol-2(3H)-ones into 1-aminoimidazolidin-2-one and 5,6-dihydro-4H-1,3,4-oxadiazine derivatives

5-Aryl(or benzyl)-3-(2-bromoethyl)-1,3,4-oxadiazol-2(3H)-ones 3 have been prepared. They were reacted with secondary alkylamines without any change of the heterocycle to give amino derivatives 6 , but with primary alkylamines, cyclic transformation occurred to give 1-acylamino-3-alkylimidazolidin-2-ones 7 . In the presence of sodium alcoholate, bromo compounds 3 were transformed into 2-aryl(or benzyl)-4-alkoxycarbonyl-5,6-dihydro-4H-1,3,4-oxadiazines 9 .     

Über Dihydro-bzw. Tetrahydrospiro([1]benzopyran-2,4′(1′H)-pyrimidin)-2′(3′H)-one

On reaction of dihydro-4,4,6-trimethyl-2(1H)-pyrimidinone1 with o-hydroxybenzaldehydes, dihydro- and tetrahydrospiro([1]-benzopyran-2,4(1H)-pyrimidin)-2(3H)-ones resp.5, 6, 7 are formed.     

Synthesis of 5-aryl-3-carbazoyl-1,3,4-oxadiazol-2(3H)-one. Derivatives and their ring transformation into 5-benzamido-1,2,4-triazolidine-3,5-dione derivatives

Some 5-aryl-3-carbazoyl-1,3,4-oxadiazol-2(3H)-one derivatives 6 and 9 have been synthesized in two ways. The expected thermal ring transformation into 2,5-disubstituted 1,3,4-oxadiazoles did not occur but, by acid hydrolysis of 5-aryl-3-[3-benzylidene-2-methyl(or phenyl)carbazoyl]-1,3,4-oxadiazol-2(3H)-ones 6 , a new ring transformation took place and the corresponding 4-benzamido-1-methyl(or phenyl)-1,2,4-triazolidine-3,5-dione derivatives 11 were formed. The 4-amino-1-phenyl-1,2,4-triazolidine-3,5-dione ( 19 ) has been prepared and its structure was confirmed by some reactions.     

Über Dihydro-6-methyl- bzw.-6-styryl-4-phenyl-2(1H)-pyrimidinone (-thione) sowie Hexahydro-5-benzoyl- bzw.-cinnamoyl-4,7-diphenyl-2(1H)-chinazolinone (-thione)

Zusammenfassung Dihydro-6-methyl-4-phenyl-2 (1H)-pyrimidinone (-thione) (1) reagieren als -Methylalkenylharnstoffe bzw.-thioharnstoffe mit Säuren zu Hexahydro-4,4-methylendi-2(1H)-pyrimidinonen (-thionen) (3), mit Phenolen zu Tetrahydro-6-hydroxyphenyl-2(1H)-pyrimidinonen (-thionen) (2), mit Benzaldehyd zu 6-Styrylverbindungen (1 d, e, g) und mit ,-ungesättigten Ketonen zu Tetrahydro-2(1H)-chinazolinonen (7). Aus 1,5-Diphenyl-1,4-pentadien-3-on und Harnstoffen, Thioharnstoffen bzw. Ammonrhodanid entstehen Diphenyl-1,3,7,9-tetraazaspiro-5,5-undecan-2,8-dione (9) bzw. Hexahydrotriphenyl-6-cinnamoyl-2(1H)-chinazolinthione (10). Hexahydro-6-benzoyl-bzw.-6-cinnamoyl-2(1H)-chinazolinone (-thione) (10) bilden sich allgemein bei Einwirkung von ,-ungesättigten Ketonen auf Dihydro-4-phenyl-6-styryl-2(1H)-pyrimidinone (-thione) (1 d, e, g).

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Heterocycles, XXVII: Dihydro-6-methyl-(or-6-styryl-)-4-phenyl-2(1H)-pyrimidinones (-thiones); Hexahydro-5-benzoyl-(or-cinnamoyl-)-4,7-diphenyl-2(1H)-quinazolinones (-thiones)

Dihydro-6-methyl-4-phenyl-2(1H)-pyrimidinones (-thiones) (1) react as -methylalkenylureas (-thioureas) with acids to hexahydro-4.4-methylenedi-2(1H)-pyrimidinones (-thiones) (3), with phenols to tetrahydro-6-hydroxyphenyl-2(1H)-pyrimidinones (-thiones) (2), with benzaldehyde to 6-styryl compounds (1 d, e, g) and with ,-unsaturated ketones to tetrahydro-2(1H)-quinazolinones (7).On reacting 1.5-diphenyl-1.4-pentadien-3-one with ureas, thioureas or ammonium thiocyanate, the products formed are diphenyl-1.3.7.9-tetraazaspiro-5.5-undecane-2.8-diones (9) and hexahydrotriphenyl-6-cinnamoyl-2(1H)-quinazolinethiones (10), resp. Hexahydro-6-benzoyl- (or-6-cinnamoyl-)-2(1H)-quinazolinones (-thiones) (10) are formed generally by the action of ,-unsaturated ketones on dihydro-4-phenyl-6-styryl-2(1H)-pyrimidinones (-thiones) (1 d, e, g).

     

Thioureas from 3-aminoquinazolin-4(3H)-one. 2. Unusual alkaline recyclization of 3-(N",N",S-trialkylisothioureido)quinazolin-4(3H)-ones into new 1,3,4-oxadiazoles

3-(N",N",S-trialkylisothioureido)quinazolin-4(3H)-ones obtained by the reactions of 3-(N",N"-dialkylthioureido)quinazolin-4(3H)-ones with alkyl halides undergo unusual recyclization into 5-(2-aminophenyl)-2-dialkylamino-1,3,4-oxadiazoles under the action of aqueous solutions of alkali, hydrazine, and primary aliphatic amines. A plausible mechanism of the recyclization was proposed.     

Arbeiten über Phosphorsäure- und Thiophosphorsäure ester mit einem heterocyclischen Substituenten. 2. Mitteilung. Eine verbesserte Methode zur Herstellung von 1, 3, 4-Oxadiazol-2(3H) onen und von Thio- und Dithiophosphorsäure-O,O-dialkyl-S-[(1, 3, 4-oxadiazol-2(3H)-on-3-yl)-methyl]-estern

Some 1,3,4-oxadiazol-2(2H)-ones with aliphatic substituents in 5-position are prepared in good yields and converted via the 3-hydroxymethyl derivatives to the corresponding 3-chloromethyl derivatives which are suitable starting materials for the preparation of insecticidal O,O-dialkyl-S-[(5-subst.-1,3,4-oxidiazol-2(3H)-one-3-yl)-methyl]-thiophosphates and dithiophosphates.     

Synthesis and Antimicrobial Activity of Some New 5-(3-Chloro-1-Benzothiophen-2-YL)-1,3,4-Oxadiazole-2-Thiol and Their Derivatives

Abstract

3-Chloro-1-benzothiophene-2-carbonylchloride 1 was made to reacts with hydrazine hydrate afforded 3-chloro-1-benothiophene-2-carbohydrazide 2 in good yield. 5-(3-chloro-1-benzothiophen-2-yl)-1,3,4-oxadiazole-2-thiol 4 was synthesized from 3-chloro-1-benzothiophene-2-carbohydrazide 2. Mannich bases, alkyl halide, and acid chlorides derivatives were then prepared. Compound 4 on condensation with chloroacetone in the presence of NaOH as base and ethanol as solvent gave 1-{[5-(3-chloro-1-benzo[b]thiophen-2-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}propan-2-on 6. Condensation of compound 6 with various aromatic aldehydes afforded a series of chalcones 7a–h. The structures of all the synthesized compounds were confirmed by spectral data and have been screened for antibacterial 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.

GRAPHICAL ABSTRACT      

Heterobimetallische Vanadium- und Thallium-2-(dimethylaminomethyl)ferrocenyl-Verbindungen

Zusammenfassung Synthesen und Eigenschaften von 2-(Dimethylaminomethyl)ferrocenyl-Derivaten der Formel (FcN) _n VCl_3–n (FcN=2-(Dimethylaminomethyl)ferrocenyl;n=1 (1), 2 (2), 3 (3)), die aus VCl₃·3THF und (FcN) Li (I) entstehen, werden mitgeteilt. WährendCp ₂VCl₂ (Cp=C₅H₅) mitI unter Bildung vonCp ₂ V(FcN) (4) reagiert, läßt sich VO (acac)₂ (acac=Anion des Acetylacetonates, C₅H₇O₂) in die 2-(Dimethylaminomethyl)ferrocenyl-Verbindung des vierwertigen Vanadiums (FcN)VO(acac),5) überführen. Dagegen entsteht bei Umsetzungen von VOCl₂·2THF mitI das Organovanadium (III)-Derivat Li [(FcN)₂V(O)Cl] (6).Reaktionen von VCl₄·2THF,Cp ₂VCl₂, VOCl₃ undCpVOCl₂ mit (FcN)₃Tl (II) führen unter Bildung von (FcN)₂TlCl (7) zu thermisch instabilen vanadiumorganischen Verbindungen. Eine eingehende Charakterisierung von1–7 erfolgte durch Elementaranalysen, Ermittlung der effektiven magnetischen Momente, IR-, Massen- und NMR-Spektroskopie sowie, insbesondere hinsichtlich der Ausbildung möglicher Chelatstrukturen, durch UV/Vis und Mößbauer-Spektroskopie.

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Heterobimetallic 2-(dimethylaminomethyl)ferrocenyl compounds of vanadium and thallium

Summary Syntheses and properties of 2-(dimethylaminomethyl)ferrocenylderivatives of the composition (FcN) _n VCl_3–n (FcN=2-(dimethylaminomethyl)ferrocenyl;n=1 (1), 2 (2), 3 (3)), which are formed from VCl₃·3THF and (FcN) Li (I), are reported. WhereasCp ₂VCl₂ (Cp=C₅H₅) reacts withI under formation ofCp ₂V(FcN) (4), VO(acac)₂ (acac=anion of acetylacetonate, C₅H₇O₂) can be transformed into the 2-(dimethylaminomethyl)-ferrocenyl compound of tetravalent vanadium (FcN)VO(acac),5). However, when VOCl₂·2THF reacts withI, the organovanadium(III)-derivative Li[(FcN)₂V(O)Cl] (6) is formed.Reactions of VCl₄·2THF,Cp ₂VCl₂, VOCl₃, andCpVOCl₂ with (FcN)₃Tl (II) lead to thermally instable vanadiumorganic compounds under formation of (FcN)₂TlCl (7). A detailed characterization of1–7 was carried out by elementary analysis, determination of effective magnetic moments, IR, mass and¹H NMR spectroscopy as well as — especially referring to the formation of possible chelate structures — by UV/Vis andMöbauer spectroscopy.

     

Photochemical versus aluminium chloride-catalyzed fries rearrangement of aryl hydrogen succinates. synthesis of 2(3H)-furanones

Summary The photochemical and aluminium chloride-catalyzed Fries rearrangement of a series of aryl hydrogen succinates3 a–f to the corresponding 4-oxoacids1 a–f are compared. Both approaches are complementary: the photochemical process is more general and becomes the method of choice for the succinoylation of phenols supporting alkoxy or hydroxy substituents, while the classical rearrangement is superior in the presence of alkyl or halogen substituents. These results are applied to the preparation of the 2(3H)-furanones2 a–f.

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Photochemische und Aluminiumchlorid-katalysierte Friessche Umlagerung von Bernsteinsäuremonoarylestern. Synthese von 2(3H)-Furanonen

Zusammenfassung Die photochemische und AlCl₃-katalysierte Friessche Umlagerung einer Reihe von Bernsteinsäuremonoarylestern3 a–f zu den entsprechenden 4-Oxosäuren1 a–f werden verglichen. Beide Methoden ergänzen einander: Der photochemische Prozeß ist breiter anwendbar und wird bei Phenolen mit Alkoxy- oder Hydroxy-Substituenten bevorzugt, während die klassische Umlagerung in Gegenwart von Alkyl- oder Halogen-Substituenten vorteilhafter ist. Diese Ergebnisse werden für die Synthese der 2(3H)-Furanone2 a–f angewendet.

     

3-Methyl[1,3,4]thiadiazino[2,3-b]quinazolin-6-ones

4H,6H-[1,3,4]Thiadiazino[2,3-b]quinazolin-6-one with a methyl group in position 3 (6a) has been synthesised by the condensation of 3-amino-2-mercapto-3H-quinazolin-4-one (1) with allyl bromide (2) followed by treatment with bromine and subsequent dehydrohalogenation of the brominated product (4) with ethanolic sodium hydroxide. Its isomeric 3-methyl-2H,6H-[1,3,4]thiadiazino[2,3-b]quinazolin-6-one (6b) has also been obtained by condensation of1 and bromoacetone (7) followed by cyclisation of the intermediates (8 or9) with hydrobromic acid or with concentrated sulphuric acid. The structures have been established on the basis of IR and PMR data.

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3-Methyl[1,3,4]thiadiazino[2,3-b]chinazolin-6-one

Zusammenfassung Zur Synthese von 4H,6H-[1,3,4]thiadiazino[2,3-b]chinazolin-6-on (6a) wurde die Kondensation von 3-Amino-2-mercapto-3H-chinazolin-4-on (1) mit Allylbromid mit nachfolgender Behandlung mit Brom und Dehydrohalogenierung des bromierten Produktes4 mit ethanolischer Natronlauge herangezogen. Das zu6a isomere 2H,6H-Produkt6b wurde ebenfalls durch Kondensation von1 mit Bromaceton und nachfolgender Cyclisierung der Zwischenprodukte8 bzw.9 mit HBr oder H₂SO₄ erhalten. Die Strukturen wurden mittels IR und NMR abgesichert.

     

Synthesis and anticancer activity evaluation of (<Emphasis Type="Italic">E</Emphasis>)-3-{[5-(aryl)-1,3,4-oxadiazol-2-yl]methyl}-5-(3,4,5-trimethoxybenzylidene)thiazolidine-2,4-diones

A series of new substituted (E)-3-{[5-(aryl)-1,3,4-oxadiazol-2-yl]methyl}-5-(3,4,5-trimethoxy-benzylidene) thiazolidine-2,4-diones have been synthesized. The products have been characterized by their IR, ¹H NMR, ¹³C NMR, and mass spectral properties and evaluated for anticancer activity against four human cancer cell lines: A549, A375, MCF-7, and HT-29.     

Zur Struktur der Tetrahydro-4-phenylspiro([1]benzopyran-2,4′(1′H)-pyrimidin)-2′(3′H)-one bzw.-thione Über Heterocyclen, 49. Mitt

The structures of tetrahydro-4-phenylspiro([1]benzopyran-2,4(1H)-pyrimidin)-2(3H)-ones and-thiones4 a, b resp., are proved by synthesis. 3-(2-methoxy-3,5-dimethylphenyl)-3-phenylpropionic acid11 b is prepared from 3,4-dihydro-6,8-dimethyl-4-phenylcoumarin10. The lithium salt of11 b reacts with isobutenyl-lithium to 1-(2-methoxy-3,5-dimethylphenyl)-5-methyl-1-phenyl-4-hexen-3-on12 a. 12 a is transferred with urea in acid medium and NH₄CNS resp. in a mixture of dihydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyl]-4,4-dimethyl-2(1H)-pyrimidinone and-thione13 a, b and tetrahydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyliden]-4,4-dimethyl-2(1H)-pyrimidinone and-thione14 a, b resp.14 b leads to13 a, b with H₂O₂. Heating of13 a, 14 a and14 b resp. with pyridin-HCl leads to the spiro compounds4 a, b.     

DMF acetals as alkylating and cyclizing agents: A facile route to substituted pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-diones

Summary Several 7-methyl-5-alkyl-2-vinylpyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-diones were prepared. The successful cyclization and alkylation of 6-(-methylbenzylidenehydrazino)-1-methyluracils2a–d using dimethylformamide acetals at high temperature provided6a–d,7a–d, and8a–d. Treatment of6a–d and7a–d with acid afforded 7-methyl-5-alkylpyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-diones9a,b; under the same conditions,3a–d reacted to 7-methylpyrazolo[3,4-d]-pyrimidine-4,6(5H)-dione (4) in good yield.

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DMF-Acetale als Alkylierungs- und Ringschlußreagentien: ein einfacher Weg zu substituierten Pyrazolo[3,4-d]pyrimidin-4,6(5H,7H)-dionen

Zusammenfassung Es wurden verschiedene 7-Methyl-5-alkyl-2-vinylpyrazolo[3,4-d]pyrimidin-4,6(5H,7H)-dione hergestellt. Cyclisierung und Alkylierung der 6-(-Methylbenzylidenhydrazino)-1-methyl-uracile2a–d mit Hilfe von Dimethylformamidacetalen bei hohen Temperaturen ergab6a–d,7a–d und8a–d. Behandlung von6a–d und7a–d mit Säure lieferte die 7-Methyl-5-alkylpyrazolo[3,4-d]pyrimidin-4,6(5H,7H)-dione9a,b; unter den gleichen Bedingungen reagierten3a–d in guter Ausbeute zu 7-Methylpyrazolo[3,4-d]pyrimidin-4,6(5H)-dion (4).

     

Über die Nitrierung von 7-Chlor-5-phenyl-1H-thieno[2,3-e]1,4-diazepin-2(3H)-on

Zusammenfassung Bei der Nitrierung von 7-Chlor-5-phenyl-1H-thieno[2,3-e]1,4-diazepin-2(3H)-on (1) wurde ein Produkt erhalten, dessen Struktur durch chemische Beweisführung bestimmt wurde.

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The nitration of 7-chlor-5-phenyl-1H-thieno[2,3-e]1,4-diazepin-2(3H)-one

The said compound (1) yielded a product whose structure was determined by chemical methods.

     

Pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9(6H8H)-diones

Some 5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9-(6H,8H)-diones (4 a–d) have been synthesised by the condensation of 3-alkyl-4-amino-5-mercapto-(1,2,4)-triazoles (1 a–d) with 5-bromobarbituric acid (2a). Similarly some 9a-nitro-5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9(8H,9aH)-diones (5 a–d) have been obtained by the condensation of1 a–d with 5-bromo-5-nitrobarbituric acid (2b) and final cyclisation withPPA. The structures have been confirmed by PMR spectra and analytical results.

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Pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(6H,8H)-dione

Zusammenfassung Es wurden einige 5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(6H,8H)-dione (4 a–d) mittels Kondensation von 3-Alkyl-4-amino-5-mercapto-(1,2,4)-triazolen (1 a–d) mit 5-Brombarbitursäure (2 a) dargestellt. Des weiteren wurden einige 9a-Nitro-5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(8H,9aH)-dione (5 a–d) über die Kondensation von1 a–d mit 5-Brom-5-nitrobarbitursäure (2 b) und anschließender Cyclisierung mitPPA synthetisiert. Die angeführten Strukturen wurden mittels PMR-Spektren und analytischen Daten abgesichert.

     

Synthesis of 2-acetyl-3-methyl-4H-1,4-benzothiazine and its derivatives

Summary 2-Aminothiophenol (1) reacts with 3-chloro-2,4-pentanedione (2) in the presence of pyridine to form 2-acetyl-3-methyl-4H-1,4-benzothiazine (3) in high yields. Reaction of3 with hydrazine gives 4-(2-aminophenylthio)-3,5-dimethylpyrazole (5). Condensation of3 with 4-nitrobenzaldehyde yields the corresponding Schiff base7. Hydroxylamine with benzothiazine3 affords 3,9a-dimethyl-3a, 9a-dihydro-9H-isoxazolo[4,5-b][1,4]benzothiazine (8).

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Synthese von 2-Acetyl-3-methyl-4H-1, 4-benzothiazin und seinen Derivaten

Zusammenfassung 2-Aminothiophenol (1) reagiert mit 3-Chlor-2,4-pentandion (2) in Anwesenheit von Pyridin unter Bildung von 2-Acetyl-3-methyl-4H-1,4-benzothiazin (3) in sehr hoher Ausbeute. Benzothiazin3 kondensiert mit Hydrazin zu 4-(2-Aminophenylthio)-3,5-dimethylpyrazol (5), dessen Aminogruppe reagiert mit 4-Nitrobenzaldehyd zu einer Schiffschen Base (7), die spektroskopisch charakterisiert wurde. Benzothiazin3 mit Hydroxylamin ergibt 3,9a-Dimethyl-3a,9a-dihydro-9H-isoxazolo[4,5-b][1,4]benzothiazin (8). Die Stereochemie der letztgenannten Verbindung wurde ermittelt.