4-Phosphoranylidene-5(4H)-oxazolones — A novel synthesis and properties

Summary 4-Phosphoranylidene-5(4H)-oxazolones (2), a hardly known class of phosphorus ylides, were readily prepared from 4-unsubstituted-5-(4H)-oxazolones (1) by treatment with Ph₃P-Br₂, Bu₃P-Br₂, Ph₃P-CCl₄, or Ph₃P-CBr₄ adducts in the presence of triethylamine in CH₂Cl₂ at room temperature in a novel, efficient one-pot procedure. The spectroscopic properties of the ylides are reported and discussed.

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4-Phosphoranyliden-5(4H)-oxazolone — Eine neue Synthese und Eigenschaften

Zusammenfassung 4-Phosphoranyliden-5(4H)-oxazolone, eine sehr wenig bekannte Gruppe der Phosphor-ylide, wurden auf einfache Weise nach einem neuen Eintopfverfahren mit guten Ausbeuten hergestellt. Als Ausgangsverbindungen wurden 4-unsubtituierte-5-(4H)-Oxazolone (1) eingesetzt, die unter der Einwirkung von Addukten wie Ph₃P-Br₂, Bu₃P-Br₂, Ph₃P-CCl₄ oder Ph₃P-CBr₄ in Anwesenheit von Triethylamin in CH₂Cl₂ bei Zimmertemperatur die Titelverbindungen liefern. Die spektroskopischen Eigenschaften der Ylide werden berichtet und diskutiert.

     

NMR studies of 4(3H)-quinazolinones and 4(3H)-quinazolinethiones

Summary Unambiguous¹H and¹³C NMR assignments for 4(3H)-quinazolinones1–6 and their corresponding 4-thiones7–12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones1,2,4, and5. Thionation of the nucleophilic amides1–6 has been found to cause a distinct change in the¹³C chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.

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Kernresonanzspektroskopie von 4(3H)-Chinazolinonen und 4(3H)-Chinazolinthionen

Zusammenfassung Die¹H- und¹³C-NMR-Spektren der 4(3H)-Chinazolinone1–6 und ihrer entsprechenden 4-Thione7–12 wurden zugeordnet. Dabei zeigte sich, daß eine frühere Zuordnung der beiden benzoiden Kohlenstoffe (C-5 und C-8) der Chinazolinone1,2,4 und5 falsch war. Ersatz des Sauerstoffs durch Schwefel in den nukleophilen Amiden1–6 führt insbesondere für C-4, aber auch für C-4a, C-5 und C-8a zu einer deutlichen Änderung der chemischen Verschiebung. Heteronukleare Kopplungskonstanten über eine und über mehrere Bindungen wurden bestimmt.

     

Simultaneous thermoanalytical investigations of (C6H5)4AsCl and (C6H5)4PCl under air and argon atmospheres

The thermoanalytical curves of (C₆H₅)₄AsCl (I) and (C₆H₅)₄PCl (II) were generated simultaneously by using a Netzsch simultaneous thermal analyser 409 under static air and dynamic argon atmospheres. The ranges of thermal stability of I and II were found to be 145–310°C and 137–365°C, respectively, and their melting points to be 261 and 278°C. The DTA profiles of I and II differ and can be used for their distinction.     

Direct diastereoselective introduction of l-menthol residue into 1,2,4-triazin-5(4H)-one

The reaction of 3-phenyl-1,2,4-triazin-5(4H)-one (1) with l-menthol in the presence of aliphatic acid anhydrides results in (6S)- and (6R)-1-acyl-6-(l-menth-3-yl)-1,6-dyhydro-3-phenyl-1,2,4-triazin-5(4H)-ones. The reaction is diastereoselective with predominant formation of (6S)-isomers. The reaction diastereoselectivity increases with enhancement of the steric hindrance in the vicinity of the reaction center of the azine.     

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).

     

Conversion of 6-phenylimino-2H-thiopyran-4-amines to 1-phenyl-2,3-dihydro-4(1H)-pyridinones

Summary 6-Phenylimino-3,6-dihydro-2H-thiopyran-4-amines (1) were converted to 1-phenyl-5,6-dihydropyridine-2(1H)-thiones (3). Those were akylated and hydrolyzed, thus yielding 6-methylthio-1-phenyl-2,3-dihydro-4(1H)-pyridinones (5). Finally, the methylthio group was removed withRaney nickel giving the title compounds6. The relative configurations of the formed diastereoisomeric dihydropyridinones have been investigated by NOE measurements.

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Umwandlung von 6-Phenylimino-2H-thiopyran-4-aminen zu 1-Phenyl-2,3-dihydro-4(1H)-pyridinonen

Zusammenfassung 6-Phenylimino-3,6-dihydro-2H-thiopyran-4-amine (1) wurden in 1-Phenyl-5,6-dihydropyridin-2(1H)-thione (3) umgewandelt. Diese wurden alkyliert und zu 6-Methylthio-1-phenyl-2,3-dihydro-4(1H)-pyridinonen (5) hydrolysiert. Zuletzt gelangte man durch selektives Entfernen der Methylthiogruppe mitRaney-Nickel zu den Titelverbindungen6. Die relativen Konfigurationen der gebildeten diastereomeren Dihydropyridinone wurden durch NOE-Messungen aufgeklärt.

     

Pyridazines with heteroatom substituents in position 3 and 5, part 1: 5-Hydroxy-3(2H)-pyridazinone and its derivatives

Summary The synthesis of the title compound7 was achieved starting with mucochloric acidvia the pyridazinones1,2 and6. The electrolytic ionisation constants for7 were found to be 4.81 (±0.03) and –0.3 (±0.3). Crystal structure analyses were performed for7 and its fixed derivatives6 and9.Dedicated to Prof. Dr. Hans Junek on the occasion of his 60th birthday     

Practical Synthesis of 4-Benzylidene-2-phenyl-5(4H)-oxazolones

A simple and alternative method has been developed for the synthesis of 4-benzylidene-2-phenyl-5(4H)-oxazolones via reactions of hippuric acid with various aldehydes in the presence of 2-chloro-4,6-dimethoxy-1,3,5-triazine/N-methylmorpholine at 75 °C.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Reactivity of Unsaturated 5(4H)-Oxazolones with Hg(II) Acetate: Synthesis of Methyl N-Benzoylamino-3-arylacrylates

An efficient and high-yield procedure to prepare methyl N-benzoylamino-3-arylacrylates from unsaturated (Z)-2-aryl-4-arylidene-5-(4H)-oxazolones and Hg(OAc)₂ in methanol is described herein. The observed reactivity of mercury(II) acetate here is different than its usual metallating behavior and it cleaves the unsaturated oxazolone ring without change of stereochemistry.     

Study of the inf luence of the alkyl ester group in (S)-valinates on diastereoselectivity of their condensation with N-acetylphenylalanine by the mixed anhydride method

The dynamic kinetic resolution in the synthesis of alkyl N-acetylphenylalanyl (S)-valinates was studied by the mixed anhydride method. The structure of the ester group of the amino component appeared to exert no substantial effect on the diastereoselectivity of the reaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 892–894, May, 2006.     

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.     

Pyridazines with hetero-atom substituents in position 3 and 5, part VII. Halogenation of 2-aryl-5-hydroxy-pyridazin-3(2H)-ones in position 4

Summary The reaction of 2-ary-5-hydroxy-3(2H)-pyridazinones (1a, b) with bromine yields the 4-bromo derivatives2a, b and with sulfuryl chloride the chloro compounds3a, b are obtained. However, with an excess of chlorine or sulfuryl chloride the 4,4-dichloro-pyridazine-dione4 is produced. Hydrolysis of4 leads to5, and in a similar manner the open chain hydrazone8 is obtained from the carboxylic acid6.

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Pyridazine mit Heteroatom-Substituenten in Stellung 3 und 5, 7. Mitt. Halogenierung von 2-Aryl-5-hydroxy-pyridazin-3(2H)-onen in 4-Stellung

Zusammenfassung Die Reaktion von 2-Aryl-5-hydroxy-pyridazin-3(2H)-onen (1a, b) mit Brom liefert die 4-Bromderivate2a, b, während mit Sulfurylchlorid3a, b erhalten werden. Ein Überschuß von Sulfurychlorid oder Chlorgas gibt jedoch das 4,4-Dichlor-pyridazin-dion4. Die Hydrolyse von4 führt unter Ringöffnung und Decarboxylierung zu5. In analoger Weise gibt die freie Carbonsäure6 das Hydrazon8.

     

Stereospecific radical addition of isopropanol andn-butanal to (5R)-(l-menthyloxy)furan-2(5H)-one

The radical addition of PrⁱOH andn-butanal to (5R)-5-(l-menthyloxy)furan-2(5H)-one occurs regio- and diastereospecifically at position 4 of the furanone ring.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 345–536, March, 1995.This work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-04497).     

The (E)/(Z)-ratio in the reaction of 5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines with bromine

Summary 3-Aryl-, 3-benzyl-, and 3H-5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines3a–h react with bromine in acetic acid solution to give mixtures of the respective 5-aroylmethylene (E) and (Z) diastereomeric derivatives5 and6. They contain more than 85% of the (E)-diastereomers along with some pure isomers. The intermediacy of the 5-bromo derivatives4 is proven and a plausible route of the reaction is presented. Structures of compounds3–6 are evidenced by analytical and spectral data.

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Das Verhältnis von (E)- und (Z)-Isomeren bei der Reaktion von 5-(2-Aryl-2-oxomethyl)-2-thioxo-4-oxo-1,3-thiazolidinen mit Brom

Zusammenfassung 3-Aryl-, 3-Benzyl- und 3H-5-(2-Aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidine3a–h reagieren mit Brom in essigsaurer Lösung zu Gemischen der entsprechenden diastereomeren 5-Arylmethylen-Derivate ((E) und (Z))5 und6. Sie enthalten mehr als 85% des (E)-Diastereomeren. Die intermediäre Natur der 5-Brom-Derivate4 wird bewiesen; ein Reaktionsweg wird vorgeschlagen. Die Strukturen der Verbindungen3–6 werden durch analytische und spektroskopische Daten abgesichert.

     

A convenient preparation of 2-thioxo-4(3H)-quinazolinones

A simple method is described for the preparation of 3-aryl-2-thioxo-4(3H)-quinazolinones (4) by the reaction of anthranilic acids and ammonium or triethylammonium N-aryl-dithiocarbamates in ethanol. The method is also applicable to the preparation of 3-ethyl-2-thioxo-4(3H)-quinazolinone.     

The complete closed coexistence curves for 2H,3H,6H,7H,8H-5,8-(Dimethylmethano)-5(R)-methylquinoxaline with water and with deuterium oxide

The complete closed solubility curves for 2H, 3H, 6H, 7H, 8H-5,8-(dimethylmethano)-5(R)-methylquinoxaline with water and with deuterium oxide have been determined. With water the lower critical solution temperature (LCST) was found to be 51.4°C and the critical solution temperature (CST) was found to be 215.0°C. With deuterium oxide the values were 40.4°C for the LSCT and 221.7°C for the CST. The deuterium oxide curve completely encompassed the water curve. Solution compositions at the critical temperatures were also determined.     

Efficient one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones from aromatic aldehydes and their one-pot oxidation to quinazolin-4(3H)-ones catalyzed by Bi(NO3)3·5H2O: Investigating the role of the catalyst

An efficient and novel synthesis of 2,3-disubstituted 2,3-dihydroquinazolin-4(1H)-ones via one-pot, three-component reaction of isatoic anhydride, primary amines and aromatic aldehydes catalyzed by Bi(NO₃)₃·5H₂O under solvent-free conditions is described. Oxidation of these 2,3-dihydroquinazolin-4(1H)-ones to their quinazolin-4(3H)-ones was also successfully performed in the presence of Bi(NO₃)₃·5H₂O. This new method has the advantages of convenient manipulation, short reaction times, excellent yields, very easy work-up, and the use of commercially available, low cost and relatively non-toxic catalyst. The role of Bi(NO₃)₃·5H₂O was also investigated in these transformations.     

3-甲基-4-芳亚甲基-异噁唑-5(4H)-酮的合成

报道了以吡啶为缚酸剂, 由乙酰乙酸乙酯、盐酸羟胺和芳香醛经三组分一锅法缩合制备3-甲基-4-芳亚甲基-异噁唑-5(4H)-酮衍生物的新方法. 产物结构经MS, ¹H NMR和IR确证.     

Reactions with pyrrolidine-2,4-diones,II: New approaches to the synthesis of substituted 5,6-dihydropyrrolo[3,4-d][1,2,3]triazol-4(2H,4H)ones

Summary Approaches leading to 5,6-dihydro-5,6-diphenyl-2-substituted-pyrrolo[3,4-d][1,2,3]-triazol-4(2H,4H)-ones (10) are described. The first approach consists of cyclodehydrating 3(or 4)-hydroxyimino-1,5-diphenyl-4(or 3)-(4-substituted phenylhydrazono)pyrrolidin-2-ones (4,7) with boiling acetic anhydride. The second approach involves cyclization of 3(or 4)-acetoxyimino-1,5-diphenyl-4(or 3)-(4-substituted phenylhydrazono)pyrrolidin-2-ones (8,9) with elimination of acetic acid upon treatment with sodium hydroxide.Part of the work has been presented at the 8^th International Congress of Heterocyclic Chemistry (August 1981), Graz, Austria     

Regio- and stereoselective 1,3-dipolar cycloaddition of arylnitrile oxides to 5-acetoxy-2(5H)-furanone

Summary Arylnitrile oxides undergo regio- and stereo-specific 1,3-dipolar cycloaddition reactions with 5-acetoxy-2(5H)-furanone. In each case a single product3a–3g results from ananti approach to the 5-acetoxy substituent, the oxygen of the 1,3-dipole being attached to C-4 of furan. Under similar conditions 5-benzoyloxy-2(5H)-furanone yields3h–3i. The structures of the adducts were determined by¹H- and¹³C-NMR spectroscopy.

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Regio- und stereoselektive 1,3-dipolare Cycloaddition von Arylnitriloxiden mit 5-Acetoxy-2(5H)-furanon

Zusammenfassung Arylnitriloxide reagieren mit 5-Acetoxy-2(5H)-furanon in einer regio- und stereoselektiven 1,3-dipolaren Cycloaddition. In jedem der untersuchten Fälle ergaben sich die einheitlichen Produkte3a–3g als Folge eineranti-Annäherung an den 5-Acetoxysubstituenten, wobei der Sauerstoff des 1,3-Dipols an das C-4 des Furans addiert. Unter ähnlichen Bedingungen ergab 5-Benzoyloxy-2(5H)-furanon die Produkte3h–3i. Die Strukturen der Addukte wurden mittels¹H-und¹³C-NMR bestimmt.