Synthesis of new polydimethylsiloxane-polyamide copolymers from phenylene-bis-5-oxazolones and aminopropyl-terminated polydimethylsiloxane oligomers

Alternating polydimethylsiloxane-polyamide block copolymers were prepared in dichloromethane or chloroform solution at room temperature from 3-amino-n-propyl-terminated polydimethylsiloxane oligomers and 2,2′-p-phenylenebis(4,4-dimethyl-5-oxazolone). Solution and thermal properties of the polymers were characterized.     

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.

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Synthesis and spectral-lumine scence properties of 2- aryl- 4- benzylide ne-5-oxazolones

A number of 2-aryl-4-benzylidene-5-oxazolones was obtained by condensation of benzaldehyde with N-acylglycines. The absorption and fluorescence spectra in chloroform at 77 °K were measured. The spectral characteristics of the investigated and previously synthesized 2-phenyl-4-arylidene-5-oxazolones are compared.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 909–911, July, 1980.     

Fluorescent Orthopalladated Complexes of 4-Aryliden-5(4H)-oxazolones from the Kaede Protein: Synthesis and Characterization

The goal of the work reported here was to amplify the fluorescent properties of 4-aryliden-5(4H)-oxazolones by suppression of the hula-twist non-radiative deactivation pathway. This aim was achieved by simultaneous bonding of a Pd center to the N atom of the heterocycle and the ortho carbon of the arylidene ring. Two different 4-((Z)-arylidene)-2-((E)-styryl)-5(4H)-oxazolones, the structures of which are closely related to the chromophore of the Kaede protein and substituted at the 2- and 4-positions of the arylidene ring (1a OMe; 1b F), were used as starting materials. Oxazolones 1a and 1b were reacted with Pd(OAc)₂ to give the corresponding dinuclear orthometalated palladium derivates 2a and 2b by regioselective C–H activation of the ortho-position of the arylidene ring. Reaction of 2a (2b) with LiCl promoted the metathesis of the bridging carboxylate by chloride ligands to afford dinuclear 3a (3b). Mononuclear complexes containing the orthopalladated oxazolone and a variety of ancillary ligands (acetylacetonate (4a, 4b), hydroxyquinolinate (5a), aminoquinoline (6a), bipyridine (7a), phenanthroline (8a)) were prepared from 3a or 3b through metathesis of anionic ligands or substitution of neutral weakly bonded ligands. All species were fully characterized and the X-ray determination of the molecular structure of 7a was carried out. This structure has strongly distorted ligands due to intramolecular interactions. Fluorescence measurements showed an increase in the quantum yield (QY) by up to one order of magnitude on comparing the free oxazolone (QY < 1%) with the palladated oxazolone (QY = 12% for 6a). This fact shows that the coordination of the oxazolone to the palladium efficiently suppresses the hula-twist deactivation pathway.     

Synthesis and transformations of 4(5H)-oxazolones and their salts (review)

The literature data on the synthesis and transformations of 4(5H)-oxazolones and their salts are correlated. An evaluation of the possibilities of the preparative utilization of the examined reactions is given.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 723–740, June, 1991.     

Synthesis of new 4(3H)-quinazolinone derivatives using 5(4H)-oxazolones

New derivatives of 5(4H)-quinazolinone containing 2-imidazolin-5-one rings have been prepared from 5(4H)-oxazolone derivatives.     

Preparation and properties of polyamides from 2,2′-p-phenylenebis-5-oxazolones with diamines

Novel phenylated polyamides having inherent viscosities in the range of 0.2–0.4 were prepared by the ring-opening polyaddition of 2,2′-p-phenylenebis(4,4-diphenyl-5-oxazolone) with aliphatic diamines in polar aprotic solvents. Similarly, unsubstituted polyamides were obtained from 2,2′-p-phenylenebis-5-oxazolone and both aliphatic and aromatic diamines. The phenylated polyamides were highly soluble in a wide range of solvents including tetrahydrofuran and dioxane, while the unsubstituted polymers showed limited solubility in the solvents. No marked differences in thermal stability between the phenylated and unsubstituted polyamides were noted, and all the polyamides began to decompose at around 250°C in both air and nitrogen.     

Substituted 4(5h)-oxazolones and their salts

2,3,5-Substituted 4(5H)-oxazolonium perchlorates were obtained by condensation of 2-methyl-substituted 4(5H)-oxazolonium perchlorates with aromatic and furan aldehydes and ketones and acetone, and their IR, UV, and PMR spectral characteristics were investigated.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 30–35, January, 1980.     

Substituted 4(5H)-oxazolones and their salts. 3. Synthesis of 4(5H)-oxazolonium salts from amides of 2,4-dihydroxy-3,3-dimethylbutanoic acid

2-Alkyl-substituted 4(5H)-oxazolonium salts were synthesized by the reaction of amides of 2,4-dihydroxy-3,3-dimethylbutanoic (pantoic) acid with aliphatic carboxylic acid anhydrides in the presence of an equimolar amount of perchloric acid. The hydrolysis of these salts was realized. Various acyl derivatives of pantoic acid amides were obtained, and the possibility of their cyclization to give 4(5H)-oxazolonium salts under the influence of condensing reagents was demonstrated. The mechanism of the heterocyclization of pantoic acid amides is discussed on the basis of these results.See [1] for communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 894–900, July, 1981.     

Reaction of 4-methylene-5(4H)-oxazolones with diazomethane

The reaction of diazomethane with some (E) and (Z)-2-substituted-4-methylene-5(4)-oxazolones ( 1a-c ) under two different conditions, has been studied. (E) and (Z)-1,2-disubstituted-7-oxo-6-oxa-4-azaspiro[2.4]-hept-4-enes ( 3a-c, 4a-c ) were mainly obtained, together with multiple addition compounds. The reaction showed to be stereoselective only when the substituents were aromatic. Acid hydrolysis of compounds 3a and 4a produced a mixture of (E) and (Z)-3,5-disubstituted-tetrahydrofuran-2-ones ( 8a, 9a ). Smooth methanolysis of the ring led to (E) and (Z)-1-benzamido-cyclopropanecarboxylic esters ( 10a-c, 11a-c ), which, on acid hydrolysis, gave (E) and (Z)-1-amino-2-phenylcyclopropanecarboxylic acids 12a and 13a . The pmr spectra have been analyzed by an iterative computer method, and the computed best values obtained have been used to deduce the stereochemistry of the spiroderivatives.     

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.

     

The transformations of 4-heteroarylaminomethylene-5(4H)-oxazolones into dehydropeptide derivatives

2-Phenyl-4-heteroarylaminomethylene-5(4H)-oxazolones 3 , which were prepared from the corresponding N,N-dimethyl-N'-heteroarylformamidines 1 and hippuric acid 2 in acetic anhydride, react with amino acids giving dehydropeptide derivatives 4, 5 , and 6 as products. Dehydration of N-protected peptides 7–10 , containing glycine at the C-terminal, followed by the reaction with formamidines 1 gave 2-substituted-4-heteroarylaminomethylene-5(4H)-oxazolones 11–14 .     

4-Phosphoranylidene-5(4H)-oxazolones II. Reactions with alkylating agents

Summary When treated with alkyl halides at 20–90°C without solvent or in acetonitrile, 4-phosphoranylidene-5(4H)-oxazolones (1) give 4-C-alkylation products4 in good yields. Alkylation of1 with alkyl triflates in CH₂Cl₂ at room temperature results in O-alkylation products5. No O-to 4-C-alkylation rearrangement can be observed. The spectroscopic properties of the alkylation products are reported and discussed.

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4-Phosphoranyliden-5(4H)-oxazolone, 2. Mitt. Reaktionen mit Alkylierungsreagentien

Zusammenfassung Behandlung von 4-Phosphoranyliden-5(4H)-oxazolonen (1) mit Alkylhalogeniden bei 20–90°C ohne Lösungsmittel oder in Acetonitril liefert in guten Ausbeuten die 4-C-alkylierten Produkte4. Alkylierung von1 mit Alkyltriflaten in CH₂Cl₂ bei Raumtemperatur ergibt O-alkylierte Produkte (5). E6 wurde keine Umlagerung von O-alkylierten zu C-alkylierten Verbindungen beobachtet. Die spektroskopischen Eigenschaften der Alkylierungsprodukte werden berichtet und diskutiert.

     

Catalytic Enantioselective Methanolysis of 4 -substituted-2-phenyl-5(4H)-oxazolones by Cinchonine

Theopeningoftheringof5(4H)-oxazolonesisoneofthemethodsforthesynthesisof-..-non-racemica-aminoacids.Thediastereoselectivering-openingof5(4H)-oxazolonesbychiralnucleophilesandenantioselectivehydrolysisandalcoholysisof5(4H)-oxazolonesbyenzymeshavebeenextensivelyinvestigated'.However,toourknow1edgenon-enzymecatalyzedenantioselectivealcoholysisof5(4H)-oxazoloneshasnotbeenreported.Inthispaper,wereportonthefirstnon-enzymecatalyzedenantioselectivealcoholysisof5(4H)-oxazolonesbycinchonine.As4-substit…     

1,3-Dipolar cycloaddition reactions of 2-phenyl-4-arylidene-5(4H)-oxazolones with nitrile oxides

Stable nitrile oxides are added stereospecifically and regioselectively to the carbon carbon double bond of 2-phenyl-4-arylidene-5(4H)-oxazolones resulting spiro-derivatives 3, 5 . The spectral properties of the reaction products are discussed. The cycloadducts give several substituted isoxazolines via an opening of the oxazolone ring with nucleophilic reagents.     

Synthesis of liquid-crystalline substances from the 5-alkyl-5-arylisoxazole series

The oxidation of 3-(4-acetoxyphenyl)-5-pentyl-2-isoxazoline with N-bromosuccinimide followed by hydrolysis of the oxidation product furnished 3-(4-hydroxyphenyl)-5-pentyl-isoxazole. Its esterification or benzylation afforded the target liquid-crystalline 3-aryl-5-pentyl-isoxazoles.     

由5-噁唑烷酮合成二肽类的简便方法(英文)

用一锅法制得了２－三溴甲基－３－甲酰基－４－甲基－５－氧－口恶唑烷酮,它与脯氨酸甲酯及其它氨基酸酯反应生成Ｎ－甲基－Ｌ－丙氨酰脯氨酸甲酯和系列Ｎ－甲基－Ｌ－丙氨酰的二肽     

Synthesis of N-benzyloxycarbonyl-N-methylaminoacids from oxazolidine-5-one derivatives

Hydrogenolysis of 3-benzyloxycarbonyloxazolidine-5-one and 3-benzyloxycarbonyl-4-benzyloxazolidine-5-one by Et₃SiH in the presence of F₃.CCO₂H is demonstrated to be a convenient method for preparing substituted N-methylaminoacids. In contrast with catalytic hydrogenation on Pd/C catalyst, the benzyloxycarbonyl is not removed and the methyl is not lost using this method.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–683, May, 1992.