3-Aryl-3-methyl

Isoxazole, 5-(p-anisyl)-3-phenyI-synthesis, 6, 63 Isoxazole, 4-aroyl-3,5-diaryI-synthesis, 6, 71 Isoxazole, aryl-UV spectra, 6, 4 Isoxazole, 3-aryl-5-unsubstituted ring cleavage, 6, 30 Isoxazole, 5-aryl-3-chloro-reactions, 5, 104 Isoxazole, 3-aryI-4-formyl-synthesis, 6, 84 Isoxazole, 3-aryl-5-methoxy-thermal isomerization, 6, 15 Isoxazole, 3-aryl-5-methyl-synthesis, 6, 63, 84 Isoxazole, 4-azorearrangement, 5, 719... 

Acyl hydrazides are useful precursors for the synthesis of 1,2,4-triazoles. Reaction of acyl hydrazides 149 with imidoylbenzotriazoles 148 in the presence of catalytic amounts of acetic acid under microwave irradiation afforded 3,4,5-trisubstituted triazoles 150 <06JOC9051>. Treatment of A-substituted acetamides with oxalyl chloride generated imidoyl chlorides, which reacted readily with aryl hydrazides to give 3-aryl-5-methyl-4-substituted[ 1,2,4]triazoles <06SC2217>. 5-Methyl triazoles could be further functionalized through a-lithiation and subsequent reaction with electrophiles. ( )-A -(Ethoxymethylene)hydrazinecarboxylic acid methyl ester 152 was applied to the one-pot synthesis of 4-substituted-2,4-dihydro-3//-1,2,4-triazolin-3-ones 153 from readily available primary alkyl and aryl amines 151 <06TL6743>. An efficient synthesis of substituted 1,2,4-triazoles involved condensation of benzoylhydrazides with thioamides under microwave irradiation <06JCR293>. 

The oxidation of aromatic aldoximes with ceric ammonium nitrate produces nitrile oxides which undergo subsequent cycloaddition to nitriles to produce 1,2,4-oxadiazoles (Equation 47) <1997PJC1093>. The anodic oxidation of aromatic aldoximes in the presence of acetonitrile has been reported to give low yields of either 3-aryl-5-methyl-1,2,4-oxadiazoles (2-25%) or 3,5-bis-aryl-l,2,4-oxadiazoles (6-28%), although the synthetic utility of this route is limited by competitive deoximation to the carbonyl being the major reaction pathway <1997MI3509>. 

Aryl-5-methyl-I,2,4-oxadiazoles serve as monodentate ligands for a number of transition metal complexes <85SA(A)1433>. 

Heating of aromatic aldehydes with nitroethane and ammonium acetate in glacial acetic acid affords 3-aryl-5-methyl-1,2,4-oxadiazoles in moderate yields <85JOCli82>. 

Das durch Pcriodat-Oxidation von 0-Acetoxy-N-(l-amino-ethyliden)-hydroxylaminen erhsilt-liche 1-Hydroximino-l-nitroso-ethan setzt sich mit Benzylhalogeniden zu 3-Aryl-5-methyl-l,2,4-oxadiazol-4-oxiden um56 ... 

Die Kondensation von Formyl-arenen, Nitro-ethan und Ammoniumacetat im Molverhaltnis 1 40 8 fllhrt in Eisessig zu 3-Aryl-5-methyl-l, 2,4-oxadiazolen als Hauptprodukt. Der komplexe Ablauf ist in den einzelnen Stufen aufgeklart und abgesichert31. 

Die reduktive Offnung von 3-Aryl-5-methyl-l,2,4-oxadiazolen mit Triphenylphosphan bei 200° fiihrt letztlich zu Cyan-arenen, Acetonitril und Triphenylphosphanoxid als isolierten Pro-dukte288 ... 

Antifungal 3-aryl-5-methyl-2,5-dihydrofuran-2-ones were reported, where the 3-aryl group was introduced by palladium chemistry. The yields were generally moderate, possibly due to the instability of the core structure at high temperatures (Scheme 60) [144],... 

As indicated in Section II,A,2,a, (5-aryl-l,2-dithiol-3-ylidene)malonic acids (14) give, by decarboxylation and protonation, 3-aryl-5-methyl-1,2-dithiolium cations (36). In the presence of aromatic amines, two types of compounds may be obtained37, resulting from the condensation of 36 with the amine, and 38, resulting from the condensation of 36 with its conjugate base (cf. Ref. 1 p. 83). 

More recently is has been reported that heating 3-aryl-5-methyl-l, 2,4-oxadiazoles with benzyl alcohol affords mainly the aryl nitrile, benzyl acetate and benzaldehyde however, 1,3,5-triazines could be detected among a number of other products.14... 

The thermodynamically more stable lithium enolate of phenylacetone, regioselectively prepared in situ with lithium diisopropylamide (LDA) at 0 °C, reacted with arylnitrile oxides giving 5-hydroxy-2-isoxazolines 19. The adducts were dehydrated under basic conditions to afford 3-aryl-5-methyl-4-phenylisoxazoles 20 in 38-73% overall yields. The phenyl and 5-chloro-2-furyl derivatives 20 are selective cyclooxygenase-1 (COX-1) inhibitors <04JMC4881>. 

Scheme 1S.28. Preparation of 3-aryl-5-methyl-2,5-dihydrofuran-2-ones.

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