2-benzoyl-4-phenyl

The treatment of 3-acylisoxazoles (438) with hydroxylamine hydrochloride gives furazan ketones (439). On the other hand, furazan ketones (439) rearrange to 3-acylisoxazoles (438) with a loss of hydroxylamine under the influence of a mineral acid. Thus, by refluxing phenacylphenylfurazan with concentrated alcoholic hydrogen chloride, 3-benzoyl-5-phenyl-isoxazole is formed similarly, phenyl(phenacylphenyl)furazan gives 3-benzoyl-3,5-diphenyl-isoxazole (62HC(17)1, p. 35). 

The role of substituents X on the mononuclear heterocyclic rearrangement (MHR) of 20 phenylhydrazones 54 of 3-benzoyl-5-phenyl-l,2,4-oxadiazole into the triazoles 55 (Equation 2) has been investigated, allowing the influence of X on the product distribution to be evaluated and first-order rate constants and Hammett correlations to be determined <1999T12885>. 

Isomerization and Rearrangement of E Arylhydrazones of 3-Benzoyl-5-phenyl-1,2,4-oxadiazoles... 

The stability of the ring system decreases considerably when one hydrogen atom is left unsubstituted (55 b). It has been claimed that 5-monosubstituted oxadiazoles like XLII could not exist, as it was not possible to isolate the 5-phenyl derivative by decarboxylation of the corresponding acid or by hydrolyzing the 3-benzoyl-5-phenyl compound. 

However, hydrolysis of the oxime of 3-benzoyl-5-phenyl oxadiazole leads to benzoyl cyanamide (76). 

Bei der Oximierung von 3-Benzoyl-5-phenyl-l,2,4-oxadiazol wird ein Gemisch aus 3-( -Hydroximino-benzyl)-5-phenyl-l,2,4-oxadiazol (III 33%) und 4-Benzoylamino-3-phenyl-fura-zan (V 57%) erhaltcn107 ... 

Da unter den Reaktionsbedingungcn das Oxim IV sich zum Furazan V umlagcrt, kann angenommen werden, daB bei dcr Umsetzung von 3-Benzoyl-5-phenyl-l,2,4-oxadiazol mit Hydroxylamin zum Furazan V die Stufe des (Z)-Oxims IV durchlaufen wird. Das Verhiiltnis Oxim/Furazan hangt von den Substituenten am 3-Acyl-l,2,4-oxadiazol ab108,109. 

Bei der Behandlung von 4-(2-Oxo-2-phenyl-ethyl)-3-phcnyl-furazancn mit cthanolischcr Salz-saure entstehen 3-Benzoyl-5-phenyl-l,2-oxazole auf folgendem Wege327,328 ... 

R = H 3-Benzoyl-5-phenyl-1,2-oxazol R = C6h5 3-Benzoyl-4,5-diphenyl-... 

The addition of amyl nitrate to a suspension of 2,4-diphenyl-5-nitro-soimidazole (37) in ether results in a mixture of 2,4-diphenyl-5-nitroim-idazole (38) and 3-benzoyl-5-phenyl-l, 2,4-oxadiazole (39), but a similar reaction using 4-phenyl-5-nitrosoimidazole gives only 3-benzoyl-1,2,4-oxadiazole (40) (60MI1). 

The kinetics for rearrangement of di-, tri-, tetra-, and penta-substituted (Z)-arylhy-drazones of 3-benzoyl-5-phenyl-l,2,4-oxadiazole to 2-aryl-4-benzoylamino-5-phenyl-... 

Similar behavior is shown by 3-acyl-l,2,4-oxadiazoles and their oximes. Thus 3-benzoyl-5-phenyl-l,2,4-oxadiazole is transformed by hydroxylamine into 3-benzamido-4-phenylfurazan, while the oximes of 3-aroyl- and 3-acetyl-5-methyl-1,2,4-oxadiazoles afford 3-aryl- and 3-methyl-4-aminofurazans in the presence of 6M hydrochloric acid. 

Benzoyl-5-bromo-2-pyrazinamine (116, R = Br) gave 3-benzoyl-5-phenyl-2-... 

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