Fathi Kamel Rafla

Pyrone series. Part X. Reactivity of 4,5,6-triaryl-2-pyrones and the corresponding thio-analogues

Several 4,5,6-triaryl-3-bromo-2-pyrones have been prepared and converted by alcoholic alkali into furancarboxylic acids. These 3-bromo-2-pyrones and some triaryl-2-pyrones when treated with phosphorus pentasulphide gave the corresponding 2-thiopyrones, from which 1-methyl-2-thiopyridones, 2-pyrone phenylhydrazones, open-chain thioamides, and 1-thio-2-pyrones were obtained. 2-Pyridones, 1-amino-2-pyridones, 1-methyl-2-pyridones, 2-methoxypyridines, and 1-methoxy-2-pyridones have also been prepared. The i.r. and u.v. spectra of these compounds are recorded.

Synthesis of isoxazolo[3,4-b]pyridin-3(1H)-one and isoxazolo[5,4-b]-pyridin-3(2H)-one

α-(N′-Hydroxyamidino)acetohydroxamic acid (I) and 5-aminoisoxazol-3(2H)-one (V) were each condensed with acetylacetone to yield 2-hydroxyamino-4,6-dimethylpyridine-3-carboxylic acid (II) and 4,6-dimethyl-isoxazolo[5,4-b]pyridin-3(2H)-one (VIa) respectively. Compound (II) gave isoxazolo[3,4-b]pyridin-3(1H)-ones (III) on acetylation, benzoylation, and bromination. The structures of (II) and (VIa) were confirmed by their conversion into known products.

Pyridine-2-thiones, 2-pyrone phenylhydrazones, and 2-pyridones from 2-pyrones

Various 5-aryloxypyran-2-thiones, 2-pyridones, and 1-amino-2-pyridones have been prepared. The pyran-2-thiones were converted into pyridine-2-thiones and phenylhydrazones. Some derivatives of 6-p-bromophenyl-5-phenoxy-4-phenyl-2-pyrone (Ia) are described.

Pyrone series. Part IX. Some reactions of 1-amino-4,5,6-triaryl-2-pyridones

Six-membered copper bis-(1-salicylideneamino-4,5,6-triaryl-2-pyridone) complexes and a number of 1-arylidene-amino-, 1-phthalimido-, 1-succinimido-, and 1-maleimido-4,5,6-triaryl-2-pyridones have been prepared. Of these, the 1-arylideneamino-derivatives are not hydrolysed by hydrochloric acid, but copper chloride or 2,4-dinitrophenylhydrazine catalyses the formation of the free amine and the corresponding aldehyde.

Synthesis and reactions of potassium cyanoacetohydroxamate

The reaction of ethyl cyanoacetate with hydroxylamine gave potassium cyanoacetohydroxamate (I), which cyclised under basic conditions to yield the isoxazolone (IIIa). Reactions of (I) with hydroxylamine and acetylacetone gave α-(hydroxyamidino)acetohydroxamic acid (II) and the cyanopyridone (IV), respectively. The reaction with benzoyl chloride yielded three products [the O-benzoyl derivative (V), the isoxazolone (IIIb), and NO-dibenzoylhydroxylamine] in amounts depending on the reaction conditions.

Cyclic hydroxamic acids. Part I. Synthesis and reactions of 1,2-di-hydro-1-hydroxy-4,6-dimethyl-2-oxopyridine-3-carbonitrile

1,2-Dihydro-1-hydroxy-4,6-dimethyl-2-oxopyridine-3-carbonitrile has been prepared, hydrolysed to the corresponding amide and acid, decarboxylated, halogenated, and nitrated.

Pyrone series. Part XI. Reactivity of 4,6-diaryl-2-pyrones and cyclopropane derivatives obtained from 2-pyrazolines

4,6-Diaryl-2-pyrones and ethyl 2-aroyl-3-arylcyclopropanecarboxylates have been prepared from 2-pyrazolines. The structure of the pyrones was established by fission with alkali. Treatment of the cyclopropane derivatives with hydrazine hydrate gave diazabicycloheptenones, from which N-acetyl and N-methyl derivatives were prepared. The 2-pyrazolines were also converted into pyrazine derivatives (III), which gave N-oxides. The pyrones could be converted into 2-pyridones, 1-methyl-2-pyridones, 2-methoxypyridines, 1-amino-2-pyridones, 2-thiopyrones, 1-methyl-2-thiopyridones, and 1-thio-2-pyrones. The structures assigned to the products were established by u.v. and i.r. spectroscopy.