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A novel series of 2,4-disubstituted-1,2,4-triazolo[1,5-a]quinazolin-5(4H)-ones were prepared by Dimroth rearrangement of their respective isomers namely 1,4-disubstituted-[1,2,4]triazolo[4,3-a]-quinazolin-5(4H)-ones. The latter were prepared via new synthetic strategy based on 1,5-elecrocyclization of the respective N-(4-oxo-3-phenylquinazolin-2-yl)nitrilimines.

A series of pyrazolo[4,3-e][1,2,4]triazolo[4,3-c]pyrimidines were prepared via oxidative cyclization of aldehyde N-(1,3-diphenylpyrazolo[3,4-d]pyrimidin-4-yl)hydrazones. Dimroth rearrangement of such a series yielded pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines.

Two series of aldose N-(3-substituted-4-oxo-3,4-dihydroquinazolin-2-yl)hydrazones were prepared by the reaction of each of the aldoses with the appropriate 2-hydrazino-3-substituted-quinazolin-4(3H)-ones. Oxidative cyclisation of these aldose hydrazones with ferric chloride in ethanol yielded the title acyclo C-nucleosides.

A novel series of 2,4-disubstituted-l,2,4-triazolo[l,5-a]-quinazolin-5(4H)-ones were prepared by Dimroth rearrangement of their respective isomers namely 1,4-disubstituted[1,2,4]triazolo[4,3-a]-quinazolin-5(4Η)-ones. The latter were prepared via new synthetic strategy based on 1,5-elecrocyclization of the respective N-(4-oxo-3-cyclohexylquinazolin-2-yl)nitrilimines.