The Use of 3-Bezylidene Phthalide as Synthon in Synthesis of Heterocyclic Compounds

2-(-Phenylacetyl) benzohydrazide (1) was prepared through the reaction of (Z)-3-benzylidene phthalide and hydrazine hydrate. Treatment of compound (1) with substituted benzoyl chloride yielded N'-aroyl-2-(-phenyl acetyl) benzohydrazide (2a-e) which upon reaction with ammonium acetate provided the corresponding 2-phenyl-1-(2-(5-aryl-1,2,4-triazole-3-yl)phenyl)ethanones (3a-e). While the reaction of compound (1) with substituted benzaldehyde gave the hydrazones represented by N'-arylidene-2-(-phenylacetyl) benzohydrazide derivatives (4a-f). Intramolecule cyclization of the latter compounds by means of acetic anhydride yielded 2-(-phenylacetyl)phenyl-4-acetyl-4,5-dihydro-5-aryl-1,3,4-oxadiazoles (5a-f).
Compounds 2-(-phenylacetyl)-N-(3,6-diphenyl-5-aryl-5,6-dihydro-1,2,4-triazine-4yl) benzamide (6a-f) were also obtained from the direct Diel-Alder reaction between dibenzylidine hydrazine as diene and compounds (4a-f) as dienophile enhanced by microwave irradiation.
The assigned structure of the prepared compounds were corroborated by available physical and spectral methods