The use of 3-bezylidene phthalide as synthon in synthesis of heterocyclic compounds

Abstract EN

2-(α-Phenylacetyl) benzohydrazide (1) was prepared through the reaction of (Z)-3- enzylidene phthalide and hydrazine hydrate.

Treatment of compound (1) with substituted benzoyl chloride yielded N'-aroyl-2-(α-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-(α-phenylacetyl) benzohydrazide derivatives (4a-f).

Intramolecule cyclization of the latter compounds by means of acetic anhydride yielded 2-(α-phenylacetyl)phenyl-4-acetyl-4, 5-dihydro-5-aryl-1, 3, 4- oxadiazoles (5a-f).

Compounds 2-(α-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.