1- (Phthalazin-l'-yl-amino)-3-chloro-4-aryl-4H-(4o-rm ethyl)-2-azetidinones (3) were prepared by cycloaddition of-methyl substituted benzal hydrazinophthalazine (2) with chloro acetylchloride. The hydrazone (2) was synthesised by the condensation of 1- hydrazinophthalazine (1) with substituted aromatic aldehydes, ketones 7 acetophenones. 1- Hydrazinophthalazine was prepared from the phthal...