Condensation Reactions of 2-Aminobenzohydrazide with Various Carbonyl Compounds

Technical iodine was found to catalyze the condensation between 2-aminobenzohydrazide (1) and some aldehydes and ketones in absolute ethanol under mild conditions to afford hydrazone and quinazoline derivatives, respectively. Condensation of 1 with terephthalaldehyde (2) in 1: 1 molar ratios afforded the hydrazone 3, while hydrazone 4 was formed on using a double molar ratio of 1. On the other hand, compound 1 condensed with 4-formyl [2.2]paracyclophane (5) to give the hydrazone 6. However, spiro-quinazolines 8, 10, 12, and 14 were formed when compound 1 reacted with ketones such as N-benzylpiperidone (7), indane-1,2,3-trione (9), cyclohexane-1,2-dione (11), and dimedone (13), respectively. Treatment of 1 with tetrabromophthalic anhydride (TBPA, 18) and pyromellitic dianhydride (PMDA, 20) furnished phthalazino-quinazoline 19 and 21, respectively. The products were fully characterized according to their spectral analyses. The mechanisms of formation of the products have been rationalized.