An efficient one-pot four-component synthesis of 1H-pyrazolo[1,2-b] phthalazine-5,10-dione derivatives catalyzed by proline

The present report articulates a potential and green method for the synthesis of pyrazolo[1,2-b]phthalazine-5,10-dione by one-pot four component reaction involving phthalimide (1), hydrazine hydrate (2), aldehyde (3) and malononitrile (4). Proline has been utilized as organo-catalyst in a mixed solvent of ethanol and water in the ratio of 2:1 at 80 degrees C. The reaction reveals excellent reactivity, functional group tolerance, and quite high yields without using any extreme reaction condition like strong acid or metal catalyst. Eighteen compounds have been synthesised by this method including five new compounds.