InCl3-catalyzed green synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones under solvent-free conditions

A simple, efficient, and green practical approach to 1H-pyrazolo[1,2-b]phthalazine-5,10-diones from phthalhydrazide, aldehydes, and malononitrile/ethyl cyanoacetate has been developed that uses inexpensive and readily available InCl3 as a catalyst in solvent-free one-pot three-component cyclo condensation reaction. This method should provide high yields, shorter reaction time, easy work-up, purification of products by nonchromatographic method, and cleaner reaction. It is a new strategy for N-fused heterocycles synthesis, which haswider application in organic and medicinal chemistry.