B(HSO4)3 as a recyclable solid acid catalyst for the synthesis of 2H-indaxolo [1, 2-b] phthalazine-triones in solvent-free medium

Boron sulfonic acid was applied as an efficient heterogeneous and reusable catalyst for the synthesis of 2H-indazolo[1,2-b] phthalazine-trione derivatives. A broad range of aromatic aldehydes were condensed via a one-pot three component reaction with phthalhydrazide and dimedone. The process was done under solvent-free conditions. High yields, short reaction times, easy work-up, eco-friendly, easy handling, availability and reusability of the catalyst are the main aspects of the present method.