Abstract
An efficient one-pot synthesis of 1 H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives via three-component condensation reaction of phthalhydrazide or 4-phenylurazole, aldehydes or isatins and dimedone in the presence of a catalytic amount of silica-supported tungstic acid (STA), as a heterogeneous solid acid catalyst under solvent-free conditions is presented. This ecofriendly protocol offers several advantages such as a cost-effective procedure with excellent yields, short reaction time, simple workup, recovery and reusability of catalyst with broad scope of usable substrates. This has made the protocol sustainable and economic.
Graphical Abstract
![](/cms/asset/fe0da9fe-3cb3-4d1d-b8ef-95f908ae37d7/gpss_a_1661414_uf0001_c.jpg)
Disclosure statement
No potential conflict of interest was reported by the authors.