Abstract
A Brønsted acidic ionic liquid [Bu
3
NH][HSO
4
] as an eco-efficient catalyst for the one-pot multicomponent synthesis of 1
H
-pyrazolo[1,2-
b
]phthalazine-5,10-diones and 2
H
-indazolo[2,1-
b
]phthalazine-triones by using various aldehyde, malononitrile/dimedone, and phthalhydrazide in the absence of a solvent at 80 °C is described. Further, the catalyst is prepared from readily available reagents and fully characterized by different techniques such as FT-IR,
1
H-NMR,
13
C-NMR, and TG, DTG and DTA analyses. The current synthetic protocol offers the mild reaction conditions, short reaction times (9–30 min), excellent yields of the products (83–95%), a clean and straightforward work-up, reusability of the catalyst up to seven catalytic runs, and a sustainable alternative to the existing methods.