Choline hydroxide promoted sustainable one-pot three-component synthesis of 1H-pyrazolo[1,2-a]pyridazine-2-carbonitriles under solvent-free conditions

A sustainable one-pot three-component synthesis of novel 1H-pyrazolo[1,2-a]pyridazine-2-carbonitrile derivatives employing a highly efficient, biodegradable, and recyclable choline hydroxide catalyst under solvent-free conditions is demonstrated. The salient features of this protocol are simple workup, mild reaction conditions, short reaction time (10 min), excellent yields (up to 97%), high atom economy, column chromatography-free protocol, and eco-friendliness. Interestingly, the choline hydroxide was recycled up to five cycles without any considerable loss of efficiency. The structures of the products were deduced by their H-1 NMR, C-13 NMR, and HRLC-MS spectra.