This research reports a green and efficient protocol for the one-pot synthesis
of dihydro-1H-indeno[1,2-b]pyridines and polysubstituted imidazoles
using a recyclable acidic ionic liquid [H-NP]HSO4 (H-NPBS). Non-corrosiveness,
safe, low waste, generality, simplicity, easy for separation, short reaction
times, high yields and environmentally benign are some of the
advantages of this methodology. The [H-NP]HSO4 (H-NPBS) has been
effectively recycled for six consecutive cycles without appreciable loss in
its activity