Tetramethylguanidiniumtriflate catalyzed Henry reaction of isatins: An efficient synthesis of 3-hydroxy-3-(nitromethyl)indolin-2-one derivatives and their anti-diabetic activity

The ionic liquid, N,N,N,N-tetramethylguanidiniumtriflate (TMGTf) was found to be an efficient catalyst solvent for Henry reaction between nitromethane and isatin derivatives to provide 3-hydroxy-3-(nitromethyl)indolin-2-one under mild conditions. The ionic liquid amenable to successive recycling without appreciable decrease in activity. Synthesized compounds have been screened for their anti-diabetic activity.