“On water” catalysis: an expeditious approach for the synthesis of quaternary centered 3-hydroxy-3-(nitromethyl)indolin-2-one derivatives
A novel, efficient, eco-friendly “on water” method has been developed for the Henry reaction of isatins with nitromethane to afford 3-hydroxy-3-nitromethylindolin-2-ones. An enhancement in reaction rate was observed “on water” under mild and catalyst-free conditions. This reaction tolerated a wide range of substrates with good to excellent product yields and is even applicable at large scales. Moreover, this method is environmentally friendly as it reduces the waste generated by the use of toxic solvents.