“On water” one-pot synthesis of quaternary centered 3-hydroxy-3-(1H-tetrazol-5-yl)indolin-2-ones

An efficient green protocol has been developed for the synthesis of 3-hydroxy-3-(1H-tetrazol-5-yl)indolin-2-ones and 3-(phenylamino)-3-(1H-tetrazol-5-yl)indolin-2-ones as a novel class of oxindole derivatives by metal-free azide-nitrile [2 + 3] cycloaddition with excellent yields.