US8933248: 3-substituted-3-hydroxy oxindole derivatives and process for preparation thereof

The invention relates to expedient method for synthesis of 3-substituted-3-hydroxy-oxindole derivatives, which are useful as synthetic precursors to valuable pharmaceutical compounds. These are synthesized by reacting nitromethane with the corresponding isatins of formula (I). The reaction process of isatins was carried using water as a solvent at room temperature to form the corresponding 3-hydroxy-3-nitromethylindolin-2-ones of formula (II).