A robust and rapid synthesis of 3-hydroxy-3-alkyl-2-oxindoles from isatins is described. This method introduces an ecofriendly, un-activated Zn dust, solid NH₄Cl and substrates under aqueous conditions, which has produced the product in moderate to good yields. Without using column chromatography, majority of the compounds were isolated in analytically pure form. The progress of the reaction could be visualized by naked eye.
