Facile Synthesis of 3‐Hydroxy Oxindole by a Decarboxylative Aldol Reaction of β‐Ketoacid and Isatin in WERSA

Facile synthesis of bioactive 3‐hydroxy‐oxindole by decarboxylative aldol reaction via in‐situ generated methyl enolate of β‐ketoacid and isatin in Water Extract of Rice Straw Ash (WERSA) is described. This method provides clean, simple and useful alternative to synthesize 3‐hydroxy‐oxindole. The products were isolated in excellent yield without using column chromatography. The green chemistry matrices calculated, and it also shows green protocol used. We have developed a novel protocol to perform the decarboxylativ aldol reaction in WERSA for the synthesis of bioactive 3‐hydroxyoxindoles at room temperature. Here WERSA were used as solvent and catalyst. The transformation did not require any activation by conventional transition metal catalyst, toxic ligand, organic solvent or by base and so on. This bio‐mass derived medium are cheap, convinient, easily available, durable, highly active and more importantly sustainable, eco‐friendly. The products were isolated without using coloum chromatography and excellent in yield. Green chemistry matrices also shows the protocol were used green.