“On water” catalyst-free, column chromatography-free and atom economical protocol for highly diastereoselective synthesis of novel class of 3-substituted, 3-hydroxy-2-oxindole scaffolds at room temperature

The “on water” highly atom economical and diastereoselective synthesis of a novel class of 3-(thiazolidinedione or oxindole) substituted, 3-hydroxy-2-oxindole scaffolds has been achieved by the reaction of isatin electrophiles with thiazolidinedione or oxindole nucleophiles in a catalyst-free and column chromatography-free protocol at room temperature. The generality of the method has been demonstrated by screening a series of isatin electrophiles as well as thiazolidinedione and oxindole derivatives. The developed method is one of the rare examples of an ideal green protocol for the synthesis of medicinally important 3-hydroxy-2-oxindole scaffolds in which the straightforward synthesis of such a framework was achieved by employing very mild, simple and handy procedures from readily available starting materials.