Oxalic acid dihydrate and proline based low transition temperature mixture: An efficient synthesis of spiro [diindenopyridine-indoline] triones derivatives

The new facile approach has been developed for the synthesis of spiro [diindenopyridine-indoline] triones under the umbrella of green chemistry. The developed protocol is endowed with the use of low transition temperature mixture as a green reaction medium, operational simplicity, easy workup procedures, good to excellent product yields, and non-chromatographic purification procedure. Since indenone fused motifs have a broad spectrum of biological activities, this protocol is expected to find application in the combinatorial synthesis of biologically active compounds.