The discovery of oxazolones-grafted spirooxindoles via three-component diversity oriented synthesis and their preliminary biological evaluation.

A facile method via 1,3-dipolar cycloaddition of substituted benzylidene-2-phenyloxazolone under mild conditions with azomethine ylides, which were generated in situ by a decarboxylative route from a common set of diverse isatins and amino acid derivatives was developed for a 15-membered library of regio- and stereoselective oxazolones-grafted spirooxindole-pyrrolidine, pyrrolizidines and pyrrolothiazoles. After screening their cytotoxic activities against a spectrum of cell-lines, compound 4h was identified as potent antitumor agent and inducing apoptosis. The present study has provided an effective entry to rapidly construct a chemical library of oxazolones-grafted spirooxindoles and developed a good lead compound for subsequent optimization.