Microwave mediated synthesis of spiro-(indoline-isoxazolidines): mechanistic study and biological activity evaluation

Regioisomeric spiro-(indoline-isoxazolidines) have been synthesized in moderate yields by the cycloaddition reaction between ethyl (3-indolylidene)acetate and various substituted α,N-diphenylnitrones, using environmentally benign microwave technology. A novel concerted reaction mechanism is described that explains the preferential formation of the regioisomeric spiro-(indoline-isoxazolidine) analog 6 over 5. These compounds were screened for anti-mycobacterial and anti-invasive activities against tumor cells.