10.1021/acs.joc.9b02608.s002 Jothi Lakshmi Nallasivam Jothi Lakshmi Nallasivam Tushar Kanti Chakraborty Tushar Kanti Chakraborty Titanocene(III)-Mediated 5‑exo-trig Radical Cyclization: En Route to Spirooxindole-Based Tetrahydrofuran and Bicyclic Lactone American Chemical Society 2019 exhibit oxirane-ring Spirooxindole-Based Tetrahydrofuran cyclization Cyclization Ti isatin core system array availability Bicyclic Lactone epoxy-acrylate En Route Titanocene presence tetrahydrofuran-based oxa-spirooxindole systems ester scope lactone quaternary center reductive opening importance spectrum intramolecular 5- exo-trig reactive prochiral C -3 position application oxa-spirooxindole molecules oxindole-appended Radical Herein disubstituted isatin-derived Cp spirooxindole heterocyclic motifs hydroxyl 2019-12-11 13:10:07 Dataset https://acs.figshare.com/articles/dataset/Titanocene_III_-Mediated_5_exo-trig_Radical_Cyclization_En_Route_to_Spirooxindole-Based_Tetrahydrofuran_and_Bicyclic_Lactone/11353406 The isatin core system is of immense importance due to the highly reactive prochiral C-3 position, which paves an easy way to construct large arrays of spirooxindole heterocyclic motifs. Herein, we depict an isatin-derived and 3,3′-disubstituted oxindole-appended epoxy-acrylate undergoing Cp<sub>2</sub>Ti­(III)­Cl-mediated reductive oxirane-ring opening with concomitant intramolecular 5-exo-trig radical cyclization leading to tetrahydrofuran-based oxa-spirooxindole systems. The fused spirooxindole structural feature is embedded in many natural products and tends to exhibit a wide spectrum of biological activities. The presence of more than one quaternary center and the availability of multiple functional groups like hydroxyl, ester, or lactone in the resultant products expand the scope of synthetic applications of the newly acquired oxa-spirooxindole molecules.