A Comparison of the Photosensitized Rearrangement and the Lewis‐Acid‐Catalyzed Rearrangement of Spirooxindole Epoxides

Abstract

Abstract Spirooxindole epoxides undergo smooth rearrangement either under photosensitization conditions or under Lewis acid catalysis to give different products. The photosensitized rearrangement of spirooxindole epoxides leads to 3‐acyl‐2‐indolones, such as spiro[cycloalkane‐1,3′‐indolin]‐2,2′‐diones, by cleavage of the C α –O bond followed by alkyl migration. The SnCl 4 ‐catalyzed rearrangement of spirooxindole epoxides gives 4,4‐dialkylquinolin‐2,3‐diones, such as spiro[cycloalkane‐1,4′‐quinolin]‐2′,3′‐diones, by cleavage of the C β –O bond followed by aryl migration.