Guanidinium Hypoiodite-Catalyzed Intramolecular Oxidative Coupling Reaction of Oxindoles with β-Dicarbonyls.

Spiro[indoline-3,4'-piperidine] is a fundamental motif present in various biologically active compounds. Here, we report an intramolecular oxidative coupling reaction of oxindoles with β-dicarbonyls in the presence of a guanidinium hypoiodite catalyst, providing spiro-coupling products in moderate to excellent yields. Furthermore, a chiral hypoiodite catalyst derived from the chiral guanidinium organocatalyst is effective for the challenging asymmetric carbon-carbon bond-forming reaction, affording optically active spiro[indoline-3,4'-piperidines].