The dimerization of an oxindole in good yield at C-3 to form a benzylic quaternary carbon-carbon bond is described. A radical anion chain mechanism is proposed for the reaction. The dimeric product is transformed into (+/-)-folicanthine by a series of reductions. A crystalline bis-borane complex of (+/-)-folicanthine was obtained, and its molecular structure was determined by X-ray crystallography.
The Reformatsky Reaction in the Isatin Series<sup>1</sup>