SYNTHESIS OF SUBSTITUTED OXINDOLES BY CHLOROPEROXIDASE CATALYZED OXIDATION OF INDOLES

Chloroperoxidase catalyzed oxidation of substituted indoles yields the corresponding oxindoles in virtually quantitative yield. These includ e 5-chloro-oxindole, a precursor for the anti-inflammatory agent Tenid ap, which was obtained in 95% yield. The reactivity of the substituted indoles depends on the nature and the position of the substituent. Bo th electronic and steric effects of substituents appear to be importan t. All of the oxygen in the product is derived from hydrogen peroxide. A mechanism is proposed for the hydroxylation which is consistent wit h these observations.