Mechanistic insights on iodine (III) promoted metal-free dual C–H activation involved in the formation of a spirocyclic bis-oxindole

Abstract

The mechanism of a metal-free, phenyliodine (III) bis(trifluoroacetate) promoted, dual aryl C–H activation of an anilide to a spirocyclic bis-oxindole is examined using density functional theory (M06-2X). The most preferred pathway proceeds through the involvement of a novel iodonium ion intermediate and a pivotal trifluoroacetate counterion. The two sequential aryl C–H activations, assisted by trifluoroacetate as well as the superior leaving group ability of PhI, facilitate the formation of spirocyclic bis-oxindole.