Indium Catalyzed Sequential Regioselective Remote C−H Indolylation and Rearrangement Reaction of Peroxyoxindole

Abstract

Indium-catalyzed sequential remote C−H functionalization (C-6 position) and C3-indolylation of peroxyoxindole using indole is described for the synthesis of terindolinone derivatives. Whereas, N-substituted 3-phenyl peroxyoxindole derivatives undergoes consecutive skeletal rearrangement to generate transient carbocation, which has been trapped with indole nucleophile to generate 2-(1H-indol-3-yl)-4-alkyl-benzo[b][1,4]oxazin-3(4H)-one derivatives. In contrast with Indium (III) Chloride, FeCl3 ⋅ 6H2O facilitates oxidative cleavage of the peroxyoxindole (Hock cleavage) and further reaction with indole to afford biologically important trisindoline derivatives. A plausible mechanism has been proposed for these reactions with experimental evidences.