α,α-Dichlorination of Oxindole Derivatives Using (Dichloroiodo)-benzene

Use of the hypervalent aryl-lambda(3)-iodane reagent iodobenzene dichloride (PhICl2) in the a-carbonyl dichlorination of 2-oxindoles is reported. Treating a series of diversely substituted 3-diazo-2-oxindoles with PhICl2 in the presence of pyridine, a Lewis base iodane-activator, results in 3,3-dichloro-2-oxindole products. Activation of PhICl2 is key to the chlorination proceeding rapidly, chemoselectively and in good to excellent yields. This investigation represents a novel approach to the synthesis of 3,3-disubstituted-2-oxindoles, and illustrates the compatibility of the ligand-transfer reaction with the 2-oxindole scaffold.