(Indol-3-yl)(DMIX)Iodonium Salts: Novel Electrophilic Indole Reagents

A new umpolung approach to the C3–H functionalization of indoles with diverse nucleophiles based on the intermediate formation of I­(III) reagents is described. The 3,5-dimethylisoxazol-4-yl auxiliary allows for selective indole transfer under catalyst-free conditions, which was impossible using previously reported reagents. Combining the mildness of transition-metal-free conditions and the high reactivity of hypervalent iodine reagents, this protocol tolerates various functional groups and provides access to indoles that are difficult to prepare conventionally.