Organocatalytic Para-Selective Amination of Phenols with Iminoquinone Monoacetals

A highly selective para C–H amination of unprotected phenols with iminoquinone acetals was realized, giving the functional phenols in good to excellent yields. Overall, this transformation is operationally simple, proceeds with readily available phenols, and has wide substrate scope and low catalyst loading. The biarylamine product is stochastically formed via [5,5]-sigmatropic rearrangement of a mixed acetal species which is generated in situ under the reaction conditions.