Boron-Mediated Selective C–H Hydroxylation of 1-Phenyl-1H-Pyrazoles

A novel strategy for boron-mediated C–H hydroxylation of 1-phenyl-1H-pyrazoles is presented. The protocol exhibits high efficiency and site exclusivity, offering the corresponding phenols in moderate to excellent yields with wide functional group tolerance under simple and metal-free conditions. Moreover, the hydroxylated products show good derivatization applications. This route provides a convenient and practical way to obtain functionalized 1-phenyl-1H-pyrazoles.