Transition-metal-catalyzed C–H functionalization of pyrazoles

This review describes recent advances in transition-metal-catalyzed C–H functionalization reactions of pyrazoles to form new C–C and C–heteroatom bonds on the pyrazole ring. In contrast to traditional cross-coupling reactions that require pre-functionalized pyrazoles, direct C–H functionalization reactions provide access to a wide range of functionalized pyrazoles in a single step. Various strategies are presented and the efficiency and regioselectivity are described with respect to the types of functional groups that are installed.