2026 MBLA Winner: Harunobu Mitsunuma

Catalytic functionalization of sp³ C–H bonds is an attractive strategy for the rapid synthesis of sp³-rich molecules with high atom and step economy. However, conventional transition-metal-catalyzed C–H activation often requires harsh conditions or directing groups, limiting its application to complex, multifunctional molecules. Although hydrogen atom transfer (HAT) catalysis enables cleavage of strong sp³ C–H bonds under mild conditions, controlling the reactivity and selectivity of the resulting carbon radicals remains challenging.

To address this issue, we developed a cooperative catalytic system consisting of a HAT catalyst for C–H activation, a transition-metal catalyst for selective bond formation, and a photoredox catalyst that electronically couples the two catalytic cycles. This ternary catalyst system strategy enables mild and selective sp³ C–H functionalization with broad functional-group tolerance and provides access to structurally complex molecules from simple hydrocarbon feedstocks. In this presentation, I will introduce new transformations enabled by these cooperative catalytic systems and discuss their potential applications in the synthesis of pharmaceutically relevant molecules.