FMPhos: Expanding the Catalytic Capacity of Small-Bite-Angle Bisphosphine Ligands in Regioselective Alkene Hydrofunctionalizations

In contrast to the plethora of large-bite-angle bisphosphine ligands available to transition-metal catalysis, the development of small-bite-angle bisphosphine ligands has suffered from the limited structural variations accessible on their single-atom-containing backbones. Herein, we report the design and applications of a discrete very small bite-angle bisphosphine ligand, namely, FMPhos. Featuring a fluorene–methylene unit appended on the single-carbon linker, the ligand harbors an unusually rigid backbone that presumably stabilizes its complexation with transition metals during catalysis. Compared with the known dppm ligand, it exhibited superior reactivity and regioselectivity in a number of alkene hydrofunctionalization reactions, catalyzed by iridium and rhodium.