Synergistic Ligand Effect in Rhodium(I)-Catalyzed Regio-Controlled Propene Hydroformylation

Propene (propylene) is the most important hydroformylation reactant on an industrial scale, representing approximately 75% of the global consumption of oxo chemicals. Both n -butanal and isobutanal, the products of propene hydroformylation, are valuable precursors, and thus controlling the regioselectivity in this reaction is of academic and industrial interest. In the Rh-catalyzed propene hydroformylation, regioselective reactions have been achieved by a modifying ligand. Although highly normal selective ( n /iso > 50) ligands have been reported, iso-selective ( n /iso < 1) ligands are limited and more importantly show a significantly reduced activity (TOF < 1000 h –1 ). Herein, we report a highly reactive and regio-controlled ( n /iso = 1) propene hydroformylation enabled by Rh catalysis with a sterically bulky π-acceptor phosphorus (bicyclic bridgehead phosphoramidite (briphos)) ligand. In addition, a briphos/PPh 3 ligand combination results in a mixed-ligand Rh(I) complex that shows regioselectivity ( n /iso = 1) and high reactivity (TOF = 22,700 h –1 ) and stability during propene hydroformylation.