SUPRAPhos ligands for the regioselective rhodium catalyzed hydroformylation of styrene forming the linear aldehyde

We report SUPRAphos-based rhodium catalysts that are unusually regioselective in the hydroformylation of styrene at low temperatures (40 degrees C) producing mainly the linear aldehyde (72%). This ligand-specific phenomenon is observed for two rhodium catalysts with heterobidentate phosphine-phosphoramidite ligands. We propose that the high selectivity for the linear product is caused by enhanced beta-hydride elimination, due to specific substrate-ligand interactions, most likely pi-pi interactions.