Supramolecular Control of Selectivity in Hydroformylation of Vinyl Arenes: Easy Access to Valuable β‐Aldehyde Intermediates

Go against the flow! A rationally designed regioselective hydroformylation catalyst, [Rh/L], in which noncovalent ligand–substrate interactions allow the unprecedented reversal of selectivity from the typical α-aldehyde to the otherwise unfavored product β-aldehyde, is reported. This catalytic system opens up novel and sustainable synthetic pathways to important intermediates for the fine-chemicals industry.