Strong π‑Acceptor Ligands in Rhodium-Catalyzed Hydroformylation of Ethene and 1‑Octene: Operando Catalysis

Strong π-acceptor N-pyrrolylphosphoramidite and pyrrolylphosphine mono- and bidentante ligands were applied in ethene hydroformylation using a stoichiometric gas mixture CO/H₂/ethene 1:1:1. Very fast reactions (TOF up to 29.5 × 10³ mol mol^–1 h^–1, 13-fold faster than triphenylphosphine) and excellent selectivities were obtained. The pyrrolylphosphine derivatives of SPANphos and Xantphos, pySPAN and pyXANT, were used in 1-octene hydroformylation. The electronic character of these ligands improved both activities and regioselectivities compared with the phenyl-substituted ligands. HPNMR and HPIR showed that both pySPAN and pyXANT favor the formation of bisequatorial [RhH­(CO)₂(ligand)] complexes under catalytic conditions.