P/O ligand systems: Facile synthesis, structure, and catalytic tests of 2′-phosphanyl-1,1′-bipheny 1-2-ols and 2′-phosphanyl-1,1′-binaphthyl-2-ols

Article abstract of DOI:10.1002/cber.19971301118

A facile synthesis of 2′-phosphanyl-1,1′-biphenyl- and 2′-phosphanyl-l,1′-binaphthyl-2-ols and their silyl ethers has been developed, consisting of electron-transfer-catalyzed ring-opening of dibenzofuran and dinaphthofuran, respectively, subsequent reaction with chlorophosphanes, and work-up with acetic acid or ClSiMe₃. Studies of the molecular and crystal structures reveal the presence of P...H-O bridging bonds in the more basic /BuPhP derivative and a nearly perpendicular arrangement of the aryl planes in the biphenyl derivatives. The barrier to rotation of the aryl planes about the C-C axis was determined by NMR in the case of the P-asymmetric derivative 3d, using the appearance of diastereoisomers by atropisomerism and P-asymmetry. Comparative screening tests of the title compounds, phosphanylphenols and phosphanylnaphthols in homogeneous Rh-catalyzed reactions demonstrate catalytic activity in hydroformylation reactions and superior properties of the biphenyl- and binaphthyl-2-ol derivatives in relation to other P-O ligands. WILEY-VCH Verlag GmbH, 1997.