P O LIGAND SYSTEMS - FACILE SYNTHESIS, STRUCTURE, AND CATALYTIC TESTSOF 2'-PHOSPHANYL-1,1'-BIPHENYL-2-OLS AND 2'-PHOSPHANYL-1,1'-BINAPHTHYL-2-OLS/

A facile synthesis of 2'-phosphanyl-1,1'-biphenyl- and 2'-phosphanyl-1 ,1'-binaphthyl-2-ols and their silyl ethers has been developed, consis ting of electron-transfer-catalyzed ring-opening of dibenzofuran and d inaphthofuran, respectively, subsequent reaction with chlorophosphanes , and work-up with acetic acid or ClSiMe3. Studies of the molecular an d crystal structures reveal the presence of P ... H-O bridging bonds i n the more basic tBuPhP derivative and a nearly perpendicular arrangem ent of the aryl planes in the biphenyl derivatives. The barrier to rot ation of the aryl planes about the C-C axis was determined by NMR in t he case of the P-asymmetric derivative 3d, using the appearance of dia stereoisomers by atropisomerism and P-asymmetry. Comparative screening tests of the title compounds, phosphanylphenols and phosphanylnaphtho ls in homogeneous Rh-catalyzed reactions demonstrate catalytic activit y in hydroformylation reactions and superior properties of the bipheny l- and binaphthgl-2-ol derivatives in relation to other P-O ligands.