EFFICIENT SYNTHESIS OF (R)-(6,6'-DIFLUOROBIPHENYL-2,2'-DIYL)BIS(DIPHENYLPHOSPHINE) AND (S)-(6,6'-DIFLUOROBIPHENYL-2,2'-DIYL)BIS(DIPHENYLPHOSPHINE) - ELECTRON-POOR BIPHENYL-TYPE LIGANDS FOR TRANSITION-METAL CATALYSTS

Racemic title compound (RS)-5 is synthesized (Scheme 1, 100g scale) in four simple steps (49% overall yield) from meta-fluorobromobenzene 1. (RS)-5 is efficiently resolved (Scheme 2) utilizing commercial (S)-(+)-dipalladium complex 9 to give homochiral (S)-(+)-5 and (R)-(-)-5 in 75 and 95% of theoretical yield, respectively. Enantiomerically pure diphosphines (S)-5 and (R)-5 do not racemize in organic solutions, even when heated to 207 degrees C. Homochiral palladium(ll) dichloride complexes (-)-11 and (+)-11 are prepared in quantitative yield. Insitu rhodium(I)-complex of homochiral 5 is ail efficient catalyst for alkene hydroboration by catecholborane and requires high hydrogen pressure to catalyze hydrogenation. Interesting anomalies of the specific rotation are observed for homochiral diphosphines (S)-(+)5 and (R)-(-)-5. The specific rotation [alpha](25)(D) of (S)-(+)-5 measured in similar aromatic hydrocarbons (toluene, o-xylene, mesitylene, tetralin) varies from +114.9 (c 0.99, toluene) to 73.9(c 0.46, tetralin).