Synthesis of some ferrocene-based 1,3-bis(phosphanes) with planar chirality as the sole source of chirality

Several enantiopure diphosphanes 21 were synthesized in three steps from a common precursor 19. The cationic rhodium complexes 22 were screened as cat alysts for asymmetric hydrogenation of various alkenes. Enantioselectivitie s up to 95-98% have been observed in some cases. Enantioselectivities are m odest in allylic substitution catalyzed by the corresponding palladium comp lexes.