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 catalysts for asymmetric hydrogenation of various alkenes. Enantioselectivities up to 95−98% have been observed in some cases. Enantioselectivities are modest in allylic substitution catalyzed by the corresponding palladium complexes.