Two precatalysts for application in asymmetric homogeneous hydrogenation

The title compounds, [(1R,1′R,2R,2′R)‐2,2′‐bis(diphenylphosphanyl)‐1,1′‐dicyclopentane](η⁴‐norbornadiene)rhodium(I) tetrafluoridoborate, [Rh(C₃₄H₃₆P₂)(C₇H₈)]BF₄, (I), and [(1R,1′R,2R,2′R)‐2,2′‐bis(diphenylphosphanyl)‐1,1′‐dicyclopentane][η⁴‐(Z,Z)‐cycloocta‐1,5‐diene]rhodium(I) tetrafluoridoborate dichloromethane monosolvate, [Rh(C₃₄H₃₆P₂)(C₈H₁₂)]BF₄·CH₂Cl₂, (II), are applied as precatalysts in asymmetric homogeneous hydrogenation, e.g. in the reduction of dehydroamino acids, affording excellent enantiomeric excesses [Zhu, Cao, Jiang & Zhang (1997). J. Am. Chem. Soc. 119 , 1799–1800].