“…Most importantly, the hydrogenation rates for MAC and AS were much higher with 1,2‐bis[(aryl)(phenyl)phosphino]ethanes [wherein aryl = o ‐RO‐Ph,6a,15 2,3‐(MeO) 2 ‐Ph, 2,3,4,5‐(MeO) 4 ‐Ph20] than with L1 – L4 , demonstrating a clear beneficial impact on the hydrogenation kinetics of the flexible CH 2 CH 2 backbone in such P , P , P′ , P′ ‐tetraaryl PCCP‐type bridged structure. However, the P ‐α‐Nap‐substituted analogue21 displayed much lower hydrogenation rates for MAC and AS compared with DiPAMP15 or 1,2‐bis[(methyl)(phenyl)phosphino]ethane17a (having comparable rates), and 1,2‐bis{[2,3‐(MeO) 2 ‐Ph](phenyl)phosphino}ethane,20 but gave the same level of enantioselectivities as with the latter, pointing here also to the unfavorable increase in the overall rigidity of the system.…”