Synthesis and Application of Chiral Phospholane Ligands Bearing a Sterically and Electrically Adjustable Moiety

A series of C 1 ‐symmetric phosphine‐phospholane ligands, 1‐(disubstituted phosphino)‐2‐(phospholano)benzenes ( 5 ), which are called UCAPs, with an achiral phosphino group and a chiral phospholane which can be sterically and electrically adjustable, has been designed and synthesized. In the asymmetric hydrogenation of ( Z )‐ N ‐benzoyl‐1‐phenylpropenamine ( 3 ), the stereorecognition abilities of the 5d−e –Rh catalysts which have a bulkier aryl substituent on the achiral phosphorus are superior to that observed with the DuPHOS‐Rh catalyst. The effects of varying substituents on the achiral phosphorus atom are discussed.