Chiral Mixed Secondary Phosphine‐Oxide–Phosphines: High‐Performing and Easily Accessible Ligands for Asymmetric Hydrogenation

P&O : Combining secondary phosphine oxides (SPOs) with phosphines leads to highly effective chiral bidentate ligands for transition‐metal‐based catalysts. JoSPOphos and TerSPOphos are readily accessible from inexpensive starting materials. The steric and electronic properties of these modular ligands can be easily tuned. In the asymmetric hydrogenation of functionalized alkenes, their rhodium complexes reacted to give enantioselectivities of up to 99 % ee and turnover frequencies of up to 20 000 h −1 .