Chiral monodentate ligands are important tools for the control of enantioselectivity in catalytic reactions. These compounds are particularly important when transition-metal catalysts lack sufficient coordination sites to bind a bidentate ligand and still retain activity. Along these lines, modular, tunable chiral carbenes [1] and phosphoramidites [2] have found particular prominence in the field of asymmetric catalysis. Aside from these compound classes, however, there is a relative paucity of effective, tunable monodentate chiral ligands that have found widespread utility. In recent studies on the platinum-catalyzed enantioselective diboration of dienes, we achieved limited success when optimizing chiral phosphoramidite and phosphonite ligands for certain substrates. [3,4] Because catalytic diboration benefits from the presence of electron-rich monodentate phosphines, [5] we considered that solutions to problematic substrates might arise from the availability of a readily preparable, tunable, chiral, Lewis basic phosphine ligand. [6] Herein, we describe the synthesis and properties of enantiomerically enriched modular 1,3-oxaphospholanes (termed OxaPhos ligands, Scheme 1). These ligands are readily available from the [*] C.