The First Examples of Enantiomerically Pure Diphosphane Dioxides—( R P , R P )‐ and ( S P , S P )‐1,2‐Di‐ ter ‐butyl‐1,2‐diphenyldiphosphane 1,2‐Dioxides, and ( R P )‐ and ( S P )‐1‐ tert ‐Butyl‐1,2,2‐triphenyldiphosphane 1,2‐Dioxides

Whereas oxidative dimerization of each of the lithiated reagents ( R P )‐ and ( S P )‐ tert ‐butylphenylphosphane oxides 1 Li and 2 Li by means of oxygen in THF at low temperature led cleanly to meso ‐1,2‐di‐ tert ‐butyl‐1,2‐diphenyldiphosphane dioxide ( 3 ), the respective nucleophilic substitution reactions of 1 Li and 2 Li with the ( R P )‐ and ( S P )‐ tert ‐butylphenylphosphinic bromides ( 4 and 6 ) in THF under argon led to the corresponding ( S P , S P )‐ and ( R P , R P )‐12‐di‐ tert ‐butyl‐1,2‐diphenyldiphosphane dioxides ( 5 and 7 ) in good yields, together with the meso ‐diphosphane dioxide 3. The structures of 3 and 5 were established by X‐ray crystallography. Similarly, the reaction of lithiated ( R P )‐phosphane oxide 1 Li with diphenylphosphinic bromide ( 8 ) or of achiral lithiated diphenylphosphane oxide 10 Li with ( R P )‐ tert ‐butylphenylphosphinic bromide ( 4 ) provided ( S P )‐ tert ‐butyltriphenyldiphosphane dioxide ( 9 ).