THE FIRST EXAMPLES OF ENANTIOMERICALLY PURE DIPHOSPHANE DIOXIDES R-P,R-P)-1,2-DI-TERT-BUTYL-1,2-DIPHENYLDIPHOSPHANE AND S-P,S-P)-1,2-DI-TERT-BUTYL-1,2-DIPHENYLDIPHOSPHANE 1,2-DIOXIDES, AND (R-P)-1-TERT-BUTYL-1,2,2-TRIPHENYLDIPHOSPHANE 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-buty l-1,2-diphenyldiphosphane dioxide (3), the respective nucleophilic sub stitution reactions of 1 Li and 2 Li with the (R-p)- and (S-p)-tert-bu tylphenylphosphinic bromides (4 and 6) in THF under argon led to the c orresponding (S-p,S-p)- and R-p,R-p)-1,2-di-tert-butyl-1,2-diphenyldip hosphane dioxides (5 and 7) in good yields, together with the meso-dip hosphane dioxide 3. The structures of 3 and 5 were established by X-ra y crystallography. Similarly, the reaction of lithiated (R-p)-phosphan e oxide 1 Li with diphenylphosphinic bromide (8) or of achiral lithiat ed diphenylphosphane oxide 10 Li with (R-p)-tert-butylphenylphosphinic bromide (4) provided (S-p)-tert-butyltriphenyldiphosphane dioxide (9) .