Stereospecific synthesis of P-epimeric (Rp1, Rp2)-bis-[O-l-menthylphenylphosphonothionyl] diselenide. A new variant of the stereoselective Staudinger reaction

An efficient procedure is described that leads to pure (S_P)- O -l-menthylphenylthiophosphinate. The absolute configuration of this diastereomer was assigned by chemical correlation and confirmed by X-ray crystallography. The reaction of the isomer with phenyl azide, leading to amidate, is a new variant of the stereoselective Staudinger reaction. Addition of elemental selenium to the (S_P)-thiophosphinate led to diastereomeric O-l-menthylphenylselenophosphonothioic acid, which was finally oxidized to the diastereomeric (R_P1,R_P2)-bis-O-l-menthylphenylphosphonothionyl] diselenide. The diselenide structure was unambiguously confirmed by ³¹P NMR spectroscopy.