Desymmetrization by direct cross-metathesis producing hitherto unreachable P-stereogenic phosphine oxides

Desymmetrization of prochiral di- and trialkenyl phosphine oxides by cross-metathesis with various olefinic partners allowed direct access to novel racemic P-stereogenic products featuring two or three different alkenyl groups. The excellent control of product selectivity and E/Z selectivity allowed the preparation of desymmetrized products in good yields from readily available precursors. These are the first examples of desymmetrization of prochiral substrates by direct cross-metathesis.