P-Stereogenic Phosphine Compounds

Gilheany et al. have reported the synthesis of P-stereogenic phosphine compounds using the asymmetric Appel reaction. According to their results, the reaction of racemic phosphines with hexachloroacetone as a chlorine source and (-)-menthol as a chiral alcohol gives diastereometric alkoxyphosphonium salts under Appel reaction conditions. Subsequent reduction of the alkoxyphosphonium salts with LiAlH₄ or NaBH₄ gives the corresponding P-stereogenic phosphines or phosphine boranes, respectively. The obtained P-stereogenic phosphine compounds can be used as ligands for transition metal complex catalysts.