Nonepimerizing Alkylation of H–P Species to Stereospecifically Generate P‑Stereogenic Phosphine Oxides: A Shortcut to Bidentate Tertiary Phosphine Ligands

The secondary RP-(−)-menthyl alkylphosphine oxide was confirmed as configurationally stable toward base and was used in base-promoted alkylation, stereospecifically affording P-retained bis or functional tertiary phosphine oxides in excellent yields. The alkylated products were deoxygenated using oxalyl chloride followed by ZnCl2–NaBH4 to form P-inversed bidentate phosphine boranes in high stereoselectivities.