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

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