Diastereoselective Synthesis of P-Stereogenic Secondary Phosphine Oxides (SPOs) Bearing a Chiral Substituent by Ring Opening of (+)-Limonene Oxide with Primary Phosphido Nucleophiles.

Kinetic separation of the commercially available /-(+)-limonene oxide mixture by ring opening with primary phosphido nucleophiles LiPHR (R = ferrocenyl, Ph, Cy, -Bu, Mes* (Mes* = 2,4,6-(-Bu)CH)), followed by treatment with aqueous NHCl and HO, gave unreacted -(+)-limonene oxide and diastereoenriched mixtures of the secondary phosphine oxides (SPOs) PHR(-(+)-Lim-OH)(O), which could be separated by chromatography and/or recrystallization. This one-pot synthesis uses a cheap chiral material and commercially available primary phosphines to control the configuration of the new P-stereogenic SPOs, which are potentially useful as ligands for metal complexes in asymmetric catalysis.