Menthyloxycarbonyl phosphonium chlorides: new derivatives for determining the enantiomeric excess of chiral tertiary phosphines

The direct alkoxycarbonylation of tertiary phosphines with alkyl chloroformates has been examined and the products characterised by NMR and X-ray crystallographic analysis. The derivatisation of representative chiral tertiary phosphines with enantiopure menthyl chloroformate allows the determination of the enantiomeric excess of scalemic mixtures by 31P NMR spectroscopic analysis.