2-Chloro-(4R,5R)-bis[(1R,2S,5R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane: A Practical Chiral Pool-Derived Reagent for Determining Enantiomeric Purity of Alcohols

2-Chloro-(4R,5R)-bis[(1R,2S,5R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane is a practical reagent for reliably determining enantiomeric purity of chiral alcohols via 31P NMR spectroscopy. The compound is available as a crystalline solid on a 20 g scale from PCl3 and bis[(1R,2S,5R)-menth-1-yl] tartrate. It is comparatively inert toward spontaneous hydrolysis under conventional laboratory conditions but undergoes quantitative substitution of alkoxide for chloride if treated with a chiral alcohol. Nonequivalent 31P NMR signals of diastereomeric 2-alkoxy-1,3,2-dioxophospholanes were dispersed by ∼1.4–0.1 ppm. The associated integral ratios reflected enantiomeric purities of preweighted samples of (R)- and (S)-1-phenylethanol, (+)- and (−)-menthol, and a set of primary, secondary, and tertiary alcohols with a precision of ±0.4–1.0%.