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-(4 R,5 R)-bis(1 R,2 S,5 R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane is a practical reagent for reliably determining enantiomeric purity of chiral alcohols via (31)P NMR spectroscopy. The compound is available as a crystalline solid on a 20 g scale from PCl 3 and bis(1 R,2 S,5 R)-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 (31)P NMR signals of diastereomeric 2-alkoxy-1,3,2-dioxophospholanes were dispersed by approximately 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%.