Synthesis and some reactions of (±)-aleuritic acid

Abstract

Condensation of the dilithio-derivative of oct-7-yn-1-ol with 8-bromo-octanoic acid gives 16-hydroxyhexadec-9-ynoic acid which is semihydrogenated to cis-16-hydroxyhexadec-9-enoic acid. Cis-and trans-hydroxylation processes then give erythro- and threo-9,10,16-trihydroxyhexadecanoic acids respectively. Infrared spectra and chromatography show that aleuritic acid is the threo-isomer but it is suggested that natural aleuritic acid is optically active.

The threo-configuration of aleuritic acid is also demonstrated (a) by conversion into trans-16-hydroxyhexadec-9-enoic acid with phosphonium iodide, (b) by transformation into erythro-9,10,16-tribromohexadecanoic acid and thence into trans-hexadec-9-enoic acid (palmitelaidic), and (c) by conversion through the bromo-acetoxy-acid into 16-hydroxy-trans-9,10-epoxyhexadecanoic acid. Erythro-9,10,16-trihydroxyhexadecanoic acid and 16-hydroxy-9,10-dioxohexadecanoic acid are prepared from aleuritic acid.