A METHOD FOR DETERMINATION OF THE ABSOLUTE-CONFIGURATION OF CHIRAL GLYCEROL RESIDUES IN NATURAL-PRODUCTS USING TEMPO OXIDATION AND CHARACTERIZATION OF THE GLYCERIC ACIDS FORMED

A method has been developed for determination of the absolute configur ation of glycerol residues in natural products. It is required that th e glycerol moiety contain a primary nonsubstituted hydroxymethyl group or that such a group can be obtained by modification without racemiza tion. The method employs TEMPO oxidation of the primary hydroxyl group , hydrolysis, butanolysis with chiral 2-butanol, and acetylation. The acetylated (+)-2-butyl esters of the glyceric acid formed by oxidation are analyzed by gas-liquid chromatography. The esterification can als o be performed with other chiral alcohols, e.g., (-)-2-octanol. The me thod is general and applicable to both primary and secondary substitut ed glycerols. It has recently been used for determination of the chira l glycerol-1-phosphate residue of the Escherichia coli O28 O-antigen, and now we report the absolute configurations of the glycerol moieties in Streptococcus pneumoniae type 18A and Streptococcus agalactaie typ e III. All studied glycerol residues were found to have the D-configur ation. (C) 1996 Academic Press, Inc.