Chemistry of bacterial endotoxins. Part 3. Reactions of oxazolines derived from 1,3,4,6-tetra-O-acetyl-2-[(3R)-3-hydroxytetradecanamido]-β-D-glucopyranose

Abstract

In acidic medium the oxazoline derived from 2-[(3RS)-3-acetoxytetradecanamido]-1,3,4,6-tetra-O-acetyl-2-deoxy-β-D-glucopyranose readily eliminates elements of acetic acid: it is transformed into an oxazoline that carries an olefinic substituent having the E configuration; this compound, when treated with an alcohol, yields the corresponding β-D-glucosaminide. No elimination takes place with the analogous 3-hydroxy-or 3-benzyloxy-tetradecanamidoglucosamine derivatives. (3R)-3-Benzyloxy-tetradecanoic acid was obtained in 60%yield upon treatment of methyl (3R)-3-hydroxytetradecanoate in benzene with benzyl bromide, silver oxide, and anhydrous calcium sulphate, followed by saponification. Under similar conditions 3,4,6-tri-O-acetyl-1,2-dideoxy-4′,5′-dihydro-2-[(2R)-2-hydroxytridecyl]-α-D-glucopyranoso[2,1-d]oxazole was transformed into the corresponding (2R)-2-benzyloxyoxazoline.