Synthesis and behaviour under acidic conditions of 2-deoxy-D-arabino-hexopyranose and 3-deoxy-2-ketoaldonic acids bearing O-phosphono or O-glucosyl substituents at position β to the carbonyl function

Abstract

Methyl 4-O-phosphono-and 4 -0 -(~-D-glucopyranosyl)-3-deoxy-~-D-erythro-2-hexulopyranosidonic acids, and 3-O-phosphono-, and 3-0-(~-D-glucopyranosyl)-2-deoxy-a-D-~f~~~~o-hexopyranoses have been synthesised and their behaviour in acidic media examined. At 100 "C, release of inorganic phosphate from the 4-O-phosphonohexulopyranosidonic acid is faster at pH 3-6 than at pH 0-1 and occurs through an elimination initiated by proton transfer. Phosphate release from the 3-O-phosphono-2-deoxy-hexopyranose occurs by a similar mechanism, but is much slower. Treatment at 100 "C with acetic acid of pH 3.4 causes release of glucosefrom the 4-O-glucosylated-3-deoxy-hexulopyranosidonic acid but not from the 3-O-glucosylated-2-deoxy-hexopyranose.STUDIES in this laboratory have shown that the Bordetellapertussis endotoxin is made up of two lipopolysaccharides, LPSl and LPS2,l in which lipid and polysaccharide regions are linked through the glycosidic bond of a 3deoxy-~-manno-2-octulopyranosonic acid (KDO) . While LPSl was rapidly hydrolysed by 0 . 0 1 ~ acetic acid (pH

Structural characterization of the cell surface lipooligosaccharides from a nontypable strain of Haemophilus influenzae

“…To rationalize the formation of diastereomeric anhydro-KDO structures in the NTHI 2019 hexasaccharide, a mechanism for their generation was sought. Elimination of a phosphate moiety from C-4 of KDO has been reported to occur during mild acid hydrolysis of intact LOS (Danan et al, 1982;Caroff et al, 1987). Loss of phosphate from the 4-position of KDO proceeds readily under these conditions because the C-4 substituent is ß to the C-2 (anomeric) carbonyl carbon and can therefore undergo ^-elimination.…”

Phosphorylated sugars. Part 27. Synthesis and reactions, in acid medium, of 5-O-substituted methyl 3-deoxy-α-D-manno-oct-2-ulopyranosidonic acid 4-phosphates

“…C2,H4,08Si requires C, 59.5; H, 8.3%); [XI,, +57.8" (c 1.2, CHCI,); G,(CDCl,; 200 MHz) 0.10 and 0.12 (2 x 3 H, 2 s, Me2Si), 0.95 (9 H, s, Me3CSi), 1.92 (1 H, =t, J3e,3a 12, J3a,4 11.5, 3-Ha), 2.13 (1 H, dd, J3e,4 5, 3-He), 3.24 and 3.32 (2 x 3 H, 2 s, 6-H), 3.80 (3 H, s, CO,Me), 4.01 ( 1 H, m, 5-H), 4.07 (1 H, m, 4-H),4.24(1H,dt,J7,, x J7,,, z 2.5,7-H),4.73and4.94(2H,2 d, OCH,Ph) and 7.36 ( 5 H, m, Ph). 2 X OMe), 3.65 (2 H, m, 8-H2), 3.75 (1 H, Zd, J 6 . 5 2 1, J 6 .…”

“…Under these conditions KDO units that are not substituted by a glycose unit of the polysaccharide chain are released as monosaccharides, unless they carry a phosphate substituent in position 4. 3 Phosphorylated KDO units have been isolated4 from, or detected in, a number of endotoxin preparations. KDO derivatives phosphorylated in position 4 behave differently from the other positional isomers inasmuch as, at 100 O C , they eliminate their phosphate group with extreme facility in acidic, neutral or alkaline envir~nrnent.~ The olefinic acid, presumably formed as the first product, eventually leads to a derivative of furoic acid (Scheme 1 ) by ring-closure involving (C-2)-(0-5)-(C-5).…”

Crystal Structure of a Complex of Surfactant Protein D (SP-D) and Haemophilus influenzae Lipopolysaccharide Reveals Shielding of Core Structures in SP-D-Resistant Strains

“…The best fit to the electron density map (Fig. 3b) is the proposed (35) 5-membered anhydro-Kdo ring arising from ␤-elimination of phosphate or pyrophosphate from KdoO4, accompanied by pyranose ring opening (35,37) and subsequent 4,7 ring closure to form a furanoid derivative with a chiral center at C4 carrying an extended substitution (Fig. 4).…”