Synthesis of a unique trisaccharide having an acetal linkage between open-chain and cyclic sugar found in the cell wall of Proteus

The first stereoselective synthesis of a unique trisaccharide containing an open-chain glycosyl cyclic acetal moiety found in the cell wall of Proteus has been successfully achieved. Most of the intermediate steps are high yielding and highly reproducible. The acetal linkage of the open-chain d-galactosamine moiety with an (S)-configuration was formed exclusively.

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4-Methoxyphenyl 2-azido-3-O-benzoyl-2-deoxy-α-d-galactopyranosideC20H21N3O7[α]D25=+205 (c 1.0, CH3CN)Source of chirality: d-galactalAbsolute configuration: (1S,2R,3S,4R,5R)

2-Azido-3,4,6-tri-O-benzyl-2-deoxy-d-galactitolC27H31N3O5[α]D25=-245 (c 1.0, CHCl3)Source of chirality: d-galactalAbsolute configuration: (2S,3R,4S,5R)

2-Azido-5-O-[(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)]-3,4,6-tri-O-benzyl-1-O-tert-butyldimethylsilyl-2-deoxy-d-galactitolC47H63N3O14Si[α]D25=-12 (c 1.0, CHCl3)Source of chirality: d-glucose and d-galactalAbsolute configuration: (1R,2R,3S,4R,5S,2′R,3′R,4′R,5′S)

4-Methoxyphenyl 2-azido-3-O-benzoyl-2-deoxy-4,6-O-(1S)-[5-O-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-2-azido-3,4,6-tri-O-benzyl-2-deoxy]-d-galactosylidene-α-d-galactopyranosideC61H66N6O20[α]D25=+96 (c 1.0, CHCl3)Source of chirality: d-glucose and d-galactalAbsolute configuration: (1R,2R,3S,4R,5S,1′S,2′R,3′R,4′R,5′R,1″S,2″R,3″S,4″R,5″R)

4-Methoxyphenyl 2-acetamido-2-deoxy-4,6-O-(1S)-[5-O-(β-d-glucopyranosyl)-2-acetamido-2-deoxy]-d-galactosylidene-α-d-galactopyranosideC29H44N2O17[α]D25=+91 (c 1.0, H2O)Source of chirality: d-glucose and d-galactalAbsolute configuration: (1R,2R,3S,4R,5S,1′S,2′R,3′R,4′R,5′R,1″S,2″R,3″S,4″R,5″R)