Expedient synthesis of a tetrasaccharide and a pentasaccharide corresponding to the cell wall O-antigen of Escherichia coli O77 and Escherichia coli O17

A concise chemical synthetic strategy has been developed for the synthesis of a tetrasaccharide and a pentasaccharide corresponding to the O-antigen of Escherichia coli O77 and E. coli O17 strains, respectively using [2+2] and [3+2] block glycosylation approaches from suitably functionalized common monosaccharide intermediates. All of the intermediate steps are high yielding while the glycosylation steps are highly stereoselective. A number of recently developed methodologies have been used in the synthesis.

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2-(Benzyloxycarbonylamino)ethyl 3-O-benzyl-4,6-O-benzylidene-β-d-mannopyranosideC30H33NO8[α]D25=-32 (c 1.2, CHCl3)Source of chirality: d-mannose

p-Methoxyphenyl 2-azido-3,4-di-O-benzoyl-2-deoxy-β-d-glucopyranosideC27H25N3O8[α]D25=+114 (c 1.2, CHCl3)Source of chirality: d-glucosamine

2-(Benzyloxycarbonylamino)ethyl 3-O-benzyl-4,6-O-benzylidene-β-d-glucopyranosideC30H33NO8[α]D25=-27 (c 1.2, CHCl3)Source of chirality: d-glucose

2-(Benzyloxycarbonylamino)ethyl (2-O-acetyl-3,4,6-tri-O-benzyl-α-d-mannopyranosyl)-(1→2)-3-O-benzyl-4,6-O-benzylidene-β-d-mannopyranosideC59H63NO14[α]D25=-5 (c 1.2, CHCl3)Source of chirality: d-mannose

2-(Benzyloxycarbonylamino)ethyl (3,4,6-tri-O-benzyl-α-d-mannopyranosyl)-(1→2)-3-O-benzyl-4,6-O-benzylidene-β-d-mannopyranosideC57H61NO13[α]D25=-3 (c 1.2, CHCl3)Source of chirality: d-mannose

Ethyl (3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-d-glucopyranosyl)-(1→6)-2,3,4-tri-O-benzoyl-1-thio-α-d-mannopyranosideC41H43N3O15S[α]D25=+54 (c 1.2, CHCl3)Source of chirality: d-glucosamine, d-mannose

2-(Benzyloxycarbonylamino)ethyl (3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-d-glucopyranosyl)-(1→6)-(2,3,4-tri-O-benzoyl-α-d-mannopyranosyl)-(1→2)-(3,4,6-tri-O-benzyl-α-d-mannopyranosyl)-(1→2)-3-O-benzyl-4,6-O-benzylidene-β-d-mannopyranosideC96H98N4O28[α]D25=+1 (c 1.2, CHCl3)Source of chirality: d-glucosamine, d-mannose

p-Methoxyphenyl (4,6-di-O-acetyl-2,3-di-O-benzyl-α-d-glucopyranosyl)-(1→6)-2-azido-3,4-di-O-benzoyl-2-deoxy-α-d-glucopyranosideC51H51N3O15[α]D25=+51 (c 1.2, CHCl3)Source of chirality: d-glucose, d-glucosamine

Ethyl (4,6-di-O-acetyl-2,3-di-O-benzyl-α-d-glucopyranosyl)-(1→6)-(2-azido-3,4-di-O-benzoyl-2-deoxy-α-d-glucopyranosyl)-(1→6)-2,3,4-tri-O-benzoyl-1-thio-α-d-mannopyranosideC73H71N3O21S[α]D25=+48 (c 1.2, CHCl3)Source of chirality: d-glucose, d-glucosamine, d-mannose

2-(Benzyloxycarbonylamino)ethyl (4,6-di-O-acetyl-2,3-di-O-benzyl-α-d-glucopyranosyl)-(1→6)-(2-azido-3,4-di-O-benzoyl-2-deoxy-α-d-glucopyranosyl)-(1→6)-(2,3,4-tri-O-benzoyl-α-d-mannopyranosyl)-(1→2)-(3,4,6-tri-O-benzyl-α-d-mannopyranosyl)-(1→2)-3-O-benzyl-4,6-O-benzylidene-β-d-mannopyranosideC128H126N4O34[α]D25=+15 (c 1.2, CHCl3)Source of chirality: d-glucose, d-glucosamine, d-mannose

2-Aminoethyl (2-acetamido-2-deoxy-α-d-glucopyranosyl)-(1→6)-(α-d-mannopyranosyl)-(1→2)-(α-d-mannopyranosyl)-(1→2)-β-d-mannopyranosideC28H50N2O21[α]D25=+12 (c 1.2, H2O)Source of chirality: d-glucosamine, d-mannose

2-Aminoethyl (α-d-glucopyranosyl)-(1→6)-(2-acetamido-2-deoxy-α-d-glucopyranosyl)-(1→6)-(α-d-mannopyranosyl)-(1→2)-(α-d-mannopyranosyl)-(1→2)-β-d-mannopyranosideC34H60N2O26[α]D25=+10 (c 1.2, H2O)Source of chirality: d-glucose, d-glucosamine, d-mannose