Synthesis of phosphorylated Neisseria meningitidis inner core lipopolysaccharide structures

A phosphoethanolamine-substituted tetrasaccharide structure, 2-aminoethyl 2-acetamido-2-deoxy-α-d-glucopyranosyl-(1→2)-6-O-[2-(tert-butyloxycarbonylaminoethyl)-phosphono]-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[β-d-glucopyranosyl-(1→4)]-l-glycero-α-d-manno-heptopyranoside, corresponding to the non-reducing part of the conserved part of Neisseria meningitidis lipopolysaccharides has been synthesized. Orthogonal protection of the phosphoethanolamino group in combination with the presence of a free amino-containing anomeric spacer allows conjugation to proteins to construct conjugate vaccine candidates. The tetrasaccharide is built up using a linear strategy, where the introduction of the terminal α-GlcNAc moiety is performed using a 2-azido-thioglucoside as a donor and NIS/AgOTf as a promoter. The synthetic pathway includes tetrasaccharide intermediates appropriately designed to permit other phosphorylation patterns as well as elongation at the reducing end.

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(2′S,3′S) Ethyl 7-O-benzyl-6-O-chloroacetyl-3,4-O-(2′,3′-dimethoxybutane-2′,3′-diyl)-1-thio-l-glycero-α-d-manno-heptopyranosideC24H35ClO9S[α]D = +17 (c 1.0, CHCl3)Source of chirality: d-mannoseAbsolute configuration: (1R,2S,3R,4R,5R,6S,2′S,3′S)

(2′S,3′S) Ethyl 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-d-glucopyranosyl-(1→2)-7-O-benzyl-6-O-chloroacetyl-3,4-O-(2′,3′-dimethoxybutane-2′,3′-diyl)-1-thio-l-glycero-α-d-manno-heptopyranosideC36H50ClN3O16S[α]D = +16 (c 1.0, CHCl3)Source of chirality: d-glucosamine and d-mannoseAbsolute configuration: (1R,2S,3S,4R,5R,6S,2′S, 3′S,1″R,2″R,3″S,4″R,5″R)

(2′S,3′S) Ethyl 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-d-glucopyranosyl-(1→2)-7-O-benzyl-6-O-chloroacetyl-3,4-O-(2′,3′-dimethoxybutane-2′,3′-diyl)-1-thio-l-glycero-α-d-manno-heptopyranoside S-oxideC36H50ClN3O17S[α]D = +22 (c 1.0, CHCl3)Source of chirality: d-glucosamine and d-mannoseAbsolute configuration: (1R,2S,3S,4R,5R,6S,2′S,3′S,1″R,2″R,3″S,4″R,5″R)

(2′S,3′S) 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-d-glucopyranosyl-(1→2)-7-O-benzyl-6-O-chloroacetyl-3,4-O-(2′,3′-dimethoxybutane-2′,3′-diyl)-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-7-O-acetyl-1,6-anhydro-2-O-benzyl-l-glycero-α-d-manno-heptopyranoseC84H90ClN3O32[α]D = +58 (c 1.0, CHCl3)Source of chirality: d-glucosamine, d-glucose and d-mannoseAbsolute configuration: (1R,2S,3S,4R,5R,6S,1′S,2′R,3′S,4′R,5′R,1″R,2″S,3″S,4″R,5″R,6″S,2′′′S,3′′′S,1′′′′R,2′′′′R,3′′′′R,′′′′S,5′′′′R)

3,4,6-Tri-O-acetyl-2-azido-2-deoxy-α-d-glucopyranosyl-(1→2)-7-O-benzyl-6-O-chloroacetyl-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-7-O-acetyl-1,6-anhydro-2-O-benzyl-l-glycero-α-d-manno-heptopyranoseC78H80ClN3O30[α]D = +12 (c 1.0, CHCl3)Source of chirality: d-glucosamine, d-glucose and d-mannoseAbsolute configuration: (1R,2S,3S,4R,5R,6S,1′S,2′R,3′S,4′R,5′R,1″R,2″S,3″S,4″S,5″S,6″S,1′′′′R,2′′′′R,3′′′′R,4′′′′S,5′′′′R)

3,4,6-Tri-O-acetyl-2-azido-2-deoxy-α-d-glucopyranosyl-(1→2)-3,4,7-tri-O-acetyl-6-O-chloroacetyl-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-1,6,7-tri-O-acetyl-2-O-benzyl-l-glycero-α-d-manno-heptopyranosideC81H86ClN3O36[α]D = +40 (c 1.0, CHCl3)Source of chirality: d-glucosamine, d-glucose and d-mannoseAbsolute configuration: (1R,2S,3S,4R,5R,6S,1′S,2′R,3′S,4′R,5′R,1″R,2″S,3″S,4″R,5″R,6″S,1′′′′R,2′′′′R,3′′′′R,4′′′′S,5′′′′R)

2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl-(1→2)-3,4,7-tri-O-acetyl-6-O-chloroacetyl-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-1,6,7-tri-O-acetyl-2-O-benzyl-l-glycero-α-d-manno-heptopyranosideC83H90ClNO37[α]D = +20 (c 1.0, CHCl3)Source of chirality: d-glucosamine, d-glucose and d-mannoseAbsolute configuration: (1R,2S,3S,4R,5R,6S,1′S,2′R,3′S,4′R,5′R,1″R,2″S, 3″S,4″R,5″R,6″S,1′′′′R,2′′′′R,3′′′′R,4′′′′S,5′′′′R)

Ethyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl-(1→2)-3,4,7-tri-O-acetyl-6-O-chloroacetyl-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-6,7-di-O-acetyl-2-O-benzyl-1-thio-l-glycero-α-d-manno-heptopyranosideC83H92ClNO35S[α]D = +28 (c 1.0, CHCl3)Source of chirality: d-glucosamine, d-glucose and d-mannoseAbsolute configuration: (1R,2S,3S,4R,5R,6S,1′S,2′R,3′S,4′R,5′R,1″R,2″S,3″S,4″R,5″R,6″S,1′′′′R,2′′′′R,3′′′′R,4′′′′S,5′′′′R)

2-(N-Benzyloxycarbonyl) aminoethyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl-(1→2)-3,4,7-tri-O-acetyl-6-O-chloroacetyl-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-6,7-di-O-acetyl-2-O-benzyl-l-glycero-α-d-manno-heptopyranosideC91H99ClN2O38[α]D = +18 (c 1.0, CHCl3)Source of chirality: d-glucosamine, d-glucose and d-mannoseAbsolute configuration: (1S,2S,3S,4R,5R,6S,1′S,2′R,3′S,4′R,5′R,1″R,2″S,3″S,4″R,5″R,6″S,1′′′′R,2′′′′R,3′′′′R,4′′′′S,5′′′′R)

2-(N-Benzyloxycarbonyl) aminoethyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl-(1→2)-3,4,7-tri-O-acetyl-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-6,7-di-O-acetyl-2-O-benzyl-l-glycero-α-d-manno-heptopyranoside-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-6,7-di-O-acetyl-2-O-benzyl-l-glycero-α-d-manno-heptopyranosideC89H98N2O37[α]D = +17 (c 1.0, CHCl3)Source of chirality: d-glucosamine, d-mannose and d-glucoseAbsolute configuration: (1S,2S,3S,4R,5R,6S,1′S,2′R,3′S,4′R,5′R,1″R,2″S,3″S,4″R,5″R,6″S,1′′′R,2′′′R,3′′′R,4′′′S,5′′′R)