502
3
Chemical Glycosylation Reactions
⊡ Scheme 34
ranosyl oligosaccharides up to the octamer based on related methodologies [235]. 2-O-Arabinofuranosylated β(1–6)-linked galactopyranosyl oligosaccharides, found in arabiogalactans,
could be obtained also by Kong et al. [236] who also reported the successful synthesis of other
arabinogalactan linkage types based on the trichloroacetimidate method [237,238,239,240].
Lipoarabinomannans have attracted great interest as well, because they are part of the cell
surface oligosaccharide of mycobacterial species that cause many diseases, including tuberculosis and leprosy. The largest heteroglycan synthesis for this type of compound was recently
reported in which the trichloroacetimidate method plays an important role [241].
In algal cell wall polysaccharides β(1–3)-linked xylans were found. Fragments up to the
hexamer were successfully synthesized [242]. The specific O-chain of the lipopolysaccharide
of many bacteria contains repeating units composed of various sugar residues. Several of these
repeating units or fragments thereof have been synthesized based on the trichloroacetimidate
method. Rhamnosylated rhamnan [243], the D-Rhapα(1–3)[L-Xylpβ(1–2)]D-Rhapα(1–3)
[L-Xylpβ(1–2)]D-Rha unit [244], ( > Scheme 34, 34i), a more complex xylorhamnan [245],
a xylosylated GlcNAc rhamnan [246], a rhamnan with GlcNAc in the branch [247,248],
the pentasaccharide D-Glcβ(1–2)-[D-Ribf β(1–3)]L-Rhapα(1–3)L-Rhapα(1–3)L-Rhapα(1–2)
L-Rhap [249], the glucurono xylomannan hexasaccharide repeating unit of C. neoformans
serotype A ( > Scheme 35) [250], a heptasaccharide fragment of C. neoformans serotype
C [251], a repeating unit of lactosillan [252], the Shigella flexneri serotype 2a [253,254,255,256,257],
and serotype 5a [258] have been efficiently obtained ( > Scheme 36). The straight forward syn-
3
Chemical Glycosylation Reactions
⊡ Scheme 34
ranosyl oligosaccharides up to the octamer based on related methodologies [235]. 2-O-Arabinofuranosylated β(1–6)-linked galactopyranosyl oligosaccharides, found in arabiogalactans,
could be obtained also by Kong et al. [236] who also reported the successful synthesis of other
arabinogalactan linkage types based on the trichloroacetimidate method [237,238,239,240].
Lipoarabinomannans have attracted great interest as well, because they are part of the cell
surface oligosaccharide of mycobacterial species that cause many diseases, including tuberculosis and leprosy. The largest heteroglycan synthesis for this type of compound was recently
reported in which the trichloroacetimidate method plays an important role [241].
In algal cell wall polysaccharides β(1–3)-linked xylans were found. Fragments up to the
hexamer were successfully synthesized [242]. The specific O-chain of the lipopolysaccharide
of many bacteria contains repeating units composed of various sugar residues. Several of these
repeating units or fragments thereof have been synthesized based on the trichloroacetimidate
method. Rhamnosylated rhamnan [243], the D-Rhapα(1–3)[L-Xylpβ(1–2)]D-Rhapα(1–3)
[L-Xylpβ(1–2)]D-Rha unit [244], ( > Scheme 34, 34i), a more complex xylorhamnan [245],
a xylosylated GlcNAc rhamnan [246], a rhamnan with GlcNAc in the branch [247,248],
the pentasaccharide D-Glcβ(1–2)-[D-Ribf β(1–3)]L-Rhapα(1–3)L-Rhapα(1–3)L-Rhapα(1–2)
L-Rhap [249], the glucurono xylomannan hexasaccharide repeating unit of C. neoformans
serotype A ( > Scheme 35) [250], a heptasaccharide fragment of C. neoformans serotype
C [251], a repeating unit of lactosillan [252], the Shigella flexneri serotype 2a [253,254,255,256,257],
and serotype 5a [258] have been efficiently obtained ( > Scheme 36). The straight forward syn-