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In-Depth Information
OH
HO
O
O
HO
N
HO
N
OH
HO
N
OH
O
OH
HO
OH
HO
O
H
HO
O
OH
O
O
OH
O
HO
HO
OH
O
O
H
HO
OH
N
O
HO
N
OH
OH
O
O
HO
N
N
OH
N
O
N
OH
N
N
N
N
O
O
N
O
N
N
HO
O
O
N
HO
N
HO
O
N
O
O
O
N
HO
N
OH
N
HO
O
HO
OH
O
O
N
OH
OH
N
O
HO
OH
HO
OH
HO
HO
O
HO
H
55
HO
56
FIGURE 12.20
Glyco-clusters exhibiting lectin inhibition.
Wong and group prepared very first carbohydrate microarrays via CuAAC reac-
tion using long aliphatic chains bearing terminal alkyne for the derivatization of
polystyrene microtiter plate through non-covalent glycolipid interactions. A series
of 11 diverse azido-sugars were prepared for grafting onto alkyne-functionalized
plate via click reaction followed by evaluation of the extent of fucosylation and/or
sialylation against potent lectin inhibitors (Scheme 12.4) [72].
Reineke et al. synthesized the diazo trehalose monomer (
70
) that underwent poly-
merization with various dialkyne-oligoamine monomers containing 1, 2, and 3-Boc-
protected secondary amines to afford three water soluble biocompatible polycations
(
73a-c
) identified as effective nucleic acid carriers (Scheme 12.5) [73].
In another approach, an efficient one-pot three enzyme based chemoenzy-
matic strategy has been developed by Chen's Research Group at UC Davis for
an easy access of diverse sialic acid containing molecules [57]. These highly
potential molecules have been successfully utilized to achieve structurally defined
sialic acid containing macrocyclic oligosaccharides of different sizes. In this
context, several oligosaccharides of varying lengths have been prepared using
chemoenzymatic method, which contain galactose at the non-reducing end and
propargyl group at the reducing end. Further, their chemoenzymatic sialylation
led to well-defined sialosides, equipped with azide and alkyne functionalities at
the two ends, for example, (
74
) on successive cyclization reaction under click
condition affords sialic acid-containing complex macrocycle (
75
) in good yield
(Scheme 12.6) [74].
The knowledge of various biochemical and physiological processes at the molec-
ular level, for example, molecular components of living cells, their organization,
interaction, movement, formation and elimination etc. can be traced out with the help
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