Chemistry Reference
In-Depth Information
hybrid
38
showed that it is properly recognized by
Ulex Europaeus Lectin-I
when it
adopts an extended conformation.
Taking into account the advantages of “glycoside cluster effect” for improvement
of carbohydrate-lectins interactions, as previously described in section 13.2.1, a new
class of functional, multivalent glycoarchitectures based on hyperbranched polyg-
lycerols (HPGs) conjugated to galactose sugar moieties were developed by click
chemistry with the aim of evaluating their multivalent effect on selectin binding [23].
In fact, HPGs represent ideal scaffolds for the multivalent presentation of saccharides
due to their biocompatible and carbohydrate-like properties. Hence, alkyne groups
were introduced into the HPG
39
by reacting with propargyl bromide in the presence
of NaH whereas galactose was reacted with a propylene spacer containing a terminal
azido group. In sequence, click reactions between alkyne-polymer
40
with protected,
unprotected and sulfated azido-galactose derivatives
41a
-
c
, using CuSO
4
/sodium
ascorbate, in THF/H
2
O, afforded glycopolymers
42a-c
(Scheme 13.7). Then, selectin
O
O
HO
OH
O
OH
O
O
O
OH
OH
O
O
O
O
HO
OH
HO
O
OH
O
O
Br
O
O
O
OH
HO
HO
OH
O
O
O
O
HO
NaH
DMF
O
O
O
O
O
HO
O
O
O
O
O
OH
OH
O
O
O
O
O
O
O
HO
OH
O
O
O
HO
OH
O
OH
O
OH
O
OH
O
O
O
HO
OH
O
OH
HO
O
O
HO
OH
O
O
HO
O
O
O
HO
OH
39
RO
40
OR
RO
RO
OR
OR
RO
RO
RO
O
O
O
OR
O
N
3
O
RO
OR
a
R=Ac
b
R=H
c
R=SO3 Na
O
RO
OR
RO
41a-c
N
CuSO
4
, sodium ascorbate,
THF/ water
N
O
N
N
N
OR
N
OR
N
N
O
O
RO
O
O
N
O
RO
RO
O
OH
O
O
OR
RO
OR
O
N
O
N
N
HO
N
OH
OR
O
O
N
O
N
O
O
O
OR
OH
O
O
O
N
N
N
RO RO
N
HO
O
RO
O
O
O
O
O
O
O
N
N
O
O
O
OR
O
O
HO
OH
OR
RO
O
OR
N
N
O
OR
O
OH
O
N
OH
O
O
O
N
O
RO
O
HO
N
O
OR
O
N
RO
N
N
OR
N
N
O
N
RO
N
O
O
N
O
N
N
O
N
OR
N
N
N
N
OR
RO
OR
O
O
N
O
RO
O
OR
OR
OR
O
RO
RO
RO
RO
O
RO
O
OR
OR
RO
RO
O
RO
OR
O
RO
RO
OR
42a-c
SCHEME 13.7
Synthesis of multivalent HPG
42a-c
constructs by click chemistry.
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