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HO
HO
HO
O
H
N
HO
O
N
N
3
HO
HO
HO
O
N
O
N
HO
HO
HO
O
HO
HO
HO
O
O
H
N
O
HN
O
HO
O
HN
O
O
OH
O
S
CuSO
4
, NaAsc, H
2
O
O
NH
O
S
HO
S
S
n
HO
S
S
n
76
77
SCHEME 6.13
Click post-glycosylation of pre-synthesized glycopolymers.
the simultaneous incorporation of a sugar and a fluorescent dye [112]. Interestingly,
the curdlan-mannopyranosyl neoglycopolymer was able to interact with polycytosine
(polyC) in a similar manner as the native polysaccharide to form a triple-stranded sta-
ble macromolecular complex with two strands of the glycopolymer and one strand of
polyC. These macromolecular complexes showed strong and specific affinity toward
complementary lectins [114].
The above approach was implemented by Fleury and coworkers for the click post-
glycosylation reaction of pre-synthesized glycopolymers bearing azide functionalities
at the preinstalled sugar moieties [115]. Thus, they prepared the polyazide glycopoly-
mer
76
by reversible addition-fragmentation chain transfer (RAFT) polymerization
of
N
-(2-azido-2-deoxy-
-D-mannopyranosyl)acrylamide and subjected it to CuAAC
with
N
-propargylamidomethyl-
-D-glucopyranoside, to give the corresponding neo-
glycopolymer with pseudodisaccharide pendant units
77
(Scheme 6.13).
A third general strategy to build triazole-linked multivalent glycopolymers takes
advantage of the efficiency of the Cu(I)-catalyzed azide-alkyne click coupling to
prepare monomers bearing polymerizable groups, such as vinyl [116] or 2-oxazoline
groups [117], avoiding complex reactions and purification procedures often associated
with carbohydrate monomer synthesis. Khiar and coworkers reported a remarkable
application of this tactic to assemble polymeric “click glycoliposomes” by pho-
topolymerization of click diacetylene monomers [118]. Propargylamide
79
, prepared
from pentacosa-10,12-diynoic acid (PCDA,
78
) was clicked with sugar azidoglyco-
sides with different spacers (e.g.,
80
) to give diacetylenic glycoamphiphiles (e.g.,
81
) that were inserted in PCDA liposomes before polymerization (
82
), affording
stable unilamellar vesicles (100-500 nm) whose color shifted from blue to red upon
interaction with a specific lectin (Scheme 6.14).
Amphiphilic click glycopolymers can be used as precursors for the generation
of self-assembled glyconanoparticles by nanoprecipitation [119, 120]. Zhao and
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