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introduction of
azide acetylene
O
HO
OH
HO
O
O
HO
HO
HO
OH
OH
OH
AcNH
4
5
O
MeO
OAc
AcO
O
O
HO
N
3
OBn
BzO
O
BzO
AcNH
6
7
Cu(I)
OAc
MeO
AcO
O
O
O
HO
BzO
OBn
O
N
N
AcNH
N
BzO
8
FIGURE 9.3
The coupling of two sugar molecules via click chemistry.
bioorganic, and medicinal chemistry [7,10-22]. One of these fields is sugar chemistry.
Sugars are very convenient, “graceful” objects not only because of their biological
activity or usefulness as components of the “chiral pool” but also they are useful
materials for testing new concepts of synthesis. Moreover, the basic chemistry of
simple sugars is well known, which allows the introduction of the reactive azide
functionality at the precisely designed position of the carbohydrate molecule. This
may be illustrated by the example shown in Figure 9.3.
Standard carbohydrate methodology (involving proper protection-deprotection)
allows the introduction of the azide group onto the C1 of the gluconic acid (
4
→
6
)
and the acetylene at the C3 of the galactosamine part (
5
7
). Coupling of these
two activated molecules by click methodology provided the building block
8
,used
further to prepare unnatural heparosan and chondroitin [23].
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