Chemistry Reference
In-Depth Information
O
HO
P
OH
O
O
O
Polyprenyl-phospho-
arabinose
O
n
OH
1
O
HO
O
Nucletotide-sugars
NH
O
O
HO
O
O
O
P
P
OH
N
O
O
HO
O
O
2
:UDP-
α
-D-Gal
f
OH
OH
O
HO
O
NH
O
O
O
O
O
P
P
OH
OH
N
O
O
O
O
3
:UDP-
β
-L-Ara
f
OH
OH
Fig. 1 Structures of natural Araf and Galf donors.
X
BzO
Br
HO
S
N
O
O
BzO
HO
R
OBz
R
OH
4
7
H
3
PO
4
R
2
O
O
O
UDPH
2
R
2
O
O
O
From
8
P
R
OR
2
UDP-
α
-D-G lc
p
(cat.), UTP
O
5
(R
2
=Bz)
8
(R
2
=H)
Gal-1-phosphate
uridyltransferase
(Gal-1-PUT)
O
From
5
NH
O
O
UDP-Glc
p
pyrophosphorylase
N
O
P
N
O
O
O
Inorganic
pyrophosphatase
Then
deprotection
6
OH
OH
O
HO
O
NH
O
O
HO
O
O
O
P
P
R
OH
N
O
O
O
O
Nucleotide-sugars
OH
OH
Scheme 1 Chemical and chemo-enzymatic synthesis of UDP-sugars.
UDP-a-
D
-Galf and UDP-a-
D
-Araf present poor stability in water and
could not be easily isolated from cell cultures. Therefore, synthetic
strategies were developed in order to provide them in reasonable amount
for further biological studies. The first chemical synthesis of UDP-a-
D
-
Galf, the phosphoramidate strategy, was proposed in 2000 by Tsvetkov
and Nikolaev,
20
and Zhang and Liu
14
(Scheme 1). The time and yield
limiting step of this approach was subsequently improved by Kiessling's
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