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In-Depth Information
OH
Protoamino
bacter rubrum
CB5 574.77
O
H
OH
O
O
HO
H
OH
OH
palatinose
HO
facile cleavage of this
bond by acids
OH
Cl
OH
HO
Cl
1. enzymatic
protection of 6-O
H
O
6
6'
O
HO
Cl
O
O
1'
H
O
OH
2. chlorination
3. deprotection
H
O
OH
OH
OH
sucralose
H
1
OH
OH
sucrose
650 x more
sweet than sucrose
HO
1. Ph
3
P/CCl
4
2. NaN
3
O
O
NH
HO
X
O
HO
NH
2
2.
X = O, S, N
4
N
3
N
3
N
3
OBn
OH
O
O
HO
O
H
O
BnO
+
BnO
N
3
O
OH
OH
H
OBn
3
OH
BnO
OH
OBn
Scheme 1 Examples of transformation of sucrose with destruction of its skeleton.
Enzymatic rearrangement of sucrose with Protoaminobacter rubrum
CB5 574.77 performed on an industrial scale, affords isomaltulose (also
named palatinose
s
) widely applied as artificial sweetener.
6
Interesting
optically pure derivatives (e.g. spiro-system 2
7
or analogs of nojirimycin
8
4) were obtained by hydrolysis of the glycosidic bond in functionalized
sucroses. Sucralose (1
0
,4,6
0
-trideoxy-1
0
,4,6
0
-trichloro-galacto-sucrose),
9
prepared by chlorination of 6-O-acetylsucrose
10
with SO
2
Cl
2
/pyridine,
represents an example in which the disaccharide skeleton is only slightly
modified.
Much more interesting (at least from our point of view) are transfor-
mations in which the carbohydrate backbone is preserved. The material
presented in this chapter will be oriented on such processes which do not
destroy the disaccharide moiety. Such derivatives of sucrose, modified at
the terminal positions might possess interesting biological properties.
11
The hydroxyl groups of sucrose can be differentiated by ester, acetal,
and ether forming reagents. Two former were extensively reviewed (see
ref. 1-3) and will not be discussed.
The material presented here will be focused on differentiation of the
hydroxyl groups by ether forming reagents and further transformations
of resulting derivatives. Moreover, the emphasis will be put on such
reactions in which only primary hydroxyl groups are involved.
The approach to macrocyclic derivatives with sucrose scaffold will also
be discussed. Application of simple sugars as chiral platforms in the
synthesis of receptors able to discriminate enantiomers is already quite
well established;
12
however, there are only limited examples of the
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