Chemistry Reference
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OAc
O
O
AcO
OAc
AcO
O
BnO
+
AcO
O
O
BnO
OAc
O
BnO
O
AcO
OPMP
O
O
N
3
AcO
BnO
O
AcO
BnO
AcO
n
50
51
n
=
1
(Ph
3
P)
3
CuBr,
DIPEA
toluene,
20°C,
12
h
52
n
=
5
OAc
O
AcO
OAc
AcO
AcO
O
OAc
O
AcO
N
O
N
OAc
AcO
N
O
AcO
O
AcO
AcO
OAc
AcO
n
PMPO
O
AcO
O
O
O
OAc
OBn
AcO
N
AcO
N
O
N
O
AcO
OBn
O
O
AcO
O
OBn
n
53
n
=
1
BnO
OBn
54
n
=
5
SCHEME 5.14
Synthesis of amylopectin analogs on maltose scaffold.
the synthesis of the regioselectively propargylated maltose derivatives
50
via
the
corresponding trityl precursors. On the other hand, peracetylated
-glycosyl azides
of glucopyranose (
56
), maltotriose and maltoheptaose were prepared by reaction of
the corresponding glycosyl bromides with Me
3
SiN
3
in the presence of Bu
4
NF. For
the click reaction the authors used (Ph
3
P)
3
.CuBr as a catalyst in the presence of
DIPEA as a base. Final compounds (
53
,
54
,
57
) were obtained in 27-65% yields,
with yields decreasing when the length of the azidooligosaccharide chain increased.
1,2,3-Triazole glycosides designed as acarbose mimetics have been synthesized
and tested as
-glucosidase inhibitors (Scheme 5.16) [19a]. The strategy involved
the thermal cycloaddition of an internal asymmetric alkyne which led to a mixture of
regioisomers (54% yield), which were isolated by chromatography (Scheme 5.17).
These analogs have been included here because they belong to the family of sugar
derivatives focused in this chapter, in spite of the fact that the cycloaddition reaction
was not Cu(I) catalyzed.
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