Chemistry Reference
In-Depth Information
A new approach towards
N-
glycosyl nitrones has been reported by Goti
et al
.
[53] Reaction of various anomerically unprotected monosaccharide derivatives
with
N-
alkyl hydroxylamines yielded
N-
glycosyl
N-
alkyl hydroxylamines, of which
only the cyclic form was detectable. Scheme 4.36 shows the preparation of
D-erythro
HO
Ph
O
Ph
N
N
O
O
O
OH
Bn-NH
2
-OH Cl
MnO
2
, CH
2
Cl
2
pyridine
O
O
O
O
O
97%
O
- H
2
O
CH
3
CH
3
CH
3
H
3
C
H
3
C
H
3
C
88%
β
only
209
210
211
MeO
2
C
MeO
2
C
CO
2
Me
CO
2
Me
CO
2
Me
CO
2
Me
O
O
N
N
212
O
O
Ph
Ph
+
toluene
O
O
O
O
CH
3
CH
3
H
3
C
H
3
C
trans-213
cis-214
77% ds trans/cis >97%
D-manno
H
3
C
H
3
C
H
3
C
H
3
C
H
3
C
H
3
C
O
O
O
H
3
C
H
3
C
H
3
C
CH
3
CH
3
CH
3
MnO
2
, CH
2
Cl
2
Bn-NH
2
-OH Cl
O
O
O
O
O
O
O
O
O
O
O
O
OH
pyridine
97%
- H
2
O
N
N
HO
O
73%
Ph
Ph
57
α
only
215
216
H
3
C
H
3
C
H
3
C
H
3
C
O
O
H
3
C
CH
3
H
3
C
CH
3
CO
2
Me
CO
2
Me
O
O
O
O
O
O
O
+
O
21
2
N
N
O
O
toluene
Ph
Ph
CO
2
Me
CO
2
Me
MeO
2
C
MeO
2
C
trans-217
cis-217
70% ds trans/cis 90%
Scheme 4.36
Preparation of
N
-glycosyl nitrones from d-erythro precursor
209
and d-manno
precursor
57
by oxidation of the corresponding
N
-glycosyl
N
-alkyl hydroxylamines
210
and
215,
including their application in stereoselective 1,3-dipolar cycloadditions with dimethyl
maleate (
212
).
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