Chemistry Reference
In-Depth Information
Table 16.9
Bifunctional tertiary amino-thiourea promoted asymmetric Michael addition of
acetylacetone to nitroolefins.
OAc
S
O
AcO
AcO
N
H
NMe
2
H
O
O
OAc
O
O
10b
(10 mol%)
NO
2
+
R
NO
2
Toluene, -40 °C
R
17
R
Yield (%)
ee (%)
Ph
93
96
4-MeC
6
H
4
80
89
4-BnOC
6
H
4
96
85
4-MeOC
6
H
4
99
88
3-MeOC
6
H
4
99
92
2-MeOC
6
H
4
89
92
2,4-(MeO)
2
C
6
H
3
99
84
4-CF
3
C
6
H
4
76
91
3-CF
3
C
6
H
4
82
89
2-CF
3
C
6
H
4
81
95
4-ClC
6
H
4
91
88
1-Naphthyl
97
95
2-Furyl
99
94
5-Me-2-furyl
99
85
85
81
(E)
-PhCH
=
CH-
nucleophiles to afford the Michael adducts in high yield with good diastereo- and
enantioselectivity.
At the same time, Zhou and coworkers reported the enantioselective Michael
addition of acetylacetone to nitroolefins by using saccharide-derived bifunctional
tertiary amine-thioureas [30]. In terms of enantioselectivity, catalyst
10b
derived
from d-glucopyranose and
N
-[(1
R
,2
R
)-2-aminocyclohexyl]-
N
,
N
-dimethylamine
gave the best results (Table 16.9). Various nitroolefins containing aryl and
heteroaryl groups gave the desired adducts
17
in high yields (76
−
99%) and
enantioselectivities (80
96%
ee
). However, the reaction of aliphatic nitroolefins
and nitro-substituted aryl nitroolefins did not proceed at all.
−
16.4
Miscellaneous Reactions
Besides the reactions described in the previous sections, carbohydrate-derived
organocatalysts have also been applied to other asymmetric transformations
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