Chemistry Reference
In-Depth Information
R
O
Ph
OH
N
OBu
t
O
N
Ph
2
C=N
Ph
OBu
t
130
(20 mol %)
+
MeN
NMe
COR
1
Ph
Ph
CO R
1
Up to 98% yield
Up to 97% ee
R = Bn or Ph
R
1
=Me,OEt,OMe
130
Scheme 8A.72.
O
O
R
2
131
(S,S)-[(salen)Al]
2
O
(2.5-10 mol %)
O
O
R
2
O
NBn
+
NC
CO
2
R
3
HN
or
NC
R
1
H
Ph
R
1
R
1
CO
2
Et
t
-BuOH
Cyclohexane
H
3
CO
2
C
Ph
NC
76-98%, 86-98%ee 68-92%, 91-97%ee
R
1
=n-Pr,Me,i-Bu,Ph
R
2
=2-CF
3
C
6
H
4
,4-MeOC
6
H
4
,
Ph, 2-thiophenyl, NHBn
R
3
=Me,Et
NN
Al
O
O
(salen)Al
O
R
1
O
NC
CO
2
CH
3
132
: (R,R)-[(salen)Al]
2
O
(1-5 mol %)
+
R
1
R
2
NC
R
2
CO
2
CH
3
°
H
R
1
= Ph, 2-thienyl, n-Pr
CH
2
CH
2
OBn
R
2
=CH
3
,n-Bu,Ph,i-Pr
Cyclohexane, 23
C
85-91% yield
75-93% ee
Scheme 8A.73.
Deng et al. [146] developed the fi rst highly enantioselective catalytic conjugate addi-
tion of
-cyanoacetates to vinyl sulfones, affording the corresponding products
in excellent yields (89-96%) and enantioselectivities (93-97% ee) (Scheme 8A.74).
Chen and coworkers [147] reported a highly enantioselective Michael addition of
α-substituted cyanoacetates to vinyl ketones catalyzed by simple bifunctional thiourea/
tertiary amine organocatalyst
134
. A number of α-aryl or alkyl cyanoacetates could be
successfully applied to give multifunctional compounds with carbon-substituted quater-
nary stereocenter with excellent enantioselectivities (82-97% ee) (Scheme 8A.75).
Jørgensen et al. [148] developed the fi rst example of nucleophilic attack from the
α-position of an allylic chiral ion pair derived from alkylidene cyanoacetates to acrolein
α
- aryl
α
