Chemistry Reference
In-Depth Information
Pd(OAc)
2
(6 mol %)
158
(6 mol %)
Proton sponge (2 eq
)
Pd(OAc)
2
(6 mol %)
157
(6 mol %)
Proton sponge (2 eq
)
OTf
+
O
O
O
THF, 90°C, 20 h
THF, 90°C, 20 h
148
149
151
150
(4.0 eq)
82% ee
98% ee
Pd(dba)
2
(3 mol %)
159
(6 mol %)
i
-Pr
2
NEt (2 eq)
Pd(dba)
2
(3 mol %)
160
(6 mol %)
i
-Pr
2
NEt (2 eq)
THF or benzene
60°C
+
ROTf
R
R
O
O
O
THF or benzene
60°C
(
S
)
(
R
)
148
78-100%
39-87% ee
(S)
66-89%
81-95% ee
(R)
R = Ph, 2-naphthyl,
p
-MeO-C
6
H
4
,
p
-F-C
6
H
4
,
p
-Me-C
6
H
4
, cyclohexenyl
Scheme 8C.53.
Pd(OAc)
2
(3 mol %)
(S)
-BINAP (9 mol %)
K
2
CO
3
(3 eq), 3 Å MS
Benzene, 65°C
O
Z
O
Z
O
R
1
R
2
R
1
R
2
+ rO f
Ar
Ar
O
O
O
173
172
174
13-86%, 5-75% ee
175
R
1
R
2
Z = H
2
C, Me
2
C, (CH
2
)
5
C,
t
-Bu
2
Si
Ar = Ph, p-Cl-C
6
H
4
-, p-Me-C
6
H
4
-, p-MeO-C
6
H
4
-,
2-naphthyl
[Pd
2
(dba)
3
]•dba (1.5-2.5 mol %)
L
*
(5.5 mol %)
i
-Pr
2
NEt (2 eq)
THF, 70°C
OTf
O
O
+
O
O
149
172a
174a
L
*
=
161
70%, 92% ee
(3.0-4.0 eq)
L
*
=
162
84%, 92% ee
Scheme 8C.54.
[96]. The same reaction using P,N-ligand
162
also afforded
172a
in 84% yield and 92%
ee (Scheme 8C.54 ) [91] .
8C.5.4.3. Other Substrates for Asymmetric Intermolecular Heck Reactions
In addi-
tion to dihydrofurans and dihydrodioxepins, dihydropyrroles and cyclopentene have
been employed as substrates for asymmetric intermolecular Heck reaction. For example,
the reaction of 2,3-dihydropyrrole
178
with aryl trifl ate
149
catalyzed by Pd complex and
chiral P,N - ligand
159
gave (
S
) - 2 - aryl - 2,5 - dihydropyrrole (
S
)
- 179
in good yield and up to
89% ee, while the same reaction catalyzed by Pd-
160
afforded the enantiomeric (
R
)
-
179
in moderate yield and 60-70% ee (Scheme 8C.55) [94]. The reaction of cyclopentene
