Chemistry Reference
In-Depth Information
TABLE 8B.57. C u Complexes and Ligands Used in C u - Catalyzed Allylic Alkylations
Cu
S
NMe
2
RMgI
X
Cu-Cat., Et
2
O
K7
R
Entry
X
R
Cu - Cat.
Mol% Cat.
T ( ° C)
Yield (%)
ee (%)
1
OAc
K7
5
20
100
31
n
- Bu
2
OAc
K7
5
0
100
29
n
- Bu
3
OAc
K7
15
0
100
42
n
- Bu
4
OAc
CuI/
L65
15
0
100
40
n
- Bu
5
OAc
i
- Pr
CuI/
L65
15
0
100
34
6
OAc
i
- Bu
CuI/
L65
15
0
80
40
7
OAc
Me
3
SiCH
2
CuI/
L65
15
20
100
37
8
OAc
n
- Bu
CuI/
L66
13
25
88
64
Ph
Ph
NMe
2
Ph
SH
SH
NMe
2
O
O
O
O
P
N
P
O
NMe
2
Fe
O
O
Ph
Ph
Ph
Ph
L
L
6
L
L
8
OMe
Me
2
N
PPh
2
O
Ph
O
P
N
P
N
Fe
PPh
2
Ph
O
O
OMe
TANIAPHOS
(
S
,
S
,
aR
)-
L59
(
R,R,R
)-
L
L
Figure 8B.36.
Ligands used in the cross-coupling of allyl substrates with Grignard reagents.
Nearly at the same time, Alexakis et al. found by high throughput screening a
TADDOL - based phosphite
L67
giving up to 73% ee in the addition of EtMgBr to cin-
namyl chloride (Table 8B.58, entry 1). CuCN was used as catalyst precursor, and a slow
addition of the Grignard reagent was essential for good ees [348]. A further increase of
the selectivity could be obtained with Cu thiophene carboxylate (CuTC) as copper
