Chemistry Reference
In-Depth Information
O
O
O
P
PPh
2
OH
83
84
Cometti
,
1982
Alper
,
1990
ee = 91%
b/l = 100/-
ee = 52%
b/l = 94/6
O
O
2
P
P
MeO
P
85
86
87
Nozaki
,
1997
Nozaki
,
2004
Claver, 2005
ee = 29%
b/l= 97%
ee = 2.4%
b/l = 98/2
ee = 53%
b/l = 100/-
Figure 10.19.
Monodentate phosphines used in asymmetric methoxycarbonylation of vinylarenes.
PPh
2
PPh
2
Figure 10.20.
The BINAP ligand
88
.
reaction. They showed that systems containing phosphetane ligands could also yield high
regioselectivity to the branched ester and ee's up to 29% in the methoxycarbonylation
of styrene using [PdCl
2
(
87
)
2
] as precursor at 70°C under 35 atm of CO (Fig. 10.19) [69].
10.3.4. Other Substrates
Using the Pd(OAc)
2
- DDPPI -
p -
TsOH (DDPPI = igand
73
, Fig. 10.17) catalytic system
for the methoxycarbonylation of norbornene, Zhou et al. achieved 92% ee under 50 atm
of CO at 120°C [70].
In 2003, the asymmetric methoxycarbonylation of acenaphthylene was reported by
using BINAP
88
(Fig. 10.20) as chiral ligand at 80°C in the presence of
p -
TsOH and
under 30 atm of CO [71]. Interestingly, by using [PdCl
2
(NCPh)
2
] as Pd precursor, ee ' s
up to 45% with 12% conversion were achieved, while using Pd(OAc)
2
only led to ee's
up to 34% but in 60% conversion under identical conditions.
