Chemistry Reference
In-Depth Information
Me
Me
PdCl
2
, PPh
3
,
Et
3
N, CO (5 atm)
+
O
Me
I
Me
O
O
4.80
4.81
4.82
Scheme 4.34
MeO
2
C
MeO
2
C
[(cinnamyl)PdCl]
2
,
L =
4.89
,
Et
3
N, CO (5 bar)
+
Br
O
4.83
4.84
4.85
Scheme 4.35
[(cinnamyl)PdCl]
2
,
L =
4.89
,
Et
3
N, CO (5 bar)
EtO
EtO
+
O
n
-Bu
O
n
-Bu
Br
O
4.86
4.87
4.88
Scheme 4.36
4.34).
35
With other alkenes, including styrene
4.84
, enol ethers
4.87
and acrylates, success was only obtained
by switching to a sophisticated phosphine ligand
4.89
(Schemes 4.35 and 4.36).
36
N
P
i
-Ad
2
N
i
-Pr
i
-Pr
4.89
The intermolecular version of the reaction can also be effective, and, under the right conditions, can give
good yields even when the substrate, such as iodide
4.90
, is capable of
-hydride elimination (Scheme 4.37).
37
Curiously, the intramolecular carbonylative Heck reaction of styrene
4.03
proceeded with net reduction of
the alkene (Scheme 4.38).
38
Multiple insertions are possible. Systems have been designed that involve two alkene insertions and three
carbon monoxide insertions, which proceed in good yield, such as the conversion of
4.95
to
4.96
(Scheme
4.39).
39
The efficiency of the reaction is notable, as the tandem sequence can go astray at various points
(Scheme 4.40). Several intermediates are capable of undergoing
-hydride elimination (
4.99
,
4.101
)ordirect
alkene insertion (
4.97
,
4.99
), but do not: CO insertion occurs instead. The high CO pressure (40 atm) is likely
to be responsible in part for this selectivity.
O
O
H
H
(Ph
3
P)
4
Pd,
i
-Pr
2
NEt,
CO (50 atm)
+
I
H
H
4.90
4.91
4.92
Scheme 4.37
