Chemistry Reference
In-Depth Information
HNPhth, Pd(OAc)
2
,
AgBF
4
, PhI(OAc)
2
O
HO
PhthN
6.106
6.107
Scheme 6.36
O
NHTs
Pd(OAc)
2
, PhI(OAc)
2
,
Me
4
NCl, NaOAc
O
NH
N
NTs
6.108
6.109
Scheme 6.37
N
E
t
3
R
R
PdCl
2
, Et
3
N
Pd
Cl
6.110
NEt
3
CO
2
Me
CO
2
Me
CO
2
Me
CO
2
Me
CO
2
Me
CO
R
R
→
RT
R
CO
2
Me
CO
2
Me
CO
2
Me
O
PdL
n
Cl
6.112
6
1
1
6.109
PdL
n
Cl
H
2
CO
2
Me
ArSnMe
3
ArSnMe
3
R
CO
2
Me
CO
2
Me
CO
2
Me
CO
2
Me
6.113
R
R
R
CO
2
Me
CO
2
Me
CO
2
Me
O
O
Ar
6.114
6.115
6.116
OMe
Ar
Scheme 6.38
Using carbon nucleophiles in these schemes is complicated by the fact that the nucleophiles themselves
are often susceptible to oxidation. The most general system is a stepwise process that is stoichiometric in
palladium (Scheme 6.38).
35
The alkene is first complexed to palladium in the presence of triethylamine,
which acts as a ligand. Addition of a stabilized carbanion nucleophile to the
2
-complex
6.110
results in
1
-complex
6.111
. Complexes of this type are stable at -20
◦
C. At higher temperatures,
the formation of a
-hydride elimination occurs to give the alkene
6.112
. Alternatively, other reagents may be added to intercept
the complex and make extra use of the expensive palladium atom. Hydrogenation yields the alkane
6.113
,
while addition of a tin reagent results in Stille coupling product
6.114
. Addition of CO and an alcohol gives
an ester
6.115
;
36
addition of a tin reagent and CO results in a ketone
6.116
.
37
Both of the carbonylation
1
-acyl complex
6.109
.
reactions proceed via the
