Chemistry Reference
In-Depth Information
OH
OH
Ph
Ph
N
N
Cl
Na
2
PdCl
4
, NaOAc
Pd
H
2
3.107
3.108
Scheme 3.47
1. Na
2
PdCl
4
, NaOAc
2. PPh
3
HO
HO
N
N
Cl(Ph
3
P)Pd
3.110
H
3.109
I
2
HO
N
3.111
I
Scheme 3.48
HO
HO
N
N
1. PdCl
2
, NaOAc
2. mcpba
Cl
3.112
3.113
Scheme 3.49
Versions of this chemistry that results in formation of carbon-oxygen and carbon-nitrogen and
carbon-halogen bonds, and are also catalytic in palladium have been developed (Scheme 3.50). The choice
of an appropriate oxidizing agent is key to the success of the chemistry. Iodosobenzene diacetate has been
found to be very effective for adding an acetate group. It has been proposed that this is by oxidation of the
C-H activation intermediate from a palladium(II) complex
3.117
to a palladium(IV) complex
3.118
, which
triggers reductive elimination, giving the
ortho
-acetoxylated product
3.115
.
The acetoxylation reaction can be applied to aryl (Scheme 3.51),
50
benzylic (Scheme 3.52)
51
and aliphatic
C-H bonds (Schemes 3.53 and 3.54).
52,53
