Chemistry Reference
In-Depth Information
MeO
MeO
O
MeO
Fe(CO)
3
Fe(CO)
3
Fe(CO)
3
1. Me
3
NO
2. H
3
O
+
BnNH
2
NHBn
NBn
NBn
OTs
OTs
1
0
.
1
1
4
1
0
.
1
5
1
0
.
1
1
6
10.117
Scheme 10.29
MeO
2
C
MeO
2
C
MeO
2
C
Fe(CO)
3
Fe(CO)
3
Fe(CO)
3
Ph
3
C
+
aq. KHCO
3
HO
1
1
8
1
1
1
1
0
1
MeO
2
C
MeO
2
C
1. TBSCl,
i
-Pr
2
NEt
2. Me
3
NO
1. OsO
4
2. TBAF
TBSO
HO
OH
OH
1
0
1
1
1
1
2
Scheme 10.30
MeO
Fe(CO)
3
MeO
1.
NHBoc
M
CO
2
Bn
2. Me
3
NO
NHBoc
1
1
3
1
0
1
2
M = IZn(CN)Cu
CO
2
Bn
Scheme 10.31
4
-complex. This may be oxidatively decomplexed to give the free
ligand or, to gain better value from the metal, reoxidized to a new
The product of nucleophilic attack is an
5
-complex. This can then be subjected
to a second nucleophilic attack. This strategy has been used, for instance, to generate nitrogen heterocycles
by combining a
C
-nucleophile and an
N
-nucleophile (Scheme 10.32). Initial
C
-addition of anion
10.125
to
complex
10.95
gave the
4
-complex
10.126
. Various oxidants can be used to regenerate the
5
-complex; in
5
-complex
10.128
after removal of the only available proton
trans
to iron.
43
Nucleophilic attack by nitrogen then gave the tricyclic product
10.129
.
Use of excess oxidant leads to decomplexation and aromatization of the product. In the case of electron-
rich aromatic products, oxidation can go further to quinone-like compounds. This has been used in the
synthesis of carbazole natural products (Scheme 10.33).
44
The substituted aniline
10.130
underwent elec-
trophilic substitution by the iron complex
10.95
. Regioselective oxidation to give a new
this case the ferrocinium ion was chosen, giving
5
-complex
10.312
allowed a second nucleophilic attack to generate the carbazole skeleton
10.133
in situ
. Further oxidation
resulted in decomplexation, aromatization of the ring to give carbazole
10.134
and some formation of
iminoquinone
10.135
.
