Chemistry Reference
In-Depth Information
(OC)
3
Fe
(OC)
3
Fe
CH
3
CO BF
4
Fe(CO)
5
,
h
ν
1
.
1
.
4
1
4
4
CH
3
O
(OC)
3
Fe
1. MeO
2. silica
10.45
CH
3
O
Scheme 10.13
Fe(CO)
3
Fe(CO)
3
AlCl
3
COCl
O
10.47
10.46
Scheme 10.14
Fe(CO)
3
18e
-H
+
Fe(CO)
3
H
+
Fe(CO)
3
Fe(CO)
3
10.51
16e
Fe(CO)
4
+ CO
10.48
10.49
10.50
18e
10.52
Scheme 10.15
10.1.2 Nucleophilic Attack
The iron diene complexes may also be attacked by strong nucleophiles, such as the anion of acetonitrile
(Scheme 10.16).
19
The kinetic position of attack on the cyclohexenyl complex
10.1
is at C2 giving an
2
-
complex
10.53
. If the products are exposed to CO at low temperature, CO insertion occurs. The intermediate
10.54
formed in this way is clearly similar to those formed by alkylation-CO insertion reactions of Collman's
reagent (Section 4.5.1). Addition of an alkylating agent such as methyl iodide causes alkylation of iron, which
is followed by reductive elimination. The cyanomethyl group and the acetyl group of the product
10.56
are
trans
because the original nucleophilic attack was
trans
to iron, while alkylation was on iron. On the other
hand, if the kinetic addition product is allowed to warm up, the thermodynamic
1
,
3
-allyl complex
10.57
is
obtained. An acidic quench then gives a mixture of alkenes,
10.58
and
10.59
.
