Chemistry Reference
In-Depth Information
O
O
Co(CO)
3
Me
Co(CO)
4
Me
4.214
4.213
Et
3
N
CH
2
NO
2
O
O
Me
Me
NO
2
4.215
4.216
Scheme 4.77
O
O
1.
O
Me
Co(CO)
4
•
NHTs
2. Et
3
N
NHTs
Ts
Co(CO)
3
4.217
4.218
4.219
Scheme 4.78
O
O
(OC)
3
Fe
4.220
O
Fe
2
(CO)
9
4.222
HO
OH
4.221
Scheme 4.79
OH
Fe
2
(CO)
9
O
(OC)
3
Fe
OH
4.223
O
4.224
Scheme 4.80
4.5.2 Ferrilactones and Ferrilactams
Treatment of vinyl epoxides
4.220
with metal-carbonyl complexes yields cyclic lactone complexes, which
incorporate an allyl ligand derived from epoxide opening (Scheme 4.79).
85
The most widely used are the
ferrilactones
4.222
, prepared using either iron pentacarbonyl or diiron nonacarbonyl.
86
These complexes
may also be prepared from other starting materials, such as diols
4.221
87
and derivatives.
88
The particular
advantage of the epoxide route is that the preparation of the vinyl epoxide starting materials can be done
through the Sharpless asymmetric epoxidation of allylic alcohols. In this way, the complexes can be prepared
with very high enantiomeric excess. An advantage of the diol route is that it also allows access to the isomeric
series of complexes
4.224
, “isoferrilactones”, in which the methylene-oxy bridge is attached to the central
carbon of the allyl unit, rather than a terminal carbon (Scheme 4.80).
