Chemistry Reference
In-Depth Information
PR'
3
PR'
3
(OC)
3
Co
Co(CO)
3
(OC)
3
Co
Co(CO)
2
(OC)
2
Co
Co(CO)
3
4a
, PR'
3
+
R' = Ph, OMe
R
R
R
er
up to 84:16
1c
R= CMe
2
OH
1d
R= CEt
2
OH
(95:5 after recrystallization)
O
N
MeO
N-oxide
MeO
H
O
N
H
H
O
R
O
er
up to 89:11
Brucine
N
-oxide (
4a
)
H
2c/2d
3c/3d
Scheme 6.5
Desymmetrization of dicobalt-alkyne clusters driven by a chiral
N
-oxide.
with molybdenum allowed Christie
et al.
to obtain the diastereomeric Co-Mo clusters
5a
and
5a'
from the cobalt hexacarbonyl complex of menthyl propargyl ether (
1a
).
Separation of these clusters also yielded diastereomeric products (the cyclopentenones
3a
and
3a'
, respectively) with opposite configuration at the newly created stereocenters
(Scheme 6.6).
(OC)
3
Co
Co(CO)
3
(OC)
3
Co
Mo(CO)
2
(OC)
2
Mo
Co(CO)
3
Na[CpMo(CO)
3
]
+
THF
*R
*R
*R
5a
5'a
1a
°
C
°
C
70
70
°
C
70
O
O
H
O
H
R*
*R
R*
H
H
3a
(dr ~ 1:1)
3'a
3a
Opposite configuration at the cyclopentenone core
Scheme 6.6
Desymmetrization of dicobalt-alkyne through iso-lobular replacement with
molybdenum.
