Chemistry Reference
In-Depth Information
than those of the Co
4
(CO)
12
-catalyzed reaction, and intra- and intermolecular reactions
proceeded to give the corresponding cyclopentenones (Scheme 3.23).
C
(OC)
3
Co
Co(CO)
3
Co
(CO)
3
R
1
R
1
(2 mol%)
R
2
Z
Z
O
Toluene, 120 °C, CO (7 atm)
n
R
2
Z = C(CO
2
Et)
2
,R
1
=H,R
2
= H (n = 1): 98%
Z = C(CO
2
Et)
2
,R
1
=Ph,R
2
=H(n=1):91%
Z = C(CO
2
Et)
2
,R
1
=
n
-Bu, R
2
=H(n=1):89%
Z = C(CO
2
Et)
2
,R
1
=H,R
2
=Me(n=1):89%
Z = C(CO
2
Et)
2
,R
1
=H,R
2
= H (n = 2): 97%
Z=CH
2
,R
1
=Ph,R
2
= H (n = 1): 98%
Z=NTs,R
1
=H,R
2
= H (n = 1): 96%
Z=NTs,R
1
=Ph,R
2
=H(n=1):91%
O
R
The same as above
R
+
With norbornene
R=Ph: 98%
R=
n
-C
8
H
17
94%
With norbornadiene
R=Ph: 89%
Scheme 3.23
Later, Krafft reported a Co
4
(CO)
12
-catalyzed reaction under much milder reaction con-
ditions (70
◦
C, CO (1 atm)) by using excess amounts of cyclohexylamine (Scheme 3.24).
24
1,6-enynes were transformed into bicyclic enones in a good yield.
R
Co
4
(CO)
12
(5-10 mol%)
R
CyNH
2
(30-60 mol%)
Z
Z
O
DME, 70 °C, CO (1 atm)
( )
( )
n
n
Z = C(CO
2
Et)
2
, R = n-Pr (n = 1): 94%
Z = C(CO
2
Me)
2
, R = H (n = 2): 92%
Z = NTs, R = H (n = 1): 88%
Z = NTs, R = n-Pr (n = 1): 81%
Z = CHCH
2
OTBS, R = H (n = 1): 85%
Z = CHCH
2
OTBS, R = n-Pr (n = 1): 91%
Co
4
(CO)
12
(10 mol%)
O
Ph
Ph
CyNH
2
(60 mol%)
+
DME, 70 °C, CO (1 atm)
97%
Scheme 3.24
