Chemistry Reference
In-Depth Information
Tab l e 9 . 4
Substrate
Product
Yield (%)
H
Z
Z
O
H
Z
C(CO
2
Et)
2
NBoc
NTs
98
90
94
O
+
R
R
R
Ph
n-Bu
54
43
recycled five times. However, for internal enyne and heteroatom-bridged enynes a higher
CO pressure of 10 atm is required. The
CNC
is also effective for intermolecular PKR under
15 atm of CO.
9.3.2.2
CNC
-catalyzed one-pot reductive PKR
The sequential reaction of PKR and hydrogenation is a useful method for the synthesis
of natural products.
30
The known reductive PKRs, however, have used stoichiometric or
substoichiometric amounts of cobalt complexes.
30
The use
CNC
as a bifunctional catalyst
in the reductive PKR in a one-pot reaction was thus a meaningful. Under the optimum
conditions (
CNC
(0.1 g, 12 wt%), substrate (0.48 mmol), THF, 130
◦
C, 5 atm CO, 5 atm
H
2
, 18 h), the desired products were successfully synthesized by
CNC
through the in-
tramolecular reductive PKRs, but the yields of the intermolecular version were moderately
low (Scheme 9.8 and Table 9.4).
H
CNC
Z
Z
O
5 atm CO, 5 atm
130
°
C, 18 h, THF
H
2
H
Scheme 9.8
