Chemistry Reference
In-Depth Information
Tab l e 7 . 4
A summary of Ti, Ru, Ni, Pd, Ir catalysts and their activities.
Inter-
Intra-
p
(CO)
Entry
PKR
PKR
Catalyst system
[atm]
TON
a
Ref.
√
[Cp
2
Ti(CO)
2
]
1
X
1.22
(9-19)
58,59
√
[Ru
3
(CO)
12
]
2
X
10-15
(16-7)
66
√
3
X
[RuCo
3
(CO)
12
]X X
=
NEt
4
, bmim, H
8
(32-46)
69
√
4
X
Ni(COD)
2
+
L
b
0
(8-17)
71
Ph
Ph
Ph
Ph
N
N
L =
√
5
X
PdCl
2
-tmtu
1
(2-4)
72
S
Me
Me
Me
Me
N
N
tmtu =
√
6
X
PdCl
2
-tmtu
+
LiCl
1
(3-30)
74
√
7
X
[Ir(COD)Cl]
2
+
Phox
2.2
(9-11)
54
O
PPh
2
N
Phox
=
√
(
S
)-tol-BIANP
c
8
X
[Ir(COD)Cl]
2
+
1
(2-9)
50
√
(
S
)-tol-BIANP
d
9
X
[Ir(COD)Cl]
2
+
0
(2-5)
51
√
(
S
)-BINAP
e
10
X
[Ir(COD)Cl]
2
+
0
(2-7)
53
a
TONs calculated with respect to the number of moles of metals, TONs in parentheses are turnover numbers of in-
tramolecular PKR
b
Insertion of 2,6-dimethlphenyl isocyanide followed by hydrolysis to obtain desired cyclopentenones
c
Under 1atm (AR:CO
8:2) atmosphere
d
Using cinnamaldehyde as CO source
e
Using nonylaldehyde as CO source
=
7.7 Tandem Reactions and Miscellaneous (other than Co complex)
The Pauson-Khand-type reactions have been successfully developed as effective methods
to construct cyclopentenone frameworks for generating many pharmaceutically useful and
scientifically interesting molecules.
76, 77
Based on the principle of atom economy, tandem
reactions has become one of the hot topics of recent decades. In 2000, Jeong and co-workers
showed a bimetallic catalyst comprising of [Pd
2
(dba)
3
(CHCl
3
)] and [RhCl(CO)(dppp)]
2
.
The alkyne malonate and allyl acetate were converted into the desired cyclopentenones in
a tandem manner, in up to 92% yield (Scheme 7.44).
78
O
Ph
Ph
[Pd
2
(dba)
3
(CHCl
3
)] / RhClCO(dppp)]
2
(EtO
2
C)
2
HC
EtO
O
EtO
BSA, dppb, toluene, 110
°
C, 25 h
+
O
CO (1 atm)
OAc
92% yield
Scheme 7.44
A bimetallic catalyst system for PKR.
