160
O
R 2
H
R 3
H
Pd/C (5 mol% Pd)
DMA, N 2 , 140 °C
O
R 2
R 3
R 1
R 1
+ H 2
18
21
O
O
O
O
O
EtO
CN
OMe
O
21a, 77 %
21b, 87 %
21c, 74 %
21d, 70 %
21e, 90 %
21f, 66 %
Scheme 5.8 Synthesis of benzofurans from ortho-alkenylphenols through Pd(0)-catalyzed C-H
bond functionalization
NH
OEt
+
N
O
O
Cp
* Co(CO)I 2 (10 mol %)
AgOTf (20 mol %)
N
N
OEt
O
O
DCE, 100 °C, 11 h
9
10
11
[Cp
* Co][OTf ] 2
Cp
* Co(CO)I 2
AgI
AgOTf
NH
OEt
HOTf
Co
NH
OEt
Cp
*
OTf
N
O
O
Co
NH
N
EtO
O
O
Cp
*
H
TfO
Cp
* Co(I)
2HOTf
H 2
NH
OEt
N
O
O
N
N
OEt
O
O
C-H
activation
insertion
hydrogen
evolution
Michael
addition
12
9
14
13
10
15
16
11
17
elimination
Scheme 5.7 Cobalt-catalyzed spirocycle synthesis
W. Ai et al.