100
Various alkynes can be coupled with diphenylmethane derivatives using CuOTftoluene complex as the catalyst and DDQ as the oxidant (Scheme 4.4) [1]. Various
aromatic alkynes are suitable substrates with good yields; aliphatic alkynes are not
efficient.
R
1 H +
R
2
H
R
1 R
2
R
1 H +
R
2
H
Oxidant
T.M. catalyst
R
1 R
2
Transtion-metal-free
Oxidant
- "H 2 "
- "H 2 "
R
1 H +
R
1 XR 2
R
1 H +
R 2
HX
T.M. catalyst
Oxidant
R 1 XR 2
Transtion-metal-free
Oxidant
- "H 2 "
- "H 2 "
R 2
HX
X = O, N, P, etc.
Scheme 4.1 Oxidative
C-C and C-X (Hetero)
couplings
C sp3 H +
C sp
H
Oxidant
- "H 2 "
C sp3
C sp
C sp3 H +
C sp2
H
Oxidant
- "H 2 "
C sp3
C sp2
C sp3 H +
C sp3
H
Oxidant
- "H 2 "
C sp3
C sp3
C sp2 H +
C sp2
H
Oxidant
- "H 2 "
C sp2
C sp2
Scheme 4.2 Oxidative
radical C-C couplings
C
H 2
C
H 2
N
R
1
R
2
H
CuBr/NBS
CH 3 CN, 80 o C, 6 h
+ H
R
3
C
H 2
C
H 2
N
R
1
R
2
R 3
R
3 = Ar, alkyl groups
Scheme 4.3 Alkynylation of tertiary amines
W. Liu