22
2.3.3.2 Cross-Coupling
Zhang and co-workers reported the first palladium-catalyzed oxidative crosscoupling of arylsilanes and arylboronic acids employing 1,4-benzoquinone as
ArZnCl +
PdCl 2 (CH 3 CN) 2 (5 mol%)
DPEphos, Desyl Chloride
THF, r.t. - 60 o C, 5 h
R 3 In
Ar
R
Cl
Cl
Cl
Cl
Br
Br
Ph
Br
Br
Br
Br
Br
Br
Ph
MeO
MeO
75%
66%
90%
57%
7 7%
85%
70%
81%
84%
82%
9 0%
81%
3
7
11
3
7
3
7
11
Scheme 2.24 Pd-catalyzed oxidative cross-coupling of arylzinc and alkylindium reagents
O
O
R 3
SnBu 3
R 2
R 1
PdCl 2 (PPh 3 ) 2 (10 mol%)
CuI, 1,4-benzoquinone
air, r.t., 40 min
O
O
O
O
R 1
R 1
R 2
R 3
R 2
R 3
Scheme 2.25 Pd-catalyzed oxidative homo-coupling of stannylquinones
ArB(OH) 2
(SIPr)Pd(OAc) 2 (H 2 O)
(1-3 mol%)
1,4-benzoquinone
MeOH, r.t., 24 h
Ar Ar
N
N
i Pr
i Pr
i Pr
i Pr
SIPr
Scheme 2.26 Palladium N-heterocyclic carbine complex-catalyzed oxidative homo-coupling of
arylboronic acids
H. Zhang