Chemistry Reference
In-Depth Information
Table 31 Suzuki-Miyaura-
type coupling of arylboronic
acids with 2-bromothiophene
[
171
]
R
1
R
2
Ratio(substrate/catalyst)
a
Yield (%)
H
H
100000:1
88
COMe
H
1000:1
90
OMe
H
1000000:1
85
H
Me
100000:1
89
a
Substrate/catalyst ratio based on aryl halide
Ar
1
B(OH)
2
(6.0 equiv),
5 mol% Pd(OAc)
2
,
10 mol%
,
K
3
PO
4
(8.0 equiv),
1,4-dioxane/toluene,
100 °C, 12 h
133
PCy
2
Ar
1
Ar
1
Br
Br
MeO
OMe
Ar
1
Ar
1
Br
Br
70-81%
S
S
132
134
Ligand
133
Scheme 54 Synthesis of tetraarylthiophenes [
348
]
Table 32 Synthesis of tetraarylthiophenes [
348
]
Ar
1
Solvent
Yields (A) (%)
Yields (B) (%)
Ph
toluene
37
70
4-MeOC
6
H
4
1,4-dioxane
94
2-MeOC
6
H
4
1,4-dioxane
38
65
1-naphthalenyl
toluene
65
4-MeC
6
H
4
toluene
87
4-ClC
6
H
4
toluene
89
4-FC
6
H
4
toluene
93
2-thienyl
toluene
-
81
Suzuki-Miyaura Cross-Coupling in the Presence of a Palladium/Tetraphosphine
Catalyst
2-Arylthiophenes 131 can be prepared by the Suzuki-Miyaura cross-coupling
reaction of 2-bromothiophene 107 with different arylboronic acids 130 in the
presence of a Tedicyp 66 palladium complex (Scheme
53
, Table
31
)[
171
]. The
arylation takes place with only 0.1-0.0001 mol% catalyst. The cross-couplings of
thienylboronic acids and aryl halides under the same reaction conditions result in
slightly poorer yields.
Suzuki-Miyaura Cross-Coupling in the Presence of a Biarylmonophosphine Ligand
Another efficient approach for the arylation of halothiophenes is the Suzuki-
Miyaura cross-coupling reaction of tetrabromothiophene 132 with different
arylboronic acids (Scheme
54
, Table
32
)[
348
]. One possibility to prepare fourfold
