Chemistry Reference
In-Depth Information
Scheme 28 Suzuki-
Miyaura coupling reactions
of 2-thienylboronic acids
R
1
R
1
R
2
X, "Pd(0)", base
R
2
B(OH)
2
S
40-96%
S
62
63
Table 16 Suzuki-Miyaura coupling reactions of 2-thienylboronic acid
R
1
R
2
X
Conditions
Yield (%)
Ref.
H
ClC
4
F
8
CH
2
CH
2
I
Pd(PPh
3
)
4
, NaHCO
3
68
[
162
]
H
C
10
F
21
CH
2
CH
2
I
Pd(PPh
3
)
4
, NaHCO
3
58
[
162
]
H
I
PdCl
2
(PPh
3
)
2
,Na
2
CO
3
82
[
163
]
X
O
(4-Me
2
NPh)CH=CH
O
X
H
4-ClC
6
H
4
CO
Cl
Pd(PPh
3
)
4
,Cs
2
CO
3
78
[
164
]
H
MeCO
Cl
Pd(PPh
3
)
4
,Cs
2
CO
3
47
[
164
]
H
Br
Pd(PPh
3
)
4
,Na
2
CO
3
96
[
165
]
O
X
MeO
MeO
O
H
3-thienyl
Br
Pd(PPh
3
)
4
,Na
2
CO
3
40-70
[
147
]
H
2-pyridyl
Br
Pd(PPh
3
)
4
,Na
2
CO
3
67
[
166
]
55
a
H
5-pyrimidinyl
Br
Pd(PPh
3
)
4
,K
2
CO
3
[
52
]
75
a
5-CHO
4-Ph
2
NC
6
H
4
Br
Pd(dppf)Cl
2
,K
2
CO
3
[
42
]
51
b
H
4-Ph
2
NC
6
H
4
Br
Pd(PPh
3
)
4
, NaHCO
3
[
42
]
65
b
5-C
10
H
21
Br
Pd(PPh
3
)
4
,Na
2
CO
3
[
161
]
X
S
S
H
Br
Pd(dppf)Cl
2
,K
2
CO
3
87
[
158
]
X
N
N
a
Microwave assisted
b
With 2-thienylboronic acid pinacol ester
compounds [
158
], which are valuable building blocks found in biologically active
molecules, or the postmodification of polycyclic aromatic hydrocarbons, e.g., the
construction of cyclopenta[
hi
]aceanthrylenes bearing thiophene-based functionali-
ties on positions 2 and 7 [
159
]. Even oligothiophenes can be synthesized, for
instance, by the polymer-supported coupling of thienylboronic acids with
iodothiophenes [
160
,
161
]. Next to the formation of aryl- and alkylthiophenes,
the versatility of the Suzuki-Miyaura reaction is also displayed in the couplings of
thienylboronic acids with diverse functional groups such as acid chlorides giving
rise to ketones (Scheme
28
, Table
16
)[
164
] or amines/aldehydes forming
aminomethylthiophenes [
167
,
168
]. The reaction proceeds via the three-step cata-
lytic cycle according to the general mechanism of metal-catalyzed cross-coupling
reactions. However, the transmetallation step requires the activation of the boron by
