Chemistry Reference
In-Depth Information
Me
3
N
NMe
3
Br
-
Pd(NH
3
)
2
Cl
2
(0.01 mol %)
18
(0.01 mol %)
NaOH, H
2
O, 120 °C, 6 h
Br
Br
-
(EtO)
3
Si
+
N
N
MeO
92%
18
MeO
Scheme 14.15
F
Br
(HO)
2
B
N
N
19
(0.01 mol %)
K
2
CO
3
, H
2
O
120 °C, 2 h
Cl
NMe
3
Cl
-
+
Pd
O
F
Cl
O
N
19
92%
Scheme 14.16
i-
Pr
i-
Pr
NaO
3
S
N
N
SO
3
Na
Pd
i-
Pr
i-
Pr
Cl
Cl
(HO)
2
B
20
(0.01 mol%)
K
2
CO
3
, TBAB, H
2
O, 75 °C, 5 h
Br
+
95%
Scheme 14.17
OH
O
N
O
21
(0.01 mol %)
Cy
2
NMe, H
2
O
120 °C, 3 h
I
O
t
-Bu
+
Pd
O
t
-Bu
Cl
Cl
94%
Cl
HO
2
21
Scheme 14.18
ligands in combination with PdCl
2
(0.01 mol%) at 80 1C in water
(Scheme 14.17).
47
Recycling of the catalyst was explored, but the conversion
to product degraded rapidly after the second cycle.
EDTA is an inexpensive water-soluble ligand. Palladium (0.1 mol%)
in combination with EDTA provides an effective catalyst for the Suzuki
coupling of aryl iodides and bromides in water.
48
Tetrakis(2-hydro-
xyethyl)ethylenediamine complexed to palladium affords an active catalyst
for aqueous-phase Suzuki coupling of aryl bromides.
49
Up to 100 000 turn-
overs were achieved with activated aryl bromides at 100 1C.
Oxime palladacycles were the first systems that allowed cross-coupling of
aryl chlorides in aqueous solvent systems.
50
The palladium complex derived
from 4
0
-hydroxyacetophenone oxime (21, Scheme 14.18) catalyzes the Suzuki
coupling of aryl bromides and chlorides at 100 1C in water-TBAB in good
yields.
51
This catalyst system is also effective in the Heck
52
and Hiyama
coupling of aryl halides.
53
A related benzothiazole oxime palladacycle (22,
Scheme 14.19) gave a highly active catalyst for the Suzuki and Heck
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