Chemistry Reference
In-Depth Information
bis(oxime) in combination with CuCl provides an effective catalyst for the
arylation of azoles with aryl iodides and bromides in water at 100 1C.
66
Amides and amino acids are a third class of privileged ligands for copper-
catalyzed coupling reactions. Copper(II) oxide in combination with an oxa-
lodihydrazide gives an effective catalyst for the selective monoarylation of
ammonia in water-TBAB with a variety of aryl iodides and bromides.
67
Under microwave heating, this system catalyzes the coupling of aryl
bromides and iodides with primary amines and anilines at 140 1C. Pyrrole-2-
carbohydrazide is another effective ligand for the aqueous-phase copper-
catalyzed arylation of amines.
68
The reaction can be accomplished within
5 min at 130 1C under microwave heating. Copper(I) iodide in combination
with lithium picolinate has been applied to the hydroxylation of aryl iodides
and bromides in water in the presence of TBAF at 130 1C.
69
The water-soluble copper-salen complex 27 is a recyclable catalyst for the
arylation of nitrogen nucleophiles in water. The catalyst promotes the ary-
lation of azoles in water with TBAB at 100 1C (Scheme 14.24).
70
The catalyst
solution was used for four reaction cycles with nearly identical yields for
each cycle. Complex 27 is also effective for the arylation of primary aliphatic
amines
71
and the selective monoarylation of ammonia in water.
72
D
-Glucosamine is an effective and environmentally benign ligand for the
copper-catalyzed monoarylation of ammonia in water.
73
D
-Glucosamine
provides a more active catalyst than a range of other carbohydrates and
more traditional ligands, such as phenanthroline or ethylenediamine. The
Cu/
D
-glucosamine catalyst was also applied to the monoarylation of
hydroxides to give phenols.
74
Given the low cost and relatively low toxicity of iron, it is a desirable al-
ternative to palladium or even copper as a catalyst. Recent research has
shown that iron can be an effective catalyst,
75
although in some cases metal
impurities appear to be the true active species.
76
Iron in combination with
DMCDA
77
or DMEDA
78
has been shown to be an effective catalyst for the
arylation of azoles and other nitrogen nucleophiles. By using the more
hydrophilic ammonium-substituted bipyridine ligand 18, recycling of an
iron catalyst was achieved in the arylation of thiols (Scheme 14.25).
79
Using
N
Br
N
27
(2 mol %)
TBAB, NaOH, H
2
O
100 °C, 12 h
N
+
N
N
Cu
H
N
N
NaO
3
S
O
O
SO
3
Na
88%
27
Scheme 14.24
Cycle (% yield)
FeCl
3
6H
2
O (10 mol %)
18
(0, 10 mol %)
KOH, H
2
O, 100 °C, 24 h
18
0 mol %
10 mol %
S
1
55
92
2
41
90
3
24
93
4
11
86
5
0
80
6
0
74
I
HS
+
O
2
N
O
2
N
Scheme 14.25
Search WWH ::
Custom Search