benzylamine. Bromoarenes react at 100
C in DMF to give good yields of products
(Table 24, entries 16–22). The recovered catalyst, after washing with acetone
followed by drying at 80
C, was used in the next run. Almost consistent activity
was observed over five cycles in the reaction of iodobenzene with imidazole
(Table 24, entry 1). The difference between the copper content of the fresh catalyst
and the used catalyst (fifth cycle) is only 2.4%.
N
N
NH
H
N
HN
N
N
NH
H
N
HN
CuI
d+
d+
Scheme 13 Possible
structure of PANI-Cu
Table 24 N-Arylation of N(H)-heterocycles and benzylamines with aryl halides using PANI-Cu
a
Entry
Aryl halide
N(H)-heterocycle/amine
Time (h)
Yield (%)
1
C 6 H5-I
Imidazole
12
92, (90, 89, 90, 87)
b
2
4-Me-C 6 H 4 -I
Imidazole
16
85
3
4-MeO-C 6 H 4 -I
Imidazole
18
82
4
4-MeCO-C 6 H 4 -I
Imidazole
8
98
5
4-NO 2 -C 6 H 4 -I
Imidazole
6
95
6
2-Me-C 6 H 4 -I
Imidazole
24
65
7
C 6 H 5 -I
Benzimidazole
16
84
8
C 6 H 5 -I
Pyrazole
14
92
9
C 6 H 5 -I
Pyrrole
12
88
10
C 6 H 5 -I
Benzylamine
15
90
11
C 6 H 5 -I
4-Methylbenzylamine
12
92
12
C 6 H 5 -I
4-Methoxybenzylamine
10
90
13
C 6 H 5 -I
Dibenzyl amine
24
0
14
c
C 6 H 5 -Br
Imidazole
15
90 (80, 65)
b
15
c
4-MeCO-C 6 H 4 -Br
Imidazole
10
95
16
c
4-NO 2 -C 6 H 4 -Br
Imidazole
8
90
17
c
4-Me-C 6 H 4 -Br
Imidazole
18
90
18
c
4-MeO-C 6 H 4 -Br
Imidazole
30
88
a
Reaction conditions: aryl halide (1 mmol), amine (1.2 mmol), PANI-Cu (2.5 mol%), Cs 2 CO 3
(3 mmol), CH 3 CN (2 mL), 80
C, N 2 atmosphere, isolated yield
b
Yields after consecutive cycles
c
DMF used as solvent and reaction temperature 100
C
148
M.L. Kantam et al.