Using the same catalyst system, Cu/Al-HTB, the scope was extended in the case
of heterocyclic amines such as imidazole, benzimidazole, pyrazole, and morpholine
with aryl chlorides, bromides, and iodides in good to excellent isolated yields.
Selected examples are listed in Table 27. However, some of the chlorides either
participated sluggishly or were unreactive towards coupling reactions under the
same reaction conditions. Many examples of the methodology were studied for
coupling partners on both sides.
R 1
H
N
N
H
S
O
O
R 2
R 1
N
S
O
O
R 2
Cu(OAc) 2 , PhB(OH) 2
TEA, THF, 4 Ä sieves
R 3
1
2
TFA-DCM (1:1)
Scheme 16 N-Arylation of solid-supported sulfonamides with phenylboronic acid catalyzed by
Cu(OAc) 2
Neat
Cyclohexylamine
temp. 160 °C
8-9 h
Cl
FG
1. p-NO 2 = 71%
2. o-NO2 = 91%, and 90%
in 4 th cycle
3. p-CHO insitu converted
to -COOH = 89%
4. p-COOH = 88%
5. o-CN = 59%
6. p-CHO, m-Cl = 56%
Cu/Al HT catalsyt (20 wt%)
K 2 CO 3 (1.1 eq.)
H
N
FG
Scheme 15 Cu/Al LDHs-catalyzed C–N bond forming reactions beween cyclohexylamine and
chloroarenes
Neat
BnNH 2
160 °C
8-12 h
Cl
NH
Ph
FG
1. p -NO 2 = 77%;
76% in 4th cycle
2. o -NO 2 = 80%
3. p-CHO insitu converted
to -COOH = 68%
4. p-CHO, m-Cl = 69%
5. p-COOH = 46%
6. o-CN = 52%
7. p-CN = 45%
8. PhCl = no reaction
9. p-OCH 3 = no reaction
Cu/Al HT catalyt (20 wt%)
K 2 CO 3 (1.1 eq.)
FG
Scheme 14 Cu/Al LDHs-catalyzed C–N bond forming reactions beween benzylamine and chloro
arenes
150
M.L. Kantam et al.