291
intramolecular C–H bond activation of arylamines was performed to construct carbazole and carbazolequinone derivatives (Scheme 65) and this study reports the
broad scope of oxidative biaryl coupling reactions with good yield of products [253].
Additionally, Jain et al. described the C5-H arylation of l-histidine in a regioselective manner by using aryl iodides as coupling partners (Scheme 66) and reported
good yield of N-benzylated imidazole while sustaining chirality [254]. Owing to the
broad range of biological significance of arylated amino acids embedded in peptides, arylation of amino acid was important.
Another accomplishment in the area of palladium-catalysed microwave-assisted
polycondensation was achieved by Kanbara et al. by arylation reaction between
3,4-ethylenedioxythiophene and 9,9-dioctyl-2,7-dibromofluorene (Scheme 67)
[255]. This effective protocol is found to be significant to construct π-conjugated
polymers having optoelectronic properties under microwave irradiation with short
reaction time and low Pd loading.
Microwave-assisted Pd-catalysed orthogonal regioselective C–H arylation reactions of thiazole derivatives were carried out by Wünsch and Itami [256]. These
thiazole derivatives act as potentially better σ1 receptor ligands. Regioselective arylation of thiazole derivatives was enhanced under microwave irradiation and resulted
in arylated product showed improved σ1 receptor affinity (Scheme 68).
Alkenylation of C2–H bond of the 3H-imidazo[4,5-b]pyridine via microwave
heating was first time established by Piguel et al. [257]. This reaction protocol used
combination of Pd and Cu catalysis and led to the construction of numerous
O
O
P
P
O
O
O
O
O
O
P
P
O
O
O
O
Pd
insoluble
polymer
(i)
(ii)
P
O
O
Reagents and conditions: (i) PdCl 2(NCPh)2 , DCE, reflux, 6d, 77%
(ii) PdCl 2(NCMe)2 , µv,300 W, 150
o
C, 1 h, 92%
=
O
P
O
Scheme 64 C–H activation of bis(phosphite) PCP-pincer ligands for synthesis of chiral Pdbis(phosphite) PCP-pincer complexes
100 W, 130
o C, 60 min
N
H
R 4
R 1
R 2
R 3
R 1
R 2
R 3
N
H
R 4
Pd(OAc)2 , Cu(OAc)2
DMF, µW
Scheme 65 Palladium-catalysed microwave-assisted C–H activation of arylamines
Insights into Sustainable C–H Bond Activation
intramolecular C–H bond activation of arylamines was performed to construct carbazole and carbazolequinone derivatives (Scheme 65) and this study reports the
broad scope of oxidative biaryl coupling reactions with good yield of products [253].
Additionally, Jain et al. described the C5-H arylation of l-histidine in a regioselective manner by using aryl iodides as coupling partners (Scheme 66) and reported
good yield of N-benzylated imidazole while sustaining chirality [254]. Owing to the
broad range of biological significance of arylated amino acids embedded in peptides, arylation of amino acid was important.
Another accomplishment in the area of palladium-catalysed microwave-assisted
polycondensation was achieved by Kanbara et al. by arylation reaction between
3,4-ethylenedioxythiophene and 9,9-dioctyl-2,7-dibromofluorene (Scheme 67)
[255]. This effective protocol is found to be significant to construct π-conjugated
polymers having optoelectronic properties under microwave irradiation with short
reaction time and low Pd loading.
Microwave-assisted Pd-catalysed orthogonal regioselective C–H arylation reactions of thiazole derivatives were carried out by Wünsch and Itami [256]. These
thiazole derivatives act as potentially better σ1 receptor ligands. Regioselective arylation of thiazole derivatives was enhanced under microwave irradiation and resulted
in arylated product showed improved σ1 receptor affinity (Scheme 68).
Alkenylation of C2–H bond of the 3H-imidazo[4,5-b]pyridine via microwave
heating was first time established by Piguel et al. [257]. This reaction protocol used
combination of Pd and Cu catalysis and led to the construction of numerous
O
O
P
P
O
O
O
O
O
O
P
P
O
O
O
O
Pd
insoluble
polymer
(i)
(ii)
P
O
O
Reagents and conditions: (i) PdCl 2(NCPh)2 , DCE, reflux, 6d, 77%
(ii) PdCl 2(NCMe)2 , µv,300 W, 150
o
C, 1 h, 92%
=
O
P
O
Scheme 64 C–H activation of bis(phosphite) PCP-pincer ligands for synthesis of chiral Pdbis(phosphite) PCP-pincer complexes
100 W, 130
o C, 60 min
N
H
R 4
R 1
R 2
R 3
R 1
R 2
R 3
N
H
R 4
Pd(OAc)2 , Cu(OAc)2
DMF, µW
Scheme 65 Palladium-catalysed microwave-assisted C–H activation of arylamines
Insights into Sustainable C–H Bond Activation