4
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cyclohexyl
I
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90
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13
4-OMe
4-OMe
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15
10
50
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14c
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16
H
4-NO2
4-Me
H
n-butyl
n-butyl
C6H5
I
8
15
7
55
30
50
35
40
20
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I
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Br
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19e
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15
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a
Reaction conditions: aryl halide (0.5 mmol), acetylene (0.6 mmol),
Pd(OAc)2 (1 mol%), A4 (2 mol%), K2CO3 (1.5 mmol), EtOH (4 mL) at room
temperature (rt) unless otherwise mentioned.
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3341-3344.
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b Isolated yield.
c, d, e, f Reactions were performed at 600C.
32. Valishinaa, E. A.; Guedes da Silva, M. F. C.; Kinzhalov, M. A.;
Timofeeva, S. A.; Buslaevaa, T. M.; Haukka, M.; Pombeiro, A. J.
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Conclusions
In conclusion, we have developed a convenient methodology
for the Sonogashira cross-coupling reaction with Pd based
catalytic system. The reaction proceeds in absence of copper and
amine. The main perspective of our current catalytic system is the
use of easily available and cheap laboratory chemical 4-
aminobenzoic acid (PABA). The reaction seems to be a
prominent protocol for the Sonogashira coupling because of the
use of low cost and effective additive for the catalytic system,
which at the same time avoids toxic solvent.
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Acknowledgments
41. Sharma, M.; Kumari, N.; Das, P.; Chutia, P.; Dutta, D. K. J. Mol.
Catal. A: Chem. 2002, 188, 25-35.
S.K.D. thanks UGC, New Delhi for Rajiv Gandhi National
Fellowship (RGNF).
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References and notes
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49. General experimental procedure for the Sonogashira cross-
coupling reaction: A round bottom flask was charged with aryl
halide (0.5 mmol) and terminal acetylene (0.6 mmol). To the
mixture, Pd(OAc)2 (1 mol%), A4 (2 mol%) and K2CO3 (1.5 mmol)
were added. The reaction mixture was stirred at room temperature
in EtOH (4 mL) for the mentioned time. The formation of the
product was confirmed by monitoring the TLC. The reaction
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extracted layer was dried over Na2SO4 and concentrated in rotary
evaporator. The crude product was purified by column
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desired product. The pure products were confirmed by 1H and 13C
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Supplementary Information
Supplementary information can be found in the
16. Yi, J.; Lu, X.; Sun, Y. -Y; Xiao, B.; Liu, L. Angew Chem, Int. Ed.
2013, 52, 12409-12413.