952
D. J. Morris et al. / Tetrahedron Letters 48 (2007) 949–953
3 mol% Pd(PhCN)2
4 mol% CuI
3 mol% Ligand,
accessible ligands can be effective in coupling reactions,
and that the structure of the ligand has a dramatic effect
on its performance in the reactions investigated.
X
X
H
I
HN(iPr)2
+
dioxane, 50 oC, 6 h.
Ph
Ph
14 X=OMe
15 X=NO2
Acknowledgements
We thank Rhodia Consumer Specialities Ltd for gener-
ous financial support of this project (to D.J.M.), the use
of the EPSRC Chemical Database Service at Dares-
bury19 and J. C. Bickerton of the Warwick MS service.
We also acknowledge the generous gift of palladium
reagents by Johnson-Matthey limited.
Scheme 5.
Table 5. Pd-Catalysed Sonogashira reaction to form 14 (% conversion)
Ligand
T/h
4.0
2.0
6.0
3a
4a
5a
6a
7a
8a
3b
4b
5b
7b
8b
3c
100
100
<1
—
100
100
100
65
52
100
93
100
21
75
100
100
<1
—
100
100
100
85
76
100
97
100
47
83
100
100
<1
—
100
100
100
92
76
100
99
100
33
90
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T/h
4.0
2.0
6.0
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65
93
—
94
100
1
82
0
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93
97
—
100
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100
96
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<1
39
2
100
74
100
86
0
100
100
100
100
<1
0
5c
7c
8c
12
13
PPh3
0
100
0
100
100