Table 4 Influence of base, solvent and catalyst on the Heck coupling of 4-bromoacetophenone with acrylic acid ethyl estera
Entry
Catalyst (mol%)
Base
T/◦C
Solvent
Yieldb (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21c
2c (0.1)
2c (0.1)
2c(0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
2c (0.1)
3 (0.1)
2d (0.1)
2e (0.1)
2f (0.1)
2g (0.1)
1c (0.05)
1c/PCy3
Et3N
CsF
KF
KOAc
K3PO4·3H2O
Na2CO3
K2CO3
Cs2CO3
NaH
140
140
140
140
140
140
140
140
140
140
140
110
110
140
140
140
140
140
140
140
140
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
Dioxane
Toluene
Xylene
DMF
DMF
DMF
DMF
DMF
DMF
DMF
90.8
89.9
87.2
80.7
72.5
55.1
52.3
23.9
34.2
18.3
20.2
75.2
88.9
89.9
85.3
75.2
81.6
80.7
79.8
53.2
66.1
KtOBu
NatOBu
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
a Reaction conditions: 4-bromoacetophenone (0.5 mmol), acrylic acid ethyl ester (0.75 mmol), base (0.75 mmol), solvent (3 mL), 11 h. b Isolated yields
(average of two experiments). c 0.05 mol% 1c, 0.3 mol% PCy3.
5
5
1
=
[PdCl{[(g -C5H5)]Fe[(g -C5H3)CH NCy]}(PCy3)], 2c. Red
solid, yield 80.4%. Found: C, 58.56; H, 7.61; N 1.87. Calc.
for C35H53ClFeNPPd: C, 58.67; H, 7.46; N, 1.95%. Mp: 196–
(m, 15H, PCy3), 1.27 (m, 9H, PCy3). 31P{ H} NMR (162 MHz,
CDCl3): d 46.89. MS-ESI+: m/z 766.3 (M+ − Cl).
◦
−1
=
197 C. IR (KBr, cm ): 2928, 2852, 1609 (C N), 1445, 1362,
1224, 1107, 1002. 1H NMR (400 MHz, CDCl3): d 8.01 (br s, 1H,
–CH N), 4.52 (s, 1H, C5H3), 4.39 (br s, 2H, C5H3), 4.25 (m,
5
5
=
[PdCl{[(g -C5H5)]Fe[(g -C5H3)C(CH3) NC6H4-4-Cl]}(PCy3)],
2f. Red solid, yield 76.3%. Found: C, 52.40; H, 6.09; N 1.54.
Calc. for C36H48Cl2FeNPPd·CH2Cl2: C, 52.66; H, 5.97; N, 1.66%.
=
overlapped with C5H5, 1H, NCHC5H10), 4.20 (s, 5H, C5H5), 2.54
(m, 3H, P(CHC5H10)3), 2.34 (m, 1H, NCy), 2.02 (m, 7H, 6 PCy3
+ 1 NCy), 1.78 (m, 17H, 15 PCy3 + 2 NCy), 1.28 (m, 15H, 9 PCy3
◦
−1
=
Mp: 257 C (decomp.). IR (KBr, cm ): 2928, 2851, 1579 (C N),
1
1446, 1364, 1224, 1086, 1006. H NMR (400 MHz, CDCl3): d
+ 6 NCy). 31P{ H} NMR (162 MHz, CDCl3): d 45.33. MS-ESI+:
1
7.31 (d, J = 8.2 Hz, 2H, C6H4), 6.89 (d, J = 8.2 Hz, 2H, C6H4),
4.54 (s, 1H, C5H3), 4.45 (s, 1H, C5H3), 4.42 (s, 1H, C5H3), 4.22 (s,
5H, C5H5), 2.51 (m, 3H, P(CHC5H10)3), 2.06 (m, 6H, PCy3), 2.03
m/z 680.3 (M+ − Cl).
5
5
1
(s, 3H, CH3), 1.72 (m, 15H, PCy3), 1.28 (m, 9H, PCy3). 31P{ H}
=
[PdCl{[(g -C5H5)]Fe[(g -C5H3)C(CH3) NC6H4-4-OCH2CH3]}-
(PCy3)], 2d. Red solid, yield 78.2%. Found: C, 54.68; H, 6.54;
N 1.51. Calc. for C38H53ClFeNOPPd·CH2Cl2: C, 54.88; H, 6.50;
NMR (162 MHz, CDCl3): d 47.56. MS-ESI+: m/z 722.3 (M+ −
Cl).
◦
N, 1.64%. Mp: 262 C (decomp.). IR (KBr, cm−1): 2928, 2850,
1
=
1583 (C N), 1506, 1468, 1447, 1238, 1106, 1050, 1003. H NMR
5
5
=
(400 MHz, CDCl3): d 6.85 (m, 4H, C6H4), 4.58 (s, 1H, C5H3), 4.47
(br s, 2H, C5H3), 4.28 (s, 5H, C5H5), 4.01 (m, 2H, –OCH2CH3),
2.51 (m, 3H, P(CHC5H10)3), 2.04 (m, 6H, PCy3), 2.00 (s, 3H,
CH3), 1.71 (m, 15H, PCy3), 1.40 (t, J = 6.8 Hz, 3H, –OCH2CH3),
[PdCl{[(g -C5H5)]Fe[(g -C5H3)C(CH3) NC6H4-2-Cl]}(PCy3)],
2g. Red solid, yield 72.6%. Found: C, 52.32; H, 5.98; N 1.54.
Calc. for C36H48Cl2FeNPPd·CH2Cl2: C, 52.66; H, 5.97; N, 1.66%.
◦
−1
=
Mp: 259 C (decomp.). IR (KBr, cm ): 2928, 2851, 1579 (C N),
1.27 (m, 9H, PCy3). 31P{ H} NMR (162 MHz, CDCl3): d 46.58.
1
1
1459, 1321, 1226, 1107, 1003. H NMR (400 MHz, CDCl3): the
MS-ESI+: m/z 732.3 (M+ − Cl).
ratio of two isomers is 1.14 : 1. d 7.42 (d, J = 7.8 Hz, 1H, C6H4),
7.39 (d, J = 7.8 Hz, 1H, C6H4), 7.30 (t, J = 7.5 Hz, 1H, C6H4),
7.24 (t, J = 7.5 Hz, 1H, C6H4), 7.12 (t, J = 7.6 Hz, 2H, C6H4),
7.03 (d, J = 7.6 Hz, 1H, C6H4), 6.89 (d, J = 7.6 Hz, 1H, C6H4),
4.56 (s, 2H, C5H3), 4.49 (s, 1H, C5H3), 4.43 (m, 2H, C5H3), 4.39
(s, 1H, C5H3), 4.32 (s, 5H, C5H5), 4.25 (s, 5H, C5H5), 2.49 (m, 6H,
P(CHC5H10)3), 2.06 (m, 12H, PCy3), 2.04 (s, 3H, CH3), 2.01 (s,
5
5
=
[PdCl{[(g -C5H5)]Fe[(g -C5H3)C(CH3) NC6H4-4-Br]}(PCy3)],
2e. Red solid, yield 75.2%. Found: C, 50.26; H, 5.63; N 1.48.
Calc. for C36H48BrClFeNPPd·CH2Cl2: C, 50.03; H, 5.67; N,
1.58%. Mp: 282 ◦C (decomp.). IR (KBr, cm−1): 2925, 2852, 1559
(C N), 1448, 1367, 1276, 1106, 1004. 1H NMR (400 MHz,
CDCl3): d 7.44 (d, J = 7.7 Hz, 2H, C6H4), 6.78 (d, J = 8.2 Hz,
2H, C6H4), 4.70 (m, 3H, C5H3), 4.38 (s, 5H, C5H5), 2.49 (m,
3H, P(CHC5H10)3), 1.99 (m, 6H, PCy3), 1.96 (s, 3H, CH3), 1.68
=
3H, CH3), 1.72 (m, 30H, PCy3), 1.25 (m, 18H, PCy3). 31P{ H}
1
NMR (162 MHz, CDCl3): d 47.45, 46.72. MS-ESI+: m/z 722.3
(M+ − Cl).
4736 | Dalton Trans., 2006, 4730–4739
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