JOURNAL OF CHEMICAL RESEARCH 2014 221
1
reusability of the MCM-41-2P-PdCl make it a highly attractive
supported palladium catalyst for the parallel solution-phase
synthesis of diverse libraries of compounds.
H NMR (CDCl ): δ 10.11 (s, 1H), 8.01 (d, J=8.0 Hz, 2H), 7.86 (d,
2
3
1
3
J=8.0 Hz, 2H); C NMR (CDCl
17.6.
-Methylbenzaldehyde (2f): Oil. IR (film): ν (cm ) 2923, 2826,
): δ 190.7, 138.7, 132.9, 129.9, 128.0,
3
1
1
6
–1
3
In conclusion, we have developed a novel, practical and
economic catalyst system for the formylation of aryl halides with
HCOONa under an atmospheric pressure of CO by using the
diphosphino-functionalised MCM-41-immobilised palladium
complex as catalyst. The reactions generated a variety of
aromatic aldehydes in good to high yields. This heterogeneous
palladium catalyst exhibits high catalytic activity and can be
reused at least 10 times without any decreases in activity. The
heterogeneous formylation of aryl halides with HCOONa under
an atmospheric pressure of CO catalysed by the MCM-41-2P-
1
1
7
1
704, 1606, 1588, 1249, 1143, 782, 685; H NMR (CDCl ): δ 9.97 (s, 1H),
.69–7.65 (m, 2H), 7.44–7.38 (m, 2H), 2.42 (s, 3H); C NMR (CDCl ): δ
3
13
3
92.6, 138.9, 136.5, 135.3, 130.0, 128.9, 127.2, 21.2.
3
-Methoxycarbonylbenzaldehyde (2g): White solid, m.p. 48–50 °C
4
0
–1
(
6
1
lit. 50–51 °C). IR (KBr): ν (cm ) 3058, 2926, 1717, 1685, 1584, 782,
89; H NMR (CDCl ): δ 10.09 (s, 1H), 8.54 (s, 1H), 8.31 (d, J=7.6 Hz,
H), 8.10 (d, J=7.6 Hz, 1H), 7.64 (t, J=7.6 Hz, 1H), 3.97 (s, 3H);
1
3
13
C
NMR (CDCl ): δ 191.4, 166.0, 136.6, 135.2, 133.1, 131.3, 131.2, 129.3,
5
3
2.5.
41
4-Acetylbenzaldehyde (2h): White solid, m.p. 33–35 °C (lit.
–1
PdCl complex provides a better and practical procedure for the
33–34 °C). IR (KBr): ν (cm ) 1711, 1687, 1574, 1264, 1205, 838, 712;
2
1
synthesis of aromatic aldehydes.
H NMR (CDCl ): δ 10.12 (s, 1H), 8.11 (d, J=8.0 Hz, 2H), 7.99 (d,
3
13
J=8.0 Hz, 2H), 2.68 (s, 3H); C NMR (CDCl ): δ 197.4, 191.6, 141.2,
3
Experimental
139.0, 129.8, 128.8, 27.0.
4
-Methoxycarbonylbenzaldehyde (2i): White solid, m.p. 61–63 °C
DMF was distilled and dried prior to use, all other reagents were used
as-received without further purification. All reactions were carried
out under an atmosphere of CO in oven-dried glassware with magnetic
stirring. IR spectra were determined on a PerkinElmer 683 instrument.
42
–1
(
lit. 63–65 °C). IR (KBr): ν (cm ) 3053, 2929, 1721, 1681, 1594, 835;
H NMR (CDCl ): δ 10.11 (s, 1H), 8.20 (d, J=8.0 Hz, 2H), 7.96 (d,
J=8.0 Hz, 2H), 3.97 (s, 3H); C NMR (CDCl ): δ 191.7, 166.1, 139.2,
135.1, 130.1, 129.5, 52.6.
1
3
13
3
1
H NMR spectra were recorded on a Bruker Avance 400 (400 MHz)
43
4
-Nitrobenzaldehyde (2j): Yellow solid, m.p. 105–106 °C (lit. 106–
spectrometer with TMS as an internal standard using CDCl as the
3
–1
13
108 °C). IR (KBr): ν (cm ) 1714, 1604, 1540, 1351, 1201, 1104, 852,
20; H NMR (CDCl ): δ 10.18 (s, 1H), 8.41 (d, J=8.4 Hz, 2H), 8.09 (d,
J=8.4 Hz, 2H); C NMR (CDCl ): δ 190.3, 151.1, 140.0, 130.5, 124.3.
3
8 °C). IR (KBr): ν (cm ) 3069, 1705, 1615, 1535, 1353, 1203, 1087, 812,
30; H NMR (CDCl ): δ 10.14 (s, 1H), 8.73 (s, 1H), 8.52–8.49 (m, 1H),
.27–8.23 (m, 1H), 7.79 (t, J=7.6 Hz, 1H); C NMR (CDCl ): δ 189.8,
48.2, 137.4, 134.7, 130.4, 128.6, 124.5.
solvent. C NMR spectra were recorded on a Bruker Avance 400
1
8
(
100 MHz) spectrometer using CDCl as the solvent. The diphosphino-
3
3
13
3
functionalised MCM-41-immobilised palladium complex [MCM-
43
-Nitrobenzaldehyde (2k): Yellow solid, m.p. 58–59 °C (lit. 57–
3
6
4
1-2P-PdCl ] was prepared according to our previous procedure.
2
–1
5
7
8
Palladium content was determined by inductively coupled plasma atom
emission; Atomscan16 (ICP-AES, TJA Corporation). Melting points
were uncorrected.
1
3
13
3
1
CAUTION: Stringent safety precautions are required due to the
toxicity of carbon monoxide gas.
2
–1
3
-Trifluoromethylbenzaldehyde (2l): Oil. IR (film): ν (cm ) 3034,
1
1
702, 1613, 1586, 1312, 1137, 914, 768; H NMR (CDCl ): δ 10.09 (s,
3
1
H), 8.16 (s, 1H), 8.09 (d, J=7.6 Hz, 1H), 7.90 (d, J=7.6 Hz, 1H), 7.71
Synthesis of aromatic aldehydes; general procedure
A 50 mL round-bottomed flask, equipped with a gas inlet tube, a reflux
condenser and a magnetic stirring bar was charged with MCM-41-2P-
13
(
t, J=7.6 Hz, 1H); C NMR (CDCl ): δ 190.8, 136.7, 132.7, 131.6 (q,
JCF =33.0 Hz), 130.8 (q, JCF =4.0 Hz), 129.8, 126.4 (q, JCF =4 Hz),
3
2
3
3
1
123.5 (q, J =271.0 Hz).
CF
PdCl (102 mg, 0.05 mmol Pd), aryl halide (5.0 mmol) and HCOONa
16
–1
2
2-Methoxybenzaldehyde (2m): Oil. IR (film): ν (cm ) 3010, 2946,
846, 1689, 1600, 1485, 1287, 1246, 835, 759; H NMR (CDCl ): δ 10.47
(7.5 mmol). The flask was flushed with CO. DMF (5 mL) was added
1
2
3
by syringe and a slow stream of CO was passed into the suspension.
The mixture was vigorously stirred at 110–130 °C for 2–20 h, cooled
to room temperature and diluted with diethyl ether (50 mL). The
palladium catalyst was separated from the mixture by filtration,
washed with distilled water (2×10 mL), ethanol (2×10 mL) and ether
(
s, 1H), 7.83–7.81 (m, 1H), 7.57–7.53 (m, 1H), 7.04–6.98 (m, 2H), 3.92
13
(s, 3H); C NMR (CDCl ): δ 190.0, 161.8, 136.0, 128.6, 124.8, 120.7,
3
1
11.6, 55.6.
3
–1
2
-Methoxycarbonylbenzaldehyde (2n): Oil. IR (film): ν (cm )
1
3
7
054, 2928, 1712, 1678, 1594, 838; H NMR (CDCl ): δ 10.62 (s, 1H),
.99–7.93 (m, 2H), 7.67–7.64 (m, 2H), 3.98 (s, 3H); C NMR (CDCl ): δ
3
(2×10 mL) and reused in the next run. The ethereal solution was
13
3
washed with water (3×20 mL), and dried over anhydrous magnesium
sulfate and concentrated under reduced pressure. The residue was
purified by flash column chromatography on silica gel (hexane–ethyl
acetate=10:1).
192.2, 166.8, 137.0, 133.0, 132.4, 132.0, 130.4, 128.5, 52.8.
3
–1
2-Trifluoromethylbenzaldehyde (2o): Oil. IR (film): ν (cm ) 3034,
1
1707, 1602, 1586, 1417, 1312, 914, 768; H NMR (CDCl ): δ 10.41 (s,
3
1
3
1H), 8.15–8.13 (m, 1H), 7.81–7.79 (m, 1H), 7.75–7.70 (m, 2H); C NMR
16
–1
2
Benzaldehyde (2a): Oil. IR (film): ν (cm ) 3063, 1702, 1653, 1597,
(CDCl ): δ 189.0, 133.6, 132.3, 131.4 (q, J =33.0 Hz), 129.1, 126.1 (q,
3
CF
1
3
1
1
(
584, 1204, 827, 745, 688; H NMR (CDCl ): δ 10.02 (s, 1H), 7.89–7.87
JCF =6.0 Hz), 123.7 (q, J =273.0 Hz).
1-Naphthaldehyde (2p): Oil. IR (film): ν (cm ) 3054, 1689, 1623,
1592, 1574, 1510, 1217, 886, 802, 772; H NMR (CDCl ): δ 10.37 (s,
3
CF
13
13
–1
m, 2H), 7.64–7.61 (m, 1H), 7.55–7.50 (m, 2H); C NMR (CDCl ): δ
3
1
1
92.4, 136.4, 134.5, 129.8, 129.0.
3
38
4
-Chlorobenzaldehyde (2b): White solid, m.p. 45–46 °C (lit. 44–
1H), 9.24 (d, J=8.4 Hz, 1H), 8.08–8.06 (m, 1H), 7.96–7.89 (m, 2H),
–1
13
45 °C). IR (KBr): ν (cm ) 2859, 1693, 1588, 1576, 1387, 1208, 1080,
7.69–7.56 (m, 3H); C NMR (CDCl ): δ 193.6, 136.7, 135.3, 133.7, 131.4,
3
1
8
40, 815; H NMR (CDCl ): δ 9.99 (s, 1H), 7.83 (d, J=8.4 Hz, 2H),
130.5, 129.1, 128.5, 127.0, 124.9.
Pyridine-3-carboxaldehyde (2q): Oil. IR (film): ν (cm ) 2849, 1705,
1589, 1575, 1427, 1215, 831, 703; H NMR (CDCl ): δ 10.14 (s, 1H), 9.10
3
13
16
–1
7.52 (d, J=8.4 Hz, 2H); C NMR (CDCl ): δ 190.8, 141.0, 134.7, 130.9,
3
1
1
29.5.
3
16
–1
13
4
-Methylbenzaldehyde (2c): Oil. IR (film): ν (cm ) 1683, 1612, 1575,
(s, 1H), 8.87–8.86 (m, 1H), 8.21–8.18 (m, 1H), 7.53–7.50 (m, 1H);
C
1
1417, 1291, 1183, 840, 757; H NMR (CDCl ): δ 9.96 (s, 1H), 7.77 (d,
NMR (CDCl ): δ 190.8, 154.8, 152.1, 135.8, 131.4, 124.1.
3
3
1
3
13
–1
J=8.0 Hz, 2H), 7.33 (d, J=8.0 Hz, 2H), 2.44 (s, 3H); C NMR (CDCl ):
Thiophene-2-carboxaldehyde (2r): Oil. IR (film): ν (cm ) 1651,
1614, 1513, 1415, 1288, 1048, 860, 781; H NMR (CDCl ): δ 9.95 (s, 1H),
7.80–7.77 (m, 2H), 7.24–7.21 (m, 1H); C NMR (CDCl ): δ 183.1, 144.0,
3
1
δ 192.3, 144.7, 130.3, 129.2, 126.6, 21.8.
3
16
–1
13
4
-Methoxybenzaldehyde (2d): Oil. IR (film): ν (cm ) 2925, 2843,
3
1
1
683, 1599, 1578, 1260, 1160, 833; H NMR (CDCl ): δ 9.88 (s, 1H),
136.4, 135.2, 128.4.
Phenylacetaldehyde (2s): Oil. IR (film): ν (cm ) 3035, 2937, 1725,
1499, 1456, 1370, 1159, 1082, 744, 697; H NMR (CDCl ): δ 8.14 (s,
1H), 7.40–7.25 (m, 5H), 5.20 (s, 2H); C NMR (CDCl ): δ 160.8, 135.2,
3
13
5
–1
7.84 (d, J=8.4 Hz, 2H), 7.00 (d, J=8.4 Hz, 2H), 3.89 (s, 3H); C NMR
1
(
CDCl ): δ 190.9, 164.6, 132.0, 129.9, 114.3, 55.6.
3
3
39
13
4
-Cyanobenzaldehyde (2e): White solid, m.p. 98–99 °C (lit.
3
–1
9
3–94 °C). IR (KBr): ν (cm ) 2229, 1708, 1607, 1571, 1203, 832, 819;
128.7, 128.5, 128.4, 65.7.
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