A novel and efficient synthesis of terminal arylacetylenes via Sonogashira coupling reactions catalysed by MCM-41-supported bidentate phosphine palladium(0) complex

Article abstract of DOI:10.3184/030823407X275928

A variety of terminal arylacetylenes have been conveniently synthesised in good to high yields via Sonogashira coupling of aryl iodides with (trimethylsilyl)acetylene catalysed by a MCM-41-supported bidentate phosphine palladium(0) complex, followed by desilylation. The polymeric palladium catalyst can be reused many times without any decrease in activity.

Full text of DOI:10.3184/030823407X275928

728 RESEARCH PAPER
DECEMBER, 728–732
JOURNAL OF CHEMICAL RESEARCH 2007
A novel and efficient synthesis of terminal arylacetylenes via
Sonogashira coupling reactions catalysed by MCM-41-supported
bidentate phosphine palladium(0) complex
Yue Wang, Bin Huang, Shouri Sheng and Mingzhong Cai*
Department of Chemistry, Jiangxi Normal University, Nanchang 330022, P. R. China
A variety of terminal arylacetylenes have been conveniently synthesised in good to high yields via Sonogashira
coupling of aryl iodides with (trimethylsilyl)acetylene catalysed by a MCM-41-supported bidentate phosphine
palladium(0) complex, followed by desilylation. The polymeric palladium catalyst can be reused many times without
any decrease in activity.
Keywords: Sonogashira coupling, MCM-41-supported catalyst, bidentate phosphine palladium complex, heterogeneous catalysis,
terminal arylacetylene
Terminal arylacetylenes are an important synthetic
intermediates1 and are usually prepared by classical
procedures such as the Vilsmeier method,2 the halogenation-
dehydrohalogenation sequence of vinyl aromatics3 and
ketones,4 and the dehydrohalogenation of β,β-dihaloolefins.5
However, these methods involve a tedious multistep synthetic
procedure and the yields are poor to moderate. The palladium-
catalysed cross-coupling of terminal alkynes with aryl halides
is known as the Sonogashira reaction6 and has become an
extremely powerful tool for the formation of carbon–carbon
bonds. This coupling reaction has been widely applied in
organic synthesis since a wide variety of functionality can be
tolerated on either partner and the yields of coupled products
are high. Lau et al.7 reported that terminal arylacetylenes could
be conveniently synthesised in good yields by palladium(0)-
catalysed Sonogashira coupling of aryl halides with (trimethyl-
silyl)acetylene, followed by desilylation under mild conditions.
However, the Sonogashira reaction generally proceeds in the
presence of a homogeneous palladium catalyst, which makes
the catalyst recovery a tedious operation and may result in
unacceptable palladium contamination of the product. From
the standpoint of green chemistry, the development of more
environmentally benign conditions for the reaction, for
example the use of a heterogeneous palladium catalyst would
be desirable.8 So far, polymer-supported palladium catalysts
have successfully been used for the Heck reaction,9 the
Suzuki reaction,10 and the Sonogashira reaction.11 However,
to the best of our knowledge, no report for the Sonogashira
coupling of aryl halides with (trimethylsilyl)acetylene has
been reported using supported palladium catalysts. Recent
developments on the mesoporous material MCM-41 provided
a possible new candidate for a solid support for immobilisation
of homogeneous catalysts.12 MCM-41 has a regular pore
diameter of ca.5 nm and a specific surface area > 700 m2
g-1.13 Its large pore size allows passage of large molecules
such as organic reactants and metal complexes through the
pores to reach the surface of the channel.14 Very recently,
we have reported the synthesis of the first MCM-41-supported
bidentate phosphine palladium(0) complex [abbreviated as
MCM-41-2P-Pd(0)] and found that this complex is a highly
active and recyclable catalyst for the heterogeneous Suzuki
reaction.15 Herein we wish to report that a variety of terminal
arylacetylenes could be conveniently synthesised in good to
high yields via Sonogashira coupling of aryl iodides with
(trimethylsilyl)acetylene catalysed by MCM-41-2P-Pd(0),
followed by desilylation under mild conditions (Scheme 1).
The MCM-41-supported bidentate phosphine palladium(0)
complex [MCM-41-2P-Pd(0)] was prepared by our previous
procedure.15 The phosphine and palladium contents were
1.15 and 0.52 mmol/g, respectively. The influences of bases,
solvents and amounts of the catalyst on the catalytic property
of the MCM-41-2P-Pd(0) complex were investigated by using
the coupling reaction of iodobenzene with (trimethylsilyl)
acetylene. The results are shown in Table 1. It was found
that among the bases tested, piperidine proved to be the most
efficient. Among the solvents used, piperidine was also the
best choice. Increasing the amount of palladium catalyst could
shorten the reaction time, but did not increase the yield of 1-
phenyl-2-(trimethylsilyl)ethyne (entry 12). The low palladium
concentration usually led to a long period of reaction, which
was consistent with our experimental results (entries 13, 14).
Taken together, excellent results were obtained when the
coupling reaction was carried out with 0.5 mol% of MCM-41-
2P-Pd(0) and 5 mol% of CuI in piperidine at room temperature
(entry 9).
The results of MCM-41-2P-Pd(0)-catalysed cross-coupling
of a variety of aryl iodides with (trimethylsilyl)acetylene are
summarised in Table 2. As shown in Table 2, the coupling
reaction of aryl iodides having electron-withdrawing or
electron- donating substituents with (trimethylsilyl)acetylene
0.5 mol% MCM-41-2P-Pd(0)
K2CO3
MeOH, r.t.
Ar
SiMe3
I
Ar
SiMe3
+
Ar
CuI, piperidine, r.t.
1
2
3
OSiMe3
PPh2
Pd
PPh2
O
Si(CH2)3N
MCM-41-2P-Pd(0) =
O
OEt
Scheme 1
* Correspondent. E-mail: caimzhong@163.com
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JOURNAL OF CHEMICAL RESEARCH 2007 729
Table 1 Sonogashira reaction of iodobenzene with (trimethylsilyl)acetylene in the presence of several bases and solventsa
Entry
Base
Solvent
MCM-41-2P-Pd(0) (mol%)
Time/h
Yield b/%
1
2
Et3N
Toluene
DMF
Dioxane
Et3N
DMF
Dioxane
BuNH2
DMF
Piperidine
DMF
Pyrrolidine
Piperidine
Piperidine
Piperidine
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
1.0
0.1
0.05
9
6
73
79
78
82
80
75
83
85
96
83
92
95
90
85
Et3N
3
Et3N
Et3N
6
4
3
5
BuNH2
6
6
BuNH2
6
7
BuNH2
3
8
Piperidine
Piperidine
Pyrrolidine
Pyrrolidine
Piperidine
Piperidine
Piperidine
5
9
2
10
11
12
13
14
5
2
1
8
24
aAll reactions were performed using 1.0 mmol of iodobenzene, 1.5 mmol of (trimethylsilyl)acetylene, 0.05 mmol of CuI and
3.0 mmol of base in 3 ml of solvent at room temperature under Ar. bIsolated yield based on the iodobenzene used.
Table 2 Synthesis of 1-aryl-2-(trimethylsilyl)ethynes 2a–na
Entry
Ar-X
Product
Yieldb/%
1
2
Ph-I
2a
2b
2c
2d
2e
2f
2g
2h
2i
2j
2k
2l
2m
2n
96
97
96
93
95
93
90
97
96
98
94
96
92
88
4-BrC6H4-I
3
4-ClC6H4-I
4
4-MeOC6H4-I
4-O2NC6H4-I
4-MeC6H4-I
5
6
7
4-HOC6H4-I
8
4-MeCOC6H4-I
4-MeOCOC6H4-I
3-O2NC6H4-I
3-MeC6H4-I
9
10
11
12
13
14
3-NCC6H4-I
1-Iodonaphthalene
2-Iodothiophene
aAll reactions were performed using 1.0 mmol of aryl iodide, 1.5 mmol of (trimethylsilyl)ethyne, 0.005 mmol of palladium catalyst
and 0.05 mmol of CuI in 3 ml of piperidine at room temperature under Ar for 2 h.
bIsolated yield based on the aryl iodide 1 used.
0.05 mmol MCM-41-2P-Pd(0)
(1st-10th use)
0.5 mmol CuI
SiMe3
I
+
SiMe3
15 mmol
Piperidine, r.t., 2 h
2a
10 mmol
Table 3 Sonogashira reaction of iodobenzene with (trimethylsilyl)acetylene catalysed by recycled catalyst
Entry
Catalyst cycle
Isolated yield/%
TON
1
2
3
First
96
93
94
192
186
Total of 1880
Tenth
First to tenth consecutive
proceeded smoothly at room temperature in piperidine giving
a variety of 1-aryl-2-(trimethylsilyl)ethynes in excellent
yields after 2 h of reaction time. The coupling reactions of
aryl bromides with (trimethylsilyl)acetylene did not occur at
25°C or 60°C under the same conditions. The cross-coupling
reaction of 4-bromoiodobenzene with (trimethylsilyl)-acety-
lene afforded selectively 1-(4-bromophenyl)-2-(trimethylsilyl)
ethyne 2b in 97% yield; no 1,4-bis(trimethylsilylethynyl)
benzene was formed (entry 2). The coupling reaction of aryl
iodides with (trimethylsilyl)acetylene also proceeded in the
absence of copper iodide, but a longer reaction time (24 h)
was required and the yield was moderate. The Sonogashira
coupling reactions of 1-iodonaphthalene and heteroaryl
iodides such as 2-iodothiophene with (trimethylsilyl)acetylene
could also proceed smoothly under the same conditions
affording the corresponding coupled products in high
yields (entries 13, 14). The optimised catalyst system is
quite general in application and tolerant of a wide range of
functional groups such as nitro, cyano, halogen, methoxy,
carbonyl, hydroxy. In all reactions, only 0.5 mol% of MCM-41-
2P-Pd(0) based on the aryl iodides was used, the molar turnover
numbers (TON) were larger than those in the corresponding
coupling reaction catalysed by the homogeneous palladium
catalysts.6,7
The MCM-41-supported bidentate phosphine palladium(0)
catalyst can be easily recovered by simple filtration. We next
examined the reuse of the catalyst by using the Sonogashira
coupling of iodobenzene with (trimethylsilyl)acetylene.
In general, the continuous recycle of resin-supported palladium
catalysts is difficult owing to leaching of the palladium species
from the polymer supports. However, when the coupling
reaction of iodobenzene with (trimethylsilyl)acetylene was
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730 JOURNAL OF CHEMICAL RESEARCH 2007
Table 4 Synthesis of terminal arylacetylenes 3a–na
Entry
ArC∫CH
Product
Yieldb/%
1
2
PhC∫CH
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
88
90
91
86
92
90
85
91
94
89
93
94
88
86
4-BrC6H4C∫CH
3
4-ClC6H4C∫CH
4
4-MeOC6H4C∫CH
4-O2NC6H4C∫CH
4-MeC6H4C∫CH
4-HOC6H4C∫CH
4-MeCOC6H4C∫CH
4-MeOCOC6H4C∫CH
3-O2NC6H4C∫CH
3-MeC6H4C∫CH
3-NCC6H4C∫CH
1-Ethynylnaphthalene
2-Ethynylthiophene
5
6
7
8
9
10
11
12
13
14
aAll reactions were performed using 1.0 mmol of 2, 0.09 mmol of K2CO3 in 3 ml of MeOH at 25°C under Ar for 3 h.
bIsolated yield based on the 2 used.
The MCM-41- 2P-Pd(0) catalyst was separated from the mixture by
filtration, washed with distilled water (2 × 10 ml), EtOH (3 × 10 ml)
and Et2O (2 × 10 ml) and reused in the next run. The ethereal
solution was washed with water (2 × 10 ml) and dried over MgSO4.
The solvent was removed under vacuum, and the residue was purified
by flash chromatography on silica gel (light petroleum:ethyl acetate
= 2:1 for 2g; light petroleum for 2a, 2b, 2c, 2f, 2k, 2m, 2n; light
petroleum: ethyl acetate = 9:1 for 2d, 2e, 2h, 2i, 2j, 2l) to give the
desired product.
run even with 0.5 mol% of MCM-41-2P-Pd(0), the catalyst
could be recycled 10 times without any loss of activity.
The reaction promoted by the tenth recycled catalyst afforded
2a in 93% yield (Table 3, entry 2). The average yield of 2a
in consecutive reactions promoted by the 1-10 times recycled
catalyst was 94% (entry 3). The result is important from a
practical point of view.
Subsequent treatment of 1-aryl-2-(trimethylsilyl)ethynes 2
with anhydrous potassium carbonate in anhydrous methanol
at 25°C for 3 h gave a variety of terminal arylacetylenes
(Scheme 1). The experimental results are summarised in
Table 4. From the Table 4, we can see that the desilylation
reaction of a variety of 1-aryl-2-(trimethylsilyl)ethynes 2 in
the presence of anhydrous potassium carbonate proceeded
smoothly under mild conditions, affording the corresponding
terminal arylacetylenes 3 in good to high yields.
In conclusion, we have developed a novel and efficient
route for synthesis of terminal arylacetylenes by the
Sonogashira coupling of aryl iodides with (trimethylsilyl)
acetylene catalysed by a MCM-41-supported bidentate
phosphine palladium(0) catalyst, followed by desilylation
under mild conditions. Because (trimethylsilyl)acetylene
can be easily prepared in high yield under mild conditions
from acetylene and chlorotrimethylsilane according to the
procedure developed by Brandsma and Verkruijsse,16 the
present method has the advantages of readily available starting
materials, straightforward and simple procedures, mild
reaction conditions, high yields, tolerance for a wide variety
of functionality, and excellent reusability of the palladium
catalyst.
Compound 2a: IR (film): ν (cm-1) 3080, 2960, 2159, 1598, 1488,
1
1250, 843, 690; H NMR (CDCl3): δ 7.48–7.45 (m, 2H), 7.31–7.29
(m, 3H), 0.25 (s, 9H); 13C NMR (CDCl3): δ 132.0, 128.5, 128.2,
123.1, 105.1, 94.1, 0.01; MS: m/z 174 (M+, 19), 159 (68), 77 (57), 73
(100); Anal. Calc. for C11H14Si: C, 75.79; H, 8.10. Found: C, 75.92;
H, 8.2%.
Compound 2b: IR (film): ν (cm-1) 2957, 2158, 1582, 1485, 1247,
1
846, 759; H NMR (CDCl3): δ 7.42 (m, J* = 8.4 Hz, 2H), 7.32 (m,
J* = 8.4 Hz, 2H), 0.24 (s, 9H); 13C NMR (CDCl3): δ 133.4, 131.5,
122.7, 122.1, 103.9, 95.6, 0.14; MS: m/z 254 (M+, 80Br, 2.6), (M+, 78Br,
2.5) 165 (51), 125 (56), 111 (77), 97 (100), 83 (80), 71 (70); Anal. Calc.
for C11H13SiBr: C, 52.16; H, 5.17. Found: C, 51.9; H, 5.0%.
Compound 2c: IR (film): ν (cm-1) 3030, 2959, 2159, 1590, 1488,
1250, 844, 759, 685; 1H NMR (CDCl3): δ 7.38 (m, J* = 8.4 Hz, 2H),
7.26 (m, J* = 8.4 Hz, 2H), 0.24 (s, 9H); 13C NMR (CDCl3): δ 134.6,
133.2, 128.6, 121.7, 103.9, 95.4, -0.07; MS: m/z 210 (M+, 37Cl, 3.8),
208(M+, 35Cl, 12) 193 (64), 73 (100); Anal. Calc. for C11H13SiCl: C,
63.27; H, 6.28. Found: C, 63.4; H, 6.1%.
Compound 2d: IR (film): ν (cm-1) 2960, 2156, 1606, 1508, 1249,
1
834, 699; H NMR (CDCl3): δ 7.41 (m, J* = 8.8 Hz, 2H), 6.81 (m,
J* = 8.8 Hz, 2H), 3.81 (s, 3H), 0.24 (s, 9H); 13C NMR (CDCl3):
δ 159.7, 133.5, 115.3, 113.8, 105.2, 92.5, 55.3, 0.08; MS: m/z 204
(M+, 31), 189 (76), 73 (100); Anal. Calc. for C12H16SiO: C, 70.53; H,
7.89. Found: C, 70.3; H, 8.1%.
Compound 2e: IR (film): ν (cm-1) 2960, 2160, 1593, 1521, 1348,
1250, 866; 1H NMR (CDCl3): δ 8.17 (m, J* = 8.8 Hz, 2H), 7.60 (m,
J* = 8.8 Hz, 2H), 0.28 (s, 9H); 13C NMR (CDCl3): δ 147.2, 132.7,
130.0, 123.5, 102.7, 100.6, -0.30; MS: m/z 219 (M+, 33), 205 (47),
204 (100), 158 (73); Anal. Calc. for C11H13NSiO2: C, 60.24; H, 5.98.
Found: C, 60.4; H, 6.1%.
Experimental
1H NMR spectra were recorded on a Bruker AC-P400 (400 MHz)
spectrometer with TMS as an internal standard using CDCl3 as the
solvent. 13C NMR (100 MHz) spectra were recorded on a Bruker
AC-P400 (400 MHz) spectrometer using CDCl3 as the solvent. IR
spectra were determined on an FTS-185 instrument as neat films.
Mass spectra were obtained on a Finigan 8239 mass spectrometer
(EI, 70 eV). Microanalyses were measured using a Yanaco MT-3
CHN microelemental analyser. All reactions were carried out in pre-
dried glassware (150°C, 4 h) and cooled under a stream of dry Ar.
Piperidine was dried by KOH and distilled prior to use. For AA'XX'
systems in 1H NMR J* = J23 + J25.
Compound 2f: IR (film): ν (cm-1) 2959, 2158, 1612, 1507, 1251,
871, 844, 816; 1H NMR (CDCl3): δ 7.35 (m, J* = 8.0 Hz, 2H), 7.09
(m, J* = 8.0 Hz, 2H), 2.34 (s, 3H), 0.24 (s, 9H); 13C NMR (CDCl3):
δ 138.6, 131.9, 128.9, 120.1, 105.4, 93.2, 21.5, 0.03; MS: m/z 188
(M+, 13), 173 (84), 69 (66), 57 (100); Anal. Calc. for C12H16Si: C,
76.53; H, 8.56. Found: C, 76.3; H, 8.3%.
Compound 2g: IR (film): ν (cm-1) 3435, 2959, 2157, 1608, 1509,
1252, 868, 841; 1H NMR (CDCl3): δ 7.35 (m, J* = 8.4 Hz, 2H), 6.75
(m, J* = 8.4 Hz, 2H), 4.92 (s, 1H), 0.23 (s, 9H); 13C NMR (CDCl3):
δ 155.8, 133.7, 115.6, 115.3, 105.0, 92.5, 0.05; MS: m/z 190 (M+,
91), 175 (100), 136 (84), 121 (94), 93 (77), 65 (58); Anal. Calc. for
C11H14SiO: C, 69.42; H, 7.41. Found: C, 69.2; H, 7.5%.
General procedure for the synthesis of 1-aryl-2-(trimethylsilyl)ethynes
2a–n
Compound 2h: IR (film): ν (cm-1) 2961, 2159, 1688, 1600, 1558,
1263, 864, 843; 1H NMR (CDCl3): δ 7.88 (m, J* = 8.4 Hz, 2H), 7.53
(m, J* = 8.4 Hz, 2H), 2.60 (s, 3H), 0.27 (s, 9H); 13C NMR (CDCl3):
δ 197.3, 136.4, 132.1, 128.1, 128.0, 104.0, 98.1, 26.6, –0.18; MS:
m/z 216 (M+, 5.2), 149 (40), 111 (45), 97 (64), 71 (77), 57 (100);
Anal. Calc. for C13H16SiO: C, 72.17; H, 7.45. Found: C, 71.9;
H, 7.35%.
The aryl iodide (1.0 mmol), MCM-41-2P-Pd(0) (10 mg, 0.005 mmol
Pd), piperidine (3 ml), and CuI (0.05 mmol) were added to a
flask under argon, and the resulting mixture was stirred at room
temperature for 5 min. To this suspension was added (trimethylsilyl)
acetylene (1.5 mmol), and the reaction mixture was stirred at room
temperature for 2 h. The mixture was dissolved in Et2O (40 ml).
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JOURNAL OF CHEMICAL RESEARCH 2007 731
Compound 2i: IR (film): ν (cm-1) 2958, 2160, 1724, 1604, 1277,
1109, 860, 844, 770; 1H NMR (CDCl3): δ 7.96 (m, J* = 8.4 Hz,
2H), 7.52 (m, J* = 8.4 Hz, 2H), 3.91 (s, 3H), 0.26 (s, 9H); 13C NMR
(CDCl3): δ 166.5, 131.9, 129.7, 129.4, 127.8, 104.1, 97.7, 52.2, –0.17;
MS: m/z 232 (M+, 79), 218 (81), 217 (100), 201 (53), 158 (45); Anal.
Calc. for C13H16SiO2: C, 67.19; H, 6.94. Found: C, 67.35; H, 6.9%.
Compound 2j: IR (film): ν (cm-1) 2962, 2169, 1572, 1532, 1353,
1251, 845; 1H NMR (CDCl3): δ 8.31 (s, 1H), 8.17–8.14 (m, 1H),
7.76–7.73 (m, 1H), 7.48 (t, J = 8.0 Hz, 1H), 0.26 (s, 9H); 13C NMR
(CDCl3): δ 148.0, 137.5, 129.2, 126.8, 125.0, 123.1, 102.2, 97.6,
-0.27; MS: m/z 219 (M+, 11), 204 (100), 183 (57); Anal. Calc. for
C11H13NSiO2: C, 60.24; H, 5.98. Found: C, 59.95; H, 5.8%.
Compound 2k: IR (film): ν (cm-1) 2960, 2151, 1602, 1579, 1483,
1250, 843; 1H NMR (CDCl3): δ 7.30–7.25 (m, 2H), 7.18 (t, J = 7.6 Hz,
1H), 7.12 (d, J = 7.6 Hz, 1H), 2.31 (s, 3H), 0.24 (s, 9H); 13C NMR
(CDCl3): δ 137.8, 132.5, 129.3, 128.9, 128.0, 122.8, 105.2, 93.6, 21.0,
–0.12; MS: m/z 188 (M+, 73), 173 (100); Anal. Calc. for C12H16Si: C,
76.53; H, 8.56. Found: C, 76.7; H, 8.4%.
1574, 670; 1H NMR (CDCl3): δ 7.38 (m, J* = 8.0 Hz, 2H), 7.12 (m,
J* = 8.0 Hz, 2H), 3.03 (s, 1H), 2.35 (s, 3H); 13C NMR (CDCl3):
δ 139.0, 132.0, 129.1, 119.0, 104.2, 83.8, 21.5; MS (EI): m/z 116
(M+, 23), 101 (45), 97 (51), 91 (64), 71 (68), 69 (80), 57 (100). Anal.
Calcd for C9H8: C, 93.06; H, 6.94. Found: C, 92.8; H, 6.75.
Compound 3g: IR (film): ν (cm-1) 3289, 2154, 1609, 1585, 1510,
1
1261, 1093, 836; H NMR (CDCl3): δ 7.41 (m, J* = 8.4 Hz, 2H),
6.80 (m, J* = 8.4 Hz, 2H), 4.93 (br, 1H), 3.02 (s, 1H); 13C NMR
(CDCl3): δ 156.3, 133.8, 115.5, 114.2, 104.3, 83.7; MS: m/z 118 (M+,
100), 93 (89), 77 (56). Anal. Calcd for C8H6O: C, 81.34; H, 5.12.
Found: C, 81.6; H, 5.35.
Compound 3h: IR (film): ν (cm-1) 3282, 2926, 2162, 1686, 1595,
1494, 761; 1H NMR (CDCl3): δ 7.91 (m, J* = 8.4 Hz, 2H), 7.57
(m, J* = 8.4 Hz, 2H), 3.25 (s, 1H), 2.61 (s, 3H); 13C NMR (CDCl3):
δ 197.3, 136.8, 132.3, 128.2, 126.9, 82.8, 80.3, 26.6; MS: m/z 144
(M+, 86), 129 (100), 101 (91), 85 (64), 71 (75), 57 (85). Anal. Calcd
for C10H8O: C, 83.31; H, 5.59. Found: C, 83.05; H, 5.3.
Compound 3i: IR (film): ν (cm-1) 3290, 2925, 1725, 1608, 1278,
1109, 696; 1H NMR (CDCl3): δ 7.99 (m, J* = 8.4 Hz, 2H), 7.55
(m, J* = 8.4 Hz, 2H), 3.92 (s, 3H), 3.23 (s, 1H); 13C NMR (CDCl3):
δ 166.4, 132.1, 130.2, 129.5, 126.8, 82.8, 80.0, 52.3; MS: m/z 160
(M+, 57), 146 (32), 129 (100), 101 (71), 75 (34). Anal. Calcd for
C10H8O2: C, 74.99; H, 5.03. Found: C, 74.75; H, 4.8.
Compound 2l: IR (film): ν (cm-1) 2957, 2236, 2151, 1594, 1571,
1476, 1248, 846; 1H NMR (CDCl3): δ 7.74 (s, 1H), 7.65 (d, J = 8.0 Hz,
1H), 7.58 (d, J = 8.0 Hz, 1H), 7.42 (t, J = 8.0 Hz, 1H), 0.26 (s, 9H);
13C NMR (CDCl3): δ 135.8, 135.2, 131.5, 129.0, 124.7, 117.9, 112.7,
102.2, 97.3, -0.36; MS: m/z 199 (M+, 31), 83 (46), 71 (63), 57 (100);
Anal. Calc. for C12H13NSi: C, 72.31; H, 6.57. Found: C, 72.1; H,
6.3%.
Compound 3j: IR (film): ν (cm-1) 3289, 2119, 1574, 1530, 1473,
1352, 807, 736; 1H NMR (CDCl3): δ 8.34 (s, 1H), 8.22–8.19 (m, 1H),
7.81–7.78 (m, 1H), 7.52 (t, J = 8.0 Hz, 1H), 3.22 (s, 1H); 13C NMR
(CDCl3): δ 148.1, 137.8, 129.4, 127.0, 124.0, 123.6, 81.1, 79.9; MS:
m/z 147 (M+, 89), 123 (34), 111 (42), 101 (100), 77 (45), 75 (65), 57
(48). Anal. Calcd for C8H5NO2: C, 65.31; H, 3.43. Found: C, 65.45;
H, 3.5.
Compound 2m: IR (film): ν (cm-1) 2962, 2147, 1706, 1565, 1393,
1261, 843, 799; 1H NMR (CDCl3): δ 8.33 (d, J = 8.4 Hz, 1H), 7.85–
7.81 (m, 2H), 7.71–7.69 (m, 1H), 7.58–7.51(m, 2H), 7.43–7.38 (m,
1H), 0.34 (s, 9H); 13C NMR (CDCl3): δ 133.3, 133.0, 130.7, 128.9,
128.1, 126.7, 126.3, 126.1, 125.0, 120.7, 103.0, 99.4, 0.0; MS: m/z
224 (M+, 3.8), 127 (26), 91 (51), 77 (62), 64 (100); Anal. Calc. for
C15H16Si: C, 80.29; H, 7.19. Found: C, 80.0; H, 7.35%.
Compound 3k: IR (film): ν (cm-1) 3291, 2922, 2381, 1631, 1463,
1
758; H NMR (CDCl3): δ 7.32–7.16 (m, 4H), 3.04 (s, 1H), 2.33 (s,
Compound 2n: IR (film): ν (cm-1) 2961, 2147, 1250, 1164, 844,
699; 1H NMR (CDCl3): δ 7.26–7.22 (m, 2H), 6.95 (t, J = 4.4 Hz, 1H),
0.25 (s, 9H); 13C NMR (CDCl3): δ 132.7, 127.4, 127.0, 123.4, 98.9,
97.7, 0.13; MS: m/z 180 (M+, 15), 165 (56), 73 (100); Anal. Calc. for
C9H12SSi: C, 59.94; H, 6.71. Found: C, 59.7; H, 6.5%.
3H); 13C NMR (CDCl3): δ 138.0, 132.7, 129.7, 129.2, 128.2, 121.9,
104.2, 83.8, 21.2; MS: m/z 116 (M+, 19), 101 (54), 97 (61), 85 (67),
71 (84), 57 (100). Anal. Calcd for C9H8: C, 93.06; H, 6.94. Found: C,
93.2; H, 7.1.
Compound 3l: IR (film): ν (cm-1) 3293, 2233, 2109, 1641, 1594,
1573, 800; 1H NMR (CDCl3): δ 7.78–7.61 (m, 3H), 7.45 (t, J = 8.0 Hz,
1H), 3.19 (s, 1H); 13C NMR (CDCl3): δ 136.2, 135.5, 132.1, 129.3,
123.8, 117.9, 113.0, 81.2, 79.8; MS: m/z 127 (M+, 100), 101 (84),
75 (41). Anal. Calcd for C9H5N: C, 85.02; H, 3.96. Found: C, 84.8;
H, 3.8.
General procedure for the synthesis of terminal arylacetylenes 3a–n
A mixture of 1-aryl-2-(trimethylsilyl)ethyne (1.0 mmol), anhydrous
potassium carbonate (0.09 mmol) in anhydrous MeOH (3 ml) was
stirred at 25°C under argon for 3 h. The solvent was evaporated
under reduced pressure, and the residue was mixed with 2 ml of
aqueous sodium bicarbonate and extracted with Et2O (3 × 10 ml).
The combined organic fractions were dried over MgSO4, and
concentrated. The residue was purified by flash chromatography on
silica gel (light petroleum:ethyl acetate = 2:1 for 3g; light petroleum
for 3a, 3b, 3c, 3f, 3k, 3m, 3n; light petroleum: ethyl acetate = 9:1 for
3d, 3e, 3h, 3i, 3j, 3l).
Compound 3m: IR (film): ν (cm-1) 3292, 3058, 2102, 1586, 1508,
800, 773; 1H NMR (CDCl3): δ 8.37–8.35 (m, 1H), 7.85 (d, J = 8.0 Hz,
2H), 7.75–7.72 (m, 1H), 7.59-7.40 (m, 3H), 3.47 (s, 1H); 13C NMR
(CDCl3): δ 133.5, 133.1, 131.2, 129.3, 128.3, 127.0, 126.5, 126.1,
125.1, 119.8, 81.9, 81.8; MS: m/z 152 (M+, 23), 127 (68), 83 (59), 69
(64), 57 (100). Anal. Calcd for C12H8: C, 94.70; H, 5.30. Found: C,
94.5; H, 5.2.
Compound 3a: IR (film): ν (cm-1) 3292, 2110, 1598, 1574, 1488,
757, 691; 1H NMR (CDCl3): δ 7.51–7.48 (m, 2H), 7.35–7.32 (m,
3H), 3.08 (s, 1H); 13C NMR (CDCl3): δ 132.1, 128.8, 128.3, 122.1,
83.7, 77.1. MS: m/z 102 (M+, 43), 77 (65), 57 (100).
Compound 3n: IR (film): ν (cm-1) 3290, 2143, 1631, 1463, 1117,
700; 1H NMR (CDCl3): δ 7.34–7.27 (m, 2H), 7.01–6.98 (m, 1H), 3.33
(s, 1H); 13C NMR (CDCl3): δ 133.1, 128.9, 127.2, 122.5, 81.2, 77.4;
MS: m/z 108 (M+, 100), 83 (48). Anal. Calcd for C6H4S: C, 66.63; H,
3.73. Found: C, 66.4; H, 3.7.
Compound3b:IR(film):ν(cm-1)3287,2346,1583,1489,1462,758;
1H NMR (CDCl3): δ 7.46 (m, J* = 8.8 Hz, 2H), 7.35 (m, J* = 8.8 Hz,
2H), 3.12 (s, 1H). 13C NMR (CDCl3): δ 133.6, 131.6, 123.1, 121.1,
82.6, 78.3. MS: m/z 182 (M+, 80Br, 1.9), 180 (M+, 78Br, 1.8), 156 (38),
101 (49), 71 (60), 57 (100). Anal. Calcd for C8H5Br: C, 53.05; H,
2.78. Found: C, 52.8; H, 2.6.
Project 20462002 was supported by the National Natural
Science Foundation of China.
Compound 3c: IR (film): ν (cm-1) 3293, 2197, 1587, 1485, 1095, 822;
1H NMR (CDCl3): δ 7.42 (m, J* = 8.4 Hz, 2H), 7.30 (m, J* = 8.4 Hz,
2H), 3.10 (s, 1H); 13C NMR (CDCl3): δ 134.9, 133.4, 128.7, 120.6,
82.5, 78.2; MS: m/z 138 (M+, 37Cl, 31), 136 (M+, 35Cl,100), 135 (88),
111 (59), 69 (46). Anal. Calcd for C8H5Cl: C, 70.33; H, 3.69. Found:
C, 70.5; H, 3.6.
Received 27 October 2007; accepted 31 December 2007
Paper 07/4917
doi: 10.3184/030823407X275928
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