Sonogashira reaction of aryl and heteroaryl halides with terminal alkynes catalyzed by a highly efficient and recyclable nanosized MCM-41 anchored palladium bipyridyl complex

Article abstract of DOI:10.3390/molecules15129157

A heterogeneous catalyst, nanosized MCM-41-Pd, was used to catalyze the Sonogashira coupling of aryl and heteroaryl halides with terminal alkynes in the presence of CuI and triphenylphosphine. The coupling products were obtained in high yields using low Pd loadings to 0.01 mol%, and the nanosized MCM-41-Pd catalyst was recovered by centrifugation of the reaction solution and re-used in further runs without significant loss of reactivity.

Full text of DOI:10.3390/molecules15129157

Molecules 2010, 15, 9157-9173; doi:10.3390/molecules15129157
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Sonogashira Reaction of Aryl and Heteroaryl Halides with
Terminal Alkynes Catalyzed by a Highly Efficient and
Recyclable Nanosized MCM-41 Anchored Palladium
Bipyridyl Complex
Bo-Nan Lin 1, Shao-Hsien Huang 1, Wei-Yi Wu 1, Chung-Yuan Mou 2 and Fu-Yu Tsai 1,*
1
Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei
106, Taiwan
2
Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
* Author to whom correspondence should be addressed; E-Mail: fuyutsai@ntut.edu.tw;
Fax: +886-2-2731-7174.
Received: 11 November 2010; in revised form: 6 December 2010 / Accepted: 9 December 2010 /
Published: 10 December 2010
Abstract: A heterogeneous catalyst, nanosized MCM-41-Pd, was used to catalyze the
Sonogashira coupling of aryl and heteroaryl halides with terminal alkynes in the presence
of CuI and triphenylphosphine. The coupling products were obtained in high yields using
low Pd loadings to 0.01 mol%, and the nanosized MCM-41-Pd catalyst was recovered by
centrifugation of the reaction solution and re-used in further runs without significant
loss of reactivity.
Keywords: Sonogashira reaction; mesoporous silica; palladium complex; recyclable
catalyst; heterogeneous catalysis
1. Introduction
The reaction of aryl halides or vinyl halides with terminal alkynes catalyzed by a Pd(II)/Cu(I)
system is known as the Sonogashira coupling, and is one of the most powerful methods for the
straightforward construction of sp2–sp carbon–carbon bonds in synthetic chemistry [1–7]. This
methodology has been widely applied to prepare biologically-active molecules [8–13], natural

Molecules 2010, 15
9158
products [14–17], conducting polymers/engineering materials [18,19], and macrocycles with acetylene
links [20,21].
The Sonogashira reaction is, in general, carried out in a homogeneous phase [22], and therefore the
recovery of expensive palladium complexes, facile separation of catalysts and products, and industrial
application are major aims for the benefit of both economy and the environment. For these reasons,
heterogenization of the homogeneous Sonogashira reaction has become an aim of great interest to
chemists in recent years. Choudary and co-workers described a layered double hydroxide-supported
nanopalladium catalyst for the coupling of aryl chlorides and phenylacetylene [23], and Pd/C has been
used to catalyze the Sonagashira reaction of aryl halides with acetylenes [24–30], while PVP-
supported nanoparticle palladium metal can be employed for the coupling of aryl iodides and bromides
with terminal alkynes [31]. Djakovitch and co-workers reported that microporous [Pd-Cu]/NaY [32],
[Pd(NH3)4]2+/(NH4)Y [33], and [Pd(NH3)4]2+/NaY [34] systems can be applied in the Sonogashira
reaction using 1–2 mol% of the Pd catalyst, and palladium can be also supported by silica in order to
create a recyclable catalyst for use in the Sonogashira reaction [35].
Mesoporous silica is becoming more and more widely used as a solid support owing to its well-
defined structure, uniform pore size, high surface area, and large number of silanol groups for the
grafting of metal complexes [36–44]. Djakovitch’s group prepared a mesoporous [Pd]/SBA-15 catalyst
to demonstrate that larger aryl halides such as bromoanthacene can be active in this catalytic system,
whereas the microporous support [Pd(NH3)4]2+/NaY is inactive [45]. Cai and co-workers employed
MCM-41-supported sulfur palladium [46], bidentate phosphine palladium [47], and thioether
palladium [48] systems to catalyze the coupling of aryl iodides and terminal alkynes after reduction of
the catalyst. Although most known heterogeneous catalysts have been demonstrated to be able to be
recycled for use in further runs, the use of catalytic amounts of 0.2–5 mol% of Pd for the Sonagashira
reaction is still too high for a single batch reaction when compared with homogeneous catalysts
[49–54]. We have recently prepared a nanosized MCM-41 grafted palladium bipyridyl complex, NS-
MCM-41-Pd (Figure 1), as a highly efficient and recyclable catalyst for the Mizoroki-Heck reaction
[55], Kumada-Tamao-Corriu reaction [56], ketone formation [57], and ynone formation [58], which
require a very low catalyst loading for a single batch reaction.
Figure 1. NS-MCM-41-Pd.
Nanosized MCM-41 wall
O
O
O
O
O
O
Si
Si
NH
HN
N
N
Pd
Cl
Cl

Molecules 2010, 15
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The major advantage of this catalyst is that the short and highly-connective wormhole-like channels
of nanosized MCM-41 lead to the easy exchange of reactants, salts and products throughout the
nanochannels, avoiding saturation of activity. In this paper, we report the use of nanosized MCM-41-
Pd to catalyze the coupling of aryl and heteroaryl halides with phenylacetylene and alkynols with high
efficiency under Sonogashira reaction conditions using a catalyst loading as low as 0.01 mol%, with
the ability to recycle the catalyst for further use (Scheme 1).
Scheme 1. NS-MCM-41-Pd-catalyzed Sonogashira reaction.
NS-MCM-41-Pd (0.1-0.01 mol%)
PPh (0.2-0.02 mol%)
3
ArX +
R
Ar
R
CuI (0.2-0.02 mol%)
Et N, solvent, heat
3
X = I, Br
R = Ph, C(CH ) OH, CH OH, CH CH OH
3 2
2
2
2
2. Results and Discussion
2.1. Optimization of reaction conditions for the Sonogashira reaction catalyzed by NS-MCM-41-Pd
The procedure for the synthesis of the catalyst, NS-MCM-41-Pd, was presented in our previous
reports. After the grafting of the palladium bipyridyl complex onto NS-MCM-41, the surface area and
pore diameter decreased from 705 m2/g and 2.5 nm to 588 m2/g and 2.3 nm, respectively, and the
amount of Pd complex anchored to the wall of NS-MCM-41 was quantified to be 0.15 mmol/g by ICP-
MASS analysis. In order to optimize the conditions for this prepared heterogeneous catalyst, the
solvent effect was first examined using iodobenzene (1a) and phenylacetylene (2a) as representative
reactants. Reactions were carried out in the presence of 0.1 mol% catalyst, 0.2 mol% CuI, 0.2 mol%
PPh3, and Et3N at 50 °C under N2 for 3 h. The results are summarized in Table 1, and it was found that
Et3N was the best solvent for this reaction (Table 1, Entry 1).
Table 1. NS-MCM-41-Pd-catalyzed Sonogashira coupling reaction of iodobenzene 1a with
phenylacetylene 2a.a
Entry
1
2
3
4
5
6
7
8
9
10
11
12
Pd (mol%) CuI (mol%)
PPh3 (mol%)
Solvent
Et3N
Toluene
DMF
DMSO
NMP
Et3N
Et3N
Et3N
Toluene
DMF
Toluene
DMF
Base
Et3N
Yield (%)b
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0
0.2
0.2
0.2
0.2
0.2
0
0.2
0
0.2
0.2
0.2
0.2
97
60
34
26
5
38
0
0
Et3Nc
Et3Nc
Et3Nc
Et3Nc
Et3N
Et3N
0
Et3N
0.2
0.2
0.2
0.2
KOHc
KOHc
0
0
0
c
K2CO3c
K2CO3
0
a Reaction conditions: [1a]:[2a]:[Pd] = 1000:1100:1, at 50 °C for 3 h. Isolated yields. 3 equiv
based on 1a was used as a base.
b
c

Molecules 2010, 15
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The use of toluene, DMF, DMSO, and NMP as solvents resulting in lower rates of conversion
(Entries 2–5). In the absence of triphenylphosphine, this Sonogashira coupling reaction still proceeded,
but with less satisfactory yields (Entry 6). However, the co-catalyst CuI appeared to be necessary for
the coupling reaction (Entries 7–8). Regarding the use of a base, inorganic bases such as KOH and
K2CO3 were also examined, but under these conditions the desired product was not obtained due to the
poor solubility of these salts in organic solvents (Entries 9–12) [55].
2.2. Sonogashira reaction of aryl halides with phenylacetylene
Following optimization of the reaction conditions, the reactions of 2a with various aryl halides were
screened in the subsequent investigation (Table 2).
Table 2. Sonogashira reaction of aryl halides (1) with phenylacetylene (2a) catalyzed by
nanosized MCM-41-Pd.a
Entry Aryl halide
Pd (mol%)
0.1
Solvent/Base
Et3N/Et3N
Et3N/Et3N
Et3N/Et3N
Et3N/Et3N
T (°C) t (h)
Yield (%)b TON
1
2
C6H5I
C6H5I
1a
1a
1b
1b
1c
1d
1d
1e
1f
50
50
50
50
50
140
100
90
90
90
90
90
90
90
90
90
3
12
3
3a, 97
3a, 98
3b, 96
3b, 96
3c, 87
3a, 30
3a, 56
3b, 93
3d, 98
3e, 99
3f, 46
3c, 40
3g, 71
3h, 36
3i, 99
3j, 98
970
9800
960
9600
870
300
560
930
980
9900
460
400
710
360
990
980
0.01
0.1
0.01
0.1
0.1
0.1
0.1
0.1
0.01
0.1
0.1
3
4
5
6
4-IC6H4CN
4-IC6H4CN
4-MeOC6H4I
C6H5Br
9
Et3N/Et3N
24
24
24
3
6
6
24
72
48
96
3
NMP/Bu3Nc
Toluene/Bu3Nc
Et3N/Et3N
7
C6H5Br
8
9
4-BrC6H4CN
4-MeCOC6H4Br
4-NO2C6H4Br
4-ClC6H4Br
4-MeOC6H4Br
2-Bromothiophene 1j
3-Bromothiophene 1k
2-Bromopyridine
3-Bromopyridine
NMP/Et3Nc
NMP/Et3Nc
NMP/Et3Nc
NMP/Et3Nc
NMP/Et3Nc
NMP/Et3Nc
NMP/Et3Nc
NMP/Et3Nc
10
11
12
13
14
15
16
1g
1h
1i
0.1
0.1
0.1
0.1
1l
1m
24
a Reaction conditions: [1]:[2a] = 1:1.1, [Pd]:[CuI]:[PPh3] = 1:2:2. Isolated yields. 3 equiv based
on 1 was used as a base.
b
c
Reactions of 2a with aryl iodides proceeded well with the use of 0.1 mol% NS-MCM-41-Pd at
50 °C (Table 2, Entries 1, 3, and 5), and it should be noted that the same good yields were also
obtained in these reactions when using a lower amount of catalyst (0.01 mol%) (Entries 2 and 4).
However, the Sonogashira reaction of bromobenzene (1d) and 2a under the same conditions did not
afford any product, but replacing the Et3N solvent by NMP, a typical solvent for such coupling
reactions, resulted in the formation of 3a in a 30% yield at an elevated temperature (Entry 6), and a
yield of up to 56% could be achieved by performing the reaction in toluene at 100 °C for 24 h (Entry
7). Using activated aryl bromides such as 4-bromobenzonitrile (1e), 4-bromoacetophenone (1f), and
4-bromonitrobenzene (1g), better yields of the coupling reactions were observed (Entries 8–10). In the
case of the coupling of 1h with 2a, the C–Cl bond was inert under the reaction conditions, while the
product coupled through the C–Br bond was obtained in a 46% yield (Entry 11). Next, we studied the
coupling of halothiophenes and halopyridines with 2a, and it appeared that 2-bromothiophene (1j) and

Molecules 2010, 15
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2-bromo-pyridine (1l) resulted in better yields than the corresponding bromides at the 3-position
(Entries 13–16).
2.3. Sonogashira reaction of aryl halides with alkynols
Under similar conditions, NS-MCM-41-Pd-catalyzed Sonogashira coupling of a wide variety of aryl
halides with 2-methyl-3-butyn-2-ol (4a) was also achieved (Table 3), and a reaction temperature of
90 °C was found to be optimal. Aryl iodides reacted with 4a to give the corresponding coupling
products in good to excellent yields (Entries 1–3), whereas the use of deactivated bromides as
substrates resulted in lower yields (Entry 4). Reactions of activated bromides delivered better
conversion rates (Entries 5–9): for example, the catalyst had a turnover number (TON) of 9,600 for the
coupling of 1e with 4a (Entry 7), and for the heteroaryl halides (Entries 11–15), the catalyst exhibited
great activity, with the exception of the reactions of 1k (Entries 12).
Table 3. Sonogashira reaction of aryl halides 1 with alkynols 4 catalyzed by nanosized MCM-41-Pd.a
Entry
1
Aryl halide
Alkynyl alcohol
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CC(CH3)2OH
HC≡CCH2OH
Pd (mol%)
0.1
t (h)
3
Yield (%)b TON
C6H5I
1a
1b
1c
1d
1e
1e
1f
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4b
4b
4b
4b
4b
4b
4b
4b
4b
4b
5a, 94
5b, 98
5c, 61
5a, 21
5b, 98
5b, 96
5d, 98
5e, 97
5f, 69
5c, 20
5g, 99
5h, 59
5i, 99
5j, 98
5j, 34
5k, 85
5k, 84
5l, 83
5k, 10
5l, 71
5m, 98
5m, 98
5n, 99
5o, 15
5p, 18
940
980
610
210
980
9600
980
970
690
200
990
590
990
980
3400
850
8400
830
100
710
980
9800
990
150
180
2
4-IC6H4CN
0.1
3
3
4-MeOC6H4I
C6H5Br
0.1
72
96
3
4
0.1
5
4-BrC6H4CN
4-BrC6H4CN
4-MeCOC6H4Br
4-NO2C6H4Br
4-ClC6H4Br
0.1
6
0.01
0.1
12
3
7
8
1g
1h
1i
0.1
3
9
0.1
24
96
48
96
3
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
4-MeOC6H4Br
2-Bromothiophene
3-Bromothiophene
2-Bromopyridine
3-Bromopyridine
3-Bromopyridine
C6H5I
0.1
1j
0.1
1k
1l
0.1
0.1
1m
1m
1a
1a
1b
1d
1e
1f
0.1
6
0.01
0.1
24
12
24
3
C6H5I
HC≡CCH2OH
0.01
0.1
4-IC6H4CN
HC≡CCH2OH
C6H5Br
HC≡CCH2OH
0.1
96
24
3
4-BrC6H4CN
4-BrC6H4COMe
4-BrC6H4COMe
4-BrC6H4NO2
4-BrC6H4Cl
HC≡CCH2OH
0.1
HC≡CCH2OH
0.1
1f
HC≡CCH2OH
0.01
0.1
48
24
72
48
1g
1h
1j
HC≡CCH2OH
HC≡CCH2OH
0.1
2-Bromothiophene
HC≡CCH2OH
0.1

Molecules 2010, 15
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Table 3. Cont.
26
27
28
29
30
31
32
33
34
3-Bromothiophene
1k
1l
HC≡CCH2OH
4b
4b
4b
4c
4c
4c
4c
4c
4c
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
96
3
5q, 8
80
810
650
780
450
990
890
320
640
2-Bromopyridine
3-Bromopyridine
C6H5I
HC≡CCH2OH
5r, 81
5s, 65
5t, 78
5u, 45
5v, 99
5w, 89
5x, 32
5y, 64
1m
1a
1c
1e
1f
HC≡CCH2OH
48
6
HC≡CCH2CH2OH
HC≡CCH2CH2OH
HC≡CCH2CH2OH
HC≡CCH2CH2OH
HC≡CCH2CH2OH
HC≡CCH2CH2OH
4-MeOC6H4I
12
12
12
12
12
4-BrC6H4CN
4-BrC6H4COMe
2-Bromothiophene
2-Bromopyridine
1j
1l
a Reaction conditions: [1]:[4a or 4c] = 1:1.1; [1]:[4b] = 1:1.5; [Pd]:[CuI]:[PPh3] = 1:2:2; Et3N was
used as the solvent and base at 90 °C. b Isolated yields.
We also studied the reactivity of propargyl alcohol (4b) with aryl and heteroaryl halides in the
presence of 0.1–0.01 mol% of catalyst (Entries 16–28). Generally, the reaction rates for the coupling of
aryl and heteroaryl halides with 4b were slower than those for coupling with 4a, and reaction of aryl
iodides with 4b at 90 °C gave the desired products in high yields (Entries 16–18). The use of 1d
afforded only 10% of product under the reaction conditions described (Entry 19), while for electron-
poor aryl bromides, excellent yields were obtained (Entries 20–23). In the case of 1f, using a
0.01 mol% catalyst loading, a TON of 9,800 was achieved, which is comparable with the reported
efficiency of homogeneous catalysts [17b,f,g] (Entry 22). On the other hand, coupling of 1h with 4b
gave a yield of only 15% (Entry 24). As for heteroaryl halides, the use of bromothiophenes 1j and 1k
did not provide the products in good yields (Entries 25 and 26), while with halopyridines, the coupling
products were obtained in good to excellent yields (Entries 27 and 28). The coupling of
3-butyn-1-ol (4c) with aryl and heteroaryl halides at a catalyst loading of 0.1 mol% was also screened,
and the corresponding products were obtained in moderate to high yields (Entries 29–34).
2.4. Recycling and leaching studies of NS-MCM-41-Pd in the Sonogashira reaction
One of the purposes of designing this catalyst was to enable catalyst recycling for further use in
subsequent reactions. In context, aryl iodides, activated aryl bromides, and several terminal alkynes
were examined under optimized reaction conditions, and after completion of the initial cycle, the NS-
MCM-41-Pd catalyst was extracted by centrifugation from the reaction mixture, washed successively
with THF, H2O, and THF, and used for the next run with no regeneration treatment. The results using
the recycled catalyst are shown in Table 4. In the case of aryl iodides, we found that the activity of the
catalyst was completely retained after two recycled runs, giving an overall TON of between 2,450 and
2,960 (Table 4, Entries 1, 3, and 5). For the activated aryl bromides, the NS-MCM-41-Pd catalyst also
exhibited high TONs in the recycled runs (Entries 2 and 4), but a gradual decrease in catalytic activity
was observed in the reaction of 1f with 4b (Entry 6).

Molecules 2010, 15
Table 4. Sonogashira coupling reaction catalyzed by recycled nanosized MCM-41-Pd.a
9163
Yield, % b (TON)
1st recycle 2nd recycle
Entry Aryl halide Alkyne
Solvent/Base T (°C) t (h)
Initial cycle
99 (990)
98 (980)
94 (940)
98 (980)
83 (830)
98 (980)
1
1a
1f
2a
2a
4a
4a
4b
4b
Et3N/Et3N
NMP/Et3Nc
Et3N/Et3N
Et3N/Et3N
Et3N/Et3N
Et3N/Et3N
50
90
90
90
90
90
3
6
3
3
3
3
99 (990)
93 (930)
90 (900)
99 (990)
82 (820)
88 (880)
98 (980)
91 (910)
88 (880)
95 (950)
80 (800)
76 (760)
2
3
1a
1f
4
5d
6d
1b
1f
a Reaction conditions: [1]:[2 or 4]:[Pd]:[CuI]:[PPh3] = 1,000:1,100:1:2:2. b Isolated yields. c 3 equiv
based on 1 was used as a base. d[1]:[4b]:[Pd]:[CuI]:[PPh3] = 1,000:1,500:1:2:2.
Several studies have successfully determined the amount of metal leaching using a hot-filtration
technique, and this method was therefore used in this study to examine the activity of the catalyst with
regards to metal leaching [45–48,56–58]. A reaction mixture of 1a with 2a in the above-described
catalytic system was stirred at 50 °C for 30 min, resulting in a GC yield of 32%. The hot reaction
mixture was then filtered through a dried Celite pad under nitrogen to remove the NS-MCM-41-Pd
catalyst and any insoluble species, and the clear filtrate was introduced to another Schlenk tube at
50 °C. Further detection by GC demonstrated improvement of the yield to only 37% after 3 h, even in
the presence of additional CuI and PPh3 (Figure 2). This result shows that no active species were
dissolved in the solution to catalyze the coupling reaction. We further determined the Pd-content in the
filtrate by ICP-MASS, and only 0.5 ppm of palladium was found in the solution, which indicated that
the catalytic activity may mainly result from the grafted palladium complex. However, another
pathway of the Sonogashira reaction is catalysis by a dissolved Pd-species that occurs inside the
channels of NS-MCM-41, and this pathway cannot be excluded.
Figure 2. Plot of yield versus time with hot-filtration for 0.5 h of reaction at 50 °C (■) and
a comparative reaction without hot-filtration (□). [1a]:[2a]:[Pd]:[CuI]:[PPh3] =
1000/1100/1/2/2.
100
80
60
40
20
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Reaction time (h)

Molecules 2010, 15
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3. Experimental
3.1. General
All reactions involving air- and moisture- sensitive conditions were carried out under a dry nitrogen
atmosphere. N-Methylpyrrolidinone (NMP) was distilled under reduced pressure before use; Et3N and
Bu3N were distilled from KOH; and toluene was distilled from sodium benzophenone ketyl. Aryl
halides and terminal alkynes were purchased from ARCOS Co. Ltd and were used without further
purification. 4,4’-Bis(bromomethyl)-2,2’-bipyridine [59,60], nanosized MCM-41 [61], and NS-MCM-
41-Pd [55,56] were prepared according to the previously-published procedures. Melting points were
recorded on melting point apparatus and were uncorrected. 1H- and 13C-NMR spectra were recorded in
CDCl3 or C6D6 solution at 25 °C on a Varian 200 NMR spectrometer. GC analysis was performed on
an SRI 8610C instrument equipped with a fused silica capillary column.
3.2. General procedure for the Sonogashira coupling
Under a nitrogen atmosphere, a mixture of NS-MCM-41-Pd (50 mg, 7.5 × 10-3 mmol-Pd), CuI
(2.9 mg, 1.5 × 10-2 mmol), and PPh3 (3.9 mg, 1.5 × 10-2 mmol) in Et3N (15 mL) in a 50 mL Schlenk
tube was charged with aryl halide (7.5 mmol) and terminal alkyne (8.3 mmol; in the case of 4b,
11.3 mmol was used), and the reaction mixture stirred at 50 °C or 90 °C. After cooling to room
temperature, the resulting solution was passed through a short silica gel column with ethyl acetate as
the eluent to remove ammonium salt. After evaporation of the solvent, column chromatography on
silica gel afforded the desired product.
1
Diphenylacetylene (3a). White solid. m.p. 60–61 °C (lit.[47] 60–61 °C). H-NMR: δ 7.32–7.34 (m,
6H), 7.51–7.56 (m, 4H); 13C-NMR: δ 89.2 (2C), 122.9 (2C), 127.8 (4C), 127.9 (2C), 131.2 (4C).
1
4-(Phenylethynyl)benzonitrile (3b). Pale yellow solid. m.p. 108–110 °C (lit.[62] 106–108 °C). H-
13
NMR: δ 7.35–7.38 (m, 3H), 7.51–7.55 (m, 2H), 7.60–7.61 (m, 4H); C-NMR: δ 87.6, 93.6, 111.1,
118.2, 121.8, 127.8, 128.1 (2C), 128.7, 131.3 (2C), 131.6 (2C), 131.6 (2C).
4-(Phenylethynyl)anisole (3c). Brown solid. m.p. 60–61 °C (lit.[62] 60.6 °C). 1H-NMR: δ 2.88 (s, 3H),
13
6.28–6.33 (m, 2H), 6.69–6.70 (m, 3H), 7.15–7.20 (m, 4H); C-NMR: δ 55.4, 87.9 (2C), 113.7 (2C),
115.0, 123.2, 127.5, 127.9 (2C), 131.0 (2C), 132.6 (2C), 158.9.
1
4-(Phenylethynyl)acetophenone (3d). Brown solid. m.p. 97–99 °C (lit.[47] 98–99 °C). H-NMR: δ
2.60 (s, 3H), 7.34–7.37 (m, 3H), 7.51–7.61 (m, 2H), 7.78–7.83 (m, 2H), 7.91–7.95 (m, 2H); 13C-NMR:
δ 27.0, 88.5, 92.6, 122.3, 127.8, 127.9 (2C), 128.0 (2C), 128.4, 131.3 (2C), 132.0 (2C), 135.7, 196.4.
4-(Phenylethynyl)nitrobenzene (3e). Yellow solid. m.p. 116–117 °C (lit.[62] 114–116 °C). 1H-NMR: δ
7.34–7.39 (m, 3H) 7.52–7.56 (m, 2H), 7.63–7.66 (m, 2H), 8.19–8.22 (m, 2H); 13C-NMR: δ 87.4, 94.6,
121.7, 123.3, 128.1 (2C), 128.9 (2C), 129.8, 131.4 (2C), 131.8 (2C), 146.4.

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Phenyl-(4-chlorophenyl)acetylene (3f). White solid. m.p. 82–83 °C (lit.[47] 82–83 °C). 1H-NMR: δ
7.30–7.36 (m, 5H), 7.43–7.46 (m, 2H), 7.51–7.53 (m, 2H); 13C-NMR: δ 88.1, 90.2, 121.4, 122.5, 128.0
(2C), 128.1, 128.3 (2C), 131.2 (2C), 132.4 (2C), 133.8.
1
2-(Theinylethynyl)benzene (3g). Pale yellow solid. m.p. 50–52 °C (lit.[63] 51–53 °C). H-NMR: δ
7.00–7.02 (m, 1H), 7.28–7.29 (m, 2H), 7.34–7.35 (m, 3H), 7.51–7.52 (m, 2H); 13C-NMR: δ 82.5, 92.9,
126.7, 126.8, 127.9 (2C), 128.0, 128.1, 131.0 (2C), 131.5, 132.0.
1
3-(Theinylethynyl)benzene (3h). Brown solid. m.p. 50–52 °C (lit.[64] 52–54 °C). H-NMR: δ
7.20–7.22 (m, 1H), 7.29–7.32 (m, 1H), 7.33–7.37 (m, 3H), 7.52–7.54 (m, 3H); 13C-NMR: δ 84.4, 88.8,
121.9, 122.8, 125.0, 127.8, 127.9 (2C), 128.2, 129.4, 131.1 (2C).
1
2-(Phenylethynyl)pyridine (3i) [65]. Colorless liquid. H-NMR: δ 7.15–7.18 (m, 1H), 7.29–7.32 (m,
3H), 7.45–7.47 (m, 1H), 7.54–7.62 (m, 3H), 8.55–8.57 (m, 1H); 13C-NMR: δ 88.4, 88.9, 121.7, 122.3,
126.6, 127.9, 128.4, 131.5, 135.6, 142.8, 149.3.
1
3-(Phenylethynyl)pyridine (3j). Yellow solid. m.p. 50–51 °C (lit.[66] 50–51 °C). H-NMR: δ
7.23–7.26 (m, 1H), 7.33–7.36 (m, 3H), 7.52–7.55 (m, 2H), 7.76–7.79 (m, 1H), 8.51–8.53 (m, 1H),
8.75–8.76 (m, 1H); 13C-NMR: δ 85.8, 92.4, 121.4, 120.0, 122.0, 122.6, 128.0 (2C), 128.3, 131.2 (2C),
137.8, 147.9, 151.6.
2-Methyl-4-phenyl-3-butyn-2-ol (5a). Yellow solid. m.p. 53–54 °C (lit.[67] 53.5–54.5 °C). 1H-NMR: δ
13
1.61 (s, 6H), 2.01 (s, 1H), 7.27–7.28 (m, 3H), 7.38–7.41 (m, 2H); C-NMR: δ 31.8 (2C), 65.7, 82.1,
104.1, 122.3, 127.8 (2C), 127.9, 131.2 (2C).
2-Methyl-4-(4’-cyano)phenyl-3-butyn-2-ol (5b) [68]. Yellow solid. m.p. 69–70 °C (lit.[69]
1
68.5–69.5 °C). H-NMR: δ 1.62 (s, 6H), 2.12 (s, 1H), 7.47 (d, J = 6.4 Hz, 2H), 7.57 (d, J = 6.4 Hz,
2H); 13C-NMR: δ 31.6 (2C), 65.7, 80.6, 98.0, 111.3, 118.1, 127.3, 131.5 (2C), 131.7 (2C).
1
2-Methyl-4-(4’-methoxy)phenyl-3-butyn-2-ol (5c) [70]. Yellow oil. H-NMR: δ 1.59 (s, 6H), 2.24 (s,
1H), 3.76 (s, 3H), 6.79 (d, J = 8.0 Hz, 2H), 7.31 (d, J = 8.0 Hz, 2H); 13C-NMR: δ 31.8 (2C), 55.3, 65.6,
81.8, 92.3, 113.5 (2C), 114.5, 132.5 (2C), 158.7.
1
2-Methyl-4-(4’-acetyl)phenyl-3-butyn-2-ol (5d) [70]. Yellow oil. H-NMR: δ 1.59 (s, 6H), 2.53 (s,
3H), 2.83 (s, 1H), 7.40 (d, J = 6.8 Hz, 2H), 7.81 (d, J = 6.8 Hz, 2H); 13C-NMR: δ 26.9, 31.5 (2C), 65.4,
81.0, 97.1, 127.3, 127.7 (2C), 131.2 (2C), 135.5, 196.6.
1
2-Methyl-4-(4’-nitro)phenyl-3-butyn-2-ol (5e). Brown solid. m.p. 100–102 °C (lit.[71] 102 °C). H-
NMR: δ 1.62 (s, 6H), 2.09 (s, 1H), 7.49 (d, J = 7.6 Hz, 2H), 8.14 (d, J = 7.6 Hz, 2H); 13C-NMR: δ 31.5
(2C), 65.7, 80.4, 99.8, 123.1 (2C), 129.3, 131.9 (2C), 146.5.

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1
2-Methyl-4-(4’-chloro)phenyl-3-butyn-2-ol (5f). White solid. m.p. 55–56 °C (lit.[72] 55–57 °C). H-
NMR: δ 1.60 (s, 6H), 2.11 (s, 1H), 7.25 (d, J = 8.4 Hz, 2H), 7.31 (d, J = 8.4 Hz, 2H); 13C-NMR: δ 31.7
(2C), 65.7, 81.0, 94.5, 120.8, 128.2 (2C), 132.4 (2C), 133.8.
1
2-Methyl-4-(2-thienyl)-3-butyn-2-ol (5g). Off-white solid. m.p. 56–57 °C (lit.[73] 54 °C). H-NMR: δ
1.58 (s, 6H), 2.51 (s, 1H), 6.91–6.93 (m, 1H), 7.14–7.15 (m, 1H), 7.19–7.21 (m, 1H); 13C-NMR: δ 31.6
(2C), 65.7, 75.4, 97.3, 122.2, 126.5, 126.6, 131.5.
1
2-Methyl-4-(3-thienyl)-3-butyn-2-ol (5h). Brown solid. m.p. 54–56 °C (lit.[74] 56 °C). H-NMR: δ
1.61 (s, 6H), 2.12 (s, 1H), 7.08–7.09 (m, 1H), 7.24–7.26 (m, 1H), 7.41–7.42 (m, 1H); 13C-NMR: δ 31.8
(2C), 65.7, 77.3, 93.2, 124.9, 128.2, 129.4.
1
2-Methyl-4-(2-pyridyl)-3-butyn-2-ol (5i). Off-white solid. m.p. 60–61 °C (lit.[25] 61 °C). H-NMR: δ
1.59 (s, 6H), 2.95 (s, 1H), 7.11–7.15 (m, 1H), 7.29–7.32 (m, 1H), 7.52–7.57 (m, 1H), 8.47–8.49 (m,
1H); 13C-NMR: δ 31.4 (2C), 64.9, 80.9, 94.6, 122.4, 126.6, 135.5, 142.3, 148.9.
1
2-Methyl-4-(3-pyridyl)-3-butyn-2-ol (5j). Yellow solid. m.p. 55–56 °C (lit.[25] 53 °C). H-NMR: δ
1.58 (s, 6H), 2.00 (s, 1H), 7.18–7.22 (m, 1H), 7.64–7.67 (m, 1H), 8.44–8.45 (m, 1H), 8.71 (s, 1H); 13C-
NMR: δ 31.6 (2C), 64.9, 78.1, 98.3, 120.0, 122.8, 138.4, 147.3, 151.3.
1
3-Phenyl-2-propyn-1-ol (5k) [75]. Yellow oil. H-NMR: δ 2.87 (s, 1H), 4.50 (s, 2H), 7.27–7.33 (m,
3H), 7.42–7.45 (m, 2H); 13C-NMR: δ 51.4, 85.3, 87.1, 123.1, 127.8 (2C), 127.9, 131.1 (2C).
3-(4’-Cyano)phenyl-2-propyn-1-ol (5l) [76]. Off-white solid. m.p. 89–91 °C (lit.[77] 87.5–88 °C). 1H-
13
NMR: δ 2.01 (s, 1H), 4.50 (s, 2H), 7.48 (d, J = 6.4 Hz, 2H), 7.57 (d, J = 6.4 Hz, 2H); C-NMR: δ
51.6, 83.9, 91.6, 111.5, 118.0, 127.1, 131.5 (2C), 131.7 (2C).
1
4-(3-Hydroxy-1-propynyl)acetophenone (5m). Yellow solid. m.p. 80–81 °C (lit.[78] 80–81 °C). H-
NMR: δ 2.55 (s, 3H), 2.80 (s, 1H), 4.90 (s, 2H), 7.43 (d, J = 8.4 Hz, 2H), 7.82 (d, J = 8.4 Hz, 2H); 13C-
NMR: δ 26.9, 51.5, 84.4, 90.7, 127.1, 127.8 (2C), 131.2 (2C), 135.7, 196.8.
3-(4’-Nitro)phenyl-2-propyn-1-ol (5n). Yellow solid. m.p. 96–97 °C (lit.[79] 95–96.5 °C). 1H-NMR: δ
13
1.95 (s, 1H), 4.52 (s, 2H), 7.54 (d, J = 8.0 Hz, 2H), 8.15 (d, J = 8.0 Hz, 2H); C-NMR: δ 51.6, 83.7,
92.4, 123.2 (2C), 129.0, 131.9 (2C), 146.6.
3-(4’-Chlorophenyl)-2-propyn-1-ol (5o). Yellow solid. m.p. 77–79 °C (lit.[72] 78.5–79 °C). 1H-NMR:
δ 2.11 (s, 1H), 4.47 (s, 2H), 7.25 (d, J = 8.8 Hz, 2H), 7.33 (d, J = 8.8 Hz, 2H); 13C-NMR: δ 51.7, 84.5,
88.0, 120.6, 128.2 (2C), 132.4 (2C), 134.1.
1
3-(2’-Thiophenyl)-2-propyn-1-ol (5p) [64]. Pale yellow oil. H-NMR: δ 2.17 (s, 1H), 4.50 (s, 2H),
6.95–6.97 (m, 1H), 7.20–7.21 (m, 1H), 7.25–7.26 (m, 1H); 13C-NMR: δ 51.8, 78.8, 91.0, 122.0, 126.6,
127.0, 131.9.

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1
3-(3’-Thiophenyl)-2-propyn-1-ol (5q) [54]. Brown oil. H-NMR: δ 3.06 (s, 1H), 4.46 (s, 2H),
7.06–7.08 (m, 1H), 7.19–7.24 (m, 1H), 7.41–7.42 (m, 1H); 13C-NMR: δ 51.4, 80.6, 86.8, 121.1, 124.9,
128.6, 129.3.
3-(2-Pyridyl)-2-propyn-1-ol (5r). White solid. m.p. 83–84 °C (lit.[80] 82 °C). 1H-NMR: δ 2.43 (s, 1H),
4.53 (s, 2H), 7.19–7.22 (m, 1H), 7.39–7.41 (m, 1H), 7.60–7.64 (m, 1H), 8.50–8.51 (m, 1H); 13C-NMR:
δ 51.3, 84.1, 88.3, 122.7, 126.8, 136.0, 142.2, 149.2.
3-(3-Pyridyl)-2-propyn-1-ol (5s). White solid. m.p. 101–102 °C (lit.[81] 99–100 °C). 1H-NMR: δ 2.08
(s, 1H), 4.49 (s, 2H), 7.23–7.36 (m, 1H), 7.70–7.74 (m, 1H), 8.47–8.48 (m, 1H), 8.74–8.75 (m, 1H);
13C-NMR: δ 51.0, 81.3, 92.0, 119.9, 122.9, 138.5, 147.6, 151.4.
1
4-Phenyl-3-butyn-1-ol (5t) [82]. Light brown oil. H-NMR: δ 1.84 (t, J = 6.2 Hz, 1H), 2.70 (t,
13
J = 6.2 Hz, 2H), 3.82 (q, J = 6.2 Hz, 2H), 7.26–7.32 (m, 3H), 7.39–7.44 (m, 2H); C-NMR: δ 23.5,
60.9, 82.1, 86.5, 123.3, 127.7, 128.1 (2C), 131.5 (2C).
4-(4’-Methoxy)phenyl-3-butyn-1-ol (5u). Pale yellow solid. m.p. 58–59 °C (lit.[83] 61 °C). 1H-NMR: δ
1.90 (br, 1H), 2.65 (t, J = 6.1 Hz, 2H), 3.77 (t, J = 6.1 Hz, 2H), 6.80 (d, J = 8.6 Hz, 2H), 7.32 (d,
J = 8.6 Hz, 2H); 13C-NMR: δ 23.6, 55.1, 61.1, 81.9, 84.8, 113.7 (2C), 115.4, 132.8 (2C), 159.1.
1
4-(4’-Cyano)phenyl-3-butyn-1-ol (5v) [53]. Pale yellow solid. m.p. 80–81 °C. H-NMR: δ 1.97 (br,
1H), 2.69 (t, J = 6.2 Hz, 2H), 3.81 (t, J = 6.2 Hz, 2H), 7.44 (d, J = 8.4 Hz, 2H), 7.54 (d, J = 8.4 Hz,
2H); 13C-NMR: δ 23.6, 60.6, 80.6, 91.8, 110.8, 118.3, 128.4, 131.7 (2C), 132.0 (2C).
4-(4-Hydroxy-1-butynyl)acetophenone (5w). Pale yellow solid. m.p. 75–77 °C (lit.[53] 74–76 °C). 1H-
NMR: δ 2.00 (br, 1H), 2.56 (s, 3H), 2.69 (t, J = 6.2 Hz, 2H), 3.81 (t, J = 6.2 Hz, 2H), 7.45 (d,
J = 8.2 Hz, 2H), 7.85 (d, J = 8.2 Hz, 2H); 13C-NMR: δ 23.7, 26.4, 60.8, 81.4, 90.5, 128.0 (2C), 128.4,
131.6 (2C), 135.7, 197.4.
1
4-(2-Thiophenyl)-3-butyn-1-ol (5x) [54]. Light brown oil. H-NMR: δ 1.93 (br, 1H), 2.69 (t,
J = 6.2 Hz, 2H), 3.79 (t, J = 6.2 Hz, 2H), 6.92 (dd, J = 5.1, 3.6 Hz, 1H), 7.14 (d, J = 3.6 Hz, 1H), 7.18
(d, J = 5.2 Hz, 1H); 13C-NMR: δ 24.0, 60.9, 75.4, 90.5, 123.3, 126.2, 126.7, 131.4.
1
4-(2-Pyridyl)-3-butyn-1-ol (5y) [25]. Light brown oil. H NMR: δ 2.72 (t, J = 6.0 Hz, 2H), 3.06 (br,
1H), 3.87 (t, J = 6.0 Hz, 2H), 7.18–7.25 (m, 1H), 7.39 (d, J = 7.8 Hz, 1H), 7.64 (td, J = 7.8, 2.0 Hz,
1H), 8.54 (d, J = 5.0 Hz, 1H); 13C-NMR: δ 23.3, 59.9, 80.7, 88.4, 122.2, 126.4, 136.0, 142.7, 148.8.
3.3. General procedure for recycling of nanosized MCM-41-Pd
Under a nitrogen atmosphere, a 50 mL Schlenk tube was charged with NS-MCM-41-Pd (50 mg,
7.5 × 10-3 mmol-Pd), CuI (2.9 mg, 1.5 × 10-2 mmol), PPh3 (3.9 mg, 1.5 × 10-2 mmol), Et3N (15 mL),
aryl halide (7.5 mmol), and terminal alkyne (8.3 mmol; in the case of 4b, 11.3 mmol was used). The

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mixture was stirred at 50 °C for 3 h (6 h for Entry 2) and then cooled to room temperature. Recovery
of NS-MCM-41-Pd was achieved by centrifugation and successive washes with THF, H2O, and THF
(2 × 40 mL each washing). The solid was then dried under vacuum overnight and used for the next run.
4. Conclusions
In conclusion, NS-MCM-41-Pd is a highly efficient and recyclable catalyst for the coupling of a
wide variety of aryl and heteroaryl halides with terminal alkynes, requiring catalyst loadings as low as
0.01 mol% for a single run. The NS-MCM-41-Pd catalyst also exhibited excellent reusability when a
catalyst loading of only 0.1 mol% was employed for the recycling studies. The results of this study
demonstrate the usefulness of anchored palladium bipyridyl complex on mesoporous silica as a
heterogeneous catalyst in cross-coupling reactions.
Acknowledgements
This research was financially supported by the National Science Council of Taiwan (NSC95-2113-
M-027-001).
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Sample Availability: Samples of the compounds are available from the authors.
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