Efficient and reusable CuI/1,10-phenanthroline-catalyzed oxidative decarboxylative homocoupling of arylpropiolic acids in aqueous DMF

Article abstract of DOI:10.1002/ejoc.201402416

An efficient method for synthesis of 1,3-diynes through the CuI/1,10-phenanthroline-catalyzed oxidative decarboxylative homocoupling of aryl pioprolic acids in aqueous DMF has been developed. The catalytic system was suitable for a variety of arylpropiolic acids, and the corresponding 1,3-diynes could be prepared in high yields. The catalytic system was recovered from the organic products by filtration and its aqueous DMF filtrate retained good activity even after at least four cycles of use.

Full text of DOI:10.1002/ejoc.201402416

Job/Unit: O42416
/KAP1
Date: 24-06-14 11:11:04
Pages: 7
FULL PAPER
DOI: 10.1002/ejoc.201402416
Efficient and Reusable CuI/1,10-Phenanthroline-Catalyzed Oxidative
Decarboxylative Homocoupling of Arylpropiolic Acids in Aqueous DMF
De-Xian Liu,[a] Fei-Long Li,[a] Hong-Xi Li,*[a] Wei-Jie Gong,[a] Jun Gao,[a] and
Jian-Ping Lang*[a,b]
Keywords: Synthetic methods / Oxidation / Alkynes / C–C coupling / Green chemistry
An efficient method for synthesis of 1,3-diynes through the
CuI/1,10-phenanthroline-catalyzed oxidative decarboxyl-
ative homocoupling of aryl pioprolic acids in aqueous DMF
has been developed. The catalytic system was suitable for a
variety of arylpropiolic acids, and the corresponding 1,3-
diynes could be prepared in high yields. The catalytic system
was recovered from the organic products by filtration and its
aqueous DMF filtrate retained good activity even after at
least four cycles of use.
1,3-diynes from iodoarenes and propiolic acid using a Son-
ogashira reaction followed by Pd-catalyzed decarboxylative
homocoupling in the presence of Ag2CO3 at 130 °C
(Scheme 1, Eq. C).[16] Fu et al. reported that copper-cata-
lyzed decarboxylative coupling of potassium alkynyl carb-
oxylates with 1,1-dibromo-1-alkenes could produce 1,3-di-
ynes (Scheme 1, Eq. D).[17] However, the coupling reactions
mentioned above were all carried out in organic solvents,
and/or required the addition of the oxidant (e.g. Ag2CO3)
and high excesses of base. From a sustainable chemistry
viewpoint, the use of water or aqueous solvents instead of
volatile organic solvents is particularly important. There-
fore, the development of simple inorganic copper cata-
lysts[18] that can facilitate the decarboxylative coupling reac-
tion of propiolic acids in aqueous media or aqueous organic
solvent mixtures using air as an oxidant agent would be
highly desirable.
Although C–C bond formation could be facilitated in
aqueous media or in aqueous solvents,[19] homocouplings
of terminal alkynes proceed more slowly in an aqueous me-
dium than in organic solvents, which may be due to the fact
that most organic alkynes are insoluble in water. To the best
of our knowledge, there have been only two reports detail-
ing the synthesis of 1,3-diynes by oxidative homocoupling
reactions of terminal alkynes in water. For instance, Tsai et
al. reported that CuSO4·5H2O/cationic 2,2-bipridyl system
or cationic 2,2-bipridyl/PdII/CuI systems catalyze the
homocoupling of terminal alkynes in water using I2 or air
as the oxidant.[20,21] The alkynyl carboxylic acid, which con-
tains hydrophilic carboxylate group,[22] can dissolve in water
or aqueous organic solvents. Could a copper catalyst cata-
lyze decarboxylative homocoupling of alkynyl carboxylic
acids to produce 1,3-diynes in aqueous organic solvents or
even aqueous media? Very recently, we have developed a
ligand-free Cu-catalyzed oxidative decarboxylative homo-
Introduction
Conjugated 1,3-diynes are important building blocks
that occur widely in natural products,[1] industrial and phar-
maceutical intermediates,[2] as well as in electronic and op-
tical materials, and elsewhere.[3] Since Glaser reported the
synthesis of 1,3-diynes by CuI-catalyzed oxidative homo-
coupling reaction of terminal alkynes in 1869,[4] copper-cat-
alyzed oxidative homocoupling reactions of terminal alk-
ynes or cross-coupling reactions of terminal alkynes with 1-
haloalkynes have been one of the most established method-
ologies for preparing both symmetric and unsymmetrical
1,3-diynes in organic synthesis.[5–7] Usually, terminal alk-
ynes are used as substrates in these methods.[8–13] The alk-
ynyl carboxylic acid, which is common, stable and easy to
handle and store, may be an effective alternative. 1,3-Diyne
derivatives could also be obtained by the oxidative decar-
boxylative homocoupling of arylpropiolic acids. For exam-
ple, Yu, Jiao et al. reported that the CuI/1,10-phenanthrol-
ine catalytic system could catalyze decarboxylative cross-
coupling of propiolic acids with terminal alkynes to pro-
duce 1,3-diynes in moderate yields (Scheme 1, Eq. A) at
120 °C.[14] Lee et al. reported that 1,3-diynes could be ob-
tained by the “one-pot” reaction of aryl iodides with propi-
olic acid catalyzed by a Pd/Cu system (Scheme 1, Eq. B).[15]
Kim et al. reported one-pot synthesis of 1,4-disubstituted
[a] College of Chemistry, Chemical Engineering and Materials
Science, Soochow University,
Suzhou 215123, P. R. China
E-mail: jplang@suda.edu.cn
http://www.suda.edu.cn
[b] State Key Laboratory of Organometallic Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences,
Shanghai 210032, P. R. China
http://www.sioc.ac.cn
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201402416.
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1

Job/Unit: O42416
/KAP1
Date: 24-06-14 11:11:04
Pages: 7
D.-X. Liu, F.-L. Li, H.-X. Li, W.-J. Gong, J. Gao, J.-P. Lang
FULL PAPER
Scheme 1. The synthesis of 1,3-diynes by transition metal-catalyzed decarboxylative coupling reactions.
coupling of arylpropiolic acids (Scheme 1, Eq. E) at lower Other ligands L2–L6 were also evaluated (Table 1, Entries
reaction temperature (50 °C) using DMSO as a solvent and 10–14) although L1 proved to be the most effective. The
I2 as an oxidant agent.[23] These limitations prompted us to controlled reaction showed that the organic ligand was nec-
further investigate new convenient methodologies to gener- essary for such an oxidative decarboxylative homocoupling
ate 1,3-diynes. Herein, we report a new and efficient system reaction. The catalyst was inactive in the absence of L1
for preparing 1,3-diyne derivatives by oxidative decarbox- (Table 1, Entry 15). In the absence of CuI, L1 ligand failed
ylative homocoupling of arylpropiolic acids using CuI/1,10- to catalyze the oxidative decarboxylative homocoupling re-
phenanthroline as the catalyst system and air as the oxidant action even with increased loadings of base (Table 1, En-
in aqueous DMF. The components of this catalytic system tries 16 and 17). Several other copper salts were evaluated
could be conveniently and effectively reused for at least four as catalysts for the oxidative decarboxylative homocoupling
times.
of phenylpropiolic acid (Table 1, Entries 18–21); CuI was
superior to the other salts examined (Table 1, Entry 5).
Among a set of bases (e.g., KOH, Na2CO3, NaHCO3,
KHCO3, K2CO3) (Table 1, Entries 22–25), K2CO3 was
Results and Discussion
We chose phenylpropiolic acid (1a) as a model system to found to be optimal for carrying out the reaction in H2O/
optimize reaction conditions (Table 1). Initially, we carried DMF (Table 1, Entry 5).
out the reaction of 1a with CuI (10 mol-%), 1,10-phen-
We envisioned that catalyst loading may also have an im-
anthroline (L1, 20 mol-%), K2CO3 (1.0 equiv.) in 2 mL of pact on the catalytic activity. Not surprisingly, the product
H2O at 100 °C. The mixture gradually turned into a homo- yield decreased from 99% to 89% when the catalyst loading
geneous blue solution, implying that arylpropiolic acid was further reduced from 10 mol-% to 5 mol-% in H2O/
could be dissolved in water in the presence of base. After DMF (Table 1, Entries 5 and 27). The loading of the L1
20 h, desired product 1,4-diphenylbuta-1,3-diyne (2a) could ligand might also affect catalytic activity. The product yield
be obtained in 28% yield coupled with ethynylbenzene (3a) decreased slightly from 99% to 96% when L1 loading was
(5% yield) (Table 1, Entry 1). This preliminary result im- changed from 20 mol-% to 15 mol-% at 100 °C (Table 1,
plied that CuI/L1 might initiate the oxidative decarbox- Entries 5 and 28). In addition, the reaction temperature in-
ylative homocoupling of 1a using air as an oxidant in water fluenced the coupling reaction. When the reaction tempera-
to produce 2a. However, the relatively low yield showed that ture was decreased from 100 °C to 90 °C, the yield of 2a
H2O may not be the optimal solvent. When the reactions was decreased slightly from 99% to 96% (Table 1, Entry
were carried out in different organic solvents such as DMF, 26).
DMSO and CH3CN, the yield of decarboxylation product
On the basis of these optimization experiments, the opti-
3a increased dramatically but the yield of coupling product mized reaction conditions were identified as follows: CuI
2a decreased (20% for DMF, 13% for DMSO and 9% for (10 mol-%) as the catalyst, L1 (20 mol-%) as the labile li-
MeCN) (Table 1, Entries 2–4). Considering the structure of gand, K2CO3 (1.0 equiv.) as the base, and H2O/DMF (v/v,
the arylpropiolic acid containing the hydrophilic carboxyl- 1:1) as the reaction solution. With these conditions in hand,
ate group and the hydropholic aryl group, the aqueous or- we next began to examine the scope of the reaction. It was
ganic solvent mixtures may be more suitable for oxidative found that a variety of functional groups could be tolerated
decarboxylative homocoupling of arylpropiolic acid. When on the arylpropiolic acid including Me, Ph, MeO, MeCO, F,
the reactions were performed in H2O/DMF (v/v = 1:1) mix- Cl, tBu substituent groups. As shown in Table 2, oxidative
tures, complete conversion of 1a into 2a was achieved decarboxylative homocoupling reactions proceeded well for
within 20 h in air at 100 °C (Table 1, Entry 5). However, the all substrates examined and desired products were isolated
catalyst showed lower activity in aqueous DMSO or in good to excellent yields. It appears that the p-, m-substi-
MeCN. As shown in Table 1, the optimal ratio of H2O and tuted groups on the phenyl moiety of arylpropiolic acids do
DMF was determined to be 1:1 (Table 1, Entries 8 and 9). not hamper the coupling reaction. Reactions of 3-(p-tolyl)-
2
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O42416
/KAP1
Date: 24-06-14 11:11:04
Pages: 7
Homocoupling of Arylpropiolic Acids
Table 1. Optimizing the reaction conditions for the decarboxylative such as MeCO, F, and Cl (Table 2, Entries 9–11). In ad-
homocoupling reaction of phenylpropiolic acid.[a]
dition, the decarboxylative homocoupling of heteroatom-
containing arylpropiolic acid also proceeded efficiently
using the described catalytic system. For instance, couplings
involving 3-(thiophen-2-yl)propiolic acid afforded antici-
pated product 1,4-di(thiophen-2-yl)buta-1,3-diyne in 91%
yield (Table 2, Entry 15).
Entry Cat.
Ligand Base
Solvent
Yield[b] [%]
2a/3a
Table 2. Synthesis of 1,4-disubstituted-1,3-diynes catalyzed in aque-
ous DMF.[a]
1
2
3
4
5
6
7
8
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
L1
L1
L1
L1
L1
L1
L1
L1
L1
L2
L3
L4
L5
L6
K2CO3
H2O
DMF
28:5
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
KOH
20:86
13:94
9:94
DMSO
CH3CN
H2O/DMF[c]
99:0
H2O/DMSO[c] 96:0
H2O/MeCN[c] 14:78
H2O/DMF[d]
H2O/DMF[e]
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
97:0
46:0
95:0
98:0
49:12
15:48
trace:8
trace/27
0:0
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26[g]
27[h]
28[i]
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
L1
H2O/DMF[c,f] 0:0
CuBr
CuCl
CuCl2
Cu(OAc)2
CuI
CuI
CuI
CuI
CuI
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
97:0
86:0
90:0
94:0
97:0
98:0
96:0
94:0
96:0
89:0
96:0
Na2CO3 H2O/DMF[c]
KHCO3 H2O/DMF[c]
NaHCO3 H2O/DMF[c]
K2CO3
K2CO3
K2CO3
H2O/DMF[c]
H2O/DMF[c]
H2O/DMF[c]
CuI
CuI
[a] Reaction conditions: phenylpropiolic acid (0.2 mmol), Cat.
(10 mol-%), ligand (20 mol-%), solvent (2 mL), base (0.2 mmol) at
100 °C, for 20 h, in air. [b] GC yields. [c] Vwater/Vorganic solvent = 1:1.
[d] Vwater/VDMF = 2:1. [e] Vwater/VDMF = 3:1. [f] K2CO3 (0.4 mmol).
[g] Reaction temperature: 90 °C. [h] 5 mol-% of CuI. [i] 15 mol-%
of L1.
[a] Reaction conditions: arylpropiolic acid (0.2 mmol), CuI
(10 mol-%), L1 (20 mol-%), K2CO3 (0.2 mmol), H2O/DMF (1 mL/
1 mL), 100 °C, 20 h, in air. [b] Isolated yields.
propiolic acid, 3-(m-tolyl)propiolic acid or 3-(3,5-dimeth-
ylphenyl)propiolic acid produced the corresponding prod-
ucts in high yields (86%–90%). However, this reaction was
sensitive to phenyl ring o-substitution and good yields were
Being insoluble in aqueous DMF, the desired products
obtained for 3-(o-tolyl)propiolic acid (80% yield; entry 2), could be readily separated by filtration. Consequently, the
3-(2-methoxyphenyl)propiolic acid (72% yield; Table 2, En- remaining aqueous DMF solution could be recycled and
try 6) and 2,4,6-trimethyl phenylpropiolic acid (74% yield; applied to fresh coupling reactions; this aspect of the cur-
Table 2, Entry 13), which may be ascribed to steric hin- rent reaction is important from practical and industrial
drance encountered during the course of homocoupling. utilization viewpoints. 3-Phenylpropiolic acid (1a) was used
The electronic nature of substituents on the arylpropiolic as a representative coupling partner in experiments to check
acid were also found to have an influence on the oxidative the amenability of this system to reuse. As shown in
decarboxylative homocoupling reactions. Couplings with Table 3, the oxidative decarboxylative homocoupling reac-
electron-deficient p-substituted phenylpropiolic acids were tion of 1a with 10 mol-% catalyst loading in the presence
found to proceed in higher yields than those with more elec- of L1 (20 mol-%) led to the formation of 2a in 90% yield
tron rich propiolic acids. For example, lower yields were (by filtration) under the optimized reaction conditions. Fol-
obtained using arylpropiolic acids bearing electron-donat- lowing completion of the first cycle, the organic product
ing groups (Me, MeO, tBu, Ph) (Table 2, Entries 4, 5, 7 and was isolated by filtration and the remaining aqueous solu-
8) relative to those bearing electron-withdrawing groups tion was recharged with base and 1a for a second cycle of
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3

Job/Unit: O42416
/KAP1
Date: 24-06-14 11:11:04
Pages: 7
D.-X. Liu, F.-L. Li, H.-X. Li, W.-J. Gong, J. Gao, J.-P. Lang
FULL PAPER
coupling. A third cycle of system application afforded a catalytic system can also be reused several times and has
59% yield for the desired coupling product indicating that potential for use in industrial applications. The reaction can
the use of this catalytic system may meet the goal of green be carried out under mild conditions and avoids the use of
chemistry.
unstable terminal alkynes, haloalkynes and alkynyl metal
reagents, thereby offering numerous opportunities for the
application of this methodology in the synthesis of other
useful compounds. Such studies are currently under way in
our laboratory.
Table 3. Reuse of CuI/L1-catalyzed oxidative decarboxylative
homocoupling of phenylpropiolic acid.[a]
Cycle
Yield [%][b]
Initial run
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 5
90
90
87
59
21
trace
Experimental Section
General Procedure for Decarboxylative Homocoupling of Arylprop-
iolic Acids in Aqueous DMF: A mixture of arylpropiolic acid
(0.2 mmol), K2CO3 (0.2 mmol) and H2O (1.0 mL) was stirred at
room temperature for 1 min. To this solution were then added
DMF (1.0 mL), CuI (10 mol-%), and 1,10-phenanthroline (20 mol-
%). The resulting mixture was stirred at 100 oC under air for 20 h.
After cooling to ambient temperature, the mixture was extracted
with diethyl ether. The extract was then dried with Na2SO4. The
solvent was removed under reduced pressure. The crude product
was purified by flash silica gel column chromatography.
[a] Reaction conditions: phenylpropiolic acid (0.2 mmol), CuI
(10 mol-%), L1 (20 mol-%), K2CO3 (0.2 mmol), H2O/DMF (1 mL/
1 mL), 100 °C, 20 h, under air. [b] Isolated yield.
Although the exact mechanism of the oxidative decar-
boxylative homocoupling reaction of arylpropiolic acid is
unknown at this stage, a plausible mechanism has been pro-
posed based on the reported mechanism for homocoupling
reactions of terminal alkynes[5n,6d,24] and decarboxylative
reactions.[25] We envision that initially, reaction of [{(L1)-
Cu}(μ-I)]2 with arylpropiolic acid yields carboxylate inter-
mediate I in the presence of K2CO3. Secondly, intermediate
I may be converted into [(L1)CuI-acetylide] intermediate II
through decarboxylation of I. Thirdly, intermediate II can
be converted into intermediate III by oxidation of the CuI
centre of intermediate II by O2 in air. Finally, intermediate
III may undergo an inner sphere electron transfer breaking
the Cu–C bonds and forming the C–C bond to produce
Csp–Csp homocoupling product and [{(L1)Cu}(μ-I)]2,
thereby furnishing the completed catalytic cycle (Scheme 2).
1,4-Diphenylbuta-1,3-diyne (2a):[21] White solid, m.p. 83–84 °C. H
NMR (400 MHz, CDCl3): δ = 7.54–7.52 (m, 4 H), 7.39–7.31 (m, 6
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 132.5, 129.2, 128.5,
121.8, 81.6, 73.9 ppm.
1
1,4-Di(o-tolyl)-buta-1,3-diyne (2b):[21] White solid, m.p. 74–75 °C.
1H NMR (400 MHz, CDCl3): δ = 7.50 (d, J = 8.0 Hz, 2 H), 7.28–
7.25 (m, 2 H), 7.23–7.21 (m, 2 H), 7.16 (q, 2 H), 2.50 (s, 6 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 141.6, 132.9, 129.6, 129.1, 125.7,
121.7, 81.1, 76.7, 20.8 ppm.
1,4-Di(m-toly)buta-1,3-diyne (2c):[21] White solid, m.p. 68–69 °C. 1H
NMR (400 MHz, CDCl3): δ = 7.34–7.32 (m, 4 H), 7.24–7.16 (m, 4
H), 2.34 (s, 6 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 138.2,
133.0, 130.1, 129.6, 128.3, 121.6, 81.6, 76.7, 73.6, 21.2 ppm.
1,4-Di(p-toly)buta-1,3-diyne (2d):[21] White solid, m.p. 135–137 °C.
1H NMR (400 MHz, CDCl3): δ = 7.41 (d, J = 8.0 Hz, 4 H), 7.14
(d, J = 8.0 Hz, 4 H), 2.36 (s, 6 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 139.5, 132.4, 129.2, 118.8, 81.5, 73.4, 21.6 ppm.
1,4-Bis(4-methoxyphenyl)buta-1,3-diyne (2e):[21] White solid, m.p.
139–140 °C. 1H NMR (400 MHz, CDCl3): δ = 7.46 (d, J = 8.0 Hz,
4 H), 6.85 (d, J = 8.0 Hz, 4 H), 3.81 (s, 6 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 160.2, 134.0, 114.1, 113.9, 81.2, 72.9,
55.3 ppm.
1,4-Bis(2-methoxyphenyl)buta-1,3-diyne (2f):[21] White solid, m.p.
1
138–139 °C. H NMR (400 MHz, CDCl3): δ = 7.46 (dd, J = 4.0, J
= 8.0 Hz, 2 H), 6.85 (td, J = 8.0 Hz, 2 H), 6.93–6.87 (m, 4 H), 3.89
(s, 6 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 161.3, 134.4,
130.6, 120.5, 111.3, 110.7, 78.7, 77.9, 55.8 ppm.
Scheme 2. Proposed catalytic cycle for the decarboxylative homo-
coupling.
1,4-Bis(4-tert-butylphenyl)buta-1,3-diyne (2g):[23] White solid, m.p.
210–211 °C. 1H NMR (400 MHz, CDCl3): δ = 7.46 (d, J = 8.0 Hz,
4 H), 7.35 (d, J = 8.0 Hz, 4 H), 1.31 (s, 18 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 152.6, 132.3, 125.5, 118.8, 81.5, 73.5, 34.9,
31.1 ppm.
Conclusions
In summary, we have developed an efficient method of
synthesis of 1,3-diynes via CuI/1,10-phenanthroline-cata-
lyzed oxidative decarboxylative homocoupling reaction of
arylpropiolic acids in aqueous DMF using air as the oxi-
dant. This approach tolerates a variety of functional groups
1,4-Bis(biphenyl-4-yl)buta-1,3-diyne (2h):[6h] Yellow solid, m.p. 91–
93 °C. 1H NMR (400 MHz, CDCl3): δ = 7.62–7.58 (m, 12 H), 7.47–
7.44 (m, 4 H), 7.39–7.36 (m, 2 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 141.9, 140.1, 132.9, 128.9, 127.9, 127.1, 127.0, 120.6,
and fails to generate much in the way of by-products. The 81.8, 74.6 ppm.
4
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O42416
/KAP1
Date: 24-06-14 11:11:04
Pages: 7
Homocoupling of Arylpropiolic Acids
1,4-Bis(4-fluorophenyl)buta-1,3-diyne (2i):[21] White solid, m.p. 186–
188 °C. 1H NMR (400 MHz, CDCl3): δ = 7.53–7.49 (m, 4 H), 7.04
(q, 4 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 164.3, 161.8,
134.6, 134.5, 117.8, 117.8, 116.0, 115.8, 80.4, 73.5 ppm.
1,4-Bis(4-chlorophenyl)buta-1,3-diyne (2j):[11b] White solid, m.p.
254–255 °C. 1H NMR (400 MHz, CDCl3): δ = 7.45 (d, J = 8.0 Hz,
4 H), 7.32 (d, J = 8.0 Hz, 4 H) ppm. Very insoluble in common
organic solvents.[11b]
Chem. 2006, 118, 1050; d) F. Bohlmann, T. Burkhardt, C.
Zdero, Naturally Occurring Acetylenes, Academic Press, Lon-
don, 1973.
a) A. Stütz, Angew. Chem. Int. Ed. Engl. 1987, 26, 320; Angew.
Chem. 1987, 99, 323; b) M. L. Lerch, M. K. Harper, D. J.
Faulkner, J. Nat. Prod. 2003, 66, 667; c) Y. Z. Zhou, H. Y. Ma,
H. Chen, L. Qiao, Y. Yao, J. Q. Cao, Y. H. Pei, Chem. Pharm.
Bull. 2006, 54, 1455; d) M. Ladika, T. E. Fisk, W. W. Wu, S. D.
Jons, J. Am. Chem. Soc. 1994, 116, 12093.
[2]
[3]
[4]
[5]
a) M. B. Nielsen, F. Diederich, Chem. Rev. 2005, 105, 1837; b)
J. Liu, J. W. Y. Lam, B. Z. Tang, Chem. Rev. 2009, 109, 5799.
a) C. Glaser, Ber. Dtsch. Chem. Ges. 1869, 2, 422; b) C. Glaser,
Ann. Chem. Pharm. 1870, 154, 137.
1,4-Bis(4-acetylphenyl)buta-1,3-diyne (2k):[21] White solid, m.p.
169–170 °C. 1H NMR (400 MHz, CDCl3): δ = 7.94 (d, J = 8.0 Hz,
4 H), 7.62 (d, J = 8.0 Hz, 4 H), 2.61 (s, 6 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 196.1, 136.1, 131.7, 127.3, 125.2, 80.9, 75.5,
25.7 ppm.
a) A. S. Hay, J. Org. Chem. 1960, 25, 1275; b) A. S. Hay, J. Org.
Chem. 1962, 27, 3320; c) E. Valenti, M. A. Pericàs, F. Serratosa,
J. Am. Chem. Soc. 1990, 112, 7405; d) J. Li, H. Jiang, Chem.
Commun. 1999, 2369; e) A. Sharifi, M. Mirzaei, M. R. Naimi-
Jamal, J. Chem. Res. Synop. 2002, 628; f) Y. Liao, R. Fathi, Z.
Yang, Org. Lett. 2003, 5, 909; g) J. S. Yadav, B. V. S. Reddy,
K. B. Reddy, K. U. Gayathri, A. R. Prasad, Tetrahedron Lett.
2003, 44, 6493; h) D. Rodríguez, L. Castedo, C. Saá, Synlett
2004, 377; i) H. F. Jiang, J. Y. Tang, A. Z. Wang, G. H. Deng,
S. R. Yang, Synthesis 2006, 1155; j) B. C. Ranu, S. Banerjee,
Lett. Org. Chem. 2006, 3, 607; k) M. F. Martínez-Esperón, D.
Rodríguez, L. Castedo, C. Saá, Tetrahedron 2006, 62, 3843; l)
X. Lu, Y. Zhang, C. Luo, Y. Wang, Synth. Commun. 2006, 36,
2503; m) B. C. Zhu, X. Z. Jiang, Appl. Organomet. Chem. 2007,
21, 345; n) K. Yamaguchi, K. Kamata, S. Yamaguchi, M. Kot-
ani, N. Mizuno, J. Catal. 2008, 258, 121; o) K. Kamata, S.
Yamaguchi, M. Kotani, K. Yamaguchi, N. Mizuno, Angew.
Chem. Int. Ed. 2008, 47, 2407; Angew. Chem. 2008, 120, 2441;
p) D. Li, K. Yin, J. Li, X. Jia, Tetrahedron Lett. 2008, 49, 5918.
a) B. Alcaide, P. Almendros, R. Carrascosa, R. Rodríguez-
Acebes, Eur. J. Org. Chem. 2008, 1575; b) F. Nador, L. Fortun-
ato, Y. Moglie, C. Vitale, G. Radivoy, Synthesis 2009, 4027; c)
S. Adimurthy, C. C. Malakar, U. Beifuss, J. Org. Chem. 2009,
74, 5648; d) L. Li, J. Wang, G. Zhang, Q. Liu, Tetrahedron
Lett. 2009, 50, 4033; e) P. Kuhn, A. Alix, M. Kumarraja, B.
Louis, P. Pale, J. Sommer, Eur. J. Org. Chem. 2009, 423; f) T.
Oishi, T. Katayama, K. Yamaguchi, N. Mizuno, Chem. Eur. J.
2009, 15, 7539; g) D. Wang, J. Li, N. Li, T. Gao, S. Hou, B.
Chen, Green Chem. 2010, 12, 45; h) Q. Zheng, R. Hua, Y. Wan,
Appl. Organomet. Chem. 2010, 24, 314; i) X. Meng, C. Li, B.
Han, T. Wang, B. Chen, Tetrahedron 2010, 66, 4029; j) K. Bala-
raman, V. Kesavan, Synthesis 2010, 3461.
1,4-Bis(3,5-dimethylphenyl)buta-1,3-diyne (2l):[23] White solid, m.p.
1
96–97 °C. H NMR (400 MHz, CDCl3): δ = 7.15 (br.s, 4 H), 7.00
(br.s, 2 H), 2.29 (s, 12 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
138.0, 131.2, 130.1, 121.5, 81.7, 73.4, 21.1 ppm.
1,4-Bis(2,4,6-trimethylphenyl)buta-1,3-diyne (2m):[23] White solid,
1
m.p. 184–185 °C. H NMR (400 MHz, CDCl3): δ = 6.87 (s, 4 H),
2.45 (s, 12 H), 2.29 (s, 6 H) ppm. 13C NMR (100 MHz, CDCl3): δ
= 141.9, 138.8, 127.9, 119.1, 81.2, 80.8, 21.6, 21.2 ppm.
1,4-Di(naphthalen-1-yl)buta-1,3-diyne (2n):[21] Yellow solid, m.p.
174–176 °C. 1H NMR (400 MHz, CDCl3): δ = 8.43 (d, J = 12.0 Hz,
2 H), 7.89–7.86 (m, 4 H), 7.84–7.82 (m, 2 H), 7.65–7.61 (m, 2 H),
7.57–7.53 (m, 2 H), 7.47–7.43 (m, 2 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 133.9, 133.1, 132.1, 129.8, 128.5, 127.2, 126.7, 126.1,
125.2, 119.5, 80.9, 78.7 ppm.
1,4-Di(thiophen-2-yl)buta-1,3-diyne (2o):[16] White solid, m.p. 90–
91 °C. 1H NMR (400 MHz, CDCl3): δ = 7.35–7.32 (m, 4 H), 7.01–
6.99 (m, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 134.4, 128.9,
127.2, 121.9, 77.8, 76.6 ppm.
[6]
Typical Procedure for the Reuse of the Catalytic Aqueous DMF
Solution: The reaction was conducted by following the procedure
described above under optimized reaction conditions shown in
Table 2. After cooling to room temperature, the mixture was fil-
tered, and the remaining aqueous solution was then charged with
phenylpropiolic acid (0.2 mmol) and K2CO3 (0.2 mmol) for the
next cycle of reaction.
[7]
a) F. Alonso, T. Melkonian, Y. Moglie, M. Yus, Eur. J. Org.
Chem. 2011, 2524; b) S. Zhang, X. Liu, T. Wang, Adv. Synth.
Catal. 2011, 353, 1463; c) A. Kusuda, X.-H. Xu, X. Wang, E.
Tokunaga, N. Shibata, Green Chem. 2011, 13, 843; d) R.
Schmidt, R. Thorwirth, T. Szuppa, A. Stolle, B. Ondruschka,
H. Hopf, Chem. Eur. J. 2011, 17, 8129; e) T. Oishi, K. Yamagu-
chi, N. Mizuno, ACS Catal. 2011, 1, 1351; f) Y. N. Li, J. L.
Wang, L. N. He, Tetrahedron Lett. 2011, 52, 3485; g) K. Yin,
C. Li, J. Li, X. Jia, Green Chem. 2011, 13, 591; h) L. van Geld-
eren, G. Rothenberg, V. R. Calderone, K. Wilson, N. R. Shiju,
Appl. Organomet. Chem. 2013, 27, 23; i) M. H. Vilhelmsen, J.
Jensen, C. G. Tortzen, M. B. Nielsen, Eur. J. Org. Chem. 2013,
701; j) Y. G. Zhu, Y. A. Shi, Org. Biomol. Chem. 2013, 11, 7451.
a) X. J. Feng, Z. R. Zhao, F. Yang, T. N. Jin, Y. J. Ma, M. Bao,
J. Organomet. Chem. 2011, 696, 1479; b) S. V. Damle, D. Seo-
moon, P. H. Lee, J. Org. Chem. 2003, 68, 7085.
a) K. Sonogashira, Y. Tohda, N. Hagihara, Tetrahedron Lett.
1975, 16, 4467; b) R. Rossi, A. Carpita, C. Bigelli, Tetrahedron
Lett. 1985, 26, 523; c) Q. Liu, D. Burton, Tetrahedron Lett.
1997, 38, 4371; d) R. Roy, S. K. Das, F. Hernández-Mateo,
F. Santoyo-González, Z. Gan, Synthesis 2001, 1049; e) W. A.
Herrmann, V. P. W. Bohm, C. W. K. Gstottmayr, M. Grosche,
C. P. Reisinger, T. Weskamp, J. Organomet. Chem. 2001, 617–
618, 616; f) A. Lei, M. Srivastava, X. Zhang, J. Org. Chem.
2002, 67, 1969; g) I. J. S. Fairlamb, P. S. Bauerlein, L. R. Marri-
Supporting Information (see footnote on the first page of this arti-
cle): Copies of the 1H and 13C NMR spectra for the isolated prod-
ucts.
Acknowledgments
The authors are grateful for financial support by the National Nat-
ural Science Foundation of China (NSFC) (grant numbers
21171124, 21171125 and 21371126), by the State Key Laboratory
of Organometallic Chemistry, by the Shanghai Institute of Organic
Chemistry, and by the Chinese Academy of Sciences (grant number
201201006). J. P. Lang highly appreciates support by the Govern-
ment of Jiangsu Province (Qin-Lan Project), by the Jiangsu Higher
Education Institutions (Priority Academic Program Development,
“333” Project), and by the Soochow University (SooChow Scholar
Program). The authors also thank the reviewers and the Editor for
their useful comments.
[8]
[9]
[1] a) G. Zeni, R. B. Panatieri, E. Lissner, P. H. Menezes, A. L.
Braga, H. A. Stefani, Org. Lett. 2001, 3, 819; b) H. Yun, S. J.
Danishefsky, J. Org. Chem. 2003, 68, 4519; c) S. A. L. Shun,
R. R. Tykwinski, Angew. Chem. Int. Ed. 2006, 45, 1034; Angew.
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5

Job/Unit: O42416
/KAP1
Date: 24-06-14 11:11:04
Pages: 7
D.-X. Liu, F.-L. Li, H.-X. Li, W.-J. Gong, J. Gao, J.-P. Lang
FULL PAPER
son, J. M. Dickinson, Chem. Commun. 2003, 632; h) D. A.
Alonso, C. Nájera, M. A. Pacheco, Adv. Synth. Catal. 2003,
345, 1146; i) J. H. Li, Y. Liang, X. D. Zhang, Tetrahedron 2005,
61, 1903; j) J. H. Li, Y. Liang, Y. X. Xie, J. Org. Chem. 2005,
70, 4393; k) A. S. Batsanov, J. C. Collings, I. J. S. Fairlamb, J. P.
Holland, J. A. K. Howard, Z. Lin, T. B. Marder, A. C. Parsons,
R. M. Ward, J. Zhu, J. Org. Chem. 2005, 70, 703; l) W. Yin,
P. V. V. S. Sarma, J. Ma, D. Han, J. L. Chen, J. M. Cook, Tetra-
hedron Lett. 2005, 46, 6363.
b) S. Rui, L. Lei, Sci. China Chem. 2011, 54, 1670; c) N. Rodri-
guez, L. J. Goossen, Chem. Soc. Rev. 2011, 40, 5030; d) P. Hu,
M. Zhang, X. M. Jie, W. P. Su, Angew. Chem. Int. Ed. 2012,
51, 227; Angew. Chem. 2012, 124, 231; e) P. Hu, Y. P. Shang,
W. P. Su, Angew. Chem. Int. Ed. 2012, 51, 5945; Angew. Chem.
2012, 124, 6047.
[19] a) C. Liu, Y. X. Zhang, N. Liu, J. S. Qiu, Green Chem. 2012,
14, 2999; b) X. M. Wu, Y. B. Wu, Lett. Org. Chem. 2012, 9,
396; c) B. W. Xin, Y. H. Zhang, K. Cheng, J. Org. Chem. 2006,
71, 5725; d) L. F. Liu, Y. H. Zhang, B. W. Xin, J. Org. Chem.
2006, 71, 3994; e) R. P. Swatloski, A. E. Visser, W. M. Reichert,
G. A. Broker, L. M. Farina, J. D. Holbrey, R. D. Rogers, Chem.
Commun. 2001, 2070; f) S. Y. Shi, Y. H. Zhang, Green Chem.
2008, 10, 868; g) B. Basu, K. Biswas, S. Kundu, S. Ghosh,
Green Chem. 2010, 12, 1734; h) S. L. Mao, Y. Sun, G. A. Yu,
C. Zhao, Z. J. Han, J. Yuan, X. L. Zhu, Q. H. Yang, S. H. Liu,
Org. Biomol. Chem. 2012, 10, 9410; i) K. W. Anderson, S. L.
Buchwald, Angew. Chem. Int. Ed. 2005, 44, 6173; Angew.
Chem. 2005, 117, 6329.
[10] a) J. Gil-Moltó, C. Nájera, Eur. J. Org. Chem. 2005, 4073; b)
C. Chen, Z. Ai, J. Lin, X. Hong, C. Xi, Synlett 2006, 2454; c)
M. Shi, H. X. Qian, Appl. Organomet. Chem. 2006, 20, 771; d)
J. Yan, J. Wu, H. Jin, J. Organomet. Chem. 2007, 692, 3636; e)
J. Yan, F. Lin, Z. Yang, Synthesis 2007, 1301; f) F. Yang, X.
Cui, Y. N. Li, J. Zhang, G. R. Ren, Y. Wu, Tetrahedron 2007,
63, 1963; g) L. Zhou, H. Y. Zhan, H. L. Liu, H. F. Jiang, Chin.
J. Chem. 2007, 25, 1413; h) T. Kurita, M. Abe, T. Maegawa, Y.
Monguchi, H. Sajiki, Synlett 2007, 2521; i) H. Li, M. Yang,
Q. Pu, Microporous Mesoporous Mater. 2012, 148, 166; j) W.
Susanto, C. Y. Chu, W. J. Ang, T. C. Chou, L. C. Lo, Y. Lam,
J. Org. Chem. 2012, 77, 2729; k) K. Mitsudo, N. Kamimoto,
H. Murakami, H. Mandai, A. Wakamiya, Y. Murata, S. Suga,
Org. Biomol. Chem. 2012, 10, 9562.
[11] a) E. H. Smith, J. Whittall, Organometallics 1994, 13, 5169; b)
W. Y. Yin, C. He, M. Chen, H. Zhang, A. W. Lei, Org. Lett.
2009, 11, 709; c) K. Fang, M. H. Xie, Z. N. Zhang, P. Ning,
G. Y. Shu, Tetrahedron Lett. 2013, 54, 3819; d) J. D. Crowley,
S. M. Goldup, N. D. Gowans, D. A. Leigh, V. E. Ronaldson,
A. M. Z. Slawin, J. Am. Chem. Soc. 2010, 132, 6243.
[12] a) G. Hilt, C. Hengst, M. Arndt, Synthesis 2009, 395; b) M. E.
Krafft, C. Hirosawa, N. Dalal, C. Ramsey, A. Stiegman, Tetra-
hedron Lett. 2001, 42, 7733.
[13] a) X. Meng, C. B. Li, B. C. Han, T. S. Wang, B. H. Chen, Tetra-
hedron 2010, 66, 4029; b) P. P. Wang, X. Y. Liu, S. L. Zhang,
Chin. J. Chem. 2013, 31, 187.
[14] M. Yu, D. Pan, W. Jia, W. Chen, N. Jiao, Tetrahedron Lett.
2010, 51, 1287.
[15] Y. Kim, A. Park, K. Park, S. Lee, Tetrahedron Lett. 2011, 52,
1766.
[16] J. Park, E. Park, A. Kim, S. A. Park, Y. Lee, K. W. Chi, Y. H.
Jung, I. S. Kim, J. Org. Chem. 2011, 76, 2214.
[17] Z. Huang, R. Shang, Z. R. Zhang, X. D. Tan, X. Xiao, Y. Fu,
J. Org. Chem. 2013, 78, 4551.
[18] a) R. Shang, Y. Fu, Y. Wang, Q. Xu, H. Z. Yu, L. Lei, Angew.
Chem. Int. Ed. 2009, 48, 9350; Angew. Chem. 2009, 121, 9514;
[20] T. M. Wu, S. H. Huang, F. Y. Tsai, Appl. Organomet. Chem.
2011, 25, 395.
[21] S. N. Chen, W. Y. Wu, F. Y. Tsai, Green Chem. 2009, 11, 269.
[22] a) B. Inés, R. SanMartin, M. Moure, E. Domingueza, Adv.
Synth. Catal. 2009, 351, 2124; b) F. Churruca, R. SanMartin,
B. Inés, I. Tellitu, E. Domingueza, Adv. Synth. Catal. 2006,
348, 1836; c) C. Liek, P. Machnitzki, T. Nickel, S. Schenk, M.
Tepper, O. Stelzer, Z. Naturforsch., B: Chem. Sci. 1999, 54,
1532 ; d) R. Amengual, E. Genin, V. Michelet, M. Savignac,
J. P. Genêt, Adv. Synth. Catal. 2002, 344, 393; e) H. Hattori,
K. I. Fujita, T. Muraki, A. Sakaba, Tetrahedron Lett. 2007, 48,
6817.
[23] D. X. Liu, F. L. Li, H. X. Li, J. Gao, J. P. Lang, Tetrahedron
2014, 70, 2416.
[24] a) N. Mizuno, K. Kamata, Y. Nakagawa, T. Oishi, K. Yamagu-
chi, Catal. Today 2010, 157, 359; b) P. Siemsen, R. C. Living-
ston, F. Diederich, Angew. Chem. Int. Ed. 2000, 39, 2632; An-
gew. Chem. 2000, 112, 2740; c) G. H. Zhang, H. Yi, G. T.
Zhang, Y. Deng, R. P. Bai, H. Zheng, J. T. Miller, A. J. Kropf,
E. E. Bunel, A. W. Lei, J. Am. Chem. Soc. 2014, 136, 924.
[25] a) T. Y. Li, P. Sun, H. L. Yang, Y. Zhu, H. Yan, L. H. Lu, J. C.
Mao, Tetrahedron 2012, 68, 6413; b) A. Kolarovicˇ, Z.
Fáberová, J. Org. Chem. 2009, 74, 7199; c) A. Kolarovicˇ, M.
Schnürch, M. D. Mihovilovic, J. Org. Chem. 2011, 76, 2613.
Received: April 14, 2014
Published Online: ᭿
6
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O42416
/KAP1
Date: 24-06-14 11:11:04
Pages: 7
Homocoupling of Arylpropiolic Acids
Decarboxylative Homocoupling
D.-X. Liu, F.-L. Li, H.-X. Li,*
W.-J. Gong, J. Gao, J.-P. Lang* ....... 1–7
A CuI/1,10-phenanthroline system was em-
ployed to catalyze the oxidative decarb-
oxylative homocoupling of arylpropiolic
acids in aqueous DMF using air as an oxi-
dant, producing 1,3-diynes in good to high
yields. Such a catalytic system could be
reused several times.
Efficient and Reusable CuI/1,10-Phen-
anthroline-Catalyzed Oxidative Decarb-
oxylative Homocoupling of Arylpropiolic
Acids in Aqueous DMF
Keywords: Synthetic methods / Oxidation /
Alkynes / C–C coupling / Green chemistry
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
7