Palladium-catalyzed multialkynyl cross-coupling reactions with tetraalkynylindates

Article abstract of DOI:10.1002/ejoc.201000027

An efficient Pd-catalyzed multialkynyl cross-coupling reaction performed with tetraalkyriylindates generated in situ from the reaction of 1 equiv. of indium trichloride with 4 equiv. of organometallic reagents has been developed to produce symmetric as well as unsymmetric multialkynyl-substituted aromatic compounds in good-to-excellent yields. In these reactions, the four acetylide groups in the tetraalkynylindates transferred effectively to a variety of aryl bromides.

Full text of DOI:10.1002/ejoc.201000027

FULL PAPER
DOI: 10.1002/ejoc.201000027
Palladium-Catalyzed Multialkynyl Cross-Coupling Reactions with
Tetraalkynylindates
Dongjin Kang,[a] Dahan Eom,[a] Hyunseok Kim,[a] and Phil Ho Lee*[a]
Dedicated to the memory of Professor Chi Sun Hahn
Keywords: Cross-coupling / Indium / Alkynes / Palladium
An efficient Pd-catalyzed multialkynyl cross-coupling reac-
tion performed with tetraalkynylindates generated in situ
from the reaction of 1 equiv. of indium trichloride with
4 equiv. of organometallic reagents has been developed to
produce symmetric as well as unsymmetric multialkynyl-
substituted aromatic compounds in good-to-excellent yields.
In these reactions, the four acetylide groups in the tetraalk-
ynylindates transferred effectively to a variety of aryl bro-
mides.
diums,[15] allenylindiums,[16] 1,3-butadien-2-ylindiums,[17]
tetraorganoindates,[18] and indium tris(organothiolate)s[19]
with a variety of electrophiles. As a continuation of our
organic-conjugated materials chemistry program,[20] we en-
visioned the possibility of extending the scope of transition-
metal-catalyzed multialkynyl cross-coupling reactions by
using tetraorganoindates. Herein, we report the efficient Pd-
catalyzed multialkynyl cross-coupling reactions of tetraalk-
ynylindates with various aryl bromides with high atom effi-
ciency, producing symmetric as well as unsym-
metric multialkynyl-substituted aromatic compounds
(Scheme 1).
Introduction
Pd-catalyzed alkynylation is one of the most general and
reliable methods for the synthesis of alkynes.[1] Much atten-
tion has recently been focused on multialkynyl-substituted
aromatic compounds owing to their potential as nonlinear
optical materials,[2] liquid crystals,[3] core structures for
light-harvesting,[4] as well as dendritic materials[5] and
building blocks for two-dimensional carbon networks.[6]
During the last two decades a variety of transition-metal-
catalyzed multialkynyl cross-coupling reactions have been
reported.[1] Of these, metalated alkynes, especially those
containing Zn,[1c,7] Sn,[8] B,[9] Cu,[10] and Au[11] have gen-
erally been used in multialkynyl cross-coupling reactions.
Although these reactions show wide applicability, conve-
nience, and overall excellence, new and efficient transition-
metal-catalyzed multialkynyl reactions are strongly required
to overcome some of their limitations, such as the use of
organometallic reagents in excess, the dimerization of the
alkynes, and the toxicity of the metals. In recent years, or-
ganoindium reagents have become a favorite in organic re-
actions mainly due to their reactivity, selectivity, ease of
preparation and handling, operational simplicity, and low
toxicity.[12,13] On the basis of these properties, Sarandeses
and co-workers reported efficient Pd-catalyzed cross-cou-
pling reactions using triorganoindiums.[14] Recently we re-
ported the Pd-catalyzed cross-coupling reactions of allylin-
Scheme 1. Pd-catalyzed multialkynyl cross-coupling reactions per-
formed with tetraalkynylindates.
Results and Discussion
Our initial study focused on the Pd-catalyzed two-fold
alkynyl cross-coupling reactions of lithium tetrakis(phenyl-
ethynyl)indate (2a) with 2,5-dibromopyridine (1a) due to its
possible applications in materials science.
Because the reaction of 2,5-dibromopyridine with tetra-
kis(phenylethynyl)indate generated in situ from 1 equiv. of
indium trichloride and 4 equiv. of lithium phenylacetylide
required a long time (17 h) in THF at 70 °C and produced
5-bromo-2-(phenylethynyl)pyridine in 5% yield (entry 2,
Table 1), various Pd catalysts were re-examined with a view
[a] National Research Laboratory for Catalytic Organic Reactions,
Department of Chemistry and Institute for Molecular Science
and Fusion Technology, Kangwon National University,
Chuncheon 200-701, Republic of South Korea
Fax: +82-33-253-7582
E-mail: phlee@kangwon.ac.kr
2330
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Eur. J. Org. Chem. 2010, 2330–2336

Multialkynyl Cross-Coupling Reactions with Tetraalkynylindates
to accelerating the reaction rate and suppressing the forma- treated with 2e to provide the desired product 3j in 88%
tion of side-products. Of the catalysts screened, [Pd(dppf)- yield (entry 10). The use of 0.9 equiv. of 2e may have been
Cl2] was the most satisfactory in terms of product yield and required because of the low solubility of 1c. The reactions
reaction rate (entry 3). The use of other ligands such as of various indates (0.6 equiv., 2c, 2a, and 2b) with 2,7-di-
Ph3P, (4-CF3C6H4)3P, and (4-MeOC6H4)3P required long bromo-9H-fluorene (1d) and 9-ethyl-3,6-dibromo-9H-carb-
reaction times (24 h, entries 1, 4, and 5) or, as in the case azole (1e) afforded the desired dialkynylated products 3k,
of entry 4, also gave a low yield of the product 3a. The use 3l, and 3m in good-to-excellent yields (entries 11–13). Treat-
of 0.6 equiv. of 2a gave the best result, which indicates that ment of 2,4-dibromoanisole with indates 2a and 2g
the four phenylethynyl groups attached to the indium trans- (0.6 equiv.) gave the corresponding 2,4-di(alkynyl)anisoles
ferred effectively to 1a with high atom efficiency.
3n and 3o in 95 and 92% yields, respectively (entries 14 and
15). We were pleased to obtain di(alkynyl)thiophenes 3p
and 3q, respectively, from the reactions of 2,3- and 3,4-di-
bromothiophene with the corresponding indates (1.2 equiv.,
entries 16 and 17). The thermal instability of di(alkynyl)-
thiophenes required the use of 1.2 equiv. of 2a. Under the
optimum reaction conditions, the reaction of indate com-
plex 2e with 5,5Ј-dibromo-2,2Ј-bithiophenyl (1i) produced
the desired di(alkynyl) product 3r in 91% yield (entry 18).
Encouraged by these results, the treatment of 1,3,5-tribro-
mobenzene (1j) and 1,2,4,5-tetrabromobenzene (1k) with 2a
(1.2 equiv.) and 2e (2 equiv.) furnished tri- and tetraalk-
ynylbenzene derivatives (3s and 3t) in 84 and 72% yields,
respectively (entries 19 and 20).
Next, Pd-catalyzed multialkynyl cross-coupling reactions
using different kinds of tetraorganoindate were examined
for the preparation of unsymmetric alkynes. For example,
consecutive two-fold Pd-catalyzed cross-coupling reactions
using different indates (0.3 equiv. of 2c and 0.3 equiv. of 2a)
occurred chemo- and regioselectively in one-pot to afford
unsymmetric dialkyne 3u in 81% yield, which indicates that
all the ligands attached to the indium transferred to the
electrophilic reagent (Scheme 2). The unsymmetric dialkyne
derivative 3v with two pyridyl groups was obtained in 70%
Table 1. Optimization of Pd-catalyzed two-fold alkynyl cross-cou-
pling reactions.[a]
Entry Pd/Ligand
t [h]
Yield [%][b]
89
1
2 mol-% [Pd2dba3CHCl3]
24
16 mol-% PPh3
4 mol-% [Pd(PPh3)4]
4 mol-% [Pd(dppf)Cl2]
2 mol-% [Pd2dba3CHCl3]
16 mol-% P(4-CF3C6H4)3
2 mol-% [Pd2dba3CHCl3]
16 mol-% P(4-MeOC6H4)3
2
3
4
17
8
24
92(5)
95
11
5
24
64
[a] The reaction was performed with 4 mol-% [Pd(dppf)Cl2] and
0.6 equiv. of indate. [b] Isolated yield. The number in parentheses
represents the yield of 5-bromo-2-(2-phenylethynyl)pyridine.
With these results in hand, the Pd-catalyzed multialkynyl yield from the reaction of 2,5-dibromopyridine and
cross-coupling reactions of various indates with 2,5-dibro- 0.3 equiv. of the indate generated in situ from (2-pyridyl)
mopyridine (1a) were investigated. The results are summa- acetylene and indium trichloride and subsequent treatment
rized in Table 2. 2,5-Di(1-heptynyl)pyridine (3b) was ob- with 0.45 equiv. of the indate derived from 6-chloro-1-pen-
tained in 96% yield by using 0.6 equiv. of lithium tetra(1- tyne. Side-products such as reduced halide compounds,
heptynyl)indate (2b) under the optimum reaction conditions two-fold cross-coupling products arising from reaction with
(entry 1). Lithium tetrakis(tert-butylethynyl)indate (2c) pro- the same alkynyl group, and homocoupling products were
duced the cross-coupling product 3c in a lower yield of not observed in the preparation of alkynes 3u and 3v.
77%, presumably due to steric considerations and its basic-
Although the mechanism for Pd-catalyzed cross-coupling
ity (entry 2). In addition, the use of 0.6 equiv. of lithium reactions with lithium tetraalkynylindate has not been
tetrakis(1-cyclohexenylethynyl)indate (2d), lithium tet- firmly established, the details of these reactions can be de-
rakis(5-chloro-1-pentynyl)indate (2e), and indate 2f with a scribed in connection with the mechanism generally ac-
THP ether group participated well as nucleophiles in the cepted for these kinds of reactions.[21] In this mechanism we
Pd-catalyzed cross-coupling reactions, producing the corre- accept that R3In, R2InX, and RInX2 are all leaving groups
sponding di(alkynyl) compounds (3d, 3e, and 3f) in good- in a catalytic cycle and that these groups can be re-involved
to-excellent yields (entries 3, 4, and 5). These results imply in a new catalytic cycle and effectively transfer groups at-
that the four acetylide groups in the tetraalkynylindates tached to indium to an electrophilic coupling partner
transferred effectively to the 2,5-dibromopyridine with high (Scheme 3). This plausible mechanism is supported by the
atom efficiency and that the double bond, chloride, and fact that nBu3In, nBu2InCl, and nBuInCl2 have been effec-
THP ether were tolerated in the cross-coupling reactions. tively used in Pd-catalyzed and carbonylative cross-coupling
The addition of 0.6 equiv. of lithium tetrakis(phenylethynyl)- reactions.[14c,22] The efficient transfer of four organic groups
indate (2a) to 4,4Ј-dibromobiphenyl (1b) resulted in all of attached to the indium to the electrophile can be explained
the phenylethynyl groups attached to indium being transfer- by the weak In–C bond strength. In addition, the large dif-
red to 1b to afford 4,4Ј-bis(phenylethynyl)biphenyl (3g) in ference between the heats of formation of In–C and In–X
85% yield (entry 7). 9,10-Dibromoanthracene (1c) was supports the present mechanism.[23]
Eur. J. Org. Chem. 2010, 2330–2336
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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D. Kang, D. Eom, H. Kim, P. H. Lee
FULL PAPER
Table 2. Pd-catalyzed multialkynyl cross-coupling reactions with tetraalkynylindate.[a]
[a] The reactions were performed with 4 mol-% [Pd(dppf)Cl2] and 0.6 equiv. of indate in THF (70 °C). [b] 0.9 equiv. of indate were used.
[c] 1.2 equiv. of indate were used. [d] 2.0 equiv. of indate were used.
aromatic compounds. In these reactions the four acetylide
Conclusions
groups in the tetraalkynylindates transferred effectively to a
We have developed an efficient Pd-catalyzed multialkynyl variety of aryl bromides with high atom efficiency. These novel
cross-coupling reaction with tetraalkynylindates generated in features make tetraalkynylindates highly useful alternatives to
situ from the reaction of 1 equiv. of indium trichloride with other organometallic reagents used in transition-metal-cata-
4 equiv. of an organometallic reagent for the preparation of lyzed multialkynyl cross-coupling reactions and also mark
symmetric as well as unsymmetric multialkynyl-substituted them out as promising reagents for organic synthesis.
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Eur. J. Org. Chem. 2010, 2330–2336

Multialkynyl Cross-Coupling Reactions with Tetraalkynylindates
Typical Procedure for the Synthesis of Tetrakis(phenylethynyl)-
indate:[18] nBuLi (1.2 mmol, 1.6  in hexane) was slowly added to
a solution of phenylacetylene (132 µL, 1.2 mmol) in THF (1 mL)
at –78 °C. After stirring for 10 min, the cooling bath was removed
and the reaction mixture was warmed to room temperature, pro-
ducing lithium (2-phenyl)ethynylide. The resulting solution was
slowly added to a solution of InCl3 (66.3 mg, 0.3 mmol) in THF
(1 mL) at –78 °C. After stirring the mixture for 30 min, the cooling
bath was removed and the reaction mixture was warmed to room
temperature over 30 min.
2,5-Bis(phenylethynyl)pyridine (3a):[24] A solution of tetrakis(phen-
ylethynyl)indate (0.3 mmol, ca. 0.l5  in dry THF) was added to a
mixture of [Pd(dppf)Cl2] (16.3 mg, 4 mol-%) and 2,5-dibromopyr-
idine (118.4 mg, 0.5 mmol) in THF (1 mL) under nitrogen. The re-
action mixture was heated at reflux for 8 h. After cooling to room
temperature, the reaction mixture was quenched with sat. aq.
NaHCO3. The aqueous layer was extracted with diethyl ether
(3ϫ20 mL) and the combined organic phases were washed with
water and brine, dried with MgSO4, filtered, and concentrated un-
der reduced pressure. The residue was purified by silica gel column
chromatography (EtOAc/hexane = 1:30) to give 2,5-bis(phenyleth-
1
ynyl)pyridine (132.7 mg, 95%). Brown solid, m.p. 170–172 °C. H
NMR (400 MHz, CDCl3, 25 °C): δ = 8.76 (s, 1 H), 7.78 (d, J =
10.14 Hz, 1 H), 7.62–7.60 (m, 2 H), 7.56 (m, 2 H), 7.50 (d, J =
8.02 Hz, 1 H), 7.37 (m, 6 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 152.5, 141.9, 138.4, 132.1, 131.7, 129.2, 129.0, 128.5,
126.4, 122.4, 122.4, 122.1, 119.2, 94.3, 91.2, 88.6, 86.0 ppm. IR
Scheme 2. Pd-catalyzed multialkynyl cross-coupling reactions using
different tpes of tetraalkynylindates.
(film): ν = 3049, 2215, 1594, 1494, 1464, 1364, 1021, 751 cm–1.
˜
2,5-Di-1-heptynylpyridine
(3b):[25]
1H
NMR
(400 MHz,
CDCl325 °C): δ = 8.46 (s, 1 H), 8.75 (d, J = 8.05 Hz, 1 H), 7.20 (d,
J = 8.05 Hz, 1 H), 2.35 (q, J = 7.23 Hz, 4 H), 1.59–1.50 (m, 4 H),
1.39–1.22 (m, 8 H), 0.86–0.81 (m, 6 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 152.7, 142.3, 138.7, 126.3, 120.0, 95.8, 93.0,
80.7, 77.8, 31.5, 31.5, 28.6, 28.4, 22.6, 19.9, 19.8, 14.35, 14.33 ppm.
IR (film): ν = 2932, 2859, 2225, 1584, 1537, 1467, 1363, 840 cm–1.
˜
2,5-Bis(3,3-dimethyl-1-butynyl)pyridine (3c): White solid, m.p. 149–
151 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.52 (s, 1 H), 7.57
(d, J = 8.04 Hz, 1 H), 7.27 (d, J = 8.04 Hz, 1 H), 1.34 (s, 9 H),
1.32 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 152.6,
142.3, 138.8, 126.4, 120.0, 103.6, 100.5, 79.3, 76.4, 31.2, 31.1, 28.5,
Scheme 3. Plausible mechanism for the Pd-catalyzed multialkynyl
cross-coupling reactions using tetraalkynylindates.
28.4 ppm. IR (film): ν = 3324, 2965, 2240, 1583, 1536, 1458, 1359,
˜
1278, 1174 cm–1. HRMS (EI): calcd. for C17H21N 239.1674; found
239.1676.
Experimental Section
2,5-Bis(cyclohexenyl-1-ethynyl)pyridine (3d): Pale-yellow solid, m.p.
78–80 °C. H NMR (400 MHz, CDCl3, 25 °C): δ = 8.58 (s, 1 H),
1
General: Reactions were carried out in oven-dried glassware under
nitrogen. All commercial reagents were used without purification
and all solvents were of reagent grade. DMF was freshly distilled
from CaH2 and dried with molecular sieves (4 Å). All reactions
were monitored by TLC using glass plates precoated with silica gel,
purifications were performed by column chromatography with sil-
7.61 (d, J = 8.09 Hz, 1 H), 7.32 (d, J = 8.09 Hz, 1 H), 6.33 (s, 1
H), 6.26 (s, 1 H), 2.24–2.22 (m, 4 H), 2.16–2.15 (m, 4 H), 1.71–1.61
(m, 8 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 152.6,
142.3, 138.5, 138.0, 137.0, 126.4, 120.7, 120.5, 120.0, 96.4, 93.4,
86.7, 84.0, 29.4, 29.2, 26.3, 26.2, 22.62, 22.60, 21.79, 21.78 ppm. IR
(film): ν = 3384, 2933, 2858, 2203, 1579, 1538, 1467, 1348, 1263,
˜
ica gel (0.04–0.063 mm, 230–400 mesh). H and 13C NMR spectra
were recorded with a 400 MHz spectrometer using deuteriated
chloroform as the solvent. Chemical shift values (δ) are reported in
1
918 cm–1. HRMS (EI): calcd. for C21H21N 287.1674; found
287.1674.
parts per million relative to TMS as an internal standard (δ =
2,5-Bis(5-chloro-1-pentynyl)pyridine (3e): 1H NMR (400 MHz,
1
7.24 ppm for H and δ = 77.0 ppm for 13C). Infrared spectra were CDCl3, 25 °C): δ = 8.55 (s, 1 H), 7.61 (d, J = 8.41 Hz, 1 H), 7.30
recorded with a FTIR spectrometer; samples were either measured
as thin films pressed between two sodium chloride plates or as sol-
ids suspended in potassium bromide disks. High-resolution mass
spectra were recorded with a JEOL JMS 700 high-resolution mass
spectrometer. Melting points were determined in an open capillary
tube.
(d, J = 8.41 Hz, 1 H), 3.73–3.69 (m, 4 H), 2.67–2.63 (m, 4 H), 2.12–
2.04 (m, 4 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 152.3,
141.7, 138.5, 126.1, 119.5, 93.3, 90.4, 81.0, 78.2, 43.7, 43.6, 31.2,
31.0, 17.0, 16.9 ppm. IR (film): ν = 2960, 2230, 1584, 1539, 1469,
˜
1439, 1270, 1173, 1035 cm–1. HRMS (EI): calcd. for C15H15Cl2N
279.0582; found 279.0583.
Eur. J. Org. Chem. 2010, 2330–2336
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D. Kang, D. Eom, H. Kim, P. H. Lee
FULL PAPER
2,5-Bis[(tetrahydropyran-2-yloxy)ethynyl]pyridine (3f): Pale-yellow
was added to a mixture of [Pd(dppf)Cl2] (16.3 mg, 4 mol-%) and
solid, m.p. 78–80 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.63 9-ethyl-3,6-dibromo-9H-carbazole (176.6 mg, 0.5 mmol) in THF
(s, 1 H), 7.68 (d, J = 8.06 Hz, 1 H), 7.39 (d, J = 8.06 Hz, 1 H),
4.90–4.87 (m, 2 H), 4.54 (dd, J = 15.58, J = 2.38 Hz, 2 H), 4.48
(1 mL) under nitrogen. The reaction mixture was heated at reflux
until consumption of the starting material (4 h). After cooling to
(dd, J = 16.09, J = 8.99 Hz, 2 H), 3.91–3.85 (m, 2 H), 3.60–3.54 room temperature, the reaction mixture was quenched with sat. aq.
(m, 2 H), 1.89–1.73 (m, 4 H), 1.70–1.53 (m, 8 H) ppm. 13C NMR
(100 MHz, CDCl3, 25 °C): δ = 153.0, 142.1, 139.1, 126.8, 119.5,
97.5, 97.4, 90.8, 87.7, 85.1, 82.6, 62.4, 55.0, 54.9, 30.6, 25.7,
NaHCO3. The aqueous layer was extracted with diethyl ether
(3ϫ20 mL) and the combined organic phases were washed with
water and brine, dried with MgSO4, filtered, and concentrated un-
der reduced pressure. The residue was purified by silica gel column
chromatography (EtOAc/hexane = 1:100) to give 9-ethyl-3,6-di(1-
heptynyl)-9H-carbazole (178.4 mg, 93%). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 8.10 (t, J = 11.66 Hz, 2 H), 7.52–7.48 (m, 2 H),
7.26–7.19 (m, 2 H), 4.29–4.22 (m, 2 H), 2.45 (t, J = 7.14 Hz, 4 H),
1.69–1.61 (m, 4 H), 1.52–1.43 (m, 4 H), 1.41–1.34 (m, 7 H), 0.94
(t, J = 7.21 Hz, 6 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ
= 140.4, 131.9, 130.2, 128.8, 128.3, 124.6, 124.3, 123.0, 114.3, 109.2,
19.4 ppm. IR (film): ν = 3475, 2942, 2869, 2244, 1584, 1540, 1469,
˜
1363, 1267, 1120, 1027, 902 cm–1. HRMS (EI): calcd. for
C21H25NO4 355.1784; found 355.1780.
4,4Ј-Bis(phenylethynyl)biphenyl (3g):[26] Pale-yellow solid, m.p. 249–
250 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.61 (s, 8 H),
7.53–7.59 (m, 4 H), 7.33–7.40 (m, 6 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 139.0, 131.1, 130.6, 127.4, 127.3, 125.9, 122.2,
121.5, 88.6, 87.9 ppm. IR (film): ν = 3051, 2919, 1914, 1568, 1438,
˜
91.1, 88.3, 38.2, 14.3 ppm. IR (film): ν = 3055, 2955, 2857, 1862,
˜
1400, 1136, 822 cm–1.
1626, 1482, 1378, 1290, 1229, 804 cm–1. HRMS (EI): calcd. for
C23H33N 383.2613; found 383.2618.
4,4Ј-Bis(5-phenyl-1-pentynyl)biphenyl (3h): White solid, m.p. 52–
54 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.52–7.45 (m, 8
H), 7.31–7.27 (m, 4 H), 7.23–7.17 (m, 6 H), 2.79 (t, J = 7.29 Hz, 4
H), 2.43 (t, J = 7.29 Hz, 4 H), 1.97–1.89 (m, 4 H) ppm. 13C NMR
(100 MHz, CDCl3, 25 °C): δ = 142.1, 140.0, 132.5, 129.0, 128.9,
1-Methoxy-2,4-bis(phenylethynyl)benzene (3n): White solid, m.p.
123–124 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.71 (s, 1 H),
7.59–7.56 (m, 2 H), 7.54–7.52 (m, 2 H), 7.50–7.47 (m, 1 H), 7.38–
7.33 (m, 6 H), 6.89 (d, J = 8.62 Hz, 1 H), 3.94 (s, 3 H) ppm. 13C
NMR (100 MHz, CDCl3, 25 °C): δ = 160.2, 137.1, 133.5, 132.1,
131.9, 128.8, 128.72, 128.71, 128.5, 123.8, 123.7, 116.0, 113.3,
127.2, 126.4, 123.6, 91.3, 81.5, 35.3, 30.8, 19.4 ppm. IR (film): ν =
˜
3061, 3026, 2938, 2222, 1602, 1493, 1454, 1261, 822 cm–1. HRMS
(EI): calcd. for C34H30 438.2348; found 438.2348.
111.2, 94.3, 88.9, 85.2, 56.4 ppm. IR (film): ν = 3055, 2964, 2839,
˜
9,10-Bis(phenylethynyl)anthracene (3i):[27] Orange solid, m.p. 229–
2210, 1591, 1502, 1441, 1281, 1248, 1179, 1024 cm–1. HRMS (EI):
calcd. for C23H16O 308.1201; found 308.1196.
1
230 °C. H NMR (400 MHz, CDCl3, 25 °C): δ = 8.72–8.69 (m, 4
H), 7.80–7.78 (m, 4 H), 7.67–7.63 (m, 4 H), 7.49–7.43 (m, 6
H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 132.5, 132.1,
129.1, 129.0, 127.7, 127.2, 123.8, 118.9, 102.8, 86.9 ppm. IR (film):
1-Methoxy-2,4-bis(5-phenyl-1-pentynyl)benzene (3o): 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 7.45 (s, 1 H), 7.31–7.27 (m, 5 H),
7.24–7.27 (m, 6 H), 6.77 (d, J = 8.59 Hz, 1 H), 5.14 (s, 3 H), 2.83–
2.76 (m, 4 H), 2.46 (t, J = 7.00 Hz, 2 H), 2.39 (t, J = 7.00 Hz, 2
H), 1.97–1.87 (m, 4 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C):
δ = 159.8, 142.1, 137.1, 132.7, 129.05, 129.00, 128.8, 126.32, 126.31,
11.6, 113.7, 110.9, 94.9, 56.3, 35.3, 35.2, 30.8, 19.6, 19.2 ppm. IR
ν = 3476, 1635, 1489, 1261, 1174, 1036, 764 cm–1.
˜
9,10-Bis(5-chloro-1-pentynyl)anthracene (3j): Orange solid, m.p.
120–121 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.54–8.50 (m,
4 H), 7.58–7.54 (m, 4 H), 3.84 (t, J = 6.29 Hz, 4 H), 2.95 (t, J =
6.88 Hz, 4 H), 2.28–2.21 (m, 4 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 132.6, 127.6, 127.0, 118.8, 101.4, 78.6, 44.3,
(film): ν = 3024, 2939, 2858, 1599, 1454, 1268, 1243, 1177, 1034,
˜
894 cm–1. HRMS (EI): calcd. for C29H28O 392.2140; found
392.2142.
32.1, 18.1 ppm. IR (film): ν = 3397, 1634, 1395, 1261, 1173, 1036,
˜
765 cm–1. HRMS (EI): calcd. for C24H20Cl2 378.0942; found
378.0945.
1
2,3-Bis(phenylethynyl)thiophene (3p): H NMR (400 MHz, CDCl3,
25 °C): δ = 7.57–7.54 (m, 4 H), 7.35–7.33 (m, 6 H), 7.20 (d, J =
5.25 Hz, 1 H), 7.10 (d, J = 5.25 Hz, 1 H) ppm. 13C NMR
(100 MHz, CDCl3, 25 °C): δ = 132.1, 131.9, 129.4, 129.1, 128.9,
128.8, 127.1, 126.7, 126.6, 123.6, 123.3, 98.0, 94.0, 84.4, 82.5 ppm.
2,7-Bis(3,3-dimethyl-1-butynyl)-9H-fluorene (3k): Yellow solid, m.p.
180–182 °C. H NMR (400 MHz, CDCl3, 25 °C): δ = 7.64 (d, J =
8.22 Hz, 2 H), 7.57 (s, 2 H), 7.41 (d, J = 8.22 Hz, 2 H), 3.82 (s, 2
H), 1.36 (s, 18 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ =
143.7, 141.0, 130.9, 128.5, 122.8, 120.1, 99.1, 80.0, 36.8, 31.5,
1
IR (film): ν = 3105, 3078, 2198, 1950, 1595, 1492, 1442, 1259,
˜
1175 cm–1. HRMS (EI): calcd. for C20H12S 284.0660; found
284.0661.
28.5 ppm. IR (film): ν = 3479, 2967, 1609, 1464, 1361, 1260, 1173,
˜
1036, 827 cm–1. HRMS (EI): calcd. for C25H26 326.2034; found
326.2036.
3,4-Di(1-heptynyl)thiophene (3q): 1H NMR (400 MHz, CDCl3,
25 °C): δ = 7.26 (s, 2 H), 2.42 (t, J = 7.08 Hz, 4 H), 1.65–1.58 (m,
4 H), 1.49–1.42 (m, 4 H), 1.40–1.31 (m, 4 H), 0.92 (t, J = 7.21 Hz,
6 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 127.3, 126.0,
9-Ethyl-3,6-bis(phenylethynyl)-9H-carbazole (3l):[28] Pale-yellow so-
lid, m.p. 161–163 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.30
(s, 2 H), 7.68 (d, J = 8.48 Hz, 2 H), 7.62 (d, J = 8.04 Hz, 4 H),
7.41–7.35 (m, 8 H), 4.33 (q, J = 7.19 Hz, 2 H), 1.44 (t, J = 7.19 Hz,
3 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 140.4, 131.9,
130.2, 128.8, 128.3, 124.6, 124.3, 123.0, 114.3, 109.2, 91.1, 88.3,
92.7, 74.9, 31.5, 28.9, 22.7, 19.9, 14.4 ppm. IR (film): ν = 3477,
˜
3106, 2956, 2857, 2233, 1465, 1260, 1173, 1036 cm–1. HRMS (EI):
calcd. for C18H24S 272.1599; found 272.1598.
38.2, 14.3 ppm. IR (film): ν = 3433, 2207, 1628, 1592, 1492, 1380,
˜
5,5Ј-Bis(5-chloro-1-pentynyl)-2,2Ј-bithiophenyl (3r): 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 7.00 (d, J = 3.38 Hz, 2 H), 6.96 (d,
J = 3.88 Hz, 2 H), 3.68 (t, J = 6.39 Hz, 4 H), 2.63 (t, J = 6.82 Hz,
4 H), 2.08–2.01 (m, 4 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 137.6, 132.6, 124.0, 123.2, 94.1, 75.0, 44.1, 31.7,
1260, 1231, 1173, 1036 cm–1.
9-Ethyl-3,6-di(1-heptynyl)-9H-carbazole (3m): (1-Heptynyl)lithium
(1.2 mmol, 1.0–1.2  in THF) was added to a solution of InCl3
(66.3 mg, 0.3 mmol) in THF (1 mL) at –78 °C under nitrogen. After
stirring the mixture for 30 min, the cooling bath was removed and
the reaction mixture was warmed to room temperature over 30 min.
The tetra(1-heptynyl)indate solution (0.3 mmol, ca. 0.l5  in THF)
17.7 ppm. IR (film): ν = 3071, 2958, 2221, 1605, 1512, 1440, 1284,
˜
1037, 796 cm–1. HRMS (EI): calcd. for C18H16Cl2S2 366.0070;
found 366.0073.
2334
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 2330–2336

Multialkynyl Cross-Coupling Reactions with Tetraalkynylindates
1,3,5-Tris(phenylethynyl)benzene (3s):[14f] White solid, m.p. 141–
142 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.66 (s, 3 H),
7.55–7.53 (m, 6 H), 7.38–7.35 (m, 9 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 134.5, 132.1, 129.0, 128.8, 124.4, 123.2, 90.9,
Acknowledgments
This work was supported by the Korean Science and Engineering
Foundation (KOSEF) through the NRL Program funded by
MOST (No. M10600000203-06J0000-20310), by the National Re-
search Foundation of Korea (NRF) grant funded by the Korea
government (MEST) (2009-0087013), and by the Korea Sanhak
Foundation. This work was supported by the second phase of the
Brain Korea 21 Program 2009. Dr. Sung Hong Kim at the KBSI
(Daegu) is thanked for recording the MS data. The NMR spectro-
scopic data were obtained from the central instrumental facility at
Kangwon National University.
88.2 ppm. IR (film): ν = 3476, 3078, 2211, 1598, 1581, 1489, 1260,
˜
1173, 1036 cm–1. HRMS (EI): calcd. for C30H18 378.1409; found
378.1411.
1,2,4,5-Tetrakis(5-chloro-1-pentynyl)benzene (3t): (5-Chloropent-
ynyl)lithium (4.0 mmol, 1.0–1.2  in dry THF) was added to a
solution of InCl3 (221.2 mg, 1.0 mmol) in THF (1 mL) at –78 °C
under nitrogen. After stirring the mixture for 30 min, the cooling
bath was removed and the reaction mixture was warmed to room
temperature over 30 min. The solution of tetrakis(5-chloropent-
ynyl)indate (1.0 mmol, ca. 0.l5  in THF) was added to a mixture
of [Pd(dppf)Cl2] (16.3 mg, 4 mol-%) and 1,2,3,5-tetrabromoben-
zene (196.9 mg, 0.5 mmol) in THF (1 mL) under nitrogen. The re-
action mixture was heated at reflux until consumption of the start-
ing material (4 h). After cooling to room temperature, the reaction
mixture was quenched with sat. aq. NaHCO3. The aqueous layer
was extracted with diethyl ether (3ϫ20 mL) and the combined or-
ganic phases were washed with water and brine, dried with MgSO4,
filtered, and concentrated under reduced pressure. The residue was
purified by silica gel column chromatography (EtOAc/hexane =
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1:60)
to
give
1,2,4,5-tetrakis(5-chloro-1-pentynyl)benzene
1
(173.0 mg, 72%). Yellow oil. H NMR (400 MHz, CDCl3, 25 °C):
δ = 7.40 (s, 2 H), 3.76 (t, J = 6.44 Hz, 8 H), 2.66 (t, J = 6.71 Hz,
8 H), 2.10–2.03 (m, 8 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 135.6, 125.5, 94.0, 80.1, 44.0, 31.7, 17.5 ppm. IR (film):
ν = 2958, 2231, 1486, 1428, 1289, 1173, 902 cm–1. HRMS (EI):
˜
calcd. for C26H26Cl4 478.0789; found 478.0788.
1-(3,3-Dimethyl-1-butynyl)-4-phenylethynylbenzene (3u): White so-
lid, m.p. 112 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 7.53 (m,
2 H), 7.44 (d, J = 8.15 Hz, 2 H), 7.37–7.33 (m, 5 H), 1.32 (s, 9
H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 132.0, 131.9,
131.8, 128.8, 124.4, 123.6, 122.6, 101.0, 91.1, 89.6, 79.3, 31.4,
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28.5 ppm. IR (film): ν = 3396, 2969, 2866, 2231, 1593, 1511, 1362,
˜
1288, 915 cm–1. HRMS (EI): calcd. for C20H18 258.1409; found
258.1410.
2-[5-(5-Chloro-1-pentynyl)pyridin-2-ylethynyl]pyridine (3v): A solu-
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NaHCO3. The aqueous layer was extracted with diethyl ether
(3ϫ20 mL) and the combined organic phases were washed with
water and brine, dried with MgSO4, filtered, and concentrated un-
der reduced pressure. The residue was purified by silica gel column
chromatography (EtOAc/hexane = 1:2) to give 2-[5-(5-chloro-1-
pentynyl)pyridin-2-ylethynyl]pyridine (98.3 mg, 70%). Brown solid,
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1
m.p. 44 °C. H NMR (400 MHz, CDCl3, 25 °C): δ = 8.65 (s, 1 H),
8.64 (d, J = 1.82 Hz, 1 H), 7.74–7.67 (m, 2 H), 7.62 (d, J = 7.88 Hz,
1 H), 7.55 (d, J = 8.04 Hz, 1 H), 7.31–7.27 (m, 1 H), 3.75 (t, J =
6.28 Hz, 2 H), 2.66 (t, J = 6.84 Hz, 2 H), 2.08 (quintet, J = 6.56 Hz,
2 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 152.6, 150.2,
142.6, 140.8, 138.7, 136.3, 127.8, 127.0, 123.5, 120.4, 94.0, 89.3,
87.6, 78.2, 43.6, 31.1, 17.0 ppm. IR (film): ν = 3420, 3049, 2959,
˜
2227, 1581, 1471, 1428, 778 cm–1. HRMS (EI): calcd. for
C17H13ClN2 280.0767; found 280.0770.
Eur. J. Org. Chem. 2010, 2330–2336
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2335

D. Kang, D. Eom, H. Kim, P. H. Lee
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Published Online: March 9, 2010
2336
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 2330–2336