Job/Unit: O20442
/KAP1
Date: 09-07-12 15:51:51
Pages: 7
An Iterative Method for the Synthesis of Symmetric Polyynes
ring for 2 h, the mixture reached –60 °C, and trimethylsilyl chloride
(0.63 mL, 4.9 mmol) was added. The reaction was allowed to stir
for 3.5 h, without further cooling. Saturated aq. NH4Cl (30 mL)
was added, and the mixture was extracted with hexanes (3ϫ
30 mL). Removal of the solvent resulted in 3c as a mixture of
brown oil and short needle-like crystals (0.17 g, 63% yield). 1H
1,10-Diiodo-1,3,5,7,9-decapentayne (5a): 1,10-Bis(trimethylsilyl)-
1,3,5,7,9-decapentayne (5c; 0.096 g, 0.36 mmol) was dissolved in
acetone (200 mL) in a round-bottom flask wrapped with aluminum
foil. AgNO3 (0.186 g, 1.09 mmol) and N-iodosuccinimide (0.488 g,
2.17 mmol) were added, and the reaction mixture was allowed to
stir at room temperature for 4.5 h. Ice water (200 mL) and hexanes
NMR (400 MHz, CDCl3, 25 °C): δ = 0.20 ppm. 13C NMR (200 mL) were added, and the aqueous layer was extracted with
(100 MHz, CDCl3, 25 °C): δ = 87.9, 87.4, 61.9, –0.6 ppm.[7]
hexanes (3ϫ 100 mL). The combined organic layers were washed
with 15% aq. Na2S2O3. The resulting yellow solution was dried
with MgSO4. Filtration and removal of solvent resulted in 5a as a
yellow solid that decomposed at 55–56 °C (0.11 g, 82% yield). 13C
NMR (100 MHz, CDCl3, 25 °C): δ = 79.0, 62.6, 61.4, 59.3,
2.3 ppm. MS (EI): m/z (%): 373 (100) [M]+, 246 (18) [M – I]+, 128
(60) [I]+, 119 (42) [M – 2I]+. HRMS (EI): calcd. for C10I2
373.80900; found 373.80923.
1,10-Bis(triisopropylsilyl)-1,3,5,7,9-decapentayne (5b): In a heart-
shaped flask wrapped in aluminum foil, diiodohexatriyne (3a;
0.123 g, 0.377 mmol) and triisopropylsilyl(trimethylstannyl)ethyne
(1b; 0.253 g, 0.734 mmol) were dissolved in dry THF (20 mL). CuI
(0.016 g, 0.084 mmol, 22 mol-%) and Pd(PPh3)2Cl2 (0.035 g,
0.050 mmol, 13 mol-%) were combined in a round-bottom flask
wrapped with foil, and the system was degassed and backfilled with
Ar. THF (5 mL) was added to this flask, and both flasks were kept
in ice baths (0 °C). The solution of 3a and 1b was added to the
catalyst mixture via cannula over a period of 9 h. After stirring for
an additional 2 h at room temperature, the solvent was removed in
vacuo, and the excess amount of the catalyst was removed using a
short plug (SiO2/hexanes). Warm MeOH/CHCl3 (10:1) was used
for recrystallization. The mixture was placed in a 45 °C water bath,
and 3 n HCl was added dropwise until a visible yellow suspension
formed. The liquid was cooled to room temperature and placed in
the freezer. Vacuum filtration was used to isolate 5b as a yellow
1,14-Bis(triisopropylsilyl)-1,3,5,7,9,11,13-tetradecaheptayne (7b): In
a heart-shaped flask wrapped in aluminum foil, diiodopentayne
(5a; 0.056 g, 0.15 mmol) and triisopropylsilyl(trimethylstannyl)eth-
yne (1b; 0.10 g, 0.29 mmol) were dissolved in dry THF (20 mL).
CuI (0.007 g, 0.037 mmol, 24 mol-%) and Pd(PPh3)2Cl2 (0.013 g,
0.018 mmol, 12 mol-%) were combined in a round-bottom flask
wrapped with foil, and the system was degassed and backfilled with
Ar. THF (5 mL) was added to the flask, and both flasks were kept
in ice baths (the diiodopentayne and tin solution was kept between
–15 and –30 °C, and the catalyst mixture was kept at 0 °C). The
solution of 5a and 1b was added to the catalyst mixture via cannula
over a period of 10 h. After stirring for an additional 2 h at room
temperature, the solvent was removed in vacuo and the excess
amount of the catalyst was removed using a short plug (SiO2/hex-
anes). Column chromatography (SiO2/hexanes) was used to isolate
7b as dark yellow oil (0.007 g, 10% yield). 1H NMR (500 MHz,
CDCl3, 25 °C): δ = 1.09 ppm. 13C NMR (125 MHz, CDCl3, 25 °C):
1
solid (0.065 g, 40% yield). H NMR (400 MHz, C6D6, 25 °C): δ =
0.99 ppm. 13C NMR (100 MHz, C6D6, 25 °C): δ = 90.65, 87.18,
63.42, 63.41, 62.49, 18.95, 11.87 ppm.[7]
1,10-Bis(trimethylsilyl)-1,3,5,7,9-decapentayne (5c): In
a heart-
shaped flask wrapped in aluminum foil, diiodohexatriyne (3a;
0.113 g, 0.347 mmol) and trimethylsilyl[(trimethylstannyl)ethynyl]-
ethyne (1c; 0.179 g, 0.686 mmol) were dissolved in dry THF
(20 mL). CuI (0.015 g, 0.079 mmol, 23 mol-%) and Pd(PPh3)2Cl2
(0.028 g, 0.041 mmol, 12 mol-%) were combined in a round-bottom
flask wrapped with foil, and the system was degassed and back-
filled with Ar. THF (5 mL) was added to the flask, and both flasks
were kept in ice baths (0 °C). The solution of 3a and 1c was added
to the catalyst mixture via cannula over a period of 10 h. After
stirring for an additional 2 h at room temperature, the solvent was
removed in vacuo and the excess amount of the catalyst was re-
moved using a short plug (SiO2/hexanes). Vacuum sublimation was
δ
= 89.34, 87.39, 62.97, 62.93, 62.62, 62.26, 61.20, 18.49,
11.27 ppm. HRMS (EI): calcd. for C32H42Si2 482.28251; found
482.28314.
Supporting Information (see footnote on the first page of this arti-
1
cle): Copies of the H NMR and 13C NMR for the prepared com-
pounds and HRMS for novel compounds.
Acknowledgments
1
used to isolate 5c as a brown solid (0.060 g, 61% yield). H NMR
This work was supported by the National Science Foundation
(CHE-0446749 and CHE-0911540). We thank Liang Luo and Da-
vid Connors for helpful discussions.
(400 MHz, CDCl3, 25 °C): δ = 0.21 ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 88.63, 87.71, 62.62, 62.23, 62.17, –0.65 ppm.[26]
1,10-Bis(phenyl)-1,3,5,7,9-decapentayne (5d): In
a heart-shaped
[1] S. Eisler, A. D. Slepkov, E. Elliott, T. Luu, R. McDonald, F. A.
Hegmann, R. R. Tykwinski, J. Am. Chem. Soc. 2005, 127,
2666–2676.
flask wrapped in aluminum foil, diiodohexatriyne (3a; 0.198 g,
0.608 mmol) and phenyl(trimethylstannyl)ethyne (1d; 0.321 g,
1.21 mmol) were dissolved in dry THF (20 mL). CuI (0.026 g,
0.14 mmol, 22 mol-%) and Pd(PPh3)2Cl2 (0.051 g, 0.073 mmol,
12 mol-%) were combined in a round-bottom flask wrapped with
foil, and the system was degassed and backfilled with Ar. THF
(5 mL) was added to the flask, and both flasks were kept in ice
baths (0 °C). The solution of 3a and 1d was added to the catalyst
mixture via cannula over a period of 9 h. After stirring for an ad-
ditional 2 h at room temperature, the solvent was removed in vacuo
and the excess amount of the catalyst was removed using a short
plug (SiO2/hexanes). Column chromatography (SiO2/hexanes) was
used to isolate 5d as a light yellow solid (0.47 g, 28% yield). 1H
NMR (400 MHz, CDCl3, 25 °C): δ = 7.56–7.54 (m, 4 H), 7.44–7.40
(m, 2 H), 7.36–7.32, (m, 4 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 133.3, 130.2, 128.6, 120.3, 77.5, 74.4, 67.3, 64.5,
62.8 ppm.[7]
[2] a) R. Castro-Beltran, G. Ramos-Ortiz, C. Jim, J. Maldonado,
M. Häußler, D. Peralta-Dominguez, M. Meneses-Nava, O.
Barbosa-Garcia, B. Tang, Appl. Phys. B: Lasers Opt. 2009, 97,
489–496; b) Y. Iwase, K. Kamada, K. Ohta, K. Kondo, J. Ma-
ter. Chem. 2003, 13, 1575–1581; c) K. Ohta, K. Kamada, J.
Chem. Phys. 2006, 124, 124303; d) R. Kishi, M. Nakano, S.
Yamada, K. Kamada, K. Ohta, T. Nitta, K. Yamaguchi, Chem.
Phys. Lett. 2004, 393, 437–441; e) R. Kishi, M. Nakano, S.
Yamada, K. Kamada, K. Ohta, T. Nitta, K. Yamaguchi, Synth.
Met. 2005, 154, 181–184.
[3] a) M. I. Bruce, P. A. Humphrey, N. N. Zaitseva, B. K. Nichol-
son, B. W. Skelton, A. H. White, Dalton Trans. 2010, 39, 8801–
8811; b) G. R. Owen, S. Gauthier, N. Weisbach, F. Hampel, N.
Bhuvanesh, J. A. Gladysz, Dalton Trans. 2010, 39, 5260–5271;
c) M. Sato, Y. Kubota, Y. Kawata, T. Fujihara, K. Unoura, A.
Oyama, Chem. Eur. J. 2006, 12, 2282–2292; d) C. S. Wang,
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5