Alternating Diacetylene Copolymer
A R T I C L E S
1.66%; O, 8.79%; I, 69.74%. Found: C, 19.86%; H, 1.68%; O, 8.93%;
I, 69.70%. HRMS (EI) m/z calcd for C3H3IO ([M]+): 181.9229.
Found: 181.9229.
After aqueous workup, the crude product was purified by column
chromatography (silica gel, EtOAc/hexanes 1:2); 0.65 g (79%) of pure
12 was obtained as a brown syrup. H NMR (300 MHz, CDCl3): δ
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Triisopropyl(prop-2-ynyloxy)silane 9. Propargyl alcohol (1.12 g,
20 mmol, 1 equiv) and imidazole (1.63 g, 24 mmol, 1.2 equiv) were
dissolved in dry DCM. Then, triisopropylsilyl chloride (3.84 g, 20
mmol, 1 equiv) was added slowly at 0 °C. The mixture was allowed to
stir for 2 h at room temperature and diluted with DCM. After aqueous
workup, 4.16 g (98%) of the crude product was obtained as a slightly
yellow liquid and used in the next step without further purification. 1H
NMR (300 MHz, CDCl3): δ 4.37 (s, 2H, CH2), 2.37 (s, 1H, CtCH),
1. 08 (m, 21H, CH3, CHMe2). 13C NMR (75 MHz, CDCl3): δ 82.3
(CtCH), 72.5 (CtCH), 51.6 (CH2), 17.8 (CH3), 11.9 (CHMe2).
6-(Triisopropylsilyloxy)hexa-2,4-diyn-1-ol 10. CuCl (0.062 g, 0.6
mmol, 0.06 equiv) was dissolved in a mixture of 10 mL of methanol
and 10 mL of n-butylamine. Then, triisopropyl(prop-2-ynyloxy)silane
9 (2.12 g, 10 mmol, 1 equiv) was added at 0 °C, followed by the
dropwise addition of 3-iodoprop-2-yn-1-ol 8 (1.82 g, 10 mmol, 1 equiv).
Whenever the reaction mixture turned to green, a few crystals of NH2-
OH‚HCl were added. After stirring for 1 h at 0 °C and for another 3
h at room temperature, the reaction mixture was filtered through a pad
of silica gel. After aqueous workup, the crude product was purified by
column chromatography (silica gel, EtOAc/hexanes 1:3); 1.5 g (56%)
8.03 (m, 2H, PhHo), 7.56 (m, 1H, PhHp), 7.43 (m, 2H, PhHm), 4.98 (s,
2H, CH2), 4.33 (s, 2H, CH2), 3.46 (s, 1H, OH). 13C NMR (75 MHz,
CDCl3): δ 165.7 (CdO), 133.3, 129.6, 128.8, 128.3 (Ph), 78.3, 72.9,
70.6, 68.9 (CtC), 52.8, 50.8 (CH2). Anal. Calcd for C13H10O3: C,
72.89%; H, 4.70%; O, 22.41%. Found: C, 72.78%; H, 4.76%; O,
22.30%. HRMS (EI) m/z calcd for C13H10O3 ([M]+): 214.0630.
Found: 214.0622. Rf ) 0.26 (EtOAc/hexanes 1:2).
6-(Pentafluorobenzoyloxy)hexa-2,4-diynyl benzoate 6. A solution
of 6-hydroxyhexa-2,4-diynyl benzoate 12 (0.65 g, 3 mmol, 1 equiv)
and pentafluorobenzoyl chloride (0.43 mL, 3 mmol, 1 equiv) in dry
DCM was cooled to 0 °C, and triethylamine (1 mL, 7 mmol, 2.3 equiv)
was added slowly. The mixture was allowed to warm to room
temperature and stirred for 5 h. After aqueous workup and column
chromatography (silica gel, DCM), 1.06 g (87%) of pure 6 was obtained
as bright yellow crystals. Colorless crystals appropriate for X-ray
analysis were prepared by slow addition of hexanes to a 20% w/w
solution of 5 in DCM until opalescence occurred and subsequent slow
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evaporation of the solvent. H NMR (300 MHz, CDCl3): δ 8.06 (m,
2H, PhHo), 7.58 (m, 1H, PhHp), 7.46 (m, 2H, PhHm), 5.05 (s, 2H, CH2),
5.01 (s, 2H, CH2). 19F NMR (188 MHz, CDCl3): δ -137.1 (m, 2F),
-147.2 (m, 1F), -160.0 (m, 2F). 13C NMR (75 MHz, CDCl3): δ 165.4,
158.223 (CdO), 145.723 (C6F5), 143.623 (C6F5), 137.723 (C6F5), 133.4,
129.7, 129.0, 128.4 (Ph), 107.023 (C6F5), 74.5, 72.0, 71.4, 70.0 (CtC),
54.0, 52.5 (CH2). Anal. Calcd for C20H9F5O4: C, 58.84%; H, 2.22%;
F, 23.27%; O, 15.68%. Found: C, 58.71%; H, 2.28%; F, 23.10%.
HRMS (EI) m/z calcd for C20H9F5O4 ([M]+): 408.0421. Found:
408.0412. Mp: 70-72 °C; 71.80 °C (DSC). Rf ) 0.70 (DCM).
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of pure 10 was obtained as a brownish liquid. H NMR (300 MHz,
CDCl3): δ 4.44 (s, 2H, CH2), 4.32 (s, 2H, CH2), 3.23 (b, 1H, OH),
1.07 (m, 21H, CH3 and CHMe2). 13C NMR (75 MHz, CDCl3): δ 77.8,
77.0, 69.6, 68.7 (CtC), 52.2, 50.1 (CH2), 17.8 (CH3), 11.8 (CHMe2).
Anal. Calcd for C15H26O2Si: C, 67.61%; H, 9.84%; O, 12.01%; Si,
10.54%. Found: C, 67.49%; H, 9.86%. HRMS (EI) m/z calcd for
C15H26O2Si ([M]+): 266.1702. Found: 266.1701. Rf ) 0.38 (EtOAc/
hexanes 1:3).
6-(Triisopropylsilyloxy)hexa-2,4-diynyl benzoate 11. A solution
of 6-(triisopropylsilyloxy)hexa-2,4-diyn-1-ol 10 (1.06 g, 4 mmol, 1
equiv) and benzoyl chloride (0.46 mL, 4 mmol, 1 equiv) in dry DCM
was cooled to 0 °C, and pyridine (0.65 mL, 8 mmol, 2 equiv) was
added slowly. The mixture was allowed to warm to room temperature
and stirred for 4 h. After aqueous workup, the crude product was
purified by column chromatography (silica gel, DCM/hexanes 1:25);
Acknowledgment. The authors would like to thank Dr. Heinz
Ru¨egger for performing solid-state NMR spectroscopy, Martin
Colussi for measuring DSC, the Gru¨tzmacher group at ETH
Zurich for helping us with Raman spectroscopy, and Prof. Dieter
Schlu¨ter for valuable discussions and his support. Financial
support from the Deutsche Forschungsgemeinschaft (Emmy
Noether program, FR 1567/2-1) is gratefully acknowledged.
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1.04 g (70%) of pure 11 was obtained as a yellow liquid. H NMR
(300 MHz, CDCl3): δ 8.07 (m, 2H, PhHo), 7.59 (m, 1H, PhHp), 7.46
(m, 2H, PhHm), 5.01 (s, 2H, CH2), 4.47 (s, 2H, CH2), 1.10 (m, 21H,
CH3, CHMe2). 13C NMR (75 MHz, CDCl3): δ 165.6 (CdO), 133.3,
129.8, 129.2, 128.4 (Ph), 78.6, 72.5, 71.0, 68.4 (CtC), 52.8, 52.2 (CH2),
17.8 (CH3), 11.9 (CHMe2). Rf ) 0.35 (EtOAc/hexanes 1:15).
6-Hydroxyhexa-2,4-diynyl benzoate 12. A solution of 6-(triiso-
propylsilyloxy)hexa-2,4-diynyl benzoate 11 (1.42 g, 3.8 mmol, 1 equiv)
in THF was cooled to -78 °C, and tetrabutylammonium fluoride (4.6
mL, 1.2 equiv, 1.0 M solution in THF) was added via a syringe. The
reaction was stirred for 2 h at -78 °C and then diluted with Et2O.
Supporting Information Available: 1H and 13C NMR spectra
of 4, 5, 6, 8, 9, 10, 11, and 12; 19F and 19F-13C HMQC NMR
spectra of 5 and 6. Raman spectra of 6 before and after UV
irradiation; ORTEP representations, crystal structure illustrations,
and complete crystallographic data (CIF) of 4, 5, 6, and 4‚5.
This material is available free of charge via the Internet at
JA0603204
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J. AM. CHEM. SOC. VOL. 128, NO. 16, 2006 5547