LETTER
elimination protocols, see: (l) Shao, G.;Orita, A.;Nishijima,
Synthesis and Photoluminescence Studies of Siloles
2563
CDCl3): d = –0.12, 14.6, 14.7, 27.1, 27.2, 55.1, 86.9, 90.3,
93.5, 94.3, 96.2, 104.7, 114.0, 115.5, 121.7, 122.8, 123.1,
123.6, 131.2, 131.3, 131.5, 131.8, 132.9, 143.1, 143.3,
159.6. Other TMS-protected phenylene ethynylenes 3c and
3d were prepared similarly from the corresponding sulfones
and aldehydes by one-shot double elimination process.6l,m
(ii) Preparation of 4e: A 100-mL flask was charged with 3e
(1.73 g, 3.76 mmol), K2CO3 (2.6 g, 18.8 mmol), THF (20
mL) and MeOH (20 mL). The mixture was stirred at r.t. for
2 h. After usual workup with EtOAc and aq NH4Cl, the
organic layer was dried over MgSO4 and filtered. The
solvents were evaporated, and the residue was
chromatographed (CH2Cl2–hexane, 3:7) to give 4e (1.35g,
93%) as a colorless solid. 1H NMR (500 MHz, CDCl3): d =
1.27–1.31 (m, 6 H), 2.80–2.86 (m, 4 H), 3.16 (s, 1 H), 3.77
(s, 3 H), 6.84 (d, J = 8.6 Hz, 2 H), 7.36 (s, 2 H), 7.45 (s, 5 H),
7.47 (s, 1 H). 13C NMR (125 MHz, CDCl3): d = 14.6, 14.7,
27.1, 30.2, 55.2, 78.9, 83.3, 86.8, 90.3, 93.3, 94.4, 114.0,
115.4, 121.6, 121.7, 123.1, 123.9, 131.3, 131.4, 131.5,
132.0, 132.9, 143.2, 143.4, 159.6.
(iii) Preparation of 10a: A solution of lithium naph-
thalenide was prepared by stirring a mixture of naphthalene
(1.17 g, 9.16 mmol) and lithium (63.6 mg, 9.16 mmol) in
THF (8 mL) at r.t. for 3 h. To the above lithium naph-
thalenide solution, diethylbis(phenylethynyl)silane (0.66 g,
2.29 mmol) in THF (8 mL) was added over 15 min, and the
mixture was stirred at r.t. for 15 min. ZnCl2 (1.56 g, 11.4
mmol) in THF (12 mL) was added at –20 °C, and the mixture
was stirred for 20 min. After N-bromosuccinimide (1.01 g,
5.72 mmol) had been added at –78 °C, the flask was shielded
from light by covering with foil and stirred at –78 °C for 1 h.
After usual workup with Et2O and aq NH4Cl, the organic
layer was washed with half-saturated Na2S2O3 solution,
dried over MgSO4 and filtered. The solvents were evapor-
ated, and the crude dibromosilole 7 was used for the next
step without further purification. To a solution of ZnCl2
(0.625 g, 4.58 mmol) in THF (8 mL) and Et3N (1.85 g, 18.3
mmol) were added dibromosilole 7 in THF (4 mL) and 4e
(1.779 g, 4.58 mmol) in THF (4 mL). After Pd(Ph3P)4
(0.264 g, 0.22 mmol) had been added, the mixture was
stirred at 65 °C for 13 h. After evaporation of the solvents,
the residue was chromatographed (EtOAc–hexane, 1:9) to
give 10a (2.82 g, 58%) as a yellow solid. 1H NMR (500
MHz, CDCl3)): d = 1.13–1.31 (m, 22 H), 2.84 (m, 8 H), 3.84
(s, 6 H), 6.90 (d, J = 8.5 Hz, 4 H), 7.19–7.24 (m, 14 H), 7.36
(s, 4 H), 7.42 (d, J = 8.0 Hz, 4 H), 7.48 (d, J = 9.0 Hz, 4 H).
13C NMR (125 MHz, CDCl3): d = 2.6, 7.1, 14.6, 14.7, 27.1,
55.2, 86.8, 90.2, 92.7, 93.8, 94.2, 99.6, 114.0, 115.4, 121.8,
122.2, 122.7, 122.9, 124.2, 127.2, 127.5, 129.3, 131.2, 131.4
(2), 132.9, 137.5, 143.1, 143.3, 159.6, 162.7. ESI–MS: m/z
[M + H] calcd for C78H67O2Si: 1063.49; found: 1063.1.
K.; Ishimaru, K.; Takezaki, M.; Wakamatsu, K.; Gleiter, R.;
Otera, J. Chem. Asian J. 2007, 2, 489. (m) Orita, A.;
Taniguchi, H.; Otera, J. Chem. Asian J. 2006, 1, 430.
(7) (a) Shao, G.; Orita, A.; Nishijima, K.; Ishimaru, K.;
Takezaki, M.; Wakamatsu, K.; Otera, J. Chem. Lett. 2006,
35, 1284. (b) Oyamada, T.; Shao, G.; Uchiuzou, H.;
Nakanotani, H.; Orita, A.; Otera, J.; Yahiro, M.; Adachi, C.
Jpn. J. Appl. Phys. 2006, 45, L1331. (c) Shao, G.; Orita, A.;
Taniguchi, H.; Ishimaru, K.; Otera, J. Synlett 2007, 231.
(d) Shao, G.; Orita, A.; Nishijima, K.; Ishimaru, K.;
Takezaki, M.; Wakamatsu, K.; Gleiter, R.; Otera, J. Chem.
Asian J. 2007, 2, 489. (e) Fenenko, L.; Shao, G.; Orita, A.;
Yahiro, M.; Otera, J.; Svechnikov, S.; Adachi, C. Chem.
Commun. 2007, 2278.
(8) For example: (a) Anderson, S. Chem. Eur. J. 2001, 7, 4706.
(b) Yamaguchi, Y.; Tanaka, T.; Kobayashi, S.; Wakamiya,
T.; Matsubara, Y.; Yoshida, Z. J. Am. Chem. Soc. 2005, 127,
9332. (c) Yamaguchi, Y.; Kobayashi, S.; Wakamiya, T.;
Matsubara, Y.; Yoshida, Z. Angew. Chem. Int. Ed. 2005, 44,
7040. (d) Yamaguchi, Y.; Ochi, T.; Wakamiya, T.;
Matsubara, Y.; Yoshida, Z. Org. Lett. 2006, 8, 717. (e) Shi,
Z.-F.; Wang, L.-J.; Wang, H.; Cao, X.-P.; Zhang, H.-L. Org.
Lett. 2007, 9, 595.
(9) UV–Vis and photofluorescence were recorded with JASCO
V-560 and JASCO FP-6500 instruments at r.t., respectively.
Absolute quantum yields of photofluorescence were
recorded by an integration sphere system (Hamamatsu
photonics C9920-02).
(10) Tamao, K.; Yamaguchi, S.; Shiro, M. J. Am. Chem. Soc.
1994, 116, 11715.
(11) Representative Experimental Procedure:
(i) Preparation of 3e: To a THF solution (40 mL) of phenyl
4-(trimethylsilylethynyl)phenylmethyl sulfone (1.57 g, 4.8
mmol) was added LiHMDS (4.8 mL, 1.0 M THF solution,
4.8 mmol) at –78 °C, and the mixture was stirred for 0.5 h.
To this solution was added a THF solution (5 mL) of 2,5-
diethyl-4-(4-methoxyphenylethynyl)benzaldehyde (1.16 g,
4.0 mmol), and the mixture was stirred for 1 h. After
ClP(O)(OEt)2 (0.694 mL, 4.8 mmol) had been added, the
mixture was stirred at r.t. for 2 h. After LiHMDS (20.0 mL,
1.0 M THF solution, 20.0 mmol) had been added at –78 °C,
the reaction mixture was stirred at –78 °C for 1 h and then at
30 °C for 17 h. After usual workup with EtOAc and aq
NH4Cl, the organic layer was dried over MgSO4 and filtered.
The solvents were evaporated, and the residue was
chromatographed (CH2Cl2–hexane, 3:7) to give 3e (1.73 g,
94%) as a colorless solid. 1H NMR (500 MHz, CDCl3): d =
0.26 (s, 9 H), 1.29 (t, J = 7.6 Hz, 6 H), 2.81–2.86 (m, 4 H),
3.82 (s, 3 H), 6.87 (d, J = 8.8 Hz, 2 H), 7.36 (s, 2 H), 7.45 (s,
4 H), 7.46 (s, 1 H), 7.48 (s, 1 H). 13C NMR (125 MHz,
Synlett 2007, No. 16, 2559–2563 © Thieme Stuttgart · New York