Site-selective monotitanation of dialkynylpyridines and its application for preparation of highly fluorescent π-conjugated oligomers

Article abstract of DOI:10.1021/ol048316p

(Chemical Equation Presented) Reaction of Ti(O-i-Pr)₄/2i-PrMgCl reagent with 2,n-bis[(trimethylsilyl)ethynyl]pyridines, where n is 3, 4, 5, and 6, or with 3,4-bis[(trimethylsilyl)-ethynyl]pyridines, proceeded with excellent site-selectivity to afford the corresponding monotitanated complex. Synthetic application of the reaction was demonstrated by an efficient preparation of π-conjugated oligomers having pyridine and enyne units alternately, which possess intense blue fluorescence emission.

Full text of DOI:10.1021/ol048316p

Supporting Information for:
Site-selective Mono-titanation of Dialkynylpyridines and Its
Application for Preparation of Highly Fluorescent p-Conjugated
Oligomers
Yuuki Takayama*, Takeshi Hanazawa, Tomohiro Andou, Kenji Muraoka, Hiroyuki
Ohtani, Mizuki Takahashi, and Fumie Sato*
Department of Biomolecular Engineering, Tokyo Institute of Technology,
4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
General. Melting points were measured with Yanaco MP-J3 Micro Melting Point
1
13
Apparatus. H and C NMR spectra were taken on a Varian Gemini-2000 spectrometer at 300
and 75 MHz, respectively. CDCl was used as the solvent. Chemical shifts are reported in parts
3
1
per million shift (d value) from Me Si (d 0 ppm for H) or based on the middle peak of the solvent
4
1
3
(
CDCl ) (d 77.00 ppm for C NMR) as an internal standard. Signal patterns are indicated as br,
3
broad; s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet. Coupling constants (J) are given in
hertz. Infrared (IR) spectra were recorded on a JASCO FT-IR 230 spectrometer and are reported
-
1
in wave numbers (cm ).
UV/Vis spectra were obtained with HITACHI U-2000
Spectrophotometer. Fluorescence spectra were obtained with SPEX FLUOROMAX-2. Mass
spectra (MS, EI, 70 eV) were measured on a Shimadzu QP-5000 GC mass spectrometer.
MALDI-TOF-MS spectra were obtained using a Shimadzu MALDI-TOFMS AXIMA-CFR. 2,5-
Dihydroxybenzoic acid (DHB) was used as matrix. Elemental analyses were performed on an
Elementar Vario-EL. All reactions were carried out under an argon atmosphere, using flame-
dried glassware and were monitored by TLC (Merck, Kieselgel 60 F254); visualization was done
with UV light (254 nm) / KMnO or Vanillin.
4
Supporting Information: page -1-Ở

Material. Ti(O-i-Pr) was distilled and stored under argon. Isopropylmagnesium
4
chloride was prepared in Et O as 1.30 – 2.25 M solution from isopropyl chloride and magnesium
2
turnings by the usual procedure, titrated and stocked under an argon atmosphere. Dry solvent
(
Et O, THF, CH Cl ) was purchased from Kanto Chemicals. Degassing of solvents and amines
2 2 2
used for Pd-catalyzed coupling reactions was accomplished by vigorously bubbling argon for at
least 1 h. Chemicals were purified or dried in a standard manner.
Preparation of Dialkynylpyridines 2.
2
2
,3-Bis[(trimethylsilyl)ethynyl]pyridine (2a).
1
This compound was prepared according to the literature procedure.
,4-Bis[(trimethylsilyl)ethynyl]pyridine (2b).
To a CH Cl (27 mL) solution of 2,4-dihydroxypyridine (1.00 g, 9.00 mmol) were added
2
2
Et N (4.60 mL, 33.0 mmol) and trifluoromethanesulfonic anhydride (3.57 mL, 21.2 mmol) at 0 °C.
3
The reaction mixture was stirred at room temperature for 12 h. After removal of the solvent, the
residue was chromatographed on silica gel (Wakogel C-200, hexane – Et O) to give 2,4-
2
bis(trifluoromethanesulfonyl)pyridine (2.60 g, 77%) as a yellow oil.
To a mixture of 2,4-bis(trifluoromethanesulfonyl)pyridine (1.70 g, 4.53 mmol), CuI (17.3
mg 0.0906 mmol), and Pd(PPh ) (52.2 mg 0.0452 mmol) in diisopropylamine (6.3 mL) was added
3
4
(
trimethylsilyl)acetylene (1.92 mL, 13.6 mmol) and the mixture was stirred for 12 h at 80 °C.
Et O and a saturated solution of NH Cl were added to the mixture at 0 °C and the organic layer was
2
4
separated, washed with brine, dried over MgSO , and concentrated in vacuo to give a crude. The
4
crude was purified by column chromatography on silica gel (Wakogel C-200, hexane – Et O) to
2
1
afford the title compound 2b (0.893 g, 73%) as a brown oil. H NMR d 8.48 (br d, J = 4.8 Hz,
1
3
1
1
1
7
H), 7.48 (br s, 1H), 7.20 (br d, J = 4.8 Hz, 1H), 0.24 (s, 9H), 0.23 (s, 9H);
C NMR d 149.70,
42.98, 131.43, 129.29, 124.78, 102.95, 101.13, 100.67, 95.50, -0.25, -0.28; IR (neat) 2960, 2160,
-
1
585, 1532, 1461, 1380, 1251, 1163, 947, 863, 760 cm ; Anal. Calcd. for C H NSi : C, 66.36; H,
15
21
2
.80; N, 5.16. Found: C, 66.04; H, 7.80; N, 5.57.
2
2
,5-Bis[(trimethylsilyl)ethynyl]pyridine (2c).
2
This compound was prepared according to the literature procedure.
,6-Bis[(trimethylsilyl)ethynyl]pyridine (2d).
Supporting Information: page -2-Ở

2
This compound was prepared according to the literature procedure.
3
,4-Bis[(trimethylsilyl)ethynyl]pyridine (2e).
3
To a mixture of 3-bromo-4-iodopyridine (1.68 g, 5.92 mmol), CuI (22.5 mg 0.118 mmol),
Pd(PPh ) (68.4 mg 0.0592 mmol), and diisopropylamine (16.6 mL, 118 mmol) in THF (8 mL) was
3
4
added (trimethylsilyl)acetylene (4.18 mL, 29.6 mmol) and the mixture was stirred for 3 days at
0 °C. Et O and a saturated solution of NH Cl were added to the mixture at 0 °C and the organic
9
2
4
layer was separated, washed with brine, dried over MgSO , and concentrated in vacuo to give a
4
crude. The crude was purified by column chromatography on silica gel (Wakogel C-200, hexane
1
–
Et O) to afford the title compound 2e (1.06 g, 66%) as a brown oil. H NMR d 8.68 (d, J = 0.9
2
1
3
Hz, 1H), 8.44 (d, J = 5.1 Hz, 1H), 7.29 (dd, J = 5.1, 0.9 Hz, 1H), 0.29 (s, 18H);
C NMR d
1
2
52.65, 147.91, 133.01, 125.10, 121.71, 104.17, 102.04, 100.38, 99.94, -0.02, -0.16; IR (neat)
-1
961, 2900, 2161, 1575, 1476, 1400, 1251, 1191, 844, 760, 701 cm ; Anal. Calcd. for
C H NSi : C, 66.36; H, 7.80. Found: C, 66.40; H, 7.62.
1
5
21
2
6
-(1-Hexynyl)-2-[(trimethylsilyl)ethynyl]pyridine (2f).
This was prepared according to the following scheme. 6-Bromo-2-iodopyridine was
4
a
1
13
synthesized from 2,6-dibromopyridine by the procedure according to the literature.
H and C
4b
spectra of 6-bromo-2-iodopridine thus synthesized were identical with the literature.
SiMe3,
i-PrMgCl (1.5 eq), THF,
2 h, then I (1.5 eq)
Pd(PPh ) Cl ,
3 2 2
CuI, Et N
3
1
2
8
9% yield
Bu
Pd(PPh ) Cl ,
67% yield
Br
Br
N
Br
Br
N
I
3
2
2
CuI, Et N
3
N
N
78% yield
SiMe3
Bu
SiMe3
To a mixture of 6-bromo-2-iodopyridine (1.16 g, 4.09 mmol), CuI (31.1 mg, 0.163 mmol),
and Pd(PPh ) Cl (57.4 mg 0.0817 mmol) in triethylamine (14 mL) was added
3
2
2
(
trimethylsilyl)acetylene (0.635 mL, 4.49 mmol) at 0 °C and the mixture was stirred for 6 h at room
temperature. After filtration, the filtrate was concentrated in vacuo to give a crude. The crude
was purified by column chromatography on silica gel (Wakogel C-200, hexane – Et O) to afford 6-
2
1
(
(
trimethylsilyl)ethynyl-2-bromopyridine (0.698 g, 67%).
H
spectrum of 6-
5
trimethylsilyl)ethynyl-2-bromopyridine thus obtained was identical with the literature.
Supporting Information: page -3-Ở

To a stirred solution of 6-(trimethylsilyl)ethynyl-2-bromopyridine (0.812 g, 3.19 mmol),
CuI (24.3 mg, 0.128 mmol), and Pd(PPh ) Cl (44.8 mg 0.0639 mmol) in triethylamine (11 mL)
3
2
2
was added 1-hexyne (0.734 mL, 6.39 mmol), and the resulting mixture was stirred for 12 h at room
temperature. The mixture was filtered and concentrated in vacuo to give a crude. The crude was
purified by column chromatography on silica gel (Wakogel C-200, hexane – Et O) to afford the
2
1
pure title compound 2f (0.634 g, 78%) as a brown oil. . H NMR d 7.54 (dd, J = 7.8, 7.8 Hz,
1
1
1
H), 7.32 (dd, J = 7.8, 0.9 Hz, 1H), 7.27 (dd, J = 7.8, 0.9 Hz, 1H), 2.40 (t, J = 6.9 Hz, 2H), 1.62-
13
.53 (m, 2H), 1.50-1.38 (m, 2H), 0.91 (t, J = 7.2 Hz, 3H), 0.23 (s, 9H);
C NMR d 144.34,
43.24, 136.22, 126.20, 125.91, 103.35, 94.92, 91.67, 79.97, 30.21, 21.92, 18.90, 13.34, -0.492;
-
1
IR (neat) 2959, 2930, 2870, 2230, 2162, 1560, 1442, 1250, 1216, 847, 810, 761 cm ; Anal. Calcd.
for C H NSi: C, 75.23; H, 8.29. Found: C, 75.52; H, 8.39.
16
21
5
-(1-Hexynyl)-2-[(trimethylsilyl)ethynyl]pyridine (2g).
To a mixture of 5-bromo-2-[(trimethylsilyl)ethynyl]pyridine (1.00 g, 3.93 mmol), CuI
30.0 mg 0.157 mmol), and Pd(PPh ) Cl (55.2 mg 0.0787 mmol) in triethylamine (16 mL) and
6
(
3
2
2
CH Cl (3 mL) was added 1-hexyne (0.678 mL, 5.90 mmol) and the mixture was stirred for 1 day
2
2
at room temperature. Et O and H O were added to the mixture at 0 °C and the organic layer was
2
2
separated, washed with brine, dried over MgSO , and concentrated in vacuo to give a crude. The
4
crude was purified by column chromatography on silica gel (Wakogel C-200, hexane – Et O) to
2
1
afford the title compound 2g (0.783 g, 78%) as an orange oil. H NMR d 8.55 (dd, J = 2.1, 0.9 Hz,
1
1
1
H), 7.60 (dd, J = 8.1, 2.1 Hz, 1H), 7.36 (dd, J = 8.1, 0.9 Hz, 1H), 2.43 (t, J = 6.9 Hz, 2H), 1.65-
13
.55 (m, 2H), 1.54-1.42 (m, 2H), 0.95 (t, J = 7.2 Hz, 3H), 0.26 (s, 9H);
C NMR d 152.50,
40.93, 138.45, 126.49, 120.60, 103.50, 96.27, 96.06, 77.27, 30.42, 21.88, 19.09, 13.44, -0.484;
-
1
IR (neat) 2959, 2933, 2870, 2230, 2164, 1540, 1466, 1363, 1250, 867, 760, 699 cm ; Anal. Calcd.
for C H NSi: C, 75.23; H, 8.29. Found: C, 75.55; H, 8.56.
16
21
4
-(1-Hexynyl)-3-[(trimethylsilyl)ethynyl]pyridine (2h).
3
Diisopropylamine (11 mL) was added to a mixture of 3-bromo-4-iodopyridine (1.08 g,
3
.80 mmol), Pd(PPh ) (44.0 mg, 0.0380 mmol), and CuI (14.5 mg, 0.0761 mmol) and then 1-
3
4
hexyne (0.656 mL, 5.71 mmol) was added to the mixture. The reaction was stirred for 12 h at
ambient temperature. The mixture was filtered and concentrated in vacuo to give a crude. The
crude was purified by column chromatography on silica gel (Wakogel C-200, hexane – AcOEt) to
3
-bromo-4-(1-hexynyl)pyridine (0.658 g, 73%) as a brown oil.
Supporting Information: page -4-Ở

To a stirred solution of to 3-bromo-4-(1-hexynyl)pyridine (0.629 g, 2.64 mmol), CuI (16.9
mg, 0.0886 mmol), and Pd(PPh ) (51.2 mg 0.0443 mmol) in diisopropylamine (6.2 mL) was added
3
4
(
trimethylsilyl)acetylene (0.940 mL, 6.65 mmol), and the resulting mixture was warmed up to
0 °C and stirred for 2 days at this temperature. The mixture was filtered and concentrated in
9
vacuo to give a crude. The crude was purified by column chromatography on silica gel (Wakogel
1
C-200, hexane – AcOEt) to afford the title compound 2h (0.372 g, 55%) as a brown oil. H NMR
d 8.63 (d, J = 0.9 Hz, 1H), 8.38 (d, J = 5.1 Hz, 1H), 7.20 (dd, J = 5.1, 0.9 Hz, 1H), 2.47 (t, J = 6.9
13
Hz, 2H), 1.66-1.55 (m, 2H), 1.54-1.43 (m, 2H), 0.94 (t, J = 7.2 Hz, 3H), 0.26 (s, 9H);
C NMR d
1
52.81, 148.16, 134.50, 125.18, 121.82, 101.45, 100.56, 100.36, 77.36, 30.36, 21.87, 19.24, 13.44,
-
1
-
0.333; IR (neat) 2959, 2933, 2870, 2230, 2160, 1577, 1478, 1400, 1250, 844, 759 cm ; Anal.
Calcd. for C H NSi: C, 75.23; H, 8.29. Found: C, 75.49; H, 8.20.
1
6
21
General Procedure for Regioselective Mono-titanation of Dialkynylpyridines 2 in Table.
(
Z)-2-[2-(trimethylsilyl)ethenyl]-3-[(trimethylsilyl)ethynyl]pyridine (3a).
To a stirred solution of 2,3-bis[(trimethylsilyl)ethynyl]pyridine (2a) (6.00 g, 22.1 mmol)
and Ti(O-i-Pr) (6.52 mL, 22.1 mmol) in 220 mL of Et O was added a 2.25 M solution of i-PrMgCl
4
2
in Et O (21.6 mL, 48.6 mmol) at –78 °C under argon to give a yellow homogeneous solution.
2
The solution was warmed up to –50 °C over 30 min, during which period its color turned brown.
After the solution was stirred at –50 °C for 2 h, H O (22 mL) was added at 0 °C. After addition of
2
NaF and Celite, the resulting mixture was filtered through a pad of Celite and concentrated in
vacuo to give a crude, which was purified by column chromatography (hexane) on silica gel
(
Wakogel C-200, hexane - Et O) to afford the title compound 3a (5.05 g, 84%) as a yellow solid.
2
1
M.p. = 33-34 °C; H NMR d 8.45 (dd, J = 4.8, 1.5 Hz, 1H), 7.72 (d, J = 14.1 Hz, 1H), 7.69 (dd, J
=
7.8, 1.5 Hz, 1H), 7.08 (dd, J = 7.8, 4.8 Hz, 1H), 6.20 (d, J = 14.1 Hz, 1H) 0.27 (s, 9H), 0.17 (s,
1
3
9
0
H);
C NMR d 156.80, 147.02, 141.16, 140.30, 139.77, 121.24, 118.32, 101.73, 101.25, 0.79,
-1
.01; IR (neat) 2957, 2898, 2157, 1547, 1420, 1250, 1164, 1096, 841 cm ; Anal. Calcd. for
C H NSi : C, 65.87; H, 8.48. Found: C, 65.62; H, 8.25.
1
5
23
2
(
Z)-2-[2-(trimethylsilyl)ethenyl]-4-[(trimethylsilyl)ethynyl]pyridine (3b).
,4-Bis[(trimethylsilyl)ethynyl]pyridine (2b) (0.137 g, 0.505 mmol) was mono-titanated
with Ti(O-i-Pr) (0.149 mL, 0.505 mmol) and a 1.61 M solution of i-PrMgCl in Et O (0.690 mL,
2
4
2
1
.11 mmol) in Et O (5 mL) as described in the general procedure. Column chromatography
2
(
Wakogel C-200, hexane - Et O) afforded the title compound 3b (0.110 g, 80%) as a pale yellow
2
Supporting Information: page -5-Ở

1
oil. H NMR d 8.49 (dd, J = 4.8, 0.6 Hz, 1H), 7.22-7.20 (m, 1H), 7.16 (d, J = 14.4 Hz, 1H), 7.14
1
3
(
dd, J = 4.8, 1.5 Hz, 1H), 6.08 (d, J = 14.4 Hz, 1H), 0.26 (s, 9H), 0.16 (s, 9H);
C NMR d 156.07,
1
48.20, 143.00, 139.01, 131.19, 125.54, 123.83, 102.22, 99.16, 0.69, -0.14; IR (neat) 2957, 2159,
-
1
1
577, 1251, 933, 838, 759 cm ; Anal. Calcd. for C H NSi : C, 65.87; H, 8.48; N, 5.12. Found:
15 23 2
C, 65.93; H, 8.79; N, 4.70.
(
Z)-2-[2-(Trimethylsilyl)ethenyl]-5-[(trimethylsilyl)ethynyl]pyridine (3c).
,5-Bis[(trimethylsilyl)ethynyl]pyridine (2c) (4.00 g, 14.7 mmol) was mono-titanated with
Ti(O-i-Pr) (4.35 mL, 14.7 mmol) and a 1.55 M solution of i-PrMgCl in Et O (20.9 mL, 32.4
2
4
2
mmol) in Et O (160 mL) as described in the general procedure. Column chromatography
2
(
Wakogel C-200, hexane - AcOEt) afforded the title compound 3c (3.56 g, 88%) as a pale yellow
1
oil. H NMR d 8.63 (d, J = 2.1 Hz, 1H), 7.67 (dd, J = 8.1, 2.1 Hz, 1H), 7.17 (d, J = 14.4 Hz, 1H),
1
3
7
1
1
.11 (d, J = 8.1 Hz, 1H), 6.11 (d, J = 14.4 Hz, 1H), 0.28 (s, 9H), 0.19 (s, 9H);
C NMR d 154.99,
51.33, 142.94, 139.85, 138.91, 122.62, 118.22, 102.11, 98.24, 0.56, -0.14; IR (neat) 2957, 2159,
-
1
586, 1539, 1475, 1363, 1251, 1024; 839 cm ; Anal. Calcd. for C H NSi : C, 65.87; H, 8.48.
15
23
2
Found: C, 65.88; H, 8.84. If the reaction was terminated by an addition of D O instead of H O,
2
2
(
Z)-2-[1,2-Bis(deuterio)-2-(trimethylsilyl)ethenyl]-5-[(trimethylsilyl)ethynyl]pyridine was obtained.
The peaks at d 7.17 ppm (alkenyl-H) and 6.11 ppm (alkenyl-H) of 3c disappeared to show 99%
deuterium incorporation in both peaks.
(
Z)-2-[2-(trimethylsilyl)ethenyl]-6-[(trimethylsilyl)ethynyl]pyridine (3d).
,6-Bis[(trimethylsilyl)ethynyl]pyridine (2d) (0.137 g, 0.505 mmol) was mono-titanated
with Ti(O-i-Pr) (0.164 mL, 0.555 mmol) and a 1.95 M solution of i-PrMgCl in Et O (0.626 mL,
2
4
2
1
.22 mmol) in Et O (5 mL) as described in the general procedure. Column chromatography
2
1
(
Wakogel C-200, hexane – Et O) afforded the title compound 3d (0.124 g, 90%). H NMR d 7.55
2
(
dd, J = 7.8, 7.8 Hz, 1H), 7.25 (dd, J = 7.8, 0.9 Hz, 1H), 7.16 (d, J = 14.1 Hz, 1H), 7.09 (dd, J = 7.8,
13
0
.9 Hz, 1H), 6.10 (d, J = 14.1 Hz, 1H), 0.28 (s, 9H), 0.23 (s, 9H);
C NMR d 156.02, 142.64,
1
41.69, 139.57, 136.16, 124.86, 122.59, 103.83, 94.40, 0.54, -0.17; IR (neat) 2957, 2157, 1557,
-
1
1
443, 1251, 1196, 1151, 1084, 970, 841, 760 cm ; Anal. Calcd. for C H NSi : C, 65.87; H, 8.48.
15 23 2
Found: C, 66.19; H, 8.22.
(
Z)-4-[2-(trimethylsilyl)ethenyl]-3-[(trimethylsilyl)ethynyl]pyridine (3e).
Supporting Information: page -6-Ở

3
,4-Bis[(trimethylsilyl)ethynyl]pyridine (2e) (0.137 g, 0.505 mmol) was mono-titanated
with Ti(O-i-Pr) (0.298 mL, 1.01 mmol) and a 1.61 M solution of i-PrMgCl in Et O (1.38 mL, 2.22
4
2
mmol) in Et O (5 mL) as described in the general procedure. Column chromatography (Wakogel
2
1
C-200, hexane – Et O) afforded the title compound 3e (0.109 g, 79%) as a brown oil. H NMR d
2
8
.63 (s, 1H), 8.44 (d, J = 5.1 Hz, 1H), 7.39 (d, J = 15.3 Hz, 1H), 7.18 (d, J = 5.1 Hz, 1H), 6.10 (d, J
1
3
=
15.3, 1H), 0.25 (s, 9H), 0.036 (s, 9H);
C NMR d 153.09, 149.53, 148.18, 142.34, 137.79,
1
8
22.20, 119.23, 102.74, 100.29, -0.17, -0.28; IR (neat) 2959, 2158, 1579, 1402, 1251, 1191, 1052,
-
1
44, 761 cm ; Anal. Calcd. for C H NSi : C, 65.87; H, 8.48. Found: C, 66.09; H, 8.47.
1
5
23
2
(
Z)-6-(1-Hexenyl)-2-[(trimethylsilyl)ethynyl]pyridine (3f).
-(1-Hexynyl)-2-[(trimethylsilyl)ethynyl]pyridine (2f) (58.6 mg, 0.229 mmol) was mono-
titanated with Ti(O-i-Pr) (0.135 mL, 0.459 mmol) and a 1.89 M solution of i-PrMgCl in Et O
6
4
2
(
0.534 mL, 1.01 mmol) in Et O (3 mL) as described in the general procedure. After being stirred
2
at -50 °C for 1 h, this reaction was terminated and column chromatography (Wakogel C-200,
hexane – Et O) afforded the title compound 3f (41.4 mg, 70%) as a pale yellow oil and the site-
2
isomer, 2-(1-hexynyl)-6-[(trimethylsilyl)ethenyl]pyridine, (9.50 mg, 16%) as a pale yellow oil.
1
3
f: H NMR d 7.56 (dd, J = 7.8, 7.8 Hz, 1H), 7.26 (d, J = 7.8 Hz, 1H), 7.17 (d, J = 7.8 Hz, 1H),
.43 (d, J = 11.7 Hz, 1H), 5.88 (dt J = 11.7, 7.5 Hz, 1H), 2.47 (dt, J = 7.5, 7.5 Hz, 2H), 1.50-1.30
6
1
3
(
m, 4H), 0.88 (t, J = 7.1 Hz, 3H), 0.25 (s, 9H);
C NMR d 157.12, 142.62, 137.81, 135.95,
1
2
5
28.43, 124.87, 123.05, 104.11, 93.98, 31.61, 28.35, 22.24, 13.74, -0.44; IR (neat) 2959, 2927,
-
1
858, 2158, 1641, 1561, 1447, 1405, 1251, 846, 760, 732 cm ; Anal. Calcd. for C H NSi: N,
1
6
23
1
.44. Found: N, 5.48. The site-isomer, 2-(1-hexynyl)-6-[(trimethylsilyl)ethenyl]pyridine:
H
NMR d 7.53 (dd, J = 7.8, 7.8 Hz, 1H), 7.18, (d, J = 7.8 Hz, 1H), 7.16 (d, J = 14.4 Hz, 1H), 7.05 (d,
J = 7.8 Hz, 1H), 6.06 (d, J = 14.4 Hz, 1H), 2.44 (t, J = 6.9 Hz, 2H), 1.65-1.48 (m, 4H), 0.95 (d, J =
1
3
7
9
1
.2 Hz, 3H), 0.21 (s, 9H).
C NMR d 156.27, 143.30, 143.03, 139.21, 136.24, 124.98, 122.01,
0.76, 80,39, 30.46, 21.83, 18.81, 13.44, 0.29; IR (neat) 2957, 2871, 2230, 1564, 1445, 1414,
-
1
241, 1088, 842, 745, 655 cm .
(
Z)-5-(1-Hexynyl)-2-[(trimethylsilyl)ethenyl]pyridine (3g).
-(1-Hexynyl)-2-[(trimethylsilyl)ethynyl]pyridine (2g) (0.103 g, 0.403 mmol) was mono-
titanated with Ti(O-i-Pr) (0.119 mL, 0.403 mmol) and a 1.62 M solution of i-PrMgCl in Et O
5
4
2
(
0.548 mL, 0.887 mmol) in Et O (4 mL) as described in the general procedure. Column
2
chromatography (Wakogel C-200, hexane – Et O) afforded the title compound 3g (0.0771 g, 74%)
2
Supporting Information: page -7-Ở

1
as a pale yellow oil. H NMR d 8.57 (d, J = 1.8 Hz, 1H), 7.59 (dd, J = 8.1, 1.8 Hz, 1H), 7.17 (d, J
=
14.4 Hz, 1H), 7.08 (d, J = 8.1 Hz, 1H), 6.07 (d J = 14.4 Hz, 1H), 2.43 (t, J = 6.9 Hz, 2H), 1.64-
1
3
1
1
2
7
.42 (m, 4H), 0.96 (t, J = 7.2 Hz, 3H), 0.16 (s, 9H);
C NMR d 154.42, 151.12, 143.28, 138.99,
38.60, 122.74, 119.27, 94.20, 77.81, 30.59, 21.90, 19.09, 13.50, 0.42; IR (neat) 2957, 2870,
-
1
230, 1588, 1534, 1483, 1364, 1240, 1212, 847, 765, 664 cm ; Anal. Calcd. for C H NSi: C,
1
6
23
4.65; H, 9.00. Found: C, 74.37; H, 9.01.
(
Z)-4-(1-Hexenyl)-3-[(trimethylsilyl)ethenyl]pyridine (3h).
-(1-Hexynyl)-3-[(trimethylsilyl)ethynyl]pyridine (2h) (58.7 mg, 0.230 mmol) was mono-
titanated with Ti(O-i-Pr) (0.136 mL, 0.460 mmol) and a 1.89 M solution of i-PrMgCl in Et O
4
4
2
(
0.535 mL, 1.01 mmol) in Et O (3 mL) as described in the general procedure. Column
2
chromatography (Wakogel C-200, hexane – Et O) afforded the title compound 3h (49.3 mg, 83%)
2
1
as a yellow oil. H NMR d 8.65 (s, 1H), 8.43 (d, J = 5.1 Hz, 1H), 7.19 (d, J = 5.1 Hz, 1H), 6.56 (d,
J = 12.0 Hz, 1H), 5.91 (dt J = 12.0, 7.5 Hz, 1H), 2.25 (dt, J = 7.5, 7.5 Hz, 2H), 1.50-1.28 (m, 4H),
1
3
0
.87 (t, J = 6.9 Hz, 3H), 0.24 (s, 9H);
C NMR d 153.41, 148.20, 147.08, 137.87, 125.15, 122.64,
1
19.44, 102.25, 100.59, 31.59, 28.57, 22.18, 13.72, -0.30; IR (neat) 3017, 2959, 2928, 2861,
-
1
2
157, 1581, 1472, 1401, 1250, 843, 761, 658 cm ; Anal. Calcd. for C H NSi: C, 74.65; H, 9.00.
16 23
Found: C, 74.58; H, 8.76.
Synthesis of Conjugated Oligomers in Scheme 1.
(
E)-2-(2-Bromoethenyl)-5-[(trimethylsilyl)ethynyl]pyridine (4).
To a stirred solution of (Z)-2-[2-(trimethylsilyl)ethenyl]-5-[(trimethylsilyl)ethynyl]pyridine
3c) (6.75 g, 24.7 mmol) in CH Cl (50 mL), cooled to –78 °C, was added slowly a solution of Br
(
(
2
2
2
1.58 mL, 30.8 mmol) in CH Cl (15 mL). To the resulting orange / red solution were added
2
2
MeOH (250 mL) and Na SO (12.3 g), and the resulting mixture was stirred until it became light
2
3
yellow. While still at –78 °C, the reaction mixture was poured into 10% Na SO solution, and
2
3
shaken until all color had disappeared. After separation, the aqueous layer was extracted
thoroughly with pentane, and the combined organic extracts dried. The solution was concentrated
in vacuo to give the crude of 2-[1,2-di(bromo)ethyl]-5-[(trimethylsilyl)ethynyl]pyridine, which was
used immediately.
The crude was dissolved in MeOH (250 mL) and THF (60 mL), and treated with MeONa
(
2.00 g, 37.0 mmol) at 0 °C. The resulting mixture was stirred at this temperature for 1 h, and
then at ambient temperature for 2 h. It was then partitioned between pentane and H O, and the
2
Supporting Information: page -8-Ở

aqueous layer was extracted thoroughly with pentane. The combined organic extracts were dried
and concentrated in vacuo to give acrude. The crude was purified by column chromatography on
silica gel (Wakogel C-200, hexane – AcOEt) to afford (E)-2-(2-Bromoethenyl)-5-ethynylpyridine
(
3.49 g, 68% overall yield from 3c).
To a stirred solution of (E)-2-(2-Bromoethenyl)-5-ethynylpyridine (1.51 g, 7.26 mmol) in
THF (24 mL) was added NaN[SiMe ] (9.44 mL, 1.00 mol/L in THF, 9.44 mmol) at –78 °C.
3
2
After being stirred for 1 h, Me SiCl (1.38 mL, 10.9 mmol) was added to the reaction mixture.
3
And then the mixture was warmed up to room temperature and stirred for 12 h. The reaction was
terminated by an addition of H O. The resulting mixture was extracted with Et O, washed with
2
2
brine, dried over MgSO , and concentrated in vacuo to give a crude. The crude was purified by
4
column chromatography on silica gel (Wakogel C-200, hexane – Et O) to afford the title compound
2
1
4
(1.74 g, 86%) as a yellow oil. H NMR d 8.59 (dd, J = 2.4, 0.6 Hz, 1H), 7.68 (dd, J = 8.1, 2.4
Hz, 1H), 7.41 (d, J = 13.8, Hz, 1H), 7.11 (d, J = 13.8 Hz, 1H), 7.09 (dd, J = 8.1, 0.6 Hz, 1H), 0.26
1
3
(
s, 9H);
C NMR d 152.75, 152.52, 139.44, 135.94, 120.77, 119.08, 113.98, 101.54, 99.07, 0.23;
-
1
IR (neat) 2959, 2159, 1473, 1250, 1163, 1023, 936, 843 cm ; Anal. Calcd. for C H BrNSi: C,
12
14
5
1.43; H, 5.04; N, 5.00. Found: C, 51.48; H, 5.05. N, 5.06.
(
E)-2-(1-Tetradecen-3-yn-1-yl)-5-[(trimethylsilyl)ethynyl]pyridine (Monomer 5).
To a mixture of 4 (1.07 g, 3.80 mmol), Pd(PPh ) Cl (53.4 mg, 0.0761 mmol), CuI (29.0 mg,
3
2
2
0
.152 mmol), and triethylamine (4.98 mL, 35.7 mmol) in THF (40 mL) was added 1-dodecyne
(
1.05 mL, 4.94 mmol) at 0 °C and the reaction mixture was stirred at this temperature for 30 min.
Et O and water were added to the mixture and the organic layer was separated, washed with brine,
2
dried over MgSO , and concentrated in vacuo to give a crude. The crude was purified by column
4
chromatography on silica gel (Wakogel C-200, hexane – Et O) to afford the title compound 5 (1.24
2
1
g, 90%) as a brown oil. H NMR d 8.58 (d, J = 1.8 Hz, 1H), 7.64 (dd, J = 8.1, 1.8 Hz, 1H), 7.12 (d,
J = 8.1 Hz, 1H), 6.84 (d, J = 15.6 Hz, 1H), 6.72 (dt, J = 15.6, 2.1 Hz, 1H), 2.37 (dt, J = 2.1, 6.9 Hz,
2
9
7
2
H), 1.61-1.51 (m, 2H), 1.46-1.34 (m, 2H), 1.33-1.22 (m, 12H), 0.88 (t, J = 6.9 Hz, 3H), 0.25 (s,
1
3
H);
C NMR d 153.54, 152.52, 139.16, 138.18, 120.79, 118.84, 114.75, 101.90, 98.81, 96.50,
9.69, 31.89, 29.56, 29.51, 29.30, 29.13, 28.89, 28.65, 22.66, 19.79, 14.08, -0.18; IR (neat) 2926,
-1
855, 2210, 2158, 1615, 1582, 1471, 1371, 1250, 955, 863, 760 cm . UV/Vis (CHCl ) l (e)
3
abs
+
[
(
nm] = 294 (21 500), 325 (37 100); MS (EI) m/z (relative intensity), 365 (30.7, M ), 252 (100), 226
61.9); Anal. Calcd for C H NSi: C, 78.84; H, 9.65. Found: C, 78.64; H, 9.62.
24
35
Supporting Information: page -9-Ở

Dimer (6).
To a stirred solution of the monomer 5 (1.14 g, 3.13 mmol) in THF (10 mL) was added
TBAF (3.13 mL, 1.0 mol/L in THF, 3.13 mmol) and the mixture was stirred for 1 h at 0 °C. The
reaction mixture was extracted with Et O, dried over MgSO , and concentrated in vacuo to give a
2
4
crude of the desilylated monomer. The terminal acetylene derivative was used for the next step
without further purification.
To a mixture of 4 (1.05 g 3.75 mmol), Pd(PPh ) (72.2 mg, 0.0625 mmol), and CuI (23.8 mg,
3
4
0
.125 mmol) in degassed i-Pr NH (1.97 mL, 14.1 mmol) was added a solution of the desilylated
2
monomer in degassed THF (16 mL). The reaction mixture was stirred at room temperature for 1 h
and extracted with Et O, washed with brine, dried over MgSO and concentrated in vacuo to afford
2
4
a crude product, which was chromatographed on silica gel (Wakogel C-200, hexane - Et O) to yield
2
the dimer 6 (1.20 g, 78% overall yield from the monomer 5) as a yellow solid. M.p. = 125-
1
1
1
1
2
26 °C; H NMR d 8.63 (d, J = 2.1 Hz, 1H) 8.62 (d, J = 2.4 Hz, 1H), 7.68 (dd, J = 7.8, 2.4 Hz,
H), 7.67 (dd, J = 8.1, 2.1 Hz, 1H), 7.18 (d, J = 7.8 Hz, 1H), 7.16 (d, J = 8.1 Hz, 1H), 7.05 (d, J =
5.9 Hz, 1H), 6.98 (d, J = 15.9 Hz, 1H), 6.86 (d, J = 15.9 Hz, 1H), 6.75 (dt, J = 15.9, 2.1 Hz, 1H),
.38 (dt, J = 2.1, 6.9 Hz, 2H), 1.62-1.51 (m, 2H), 1.48-1.22 (m, 14H), 0.88 (t, J = 6.9 Hz, 3H), 0.26
13
(
s, 9H);
C NMR d 153.53, 152.76, 152.67, 152.22, 140.00, 139.30, 138.80, 138.17, 121.59,
1
2
1
21.06, 119.45, 118.87, 114.79, 113.07, 101.72, 99.41, 96.69, 92.60, 91.48, 79.72, 31.88, 29.56,
9.51, 29.30, 29.13, 28.90, 28.64, 22.67, 19.80, 14.10, -0.20; IR (KBr) 2922, 2852, 2188, 2154,
-
1
575, 1469, 1369, 1250, 954, 858, 758 cm ; UV/Vis (CHCl ) l (e) [nm] = 256 (15 700), 294
3
abs
(
17 600), 367 (66 300), 389 (51 100); MALDI-TOF-MS (DHB) 492.9 (Calcd for C H N Si:
33 40 2
4
92.3); Anal. Calcd for C H N Si: C, 80.43; H, 8.18; N, 5.68. Found: C, 80.54; H, 8.11; N, 5.98.
33 40 2
Trimer (7).
The dimer 6 (1.10 g, 2.23 mmol) was desilylated with TBAF (2.23 mL, 1.0 mol/L in THF,
.23 mmol) and the resulting terminal acetylene was cross-coupled with vinyl bromide 4 (0.751 g,
.68 mmol) in degassed CHCl (22 mL) in the presence of Pd(PPh ) (77.4 mg, 0.0670 mmol), CuI
2
2
3
3 4
(
25.5 mg, 0.134 mmol), and degassed i-Pr NH (2.03 mL, 14.5 mmol) for 1 h as described in the
2
procedure for synthesis of 6. The reaction was extracted with CHCl and recrystallization from
3
CHCl - hexane afforded the trimer 7 (1.00 g, 73% overall yield from the dimer 6) as a yellow solid.
3
1
M.p. = >220 °C (decoloration from yellow to brown); H NMR d 8.68-8.64 (m, 1H), 8.64-8.61 (m,
2
7
H), 7.71 (dd, J = 7.8, 2.1 Hz, 1H), 7.70 (dd, J = 7.8, 2.4 Hz, 1H), 7.68 (dd, J = 7.8, 2.1 Hz, 1H),
.26-7.17 (m, 2H), 7.17 (d, J = 7.8 Hz, 1H), 7.073 (d, J = 15.9 Hz, 1H), 7.070 (d, J = 15.9 Hz, 1H),
Supporting Information: page -10-Ở

7
.00 (d, J = 15.9 Hz, 1H), 6.99 (d, J = 15.9 Hz, 1H), 6.87 (d, J = 15.9 Hz, 1H), 6.75 (dt, J = 15.9,
.1 Hz, 1H), 2.39 (dt, J = 2.1, 6.6 Hz, 2H), 1.63-1.51 (m, 2H), 1.47-1.22 (m, 14H), 0.88 (t, J = 7.2
2
1
3
Hz, 3H), 0.27 (s, 9H);
C NMR d 153.70, 152.94, 152.83 (x2), 152.52, 152.36, 140.33, 140.11,
1
1
2
1
39.43, 139.03, 138.93, 138.28, 121.89, 121.71, 121.13, 119.60 (x2), 118.96, 114.90, 113.20,
13.06, 101.75, 99.55, 96.75, 93.10, 92.71, 91.65, 91.37, 79.74, 31.81, 29.48, 29.43, 29.22, 29.05,
8.82, 28.56, 22.57, 19.72, 13.98, -0.33; IR (KBr) 2922, 2852, 2203, 2152, 1572, 1468, 1367,
-
1
250, 956, 855, 757 cm . UV/Vis (CHCl ) l (e) [nm] = 282 (22 200), 391 (86 400); MALDI-
3
abs
TOF-MS (DHB) 619.8 (Calcd for C H N Si: 619.3); Anal. Calcd for C H N Si: C, 81.37; H,
42
45
3
42 45
3
7
.32. Found: C, 81.46; H, 7.32.
Tetramer (8).
The trimer 7 (100 mg, 0.161 mmol) was desilylated with TBAF (0.161 mL, 1.0 mol/L in
THF, 0.161 mmol) and the resulting terminal acetylene was cross-coupled with vinyl bromide 4
(
54.2 mg g, 0.194 mmol) in degassed CHCl (40 mL) in the presence of Pd(PPh ) (37.3 mg, 0.0323
3 3 4
mmol), CuI (12.3 mg, 0.0645 mmol), and degassed i-Pr NH (0.147 mL, 1.05 mmol) for 1 h as
2
described in the procedure for synthesis of 6. The reaction was extracted with CHCl and column
3
chromatography on silica gel (Wakogel C-200, hexane – CHCl ) and the following recrystallization
3
from CHCl - hexane afforded the tetramer 8 (62.2 mg, 52% overall yield from the trimer 7) as a
3
1
yellow solid. M.p. = >250 °C (decoloration from yellow to brown); H NMR d 8.70-8.66 (m,
2
H), 8.65-8.60 (m, 2H), 7.76-7.64 (m, 4H), 7.26-7.20 (m, 3H), 7.17 (d, J = 7.8 Hz, 1H), 7.12-6.98
(
m, 5H), 7.00 (d, J = 15.9 Hz, 1H), 6.87 (d, J = 15.3 Hz, 1H), 6.82-6.72 (m, 1H), 2.44-2.34 (m, 2H),
1
2
=
.62-1.46 (m, 2H), 1.36-1.18 (m, 14H), 0.88 (t, J = 6.9 Hz, 3H), 0.27 (s, 9H); IR (KBr) 2923,
-
1
852, 2190, 2153, 1570, 1543, 1468, 1368, 1251, 957, 859 cm . UV/Vis (CHCl ) l (e) [nm]
3
abs
285 (24 600), 329 (35 300), 398 (108 700); MALDI-TOF-MS (DHB) 747.2 (Calcd for
C H N Si: 746.4); Anal. Calcd for C H N Si: N, 7.50. Found: N, 7.57. Solubility was too low
5
1
50
4
51 50
4
13
to measure the C NMR spectrum.
Determination of the Structure of 3a-c and 3e.
The structures of 3a-c and 3e were confirmed in comparison with the corresponding
authentic sample prepared according to the following schemes. The yields are not necessarily
optimized.
For 3a
Supporting Information: page -11-Ở

AcO
HO
TfO
DIBAL-H
3%
Tf O, Et N
2 3
N
N
N
5
54%
Me Si
Me Si
Me Si
3
3
3
SiMe3,
Pd(PPh3)4,
CuI, i-Pr NH
74%
Ti(O-i-Pr)4/
i-PrMgCl Me Si
Me
3
Si
TfO
2
2
3
Me Si
3
8
4%
N
N
3a
3
-[(Trifluoromethane)sulfonyl]oxy-2-[(trimethylsilyl)ethynyl]pyridine.
7
To 3-acetoxy-2-[(trimethylsilyl)ethynyl]pyridine (1.29 g, 5.53 mmol) in Et O (18 mL) was
2
added DIBAL-H (14.0 mL, 0.95 mol/L in hexane, 13.3 mmol) at -78 °C and warmed up to 0 °C
over 2 h and then the reaction mixture was stirred for 30 min at this temperature. After H O (1.5
2
mL) was cautiously added to the mixture, NaF (1.7 g) and Celite (1.4 g) were successively added to
the resulting mixture. The mixture was filtered through Celite pad, and then the filtrate was
evaporated to give a crude, which was recrystallized from Et O – hexane to afford 3-hydroxy-2-
2
1
[
(trimethylsilyl)ethynyl]pyridine (0.558 g, 53%). H spectrum of this product was identical with
8
the literature.
To a stirred solution of 3-hydroxy-2-[(trimethylsilyl)ethynyl]pyridine (0.549 g, 2.87 mmol)
and Et N (0.880 mL, 6.31 mmol) in CH Cl (9 mL) was added trifluoromethanesulfonic anhydride
3
2
2
(
0.579 mL, 3.44 mmol) at 0 °C and the reaction mixture was stirred for 8 h at room temperature.
H O was added to the mixture at 0 °C and the organic layer was separated, washed with brine, dried
2
over MgSO , and concentrated in vacuo to give a crude. The crude was purified by column
4
chromatography on silica gel (Wakogel C-200, hexane – AcOEt) to afford the title compound
1
(
0.499 g, 54%). H NMR d 8.54 (dd, J = 4.5, 1.2 Hz, 1H), 7.59 (dd, J = 8.4, 1.2 Hz, 1H), 7.32 (dd,
1
3
J = 8.4, 4.5 Hz, 1H), 0.25 (s, 9H);
C NMR d 149.30, 147.92, 137.33, 129.31, 124.03, 118.64 (q,
JC-F = 319.3 Hz), 104.27, 96.94, -0.90.
-[(Trifluoromethane)sulfonyl]oxy-2-[(trimethylsilyl)ethenyl]pyridine.
To stirred solution of 3-[(Trifluoromethane)sulfonyl]oxy-2-
(trimethylsilyl)ethynyl]pyridine (0.513 g, 1.59 mmol) and Ti(O-i-Pr) (0.702 mL, 2.38 mmol) in
3
a
[
4
1
6 mL of Et O was added a 1.38 M solution of i-PrMgCl in Et O (3.45 mL, 4.76 mmol) at –78 °C.
2 2
The solution was warmed up to –50 °C over 30 min and stirred at this temperature for 2 h. The
reaction was terminated by an addition of H O (2.4 mL). After addition of NaF and Celite, the
2
resulting mixture was filtered through a pad of Celite and concentrated in vacuo to give a crude,
which was purified by column chromatography on silica gel (Wakogel C-200, hexane - Et O) to
2
Supporting Information: page -12-Ở

1
afford the title compound (0.434 g, 84%). H NMR d 8.55 (dd, J = 4.2, 1.2 Hz, 1H), 7.59 (dd, J =
8
0
.1, 1.2 Hz, 1H), 7.43 (d, J = 14.7 Hz, 1H), 7.26 (dd, J = 8.1, 4.2 Hz, 1H), 6.35 (d, J = 14.7 Hz, 1H),
1
3
.16 (s, 9H);
C NMR d 149.07, 147.66, 144.28, 143.67, 135.11, 129.23, 123.31, 118.51 (q, JC-F
=
318.4 Hz), 0.30.
(
Z)-2-[2-(trimethylsilyl)ethenyl]-3-[(trimethylsilyl)ethynyl]pyridine (3a).
To a mixture of 3-[(Trifluoromethane)sulfonyl]oxy-2-[(trimethylsilyl)ethenyl]pyridine
0.349 g, 1.07 mmol), CuI (25.7 mg 0.135 mmol), and Pd(PPh ) (78.0 mg 0.0675 mmol) in
(
3
4
diisopropylamine (1.8 mL) was added (trimethylsilyl)acetylene (0.420 mL, 2.97 mmol) and the
mixture was stirred for 3 day at 80 °C. Et O and H O were added to the mixture and the organic
2
2
layer was separated, washed with brine, dried over MgSO , and concentrated in vacuo to give a
4
crude. The crude was purified by column chromatography on silica gel (Wakogel C-200, hexane
–
Et O) to afford the title compound 3a (0.278 g, 95%). Physical properties of the authentic
2
sample thus synthesized were identical with those of 3a obtained by the mono-titanation of 2a.
For 3b
SiMe3
Br
CHO
CBr , PPh
Br
Cl
n-BuLi, Me SiCl
4
3
3
2
4%
51%
Cl
N
N
Cl
N
N
SiMe3,
SiMe3
Ti(O-i-Pr)4/
i-PrMgCl
SiMe3 Pd(PPh3)4,
2
CuI, Et N
3
2
0%
11%
Cl
N
Me Si
3
regioisomer of 3b
2
-Chloro-4-(2,2-dibromoethenyl)pyridine.
To a solution of CBr (13.1 g, 39.4 mmol) in CH Cl (41 mL) was added a CH Cl (30 mL)
4
2
2
2
2
solution of PPh (20.7 g, 78.8 mmol) at 0 °C. After being stirred for 5 min, a solution of 2-chloro-
3
9
4
-pyridinecarboxaldehyde (1.86 g, 13.1 mmol) in CH Cl (30 mL) was introduced to the mixture
2
2
and the resulting mixture was stirred for 20 min at room temperature. H O was added to the
2
mixture at 0 °C and the organic layer was separated with CH Cl , washed with brine, dried over
2
2
MgSO , and concentrated in vacuo to give a crude. The crude was purified by column
4
chromatography on silica gel (Wakogel C-200, hexane – AcOEt) to afford the title compound
1
(
0.948 g, 24%). H NMR d 8.40 (dd, J = 5.1, 0.6 Hz, 1H), 7.47 (ddd, J = 1.5, 0.75, 0.6 Hz, 1H),
Supporting Information: page -13-Ở

13
7
1
2
.39 (dd, J = 0.75, 0.6 Hz, 1H), 7.36 (ddd, J = 5.1, 1.5, 0.6 Hz, 1H);
45.58, 133.34, 123.01, 121.26, 95.88.
C NMR d 152.12, 150.03,
-Chloro-4-[(trimethylsilyl)ethynyl]pyridine.
To a stirred solution of 2-Chloro-4-(2,2-dibromoethenyl)pyridine (0.726 g, 2.44 mmol) in
THF (8 mL) was added n-BuLi (3.22 mL, 1.59 mol/L in hexane, 5.12 mmol) at -78 °C After
stirring for 30 min, chlorotrimethylsilane (0.465 mL, 3.66 mmol) was added. After stirring at
-
78 °C for 1 h, the reaction mixture was warmed up to room temperature and stirred for 30 min.
The reaction was terminated by an addition of H O. The organic layer was separated and the
2
aqueous layer was extracted with Et O. The combined organic layers were washed with brine,
2
dried over MgSO , and concentrated to give a crude, which was chromatographed on silica gel
4
1
(
Wakogel C-200, hexane – AcOEt) to afford the title compound (0.261 g, 51%). H NMR d 8.32
dd, J = 5.1, 0.9 Hz, 1H), 7.35 (dd, J = 1.2, 0.9 Hz, 1H), 7.21 (dd, J = 5.1, 1.2 Hz, 1H), 0.25 (s, 9H);
(
1
3
C NMR d 151.76, 149.63, 134.14, 126.45, 124.49, 101.87, 100.55, -0.59.
-Chloro-4-[(trimethylsilyl)ethenyl]pyridine.
2
To a stirred solution 2-Chloro-4-[(trimethylsilyl)ethynyl]pyridine (0.233 g, 1.11 mmol) and
Ti(O-i-Pr) (0.492 mL, 1.67 mmol) in 11 mL of Et O was added a 1.30 M solution of i-PrMgCl in
4
2
Et O (2.56 mL, 3.33 mmol) at –78 °C. The solution was warmed up to –50 °C over 30 min and
2
stirred at this temperature for 2 h. The reaction was terminated by an addition of H O (1.7 mL).
2
After addition of NaF and celite, the resulting mixture was filtered through a pad of Celite and
concentrated in vacuo to give a crude, which was purified by column chromatography on silica gel
1
(
Wakogel C-200, hexane - AcOEt) to afford the title compound (0.0461 g, 20%). H NMR d 8.32
dd, J = 5.1, 0.6 Hz, 1H), 7.20 (dd, J = 1.5, 0.6 Hz, 1H), 7.18 (d, J = 15.0 Hz, 1H), 7.08 (dd, J = 5.1,
(
1
3
1
1
4
.5 Hz, 1H), 6.11 (d, J = 15.0 Hz, 1H), 0.077 (s, 9H);
C NMR d 151.62, 150.81, 149.40, 142.16,
39.22, 123.30, 121.64, -0.17.
-(Trimethylsilyl)ethenyl-2-[(trimethylsilyl)ethynyl]pyridine.
To a mixture of 2-Chloro-4-[(trimethylsilyl)ethenyl]pyridine (43.8 mg, 0.207 mmol), CuI
(
15.8 mg 0.0827 mmol), and Pd(PPh ) Cl (29.0 mg 0.0414 mmol) in triethylamine (1 mL) was
3 2 2
added (trimethylsilyl)acetylene (87.7 mL, 0.621 mmol) and the mixture was stirred for 3 days at
10 °C The reaction mixture was filtered and the filtrate was concentrated in vacuo to give a
crude. The crude was purified by column chromatography on silica gel (Wakogel C-200, hexane
1
–
AcOEt) to afford the title compound (6.40 mg, 11%) which is the site-isomer of 3b obtained by
1
the mono-titanation of 2b. H NMR d 8.50 (dd, J = 5.1, 0.9 Hz, 1H), 7.33 (dd, J = 1.5, 0.9 Hz,
1
H), 7.19 (d, J = 15.3 Hz, 1H), 7.10 (dd, J = 5.1, 1.5 Hz, 1H), 6.07 (d, J = 15.3 Hz, 1H), 0.27 (s,
Supporting Information: page -14-Ở

1
3
9
9
H), 0.067 (s, 9H);
C NMR d 149.76, 147.98, 143.00, 142.90, 138.37, 126.63, 122.14, 103.73,
-
1
4.83, -0.11, -0.44; IR (neat) 2960, 2901, 2162, 1583, 1538, 1463, 1389, 1251, 844, 763, 657 cm .
For 3c
SiMe3,
Br
Ti(O-i-Pr)4/
i-PrMgCl
Pd(PPh ) Cl ,
SiMe3
3 2
2
Br
2
CuI, Et N
Me Si
3
3
Me Si
3
N
74%
82%
N
Me Si
N
3
3c
(
Z)-2-[2-(trimethylsilyl)ethenyl]-5-[(trimethylsilyl)ethynyl]pyridine (3c).
6
To a stirred solution 5-bromo-2-[(trimethylsilyl)ethynyl]pyridine (0.298 g, 1.17 mmol) and
Ti(O-i-Pr) (0.415 mL, 1.41 mmol) in 10 mL of Et O was added a 1.61 M solution of i-PrMgCl in
4
2
Et O (1.75 mL, 2.81 mmol) at –78 °C. The solution was warmed up to –50 °C over 30 min and
2
stirred at this temperature for 2 h. The reaction was terminated by an addition of H O (1.4 mL).
2
After addition of NaF and Celite, the resulting mixture was filtered through a pad of Celite and
concentrated in vacuo to give a crude, which was purified by column chromatography on silica gel
(
Wakogel C-200, hexane - Et O) to afford 5-bromo-2-[(trimethylsilyl)ethenyl]pyridine (0.222 g,
2
7
4%).
To a mixture of 5-bromo-2-[(trimethylsilyl)ethenyl]pyridine (0.206 g, 0.804 mmol), CuI
30.6 mg 0.161 mmol), and Pd(PPh ) Cl (56.4 mg 0.0804 mmol) in triethylamine (3.2 mL) and
(
3
2
2
CH Cl (0.6 mL) was added (trimethylsilyl)acetylene (0.170 mL, 1.21 mmol) and the mixture was
2
2
stirred for 6 h at room temperature. Et O and H O were added to the mixture and the organic layer
2
2
was separated, washed with brine, dried over MgSO , and concentrated in vacuo to give a crude.
4
The crude was purified by column chromatography on silica gel (Wakogel C-200, hexane – Et O)
2
to afford the title compound 3c (0.180 g, 82%). Physical properties of the authentic sample thus
synthesized were identical with those of 3c obtained by the mono-titanation of 2c.
For 3e
Me Si
SiMe3,
3
Ti(O-i-Pr)4/
i-PrMgCl
SiMe3 Pd(PPh ) Cl , Me Si
SiMe3
3 2
2
3
2
CuI, Et N
3
Br
Br
6
7%
82%
N
N
N
3e
3
-Bromo-4-[(trimethylsilyl)ethenyl]pyridine.
Supporting Information: page -15-Ở

3
To a stirred solution 3-bromo-4-[(trimethylsilyl)ethynyl]pyridine (0.670 g, 2.64 mmol) and
Ti(O-i-Pr) (1.01 mL, 3.43 mmol) in 26 mL of Et O was added a 1.30 M solution of i-PrMgCl in
4
2
Et O (5.27 mL, 6.85 mmol) at –78 °C. The solution was warmed up to –50 °C over 30 min and
2
stirred at this temperature for 2 h. The reaction was terminated by an addition of H O (3.4 mL).
2
After addition of NaF and Celite, the resulting mixture was filtered through a pad of Celite and
concentrated in vacuo to give a crude, which was purified by column chromatography on silica gel
1
(
Wakogel C-200, hexane - Et O) to afford the title compound (0.452 g, 67%). H NMR d 8.68 (s,
2
1
1
H), 8.45 (d, J = 5.1 Hz, 1H), 7.182 (d, J = 14.7 Hz, 1H), 7.181 (d, J = 5.1 Hz, 1H), 6.11 (d, J =
1
3
4.7 Hz, 1H), -0.014 (s, 9H);
C NMR d 151.72, 148.22, 147.88, 142.87, 137.90, 124.61, 121.57,
-
0.28.
(
Z)-4-[2-(trimethylsilyl)ethenyl]-3-[(trimethylsilyl)ethynyl]pyridine (3e).
To a mixture of 3-bromo-4-[(trimethylsilyl)ethenyl]pyridine (0.422 g, 1.65 mmol), CuI
21.9 mg 0.115 mmol), and Pd(PPh ) Cl (40.3 mg 0.0574 mmol) in triethylamine (7.7 mL) was
(
3
2
2
added (trimethylsilane)acetylene (0.406 mL, 2.87 mmol) and the mixture was stirred for 3 days at
10 °C. The reaction mixture was filtered and the filtrate was concentrated in vacuo to give a
crude. The crude was purified by column chromatography on silica gel (Wakogel C-200, hexane
AcOEt) to afford the title compound 3e (0.371 g, 82%). Physical properties of the authentic
1
–
sample thus synthesized were identical with those of 3e obtained by the mono-titanation of 2e.
Figure 1. Electronic Absorption Spectra of 5-8.
Supporting Information: page -16-Ở

Figure 2. Fluorescence spectra of 5-8.
References
(
(
(
(
1)
2)
3)
4)
Kim, C.-S.; Russell, K. C. J. Org. Chem. 1998, 63, 8229-8234.
Bunten, K. A.; Kakkar, A. K. Macromolecules 1996, 29, 2885-2893.
Baxter, P. N. W. Chem. Eur. J. 2003, 9, 2531-2541.
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Supporting Information: page -17-Ở