1
616
S. Hermes et al. / Tetrahedron Letters 50 (2009) 1614–1617
by typical Suzuki cross-coupling. The results presented here offer
the possibility to obtain a number of different 1,2-diarylethenes
compounds in a very fast and high yielding process.
CHCl
for 2 h at room temperature, and subsequently poured into H
water layer was extracted with dichloromethane (3 Â 50 ml). The combined
organic phases were dried (Na SO ), filtered, and the solvent was evaporated in
3
(75 ml). After addition of the bromine, the reaction mixture was stirred
2
O (100 ml). The
2
4
vacuo. The product was finally cleaned by vacuum distillation (40 °C,
À2
colorless liquid (14.5 g, 91%). 1H NMR (400 MHz,
1
0
mbar) to yield
a
Acknowledgments
+
CDCl
5. Dixon, S. J. Org. Chem. 1956, 21, 400–403.
36. Procedure for the synthesis
thienyl]hexafluorocyclopentene (2): To
3
): d 2.32 (s, 3H), 6.73 (s, 1H) ppm; EI-MS: m/z 211 [M ].
3
We are grateful for the Feodor Lynen-fellowship (to S. H.) from
the Alexander von Humboldt-foundation (Germany). This work has
been partly supported by the Italian Scientific and Technological
Research Ministry through FIRB project RBNE033KMA ‘Composti
molecolari e materiali ibridi nanostrutturati con proprietà ottiche
risonanti e non risonanti per dispositivi fotonici’ and PRIN 2006
project ‘Photochromic polymers as active materials for innovative
reference surfaces for optical interferometry’.
of
a
1,2-bis-[2-methyl-5-chloro-3-
stirred solution of (3.0 g,
1
1
1
4.2 mmol) in THF (100 ml), n-Butyllithium (6.2 ml, 2.5 M in hexane,
5.6 mmol) was added dropwise at À78 °C under argon atmosphere. The
mixture was stirred for 10 min at the same temperature. Subsequently,
perfluorocyclopentene (0.88 ml, 6.5 mmol) was slowly added with a cooled
syringe, and stirring was continued for 30 min at À78 °C. Then the solution was
allowed to warm up to room temperature and consequently quenched with
aqueous HCl (50 ml, 0.1 M). The product was extracted with ether (3 Â 50 ml).
2 4
The combined organic layers were dried over Na SO , filtrated, and evaporated.
A white crystalline solid (1.7 g, 55%) was obtained after purification by column
chromatography on silica gel (petroleum ether) and recrystallization from the
same solvent. 1H NMR (400 MHz, CDCl ): d 1.88 (s, 6H), 6.89 (s, 2H) ppm; EI-
References and notes
3
+
MS: m/z 437 [M ].
1
.
Crano, J. C.; Guglielmetti, R. J. Organic Photochromic and Thermochromic
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.
2
6
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8
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.
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Myles, A. J.; Branda, N. R. Adv. Funct. Mater. 2002, 12, 167–173.
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43. Procedure
hexafluorocyclopentene (3a): Phenylboronic acid (0.307 g, 2.52 mmol),
3 4
(0.5 g, 1.14 mmol), Na CO (1.31 g, 4.58 mmol), and Pd(PPh )
for
the
synthesis
of
1,2-bis-[2-methyl-5-phenyl-3-thienyl]
2
2
3
 10
H
2
O
2
003, 4, 1124–1127.
(0.132 g, 0.11 mmol) were placed in a reaction flask under inert atmosphere.
DME (20 ml, degassed) and water (5 ml, degassed) were subsequently added,
and the solution was refluxed under argon. After 24 h, completeness of the
reaction was proved by TLC. Different photochromic molecules corresponding
to 0- (red), 1- (violet), or 2-times (deep blue) phenyl functionalized units are
clearly visible after irradiation with UV-light. If necessary further amounts of
9
.
Bianco, A.; Bertarelli, C.; Rabolt, J. F.; Zerbi, G. Chem. Mater. 2005, 17, 869–874.
1
1
1
1
0. Kang, J. W.; Kim, E.; Kim, J. J. Opt. Mater. 2003, 21, 543–548.
1. Fernandez-Acebes, A.; Lehn, J. M. Chem.-Eur. J. 1999, 5, 3285–3292.
2. Kawai, S. H.; Gilat, S. L.; Lehn, J. M. Eur. J. Org. Chem. 1999, 2359–2366.
3. Bertarelli, C.; Gallazzi, M. C.; Zerbi, G.; Molinari, E.; Bianco, A.; Giro, E. Mol.
Cryst. Liq. Cryst. 2005, 430, 187–192.
3 4
phenylboronic acid (31 mg, 0,25 mmol) and Pd(PPh ) (13 mg, 0,01 mmol)
1
4. Bianco, A.; Bertarelli, C.; Gallazzi, M. C.; Zerbi, G.; Giro, E.; Molinari, E. Astron.
Nachr. 2005, 326, 370–374.
5. Kasatani, K.; Kambe, S.; Irie, M. J. Photochem. Photobiol. A 1999, 122, 11–15.
6. Kawai, S. H.; Gilat, S. L.; Lehn, J. M. Chem. Commun. 1994, 1011–1013.
7. Kawai, S. H. Tetrahedron Lett. 1998, 39, 4445–4448.
were added to complete the reaction, and heating was continued for ca. 10 h.
Now the mixture was quenched with water (20 ml) and ether (50 ml). The
organic layer was separated, and the water phase was extracted further times
1
1
1
1
with ether (3 Â 50 ml). The combined organic phases were dried (Na
2 4
SO ),
filtered, and the solvent was evaporated in vacuo. A slightly blue solid (0.54 g,
91%) was obtained after purification by column chromatography on silica gel
8. Bertarelli, C.; Bianco, A.; D’Amore, F.; Gallazzi, M. C.; Zerbi, G. Adv. Funct. Mater.
(petroleum ether). 1H NMR (400 MHz, CDCl
2
004, 14, 357–363.
3
): d 1.97 (s, 6H), 7.29 (s, 2H), 7.33–
+
1
2
2
2
2
2
2
2
9. Browne, W. R.; De Jong, J. J. D.; Kudernac, T.; Walko, M.; Lucas, L. N.; Uchida, K.;
7.56 (m, 10H); ESI-MS: m/z 542.9 [M+Na] . Calcd for C27
H
18
F
6 2
S : C, 62.30; H,
Van Esch, J. H.; Feringa, B. L. Chem.-Eur. J. 2005, 11, 6430–6441.
3.49. Found: C, 62.48; H, 3.72.
0. Browne, W. R.; De Jong, J. J. D.; Kudernac, T.; Walko, M.; Lucas, L. N.; Uchida, K.;
Van Esch, J. H.; Feringa, B. L. Chem.-Eur. J. 2005, 11, 6414–6429.
1. Giordano, L.; Jovin, T. M.; Irie, M.; Jares-Erijman, E. A. JACS 2002, 124, 7481–
44. Procedure for the synthesis of 1,2-bis-[2-methyl-5-(p-hydroxyphenyl)-3-
thienyl]hexafluorocyclopentene (3b): Following the procedure as described for
3a, the title compound was prepared from
hydroxyphenylboronic acid pinacol ester (0.554 g, 2.52 mmol). After
purification by column chromatography on silica gel (diethyl ether),
2 (0.5 g, 1.14 mmol) and 4-
7
489.
2. Fulwyler, M.; Hanley, Q. S.; Schnetter, C.; Young, I. T.; Jares-Erijman, E. A.;
Arndt-Jovin, D.; Jovin, T. M. Cytom. Part A 2005, 67A, 68–75.
3. Kudernac, T.; Van Der Molen, S. J.; Van Wees, B. J.; Feringa, B. L. Chem. Commun.
a
1
slightly blue solid is obtained (0.54 g, 85%). H NMR (400 MHz, CDCl
3
): d
1.94 (s, 6H), 6.86 (d, J = 8,7 Hz, 4H), 7.15 (s, 2H), 7.42 (d, J = 8,7 Hz, 4H); ESI-MS:
+
2
006, 3597–3599.
18 6 2 2
m/z 570.9 [M+Na] . Calcd for C27H F O S : C, 58.69; H, 3.28. Found: C, 58.49;
4. Kudernac, T.; De Jong, J. J.; Van Esch, J.; Feringa, B. L.; Dulic, D.; Van Der Molen,
S. J.; Van Wees, B. J. Mol. Cryst. Liq. Cryst. 2005, 430, 205–210.
5. Katsonis, N.; Kudernac, T.; Walko, M.; Van Der Molen, S. J.; Van Wees, B. J.;
Feringa, B. L. Adv. Mater. 2006, 18, 1397–1400.
6. Dulic, D.; Van Der Molen, S. J.; Kudernac, T.; Jonkman, H. T.; De Jong, J. J. D.;
Bowden, T. N.; Van Esch, J.; Feringa, B. L.; Van Wees, B. J. Phys. Rev. Lett. 2003,
H, 3.49.
45. Procedure for the synthesis of 1,2-bis-[2-methyl-5-(p-(hydroxymethyl)phenyl)-3-
thienyl]hexafluorocyclopentene (3c): Following the procedure as described for
3a, the title compound was prepared from
2 (0.5 g, 1.14 mmol) and 4-
(hydroxymethyl)phenylboronic acid (0.383, 2.52 mmol). After purification by
column chromatography on silica gel (diethyl ether), a slightly blue solid is
obtained (0.57 g, 86%). 1H NMR (400 MHz, CDCl
): d 1.97 (s, 6H), 4.71 (s, 4H),
7.28 (s, 2H), 7.38 (d, J = 8.2 Hz, 4H), 7.54 (d, J = 8.2 Hz, 4H); ESI-MS m/z 603.0
91.
3
2
2
7. Zayat, M.; Pardo, R.; Levy, D. J. Mater. Chem. 2003, 13, 2899–2903.
8. Chaput, F.; Biteau, J.; Lahlil, K.; Boilot, J. P.; Darracq, B.; Levy, Y.; Peretti, J.;
Safarov, V. I.; Parent, G.; Fernandez-Acebes, A.; Lehn, J. M. Mol. Cryst. Liq. Cryst.
Part A 2000, 344, 77–82.
9. Biteau, J.; Tsivgoulis, G. M.; Chaput, F.; Boilot, J. P.; Gilat, S.; Kawai, S.; Lehn,
J. M.; Darracq, B.; Martin, F.; Levy, Y. Mol. Cryst. Liq. Cryst. Part A 1997, 297,
+
22 6 2 2
[M+Na] . Calcd for C29H F O S : C, 59.99; H, 3.82. Found: C, 61.11; H, 3.91.
46. Procedure for the synthesis of 1,2-Bis-[2-methyl-5-(p-carboxyphenyl)-3-
thienyl]hexafluorocyclopentene (3d):Following the procedure as described for
3a, the title compound was prepared from 2 (0.5 g, 1.14 mmol) and 4-
Carboxyphenylboronic acid (0.418, 2.52 mmol). In contrast to 3a the reaction
mixture had to be quenched with aqueous HCl to protonate the product. After
purification by column chromatography on silica gel (diethyl ether) a slightly
blue solid is obtained (0.65 g, 94%). 1H NMR (400 MHz, acetone-d6): d 2.10 (s,
2
6
5–72.
3
3
0. Yamamoto, S.; Matsuda, K.; Irie, M. Chem.-Eur. J. 2003, 9, 4878–4886.
1. Irie, M.; Lifka, T.; Uchida, K. Mol. Cryst. Liq. Cryst. Part A 1997, 297–298, 81–
8
4.
6H), 7.70 (s, 2H), 7.81 (d, J = 8.5 Hz, 4H), 8.08 (d, J = 8.5 Hz, 4H); ESI-MS: m/z
À
3
3
2. Yamamoto, S.; Matsuda, K.; Irie, M. Org. Lett. 2003, 5, 1769–1772.
3. All operations were carried out under a dry, oxygen-free argon atmosphere.
Reagent-grade solvents were distilled from potassium under argon. Unless
606.9 [M-H] . Calcd for C29
18 6 4 2
H F O S : C, 57.24; H, 2.98; found: C, 57.60; H,
3.19.
47. Procedure for the synthesis of 1,2-bis-[2-methyl-5-(p-aminophenyl)-3-
thienyl]hexafluorocyclopentene (3e): Following the procedure as described for
otherwise specified, all reagents and catalysts were commercial (Aldrich, Alfa
1
Aesar). H NMR spectra were recorded of a solution in CDCl
3
or acetone-d
6
on a
3a, the title compound was prepared from 2 (0.5 g, 1.14 mmol) and 4-
Bruker AXR 400 spectrometer at 400 MHZ. Molecular weights were
determined by a Bruker Esquire 3000 Plus ESI-MS. Elemental analysis was
recorded by PerkinElmer 2400 Series II CHNS/O System.
aminophenylboronic acid pinacol ester (0.552, 2.52 mmol). After purification
by column chromatography on silica gel (diethyl ether), a green-blue solid is
obtained (0.53 g, 84%). 1H NMR (400 MHz, CDCl
): d 1.95 (s, 6H), 3.76 (s, 4H),
6.67 (d, J = 8.5 Hz, 4H), 7.10 (s, 2H), 7.34 (d, J = 8.5 Hz, 4H); ESI-MS: m/z 551.0
3
3
4. Procedure for the synthesis of 3-bromo-5-chloro-2-methylthiophene (1):20
A
+
solution of bromine (3.89 ml, 75.4 mmol) in CHCl
3
(20 ml) was added slowly to
[M+H] . Calcd for C27
3.81; N, 5.30.
20 6 2 2
H F N S : C, 58.90; H, 3.66; N, 5.09. Found: C, 58.79; H,
an ice-cooled solution of 4-Chloro-2-methylthiophene (10.0 g, 75.4 mmol) in