W.-L. Chia et al. / Tetrahedron Letters 42 (2001) 2177–2179
2179
2-(4-n-butylphenyl)-5-phenylpyridine (4e) and 2-(4-n-
pentylphenyl)-5-phenylpyridine (4g) was done by using
a polarized optical microscope, which further confirmed
the phase transitions of these two compounds. Both 4e
and 4g in the mesophases showed mosaic textures dur-
ing their second heating cycles, which complimented the
results found by dsc that highly ordered mesophases
(presumably smectic) occur in these mesophases. The
immobility of those colorful domains in mosaic textures
(Fig. 1) provides additional evidence of the presence of
highly crystalline mesophases. However, the exact iden-
tification of the mesophases of these two compounds
needs to be further characterized by X-ray diffraction
methods.
another 8 h. After evaporating the THF, the residue was
extracted with ether. The organic layer was further
washed twice with 10% HCl solution and brine and dried
with magnesium sulfate. Yields of the intermediates were
found to be 70–90%. For 4a: To a solution of 20 ml dry
toluene and crude 3a was added about 1.5 equiv. o-chlor-
anil. The reaction mixture was heated to reflux for a
number of hours under inert atmosphere and then
quenched by adding 25 ml 1N NaOH solution and 25 ml
ethyl ether and filtered through Celite. Normal aqueous
work up and isolation with column chromatography
affords the products 4a (71%). These crude products were
further purified by either recrystallization from hexane or
by vacuum distillation.
10. 1H NMR (400 MHz, CDCl3). 4a: 8.66 (d, 1H, J=4.7
Hz), 7.89 (d, 2H, J=8.3 Hz), 7.72–7.67 (m, 2H), 7.27 (d,
2H, J=8.3 Hz), 7.19–7.15 (m, 1H), 2.65 (t, 2H, J=7.6
Hz), 1.66–1.59 (m, 2H), 1.41–1.33 (m, 2H), 0.92 (t, 3H,
J=7.3 Hz); 4b: 8.52 (dd, 1H, J1=1.4 Hz, J2=0.6 Hz),
7.89 (d, 2H, J=8.3 Hz), 7.6 (d, 1H, J=8.1 Hz), 7.53 (dd,
1H, J1=8.0 Hz, J2=0.5 Hz), 7.28 (d, 2H, J=8.3 Hz),
2.67 (t, 2H, J=7.6 Hz), 2.35 (s, 3H), 1.68–1.61 (m, 2H),
1.44–1.34 (m, 2H), 0.95 (t, 3H, J=7.3 Hz); 4c: 8.55 (d,
1H, J=1.6 Hz), 7.9 (d, 2H, J=8.2 Hz), 7.67 (d, 1H,
J=8.1 Hz), 7.63 (d, 1H, J=8.2 Hz), 7.29 (d, 2H, J=8.2
Hz), 2.73–2.65 (m, 4H), 1.68–1.60 (m, 2H), 1.43–1.34 (m,
2H), 1.29 (t, 3H, J=7.6 Hz), 0.948 (t, 3H, J=7.3 Hz); 4d:
8.51 (d, 1H, J=1.9 Hz), 7.89 (d, 2H, J=8.3 Hz), 7.63 (d,
1H, J=8.1 Hz), 7.55 (dd, 1H, J1=8.1 Hz, J2=2.3 Hz),
7.28 (d, 2H, J=8.3 Hz), 2.68–2.63 (m, 4H), 1.68–1.60 (m,
4H), 1.42–1.35 (m, 4H), 0.97–0.93 (m, 6H); 4e: 8.91 (dd,
1H, J1=2.4 Hz, J2=0.7 Hz), 7.95 (d, 2H, J=8.3 Hz),
7.92 (dd, 1H, J1=8.2 Hz, J2=2.4 Hz), 7.77 (dd, 1H,
J1=8.2 Hz, J2=0.8 Hz), 7.63 (dt, 2H, J1=6.8 Hz, J2=
1.4 Hz), 7.48 (td, 2H, J1=7.0 Hz, J2=1.5 Hz), 7.4 (t, 1H,
J=5.31 Hz), 7.30 (d, 2H, J=8.4 Hz), 2.67 (t, 2H, J=7.6
Hz), 1.7–1.61 (m, 2H), 1.41–1.36 (m, 2H), 0.94 (t, 3H,
J=7.3 Hz); 4f: 8.69 (d, 1H, J=4.9 Hz), 7.93 (d, 2H,
J=8.1 Hz), 7.71 (d, 2H, J=3.5 Hz), 7.31 (d, 2H, J=8.1
Hz), 7.19 (dd, 1H, J1=8.4 Hz, J2=4.7 Hz), 2.67 (t, 2H,
J=7.6 Hz), 1.71–1.64 (m, 2H), 1.4–1.33 (m, 4H), 0.92 (t,
3H, J=6.9 Hz); 4g: 8.91 (dd, 1H, J1=2.4 Hz, J2=0.7
Hz), 7.95 (d, 2H, J=8.3 Hz), 7.90 (dd, 1H, J1=8.3 Hz,
J2=2.4 Hz), 7.76 (dd, 1H, J1=10.9 Hz, J2=0.8 Hz), 7.61
(dt, 2H, J1=8.3 Hz, J2=1.4 Hz), 7.47 (td, 2H, J1=7.0
Hz, J2=1.4 Hz), 7.38 (t, 1H, J=7.4 Hz), 7.29 (d, 2H,
J=8.3 Hz), 2.69 (t, 2H, J=7.9 Hz), 1.73–1.65 (m, 2H),
1.41–1.34 (m, 4H), 0.93 (t, 3H, J=6.9 Hz). All com-
pounds gave satisfactory data by 13C NMR (75 MHz,
CDCl3) and IR spectrum.
Acknowledgements
The authors gratefully acknowledge the financial sup-
port of the cross cultural center of Fu Jen Catholic
University. Grant 0167-1999-1.0-0105.
References
1. (a) Comins, D. L.; Abdullah, A. H. J. Org. Chem. 1982,
47, 4315; (b) Kartritzky, A. R.; Ibrahim, M. H.; Valnot,
J.-Y.; Sammes, M. P. J. Chem. Res. 1981, 70; (c) Akiba,
K.; Iseki, Y.; Wada, M. Tetrahedron Lett. 1982, 23, 429.
2. Yamaguchi, R.; Nakanozo, Y.; Matuki, T.; Hata, E.;
Kawanishi, M. Bull. Chem. Soc. Jpn. 1987, 60, 215.
3. (a) Chia, W.-L.; Shiao, M.-J. Tetrahedron Lett. 1991, 32,
2033; (b) Shing, T.-L.; Chia, W.-L.; Shiao, M.-J.; Chau,
T.-Y. Synthesis 1991, 849; (c) Shiao, M.-J.; Chia, W.-L.;
Peng, C.-L.; Shen, C.-C. J. Org. Chem. 1993, 58, 3162.
4. (a) Bahadur, B. Liquid Crystals; World Scientific Publish-
ing Co. Pte. Ltd, 1990; Vols. 1–3; (b) Scheuble, B. S.
Kontakte (Darmstadt) 1989, 34; (c) Schadt, M. Display
1992, 13, 11.
5. Nash, J. A.; Gray, G. W. Mol. Cryst. Liq. Cryst. 1974,
25, 299.
6. Pavelyuchenko, A. I.; Smirnova, N. I.; Mikhailova, T.
A.; Kovshev, E. I.; Titov, V. V. Zh. Org. Khim. 1986, 22,
1061.
7. Burrow, M. P.; Gray, G. W.; Lacey, D.; Toyne, K. J. Liq.
Cryst. 1988, 3, 1643.
8. Reiffenrath, V.; Bremer, M. Angew. Chem., Int. Ed. Engl.
1994, 33, 1386.
9. Representative experimental procedure for 3a: To a
(Grignard) solution of 1-bromo-4-butylbenzene (10
mmol) in 20 ml THF was added freshly dried magnesium
granules (11 mmol) under an inert atmosphere. The
Grignard solution 1 was then slowly added by syringe
into a preformed solution of pyridinium chloride 2 (10
mmol ethyl chloroformate, 10 mmol pyridine, 20 ml dry
THF at −20°C, 0.5 h) at −20°C. The resulting solution
was warmed slowly to room temperature and stirred for
11. Gray, G. W.; Hird, M.; Lacey, D.; Toyne, K. J. J. Chem.
Soc., Perkin Trans. 2 1989, 2041.
12. The magnitudes of enthalpy changes between crystal-to-
mesophase and mesophase-to-isotropic phase for 2-(4-n-
butylphenyl)-5-phenylpyridine (4e) were 8.04 and 26.22
J/g, respectively, and those for 2-(4-n-pentylphenyl)-5-
phenylpyridine (4g) were 7.20 and 22.67 J/g, respectively.
.