Dehydroabietic acid esters as chiral dopants for nematic liquid crystals

Article abstract of DOI:10.1246/bcsj.80.589

Dehydroabietic acid esters were prepared as new chiral dopants for the nematic liquid crystals. The magnitude of the helical twisting power (HTP) was good due to simple but rigid three-ring structure and two axial methyl groups. The relationship between t

Full text of DOI:10.1246/bcsj.80.589

ꢀ 2007 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 80, No. 3, 589–593 (2007)
589
Dehydroabietic Acid Esters as Chiral Dopants
for Nematic Liquid Crystals
Hiroaki Shitara, Marie Aruga, Emi Odagiri, Kayoko Taniguchi,
ꢀ
Mikio Yasutake, and Takuji Hirose
Department of Applied Chemistry, Faculty of Engineering, Saitama University,
Shimo-ohkubo 255, Sakura-ku, Saitama 338-8570
Received March 1, 2006; E-mail: hirose@apc.saitama-u.ac.jp
Dehydroabietic acid esters were prepared as new chiral dopants for the nematic liquid crystals. The magnitude of
the helical twisting power (HTP) was good due to simple but rigid three-ring structure and two axial methyl groups. The
relationship between the HTP or MHTP (molar helical twisting power) values and the terminal structures was studied.
Considering the synthetic accessibility and their miscibility with liquid crystals, the acid was shown to be a good can-
didate as the scaffold of chiral dopants for the nematic liquid crystals.
Currently, not only lap-top computers but also more and
more desk-top computers have a liquid-crystalline display
(LCD), which is one of the most important applications of liq-
uid crystals (LCs).1 The LCs used in the displays are mostly in
a nematic phase having chirality, which is therefore called a
and they must be economical for industrialize. Recently, we
have investigated the HTP of chiral chroman derivatives,
which are easily synthesized and resolved.7 The chroman de-
rivatives have a rigid two-ring structure bearing a quaternary
asymmetric center and flexible terminal groups and, as a result,
two flexible but short side chains were found to be effective to
obtain 11.2 mmꢁ1 for ethyl 6-benzyloxy-2-methylchromane-2-
carboxylate.7
ꢀ
‘‘chiral nematic phase’’ (N ). The chiral nematic phase is con-
trolled by an electrical field, and interaction with polarized
light is the basic principle of the widely used LCD. Chiral
nematic phases can be prepared from optically active liquid-
crystalline molecules, like cholesteryl benzoate, which is the
first liquid crystal prepared by Reinitzer,2 or from non-chiral
nematic phases doped with an optically active molecule as a
chiral dopant, such as cholesteryl nonanoate (CN).1a Today,
all commercial LCDs are composed in the latter style.
In the framework of our chiral recognition work, dehydro-
ꢀ
abietic acid (DAA) (1 ) has been shown to be an effective re-
solving agent for some 2-aminoalcohols.8 Dehydroabietic acid
is an interesting natural compound as it is readily available and
has three asymmetric carbons. Structurally, DAA has a re-
stricted three-ring structure and a carboxyl group is directly at-
tached to a quaternary asymmetric carbon in a cyclohexyl ring.
We expected certain DAA derivatives can be chiral LCs and/
or good chiral dopants for calamitic LC molecules, like choles-
terol derivatives.
The strength of chiral induction by a dopant, i.e., the helical
twisting power (HTP), can be estimated by using Eq. 1,3
HTP ¼ ðpcÞꢁ1
ð1Þ
ꢀ
ꢀ
where p is the pitch of the chiral nematic phase in mm and c is
the mass fraction of the dopant. In order to discuss the effect of
molecular characteristics on HTP, we have introduced the idea
of molar helical twisting power (MHTP) defined by Eq. 2.4
In this paper, we report new chiral dopants (2 –8 ),
Chart 1, derived from DAA, and discuss the relation between
the HTP or MHTP and the molecular structures of the dopants.
Results and Discussion
MHTP ¼ HTP Mw=1000 ðmmꢁ1 molꢁ1 kgÞ
ð2Þ
ꢂ
Structures of DAA and Its Ester. The crystal structure of
DAA was obtained by X-ray single-crystal diffraction analysis
and the crystal data are summarized in Table 1. As shown in
A high HTP value allows for thin LCDs or a low content of the
dopant, and the value depends on the molecular structures of
both the chiral dopant as well as the host nematic LC. HTP
depends on the structure of the chiral dopant as a guest in a
certain host nematic LC. Therefore, new chiral dopants with
larger values of HTP are still required for new LCs and for
further improvement of the LCD performance. However, the
relation between the HTP and the molecular structures is not
well established.5,6
2* - 5* : W = none, n = 1, 6, 8, 10.
6* : W =
7* : W =
8* : W =
, n = 0.
, n = 6.
, n = 6.
O
Chiral dopants are often designed to have similar structures
to the host LCs, which usually have rigid ‘‘cores’’ and long
flexible chains. At the same time, however, they need to be
compact so as not to increase the viscosity of the LC phases,
CO2-W-CnH2n+1
O
Chart 1. Chiral dopants used in this study.
Published on the web March 13, 2007; doi:10.1246/bcsj.80.589

590 Bull. Chem. Soc. Jpn. Vol. 80, No. 3 (2007)
Dehydroabietic Acid Esters as Chiral Dopants
Table 1. Crystallographic Data for Dehydroabietic Acid
Empirical formula
Formula weight
T/K
Crystal dimensions/mm3
Crystal color, shape
Crystal system
Space group
C40H56O4
600.85
a, b
123(2)
0:45 ꢃ 0:45 ꢃ 0:12
75%
COOH
COOCH3
colorless, prism
Monoclinic
1*
2*
P21
11.538(2)
11.713(2)
13.675(3)
108.29
1754.8(6)
˚
a) H2SO4.
b) CH3OH, 24 h.
a/A
˚
b/A
˚
ꢀ
c/A
Scheme 1. Synthesis of methyl dehydroabietate (2 ).
ꢀ/ꢄ
˚
V/A
3
Z
2
1.137
Dcalcd/Mg mꢁ3
ꢁ(Mo Kꢂ)/mmꢁ1
Reflections collected
Independent reflections
Final R indices [I > 2ꢃðIÞ]
R indices (all data)
GOF
0.071
12347
a, b
32 - 45%
COOH
COOR
7209 [R(int) = 0.0188]
R1 ¼ 0:0572, wR2 ¼ 0:1574
R1 ¼ 0:0616, wR2 ¼ 0:1635
1.262
1*
3*- 8*
a) SOCl2.
b) ROH, 48 h,( R = CnH2n+1 (n = 6,8,10), Ph,
OC6H13
OC6H13
).
,
ꢀ
ꢀ
Scheme 2. Synthesis of dehydroabietic acid esters (3 –8 ).
Table 2. HTPaÞ and MHTPaÞ of DAA Esters
COO W CnH2n+1
HTPbÞ
MHTPbÞ
Compound
W
n
/mmꢁ1 /mmꢁ1 molꢁ1 kg
ꢀ
ꢀ
ꢀ
ꢀ
2
3
4
5
—
—
—
—
1
6
8
ꢁ11:5
ꢁ7:35
ꢁ7:00
ꢁ6:53
ꢁ3:61
ꢁ2:83
ꢁ2:79
ꢁ2:69
(a)
(b)
10
ꢀ
ꢀ
ꢀ
2.89cÞ
ꢁ8:23
ꢁ9:00
1.09cÞ
ꢁ3:92
ꢁ4:84
Fig. 1. Crystal structure of dehydroabietic acid.
6
7
8
—
6
O
Fig. 1, the structure is rather planar, and the carboxyl group is
in an equatorial position, while two methyl groups on the
asymmetric carbons are in a 1,3-diaxial arrangement (Fig. 1b).
These features distinguish the two sides of DAA, and basical-
ly, it has the same structure as that of the methyl ester,9 except
for the conformation of the ester and the carboxylic acid parts.
Both AM1 and PM3 calculation using MOPAC10 on the most
stable conformations of methyl, phenyl, and hexyloxyphenyl
esters gave the same structures as that shown in Fig. 1, even
though DAA forms a dimeric structure due to hydrogen bond-
ing between carboxyl groups.
6
O
a) Host liquid crystal (ZLI-1132):dopant = 99:1 (by weight).
b) The minus sign shows a left-handed helical sense of the
nematic phase. c) The handedness was not measurable due
to small HTP.
derivatives showed liquid crystallinity, and they were liquid at
room temperature except for 2 , which was obtained as solid.
All of the esters were miscible with the host LC (ZLI-1132)
and were a good dopants because they did not cause phase sep-
aration in or raise viscosity of the LC phase.
Relationship between Structure and Helical Twisting
Power of Dehydroabietic Acid Derivatives. The HTP of
each chiral dopant was measured as a 1 wt % mixture with
the host LC,11 and the results calculated using Eq. 1 are sum-
marized in Table 2 together with the MHTP. Most of them in-
duced a left-handed helicity in CN. The HTP of commercially
ꢀ
Synthesis of Chiral Dopants. In order to study the effect
of a side chain, the length of an alkyl group was changed from
ꢀ
was also investigated using 6 –8 .
ꢀ
C1 (2 ) to C10 (5 ), and the effect of an aromatic structure
ꢀ
Dopant 2 , was derived from (+)-DAA (1 ) by direct ester-
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ification with methanol (Scheme 1), and 3 –8 were obtained
by the reaction of the acid chloride with the corresponding pri-
mary alcohols or phenols (Scheme 2). Unexpectedly, no ester

H. Shitara et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 3 (2007)
591
14
12
10
8
5.42°
O
Me
C
MeO
H2C
CH2
6
AM1 calc. : -115 kcal /mol
4
2
0
0
Me
OMe
2
4
6
8
10
Alkyl chain length ( CnH2n+1 ) [ n ]
Fig. 2. Alkyl chain length of dehydroabietic acid alkyl
12
136°
C
C
H2C
CH2
O
ꢀ
ꢀ
esters (2 –5 ) and HTP correlation.
AM1 calc. : -115 kcal /mol
available CN is known to be 4.4 mmꢁ1, which is the same as
ꢀ
ꢀ
the host LC.1a Comparing the HTP data of 2 –5 , the ring
structure of DAA should have a good chiral-induction ability,
(a) Simulated stable conformations of 2*
e.g., 11.5 mmꢁ1 for 2 , comparable to the chroman deriva-
ꢀ
tives.7 However, the HTP values gradually decreased as the al-
1.98°
kyl chain length increased: 3 (n ¼ 6), 7.35 mmꢁ1; 4 (n ¼ 8),
ꢀ
ꢀ
Me
O
7.00 mmꢁ1; and 5 (n ¼ 10), 6.53 mmꢁ1 (n in Table 2). Thus,
ꢀ
C
as shown in Fig. 2, the alkyl chain length of the ester group
has a weak negative effect on the HTP. It is in contrast to
the relationship reported by Emoto et al. for chiral 40-(2-alka-
noyloxypropoxy)biphenyl derivatives.12 They use chiral alco-
hols as the terminal moiety, while the present system has an
asymmetric center in the acid moiety in a ring structure and
the terminal alcohol units are achiral. The positional difference
of the chiral center is the major reason for the opposite effect
of the alkyl chain length.
H C
2
CH
2
PhO
AM1 calc. : -74.8 kcal /mol
Me
OPh
160°
C
On the other hand, introduction of rigid phenyl group with-
out an alkyl chain largely decreased the HTP for 6 . Although
H C
CH
2
2
ꢀ
O
the carboxyl group is equatorial to the ring structure (Fig. 1),
the additional bulky phenyl group might reduce the planarity
and lessen the affinity or interaction with the host LC mole-
cules. However, introduction of flexible n-hexyloxy group in-
AM1 calc. : -74.7 kcal /mol
(b) Simulated stable conformations of 6*
ꢀ
creased the HTP for 7 (8.23 mmꢁ1), and a slight increase in
ꢀ
HTP (9.0 mmꢁ1) for 8 having a biphenyl group was observed.
In fact, their MHTP became higher than that of 2 . The com-
Fig. 3. Simulated structures of 2 (a) and 6 (b) based on
ꢀ
AM1 calculation. Quite similar results were obtained by
ꢀ
ꢀ
ꢀ
ꢀ
PM3 calculation and also for 3 and 7 .
bination of aromatic and aliphatic structures in an alcohol
moiety seems promising for further improvement.
Correlations between the molecular structure of a dopant
and helicity of induced chiral LC have been investigated and
discussed for many systems.13,14 Ferrarni, Spada, et al. have
presented a model that includes a shape term and a reaction
field term to explain the chiral induction and the HTP by chiral
biphenyls in nematic LCs.14d The first term is related to the
molecular shape, and the second term is related to atomic
properties, chemical structures, and flexibility of functional
groups or substituents. Recently, it has been reported that the
dopant shape, not its chirality, causes the switch in handedness
of nematic LCs.13c,14d Considering the present dopants, how-
ever, all DAA derivatives are structurally close each other,
and the HTP sign does not change. In fact, the stable confor-
mation, simulated with MM215 and MOPAC 2002,10 gave sim-
difference was found in the dihedral angle for (H3)C–C–
C=O, that is the direction of a carbonyl dipole, between alkyl
ꢀ
ꢀ
ꢀ
ꢀ
esters, 2 and 3 , and phenyl esters, 6 and 7 . Although the
simulated structures may not be the real ones in the nematic
LC, it should be the factor of a reaction field model. Further
studies are in progress in order to accumulate additional data
on electrostatic interactions caused by functional groups and
substituents.
In conclusion, it was shown that optically active dehydro-
abietic acid esters are good chiral dopants with high miscibility
to the host LC. By arranging a short alkyl ester group, such
as methyl ester, high HTP was induced (HTP ¼ 11:5 mmꢁ1
,
MHTP ¼ 3:61 mmꢁ1 molꢁ1 kg) probably because the structure
has an appropriate balance of rigidity and bulkiness between
the dehydroabietic acid and alcohol moieties. The aromatic
core having an alkoxy group at the para position effectively
ꢀ
ꢀ
ꢀ
ꢀ
ilar structures for 2 , 3 , 6 , and 7 . As shown in Fig. 3 for
ꢀ
ꢀ
2
and 6 , in spite of apparently similar structures, a major

592 Bull. Chem. Soc. Jpn. Vol. 80, No. 3 (2007)
Dehydroabietic Acid Esters as Chiral Dopants
ꢁ1
ꢅ
ꢅ
¼
the product as a white solid (99.0 mg, 0.315 mmol, 75.7%): mp
34
to induced helical structure (HTP 9 mm , MHTP 4{5
¼
62–62.8 ꢄC, ½ꢂꢆD þ54:4ꢄ (c 1.0, MeOH) (lit.: mp 63–64.5 ꢄC,
mmꢁ1 molꢁ1 kg). Although the relation between the ester struc-
ture and HTP seems complex, it is similar to that of the chro-
man derivatives, which also contain a carboxyl group on a qua-
ternary asymmetric carbon.7
20
½ꢂꢆD þ61ꢄ);19 1H NMR (200 MHz, CDCl3) ꢆ 7.16 (d, J ¼ 8:30
Hz, 1H), 6.99 (d, J ¼ 8:30 Hz, 1H), 6.88 (s, 1H), 3.66 (s, 3H),
2.97–2.70 (m, 3H), 2.43–2.11 (m, 2H), 1.97–1.35 (m, 10H), 1.27
(s, 3H), 1.22 (d, J ¼ 6:84 Hz, 6H); 13C NMR (100 MHz, CDCl3) ꢆ
16.48, 18.56, 21.69, 23.96 (2C), 25.08, 29.98, 33.45, 36.63, 36.93,
37.98, 44.84, 47.65, 51.87, 123.88, 124.11, 126.86, 134.68,
145.70, 146.91, 179.12; IR (KBr) 2930, 1718, 1496, 1251, 1176,
Experimental
Infrared spectra were recorded on a JASCO FT/IR 400 spec-
trometer. Melting temperatures were determined on Mel-Temp
melting point apparatus (Laboratory Devices, MA) and were re-
ported uncorrected. The measurement of 1H NMR spectra was
performed on Bruker AC300P and AC200, DPX400 spectrome-
ters, and EI-MS spectra were recorded on a JEOL DX303 spec-
trometer (Molecular Analysis and Life Science (MALS) Center,
Saitama University). Specific rotations were measured with a
JASCO DIP-370 polarimeter. The computations were performed
with MM2 (CAChe ver. 7.5)15 and MOPAC 2002 (AM1 &
PM3, CAChe ver. 7.5).10
822 cmꢁ1
.
ꢀ
Synthesis of Hexyl Dehydroabietate (3 ). General proce-
dure: A 30-mL, two-necked, round-bottom flask, equipped with
a magnetic stirring bar and a reflux condenser protected from
moisture by a CaCl2 drying tube, was charged with dehydroabietic
ꢀ
acid 1 (217 mg, 0.723 mmol). Thionyl chloride (2 mL) was added
in one portion, and the reaction mixture was heated at reflux for
3 h. Excess thionyl chloride was removed under reduced pressure.
The flask was flushed with nitrogen, and dry tetrahydrofuran
(THF, 2 mL), dry pyridine (500 mL), and then 1-hexanol (80.5 mg,
0.780 mmol) were added. After stirring at rt for 48 h, the salt was
removed by filtration, and the filtrate was concentrated under
reduced pressure to dryness. The residue was dissolved in ether,
and the solution was poured into a separatory funnel and washed
with water (15 mL ꢃ 2). The organic layer was dried over anhyd.
NaSO4. The solution was concentrated under reduced pressure to
dryness, and the residue was purified by chromatography (silica
gel, hexane:ethyl acetate = 4:1). The eluent was removed to ob-
ꢀ
Dehydroabietic Acid (DAA) (1 ). Dehydroabietic acid was
kindly supplied by Arakawa Chemical Industries Ltd. and purified
to >99% purity according to the literature:16 mp 170–171.5 ꢄC,
30
20
½ꢂꢆD þ61:8ꢄ (c 1.0, MeOH) (lit.: mp 170–171.5 ꢄC, ½ꢂꢆD þ62:5ꢄ,
c 2.0, 95% EtOH).7,12
Measurement of HTP and Handedness of the Induced
Chirality. The LC sample was prepared by adding 1 wt % of a
chiral dopant into the achiral host LC mixture ZLI-1132 (Merck).
The helical pitch of the chiral nematic phases were measured us-
ing wedge-shaped samples, contained between a convex lens and
a plane glass plate (Cano-wedge cell, tan ꢄ ¼ 0:0083, 0.0140,
0.0194, 0.0288, E. H. C. Ind., Ltd.,) by means of the resulting
Cano lines.11 All solvents were used as received except for dry
tetrahydrofuran and dry pyridine used in the synthesis of most
of the DAA esters.
The handedness of an induced helix was determined by the
contact method with the mixture of the achiral host LC and CN
(2 wt %), which is known to cause left handedness.1a
Crystal Structure Analysis of DAA (1 ). Data collection
was performed on a Bruker SMART CCD system (MALS Center)
1
tain a colorless oil (103 mg, 0.268 mmol, 34.4%). H NMR (300
MHz, CDCl3) ꢆ 7.17 (d, J ¼ 8:27 Hz, 1H), 7.00 (d, J ¼ 8:27 Hz,
1H), 6.88 (s, 1H), 4.01–3.99 (m, 2H), 2.95–2.70 (m, 3H), 2.42–
2.15 (m, 2H), 1.94–1.10 (m, 27H), 0.877 (t, J ¼ 6:80 Hz, 3H);
13C NMR (100 MHz, CDCl3) ꢆ 14.08, 16.33, 18.15, 22.96, 23.64,
23.95 (2C), 25.97, 26.09, 28.91, 30.35, 31.56, 33.58, 36.51, 37.05,
37.79, 43.69, 46.51, 60.89, 123.49, 125.04, 128.78, 132.56,
146.91, 153.05, 177.29; IR (neat) 2932, 1724, 1497, 1460, 1244,
32
1173, 822 cmꢁ1; ½ꢂꢆD þ26:9ꢄ (c 1.0, MeOH).
ꢀ
ꢀ
scribed in the general procedure, 4 (114 mg, 0.277 mmol) was
Synthesis of Octyl Dehydroabietate (4 ). Prepared as de-
ꢀ
obtained as colorless oil in 34.4% yield from 1 (241 mg, 0.803
ꢀ
mmol) and 1-octanol (105 mg, 0.808 mmol). H NMR (300 MHz,
with graphite monochromated Mo Kꢂ radiation (ꢅ ¼ 0:71069
1
˚
A) at 123 K. The linear absorption coefficient, (ꢁ), for Mo Kꢂ
was 0.071 mmꢁ1. The crystal structure was solved by a direct
method with SIR9717 and refined by full-matrix least-squares us-
ing SHLEXL9718 to a final reliability value of 0.0572. The non-hy-
drogen atoms were refined anisotropically while the hydrogen
atoms were located at geometrically calculated positions.
CDCl3) ꢆ 7.17 (d, J ¼ 8:07 Hz, 1H), 7.00 (d, J ¼ 8:07 Hz, 1H),
6.89 (s, 1H), 4.20–3.95 (m, 2H), 3.00–2.78 (m, 3H), 2.40–2.20
(m, 2H), 1.94–1.10 (m, 31H), 0.878 (t, J ¼ 6:60 Hz, 3H); IR (neat)
32
2925, 1723, 1497, 1467, 1245, 1174, 822 cmꢁ1; ½ꢂꢆD þ35:8ꢄ (c
1.0, EtOH). Found: C, 81.34; H, 11.03%. Calcd for C28H44O2:
C, 81.49; H, 10.74%.
Crystallographic data for DAA have been deposited with
Cambridge Crystallographic Data Centre: Deposition number
CCDC-299433 for DAA. Copies of the data can be obtained free
of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html
(or from the CCDC, 12, Union Road, Cambridge, CB2 1EZ,
UK; Fax: +44 1223 36033; e-mail: deposit@ccdc.cam.ac.uk).
ꢀ
general procedure, 5 (162 mg, 0.368 mmol) was obtained as col-
Synthesis of Decyl Dehydroabietate (5 ). Following the
ꢀ
ꢀ
orless oil in 32.7% yield from 1 (338 mg, 1.13 mmol) and 1-dec-
anol (179 mg, 1.13 mmol). 1H NMR (300 MHz, CDCl3) ꢆ 7.17 (d,
J ¼ 8:09 Hz, 1H), 7.00 (d, J ¼ 8:09 Hz, 1H), 6.88 (s, 1H), 4.20–
3.95 (m, 2H), 2.92–2.70 (m, 3H), 2.39–2.20 (m, 2H), 1.82–1.69
(m, 6H), 1.65–1.55 (m, 1H), 1.40–1.15 (m, 28H), 0.878 (t, J ¼
6:62 Hz, 3H); IR (neat) 2926, 1724, 1497, 1460, 1245, 1173,
ꢀ
Synthesis of Methyl Dehydroabietate (2 ). A 50-mL round-
bottom flask, equipped with a magnetic stirring bar and a reflux
condenser topped by a CaCl2 drying tube, was charged with dehy-
32
ꢀ
droabietic acid 1 (125 mg, 0.417 mmol). Methanol (20 mL) and
822 cmꢁ1; ½ꢂꢆD þ30:5ꢄ (c 1.0, EtOH). Found: C, 81.37; H,
conc. H2SO4 (5 drops) was added, and the reaction mixture was
heated under reflux for 24 h. The reaction mixture was concentrat-
ed under reduced pressure and diluted with ether (15 mL). The
mixture was washed with sat. NaHCO3 aq, water, brine, and dried
over anhyd. NaSO4. The solution was concentrated to dryness,
and the residue was purified by chromatography (silica gel, hex-
ane:ethyl acetate = 20:1). The eluent was concentrated to obtain
10.91%. Calcd for C30H48O2: C, 81.76; H, 10.97%.
Synthesis of Phenyl Dehydroabietate (6 ). Following the
ꢀ
general procedure, 6 (155 mg, 0.412 mmol) was obtained as a
ꢀ
ꢀ
colorless oil in 43.4% yield from 1 (269 mg, 0.897 mmol) and
phenol (89.3 mg, 0.949 mmol). 1H NMR (300 MHz, CDCl3) ꢆ
7.50–7.31 (m, 3H), 7.25–7.13 (m, 3H), 7.00 (d, J ¼ 8:09 Hz, 1H),
6.88 (s, 1H), 2.92–2.70 (m, 3H), 2.39–2.20 (m, 2H), 1.95–1.75 (m,

H. Shitara et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 3 (2007)
593
6H), 1.75–1.50 (m, 1H), 1.39 (s, 3H), 1.25 (d, J ¼ 7:3 Hz, 6H),
1.21 (s, 3H); 13C NMR (100 MHz, CDCl3) ꢆ 16.59, 18.58, 21.87,
23.95 (2C), 25.20, 30.15, 33.44, 36.43, 37.21, 37.96, 44.88, 47.88,
121.41 (2C), 123.99, 124.20, 125.82, 126.62, 129.35 (2C), 134.57,
145.80, 146.74, 151.19, 177.19; IR (neat) 2955, 1746, 1594, 1493,
3
G. Vertogen, W. H. de Jeu, Thermotropic Liquid Crystals,
Fundamentals, Springer, Berlin, 1988.
Y. Aoki, S. Nomoto, T. Hirose, H. Nohira, Mol. Cryst. Liq.
Cryst. 2000, 346, 35.
H.-G. Kuball, T. H. Muller, H. Bruning, A. Schonhofer,
4
5
¨
¨
¨
32
1232, 1197, 822 cmꢁ1; ½ꢂꢆD þ69:3ꢄ (c 1.0, MeOH). Found: C,
Mol. Cryst. Liq. Cryst. 1995, 261, 205.
C. Stutzer, W. Weissflog, H. Stegmeyer, Liq. Cryst. 1996,
21, 557.
81.97; H, 8.62%. Calcd for C26H32O2: C, 82.93; H, 8.57%.
Synthesis of 4-Hexyloxyphenyl Dehydroabietate (7 ). Fol-
6
¨
ꢀ
lowing the general procedure, 7 (220 mg, 0.462 mmol) was
ꢀ
7
a) H. Shitara, Y. Aoki, T. Hirose, H. Nohira, Bull. Chem.
ꢀ
obtained as a colorless oil in 46.1% yield from 1 (301 mg,
Soc. Jpn. 2000, 73, 259. b) H. Shitara, Y. Aoki, T. Hirose, H.
Nohira, Chem. Lett. 1998, 261.
1.00 mmol) and 4-hexyloxyphenol (479 mg, 1.01 mmol). 1H NMR
(300 MHz, CDCl3) ꢆ 7.52 (d, J ¼ 8:43 Hz, 2H), 7.47 (d, J ¼ 8:43
Hz, 2H), 7.20 (d, J ¼ 8:45 Hz, 1H), 7.06 (d, J ¼ 8:45 Hz, 1H),
6.91 (s, 1H), 3.99 (t, J ¼ 6:62 Hz, 2H), 3.05–2.80 (m, 3H), 2.46
(d, J ¼ 11:4 Hz, 1H), 2.36 (d, J ¼ 12:9 Hz, 1H), 2.10–1.70 (m,
7H), 1.70–1.11 (m, 20H), 0.912 (t, J ¼ 6:96 Hz, 3H); IR (neat)
8
Z. Guangyou, L. Yuquing, W. Zhaohui, H. Nohira, T. Hir-
ose, Tetrahedron: Asymmetry 2003, 14, 3297.
S. Hamodrakas, D. Akrigg, B. Sheldrick, Cryst. Struct.
9
Commun. 1978, 7, 429.
10 a) M. J. S. Dewar, E. G. Zoebisch, E. F. Healy, J. J. P.
Stewart, J. Am. Chem. Soc. 1985, 107, 3902. b) J. J. P. Stewart,
J. Comput. Chem. 1989, 10, 209. c) J. J. P. Stewart, MOPAC
2002, Fujitsu Ltd., Tokyo, Japan, 1998.
11 R. Cano, Bull. Soc. Fr. Mineral. Cristallogr. 1968, 91, 20.
12 N. Emoto, M. Tanaka, S. Saito, K. Furukawa, T. Inukai,
Jpn. J. Appl. Phys. 1989, 28, L121.
13 a) G. P. Spada, G. Proni, Enantiomer 1998, 3, 301. b) D.
Vizitiu, C. Lazar, B. J. Halden, R. P. Lemieux, J. Am. Chem.
Soc. 1999, 121, 8229. c) J. Yoshida, H. Sato, A. Yamagishi, N.
Hoshino, J. Am. Chem. Soc. 2005, 127, 8453.
14 a) A. Ferrarini, G. J. Moro, P. L. Nordi, Phys. Rev. E 1996,
53, 681. b) A. di Matteo, A. Ferrarini, G. J. Moro, J. Phys. Chem.
B 2000, 104, 7764. c) A. di Matteo, A. Ferrarini, J. Phys. Chem. B
2001, 105, 2837. d) A. di Matteo, S. M. Todd, G. Gottarelli, G.
´
Solladie, V. E. Williams, R. P. Lemieux, A. Ferrarni, G. P. Spada,
J. Am. Chem. Soc. 2001, 123, 7842.
15 N. L. Allinger, J. Am. Chem. Soc. 1977, 99, 8127.
16 L. Qixian, Songzhi Jiagong Gongyi, China Forestry
Publication, Beijing, Chinese, 1998, pp. 49–51.
17 A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C.
Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R.
Spagna, J. Appl. Crystallogr. 1999, 32, 115.
34
2931, 1734, 1499, 1459, 994, 821 cmꢁ1; ½ꢂꢆD þ35:6ꢄ (c 0.5,
CHCl3).
ꢀ
Synthesis of 40-Hexyloxybiphenyl-4-yl Dehydroabietate (8 ).
ꢀ
Following the general procedure, 8 (260 mg, 0.471 mmol) was
obtained as a colorless oil in 45.3% yield from 1 (312 mg,
ꢀ
1.04 mmol) and 40-hexyloxybiphenyl-4-ol (281 mg, 1.04 mmol).
1H NMR (300 MHz, CDCl3) ꢆ 7.52 (d, J ¼ 8:40 Hz, 2H), 7.47
(d, J ¼ 8:80 Hz, 2H), 7.19 (d, J ¼ 8:00 Hz, 1H), 7.08–6.08 (m,
4H), 6.95 (d, J ¼ 8:00 Hz, 1H), 4.00 (t, J ¼ 8:80 Hz, 2H), 3.03–
2.89 (m, 3H), 2.83 (m, 1H), 2.46 (d, J ¼ 12:4 Hz, 1H), 2.36 (d,
J ¼ 12:8 Hz, 1H), 2.06–1.40 (m, 7H), 1.38–1.28 (m, 20H),
0.912 (t, J ¼ 7:00 Hz, 3H); IR (neat) 3465, 2950, 1744, 1608,
1497, 1205, 1166, 822 cmꢁ1; EI-MS (70 eV) m=z (rel. intensity)
34
552 (Mþ; 22), 299 (35), 270 (100); ½ꢂꢆD þ34:7ꢄ (c 0.5, CHCl3).
References
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