The chiral pool as valuable natural source: New chiral mesogens made from lactic acid

Article abstract of DOI:10.1080/15421406.2011.569689

Twenty new enantiopure chiral materials have been synthesized, showing liquid crystalline phases of smectic (SmA*), twisted grain boundary (TGB) and cholesteric (N*) type. The central ester-linkage as well as the length of the attached alkyl-chains were varied in a systematic way and the effects of these structural changes on the liquid crystalline properties have been studied. The liquid crystalline phases were characterized by means of differential scanning calorimetry, polarisation microscopy as well as small angle X-ray diffraction (SAXS). Copyright Taylor & Francis Group, LLC.

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The Chiral Pool as Valuable Natural
Source: New Chiral Mesogens Made From
Lactic Acid
F. Brombach a , J. M. Neudörfl a & D. Blunk a
a Department of Chemistry, University of Cologne, Cologne,
Germany
Published online: 14 Jun 2011.
To cite this article: F. Brombach , J. M. Neudrfl & D. Blunk (2011) The Chiral Pool as Valuable Natural
Source: New Chiral Mesogens Made From Lactic Acid, Molecular Crystals and Liquid Crystals, 542:1,
62/[584]-74/[596], DOI: 10.1080/15421406.2011.569689
To link to this article: http://dx.doi.org/10.1080/15421406.2011.569689
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Mol. Cryst. Liq. Cryst., Vol. 542: pp. 62=[584]–74=[596], 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 1542-1406 print=1563-5287 online
DOI: 10.1080/15421406.2011.569689
The Chiral Pool as Valuable Natural Source: New
Chiral Mesogens Made From Lactic Acid
¨
F. BROMBACH, J. M. NEUDORFL, AND D. BLUNK
Department of Chemistry, University of Cologne, Cologne, Germany
Twenty new enantiopure chiral materials have been synthesized, showing liquid crys-
talline phases of smectic (SmAꢀ), twisted grain boundary (TGB) and cholesteric
(Nꢀ) type. The central ester-linkage as well as the length of the attached
alkyl-chains were varied in a systematic way and the effects of these structural
changes on the liquid crystalline properties have been studied. The liquid crystalline
phases were characterized by means of differential scanning calorimetry, polaris-
ation microscopy as well as small angle X-ray diffraction (SAXS).
Keywords Chiral pool; chirality; cholesteric phase; liquid crystals; smectic phase;
synthesis
1. Introduction
Chiral liquid crystalline (LC) materials have gained increasing importance over the
last few decades. Especially mesophases with a chiral tilt pattern of the mesogens
have attracted the attention of physicists and chemists worldwide due to their impor-
tance for ferroelectric LC-displays, but also the chiral nematic (i.e., cholesteric) and
SmAꢀ-phase show interestung features (flexoelectric or electroclinic effect, respect-
ively) which possibly could be applied in electro-optic devices [1–3]. A somewhat
more exotic example of an application of chiral LC-phases is the movement of
macroscopic objects on a liquid crystalline film [4].
In many mesogens of this kind the chirality is allocated in the aliphatic
side-chain which is connected to the core via an ester or ether function. As starting
materials for the syntheses of such esters or ethers most commonly enantiomerically
pure secondary alkyl alcohols are used which have the disadvantage that they are
comparatively expensive due to their difficult production. Therefore a reasonable
approach for synthesizing chiral, enantiomerically pure low-cost materials is the
use of chiral-pool materials like naturally occurring alcohols, amino-acids or the
bifunctional lactic-acid. The latter is the approach which we follow here. The prin-
cipal use of lactic acid in mesogenic structures is not completely new [5–7], but still
the field is wide open and interesting to be explored.
Address correspondence to D. Blunk, Department of Chemistry, University of Cologne,
Greinstrasse 4, 50939 Cologne, Germany. Tel.: þ49-221-470-5213; Fax: þ49-221-470-3064;
E-mail: d.blunk@uni-koeln.de
62=[584]

New Chiral Mesogens Made From Lactic Acid
63=[585]
Figure 1. Fischer esterification of lactic acid with alcohols to yield the lactates 2a-e.
2. Synthesis
The syntheses of the chiral homologue side chains started from commercially avail-
able (S)-lactic-acid (1) which was esterified under acid catalyzed conditions to yield
the alkyl-lactates 2a-e in enantiomerically pure form (Fig. 1).
The syntheses towards the stiff mesogen cores are shown in Figure 2. These core
systems were synthesized via Steglich or acid chloride esterification reactions. For
the synthesis of 13 the Steglich esterification failed. Instead, esterification with the
respective acid chloride was successful (which previously was prepared from the car-
boxylic acid with SOCl2). Afterwards, the resulting benzaldehydes were oxidized
with Jones reagent to yield the carboxylic acids 5, 7, 10 and 13. For all products,
except for 13, no extensive workup was required. Each precursor 5, 7, 10 and 13
was isolated and purified by a single recrystallisation in excellent purities. All these
intermediates, the aldehydes resulting after the first step and the carboxylic acids 5,
7, 10 and 13 show thermotropic liquid crystalline behavior which will be reported
elsewhere together with their detailed synthetic and analytic description.
By combining the five chiral alkyl-lactates 2a-e with the four carboxylic acids 5,
7, 10 and 13 twenty new mesogens were synthesized using a modified Mitsunobu pro-
tocol in which di-tert-butyl azodicarboxylate (DTBAD) was used to simplify the
purification of the final products: DTBAD decomposes in strong acids [8]. An
example for this type of reaction is given in Figure 3. Details about the likewise synth-
eses of all the new chiral liquid crystalline compounds 14-17 are compiled in Table 1.
3. Thermomesomorphic Properties
The characterization of the mesophases of 14-17 was performed by means of polariza-
tion microscopy, differential scanning calorimetry and X-ray diffraction measurements.
Figure 2. Synthesis of the four rigid core systems 5, 7, 10 and 13.

64=[586]
F. Brombach et al.
Figure 3. Modified Mitsunobu esterification on the example of 14a. This principal method
was used here to build all the target compounds 14-17. The yield of 70% was obtained for this
exemplified reaction; in general up to 88% of the desired product was isolated (cf. Table 1).
Instrumental details are given in the experimental part. The mesogenic proper-
ties of the synthesized new chiral mesogens are summarized in Table 2. Most inter-
estingly, despite of its influence on the p-system of the mesogens, the orientation of
the central ester linkage is not that much important for the thermotropic behavior of
the compounds, but the nature of the bicyclic structure of the core system is. In case
of the cyclohexyl phenyl core (series 14 and 16), a cholesteric mesophase is found.
Furthermore, the clearing temperatures of series 14 and 16 decrease with increasing
chain length while the melting temperatures are comparable between both series. For
the bicyclohexyl derivatives (series 15 and 17) the clearing temperatures decrease
with increasing chain length. The same trend is observed for the melting tempera-
tures of 17, except for n ¼ 6 which is an outlier. In contrast to the cyclohexyl phenyl
core mesogens (series 14 and 16) all of the bicyclohexyl core mesogens (series 15 and
17) developed smectic phases additionally to the cholesteric phase. In some cases
Table 1. Synthesized, chiral liquid crystalline compounds
Carboxylic
acid
Alcohol Product Yield (%)
5
5
5
5
5
7
7
7
7
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
14a
14b
14c
14d
14e
15a
15b
15c
15d
15e
16a
16b
16c
16d
16e
17a
17b
17c
17d
17e
70
76
65
54
60
52
71
75
57
68
88
48
66
45
66
75
40
50
47
35
7
10
10
10
10
10
13
13
13
13
13

65=[587]

66=[588]
F. Brombach et al.
Table 3. Measured layer thicknesses in the SmAꢀ-phase, calculated molecular length
and intralayer molecular distances
Measured layer
distance
Calculated
molecular length
Intralayer
molecular distance
Substance
˚
˚
˚
15b
15c
15e
27.6 A
26.9 A
4.8 A
˚
˚
˚
29.5 A
29.0 A
4.8 A
˚
32.3 A
˚
33.7 A
˚
4.7 A
(14a, 15d, 15e, 17b and 17c) a TGB phase could be observed between the SmAꢀ and
the cholesteric phase.
For compounds 15b, 15c and 15e SAXS measurements were performed to deter-
mine the layer spacing of the SmAꢀ phase. To compare these results with the respect-
ive molecular structure, the molecular length was estimated by simple force field
simulations using Macromodel 9.0 with the implemented MM3 force field [9]. The
results of these studies are listed in Table 3. In addition to the small angle X-ray dif-
fraction studies also wide angle measurements were performed. When the samples
were cooled below the temperature range of the SmAꢀ-phase the broad, diffuse halo
in the wide angle region sharpened and split up to give narrower circles which
corresponds to the formation of order within the smectic layers.
4. Single Crystal X-Ray Structure and Circular Dichroism
Some single crystals for X-ray analysis could be grown from compound 16e. How-
ever, the quality of the crystals was somewhat poor due to their sensitivity to mech-
anical stress. Although the obtained R-values of 15% for R1 and 12% for R2 are too
large to meet crystallographic quality standards, the molecular structure could be
clearly identified and the obtained crystal structure of 16e is shown in Figure 4.
Interestingly, the carbonyl oxygens of the central terephthalic acid unit have a
dihedral-angle of 0.7ꢁ with respect to each other (and not of 180ꢁ) which is a rather
uncommon feature in crystals for terephthalic acid derivatives. The absolute con-
figuration of the stereogenic center could not be confirmed directly by these X-ray
investigations due to the lack of heavier atoms than oxygen, but the expected reten-
tion of stereochemistry could be proven by the combination of the X-ray structure
with circular dichroism (CD) measurements.
The CD spectrum of 16e is depicted in Figure 5 and shows a negative Cotton
effect at 240 nm. Putting the crystal structure of 16e into the model of the octant rule,
the negative sign of the Cotton effect could be rationalized (Fig. 6) and proves the
expected retention of the (S)-configured stereo center throughout the synthesis.
Figure 4. Two molecules of 16e in their crystalline packing. (Figure appears in color online.)

New Chiral Mesogens Made From Lactic Acid
67=[589]
Figure 5. Circular dichroism spectrum of 16e.
=
Figure 6. Carbonyl octant rule applied to 16e, view along the C O bond (upper part), view
from the top (lower part). (Figure appears in color online.)

68=[590]
F. Brombach et al.
Quantum chemical calculations in order to separate the contribution of each of the
two carbonyl chromophores in the vicinity of the stereocenter to the CD spectrum
are in progress.
5. Summary and Perspectives
Twenty new enantiomerically pure thermomesomorphic compounds were synthesized
(series 14-17), each in three linear synthetic steps from commercially available building
blocks with their chirality originating from cheap lactic acid. With these compounds
the influence of the reversion of the central ester linkage as well as the changes in
the mesomorphic properties in cases of either a bicyclohexyl or cyclohexylphenyl core
substructure have been investigated. Especially the mesogens 15c and 17c with
medium long aliphatic chains show melting temperatures close to room temperature
and a broad temperature range of their SmAꢀ phase. For all compounds a short pitch
cholesteric phase was found, partly accompanied with smectic or TGB phases.
Currently we are investigating the influence of replacing the central phenyl ring
of the terephthalic acid or hydroxybenzoic acid substructures, respectively, with a
biphenyl system. With these systems we expect a stabilization of smectic phases
but also higher melting points.
6. Experimental
6.1. Instruments
1H-NMR. The 1H-NMR spectra were recorded on Bruker AC 300, Bruker DPX 300
or on Bruker DRX 500 instruments. Chemical shifts are reported as d in ppm,
coupling constants J in Hz. DMSO-d6 (d ¼ 2.49 ppm) or CDCl3 (d ¼ 7.24 ppm)
were used as solvents, respectively, and the peaks of their undeuterated parts were
used as internal standard. Splitting patterns are designated as s (singlet), d
(doublet), t (triplet), q (quartet) or m (multiplet).
13C-NMR. The 13C-NMR spectra were recorded as APT spectra either on a Bruker
AC 300 or on a Bruker DRX 500 instrument.
Mass Spectrometry. (HR-MS) were recorded on a Finnigan MAT 900S. The method
of ionization is given individually with each spectrum in parentheses.
Elemental Analysis. Elementar Vario EL.
Differential Scanning Calorimetry (DSC). Mettler DSC TA3000, heating rate 5 K=
min, cooling rate 10 K=min.
Polarization Microscopy (PM). Leitz Laborlux 12 Pol.
Small and Wide Angle X-Ray Scattering (SAXS and WAXS). X-Ray measurements
were performed using aligned samples (filled in 0.7 mm Mark capillars) with a
Bruker AXS NanoSTAR with a 2D-detector.
6.2. Synthetic Precursors
The aldehydes and carboxylic acids 5, 7, 10 and 13 were synthesized according to
Figure 2 by using standard procedures. Exact reaction conditions as well as analyti-
cal data of these substances are available from the author on request.

New Chiral Mesogens Made From Lactic Acid
69=[591]
6.3. General Procedure for the Mitsunobu Esterification
Under Argon-Atmosphere a Schlenck-flask was charged with 1 mmol of carboxylic
acid 5, 7, 10 or 13, respectively, and 1 mmol of PPh3. Afterwards dry THF and
1 mmol of the corresponding alcohol 2a-e were added. To this solution 1 equivalent
of DTBAD was added in small portions. The progress of the reaction was followed
by TLC. After completion of the reaction the solvent was removed and the target
compound was isolated via flash-chromatography with ethylacetate=cyclohexane
as mobile phase and silica gel as stationary phase.
6.4. Analytical Data
The atom numbers in the structure drawings apply to the assignments given in the
spectra and do not follow the IUPAC scheme used for the naming of the com-
pounds. IR and LR-MS of all compounds are available from the authors on request.
Figure 7.
4-(f[(2R)-1-Ethoxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)benzoate
14a, n ¼ 2. dH (300MHz; CDCl3) ¼ 8.12 (m, 4H; 7-H, 12-H), 7.30 (m, 4H; 6-H, 11-H),
5.31 (q, J ¼ 7.0 Hz, 1H; 15-H), 4.23 (q, J ¼ 7.1 Hz, 2H; 17-H), 2.55 (m, 1H; 4-H), 1.89
(m, 4H), 1.34 (m, 18H). dC(75 MHz; CDCl3) ¼ 170.3 (C16), 164.8 (C14), 164.2 (C9),
154.6 (C10), 154.1 (C5), 131.0 (C7=C12), 130.0 (C7=C12), 126.8 (C6), 126.6 (C8=
C13), 126.2 (C8=C13), 121.4 (C11), 68.8 (C15), 61.0 (C17), 44.4 (C4), 39.2, 36.5, 33.6
(2C), 32.9 (2C), 19.6, 16.7, 13.9, 13.7. HR-MS (EI, 70 eV); m=z: 466.236 (calc.
466.2355). EA: Found: C, 72.077; H, 7.3424. C28H34O6 calculated C, 72.08; H, 7.35%.
4-(f[(2R)-1-Butoxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)benzoate
14b, n ¼ 4. dH (300 MHz; CDCl3) ¼ 8.12 (m, 4H; 7-H, 12-H), 7.30 (m, 4H; 6-H,
11-H), 5.31 (q, J ¼ 7.0 Hz, 1-H; 15-H), 4.16 (m, 2H; 18-H), 2.55 (m, 1H; 4-H), 1.89
(m, 4H; 3-H), 1.34 (m, 22H). dC(75 MHz; CDCl3) ¼ 170.8 (C16), 165.2 (C14), 164.6
(C9), 155.0 (C10), 154.5 (C5), 131.4 (C7=C12), 130.4 (C7=C12), 127.2 (C6), 127.0
(C8=C13), 126.6 (C8=C13), 121.8 (C11), 69.3 (C15), 65.2 (C17), 44.9 (C4), 39.6,
36.9, 34.0 (2C), 33.4 (2C), 30.5, 20.0, 19.0, 17.1, 14.4, 13.6. HR-MS (EI, m=z):
494.267 (calc. 494.2668). EA: Found: C, 72.652; H, 7.7572. C30H38O6 calculated C,
72.85; H, 7.74%.
4-(f[(2R)-1-Hexyloxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)benzoate
14c, n ¼ 6. dH(300 MHz; CDCl3) ¼ 8.12 (m, 4H; 7-H, 12-H), 7.30 (m, 4H; 6-H,
11-H), 5.31 (q, J ¼ 7.0 Hz, 1-H; 15-H), 4.16 (m, 2H; 18-H), 2.55 (m, 1H; 4-H),
1.89 (m, 4H; 3-H), 1.34 (m, 26H). dC(75 MHz; CDCl3) ¼ 170.8 (C16), 165.2 (C14),

70=[592]
F. Brombach et al.
164.6 (C9), 155.0 (C10), 154.5 (C5), 131.4 (C7=C12), 130.4 (C7=C12), 127.2 (C6),
127.0 (C8=C13), 126.6 (C8=C13), 121.8 (C11), 69.3 (C15), 65.6 (C17), 44.9 (C4),
44.9, 39.7, 37.0, 34.0 (2C), 33.4 (2C), 31.4, 28.5, 25.4, 22.5, 20.0, 17.1, 14.4, 13.6.
HR-MS (EI, 70 eV); m=z: 522.297 (calc. 522.2981). EA: Found: C, 73.561; H
8.0388,. C32H42O6 calculated C, 73.53; H, 8.10%.
4-(f[(2R)-1-Octyloxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)benzoate
14d, n ¼ 8. dH(300 MHz; CDCl3) ¼ 8.12 (m, 4H; 7-H, 12-H), 7.30 (m, 4H; 6-H,
11-H), 5.31 (q, J ¼ 7.0 Hz, 1-H; 15-H), 4.16 (m, 2H; 18-H), 1.34 (m, 30H).
dC(75 MHz; CDCl3) ¼ 170.8 (C16), 165.2 (C14), 164.6 (C9), 155.0 (C10), 154.5
(C5), 131.4 (C7=C12), 130.4 (C7=C12), 127.2 (C6), 127.0 (C8=C13), 126.6 (C8=
C13), 121.8 (C11), 69.3 (C15), 65.5 (C17), 44.9 (C4), 44.9, 39.6, 36.9, 34.0 (2C),
33.4 (2C), 31.7, 29.1 (2C), 28.5, 25.8, 22.6, 20.0, 17.1, 14.4, 14.1. HR-MS (ESI,
70 eV; MeOH); m=z: 573.319 (calc. 573.3192) [MþNa]þ. EA: Found: C, 74.259;
H, 8.4967. C34H46O6 calculated C, 74.15; H, 8.42%.
4-(f[(2R)-1-Decyloxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)benzoate
14e, n ¼ 10. dH(300 MHz; CDCl3) ¼ 8.12 (m, 4H; 7-H, 12-H), 7.30 (m, 4H; 6-H,
11-H), 5.31 (q, J ¼ 7.0 Hz, 1-H; 15-H), 4.16 (m, 2H; 18-H), 1.34 (m, 34H).
dC(75 MHz; CDCl3) ¼ 170.8 (C16), 165.2 (C14), 164.6 (C9), 155.0 (C10), 154.5
(C5), 131.4 (C7=C12), 130.4 (C7=C12), 127.2 (C6), 127.0 (C8=C13), 126.6 (C8=
C13), 121.8 (C11), 69.3 (C15), 65.5 (C17), 44.8 (C4), 39.6, 36.9, 34.0 (2C), 33.4
(2C), 31.8, 29.5 (2C), 29.2, 29.1, 28.4, 25.7, 22.6, 19.9, 17.1, 14.3, 14.1. HR-MS
(ESI, 70 eV; MeOH); m=z: 601.351 (calc. 601.3505) [MþNa]þ. EA: Found: C,
74.716; H, 8.7780. C36H50O6 calculated C, 74.71; H, 8.71%.
Figure 8.
4-(f[(2R)-1-Ethoxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)
cyclohexane-1-carboxylate 15a, n ¼ 2. dH(300 MHz; CDCl3) ¼ 8.08 (d, J ¼ 8.7 Hz,
2H; 12-H), 7.13 (d, J ¼ 8.7 Hz, 2H; 11-H), 5.28 (q, J ¼ 7.0 Hz, 1H; 15-H), 4.21 (q,
J ¼ 7.1 Hz, 2H; 17-H), 2.45 (m, 1H; 8-H), 2.14 (d, J ¼ 12.1 Hz, 2H; 7-H), 1.50 (m,
30H). dC(75 MHz; CDCl3) ¼ 174.1 (9-C), 170.7 (16-C), 165.2 (14-C), 154.9 (10-C),
131.4 (12-C), 126.8 (13-C), 121.6 (11-C), 69.2 (15-C), 61.4 (17-C), 43.7, 43.2, 42.5,
39.8, 37.6, 33.5 (2C), 30.0 (2C), 29.2 (2C), 29.1 (2C), 20.0, 17.1, 14.4, 14.1.
HR-MS (EI, 70 eV); m=z: 472.283 (calc. 472.2825). EA: Found: C,71.054 ; H,
8.5263. C28H40O6 calculated C, 71.16; H, 8.53%.
4-(f[(2R)-1-Butoxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)
cyclohexane-1-carboxylate 15b, n ¼ 4. dH(300 MHz; CDCl3) ¼ 8.08 (d, J ¼ 8.6 Hz,
2H; 12-H), 7.13 (d, J ¼ 8.6 Hz, 2H; 11-H), 5.28 (q, J ¼ 7.0 Hz, 1H; 15-H), 4.15 (m,

New Chiral Mesogens Made From Lactic Acid
71=[593]
2H, 17-H), 2.45 (m, 1H; 8-H), 2.14 (d, J ¼ 12.1 Hz, 2H; 7-H), 1.50 (m, 34H).
dC(75 MHz; CDCl3) ¼ 174.1 (9-C), 170.7 (16-C), 165.2 (14-C), 154.9 (10-C), 131.4
(12-C), 126.8 (13-C), 121.6 (11-C), 69.2 (15-C), 65.3 (17-C), 43.7, 43.2, 42.5, 39.8,
37.6, 33.5 (2C), 30.5, 30.0 (2C), 29.3 (2C), 29.1 (2C), 20.0, 19.0, 17.1, 14.4, 13.7.
HR-MS (EI, 70 eV); m=z: 500.313 (calc. 500.3138). EA: Found: C, 72.186; H,
8.8348. C30H44O6 calculated C, 71.97; H, 8.86%.
4-(f[(2R)-1-Hexyloxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)
cyclohexane-1-carboxylate 15c, n ¼ 6. dH(300 MHz; CDCl3) ¼ 8.08 (d, J ¼ 8.6 Hz,
2H; 12-H), 7.13 (d, J ¼ 8.7 Hz, 2H; 11-H), 5.29 (q, J ¼ 7.0 Hz, 1H; 15-H), 4.13 (m,
2H; 17-H), 2.45 (m, 1H; 8-H), 2.14 (d, J ¼ 12.2 Hz, 2H; 7-H), 1.50 (m, 38H).
dC(75 MHz; CDCl3) ¼ 174.1 (9-C), 170.7 (16-C), 165.2 (14-C), 154.9 (10-C), 131.4
(12-C), 126.8 (13-C), 121.6 (11-C), 69.2 (15-C), 65.5 (17-C), 43.7, 43.2, 42.5, 39.8,
37.6, 33.5 (2C), 31.3, 30.0 (2C), 29.3 (2C), 29.1 (2C), 28.4, 25.4, 22.5, 20.0, 17.1,
14.4, 13.7. HR-MS (EI, 70 eV); m=z: 528.345 (calc. 528.3451). EA: Found: C,
72.672; H, 9.1451. C32H48O6 calculated C, 72.69; H, 9.15%.
4-(f[(2R)-1-Octyloxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)
cyclohexane-1-carboxylate 15d, n ¼ 8. dH(300 MHz; CDCl3) ¼ 8.08 (d, J ¼ 8.6 Hz, 2H;
12-H), 7.13 (d, J ¼ 8.7 Hz, 2H; 11-H), 5.29 (q, J ¼ 7.0 Hz, 1H; 15-H), 4.13 (m, 2H;
17-H), 2.45 (m, 1H; 8-H), 2.14 (d, J ¼ 12.2 Hz, 2H; 7-H), 1.50 (m, 42H).
dC(75 MHz; CDCl3) ¼ 174.1 (9-C), 170.7 (16-C), 165.2 (14-C), 154.9 (10-C), 131.4
(12-C), 126.8 (13-C), 121.6 (11-C), 69.2 (15-C), 65.5 (17-C), 43.7, 43.2, 42.5, 39.8,
37.6, 33.5 (2C), 31.7, 30.0 (2C), 29.2 (2C), 29.1 (2C), 29.0 (2C), 28.5, 25.7, 22.6,
20.0, 17.1, 14.4, 14.1. HR-MS (EI, 70 eV); m=z: 556.3766 (calc. 556.3764). EA:
Found: C, 73.405; H, 9.4615. C34H52O6 calculated C, 73.34; H, 9.41%.
Figure 9.
4-(f[(2R)-1-Decyloxy-1-oxopropan-2-yl]oxygcarbonyl)phenyl 4-(4-propylcyclohexyl)
cyclohexane-1-carboxylate 15e, N ¼ 10. dH(300MHz; CDCl3) ¼ 8.08 (d, J ¼ 8.7 Hz,
2H; 12-H), 7.13 (d, J ¼ 8.7 Hz, 2H; 11-H), 5.28 (q, J ¼ 7.1 Hz, 1H; 15-H), 4.15 (m,
2H, 17-H), 2.45 (m, 1H; 8-H), 2.14 (d, J ¼ 12.3 Hz, 2H; 7-H), 1.50 (m, 46H).
dC(75 MHz; CDCl3) ¼ 174.1 (9-C), 170.7 (16-C), 165.2 (14-C), 154.9 (10-C), 131.4
(12-C), 126.8 (13-C), 121.6 (11-C), 69.2 (15-C), 65.5 (17-C), 43.7, 43.2, 42.5, 39.8,
37.6, 33.5 (2C), 31.9, 30.0 (2C), 29.5, 29.3 (2C), 29.2 (2C), 29.1 (2C), 28.5, 26.9,
25.7, 22.7, 20.0, 17.1, 14.4, 13.7. HR-MS (EI, 70eV); m=z: 584.407 (calc. 584.4077).
EA: Found: C, 73.725; H, 9.6296. C36H56O6 calculated C, 73.93; H, 9.65%.
4-(4-Propylcyclohexyl)phenyl 4-(f[(2R)-1-ethoxy-1-oxopropan-2-yl]oxygcarbonyl)benzoate
16a, n ¼ 2. dH(300 MHz; CDCl3) ¼ 8.22 (m, 4H; 11-H, 12-H), 7.25 (d, J ¼ 6.9 Hz,
2H; 6-H), 7.12 (d, J ¼ 8.5 Hz, 2H; 7-H) 5.34 (q, 1H, J ¼ 7.1 Hz; 15-H), 4.21 (q,

72=[594]
F. Brombach et al.
J ¼ 7.1 Hz, 2H; 17-H), 2.48 (m, 1H; 4-H), 1.88 (t, J ¼ 11.4 Hz, 4H; 3-H), 1.64 (d,
J ¼ 7.1 Hz, 3H; 100-H), 1.28 (m, 12H), 0.89 (t, J ¼ 6.9 Hz, 3H; 30-H). dC(75 MHz;
CDCl3) ¼ 170.5 (C-16), 165.1 (C-9=C-13), 164.5 (C-9=C-13), 148.6 (C-8), 145.7
(C-5), 133.8 (C-13, C-10), 130.1 (C-11=C-12), 129.9 (C-11=C-12), 127.8 (C-6),
121.1 (C-7), 69.6 (C-100), 61.5 (C-17), 44.1 (C-4), 39.7 (C-10), 37.0 (C-1), 34.4 (C-2=
C-3), 33.5 (C-2=C3), 20.0 (C-20), 17.0 (C-3), 14.4 (C-18), 14.1 (C-30). HR-MS (EI,
70 eV); m=z: 466.235 (calc. 466.2355). EA: Found: C, 71.995; H, 7.3788. C28H34O6
calculated C, 72.08; H, 7.35%.
4-(4-Propylcyclohexyl)phenyl 4-(f[(2R)-1-butoxy-1-oxopropan-2-yl]oxygcarbonyl)benzoate
16b, n ¼ 4. dH(300 MHz; CDCl3) ¼ 8.22 (m, 4H; 11-H, 12-H), 7.25 (d, J ¼ 6.9 Hz,
2H; 6-H), 7.12 (d, J ¼ 8.5 Hz, 2H; 7-H), 5.34 (q, J ¼ 7.1 Hz, 1H; 15-H), 4.18 (t,
J ¼ 6.4 Hz, 2H; 17-H), 2.48 (m, 1H; 4-H), 1.88 (t, J ¼ 11.5 Hz, 4H; 3-H), 1.64 (d,
J ¼ 7.1 Hz, 3H; 1’’-H), 1.28 (m, 19H). dC(75 MHz; CDCl3) ¼ 170.5 (C-16), 165.1
(C-9=C-13), 164.5 (C-9=C-13), 148.6 (C-8), 145.7 (C-5), 133.8 (C-13, C-10), 130.1
(C-11=C-12), 129.9 (C-11=C-12), 127.8 (C-6), 121.1 (C-7), 69.6 (C-100), 65.3, 44.0,
39.6, 36.9, 34.3 (2C), 33.5 (2C), 30.4, 20.0, 18.9, 17.0, 14.3, 13.6. HR-MS (EI,
70 eV); m=z: 494.266 (calc. 494.2668). EA: Found: C, 72.781; H, 7.7700. C30H38O6
calculated C, 72.85; H, 7.74%.
4-(4-Propylcyclohexyl)phenyl 4-(f[(2R)-1-hexyloxy-1-oxopropan-2-yl]oxygcarbonyl)benzoate
16c, n ¼ 6. dH(300 MHz; CDCl3) ¼ 8.22 (m, 4H; 11-H, 12-H), 7.25 (d, J ¼ 6.9 Hz,
2H; 6-H), 7.12 (d, J ¼ 8.5 Hz, 2H; 7-H), 5.34 (q, J ¼ 7.0 Hz, 1H; 15-H), 4.15 (m,
2H; 17-H), 2.48 (m, 1H; 4-H), 1.88 (t, J ¼ 11.5 Hz, 4H; 3-H), 1.64 (d, J ¼ 7.1 Hz,
3H; 100-H), 1.28 (m, 23H). dC(75 MHz; CDCl3) ¼ 170.5 (C-16), 165.1 (C-9=C-13),
164.5 (C-9=C-13), 148.6 (C-8), 145.7 (C-5), 133.7 (C-13, C-10), 130.1 (C-11=C-12),
129.9 (C-11=C-12), 127.8 (C-6), 121.1 (C-7), 69.6 (C-100), 65.6, 44.0, 39.6, 36.9,
34.3 (2C), 33.5 (2C), 31.3, 28.4, 25.4, 22.4, 20.0, 17.0, 14.3, 13.9. HR-MS (EI,
70 eV); m=z: 522.298 (calc. 522.2981). EA: Found: C, 73.466; H, 8.1220. C32H42O6
calculated C, 73.53; H, 8.10%.
4-(4-Propylcyclohexyl)phenyl 4-(f[(2R)-1-octyloxy-1-oxopropan-2-yl]oxygcarbonyl)
benzoate 16d, n ¼ 8. dH(300 MHz; CDCl3) ¼ 8.22 (m, 4H; 11-H, 12-H), 7.25 (d,
J ¼ 6.9 Hz, 2H; 6-H), 7.12 (d, J ¼ 8.5 Hz, 2H; 7-H), 5.34 (q, J ¼ 7.0 Hz, 1H; 15-H),
4.15 (m, 2H; 17-H), 2.48 (m, 1H; 4-H), 1.88 (t, J ¼ 11.5 Hz, 4H; 3-H), 1.64 (d,
J ¼ 7.1 Hz, 3H; 100-H), 1.28 (m, 27H). dC(75 MHz; CDCl3) ¼ 170.5 (C-16), 165.1
(C-9=C-13), 164.5 (C-9=C-13), 148.6 (C-8), 145.7 (C-5), 133.8 (C-13, C-10), 130.1
(C-11=C-12), 129.9 (C-11=C-12), 127.8 (C-6), 121.1 (C-7), 69.7 (C-100), 65.7, 44.0,
39.6, 36.9, 34.3 (2C), 33.5 (2C), 31.8, 29.2, 31.3, 28.4, 25.4, 22.4, 20.0, 17.0, 14.3,
13.9. HR-MS (EI, 70 eV); m=z: 550.329 (calc. 550.3294). EA: Found: C, 74.021; H,
8.4327. C34H46O6 calculated C, 74.15; H, 8.42%.
4-(4-Propylcyclohexyl)phenyl 4-(f[(2R)-1-decyloxy-1-oxopropan-2-yl]oxygcarbonyl)benzoate
16e, n ¼ 10. dH(300 MHz; CDCl3) ¼ 8.22 (m, 4H; 11-H, 12-H), 7.25 (d, J ¼ 6.9 Hz,
2H; 6-H), 7.12 (d, J ¼ 8.5 Hz, 2H; 7-H), 5.34 (q, J ¼ 7.0 Hz, 1H; 15-H), 4.15 (m,
2H; 17-H), 2.48 (m, 1H; 4-H), 1.88 (t, J ¼ 11.5 Hz, 4H; 3-H), 1.64 (d, J ¼ 7.1 Hz,
3H; 100-H), 1.28 (m, 31H). dC(75 MHz; CDCl3) ¼ 170.5 (C-16), 165.1 (C-9=C-13),
164.5 (C-9=C-13), 148.6 (C-8), 145.7 (C-5), 133.8 (C-13, C-10), 130.1 (C-11=C-12),
129.9 (C-11=C-12), 127.8 (C-6), 121.1 (C-7), 69.6 (C-100), 65.6, 44.0, 39.6, 36.9,
34.3 (2C), 33.5 (2C), 31.8, 29.4 (2C), 29.2, 29.1, 28.4, 25.7, 22.6, 20.0, 17.0, 14.4,

New Chiral Mesogens Made From Lactic Acid
73=[595]
14.1. HR-MS (EI, 70 eV); m=z: 578.360 (calc. 578.3607). EA: Found: C, 74.225; H,
8.6944. C36H50O6 calculated C, 74.71; H, 8.71%.
Figure 10.
4-(4-Propylcyclohexyl)cyclohexyl 4-(f[(2R)-1-ethoxy-1-oxopropan-2-yl]oxygcarbonyl)
benzoate 17a, n¼ 2. dH(300 MHz; CDCl3) ¼ 8.09 (m, 4H; 11-H, 12-H), 5.31 (q,
J¼ 7.0 Hz, 1H; 15-H), 4.88 (m, 1H; 8-H), 4.23 (q, J ¼ 7.1 Hz, 2H; 17-H), 2.11 (m,
2H; 7-H), 1.20 (m, 30H). dC(75 MHz; CDCl3) ¼ 170.5 (C-16), 165.2 (C-9, C-14),
135.0 (C-10=C-13), 132.9 (C-10=C-13), 129.6 (C-11=C-12), 129.4 (C-11=C-12), 74.9
(C-8), 69.5 (C-15), 61.4 (C-17), 42.7, 42.2, 39.7, 37.5, 33.4 (2C), 31.9 (2C), 30.1 (2C),
27.9 (2C), 20.0, 17.0 (C-10), 14.4 (C-18), 14.0 (C-30). HR-MS (ESI, 70 eV; MeOH);
m=z: 495.272 (calc. 495.2722) [MþNa]þ. EA: Found: C, 71.136; H, 8.5667. C28H40O6
calculated C, 71.16; H, 8.53%.
4-(4-Propylcyclohexyl)cyclohexyl 4-(f[(2R)-1-butoxy-1-oxopropan-2-yl]oxygcarbonyl)
benzoate 17b, n¼ 4. dH(300MHz; CDCl3) ¼ 8.09 (m, 4H; 11-H, 12-H), 5.31 (q,
J ¼ 7.0 Hz, 1H; 15-H), 4.16 (m, 2H; 17-H), 2.11 (m, 2H; 7-H), 1.20 (m, 34H).
dC(75 MHz; CDCl3) ¼ 170.6 (C-16), 165.2 (C-14, C-9), 135.0 (C10=C13), 133.0 (C10=
C13), 129.7 (C-12=C-11), 129.5 (C-12=C-11), 75.0 (C-8), 69.6 (C-15), 65.3 (C-17), 42.8
(C-5=C-4), 42.3 (C-5=C-4), 39.8 (C-10), 37.6, 33.5 (2C), 32.0 (2C), 30.5, 30.2 (2C),
28.0 (2C), 20.1, 19.0, 17.1, 14.4, 13.6. HR-MS (EI, 70eV); m=z: 500.314 (calc.
500.3138). EA: Found: C, 71.793; H, 8.8316. C30H44O6 calculated C, 71.97; H, 8.86%.
4-(4-Propylcyclohexyl)cyclohexyl 4-(f[(2R)-1-hexyloxy-1-oxopropan-2-yl]oxygcarbonyl)
benzoate 17c, n¼ 6. dH(300 MHz; CDCl3)¼ 8.09 (m, 4H; 11-H, 12-H), 5.31 (q,
J¼ 7.0 Hz, 1H; 15-H), 4.14 (m, 2H; 17-H), 2.11 (m, 2H; 7-H), 1.20 (m, 38H).
dC(75 MHz; CDCl3)¼ 170.6 (C-16), 165.2 (C-14, C-9), 135.0 (C10=C13), 133.0 (C10=
C13), 129.7 (C-12=C-11), 129.5 (C-12=C-11), 75.0 (C-8), 69.5 (C-15), 65.6 (C-17), 42.7
(C-5=C-4), 42.2 (C-5=C-4), 39.8 (C-10), 37.5, 33.5(2C), 31.9 (2C), 31.3, 30.2 (2C), 28.4,
27.9 (2C), 25.4, 22.5, 20.0, 17.1, 14.4, 13.9. HR-MS (ESI, 70 eV; MeOH); m=z: 551.335
(calc. 551.3349) [MþNa]þ. EA: Found: C, 72.595; H, 9.1522. C32H48O6 calculated C,
72.69; H, 9.15%.
4-(4-Propylcyclohexyl)cyclohexyl 4-(f[(2R)-1-octyloxy-1-oxopropan-2-yl]oxygcarbonyl)
benzoate 17d, n ¼ 8. dH(300 MHz; CDCl3) ¼ 8.09 (m, 4H; 11-H, 12-H), 5.32 (q,
J ¼ 7.0 Hz, 1H; 15-H), 4.88 (m, 1H; 8-H), 4.14 (m, 2H; 17-H), 2.11 (m, 2H; 7-H),
1.26 (m, 42H). dC(75 MHz; CDCl3) ¼ 170.6 (C-16), 165.2 (C-14, C-9), 135.0 (C10=
C13), 133.0 (C10=C13), 129.7 (C-12=C-11), 129.5 (C-12=C-11), 75.0 (C-8), 69.5
(C-15), 65.6 (C-17), 42.7 (C-5=C-4), 42.2 (C-5=C-4), 39.8 (C-10), 37.5, 33.5 (2C),
31.9 (2C), 31.7, 30.2 (2C), 29.1 (2C), 28.5, 27.9 (2C), 25.8, 22.6, 20.0, 17.1, 14.1,

74=[596]
F. Brombach et al.
14.0. HR-MS (ESI, 70 eV; MeOH, CH2Cl2); m=z: 579.365 (calc. 579.3661) [MþNa]þ.
EA: Found: C, 73.193; H, 9.3013. C34H52O6 calculated C, 73.34; H, 9.41%.
4-(4-Propylcyclohexyl)cyclohexyl 4-(f[(2R)-1-decyloxy-1-oxopropan-2-yl]oxygcarbonyl)
benzoate 17e, n ¼ 10. dH(300 MHz; CDCl3) ¼ 8.09 (m, 4H; 11-H, 12-H), 5.32 (q,
J ¼ 7.0 Hz, 1H; 15-H), 4.88 (m, 1H; 8-H), 4.14 (m, 2H; 17-H), 2.11 (m, 2H; 7-H),
1.26 (m, 46H). dC(75 MHz; CDCl3) ¼ 170.6 (C-16), 165.2 (C-14, C-9), 135.0 (C10=
C13), 133.0 (C10=C13), 129.7 (C-12=C-11), 129.5 (C-12=C-11), 75.0 (C-8), 69.5
(C-15), 65.6 (C-17), 42.7 (C-5=C-4), 42.2 (C-5=C-4), 39.8 (C-10), 37.5, 33.5 (2C),
31.9 (2C), 31.9, 30.2 (2C), 29.5 (2C), 29.3, 29.1, 28.5 (2C), 27.9, 25.8, 22.7, 20.0,
17.1, 14.1, 14.0. HR-MS (ESI, 70 eV; MeOH); m=z: 607.397 (calc. 607.3975)
[MþNa]þ. EA: Found: C, 73.755; H, 9.5130. C36H56O6 calculated C, 73.93; H,
9.65%.
Acknowledgment
We thank the Merck KGaA, Darmstadt, Germany for providing us with valuable
starting materials as well as Prof. Dr. Gießelmann, Universita¨t Stuttgart, Germany
for giving us access to his SAXS- and WAXS-equipment.
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