Liquid crystals based on hypervalent sulfur fluorides. Part 4. [1] Pentafluorosulfanyl alkanes and olefins

Article abstract of DOI:10.1016/j.jfluchem.2005.11.015

New liquid crystals with a pentafluorosulfanyl function as their polar terminal group were prepared and fully characterized. The synthetic key step was the triethyl borane-catalyzed addition of SF₅Br to a suitable olefin precursor, followed by

Full text of DOI:10.1016/j.jfluchem.2005.11.015

Journal of Fluorine Chemistry 127 (2006) 610–619
www.elsevier.com/locate/fluor
Liquid crystals based on hypervalent sulfur fluorides
Part 4. [1] Pentafluorosulfanyl alkanes and olefins
b
b
Peer Kirsch a, , Jorg T. Binder , Enno Lork , Gerd-Volker Roschenthaler
*
b,**
¨
¨
a Merck Ltd. Japan, Atsugi Technical Center, 4084 Nakatsu, Aikawa-machi, Aiko-gun, Kanagawa 243-0303, Japan
b Institute for Inorganic and Physical Chemistry, University of Bremen, Leobener Str. NW2 C2350, D-28334 Bremen, Germany
Received 11 November 2005; accepted 16 November 2005
Available online 24 January 2006
Abstract
New liquid crystals with a pentafluorosulfanyl function as their polar terminal group were prepared and fully characterized. The synthetic key
step was the triethyl borane-catalyzed addition of SF5Br to a suitable olefin precursor, followed by dehydrobromination. The most interesting
characteristic of the new materials is their combination of high polarity (De) with very low birefringence (Dn), which is of particular importance for
LCDs for mobile applications.
# 2005 Elsevier B.V. All rights reserved.
Keywords: Cholestane derivatives; Hypervalent compounds; Liquid crystals; Mesogens; Steroids; Sulfur fluorides
1. Introduction
carbon–fluorine bonds [7]. The current benchmark for the
maximum achievable polarity for commercially used liquid
crystals is set by the trifluoromethyl group (e.g., 1). In order to
further increase De we started several years ago to investigate the
potential of polar groups based on hypervalent sulfur fluorides,
such as the pentafluorosulfanyl [1,8] and the trans-trifluoro-
methyltetrafluorosulfuranyl group [1]. The SF5 group shows a
chemical and photochemical stability similar to the CF3 group
[9], but its group dipole momentis significantly higher, rendering
it a kind of ‘‘super-CF3’’ function. The ion affinity of the
pentafluorosulfanyl group is weak enough to make it compatible
with current active matrix LCD technology [10].
In the recent few years liquid crystal displays (LCD) have
become an integral part of our daily life [2]. The nematic liquid
crystalline material in the ‘‘heart’’ of all LCD devices is required
to keep functioning for tenths of thousands of hours under
sometimes rather extreme environmental conditions without
noticable deterioration [3]. In particular for high-resolution
active matrix LCDs the liquid crystal has also to show a very low
ability to solvate and mobilize ionic impurities by coordinative
complexation [4]. These stringent requirements can currently
only be met by the so-called super fluorinated materials (SFM),
which do not contain any heteroatoms except fluorine and
oxygen [5]. The main functions of the fluorine substitution in this
type of materials are the modulation of the mesophases and the
achievement of a strong dielectric anisotropy (De) [2,6].
The design of polar liquid crystals becomes a particular
challenge, when the combination of high dielectric anisotropy
(De) with very low birefringence (Dn) is required. The main
application for this type of materials are LCDs for mobile
devices, such as cellular phones, personal digital assistants
(PDA) or video games. Here, the state of the art are materials
with a terminal trifluoromethyl group (2) or longer perfluoro-
alkyl groups [2]. In order to extend the range of De for liquid
crystals with very low birefringence we selected materials
with pentafluorosulfanyl vinyl (3), methylene (4), ethyl (5)
and difluoromethyl functions (6) as our target compounds
(Scheme 1).
Many LCD applications require a very high dielectric
anisotropy (De) of the liquid crystal, which is often difficult to
achieve with conventional fluorinated materials deriving their
molecular dipole moment (m) from the dipoles of several polar
* Corresponding author. Tel.: +81 46 286 2523; fax: +81 46 285 3838.
** Corresponding author. Tel.: +49 421 218 2493; fax: +49 421 218 4267.
E-mail addresses: peer_kirsch@merck.co.jp (P. Kirsch),
With few exceptions [11], so far mostly aromatic SF5
derivatives have been used as structural motifs in materials
¨
gvr@chemie.uni-bremen.de (G.-V. Roschenthaler).
0022-1139/$ – see front matter # 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2005.11.015

P. Kirsch et al. / Journal of Fluorine Chemistry 127 (2006) 610–619
611
Scheme 1. Liquid crystals 3–6 with a terminal pentafluorosulfanyl group are combining high dielectric anisotropy (De) with very low birefringence (Dn).
sciences, due to the commercial availability of several
pentafluorosulfanyl derivatives. Pentafluorosulfanyl arenes
are readily available from aromatic disulfides or sulfenyl
chlorides by oxidative fluorination with silver difluoride
[9,12] or – on a larger scale – by selective direct fluorination
[13]. The most commonly used access to pentafluorosulfanyl
alkanes and olefins is much less convenient, requiring the
addition of SF5Cl (bp ꢀ21 8C) or SF5Br (bp 3.1 8C) to
carbon–carbon double bonds [14]. Both reagents are highly
toxic gases [15], which are not commercially available on a
regular basis.
2. Results and discussion
With regard to their addition to carbon–carbon double
bonds, the pentafluorosulfanyl halides SF5Cl and SF5Br show a
similar but slightly higher reactivity than perfluoroalkyl
bromides and iodides. The uncatalyzed addition proceeds
from around room temperature upwards [14a–d], but the onset
of the exothermic reaction is sometimes unpredictable. A
smooth reaction of SF5Br can be induced by catalytic amounts
of triethyl borane at ꢀ20 8C [14e]. Application of this general
procedure to our liquid crystal precursors (7, 10, 13, 15 and 19)
Scheme 2. Syntheses of the liquid crystals 3, 5 and 12: (a) SF5Br, BEt3 (0.15 equiv.), n-heptane; ꢀ40 to ꢀ20 8C, 2 h (8a: 85%, 8b: 87%, 11: 83%). (b) KOH powder,
n-heptane; 35 8C, 18 h (3a: 74%, 3b: 84%, 12: 97%). (c) (1) tert-BuLi, n-pentane; ꢀ78 8C, 18 h; (2) EtOH; ꢀ60 8C to room temperature (16%, GC yield). If the
dehydrohalogenation of 8 is carried out at higher temperature (65 8C), significant quantities of the corresponding acetylene derivative 9 (upper box) are formed: 3a/9a:
66%/19%; 3b/9b: 69%/18%. The E-selectivity of the dehydrobromination can be explained by the elimination with the bulky liquid crystal (LC) and the SF5 groups in
the sterically favorable anti conformation (lower box).

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Scheme 3. Syntheses of the liquid crystals 4, 17 and 21: (a) SF5Br, BEt3 (0.15 equiv.), n-heptane; ꢀ40 to ꢀ20 8C (14a: 87%, 14b: 76%, 16: 87%, 20: 77%). (b) KOH
powder, n-heptane; 65 8C, 18 h (4a: 87%, 4b: 89%, 17: 96%, 21: 81%). (c) Ph3PCH3+Brꢀ, KOtBu, THF; 0 8C to room temperature, 3 h (75%).
furnished the corresponding addition products not only in good
yields but also with a surprisingly high regioselectivity. In all
cases the terminal b-bromo pentafluorosulfanyl alkanes were
obtained exclusively (Schemes 2 and 3). The dehydrohalo-
genation of the primary addition products 8 and 11 with
potassium hydroxide powder at 35 8C in n-heptane furnished
pure E-olefins. For the reaction of compounds 14, 16 and 20 an
elevated temperature of 65 8C was necessary. Interestingly,
when the dehydrohalogenation of 8 was tried also at 65 8C, the
formation of significant quantities of 9 was observed. This
unexpected reactivity indicates a pseudohalide-like reactivity
of the SF5 group, allowing a second dehydropentafluorosulfa-
nylation step from the primarily formed product 3. In the case
of the cholestane derivative 20 a 10:1 Z/E-isomer mixture of the
Scheme 4. Syntheses of the liquid crystal precursors 24 and 27: (a) CF2Br2, P(NMe2)3, dioxane/THF 4:1; 5 8C to room temperature, 18 h (23: 89%, 26: 64%). (b)
SF5Br, BEt3 (0.15 equiv.), n-heptane; ꢀ40 to ꢀ20 8C (24: 79%, 27: 82%). (c) KOtBu, THF, 35 8C (yield of 23 not determined).

P. Kirsch et al. / Journal of Fluorine Chemistry 127 (2006) 610–619
613
crude dehydrobromination product 21 was obtained. Crystal-
lization from ethanol/n-heptane 1:1 yielded pure Z-isomer.
Unexpectedly, all attempts to reduce any of the SF5 olefins to
the corresponding alkanes failed completely. Under the
conditions of catalytic hydrogenation neither with hetero-
geneous palladium, rhodium or platinum catalysts, nor with
Wilkonson’s catalyst any reactivity of 3a was observed.
Increasing the temperature to 100 8C and the hydrogen pressure
to 100 bar resulted only in reductive decomposition of the SF5
group. Also other reductive agents, acting by different
mechanisms, such as diimine [16], Hantztsch’s 1,4-dihydro-
pyridine [17], sodium borohydride [18] or triethyl silane/
trifluoroacetic acid [19] were tried without success. A possible
reason for this surprising lack of reactivity of the double bond is
the combination of steric bulkiness and the strongly negative
(ꢀI) inductive effect of the SF5 group.
Scheme 5. Proposed mechanism for the base-induced reversion of the SF5Br
addition in 24 ! 23 (bottom), compared to the dehydrobromination of 14 ! 4
(top).
product. A possible explanation for this unusual reaction path
is the combined inductive effect of the two b-fluorine atoms
and the SF5 substituent which is destabilizing any transient
positive charge at the b-carbon during the ‘‘normal’’ dehydro-
halogenation (Scheme 5). On the other hand, if the bromine is
attackedbyanucleophile,astabilizedtransientnegativechargeis
generated during the formal ‘‘Br-SF5’’ elimination.
As an alternative access to pentafluorosulfanyl ethyl
derivatives such as 5, the hydrodebromination of 8a was
attempted—also with limited success. Reducing agents such as
tri-n-butyl tin hydride [20], NaBH4 [21] and magnesium [22]
showed no reactivity at all. The use of zinc [23] and LiAlH4
[24] resulted only in the reduction of the SF5 group. n-Butyl
lithium [22] acted only as a base but did not cause bromine
lithium exchange. Finally, a partial success was achieved using
tert-butyl lithium [25] in n-pentane at ꢀ78 8C, followed by
addition of ethanol. Here, the formation of 16% of the reduced
target compound 5 was achieved, unfortunately accompanied
by 20% of starting material 8a and 48% of 7a as the
dehydropentafluorosulfanylation product of 8a (Scheme 2).
The addition of SF5Br to difluoromethylene derivatives [26]
23and26succeededsmoothlyasfortheotherolefins(Scheme4).
Also here, perfect regioselectivity was found. On the other hand,
all attempts for the subsequent dehydrobromination of 24 gave
either no reaction at all or – using KOtBu as a stronger base – the
difluoromethylenestartingmaterial23astheunexpectedreaction
Crystallization of the liquid crystal 3a from ethanol
furnished needles suitable for X-ray structure analysis [27]
(Fig. 1). Like for the aromatic SF5 derivatives [8b,28], the C–S–
Feq angle is with ca. 91.48 resp. ca. 93.98 larger than the 908
found for the basic system SF6. Therefore, the equatorial
fluorine atoms are – along with the axial fluorine – contributing
significantly to the molecular dipole moment (m) and thus also
to the dielectric anisotropy (De) of the liquid crystal [7]. The
packing of 3a at ꢀ100 8C shows a clear segregation of the
fluorophobic hydrocarbon moiety of the mesogenic core
structure and the fluorophilic SF5 groups into a layered
arrangement, possibly preforming the smectic phase observed
at higher temperatures.
The mesogenic properties [30] of all the newly synthesized
liquid crystals (Table 1) are quite typical for bicyclohexyl
Fig. 1. Crystal structure of the pentafluorosulfanyl vinyl substituted liquid crystal 3a [27,29]: the molecular unit (middle) and packing (bottom). Selected bond lengths
and angles: C–S 178.2(3) pm; S–Feq 158.3(2), 158.7(2), 158.7(2) and 158.8(2) pm; S–Fax 159.8(2) pm; C–S–Feq 91.318, 91.538, 93.838 and 94.108.

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P. Kirsch et al. / Journal of Fluorine Chemistry 127 (2006) 610–619
Table 1
The physical properties of the new SF5 substituted liquid crystals (3a/b, 4a/b, 12, 17, 21) in comparison to some of their CF3 analogues (1a/b, 2a/b, 28) [30]
No.
Phase sequence
TNI,virt
Devirt
Dnvirt
1a
1b
2a
2b
3a
3b
4a
4b
12
17
21
28
C 19 SH? (8) SB? 41 I
C 35 SG? (33) I
C 60 SB 61 I
C 59 N (57.2) I
C 51 SG? 65 I
C 58 SB 89 I
C 41 I
ꢀ44.4
ꢀ22.0
5.6
6.8
5.3
6.2a
7.9
10.5
9.9
6.3
5.8
10.1
4.3
–
0.0594
0.0510
0.0510a
0.0710
0.0704
0.0707
0.0633
0.0654
0.0641
0.0567
–
18.8
8.3
24.5
ꢀ93.8
ꢀ78.9
168.4
79.5
–
C 37 I
C 145 SB 173 N 194.1 I
C 68 SB 115 I
C 123 I
C 21 I
ꢀ78.9
3.4
0.0581
The phase transition temperatures and the virtual clearing points (TNI,virt) are cited in 8C. C: crystalline, SB: smectic B, SG: smectic G, N: nematic, I: isotropic. In the
cases marked by a question mark the mesophase assignment is not clear. Values in parentheses denote monotropic phase transitions.
a
Extrapolated from Merck mixture N.
systems,i.e., theyshowastrongtendencytoformsmecticphases.
Their birefringences (Dn) are rather low, although slightly higher
than for 1, which is due to the insertion of the polarizable vinyl
group. Compared to their trifluoromethyl analogues (2a/b and
28), the extrapolated clearing points (TNI,virt) of 3a/b and 4b are
several degrees higher. This effect has already been found for
aromatic SF5 systems [8b], and it is presumably caused by the
largersizeoftheSF5 groupcomparedtoCF3. Mostimportant, the
dielectric anisotropies (De) of 3a/b and 4b are about two to four
units higher than for 2a/b and 28. In particular, compound 12 has
a very favourable combination of high clearing point (TNI,virt),
high De and low Dn.
technology. The compounds show a remarkable chemical
stability, just like their trifluoromethyl analogues. The synthetic
key step – the addition of SF5Br to a carbon–carbon double
bond – was extended to 1,1-difluoroolefins, giving access to a
variety of potentially useful intermediates. The primary
pentafluorosulfanyl b-bromo alkanes as well as the correspond-
ing olefins were found to be surprisingly resistant towards all
kinds of reducing agents.
4. Experimental
4.1. General remarks
The SF5 methylene systems 4 and 17 have generally much
lower clearing temperatures and dielectric anisotropies than
their SF5 vinyl analogues. This is caused by the geometry of
these compounds, which have a kink in their otherwise
elongated shape, reducing the clearing point. Since the SF5
group is oriented in an oblique angle relative to the long
molecular axis, the director of the nematic phase and the
molecular dipole moment m are misaligned, which is reducing
De in spite of the high absolute value of m [7].
Caution: When handling SF5Br, adequate safety precautions
have to be taken. The reactive and highly toxic gas (bp 3.1 8C)
[15] should be handled only under a well-ventilated hood. Even
under normal ambient illumination photochemical dissociation
into bromine and extremely toxic S2F10 occurs, which is easily
visible by the emerging brown color. After completion of the
addition reaction the apparatus should be purged with nitrogen,
and the exhaust gas washed and hydrolyzed with KOH solution.
The SF5Br was purchased from Air Products & Chemicals. The
precursor 19 was synthesized according to Ref. [31], 26 in
analogy to Ref. [26].
The cholestane derivative 21 shows no mesophase in the neat
state, but it induces a cholesteric phase in a nematic host
mixture with a helical twisting power (HTP) of 7.7 mmꢀ1 [30].
3. Conclusion
4.2. Addition of SF5Br to olefins and difluoroolefins
Using the pentafluorosulfanyl group, a new class of liquid
crystals became available, combining high dielectric anisotropy
(De) with low birefringence (Dn). The pentafluorosulfanyl
group is so far the most polar terminal group for liquid crystals
which is still compatible with current active matrix LCD
4.2.1. Representative procedure for 4-[1-bromo-2-
(pentafluoro-l6-sulfanyl)ethyl]-40-propyl-1,10-bicyclohexyl
(8a)
A solution of 7a (7.03 g, 30.0 mmol) in n-heptane (120 mL)
was treated at a temperature between ꢀ40 and ꢀ30 8C with

P. Kirsch et al. / Journal of Fluorine Chemistry 127 (2006) 610–619
615
BEt3 (1 M in n-hexane; 4.5 mL, 4.5 mmol). Then SF5Br
(10.6 g, 51.2 mmol) was condensed into the reaction vessel.
The end of the reaction was indicated by a yellow or orange
coloration of the reaction mixture. The completion was
verified by the addition of a small quantity of BEt3 (1 M in n-
hexane; 0.4–0.5 mL): if no discoloration occurred, the
addition was considered complete. The mixture was stirred
for additional 2 h between ꢀ30 and ꢀ20 8C, then allowed to
warm up to room temperature. The mixture was poured into
ice-cold saturated aqueous NaHCO3 solution, and the organic
phase was separated and extracted with aqueous NaHCO3
until the color disappeared. The aqueous phase was extracted
three times with n-heptane. The combined organic extracts
were dried over Na2SO4 and evaporated to dryness. The crude
product was purified by chromatography (silica gel; n-
heptane) and subsequent crystallization from ethanol: yield
85% (98.1% purity by HPLC), colorless solid, mp 47–48 8C
(EtOH); IR (KBr): 2934 (s), 2850 (s), 1453 (m), 1432 (w),
1210 (vw), 1011 (vw), 978 (w), 956 (w), 937 (w), 909 (m),
875 (vs), 856 (vs), 814 (vs), 790 (m), 784 (m), 708 (vw), 638
(vw), 606 (vw), 587 (m), 571 (w), 566 (w), 559 cmꢀ1 (w); 1H
NMR (500 MHz, CDCl3, 303 K): d = 4.40 (td, J = 6.3 Hz,
J = 3.0 Hz, 1H), 4.12 (m, 2H), 1.90–1.53 (m, 9H), 1.50–0.55
(m, 18H); 13C NMR (75 MHz, CDCl3, 303 K): d = 75.9
(quint, J = 13.0 Hz), 53.2, 43.3, 43.2, 42.9, 39.8, 37.6, 33.5,
31.4, 30.1, 29.3, 29.1, 27.6, 20.0, 14.4; 19F NMR (235 MHz,
CDCl3, 300 K): d = 84.7 (m, 1F, SFax; overlapped by quintet
with J = 146.1 Hz), 67.0 (m, 4F, SFeq; overlapped by doublet
with J = 146.1 Hz); MS (EI, 70 eV, 180 8C): m/z (%) = 440
(5) [M+], 207 (5), 127 (11), 125 (78), 108 (5), 89 (6), 96 (100),
43 (51); HRMS for [M+](C17H30BrF5S): calcd. 440.1172,
found 440.1174.
(vs), 864 (s), 841 (s), 819 (vs), 725 (vw), 659 (vw), 618 (w), 594
1
(w), 581 (m), 571 (w), 563 cmꢀ1 (w); H NMR (500 MHz,
CDCl3, 303 K): d = 4.41 (td, J = 6.0 Hz, J = 2.9 Hz, 1H), 4.12
(m, 2H), 1.87–1.78 (m, 2H), 1.75–1.65 (m, 10H), 1.60 (mc,
1H), 1.40–1.23 (m, 4H), 1.22–0.80 (m, 24H); 13C NMR
(75 MHz, CDCl3, 303 K): d = 76.3 (quint, J = 13.0 Hz), 53.4,
43.9, 43.7, 40.2, 38.6, 38.1, 38.0, 35.1, 34.7, 34.1, 32.9, 32.7,
31.8, 30.1, 27.7, 20.4, 14.8; 19F NMR (235 MHz, CDCl3,
300 K): d = 84.1 (m, 1F, SFax; overlapped by quintet with
J = 146.4 Hz), 66.4 (m, 4F, SFeq; overlapped by doublet with
J = 146.4 Hz); MS (EI, 70 eV, 220 8C): m/z (%) = 550 (16)
[M+], 424 (8), 345 (5), 207 (6), 125 (70), 108 (6), 96 (79), 69
(100), 43 (10), 29 (7); HRMS for [M+](C25H44BrF5S): calcd.
550.22673, found 550.22670.
4.2.4. 4-Bromo-4-[(pentafluoro-l6-sulfanyl)methyl]-40-
propyl-1,10-bicyclohexyl (14a)
Yield 61% (97.2% purity by HPLC), colorless solid, mp 30–
31 8C (i-PrOH/EtOH 1:1); IR (KBr): 2949 (s), 2922 (s), 2851
(m), 1465 (w), 1441 (m), 1146 (w), 1066 (w), 1053 (w), 978
(w), 955 (w), 941 (w), 930 (m), 853 (vs), 821 (vs), 779 (w), 690
(w), 636 (s), 596 (m), 566 (w), 500 cmꢀ1 (w); 1H NMR
(500 MHz, CDCl3, 303 K): d = 4.21 (quint, J = 8.8 Hz, 2H),
2.40–2.09 (m, 2H), 1.87–1.51 (m, 10H), 1.35–0.84 (m, 14H);
13C NMR (75 MHz, CDCl3, 303 K): d = 83.3 (quint,
J = 11.0 Hz), 69.4, 42.9, 41.8, 39.7, 39.0, 37.6, 33.4, 30.0,
26.4, 20.0, 14.4; 19F NMR (235 MHz, CDCl3, 300 K): d = 84.4
(m, 1F, SFax; overlapped by quintet with J = 144.9 Hz), 70.1
(m, 4F, SFeq; overlapped by doublet with J = 145.9 Hz); MS
(EI, 70 eV, 200 8C): m/z (%) = 347 (27) [M+–Br], 219 (23), 125
(38), 111 (30), 95 (41), 83 (52), 79 (38), 69 (77), 43 (88), 41
(100); HRMS for [M+–Br](C16H28F5S): calcd. 347.1832, found
347.1837.
4.2.2. 4-[1-Bromo-2-(pentafluoro-l6-sulfanyl)ethyl]-40-
pentyl-1,10-bicyclohexyl (8b)
4.2.5. 4-Bromo-4-[(pentafluoro-l6-sulfanyl)methyl]-40-
pentyl-1,10-bicyclohexyl (14b)
Yield 87% (98.9% purity by HPLC), colorless solid, mp 38–
39 8C (EtOH); IR (KBr): 2925 (s), 2848 (s), 1468 (w), 1450 (w),
1416 (w), 1217 (vw), 1172 (vw), 1053 (vw), 917 (m), 878 (vs),
863 (s), 847 (s), 813 (vs), 790 (w), 712 (w), 629 (w), 600 (m),
573 (vw), 558 cmꢀ1 (w); 1H NMR (500 MHz, CDCl3, 303 K):
d = 4.41 (td, J = 6.3 Hz, J = 3.0 Hz, 1H), 4.12 (m, 2H), 1.85–
1.65 (m, 8H), 1.59 (mc, 1H), 1.38–1.18 (m, 8H), 1.17–0.80 (m,
14H); 13C NMR (75 MHz, CDCl3, 303 K): d = 75.9 (quint,
J = 13.0 Hz), 53.2, 43.3, 43.2, 42.9, 37.9, 37.4, 33.6, 32.2, 31.4,
30.1, 29.4, 29.2, 27.6, 26.6, 22.7, 14.1; 19F NMR (235 MHz,
CDCl3, 300 K): d = 81.1 (m, 1F, SFax; overlapped by quintet
with J = 146.2 Hz), 63.4 (m, 4F, SFeq; overlapped by doublet
with J = 146.1 Hz); MS (EI, 70 eV, 160 8C): m/z (%) = 468 (8)
[M+], 235 (10), 153 (65), 127 (8), 69 (100), 43 (21); HRMS for
[M+](C19H34BrF5S): calcd. 468.1485, found 468.1490.
Yield 76% (82.9% purity by HPLC), colorless solid, mp
35 8C (i-PrOH/EtOH 1:1); IR (KBr): 2956 (m), 2923 (s), 2851
(m), 1653 (vw), 1443 (w), 1060 (w), 929 (w), 871 (s), 845 (vs),
838 (vs), 823 (s), 725 (vw), 691 (vw), 637 (w), 596 (w), 563
1
(vw), 504 cmꢀ1 (vw); H NMR (500 MHz, CDCl3, 303 K):
d = 4.21 (quint, J = 8.9 Hz, 2H), 2.20–2.12 (m, 2H), 1.87–1.55
(m, 9H), 1.49–0.80 (m, 19H); 13C NMR (75 MHz, CDCl3,
303 K): d = 83.3 (quint, J = 10.9 Hz), 69.4, 42.8, 41.8, 39.0,
37.8, 37.4, 33.4, 32.2, 30.0, 26.6, 26.4, 22.7, 14.1; 19F NMR
(235 MHz, CDCl3, 300 K): d = 81.9 (m, 1F, SFax; overlapped
by quintet with J = 145.8 Hz), 67.6 (m, 4F, SFeq; overlapped by
doublet with J = 145.8 Hz); MS (EI, 70 eV, 180 8C): m/z
(%) = 375 (35) [M+–Br], 247 (14), 153 (17), 111 (30), 97 (96),
82 (100), 69 (50), 55 (58), 43 (33); HRMS for [M+–
Br](C18H32F5S): calcd. 375.2145, found 375.2151.
4.2.3. 4-{2-[4-[1-Bromo-2-(pentafluoro-l6-
sulfanyl)ethyl]cyclohexyl]ethyl}-40-propyl-1,10-
bicyclohexyl (11)
Yield 83% (98.4% purity by HPLC), colorless solid, mp
135 8C (i-PrOH/n-heptane 1:1); IR (KBr): 2917 (s), 2848 (s),
1447 (m), 1380 (vw), 1311 (vw), 1203 (vw), 1171 (vw), 888
4.2.6. 4-{2-[4-Bromo-4-[(pentafluoro-l6-
sulfanyl)methyl]cyclohexyl]ethyl}-40-propyl-1,10-
bicyclohexyl (16)
Yield 87% (97.2% purity by HPLC), colorless solid, mp
125 8C (i-PrOH/n-heptane 1:1); IR (KBr): 2952 (m), 2913 (s),

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P. Kirsch et al. / Journal of Fluorine Chemistry 127 (2006) 610–619
2847 (m), 1653 (vw), 1457 (w), 1444 (m), 957 (w), 944 (w),
915 (m), 866 (vs), 855 (m), 824 (m-s), 807 (s), 690 (vw), 636
(m), 598 (w), 564 cmꢀ1 (w); 1H NMR: d = 4.22 (quint,
J = 8.7 Hz, 2H), 2.23–2.01 (m, 3H), 1.89–1.65 (m, 11H),
1.54–1.46 (m, 2H), 1.37–0.80 (m, 24H); 13C NMR (75 MHz,
CDCl3, 303 K): d = 83.7 (quint, J = 10.7 Hz), 69.7, 43.9,
40.2, 39.2, 38.6, 38.1, 36.9, 35.0, 34.3, 34.1, 30.5, 29.8, 20.4,
14.8; 19F NMR: d = 85.7 (m, 1F, SFax; overlapped by quintet
with J = 145.9 Hz), 71.4 (m, 4F, SFeq; overlapped by doublet
with J = 145.9 Hz); MS (EI, 70 eV, 180 8C): m/z (%) = 538
(2) [M+], 457 (29), 330 (25), 220 (12), 203 (24), 125 (56),
111 (25), 108 (8), 95 (62), 89 (10), 83 (71), 69 (100), 55 (69),
43 (12); HRMS for [M+](C24H42BrF5S): calcd. 536.2111,
found 536.2100.
4.2.9. 3-Bromo-3-[difluoro(pentafluoro-l6-
sulfanyl)methyl]-5a-cholestane (27)
Yield 82% (99.0% purity by HPLC), colorless solid, mp
20
150 8C (i-PrOH/n-heptane 1:1); ½aꢁD = +24.58 (n-heptane,
0.0106 g mLꢀ1); IR (KBr): 2959 (s), 2936 (s), 2870 (m),
1468 (m), 1444 (w), 1387 (w), 1372 (w), 1198 (w), 1156 (m),
1133 (w), 975 (w), 956 (w), 929 (w), 877 (vs), 866 (vs), 836
(m), 795 (w), 766 (s), 730 (w), 670 (w), 595 (m), 571 cmꢀ1 (w);
1H NMR (500 MHz, CDCl3, 303 K): d = 2.10–2.05 (m, 2H),
1.90 (mc, 1H), 1.87–1.67 (m, 6H), 1.60–1.47 (m, 4H), 1.40–
1.21 (m, 8H), 1.17–0.95 (m, 10H), 0.91 (d, J = 6.5 Hz, 3H),
0.87 (d, J = 6.5 Hz, 3H), 0.86 (d, J = 6.6 Hz, 3H), 0.79 (s, 3H),
0.66 (s, 3H); 13C NMR (75 MHz, CDCl3, 303 K): d = 130.8,
56.4, 56.3, 53.6, 42.6, 41.2, 39.9, 39.5, 36.2, 35.8, 35.5, 35.4,
33.8, 31.7, 28.2, 28.0, 27.8, 24.2, 23.9, 22.8, 22.6, 21.0, 18.7,
12.4, 12.1; 19F NMR (235 MHz, CDCl3, 300 K): d = 70.6
(quint, J = 145.7 Hz, 1H, SFax), 46.4 (dt, J = 145.7,
J = 17.5 Hz, 4F, SFeq), ꢀ83.0 (br. s, 2F, CF2); MS (EI,
70 eV, 220 8C): m/z (%) = 626 (49) [M+], 611 (12), 471 (100),
457 (24), 420 (56), 405 (27), 265 (88), 169 (19), 156 (22), 123
(47), 109 (46), 81 (58), 69 (41), 55 (55), 43 (40); HRMS for
[M+](C28H46BrF7S): calcd. 626.2392, found 626.2393.
4.2.7. 3-Bromo-3-[(pentafluoro-l6-sulfanyl)methyl]-5a-
cholestane (20)
Yield 77% (98.8% purity by HPLC), colorless solid, mp
20
102 8C (i-PrOH/n-heptane 1:1); ½aꢁD = +27.28 (i-PrOH,
0.0106 g mLꢀ1); IR (KBr): 2960 (s), 2931 (s), 2870 (s),
1468 (m), 1444 (m), 1426 (w), 1386 (m), 1369 (m), 1334 (vw),
1307 (vw), 1293 (vw), 1244 (w), 1161 (m), 1117 (w), 1033 (w),
979 (m), 963 (m), 931 (m), 902 (m), 874 (vs), 849 (vs), 819 (vs),
788 (m), 732 (w), 699 (w), 641 (s), 624 (w), 600 (m), 572 (w),
4.3. Dehydrobromination of b-bromo pentafluorosulfanyl
alkanes
1
565 cmꢀ1 (w); H NMR (500 MHz, CDCl3, 303 K): d = 4.25
(quint, J = 8.6 Hz, 2H), 2.09–1.95 (m, 3H), 1.86–1.67 (m, 6H),
1.60–1.48 (m, 4H), 1.40–1.23 (m, 8H), 1.17–0.95 (m, 10H),
0.90 (d, J = 6.5 Hz, 3H), 0.89 (d, J = 6.5 Hz, 3H), 0.87 (d,
J = 6.5 Hz, 3H), 0.76 (s, 3H), 0.66 (s, 3H); 13C NMR (75 MHz,
CDCl3, 303 K): d = 82.9 (quint, J = 10.3 Hz), 71.0, 56.4, 56.3,
53.6, 42.7, 42.6, 41.2, 39.9, 39.5, 36.2, 35.8, 35.7, 35.4, 35.2,
35.0, 31.7, 28.3, 28.0, 27.8, 24.2, 23.9, 22.8, 22.6, 21.0, 18.7,
12.4, 12.1; 19F NMR (235 MHz, CDCl3, 300 K): d = 85.5 (m,
1F, SFax; overlapped by quintet with J = 145.8 Hz), 70.9 (m,
4F, SFeq; overlapped by doublet with J = 145.8 Hz); MS (EI,
70 eV, 200 8C): m/z (%) = 590 (76) [M+], 575 (18), 435 (100),
421 (20), 385 (9), 384 (32), 369 (25), 357 (13), 229 (51), 121
(47), 106 (50), 95 (87), 89 (8), 81 (71), 71 (29), 57 (62), 43 (97);
HRMS for [M+](C28H48BrF5S): calcd. 590.2580, found
590.2577.
4.3.1. Representative procedure for 4-[E-2-(pentafluoro-
l6-sulfanyl)vinyl]-40-propyl-1,10-bicyclohexyl (3a)
A solution of 8a (3.38 g, 7.66 mmol) in n-heptane (100 mL)
was treated with KOH powder (4.49 g, 80.0 mmol) and stirred
at 35 8C for 18 h. The KOH powder is filtered off, the solvent
evaporated to dryness and the crude product purified by
chromatography (silica gel; n-heptane) and subsequent crystal-
lization from ethanol: yield 74% (99.4% purity by HPLC),
colorless solid, mp 51 8C (EtOH), smectic G 65 8C, isotropic;
IR (KBr): 2952 (m), 2927 (s), 2851 (s), 1650 (w), 1443 (m),
1186 (w), 976 (m), 960 (m), 915 (s), 891 (vs), 867 (vs), 849–838
(vs), 797 (m), 739 (w), 717 (m), 649 (m), 629 (m), 596 (m), 572
(m), 561 cmꢀ1 (w); 1H NMR (500 MHz, CDCl3, 303 K):
d = 6.47–6.28 (m, 2H), 2.03 (mc, 1H), 1.84–1.67 (m, 8H), 1.34–
0.84 (m, 18H); 13C NMR (75 MHz, CDCl3, 303 K): d = 143.9,
139.1, 43.3, 42.6, 39.8, 39.6, 37.6, 33.5, 31.9, 30.0, 29.3, 20.0,
14.4; 19F NMR (235 MHz, CDCl3, 300 K): d = 84.4 (m, 1F,
SFax; overlapped by quintet with J = 149.9 Hz), 62.8 (m, 4F,
SFeq; overlapped by doublet with J = 149.9 Hz); MS (EI,
70 eV, 140 8C): m/z (%) = 360 (29) [M+], 317 (8), 276 (6), 262
(5), 123 (29), 109 (22), 95 (14), 83 (67), 69 (100), 55 (51), 41
(53); HRMS for [M+](C17H29F5S): calcd. 360.1910, found
360.1900.
4.2.8. 4-Bromo-4-[difluoro(pentafluoro-l6-
sulfanyl)methyl]-40-propyl-1,10-bicyclohexyl (24)
Yield 79% (93.3% purity by HPLC), colorless solid, mp 21–
22 8C; IR (KBr): 2956 (m), 2926 (s), 2852 (s), 1449 (m), 1379
(vw), 1258 (vw), 1202 (m), 1153 (m), 1130 (w), 1108 (w), 1086
(vw), 1054 (vw), 977 (vw), 877–860 (vs), 802 (s), 775 (m), 760
(s), 724 (vw), 670 (w), 596 (s), 574 cmꢀ1 (w); 1H NMR
(500 MHz, CDCl3, 303 K): d = 2.29–2.20 (m, 2H), 1.97–1.52
(m, 10H), 1.38–0.80 (m, 14H); 13C NMR (75 MHz, CDCl3,
303 K): d = 131.1, 97.3, 42.8, 41.8, 39.8, 37.6, 33.4, 31.0, 30.0,
25.2, 20.1, 14.4; 19F NMR (235 MHz, CDCl3, 300 K): d = 71.3
(quint, J = 145.9 Hz, 1F, SFax), 47.0 (dt, J = 145.9 Hz,
J = 17.6 Hz, 4F, SFeq), ꢀ83.0 (br. s, 2F, CF2); MS (EI,
70 eV, 180 8C): m/z (%) = 462 (1) [M+], 383 (6), 125 (92), 111
(20), 83 (65), 69 (100), 55 (36), 43 (15); HRMS for
[M+](C16H26BrF7S): calcd. 462.0827, found 462.0832.
For 3a, 3b and 12 the dehydrobromination was conducted at
35 8C, for 4, 17 and 21 at 65 8C.
4.3.2. 4-[E-2-(Pentafluoro-l6-sulfanyl)vinyl]-40-pentyl-
1,10-bicyclohexyl (3b)
Yield 84% (99.8% purity by HPLC), colorless solid, mp
58 8C (EtOH), smectic B 89 8C, isotropic; IR (KBr): 2920 (s),
2849 (s), 1655 (w), 1468 (m), 1443 (m), 1221 (vw), 977 (m),

P. Kirsch et al. / Journal of Fluorine Chemistry 127 (2006) 610–619
617
915 (s), 833 (vs), 824 (vs), 774 (w), 745 (m), 722 (w), 664 (vw),
651 (vw), 633 (m), 600 (m), 579 (m), 572 cmꢀ1 (w); 1H NMR
(500 MHz, CDCl3, 303 K): d = 6.46–6.29 (m, 2H), 2.02 (mc,
1H), 1.83–1.65 (m, 8H), 1.32–0.82 (m, 22H); 13C NMR
(75 MHz, CDCl3, 303 K): d = 143.9, 139.1, 43.3, 42.6, 39.6,
37.9, 37.4, 33.6, 32.2, 31.9, 30.0, 29.3, 26.6, 22.7, 14.1; 19F
NMR (235 MHz, CDCl3, 300 K): d = 85.8 (m, 1F, SFax;
overlapped by quintet with J = 149.9 Hz), 64.1 (m, 4F, SFeq;
overlapped by doublet with J = 149.9 Hz); MS (EI, 70 eV,
220 8C): m/z (%) = 388 (22) [M+], 317 (8), 276 (7), 262 (6), 151
(22), 109 (23), 97 (83), 83 (100), 69 (58), 55 (78), 41 (59);
HRMS for [M+](C19H33F5S): calcd. 388.2223, found
388.2210.
2850 (s), 1657 (m), 1468 (m), 1445 (s), 1382 (w), 1351 (w),
1167 (w), 1154 (w), 1138 (w), 929 (s), 904 (vs), 870 (vs), 847–
826 (vs), 782 (s), 726 (s), 678 (w), 647 (s), 598 (s), 573 (m),
1
566 cmꢀ1 (m); H NMR (500 MHz, CDCl3, 303 K): d = 6.13
(quint, J = 9.0 Hz, 1H), 3.08 (mc, 1H), 2.23–2.10 (m, 2H),
1.97–1.87 (m, 3H), 1.77–1.69 (m, 4H), 1.32–0.80 (m, 20H); 13
C
NMR (75 MHz, CDCl3, 303 K): d = 149.7, 132.5 (quint,
J = 17.2 Hz), 43.0, 42.9, 38.2, 37.8, 36.2, 33.9, 32.6, 31.8,
30.8, 30.5, 27.0, 23.1, 14.4; 19F NMR (235 MHz, CDCl3,
300 K): d = 84.5 (m, 1F, SFax; overlapped by quintet with
J = 149.5 Hz), 64.1 (dd, J = 149.5 Hz, J = 9.0 Hz, 4F, SFeq);
MS (EI, 70 eV, 180 8C): m/z (%) = 374 (81) [M+], 318 (5), 303
(12), 289 (7), 262 (8), 248 (5), 247 (11), 191 (7), 151 (32), 137
(12), 111 (19), 97 (79), 83 (100), 71 (17), 69 (55), 55 (66), 49
(19), 43 (28); HRMS for [M+](C18H31F5S): calcd. 374.2067,
found 374.2070.
4.3.3. 4-{2-[4-[E-2-(Pentafluoro-l6-
sulfanyl)vinyl]cyclohexyl]ethyl}-40-propyl-1,10-
bicyclohexyl (12)
Yield 97% (99.8% purity by HPLC), colorless solid, mp
145 8C (i-PrOH/n-heptane 1:1), smectic B 173 8C, nematic
194 8C, isotropic; IR (KBr): 2919 (s), 2849 (s), 1653 (w), 1448
(m), 1381 (w), 968 (m), 912 (s), 832 (vs), 795 (w), 746 (w), 722
4.3.6. 4-{2-[4-[(Pentafluoro-l6-
sulfanyl)methylene]cyclohexyl]ethyl}-40-propyl-1,10-
bicyclohexyl (17)
Yield 96% (99.4% purity by HPLC), colorless solid, mp
68 8C (i-PrOH/n-heptane 1:1), smectic B 115 8C, isotropic; IR
(KBr): 3017 (w), 2952 (s), 2923 (s), 2848 (s), 1658 (w), 1443
(m), 1435 (m), 1376 (w), 1222 (vw), 1158 (w), 1138 (vw), 960
(w), 937 (w), 926 (m), 884 (vs), 852 (s), 822 (vs), 787 (s), 722
(s), 675 (w), 644 (s), 597 (s), 573 (m), 568 (m) cmꢀ1; 1H NMR
(500 MHz, CDCl3, 303 K): d = 6.14 (quint, J = 8.9 Hz, 1H),
3.03 (mc, 1H), 2.22–2.10 (m, 2H), 1.96–1.89 (m, 3H), 1.75–
1.68 (m, 8H), 1.42 (mc, 1H), 1.32–0.80 (m, 25H); 13C NMR
(75 MHz, CDCl3, 303 K): d = 149.3, 132.2, 43.5, 39.9, 38.2,
37.7, 37.2, 35.5, 34.8, 34.3, 33.7, 33.4, 33.2, 30.1, 30.1, 29.9,
20.1, 14.4; 19F NMR (235 MHz, CDCl3, 300 K): d = 84.4 (m,
1F, SFax; overlapped by quintet with J = 149.6 Hz), 64.0 (dd,
J = 149.6 Hz, J = 8.9 Hz, 4F, SFeq); MS (EI, 70 eV, 240 8C): m/
z (%) = 456 (8) [M+], 330 (12), 329 (24), 203 (15), 191 (7), 125
(54), 96 (47), 83 (72), 69 (100), 55 (58); HRMS for
[M+](C24H41F5S): calcd. 456.2849, found 456.2855.
1
(w), 664 (vw), 650 (w), 609 (w), 600 (m), 570 cmꢀ1 (w); H
NMR (500 MHz, CDCl3, 303 K): d = 6.45–6.30 (m, 2H), 2.04
(mc, 1H), 1.82–1.68 (m, 12H), 1.32–1.26 (m, 2H), 1.40–0.80
(m, 26H); 13C NMR (75 MHz, CDCl3, 303 K): d = 143.9,
139.0, 43.5, 39.9, 39.6, 38.2, 37.7, 37.3, 34.7, 34.5, 33.7, 33.7,
32.5, 31.6, 30.1, 20.1, 14.4; 19F NMR (235 MHz, CDCl3,
300 K): d = 83.3 (m, 1F, SFax; overlapped by quintet with
J = 149.9 Hz), 61.6 (m, 4F, SFeq; overlapped by doublet with
J = 149.9 Hz); MS (EI, 70 eV, 220 8C): m/z (%) = 470 (30)
[M+], 345 (6), 220 (38), 205 (8), 191 (5), 125 (39), 109 (21), 96
(60), 83 (75), 69 (100), 55 (58), 40 (77); HRMS for
[M+](C25H43F5S): calcd. 470.3006, found 470.3012.
4.3.4. 4-[(Pentafluoro-l6-sulfanyl)methylene]-40-propyl-
1,10-bicyclohexyl (4a)
Yield 87% (99.8% purity by HPLC), colorless solid, mp
41 8C (i-PrOH/n-heptane 1:1); IR (KBr): 2955 (s), 2925 (s),
2850 (s), 1655 (m), 1465 (m), 1444 (s), 1430 (w), 975 (m), 929
(m), 900 (s), 841 (vs), 827 (vs), 790 (s), 782 (s), 726 (s), 648 (s),
597 (m), 572 (m), 566 cmꢀ1 (m); 1H NMR (500 MHz, CDCl3,
303 K): d = 6.13 (quint, J = 8.9 Hz, 1H), 3.08 (mc, 1H), 2.25–
2.09 (m, 2H), 1.99–1.85 (m, 3H), 1.77–1.69 (m, 4H), 1.35–0.79
(m, 16H); 13C NMR (75 MHz, CDCl3, 303 K): d = 149.7, 132.5
(quint, J = 17.3 Hz), 43.0, 42.9, 40.1, 37.9, 36.2, 33.8, 31.8,
30.8, 30.5, 20.4, 14.7; 19F NMR (235 MHz, CDCl3, 300 K):
d = 86.4 (m, 1F, SFax; overlapped by quintet with
J = 149.5 Hz), 66.0 (dd, J = 149.5 Hz, J = 8.9 Hz, 4F, SFeq);
MS (EI, 70 eV, 180 8C): m/z (%) = 346 (40) [M+], 303 (6), 219
(7), 123 (33), 103 (14), 95 (18), 83 (63), 79 (13), 69 (100), 55
(43), 41 (41); HRMS for [M+](C16H27F5S): calcd. 346.1754,
found 346.1756.
4.3.7. 3-[Z-(Pentafluoro-l6-sulfanyl)methylene]-5a-
cholestane (21)
Yield 81% (96.2% purity by HPLC), colorless solid, mp
20
123 8C (EtOH/n-heptane 1:1); ½aꢁD = +44.28 (n-heptane,
0.01016 g mLꢀ1); IR (KBr): 2950 (s), 2913 (s), 2866 (s),
1644 (w), 1469 (m), 1445 (m), 1384 (w), 1147 (w), 1033 (w),
929 (m), 879 (vs), 844 (s), 832 (vs), 794 (m), 778 (m), 723 (s),
1
642 (m), 627 (w), 594 (m), 575 (w), 568 cmꢀ1 (w); H NMR
(500 MHz, CDCl3, 303 K): d = 6.10 (quint, J = 8.6 Hz, 1H),
2.68 (mc, 1H), 2.32 (mc, 1H), 2.05 (mc, 1H), 1.98–1.78 (m,
4H), 1.68 (mc, 1H), 1.59–1.42 (m, 3H), 1.40–0.95 (m, 20H),
0.90 (s, 3H), 0.89 (s, 3H), 0.87 (d, J = 6.6 Hz, 3H), 0.85 (d,
J = 6.6 Hz, 3H), 0.66 (s, 3H); 13C NMR (75 MHz, CDCl3,
303 K): d = 149.5, 132.2 (quint, J = 17.0 Hz), 56.8, 56.7, 54.5,
47.4, 43.0, 40.3, 40.2, 39.9, 36.6, 36.3, 36.2, 35.8, 33.1, 32.3,
32.1, 29.3, 28.6, 28.4, 24.6, 24.2, 23.2, 22.9, 21.6, 19.1, 12.5,
12.3; 19F NMR (235 MHz, CDCl3, 300 K): d = 88.5 (m, 1F,
SFax; overlapped by quintet with J = 149.7 Hz), 68.0 (dd,
J = 149.7 Hz, J = 8.6 Hz, 4F, SFeq); MS (EI, 70 eV, 180 8C): m/
4.3.5. 4-[(Pentafluoro-l6-sulfanyl)methylene]-40-pentyl-
1,10-bicyclohexyl (4b)
Yield 89% (99.8% purity by HPLC), colorless solid, mp
37 8C (i-PrOH/n-heptane 1:1); IR (KBr): 2957 (s), 2919 (s),

618
P. Kirsch et al. / Journal of Fluorine Chemistry 127 (2006) 610–619
z (%) = 510 (80) [M+], 495 (16), 370 (10), 355 (100), 341 (18),
287 (14), 122 (21), 109 (23), 95 (30), 81 (27), 69 (23), 57 (21),
43 (27); HRMS for [M+](C28H47F5S): calcd. 510.3319, found
510.3331.
(b) D. Demus, G. Pelzl, Z. Chem. 21 (1981) 1–9;
(c) W.H. de Jeu, Physical Properties of Liquid Crystalline Materials,
Gordon & Breach, 1980.
[8] (a) P. Kirsch, A. Hahn, Eur. J. Org. Chem. (2005) 3095–3100;
P. Kirsch, M. Bremer, M. Heckmeier, K. Tarumi, Angew. Chem. 111
(1999) 2174–2178;
(b) P. Kirsch, M. Bremer, M. Heckmeier, K. Tarumi, Angew. Chem. Int.
Ed. Engl. 38 (1999) 1989–1992;
4.4. Hydrodebromination of 8a with tert-butyl lithium
P. Kirsch, M. Bremer, A. Taugerbeck, T. Wallmichrath, Angew. Chem. 113
(2001) 1528–1532;
A solution of 8a (1.48 g, 3.35 mmol) in n-pentane (30 mL)
was cooled to ꢀ78 8C. tert-Butyl Lithium (15% solution in n-
pentane; 4.3 mL, 6.8 mmol) was added dropwise, and the
mixture was stirred for 18 h between ꢀ78 and ꢀ60 8C. After
careful addition of ethanol (5 mL), the mixture was allowed to
warm up to room temperature and poured into ice water
(100 mL). The organic layer was separated and the aqueous
phase extracted three times with n-heptane. The combined
organic phases were dried over Na2SO4 and evaporated to
dryness. The composition of the crude product was determined
by GC–MS (column: Factor Four VF5 ms; temperature profile:
(c) P. Kirsch, M. Bremer, A. Taugerbeck, T. Wallmichrath, Angew. Chem.
Int. Ed. 40 (2001) 1480–1484;
(d) P. Kirsch, M. Bremer, M. Heckmeier, K. Tarumi, Mol. Cryst. Liq.
Cryst. 346 (2000) 29–33.
[9] (a) W.A. Sheppard, J. Am. Chem. Soc. 82 (1960) 4751–4752;
(b) W.A. Sheppard, J. Am. Chem. Soc. 84 (1962) 3064–3071;
(c) W.A. Sheppard, J. Am. Chem. Soc. 84 (1962) 3072–3076.
[10] D. Ku¨hne, Ph.D. Thesis, University of Bremen, Germany, 2005.
[11] (a) J.C. Hansen, P.M. Savu, US 5159105 (1992) (Chem. Abstr. 1992, 116,
58727);
(b) J.C. Hansen, P.M. Savu, US 5286352 (1992) (Chem. Abstr. 1992, 116,
58727).
(c) R. Winter, P.G. Nixon, G.L. Gard, D.G. Castner, N.R. Holcomb, Y.-H.
Hu, D.W. Grainger, Chem. Mater. 11 (1999) 3044;
100–320 8C at 8 8C minꢀ1; pressure: 1 bar; split: 50 mL minꢀ1
;
injector temperature: 280 8C; injected sample volume: 1 mL):
(d) R. Winter, P.G. Nixon, R.J. Terjeson, J. Mohtasham, N.R. Holcomb,
D.W. Grainger, D. Graham, D.G. Caster, G.L. Gard, J. Fluorine Chem. 115
(2002) 107;
4-Propyl-40-vinyl-1,10-bicyclohexyl (7a): tR = 13.1 min;
48% GC yield; MS (EI, 70 eV): m/z (%) = 234 (39) [M+],
205 (17), 150 (12), 136 (11), 123 (24), 109 (59), 95 (43), 81
(65), 69 (100), 55 (60), 41 (50), 29 (8), 27 (16).
4-[2-(Pentafluoro-l6-sulfanyl)ethyl]-40-propyl-1,10-bicyclo-
hexyl (5): tR = 16.6 min; 16% GC yield; MS (EI, 70 eV): m/z
(%) = 362 (11) [M+], 236 (9), 125 (83), 109 (14), 95 (10), 83
(63), 69 (100), 55 (32), 41 (19).
(e) R.W. Winter, R. Dodan, L. Holmes, G.L. Gard, J. Fluorine Chem. 125
(2004) 37–41;
(f) G. Kostov, B. Ameduri, T. Sergeeva, W.R. Dolbier Jr., R. Winter, G.L.
Gard, Macromolecules 38 (2005) 8316–8326.
[12] A.M. Sipyagin, C.P. Bateman, Y.-T. Tan, J.S. Thrasher, J. Fluorine Chem.
112 (2001) 287–295.
[13] (a) R.D. Chambers, M.P. Greenhall, J. Hutchinson, J.S. Moilliet, J.
Thomson, in: Proceedings of the 211th National Meeting of the American
Chemical Society, New Orleans, LA, March 24–26, American Chemical
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4-[1-Bromo-2-(pentafluoro-l6-sulfanyl)ethyl]-40-propyl-
1,10-bicyclohexyl (8a): tR = 19.6 min; 20% GC yield; MS see
above.
(b) M.P. Greenhall, 15th International Symposium on Fluorine Chemis-
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(c) R.D. Bowden, M.P. Greenhall, J.S. Moillet, J. Thomson, WO 97/
05106 (1997) (Chem. Abstr. 1997, 126, 199340);
Acknowledgements
(d) R.D. Bowden, M.P. Greenhall, J.S. Moillet, J. Thomson, US 5741935
(1997) (Chem. Abstr. 1997, 126, 199340).
We thank J. Haas and K. Altenburg for the physical
characterization of the liquid crystals. We also appreciate the
valuable advice of Dr. M. Bremer on computational methods.
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