Preparation of symmetrical and unsymmetrical monomers towards bridge trifluoromethylated poly(p-phenylenevinylene)

Article abstract of DOI:10.1016/j.jfluchem.2004.05.004

The preparation and identification of a series of trifluoromethylated and bis(trifluoromethylated) precursors and monomers for bridge substituted trifluoromethylated poly(p-phenylenevinylene) (PPV) is reported. These monomers were prepared in several steps from terephthaldicarboxaldehyde and they contain symmetrical and unsymmetrical combinations of leaving groups and/or polarizers, including chlorides, sulfoxides, sulphones, tosylates and S-methyl (and also O-ethyl) xanthates. The electron withdrawing effect of the trifluoromethyl group dominated the regioselectivity of substitution, thus allowing the convenient and selective formation of unsymmetrically substituted products in high yield.

Full text of DOI:10.1016/j.jfluchem.2004.05.004

Journal of Fluorine Chemistry 125 (2004) 1473–1480
Preparation of symmetrical and unsymmetrical monomers towards
bridge trifluoromethylated poly(p-phenylenevinylene)$
Alex J. Roche*, Anne D. Loyle, Jean-Pierre Pinto
Department of Chemistry, Rutgers, The State University of New Jersey, 315 Penn Street, Camden, NJ 08102-1411, USA
Received 23 April 2004; accepted 11 May 2004
Available online 1 July 2004
Abstract
The preparation and identification of a series of trifluoromethylated and bis(trifluoromethylated) precursors and monomers for bridge
substituted trifluoromethylated poly(p-phenylenevinylene) (PPV) is reported. These monomers were prepared in several steps from
terephthaldicarboxaldehyde and they contain symmetrical and unsymmetrical combinations of leaving groups and/or polarizers, including
chlorides, sulfoxides, sulphones, tosylates and S-methyl (and also O-ethyl) xanthates. The electron withdrawing effect of the trifluoromethyl
group dominated the regioselectivity of substitution, thus allowing the convenient and selective formation of unsymmetrically substituted
products in high yield.
# 2004 Elsevier B.V. All rights reserved.
Keywords: Trifluoromethyl; PPV; Monomer; Regioselective; Nucleophilic substitution
1. Introduction
preparation of the same conjugated polymer via different
precursor routes results in the formation of polymers with
similar chemical structures but different electrical properties
[1c]. An approach designed to minimize common draw-
backs of precursor routes (such as monomer and precursor
polymer instability, gel formation, solubility problems)
recently appeared utilizing unsymmetrical monomers bear-
ing a leaving group (chlorine) and a polarizer (alkyl sulf-
oxide) at opposite ends of the monomer, and those
monomers were reported to generate stable and soluble
precursor polymers [9] Scheme 1.
The properties of PPV can be fine tuned through the
incorporation of substituents into the polymer framework.
PPV’s with electron withdrawing groups (such as cyano)
have been calculated [10] and demonstrated [11,12] to
exhibit higher electron affinities and ionization potentials
and smaller band gaps relative to PPV. These changes allow
the fabrication of cheaper, more stable and more efficient
devices. Indeed such cyano bearing PPV’s exhibit impress-
ive photoluminescence efficiency (60%) and external effi-
ciency (4%) in a single layer electroluminescence device
[11]. Whilst there are several PPV derivatives that bear the
trifluoromethyl group on the aryl ring of PPV [13], the parent
polymers 2 and 3 with trifluoromethyl substitution on the
vinylene linkage are not described in the literature Fig. 1.
There are however two reported examples of PPV co-
polymers bearing a trifluoromethyl group on the ethylene
The preparation and study of poly(p-phenylenevinylene)
(PPV) 1, and its derivatives continues to be an intensively
active area of research, especially driven by their application
in polymer light emitting diodes (PLEDs), nanocomposites,
and other devices that require organic materials to conduct,
semi-conduct or laze [1]. There are many established meth-
ods of preparing PPVand its derivatives, and these have been
extensively reviewed [2], but the preferred method is known
as the ‘‘precursor polymer route’’. The monomer is poly-
merized under basic conditions to generate the precursor
polymer, which is processable (soluble), and a subsequent
thermal elimination step generates the conjugated polymer.
The original precursor polymer route reported by Wessling
et al. [3] used bis-sulfonium salts, and alternative variations
and modifications have been subsequently published
employing halogens [4], ethers [5], xanthates [1c,6], sul-
fones [7] and sulfoxides [8]. The precursor polymers bearing
these different leaving groups have varying solubilities and
stabilities, and undergo the final thermal elimination at
different temperatures. It has been demonstrated that the
$ Supplementary data associated with this article can be found at doi:
10.1016/j.jfluchem.2004.05.004.
* Corresponding author. Tel.: þ1-856-225-6166;
fax: þ1-856-225-6506.
E-mail address: alroche@crab.rutgers.edu (A.J. Roche).
0022-1139/$ – see front matter # 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2004.05.004

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A.J. Roche et al. / Journal of Fluorine Chemistry 125 (2004) 1473–1480
Fig. 2. Structural motif of desired monomers.
the trifluoromethylated aldehyde 7 by careful column chro-
matography, it was more convenient to expose the mixture of
products to LiAlH4 reduction, to produce a mixture of diols,
since this afforded a far easier chromatographic separation.
The extra trifluoromethyl group facilitated the faster elution
of 8 versus 9 from the silica gel column (1/1 ethyl acetate/
chloroform Rf 0.80 and 0.46). Use of two equivalents of CF3-
TMS to terephthaldicarboxaldehyde gave a 2:1.5 ratio of
8:7, whereas using 1 equivalent gave 8:7 in a 1:7 ratio. In
both cases, the corresponding diols 8 and 9 were separated
and isolated in combined yields of around 80% from ter-
ephthaldicarboxaldehyde Scheme 2.
Diols 8 and 9 were converted into the corresponding
dichlorides in standard fashion employing thionyl chloride
and pyridine. The products were formed in reasonable yield
(60–65%) and 10 and 11 could be separated by column
chromatography, although with this series of compounds, it
was always most practical to separate the compounds at the
diol stage.
Scheme 1. The precursor polymer route.
bridge; 4 has di-alkoxy substituents on alternating benzene
rings, and 5 contains a polyether spacer group [14].
Both were prepared by Wittig–Horner polycondensation,
and not via the precursor polymer route. The trifluoro-
methyl group was shown to impart enhanced stability to
these polymers and increased electron affinities. This
brought about an increase in internal device efficiency
of two orders of magnitude when 4 was used in a PPV-
based LED.
2. Results and discussion
In order to prepare the previously unreported bridge
substituted trifluoromethyl and bis(trifluoromethyl) PPV
polymers 2 and 3 via the precursor polymer route, com-
pounds of the general form 6 were required. It was slightly
surprising to find that such simple compounds are not
reported in the literature Fig. 2.
Our approach started with the nucleophilic addition of
trifluoromethyl [15] to either one or both aldehyde func-
tionalities of terephthaldicarboxaldehyde. Whilst it was
possible to separate the bis(trifluoromethylated) diol 8 from
For PPV and related systems, the chloro-precursor poly-
mer is often found to be insoluble in organic solvents, and
therefore unsuitable for thin film formation [16]. Indeed we
have found this to be the case in our preliminary polymer-
ization of 11 with potassium t-butoxide. To circumvent this
problem, it is common to use substituents that can enhance
solubility and also undergo thermal elimination to create a
new p bond, such as xanthates, sulfoxides and sulphones.
Towards this end, the substitution of the chlorine substitu-
ents was examined Scheme 3.
Fig. 1. Bridge trifluoromethylated PPV polymers and co-polymers.
Scheme 2.

A.J. Roche et al. / Journal of Fluorine Chemistry 125 (2004) 1473–1480
1475
Scheme 3.
When 11 was stirred at room temperature with 1.1
equivalents of O-ethyl xanthic acid salt, 12 was generated
in 86% isolated yield. However despite higher ratios of
nucleophile, elevated temperatures, high dielectric solvents
and extended reaction times, 12 was still the only observable
product; the chlorine at the -CF3 terminus remained stub-
bornly unaffected. Indeed analogous attempts to substitute
10 using forcing conditions such as refluxing trifluoroacetic
acid and/or Lewis acids proved unsuccessful. Similar sub-
stitution only at the non-trifluoromethylated terminus of 11
was also obtained in excellent yield using the anion from n-
octane thiol as nucleophile. The crude thio-ether products
were oxidized to produce sulfoxide 13 by using H2O2 with a
tellurium dioxide catalyst. Sulphone 14 was prepared by
oxidation of the corresponding sulfoxide, and also more
directly by the direct oxidation of crude thioether products
with mcpba [17] Scheme 3.
Scheme 5.
Ditosylates 17 and 18 were prepared in high isolated yield
from 8 and 9 respectively, using a standard protocol of
sodium hydride and tosyl chloride. Interestingly, we
1
observed that in the H NMR of 9, the –OH resonance at
the trifluoromethyl terminus appeared 1.5 ppm downfield of
the other –OH resonance (doublet, dH ¼ 5.7 ppm versus
triplet, dH ¼ 4.2 ppm). This shift is obviously caused by
the electron withdrawing trifluoromethyl group, and the
resultant acidifying influence was evident when less than
two equivalents of base were used in a transformation of 9 to
18. In this case, compound 22 was also formed. This isomer
was identified by the similarities of the NMR spectra with
the appropriate structural motifs of 9 and 18. None of the
1
Such observations are supported by a report that whilst 15
would not undergo nucleophilic substitution of chloride,
compound 16 would, with the latter case proceeding through
a quinine methide intermediate [18] Scheme 4. Indeed, the
strong electron withdrawing trifluoromethyl group (spþ
0.61) [19] has been shown to retard solvolysis of benzylic
tosylates by over six orders of magnitude [20], and thus our
mono-trifluoromethylated compounds are ideal systems for
generating monomers with an unsymmetrical arrangement
of leaving group and polarizer in both high selectivity and
high yield. Common drawbacks of unsymmetrical monomer
formation are problems with over-substitution, use of excess
substrate, tedious separations and recuperation of expensive
starting materials [21]. Conversely, our methods avoid such
shortcomings, and generally the syntheses only required
water/organic extraction to produce products of sufficient
purity for 13C analysis. Further purification was achieved
through column chromatography and all the monomers
reported here were found to be stable to chromatography
on silica gel.
other regio-isomer was detected by H or 19F NMR.
It was observed that 18 underwent substitution only at the
non-trifluoromethylated terminus, even with excess nucleo-
phile and elevated temperatures. As before, when n-octyl
thiolate was used as the nucleophile, the crude thio-ether
products were smoothly oxidized to the corresponding
sulfoxide 20 and sulphone 21 in high isolated yield.
Evidence of the regioselectivity in our processes was
1
immediately obvious from the 19F and H NMR spectra,
as illustrated in the transformation of 11 to 13. The 19F and
1H signals from the –CF3 substituted terminus remained
unchanged (dF ¼ ꢀ73 ppm, doublet and dH ¼ 5.1 ppm,
quartet), whilst the benzylic -CH2 resonance shifted from
dH ¼ 4.6 to 3.9 ppm. For 12, the connectivity of the xanthate
to the –CH2 terminus has been unambiguously confirmed by
the correlation of the benzylic –CH2 proton signal with the
xanthate carbon in a heteronuclear chemical shift correlation
3
(HETCOR, indirect JHꢀC ¼ 8 Hz) NMR experiment [24].
Our attempts to generate the corresponding triflates met
with complications. The reaction of either 8 or 9 with
sodium hydride followed by addition of triflic anhydride
only ever generated oligomeric compounds. This was also
true when two equivalents of pyridine were employed as
base, yet when pyridine was used as a solvent for the
transformation, products 23 and 24 were generated in high
yield. These products are presumably formed via pyridine
displacement of the initially formed triflate group. Whilst we
could prepare purified samples of 23 and 24 sufficient for
13C analysis (with only trace amounts of pyridinium triflate
as impurities) via repeated recrystallizations from water/
acetone (2/1, v/v), we were unable to prepare large yields of
analytically pure compounds. Moreover, upon standing for
The literature reports of the solvolysis and other substitu-
tions reactions of trifluoromethyl bearing benzylic tosylates
[20,22], mesylates and triflates [23] led us to examine the
preparation and substitution potential of some alternative
superior leaving groups Scheme 5.
Scheme 4.

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A.J. Roche et al. / Journal of Fluorine Chemistry 125 (2004) 1473–1480
are structurally similar to Pirkle’s alcohol [26] and espe-
cially the recently reported difunctional analogue [27].
Those compounds are widely used as chiral solvating agents
[28] since they are able to generate observable differences in
NMR spectra of enantiomers. No resolution of our diaster-
eomeric mixtures was attempted.
With these new monomers in hand, the polymerization
and subsequent thermal elimination are currently under
investigation. The mechanism of elimination, polymeriza-
tion and thermal elimination to introduce conjugation for
various precursor polymer routes is still an area of active
research, and this area was recently reviewed [29]. Our new
monomers will allow insight into the effect of the trifluor-
omethyl group(s) on these processes.
Scheme 6.
several days in aqueous base, the 19F NMR signal corre-
sponding to the trifluoromethyl groups of 23 and 24 gradu-
ally disappeared, and we observed the corresponding
1
liberation of fluoride ion, and also the H signal for the
CHCF3 changed from a quartet to a singlet (the rest of the
spectrum remaining essentially unchanged). We attribute
this to the hydrolysis of the trifluoromethyl group to car-
boxylic acid, with this process being greatly facilitated by
the proximate pyridinium group (Scheme 6).
We also found that pyridine would not displace the
tosylates in compound 17, nor would the di-pyridinium salt
23 react with nucleophiles such as chloride ion, xanthic acid
salt or octyl thiolate. Also, related attempts to generate a di-
triflate in situ in the presence of nucleophiles such as thiolate
or xanthic acid salts only ever generated at most trace
amounts of desired substitution products.
Whilst the incorporation of O-ethyl xanthate groups at
the –CF3 termini had frustrated us, we were able to prepare
compounds containing the corresponding S-methyl
xanthates. Reaction of the diols 8 and 9 with sodium
hydride, carbon disulfide and methyl iodide generated
25 and 26 in high yield. In 1999, Burn and co-workers
[25] were the first to report the successful use of S-methyl
xanthates in the preparation of an alkoxy-PPV derivative .
Indeed they reported that photoluminescence quantum
yields (PLQY) were always higher for their S-methyl
xanthate derived polymers versus their chlorine-derived
analogues Scheme 7.
3. Summary
A series of trifluoromethylated and bis(trifluoromethy-
lated) compounds were prepared and characterized, starting
from a commercially available starting material. The tri-
fluoromethyl substituent strongly discouraged nucleophilic
substitution of proximate leaving groups. This regioselec-
tivity was exploited and a variety of unsymmetrically sub-
stituted compounds were conveniently produced in high
yield via transformations at the non-trifluoromethylated
terminus. These compounds fit the criteria for monomers
to prepare the previously unreported PPV derivatives with
both one and two trifluoromethyl substituents, via the ‘‘pre-
cursor polymer route’’. The monomers contain a selection of
different leaving groups and polarizers, and this should
enable the preparation of polymers with a range of electronic
properties. Investigation into the polymerization and the
subsequent thermal elimination to introduce conjugation
is already underway.
4. Experimental section
It was notable that the 19F, 13C and 1H NMR of six of our
compounds revealed the presence of diastereomers. In the
cases of 8, 10, 18 and 25 this arises due to two chiral carbons,
whereas 13 and 20 contain a chiral carbon and an asym-
metric sulfoxide functionality. Such manifestations were
most obvious in the spectra for atoms proximate to the
centers of asymmetry, such as overlapping quartet patterns
in the H NMR for –CHCF3 signals, and the H and 13C
peaks of the methylene groups either side of the asymmetric
sulfoxide groups. Relatedly, compound 8 and its derivatives
All NMR spectra were obtained on a Varian Mercury Plus
300 MHz spectrometer with 5 mm ATB probe at ambient
1
temperature. All 19F, H and 13C NMR spectra were per-
formed in CDCl3 at 282, 300 and 75 MHz respectively,
except where indicated in the text. Chemical shifts for 19F,
1H and 13C spectra were determined relative to CFCl3
(0.0 ppm), residual CHCl3 (7.24 ppm) and CDCl3
(77.0 ppm) respectively. All products were white solids,
except where specified otherwise in the text. All reagents,
unless otherwise specified, were used as purchased from
Aldrich or Fisher. Column chromatography was performed
using chromatographic silica gel 200–425 mesh, as supplied
by Fisher. Melting points are uncorrected. Low-resolution
mass spectrometry was performed at the Center for
Advanced Food Technology, New Brunswick, NJ, and
high-resolution mass spectrometry was performed at the
University of Pennsylvania, Philadelphia, PA.
1
1
Scheme 7.

A.J. Roche et al. / Journal of Fluorine Chemistry 125 (2004) 1473–1480
1477
4.1. 1-(1-Hydroxy-2,2,2-trifluoroethyl)-4-
(hydroxymethyl)benzene 9 and 1,4-bis-(1-hydroxy-2,2,2-
trifluoroethyl)benzene 8
4.5. 1-(1-Chloro-2,2,2-trifluoroethyl)-4-
(chloromethyl)benzene 11
Diol 9 (20.00 g, 97.96 mmol) was dissolved in pyridine
(23 mL, 0.28 mol) at room temperature under an atmosphere
of dry nitrogen. Thionyl chloride (34 mL, 0.47 mol) was
added via syringe, and the mixture was brought to reflux for
a period of 24 h. The excess pyridine and thionyl chloride
were removed by distillation, and the resulting brown sludge
was absorbed on an equal volume of silica gel and column
chromatography produced 11 (Rf 0.45, 19/1 hexane/ether)
A
solution of terephthaldicarboxaldehyde (2.63 g,
19.61 mmol) in anhydrous THF (50 mL) was stirred and
cooled to 0 8C under an atmosphere of nitrogen. CF3-TMS
(5.58 g, 39.22 mmol) was added, and then tetrabutylammo-
nium fluoride (0.3 mL of 1.0 M solution in THF) was added
via syringe. The resulting yellow solution was left to warm
to room temperature for 13 h. Then ice (15 mL) was added,
followed by hydrochloric acid (50 mL, 0.5 M). Ether extrac-
tion followed by drying (MgSO4) and rotary evaporation
afforded a pale yellow solid shown by NMR to contain 8 and
7 in a 4:3 ratio.
1
(14.22 g, 60%). Pale yellow oil. H NMR d 7.50 (d, J ¼
8.0 Hz, 2H), 7.45 (d, J ¼ 8.0 Hz, 2H), 5.12 (q, J ¼ 6.8 Hz,
1H), 4.61 (s, 2H); 13C NMR d 138.2, 131.0, 127.9, 127.7,
122.1 (q, J ¼ 278.9 Hz), 57.1 (q, J ¼ 34.3 Hz), 44.2; 19F
NMR d ꢀ77.1 (d, J ¼ 6.6 Hz); MS (EIþ) m/z 242 (26) [Mþ],
207 (1 0 0).
4.2. 1-(1-Hydroxy-2,2,2-trifluoroethyl)-4-
(formyl)benzene 7
4.6. 1,4-Bis-(1-chloro-2,2,2-trifluoroethyl)benzene 10
1
(Rf 0.70 1/1 ethyl acetate/chloroform) H NMR d 10.04
(s, 1H), 7.94 (d, J ¼ 8.4 Hz, 2H), 7.75 (d, J ¼ 8.4 Hz, 2H),
6.11 (d, J ¼ 5.4 Hz, 1H), 5.36 (m, 1H); 19F NMR d ꢀ77.1 (d,
J ¼ 6.6 Hz). The crude reaction mixture was dissolved in
anhydrous ether (15 mL) and added dropwise to a stirred,
cooled (0 8C) solution of lithium aluminum hydride (1.00 g,
26.35 mmol) in anhydrous ether (20 mL) under an atmo-
sphere of dry nitrogen. The mixture was allowed to warm to
room temperature over a period of 3 h. Then ice (20 mL) was
added, along with sulphuric acid (8 mL of 40% solution).
After stirring for 1 h, ether extraction followed by drying
(MgSO4) and rotary evaporation gave a white solid that upon
column chromatography yielded 8 (Rf 0.80, 1/1 ethyl acet-
ate/chloroform) and 9 (Rf 0.46, 1/1 ethyl acetate/chloro-
form).
Using the same scale and procedure as for 11, diol 8 was
converted to 10 (Rf 0.46, 19/1 hexane/ether) (65%). Pale
yellow oil. 1H NMR d 7.56 (s, 4H), 5.15 (q, J ¼ 6.7 Hz, 2H);
13C NMR d 134.1, 129.2, 123.3 (q, J ¼ 278.5 Hz), 58.13 and
58.11 (diastereomer) (q, J ¼ 34.6 Hz); 19F NMR d ꢀ73.1 (d,
J ¼ 6.7 Hz); MS (EIþ) m/z 310 (35) [Mþ], 241 (1 0 0);
HRMS (CIþ) calculated for C10H6Cl2F6 [MH]þ 310.98290,
found 310.9841.
4.7. 1-(1-Chloro-2,2,2-trifluoroethyl)-4-
[ethoxy(thiocarbonyl)thiomethyl]benzene 12
Potassium O-ethyl xanthic acid salt (1.04 g, 6.49 mmol)
was added to a solution of 11 (1.00 g, 4.33 mmol) in
methanol (20 mL), and stirred at room temperature over-
night. Then saturated NaCl solution (20 mL) was added
along with dichloromethane (20 mL). After stirring for
25 min, extraction with dichloromethane, followed by dry-
ing (MgSO4), rotary evaporation and column chromatogra-
phy (Rf 0.39, 3/2 hexane/dichloromethane) gave 12 (1.22 g,
86%) colorless oil. 1H NMR d 7.42 (d, J ¼ 8.4 Hz, 2H), 7.37
(d, J ¼ 8.4 Hz, 2H), 5.11 (q, J ¼ 6.9 Hz, 1H), 4.63 (q, J ¼
7.2 Hz, 2H), 4.36 (s, 2H), 1.39 (t, J ¼ 7.2 Hz, 3H); 13C NMR
d 212.6, 137.1, 130.1, 128.2, 127.7, 122.1 (q, J ¼ 278.9 Hz),
69.2, 57.2 (q, J ¼ 34.3 Hz), 38.6, 12.7; 19F NMR d ꢀ73.1 (d,
J ¼ 6.9 Hz); HRMS (CIþ) calculated for C12H12OF3ClS2
327.99702, found 327.9981.
4.3. 1,4-Bis-(1-hydroxy-2,2,2-trifluoroethyl)benzene 8
(2.58 g, 48%) Mp ¼ 116–118 8C. (Literature [30] for
(R,R) diastereomer 78–80 8C). 1H NMR (CDCl3/d6-acetone
1/1) d 7.53 (s, 4H), 5.91 (d, 2H), 5.07 and 5.05 (diaster-
eomer) (m, 2H); 13C NMR (CDCl3/d6-acetone 1/1) d 71.7
and 71.6 (diastereomer) (q, J ¼ 31.5 Hz), 124.2 (q, J ¼
281.7 Hz), 127.2, 135.6; 19F NMR d ꢀ77.0 (d, J ¼ 6.6 Hz);
MS (EI) m/z 274 (15) [Mþ], 205 (1 0 0).
4.4. 1-(1-Hydroxy-2,2,2-trifluoroethyl)-4-
(hydroxymethyl)benzene 9
(1.45 g, 36%). Mp ¼ 92–94 8C 1H NMR (CDCl3/d6-
acetone 1/1) d 7.47 (d, J ¼ 8.0 Hz, 2H), 7.40 (d, J ¼
8.0 Hz, 2H), 5.67 (d, J ¼ 5.4 Hz, 1H), 5.03 (m, 1H), 4.78
(d, J ¼ 5.7 Hz, 2H), 4.17 (t, J ¼ 5.7 Hz, 1H); 13C NMR
(CDCl3/d6-acetone 1/1) d 141.9, 133.3, 126.8, 125.8, 124.1
(q, J ¼ 282.0 Hz), 71.3 (q, J ¼ 31.2 Hz), 63.4; 19F NMR d
ꢀ77.1 (d, J ¼ 6.6 Hz); MS (EIþ) m/z 206 (41) [Mþ], 137
(1 0 0).
4.8. 1-(1-Chloro-2,2,2-trifluoroethyl)-4-[(n-
octylsulfinyl)methyl]benzene 13
n-Octane thiol (0.95 g, 6.49 mmol) was stirred with
sodium t-butoxide (0.62 g, 6.49 mmol) in methanol
(50 mL) for 30 min at room temperature, and then a solution
of 11 (1.00 g, 4.33 mmol) in methanol (10 mL) was added.
After 1 h at room temperature tellurium dioxide (35 mg,

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A.J. Roche et al. / Journal of Fluorine Chemistry 125 (2004) 1473–1480
0.22 mmol) and hydrogen peroxide (1.26 mL of 35% solu-
tion) were added and the reaction was stirred for another
hour. Saturated sodium chloride solution (20 mL) was added
along with 20 mL of dichloromethane. After stirring for 1 h,
dichloromethane extraction followed by drying (MgSO4)
and rotary evaporation produced a solid residue that upon
column chromatography (Rf 0.53, 1/1 ether/chloroform)
yielded 13 (1.42 g, 89%). Mp ¼ 57–60 8C. 1H NMR d
7.47 (d, J ¼ 7.8 Hz, 2H), 7.32 (d, J ¼ 7.8 Hz, 2H), 5.11
(q, J ¼ 6.6 Hz, 1H), 3.95 and 3.93 (diastereomer) (d, J ¼
13.5 Hz, 2H), 2.58 (t, J ¼ 8.1 Hz, 2H), 1.76 (m, 2H), 1.40–
1.24 (m, 10H), 0.85 (t, J ¼ 5.1 Hz, 3H); 13C NMR d 131.2,
131.0, 129.2, 128.0, 122.1 (q, J ¼ 278.6 Hz), 57.1 (q, J ¼
34.3 Hz), 56.5 and 56.4 (diastereomer), 50.33 and 50.29
(diastereomer), 30.6, 28.1, 27.9, 27.7, 21.5, 21.4, 13.0; 19F
NMR d ꢀ73.1 (d, J ¼ 6.6 Hz); HRMS (CIþ) calculated for
C17H24OF3ClS [MH]þ 369.12668, found 369.1269.
solid, that upon chromatography (Rf 0.42, 2/1 ether/hexane)
afforded 18 (5.49 g, 88%). Mp ¼ 137–140 8C. 1H NMR d 7.75
(d, J ¼ 8.1 Hz, 2H), 7.62 (d, J ¼ 8.1 Hz, 2H), 7.31 (d, J ¼
8.1 Hz, 2H), 7.27 (d, J ¼ 8.1 Hz, 2H), 7.24 (d, J ¼ 8.1 Hz, 2H),
7.19 (d, J ¼ 8.1 Hz, 2H), 5.62. (q, J ¼ 6.3 Hz, 1H), 5.02 (s,
2H), 2.44 (s, 3H), 2.40 (s, 3H); 13C NMR d 145.5, 145.0, 135.5,
132.9, 132.6, 130.4, 129.8, 129.7, 128.4, 128.2, 127.8, 127.7,
121.9 (q, J ¼ 280.5 Hz), 77.4 (q, J ¼ 34.3 Hz), 70.8, 21.7, 21.6;
19F NMR d ꢀ76.7 (d, J ¼ 6.3 Hz); HRMS (ESI) calculated for
C23H21O6F3S2 [M þ Na]þ 537.06294, found 537.0646.
When the above reaction was performed with 1.5 equiva-
lents of sodium hydride, column chromatography of the
product mixture afforded 18 (Rf 0.42, 2/1 ether/hexane)
(3.06 g, 49%) and 1-(1-p-toluenesulphonyloxy-2,2,2-tri-
fluoroethyl)-4-(hydroxymethyl)benzene 22 (Rf 0.59, ether)
(1.40 g, 32%). Mp ¼ 79–81 8C. 1H NMR d 7.54 (d,
J ¼ 7.6 Hz, 2H), 7.19 (s, 4H), 7.11 (d, J ¼ 7.6 Hz, 2H),
5.55 (q, J ¼ 6.0 Hz, 1H), 4.55 (s, 2H), 2.29 (s, 3H); 13C
NMR d 145.3, 143.1, 132.8, 129.6, 128.8, 128.1, 127.8,
126.8, 122.1 (q, J ¼ 280.8 Hz), 77.7 (q, J ¼ 34.0þHz), 64.4,
21.6; 19F NMR d ꢀ76.0 (d, J ¼ 6.0 Hz); MS (CI ) m/z 359
(41) [MꢀH]þ, 343 (1 0 0); HRMS (ESI) calculated for
C16H-O4F3S [M þ Na]þ 383.05408, found 383.0514.
4.9. 1-(1-Chloro-2,2,2-trifluoroethyl)-4-[(n-
octylsulfonyl)methyl]benzene 14
A dichloromethane solution (5 mL) of 13 (0.18 g,
0.51 mmol) was cooled to 0 8C under an atmosphere of
dry nitrogen, and over a period of 15 min a solution of
mcpba (0.88 g, 5.07 mmol) in dichloromethane (15 mL) was
added. The solution was warmed to room temperature and
stirred for an additional hour. Then sodium hydroxide
(10 mL of 5% solution) was added, followed by 30 mL of
dichloromethane. Dichloromethane extraction, drying
(MgSO4) and rotary evaporation produced a white solid
residue that after column chromatography (Rf 0.41, 2/1
ether/hexane) afforded 14 (0.19 g, 94%). Mp ¼ 94–96 8C.
1H NMR d 7.51 (d, J ¼ 8.4 Hz, 2H), 7.43 (d, J ¼ 8.4 Hz,
2H), 5.13 (q, J ¼ 6.9 Hz, 1H), 4.21 (diastereomer) (d, J ¼
13.5 Hz, 2H), 2.58 (t, J ¼ 8.1 Hz, 2H), 1.76 (m, 2H), 1.40–
1.24 (m, 10H), 0.85 (t, J ¼ 5.1 Hz, 3H); 13C NMR d 131.2,
130.9, 129.2, 128.0, 122.0 (q, J ¼ 278.6 Hz), 57.1 (q, J ¼
34.3 Hz), 56.5 and 56.4 (diastereomer), 50.33 and 50.29
(diastereomer), 30.6, 28.0, 27.9, 27.7, 21.5, 21.4, 13.0; 19F
NMR d ꢀ73.1 (d, J ¼ 6.9 Hz); HRMS (CIþ) calculated for
C17H24O2F3ClS [MH]þ 385.1215, found 385.1203.
4.11. 1,4-Bis-(1-p-toluenesulphonyloxy-2,2,2-
trifluoroethyl)benzene 17
Using the same scale and procedure as for 18, bisdiol 9
was converted to 17 (Rf 0.47, 2/1 ether/hexane) (83%). Mp ¼
205–207 8C. 1H NMR d 7.49 and 7.47 diastereomer (d, J ¼
8.4 Hz, 4H), 7.13 and 7.11 diastereomer (s, 4H), 7.09 and
7.08 diastereomer (d, J ¼ 8.4 Hz, 4H), 5.57 and 5.55
diastereomer (q, J ¼ 6.3 Hz, 2H), 2.28 (s, 3H); 13C NMR
d 145.6, 132.57 and 132.52 diastereomer, 131.7 and 131.1
diastereomer, 129.63 and 129.61 diastereomer, 129.2,
127.72 and 127.67 diastereomer, 121.8 (q, J ¼ 280.8 Hz),
77.4 and 77.3 diastereomer (q, J ¼ 34.0 Hz), 21.6; 19F NMR
d ꢀ75.9 and ꢀ76.0 diastereomer (d, J ¼ 6.3 Hz); MS (EI) m/
z 582 (10) [Mþ], 91 (1 0 0); HRMS (ESI) calculated for
C24H20O6F6S2 [M þ Na]þ 605.05032, found 605.0529.
4.12. 1-(1-p-Toluenesulphonyloxy-2,2,2-trifluoroethyl)-4-
[ethoxy(thiocarbonyl)thiomethyl]benzene 19
4.10. 1-(1-p-Toluenesulphonyloxy-2,2,2-trifluoroethyl)-4-
[(p-toluenesulphonyloxy)methyl]benzene 18
Potassium O-ethyl xanthic acid salt (0.75 g, 4.69 mmol)
was added to a solution of 18 (2.00 g, 3.89 mmol) in
methanol (20 mL), and stirred at room temperature over-
night. Then saturated NaCl solution (20 mL) was added
along with dichloromethane (20 mL). After stirring for
20 min, extraction with dichloromethane, followed by dry-
ing (MgSO4), rotary evaporation and column chromatogra-
phy (Rf 0.55, 1/1 ether/hexane) gave 19 (1.61 g, 89%). Mp ¼
67–68 8C. 1H NMR d 7.56 (d, J ¼ 8.1 Hz, 2H), 7.21 (s, 4H),
7.14 (d, J ¼ 8.1 Hz, 2H), 5.64 (q, J ¼ 6.3 Hz, 1H), 4.62 (q, J
¼ 7.2 Hz, 2H), 4.29 (s, 2H), 2.35 (s, 3H), 1.38 (t, J ¼ 7.2 Hz,
3H); 13C NMR d 213.2, 145.3, 138.2, 132.6, 129.5, 129.0,
Under an atmosphere of dry nitrogen, a mineral oil dis-
persion of sodium hydride (1.02 g of 60 wt.%., 25.49 mmol)
was dissolved in anhydrous THF (40 mL) at room tempera-
ture. A solution of 9 (2.50 g, 12.14 mmol) in THF (80 mL)
was added dropwise to the stirred solution, and after 50 min a
solution of tosyl chloride (5.78 g, 30.35 mmol) in THF
(40 mL) was added dropwise. The resulting creamy yellow
mixture was warmed to reflux overnight. After cooling to
room temperature, ice (25 mL) was added, and this was
followed by ether extraction. The ether layers were combined,
dried (MgSO4) and rotary evaporated to yield a pale yellow

A.J. Roche et al. / Journal of Fluorine Chemistry 125 (2004) 1473–1480
1479
128.6, 128.1, 127.6, 122.0 (q, J ¼ 280.6 Hz), 77.7 (q, J ¼
4.15. 1-(1-Pyridinium-2,2,2-trifluoroethyl)-4-
[(pyridinium)methyl]benzene
bis(trifluoromethansulfonate) 24
34.4 Hz), 70.2, 39.6, 21.5, 13.7; 19F NMR d ꢀ75.9 (d, J ¼
6.3 Hz); HRMS (ESI) calculated for C19H19O4F3S3 [M þ
Na]þ 487.02953, found 487.0274.
Under an atmosphere of dry nitrogen a solution of diol 9
(0.21 g, 1.03 mmol) in pyridine (3 mL) was cooled to 0 8C.
After stirring for 1 h at this temperature, triflic anhydride
(1.67 g, 2.5 mmol) was added via syringe. The resulting
bright red solution was stirred and allowed to warm to room
temperature over a period of 4 h. Then ice (20 mL) was
added to the reaction. The solution was adjusted to neutral
pH and the aqueous layer was extracted with ether. The
aqueous layer was evaporated, was shown to contain 24 in
78% yield (based on a 19F NMR yield versus a known
amount of added trifluoroethanoic acid). The purity was
enhanced by several recrystallizations from 2:1 water/acet-
one. Mp > 275 8C. 1H NMR (D2O: acetone-d6 1/1) d 8.90 (d,
J ¼ 6.3 Hz, 2H), 8.78 (d, J ¼ 6.0 Hz, 2H), 8.60 (t, J ¼
6.6 Hz, 1H), 8.45 (t, J ¼ 6.6 Hz, 1H), 8.06 (t, J ¼ 7.2 Hz,
2H), 7.96 (t, J ¼ 6.9 Hz, 2H), 7.65 (t, J ¼ 7.8 Hz, 2H), 7.50
(t, J ¼ 7.8 Hz, 2H), 7.00 (q, J ¼ 7.2 Hz, 1H), 5.78 (s, 2H);
19F NMR (D2O: acetone-d6 1/1) d -69.1 (d, J ¼ 7.2 Hz, 3F),
ꢀ77.5 (s, 6F); MS (APCI:APþ) m/z 479 (1 0 0)
[C19H17F3N22þ.CF3SO3ꢀ]; (APꢀ) 149 (1 0 0) [CF3SO3ꢀ].
4.13. 1-(1-p-Toluenesulphonyloxy-2,2,2-trifluoroethyl)-4-
[(n-octylsulfinyl)methyl]benzene 20
n-Octane thiol (0.67 g, 4.55 mmol) was stirred with sodium
t-butoxide (0.44 g, 4.55 mmol) in methanol (20 mL) for
30 min at room temperature, and then a solution of 17
(1.95 g, 3.79 mmol) in methanol (15 mL) was added. After
stirring for 1 h at room temperature, tellurium dioxide (3 mg,
0.18 mmol) and hydrogen peroxide (1.2 mL of 10 M solution,
11.37 mmol) were added and stirred for another hour. Satu-
rated sodium chloride solution (20 mL) was added along with
20 mL of dichloromethane, and after stirring for 1 h, dichlor-
omethane extraction followed by drying (MgSO4) and rotary
evaporation produced a solid reside that upon column chro-
matography (Rf 0.50, 1/1 ether/chloroform) yielded 20
1
(1.70 g, 89%). Mp ¼ 95–97 8C. H NMR d 7.64 and 7.63
(d, J ¼ 8.1 Hz, 2H), 7.33 and 7.32 (d, J ¼ 8.1 Hz, 2H), 7.24
and 7.23 (d, J ¼ 8.1 Hz, 2H), 7.23 and 7.22 (d, J ¼ 8.1 Hz,
2H), 5.63 and 5.61 (q, J ¼ 6.3 Hz, 1H), 3.89 and 3.88 (s, 2H),
2.59 (t, J ¼ 7.6 Hz, 2H), 2.39 (s, 3H), 1.77 (m, 2H), 1.40–1.20
(m, 10H), 0.86 (m, 3H); 13C NMR d 145.5 and 145.4
diastereomer, 132.80 and 132.77 diastereomer, 132.67 and
132.62 diastereomer, 130.2, 129.9 and 129.8 diastereomer,
129.7, 128.5, 127.8, 122.0 (q, J ¼ 280.8 Hz), 77.5 and 77.4
diastereomer (q, J ¼ 34.3 Hz), 57.83 and 57.79 diastereomer,
31.8, 31.0, 29.2, 28.9, 22.7, 21.8, 14.1; 19F NMR d ꢀ75.8 (d, J
¼ 6.3 Hz); HRMS (ESI) calculated for C24H31O4F3S2 [M þ
Na]þ 527.15136, found 527.1498.
4.16. 1,4-Bis-(1-pyridinium-2,2,2-trifluoroethyl)benzene
bis(trifluoromethansulfonate) 23
Using the same scale and procedure as for 24, diol 8 was
converted to 23 (85% yield based on a 19F NMR yield versus
a known amount of added trifluoroethanoic acid). Mp >
1
275 8C. H NMR ((D2O: acetone-d6 1/1) d 9.25 (d, J ¼
6.0 Hz, 4H), 8.88 (t, J ¼ 6.6 Hz, 2H), 8.36 (t, J ¼ 6.9 Hz,
4H), 8.05 (s, 4H), 7.45 (q, J ¼ 6.9 Hz, 2H); 13C NMR (D2O:
acetone-d6 1/1) d 149.5, 145.3, 131.5, 130.5, 129.8, 122.7 (q,
J ¼ 283.4 Hz), 120.4 (q, J ¼ 280.6 Hz), 71.8 (q, J ¼
32.7 Hz); 19F NMR (D2O: acetone-d6 1/1) d ꢀ70.3 (d, J
¼ 6.9 Hz, 6F), ꢀ79.5 (s, 6F); MS (APCI:APþ) m/z 547 (31)
[C20H16F6N22þꢁCF3SO3ꢀ], 318 (1 0 0); (APꢀ) 149 (1 0 0)
[CF3SO3ꢀ].
4.14. 1-(1-p-Toluenesulphonyloxy-2,2,2-trifluoroethyl)-4-
[(n-octylsulfonyl)methyl]benzene 21
A dichloromethane solution (5 mL) of 20 (0.43 g,
0.85 mmol) was cooled to 0 8C under an atmosphere of
dry nitrogen, and over a period of 15 min a solution of
mcpba (0.15 g, 0.85 mmol) in dichloromethane (15 mL) was
added. The solution was warmed to room temperature and
stirred for an additional hour. Then sodium hydroxide (5 mL
of 5% solution) was added followed by 30 mL of dichlor-
omethane. Dichloromethane extraction, drying (MgSO4)
and rotary evaporation produced a solid residue that after
column chromatography (Rf 0.38, 3/1 ether/hexane)
4.17. 1-[1-(Methylthio)thiocarbonyloxy-2,2,2-trifluoroethyl]-
4-[methylthio(thiocarbonyl)oxymethyl]benzene 26
Under an atmosphere of dry nitrogen, a mineral oil
dispersion of sodium hydride (0.32 g of 60 wt.%,
7.88 mmol) was dissolved in anhydrous THF (10 mL) at
room temperature. A solution of 9 (0.65 g, 3.15 mmol) in
THF (10 mL) was added dropwise to the stirred solution,
and after 60 min carbon disulphide (1.22 g, 15.75 mmol)
was added via syringe. The mixture was stirred at room
temperature for 1 h and then methyl iodide (2.23 g,
15.75 mmol) was added via syringe and the reaction was
left to stir overnight. Afterwards ice/water (20 mL) was
added, followed by ether extraction. The ether layers were
combined, dried (MgSO4) and rotary evaporated to yield a
1
afforded 21 (0.39 g, 89%). Mp ¼ 93–95 8C. H NMR d
7.66 (d, J ¼ 8.4 Hz, 2H), 7.38 (s, 4H), 7.24 (d, J ¼ 8.4 Hz,
2H), 5.68 (q, J ¼ 6.3 Hz, 1H), 4.18 (s, 2H), 2.86 (t, J ¼
7.8 Hz, 2H), 2.42 (s, 3H), 1.82 (m, 2H), 1.54–1.10 (m, 10H),
0.87 (m, 3H); 13C NMR d 145.6, 132.7, 130.9, 130.6, 130.1,
129.8, 128.6, 127.8, 122.0 (q, J ¼ 280.8 Hz), 77.4 (q, J ¼
34.3 Hz), 58.7, 31.7, 29.1, 29.0, 28.5, 22.7, 22.0, 14.1; 19F
NMR d ꢀ75.9 (d, J ¼ 6.3 Hz); HRMS (ESI) calculated for
C24H31O5F3S2 [M þ Na]þ 543.14627, found 543.1448.

1480
A.J. Roche et al. / Journal of Fluorine Chemistry 125 (2004) 1473–1480
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solid residue that upon column chromatography (Rf 0.40, 9/1
1
hexane/ether) afforded 26 (0.98g, 81%). Colorless oil. H
NMR d 7.49 (d, J ¼ 8.0 Hz, 2H), 7.44 (d, J ¼ 8.0 Hz, 2H),
6.89 (q, J ¼ 6.9 Hz, 1H), 5.63 (s, 2H), 2.60 (s, 3H), 2.59 (s,
3H); 13C NMR d 215.3, 213.5, 136.6, 130.6, 128.5, 128.4,
122.6 (q, J ¼ 280.3 Hz), 78.3 (q, J ¼ 33.2 Hz), þ74.0, 19.6,
19.2; 19F NMR d ꢀ75.0 (d, J ¼ 6.9 Hz); MS (CI ) m/z 386
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4.18. 1,4-Bis-[1-(methylthio)thiocarbonyloxy-2,2,2-
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25 (Rf 0.50, 1/1 hexane/ether) (83%). Mp ¼ 70–74 8C. H
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13C NMR d 213.61 and 213.57 diastereomer, 132.3, 128.6,
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Acknowledgements
The National Science Foundation is gratefully acknowl-
edged for allowing the purchase of the NMR system through
a Major Research Instrumentation grant (NSF CHE-
0116145). Rutgers, The State University of New Jersey,
Campus at Camden, is also acknowledged for generously
providing startup funds.
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