Synthesis of novel fluorinated hexa-peri-hexabenzocoronenes

Article abstract of DOI:10.1055/s-2006-942550

The synthesis of several perfluoroalkylated hexabenzocoronene derivatives is described. The substituents range from linear semiperfluoroalkylated chains to branched perfluoroalkylated chains. Novel strategies were applied to overcome the low solubility an

Full text of DOI:10.1055/s-2006-942550

PAPER
2891
Synthesis of Novel Fluorinated Hexa-peri-hexabenzocoronenes
S
ynthesis of Fluor
l
inate
d
H
i
exa-pe
v
ri-hexabenz
i
ocoron
e
ene
s
r F. Aebischer,a Patrick Tondo,a Bassam Alameddine,b Titus A. Jenny*a
a
Chemistry Department, University of Fribourg, 9 chemin du Musée, 1700 Fribourg, Switzerland
Fax +41(26)3009739; E-mail: titus.jenny@unifr.ch
Chemistry Department, University of Balamand, P.O. Box 100, Tripoli, Lebanon
b
Received 5 May 2006; revised 24 May 2006
volves the cobalt-catalysed7 cyclotrimerisation of the
corresponding disubstituted tolane derivatives 3, yielding
hexaphenylbenzene moieties 2, which are subsequently
cyclodehydrogenated, under the Kovacic conditions,8 in
which the iron(III) chloride reagent acts as both Lewis
acid and oxidant (Scheme 1). The latter conditions, how-
ever, prevent the preparation of HBC derivatives in which
perfluorinated side chains are directly attached to the core.
An alkyl spacer of at least two carbons, or an ether or thio-
ether linkage is required to reduce the electron-withdraw-
ing effect of the perfluorinated side chain to an acceptable
level for the mild iron(III) chloride reagent to be success-
ful.5 The main task remains, therefore, in the preparation
of the symmetrically substituted tolane derivatives 3
(Scheme 1). Nonetheless, the drastic change in both reac-
tivity and solubility of highly fluorinated derivatives did
not allow the application of the conditions already report-
ed in the literature9 to the preparation of alkylated tolane
derivatives. The Kumada cross-coupling of a bis-bromi-
nated tolane with perfluoroalkyl Grignard intermediates,
for example, requires up to one week of reaction time and
yields the desired tolane only in unreliable and at best very
moderate yields,5 whereas for regular alkyl Grignard spe-
cies the reaction works without difficulties in a short time
and in acceptable yields.9
Abstract: The synthesis of several perfluoroalkylated hexabenzo-
coronene derivatives is described. The substituents range from lin-
ear semiperfluoroalkylated chains to branched perfluoroalkylated
chains. Novel strategies were applied to overcome the low solubili-
ty and the low reactivity of such chains.
Key words: coronenes, tolanes, perfluoroalkyl substituents, cross-
coupling, cyclodehydrogenation
Polycondensed aromatic hydrocarbons (PAHs) represent
a widely investigated class of aromatic compounds and
have been extensively studied over the past decades.1
Hexa-peri-hexabenzocoronene (HBC), an all-benzoid
PAH containing thirteen fused benzene rings, possesses
high thermal and chemical stability. It is also known to
self-assemble into highly ordered architectures,2 render-
ing the HBC moiety a candidate of high potential for ap-
plications in plastic electronics. Many functionalised
HBCs, either with extended conjugated structures, or with
alkyl groups on their periphery, have been prepared,3 but
only few bearing perfluoroalkylated side chains have been
reported.4,5 Those highly fluorinated side chains are ex-
pected to clad the HBC molecule with a Teflon-like man-
tle that reduces the tendency for any lateral aggregation.5
We report herein the synthesis of three new HBC deriva-
tives bearing linear and branched fluorinated side chains
(Figure 1).
A better way to prepare perfluoroalkylated tolane deriva-
tives consists therefore of synthesising first the halogenat-
ed precursors 5a–c (Schemes 2 and 3), as these
compounds are highly soluble in common organic sol-
The best strategy for the synthesis of symmetrically sub-
stituted hexa-peri-hexabenzocoronene6 derivatives 1 in-
R
R
R
R
R
R
R
R
R
R
R
R
R
R
Scheme 1 Retrosynthesis3 showing strategic bond disconnection for the preparation of hexa-peri-hexabenzocoronenes
SYNTHESIS 2006, No. 17, pp 2891–2896
x
x.
x
x
.
2
0
0
6
Advanced online publication: 15.08.2006
DOI: 10.1055/s-2006-942550; Art ID: Z09406SS
© Georg Thieme Verlag Stuttgart · New York

2892
O. F. Aebischer et al.
PAPER
R
tions, only the iodine of the side chain of 6 reacts, without
debromination of the aromatic core occurring. Finally,
bromobenzene 7 was converted into the more reactive io-
dobenzene 5b by a halogen-exchange13 reaction. Com-
pound 5b was isolated in 40% overall yield for the three
steps and in high purity after silica gel column chromatog-
raphy.
R
R
1a: R = (CH2)2(CF2)6F
1b: R = (CH2)4(CF2)6F
1c: R = (CH2)3CH[CH2(CF2)6F]2
The preparation of precursor 5c started with the Kumada
cross-coupling of the known fluorinated iodoalkene 814
with allylmagnesium bromide. The coupling only suc-
ceeded when the Grignard derivative was added very
slowly (over several hours) at 0 °C; otherwise, many side
products formed. The Heck reaction between fluorinated
alkene 9 and benzenediazonium 10 proved to be a chal-
lenge. Coupling was attempted in the presence of palladi-
um(II) acetate and methanol, but no product formed at all.
Fortunately, the coupling was finally achieved when pal-
ladium(II) acetate, calcium carbonate, and a methanol–
tetrahydrofuran mixture (3:1) was used at 50 °C. Purifica-
tion of the crude product by column chromatography over
silica gel afforded styrene derivative 11 as a colourless oil
in moderate yield. Hydrogenation was achieved under
mild conditions with the use of a rhodium–carbon cata-
lyst,11 to prevent the dehalogenation of the aromatic core.
Finally, compound 5c was isolated as a colourless liquid
in 34% isolated overall yield.
R
R
R
Figure 1 Hexa-peri-hexabenzocoronene target molecules
vents, allowing for their preparation in high purity. The
tolane derivatives 3a–c are then obtained in a one-pot
Sonogashira reaction,10 as white, sparingly soluble com-
pounds (Scheme 4).
Precursor 5a is already described in the literature,11
whereas precursors 5b and 5c are, to our knowledge, new
derivatives and represent very interesting fluorinated
building blocks.
For the synthesis of compound 5b (Scheme 2), 1-bromo-
4-but-3-enylbenzene (4) was first coupled with perfluoro-
hexyl iodide in a radical reaction. Sodium metabisulfite
was added to temper the reaction and to reduce the amount
of side products.12 Of all tested dehalogenation methods,
the use of lithium aluminum hydride was best for removal
of the iodine of the side chain of 6. Under these condi-
The most efficient way to convert an aromatic halide into
a tolane derivative involves a Sonogashira coupling.
Many different conditions are proposed in literature, but
Rf6I, Na2S2O5 30%
AIBN, 80 °C
Br
Br
I
98%
Rf6
4
6
LiAlH4, THF,
r.t.
Ni, KI, I2, DMF,
150 °C
I
Br
77%
83%
Rf6
Rf6
5b
7
Rf6 = C6F13
Scheme 2 Three-step synthesis of fluoroalkyl-substituted iodobenzene precursor 5b
MgBr
Rf6
Rf6
Rf6
Rf6
Pd(dppf)Cl2⋅CH2Cl2,
THF, 0 °C to r.t.
I
9
85%
8
Rf6
Rf6
Rf6
Rf6
N2BF4
9, Pd(OAc)2,
MeOH–THF (3:1),
CaCO3, 50 °C
Rh/C, H2 (60 bar),
pentane, r.t.
51%
98%
Br 10
11
5c
Br
Br
Scheme 3 Synthesis of fluoroalkyl-substituted bromobenzene precursor 5c by Kumada and Heck coupling
Synthesis 2006, No. 17, 2891–2896 © Thieme Stuttgart · New York

PAPER
Synthesis of Fluorinated Hexa-peri-hexabenzocoronenes
2893
PdCl2(PPh2), CuI, DBU
benzene, H2O, TMSC≡CH, r.t.
R
R
X
R
R = (CH2)2(CF2)6F, X = I (5a)
R = (CH2)4(CF2)6F, X = I (5b)
R = (CH2)2(CF2)6F (33%) (3a)
R = (CH2)4(CF2)6F (44%) (3b)
R = (CH2)3CH[CH2(CF2)6F]2, X = Br (5c)
R = (CH2)3CH[CH2(CF2)6F]2 (47%) (3c)
Scheme 4 Sonogashira one-pot coupling of fluoroalkylated halobenzenes with (trimethylsilyl)acetylene to yield tolane derivatives 3a–3c
most of them proceed stepwise, starting with the coupling drogen chloride, to yield the HBC derivatives 1a–c in fair
of the appropriate halobenzene precursor with (trimethyl- to good yields (45–70%) (Scheme 5). Final purification
silyl)acetylene, followed by deprotection of the trimethyl- was by recrystallisation from benzotrifluoride, hexafluo-
silyl group and, finally, by coupling this product with the robenzene, and diethyl ether.
second halobenzene. In our case, however, this approach
failed at the deprotection stage for solubility reasons. For-
In conclusion, three new symmetrically substituted hexa-
peri-hexabenzocoronenes bearing linear or branched par-
tially fluorinated alkyl chains in their periphery were pre-
pared and characterised. These HBC derivatives 1a–c are
tunately, two methods were found to perform the coupling
in a one-pot reaction. The first15 uses a constant stream of
acetylene passing through the reaction mixture at 80 °C.
potential candidates in plastic electronics, while their pre-
As the obtained yields were generally low, a second meth-
cursors are new, interesting partially fluorinated building
od was applied, in which (trimethylsilyl)acetylene10 was
blocks.
used instead. Despite the problems encountered in the
stepwise procedure, the highly fluorinated precursors 5a–
c yielded the tolane derivatives 3a–c, although in moder-
ate yields owing to their difficult purification: linear per-
All reagents and solvents were purchased from commercial sources
and used without further purification. THF and CH2Cl2 were dried
and deoxygenated by the Grubbs method.16 All reactions were per-
fluoroalkylated tolane derivatives 3a and 3b are only
slightly soluble in common organic solvents, and were pu-
rified by recrystallisation and filtration over basic alumi-
num oxide. Nevertheless, the method avoids the
formation of homocoupled products, normally occurring
in one-pot procedures owing to the very low solubility of
the alkynylated intermediates. It has to be noted that even
minor admixtures of homocoupled products totally pre-
vent the subsequent cyclotrimerisation reaction from oc-
curring and that, in the case of the perfluorinated side
chains, these byproducts cannot be removed by chroma-
tography.
Cyclotrimerisation7 of all tolane derivatives 3a–c
(Scheme 5) was achieved in high yield, provided that they
were of high purity. Finally, cyclodehydrogenation8 was
performed in the presence of a large excess of iron(III)
chloride (typically 20- to 60-fold) in nitromethane, and
under a constant stream of argon to remove the formed hy-
formed under inert atmosphere (N2 or Ar). 1H NMR and 13C NMR
spectra were recorded on a Bruker DPX 360 or a Bruker DRX 500
spectrometer, using CDCl3 or hexafluorobenzene as solvent. Chem-
ical shifts (d) are reported in ppm, and coupling constants (J) are
given in Hz. Mass spectra were recorded on a Finnigan Thermo
Quest GC/MS Voyager spectrometer or a Bruker 4.7 T BioAPEX II
FT/ICR spectrometer. Analytical TLC was performed on Merck
Kieselgel 60 F254 pre-coated glass plates and visualised by spray-
ing with a KMnO4 soln.
1-Bromo-4-(5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluoro-3-iodode-
cyl)benzene (6)
Perfluorohexyl iodide (2.6 g, 5.86 mmol) was syringed into a round-
bottomed flask equipped with a reflux condenser and heated to
50 °C. After injection of a 30% aq soln of Na2S2O5 (1 mL), followed
by the addition of AIBN (19 mg, 0.11 mmol) and 4 (1.2 g, 5.68
mmol), the mixture was heated to 80 °C for 4 h. H2O (20 mL) was
then added and the product was extracted with CH2Cl2 (3 × 50 mL).
The combined organic phases were washed with H2O (3 × 50 mL),
dried (Na2SO4), filtered, and evaporated; this afforded the title com-
pound as a colourless oil.
R
R
R
R
R
R
R
R
R
R
R
Co2(CO)8,
dioxane, 110 °C
FeCl3, CH3NO2,
CH2Cl2, 40 °C
R
R = (CH2)2(CF2)6F (82%) (2a)
R = (CH2)4(CF2)6F (90%) (2b)
R = (CH2)3CH[CH2(CF2)6F]2 (95%) (2c)
R = (CH2)2(CF2)6F (70%) (1a)
R = (CH2)4(CF2)6F (70%) (1b)
R = (CH2)3CH[CH2(CF2)6F]2 (67%) (1c)
R
R
3a–c
Scheme 5 Trimerisation and cyclodehydrogenation of tolanes yielding the desired hexa-peri-hexabenzocoronene derivatives 1a–c
Synthesis 2006, No. 17, 2891–2896 © Thieme Stuttgart · New York

2894
O. F. Aebischer et al.
PAPER
Yield: 3.67 g (98%); Rf = 0.63 (pentane).
as solvent. After evaporation of pentane, the title compound was ob-
tained as a colourless oil.
1H NMR (360 MHz, CDCl3): d = 7.42 (d, J = 8.2 Hz, 2 H, Ar), 7.19
(d, J = 8.2 Hz, 2 H, Ar), 4.23 (tt, J = 8.6, 5.0 Hz, 1 H, CHI), 2.48–
3.04 (m, 4 H, CH2), 2.00–2.17 (m, 2 H, CH2).
13C NMR (90.55 MHz, CDCl3): d = 138.78, 131.70, 130.24,
107.56–121.07 (m, Rf6), 120.21, 41.69, 41.73 (t, J = 21.1 Hz),
41.39, 35.13, 19.71.
Yield: 3.79 g (85%); Rf = 0.86 (pentane–Et2O, 4:1).
1H NMR (360 MHz, CDCl3): d = 5.72 (ddt, J = 17.3, 10.0, 6.8 Hz,
1 H, CH), 5.20 (d, J = 17.3 Hz, 1 H, CH2), 5.15 (d, J = 10.0 Hz, 1
H, CH2), 2.55 (sept, J = 6.8 Hz, 1 H, CH), 2.34 (t, J = 6.8 Hz, 2 H,
CH2), 2.13–2.27 (m, 4 H, CH2).
MS (EI, 70 eV): m/z (%) = 656.9 (5) [M+], 529.6 (13), 170.8 (100),
116.9 (44), 89.9 (75).
13C NMR (90.55 MHz, CDCl3): d = 133.5, 119.32, 105.25–122.33
(m, Rf6), 38.80, 33.60 (t, J = 21.1 Hz), 24.94.
MS (EI, 70 eV): m/z (%) = 721.2 (2) [M+], 378.3 (100).
1-Bromo-4-(5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorodecyl)ben-
zene (7)
1-Bromo-4-[6,6,7,7,8,8,9,9,10,10,11,11,11-tridecafluoro-4-
(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)undec-1-enyl]ben-
zene (11)
To a slurry of LAH (574 mg, 15.1 mmol) in THF (5 mL) was added
6 (5.0 g, 7.56 mmol) in THF (10 mL). After 3 h of reaction at r.t.,
the mixture was quenched by the addition of H2O (5 mL), 1 M
NaOH (5 mL), and H2O again (15 mL). The suspension was filtered
and washed exhaustively with Et2O (5 × 100 mL). The organic
phase was separated, washed with H2O (3 × 30 mL), dried
(Na2SO4), filtered, and evaporated. Purification by column chroma-
tography (silica gel, pentane) afforded the title compound as a co-
lourless oil.
To a suspension of 10 (5.4 g, 20 mmol), Pd(OAc)2 (90 mg, 0.4
mmol), and CaCO3 (2 g, 20 mmol) in MeOH (12 mL) was added 9
(14.4 g, 20 mmol) in THF (36 mL). The mixture was heated to
50 °C and stirred for 44 h. Removal of all volatiles yielded a crude
brown solid, which was suspended in pentane and filtered over a
plug of silica gel under reduced pressure with pentane as eluent.
Evaporation of the pentane afforded the crude reaction product,
which was purified by column chromatography (silica gel, pen-
tane). Evaporation of pentane from the combined fractions yielded
the title compound as a colourless oil.
Yield: 3.4 g (77%); Rf = 0.63 (pentane).
1H NMR (360 MHz, CDCl3): d = 7.41 (d, J = 8.2 Hz, 2 H, Ar), 7.05
(d, J = 8.2 Hz, 2 H, Ar), 2.61 (t, J = 7.0 Hz, 2 H, CH2), 2.01–2.15
(m, 2 H, CH2), 1.61–1.73 (m, 4 H, CH2).
Yield: 8.98 g (51%); Rf = 0.55 (pentane).
13C NMR (90.55 MHz, CDCl3): d = 140.55, 131.49, 130.08, 119.73,
108.07–121.99 (m, Rf6), 34.94, 30.69, 30.69 (t, J = 22.5 Hz), 19.75
(t, J = 3.6 Hz).
1H NMR (360 MHz, CDCl3): d = 7.45 (d, J = 8.2 Hz, 2 H, Ar), 7.22
(d, J = 8.2 Hz, 2 H, Ar), 6.43 (d, J = 15.9 Hz, 1 H, CH), 6.06 (dt,
J = 15.9, 7.3 Hz, 1 H, CH), 2.63 (sept, J = 5.9 Hz, 1 H, CH), 2.49 (t,
J = 7.3 Hz, 2 H, CH2), 2.17–2.30 (m, 4 H, CH2).
13C NMR (90.55 MHz, CDCl3): d = 135.61, 133.29, 131.73, 127.69,
125.65, 121.45, 107.81–118.87 (m, Rf6), 37.96, 33.76 (t, J = 20.8
Hz), 25.48.
MS (EI, 70 eV): m/z (%) = 530.7 (28) [M+], 170.8 (100), 91 (68).
1-Iodo-4-(5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorodecyl)ben-
zene (5b)
To a mixture of Ni (54.8 mg, 0.94 mmol), KI (62 mg, 0.37 mmol),
I2 (2.3 mg, 9.3 mmol), and deoxygenated 7 (0.1 g, 0.19 mmol) was
added DMF (0.5 mL). The resulting suspension was heated to
150 °C for 27 h. The crude reaction mixture was allowed to cool to
r.t., before 3% aq HCl (10 mL) was added. The resulting mixture
was extracted with pentane (3 × 20 mL). The combined organic lay-
ers were dried (Na2SO4) and filtered, and all volatiles were re-
moved. This yielded a brown liquid, which was filtered over a plug
of silica gel under reduced pressure with pentane as eluent; this af-
forded the title compound as a colourless liquid.
MS (EI, 70 eV): m/z (%) = 873.98 (85) [M+], 461.04 (12), 198.03
(100).
1-Bromo-4-[6,6,7,7,8,8,9,9,10,10,11,11,11-tridecafluoro-4-
(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)undecyl]benzene
(5c)
Bromobenzene 11 (9.6 g, 10.98 mmol) was dissolved in pentane (90
mL) and placed in a 250-mL autoclave. The Rh/C (450 mg, 0.44
mmol) catalyst was added, and the autoclave was purged with H2
(2 × 60 bar). The mixture was stirred at r.t. under H2 (50 bar) for 24
h. Afterwards, the catalyst was removed by filtration over a silica-
gel plug under reduced pressure with pentane as solvent. Removing
all volatiles yielded the title compound as a colourless oil.
Yield: 90 mg (83%); Rf = 0.65 (pentane).
1H NMR (360 MHz, CDCl3): d = 7.61 (d, J = 8.2 Hz, 2 H, Ar), 6.93
(d, J = 8.2 Hz, 2 H, Ar), 2.60 (t, J = 7.04 Hz, 2 H, CH2), 2.00–2.15
(m, 2 H, CH2), 1.61–1.71 (m, 4 H, CH2).
Yield: 9.4 g (98%); Rf = 0.70 (pentane).
13C NMR (90.55 MHz, CDCl3): d = 141.22, 137.47, 130.44, 90.98,
107.65–121.48 (m, Rf6), 35.03, 30.68 (t, J = 22.5 Hz), 30.65, 19.76
(t, 3JCF = 3.64 Hz).
1H NMR (360 MHz, CDCl3): d = 7.41 (d, J = 8.2 Hz, 2 H, Ar), 7.05
(d, J = 8.2 Hz, 2 H, Ar), 2.59 (t, J = 6.5 Hz, 2 H, CH2), 2.44 (sept,
J = 5.5 Hz, 1 H, CH), 2.07–2.24 (m, 4 H, CH2), 1.58–1.65 (m, 4 H,
CH2).
13C NMR (90.55 MHz, CDCl3): d = 140.52, 131.51, 130.05, 119.80,
35.02, 34.27, 34.22 (t, J = 21.1 Hz), 27.78, 25.40.
MS (EI, 70 eV): m/z (%) = 578.8 (12) [M+], 216.9 (100), 89.9 (21).
8-Allyl-1,1,1,2,2,3,3,4,4,5,5,6,6,10,10,11,11,12,12,13,13,14,14,-
15,15,15-hexacosafluoropentadecane (9)
MS (EI, 70 eV): m/z (%) = 875.99 (100) [M+].
An oven-dried Schlenk flask was charged with [Pd(dppf)Cl2]
CH2Cl2 (253 mg, 0.31 mmol) and deoxygenated 8 (5 g, 6.2 mmol),
diluted with THF (20 mL). The mixture was cooled to 0 °C in an
ice–NaCl bath. Then 1 M allylmagnesium bromide in Et2O (9.3 mL,
9.3 mmol) was syringed in slowly (2 h), and this yielded a yellow
soln. The ice bath was removed after the addition was completed
and the mixture (turning green) was stirred for 12 h at r.t. before be-
ing quenched with MeOH (10 mL). All volatiles were removed un-
der reduced pressure; a brown suspension remained, which was
filtered over a silica-gel plug under reduced pressure with pentane
1,1¢-Ethyne-1,2-diylbis[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluo-
rooctyl)benzene] (3a)
CuI (18 mg, 99 mmol) and [PdCl2(PPh3)2] (40 mg, 59.6 mmol) were
suspended in an oven-dried Schlenk flask in freshly distilled ben-
zene (2.5 mL). Iodobenzene 5a (0.5 g, 0.99 mmol) was dissolved in
benzene (2.5 mL) before being added to the reaction vessel fol-
lowed by the injection of DBU (0.88 mL, 5.94 mmol). H2O (7 mL,
40 mmol) and (trimethylsilyl)acetylene (66 mL, 0.47 mmol) were
added simultaneously by two syringes. The Schlenk flask was then
Synthesis 2006, No. 17, 2891–2896 © Thieme Stuttgart · New York

PAPER
Synthesis of Fluorinated Hexa-peri-hexabenzocoronenes
2895
protected from ambient light and heated to 80 °C. After 72 h of re-
action, the black reaction mixture was allowed to cool to r.t. before
Et2O (50 ml) was added. The crude mixture was extracted with H2O
(2 × 50 mL), 10% HCl (50 mL), brine (50 mL) and H2O (50 mL).
The combined organic fractions were dried (Na2SO4), filtered, and
evaporated. This yielded a brown solid which was dissolved in
Et2O–pentane (9:1; 400 mL) and filtered over a plug of basic alu-
minium oxide under reduced pressure. After evaporation of all vol-
atiles, a yellow solid was obtained, which was further purified by
recrystallisation from pentane–Et2O–EtOH; this yielded the title
compound as an off-white solid.
vent removed all traces of the catalyst and yielded a yellow solid
which was recrystallised from Et2O–EtOH; this gave the title com-
pound as a white solid.
Yield: 82 mg (82%); Rf = 0.85 (pentane–EtOAc, 9:1).
1H NMR (360 MHz, CDCl3): d = 6.73 (d, J = 8.1 Hz, 12 H, Ar), 6.70
(d, J = 8.1 Hz, 12 H, Ar), 2.68 (t, J = 7.9 Hz, 12 H), 2.07–2.21 (m,
12 H).
13C NMR (90.55 MHz, CDCl3): d = 140.06, 138.90, 135.98, 131.65,
126.52, 109.25–120.15 (m, Rf6), 32.54 (t, J = 22.1 Hz), 25.88 (t,
J = 4.0 Hz).
MALDI-ICR-MS (DCTB): m/z [M+] (%) calcd for C90H48F78:
Yield: 143 mg (33%); Rf = 0.46 (pentane).
1H NMR (360 MHz, CDCl3): d = 7.49 (d, J = 8.1 Hz, 4 H, Ar), 7.20
(d, J = 8.1 Hz, 4 H, Ar), 2.93 (m, J = 8.4 Hz, 4 H, CH2), 2.23–2.44
(m, 4 H, CH2).
13C NMR (90.55 MHz, CDCl3): d = 139.38, 131.98, 128. 35,
121.73, 108.38–119.99 (m, Rf6), 89.07, 32.68 (t, J = 22.1 Hz),
26.40.
2610.25; found: 2610.22 (100).
Hexakis[4-(5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorodecyl)phe-
nyl]benzene (2b)
As described for compound 2a, tolane 3b (2.8 g, 3.02 mmol) was
converted into the title compound in the presence of Co2(CO)8
(62.16 mg, 0.18 mmol) and dioxane (180 mL).
MS (EI, 70 eV): m/z (%) = 870.08 (100) [M+], 481.27 (20).
Yield: 2.52 g (90%); Rf = 0.19 (pentane–EtOAc, 9:1).
1H NMR (360 MHz, CDCl3): d = 6.68 (d, J = 7.9 Hz, 12 H, Ar), 6.62
(d, J = 7.9 Hz, 12 H, Ar), 2.39 (t, J = 7.0 Hz, 12 H, CH2), 1.89–2.04
(m, 12 H, CH2), 1.46–1.53 (m, 12 H, CH2), 1.34–1.45 (m, 12 H,
CH2).
13C NMR (90.55 MHz, CDCl3): d = 140.19, 138.53, 137.85, 131.58,
126.45, 108.07–121.19 (m, Rf6), 34.62, 30.55 (t, J = 22.5 Hz),
30.38, 18.96.
1,1¢-Ethyne-1,2-diylbis[4-(5,5,6,6,7,7,8,8,9,9,10,10,10-trideca-
fluorodecyl)benzene] (3b)
As described for compound 3a, iodobenzene 5b (9.9 g, 17.12
mmol) reacted with (trimethylsilyl)acetylene (1.32 mL, 9.08 mmol)
in the presence of CuI (326 mg, 1.71 mmol), [PdCl2(PPh3)2] (721
mg, 1.03 mmol), DBU (15.35 mL, 103 mmol), THF (80 mL), and
H2O (123 mL, 6.85 mmol).
MALDI-ICR-MS (DCTB): m/z [M+] (%) calcd for C102H72F78:
Yield: 3.5 g (44%); Rf = 0.95 (pentane–EtOAc, 4:1).
1H NMR (500 MHz, CDCl3): d = 7.45 (d, J = 8.1 Hz, 4 H, Ar), 7.15
(d, J = 8.1 Hz, 4 H, Ar), 2.67 (t, J = 7.5 Hz, 4 H, CH2), 2.05–2.14
(m, 4 H, CH2), 1.68–1.76 (m, 8 H, CH2).
13C NMR (125.77 MHz, CDCl3): d = 141.89, 131.65, 128.37,
121.00, 88.96, 105.63–121.06 (m, Rf6), 35.45, 30.72 (t, J = 22.1
Hz,), 30.62, 19.79.
2778.44; found: 2778.45 (92).
Hexakis{4-[6,6,7,7,8,8,9,9,10,10,11,11,11-tridecafluoro-4-
(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)undecyl]phe-
nyl}benzene (2c)
As described for compound 2a, tolane 3c (1.1 g, 0.67 mmol) was
converted into the title compound in the presence of Co2(CO)8 (18.6
mg, 43 mmol) and dioxane (20 mL).
MS (EI, 70 eV): m/z (%) = 928.0 (15) [M+], 565.9 (100).
Yield: 1.05 g (95%); Rf = 0.90 (pentane).
1,1¢-Ethyne-1,2-diylbis{4-[6,6,7,7,8,8,9,9,10,10,11,11,11-tride-
cafluoro-4-(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)unde-
cyl]benzene} (3c)
As described for compound 3a, bromobenzene 5c (2.8 g, 3.2 mmol)
reacted with (trimethylsilyl)acetylene (0.22 mL, 1.5 mmol) in the
presence of CuI (60.8 mg, 0.32 mmol), PdCl2(PPh3)2 (134 mg, 0.19
mmol), DBU (2.7 mL, 19 mmol), benzene (15 mL), and H2O (23
mL, 1.3 mmol).
1H NMR (500 MHz, CDCl3): d = 6.69 (d, J = 8.2 Hz, 12 H, Ar), 6.60
(d, J = 8.2 Hz, 12 H, Ar), 2.35 (m, 6 H, CH), 2.34 (m, 12 H, CH2),
1.99–2.19 (m, 24 H, CH2), 1.35–1.46 (m, 24 H, CH2).
13C NMR (125.77 MHz, CDCl3): d = 140.16, 138.59, 137.81,
131.55, 126.33, 110.56–120.60 (m, Rf6), 34.73, 34.11 (t, J = 21.1
Hz), 33.78, 27.36, 25.19.
MALDI-ICR-MS (DCTB): m/z [M+] (%) calcd for C150H90F156
4854.46; found: 4854.45 (48).
:
Yield: 1.2 g (47%); Rf = 0.15 (pentane).
1H NMR (360 MHz, CDCl3): d = 7.46 (d, J = 8.2 Hz, 4 H, Ar), 7.15
(d, J = 8.2 Hz, 4 H, Ar), 2.65 (t, J = 6.8 Hz, 4 H, CH2), 2.45 (sept,
J = 5.9 Hz, 2 H, CH), 2.07–2.24 (m, 8 H, CH2), 1.58–1.65 (m, 8 H,
CH2).
13C NMR (90.55 MHz, CDCl3): d = 141.83, 131.66, 128.35, 121.06,
108.05–120.83 (m, Rf6), 88.95, 35.52, 34.30, 34.24 (t, J = 21.1 Hz),
27.66, 25.40.
2,5,8,11,14,17-Hexakis(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-
octyl)hexabenzo[bc,ef,hi,kl,no,qr]coronene (1a)
Hexaphenylbenzene 2a (0.2 g, 76.6 mmol) was dissolved in dry
CH2Cl2 (10 mL). At the same time, a soln of FeCl3 (7.45 mg, 4.59
mmol) was prepared in MeNO2 (4 mL). The FeCl3 soln was added
drop-by-drop by syringe to the mixture at 45 °C. Argon was bub-
bled through the mixture through a Teflon capillary during all the
reaction time. After 27 h of reaction, the mixture was quenched by
the addition of MeOH (100 mL). The black precipitate was collect-
ed by suction filtration over Millipore and was suspended in differ-
ent common organic solvents (CH2Cl2, MeOH, Et2O, and pentane).
The formed suspensions were each time treated in an ultrasonic bath
for 30 min, followed by refluxing for 1 h. After 2 h of cooling in the
refrigerator, the suspensions were filtered over Millipore, yielding
an orange compound which was re-precipitated first from benzotri-
fluoride (5 mL), and, finally, from hexafluorobenzene (3 × 5 mL);
this gave the title compound as a bright yellow powder.
MALDI-ICR-MS (DCTB): m/z calcd for C50H30F52: 1618.15;
found: 1618.15; m/z (%) = 1618.15 (100) [M+], 1387.08 (18),
922.10 (15).
Hexakis[4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)phe-
nyl]benzene (2a)
Tolane 3a (0.1 g, 115 mmol) was dissolved in dioxane (20 mL).
Co2(CO)8 (2.4 mg, 6.9 mmol) was added before the reaction mixture
was heated to 110 °C. After 48 h, the mixture was cooled to r.t. and
all volatiles were removed, yielding a brown solid. Filtration
through a plug of silica gel under reduced pressure with Et2O as sol-
Synthesis 2006, No. 17, 2891–2896 © Thieme Stuttgart · New York

2896
O. F. Aebischer et al.
PAPER
Yield: 140 mg (70%).
1H NMR (500 MHz, CDCl3): d = 8.82 (br s, 12 H, HBC), 3.63 (br s,
12 H, CH2), 3.02 (m, 12 H, CH2).
MALDI-ICR-MS (DCTB, solvent-free preparation17): m/z [M+]
calcd for C90H36F78: 2598.15; found: 2598.17; m/z (%) = 2598.17
(100), 2265.16 (15), 1932.17 (5).
References
(1) (a) Clar, E. Polycyclic Hydrocarbons, Vol. I/II; Academic
Press: New York, 1964. (b) Harvey, R. G. Polycyclic
Aromatic Hydrocarbons; Wiley-VCH: New York, 1997.
(2) Wu, J.; Watson, M. D.; Zhang, L.; Wang, Z.; Müllen, K. J.
Am. Chem. Soc. 2004, 126, 177.
(3) Kastler, M.; Pisula, W.; Wasserfallen, D.; Pakula, T.;
Müllen, K. J. Am. Chem. Soc. 2005, 127, 4286.
(4) Spraul, K. B.; Suresh, S.; Glaser, S.; Perahia, D.; Ballato, J.;
Smith, D. W. J. Am. Chem. Soc. 2004, 126, 12772.
(5) Alameddine, B.; Aebischer, O. F.; Amrein, W.; Donnio, B.;
Deschenaux, R.; Guillon, D.; Savary, C.; Scanu, D.;
Scheidegger, O.; Jenny, T. A. Chem. Mater. 2005, 17, 4798.
(6) Fechtenkötter, A.; Saalwächter, K.; Harbison, M. A.;
Müllen, K.; Spiess, H. W. Angew. Chem. Int. Ed. 1999, 38,
3039.
(7) Vollhardt, K. P. C. Acc. Chem. Res. 1977, 10, 1.
(8) Kovacic, P.; Jones, M. B. Chem. Rev. 1987, 87, 357.
(9) Fechtenkötter, A.; Tchebotareva, N.; Watson, M.; Müllen,
K. Tetrahedron 2001, 57, 3769.
UV/Vis (benzotrifluoride, 10–6 M): lmax = 343, 359, 370 nm.
2,5,8,11,14,17-Hexakis(5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluo-
rodecyl)hexabenzo[bc,ef,hi,kl,no,qr]coronene (1b)
As described for compound 1a, hexaphenylbenzene 2b (1.0 g, 0.36
mmol) was converted into the title compound in the presence of
CH2Cl2 (50 mL) and FeCl3 (1.17 g, 7.19 mmol) in MeNO2 (20 mL).
Yield: 697 mg (70%).
1H NMR (500 MHz, CDCl3): d = 9.06 (s, 12 H, HBC), 3.57 (t,
J = 7.8 Hz, 12 H, CH2), 2.59–2.63 (m, 24 H, CH2), 2.30 (q,
3JHH = 7.8 Hz, 12 H, CH2).
MALDI-ICR-MS (DCTB, solvent-free preparation): m/z [M+] calcd
for C102H60F78: 2766.34; found: 2766.33; m/z (%) = 2766.33 (91),
1906.34 (20), 1644.28 (10), 1384.27 (5).
(10) Mio, M. J.; Kopel, L. C.; Braun, J. B.; Gadzikwa, T. L.; Hull,
K. L.; Brisbois, R. G.; Markworth, C. J.; Grieco, P. A. Org.
Lett. 2002, 4, 3199.
UV/Vis (benzotrifluoride, 10–6 M): lmax = 343, 359, 370 nm.
(11) Darses, S.; Pucheault, M.; Genêt, J.-P. Eur. J. Org. Chem.
2,5,8,11,14,17-Hexakis[6,6,7,7,8,8,9,9,10,10,11,11,11-trideca-
fluoro-4-(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)unde-
cyl]hexabenzo[bc,ef,hi,kl,no,qr]coronene (1c)
As described for compound 1a, hexaphenylbenzene 2c (1.0 g, 0.21
mmol) was converted into the title compound in the presence of
CH2Cl2 (80 mL) and FeCl3 (0.6 g, 3.7 mmol) in MeNO2 (8 mL).
2001, 1121.
(12) Brace, N. O. J. Fluorine Chem. 1999, 93, 1.
(13) Yang, S. H.; Li, C. S.; Cheng, C. H. J. Org. Chem. 1987, 52,
691.
(14) Gambaretto, G.; Conte, L.; Fornasieri, G.; Zarantonello, C.;
Tonei, D.; Sassi, A.; Bertani, R. J. Fluorine Chem. 2003,
121, 57.
(15) Bader, A.; Gladbach, B.; Arlt, D. US Patent 5,185,454, 1993.
(16) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R.
K.; Timmers, F. J. Organometallics 1996, 15, 1518.
(17) Trimpin, S.; Rouhanipour, A.; Az, R.; Räder, H. J.; Müllen,
K. Rapid Commun. Mass Spectrom. 2001, 15, 1364.
Yield: 667 mg (67%).
1H NMR (360 MHz, CDCl3): d = 9.23 (s, 12 H, HBC), 2.27–2,62
(br m, 66 H).
MALDI-ICR-MS (DCTB, solvent-free preparation): m/z [M+] (%)
calcd for C150H78F156: 4842.36; found: 4842.39 (58).
UV/Vis (benzotrifluoride, 10–6 M): lmax = 344, 361, 390 nm.
Synthesis 2006, No. 17, 2891–2896 © Thieme Stuttgart · New York