DOI: 10.1002/ejoc.201600311

Full Paper

Fullerenes

Synthesis of a Crushed Fullerene C60H24 through Sixfold
Palladium-Catalyzed Arylation
Ruth Dorel,[a] Paula de Mendoza,[a] Pilar Calleja,[a] Sergio Pascual,[a]
Esther González-Cantalapiedra,[a][‡] Noemí Cabello,[a] and Antonio M. Echavarren*[a,b]
Dedicated to Professor Achille Umani-Ronchi in the occasion of his 80th birthday

Abstract: The synthesis of a new C3v-symmetric crushed fullerene C60H24 (5) has been accomplished in three steps from truxene through sixfold palladium-catalyzed intramolecular aryl-

ation of a syn-trialkylated truxene precursor. Laser irradiation of
5 induces cyclodehydrogenation processes that result in the
formation of C60, as detected by LDI-MS.

Introduction

functionalized compounds,[6] whereas flash-vacuum pyrolysis
was used in the synthesis of fullerene C60 from C60H27Cl3 as the
precursor.[7]
Fullerene C60 and triazafullererene C57N3 were also formed
from 2 and C57H33N3[8] precursors, respectively, by cyclodehydrogenation on a platinum surface.[9] STM images were obtained for deposited triangular fullerene precursors that, after
annealing at 750 K, formed round-shaped C60, indistinguishable
from those images of authentic C60 fullerene, and ball-shaped
heterofullerene C57N3, which was previously unknown.
We now report our efforts towards the synthesis of new
crushed fullerenes already containing 78 of the 90 C–C bonds
present in C60 fullerene. We envisioned two possible truxene-

Truxene (10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorene) (1) is
a useful platform for the threefold synthesis of crushed fullerene C60H30 (2) and other C3v-symmetric molecules
(Scheme 1),[1–3] as well as being an attractive building block
for the preparation of new materials to be used in molecular
electronics.[4] The laser-induced cyclodehydrogenation in the
gas phase to form closed-shell C60 fullerene has been previously
demonstrated for 2 (“crushed fullerene”)[5] and other related

Scheme 1. Synthesis of crushed fullerene C60H30 (2).
[a] Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of
Science and Technology,
Av. Països Catalans 16, 43007 Tarragona, Spain
E-mail: aechavarren@iciq.es
http://www.iciq.org/research/research_group/prof-antonio-m-echavarren/
[b] Departament de Química Orgànica i Analítica, Universitat Rovira i Virgili,
C/ Marcel·lí Domingo s/n, 43007 Tarragona, Spain
[‡] Current address: Medicinal Chemistry Department, Spanish National
Cancer Research Centre (CNIO)
C/ Melchor Fernández Almagro 3, 28029 Madrid, Spain
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under http://dx.doi.org/10.1002/ejoc.201600311.
© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. ·
This is an open access article under the terms of the Creative Commons
Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and
is not used for commercial purposes
Eur. J. Org. Chem. 2016, 3171–3176

Scheme 2. Retrosynthetic strategy for crushed fullerenes C60H24 3 and 5.

3171

© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
based C60H24 isomers 3 and 5, which are more advanced
crushed fullerenes than 2 and could be respectively accessed
from the suitably functionalized trialkylated truxene precursors
4 and 6 by means of multiple Pd-catalyzed direct arylations
(Scheme 2).[10] These π-expanded truxenes could also give rise
to C60 by laser-promoted cyclodehydrogenation (Scheme 3). Interestingly, 5 was proposed to be a plausible intermediate in
the formation of C60 fullerene,[11] although its synthesis and
characterization have never been reported.

Results and Discussion
4,9,14-Trisubstituted truxenes 7 were prepared by acid-catalyzed trimerization of the corresponding 7-substituted 1-indanones.[1b] Triple alkylation of their lithium or sodium trianions
afforded the expected products 4 as crude mixtures of syn and
anti isomers, as determined from 1H NMR spectra of the crude
materials, which surprisingly could not be isomerized in the
presence of base to form exclusively the syn isomer, as we had
previously observed in the vast majority of cases.[1a] Thus, 4a
was obtained as a 1.3:1 mixture of syn and anti isomers after
chromatographic purification, whereas in the case of 4b, pure
anti isomer was isolated after column chromatography and precipitation from mixtures of CH2Cl2 and pentane (Scheme 4). The
structure of anti-4b was confirmed by X-ray diffraction analysis.[13]

Scheme 4. Synthesis of trialkylated precursors 4 and X-ray crystal structure
of anti-4b.

Scheme 3. (a) Laser-induced formation of C60 fullerene from 3 and 5. (b)
Schlegel projections of 3 and 5 onto C60.

Although remarkable multiple intermolecular palladium-catalyzed arylations have been reported,[12] for the intramolecular
palladium-catalyzed arylation reaction of bromoarenes, the formation of 5 from 6 would involve the highest order (sixfold)
arylation of this type to date.[12a]
Eur. J. Org. Chem. 2016, 3171–3176

www.eurjoc.org

Given that all attempts to convert 4a directly into crushed
fullerene 3 by Pd-catalyzed intramolecular direct arylation afforded complex mixtures from which 3 could not be identified,
we turned our attention to the cyclization of 4b. It seemed clear
to us that this cyclization could be sequentially carried out by
initial triple Pd-catalyzed cyclization of 4b to form 8 after dehydrogenation, followed by triple demethylation, formation of
the corresponding tristriflate, and subsequent triple Pd-catalyzed intramolecular arylation (Scheme 5). After screening a
range of reaction conditions, we found that the triple Pd-catalyzed cyclization of anti-4b proceeded in moderate yield in the
presence of Pd(OAc)2 and PhDavePhos. Treatment of the resulting mixture with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
(DDQ) forced the triple dehydrogenation to afford 8 in 31 %
yield over the two steps, the structure of which was confirmed
by X-ray diffraction.[13] Demethylation of 8 was carried out with
BBr3 to form 9 as a poorly soluble solid in excellent yield. However, conversion of 9 into tristriflate 10 could only be achieved

3172

© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
at low temperatures and in low yield. Furthermore, 10 turned
out to be unstable under ambient conditions, and attempts to
cyclize this tristriflate to form 3 in the presence of different Pd
catalysts failed, providing complex mixtures, presumably due to
its low stability.

Scheme 5. Synthesis tristriflate 10 from anti-4b and X-ray crystal structure of 8.

Not discouraged by these results, we decided to focus our
efforts on the synthesis of crushed fullerene 5. Thus, tribromotruxene 11 was prepared by direct bromination of truxene,[1b]
which can be readily obtained in a multigram scale from 1-

indanone.[14] Triple alkylation of the corresponding sodium trianion with 1-bromo-2-(bromomethyl)naphthalene furnished the
desired hexabrominated precursor 6. The triple alkylation of 11
afforded mixtures of anti and syn isomers that, as happened in
the case of 4, could not be isomerized in the presence of base
to form exclusively the syn isomer.[1a] Nevertheless, pure syn
isomer could be obtained upon precipitation from mixtures of
CH2Cl2 and pentane (Scheme 6). A conceivable alternative synthesis of 5 by the direct acid-catalyzed triannulation strategy[15]
would require the development of a synthesis of unknown ketone indeno[4,3,2,1-lmno]acephenanthrylen-1(2H)-one or its regioisomer.[16]
Hexabromotruxene syn-6 was next subjected to different palladium-catalyzed direct arylation reaction conditions. Due to
the high insolubility of both syn-6 and the product of this transformation, LDI-MS experiments were used as a tool to find the
optimal conditions for the intramolecular arylation. When
Pd(OAc)2, BnMe3NBr, and K2CO3[1g] were used under different
reaction conditions, only complex mixtures were detected, and
no clear formation of 5 was observed. The use of phosphine
ligands such as Xantphos, 1,3-bis(diphenylphosphanyl)propane
(dppp) or PhDavePhos did not result in any improvement. Fortunately, when ethylenebis(diphenylphosphine) (dppe) was
used as the ligand, we were able to observe clear evidence for
the formation of 5. After extensive optimization of the reaction
conditions, LDI experiments of the isolated solid in positive and
negative modes showed a single peak at m/z 744 with an experimental isotopic pattern that was consistent with the theoretical distribution calculated for 5 (Figure 1). This peak corresponds to the target crushed fullerene, which could be isolated
in 44 % yield as a highly insoluble orange solid. Formation of 5
from syn-6 involves a remarkable sequence of nine reactions
catalyzed by palladium: sixfold intramolecular arylation and a
triple dehydrogenation process.

Scheme 6. Synthesis of crushed fullerene C60H24 (5).
Eur. J. Org. Chem. 2016, 3171–3176

www.eurjoc.org

3173

© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
the range of 126 μJ, a peak at m/z 721 corresponding to the
formation of [C60 + H]·+ could be identified, which underwent
further C2 fragmentations to give a series similar to that resulting from pure C60 fullerene (Figure 2, b).[5b]

Conclusions
Figure 1. (left) LDI– mass spectrum of crushed fullerene C60H24 (5).
(right) Theoretical and experimental isotopic pattern for C60H24 (5).

To verify that 5 is a direct precursor of C60 fullerene, a sample
of pure C60H24 was analyzed by MALDI and LDI-MS in positive
and negative modes by using increasing laser powers, and the
results in positive mode were compared to those arising from
the analogous experiments on a sample of pure C60. MALDI-MS
analysis at the threshold of ion formation in negative mode
using 2,5-dihydroxybenzoic acid (DHB) as the matrix showed
exclusively the molecular ion of 3, whereas at a higher laser
power in the range of 129 μJ, this precursor ion underwent
threefold H2 loss giving [C60H22]·–, [C60H20]·–, and [C60H18]·– (m/z
742, 740, and 738, respectively, Figure 2, a). On the other hand,
when the sample was analyzed in positive mode by LDI-MS to
avoid interferences derived from the matrix at a laser power in

Figure 2. (a) (top) MALDI– mass spectrum of 5 at the threshold of ion formation using DHB as the matrix. (bottom) MALDI– mass spectrum of 5 at 129 μJ
using DHB as the matrix. (b) (top) LDI+ mass spectrum of C60 fullerene at a
laser power of 106 μJ. (center) LDI+ mass spectrum of C60 fullerene at a laser
power of 115 μJ. (bottom) LDI+ mass spectrum of 5 at a laser power of 126 μJ.
Eur. J. Org. Chem. 2016, 3171–3176

www.eurjoc.org

A new, advanced crushed fullerene C60H24 has been synthesized by a sixfold palladium-catalyzed intramolecular arylation,
which takes place in a remarkable 44 % yield, equivalent to an
average 87 % yield per C–C bond formation, and subsequent in
situ dehydrogenation. Open-shell C60 derivative 5 gives rise to
C60 fullerene by applying high-power laser irradiation in LDI-MS
experiments. On-surface cyclodehydrogenation experiments to
form C60 are underway.

Experimental Section
General Procedures: Reactions were performed under argon atmosphere in solvents dried by passing through an activated alumina column on a PureSolvTM solvent purification system (Innovative Technologies, Inc., MA). Thin-layer chromatography was carried
out using TLC aluminum sheets coated with 0.2 mm of silica gel
(Merck Gf234). Chromatographic purifications were carried out using flash grade silica gel (SDS Chromatogel 60 ACC, 40–60 μm).
NMR spectra were recorded at 25 °C with a Bruker Avance 300, 400
Ultrashield and Bruker Avance 500 Ultrashield apparatus, or at
120 °C with a Bruker Avance 500 Ultrashield apparatus. Mass spectra
were recorded with a MicroTOF Focus Bruker Daltonics mass spectrometer (ESI) or with an Autoflex Bruker Daltonics (MALDI and LDI)
equipped with a nitrogen laser (337 nm) with a mean energy of
165.6 μJ per pulse and a beam dimension of 4 × 2.5 mm. Samples
were measured at least four times under the same conditions and a
minimum of 200 shots were accumulated per full spectrum. Melting
points were determined with a Büchi melting point apparatus. Crystal structure determinations were carried out with a Bruker-Nonius
diffractometer equipped with an APPEX 2 4K CCD area detector,
a FR591 rotating anode with Mo-Kα radiation, Montel mirrors as
monochromator and a Kryoflex low-temperature device (T =
–173 °C). Full-sphere data collection was used with w and j scans.
Programs used: Data collection APEX-2, data reduction Bruker Saint
V/.60A and absorption correction SADABS. Structure Solution and
Refinement: Crystal structure solution was achieved by using direct
methods as implement in SHELXTL and visualized by using the program XP. Missing atoms were subsequently located from difference
Fourier synthesis and added to the atom list. Least-squares refinement on F2 using all measured intensities was carried out using the
program SHELXTL. All non-hydrogen atoms were refined including
anisotropic displacement parameters.
5,10,15-Tris[(1-bromonaphthalen-2-yl)methyl]-4,9,14-tribromo10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorine (4a): A suspension of 4,9,14-tribromo-10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorene (360 mg, 0.62 mmol) in anhydrous DMF (5 mL) was added
over a suspension of NaH (60 % in mineral oil, 82 mg, 2.04 mmol)
in anhydrous DMF (5 mL) at 0 °C under Ar atmosphere. After ultrasonicating the resulting mixture for 50 min, a solution of 1-bromo2-(bromomethyl)naphthalene (577 mg, 1.92 mmol) in anhydrous
DMF (10 mL) was added and the mixture was stirred at room temperature for 16 h. H 2 O (20 mL) was added and the precipitate
formed was filtered off and dissolved in CH2Cl2 (50 mL). The result-

3174

© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
ing green solution was dried with MgSO4, filtered and concentrated
under reduced pressure. Purification by silica gel column chromatography (cyclohexane/CH2Cl2 8:2) gave a major fraction containing
4a as a mixture of syn and anti isomers together with unidentified
impurities. This fraction was partially dissolved in CH2Cl2 (10 mL)
and precipitated with pentane (30 mL). The supernatant was removed and the solid was washed again with pentane (3 × 20 mL)
and dried under reduced pressure giving the title compound, yield
331 mg (0.268 mmol, 41 %); pale-yellow solid; syn/anti = 1.3:1; m.p.
298–300 °C. 1H NMR (500 MHz, CDCl3): δ = 8.22–8.16 (m, 4.9 H, syn,
anti), 8.13 (d, J = 8.5 Hz, 2 H, anti), 7.80 (d, J = 9.6 Hz, 1 H, anti),
7.74–7.69 (m, 5.9 H, syn, anti), 7.68–7.63 (m, 5.9 H, syn, anti), 7.62–
7.58 (m, 4.9 H, syn, anti), 7.57–7.47 (m, 10 H), 7.46–7.43 (m, 3.9 H,
syn), 7.43–7.39 (m, 4.9 H, syn, anti), 7.36–7.33 (m, 3 H, anti), 7.26 (d,
J = 8.4 Hz, 3.9 H, syn), 7.09 (t, J = 8.4 Hz, 1 H, anti), 6.96 (t, J =
7.6 Hz, 3.9 H, syn), 6.89 (dt, J = 7.4, 0.9 Hz, 3.9 H, syn), 6.87–6.84 (m,
1 H, anti), 6.81 (d, J = 7.6 Hz, 1 H, anti), 6.79–6.76 (m, 1 H, anti), 6.63
(t, J = 7.6 Hz, 1 H, anti), 6.44 (t, J = 7.5 Hz, 1 H, anti), 6.41–6.36 (m,
2 H, anti), 6.12 (dd, J = 8.5, 6.1 Hz, 3.9 H, syn), 5.99 (dd, J = 9.7,
5.9 Hz, 1 H, anti), 3.77–3.71 (m, 3.9 H, syn), 3.70–3.67 (m, 1 H, anti),
3.59 (dd, J = 13.8, 7.0 Hz, 1 H, anti), 3.49 (dd, J = 13.8, 6.6 Hz, 1 H,
anti), 3.22 (dd, J = 13.8, 8.0 Hz, 1 H, anti), 3.16 (dd, J = 14.1, 8.6 Hz,
3.9 H, syn), 2.76 (dd, J = 13.9, 9.8 Hz, 1 H, anti) ppm. 13C NMR
(126 MHz, CDCl3): δ = 150.66, 150.31, 149.54, 149.16, 144.95, 144.43,
142.51, 142.41, 141.14, 140.64, 139.30, 138.95, 137.65, 137.26,
137.23, 137.01, 136.87, 136.68, 136.30, 135.92, 133.31, 133.28,
133.24, 133.20, 133.15, 132.91, 132.85, 132.37, 132.24, 132.21,
132.20, 128.27, 128.18, 128.08, 128.02, 127.97, 127.94, 127.88,
127.86, 127.84, 127.79, 127.74, 127.68, 127.60, 127.40, 127.37,
127.24, 127.17, 127.14, 126.99, 126.87, 126.84, 126.25, 126.02,
125.99, 125.85, 125.80, 125.64, 125.52, 123.88, 123.79, 123.32,
123.30, 116.11, 115.99, 115.19, 52.49 (anti), 52.14 (syn), 50.45 (anti),
49.98 (anti), 42.12 (anti), 41.53 (anti), 39.95 (anti), 39.31 (syn) (aromatic peaks missing due to overlapping) ppm. HRMS (MALDI+): m/z
calcd. for C60H3579Br381Br3 [M – H]+ 1234.7772; found 1234.7785.
(5R*,10S*,15S*)-5,10,15-Tris[(1-bromonaphthalen-2-yl)methyl]4,9,14-trimethoxy-10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorine (anti-4b): To a mixture of 4,9,14-trimethoxy-10,15-dihydro5H-diindeno[1,2-a:1′,2′-c]fluorine (600 mg, 1.39 mmol) in anhydrous
THF (55 mL) at –78 °C was added nBuLi (2.5 M in hexanes, 1.94 mL,
4.86 mmol) and the mixture was slowly warmed to –10 °C for 3 h.
Then, 1-bromo-2-bromomethylnaphthalene (1.67 g, 5.56 mmol) in
anhydrous THF (20 mL) was added and the mixture was warmed to
room temperature. After 30 min at that temperature, the mixture
was diluted with EtOAc and washed with saturated aqueous NaCl,
dried with MgSO4, and the volatiles evaporated. The residue was
purified by chromatography (cyclohexane/CH2Cl2, 8:2 to 1:1) to give
4b as a 3:1 mixture of anti/syn isomers together with unidentified
impurities. After precipitation from CH2Cl2/pentane mixtures, pure
anti-4b was obtained, yield 1.01 g (0.93 mmol, 67 %); m.p. 193–
195 °C. 1H NMR (400 MHz, CDCl3): δ = 8.25 (dt, J = 8.6, 1.0 Hz, 1 H),
8.22 (d, J = 8.6 Hz, 1 H), 8.18 (dd, J = 8.6, 1.0 Hz, 1 H), 7.78 (d, J =
7.0 Hz, 1 H), 7.73 (d, J = 7.0 Hz, 1 H), 7.65 (d, J = 8.4 Hz, 1 H), 7.61
(d, J = 5.5 Hz, 1 H), 7.59 (d, J = 6.2 Hz, 1 H), 7.55 (dt, J = 8.7, 1.6 Hz,
1 H), 7.51 (dd, J = 6.2, 1.4 Hz, 1 H), 7.49–7.41 (m, 5 H), 7.38 (d, J =
8.4 Hz, 1 H), 7.32 (ddd, J = 8.0, 6.8, 1.2 Hz, 1 H), 7.14–7.09 (m, 1 H),
7.06 (d, J = 7.6 Hz, 1 H), 7.02 (d, J = 7.6 Hz, 1 H), 6.94 (dd, J = 8.1,
7.4 Hz, 1 H), 6.86–6.76 (m, 4 H), 6.68 (dt, J = 7.4, 0.9 Hz, 1 H), 6.40
(dt, J = 7.4, 0.9 Hz, 1 H), 5.74 (dd, J = 8.3, 5.8 Hz, 1 H), 5.64 (t, J =
6.2 Hz, 1 H), 5.47 (dd, J = 9.5, 5.3 Hz, 1 H), 4.13 (s, 3 H), 4.08 (s, 3
H), 4.06 (s, 3 H), 4.04–4.00 (m, 1 H), 3.79 (dd, J = 14.0, 5.9 Hz, 1 H),
3.64 (dd, J = 13.8, 6.3 Hz, 1 H), 3.50 (dd, J = 14.2, 5.3 Hz, 1 H), 3.21
(dd, J = 14.0, 8.3 Hz, 1 H), 2.85 (dd, J = 14.1, 9.5 Hz, 1 H) ppm. 13C
Eur. J. Org. Chem. 2016, 3171–3176

www.eurjoc.org

NMR (101 MHz, CDCl3): δ = 154.45, 154.30, 154.14, 150.07, 148.98,
142.91, 141.24, 141.09, 138.18, 137.74, 137.15, 136.21, 136.15,
135.88, 133.17, 133.11, 132.34, 132.29, 129.73, 128.55, 128.42,
128.21, 128.13, 128.02, 127.96, 127.87, 127.78, 127.76, 127.73,
127.57, 127.47, 126.99, 126.88, 126.77, 126.53, 126.50, 125.79,
125.72, 125.69, 125.61, 125.51, 125.28, 118.22, 117.73, 117.67,
110.04, 109.92, 109.84, 56.07, 55.96, 55.61, 50.97, 50.04, 49.56, 42.78,
41.68, 41.57 (peaks missing due to overlapping) ppm. HRMS (ESI+):
m/z calcd. for C 6 3 H 4 5 Br 3 NaO 3 [M + Na] + 1109.0811; found
1109.0779.
3,13,23-Trimethoxybenzo[1,2-e:3,4-e′:5,6-e′′]tribenzo[l]acephenanthrylene (8): Compound anti-4b (400 mg, 0.37 mmol),
Pd(OAc)2 (82.4 mg, 0.37 mmol), PhDavePhos (70.6 mg, 0.19 mmol)
and K2CO3 (102.3 mg, 0.74 mmol) were suspended in anhydrous
DMA (1.9 mL, 0.2 M) in a sealed tube under Ar atmosphere, and
the mixture was heated at 140 °C for 16 h. After cooling to room
temperature, CHCl3 (20 mL) was added and the mixture was washed
with saturated aqueous NaCl (3 × 15 mL), dried with MgSO4, and
concentrated to dryness. The resulting crude material was dissolved
in toluene (10 mL), then DDQ (840 mg, 3.7 mmol) was added and
the reaction was stirred at 120 °C for 6 h. After cooling to room
temperature, the solution was washed with 2 M solution of KOH
(3 × 10 mL), dried with MgSO4, and concentrated to a volume of
ca. 2 mL (higher yields were obtained when the crude material
was not taken to dryness). Purification by flash chromatography
(cyclohexane/CHCl3, 7:3 to 0:1) afforded the product as a brownish
solid that became insoluble after drying, yield 96.5 mg (0.11 mmol,
31 % over two steps); m.p. >300 °C. 1H NMR (400 MHz, C2D2Cl4):
δ = 9.24 (d, J = 8.4 Hz, 3 H), 9.10 (d, J = 9.1 Hz, 3 H), 8.42 (s, 3 H),
8.12 (dd, J = 8.0, 1.4 Hz, 3 H), 8.06 (d, J = 8.6 Hz, 3 H), 7.94 (d, J =
8.6 Hz, 3 H), 7.85 (ddd, J = 8.4, 6.8, 1.5 Hz, 3 H), 7.74 (ddd, J = 7.9,
6.8, 1.0 Hz, 3 H), 7.61 (d, J = 9.2 Hz, 3 H), 4.12 (s, 9 H) ppm. 13C
NMR (101 MHz, C2D2Cl4): δ = 153.16, 136.34, 134.69, 133.49, 133.17,
131.87, 131.04, 130.06, 129.66, 128.72, 128.29, 128.15, 128.02,
126.57, 126.13, 126.08, 125.52, 121.55, 121.54, 113.70, 54.79 ppm.
HRMS (MALDI + ): m/z calcd. for C 63 H 36 O 3 [M] + 840.2664; found
840.2673.
3,13,23-Trihydroxybenzo[1,2-e:3,4-e′:5,6-e′′]tribenzo[l]acephenanthrylene (9): To a mixture of 8 (70 mg, 0.08 mmol) in anhydrous
CH 2 Cl 2 (10 mL) was added BBr 3 (1.0 M in CH 2 Cl 2 , 2.12 mL,
2.12 mmol) and the mixture was stirred at room temperature for
5 d. After cooling to 0 °C, H2O (10 mL) was slowly added, the aqueous phase was extracted with CH2Cl2 (10 mL), the combined organic layers were dried with MgSO4 and the volatiles evaporated.
The solid was triturated with hexanes and EtOAc to obtain 9 as a
brown solid with low solubility in organic solvents, yield 57.4 mg
(0.07 mmol, 91 %); m.p. >300 °C. 1H NMR (400 MHz, [D6]acetone):
δ = 10.00 (s, 3 H), 9.32 (d, J = 8.5 Hz, 3 H), 9.15 (d, J = 9.0 Hz, 3 H),
9.01 (s, 3 H), 8.24 (d, J = 8.6 Hz, 3 H), 8.16 (d, J = 7.9 Hz, 4 H), 8.02
(d, J = 8.6 Hz, 3 H), 7.88–7.83 (m, 3 H), 7.75–7.71 (m, 6 H) ppm. Full
13
C NMR spectroscopic data could not be recorded due to the low
solubility of the product. HRMS (FAB+): m/z calcd. for C60H30O3 [M]+
798.2195; found 798.2194.
(5S*,10S*,15S*)-2,7,12-Tribromo-5,10,15-tris[(1-bromonaphthalen-2-yl)methyl]-10,15-dihydro-5H-diindeno[1,2a:1′,2′-c]fluorene (syn-6): A suspension of 11 (360 mg, 0.62 mmol)
in anhydrous DMF (5 mL) was added over a suspension of NaH
(60 % in mineral oil, 82 mg, 2.04 mmol) in anhydrous DMF (5 mL)
at 0 °C under Ar atmosphere. After ultrasonicating the resulting
mixture for 50 min, a solution of 1-bromo-2-(bromomethyl)naphthalene (577 mg, 1.92 mmol) in anhydrous DMF (10 mL) was
added and the mixture was stirred at room temperature for 16 h.

3175

© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
H2O (20 mL) was added and the precipitate formed was filtered off
and redissolved in CH2Cl2 (50 mL). The resulting green solution was
dried with MgSO4, filtered, and concentrated under reduced pressure. Purification by silica gel column chromatography (cyclohexane/CH2Cl2, 8:2) gave a major fraction containing the desired syncompound together with variable amounts of the anti-isomer and
unidentified impurities. This fraction was partially dissolved in
CH2Cl2 (10 mL) and precipitated with pentane (30 mL). The supernatant was removed and the solid was washed again with pentane
(3 × 20 mL) and dried under reduced pressure to give the title compound, yield 121 mg (0.098 mmol, 15 %); pale-yellow solid; m.p. >
300 °C. 1H NMR (500 MHz, CDCl2CDCl2, 120 °C): δ = 8.37 (d, J =
9.3 Hz, 3 H), 7.77 (d, J = 2.9 Hz, 3 H), 7.76 (d, J = 3.0 Hz, 3 H), 7.63
(ddd, J = 8.5, 6.9, 1.4 Hz, 3 H), 7.56–7.49 (m, 6 H), 7.37 (dd, J = 8.1,
1.9 Hz, 3 H), 7.05 (d, J = 1.9 Hz, 3 H), 6.86 (d, J = 8.3 Hz, 3 H), 4.72
(dd, J = 7.1, 7.1 Hz, 3 H), 3.79 (dd, J = 13.7, 6.4 Hz, 3 H), 3.34 (dd,
J = 13.9, 8.2 Hz, 3 H) ppm. 13C NMR (126 MHz, CDCl2CDCl2, 120 °C):
δ = 148.2, 140.1, 138.2, 135.6, 133.1, 132.1, 129.6, 128.1, 128.1, 127.4,
126.9, 126.9, 126.4, 125.7, 124.6, 122.8, 119.8, 46.1, 40.6 (one aromatic carbon missing due to overlapping) ppm. HRMS (MALDI+):
m/z calcd. for C60H3579Br381Br3 [M – H]+ 1234.7772; found
1234.7809.
Triindeno[4,3,2,1-lmno]acephenanthrylene (5): A mixture of syn6 (62.8 mg, 0.051 mmol), Pd(OAc)2 (22.9 mg, 0.102 mmol), dppe
(40.5 mg, 0.102 mmol), and K2CO3 (105.7 mg, 0.765 mmol) in anhydrous DMA (0.5 mL) under Ar atmosphere was heated at 140 °C in
a sealed tube for 36 h. After cooling to room temperature, H2O
(5 mL) was added and the precipitated solid was filtered off and
washed by centrifugation with H2O (6 × 15 mL), acetone (6 ×
15 mL), satd. aq. NaCN (3 × 15 mL), acetone (6 × 15 mL) and finally
CH2Cl2 (5 × 15 mL) until the liquid phase remained colorless. After
drying the remaining solid under reduced pressure, crushed fullerene C60H24 was obtained, yield 16.8 mg (0.023 mmol, 44 %); darkorange highly insoluble solid; m.p. > 300 °C. NMR spectroscopic
data could not be acquired due to the low solubility of the compound. HRMS (LDI–): m/z calcd. for C60H24 [M]– 744.1883; found
744.1848.

[2]

[3]

[4]
[5]

[6]
[7]
[8]
[9]

[10]

[11]
[12]

Acknowledgments
The authors thank the Ministerio de Economía y Competitividad
(MINECO) (Severo Ochoa Excellence Accreditation 2014–2018,
SEV-2013-0319, project number CTQ2013-42106-P), the European Research Council (ERC) (Advanced Grant 321066), the
Agència de Gestió d'Ajuts Universitaris (AGAUR) (2014 SGR 818),
and the ICIQ Foundation.

[13]

[14]
[15]
[16]

Keywords: Fullerenes · Truxene · Palladium · Arylation ·
Mass spectrometry
[1] a) Ó. de Frutos, B. Gómez-Lor, T. Granier, M. Á. Monge, E. GutiérrezPuebla, A. M. Echavarren, Angew. Chem. Int. Ed. 1999, 38, 204–207;
Angew. Chem. 1999, 111, 186; b) B. Gómez-Lor, Ó. de Frutos, P. A. Ceballos, T. Granier, A. M. Echavarren, Eur. J. Org. Chem. 2001, 2107–2114;

Eur. J. Org. Chem. 2016, 3171–3176

www.eurjoc.org

c) Ó. de Frutos, T. Granier, B. Gómez-Lor, J. Jiménez-Barbero, A. Monge,
E. Gutiérrez-Puebla, A. M. Echavarren, Chem. Eur. J. 2002, 8, 2879–2890;
d) M. Ruiz, B. Gómez-Lor, A. Santos, A. M. Echavarren, Eur. J. Org. Chem.
2004, 858–866; e) B. Gómez-Lor, E. González-Cantalapiedra, M. Ruiz, Ó.
de Frutos, D. J. Cárdenas, A. Santos, A. M. Echavarren, Chem. Eur. J. 2004,
10, 2601–2608; f) E. González-Cantalapiedra, M. Ruiz, B. Gómez-Lor, B.
Alonso, D. García-Cuadrado, D. J. Cárdenas, A. M. Echavarren, Eur. J. Org.
Chem. 2005, 4127–4140; g) B. Gómez-Lor, Ó. de Frutos, A. M. Echavarren,
Chem. Commun. 1999, 2431–2432.
a) W. Y. Lai, R. D. Xia, D. C. C. Bradley, W. Huang, Chem. Eur. J. 2010, 16,
8471–8479; b) H. J. Xia, J. T. He, B. Xu, S. P. Wen, Y. W. Li, W. J. Tian,
Tetrahedron 2008, 64, 5736–5742; c) M. S. Yuan, Z. Q. Liu, Q. Fang, J. Org.
Chem. 2007, 72, 7915–7922; d) X.-Y. Cao, H. Zi, W. Zhang, H. Lu, J. Pei, J.
Org. Chem. 2005, 70, 3645–3653; e) M.-T. Kao, J.-H. Chen, Y.-Y. Chu, K.-P.
Tseng, C.-H. Hsu, K.-T. Wong, C.-W. Chang, C.-P. Hsu, Y.-Y. Liu, Org. Lett.
2011, 13, 1714–1717; f) Y. Xie, X. Zhang, Y. Xiao, Y. Zhang, F. Zhou, J. Qi,
J. Qu, Chem. Commun. 2012, 48, 4338–4340; g) G. Zhang, F. Rominger,
M. Mastalerz, Chem. Eur. J. 2016, 22, 3084–3093.
a) A. Mueller, K. Y. Amsharov, M. Jansen, Tetrahedron Lett. 2010, 51, 3221–
3225; b) M. A. Kabdulov, K. Y. Amsharov, M. Jansen, Tetrahedron 2010,
66, 8587–8593.
F. Goubard, F. Dumur, RSC Adv. 2015, 5, 3521–3551.
a) B. Gómez-Lor, C. Koper, R. H. Fokkens, E. J. Vlietstra, T. J. Cleij, L. W.
Jenneskens, N. M. M. Nibbering, A. M. Echavarren, Chem. Commun. 2002,
370–371; b) M. M. Boorum, Y. V. Vasil'ev, T. Drewello, L. T. Scott, Science
2001, 294, 828–831.
M. Kabdulov, M. Jansen, K. Y. Amsharov, Chem. Eur. J. 2013, 19, 17262–
17266.
L. T. Scott, M. M. Boorum, B. J. McMahon, S. Hagen, J. Mack, J. Blank, H.
Wegner, A. de Meijere, Science 2002, 295, 1500–1503.
B. Gómez-Lor, A. M. Echavarren, Org. Lett. 2004, 6, 2993–2996.
a) G. Otero, G. Biddau, C. Sánchez-Sánchez, R. Caillard, M. F. López, C.
Rogero, F. J. Palomares, N. Cabello, M. A. Basanta, J. Ortega, J. Méndez,
A. M. Echavarren, R. Pérez, B. Gómez-Lor, J. A. Martín-Gago, Nature 2008,
454, 865–868; b) K. Amsharov, N. Abdurakhmanova, S. Stepanow, S. Rauschenbach, M. Jansen, K. Kern, Angew. Chem. Int. Ed. 2010, 49, 9392–
9396; Angew. Chem. 2010, 122, 9582.
a) A. M. Echavarren, B. Gómez-Lor, J. J. González, Ó. de Frutos, Synlett
2003, 585–597; b) S. Pascual, P. de Mendoza, A. M. Echavarren, Org.
Biomol. Chem. 2007, 5, 2727–2734.
T.-C. Chang, A. Naim, S. N. Ahmed, G. Goodloe, P. B. Shevlin, J. Am. Chem.
Soc. 1992, 114, 7603–7604.
See: a) E. A. Jackson, B. D. Steinberg, M. Bancu, A. Wakamiya, L. T. Scott,
J. Am. Chem. Soc. 2007, 129, 484–485; b) K. Mochida, K. Kawasumi, Y.
Segawa, K. Itami, J. Am. Chem. Soc. 2011, 133, 10716–10719; c) Q. Zhang,
K. Kawasumi, Y. Segawa, K. Itami, L. T. Scott, J. Am. Chem. Soc. 2012, 134,
15664–15667; d) K. Kawasumi, Q. Zhang, Y. Segawa, L. T. Scott, K. Itami,
Nat. Chem. 2013, 5, 739–744.
CCDC 1467307 (for anti-4b), and 1467308 (for 8) contain the supplementary crystallographic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre.
E. V. Dehmlow, T. Kelle, Synth. Commun. 1997, 27, 2021–2031.
A. W. Amick, L. T. Scott, J. Org. Chem. 2007, 72, 3412–3418.
The parent hydrocarbon 1,2-dihydroindeno[4,3,2,1-lmno]acephenanthrylene is also an unknown compound. Indeno[4,3,2,1-lmno]acephenanthrylene is also unknown but has been proposed as an intermediate in the formation of cyclopenta[cd]pyrene by flash vacuum pyrolysis: M. Sarobe, H. C. Kwint, T. Fleer, R. W. A. Havenith, L. W. Jenneskens,
E. J. Vlietstra, J. H. V. Lenthe, J. Wesseling, Eur. J. Org. Chem. 1999, 1191–
1200.

Received: March 14, 2016
Published Online: May 2, 2016

3176

© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim