Straightforward Synthesis of Novel Acene-Based Aryne Precursors

Article abstract of DOI:10.1055/s-0034-1381005

Large polycyclic o-(trimethylsilyl)aryl triflates are easily obtained by reaction of commercially available bisaryne precursors with cyclopentadienones. The transformation involves controlled generation of one of the aryne functionalities, trapping by Die

Full text of DOI:10.1055/s-0034-1381005

SYNLETT
0
9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
© Georg Thieme Verlag Stuttgart · New York
2015, 26, 1633–1637
letter
1633
D. Rodríguez-Lojo et al.
Letter
Synlett
Straightforward Synthesis of Novel Acene-Based Aryne Precur-
sors
TfO
TMS
Ph
Diego Rodríguez-Lojo
Diego Peña*
TMS
OTf
Dolores Pérez*
Enrique Guitián
TMS
OTf
CsF, MeCN–CH2Cl2, 50 °C
44–60%
Ph
Ph
Ph
Centro de Investigación en Química Biolóxica e Materiais
Moleculares (CIQUS) and Departamento de Química
Orgánica, Facultade de Química, Universidade de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
diego.pena@usc.es
one single step
O
TMS
TMS
OTf
Ph
TMS
TMS
OTf
TfO
dolores.perez@usc.es
via
OTf
CsF, MeCN–CH2Cl2, 50 °C
21–40%
Dedicated to Prof. K. Peter C. Vollhardt
Ph
1–2
Received: 10.04.2015
Accepted after revision: 16.05.2015
Published online: 11.06.2015
quired longer, less efficient synthetic routes. Here we report
a straightforward method for the synthesis of extended
polycyclic o-(trimethylsilyl)aryl triflates by means of con-
trolled [4+2] cycloadditions between cyclopentadienones
and bistriflates 112 or 2 (Figure 1),13 which are formal pre-
cursors of the 1,4-benzodiyne and 2,6-naphthodiyne, re-
spectively.
DOI: 10.1055/s-0034-1381005; Art ID: st-2015-b0262-l
Abstract Large polycyclic o-(trimethylsilyl)aryl triflates are easily ob-
tained by reaction of commercially available bisaryne precursors with
cyclopentadienones. The transformation involves controlled generation
of one of the aryne functionalities, trapping by Diels–Alder reaction
with a dienone, and chelotropic extrusion of CO. The newly synthesized
triflates are precursors of acene-based arynes, including a didehydro-
pentacene.
TfO
TMS
OTf
TfO
OTf
TMS
TMS
TMS
Key words arynes, polycyclic aromatic hydrocarbons, acenes, Diels–
Alder reaction, cycloadditions
2
1
Figure 1
In recent years the chemistry of arynes1 has experi-
enced a significant resurgence mainly due to the availabili-
ty of suitable methods for their generation.2 Most of the
work published in the last decade used the fluoride-
induced elimination from o-(trimethylsilyl)aryl triflates for
the generation of arynes and hetarynes under mild condi-
tions. This method, first described by Kobayashi et al.3 and
further developed by our group and others, spelled the dis-
covery of novel reaction venues, including metal-catalyzed
transformations,4,5 and facilitated the application of aryne
chemistry to the synthesis of complex natural products6
and novel polycyclic aromatic systems.7
The preparation of simple o-(trimethylsilyl)aryl triflates
is usually achieved in one or two synthetic steps from the
corresponding o-bromophenols8 which, in many cases, are
accessible by selective o-bromination of phenols. This pro-
cedure has been proved useful for the synthesis of a variety
of benzyne, naphthyne, or phenanthryne precursors, start-
ing from easily available phenols, naphthols, or phenan-
throls. The preparation of slightly more complex polycyclic
o-(trimethylsilyl)aryl triflates, such as the precursors of
2,3-triphenylyne,9 2,3-biphenylyne,10 or corannulyne,11 re-
In the course of one of our research projects, focused to
the synthesis of large polycyclic aromatic hydrocarbons
(PAH) with application in organic electronics, we recently
reported the use of the masked bisbenzyne approach for
the synthesis of the benzotriphenylyne precursor 3.14
Thus, treatment of cyclopentadienone 415 with 3-bro-
mo-4-hydroxy-6-(trimethylsilyl)phenyl triflate (5) and
TBAF afforded bromophenol 6, through a [4+2] cycloaddi-
tion of the dienone with aryne 7, followed by chelotropic
decarbonylation (Scheme 1, route A).
Transformation of 6 into the corresponding o-(trimeth-
ylsilyl)aryl triflate following our general established proto-
col,8 afforded benzotriphenylyne precursor 3 in 30% overall
yield, which was subsequently subjected to palladium-cata-
lyzed cyclotrimerization to build a clover-shaped 16-ring
nanographene. In an attempt to synthetize 3 more effi-
ciently, we explored the reaction of
4 with 2,5-
bis(trimethysilyl)-1,4-phenylene bis(triflate) (1), under
controlled conditions for the selective generation and trap-
ping of functionalized monoaryne 8. Successfully, we found
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1633–1637

1634
D. Rodríguez-Lojo et al.
Letter
Synlett
knowledge – no example of an efficient single fluoride-
induced elimination to generate intermediate 8 had been
described prior to our work.18
A
Ph
Ph
1) TBAF, r.t.
2) DCE, reflux
TfO
Br
+
Application of the same protocol to the reaction of 1
with other dienones, such as the commercially available
2,3,4,5-tetraphenylcyclopentadienone (10) and the easily
accessible 9,11-diphenyl-10H-cyclopenta[e]pyren-10-one
(11),19 afforded the corresponding o-(trimethylsilyl)aryl tri-
flates 12 and 13 in 60% and 44% yields, respectively (Table 1,
entries 1 and 3). As mentioned above, compound 3 is a con-
venient precursor of the dibenzofused 2,3-didehydroan-
thracene 15 as demonstrated in the synthesis of a [16]clo-
verphene.14 On the other hand, the tetraphenylnapthyne
14, which can be generated from 12, and the bisbenzotetra-
cyne 16, available through 13, had been obtained before
from other precursors20,21 and employed in Diels–Alder re-
actions for the synthesis of stable, phenyl-substituted
and/or benzoannulated large acenes.
O
TMS
OH
Br
5
4
via
OH
7
B
Ph
1, CsF
Br
MeCN–CH2Cl2,
50 °C
OH
TMS
OTf
Ph
via
6 (44%)
8
1) HMDS
Ph
In order to extend the polycyclic aryne core towards
larger acenes, we explored the reactions of the 2,6-naph-
thodiyne precursor 2. Satisfyingly, treatment of 2 with 120
mol% CsF in the presence of dienes 4, 10, and 11 under sim-
ilar controlled conditions, afforded the corresponding o-
(trimethylsilyl)aryl triflates 17–19 as major products in
reasonable yields (Table 1, entries 4–6).22 Remarkably, tri-
flate 19 is a stable, functionalized pentacene23 and a poten-
tial precursor of the large pentacene-based aryne 22. The
UV/vis spectra of 19 showed the lowest-energy absorption
band at λonset = 484 nm, with a band gap of 2.56 eV, slightly
lower than the HOMO–LUMO gap of a previously described
pyrene-terminated pentacene (Figure 2).24 On the other
hand, cyclic voltammetry (CV) showed a reversible reduc-
tion process at E1/2red = –1.48 V.
2) i. n-BuLi
ii. Tf2O
TMS
OTf
58%
one single step
70% (30% overall)
Ph
3
O
Ph
R2
OR1
9a, R1 = H, R2 = Br
9b, R1 = Tf, R2 = TMS
Ph
9
Scheme 1 Synthesis of 3. (A) Two-step procedure (masked bisbenzyne
approach);14 (B) one-step procedure using bistriflate 1.
that treatment of 1 with 120 mol% anhydrous CsF in a
MeCN–CH2Cl2 mixture (2:1), in the presence of 1,3-diphe-
nyl-2H-cyclopenta[l]phenanthren-2-one (4), afforded tri-
flate 3 in 58% yield (Scheme 1, route B).
The choice of the solvent mixture and the use of CsF as
fluoride source seem to be crucial for the success of this
chemoselective transformation.17 On the one hand, CsF is
only slightly soluble under these conditions, which allows
the slow generation of the aryne. On the other hand, the
lower solubility of the reaction products (with respect to
the reagents) promotes their partial precipitation from the
reaction mixture and minimizes the possibility of generat-
ing a second aryne.
Figure 2 Electronic properties of pentacene 19. (a) Absorption (solid
line) and emission (dashed line) spectra in CH2Cl2; (b) cyclic voltammo-
gram in CH2Cl2/0.1 M Bu4NPF6 using AgCl/Ag as the reference elec-
trode.
The reaction proceeds via [4+2] cycloaddition reaction
of monoaryne 8 to cyclopentadienone 4, followed by chelo-
tropic extrusion of carbon monoxide. In some experiments,
the intermediate cycloadduct 9 can be detected and forced
to evolve towards 3 upon additional heating. It is worth to
note that bistriflate 1 had been previously used as 1,4-bis-
benzyne synthon equivalent in a double Diels–Alder reac-
tion to build a stable twistacene,12 but – to the best of our
In conclusion, an expeditious method for the synthesis
of novel polycyclic o-(trimethylsilyl)aryl triflates, based on
the controlled reaction of a formal bisaryne precursor with
cyclopentadienones, has been described. The application of
these compounds to the synthesis of novel acene, phene,
and starphene derivatives by means of aryne cycloaddition
reactions will be reported in due course.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1633–1637

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D. Rodríguez-Lojo et al.
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Table 1 Reaction of Bistriflates 1 and 2 with Cyclopentadienones16
Entry Bisaryne precursor Cyclopentadienone
Product
Yield (%) Derived aryne
Ph
Ph
Ph
Ph
Ph
Ph
Ph
TMS
OTf
O
1
1
60
Ph
Ph
Ph
Ph
Ph
10
12
14
Ph
Ph
Ph
Ph
Ph
TMS
O
2
1
58
OTf
Ph
3
4
15
Ph
Ph
Ph
Ph
TMS
O
3
4
5
6
1
2
2
2
44
OTf
Ph
Ph
13
11
10
16
Ph
Ph
Ph
Ph
Ph
TMS
OTf
40
Ph
Ph
Ph
17
20
Ph
Ph
Ph
TMS
OTf
4
21
Ph
18
21
Ph
Ph
Ph
TMS
11
24
OTf
Ph
19
22
Acknowledgment
Supporting Information
Financial support from the Spanish Ministry of Science and Competi-
tiveness (MINECO, CTQ2013-44142-P and MAT2013-46593-C6-6-P),
the European Union (Project PAMS, contract no. 610446), Xunta de
Galicia (GPC2014/25), and FEDER is gratefully acknowledged. D.R.-L.
thanks the Spanish Ministry of Education for the award of an FPU fel-
lowship.
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0034-1381005.
S
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p
p
ortiInfogrmoaitn
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References and Notes
additional portion of o-(trimethylsilyl)aryl triflate.
9,14-Diphenyl-12-(trimethylsilyl)benzo[f]tetraphen-11-yl
Trifluoromethanesulfonate (3)
(1) General reviews on aryne chemistry: (a) Hoffmann, R. W. Dehy-
drobenzene and Cycloalkynes; Academic Press: New York, 1967.
(b) Hart, H. The Chemistry of Triple-Bonded Functional Groups, In
Arynes and Heteroarynes; Patai, S.; Rappoport, Z., Eds.; Wiley:
Chichester, 1994, Suppl. C2 1017. (c) Pellisier, H.; Santelli, M.
Tetrahedron 2003, 59, 701. (d) Sanz, R. Org. Prep. Proced. Int.
2008, 40, 215.
(2) Kitamura, T. Aust. J. Chem. 2010, 98, 987.
(3) Himeshima, Y.; Sonoda, T.; Kobayashi, H. Chem. Lett. 1983,
1211.
(4) Representative metal-catalyzed transformations involving
arynes: (a) Peña, D.; Escudero, S.; Pérez, D.; Guitián, E.; Castedo,
L. Angew. Chem. Int. Ed. 1998, 37, 2659. (b) Peña, D.; Pérez, D.;
Guitián, E.; Castedo, L. J. Am. Chem. Soc. 1999, 121, 5827.
(c) Yokinawa, E.; Yamamoto, Y. Angew. Chem. Int. Ed. 2000, 39,
173. (d) Peña, D.; Pérez, D.; Guitián, E. Palladium-Catalyzed Cyc-
loaddition Reactions of Arynes, In Palladium in Organic Synthesis;
Vol. 14; Tsuji, J., Ed.; Springer: Weinheim, 2005, 109. (e) Liu, Z.;
Larock, R. C. J. Org. Chem. 2007, 72, 223. (f) Yoshida, H.; Ohshita,
J.; Kunai, A. Bull. Chem. Soc. Jpn. 2010, 83, 199. (g) Worlikar, S. A.;
Larock, R. C. Current. Org. React. 2011, 15, 3214.
(5) Representative novel metal-free transformations: (a) Peña, D.;
Pérez, D.; Guitián, E. Angew. Chem. Int. Ed. 2006, 45, 3579.
(b) Bhunia, A.; Yetra, S. R.; Biju, A. T. Chem. Soc. Rev. 2012, 41,
3140. (c) Bhunia, A.; Biju, A. T. Synlett 2014, 25, 608. (d) Criado,
A.; Vilas-Varela, M.; Cobas, A.; Pérez, D.; Peña, D.; Guitián, E. J.
Org. Chem. 2013, 78, 12637. (e) Dubrovskiy, A. V.; Markina, N.
A.; Larock, R. C. Org. Biomol. Chem. 2013, 11, 191.
Reaction of 1,3-diphenyl-2H-cyclopenta[l]phenanthren-2-one
(4, 243 mg, 0.637 mmol), 2,5-bis(trimethylsilyl)-1,4-phenylene
bis(trifluoromethanesulfonate) (1, 300 mg, 0.579 mmol), and
CsF (105 mg, 0.695 mmol) in MeCN–CH2Cl2 (2:1; 9 mL) afforded
3 (218 mg, 58%) as a greenish solid; mp 219–221 °C. 1H NMR
(250 MHZ, CDCl3): δ = 8.29 (d, J = 7.3 Hz, 2 H), 8.13 (s, 1 H), 7.85
(s, 1 H), 7.59 (d, J = 8.5 Hz, 2 H), 7.54 (m, 5 H), 7.54 (m, 5 H),
7.41–7.36 (m, 2 H), 7.04–6.98 (m, 2 H), 0.33 (s, 9 H) ppm. 13C
NMR (63 MHz, CDCl3): δ = 152.6 (C), 140.9 (C), 140.5 (C), 136.8
(CH), 135.4 (C), 135.2 (C), 132.7 (C), 132.3 (2 CH), 132.2 (C),
132.1 (2 CH), 132.1 (C), 131.9 (C), 130.8 (C), 130.6 (C), 130.55
(C), 130.50 (CH), 130.4 (CH), 129.8 (C), 129.3 (C), 129.1 (2 CH),
129.0 (2 CH), 128.0 (CH), 127.9 (CH), 127.3 (CH), 127.2 (CH),
125.9 (2 CH), 123.3 (2 CH), 115.7 (CH), –0.8 (3 CH3) ppm. MS
(EI): m/z (%) = 650 (30). HRMS (EI): m/z calcd for C38H29F3O3SSi:
650.1559; found: 650.1563.
5,6,7,8-Tetraphenyl-3-(trimethylsilyl)naphthalen-2-yl Triflu-
oromethanesulfonate (12)
Reaction of 2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-one (10,
329 mg, 0.858 mmol), 2,5-bis(trimethylsilyl)-1,4-phenylene
bis(trifluoromethanesulfonate) (1, 404 mg, 0.780 mmol), and
CsF (142 mg, 0.936 mmol) in MeCN–CH2Cl2 (2:1; 11 mL)
afforded 12 (305 mg, 60%) as a white solid; mp 249–251 °C. 1H
NMR (300 MHZ, CDCl3): δ = 7.89 (s, 1 H), 7.59 (s, 1 H), 7.32–7.20
(m, 10 H), 6.92–6.87 (m, 10 H), 0.30 (s, 9 H) ppm. 13C NMR (75
MHz, CDCl3): δ = 152.8 (C), 140.7 (C), 139.9 (4C), 138.7 (2 C),
138.5 (C), 138.3 (C), 136.9 (CH), 133.4 (C), 131.1 (3 CH), 131.1 (4
CH), 130.9 (2 CH), 130.5 (C), 127.7 (2 CH), 127.6 (2 CH), 126.9
(CH), 126.7 (4 CH), 125.7 (CH), 125.6 (CH), 118.4 (q, J = 320 Hz,
CF3), 116.3 (CH), –0.9 (3 CH3) ppm. MS (EI): m/z (%) = 652.3 (70)
[M+], 504.3 (14), 293.3 (41), 147.1 (43). HRMS (EI): m/z calcd for
(6) (a) Tadross, P. M.; Stoltz, B. M. Chem. Rev. 2012, 112, 3550.
(b) Gampe, C. M.; Carreira, E. M. Angew. Chem. Int. Ed. 2012, 51,
3766.
(7) (a) Pérez, D.; Peña, D.; Guitián, E. Eur. J. Org. Chem. 2013, 5981.
(b) Li, J.; Zhang, Q. Synlett 2013, 24, 686.
C
38H31F3O3SSi: 652.1715; found: 652.1713.
(8) Peña, D.; Cobas, A.; Pérez, D.; Guitián, E.; Castedo, L. Synthesis
2002, 1454.
(9) Romero, C.; Peña, D.; Pérez, D.; Guitián, E. Chem. Eur. J. 2006, 12,
5677.
(10) Iglesias, B.; Cobas, A.; Pérez, D.; Guitián, E.; Vollhardt, K. P. C.
Org. Lett. 2004, 6, 3557.
(11) Sygula, A.; Sygula, R.; Kobryn, L. Org. Lett. 2008, 10, 3927.
(12) Duong, H. M.; Bendikov, M.; Steiger, D.; Zhang, Q.; Sonmez, G.;
Yamada, J.; Wudl, F. Org. Lett. 2003, 5, 4433.
(13) Kitamura, C.; Abe, Y.; Ohara, T.; Yoneda, A.; Kawase, T.;
Kobayashi, T.; Naito, H.; Komatsu, T. Chem. Eur. J. 2010, 16, 890.
(14) Alonso, J. M.; Díaz-Álvarez, A. E.; Criado, A.; Peña, D.; Pérez, D.;
Guitián, E. Angew. Chem. Int. Ed. 2012, 51, 173.
(15) Wooi, G. Y.; White, J. M. Org. Biomol. Chem. 2005, 3, 972.
(16) General Procedure
9,14-Diphenyl-12-(trimethylsilyl)dibenzo[de,qr]tetracen-11-
yl Trifluoromethanesulfonate (13)
Reaction of 9,11-diphenyl-10H-cyclopenta[e]pyren-10-one (11,
100 mg, 0.246 mmol), 2,5-bis(trimethylsilyl)-1,4-phenylene
bis(trifluoromethanesulfonate) (1, 116 mg, 0.224 mmol), and
CsF (41 mg, 0.269 mmol) in MeCN–CH2Cl2 (2:1; 9 mL) afforded
13 (66 mg, 40%) as a yellow solid; mp 279–281 °C. 1H NMR (500
MHZ, CDCl3): δ = 8.11 (s, 1 H), 7.90–7.85 (m, 6 H), 7.82 (s, 1 H),
7.56–7.48 (m, 10 H), 7.35 (td, J = 7.9, 2.2 Hz, 2 H), 0.32 (s, 9 H)
ppm. 13C NMR (126 MHz, CDCl3): δ = 153.0 (C), 141.7 (C), 141.4
(C), 137.3 (CH), 136.9 (C), 136.6 (C), 133.2 (C), 132.4 (2 CH),
132.2 (2 CH), 131.0 (C), 131.0 (C), 130.99 (C) 130.97 (C), 130.3
(C), 130.2 (C), 130.1 (C), 129.9 (C), 129.5 (2 CH), 129.4 (2 CH),
129.1 (CH), 129.0 (CH), 128.2 (CH), 128.1 (CH), 127.1 (CH),
127.1 (CH), 126.6 (CH), 126.4 (CH), 126.2 (C), 126.1 (C), 125.1
(CH), 125.0 (CH), 118.5 (q, J = 325 Hz, CF3), 116.1 (CH), –0.6 (3
CH3) ppm. MS (EI): m/z (%) = 674 (100) [M+], 541 (53), 448 (16).
5,6,7,8-Tetraphenyl-3-(trimethylsilyl)anthracen-2-yl Trifluo-
romethanesulfonate (17)
Reaction of 2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-one (10,
126 mg, 0.329 mmol), 3,6-bis(trimethylsilyl)-naphthalene-2,7-
diyl bis(trifluoromethanesulfonate) (2, 115 mg, 0.299 mmol),
and CsF (55 mg, 0.359 mmol) in MeCN–CH2Cl2 (2:1; 9 mL)
afforded 17 (84 mg, 40%) as a white solid; mp 223–225 °C. 1H
NMR (300 MHZ, CDCl3): δ = 8.27 (s, 1 H), 8.22 (s, 1 H), 8.04 (s, 1
H), 7.82 (s, 1 H), 7.39–7.21 (m, 10 H), 7.01–6.78 (m, 10 H), 0.43
(s, 9 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 152.4 (C), 140.5 (2
C), 139.91 (C), 139.59 (C), 139.52 (C), 139.4 (C), 139.0 (CH),
To a solution of bisaryne precursor 1 or 2 and cyclopentadien-
one 4, 10, or 11 (110 mol%), in 2:1 MeCN–CH2Cl2, finely pow-
dered anhydrous CsF (120 mol%) was added, and the mixture
was stirred at 50 °C under argon atmosphere for 12 h. The
solvent was evaporated under reduced pressure, and the result-
ing mixture was purified by column chromatography (SiO2,
hexanes–CH2Cl2) to isolate the corresponding o-(trimethylsi-
lyl)aryl triflate. In some experiments, the intermediate Diels–
Alder adduct (e.g., 9) was detected in other fractions eluted
from the column, which were collected, concentrated under
vacuum, dissolved in tetrachloroethane, and refluxed for 12 h.
Evaporation of the solvent under vacuum and column chroma-
tography (SiO2, hexanes–CH2Cl2) of the residue afforded an
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1633–1637

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D. Rodríguez-Lojo et al.
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Synlett
138.6 (C), 138.3 (C), 132.1 (C), 131.7 (C), 131.6 (CH), 131.6 (CH),
131.4 (CH), 129.6 (C), 128.1 (CH), 128.0 (CH), 127.0 (CH), 126.9
(CH), 126.9 (CH), 126.8 (CH), 126.4 (CH), 125.7 (CH), 116.2 (CH),
–0.4 (3 CH3) ppm. MS (MALDI-TOF): m/z = 702 [M+].
9,16-Diphenyl-13-(trimethylsilyl)dibenzo[a,c]tetracen-12-yl
Trifluoromethanesulfonate (18)
130.1 (C), 129.7 (CH), 129.6 (CH), 129.4 (CH), 129.3 (CH), 128.2
(CH), 128.1 (CH), 127.0 (CH), 127.0 (CH), 126.7 (CH), 126.6 (CH),
126.6 (CH), 126.4 (C), 126.3 (C), 126.1 (CH), 125.1 (CH), 125.1
(C), 118.2 (q, J = 322 Hz, CF3), 116.29 (CH), 116.28 (CH), –0.43 (3
CH3) ppm. MS (MALDI-TOF): m/z = 724 [M+].
(17) The use of neat MeCN or CH2Cl2 resulted in lower conversions
due to the poor solubility of either the diene (in MeCN) or the
CsF (in CH2Cl2). On the other hand the use of TBAF as the fluo-
ride source afforded lower yields of the expected triflates.
(18) In parallel to the work described in this article, we also studied
the generation of a naphtho[1,2,3,4-ghi]perylyne precursor by
reaction of 8 with perylene: Schuler, B.; Collazos, S.; Gross, L.;
Meyer, G.; Pérez, D.; Guitián, E.; Peña, D. Angew. Chem. Int. Ed.
2014, 53, 9004.
Reaction of 1,3-diphenyl-2H-cyclopenta[l]phenanthren-2-one
(4, 148 mg, 0.388 mmol), 3,6-bis(trimethylsilyl)-naphthalene-
2,7-diyl bis(trifluoromethanesulfonate) (2, 200 mg, 0.353
mmol), and CsF (65 mg, 0.424 mmol) in MeCN–CH2Cl2 (2:1; 9
mL) afforded 18 (50 mg, 21%) as a yellow solid. 1H NMR (500
MHZ, CDCl3): δ = 8.51 (s, 1 H), 8.46 (s, 1 H), 8.18 (d, J = 7.9 Hz, 2
H), 8.05 (s, 1 H), 7.84 (s, 1 H), 7.66–7.54 (m, 10 H), 7.42 (t, J = 8.0
Hz, 2 H), 7.32 (t, J = 7.5 Hz, 2 H), 6.95 (t, J = 7.7 Hz, 2 H), 0.43 (s, 9
H) ppm. 13C NMR (126 MHz, CDCl3): δ = 152.4 (C), 141.6 (2 C),
141.5 (2 C), 139.0 (CH), 135.4 (C), 135.0 (C), 133.0 (2 CH), 133.0
(2 CH), 132.6 (C), 132.6 (C), 131.8 (C), 131.5 (C), 131.5 (C), 131.4
(C), 131.2 (C), 131.0 (CH), 130.9 (CH), 130.0 (C), 129.6 (2 CH),
129.5 (2 CH), 128.3 (CH), 128.2 (CH), 128.06 (C), 127.6 (CH),
127.6 (CH), 126.5 (CH), 126.3 (CH), 126.0 (CH), 123.7 (CH),
118.2 (q, J = 321 Hz, CF3), 116.3 (CH), –0.4 (CH3) ppm. MS
(MALDI-TOF): m/z = 700 [M+].
(19) Pascal, R. A. Jr.; McMillan, W. D.; Van Engen, D.; Eason, R. G.
J. Am. Chem. Soc. 1987, 109, 4660.
(20) Miao, Q.; Chi, X.; Xiao, S.; Zeis, R.; Lefernfeld, M.; Siegrist, T.;
Steigerwald, M. L.; Nuckolls, C. J. Am. Chem. Soc. 2006, 128, 1340.
(21) (a) Zhang, Q.; Divayana, Y.; Xiao, J.; Wang, Z.; Tiekink, E. R. T.;
Doung, H. M.; Zhang, H.; Boey, F.; Sun, X. W.; Wudl, F. Chem. Eur.
J. 2010, 16, 7422. (b) Xiao, J.; Liu, S.; Liu, Y.; Ji, L.; Liu, X.; Zhang,
H.; Sun, X.; Zhang, Q. Chem. Asian J. 2012, 7, 561. (c) Xiao, J.;
Duong, H. M.; Liu, Y.; Shi, W.; Ji, L.; Li, G.; Li, S.; Liu, X.-W.; Ma, J.;
Wudl, F.; Zhang, Q. Angew. Chem. Int. Ed. 2012, 51, 6094.
(22) We have already employed triflate 17 as an efficient precursor
of tetraphenylanthracyne 20, in the synthesis of large benzo-
fused acenes: Rodríguez-Lojo, D. R.; Pérez, D.; Peña, D.; Guitián,
E. Chem. Commun. 2015, 51, 5418.
(23) Pentacene and larger acenes are paradigmatic organic semicon-
ductors, although their poor solubility and low stability limit
their application: Anthony, J. E. Angew. Chem. Int. Ed. 2008, 47,
452.
(24) Xiao, J.; Divayana, Y.; Zhang, Q.; Doung, H. M.; Zhang, H.; Boey,
F.; Sun, X. W.; Wudl, F. J. Mat. Chem. 2010, 20, 8617.
9,16-Diphenyl-13-(trimethylsilyl)dibenzo[de,uv]pentacen-
12-yl Trifluoromethanesulfonate (19)
Reaction of 9,11-diphenyl-10H-cyclopenta[e]pyren-10-one (11,
118 mg, 0.290 mmol), 3,6-bis(trimethylsilyl)-naphthalene-2,7-
diyl bis(trifluoromethanesulfonate) (2, 150 mg, 0.264 mmol),
and CsF (48 mg, 0.317 mmol) in MeCN–CH2Cl2 (2:1; 9 mL)
1
afforded 19 (46 mg, 24%) as a yellow solid. H NMR (500 MHZ,
CDCl3): δ = 8.52 (s, 1 H), 8.47 (s, 1 H), 8.06 (s, 1 H), 7.85 (m, 3 H),
7.82 (d, J = 7.7 Hz, 2 H), 7.73 (t, J = 8.4 Hz, 2 H), 7.65–7.57 (m, 10
H), 7.29 (td, J = 7.9, 1.2 Hz, 2 H), 0.44 (s, 9 H) ppm. 13C NMR (126
MHz, CDCl3): δ = 152.4 (C), 142.1 (C), 142.0 (C), 139.1 (CH),
136.6 (C), 136.6 (C), 132.8 (2 CH), 132.76 (2 CH), 132.0 (C), 131.6
(C), 131.6 (C), 131.3 (C), 131.0 (C), 130.9 (C), 130.4 (C), 130.4 (C),
© Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, 1633–1637