Three-Fold Scholl-Type Cycloheptatriene Ring Formation around a Tribenzotriquinacene Core: Toward Warped Graphenes

Article abstract of DOI:10.1021/jacs.6b05820

A nonplanar polycyclic aromatic compound 6 bearing a tribenzotriquinacene (TBTQ) core merged with an o,p,o,p,o,p-hexaphenylene belt was prepared and characterized by NMR spectroscopy and X-ray crystallography. The key synthesis step involves three Scholl-type cycloheptatriene ring formation steps of the 1,4,8-tris(3′,4′-dimethoxyphenyl)-TBTQ derivative 5. The bridging of each of the three TBTQ bays by 1,2-phenylene units in compound 6 gives rise to an unusual wizard hat shaped structure, which represents a promising key intermediate for the construction of nonplanar nanographene molecules bearing a TBTQ core.

Full text of DOI:10.1021/jacs.6b05820

Subscriber access provided by Northern Illinois University
Communication
Three-Fold Scholl-Type Cycloheptatriene Ring Formation around
a Tribenzotriquinacene Core – On the Way to Warped Graphenes
Ho-Wang Ip, Chun-Fai Ng, Hak-Fun Chow, and Dietmar Kuck
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.6b05820 • Publication Date (Web): 01 Aug 2016
Downloaded from http://pubs.acs.org on August 2, 2016
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a free service to the research community to expedite the
dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts
appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been
fully peer reviewed, but should not be considered the official version of record. They are accessible to all
readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered
to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published
in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just
Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor
changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers
and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors
or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Journal of the American Chemical Society is published by the American Chemical
Society. 1155 Sixteenth Street N.W., Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 5
Journal of the American Chemical Society
1
2
3
4
5
6
Three-Fold Scholl-Type Cycloheptatriene Ring Formation around a
Tribenzotriquinacene Core – On the Way to Warped Graphenes
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
†
†
†,
‡,
Ho-Wang Ip, Chun-Fai Ng, Hak-Fun Chow, * and Dietmar Kuck *
†
Department of Chemistry, Institute of Molecular Functional Materials, and The Center of Novel Functional Mole-
cules, The Chinese University of Hong Kong, Shatin, Hong Kong
‡
Department of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, 33615 Bielefeld, Germa-
ny
Supporting Information Placeholder
former case, unfavorable crowding and/or poor solubility of
ABSTRACT: A nonplanar polycyclic aromatic compound 6
the partially-fused intermediates may have prevented the
desired multiple ring fusion, while in the latter the failure
was attributed to steric inhibition when placing the bulky t-
butyl groups into the bay areas of the PAC unit.
bearing a tribenzotriquinacene (TBTQ) core merged with an
o,p,o,p,o,p-hexaphenylene
characterized by NMR
belt
spectroscopy
was
prepared
and
and
X-ray
crystallography. The key synthesis step involves three Scholl-
type cycloheptatriene ring formation steps of the 1,4,8-tris-
(3’,4’-dimethoxyphenyl)-TBTQ derivative 5. The bridging of
each of the three TBTQ bays by 1,2-phenylene units in
compound 6 gives rise to an unusual wizard hat-shaped
structure, which represents a promising key intermediate for
the construction of nonplanar nanographene molecules
bearing a TBTQ core.
Polycyclic aromatic compounds (PACs) possessing
a
curved π-surface have aroused immense interests for decades
1
due to their strained structures and unusual properties.
Curved PACs in the forms of spheres, tubes, hemi-spheres
and saddles are well-known morphologies of nanographenes
2
and their applications have been well-documented. These
curved molecules are mostly prepared by “bottom-up” strat-
egies because they offer better product homogeneity and
higher morphological control. Generally, the curved nature
of PACs can be induced by the presence of nonhexagonal
3
rings or by steric crowding between substituents in a con-
Figure 1. Successful (blue bonds) bay-bridging cyclohepta-
triene ring formation of the TBTQ-merged hexa-peri-
hexabenzocoronene 1 and unsuccessful (red bonds) cyclo-
heptatriene ring formation of the TBTQ precursor 2 and the
fenestrindane precursor 3.
4
gested PAC skeleton. Among the many synthetic protocols,
5
,6
the Scholl reaction is the most effective method to stitch a
delicately designed, loosely π-conjugated polyaryl ring sys-
tem to the curved PAC at the final stage of the synthesis. The
scope of the original Scholl method, which involved mostly
hexagonal ring formation, has been optimized and expanded
7
8
by Müllen and King. In contrast, there are only a few suc-
cessful examples of employing the Scholl conditions in pro-
moting heptagon ring formation. Several curved PACs pre-
pared via the formation of cycloheptatrienylidene rings had
Conceptually, a 2'-m-terphenylyl residue at the C-2 posi-
tion of the TBTQ skeleton (A in Chart 1) appears to be the
minimum prerequisite to site a phenyl ring into the to-be-
bridged bay region, although such an approach would create
entropic penalty against cycloheptatriene ring formation due
to the presence of two rotatable aryl-aryl bonds. On the
other hand, the entropic advantage of a conformationally
pre-organized phenyl substituent placed suitably at the C-1
position (B in Chart 1) may promise successful bridging of
the bay by Scholl-type cyclization. In this contribution, we
present the successful synthesis of two 1,4,8-tris-
(dimethoxyphenyl)-TBTQ derivatives, 4 and 5, the latter of
3
g,3k
4f
been reported by Itami
and Durola. Pursuing an early
idea to use tribenzotriquinacene (TBTQ) or fenestrindane
9
cores to construct warped graphene cuttings, one of us
recently disclosed the successful synthesis of the curved PAC
1 based on a single cycloheptatriene ring formation around a
1
0
TBTQ core (Figure 1). However, multiple cycloheptatriene
1
1
ring formation of the TBTQ derivative 2 or fenestrindane
1
2
congener 3 under similar Scholl conditions failed. In the
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 5
1
5
which underwent an unprecedented three-fold Scholl-type
cycloheptatriene ring formation, leading to the successful
synthesis of the non-planar PAC 6. Hence, the placement of
aryl groups at the various bay positions did indeed promote
the Scholl reaction. The resulting wizard hat-shaped mole-
cule 6, having methoxy groups on the rim, can serve as a key
intermediate toward the synthesis of further π-extended
enced a strong upfield shift (e.g. δ 7.5 → 5.7 for 5), while the
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
positions of the bridgehead proton signals were slightly
downfield shifted (δ 4.7 → 5.0 for 5) (Figures 2a and 2b).
H NMR spectra of the tris-(2’,3’-
dimethoxyphenyl)-TBTQ isomer 4 containing ortho-methoxy
1
Interestingly, the
substituents showed extreme signal broadening, but became
1
5
well resolved at 60 °C. This observation is attributed to the
hindered rotation about the newly formed aryl-aryl bonds
due to steric interaction of the ortho-methoxy groups within
the corresponding bays.
9,13
nonplanar nanographenes such as compound 7.
Chart 1. Strategies (A, B) and progress (4−6) for TBTQ
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
bay bridging towards warped graphene (7).
Scheme 1. Synthesis of 1,4,8-triaryl-substituted TBTQ
derivatives 4 and 5.
1
2
1
Tf
pyridine
2
O
MeO
OMe
HO
OH
BBr
3
CH Cl
A
B
2
2
2 2
CH Cl
MeO
HO
MeO
OMe MeO
OMe
OMe
OMe
8
9 (89%)
9
12
MeO
MeO
MeO
OMe
8
1
B(OH)
2
5
4
11a
2
, CsF, SPhos
TfO
OTf
4
5
(97%)
OMe
Pd(OAc)
OMe
MeO
5
OMe
dioxane, 100 °C
(89%)
TfO
4
MeO
10 (75%)
MeO
B(OH)2
17 18
OMe
OMe
11b
MeO
MeO
1
4
12
5
11
6
MeO
OMe
6
7
1,4,8-Trimethoxy-12d-methyltribenzotriquinacene 8, a key
intermediate for the preparation of compounds 4 and 5, was
prepared via the standard regiocontrolled double cyclization
method reported previously by us (Scheme 1).
9
c,14,15
This
compound was then subjected to demethylation with boron
tribromide to give the corresponding trihydroxy-TBTQ de-
rivative 9 in 89% yield. Subsequent reaction of 9 with triflic
anhydride gave the TBTQ-tris-triflate 10 in 75% yield. Based
on the previous findings that electron-rich aryl groups could
8
facilitate the classical Scholl reaction, dimethoxyphenyl
1
groups were introduced into the TBTQ skeleton. The Suzuki-
Miyaura coupling of compound 10 with two different di-
methoxyphenylboronic acids 11a and 11b were examined
under various conditions. Finally, it was found that a combi-
Figure 2. Stacked partial H NMR (CDCl , 400 MHz, 20 °C)
3
spectra of (a) tris-triflate 10, (b) tris-(3’,4’-dimethoxyphenyl)-
TBTQ 5, (c) singly bridged V-shaped TBTQ 13, and (d) triply
1
bridged TBTQ 6. Blue circles indicate H signals due to the
nation of Pd(OAc) –CsF–SPhos in dioxane at 100 °C for 5 d
2
inner bay protons, which exhibit upfield shifts after arylation
at C-1, C-4 and C-8 and disappear upon cycloheptatriene
was the optimum condition. Hence, compounds 4 and 5 were
obtained in 97% and 89% yield, respectively from tris-triflate
1
formation. Red squares indicate H signals due to the bridge-
1
0 and the corresponding boronic acid. All the synthesized
head protons before cycloheptatriene formation, which show
1
13
1
compounds were characterized by H and C NMR spectros-
copy and mass spectrometry and it was ensured that com-
plete three-fold coupling was achieved in both cases. Due to
the magnetic shielding effect of the aryl rings introduced, the
bay protons 5-H, 9-H and 12-H of compounds 4 and 5 experi-
downfield shifts after arylation. Green stars denote H signals
due to the upfield shifted bridgehead protons after cyclohep-
tatriene formation.
ACS Paragon Plus Environment

Page 3 of 5
Journal of the American Chemical Society
1
13
Scheme 2. DDQ−TfOH-promoted oxidative cyclohep-
tatriene ring formation reactions.
H and C NMR spectra of the C3v-symmetrical product 6
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
were highly simplified as compared to those of the non-
cyclized 5 or mono-cyclized 13 precursors. Hence, the proton
signals of 5-H, 9-H and 12-H disappeared, while the bridge-
head protons were shifted upfield to δ 4.4 (Figure 2d). Direct
treatment of compound 5 with excess DDQ (5.0 eq.) also
gave compound 6 in comparable yields (37%), but product
purification was tedious because of the presence of many
side products.
MeO
MeO
OMe
OMe
MeO
MeO
OMe
OMe
DDQ (1 eq.)
TfOH
Cl , 0 °C
OMe
OMe
OMe
CH
2
2
OMe
12 (36%)
4
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
MeO
MeO
OMe
OMe
MeO
MeO
OMe
OMe
DDQ (1 eq.)
TfOH
2 2
CH Cl , 0 °C
MeO
OMe
MeO
13 (65%)
DDQ (3 eq.)
TfOH, CH Cl , 0 °C
OMe
5
DDQ (5 eq.)
TfOH, CH Cl , 0 °C
2
2
2
2
6
(61%)
6 (37%)
The cycloheptatriene ring formation of the tris-
dimethoxyphenyl) derivatives 4 and 5 was tested under
different conditions. Several oxidative systems including
(
Figure 3. Crystal structure of 6: (a) side view with carbon
atom positions shown as 50% probability ellipsoids and (b)
top view; (c) convex-convex π−π interactions in crystal pack-
ing of 6; (d) molecular packing with hydrogen atoms and
solvent molecules (pyridine) omitted for clarity.
1
6
17
FeCl −MeNO /CH Cl ,
AlCl −Cu(OTf) /CS ,
3 2 2
3
2
2
2
18
19
MoCl /CH Cl and DDQ−TfOH/CH Cl were employed.
With FeCl as the oxidant, only starting material was recov-
ered. Use of AlCl −Cu(OTf) gave very messy product mix-
tures. Deeply-colored, highly insoluble solids were obtained
when MoCl5 was employed. In the end, the DDQ−TfOH
system turned out to be most promising. Hence, the tris-
5
2
2
2
2
3
3
2
The wizard hat-shaped molecular structure of 6 was un-
ambiguously confirmed by X-ray crystallography using a
single crystal obtained from a pyridine solution of 6 by slow
(
2’,3’-dimethoxyphenyl) 4 and tris-(3’,4’-dimethoxyphenyl)
1
5,20
derivatives 5, when treated with 1.0 eq. of DDQ, gave the V-
shaped mono-cyclized products 12 and 13 in 36% and 65%
yield, respectively (Scheme 2). The V-shaped structure of
evaporation at 20 °C (Figure 3).
The concave shape was
generated by the three indane wings of the central TBTQ
core, whereas the o,p,o,p,o,p-hexaphenylene rim, together
with the three heptagons of negative curvature, formed the
convex surface surrounding the TBTQ core. The depth of the
1
5
both compounds was confirmed by 2D NMR experiments.
1
Upon cycloheptatriene formation, it was found that the H
NMR signal of the bridgehead protons belonging to the sev-
en-membered rings experienced a significant shielding (e.g.,
δ 5.0 → 4.2 for compound 13) induced by the 4,5-dimethoxy-
21
hat was found to be 3.2 Å and the average dihedral angle
between two indane planes was 111.6°. In the crystal packing,
two neighboring molecules were packed with one molecule
facing up and the other facing down. One of the aromatic
rings of the original TBTQ core was found to stack in nearly
parallel face-centered fashion with another TBTQ aromatic
ring of the neighboring molecule, both via the convex faces.
The intermolecular π-π distance between the two rings is 3.7
Å. On the other hand, concave-concave π−π stacking was not
observed between any of the TBTQ aromatic rings and be-
tween any of the dimethoxy-substituted aromatic rings. The
three axes crossing the central carbon and the centers of the
outer peripheral indane C−C bonds meet each other at the
1
,2-phenylene bridge (Figure 2c). Despite numerous purifica-
tion attempts, compound 12 was always contaminated with
small amount (10%) of the starting material 4. Nevertheless,
the identity of 12 could be unambiguously confirmed by
15
various spectroscopic methods. Notably, singly bridged
isomers other than 12 and 13 were not found. The preference
for the V-shaped isomers may be attributed to the fact that
their formation involves electrophilic attack between the two
most electron-rich biphenyl and p-terphenyl units in 4 and 5.
Furthermore, products 12 and 13, having five aryl rings in
conjugation, should be thermodynamically more stable than
the unobserved regioisomers, which contain less such aryl
rings. Further treatment of 12 with DDQ (3.0 eq.) failed to
give the expected three-fold cyclization product. It is be-
lieved that the elusive cyclization product of 12 would suffer
from significant steric strain because of the presence of three
methoxy groups at the bay positions. In stark contrast, under
similar reaction conditions, compound 13 furnished the
three-fold cyclization product 6 in 61% yield. Moreover, we
were unable to identify any doubly cyclized products. The
structures of all compounds were again confirmed by NMR
1
5
central carbon at an angle of 78.0°. Comparing these data
with the parent hydrocarbon, 12d-methyltribenzo-
22
triquinacene, in which the axes cross at 87.2° and the hat
depth is 2.9 Å, reveals that the three-fold bay-bridged TBTQ
derivative 6 acquires an even more concave bowl structure.
As for the o,p,o,p,o,p-hexaphenylene rim, the dihedral angle
between two conjugated phenyl rings in 6 was found to be
between 40–45°, whereas the corresponding dihedral angles
of o,p,o,p,o,p-hexaphenylene, itself being a ‘des-neopentyl’
analog of 6, lie in the range of 40–75° according to theoretical
23
calculations. Hence the ortho- and para-phenylene rings
15
spectroscopy and mass spectrometry. In particular, both the
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 4 of 5
are oriented in a significantly more coplanar manner in com-
Chem. 2013, 5, 739–744. (h) Sakamoto, Y.; Suzuki, T. J. Am. Chem.
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
pound 6 as compared to the parent hydrocarbon.
Soc. 2013, 135, 14074–14077. (i) Miller, R. W.; Duncan, A. K.;
Schneebeli, S. T.; Gray, D. L.; Whalley, A. C. Chem. Eur. J. 2014, 20,
Compound 6 is soluble in most organic solvents, resulting
in an orange solution with weak purple fluorescence when
irradiated with UV light. In chloroform, four absorption
peaks at 238, 253, 273 and 300 nm could be resolved in the
3
705–3711. (j) Cheung, K. Y.; Xu, X.; Miao, Q. J. Am. Chem. Soc. 2015,
1
37, 3910–3914. (k) Kato, K.; Segawa, Y.; Scott, L. T.; Itami, K. Chem.
Asian J. 2015, 10, 1635–1639.
(4) (a) Pascal, R. A.; McMillan, W. D.; Van Engen, D. J. Am. Chem.
Soc. 1986, 108, 5652–5653. (b) Lu, J.; Ho, D. M.; Vogelaar, N. J.; Kraml,
C. M.; Pascal, R. A. J. Am. Chem. Soc. 2004, 126, 11168–11169. (c) Col-
lins, S. K.; Grandbois, A.; Vachon, M. P.; Côté, J.; Angew. Chem. Int.
Ed. 2006, 45, 2923–2926. (d) 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, 6094–6098. (e) Arslan, H.; Uribe-Romo, F. J.;
Smith, B. J.; Dichtel, W. R. Chem. Sci. 2013, 4, 3973–3978. (f) Pradhan,
A.; Dechambenoit, P.; Bock, H.; Durola, F. J. Org. Chem. 2013, 78,
2266–2274. (g) Fujikawa, T.; Segawa, Y.; Itami, K. J. Am. Chem. Soc.
1
5
UV-absorption spectrum. The low-energy absorption onset
was found to be 347 nm, reflecting a HOMO-LUMO gap of
3.57 eV. In the fluorescence spectrum, an emission maximum
was observed at 380 nm upon excitation at 300 nm. The
cyclic voltammogram of 6 in dichloromethane exhibits one
quasi-reversible oxidation wave with half-wave oxidation
potential of 1.09 V vs ferrocenium/ferrocene (first oxidation
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
5
onset at 0.82 eV). The HOMO and LUMO energy levels of 6
1
5
2
015, 137, 7763–7768. (h) Kashihara, H.; Asada, T.; Kamikawa, K.
Chem. Eur. J. 2015, 21, 6523–6527.
5) Scholl, R.; Mansfeld, J. Ber. Dtsch. Chem. Ges. 1910, 43, 1734–1746.
were estimated to be −5.92 eV and −2.35 eV, respectively.
In summary, we reported the synthesis of an unprecedent-
ed wizard hat-shaped PAC 6 based on the TBTQ framework
using a three-fold Scholl-type cycloheptatriene formation
reaction. The structural features, crystallographic packing
modes, optical and electronic properties of the TBTQ-PAC 6
were also examined. This new synthetic protocol, in princi-
(
(6) Grzybowski, M.; Skonieczny, K.; Butenschön, H.; Gryko, D. T.
Angew. Chem. Int. Ed. 2013, 52, 9900–9930.
(7) (a) Iyer, V. S.; Wehmeier, M.; Brand, J. D.; Keegstra, M. A.;
Müllen, K. Angew. Chem. Int. Ed. 1997, 36, 1604–1607. (b) Simpson, C.
D.; Brand, J. D.; Berresheim, A. J.; Przybilla, L.; Räder, H. J.; Müllen,
K. Chem. Eur. J. 2002, 8, 1424–1429. (c) Yang, X.; Dou, X.;
Rouhanipour, A.; Zhi, L.; Räder, H. J.; Müllen, K. J. Am. Chem. Soc.
ple, could also be applied to C -symmetrical 1,5,9-triaryl-
3
14b,14c,24
TBTQ compounds as starting materials.
With the six
2
008, 130, 4216–4217. (d) Vo, T. H.; Shekhirev, M.; Kunkel, D. A.;
Orange, F.; Guinel, M. J. F.; Enders, A.; Sinitskii, A. Chem. Commun.
014, 50, 4172–4174. (e) Lorbach, D.; Keerthi, A.; Figueira-Duarte, T.
M.; Baumgarten, M.; Wagner, M.; Müllen, K. Angew. Chem. Int. Ed.
016, 55, 418–421.
methoxy groups available for further manipulations, exten-
sion of the curved aromatic surface to warped nanogra-
phenes such as 7 is underway in our laboratories.
2
2
ASSOCIATED CONTENT
(8) (a) Rempala, P.; Kroulík, J.; King, B. T. J. Am. Chem. Soc. 2004,
126, 15002–15003. (b) Rempala, P.; Kroulík, J.; King, B. T. J. Org. Chem.
Supporting Information
2006, 71, 5067–5081. (c) King, B. T.; Kroulík, J.; Robertson, C. R.;
Experimental details, NMR, X-ray, UV and cyclic voltamme-
try data (PDF)
Rempala, P.; Hilton, C. L.; Korinek, J. D.; Gortari, L. M. J. Org. Chem.
2007, 72, 2279–2288. (d) Ormsby, J. L.; Black, T. D.; Hilton, C. L.;
Bharat; King, B. T. Tetrahedron 2008, 64, 11370–11378.
(9) (a) Tellenbröker, J.; Kuck, D. Angew. Chem., Int. Ed. 1999, 38,
919–922. (b) Tellenbröker, J.; Kuck, D. Eur. J. Org. Chem. 2001, 1483–
1489. (c) Kuck, D. Chem. Rev. 2006, 106, 4885–4925.
AUTHOR INFORMATION
Corresponding Author
(
(
10) Mughal, E. U.; Kuck, D. Chem. Commun. 2012, 48, 8880–8882.
11) Mughal, E. U.; Neumann, B.; Stammler, H.-G.; Kuck, D. Eur. J.
*hfchow@cuhk.edu.hk
*dietmar.kuck@uni-bielefeld.de
Org. Chem. 2014, 2014, 7469–7480.
(12) An, P.; Chow, H.-F.; Kuck, D. Synlett 2016, 27, 1255–1261.
(13) Kirchwehm, Y.; Damme, A.; Kupfer, T.; Braunschweig, H.;
Krüger, A. Chem. Commun. 2012, 48, 1502–1504.
Notes
The authors declare no competing financial interests.
(
14) (a) Kuck, D. Angew. Chem. Int. Ed. 1984, 23, 508–509. (b) Xu, W.-
R.; Chow, H.-F.; Cao, X.-P.; Kuck, D. J. Org. Chem. 2014, 79, 9335–
346. (c) Xu, W.-R.; Chow, H.-F.; Cao, X.-P.; Kuck, D. J. Org. Chem.
015, 80, 4221–4222.
(15) See Supporting Information for details.
16) Feng, X.; Wu, J.; Enkelmann, V.; Müllen, K. Org. Lett. 2006, 8,
1145–1148.
17) Dötz, F.; Brand, J. D.; Ito, S.; Gherghel, L.; Müllen, K. J. Am.
Chem. Soc. 2000, 122, 7707–7717.
18) Kramer, B.; Averhoff, A.; Waldvogel, S. R. Angew. Chem. Int. Ed.
2002, 41, 2981–2982.
ACKNOWLEDGMENT
9
2
The work was supported by the UGC of HK (project no:
AoE/P-03/08).
(
REFERENCES
(
(
1) (a) Hirsch, A.; Soi, A.; Karfunkel, H. R. Angew. Chem. Int. Ed.
1992, 31, 766–768. (b) King, B. T.; Olmstead, M. M.; Baldridge, K. K.;
Kumar, B.; Balch, A. L.; Gharamaleki, J. A.; Chem. Commun. 2012, 48,
(
9
882–9884. (c) Scott, L. T. Chem. Soc. Rev. 2015, 44, 6464–6471.
(
(
19) Zhai, L.; Shukla, R.; Rathore, R. Org. Lett. 2009, 11, 3474–3477.
20) CCDC-1474467 contains the supplementary crystallographic
(
(
2) (a) Li, Z.; Liu, Z.; Sun, H.; Gao, C.; Chem. Rev. 2015, 115, 7046–7117.
b) Narita, A.; Wang, X.-Y.; Feng, X.; Müllen, K. Chem. Soc. Rev. 2015,
data for 6.
21) The hat depth is defined as the distance of the central quater-
4
4, 6616–6643. (c) Segawa, Y.; Yagi, A.; Matsui, K.; Itami, K. Angew.
Chem. Int. Ed. 2016, 55, 5136–5158.
3) (a) Yamamoto, K.; Saitho, Y.; Iwaki, D.; Ooka, T. Angew. Chem.
Int. Ed. 1991, 30, 1173–1174. (b) Tsefrikas, V. M.; Scott, L. T. Chem. Rev.
006, 106, 4868–4884. (c) Wu, Y.-T.; Siegel, J. S. Chem. Rev. 2006,
06, 4843–4867. (d) Bharat; Bhola, R.; Bally, T.; Valente, A.; Cyrański,
(
nary carbon atom to the plane defined by the three mid-points of the
C5−C6, C11−C12 and C17−C18 bonds of compound 6.
(
(
22) Brandenburg, J. G.; Grimme, S.; Jones, P. G.; Markopoulos, G.;
Hopf, H.; Cyranski, M. K.; Kuck, D.; Chem. Eur. J. 2013, 19, 9930–
938.
2
1
9
M. K.; Dobrzycki, Ł.; Spain, S. M.; Rempała, P.; Chin, M. R.; King, B.
T. Angew. Chem. Int. Ed. 2010, 49, 399–402 (e) Luo, J.; Xu, X.; Mao,
R.; Miao, Q. J. Am. Chem. Soc. 2012, 134, 13796–13803. (f) Feng, C.-N.;
Kuo, M.-Y.; Wu, Y.-T.; Angew. Chem. Int. Ed. 2013, 52, 7791–7794. (g)
Kawasumi, K.; Zhang, Q.; Segawa, Y.; Scott, L. T.; Itami, K. Nat.
(
(
23) Fujioka, Y. Bull. Chem. Soc. Jpn. 1984, 57, 3494–3506.
24) Markopoulos, G.; Henneicke, L.; Shen, J.; Okamoto, Y.; Jones, P.
G.; Hopf, H. Angew. Chem. Int. Ed. 2012, 51, 12884–12887.
ACS Paragon Plus Environment

Page 5 of 5
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
5
ACS Paragon Plus Environment