Structures, dynamic behavior, and spectroscopic properties of 1,8-Anthrylene-ethenylene cyclic dimers and their substituent effects1

Article abstract of DOI:10.1246/bcsj.20150245

Cyclic compounds consisting of two 1,8-anthrylene units and two ethenylene linkers were studied as ?-conjugated compounds. Three derivatives having substituents (H, Me, and Ph) at the linker moieties were synthesized by Suzuki?Miyaura coupling of the corr

Full text of DOI:10.1246/bcsj.20150245

Structures, Dynamic Behavior, and Spectroscopic Properties
of 1,8-Anthrylene-Ethenylene Cyclic Dimers
and Their Substituent Effects1
Masataka Inoue,1 Tetsuo Iwanaga,1 and Shinji Toyota*2
1Department of Chemistry, Faculty of Science, Okayama University of Science,
1-1 Ridaicho, Kita-ku, Okayama 700-0005
2Department of Chemistry and Materials Science, Tokyo Institute of Technology,
2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551
E-mail: stoyota@cms.titech.ac.jp
Received: July 17, 2015; Accepted: August 14, 2015; Web Released: August 21, 2015
Shinji Toyota
Professor Shinji Toyota studied chemistry at The University of Tokyo and received Master’s degree in 1988.
He became research assistant of Okayama University of Science in 1988. After he received Doctor’s degree
in 1992 from The University of Tokyo, he was promoted to professor in 2002. He stayed in University of
California, San Diego as visiting researcher in 1996–1997. In 2015, he moved to Tokyo Instituted of
Technology as professor. He is interested in physical organic chemistry, structural organic chemistry, and
stereochemistry.
Abstract
systems, trans-ethenylene linkers (-CH=CH-) have also been
occasionally utilized to connect the aromatic moieties.5 Because
this double bond linker has a nonlinear zigzag shape, the chain
shape and the conjugation are dependent on the conformation
about the single bonds. For anthrylene-ethenylene oligomers,
some acyclic and cyclic analogs were reported as novel
fluorophores and twisted systems.6 Another example of a cyclic
compound is 2, which was synthesized as a fused [14]annulene
in 1971 by Akiyama and Nakagawa.7 Although the authors
proposed a nonplanar structure on the basis of electronic
spectra, this cyclic compound has not been further investigated
for more than 40 years.
In order to revisit this compound, we introduced a 2,4,6-
trimethylphenyl (mesityl or Mes) group at the 10-position of
one of the anthracene units. This bulky group is known to
improve the solubility and stability of the attaching aromatic
moieties because it offers steric protection from molecular
stacking and external reagents.8 Another important role is that
the two methyl groups at the 2,6-positions (o-Me) serve as a
probe for the observation of dynamic behavior by NMR spec-
troscopy because the mesityl group is conformationally locked
relative to the anthracene group.9 Therefore, we selected com-
pound 3a bearing an extra 10-mesityl group as the main target
in the present study. We also synthesized its derivatives, 3b
and 3c, which have methyl and phenyl groups at the linker
moieties, respectively, and should influence the structures and
properties of the macrocyclic compounds. We herein report the
synthesis of soluble cyclic dimers 3 by cross coupling reactions
and the substituent effects on their structures, dynamic behav-
ior, and spectroscopic properties.
Cyclic compounds consisting of two 1,8-anthrylene units
and two ethenylene linkers were studied as π-conjugated com-
pounds. Three derivatives having substituents (H, Me, and Ph)
at the linker moieties were synthesized by Suzuki-Miyaura
coupling of the corresponding diethenylanthracene boronic
esters with 1,8-diiodo-10-mesitylanthracene. The X-ray analy-
sis and DFT calculations revealed that all the compounds
had nonplanar cyclic frameworks where the two ethenylene
linkers were syn to the anthracene units. Exchanges between
the two syn forms were observed from the line shape changes
in the 1H NMR signals of the mesityl group. Their barriers
increased in the order of H, Ph, and Me compounds from 34
to 70 kJ mol¹1. The effects of substituents on the molecular
structure, dynamic behavior, and electronic properties are
discussed.
We have concentrated our efforts on studies of cyclic
oligomers consisting of anthracene units and acetylene linkers
as novel π-conjugated compounds for about ten years.2 Based
on the molecular designs, we have constructed a large number
of fascinating cyclic systems by modifying the number of
aromatic units and the position and length of acetylene linkers.
We have synthesized cyclic oligomers ranging from dimers to
dodecamers having U-turn shaped 1,8-anthrylene units.2 As the
smallest cyclic oligomer, we reported cyclic dimer 1 (Figure 1)
with two ethynylene linkers (-C¸C-), which featured a rigid
and planar framework that produced characteristic absorption
and emission spectra.3,4 In the molecular design of π-conjugated
Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan | 1591

iPr
Mes
10
8
1
9
R
R
9'
8'
1'
a: R = H
b: R = Me
c: R = Ph
iPr
1
2
3
Figure 1. 1,8-Anthrylene cyclic dimers with various linkers (Mes: mesityl).
Bpin
R
Bpin
R
R
R
R
Bpin
Bpin
I
I
Bpin
5
[Pd(PtBu3)2]
iPr2NH
toluene
6a
6c'
R = Ph
4
R = H 86%
R
R
Bpin
R
Bpin
(Bpin)2
CuCl, PPh3,
NaOtBu
R
a: R = H
b: R = Me
c: R = Ph
MeOH
THF
b: 93%
c: 28%
7
6
Mes
Bpin
R
Bpin
R
[Pd(PPh3)4]
I
I
Cs2CO3
toluene, H2O
1.0 x 10–4 mol L–1
+
R
R
a: 33% (25%)
b: 51% (40%)
c: 63% (54%)
Mes
3
6
8
¹1
Scheme 1. Synthesis of cyclic dimers 3 (Bpin: 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-1-yl group. Yields at 1.0 © 10¹3 mol L are
given in parentheses).
stituted boronic esters, but the reaction with 5b proceeded very
slowly and the reaction with 5c gave undesired stereoisomer
Results and Discussion
Synthesis. Compound 2 had been synthesized by the Wittig
reaction of dialdehyde and diylide of anthracene derivatives via
several steps in the original literature.7 In order to decrease the
number of reaction steps and facilitate the structural modifica-
tion, we adopted cross coupling reactions. Compounds 3 were
synthesized by cyclization via the Suzuki-Miyaura coupling
of diboronic esters 6 and diiodoanthracene 810 (Scheme 1).
Compound 6a was readily prepared by the Heck reaction of
1,8-diiodoanthracene (4) and ethenylboronic ester 5a in 86%
yield.11 This coupling reaction was also carried out with sub-
6c¤.12 Therefore, we utilized the addition reactions of 1,8-
diethynylanthracene derivatives 7. Although hydroborations
of 7b and 7c with pinacolborane under some conditions were
unsuccessful,13 the reactions with bis(pinacolate)diboron in the
presence of CuCl gave the desired products in good yield for
6b and in low yield for 6c.14 In the latter case, the formation of
regioisomers lowered the isolated yield of 6c.
Thus prepared diboronic esters 6 were cyclized with 8,
which was prepared from 4,5-diiodo-9-anthrone and mesityl-
magnesium bromide, by the Suzuki-Miyaura coupling. The
1592 | Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan

1.5
1.0
(a)
(b)
0.5
0
240
320
400
480
400
480
560
640
/ nm
/ nm
¹1
Figure 2. UV-vis (a) and fluorescence (b) spectra of 3a (black), 3b (blue), and 3c (red) in CHCl3 at 1.0 © 10¹5 mol L (UV-vis)
¹1
and 1.0 © 10¹6 mol L (FL).
Table 1. UV-vis and fluorescence spectral data of 3 and 2 in chloroform
UV-vis
max/nm (¾)a)
FL
Stokes shift
Compound
¹1
-
-
edge/nmb)
-max/nm
Φfc)
/nm [cm
]
3a
3b
3c
2
417 (19000)
398 (16500)
400 (17000)
413 (14800)
466
421
435
461
491
438
478
484
0.71
0.82
0.39
0.67
74 [3610]
40 [2300]
78 [4080]
71 [3550]
a) Wavelengths and molar extinction coefficients of the absorption at the longest wavelength. b) Wavelengths at
peak edge (5% intensity of the maximum peak). c) Absolute fluorescence quantum yield.
reaction with [Pd(PPh3)4] as catalyst and Cs2CO3 as base
afforded the desired cyclic products in moderate yields.11 The
yields were slightly increased to 33-63% under the low con-
centration conditions (1.0 © 10¹4 mol L¹1). Compounds 3 were
obtained as a yellow solid, and their structures were elucidated
on the basis of spectroscopic data. Compound 2 was similarly
synthesized from 6a and 1,8-diiodoanthracene as reference
compound. The molecular ion peaks were observed at the
expected molecular weights, m/z 522.23 (3a), 550.27 (3b), and
substituent on the absorption spectra. Compounds 3b and 3c
showed structured bands in this region, and the bands at the
longest wavelength were blue-shifted by ca. 20 nm (peak) or
ca. 40 nm (peak edge) relative to the peak of 3a. This difference
will be discussed later in terms of the molecular structure.
In the fluorescence spectra, compounds 3a and 3c as well
as 21 showed broad emission bands at 480-490 nm, resulting
in large Stokes shifts at ca. 70 nm (ca. 3600 cm¹1). In contrast,
a blue shift was notable for the emission of 3b, and the Stokes
shift was decreased to 40 nm (2300 cm¹1). These results mean
that structural changes from the ground state to the excited state
should be very large for 3a and 3c. Compounds 3 are highly
emissive in solution; the absolute fluorescence quantum yields
(Φf ) of 3a and 3b are comparable to those of typical fluorescent
anthracene compounds, such as 9,10-diphenylanthracene (0.90)
and 9,10-bis(phenylethynyl)anthracene (0.87).16
Molecular Structures. The molecular structures of 3a-3c
and 2 were investigated by X-ray analysis and DFT calcu-
lations. Their ORTEP drawings are shown in Figure 3. All
compounds have stair-like nonplanar macrocyclic frameworks,
where two ethenylene moieties are directed to the same side
of each anthracene plane (syn form). The conformation is
characterized by the dihedral angles between the ethenylene
moieties and the anthracene planes. The averages of the four
angles (absolute values) at the acute angle corners are rather
small (40-47°) for 3a and 2 and large (73-79°) for 3b and 3c.
Therefore, the substituents at the linker positions increased the
dihedral angles via the steric hindrance, and it led to the
decreased π-conjugation in the cyclic system. This structural
1
674.30 (3c). In the H NMR spectrum of 3a, the signal due
to alkene protons was observed as a singlet at ¤ 7.81, thereby
offering no information on the coupling due to the coincidence
of the chemical shifts of the two kinds of protons.15 Signals
assignable to the inner protons at the 9-positions in 3a-3c
were observed in the low-field region (¤ 9.6-10.1) due to the
anisotropic effects of the double bond moieties at the 1,8-
positions. The signal due to the o-Me groups in the mesityl
group was observed as a singlet at ¤ 1.8 in all the compounds
in CDCl3. In toluene-d8, the o-Me signals of 3b and 3c were
observed as two broad singlets and a broad singlet, respec-
tively. The broad signals suggest that the molecules undergo
dynamic processes on the NMR time scale. These observations
are analyzed and discussed later.
Electronic Spectra. The UV-vis absorption spectra and
the fluorescence spectra of 3 were measured in chloroform
(Figure 2 and Table 1). Compound 3a showed a broad absorp-
tion band peaking at 417 nm and extending to 470 nm in the p-
band region. This wavelength is comparable to that of parent
compound 2, indicating a very small effect of the 10-mesityl
Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan | 1593

3a
3b
*
*
*
*
[41.7°] (40.0°)
*
*
*
*
[79.4°]
3c
*
*
*
*
[73.8°] (72.8°)
2
[47.2°] (45.8°)
Figure 3. Two views of ORTEP drawings of compounds 3a-3c and 2 (Solvent molecules are omitted. One of the two independent
molecules for 3a, 3c, and 2. Values in brackets are the averaged angles of the four dihedral angles marked by an asterisk (*), and
those in parentheses are values for another independent molecule).
feature is consistent with the blue shift in the absorption spectra
of 3b and 3c. The mesityl group in 3 is nearly perpendicular to
the attaching anthracene plane (dihedral angle 75-88°). In 3c,
one phenyl group is nearly coplanar to the ethenylene group,
whereas the other phenyl group is twisted by ca. 80° to form an
intramolecular C-H£π contact at ca. 3.0 ¡ between the two
phenyl groups.17
Figure 4 shows the packing diagrams of the X-ray structures
of 3a and 2. For 3a, no significant intermolecular π£π contacts
are observable, and the molecules loosely interact with one
another via mainly C-H£π contacts. The mesityl groups form
a column in the crystal lattice, where the solvent (benzene)
molecules are included in the cavities. The packing modes of
3b and 3c are similar to that of 3a. Compound 2 shows a
typical herringbone packing, where the molecules form a
linear network via π£π interactions. The distance between the
interacting anthracene planes is ca. 3.4 ¡, which is comparable
to the sum of the van der Waals radii of aromatic carbons. The
difference in the crystal packing unambiguously indicates that
the mesityl groups in 3a prevent the molecules from forming
tight intermolecular interactions in the crystal, thus increasing
the solubility.8
of the linker moieties for each compound (Figure 5). The
two ethenylene moieties are nearly parallel in the syn forms,
whereas they are crossed in the anti forms. The X-ray structures
are mostly reproduced by the calculation in the syn forms even
though there is a difference in the conformation of the phenyl
groups in syn-3c, which would be readily influenced by the
packing effect in the X-ray structure. In all the compounds, the
syn forms were more stable than the anti forms, where the
energy differences ¦E were 9.0-11.1 kJ mol¹1 (Table 2). These
values mean that compounds 3 mostly exist in the syn form
under ordinary conditions.
MO Analysis. To obtain further insight into the effects
of the molecular structures on the π-conjugation, we analyzed
the molecular orbitals calculated at the same level. The HOMO
and LUMO plots of 3 are shown in Figure 6. The orbitals are
spread over the macrocyclic framework at the HOMO and
LUMO levels for 3a. Therefore, the conjugation of the anthra-
cene units is extended across the ethenylene linkers leading
to bathochromic effects on the p-band absorption due to the
HOMO¼LUMO excitation. In contrast, the orbitals are mainly
located on one or two anthracene unit(s) and not extended
across the ethenylene moieties at the HOMO and LUMO levels
for 3b and 3c. This orbital distribution indicates that the π-
conjugation is disconnected at the ethenylene linkers in the
nearly bisected conformation. We also calculated the absorp-
DFT calculations of 3 were carried out at the M05/6-31G*
level of theory.18 We obtained two energy-minimum struc-
tures, syn and anti forms, that differed in the conformation
1594 | Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan

3.4 Å
3a
2
Figure 4. Packing diagrams of X-ray structures of 3a and 2.
syn-3a
anti-3a
3a (TS1)
3a (TS2)
3a (planar)
syn-3b
anti-3b
3b (TS1)
syn-3c
anti-3c
3c (TS1)
Figure 5. Calculated structures of syn and anti forms and related structures of 3 optimized at M05/6-31G* level.
Table 2. Relative energies of syn and anti forms and other
related structures of 3 calculated at M05/6-31G* level and
observed barriers to dynamic processes
to the HOMO¼LUMO excitation (Supporting Information).
The large bathochromic effect of 3a relative to that of 3b and
3c was reasonably reproduced by the theoretical calculation
when we compared the peak edge wavelengths in the observed
spectra.
¹1
E/kJ mol
Observed barrier
¹1
/kJ mol
syn
anti
TS1
TS2
planar
Dynamic Behavior.
In order to observe the dynamic
3a
3b
3c
0
0
0
9.4 37.6
9.0 72.0
11.1 57.1
36.6
®
61.7
®
34 (168 K)
70 (305 K)
55.8 (273 K)
behavior of macrocyclic compounds 3, variable temperature
(VT) NMR spectra were measured by using the proton signals
due to the mesityl group as probe. Because the rotation of
the mesityl group relative to the attaching anthracene plane
never occurs under ordinary conditions (estimated barrier
ca. 200 kJ mol¹1),9a the magnetic environment of the two o-Me
groups is influenced by the conformational preference and the
exchange rates (Scheme 2). The two o-Me groups are non-
®
®
tion spectra of 3 by the TDDFT method. The calculated
wavelengths in the p-band region were 447, 397, and 398 nm
for 3a, 3b, and 3c, respectively, which were mainly attributed
Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan | 1595

1
equivalent in the syn form of Cs symmetry, whereas they are
equivalent in the anti form of C2 symmetry. These signals can
be averaged by facile exchange between possible isomers.
Although the signals due to m-H atoms should exhibit the same
behavior, their chemical shift difference was too small to use as
an NMR probe.
The VT 1H NMR spectra were measured in CD2Cl2 or
toluene-d8, depending on the measurable temperature range and
the solubility (Figure 7). For 3a, the o-Me groups gave a sharp
singlet at room temperature in CD2Cl2, which was unchanged
even after lowering the temperature to ¹83 °C. This signal
began to broaden at ¹90 °C and decoalesced at ¹105 °C. Dur-
ing the measurements, the other signals showed no significant
line shape changes. This observation can be explained by the
exchange between the two syn forms, which are topomers of
each other, via the rotation of the ethenylene groups, resulting
in the site exchange between MeA and MeB, as shown in
Scheme 2. Although the exchange was not frozen on the NMR
time scale at the lowest attainable temperature, we estimated
The VT H NMR spectra of 3b and 3c were measured in
toluene-d8. For 3c, the signal due to the o-Me group appeared
as a broad singlet at room temperature, decoalesced at ¹2 °C,
and resharpened into two singlets at ¹58 °C. Total line shape
analysis gave the following kinetic parameters: ¦Hº
53.3 kJ mol¹1, ¦Sº = ¹9.1 J mol¹1 K¹1, and ¦Gº273 = 55.8
kJ mol¹1. For 3b, the signal was observed as a broad doublet at
room temperature, and coalesced at 32 °C. Because the chemi-
cal shift difference was small (ca. 3 Hz), the barrier to exchange
could be approximately determined by the coalescence method,
=
¹1
i.e., it was 70 kJ mol at 32 °C.
The mechanism of the dynamic behavior is discussed on the
basis of the above results as well as the additional calculations
of transient structures. We propose two discrete mechanisms
for the process from the syn form to its topomer (Scheme 3).
Mechanism A involves the concurrent rotation of the four
C(arom)-C(sp2) bonds through a planar transition state during
the topomerization (syn-3 and syn-3¤ are topomers of each
other). The calculation suggests that the nearly planar structure
of 3a is less stable by ca. 62 kJ mol¹1 than the global minimum
structure (Figure 5 and Table 2). This structure is very unstable
because of the steric hindrance between the ethenylene and
anthracene H atoms in the inner region. As a result, the anthra-
cene moieties suffer from large out-of-plane deformations
particularly at the 9-positions. For the substituted derivatives,
3b and 3c, the calculations of such structures were impossible
because one of the substituents R should be directed into the
macrocyclic framework. Therefore, this mechanism is unlikely
because the calculated energies are much higher than the
observed ones.
the barrier to exchange at the coalescence temperature to be
¹1 19
¦Gº168 = 34 kJ mol
.
Mechanism B proceeds via the stepwise rotation of the two
linker moieties, where the rotation of one ethenylene moiety
in the syn form leads to the anti form as the intermediate
and the following rotation of the other ethenylene moiety leads
to the syn form (Scheme 3). In the transition state, one of
the ethenylene groups is nearly coplanar with the anthracene
planes, where substituent R at the rotating linker is either inside
or outside the macrocyclic ring. These two transition state
structures, TS1 and TS2, were calculated for each compound
(Figure 5). The two structures have comparable energies for 3a,
Figure 6. HOMO and LUMO plots of syn-3 calculated at
M05/6-31G* level.
H
MeA
R
MeB
H
R
Me
Me
R
H
MeA
MeB
R
H
syn-3
syn-3'
R
H
MeX
MeX
Me
H
R
anti-3
Scheme 2. Magnetic equivalence of o-Me signals in the mesityl group in syn-3 and anti-3. Each symbol A, B, or X denotes the o-Me
groups having the same chemical shift.
1596 | Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan

Figure 7. Line shape changes of o-Me signals in VT 1H NMR spectra of 3a in CD2Cl2 and 3b and 3c in toluene-d8. * Signals due to
solvent.
Mechanism A (concurrent rotation)
H
R
R
H
Mes
H
Mes
R
R
Mes
R
H
H
R
H
syn-3
syn-3'
3 (planar)
Mechanism B (stepwise rotation)
R
R
R
Mes
R
H
Mes
Mes
R
H
or
or
H
H
R
H
R
H
H
syn-3
3 (TS1)
3 (TS2)
Mes
H
H
H
R
R
H
R
H
H
H
Mes
anti-3
Mes
Mes
R
R
R
R
3' (TS2)
3' (TS1)
syn-3'
Scheme 3. Mechanisms for exchange between two syn forms of 3 (R = H, Me, or Ph).
¹1
where TS2 is more stable by only 1 kJ mol than TS1. There-
fore, the rotation can occur via the two transition states. For
3b and 3c, the rotation via TS2 is quite unlikely because of
the severe steric hindrance of the inside non-hydrogen group
R. We were able to obtain only the TS1 structure by opti-
mization as the transition state. Thus calculated barriers, the
energy difference between the syn form and TS, were 36.6 (3a),
ethene (ca. 16 kJ mol¹1).20 In the cyclic system of 3, the transi-
tion state is destabilized by the unavoidable steric interactions
in the inner region, which are a kind of transannular interaction.
The barriers increase in the order of 3a (R = H), 3c (Ph), and
3b (Me). This tendency can be explained by the steric sizes
of H (1.2 ¡), Ph (1.7 ¡), and Me (2.0 ¡), where the van der
Waals radii or effective radii are given in parentheses.21 The
calculated transition state structures suggest that the steric
interactions of the outside substituent in the rotating ethenylene
moiety are important. Figure 8 shows the calculated TS1
structures of 3b and 3c. The outside Me or Ph group interacts
with aromatic 2-H and 2¤-H atoms. The distances between the
Me group and the interacting H atoms in 3b, 2.55 and 2.33 ¡,
¹1
72.0 (3b), and 57.1 kJ mol (3c). These values are in good
agreement with the experimental barriers determined by VT
NMR measurements. These data support mechanism B for the
topomerization between the two syn forms.
The barrier of 3a is higher than the barriers to rotation of
acyclic trans-diarylethenes, for example, trans-1,2-diphenyl-
Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
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2’
2’
1’
1’
2.55 Å
2.49 Å
2.26 Å
2.33 Å
1
1
2
2
Figure 8. Structures of TS1 of 3b (left) and 3c (right). Mesityl groups are omitted for clarity.
are smaller than the sum of radii of the two substituents (3.2 ¡).
method or on a Bruker autoflex speed by MALDI-TOF/TOF
method. UV-vis spectra were measured on a Hitachi U-3000
spectrometer with a 10 mm cell. Fluorescence spectra were
measured on a JASCO FP-6500 spectrofluorometer with a 10
mm cell with the sample degassed by Ar gas immediately
before measurements. Absolute fluorescence quantum yields
were recorded on a Hamamatsu photonics C9920-02. Column
chromatography was carried out with Merck Silica Gel 60 (70-
230 mesh). Boronic acid pinacol esters were purchased from
Aldrich.
Compound 6a. 1,8-Diiodoanthracene10 (4, 3.00 g, 6.98
mmol) was dissolved in a mixture of degassed toluene (70 mL)
and diisopropylamine (3.92 mL, 27.9 mmol). To the solution
were added 5a (3.58 mL, 20.9 mmol) and [Pd(PtBu3)2] (357 mg,
0.699 mmol). The reaction mixture was heated at 80 °C for 24 h
under Ar. After the mixture was filtered through Celite, the
filtrate was evaporated. The crude product was purified by
chromatography on silica gel with toluene/CH2Cl2 1:1 eluent
to give the desired compound as black oil. Yield 2.89 g (86%);
1H NMR (400 MHz, CDCl3): ¤ 1.40 (24H, s), 6.36 (2H, d,
J = 18.2 Hz), 7.47 (2H, dd, J = 6.8, 8.0 Hz), 7.75 (2H, d, J =
6.8 Hz), 7.97 (2H, d, J = 8.0 Hz), 8.40 (2H, d, J = 18.2 Hz),
8.44 (1H, s), 9.09 (1H, s); 13C NMR (100 MHz, CDCl3): ¤
24.91, 83.35, 118.47, 124.12, 125.26, 127.54, 129.15, 129.53,
131.59, 136.03, 146.65 (one aliphatic signal missing); HRMS
(FAB) found: 482.2777 m/z [M]+; calcd for C30H3611B2O4
m/z 482.2810. The large coupling constant supports E stereo-
chemistry for the ethenylene moieties.
In addition, the anthracene moiety involving C1¤ and C2¤
suffers from significant out-of-plane deformation. In TS1 of 3c,
the phenyl group is perpendicular to the linker moiety to
minimize the steric hindrance. The distances between the
phenyl ipso carbon atom and the interacting H atoms, 2.49 and
2.26 ¡, are within the sum of radii (2.9 ¡). In this conforma-
tion, C-H£π interactions may stabilize the transition state.17
In summary, macrocyclic compounds consisting of two
anthracene units and two ethenylene linkers were synthesized
by cross-coupling reactions. The X-ray analysis and DFT
calculations revealed that the macrocyclic framework adopted
the nonplanar syn form. The structures and the electronic
properties were influenced by the substituents at the linker
moieties, and the Me and Ph substituents decreased the π-
conjugation between the anthracene units and the ethenylene
linkers due to the large dihedral angles relative to the
substituent-free derivative. The dynamic processes between
the two syn forms were observed from the line shape changes
of the o-Me signals in the mesityl group in the VT NMR
spectra. This topomerization took place by the stepwise rotation
of the two ethenylene linkers via the anti form as an inter-
mediate, as if the two nonlinear linkers were performing
pedaling motion within the cyclic system. The barriers increas-
ed in the order of H, Ph, and Me derivatives, corresponding
to their steric sizes. These findings indicate that the structures
and properties of nonplanar macrocyclic systems can be fur-
ther modified by introducing substituents at various positions.
Further studies of the synthesis of various derivatives involving
cis-ethenylene linkers or more than two anthracene units are in
progress toward creation of novel cyclic systems.
1,8-Diiodo-9-mesitylanthracene (8).
mesitylmagnesium bromide (1 mol L
To a solution of
THF solution, 40.4
¹1
mL, 40.4 mmol) in THF (100 mL) was added 4,5-diiodo-9-
anthrone10 (3.00 g, 6.73 mmol) under Ar. After the solution was
stirred for 24 h at room temperature, the reaction was quenched
with NH4Cl aq (60 mL). The organic layer was separated, and
the aqueous layer was extracted with ether (20 mL © 3). The
combined organic layer was dried over MgSO4 and evaporated.
The crude product was purified by chromatography on silica
gel with hexane eluent to give the desired compound as a
yellow solid. Yield 3.12 g (85%); mp 247-251 °C (dec);
1H NMR (400 MHz, CDCl3): ¤ 1.65 (6H, s), 2.44 (3H, s),
7.05 (2H, dd, J = 6.8, 8.4 Hz), 7.07 (2H, s), 7.48 (2H, d,
Experimental
General.
Melting points are uncorrected. Elemental
analyses were performed with a Perkin-Elmer 2400 series
1
analyzer. H and 13C NMR spectra were measured on a JEOL
JNM-ECS400 spectrometer at 400 and 100 MHz, respectively.
Variable temperature 1H NMR spectra were measured on a
JEOL JNM-GSX400 spectrometer at 400 MHz or the JEOL
JNM-ECS400 spectrometer. High-resolution mass spectra were
measured on a JEOL MStation-700 spectrometer by FAB
1598 | Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan

J = 6.8 Hz), 8.15 (2H, d, J = 8.4 Hz), 9.09 (1H, s); 13C NMR
(100 MHz, CDCl3): ¤ 20.12, 21.38, 100.98, 127.07, 127.16,
128.58, 130.65, 133.24, 133.89, 136.97, 137.51, 137.81,
137.94, 138.13; HRMS (FAB) found: m/z 547.9545 [M]+;
calcd for C23H18I2 m/z 547.9498; Anal found: C, 50.23, H,
3.11%. calcd for C23H18I2: C, 50.39, H, 3.31%.
11.1 mL, 17.8 mmol) with a syringe at ¹78 °C under Ar. After
this solution was stirred at that temperature for 1 h, MeI (2.75
mL, 44.2 mmol) was added. The solution was stirred at that
temperature at 1 h, and then at room temperature for 1 h. The
reaction mixture was treated with aq. NH4Cl (20 mL), and the
organic solvents were evaporated. The organic materials were
extracted with CH2Cl2 (20 mL © 3). The combined organic
layer was dried over MgSO4 and evaporated. The crude product
was purified by chromatography on silica gel with hexane/
CH2Cl2 3:1 eluent to give the desired compound as a yellow
solid. Yield 1.04 g (93%); mp 200-203 °C; 1H NMR (400 MHz,
CDCl3): ¤ 2.30 (6H, s), 7.40 (2H, dd, J = 6.8, 8.8 Hz), 7.63
(2H, d, J = 6.8 Hz), 7.95 (2H, d, J = 8.8 Hz), 8.40 (1H, s),
9.40 (1H, s); 13C NMR (100 MHz, CDCl3): ¤ 4.81, 78.17,
91.50, 122.37, 124.37, 125.21, 127.20, 128.24, 129.69, 131.60,
131.93; HRMS (FAB) found 254.1081 m/z [M]+; calcd for
C20H14 m/z 254.1096; Anal found: C, 94.05, H, 5.73%. calcd
for C20H10: C, 94.45, H, 5.55%.
Cyclic Dimer 3a. To a mixture of degassed toluene (200
mL) and water (20 mL) were added 6a (10.1 mg, 20.9 ¯mol,
¹1
ca. 1.0 © 10¹4 mol L in toluene), 8 (11.5 mg, 21.0 ¯mol),
Cs2CO3 (67.4 mg, 0.21 mmol), and [Pd(PPh3)4] (2.4 mg, 2.1
¯mol). The reaction mixture was heated at 90 °C for 48 h under
Ar. After the mixture was filtered through Celite, the organic
layer was separated and the aqueous layer was extracted with
ether (10 mL © 3). The combined organic layer was dried over
MgSO4 and evaporated. The crude product was purified by
chromatography on silica gel with hexane/CH2Cl2 10:1 eluent
to give the desired product (3.6 mg, 33%) as yellow crystals.
The yield was 25% when the concentration of 6a was 1.0 ©
10¹3 mol L¹1. Mp 290-301 °C (dec); 1H NMR (400 MHz,
CDCl3): ¤ 1.78 (6H, s), 2.48 (3H, s), 7.13 (2H, s), 7.42 (2H,
dd, J = 6.8, 8.8 Hz), 7.48 (2H, d, J = 8.8 Hz), 7.58 (2H, dd,
J = 6.4, 8.4 Hz), 7.67 (2H, d, J = 6.8 Hz), 7.68 (2H, d, J =
6.4 Hz), 7.81 (4H, s), 8.04 (2H, d, J = 8.4 Hz), 8.56 (1H, s),
10.07 (1H, s), 10.08 (1H, s); 13C NMR (100 MHz, CDCl3):
¤ 20.28, 21.42, 121.94, 122.64, 123.91, 125.65, 125.72,
125.75, 127.10, 127.71, 128.47, 130.20, 130.24, 130.34,
132.20, 133.54, 133.76, 136.80, 137.11, 137.23, 137.35,
137.76 (two aromatic signals missing); UV-vis (CHCl3) -max
(¾) 252 (147000), 417 (19000) nm; FL (CHCl3) -max 491 nm,
Compound 6b. A mixture of CuCl (19.5 mg, 0.197 mmol),
NaOtBu (75.7 mg, 0.788 mmol), and PPh3 (103 mg, 0.393
mmol) was suspended in THF (25 mL) under Ar. After this
mixture was stirred for 30 min, bis(pinacolato)diboron (1.50 g,
5.91 mmol) was added. After this mixture was further stirred
for 10 min, 7 (500 mg, 1.97 mmol) and MeOH (0.64 mL, 16
mmol) were added. The reaction mixture was heated at 50 °C
for 1 h, and then filtered through Celite. The filtrate was evapo-
rated, and the residue was dissolved in CHCl3 (20 mL). This
¹1
organic layer was washed with 1 mol L aq. HCl (10 mL © 3)
and aq. NaCl (10 mL), dried over MgSO4, and evaporated. The
crude product was purified by chromatography on silica gel
with hexane/ethyl acetate 40:1 eluent to give the desired
product as brown oil. Yield 932 mg (93%); 1H NMR (400
MHz, CDCl3): ¤ 1.37 (24H, s), 1.87 (6H, s), 7.34 (2H, d, J =
6.8 Hz), 7.44 (2H, dd, J = 6.8, 8.4 Hz), 7.82 (2H, s), 7.93 (2H,
d, J = 8.4 Hz), 8.44 (1H, s), 8.54 (1H, s); 13C NMR (100 MHz,
CDCl3): ¤ 16.74, 25.09, 83.57, 121.45, 124.83, 126.65, 127.46,
127.87, 130.16, 131.77, 135.76, 141.33 (one aliphatic signal
missing); HRMS (FAB) found 510.3113 m/z [M]+; calcd for
C32H4011B2O4 m/z 510.3113.
-
ex 421 nm, Φf 0.71; HRMS (FAB) found: m/z 522.2308 [M]+;
calcd for C41H30 m/z 522.2348.
Cyclic Dimer 2. This compound was similarly prepared
from 6a (10.1 mg, 20.9 mmol) and 4 (9.1 mg, 21 mmol). The
chromatographic purification gave the desired compound as a
yellow solid. Yield 2.7 mg (32%); mp 301-310 °C (dec) [ref.
>360 °C (dec)];7 1H NMR (400 MHz, CDCl3): ¤ 7.57 (4H, dd,
J = 6.2, 8.0 Hz), 7.67 (4H, d, J = 6.2 Hz), 7.77 (4H, s), 8.03
(4H, d, J = 8.0 Hz), 8.55 (2H, s), 10.01 (2H, s); UV-vis
(CHCl3) -max (¾) 250 (133000), 413 (14800) nm; FL (CHCl3)
-
484 nm, -ex 416 nm, Φf 0.67; HRMS (MALDI-TOF)
Cyclic Dimer 3b. This compound was similarly synthe-
sized from 6b (10.0 mg, 19.6 ¯mol), 8 (10.7 mg, 19.5 ¯mol),
Cs2CO3 (63.6 mg, 0.195 mmol), and [Pd(PPh3)4] (2.25 mg, 1.95
¯mol) as the synthesis of 3a. The crude product was purified by
chromatography on silica gel with hexane/CH2Cl2 10:1 eluent
to give the desired product as yellow solid. The yield was
max
found: m/z 404.1565 [M]+; calcd for C32H20 404.1565. The
13C NMR spectrum could not be measured due to the low
solubility.
Reaction of 4 and 5b. This coupling reaction was similarly
performed by using 4 (100 mg, 0.233 mmol), 5b (0.131 mL,
0.697 mmol), and [Pd(PtBu3)2] (11.9 mg, 0.0233 mmol) in
toluene (5 mL) and diisopropylamine (0.131 mL, 0.932 mmol)
as the synthesis of 3a. Even though the reaction mixture was
heated at 80 °C for 72 h, most of the starting material was
recovered. A small amount of the mono-coupling product was
¹1
5.5 mg (51%) at ca. 1.0 © 10¹4 mol L and 4.3 mg (40%) at
1
ca. 1.0 © 10¹3 mol L¹1. Mp 167-169 °C; H NMR (400 MHz,
CDCl3): ¤ 1.81 (6H, s), 2.10 (6H, s), 2.49 (3H, s), 7.31 (2H, s),
7.15 (2H, s), 7.40 (2H, dd, J = 6.4, 8.8 Hz), 7.48 (2H, d,
J = 8.8 Hz), 7.51-7.53 (4H, m), 7.58 (2H, dd, J = 6.8, 8.8 Hz),
8.05 (2H, d, J = 8.0 Hz), 8.57 (1H, s), 9.62 (2H, s); 13C NMR
(100 MHz, CDCl3): ¤ 20.38, 21.02, 21.43, 122.94, 123.66,
123.82, 125.25, 125.33, 125.51, 126.97, 127.29, 128.43,
129.23, 130.14, 130.18, 130.76, 132.03, 135.17, 136.56,
136.76, 137.26, 137.84, 141.47, 143.89 (one aromatic signal
missing); UV-vis (CHCl3) -max (¾) 254 (141000), 359 (9240),
378 (15500), 398 (16500) nm; FL (CHCl3) -max 438 nm, -ex
398 nm, Φf 0.82; HRMS (FAB) found 550.2659 m/z [M]+;
calcd for C43H34 m/z 550.2661.
1
obtained: H NMR (400 MHz, CDCl3): ¤ 1.40 (12H, s), 1.87
(3H, d, J = 1.6 Hz), 7.15 (1H, dd, J = 7.2, 8.4 Hz), 7.41 (1H, d,
J = 6.8 Hz), 7.51 (1H, dd, J = 7.2, 8.4 Hz), 7.91 (1H, br), 7.95
(1H, d, J = 8.4 Hz), 7.99 (1H, d, J = 8.0 Hz), 8.09 (1H, d,
J = 7.6 Hz), 8.37 (1H, s), 8.77 (1H, s); HRMS (FAB) found:
m/z 470.0933 [M]+; calcd for C23H2411BIO2 m/z 470.0914.
1,8-Bis(1-propynyl)anthracene (7b). To a solution of 1,8-
diethynylanthracene22 (1.00 g, 4.42 mmol) in anhydrous THF
(100 mL) was slowly added BuLi (1.6 mol L¹1 hexane solution,
Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan | 1599

Reaction of 4 and 5c. This reaction was similarly per-
formed with 4 (300 mg, 0.698 mmol), 5c (483 mg, 2.10 mmol),
and [Pd(PtBu3)2] (35.7 mg, 0.0699 mmol) in toluene (15 mL)
and diisopropylamine (0.39 mL, 2.77 mmol) as the synthesis of
6a. The crude product was purified by chromatography on
silica gel with hexane/ethyl acetate 5:1 to give compound 6c¤
(E/E product) as a brown solid. The stereochemistry was
confirmed by X-ray analysis (Figure S3). Yield 342 mg (77%);
shifts of a methanol sample or a 1,2-ethanediol sample. For 3a,
the signal due to the o-Me groups decoalesced at ¹105 °C
(168 K). The chemical shift difference (¦¯/Hz) was estimated
to be 42 Hz, even though the signals were still broad at
¹109 °C, the lowest attainable temperature. The rate constant at
the coalescence temperature (Tc) was calculated by the empiri-
pffiffiffi
cal equation for the coalescence method, k = (π/ 2)¢¦¯, to be
¹1 19
k = 152 s
.
This value corresponded to the free energy of
1
mp 172-174 °C; H NMR (400 MHz, CDCl3): ¤ 1.11 (24H, s),
activation ¦Gº at Tc to be 34 kJ mol¹1. For 3b, the o-Me
signals coalesced at 32 °C (305 K) and the ¦¯ was approx-
imately 3 Hz. These values afforded k = 6.7 s¹1 and ¦Gº = 70
kJ mol¹1 at Tc in a similar manner. The total line shape analyses
of the o-Me signals of 3c were performed by the DNMR3K
program (Figure S2).23 The line shape changes were analyzed
as 2-site mutual exchanges (A ꢀ X). The chemical shift differ-
ence (¦¯) was assumed to be a linear function of the temper-
ature (t/°C) as ¦¯ = ¹0.247 t + 56.9 (Hz), and the spin-spin
relaxation time (T2/s) was fixed at 0.06. Rate constants are as
7.28-7.33 (6H, m), 7.42 (2H, dd, J = 6.8, 8.8 Hz), 7.58-7.60
(6H, m), 7.95 (2H, d, J = 8.8 Hz), 8.03 (2H, s), 8.43 (1H, s),
8.96 (1H, s); 13C NMR (100 MHz, CDCl3): ¤ 24.80, 83.93,
121.88, 125.04, 125.31, 127.01, 127.07, 127.25, 128.20,
128.62, 130.50, 131.76, 137.26, 138.64, 142.40 (one aliphatic
signal missing); HRMS (FAB) found 634.3436 m/z [M]+;
calcd for C42H4411B2O4 m/z 634.3426.
Compound 6c. This compound was similarly prepared
from 7c10 (900 mg, 2.38 mmol), bis(pinacolato)diboron (1.81 g,
7.13 mmol), CuCl (23.6 mg, 0.238 mmol), NaOtBu (91.5 mg,
0.952 mmol), PPh3 (125 mg, 0.477 mmol), and MeOH (769 ¯L,
19.0 mmol) in THF (45 mL) as the synthesis of 6b. The crude
product was purified by chromatography on silica gel with
CHCl3 eluent to give the desired product as a yellow solid.
Yield 421 mg (28%); Mp 208-211 °C; 1H NMR (400 MHz,
CDCl3): ¤ 1.42 (24H, s), 7.00-7.11 (12H, m), 7.18 (2H, dd,
J = 7.2, 8.4 Hz), 7.79 (2H, d, J = 8.4 Hz), 7.97 (2H, s), 8.33
(1H, s), 8.55 (1H, s); 13C NMR (100 MHz, CDCl3): ¤ 25.13,
83.98, 121.39, 124.85, 126.23, 127.54, 127.89, 127.94, 127.99,
129.68, 131.61, 135.85, 140.30, 142.68 (one aliphatic signal
and one aromatic signal missing); HRMS (FAB) found
634.3464 m/z [M]+; calcd for C42H44B2O4 m/z 634.3426.
This reaction also gave several other isomers, which were not
separable by conventional chromatography.
¹1
follows: k/s (t/°C) = 15 (¹21.7), 25 (¹16.5), 40 (¹11.4),
65 (¹6.5). 100 (¹1.5), 170 (3.3), 250 (8.1), 350 (12.7). The
Eyring plot of these data afforded the following kinetic param-
¹1
eters: ¦Hº = (53.3 « 1.8) kJ mol
,
¦Sº = (¹9.1 « 6.7)
J mol¹1 K¹1, ¦Gº273 = (55.8 « 3.8) kJ mol
.
¹1
DFT Calculations. Calculations were carried out with
Gaussian 0924 program on a Windows computer. The structures
were optimized by the hybrid DFT method at the M05/6-31G*
level. The frequency analysis gave no imaginary frequency for
each energy minimum structure, one imaginary frequency for
transition state structure, and two imaginary frequencies for
nearly planar structure. The calculations of excited states were
carried out by the TDDFT method at the same level.
X-ray Analysis. Single crystals of 3 and 2 were obtained
by crystallization from suitable solvents. Diffraction data were
collected on a Rigaku Varimax imaging plate diffractometer
with Mo Kα radiation (- = 0.71075 ¡) to a maximum 2ª value
of 55.0° at ¹150 °C. The structure was solved by the direct
method (SHELXS97)25 and refined by the full-matrix least
squares method (SHELXL97).26 Non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were included in fixed
positions. Copies of the data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from
the Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge, CB2 1EZ, UK; Fax: +44 1223 762911; e-mail:
deposit@ccdc.cam.ac.uk). 3a (CCDC 953893): Recrystallized
from benzene/ethanol. Formula (C41H30)¢0.25(C6H6), M =
Cyclic Dimer 3c. This compound was similarly synthe-
sized from 6c (10.0 mg, 15.8 ¯mol), 8 (8.68 mg, 15.8 ¯mol),
Cs2CO3 (51.3 mg, 0.157 mmol), and [Pd(PPh3)4] (1.83 mg, 1.58
¯mol) as the synthesis of 3a. The crude product was purified by
chromatography on silica gel with hexane/CH2Cl2 10:1 eluent
to give the desired product as yellow solid. The yield was
¹1
6.7 mg (63%) at ca. 1.0 © 10¹4 mol L and 5.7 mg (54%) at
1
ca. 1.0 © 10¹3 mol L¹1. Mp 300-310 °C (dec); H NMR (400
MHz, CDCl3): ¤ 1.81 (6H, s), 2.48 (3H, s), 6.76 (4H, t,
J = 8.0 Hz), 6.89 (2H, t, J = 7.2 Hz), 7.02 (4H, d, J = 8.0 Hz),
7.13 (2H, s), 7.37 (2H, s), 7.42-7.50 (8H, m), 7.66 (2H, d,
J = 6.4 Hz), 7.99 (2H, d, J = 8.4 Hz), 8.51 (1H, s), 9.77 (1H,
s), 9.86 (1H, s); 13C NMR (100 MHz, CDCl3): ¤ 20.52, 21.44,
123.92, 124.47, 124.99, 125.40, 125.45, 125.58, 125.72,
126.98, 127.29, 127.82, 128.45, 130.17, 131.02, 131.19,
131.38, 131.90, 135.07, 136.49, 136.75, 137.29, 137.90,
138.74, 142.33, 143.72 (two aromatic signals missing); UV-
vis (CHCl3) -max (¾) 255 (123000), 360 (10400), 379 (17000),
400 (17000) nm; FL (CHCl3) -max 478 nm, -ex 377 nm, Φf
0.39; HRMS (FAB) found 674.2988 m/z [M]+; calcd for
C53H38 m/z 674.2974.
VT NMR Measurements. 1H NMR spectra were mea-
sured at variable temperatures in toluene-d8 (3b and 3c) or in
CD2Cl2 (3a) on a JEOL JNM-ECS400 spectrometer at 400
MHz (Figure S1). The sample temperature was monitored by a
thermocouple after calibration with the 1H NMR chemical
ꢀ
1084.35, triclinic, P1, a = 11.130(2), b = 15.080(3), c =
18.842(4) ¡,
¡ = 100.300(12),
¢ = 92.311(17),
£ =
¹3
110.700(9)°, V = 2892.3(11) ¡3, Z = 4, Dc = 1.245 g cm
,
®(Mo Kα) = 0.070 mm¹1. Number of data 24518, number of
data used 12959 [I > 2.0σ(I)], R1 = 0.0890, wR2 = 0.1801,
GOF = 1.075. CCDC 953893. 3b (CCDC 1407436): Recrys-
tallized from benzene/ethanol. Formula C43H34 1.5(C6H6),
ꢀ
M = 667.86, triclinic, P1, a = 10.318(3), b = 12.288(3), c =
15.711(4) ¡, ¡ = 102.516(3), ¢ = 90.952(3), £ = 109.733(3)°,
V = 1821.7(8) ¡3, Z = 2, Dc = 1.218 g cm¹3, ®(Mo Kα) =
0.069 mm¹1. Number of data 16025, number of data used
8187 [I > 2.0σ(I)], R1 = 0.0528, wR2 = 0.1268, GOF =
1.055. 3c (CCDC 1407435): Recrystallized from benzene/
ethanol. Formula (C53H38)¢1.5(C6H6), M = 792.00, triclinic,
1600 | Bull. Chem. Soc. Jpn. 2015, 88, 1591–1602 | doi:10.1246/bcsj.20150245
© 2015 The Chemical Society of Japan

ꢀ
Köhler, F. D. Sönnichsen, L. Ernst, C. Näther, R. Herges, Chem.®
Eur. J. 2010, 16, 7767. c) S. Heun, H. Bässler, U. Müller, K.
Müllen, J. Phys. Chem. 1994, 98, 7355. d) A. Bohnen, H. J. Räder,
K. Müllen, Synth. Met. 1992, 47, 37. e) H.-P. Weitzel, A. Bohen,
K. Müllen, Makromol. Chem. 1990, 191, 2815. f) S. Nakatsuji, K.
Matsuda, Y. Uesugi, K. Nakashima, S. Akiyama, G. Katzer, W.
Fabian, J. Chem. Soc., Perkin Trans. 2 1991, 861.
P1, a = 10.0012(13), b = 14.897(2), c = 29.721(4) ¡, ¡ =
80.707(4), ¢ = 84.409(5), £ = 83.905(5)°, V = 4330.5(10) ¡3,
Z = 4, Dc = 1.215 g cm¹3, ®(Mo Kα) = 0.069 mm¹1. Number
of data 38314, number of data used 19509 [I > 2.0σ(I)], R1 =
0.0756, wR2 = 0.1512, GOF = 1.071. 2 (CCDC 1407434):
Recrystallized from chlorobenzene. Formula C32H20, M =
ꢀ
404.48, triclinic, P1, a = 7.294(2), b = 10.142(3), c =
7
3158.
8
S. Akiyama, M. Nakagawa, Bull. Chem. Soc. Jpn. 1971, 44,
13.847(4) ¡, ¡ = 95.757(5), ¢ = 92.502(5), £ = 101.972(5)°,
V = 994.9(5) ¡3, Z = 2, Dc = 1.350 g cm
, ®(Mo Kα) =
¹3
a) M. Yoshikawa, S. Imigi, K. Wakamatsu, T. Iwanaga, S.
0.076 mm¹1. Number of data 8798, number of data used
4497 [I > 2.0σ(I)], R1 = 0.0514, wR2 = 0.1188, GOF =
1.017.
Toyota, Chem. Lett. 2013, 42, 559. b) A. Konishi, Y. Hirao, K.
Matsumoto, H. Kurata, R. Kishi, Y. Shigeta, M. Nakano, K.
Tokunaga, K. Kamada, T. Kubo, J. Am. Chem. Soc. 2013, 135,
1430. c) Y. Fujiwara, R. Ozawa, D. Onuma, K. Suzuki, K. Yoza, K.
Kobayashi, J. Org. Chem. 2013, 78, 2206.
This work was partly supported by MEXT KAKENHI for
Scientific Research on Innovative Areas (Integrated Organic
Synthesis) Grant Number 24106743, JSPS KAKENHI for
Scientific Research (C) Grant Number 26410060, and by a
MEXT-Supported Program for the Strategic Research Founda-
tion at Private Universities, 2009-2013.
9
a) S. Toyota, T. Oki, M. Inoue, K. Wakamatsu, T. Iwanaga,
Chem. Lett. 2015, 44, 978. b) K. Nikitin, H. Müller-Bunz, Y. Ortin,
J. Muldoon, M. J. McGlinchey, Org. Lett. 2011, 13, 256. c) D.
Nori-shargh, S. Asadzadeh, F.-R. Ghanizadeh, F. Deyhimi, M. M.
Amini, S. Jameh-Bozorghi, THEOCHEM 2005, 717, 41.
10 M. Goichi, K. Segawa, S. Suzuki, S. Toyota, Synthesis
2005, 2116.
Supporting Information
1H (VT) and 13C NMR of 3, X-ray structure of 6c¤, and DFT
calculation data of 3. This material is available electronically
on J-STAGE.
11 a) K. Itami, K. Tonogaki, T. Nokami, Y. Ohashi, J. Yoshida,
Angew. Chem., Int. Ed. 2006, 45, 2404. b) K. Itami, K. Tonogaki,
Y. Ohashi, J. Yoshida, Org. Lett. 2004, 6, 4093.
12 The stereochemistry of 6c¤ was confirmed by the X-ray
analysis. The observed structure is given in Supporting
Information.
References and Notes
1
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