Synthesis, structure, and photoreactions of fluorinated 2,11-diaza[32]paracyclophane: Photochemical formation of cage-diene type benzene dimer

Article abstract of DOI:10.1002/poc.3726

An octafluorinated 2,11-diaza[3₂]paracyclophane derivative 12 was prepared, and its photochemical reaction was investigated. Upon irradiation at 300?nm, the fluorinated azacyclophane 12 underwent efficient photodimerization of the benzene cores to afford the corresponding photoisomer 13, which possessed cage diene benzene dimer structure (pentacyclo[6.4.0.0.^2,70.^3,120^6,9]dodeca-4,10-diene skeleton). The cage diene structure was established by single-crystal X-ray diffraction analysis. The cage diene 13 thermally isomerized to a syn-o,o′-dibenzene isomer 22. The activation parameters for the thermal isomerization were determined to be E_a?=?121?kJ?mol^?1, ΔH^≠?=?118?kJ?mol^?1, ΔS^≠ _(293?K)?=?22?J?mol^?1?K^?1, and ΔG^≠ _(293?K)?=?111?kJ?mol^?1. It was revealed that, by photoirradiation at 300?nm, the syn-o,o′-dibenzene isomer 22 underwent facile intramolecular [π4s?+?π4s] cycloaddition to reproduce the cage diene isomer 13.

Full text of DOI:10.1002/poc.3726

Received: 14 April 2017
DOI: 10.1002/poc.3726
Revised: 13 May 2017
Accepted: 16 May 2017
S P E C I A L I S S U E A R T I C L E
Synthesis, structure, and photoreactions of fluorinated 2,11‐
diaza[32]paracyclophane: Photochemical formation of cage‐diene
type benzene dimer
Hideki Okamoto1
| Tetsuya Kozai1 | Zenji Okabayashi1 | Teruo Shinmyozu2 | Hiromi Ota3 |
Kiichi Amimoto4 | Kyosuke Satake1
1 Division of Earth, Life, and Molecular
Sciences, Graduate School of Natural
Science and Technology, Okayama
University, Okayama, Japan
Abstract
An octafluorinated 2,11‐diaza[32]paracyclophane derivative 12 was prepared, and
its photochemical reaction was investigated. Upon irradiation at 300 nm, the fluori-
nated azacyclophane 12 underwent efficient photodimerization of the benzene cores
to afford the corresponding photoisomer 13, which possessed cage diene benzene
dimer structure (pentacyclo[6.4.0.0.2,70.3,1206,9]dodeca‐4,10‐diene skeleton). The
cage diene structure was established by single‐crystal X‐ray diffraction analysis.
The cage diene 13 thermally isomerized to a syn‐o,o′‐dibenzene isomer 22. The acti-
vation parameters for the thermal isomerization were determined to be
2 Department of Chemistry, National Taiwan
University, Taipei, Taiwan
3 Department of Instrumental Analysis,
Advanced Science Research Center,
Okayama University, Okayama, Japan
4 Department of Science Education, Graduate
School of Education, Hiroshima University,
Hiroshima, Japan
Ea = 121 kJ mol−1, ΔH≠ = 118 kJ mol−1, ΔS≠
= 22 J mol−1 K−1, and
(293 K)
ΔG≠
= 111 kJ mol−1. It was revealed that, by photoirradiation at 300 nm,
Correspondence
(293 K)
H. Okamoto, Division of Earth, Life, and
Molecular Sciences, Graduate School of
Natural Science and Technology, Okayama
University, Tsushima‐Naka 3‐1‐1, Kita‐ku,
Okayama 700‐8530, Japan.
the syn‐o,o′‐dibenzene isomer 22 underwent facile intramolecular [π4s + π4s]
cycloaddition to reproduce the cage diene isomer 13.
KEYWORDS
Email: hokamoto@okayama‐u.ac.jp
azacyclophane, benzene dimer, cage compound, cyclophane, photocycloaddition
Funding information
Japan Society for the Promotion of Science,
Grant/Award Number: JP24550054
1 | INTRODUCTION
dimerization.[3] Only a few dimerizations of benzenes have
been reported for photolysis of structurally restricted
Benzene dimers, (CH)12 hydrocarbons, have attracted much
attention because they have highly strained and fascinating
molecular structures and are generally unstable and difficult
to access through conventional thermal or catalytic reac-
tions.[1,2] It has been established that benzenes display variety
of photoreaction pathways such as valence isomerizations,
cycloadditions with alkenes, and substitution reactions
(Scheme 1A). However, they rarely undergo photochemical
cyclophane systems in which the 2 benzene cores are fixed
in a close and specific orientation.[4]
Two pioneering studies on benzene photodimerization in
cyclophane systems are the [6 + 6] photocycloaddition of
orthocyclophane 1 by Prinzbach (Scheme 1B)[5,6] and the
cage diene 4 formation of 4‐layered cyclophane 3 by Misumi
and Higuchi (Scheme 1C).[7,8] One of the present authors has
investigated photoreactions of carbon‐bridged [33]‐ and [34]
cyclophanes (5, 7) and revealed that benzene dimers (6, 8)
were
obtained
through
complex
rearrangements
(Scheme 1D,E).[9–11] The present authors reported that pho-
This paper is dedicated to Professor Waldemar Adam on the occasion of his
80th birthday.
tolysis of a diaza[32]paracyclophane 9 produced octahedrane
J Phys Org Chem. 2017;e3726.
wileyonlinelibrary.com/journal/poc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/poc.3726

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OKAMOTO ET AL.
thus, electronic absorption band of hexafluoro[33](1,3,5)
cyclophane remarkably blue shifted compared to that of
nonsubstituted parent cyclophane.[13] Fluorination on the side
chains may modify photochemical properties of a cyclophane
system. Upon photolysis, [22](1,4)anthracenoparacyclophane
having fluorinated side chains underwent unusual intermolec-
ular [π2s + π2s] dimerization.[14,15]
These facts motivated us to investigate the photoreaction
of
a
fluorine‐substituted azacyclophane. Fluorinated
azacyclophanes would display different photochemical prop-
erties compared with the previously reported photoreactive
cyclophanes by virtue of both the nitrogen‐containing bridg-
ing and fluorine substituent effects. Furthermore, it has been
expected that the introduction of fluorine atoms stabilizes a
photochemically formed strained product structure(s)[16] and
enables us to isolate the hitherto unknown photoproduct.
Herein, we report the synthesis of novel fluorinated
azacyclophane 12 and its photoreaction affording cage diene
13 (Chart 1). Structural analysis, as well as the photo‐ and
thermal behavior of cage diene 13, are also described.
2 | RESULTS AND DISCUSSION
2.1 | Synthesis and structure of fluorinated
azacyclophane 12
The synthetic route to fluorinated azacyclophane 12 is shown
in Scheme 2. Coupling between the components 14 and 15 in
the presence of NaH afforded azacyclophane 16. As
SCHEME 1 Photoreactions of cyclophanes affording benzene dimers
CHART
1
Structures of fluorinated azacyclophane 12 and
photoproduct 13
10 and cage diene 11 as the major and minor products,
respectively (Scheme 1F).[12] As the corresponding carbon‐
bridged [32]paracyclophane was essentially inert against
photoirradiation, the nitrogen‐containing bridges have been
considered to play a critical role in modifying photoreactivity
of the paracyclophane system.[12]
Currently, little information is available concerning effects
of aromatic‐core substituents on the photochemical behavior
of the [32]paracyclophane system, namely, that of the nitro-
gen‐bridged cyclophanes.[4] Thus, it would be of interest to
reveal the substituent effects on the photochemical behavior.
It has been reported that introduction of fluorine atoms into
aromatic cores of [33]cyclophanes significantly affected the
electronic features of the carbon‐bridged cyclophane,
SCHEME 2 Synthetic route to azacyclophane 12

OKAMOTO ET AL.
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tosylamide 16 was hardly soluble in common organic sol-
vents, it was used in the following reaction without purifica-
tion. Detosylation of 16 was achieved by heating in
concentrated sulfuric acid and subsequent reprotection on
the amino moiety with pivaloyl chloride afforded the desired
azacyclophane 12 in 39% overall yield from 14 and 15. The
pivaloyl amide was selected because of the following 2 rea-
sons: It shows no absorption band in the wavelength region
where azacyclophane chromophore displays an absorption
band(s) and the amide C–N bond freely rotates at room tem-
perature (rt).[17] The latter makes compounds characteriza-
tion easy due to negligible contribution of amide rotamers.[12]
Azacyclophane 12 was characterized by spectroscopic as
well as elemental analyses. Furthermore, the structure of
azacyclophane 12 was studied by an X‐ray crystallographic
analysis (Figure 1). An X‐ray structure of azacyclophane 9
having no substituent on the benzene cores is also shown to
reveal the effects of fluorine atoms on the azacyclophane
structure. Selected structural parameters are summarized in
Table 1. In the solid state, the side bridges of azacyclophanes
9 and 12 adopted a chair conformation (Figure 1A,E) with
the 2 amide parts in an anti orientation (Figure 1B,F). For
fluorinated derivative 12, the distance between the mean
planes of the benzene rings d1 is 2.942 Å, which is shorter
than that of nonsubstituted one 9 (3.189 Å). Two benzene
rings in 12 are tilted by d4 = 0.928 Å from full overlap while
those in 9 almost fully overlapped (d4 = 0.080 Å). It is con-
sidered that the fluorinated benzene rings in azacyclophane
12 deviated from full overlap conformation to reduce repul-
sive interaction of polarized Cδ+–Fδ− bonds between the 2
benzene rings resulting in the parallel‐displacement confor-
mation.[18,19] The benzene rings of the azacyclophanes 9
FIGURE 1 X‐ray structures of azacyclophanes 9 and 12. A and B, Molecular structure of 12 top and front views, respectively. C and D, Crystal
packing of 12 viewed from ab and ac planes, respectively. Hydrogen atoms are omitted for clarity. E and F, Molecular structure of 9 top and front
views, respectively. Hydrogen atoms are omitted for clarity. G and H, Crystal packing of 9 viewed from ab and ac planes, respectively
TABLE 1 Structural parameters of azacyclophanes 9 and 12
Compound
d1 (Å)a
d2 (Å)b
d3 (Å)c
d4 (Å)d
θ (°)e
12
2.942
9
3.189
3.148, 3.130
3.007
3.250, 3.237
3.091
0.928
0.080
5.61, 5.05
6.46, 5.90
aDistance between mean planes of the benzene rings.
bNonbonding distance between the bridging carbon atoms.
cNonbonding distance between the nonbridging carbon atoms.
dTilting of the 2 benzene rings.
eFolding angle of the benzene rings.

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OKAMOTO ET AL.
and 12 distorted slightly from planarity with folding angle
θ = 5.05–6.46° (Table 1).
In crystalline, fluorinated molecules of 12 stacked in a
face‐to‐face manner to form one‐dimensional column along
with b axis by an attractive intermolecular C•••F contact
(3.142 Å, Figure 1D). In contrast, for nonfluorinated deriva-
tive 9, molecules aligned in an edge‐to‐face manner (Figure 1
G). The neighboring molecules of 9 contacted through an
interaction between the aromatic hydrogen and carbon atoms
(Figure 1G). Therefore, the fluorine substitution modifies
crystal structure of the azacyclophane system. Such effects
of fluorine substitution on crystal structures have also been
reported for [33]cyclophane system.[13]
2.2 | Absorption and fluorescence spectra of
azacyclophane 12
To obtain an insight into electronic features of azacyclophane
12, electronic spectra were observed in MeCN at rt.
Azacyclophane 12 showed a small absorption band at
270 nm, and the absorption edge showed tailing over 310 nm
(Figure 2, blue line). Very weak fluorescence emission band
was detected with an emission maximum at 363 nm
(Figure 2, red line). As the excitation spectrum of the
363‐nm emission band was identical with the absorption pro-
file (Figure 2, dotted line), the fluorescence emission band
was unambiguously assigned to azacyclophane 12. The
Stokes shift was estimated to be ca. 7500 cm−1 suggesting
that the 2 benzene chromophores strongly interacted in the
excited state to form intramolecular excimer. Such a large
Stokes shift was also observed for nonsubstituted
azacyclophane 9 (ca. 7000 cm−1).[12]
Figure 3 shows frontier orbitals of azacyclophane 12
calculated at the B3LYP/6‐31+G(d) theory. In the lowest
unoccupied molecular orbital (LUMO), p orbitals of the 2
benzene rings overlap through space in an in‐phase manner
(π‐π interaction). It is notable that the aromatic π orbitals
apparently conjugated with the C–N σ bonds and the CH2
FIGURE 3 Frontier molecular orbitals of azacyclophane 12 (B3LYP/
6‐31+G(d))
moieties of the side bridges (σ‐π interaction). Due to both
the π‐π and σ‐π interactions, 2 benzene rings are considered
to strongly interact in the excited state.[12] These theoretical
calculation results are consistent with the experimentally
observed intramolecular excimer‐like fluorescence behavior
of azacyclophane 12.
2.3 | Photochemical reaction of azacyclophane
12
Upon irradiation at 300 nm in CDCl3, azacyclophane 12
underwent an efficient reaction, and formation of a single
product was observed by 1H‐NMR time‐course spectra
(Figure 4). The starting azacyclophane 12 was completely
consumed after 90 minutes of irradiation, and the photoprod-
uct was observed in 85% yield (Figure 4, inset). The photo-
product was isolated, and, based on spectral analysis, the
structure was assigned as a cage diene 13, which had a
pentacyclo[6.4.0.0.2,70.3,1206,9]dodeca‐4,10‐diene skeleton
(Scheme 3) and further confirmed by an X‐ray crystallo-
graphic analysis (vide infra). For a preparative photoreaction,
the isolation yield of cage diene 13 was 70%. As seen from
the inset in Figure 4, the photoproduct 13 was durable under
the investigated photolysis conditions. For the photoreaction
of nonfluorinated derivative 9, octahedrane formation is
known to be the main photochemical process.[12] In contrast,
corresponding octahedrane 17 was not detected for the pho-
toreaction of azacyclophane 12. Therefore, the fluorine atoms
modified the photochemical behavior of the azacyclophane
system. Currently, the reason why octahedrane formation is
suppressed by the fluorination is not clear, and experimental
and theoretical investigations to reveal the substituent effects
are underway.
FIGURE 2 Electronic spectra of azacyclophane 12 (MeCN):
Absorption (blue line), fluorescence emission (red line), and excitation
(dotted line)

OKAMOTO ET AL.
5 of 8
Figure 5 shows an X‐ray structure of cage diene 13. The bond
distances of the C6–C8 and C7–C13 pillars were 1.624 and
1.626 Å, respectively, which were significantly longer than
that of normal C–C single bond in cyclobutane (ca.
1.55 Å).[22] The bond distances of C9–C10 and C5–C11 pil-
lars were, respectively, 1.550 and 1.557 Å showing no signif-
icant distortion compared to that of normal cyclobutane. The
olefinic carbon atoms are placed in proximal positions; non-
bonding C–C distances are 2.990 Å for C2–C3 and 2.983 Å
for C4–C28.
2.5 | Photo‐ and thermal reactions of cage
diene 13
Chemical reactivity, namely, photoreactivity, of the cage
diene framework 18 has been of great interest because it
has been expected as a precursor to hexaprismane skeleton
19.[23,24] We have previously reported that cage diene 11
(see structure in Scheme 1) reverted to azacyclophane 9 upon
300‐nm photolysis.[12] We expected that the fluorination
might affect the photoreaction of the cage diene system.
Additionally, the parent cage diene 18 is known to thermally
FIGURE 4 1H NMR spectra of azacyclophane 12 during 300‐nm
irradiation (in CDCl3). The inset displays time profile for the
photolysis (○: 12, ●: 13)
revert to
2 benzenes through syn‐o,o′‐dibenzene 20
(Scheme 4).[20,21] Therefore, we investigated photochemical
(direct and sensitized) and thermal reactions of cage diene 13.
When cage diene 13 was irradiated at 254 nm in nitrogen‐
purged CD3CN, it was gradually consumed (Figure S1A).
1
Although, in H NMR spectrum of the photolysate, some
very small signals evolved after 2.5 hours, no appreciable
photoproduct was assigned. Thus, cage diene 13 decomposed
to unidentified compounds. Then, xanthone‐sensitized pho-
tolysis was conducted. We selected xanthone as the triplet
sensitizer because it has been reported that xanthone‐sensi-
tized photolysis effectively promotes intramolecular
[π2s + π2s] cycloaddition of [4 + 4]‐type benzene‐naphtha-
lene cross‐dimers.[25,26] When a 1:1.3 mixture of cage diene
13 and xanthone in degassed acetone‐d6 was irradiated at
350 nm, almost no change in its 1H NMR profile was
observed after 1 hour (Figure S1B). From these results,
we conclude that cage diene 13 was photolabile to
decompose in the excited singlet state while inert in the triplet
SCHEME 3 Photochemical reaction of azacyclophane 12
2.4 | Structure of cage diene 13
The
cage
diene
structure
13,
i.e.
pentacyclo[6.4.0.0.2,70.3,1206,9]dodeca‐4,10‐diene skeleton,
has been of research interest as highly strained (CH)12 class
of benzene dimers. Detailed structural features of the parent
compound have yet to be elucidated due to its thermal instabil-
ity undergoing facile dissociation into 2 benzenes.[20,21]
FIGURE 5 X‐ray structure of cage diene 13. Hydrogens are omitted
for clarity
SCHEME 4 Desired photochemical process and reported thermal
reversion of cage diene 18

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OKAMOTO ET AL.
state. Therefore, the desired hexaprismane 21 is currently not
accessible by the photoreaction of cage diene 13 (Scheme 5).
Thermally, cage diene 13 was found to undergo a rear-
rangement affording syn‐o,o′‐dibenzene 22 (Scheme 6), as
in the case reported for the parent compound 18.[20] To
isolate dibenzene 22, a 1,1,2,2‐tetrachloroethane solution of
azacyclophane 12 was irradiated at 300 nm for 1.5 hours sub-
sequently heated at 100°C for 0.5 hour. After removal of the
solvent, the residue was washed with EtOH to afford
dibenzene 22 in 48% isolation yield from 12. The syn‐o,o′‐
dibenzene structure was assigned by NMR spectroscopy as
well as high‐resolution mass spectrometry. Figure 6 com-
pares the 13C NMR spectra between cage diene 13 and
dibenzene 22. The signal of the bridged carbon atom (Cb)
of cage diene 13 resonated at 59.5 ppm (Figure 6, lower);
by contrast, that of dibenzene 18 resonated at 111.4 ppm
(Figure 6, upper). These results provide an evidence that
the bridge carbon atoms Cb are olefinic in the dibenzene
structure 22. Parent syn‐o,o′‐dibenzene 20 has been known
to be an unstable compound because it thermally isomerizes
to anti‐o,o′‐dibenzene, which finally reverted to 2 ben-
zenes.[20,21] Dibenzene 22 was durable at 100°C for several
hours (data not shown). It is presumably because that
dibenzene 22 could not isomerize to the corresponding
FIGURE 6 13C NMR spectra of cage diene 13 (lower) and dibenzene
22 (upper) in CDCl3 (150 MHz)
anti‐o,o′‐dibenzene isomer due to the structural restriction
by the side bridges.
The thermolysis process was monitored by 1H NMR spec-
troscopy in 1,1,2,2‐tetrachloroethane‐d2 to understand the
thermal features of cage diene 13. The thermolysis of cage
diene 13 followed first‐order kinetics as shown in Figure 7
A. Arrhenius plots for the thermolysis displayed a linear cor-
relation to provide an activation energy, Ea = 121 kJ mol−1
(Figure 7). According to the transition state theory, activation
parameters for the thermal isomerization were evaluated to be
ΔH≠ = 118 kJ mol−1, ΔS≠
= 22 J mol−1 K−1, and
(293 K)
ΔG≠(293 K) = 111 kJ mol−1
.
Photochemical behavior of dibenzene 22 was also inves-
tigated. Upon 300‐nm irradiation for 5 minutes, dibenzene
22 quantitatively reproduced cage diene 13 through an intra-
molecular [π4s + π4s] cycloaddition (Scheme 6 and Figure
S2). To the best of our knowledge, the photoconversion of
syn‐o,o′‐dibenzene to cage diene was first observed.
SCHEME 5 Photoreactions of cage diene 13
3 | SUMMARY
Fluorinated azacyclophane 12 was synthesized to reveal the
effects of fluorine atoms on the structural and electronic fea-
tures as well as those on the photoreactivity of the
azacyclophane system. The X‐ray structure of azacyclophane
12 indicated that the molecular structure and crystal packing
were modulated by the fluorination on the benzene rings
(Figure 1 and Table 1). Upon photoreaction, azacyclophane
SCHEME 6 Thermal ring opening and photo ring closure of the
cage diene system

OKAMOTO ET AL.
7 of 8
were dropped into DMF (400 mL) at rt under a nitrogen atmo-
sphere during a period of 5.5 hours. The mixture was stirred for
additional 37 hours at rt. The resulting mixture was concen-
trated under reduced pressure and MeOH (20 mL) was added
to the residue. The precipitate formed was collected to afford
azacyclophane 16 (1.62 g) as colorless crystals. The compound
16 was used in the following reaction without further purifica-
tion because of its poor solubility in common solvents.
Compound 16 (308 mg, 0.45 mmol) was dissolved in
95% H2SO4 (4 mL) and heated at 70°C for 3 hours. After
cooling, the solution was cautiously diluted with water and
extracted with CH2Cl2 (3 × 15 mL). The water phase was
basified with 10 % NaOH aq. and extracted with CHCl3
(3 × 15 mL). The solution was dried over anhyd. MgSO4.
After removal of the solvent, the residue was dissolved in
CH2Cl2 (5 mL), and Et3N (181 μL, 1.30 mmol) was added.
To the solution was dropwise added a solution of pivaloyl
chloride (159 μL, 1.30 mmol) in CH2Cl2 (1 mL) at 0°C under
a nitrogen atmosphere. The mixture was then stirred at rt for
3 hours. The solution was extracted with CHCl3 (30 mL), and
the extract was dried over anhyd. MgSO4. After removal of
the solvent, azacyclophane 12 was obtained as colorless crys-
tals (0.16 g, 39% from 14 and 15).
Physical data: mp 289–292°C. 1H NMR (300 MHz,
CDCl3) δH = 1.44 (s, 18H), 4.98 (s, 8H). 13C NMR
(150 MHz, CDCl3) δC = 29.0, 40.1, 41.7, 115.5, 145.0
(JCF = 253 Hz), 177.9. 19F NMR (282 MHz, CDCl3).
δF = −142.0 (s). IR (neat) νmax 1638 cm−1 (C═O). Anal.
Calcd for C26H26F8N2O2: C, 56.73; H, 4.76; N, 5.09. Found:
C, 56.67; H, 4.59; N, 5.04. HRMS (FAB) Calcd. for
C26H27F8N2O2: 551.1946. Found: 551.1919 ([M + H]).
FIGURE 7 A, First‐order plots and B, Arrhenius plots for thermal
isomerization from cage diene 13 to dibenzene 22 in 1,1,2,2‐
tetrachloroethane‐d2
12 efficiently produced cage diene 13 as the sole product
(Scheme 3). These results show clear contrast to
photoreactivity of nonsubstituted analogue 9, which photo-
chemically produced octahedrane 10 as the major product. It
was found that the fluorination on the aromatic rings drasti-
cally modified the photoreaction modes of the azacyclophane
system. The present results suggest that, by appropriately
altering the aromatic substituents, one would control the ben-
zene‐benzene photodimerization modes of the azacyclophane
system. Currently, theoretical and experimental studies to
clarify the substituent effects that modify photoreactivities
of the azacyclophane system are underway. The structure of
the cage diene 13 was successfully established by an X‐ray
crystallographic analysis. The bond distances of the C6–C8
and C7–C13 pillars are very long as C–C single bond (approx-
imately 1.624 Å, see Figure 5), which suggests the thermal
instability of the cage diene structure.
4.2 | Cage diene 13
Five solutions of azacyclophane 12 (5 × 2.0 mg, 5 × 3.6 μmol)
in CH2Cl2 (5 × 2 mL) was purged with nitrogen and irradi-
ated at 300 nm for 90 minutes at rt in Pyrex NMR tubes.
After removal of the solvent under reduced pressure, the res-
idue was washed with EtOH to afford cage diene 13 as color-
less crystals (7.0 mg, 70%).
1
Physical data: mp > 280°C dec. H NMR (300 MHz,
CDCl3) δH = 1.31 (s, 18H), 3.79 (d, 4H, J = 12.5 Hz),
4.62 (d, 4H, J = 12.5 Hz). 13C NMR (150 MHz, CDCl3)
δC = 27.4, 39.4, 45.5, 59.5, 92.7 (d, JCF = 274 Hz), 142.8
(d, JCF = 269 Hz), 177.8. 19F NMR (282 MHz, CDCl3)
δF = −191.3 (s, 4F), −142.6 (s, 4F). IR (neat) νmax
1634 cm−1 (C═O). HRMS (FAB) Calcd. for C26H27F8N2O2:
551.1946. Found: 551.1966 ([M + H]).
4 | EXPERIMENTAL
4.1 | N,N′‐dipivaloyl‐5,6,8,9,14,15,17,18‐
octafluoro‐2,11‐diaza[32]paracyclophane 2
A mixture of NaH (60% in mineral oil, 0.304 g, 12.7 mmol) and
tosylamide 15 (2.02 g, 3.91 mmol) in DMF (70 mL) and a solu-
tion of dibromide 14 (1.31 g, 3.91 mmol) in DMF (70 mL)
4.3 | o,o′‐dibenzene 22
Five Pyrex tubes, each containing
a
solutions of
azacyclophane 12 (5 × 2.0 mg, 5 × 3.6 μmol) in

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OKAMOTO ET AL.
[10] C. Lim, M. Yasutake, T. Shinmyozu, Angew. Chem. Int. Ed. 2000,
39, 578.
CHCl2CHCl2 (5 × 2 mL, purged with nitrogen), were irradi-
ated at 300 nm for 90 minutes at rt to afford cage diene 13.
The solutions were then heated at 100°C for 0.5 hour. After
removal of the solvent under reduced pressure, the residue
was washed with EtOH to afford o,o′‐dibenzene 22 as color-
less crystals (4.8 mg, 48% from 12).
[11] R. Nogita, K. Matohara, M. Yamaji, T. Oda, Y. Sakamoto, T.
Kumagai, C. Lim, M. Yasutake, T. Shimo, C. W. Jefford, T.
Shinmyozu, J. Am. Chem. Soc. 2004, 126, 13732.
[12] H. Okamoto, H. Ishida, K. Satake, M. Kimura, J. Am. Chem. Soc.
2006, 128, 16508.
Physical data: mp > 300°C. 1H NMR (600 MHz, CDCl3)
δH = 1.33 (s, 18H), 3.92 (d, 4H, J = 16.6 Hz), 5.22 (d, 4H,
J = 16.6 Hz). 13C NMR (150 MHz, CDCl3) δC = 28.6,
39.8, 42.9, 91.6 (d, J = 249 Hz), 111.4, 147.5 (d,
JCF = 271 Hz), 178.3. 19F NMR (282 MHz, CDCl3)
δF = −181.2 (s, 4F), −127.2 (s, 4F). IR (neat) νmax
1634 cm−1 (C═O). HRMS (FAB) Calcd. for C26H27F8N2O2:
551.1946. Found: 551.1918 ([M + H]).
[13] T. Koga, M. Yasutake, T. Shinmyozu, Org. Lett. 2001, 3, 1419.
[14] W. R. Dolbier Jr., Y.‐A. Zhai, M. A. Battiste, K. A. Abboud, I.
Ghiviriga, K. Wu, ARKIVOC 2006, 3, 97.
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Financial support by KAKENHI from Japan Society for the
Promotion of Science (No. JP24550054) is gratefully
acknowledged. Part of this work was performed under the
Cooperative Research Program of the “Network Joint
Research Center for Materials and Devices.” HO thanks Prof
Manabu Abe (Hiroshima University) and Prof Minoru
Yamaji (Gunma University) for active discussions. The
authors are grateful to the Micro Elemental Analysis Team
of Okayama University for the combustion analysis of novel
compounds.
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How to cite this article: Okamoto H, Kozai T,
Okabayashi Z, et al. Synthesis, structure, and
photoreactions of fluorinated 2,11‐diaza[32]
paracyclophane: Photochemical formation of cage‐
diene type benzene dimer. J Phys Org Chem. 2017;
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