Synthesis of 2,24-Diene-12,13,15,16,34,35,37,38-octaphenyl[44]triphenylparacyclophane

Article abstract of DOI:10.1055/a-1479-6611

A new octaphenyl[4.4]triphenylparacyclophanediene was readily synthesized in six steps from p -xylene via the installment of bromine atoms, replacement with a vinyl group, carbonylative coupling, intermolecular followed by intramolecular double Grubbs olefin metathesis, Knoevenagel condensation, and Diels-Alder cycloaddition. The belt-shaped structure and trans -stereochemistry of the alkene moieties of the octaphenyl[4.4]triphenylparacyclophane and a synthetic intermediate, 2,21-dioxo-11,30-diene[3.4.3.4]paracyclophane, were determined by X-ray crystallography. The synthetic methodology leading to octaphenyl[4.4]triphenylparacyclophane is applicable for the synthesis of substituted triphenylparacyclophanes and possibly their corresponding bis-hexabenzocoronenylparacyclophanes via a Scholl-Mullen oxidative aryl-aryl coupling reaction.

Full text of DOI:10.1055/a-1479-6611

SYNTHESIS
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart
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021, 53, A–F
paper
A
en
Synthesis
B. Wiredu et al.
Paper
Synthesis of 2,24-Diene-12,13,15,16,34,35,37,38-octaphenyl[4.4]-
triphenylparacyclophane
Bernard Wiredu
Mahendra Thapa
Sheen Y. Hua
John Desper
O
1
) KOH
PhCOCOPh
Duy H. Hua*
2)
Ph
Ph
Department of Chemistry, Kansas State University, Manhattan,
KS 66506, USA
duy@ksu.edu
O
Made from p-xylene in 4 steps
De Meu pya ai CHlr otd. mrHu r yeeu @nsa pt k oos nuf d.Cei hnd egu mA i us t rh yo ,rKansas State University, Manhattan, KS 66506, USA
7
,8
Received: 03.03.2021
Accepted after revision: 12.04.2021
Published online: 12.04.2021
bled tubular molecules, selective binding to guest mole-
9
10
cules, and unique bioactivity. Herein, we described a short,
effective synthesis of 2,24-diene-12,13,15,16,34,35,37,38-
octaphenyl[4.4]triphenylparacyclophane (1) (Figure 1),
which may serve as an intermediate for the construction of
self-assembled cyclophanes and supramolecules. Triphen-
ylparacyclophane 1, a symmetrical molecule, possesses two
alternated but-2-enyl-hexaphenylbenzene units. The but-
DOI: 10.1055/a-1479-6611; Art ID: ss-2021-m0106-op
Abstract A new octaphenyl[4.4]triphenylparacyclophanediene was
readily synthesized in six steps from p-xylene via the installment of bro-
mine atoms, replacement with a vinyl group, carbonylative coupling, in-
termolecular followed by intramolecular double Grubbs olefin metathe-
sis, Knoevenagel condensation, and Diels–Alder cycloaddition. The belt-
shaped structure and trans-stereochemistry of the alkene moieties of
the octaphenyl[4.4]triphenylparacyclophane and a synthetic intermedi-
ate, 2,21-dioxo-11,30-diene[3.4.3.4]paracyclophane, were determined
by X-ray crystallography. The synthetic methodology leading to octa-
phenyl[4.4]triphenylparacyclophane is applicable for the synthesis of
substituted triphenylparacyclophanes and possibly their corresponding
bis-hexabenzocoronenylparacyclophanes via a Scholl–Mullen oxidative
aryl-aryl coupling reaction.
2
-ene moieties allow further functional group transforma-
tion and the phenyl units can be appended with substitu-
ents. Notably, substituted triphenylparacyclophane 1 may
be used to produce a fragment of small and well-defined
carbon nanotubes via an aryl-aryl dehydrogenative cou-
11
pling reaction, whose application in materials and bioma-
terials can be explored.
Various cyclophanes and belt-liked macrocycles have
Key words belt-shaped molecules, cyclophanes, octaphenyl[4.4]-
triphenylparacyclophane, Grubbs olefin metathesis, Knoevenagel
condensation, Diels–Alder cycloaddition, carbonylative coupling
6,12
been synthesized by double Wittig reaction,
double
1
3
Diels–Alder reaction, titanium-mediated double coupling
1
4
of 3,3′-(Z)-stilbenedicarbaldehyde, cyclodimerization of
Supramolecular chemistry1 has led to the design of
cumulenes generated from 1,χ-elimination reaction, dou-
15
2
many fascinating molecules possessing useful properties.
ble Suzuki coupling reaction of diiodoarenes and diarylbor-
1
6
In-plane aromaticity, magnetically induced currents, and
photophysical and photochemical properties of belt-
shaped molecules, assembled by fused benzene rings or
carbon chains, have offered fascinating discoveries in the
past few years. For example, liquid crystalline crown ether
substituted phthalocyanines undergo self assembly to form
molecular cables, consisting of a central electron wire sur-
onates, and 2nd generation Grubbs–ZnCl catalyzed intra-
2
molecular metathesis of 1,1′-bis(but-3-enyl)-2,2′-bisbenz-
1
7
imidazole. The latter reported only ten- and twelve-
membered macrocycles and a 1:1 mixture of E- and Z-iso-
mers were found in the twelve-membered ring system.17
We envisioned that a short synthesis of cyclophane 1 could
derive from biscyclopentadienylcyclophane 2, which might
obtain from diketocyclophane 3 as depicted in Figure 1.
Diketocyclophane 3 could be made from a double Grubbs
olefin metatheses of 1,3-diarylacetone 4, which could read-
ily be achieved from the carbonylation of 1-allyl-4-(bro-
momethyl)benzene (5). Synthesis of substituted hexaaryl-
3
rounded by four ion channels. A molecular tweezer, de-
rived from a rigid bicyclic aromatic ring system, binds se-
lectively to lysine and arginine residues of peptides,
demonstrating a molecular recognition.4 Planar chiral
bis(thiourea)-[2.2]paracyclophanes serve as chiral catalysts
5
18
for enantioselective Michael addition reaction. Our interest
benzenes has been reported via the carbonylation fol-
6,7
in cyclophanes, stemming from non-covalent –, –cat-
lowed by condensation with benzil and Diels–Alder
ion, and hydrophobic interactions, may lead to self-assem-
©
2021. Thieme. All rights reserved. Synthesis 2021, 53, A–F
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
Synthesis
B. Wiredu et al.
Paper
Ph
Ph
Ph
Ph
O
O
O
O
2
3
1
O
Br
4
5
Figure 1 Retrosynthesis of cyclophane 1
cycloaddition.19 However, 1,3-bis(4-allylphenyl)propan-2-
one (4) and its transformed cyclophanes 1–3 have not been
reported previously.
droxide, and a catalytic amount of phase-transfer reagent,
tetrabutylammonium hydrogensulfate, in CH Cl /H O at 25
2
2
2
°C for 3 h gave a 50% yield of 4. Using 3 mol% of 2nd genera-
tion Grubbs catalyst under refluxing dichloromethane for
16 h, diarylacetone 4 underwent homocoupling followed by
ring-closing olefin metatheses to give a 60% yield of cyclo-
phane 3, whose structure was unambiguously determined
by single-crystal X-ray analysis (Figure 2). The X-ray struc-
1
-Allyl-4-(bromomethyl)benzene (5) was synthesized
from the dibromination of p-xylene (6) with 2 equiv of N-
bromosuccinimide (NBS) and a catalytic amount of benzoyl
peroxide followed by monosubstitution with 1 equiv of vi-
nylmagnesium bromide and HMPA in diethyl ether and THF
1
7
(
1:1), in a 37% overall yield (Scheme 1). A reported carbon-
ture showed trans configuration in both alkene moieties,
indicating the Grubbs olefin metathesis is stereoselective
under the reaction conditions. Double Knoevenagel con-
densation of diketone cyclophane 3 and 2 equiv of benzil
1
8,19
ylative coupling reaction
was followed for the prepara-
tion of symmetrical diarylacetone 4. Hence, treatment of
benzyl bromide 5 with 0.5 equiv of Fe(CO) , calcium hy-
5
1
2
) NBS
cat. (PhCOO)2
O
0
.5 equiv Fe(CO)5
Br
Ca(OH)2
) CH2=CHMgBr
HMPA, THF/Et2O
Bu4NHSO4
H2O, CH2Cl2
5
4
6
25 °C, 24 h
(37% overall yield)
(50% yield)
O
Ph
Ph
Ph
3
mol%
2nd generation
Grubbs catalyst
KOH, EtOH
reflux, 5 h
O
O
CH2Cl2, reflux
O
1
6 h
Ph
Ph
Ph
O
3
7
O
2
(60% yield)
(86% yield)
Ph
Ph
(
8)
Ph-O-Ph
reflux
9
1
(40% yield)
Scheme 1 Synthesis of 2,24-diene-12,13,15,16,34,35,37,38-octaphenyl[4.4]triphenylparacyclophane (1)
©
2021. Thieme. All rights reserved. Synthesis 2021, 53, A–F

C
Synthesis
B. Wiredu et al.
Paper
(
7) under refluxing ethanol in the presence of potassium
hydroxide afforded an 86% yield of bis-cyclopentadienone
cyclophane 2. Diels–Alder cycloaddition reaction of 2 and 2
equiv of diphenylacetylene (8) in refluxing diphenyl
1
9,20
ether
with the concomitant of carbon monoxide fur-
nished octaphenyl[4.4]triphenylparacyclophane 1 in 40%
yield. An attempt to carry out the Diels–Alder reaction in
refluxing 1,2-dichlorobenzene gave no desired product. The
bulky cyclophane molecule 2 likely requires a higher activa-
tion energy for the intermolecular Diels–Alder reaction.
The structure of molecule 1 was firmly established through
a single-crystal X-ray analysis and the ORTEP drawing is de-
picted in Figure 3. The trans-stereochemistry of the two
alkene moieties in 1 remains intact. The distance between
the centers of the two central benzene rings of cyclophane
Figure 3 ORTEP drawing of the single-crystal X-ray analysis of triphen-
ylparacyclophane 1; CCDC 2065345. Selected bond lengths (Å) and an-
gles (°): C4–C5 1.544(4), C8–C11 1.504(4), C11–C12 1.406(4), C11–
C16 1.412(4), C13–C14 1.412(4), C14–C15 1.402(4), C14–C17
1
is 14.29 Å. It possesses a similar cavity as that of [8]cyclo-
2
1
paraphenylene. The two central phenyl rings, each at-
tached to six aryl rings, are parallel, while the remaining
twelve phenyl rings are slightly off from perpendicular, as
found in the crystal structure (Figure 3).
1
.496(4), C15–C16 1.407(4), C20–C21 1.379(4), C1–C20 1.527(4),
C1–C2 1.468(5), C2–C3 1.359(5), C3–C4 1.500(4); C13–C14–C15
20.3(2), C13–C14–C17 119.4(2), C6–C5–C10 117.8(3), C19–C20–
1
C21 117.7(3), C18–C19–C20 121.5(3), C5–C10–C9 121.2(3), C1–C2–
C3 125.0(3), C2–C3–C4 122.2(3).
Information of the two single-crystal X-ray structural
analyses of molecules 3 and 1 are summarized in Table 1,
including their formulas, crystal data, methods of collec-
tion, and methods of structural solutions and refinement.22
Selected bond lengths and angles are listed in Figures 2 and
3
.
Table 1 Formulas, Crystal Data, Method of Collection, and Methods of
Structural Solutions and Refinement of X-ray Structures of 3 and 1
Molecule
3a
1b
Formula
FW
C
38
H
36
O
2
92 68
C H
524.67
1170.28
120(15)
0.71073
orthorhombic
Pbca
T (K)
120(15)

(Å)
0.71073
monoclinic
P2(1)/c
Crystal system
Space group
a (Å)
13.9091(5)
6.2647(2)
17.1630(6)
90
23.3936(11)
11.9225(5)
23.4018(11)
90
b (Å)
c (Å)



(°)
(°)
(°)
107.354(2)
90
90
90
V (Å3)
1427.44(9)
2 (molecules)
1.221
6527.0(5)
4 (molecules)
1.191
Z
d
calcd (g/m3)
Abs coeff (mm–1
F(000)
)
0.073
0.067
Figure 2 ORTEP drawing of the single-crystal X-ray analysis of diketone
cyclophane 3; CCDC 2065344. Selected bond lengths (Å) and angles (°):
C1–C2 1.5171(14), C2–C3 1.5226(14), C2–O2 1.2090(12), C1–C17
560.0
2473.0
1
1
1
1
.5183(14), C7–C10 1.5182(14), C10–C11 1.5023(15), C11–C12
.3336(15), C14–C15 1.3976(14); C1–C2–C3 116.51(8), C3–C4–C5
20.71(9), C1–C2–O2 122.15(9), C6–C7–C10 120.63(9), C7–C10–C11
12.66(9), C10–C11–C12 124.34(10), C11–C12–C13 124.88(10),
2θ range (°)
Reflns collected
4.974–64.03
31687
4.878–60.038
50637
Independent reflections/Rint
% Completeness /θ (°)
4967/0.0369
99.9/32.01
9131/0.0550
95.8/30.02
C14–C15–C16 121.24(9).
©
2021. Thieme. All rights reserved. Synthesis 2021, 53, A–F

D
Synthesis
B. Wiredu et al.
Paper
Molecule
3a
1b
none
Chemicals were purchased from Fisher Scientific and VWR interna-
tional LLC. Solvents were dried over appropriated drying agent such
as CaH2 (for DMF, CH Cl , and MeCN), or Na/benzophenone (for THF
Abs corr
none
2
2
Max, min transm
0.9891, 0.9783
0.9920, 0.9801
and Et O) followed by distillation. Column chromatography was car-
2
1
full-matrix on F2
full-matrix on F2
ried out on silica gel (200–400 mesh). H NMR spectra (400 MHz and
Least squares refinement method
Data/restraints/params
GOF (on F2)
2
00 MHz) and 13C NMR spectra (100 MHz and 50 MHz) were recorded
4967/0/181
1.030
9131/0/416
1.051
on Varian Unity plus 400 MHz and 200 MHz spectrometers, and mea-
1
sured from a solution in CDCl unless otherwise mentioned. H NMR
3
1
3
were recorded relative to TMS ( = 0) or CHCl ( = 7.26) and C NMR
R
wR
1
(obsd)
0.0467
0.1250
0.0815
0.2272
3
c
relative to CDCl ( = 77.0). Mass spectra were obtained from an API
2
(all)
3
2
000-triple quadrupole ESI-MS/MS mass spectrometer (Applied Bio-
Max/min residual electron density
0.53/–0.20
1.06/–0.37
–
3
systems). HRMS were obtained from a LCT Premier (Waters Corp.,
Milford MA) time of flight mass spectrometer at the University of
Kansas. The instrument operated at 10,000 resolution (W mode) with
dynamic range enhancement that attenuates large intensity signals.
Mass correction for exact mass determinations was made automati-
cally with the lock mass feature in the MassLynx data system. Single-
crystal X-ray structures were obtained from a Siemens SMART 1000
low-temperature (LT-2A) single-crystal X-ray diffractometer.
(
e /Å )
a
b
c
Bruker Platinum 135; Cu rotating anode/optical mirrors.
Bruker APEX II; Mo sealed tube/monochromator.
1
2
2
2
2
2)2]}1/2.
R = Σ[F – F ]/Σ[F ]; wR = {Σ[w(F – F ) ]/Σ[w(F
0 c 0 0 c 0
Hexa-peri-hexabenzocoronene has been prepared from
hexaphenylbenzene via a Scholl–Mullen oxidative aryl-aryl
coupling reaction.1
1,20,23
We have attempted to convert
1
,4-Bis(bromomethyl)benzene
triphenylparacyclophane 1 into bishexabenzocoronenylpa-
racyclophane 9 (Scheme 1) via the Scholl–Mullen reaction
using various reagents in diluted solution including FeCl in
To a solution of p-xylene (6; 45 mL, 0.365 mol) in benzene (600 mL)
under argon were added NBS (129 g, 0.731 mol) and benzoyl peroxide
3
(
3.38 g, 0.015 mol). The mixture was heated under reflux for 4 h. One
MeNO , Cu(OTf) in CS , and FeCl /Cu(OTf) in CS . In all cas-
2
2
2
3
2
2
half of the benzene of the reaction solution was removed using a rota-
ry evaporator with a cold trap, and the resulting residue gradually
cooled to 0 °C to obtain a white precipitate. The white solid was col-
lected by filtration, washed several times with water, and dried under
vacuum overnight to give 1,4-bis(bromomethyl)benzene as a white
solid; yield: 58.0 g (60%); mp 141.0–144.0 °C (Lit.24 142–144 °C).
es, insoluble colored materials, consisting of purple or
black, were obtained and the desired bishexabenzocoro-
nenylparacyclophane 9 was not identifiable. Various organ-
ic and inorganic solvents were attempted to dissolve the
crude products, including hexane, toluene, diethyl ether,
1H NMR (200 MHz, CDCl
):  = 7.37 (s, 4 H, Ar-H), 4.48 (s, 4 H, CH
C NMR (50 MHz, CDCl ):  = 138.2 (2 C), 129.7 (4 C), 33.0 (2 C).
-Br).
2
ethyl acetate, chloroform, DMF, DMSO, H O, trifluoroacetic
3
2
1
3
acid, THF/aqueous HCl or H SO solution at room tempera-
2
4
3
ture or elevated temperature (~70 °C), but no detectable de-
sired material was found in the solution. The but-2-enyl
functions of octaphenyl[4.4]triphenylparacyclophane can
be functionalized by the installation of alkyl chains or polar
groups. Substituted aromatic ring systems, such as substi-
tuted benzils and diphenylacetylenes, can be used in the
described synthetic scheme to generate substituted triph-
enylparacyclophane derivatives, which may afford the syn-
thesis of solubilized substituted bis-hexabenzocoronenyl-
paracyclophanes.
The spectral data are in agreement with those reported.25
1-Allyl-4-(bromomethyl)benzene (5)
To a solution of 1,4-bis(bromomethyl)benzene (8.0 g, 30.3 mmol) in
Et O/THF (1:1, 160 mL) under argon at 25 °C were added 1.0 M vinyl-
2
magnesium bromide in THF, 31 mL, 31 mmol) and freshly distilled
HMPA (5.3 mL, 30.3 mmol). The mixture was stirred for 24 h, diluted
with aq sat. NH Cl solution, and extracted with Et O (3 ×). The com-
4
2
bined organic layers were washed with water and brine, dried (anhyd
Na SO ), concentrated, and column chromatographed (silica gel, gra-
2
4
dient hexane/Et O) to give compound 5 (3.83 g, 62%) as an oil along
2
In summary,
a
facile synthesis of 2,24-diene-
with recovered 1,4-bis(bromomethyl)benzene (1.5 g, 19%).
12,13,15,16,34,35,37,38-octaphenyl[4.4]triphenylparacyclo-
1
H NMR (200 MHz, CDCl ):  = 7.33 (d, J = 8.2 Hz, 2 H), 7.17 (d, J = 7.8
3
phane was accomplished starting from p-xylene in six steps
with a 3.8% overall yield and is amendable to large-scale
synthesis. The key step involved a Grubbs ruthenium-cata-
lyzed one-pot homocoupling olefin metathesis of 1,3-bis(4-
allylphenyl)propan-2-one accompanied by ring-closing ole-
fin metathesis to generate 2,21-dioxo-11,30-trans,trans-di-
ene[3.4.3.4]paracyclophane. Only trans-stereochemistry
was found in the paracyclophane product, suggesting both
intermolecular and intramolecular Grubbs olefin metathe-
ses in this system are stereoselective. The paracyclophane
underwent condensation with two moles of benzil and sub-
sequent Diels–Alder cycloaddition with diphenylacetylene
furnished the targeted octaphenyl[4.4]triphenylparacyclo-
phane.
Hz, 2 H), 6.00–5.90 (m, 1 H, =CH), 5.11–5.05 (m, 1 H, =CH ), 5.04–4.90
2
(m, 1 H, =CH
), 4.49 (s, 2 H, CH Br), 3.39 (d, J = 6.6 Hz, 2 H, CH C=).
2 2
2
1
3
C NMR (50 MHz, CDCl ):  = 140.7, 137.2, 135.8, 129.4 (2 C), 129.3 (2
3
C), 116.4, 40.1, 33.8.
MS (ESI, MeOH): m/z (%) = 233.01 (100), 235.21 (97.3) (M + Na+).
HRMS-ESI: m/z [M + Na]+ calcd for C10H11BrNa: 232.9942; found:
233.1167.
The spectral data are in agreement with those reported.26
1,3-Bis(4-allylphenyl)propan-2-one (4)
To a mixture of Ca(OH) (0.98 g, 13.3 mmol) and of Bu NHSO (0.56 g,
2
4
4
1.66 mmol) under argon were added degassed water/CH Cl (1:1, 60
2
2
mL); argon gas was bubbled into the solution for 5 min. To it was add-
ed Fe(CO)5 (0.5 mL, 3.8 mmol) under vigorous stirring. A solution of
©
2021. Thieme. All rights reserved. Synthesis 2021, 53, A–F

E
Synthesis
B. Wiredu et al.
Paper
compound 5 (1.40 g, 6.63 mmol) in CH Cl (5 mL) was added to the
mixture via a cannula. After stirring at 25 °C for 3 h, air was bubbled
color of compound 2 was discharged to give an off pale-yellowish col-
ored solution. The solvent was removed by distillation under high
vacuum and the residue was subjected to column chromatography
2
2
into the reaction solution to destroy excess Fe(CO) , and the resulting
5
mixture was filtered through a fritted funnel. The filtrate was diluted
with 1 M HCl (10 mL) and extracted with EtOAc (3 ×). The combined
(silica gel, gradient hexane/Et O) to yield compound 1 as a white sol-
id; yield: 20 mg (40%); mp 76.0–77.0 °C.
2
organic layers were washed with aq NaHCO , water, and brine, dried
1
3
H NMR (200 MHz, CDCl ):  = 7.20–6.25 (m, 56 H, ArH), 5.50–5.25 (br
3
(
anhyd Na SO ), filtered, and concentrated to dryness. The residue
2 4
s, 4 H, =CH), 3.05–2.80 (br s, 8 H, CH2).
1
was subjected to column chromatography (silica gel, hexane/Et O 4:1)
2
3
C NMR (100 MHz, CDCl ):  = 141.2, 140.7, 138.4, 137.7, 133.4,
3
to give 4 as an oil; yield: 0.48 g (50%).
1
31.7, 130.8, 129.9, 127.0, 126.6, 125.4, 38.1.
1
H NMR (400 MHz, CDCl ):  = 7.16 (d, J = 8.4 Hz, 4 H), 7.09 (d, J = 8.4
3
HRMS-ESI (micrOTOF-Q, electrospray): m/z [M + Na]+ calcd for
C92H68Na: 1195.5213; found: 1195.5183.
Hz, 4 H), 6.02–5.92 (m, 2 H, =CH), 5.11 (dd, J = 12, 2 Hz, 2 H, =CH2),
5
.07 (dd, J = 9, 2 Hz, 2 H, =CH ), 3.70 (s, 4 H), 3.39 (d, J = 6.6 Hz, 4 H).
2
1
3
The compound crystallized (Et O) to give single crystals, whose struc-
2
ture was solved by X-ray analysis.
C NMR (100 MHz, CDCl ):  = 206.2, 139.1 (2 C), 137.5 (2 C), 132.0 (2
3
C), 129.8 (4 C), 129.2 (4 C), 116.1 (2 C), 48.9 (2 C), 40.1 (2 C).
HRMS-ESI: m/z [M
H]+ calcd for C21H23O: 291.1749; found:
+
291.1747.
Conflict of Interest
The authors declare no conflict of interest.
2
,21-Dioxo-11,30-diene[3.4.3.4]paracyclophane (3)
To a solution of ketone 4 (0.20 g, 0.69 mmol) in degassed CH Cl (40
2
2
mL) under argon was added dropwise a solution of 2nd generation
Grubbs catalyst (17.5 mg, 0.02 mmol) in degassed CH Cl (10 mL) over
Funding Information
2
2
a period of 30 min. After refluxing for 16 h, the mixture was cooled to
5 °C, diluted with water (30 mL) and extracted with CH Cl (3 × 30
Research reported in this publication was supported in part by the
National Institute of General Medical Sciences of the National Insti-
tutes of Health under award number NIH R01GM128659 (to D.H.H.)
and National Science Foundation (CHE-1662705). The content is sole-
ly the responsibility of the authors and does not necessarily represent
the official views of the National Institutes of Health. This material
was based upon work in part supported by the National Science Foun-
dation under 1826982 (to D.H.H.) for the purchase of an NMR spec-
2
2
2
mL). The combined extracts were washed with water and brine, dried
MgSO ), concentrated, and column chromatographed (silica gel, gra-
(
4
dient hexane/Et O) to give paracyclophane 3 as a white solid; yield:
2
0.108 g (60%); mp 61.0–62.0 °C.
1
H NMR (200 MHz, CDCl ):  = 7.11 (d, J = 7.0 Hz, 8 H), 7.03 (d, J = 7.0
3
Hz, 8 H), 5.63 (t, J = 6.8 Hz, 4 H), 3.68 (s, 8 H), 3.35 (d, J = 6.8 Hz, 8 H).
1
3
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C NMR (50 MHz, CDCl ):  = 206.4, 139.5, 131.8, 130.6, 129.7 (8 C),
3
1
29.1 (8 C), 48.7, 38.6; a small amount of contaminants was found in
1
3
the C NMR spectrum.
Supporting Information
HRMS-ESI: m/z [M + H]+ calcd for C38H36O Na: 547.2613; found:
2
547.2629.
Supporting information for this article is available online at
The compound crystallized (Et O) to give single crystals, whose struc-
https://doi.org/10.1055/a-1479-6611. Su
p
p
orti
n
g Inform atio
n
Su
p
p
orting Inform atio
n
2
ture was solved by X-ray analysis.
References
Paracyclophane 2
To a mixture of diketone 3 (58 mg, 0.109 mmol), KOH (15 mg, 0.27
mmol), and benzil (7; 57 mg, 0.271 mmol) under argon, was added
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h. The mixture was cooled to 25 °C and concentrated on a rotary
evaporator to remove EtOH. The residue was subjected to column
chromatography (silica gel, gradient hexane/CH Cl ) to afford com-
(
1) Lehn, J.-M. In Supramolecular Chemistry, Concepts and Perspec-
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1
H NMR (200 MHz, CDCl ):  = 7.25–6.83 (m, 36 H, Ar-H), 5.64 (t, J =
3
6.6 Hz, 4 H), 3.27 (d, J = 6.6 Hz, 8 H).
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(5) Kitagaki, S.; Shimo, E.; Takeda, S.; Fukai, R.; Kojima, N.;
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3
1
30.4, 129.5, 128.4, 128.2, 128.1, 125.1, 38.0.
HRMS-ESI: m/z [M + NH ]+ calcd for C66H48O2 + NH +: 890.3998;
4
4
(
(
(
6) Povie, G.; Segawa, Y.; Nishihara, T.; Miyauchi, Y.; Itami, K.
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2
found: 895.3580.
2
,24-Diene-12,13,15,16,34,35,37,38-octaphenyl[4.4]triphenylpara-
cyclophane (1)
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2
heated under reflux at 260 °C over a sand bath for 20 h. The purple
©
2021. Thieme. All rights reserved. Synthesis 2021, 53, A–F

F
Synthesis
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(
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(
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©
2021. Thieme. All rights reserved. Synthesis 2021, 53, A–F