Synthesis of a Cyclophane Bearing Two Benz[a]anthracene Units Connected at the 5 and 7 Positions with Two Naphth-1,4-diyl Groups

Article abstract of DOI:10.1021/acs.joc.7b03081

A synthetic pathway to a cyclophane bearing two benz[a]anthracene units connected at the 5 and 7 positions through two naphth-1,4-diyl groups was developed, and its structure was confirmed by X-ray structure analysis. Because of structural constraints, the two naphthyl groups are distorted from planarity and the bonds connecting them to the benz[a]anthracene units are bent significantly. The UV-vis and fluorescence spectra of the cyclophane are red-shifted from those of 7-(1-naphthalenyl)benz[a]anthracene, which is the corresponding monomeric polycyclic aromatic hydrocarbon.

Full text of DOI:10.1021/acs.joc.7b03081

Subscriber access provided by READING UNIV
Note
Synthesis of a Cyclophane Bearing Two Benz[a]anthracene Units
Connected at 5 and 7 Positions with Two Naphth-1,4-diyl Groups
Haresh Thakellapalli, Behzad Farajidizaji, Shuangjiang Li, Josef C. Heller, Yu Zhang,
Novruz G Akhmedov, Carsten Milsmann, Jeffrey L. Petersen, and Kung K. Wang
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.7b03081 • Publication Date (Web): 29 Jan 2018
Downloaded from http://pubs.acs.org on January 29, 2018
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a free service to the research community to expedite the
dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts
appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been
fully peer reviewed, but should not be considered the official version of record. They are accessible to all
readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered
to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published
in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just
Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor
changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers
and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors
or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
The Journal of Organic Chemistry is published by the American Chemical Society.
1155 Sixteenth Street N.W., Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 5
The Journal of Organic Chemistry
1
2
3
4
5
6
7
8
9
Synthesis of a Cyclophane Bearing Two Benz[a]anthracene
Units Connected at 5 and 7 Positions with Two Naphth-1,4-
diyl Groups
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Haresh Thakellapalli, Behzad Farajidizaji, Shuangjiang Li, Josef C. Heller, Yu Zhang, Novruz G.
Akhmedov, Carsten Milsmann, Jeffrey L. Petersen, and Kung K. Wang*
C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, 26506-6045, United
States
Supporting Information Placeholder
ABSTRACT: A synthetic pathway to a cyclophane bearing two benz[a]anthracene units connected at 5 and 7 positions through two
naphth-1,4-diyl groups was developed and its structure was confirmed by X-ray structure analysis. Because of structural constraints,
the two naphthyl groups are distorted from planarity and the bonds connecting them to the benz[a]anthracene units are bent signifi-
cantly. The UV‒vis and fluorescence spectra of the cyclophane are red-shifted from 7-(1-naphthalenyl)benz[a]anthracene, which is
the corresponding monomeric polycyclic aromatic hydrocarbon.
Cyclophanes as bridged aromatic compounds have continued
to attract considerable attention due in part to their unusual
structural features, ability to form host-guest complexes, and in-
teresting material properties.1 Development of synthetic meth-
ods for strained cyclophanes faces the challenge of overcoming
the developing strain energy along the synthetic pathways. Sev-
eral synthetic strategies have been reported for cyclophanes, in-
cluding systems containing unusually strained structures.2 Dur-
ing our investigation of new synthetic pathways for cyclopara-
phenylenes,3 a serendipitous discovery led to the formation of a
strained cyclophane bearing two benz[a]anthracene units con-
nected at 5 and 7 positions through two naphth-1,4-diyl groups
Scheme 1. Synthesis of Dibromide 4
The synthetic sequence began with the Sonogashira reactions
between 1-bromo-4-iodonaphthalene (1) and 1,7-octadiyne to
give diyne 2 in 86% isolated yield (Scheme 1). Treatment of 2
with zirconocene, generated in situ from Cp2ZrCl2 and two
equiv of BuLi, followed by hydrolysis with aqueous HCl pro-
duced 1,3-butadiene 3.4 Upon being exposed to a catalytic
amount of BF3.OEt2 (18 mol %) at 150 °C for 24 h, diene 3 was
transformed to the rearranged isomer 4 in 83% isolated yield.
The DFT-optimized structure of 4 is shown in Figure 1. The
temperature-dependent 1H NMR studies indicate that the rate of
rotation around the bond attaching the 4-bromo-1-naphthyl
group to the hydrogenated benz[a]anthracene unit is relatively
slow on the NMR time scale at room temperature.
Figure 1. DFT-optimized structure of 4 with carbons (gray), hy-
drogens (white), and bromines (blue).
ACS Paragon Plus Environment

The Journal of Organic Chemistry
The formation of 4 was rather unexpected. Originally we were
Page 2 of 5
The Ni(cod)2-mediated (cod being 1,5-cyclooctadiene) homo-
coupling reactions of 4 in the presence of 2,2'-bipyridyl (bpy)6
most likely produced 11, which was not isolated and character-
ized (Scheme 4). Oxidative aromatization of 11 with DDQ3 at
150 °C for 4 h then produced cyclophane 12 in 5% yield over
two steps from 4.
1
2
3
4
5
6
7
8
attempting to promote the Diels‒Alder reaction between 3 and
dimethyl acetylenedicarboxylate in the presence of a catalytic
amount of BF3.OEt2 for the preparation of a Diels‒Alder adduct
as a precursor leading to cycloparaphenylenes,3b,e but instead 4
was produced. A plausible reaction pathway from 3 to 4 could
involve an initial nonconcerted 1,3-hydrogen shift to form 5
(Scheme 2). Compound 5 was found to be essentially the only
initial product after heating at 150 °C for 2 h, and it was isolated
for structural elucidation by NMR and HRMS spectroscopy.
Heating the isolated 5 in the presence of a catalytic amount of
BF3.OEt2 at 150 °C for 24 h also gave 4. It was also observed
that heating 3 in the presence of a catalytic amount of acetic
acid at 150 °C for 24 h also gave 4 in 92% isolated yield. A
nonconcerted 1,3-hydrogen shift of 5 could produce 6 with one
of the double bonds of the diene moiety having the Z geometry.
A subsequent disrotatory electrocyclic reaction of 6, which was
not isolated and detected, to form 7 followed by a nonconcerted
1,3-hydrogen shift could then produce 4.
Scheme 4. Synthesis of Cyclophane 12
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Scheme 2. Plausible Reaction Mechanism for the Formation
of 4
The structure of 12 bearing two benz[a]anthracene units con-
nected at 5 and 7 positions through two naphth-1,4-diyl groups
was confirmed by X-ray structure analysis (Figure 2). The two
naphthyl groups are essentially parallel to each other but per-
pendicular to the benz[a]anthracene units. They point in oppo-
site directions and are distorted from planarity. The bonds con-
necting them to the C5 and C7 carbons of the benz[a]anthracene
units are bent toward each other with bond angles of 114.5° and
1
115.1°, respectively, as indicated. The H NMR signal of the
hydrogens attached to C6 occurred at δ 4.87, which was shifted
significantly upfield by the magnetic ring currents of the naph-
thyl groups.
The connectivity of the carbon skeleton in 4 was further sup-
ported by the isolation of the aromatized product 8 when an ex-
cess of BF3.OEt2 was used (Scheme 3). Oxidative aromatization
of 8 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)
produced 9 with its structure established by X-ray structure
analysis. Treatment of 9 with BuLi for lithium‒halogen ex-
change followed by protonation then gave 7-(1-naphtha-
lenyl)benz[a]anthracene (10), which was prepared previously
by an independent synthetic route.5
114.5°
115.1°
Figure 2. ORTEP drawing of cyclophane 12. The molecule lies on
a crystallographic center of inversion. The thermal ellipsoids are
scaled to enclose 50% probability.
Scheme 3. Synthesis of Hydrocarbon 10
We also investigated the optical and electrochemical properties
of cyclophane 12 and compared them with those of 10. The
UV‒vis and fluorescence spectra were recorded in degassed di-
chloromethane as the solvent. Cyclophane 12 showed absorp-
tion maxima at 290 and 300 nm and absorption bands between
320 and 410 nm (Figure 3). They were red-shifted from those
of 10, which showed absorption maxima at 283 and 294 nm and
absorption bands between 310 and 395 nm. The fluorescence
maxima also showed red-shift from 396 and 417 nm in 10 to
402 and 429 nm in cyclophane 12.
ACS Paragon Plus Environment

Page 3 of 5
The Journal of Organic Chemistry
mmol), and CuI (0.213 g, 1.12 mmol) in 200 mL of triethyla-
1
2
3
4
5
6
7
8
mine was added 1,7-octadiyne (0.970 g, 9.15 mmol), and the
mixture was stirred at 70 °C for 8 h. After the solution was
cooled to rt, triethylamine was removed in vacuo, and then
CH2Cl2 (400 mL) and water (200 mL) were added. The result-
ing mixture was extracted with CH2Cl2 (2 × 100 mL), and the
combined organic layers were washed with water and brine,
dried over Na2SO4, and concentrated in vacuo to yield a pale-
yellow solid. The pale yellow solid was purified by silica gel
column chromatography using ethyl acetate/hexanes (1:9) as el-
uent to obtain 2 (4.05 g, 7.84 mmol, 86% yield) as a pale yellow
9
1
solid: IR 1381, 834, 762 cm‒1; H NMR (CDCl3, 400 MHz) δ
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
8.36 (2 H, dd, J = 8.0, 1.6 Hz), 8.24 (2 H, dd, J = 8.0, 2.0 Hz),
7.70 (2 H, d, J = 7.8 Hz), 7.63–7.53 (4 H, m), 7.46 (2 H, d, J =
7.8 Hz), 2.68 (4 H, m), 1.98 (4 H, m); 13C NMR (CDCl3, 100
MHz) δ 134.5, 131.7, 130.1, 129.4, 127.6, 127.4, 127.3, 126.8,
122.7, 121.7, 95.9, 78.5, 28.0, 19.4; HRMS (ESI/FT-ICR) m/z
[M + H]+ calcd for C28H21Br2 515.0005, 516.9984, 518.9964;
found 515.0010, 516.9989, 518.9969.
Figure 3. UV‒vis (solid lines) and fluorescence (dashed lines)
spectra of 10 (red) and 12 (black) in dichloromethane.
Electrochemical properties of 10 and cyclophane 12 were in-
vestigated by cyclic voltammetry in tetrahydrofuran with 0.1 M
[N(n-Bu)4][PF6] and referenced to ferrocene/ferrocenium
(Fc/Fc+) couple as an internal standard. Compound 10 showed
a reversible reduction with E1/2 = −2.59 V and three irreversible
oxidation events at Epa = 0.63, 1.14, and 1.41 V. A similar redox
behavior was also observed for cyclophane 12 with an irreversi-
ble redox couple at Epa = −2.42 V and Epc = −2.73 V. Again, no
reversible oxidation events were observed for 12.
Preparation of 3. To a solution of Cp2ZrCl2 (2.68 g, 9.17
mmol) in THF (70 mL) at −78 °C under an argon atmosphere
was added n-butyllithium (7.0 mL of a 2.5 M solution in hex-
anes, 17.5 mmol). After 1 h at −78 °C, 2 (3.75 g, 7.26 mmol) in
30 mL of THF under argon was added slowly via cannula. The
reaction mixture was then warmed to rt. After 12 h, the reaction
mixture was poured into 300 mL of a 3 M aqueous HCl solution.
After 30 min of stirring, the reaction mixture was extracted with
dichloromethane (2 × 100 mL). The combined organic layers
were washed with a saturated Na2CO3 solution and dried over
MgSO4. After passing through a silica gel column (9.0 cm high,
2.5 cm in diameter), the solvent was evaporated in vacuo, and
the residue was washed with cold ethanol to give 3 (3.60 g, 6.98
mmol, 96% yield) as a white solid: IR 1503, 1377, 760 cm–1; 1H
NMR (CDCl3, 400 MHz) δ 8.30 (2 H, dd, J = 7.8, 1.6 Hz), 8.14
(2 H, dd, J = 7.4, 1.6 Hz), 7.80 (2 H, d, J = 7.4 Hz), 7.66–7.57
(4 H, m), 7.26 (2 H, d, J = 7 Hz), 7.07 (2 H, s), 2.45 (4 H, m),
1.63 (4 H, m); 13C NMR (CDCl3, 100 MHz) δ 146.5, 135.1,
133.6, 132.0, 129.4, 127.6, 127.3, 127.2, 126.6, 125.7, 121.8,
120.9, 30.8, 26.7; HRMS (ESI/Orbitrap) m/z [M]+ calcd for
C28H22Br2 516.0083, 518.0062, 520.0042; found 516.0091,
518.0068, 520.0040.
In summary, a synthetic pathway to cyclophane 12 has been
developed. Isomerization of 1,3-butadiene 3 to the hydrogen-
ated benz[a]anthracene 4 followed by the Ni(cod)2-mediated
macrocyclization and oxidative aromatization with DDQ are
the key steps of the synthetic pathway. The structure of 12 was
established by X-ray structure analysis. Because of structural
constraints, the two naphthyl groups are distorted from planar-
ity and the bonds connecting them to the benz[a]anthracene
1
units are bent significantly. The H NMR signal of the hydro-
gens on the C6 carbons of the benz[a]anthracene units is shifted
significantly upfield to δ 4.87. The UV‒vis and fluorescence
spectra of 10 and 12 were recorded, and their electrochemical
properties in THF were probed by cyclic voltammetry.
EXPERIMENTAL SECTION
General Experimental Methods.
All reactions were conducted in oven-dried (120 °C) glass-
ware under a nitrogen atmosphere unless otherwise indicated.
Chemicals, including 1,4-dibromonaphthalene, 1,7-octadiyne,
tetrakis(triphenylphosphine)palladium [Pd(PPh3)4], Cp2ZrCl2,
BF3.OEt2, bis(1,5-cyclooctadiene)nickel [Ni(cod)2], 2,2′-bi-
pyridyl (bpy), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
(DDQ), were purchased from chemical suppliers and were used
as received. Treatment of 1,4-dibromonaphthalene in THF with
butyllithium at −78 °C followed by iodine produced 1-bromo-
4-iodonaphthalene (1).7 UV–vis absorption spectra were rec-
orded on a spectrophotometer with a 1 nm resolution, and the
baseline was corrected with a solvent filled square quartz cell.
Fluorescence spectra were recorded on a spectrofluorophotom-
eter with a 2 nm resolution. Infrared (IR) spectra of solid sam-
ples were recorded on a Fourier transform infrared system
equipped with a diamond crystal attenuated total reflectance
sampling interface. HRMS spectra were obtained on an FT-ICR
or an Orbitrap mass analyzer coupled with electrospray ioniza-
tion (ESI).
Preparation of 4. To a 25 mL pressure vessel were added 3
(0.700 g, 1.35 mmol), BF3·OEt2 (0.03 mL, 0.2 mmol) and 1 mL
of dry toluene under an argon atmosphere. The reaction mixture
was stirred at 150 °C for 24 h before it was cooled to rt. Toluene
was evaporated in vacuo, and the residue was purified by flash
column chromatography (silica gel/ethyl acetate:hexanes =
5:95) to afford 4 (0.585 g, 1.13 mmol, 83% yield) as a white
solid: IR 1595, 1378, 750 cm–1; 1H NMR (600 MHz, CDCl3, 25
°C) δ 8.31 (1 H, d, J = 8.2 Hz), 8.17 (1 H, d, J = 8.2 Hz), 8.09
(1 H, d, J = 8.8 Hz), 7.71–7.66 (1 H, br), 7.63–7.55 (4 H, m),
7.28 (1 H, s), 7.15 (1 H, br), 5.22 (1 H, br), 3.86 (1 H, d, J =
22.6 Hz), 3.78 (1 H, d, J = 21.7 Hz), 2.26 (2 H, m), 1.90 (1 H,
1
m), 1.74 (1 H, m), 1.62–1.48 (4 H, m); H NMR (600 MHz,
CDCl3, 60 °C) δ 8.32 (1 H, d, J = 8.6 Hz), 8.31–8.23 (1 H, br),
8.18 (1 H, d, J = 8.2 Hz), 8.09 (1 H, d, J = 8.2 Hz), 7.69 (1 H,
d, J = 7.8 Hz), 7.61 (1 H, t, J = 7.6 Hz), 7.57 (1 H, t, J = 7.9
Hz), 7.56 (1 H, t, J = 7.5 Hz), 7.53–7.46 (1 H, br), 7.31 (1 H, s),
7.16 (1 H, d, J = 7.6 Hz), 5.25 (1 H, s), 3.88 (1 H, d, J = 21.2
Hz), 3.79 (1 H, d, J = 21.5 Hz), 2.29 (2 H, m), 1.93 (1 H, m),
1.76 (1 H, m), 1.62–1.50 (3 H, m), 1.43 (1 H, br); 13C NMR
(CDCl3, 150 MHz, 25 °C) δ 132.7, 130.6, 130.5, 129.9, 129.87,
128.1, 128.0, 127.7, 126.9, 126.5, 125.6, 124.1, 123.6, 121.2,
Preparation of 2. To a degassed solution of 1-bromo-4-
iodonaphthalene (1, 6.20 g, 18.6 mmol), Pd(PPh3)4 (1.30 g, 1.12
ACS Paragon Plus Environment

The Journal of Organic Chemistry
32.6, 30.3, 28.1, 23.1, 22.7; 13C NMR (CDCl3, 150 MHz, –40
°C) δ 142.8, 142.6, 138.6, 136.6, 135.2, 133.3, 132.3, 132.2,
132.1, 131.3, 130.6, 130.2, 130.1, 129.93, 129.88, 129.3, 129.0,
128.0, 127.9, 127.6, 127.4, 127.2, 127.0, 126.8, 126.7, 126.4,
126.3, 52.1, 43.6, 32.3, 32.2, 31.6, 29.96, 29.89, 28.1, 27.6,
22.8, 22.7, 22.5; HRMS (ESI/Orbitrap) m/z [M]+ calcd for
C28H22Br2 516.0083, 518.0062, 520.0042; found 516.0097,
518.0087, 520.0030.
Page 4 of 5
fied by flash column chromatography (silica gel/ethyl ace-
tate:hexanes = 1:9) to produce 9 (0.085 g, 0.17 mmol, 88%
yield) as a yellow solid: IR 1503, 1374, 743 cm–1; 1H NMR (400
MHz, CDCl3) δ 9.33 (1 H, s), 8.95 (1 H, d, J = 8.2 Hz), 8.44 (1
H, d, J = 8.7 Hz), 8.31 (1 H, d, J = 7.8 Hz), 8.20 (1 H, d, J = 8.2
Hz), 8.03 (1 H, d, J = 7.8 Hz), 7.79 (1 H, t, J = 7.8 Hz), 7.72 (1
H, t, J = 7.6 Hz), 7.64–7.54 (3 H, m), 7.39 (1 H, d, J = 7.8 Hz),
7.36–7.24 (3 H, m), 7.09 (1 H, d, J = 8.2 Hz); 13C NMR (CDCl3,
100 MHz) δ 135.9, 134.5, 133.8, 132.2, 131.7, 131.6, 131.4,
130.1, 129.7, 129.6, 129.4, 128.79, 128.76, 128.4, 128.0, 127.9,
127.62, 127.58, 127.3, 126.9, 126.58, 126.56, 126.1, 123.3,
123.1, 122.9, 122.5; HRMS (ESI/Orbitrap) m/z [M]+ calcd for
C28H16Br2 509.9613, 511.9593, 513.9572; found 509.9629,
511.9600, 513.9565.
1
2
3
4
5
6
7
8
Alternatively, compound 3 (0.100 g, 0.193 mmol) was taken
up in 2 mL of toluene and heated at 150 °C for 24 h in the pres-
ence of a catalytic amount of acetic acid (4 drops) to produce 4
(0.092 g, 0.18 mmol, 92% yield) as a white solid.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Isolation of 5. From the reaction mixture for the preparation of
4, an aliquot of 0.1 mL was removed within 2 h and concen-
trated in vacuo. The resulting product without further purifica-
tion was identified as 5: IR 1377, 1261, 755 cm–1; 1H NMR
(CDCl3, 600 MHz) δ 8.33 (1 H, dd, J = 8.8, 1.5 Hz), 8.22 (1 H,
d, J = 8.4 Hz), 8.09 (1 H, d, J = 8.2 Hz), 7.79 (1 H, d, J = 7.6
Hz), 7.73 (1 H, d, J = 7.6 Hz), 7.63–7.52 (4 H, m), 7.40 (1 H,
ddd, J = 8.2, 6.8, 1.2 Hz), 7.33 (1 H, d, J = 7.6 Hz), 7.16 (1 H,
dd, J = 7.6, 0.9 Hz), 6.76 (1 H, s), 5.68 (1 H, t, J = 4.2 Hz), 4.17
(2 H, s), 2.46 (2 H, m), 2.20 (2 H, m), 1.69 (2 H, quintet, J =
6.2 Hz); 13C NMR (CDCl3, 150 MHz) δ 139.0, 136.6, 135.3,
135.1, 133.6, 133.4, 132.0, 131.8, 129.6, 129.2, 127.9, 127.5,
127.09, 127.07, 127.0, 126.9, 126.8, 126.5, 125.6, 124.4, 121.4,
121.3, 120.5, 36.3, 27.8, 26.4, 23.0; HRMS (ESI/Orbitrap) m/z
[M]+ calcd for C28H22Br2 516.0083, 518.0062, 520.0042; found
516.0090, 518.0069, 520.0033.
Recrystallization of 9 from a mixture of chloroform and hex-
anes produced a single crystal suitable for X-ray structure anal-
ysis.
Preparation of 10.5 To a 25 mL flask containing 9 (0.070 g,
0.14 mmol) in THF (2 mL) at –78 °C was added butyllithium
(0.13 mL, 2.5 M in hexanes, 0.33 mmol). The reaction mixture
was stirred at –78 °C for 1 h and then treated with 0.5 mL of a
1.0 M aqueous HCl solution before it was warmed to rt. The
reaction mixture was extracted with ethyl acetate (2 × 25 mL).
The combined organic layers were washed with a saturated
aqueous Na2CO3 solution and dried over MgSO4. After passing
through a short silica gel column, the solvent was evaporated in
vacuo, and the residue was purified by flash column chroma-
tography (silica gel/ethyl acetate:hexanes = 5:9.5) to produce
10 (0.043 g, 0.12 mmol, 86% yield) as a pale yellow solid: IR
1734, 1505, 748 cm–1; 1H NMR (400 MHz, CDCl3) δ 9.36 (1 H,
s), 8.96 (1 H, d, J = 8.2 Hz), 8.22 (1 H, d, J = 8.4 Hz), 8.07 (1
H, d, J = 8.2 Hz), 8.01 (1 H, d, J = 8.3 Hz), 7.79 (1 H, dd, J =
7.6, 1.3 Hz), 7.75–7.68 (2 H, m), 7.62 (1 H, ddd, J = 8.2, 7.2,
1.2 Hz), 7.57–7.52 (2 H, m), 7.48 (1 H, ddd, J = 8.2, 6.7, 1.3
Hz), 7.43–7.38 (2 H, m), 7.32 (1 H, ddd, J = 8.7, 6.5, 1.2 Hz),
7.24–7.19 (2 H, m), 7.11 (1 H, d, J = 8.2 Hz); 13C NMR (CDCl3,
100 MHz) δ 136.6, 135.4, 133.7, 133.5, 131.60, 131.56, 131.54,
130.6, 129.6, 129.1, 128.63, 128.58, 128.55, 128.2, 128.1,
127.2, 127.1, 127.0, 126.7, 126.5, 126.3, 126.0, 125.9, 125.63,
125.58, 125.56, 123.1, 121.9; HRMS (ESI/FT-ICR) m/z [M]+
calcd for C28H18 354.1403; found 354.1413.
Compound 5 was taken up in dry toluene and heated in the
presence of a catalytic amount of BF3·OEt2 at 150 °C for 24 h
to produce 4.
Preparation of 8. To a 25 mL pressure vessel was added a so-
lution of 3 (2.44 g, 4.71 mmol) and BF3·OEt2 (1.0 mL, 8.1
mmol) in 2 mL of dry toluene under an argon atmosphere. The
reaction mixture was stirred at 150 °C for 24 h before it was
cooled to rt. Toluene was evaporated in vacuo, and the residue
was purified by flash column chromatography (silica gel/ethyl
acetate:hexanes = 5:95) to afford 8 (2.00 g, 3.87 mmol, 82%
1
yield) as a brown solid: IR 1727, 1444, 1252, 756 cm–1; H
NMR (600 MHz, CDCl3) δ 8.75 (1 H, dd, J = 8.6, 0.7 Hz), 8.53
(1 H, s), 8.39 (1 H, dd, J = 8.0, 1.9 Hz), 8.27 (1 H, dd, J = 7.4,
1.3 Hz), 7.95 (1 H, d, J = 7.5 Hz), 7.71 (1 H, ddd, J = 8.3, 7.0,
1.5 Hz), 7.66 (1 H, ddd, J = 8.2, 7.0, 1.3 Hz), 7.61 (1 H, ddd, J
= 8.1, 6.8, 1.2 Hz), 7.36 (1 H, s), 7.34 (1 H, ddd, J = 8.3, 6.7,
1.1 Hz), 7.23–7.20 (2 H, m), 3.16 (2 H, t, J = 6.5 Hz), 2.48 (1
H, dt, J = 17.3, 6.5 Hz), 2.21 (1 H, dt, J = 17.3, 6.2 Hz), 1.87 (2
H, quintet, J = 6.2 Hz), 1.76–1.64 (2 H, m); 13C NMR (CDCl3,
150 MHz) δ 137.1, 137.0, 136.3, 135.5, 133.7, 132.3, 131.0,
129.99, 129.93, 129.90, 128.3, 128.2, 128.0, 127.9, 127.7,
127.5, 127.3, 127.23, 127.22, 126.2, 122.8, 122.7, 121.2, 30.9,
28.0, 23.2, 22.9; HRMS (ESI/FT-ICR) m/z [M]+ calcd for
C28H20Br2 513.9926, 515.9906, 517.9885; found 513.9934,
515.9914, 517.9891.
Preparation of 12. A 500 mL flask containing 4 (0.575 g, 1.11
mmol) and 2,2′-bipyridyl (0.423 g, 2.71 mmol) was flushed
with nitrogen. The flask was then placed in a glovebox before
Ni(cod)2 (0.739 g, 2.69 mmol) was added. The flask was fitted
with a condenser and a rubber septum and then removed from
the glovebox. THF (110 mL) was introduced via cannula, and
the reaction mixture was heated at reflux for 24 h before it was
cooled to rt. The reaction mixture was passed through a silica
gel column (10 cm high, 1.5 cm in diameter), and the column
was further eluted with ethyl acetate (150 mL) and dichloro-
methane (150 mL). The combined eluates were concentrated,
and the residue was used in the next step without further purifi-
cation. To the flask containing the residue was added DDQ
(0.500 g, 2.20 mmol). The flask was flushed with nitrogen, and
chlorobenzene (3 mL) was added by using a syringe. The reac-
tion mixture was heated at 130 °C for 4 h before it was cooled
to rt. Dichloromethane (100 mL) was added, and the solution
was immediately passed through a basic alumina column (7.0
cm high, 2.5 cm in diameter), and the column was further eluted
with dichloromethane (100 mL). The combined eluates were
concentrated, and the residue was purified by flash column
Preparation of 9. To a 25 mL flask containing 8 (0.100 g,
0.194 mmol) in chlorobenzene (2 mL) was added DDQ (0.265
g, 1.17 mmol). The reaction mixture was heated at 150 °C for 4
h before it was cooled to rt. Dichloromethane (100 mL) was
added, and the solution was immediately passed through a basic
alumina column (7.0 cm high, 2.5 cm in diameter), and the col-
umn was further eluted with 100 mL of dichloromethane. The
combined eluates were concentrated, and the residue was puri-
ACS Paragon Plus Environment

Page 5 of 5
The Journal of Organic Chemistry
chromatography (silica gel/ethyl acetate:hexanes = 1:9) to pro- the acquisition of a Bruker AXS D8 Venture X-ray diffractom-
1
2
3
4
5
6
7
8
duce 12 (0.020 g, 0.028 mmol, 5% yield) as a white solid: mp
>230 °C; IR 1725, 1459, 1263, 762 cm–1; 1H NMR (600 MHz,
CDCl3) δ 9.38 (2 H, s), 9.08 (2 H, dd, J = 8.3, 1.0 Hz), 8.42 (2
H, dd, J = 8.5, 1.3 Hz), 8.34 (2 H, dd, J = 8.4, 1.3 Hz), 8.21 (2
H, dd, J = 7.8, 1.3 Hz), 7.82 (2 H, ddd, J = 8.3, 7.0, 1.3 Hz),
7.72 (2 H, ddd, J = 7.8, 7.0, 1.0 Hz), 7.70 (2 H, ddd, J = 8.4,
6.6, 1.3 Hz), 7.66 (2 H, ddd, J = 8.5, 6.6, 1.3 Hz), 7.42 (2 H, dd,
J = 8.6, 1.3 Hz), 7.31 (2 H, d, J = 7.2 Hz), 7.27 (2 H, dd, J =
8.3, 1.4 Hz), 7.15 (2 H, ddd, J = 8.3, 6.8, 1.4 Hz), 7.14 (2 H, d,
J = 7.2 Hz), 7.10 (2 H, ddd, J = 8.3, 6.8, 1.3 Hz), 4.87 (2 H, s);
13C NMR (CDCl3, 150 MHz) δ 140.9, 138.1, 137.3, 136.3,
135.44, 135.39, 131.7, 131.3, 130.7, 130.5, 130.4, 130.3, 129.7,
129.1, 128.8, 127.74, 127.69, 127.3, 127.1, 126.9, 126.50,
126.45, 126.1, 125.90, 125.83, 125.81, 123.6, 121.7; HRMS
(ESI/FT-ICR) m/z [M]+ calcd for C56H32 704.2499; found
704.2504.
eter.
REFERENCES
(1) (a) Ghasemabadi, P. G.; Yao, T.; Bodwell, G. J. Chem. Soc. Rev.
2015, 44, 6494-6518. (b) Barnes, J. C.; Juríček, M.; Strutt, N.
L.; Frasconi, M.; Sampath, S.; Giesener, M. A.; McGrier, P.
L.; Bruns, C. J.; Stern, C. L.; Sarjeant, A. A.; Stoddart, J. F.
J. Am. Chem. Soc. 2013, 135, 183-192. (c) Juríček, M.;
Barnes, J. C.; Dale, E. J.; Liu, W.-G.; Strutt, N. L.; Bruns, C.
J.; Vermeulen, N. A.; Ghooray, K. C.; Sarjeant, A. A.; Stern,
C. L.; Botros, Y. Y.; Goddard, W. A., III; Stoddart, J. F. J.
Am. Chem. Soc. 2013, 135, 12736-12746. (d) Bruns, C. J.;
Frasconi, M.; Iehl, J.; Hartlieb, K. J.; Schneebeli, S. T.;
Cheng, C.; Stupp, S. I.; Stoddart, J. F. J. Am. Chem. Soc.
2014, 136, 4714-4723. (e) Reiser, O.; König, B.; Meerholz,
K.; Heinze, J.; Wellauer, T.; Gerson, F.; Frim, R.; Rab-
inovitz, M.; de Meijere, A. J. Am. Chem. Soc. 1993, 115,
3511-3518. (f) Darzi, E. R.; Jasti, R. Chem. Soc. Rev. 2015, 44,
6401-6410. (g) Segawa, Y.; Yagi, A.; Matsui, K.; Itami, K. An-
gew. Chem., Int. Ed. 2016, 55, 5136-5158.
(2) (a) Bodwell, G. J.; Nandaluru, P. R. Isr. J. Chem. 2012, 52, 105-
138. (b) Kotha, S.; Shirbhate, M. E.; Waghule, G. T. Beilstein J.
Org. Chem. 2015, 11, 1274-1331. (c) Chen, H.-B.; Yin, J.;
Wang, Y.; Pei, J. Org. Lett. 2008, 10, 3113-3116. (d) Iyoda, M.;
Kondo, T.; Nakao, K.; Hara, K.; Kuwatani, Y.; Yoshida, M.;
Matsuyama, H. Org. Lett. 2000, 2, 2081-2083.
(3) (a) Huang, C.; Huang, Y.; Akhmedov, N. G.; Popp, B. V.; Pe-
tersen, J. L.; Wang, K. K. Org. Lett. 2014, 16, 2672-2675. (b)
Li, S.; Huang, C.; Thakellapalli, H.; Farajidizaji, B.; Popp, B. V.;
Petersen, J. L.; Wang, K. K. Org. Lett. 2016, 18, 2268-2271. (c)
Huang, C.; Li, S.; Thakellapalli, H.; Farajidizaji, B.; Huang, Y.;
Akhmedov, N. G.; Popp, B. V.; Petersen, J. L.; Wang, K. K. J.
Org. Chem. 2017, 82, 1166-1174. (d) Farajidizaji, B.; Huang, C.;
Thakellapalli, H.; Li, S.; Akhmedov, N. G.; Popp, B. V.; Pe-
tersen, J. L.; Wang, K. K. J. Org. Chem. 2017, 82, 4458-4464.
(e) Thakellapalli, H.; Li, S.; Farajidizaji, B.; Baughman, N. N.;
Akhmedov, N. G.; Popp, B. V.; Wang, K. K. Org. Lett. 2017,
19, 2674-2677.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Recrystallization of 12 from a mixture of chloroform and hex-
anes produced a single crystal suitable for X-ray structure anal-
ysis.
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the ACS
Publications website at DOI:
Tables listing crystal data and structure refinement for 9 and 12;
UV‒visible and fluorescence spectra of 10 and 12; cyclic voltam-
mograms of 10 and 12; 1H and 13C NMR spectra of all new com-
pounds (PDF)
X-ray crystallographic file for 9 (CIF)
X-ray crystallographic file for 12 (CIF)
AUTHOR INFORMATION
Corresponding Author
*E-mail: kung.wang@mail.wvu.edu
(4) (a) Takahashi, T.; Tsai, F.-Y.; Li, Y. Chem. Lett. 1999, 1173-
1174. (b) Jiang, B.; Tilley, T. D. J. Am. Chem. Soc. 1999, 121,
9744-9745. (c) Morisaki, Y.; Aiki, Y.; Chujo, Y. Macromole-
cules 2003, 36, 2594-2597.
(5) Li, G.; Zhou, S.; Su, G.; Liu, Y.; Wang, P. G. J. Org. Chem.
2007, 72, 9830-9833.
(6) (a) Segawa, Y.; Miyamoto, S.; Omachi, H.; Matsuura, S.; Šenel,
P.; Sasamori, T.; Tokitoh, N.; Itami, K. Angew. Chem., Int. Ed.
2011, 50, 3244-3248. (b) Segawa, Y.; Šenel, P.; Matsuura, S.;
Omachi, H.; Itami, K. Chem. Lett. 2011, 40, 423-425.
(7) Nesterov, E. E.; Zhu, Z.; Swager, T. M. J. Am. Chem. Soc. 2005,
127, 10083-10088.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
This material is based upon work supported by the National Sci-
ence Foundation under CHE – 1464026. The NMR spectrome-
ter on which this work was carried out was supported by the
Major Research Instrumentation (MRI) Program of the NSF
(CHE – 1228336). J.L.P. acknowledges the financial support
provided by the MRI Program of the NSF (CHE – 1336071) for
ACS Paragon Plus Environment