A Superior Synthesis of Longitudinally Twisted Acenes

Article abstract of DOI:10.1002/chem.201704501

Seven longitudinally twisted acenes (an anthracene, two tetracenes, three pentacenes, and a hexacene) have been synthesized by the addition of aryllithium reagents to the appropriate quinone precursors, followed by SnCl₂-mediated reduction of their diol intermediates, and several of these acenes have been crystallographically characterized. The new syntheses of the three previously reported twisted acenes, decaphenylanthracene (1), 9,10,11,20,21,22-hexaphenyltetrabenzo[a,c,l,n]pentacene (2), and 9,10,11,12,13,14,15,16-octaphenyldibenzo[a,c]tetracene (14), resulted in a reduction of the number of synthetic steps. As a consequence their overall yields were increased by factors of 50-, 24-, and 66-fold, respectively. All of the twisted acene syntheses reported here are suitable for the synthesis of at least gram quantities of these remarkable hydrocarbon materials.

Full text of DOI:10.1002/chem.201704501

A Journal of
Accepted Article
Title: A Superior Synthesis of Longitudinally Twisted Acenes
Authors: Robert G. Clevenger, Bharat Kumar, Elizabeth M. Menuey,
Gene-Hsiang Lee, Dustin Patterson, and Kathleen Victoria
Kilway
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10.1002/chem.201704501
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A Superior Synthesis of Longitudinally Twisted Acenes
Robert G. Clevenger,[a] Bharat Kumar,[b] Elizabeth M. Menuey,[a] Gene-Hsiang Lee,[c] Dustin
Patterson,[b] and Kathleen V. Kilway*[a]
Abstract: Seven longitudinally twisted acenes—an anthracene, two
tetracenes, three pentacenes, and hexacene—have been
conditions necessary to generate the aryne. Typically, this
requires long syntheses resulting in low overall yields. For
instance, anthracene 1 has a convergent eight-step synthesis
a
synthesized by the addition of aryllithium reagents to the appropriate
quinone precursors, followed by SnCl2-mediated reduction of their
diol intermediates, and several of these acenes have been
crystallographically characterized. The new syntheses of the three
previously reported twisted acenes, decaphenylanthracene (1),
9,10,11,20,21,22-hexaphenyltetrabenzo[a,c,l,n]pentacene (2), and
from commercially available tetracyclone (3) and gave
a
reported overall yield of 0.1%.[6]
9,10,11,12,13,14,15,16-octaphenyldibenzo[a,c]tetracene
(14),
resulted in a reduction of the number of synthetic steps and an
improvement of their overall yields were increased by factors of 50-,
24-, and 66-fold, respectively. All of the twisted acene syntheses
reported here are suitable for the synthesis of at least gram
quantities of these remarkable hydrocarbon.characters.
However, a classical method for the syntheses of substituted
polycyclic aromatic hydrocarbons (PAHs) is by what we will call
the “quinone” approach: the addition of an organometallic
reagent to a suitable quinone precursor, followed by the
reduction of its diol intermediate. Interestingly, it has been
applied to the syntheses of several sterically congested
Introduction
Longitudinally twisted acenes (LTAs) have long been of interest
due in part to the remarkable helical shapes many of them have
exhibited in their X-ray crystal structures and to their generally
pleasing aesthetics.[1] Besides their remarkable twists, several
LTAs have exhibited theoretically interesting and potentially
useful physical properties.[2–5] Of particular note are
decaphenylanthracene[6] (1), the longest perphenylacene yet
described, with an end-to-end twist of 63°, and
9,10,11,20,21,22-hexaphenyltetrabenzo[a,c,l,n]pentacene[7,8] (2),
arguably the most impressive LTA synthesized to date, with the
exceptional end-to-end twist of 144º, the largest yet known.
anthracenes.[16–19] Intrigued, we added phenyllithium to
a
refluxing suspension of octaphenylanthraquinone[20] (4) in dry
benzene. The diol intermediate, which was isolated from the
reaction mixture but not purified, was treated with SnCl2 and HCl
in refluxing THF to form 1 in 52% yield, a 50-fold improvement
over its original synthesis (Scheme 1). As it turns out, this
“quinone” approach proves not only to be a superior alternative
to the synthesis of compound 1, but for compound 2 as well, and
as a facile means of obtaining several LTAs in general, all of
which is presented here in the following paragraphs.
Anthracene
1 was found to display exceptionally stable
electrogenerated chemiluminescence (ECL),[9] and pentacene 2
was resolved into its pure enantiomers, which possessed
extremely large specific rotations of [α]D = ±7400°.
The synthetic methodology used to produce compounds 1 and 2,
and which is predominantly used to synthesize sterically
congested acenes in general,[1,10–15] is by what we will refer to as
the “benzyne” approach: the design of a benzyne precursor and
its subsequent trapping by a diene compatible with the reaction
[a]
Dr. R. G. Clevenger, E. M. Menuey, Prof. K. V. Kilway
Department of Chemistry
University of Missouri – Kansas City
5100 Rockhill Road, Kansas City, MO 64110-2499
E-mail: kilwayk@umkc.edu
Scheme 1. Conditions: i. phenyllithium, benzene, rt 17 h; ii. anhyd. SnCl2, HCl,
THF, reflux 1 h, 52% (steps i and ii).
[b]
[c]
Dr. B. Kumar, D. Patterson
Department of Chemistry
University of Nevada, Reno
1664 North Virginia Street, Reno, NV 89557
Dr. G.-H. Lee
Results and Discussion
Instrumentation Center
National Taiwan University, No 1 Sec. 4, Roosevelt Rd. Da`am Dist.
Taipei City, 10617 Taiwan (R.O.C)
A convenient quinone precursor for pentacene 2 is 9,11,20,22-
(5),
which is known and typically prepared by the double addition of
tetraphenyltetrabenzo[a,c,l,n]pentacene-10,21-dione[21,22]
Supporting information for this article is given via a link at the end of the
document.
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phencyclone[23–25] (6) to one-half equivalent of p-benzoquinone.
But as illustrated in Scheme 2, it may also be prepared by the
steric congestion as its phenanthrene equivalent, the C6A–C5A–
C21–C20 torsion angle measures at 134.6°, almost 10° less
than that reported for compound 2, and less than the AM1-
predicted 141°. Crystal structures of previously reported LTAs
typically show that the overall twist of the acene is distributed
somewhat evenly among the individual benzene rings,[1] and the
individual rings of compound 10 showed a similarly even
distribution. The twists of five rings measured (from left-to-right)
20°, 30°, 29°, 30°, and 21°, respectively, with the exception
being the terminal ring on the pyrene subunit, which possessed
a nominal 4° twist. Average distance between ipso carbons and
benzo hydrogens [e.g., C22–H1] is 2.33 Å, while the average
distance between ipso carbons [e.g., C28–C34] is 2.94 Å. These
intramolecular non-bonded contacts are virtually identical to
those observed in pentacene 2.
condensation
of
the
previously
reported
9,14-
diphenylbenzo[f]tetraphene-10,13-dione[26] (7) with 6 in 36%
yield. Although this route is less efficient than that described
above—quinone 5 was previously prepared in 69% yield—
compound 7 is a useful precursor from which to build other
polycyclic quinones. For instance, heating
7
with
pyrenecyclone[27] (8) in nitrobenzene gave 9,11,20,22-
tetraphenyltetrabenzo[a,c,lm,qr]hexacene-10,21-dione (9) in
57% yield.
Phenyllithium added smoothly to a refluxing suspension of 5 in
dry benzene, followed by treatment of its crude diol intermediate
with SnCl2 and HCl in refluxing THF. After recrystallization of the
isolated red solid, compound 2 was produced cleanly in 73%
yield. This three-step synthesis from phencyclone (6) gave 2 in
an overall yield of 20%, an estimated 24-fold improvement over
its original seven convergent step synthesis. Phenyllithium
addition to 9, followed by SnCl2-mediated reduction produced
9,10,11,20,21,22-hexaphenyltetrabenzo[a,c,lm,qr]hexacene (10)
in 35% yield.
Figure 1. Molecular structure of compound 10. Thermal ellipsoids have been
drawn at the 50% probability level, and all hydrogens except H1 have been
omitted for clarity.
A seemingly straightforward means of obtaining LTAs with even
greater twists than that of pentacene 2 would be by the addition
of bulkier aryllithium reagents to quinone 5. 5-Bromo-m-xylene
was converted to its corresponding aryllithium reagent by
treatment with n-butyllithium at -78 °C, and it was added to a
refluxing suspension of quinone 5 in dry benzene. SnCl2-
mediated reduction of the diol intermediate afforded 10,21-
bis(3,5-dimethylphenyl)-9,11,20,22-tetraphenyltetrabenzo[a,c,l,n]
pentacene (11) in 55% yield. Crystals of compound 11 suitable
for X-ray analysis were obtained from CH2Cl2–hexanes, and its
molecular structure is shown in Figure 2. Acene 11 crystallizes
in a general position in the monoclinic space group P21/c, with Z
Scheme 2. 1-Np represents a 1-naphthyl group. Conditions: (a) nitrobenzene,
reflux 24 h, 36%; (b) for 2: i. phenyllithium, benzene, reflux 1 h, rt 20 h; ii.
anhyd. SnCl2, THF, HCl, reflux 1 h, 73% (steps i and ii); for 11: i. 5-bromo-m-
xylenes, nBuLi, THF, -78 °C, benzene, reflux 1 h, rt 22 h; ii. SnCl2•2H2O, THF,
HCl, reflux 1 h, 55% (steps i and ii); for 12: i. 1-bromonaphthalene, nBuLi, THF,
-78 °C, benzene, reflux 1 h, rt 24 h; ii. SnCl2•2H2O, THF, HCl, reflux 1 h, 29%
(steps i and ii); (c) nitrobenzene, reflux 24 h, 57%; and (d) i. phenyllithium,
benzene, reflux 30 min, rt 24 h; ii. SnCl2•2H2O, THF, HCl, reflux 1 h, 35%
(steps i and ii).
=
4. We assumed that derivative 11, with its sterically
demanding xylene substituents, would naturally possess an
even greater end-to-end twist than the 144° twist observed in 2,
albeit not necessarily dramatically greater. But AM1 calculations
predicted, somewhat to our surprise, that both compounds
should possess identical end-to-end twists. We were therefore
pleased to find the C28–C27–C3–C19 torsion angle measured
at 147.7°, with individual rings twists (from left-to-right) of 27°,
29°, 28°, 30°, and 31°, respectively, thus making acene 11 the
most twisted pentacene yet known. Average distance between
Compound 10 is a red solid, and crystals suitable for X-ray
analysis were obtained from 1,2,4-trimethylbenzene–MeOH. Its
molecular structure is shown in Figure 1. Acene 10 crystallizes
in a special position in the monoclinic space group C2/c, with Z =
4, and it possesses crystallographic C2 symmetry. Although the
pyrene moiety in compound 10 would appear to offer the same
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ipso carbons and benzo hydrogens [e.g., C35–H77] for 11 is
2.42 Å, slightly greater than that observed in compound 2, while
the average distance between ipso carbons [e.g., C35–C41] is
2.94 Å. which is identical.
distances are virtually identical to those observed in pentacene 2,
while the C–H distances differ only slightly.
Figure 3. Molecular structure of compound 12. Thermal ellipsoids have been
drawn at the 50% probability level, and all hydrogens except H25 have been
omitted for clarity.
Figure 2. Molecular structure of compound 11. Thermal ellipsoids have been
drawn at the 50% probability level, and all hydrogens except H77 have been
omitted for clarity.
Refluxing
7 with tetracyclone (3) in nitrobenzene formed
9,11,12,13,14,16-hexaphenyldibenzo[a,c]tetracene-10,15-dione
(13) in 22% yield (Scheme 3), a reasonable precursor for the
previously reported 9,10,11,12,13,14,15,16-octaphenyldibenzo-
[a,c]tetracene[28] (14). Phenyllithium was added to 13 in dry THF,
but unlike with the previous syntheses, isolation of the crude diol
was skipped—a solution of SnCl2 and HCl were added directly to
the reaction contents, giving 14 in 40% yield. The overall yield of
acene 14 from phencyclone (6) was 6.6%, an almost 66-fold
improvement over its original synthesis. Condensation of
dienone 7 with the easily prepared acecyclone[23] (15) gave
7,9,18,20-tetraphenylacenaphtho[1,2-k]dibenzo[a,c]tetracene-
8,19-dione (16) in 54% yield. Addition of phenyllithium followed
by reduction produced 7,8,9,18,19,20-hexaphenylacenaphtho-
[1,2-k]dibenzo[a,c]tetracene (17) in 20% yield.
Surprisingly, the addition of the even bulkier 1-naphthyl (1-Np)
substituent proved to be just as facile as the others. Similar to
the synthesis of compound 11 described previously, 10,21-di(1-
naphthyl)-9,11,20,22-tetraphenyltetrabenzo[a,c,l,n]pentacene
(12) was produced in 29% yield. With the addition of naphthyl
substituents, the formation of both cis- and trans-isomers is a
1
likely possibility. But the H NMR spectrum of 12—derived from
the reduction of the crude diol intermediate—showed the
predominance of only one isomer. Which one? The X-ray crystal
structure of quinone 5,[22] which shows the carbonyl groups trans
to one another and tilted up, with the surrounding phenyl
substituents splayed open and situated underneath, would lead
one to expect the trans-isomer to be the dominant, if not
exclusive, product formed. Chromatographic purification of the
crude diol was used to obtain a pure diol, as determined by TLC,
and after its reduction, we were able to obtain a clean NMR
spectrum of a single isomer—what we posit to be the pure trans-
isomer.
Crystals for X-ray analysis for compound 12 were grown from
the product obtained from the reduction of the crude diol, and its
molecular structure is shown in Figure 3. Acene 12 crystallizes
in a general position in the triclinic space group P1, with Z = 2,
and shows only the presence of the trans-isomer. The C10–
C11–C29–C30 torsion angle measures at 140.9°, less than the
AM1 calculated 144° end-to-end twist, with individual rings twists
(from left-to-right) of 26°, 29°, 29°, 29°, and 27°, respectively.
Average distance between ipso carbons and benzo hydrogens
[e.g., C71–H25] for 12 is 2.37 Å, while the average distance
between ipso carbons [e.g., C71–C61] is 2.94 Å. The C–C
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Conclusions
We have adapted a classical method for the synthesis of
substituted acenes, which we have coined the “quinone”
approach, as an alternative to the “benzyne” approach for the
synthesis of seven longitudinally twisted acenes. It is quite
evident that if a suitable quinone precursor is available, it is a far
superior approach, as demonstrated by the relatively facile
syntheses of the previously reported compounds 1, 2, and 14,
whose overall yields were increased by 50-, 24-, and 66-fold,
respectively. Professor Pascal, to whom we have communicated
our preliminary synthetic results, reports that
a first-year
graduate student was able to prepare five grams of pentacene 2
in less than two weeks by using our method, which also speaks
its scalability. AM1 calculations provide a good guide for the
end-to-end twists of LTAs, but cannot predict how the twists will
be impacted by crystal packing forces as compounds 10 (134.6°
versus AM1 141.5°), 11 (147.7° versus AM1 144.1°), and 12
demonstrate (140.9° versus AM1 144°). And counter to what
one would think, addition of bulkier aryllithium substituents—as
compared to the phenyl group—has little to no impact on the
end-to-end twist as predicted by AM1 and confirmed by X-ray
crystallography, although each differs slightly from calculations
in their solid state.
Scheme 3. Conditions: (a) nitrobenzene, reflux 48 h, 22%; (b) i. phenyllithium,
THF, rt 1.5 h, reflux 1.5 h; ii. SnCl2•2H2O, THF, HCl, reflux 18 h, 40% (steps i
and ii); (c) nitrobenzene, reflux 25 h, 54%; (d) i. phenyllithium, THF, rt 24 h; ii.
SnCl2•2H2O, THF, HCl, reflux 16 h, 20% (steps i and ii).
Orange crystals of acene 17 suitable for X-ray analysis were
grown from EtOAc–CH2Cl2, and its molecular structure is shown
in Figure 4. Acene 17 lies in a general position and crystallizes
in the monoclinic space group P21/n, with Z = 4. The C22–C21–
C15–C14 torsion angle measures 102.3°, while the end-to-end
twist of the tetracene substructure within is 96.1°—AM1
calculations predict an overall twist of 109° and the tetracene
substructure twist to be 104.5°. Compound 17 displays
remarkable stability in a chloroform solution exposed to air and
ambient light, showing only slight decomposition, as judged by
TLC, even after several weeks.
Table 1. Theoretical and observed twist dihedral angle.
Compound
AM1
X-ray
1[6]
2[7,8]
10
67°
63°
144°
144°
141.5°
144.1°
144°
134.6
147.7°
140.9°
105°
11
12
14[28]
17
109.3°
109°, 104.5°
102.3°,
96.1°
Experimental Section
Materials and Methods
All commercial reagents obtained were used as purchased
unless noted otherwise. THF was distilled from sodium–
benzophenone and benzene was distilled from calcium hydride,
both under an argon atmosphere. All melting points were
recorded on a Mel-Temp apparatus and are uncorrected. TLC
was performed on 0.25 mm polyester-backed silica gel plates
with F254 indicator. Spots were visualized with UV light (254 nm
and 365 nm). Column chromatography was performed with silica
Figure 4. Molecular structure of compound 17. Thermal ellipsoids have been
drawn at the 50% probability level, and all hydrogens except H1 have been
omitted for clarity.
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gel 60Å (18–32 μm mesh). 1H NMR spectra were recorded on a
Varian AC 400 spectrometer operating at 400 MHz. Chemical
shifts (δ) are reported in ppm using the residual solvent peak as
the internal standard (CHCl3: δ 7.26). 1H NMR data are reported
as follows: chemical shift, multiplicity (s = singlet, d = doublet, t =
triplet, dd = doublet of doublets, dt = doublet of triplets, td =
triplet of doublets, m = multiplet, br = broad signal), coupling
constant (reported to the nearest 0.5 Hz), and integration. 13C
NMR spectra were recorded on a Varian AC 400 spectrometer
operating at 101 MHz. Chemical shifts (δ) are reported in ppm
using the residual solvent peak as the internal standard (CHCl3:
under argon. The reaction was quenched by the addition of
water (10 mL) and acidified with acetic acid. The contents were
poured into water (20 mL) and steam distilled to remove the
organic solvents. The solid was collected via vacuum filtration
and rinsed with ethanol. The crude diol was brought to reflux in
THF (10 mL) in a screw-capped vial. A solution of anhyd. SnCl2
(920 mg, 4.9 mmol) dissolved into HCl (1 mL) was added in one
portion to the refluxing THF suspension. The reaction contents
were maintained at reflux for 1 h. The reaction contents were
diluted with acetone (15 mL) and filtered. The solid was
recrystallized from CHCl3MeOH to give 1 as a yellow solid (120
1
δ
77.0). Mass spectra were recorded using either an
mg, 0.13 mmol, 52%): mp >400 °C (lit.[6] mp >400 °C); H NMR
atmospheric pressure photoionization (APPI) source on a time-
of-flight (TOF) instrument in the positive mode with the use of
toluene to promote ionization when necessary, an electrospray
ionization (ESI) source on a time-of-flight (TOF) instrument in
the positive mode, or a matrix assisted laser desorption (MALDI-
TOF). UV-Vis spectra were collected on an Ocean Optics
USB2000 UV-Vis-NIR spectrophotometer. X-ray data were
collected by using graphite monochromated Mo K radiation
(0.71073 Å) on a Nonius KappaCCD diffractometer. No special
steps were taken to exclude oxygen or moisture during the
growth of X-ray quality crystals. The diffraction data were
processed and reduced with DENZO,[29] PLATON,[30] Siemens
SHELXTL,[31] and SQUEEZE/BYPASS.[32] All structures were
solved by direct methods and were refined by full-matrix least-
squares on F2 using SHELXTL. All structures were solved by the
charge flipping algorithm or direct methods.
(400 MHz, CDCl3) δ 6.27 (d, J = 8 Hz, 8 H), 6.41 (t, J = 7 Hz, 4
H), 6.47–6.60 (m, 22 H), 6.70–6.78 (m, 16 H); 13C NMR (101
MHz, CDCl3) δ 124.1, 124.8, 125.4, 125.9, 126.1, 126.4, 131.1,
131.8, 132.3, 134.8, 135.9, 136.9, 138.5, 140.4, 140.9, 142.0
(16 of 16 expected resonances observed); NMR spectra are
essentially identical to that reported by Qiao et al.[6]; HRMS (ESI-
TOF) m/z 961.3787 ([M + Na]+), calcd for C74H50Na 961.3805.
Synthesis of Phencyclone (6)
It was synthesized by a procedure adapted from the work of
Pascal et al.[24] Small aliquots of a solution of NaOH (1.09 g,
27.3 mmol) in ethanol (30 mL) were added to a suspension of
9,10-phenanthrenequinone (3.02 g, 14.5 mmol) and 1,3-
diphenylacetone (3.28 g, 15.6 mmol) in ethanol (100 mL). Once
complete, the reaction contents were stirred at rt for 15 min, then
heated to a gentle reflux, at which point the flask was
immediately placed into an ice-bath. Once cooled, the
precipitate was collected via vacuum filtration and rinsed with
ethanol to give 6 as a black solid, which was used in the next
step without any further purification (4.90 g, 12.8 mmol, 88.3%):
1H NMR (400 MHz, CDCl3) δ 6.95 (t, J = 7 Hz, 2 H), 7.28–7.30
(m, 2 H), 7.36–7.45 (m, 10 H), 7.55 (dd, J = 8, 1 Hz, 2 H), 7.81
(d, J = 7.5 Hz, 2 H); NMR spectrum is essentially identical to that
reported by Marchand et al.[25]; HRMS (ESI-TOF) m/z 405.1250
([M + Na]+), calcd for C29H18ONa 405.1250.
Synthesis of Octaphenylanthraquinone (4)
It was synthesized by a procedure adapted from the work of Lu
et al.[20] Tetracyclone 3 (10.0 g, 26.0 mmol) and p-benzoquinone
(1.49 g, 13.8 mmol) were heated at reflux in nitrobenzene (20
mL) for 23 h. The reaction contents were poured into ethanol
(300 mL), and the precipitate was collected via vacuum filtration.
The solid was stirred in acetone (100 mL) and vacuum filtered.
The crude quinone was subjected to column chromatography
(silica gel; eluent: CH2Cl2). All the fractions containing quinone 4,
Rf 0.69 TLC (silica gel; eluent: 1:9 EtOAc‒toluene) were
combined, and the solvent was removed under reduced
pressure. The residue was triturated with acetone and vacuum
filtered to give 4 as a tannish solid, which was used in the next
step without any further purification (1.03 g, 1.26 mmol, 9.69%).
An analytical sample was obtained by recrystallizing a small
amount of 4 from CHCl3–MeOH: mp 401–402 °C (lit.[20] mp 391‒
Synthesis of 9,14-Diphenylbenzo[f]tetraphene-10,13-dione
(7)
It was was synthesized by a procedure adapted from the work of
Mondal et al.[26] Phencyclone 6 (5.08 g, 13.3 mmol) and p-
benzoquinone (4.82 g, 44.6 mmol) were heated at reflux in
nitrobenzene (20 mL) for 2 h. The reaction contents were poured
into ethanol (300 mL) and the precipitate was collected via
392 °C); 1H NMR (400 MHz, CDCl3) δ 6.71 (dd, J = 7, 2 Hz, 8 H), vacuum filtration. The solid was dissolved in a minimal amount
6.80‒6.83 (m, 12 H), 6.93‒6.99 (m, 20 H); 13C NMR (101 MHz,
CDCl3) δ 125.9, 126.1, 126.7, 126.9, 130.3, 130.7, 135.4, 137.8,
138.7, 139.8, 146.3, 188.6 (12 of 12 expected resonances
observed); NMR spectra are essentially identical to that reported
by Lu et al.[20]; HRMS (ESI-TOF) m/z 839.2905 ([M + Na]+),
calcd for C62H40O2Na 839.2921.
of CH2Cl2, and it was subjected to column chromatography
(silica gel; eluent: CH2Cl2). A red band was collected with Rf 0.54
TLC (silica gel; eluent: 1:9 EtOActoluene). The solvent was
removed under reduced pressure to give 7 as an orange solid,
which was used in the next step without any further purification
(4.58 g, 9.95 mmol, 74.9%). An analytical sample was obtained
by recrystallizing a small amount of 7 from CHCl3MeOH: mp
1
Synthesis of Decaphenylanthracene (1)
320.5 °C dec (lit.[26] mp 305 °C); H NMR (400 MHz, CDCl3) 
Phenyllithium (1.8 M in dibutyl ether, 0.70 mL, 1.3 mmol) was
added to a suspension of quinone 4 (200 mg, 0.24 mmol) in dry
benzene (10 mL), and the contents were stirred for 17 h at rt
6.88 (s, 2 H), 7.07 (td, J = 8, 1 Hz, 2 H), 7.337.36 (m, 4 H),
7.447.52 (m, 10 H), 8.40 (d, J = 7.5 Hz, 2 H); 13C NMR (101
MHz, CDCl3)  123.3, 125.7, 127.7, 128.1, 129.0, 129.5, 129.9,
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130.3, 130.7, 132.4, 136.5, 138.9, 139.6, 141.2, 186.9 (15 of 15
expected resonances observed); HRMS (ESI-TOF) m/z
483.1354 ([M + Na]+), calcd for C34H20O2Na 483.1356.
7.35 (m, 12 H), 7.38 (t, J = 8 Hz, 2 H), 7.43 (t, J = 7.5 Hz, 2 H),
7.53 (d, J = 8.5 Hz, 2 H), 7.80 (d, J = 8 Hz, 2 H), 7.92 (s, 2 H),
7.94 (d, J = 7.5 Hz, 2 H), 8.36 (d, J = 8 Hz, 2 H); due to poor
solubility, a definitive 13C NMR spectral characterization of 9
could not be obtained; HRMS (ESI-TOF) m/z 859.2605 ([M +
Na]+), calcd for C64H36O2Na 859.2608.
Synthesis of 9,11,20,22-Tetraphenyltetrabenzo[a,c,l,n]penta-
cene-10,21-dione (5)
Quinone 7 (660 mg, 1.4 mmol) and phencyclone 6 (610 mg, 1.6
mmol) were placed into a screw-capped vial and gradually
heated to reflux in nitrobenzene (4 mL) over the course of 1 h.
The reaction contents were maintained at reflux for 24 h. The
reaction mixture was diluted with acetone (20 mL) and the
precipitate was collected via vacuum filtration. The solid was
boiled briefly in nitrobenzene (20 mL) and diluted with acetone
(10 mL). The precipitate was collected via vacuum filtration to
give 5 as a yellow solid, which was used in the next step without
any further purification (420 mg, 0.52 mmol, 36%): mp >400 °C
Synthesis of 9,10,11,20,21,22-Hexaphenyltetrabenzo[a,c,l,n]
pentacene (2)
Phenyllithium (1.8 M in dibutyl ether, 0.4 mL, 0.7 mmol) was
added to a suspension of quinone 5 (110 mg, 0.14 mmol) in dry
benzene (8 mL) under argon at reflux. The reaction contents
were maintained at reflux for 1 h and then stirred for 20 h at rt.
The reaction was quenched by the addition of water (10 mL) and
acidified with acetic acid. The contents were poured into water
(10 mL) and steam distilled to remove the organic solvents. The
aqueous mixture was extracted with CH2Cl2, dried over Na2SO4,
and filtered. The solvent was removed under reduced pressure.
The crude diol was heated at reflux in THF (6 mL) in a screw-
capped vial. A solution of anhyd. SnCl2 (1.09 g, 5.75 mmol)
dissolved into HCl (1 mL) was added in one portion to the
refluxing THF solution. The reaction contents were maintained at
reflux for 1 h. The THF was removed under reduced pressure,
and the residue was triturated with water (20 mL). The solid was
collected via vacuum filtration and rinsed thoroughly with ethanol.
Recrystallization from CHCl3‒MeOH gave 2 as a red solid (92
mg, 0.098 mmol, 73%): mp >400 °C (lit.[7,8] mp >470 °C); 1H
NMR (400 MHz, CDCl3) δ 6.41 (t, J = 7.5 Hz, 4 H), 6.52 (tt, J =
7.5, 1.5 Hz, 2 H), 6.56 (dd, J = 8.5, 1 Hz, 4 H), 6.62‒6.71 (m, 12
H), 6.73‒6.77 (m, 8 H), 6.86 (tt, J = 7.5, 1.5 Hz, 4 H), 6.92 (td, J
= 7.5, 1 Hz, 4 H), 7.23 (td, J = 7.5, 1 Hz, 4 H), 8.06 (dd, J = 8, 1
Hz, 4 H); 13C NMR (101 MHz, CDCl3) δ 123.4, 125.3, 125.7,
126.2, 126.6, 127.7, 127.8, 128.0, 130.0, 132.1, 132.6, 132.9,
1
(lit.[21] mp 460–461 °C); H NMR (400 MHz, CDCl3) δ 7.02 (td, J
= 8, 1 Hz, 4 H), 7.22–7.33 (m, 20 H), 7.43 (td, J = 8, 1 Hz, 4 H),
7.51 (dd, J = 8.5, 1 Hz, 4 H), 8.35 (dd, J = 8, 1 Hz, 4 H); NMR
spectrum is essentially identical to that reported by Pascal et
al.[22]
Synthesis of Pyrenecyclone (8)
It was synthesized by a procedure adapted from the work of
Pascal et al.[24] A solution of KOH (240 mg, 4.3 mmol) in ethanol
(5 mL) was added in small aliquots to a stirring suspension of
pyrene-4,5-dione[33] (460 mg, 2.0 mmol) and 1,3-
diphenylacetone (450 mg, 2.1 mmol) in ethanol (50 mL). Once
the addition was complete, the reaction contents were stirred at
rt for 15 min. The reaction mixture was heated to reflux and then
immediately cooled in an ice-bath. The precipitate was collected
via vacuum filtration and rinsed with ethanol. Recrystallization
from CHCl3MeOH gave 8 as a brown solid, which was used in
the next step without any further purification (350 mg, 0.86 mmol, 133.0, 133.1, 134.1, 134.2, 135.0, 140.0, 141.1 (19 of 22
43%): mp 226 °C dec (lit.[27] mp 235239 °C); 1H NMR (400 MHz, expected resonances observed; but the δ 126.6 resonance may
CDCl3) δ 7.25 (t, J = 8 Hz, 2 H), 7.39–7.50 (m, 10 H), 7.66 (s, 2
H), 7.74 (dd, J = 7.5, 1 Hz, 2 H), 7.87 (dd, J = 7.5, 1 Hz, 2 H);
NMR spectrum is essentially identical to that reported by Pascal
et al.[27]; HRMS (ESI-TOF) m/z 407.1420 ([M + H]+), calcd for
C31H19O 407.1430.
contain two lines); NMR spectra are essentially identical to that
reported by Lu et al.[7,8]; MS (MALDI-TOF) m/z 934.290 ([M]+),
calcd for C74H46 934.3600.
Synthesis
of
9,10,11,20,21,22-Hexaphenyltetrabenzo
[a,c,lm,qr]hexacene (10)
Synthesis of 9,11,20,22-Tetraphenyltetrabenzo[a,c,lm,qr]
hexacene-10,21-dione (9)
Phenyllithium (2 M in dibutyl ether, 0.80 mL, 1.6 mmol) was
added to a suspension of quinone 9 (210 mg, 0.25 mmol) in dry
benzene (10 mL) at rt under argon. The reaction was heated at
reflux for 30 min and then stirred for 24 h at rt. The reaction was
quenched by the addition of water (10 mL) and acidified with
acetic acid. The contents were poured into water (20 mL) and
steam distilled to remove the organic solvents. The aqueous
mixture was extracted with CH2Cl2. The organic extract was
dried over Na2SO4 and filtered. The solvent was removed under
reduced pressure. The crude diol was heated at reflux in THF (8
mL) with SnCl2•2H2O (1.05 g, 4.65 mmol) and HCl (1 mL) in a
screw-capped vial for 1 h. The reaction contents were poured
into water (70 mL) and extracted with CH2Cl2. The organic
extract was dried over Na2SO4 and filtered. The solvent was
removed under reduced pressure. The residue was subjected to
column chromatography (silica gel; eluent: hexanes, followed by
Quinone 7 (510 mg, 1.1 mmol) and pyrenecyclone 8 (510 mg,
1.3 mmol) were placed into a screw-capped vial and heated to
reflux over the course of 1.5 h in nitrobenzene (3 mL). The reflux
was maintained for 24 h. The reaction contents were diluted with
acetone (25 mL). The precipitate was collected via vacuum
filtration and rinsed with ethanol and acetone. The solid was
briefly boiled in nitrobenzene (10 mL) and then diluted with
acetone (10 mL). The precipitate was collected via vacuum
filtration to give 9 as a yellow solid, which was used in the next
step without any further purification (530 mg, 0.63 mmol, 57%).
An analytical sample was obtained by subjecting a small amount
of 9 to column chromatography (silica gel; eluent: toluene,
followed by 20% CH2Cl2toluene): mp >400 °C; 1H NMR (400
MHz, CDCl3) δ 7.02 (t, J = 8 Hz, 2 H), 7.16–7.26 (m, 8 H), 7.28–
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10.1002/chem.201704501
Chemistry - A European Journal
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20% toluene–hexanes). A red fluorescent band was collected
with Rf 0.42 TLC (silica gel; eluent: 3:7 CH2Cl2–hexanes).
Recrystallization from CHCl3–MeOH gave 10 as a red solid (85
mg, 0.089 mmol, 35%): mp >400 ºC; 1H NMR (400 MHz, CDCl3,
25 °C) δ 6.40 (q, J = 8 Hz, 4 H), 6.51 (d, J = 7.5 Hz, 2 H), 6.53–
6.68 (m, 13 H), 6.72–6.79 (m, 7 H), 6.84–6.89 (m, 6 H), 6.92–
but the δ 127.2 and 132.6 resonances may contain two lines);
UV (CHCl3) λmax (log ϵ) 376 (sh, 5.04), 393 (5.25), 481 (sh, 3.81),
505 (3.90), 539 (3.79); HRMS (APPI-TOF) m/z 991.4248 ([M +
H]+), calcd for C78H55 991.4298; crystals suitable for X-ray
analysis were obtained from CH2Cl2–MeOH.
7.01 (m, 4 H), 7.07 (t, J = 8 Hz, 2 H), 7.21–7.25 (m, 2 H), 7.70 (d, Synthesis of 10,21-Di(1-naphthyl)-9,11,20,22-tetraphenyl
J = 7.5 Hz, 2 H), 7.79 (s, 2 H), 8.06 (dd, J = 8, 1 Hz, 2 H); 13C
NMR (101 MHz, CDCl3) δ 123.4, 124.3, 125.3, 125.4, 125.7,
126.2, 126.6, 127.7, 127.8, 127.9, 128.0, 128.2, 130.1, 130.6,
130.7, 132.1, 132.6, 132.8, 132.9, 133.1, 133.2, 133.3, 134.2,
134.9, 135.1, 135.3, 140.0, 141.2, 141.5 (29 of 32 expected
resonances observed; but the δ 127.7, 128.0, 133.1, and 134.2
resonances may contain two lines, and the δ 126.2 and 126.6
resonances may contain three lines); UV (CHCl3) λmax (log ϵ) 403
(4.97), 486 (sh, 3.99), 508 (4.04), 543 (3.87); HRMS (ESI-TOF)
m/z 958.3537 ([M]+), calcd for C76H46 958.3600; crystals suitable
for X-ray analysis were obtained from 1,2,4-trimethylbenzene–
MeOH.
tetrabenzo[a,c,l,n]pentacene (12)
n-Butyllithium (2.5 M in hexanes, 1.2 mL, 3.0 mmol) was added
in small aliquots to a solution of 1-bromonaphthalene (0.45 mL,
3.2 mmol) in dry THF (6 mL), which was cooled to -78 °C under
argon. Once the addition was complete, the contents were
allowed to stir at -78 °C for 20 min and then stirred at rt until the
opaque contents became clear. The resulting lithium reagent
was added to a refluxing suspension of quinone 5 (220 mg, 0.27
mmol) in dry benzene (20 mL) under argon. The reaction
contents were maintained at reflux for 1 h and then stirred for 24
h at rt. The reaction was quenched by the addition of water (10
mL) and acidified with acetic acid. The contents were poured
into water (20 mL) and steam distilled to remove the organic
solvents. The aqueous mixture was extracted with CH2Cl2, dried
over Na2SO4, and filtered. The solvent was removed under
reduced pressure. The residue was placed into a screw-capped
vial with THF (8 mL) and the contents brought to reflux. A
solution of SnCl2•2H2O (3.88 g, 17.2 mmol) dissolved into HCl (1
mL) was added in one portion to the refluxing THF solution. The
reaction contents were maintained at reflux for 1 h. The solvent
was removed under reduced pressure, and the residue was
dissolved into CH2Cl2. The organic solvent was washed with
water (75 mL), dried over Na2SO4, and filtered. The solvent was
removed under reduced pressure. The solid was subjected to
column chromatography (silica gel; eluent: hexanes, followed by
1:3 and then 1:1 CH2Cl2–hexanes). A red fluorescent band was
collected with Rf 0.69 TLC (silica gel; eluent: 1:1 CH2Cl2–
hexanes). Recrystallization from o-dichlorobenzene–acetone
gave 12 as a red solid (81 mg, 0.078 mmol, 29%): mp >400 °C;
a clean NMR spectra was obtained by subjecting a small
amount of the crude diol to column chromatography (silica gel;
eluent: toluene). A blue fluorescent band was collected with Rf
0.30 TLC (silica gel; eluent: 3:7 hexanes–toluene). This band
was again subjected to column chromatography (silica gel;
eluent: hexanes, followed by 2:3 toluene–hexanes). The eluent
was removed under reduced pressure and the residue triturated
with methanol and then acetone to give presumably the pure
trans-diol, which was reduced to form 12 under conditions stated
above; 1H NMR (400 MHz, CDCl3) δ 5.71 (dq, J = 8, 1 Hz, 2 H),
6.16–6.24 (m, 4 H), 6.33 (tt, J = 7.5, 1.5 Hz, 2 H), 6.42 (td, 7.5, 1
Hz, 2 H), 6.54–6.58 (m, 6 H), 6.61 (dt, J = 7.5, 1.5 Hz, 2 H),
6.65–6.71 (m, 6 H), 6.73–6.77 (m, 2 H), 6.86 (td, J = 7.5, 1.5 Hz,
2 H), 6.94–6.96 (m, 6 H), 7.02 (d, J = 8.5 Hz, 2 H), 7.06–7.10 (m,
4 H), 7.16 (td, J = 7.5, 1 Hz, 2 H), 7.21 (td, J = 7.5, 1 Hz, 2 H),
Synthesis of 10,21-Bis(3,5-dimethylphenyl)-9,11,20,22-tetra-
phenyltetrabenzo[a,c,l,n] pentacene (11)
n-Butyllithium (2.5 M in hexanes, 1.2 mL, 3.0 mmol) was added
in small aliquots to a solution of 5-bromo-m-xylenes (0.45 mL,
3.3 mmol) in dry THF (6 mL) which was cooled to -78 °C under
argon. Once the addition was complete, the contents were
allowed to stir at -78 °C for 20 min, and then stirred at rt until the
opaque contents became clear. The resulting lithium reagent
was added to a refluxing suspension of quinone 5 (210 mg, 0.26
mmol) in dry benzene (20 mL) under argon. The reaction
contents were maintained at reflux for 1 h, and then stirred for
22 h at rt. The reaction was quenched by the addition of water
(10 mL) and acidified with acetic acid. The contents were poured
into water (20 mL) and steam distilled to remove the organic
solvents. The aqueous mixture was extracted with CH2Cl2, dried
over Na2SO4, filtered, and the solvent removed under reduced
pressure. The residue was placed into a screw-capped vial with
THF (8 mL) and the contents brought to reflux. A solution of
SnCl2•2H2O (4.06 g, 18.0 mmol) dissolved into HCl (1 mL) was
added in one portion to the refluxing THF solution. The reaction
contents were maintained at reflux for 1 h. The THF was
removed under reduced pressure. An equal volume of a water–
ethanol solution (30 mL) was added to the residue and the
resulting precipitate was collected via vacuum filtration, and
rinsed with ethanol. The solid was subjected to column
chromatography (silica gel; eluent: hexanes, followed by 1:3
CH2Cl2–hexanes). A red fluorescent band was collected with Rf
0.46 TLC (silica gel; eluent: 3:7 CH2Cl2–hexanes).
Recrystallization from o-dichlorobenzene–acetone gave 11 as a
1
red solid (140 mg, 0.14 mmol, 55%): mp >400 °C; H NMR (400
MHz, CDCl3) δ 1.77 (s, 12 H), 6.04 (s, 2 H), 6.18 (d, J = 1.5 Hz,
4 H), 6.62‒6.65 (m, 4 H), 6.67‒6.70 (m, 8 H), 6.73‒6.78 (m, 8 H), 7.31 (dd, J = 8.5, 1.5 Hz, 2 H), 7.99 (dd, J = 8, 1 Hz, 2 H), 8.05
6.85 (tt, J = 7.5, 1.5 Hz, 4 H), 6.95 (td, J = 7.5, 1 Hz, 4 H), 7.23
(td, J = 7.5, 1 Hz, 4 H), 8.08 (dd, J = 8, 1 Hz, 4 H); 13C NMR (101
MHz, CDCl3) δ 20.4, 123.4, 125.3, 125.8, 126.5, 127.2, 127.3,
127.4, 130.2, 132.3, 132.6, 132.9, 133.0, 133.2, 134.3, 134.5,
135.1, 139.5, 141.2 (19 of 19 expected resonances observed;
(dd, J = 8, 1 Hz, 2 H); 13C NMR (101 MHz, CDCl3) δ 123.1,
123.4, 124.4, 124.6, 124.8, 125.0, 125.2, 125.3, 126.1, 126.5,
126.6, 126.9, 127.1, 127.3, 127.5, 128.0, 130.0, 131.1, 131.8,
131.9, 132.0, 132.1, 132.4, 132.6, 132.8, 133.0, 133.4, 133.7,
134.4, 134.6, 134.7, 134.8, 137.9, 140.3, 140.5 (35 of 37
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10.1002/chem.201704501
Chemistry - A European Journal
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expected resonances observed; but the δ 126.5, 130.0, and
131.1 resonances may contain two lines); UV (CHCl3) λmax (log
ϵ) 391 (5.09), 478 (sh, 3.80), 508 (3.91), 537 (3.82); HRMS
(APPI-TOF) m/z 1035.3928 ([M + H]+), calcd for C82H51
1035.3985; crystals suitable for X-ray analysis were obtained
from toluene–MeOH.
was obtained by recrystallizing a small amount of 16 from
CHCl3‒MeOH: mp 396–399 °C dec; H NMR (400 MHz, CDCl3)
1
δ 6.63 (d, J = 7 Hz, 2 H), 7.02 (td, J = 7.5, 1.5 Hz, 2 H), 7.17‒
7.21 (m, 4 H), 7.26‒7.29 (m, 9 H), 7.33 (t, J = 7.5 Hz, 2 H),
7.40–7.47 (m, 9 H), 7.64 (dd, J = 8.5, 1 Hz, 2 H), 7.79 (d, J = 7.5
Hz, 2 H), 8.35 (dd, J = 8, 1 Hz, 2 H); due to poor solubility, a
definitive 13C NMR spectral characterization of 16 could not be
obtained; HRMS (ESI-TOF) m/z 809.2420 ([M + Na]+), calcd for
C60H34O2Na 809.2451.
Synthesis of Acecyclone (15)
It was synthesized by a procedure adapted from the work of
Pascal et al.[24] Small aliquots of a solution of NaOH (1.57 g,
39.3 mmol) in ethanol (50 mL) were added to a suspension of
acequinone (4.00 g, 22.0 mmol) and 1,3-diphenylacetone (5.25
g, 25.0 mmol) in ethanol (100 mL) at rt. Once complete, the
reaction contents were stirred at rt for 15 min, then heated to a
gentle reflux, at which point the flask was immediately placed
into an ice-bath. Once cooled, the precipitate was collected via
vacuum filtration and rinsed with ethanol to give 15 as a brown
solid, which was used in the next step without any further
purification (7.40 g, 20.8 mmol, 94.6%). An analytical sample
was obtained by recrystallizing a small amount of 15 from
CHCl3–MeOH: mp 286–289 °C gas evolution (lit.[23] mp 289–
290 °C); 1H NMR (400 MHz, CDCl3) δ 7.41 (tt, J = 7.5, 1.5 Hz, 2
H), 7.50–7.55 (m, 4 H), 7.59 (t, J = 7.5 Hz, 2 H), 7.82–7.84 (m, 4
H), 7.87 (d, J = 8 Hz, 2 H), 8.07 (d, J = 7 Hz, 2 H); HRMS (ESI-
TOF) m/z 379.1096 ([M + Na]+), calcd for C27H16ONa 379.1093.
Synthesis of 9,10,11,12,13,14,15,16-Octaphenyldibenzo[a,c]
tetracene (14)
Phenyllithium (1.8 M in dibutyl ether, 0.50 mL, 0.90 mmol) was
added to a suspension of quinone 13 (110 mg, 0.13 mmol) in dry
THF (10 mL) under argon. The reaction contents were stirred for
1.5 h at rt and then heated at reflux for 1.5 h. After the contents
were cooled to rt, SnCl2•2H2O (560 mg, 2.5 mmol) and HCl (2
mL) were added, and the mixture heated at reflux for 18 h. The
reaction contents were poured into water (40 mL), and diluted
with ethyl acetate (50 mL). The aqueous layer was removed and
was washed with sat. NaCl (2 x 40 mL), dried over Na2SO4, and
filtered. The solvent was removed under reduced pressure. The
residue was subjected to column chromatography (silica gel;
eluent: hexanes, followed by 1:4 toluene–hexanes). An orange
fluorescent band was collected with Rf 0.57 TLC (silica gel;
eluent: 2:3 CH2Cl2–hexanes). Recrystallization from CHCl3–
MeOH gave 14 as an orange solid (50 mg, 0.053 mmol, 40%):
Synthesis of 9,11,12,13,14,16-Hexaphenyldibenzo[a,c]tetra-
cene-10,15-dione (13)
1
mp >400 °C (lit.[28] mp >400 °C); H NMR (400 MHz, CDCl3) δ
Quinone 7 (1.56 g, 3.39 mmol) and tetracyclone 3 (1.90 g, 4.94
mmol) were heated at reflux in nitrobenzene (5 mL) for 48 h.
Methanol (30 mL) was added, and the reaction contents boiled
briefly. The resulting precipitate was collected via vacuum
filtration, and it was subjected to column chromatography (silica
gel; eluent: toluene). A yellow band was collected with Rf 0.72
TLC (silica gel; eluent: 1:9 EtOActoluene). The solvent was
removed under reduced pressure, and the residue triturated with
acetone to give 13 as a yellow solid, which was used in the next
step without any further purification (610 mg, 0.75 mmol, 22%).
An analytical sample was obtained by recrystallizing a small
amount of 13 from CHCl3MeOH: mp 365–367 °C; 1H NMR (400
MHz, CDCl3) δ 6.65–6.70 (m, 4 H), 6.82–6.85 (m, 6 H), 6.94–
6.98 (m, 8 H), 7.00–7.05 (m, 4 H), 7.10–7.14 (m, 4 H), 7.21–7.25
(m, 6 H), 7.42 (td, J = 7.5, 1 Hz, 2 H), 7.62 (dd, J = 8.5, 1 Hz, 2
H), 8.36 (dd, J = 8, 1 Hz, 2 H); due to poor solubility, a definitive
13C NMR spectral characterization of 13 could not be obtained;
6.20 (d, J = 8 Hz, 2 H), 6.26 (t, J = 7.5 Hz, 2 H), 6.34–6.38 (m, 4
H), 6.45–6.54 (m, 12 H), 6.60–6.84 (m, 18 H), 6.90–6.95 (m, 4
H), 7.06 (td, J = 7.5, 1 Hz, 2 H), 7.20 (td, J = 7.5, 1 Hz, 2 H),
8.02 (dd, J = 8, 1 Hz, 2 H); 13C NMR (101 MHz, CDCl3, 35 °C) δ
123.4, 124.4, 124.9, 125.4, 125.6, 125.9, 126.1, 126.2, 126.5,
127.6, 127.8, 128.2, 129.9, 130.7 (br), 131.5, 131.9 (br), 132.2,
132.6, 132.7, 132.9, 133.1, 134.1, 134.8, 135.1, 135.2, 137.0,
138.5, 140.4, 140.5, 141.5, 141.6 (29 expected but 31 of a
theoretically possible 37 resonances observed; but the δ 125.9,
126.5, and 132.6 resonances may contain two lines); NMR
spectra are essentially identical to that reported by Qiao et al.[28]
;
MS (MALDI-TOF) m/z 936.355 ([M]+), calcd for C74H48 936.3756.
Synthesis of 7,8,9,18,19,20-Hexaphenylacenaphtho[1,2-k]di-
benzo[a,c]tetracene (17)
Phenyllithium (2 M in dibutyl ether, 0.70 mL, 1.4 mmol) was
added to a suspension of quinone 16 (200 mg, 0.25 mmol) in dry
THF (10 mL), and the contents were stirred for 24 h at rt under
argon. The reaction was quenched with the addition of water (10
mL), acidified with acetic acid, poured into water (20 mL), and
steam distilled to remove the organic solvents. The solid was
collected via vacuum filtration and rinsed with ethanol. The
crude diol was heated at reflux in THF (6 mL) with SnCl2•2H2O
(1.82 g, 8.07 mmol) and HCl (0.5 mL) in a screw-capped vial for
16 h. The reaction contents were poured into water (60 mL) and
extracted with CH2Cl2. The organic extract was washed with sat.
NaCl (100 mL), dried over Na2SO4, and filtered. The solvent was
removed under reduced pressure. The residue was subjected to
column chromatography (silica gel; eluent: hexanes, followed by
HRMS (ESI-TOF) m/z 837.2742 ([M
C62H38O2Na 837.2764.
+
Na]+), calcd for
Synthesis
of
7,9,18,20-Tetraphenylacenaphtho[1,2-k]di-
benzo[a,c]tetracene-8,19-dione (16)
Quinone 7 (600 mg, 1.3 mmol) and acecyclone 15 (480 mg, 1.3
mmol) were placed into a screw-capped vial and heated at reflux
in nitrobenzene (2 mL) for 25 h. Acetone (10 mL) was added,
and the resulting precipitate was collected via vacuum filtration.
Recrystallization from nitrobenzene‒acetone gave 16 as a
yellow solid, which was used in the next step without any further
purification (550 mg, 0.70 mmol, 54%). An analytical sample
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10.1002/chem.201704501
Chemistry - A European Journal
FULL PAPER
[1]
R. A. Pascal Jr., Chem. Rev. 2006, 106, 4809–4819, and references
cited therein.
1:4 CH2Cl2–hexanes). An orange fluorescent band was collected
with Rf 0.60 TLC (silica gel; eluent: 2:3 CH2Cl2–hexanes). This
fraction was subjected to column chromatography (silica gel;
eluent: hexanes, followed by 3:7 toluene–hexanes).
Recrystallization from toluene–MeOH gave 17 as an orange
solid (47 mg, 0.052 mmol, 20%): mp >400 °C; 1H NMR (400
MHz, CDCl3) δ 6.39–6.53 (m, 12 H), 6.57–6.67 (m, 6 H), 6.71 (td,
J = 8, 1 Hz, 2 H), 6.78–6.83 (m, 4 H), 6.86–7.10 (m, 12 H), 7.19
(t, J = 7.5 Hz, 4 H), 7.61 (d, J = 8 Hz, 2 H), 8.02 (dd, J = 8, 1 Hz,
2 H); 13C NMR (101 MHz, CDCl3) δ 121.8, 123.4, 125.3, 125.4,
125.7, 125.9, 126.1, 126.4, 126.5, 127.5, 127.6, 127.8 (br),
127.9, 128.4, 129.7, 129.9 (br), 130.2, 132.0, 132.5, 133.1,
133.2, 133.5, 134.0, 134.1, 134.6, 135.6, 135.7, 136.1, 136.6,
140.3, 140.4, 141.7 (31 expected but 32 of a theoretically
possible 37 resonances observed; but the δ 132.0 resonance
may contain two lines); UV (CHCl3) λmax (log ϵ) 265 (4.42), 370
(4.67), 388 (4.66), 406 (4.62), 486 (3.97), 512 (3.96); HRMS
(ESI-TOF) m/z 931.3311 ([M + Na]+), calcd for C72H44Na
931.3335; crystals suitable for X-ray analysis were obtained
from EtOAc–CH2Cl2.
[2]
[3]
K. P. Meurer, F. Vögtle, Top. Curr. Chem. 1985, 127, 1–76.
S. Grimme, J. Harren, A. Sobanski, F. Vögtle, Eur. J. Org. Chem. 1998,
1491–1509.
[4]
[5]
J. E. Norton, K. N. Houk, J. Am. Chem. Soc. 2005, 127, 4162‒4163.
R. S. Walters, C. M. Kraml, N. Byrne, D. M. Ho, Q. Qin, F. J. Coughlin,
S. Bernhard, R. A. Pascal Jr., J. Am. Chem. Soc. 2008, 130, 16435–
16441.
[6]
[7]
[8]
[9]
X. Qiao, M. A. Padula, D. M. Ho, N. J. Vogelaar, C. E. Schutt, R. A.
Pascal Jr., J. Am. Chem. Soc. 1996, 118, 741‒745.
J. Lu, D. M. Ho, N. J. Vogelaar, C. M. Kraml, R. A. Pascal Jr., J. Am.
Chem. Soc. 2004, 126, 11168–11169.
J. Lu, D. M. Ho, N. J. Vogelaar, C. M. Kraml, S. Bernhard, N. Byrne, L.
R. Kim, R. A. Pascal Jr., J. Am. Chem. Soc. 2006, 128, 17043–17050.
J. D. Debad, S. K. Lee, X. Qiao, R. A. Pascal Jr., A. J. Bard, Acta Chem.
Scand. 1998, 52, 45–50.
[10] H. Hart, A. Oku, J. Org. Chem. 1972, 37, 4269–4274.
[11] H. Hart, B. Ruge, Tetrahedron Lett. 1977, 3143–3146.
[12] A. Sy, H. Hart, J. Org. Chem. 1979, 44, 7–9.
[13] H. Hart, C.-Y. Lai, G. Nwokogu, S. Shamouilian, A. Teuerstein, C.
Zlotogorski, J. Am. Chem. Soc. 1980, 102, 6649–6651.
[14] H. Hart, C.-Y. Lai, G. C. Nwokogu, S. Shamouilian, Tetrahedron 1987,
43, 5203–5224.
Computational methodology
[15] X. Qiao, I. Pelczer, R. A. Pascal Jr., Chirality 1998, 10, 154–158.
[16] C. Weizmann, E. Bergmann, L. Haskelberg, J. Chem. Soc. 1939, 391–
397.
All calculations were performed using AM1 as implemented in
Gaussian 09.[34] Geometry optimizations were performed for all
compounds followed by frequency calculations to confirm
structures obtained correspond to a minima.
[17] Y. Lepage, O. Pouchot, Bull. Soc. Chim. Fr. 1965, 2342–2344.
[18] S. C. Dickerman, D. De Souza, P. Wolf, J. Org. Chem. 1965, 30, 1981–
1985.
[19] K. Kitazawa, T. Kochi, M. Sato, F. Kakiuchi, Org. Lett. 2009, 11, 1951–
1954.
Supplementary data
1H and 13C NMR spectra of compounds 7, 9, 10, 11, 12, 13, 16,
and 17 and the AM1 optimized structures of compounds 1, 10,
11, 12, 14, and 17 are included in the supplemental material.
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication nos.
CCDC 1570789, 1570790, 1570791, and 1570792. Copies of
the data can be obtained, free of charge, on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, (fax: +44-
(0)1223-336033 or e-mail: deposit@ccdc.cam.ac.uk).
[20] J. Lu, J. Zhang, X. Shen, D. M. Ho, R. A. Pascal Jr., J. Am. Chem. Soc.
2002, 124, 8035‒8041.
[21] B. A. Arbuzov, V. S. Abramov, Ya. B. Devyatov, J. Gen. Chem. USSR
1939, 9, 1559–1563.
[22] R. A. Pascal Jr., D. Van Engen, Tetrahedron Lett. 1987, 28, 293–294.
[23] W. Dilthey, I. ter Horst, W. Schommer, J. Prakt. Chem. 1935, 143, 189–
210.
[24] R. A. Pascal Jr., D. Van Engen, B. Kahr, W. D. McMillan, J. Org. Chem.
1988, 53, 1687–1689.
[25] A. P. Marchand, G. Srinivas, W. H. Watson, ARKIVOC 2003, Part 3, 8–
15.
[26] S. Mondal, A. J. Bhattacharya, Current Science 1984, 53, 12291232.
[27] R. A. Pascal Jr., W. D. McMillan, D. Van Engen, R. G. Eason, J. Am.
Chem. Soc. 1987, 109, 4660–4665.
Acknowledgements
[28] X. Qiao, D. M. Ho, R. A. Pascal Jr., Angew. Chem., Int. Ed. Engl. 1997,
36, 1531–1532.
We would like to acknowledge Professor Robert Pascal (Tulane)
for his input on crystal refinement and editorial comments;
Professor Ben King (Reno) for use of his facilities for X-ray and
mass spectrometry data collection; Professor David Van Horn
(UMKC) for his guidance and use of his UV-Vis spectrometer;
and the Instrument Center of Taiwan for X-ray and mass
spectrometry data collection. Support for NMR instrumentation
has been provided by the University of Missouri Research Board,
UMKC Office of Research Administration, and the UMKC
College of Arts and Sciences.
[29] Z. Otwinowski, W. Minor, Methods Enzymol. 1997, 276, 307–326.
[30] A. L. Spek, J. Appl. Crystallog. 2003, 36, 7–13.
[31] G. M. Sheldrick, SHELXTL Version 5. Siemens Analytical X-ray
Instruments, Madison, Wisconsin, USA, 1996.
[32] P. Van der Sluis, A. L. Spek, Acta Crystallogr., Sect. A 1990, 46, 194–
201.
[33] J. Hu, D. Zhang, F. W. Harris, J. Org. Chem. 2005, 70, 707–708.
[34] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb,
J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A.
Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F.
Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O.
Kitao, H. Nakai, T. Vreven, J. A. Montgomery Jr., J. E. Peralta, F.
Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N.
Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A.
Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, N. J.
Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J.
Keywords: Acenes • Pentacene • Quinones • Reduction •
Tetracene
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10.1002/chem.201704501
Chemistry - A European Journal
FULL PAPER
Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. A. J. Austin, R.
Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G.
Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A.
D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J.
Fox, Gaussian 09, Revision E.01 Gaussian, Inc., Wallingford CT
(2013).
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10.1002/chem.201704501
Chemistry - A European Journal
FULL PAPER
FULL PAPER
The addition of several aryllithium
reagents to a variety of sterically
Robert G. Clevenger, Bharat Kumar,
Elizabeth M. Menuey, Gene-Hsiang Lee,
Dustin Patterson, and Kathleen V.
Kilway*
Ph
Ph
O
O
Ph
Ph
Ph
Ph
R
R
Ph
Ph
congested
polycyclic
quinones
followed by SnCl2-mediated reduction
allowed relatively easy access to a
large number of longitudinally twisted
acenes. This facile approach also
allows one to prepare these
remarkable hydrocarbons in gram-
scale quantities if desired.
Page No. – Page No.
A Superior Synthesis of
Longitudinally Twisted Acenes
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