Synthesis of corannulene and alkyl derivatives of corannulene

Article abstract of DOI:10.1021/ja991310o

Synthesis of corannulene and alkyl corannulene derivatives has been accomplished using solution-phase chemistry. The key step in the synthesis is the coupling of benzylic bromides of 1,6,7,10-tetraalkylfluoranthene derivatives by low-valent titanium to construct the corannulene nucleus. The use of low-valent titanium represents a viable alternative to flash vacuum pyrolysis methods previously developed. Corannulene (1), methylcorannulene (8), three different dimethylcorannulenes (2, 3, 5), two different tetramethylcorannulenes (4, 6), acecorannulylene (7), C_5h symmetric pentamethylcorannulene (9), and decamethylcorannulene (10) have been prepared using low-valent titanium carbon-carbon coupling chemistry and halogen for alkyl exchange chemistry mediated by trimethylaluminum and catalytic nickel salts.

Full text of DOI:10.1021/ja991310o

7804
J. Am. Chem. Soc. 1999, 121, 7804-7813
Synthesis of Corannulene and Alkyl Derivatives of Corannulene
T. Jon Seiders, Eric L. Elliott, Gunther H. Grube, and Jay S. Siegel*
Contribution from the Department of Chemistry, UniVersity of California, San Diego,
La Jolla, California 92093-0358
ReceiVed April 23, 1999
Abstract: Synthesis of corannulene and alkyl corannulene derivatives has been accomplished using solution-
phase chemistry. The key step in the synthesis is the coupling of benzylic bromides of 1,6,7,10-
tetraalkylfluoranthene derivatives by low-valent titanium to construct the corannulene nucleus. The use of
low-valent titanium represents a viable alternative to flash vacuum pyrolysis methods previously developed.
Corannulene (1), methylcorannulene (8), three different dimethylcorannulenes (2, 3, 5), two different tetra-
methylcorannulenes (4, 6), acecorannulylene (7), C5h symmetric pentamethylcorannulene (9), and decameth-
ylcorannulene (10) have been prepared using low-valent titanium carbon-carbon coupling chemistry and halogen
for alkyl exchange chemistry mediated by trimethylaluminum and catalytic nickel salts.
Corannulene (1), first synthesized in 1966 by Lawton and
energies. In contrast to Friedel-Crafts chemistry, syntheses
using FVP methods have succeeded in making these flanking
bonds; presumably, the activation energy is overcome by use
of high temperatures (900-1100 °C).
Barth,1,2 has received renewed attention since the discovery of
macroscopic quantities of fullerenes.3 To replace the original
17-step synthesis, Scott4-6 and our lab7,8 have developed two
different strategies for the synthesis of the corannulene nucleus,
using flash vacuum pyrolysis (FVP) and solution-phase chem-
istry, respectively. Modifications to the original FVP method
have been reported from various laboratories.9-11 Although FVP
methods provide rapid access to fullerene fragments, they lack
the ability to construct simple alkyl derivatives of corannulene
in a regioselective manner. In contrast, solution-phase chemistry
highlighted by organometallic C-C coupling methods allows
controlled synthesis of corannulene and numerous alkyl deriva-
tives (Figure 1).
An alternative disconnection, the rim bonds,14 suggests 1,6,7,-
10-tetramethylfluoranthene (11) as a precursor. In fluoranthene
11 the methyl groups are within van der Waals contacts of one
another, and the crystal structure reveals a molecular distortion
to a twisted C2 symmetric conformation.15 Initial preparation
of 1, by way of fluoranthene 11, utilized a relatively low-
temperature pyrolysis,7 and this fact motivated a reinvestigation
of solution-phase methods.
The key reaction in the solution-phase synthesis is the
coupling of the methyl carbons to form the rim bond. A variety
of methods have been developed to couple functionalized
benzylic carbons. Homocoupling of benzylic and allylic halides
with a low-valent titanium reagent16 proved to be our method
of choice, and has led to a useful solution-phase synthesis of 1.
Further retrosynthetic analysis from fluoranthene 11 reveals 3,8-
dimethylacenaphthaquinone (12) as a precursor12 that would be
readily available from 2,7-dimethylnaphthalene. Substituted
acenaphthaquinones with appropriate functionality in the 3 and
8 positions represent the keystones for the syntheses of alkyl
corannulenes in general, of which corannulene (1), methyl-
corannulene (8), three different dimethylcorannulenes (2, 3, 5),
two different tetramethylcorannulenes (4, 6), acecorannulylene
(7), C5h symmetric pentamethylcorannulene (9), and decameth-
ylcorannulene (10) have been prepared.
Corannulene and 2,5-Dimethylcorannulene. Synthesis of
1 (Scheme 1) follows a route similar to our previous work.7,15
Formaldehyde and HCl in acetic acid accomplish a chloro-
methylation in the 1 position of 2,7-dimethylnaphthalene (13).
The chlorine is displaced by cyanide, hydrolyzed to the car-
boxylic acid, and cyclized by way of the acid chloride in three
steps to yield 3,8-dimethyl-1-acenaphthenone (17).17 Ketone 17
Retrosynthetic Analysis. An obvious retrosynthetic discon-
nection of corannulene is at the flanking bonds, suggesting a
dialkylfluoranthene precursor. Such a strategy might employ
Friedel-Crafts or other π-mediated carbon-carbon bond-
forming methodology; however, attempts using these method-
ologies have been uniformly unsuccessful.12,13 The likely
downfall of such strategies is the severe distortion required to
reach the transition state, leading to unreasonably high activation
(1) Barth, W. E.; Lawton, R. G. J. Am. Chem. Soc. 1966, 88, 380-381.
(2) Lawton, R. G.; Barth, W. E. J. Am. Chem. Soc. 1971, 93, 1730-1745.
(3) Kra¨tschmer, W.; Lamb, L. D.; Fostiropoulos, K.; Huffman, D. R.
Nature 1990, 347, 354-358.
(4) Scott, L. T.; Hashemi, M. M.; Meyer, D. T.; Warren, H. B. J. Am.
Chem. Soc. 1991, 113, 7082-7084.
(5) Scott, L. T.; Hashemi, M. M.; Bratcher, M. S. J. Am. Chem. Soc.
1992, 114, 1920-1921.
(6) Scott, L. T.; Cheng, P. C.; Hashemi, M. M.; Bratcher, M. S.; Meyer,
D. T.; Warren, H. B. J. Am. Chem. Soc. 1997, 119, 10963-10968.
(7) Borchardt, A.; Fuchicello, A.; Kilway, K. V.; Baldridge, K. K.; Siegel,
J. S. J. Am. Chem. Soc. 1992, 114, 1921-1923.
(8) Seiders, T. J.; Baldridge, K. K.; Siegel, J. S. J. Am. Chem. Soc. 1996,
118, 2754-2755.
(9) Zimmermann, G.; Nuechter, U.; Hagen, S.; Nuechter, M. Tetrahedron
Lett. 1994, 35, 4747-4750.
(10) Liu, C. Z.; Rabideau, P. W. Tetrahedron Lett. 1996, 37, 3437-
3440.
(14) Precedence for rim bond formation using a carbon-carbon coupling
procedure comes from the first synthesis of corannulene.
(15) Borchardt, A.; Hardcastle, K.; Gantzel, P.; Siegel, J. S. Tetrahedron
Lett. 1993, 34, 273-276.
(16) Olah, G. A.; Prakash, G. K. S. Synthesis 1976, 607.
(17) Buu-Hoi; Cagniant, P. ReV. Sci. 1942, 80, 130.
(11) Mehta, G.; Panda, G. Tetrahedron Lett. 1997, 38, 2145-2148.
(12) Craig, J. T.; Robins, M. D. W. Aust. J. Chem. 1968, 21, 2237-
2245.
(13) Davy, J. R.; Iskander, M. N.; Reiss, J. A. Tetrahedron Lett. 1978,
42, 4085-4088.
10.1021/ja991310o CCC: $18.00 © 1999 American Chemical Society
Published on Web 08/17/1999

Synthesis of Corannulene and Its Alkyl DeriVatiVes
J. Am. Chem. Soc., Vol. 121, No. 34, 1999 7805
Figure 1. Derivatives of corannulene (1).
A slightly modified method of this corannulene synthesis
leads to 2,5-dimethylcorannulene (2) (Scheme 1).8 At the
cyclopentadienone precursor stage, 4-heptanone is used instead
of 3-pentanone. In addition, because the resulting 7,10-diethyl-
1,6-dimethylfluoranthene (19) does not form an octabromide,
the reductive coupling (TiCl3-LiAlH4) is performed on the
tetrabromide 20 followed by a 2,3-dichloro-5,6-dicyanoquinone
(DDQ) oxidation to yield corannulene 2.
1,6-Dimethylcorannulene (3) and 1,2,5,6-Tetramethyl-
corannulene (4). The synthesis of 1,6-dimethylcorannulene (3)
(Scheme 2) starts from 2,7-dibromonaphthalene (21).18,19 Nickel-
catalyzed Kumada coupling20 of the aryl bromides with ethyl-
magnesium chloride yields 2,7-diethylnaphthalene. Synthesis of
1,6-diethyl-7,10-dimethylfluoranthene (27) from naphthalene 21
proceeds in a manner analogous to the synthesis of fluoranthenes
11 and 19 shown in Scheme 1. As with fluoranthene 19,
fluoranthene 27 is brominated with NBS under irradiation with
light to yield the tetrabromide 28, which is coupled by the
improved low-valent titanium reagent (TiCl4/Zn-Cu) to yield
1,6-dimethyltetrahydrocorannulene. Dehydrogenation with DDQ
yields corannulene 3.
Synthesis of 1,2,5,6-tetramethylcorannulene (4) (Scheme 2)
draws from the syntheses of corannulenes 2 and 3. 4-Heptanone
is used in the two-step conversion of 3,8-diethylacenaph-
thaquinone (26) to 1,6,7,10-tetraethylfluoranthene (29). Bromi-
nation of fluoranthene 29 with NBS under irradiation with light
yields the tetrabromide 30, which is coupled by the low-valent
titanium reagent followed by dehydrogenation with DDQ to
yield corannulene 4. Although only run once, the yield of this
dehydrogenation (6%) is notably lower than that seen in previous
dehydrogenations, and deserves further investigation.
2,3-Dichlorocorannulene, 2,7-Dimethyl-4,5-dichlorocoran-
nulene, and Acecorannulylene. Whereas the methods described
above give relatively fast and efficient access to several
corannulene derivatives, synthesis of derivatives with substit-
uents in the peri positions would not be possible. An alternative
route was therefore developed.
Figure 2. Retrosynthetic disconnections of corannulene.
is oxidized with selenium dioxide in dioxane/water to yield
diketone 12. Diketone 12 is condensed with 3-pentanone in
methanolic potassium hydroxide to construct the cyclopenta-
dienone precursor. The cyclopentadienone is generated in acetic
anhydride and trapped by a Diels-Alder reaction with norbor-
nadiene, an acetylene equivalent. A cascade of retrocycloaddi-
tions follows to release cyclopentadiene and carbon monoxide,
and affords fluoranthene 11. Fluoranthene 11 is brominated with
N-bromosuccinimide (NBS) under irradiation with light to yield
1,6,7,10-tetrakis(dibromomethyl)fluoranthene (18). In early
work, octabromide 18 was reacted with the low-valent titanium
reagent generated from TiCl3 and LiAlH4 to afford 1 in 33%
yield. Later procedures, using TiCl4 and Zn-Cu couple, increase
the yield of 1 to 80%.
(18) Katz, T. J.; Sudhakar, A.; Teasley, M. F.; Gilbert, A. M.; Geiger,
W. E.; Robben, M. P.; Wuensh, M.; Ward, M. D. J. Am. Chem. Soc. 1993,
115, 3182-3198.
(19) Schaefer, J. P.; Higgins, J.; Shenoy, P. K. Org. Synth. 1973, 5, 142-
145.
(20) Tamao, K.; Sumitani, K.; Kumada, M. J. Am. Chem. Soc. 1972,
94, 4374-4376.

7806 J. Am. Chem. Soc., Vol. 121, No. 34, 1999
Seiders et al.
Scheme 1
Scheme 2

Synthesis of Corannulene and Its Alkyl DeriVatiVes
J. Am. Chem. Soc., Vol. 121, No. 34, 1999 7807
Scheme 3
t
The synthesis of derivatives with substitution in the peri
positions (Scheme 3) begins with chlorination of acenaphthene
(31) by sulfuryl chloride in nitrobenzene with a catalytic amount
of aluminum chloride,21 followed by electrophilic bromination
with bromine and ferric chloride or ferric bromide in methylene
chloride. The oxidation of 5,6-dichloro-3,8-dibromoacenaph-
thene (33) is achieved by chromium trioxide in acetic anhy-
dride22 to yield a synthetically versatile acenaphthaquinone
derivative (34). The standard procedure for converting acenaph-
thaquinones to fluoranthenes (vida supra) is effected with
3-pentanone to yield 1,6-dibromo-3,4-dichloro-7,10-dimeth-
ylfluoranthene (35). Palladium-catalyzed reaction of trimethyl-
aluminum with the bromides of fluoranthene 35 yields 3,4-
dichloro-1,6,7,10-tetramethylfluoranthene (36).23 Bromination
with NBS gives the octabromide 37 as a sparingly soluble
material, which is coupled by the improved low-valent titanium
reagent to afford 2,3-dichlorocorannulene (38).
2,7-Dimethyl-4,5-dichlorocorannulene (41) is synthesized
(Scheme 3) by palladium-catalyzed replacement of the bromides
of fluoranthene 35 with triethyl aluminum to yield 1,6-diethyl-
7,10-dimethyl-3,4-dichlorofluoranthene (39). By analogy to
corannulene 3, corannulene 41 is synthesized by bromination
of fluoranthene 39 with NBS under irradiation of light to the
tetrabromide 40, followed by low-valent titanium coupling and
DDQ dehydrogenation.
Acecorannulylene (7), previously synthesized by a FVP
route,24,25 is significantly more curved than 1.26 A slight
modification of the route to corannulenes 38 and 41 allowed
for the synthesis of corannulene 7. The synthesis from 7
(Scheme 4) involves exhaustive methylation of fluoranthene 35
with trimethylaluminum and a nickel(0) catalyst to afford
1,3,4,6,7,10-hexamethylfluoranthene (42). Fluoranthene 42 is
brominated with excess NBS under irradiation with light to yield
the dodecabromide 43, which is coupled by the improved low-
valent titanium reagent (TiCl4/Zn-Cu) to yield 7 in somewhat
low yield (20%).
Alkylcorannulenes from Halocorannulenes. A variety of
halocorannulenes are now available, for example compounds
38 and 41, as well as bromocorannulene (44),27 pentachloroc-
orannulene (45),27,28 and decachlorocorannulene (46).27-29 Each
of these can be conveniently converted to their corresponding
alkyl corannulene derivatives (5, 6, 8, 9, 10) by a general
coupling procedure that uses alkyl aluminum reagents in the
presence of a catalytic amount of nickel(0) (Scheme 5). An
important variable in this methodology is the solvent. Whereas
this method works well with most halocorannulenes in THF or
(24) Abdourazak, A. H.; Sygula, A.; Rabideau, P. W. J. Am. Chem. Soc.
1993, 115, 3010-3011.
(25) Sygula, A.; Abdourazak, A. H.; Rabideau, P. W. J. Am. Chem. Soc.
1996, 118, 339-343.
(26) Sygula, A.; Folsom, H. E.; Sygula, R.; Abdourazak, A. H.;
Marcinow, Z.; Fronczek, F. R.; Rabideau, P. W. J. Chem. Soc., Chem.
Commun. 1994, 2571-2572.
(21) Miyamoto, H.; Yui, K.; Aso, Y.; Otsubo, T.; Ogura, F. Tetrahedron
Lett. 1986, 27, 2011-2014.
(22) March, J. AdVanced Organic Chemistry, 4th ed.; John Wiley and
Sons: New York, 1992.
(27) Cheng, P. C. Ph.D. Dissertation, Boston College: Boston, 1996;
pp 212.
(23) Unlike 2,7-dibromonaphthalene, reaction of 35 with grignard
reagents in the presence of nickel gave mostly protonation, presumably
exchange to an aromatic grignard followed by protonation upon workup.
(28) Scott, L. T. Pure Appl. Chem. 1996, 68, 291-300.
(29) Huang, R.; Huang, W.; Wang, Y.; Tang, Z.; Zheng, L. J. Am. Chem.
Soc. 1997, 119, 5954-5955.

7808 J. Am. Chem. Soc., Vol. 121, No. 34, 1999
Seiders et al.
Table 1. Ultraviolet, Fluorescence, Electrochemical Reduction
Scheme 4
Potentials, and Ionization Potentials for Corannulene Derivatives
UVa fluorescence (λ)a
compd λmax ꢀ (×104) excitation emission E1/2c (V) IPf (eV)
1
196
220
251
286
198
222
256
289
199
226
262
293
198
222
254
289
200
225
258
292
200
226
260
295
204b
234b
272b
304b
7.8
5.4
7.8
4.2
5.1
3.9
4.6
3.0
2.9
2.3
2.3
2.1
5.4
4.0
5.7
3.1
1.1
0.8
1.2
0.7
2.3
1.6
2.3
1.4
0.7
0.5
0.6
0.4
247, 286
258, 290
264, 294
256, 290
260, 294
261, 297
421
425
429
420
426
431
-2.23
-2.84
-1.87d
-2.47d
-2.29
-2.94
8.05
7.72
7.56
7.79
7.62
7.71
7.19
3
4
-2.32
-2.86
5
-2.30
-2.90
6
-2.35
-2.87
Scheme 5
9
-2.38
-2.93
10
-2.48e
>-3.00e
a In acetonitrile. b In cyclohexane. c 0.1 M tetrabutylammonium
hexafluorophosphate in acetonitrile vs Ag/AgNO3 in acetonitrile. d 0.1
M tetrabutylammonium perchlorate in acetonitrile vs aqueous Ag/AgCl
(literature values under the same conditions -1.88 and -2.46 V, ref
29). e 0.1 M tetrabutylammonium hexafluorophosphate in N,N-di-
f
methylformamide vs Ag/AgNO3. Calculated (RHF/DZV(2d,p)//B3LYP/
cc-pVDZ) using Koopmans’ theorem.34
reduction state up to the tetraanion, which forms a sandwich
31-33
complex of (14-)2Li+
.
8
No evidence for aggregation has
been observed for 1-, 12-, or 13-. The relative ease of reduction
of 1 piqued our interest in the sensitivity of the reduction
potential to alkyl substitution. The addition of methyl groups
to the corannulene nucleus shifted the electrochemical reduction
for the monoanion and dianion to a more negative potential and
is consistent with an increasing electron density in the coran-
nulene nucleus. Comparing 1 and 10, a difference of 250 mV
for the monoanion and at least 160 mV for the dianion is
measured.
DME, the sparingly soluble corannulene 46 reacts only in
dimethylethylene urea (DMEU).
Whereas the electrochemical reduction, an estimate of the
electron affinity, was reversible, the oxidation was irreversible.
To obtain estimates for the oxidation, the ionization potentials
were calculated using Koopmans’ theorem at the RHF/DZV-
(2d,p)//B3LYP/cc-pVDZ level of theory.34 Upon addition of
methyl groups to the corannulene nucleus, the ionization poten-
tials diminished from 8.05 eV for 1 to 7.19 eV for 10. Like the
electrochemical reduction, the shift to lower ionization potential
is consistent with an increase in electron density in the coran-
nulene nucleus as the number of methyl substituents increases.
Physical Properties. Having access to corannulene deriva-
tives with controlled substitution allows a systematic investiga-
tion of the effects of substitution on the spectroscopic and
electrochemical properties of the corannulene nucleus (Table
1). The addition of methyl groups to the corannulene nucleus
shifts the UV spectra to longer wavelengths for each of the four
peaks. With red shifts of only 8, 14, 21, and 18 nm between 1
and 10 for the individual peaks, the UV spectra seem relatively
insensitive to methyl substitution. Fluorescence spectra also
reflect relative wavelength insensitivity to methyl substitution.
The shifts in the UV and fluorescence spectra, although small,
are in the expected direction for methyl acting as a weak electron
donor.
(30) Janata, J.; Gendell, J.; Ling, C.; Barth, W.; Backes, L.; Mark, H.
B.; Lawton, R. G. J. Am. Chem. Soc. 1967, 89, 3058.
(31) Ayalon, A.; Rabinovitz, M.; Cheng, P. C.; Scott, L. T. Angew.
Chem., Int. Ed. Engl. 1992, 31, 1636-1637.
(32) Ayalon, A.; Sygula, A.; Cheng, P. C.; Rabinovitz, M.; Rabideau,
P. W.; Scott, L. T. Science 1994, 265, 1065-1067.
Originally, Lawton observed the electrochemical reduction
of 1 to the anion and dianion.30 Subsequent studies have found
the reduction of 1 with lithium to proceed through each discrete
(33) Baumgarten, M.; Gherghel, L.; Wagner, M.; Weitz, A.; Rabinovitz,
M.; Cheng, P. C.; Scott, L. T. J. Am. Chem. Soc. 1995, 117, 6254-6257.
(34) Baldridge, K. K. Unpublished results.

Synthesis of Corannulene and Its Alkyl DeriVatiVes
J. Am. Chem. Soc., Vol. 121, No. 34, 1999 7809
10H). 13C NMR (125 MHz, CDCl3): δ 127.2, 130.8, 135.8. HRMS
m/z: found 250.0779; calcd (C20H10) 250.0783.
Substitution of the rim of corannulene expands the scope of
this class of compounds. In particular, alkyl substitution can
effect bowl depth, crystal packing, HOMO-LUMO gap, and
inversion dynamics. Alkyl corannulenes can be used as building
blocks for larger structures, such as cyclophanes, dendrimers,
and liquid crystals. Such constructs hold the promise of
developing selective fullerene hosts, electron-transport materials,
and novel polymers.
1,6-Dimethyl-7,10-diethylfluoranthene (19). A 20% solution of
potassium hydroxide in methanol (100 mL) was added to a solution of
3,8-dimethylacenaphthenequinone (12) (9.25 g, 44 mmol) and 4-hep-
tanone (25 mL) in methanol (250 mL). The solution was stirred at
ambient temperature for 1 h, diluted with water (250 mL), and extracted
with dichloromethane (300 mL). The organic layer was washed once
with 10% aqueous hydrochloric acid (100 mL) and three times with
water (250 mL), dried with magnesium sulfate, filtered, and evaporated.
The crude oil was transferred to a 200 mL sealable reaction vessel and
2,5-norbornadiene (30 mL) and acetic anhydride (100 mL) were added.
The vessel was sealed and placed in an oil bath at 140 °C for 3 days.
The reaction was cooled to ambient temperature, diluted with benzene
(100 mL), neutralized with 10% aqueous sodium hydroxide (100 mL),
and extracted 3 times with water (100 mL). The organic layer was
dried with magnesium sulfate, filtered, and evaporated to yield a dark
brown oil. The oil was purified by column chromatography on silica
gel with cyclohexane as the eluent to yield a golden yellow oil that
solidifies upon standing (6.00 g, 48% 2 steps). Mp 46-47 °C. 1H NMR
(CDCl3, 500 MHz): δ 1.30 (t, 3J ) 7.0 Hz, 3H), 2.79 (s, 3H), 3.11 (q,
Experimental Section
General Data. 1H- and 13C NMR spectra were recorded on Varian
(Mercury 300 MHz/400 MHz; Unity 500 MHz) or General Electric
(QE 300 MHz) spectrometers with tetramethylsilane as the internal
standard. Low-resolution mass spectral analyses were performed in the
EI-mode on a HP GC/MS 59970 spectrometer. High-resolution mass
spectra were obtained from the University of California Riverside mass
spectrometry facility in the FAB or DEI mode. UV/vis spectra were
recorded on a Perkin-Elmer Lambda 6 UV/vis spectrophotometer.
Infrared spectra were recorded on a Perkin-Elmer 1420 IR spectro-
photometer. Fluorescence spectra were recorded on a Photon Technol-
ogy International fluorimeter. Cyclic voltammograms were recorded
on a Bioanalytical Systems CV-50W electrochemical apparatus. Melting
points were obtained on a Mel-Temp melting point apparatus and are
reported uncorrected.
3
3
3J ) 7.0 Hz, 2H), 7.26 (s, 2H), 7.35 (d, J ) 8.0 Hz, 2H), 7.66 (d, J
) 8.0, 2H). 13C NMR (CDCl3, 125 MHz): δ 15.49, 24.54, 28.41,
125.98, 126.62, 128.51, 131.82, 131.93, 133.61, 135.10, 136.49, 139.19.
HRMS m/z: found 286.1718; calcd (C22H22) 286.1722.
1,6-Bis(bromomethyl)-7,10-bis(1-bromoethyl)fluoranthene (20)
(Mixture of Diastereomers). 1,6-Dimethyl-7,10-diethylfluoranthene
(19) (0.81 g, 2.83 mmol), N-bromosuccinimide (4.04 g, 22.68 mmol),
and benzoyl peroxide (10 mg) in carbon tetrachloride (250 mL) were
irradiated with incandescent light and refluxed for 6 h. The solution
was extracted 3 times with water (200 mL), dried with magnesium
sulfate, filtered, and evaporated to yield a golden solid (2.15 g,
quantitative). 1H NMR (CDCl3, 300 MHz): δ (ppm) 2.0-2.2 (m, 6H),
4.6-5.2 (m, 4H), 5.8-6.1 (m, 2H), 7.7-8.0 (m, 6H).
Techniques and Materials. All experiments were carried out under
argon in freshly distilled solvents under anhydrous conditions unless
otherwise noted. Commercial chemicals were used as supplied. Tet-
rahydrofuran (THF), toluene, and dimethoxyethane (DME) were
distilled from sodium/benzophenone; dichloromethane was distilled
from calcium hydride; carbon tetrachloride was distilled from phos-
phorus pentoxide; nitrobenzene was dried with calcium chloride; and
dimethylethyleneurea (DMEU) was dried with 4 Å molecular sieves.
Yields refer to chromatographically and spectroscopically (1H NMR)
homogeneous materials, unless otherwise stated. Characterization of
all new compounds was done by 1H and 13C NMR as well as by mass
spectroscopy. Fluoranthenes containing benzylic bromides were often
obtained as mixtures of diastereomers and not purified because of their
poor solubility. All tetrahydrocorannulenes were obtained as mixtures
of cis and trans isomers; in addition, they already contained the
corresponding corannulenes and dihydrocorannulenes and were used
as crude materials for further oxidation. When such compounds were
isolated and used as mixtures, characterization was restricted to 1H NMR
spectroscopy. All compounds mentioned in Scheme 1 toward the
synthesis of 18 have been reported previously.7
2,5-Dimethyl-1,2,5,6-tetrahydrocorannulene (Mixture of Cis and
Trans Isomers). Titanium trichloride (1.54 g, 9.97 mmol) and lithium
aluminum hydride (0.190 g, 4.98 mmol) in THF (200 mL) were refluxed
for 30 min yielding a black suspension. A solution of 1,6-bis-
(bromomethyl)-7,10-bis(1-bromoethyl)fluoranthene (20) (3.00 g, 4.98
mmol) in THF (100 mL) was added to the refluxing black suspension
over a period of 12 h and refluxed an additional 3 h after the addition
was complete. The reaction was diluted with benzene (100 mL),
extracted 3 times with water (250 mL), dried with magnesium sulfate,
filtered, and evaporated. The residue was purified by column chroma-
tography (cyclohexane/benzene 9:1) to yield a pale yellow solid (0.45
g, 33%). 1H NMR (CDCl3, 500 MHz): δ (ppm) 1.49 (d, 3J ) 6.9 Hz,
6H), 1.57 (d, 3J ) 6.3 Hz, 6H), 2.49-3.85 (m, 12H), 7.0-7.2 (m, 2H),
7.00 (s, 2H), 7.02 (s, 2H), 7.14 (d, 3J ) 8.4 Hz, 2H), 7.15 (d, 3J ) 8.4
Preparative column chromatography was performed with silica gel
(230-425 mesh) from Fisher Scientific Company. Thin-layer chro-
matography (TLC) was performed on aluminum backed silica gel 60
F254 plates from Alltech.
3
Hz, 2H), 7.57 (d, J ) 8.4 Hz, 4H).
2,5-Dimethylcorannulene (2). 2,5-Dimethyl-1,2,5,6-tetrahydro-
corannulene (0.40 g, 1.42 mmol) and 2,3-dichloro-5,6-dicyanoquinone
(0.81 g, 3.55 mmol) in benzene (125 mL) were refluxed for 1 h. The
solution was diluted with cyclohexane (125 mL) and filtered through
a plug of silica gel, then the plug was washed with additional
cyclohexane (125 mL). The solvent was evaporated to yield a pale
1,6,7,10-Tetrakis(dibromomethyl)fluoranthene (18). 1,6,7,10-Tet-
ramethylfluoranthene (3.97 g, 15.4 mmol), N-bromosuccinimide (27.4
g, 154 mmol), and benzoyl peroxide (10 mg) in dry carbon tetrachloride
(250 mL) were irradiated with incandescent light and refluxed for 15
h. The solvent was distilled off and the solid dissolved in dichlo-
romethane (100 mL), washed 3 times with water (100 mL), dried over
magnesium sulfate, filtered, and evaporated to yield a golden solid
(13.65 g, quantitative). Mp >300 °C. 1H NMR (500 MHz, CDCl3): δ
1
yellow solid (0.28 g, 70%). Mp 189-193 °C. H NMR (CDCl3, 500
MHz): δ (ppm) 2.83 (s, 6H), 7.55 (s, 2H), 7.68 (d, 3J ) 8.5 Hz, 2H),
3
7.74 (d, J ) 8.5, 2H), 7.94 (s, 2H). 13C NMR (CDCl3, 125 MHz): δ
3
7.10 (s, 2H), 7.22 (s, 2H), 7.99 (d, J ) 8.5 Hz, 2H), 8.22 (s, 2H),
3
8.28 (d, J ) 8.5 Hz, 2H). 13C NMR (100 MHz, CDCl3): δ (ppm)
18.74, 124.83, 125.79, 126.31, 127.12, 129.97, 130.66, 131.56, 134.93,
135.50, 136.04, 136.66. HRMS-FAB+ [M + Cs]+: found 411.0150,
calcd (C22H14) 411.0166.
38.5, 39.0, 127.6, 129.1, 130.1, 130.2, 131.5, 131.8, 132.3, 136.5, 137.9.
HRMS m/z: found 889.4202; calcd (C20H10Br8) 889.4168.
Corannulene (1). Zinc-copper couple (28.7 g, 442 mmol) and
titanium tetrachloride (12.2 mL, 110 mmol) in DME (250 mL) were
refluxed for 2 h yielding a black suspension. A solution of 1,6,7,10-
tetrakis(dibromomethyl)fluoranthene (18) (6.73 g, 7.56 mmol) in DME
(100 mL) was added to the refluxing suspension over a period of 2
days. The mixture was refluxed an additional 3 h, diluted with
cyclohexane (250 mL), and filtered through a plug of silica gel; the
plug was washed with additional benzene (500 mL). The solvent was
evaporated to yield a pale yellow solid (1.50 g, 80%). Mp 264-265
°C (lit. mp 268-269 °C).2 1H NMR (500 MHz, CDCl3): δ 7.82 (s,
2,7-Diethylnaphthalene. Ethylmagnesium chloride 25% in THF
(58.7 h, 228 mL, 660 mmol) was added dropwise to a solution of 2,7-
dibromonaphthalene18 (90.0 g, 315 mmol) and 1,3-bis(diphenylphos-
phino)nickel(II) chloride (1.71 g, 3.15 mmol) in THF (350 mL) at 0
°C. The mixture was refluxed for 30 min, cooled to ambient temper-
ature, and quenched carefully by slow addition of water (50 mL).
Benzene (100 mL) was added and the organic layer was washed 3 times
with water (500 mL), dried with magnesium sulfate, filtered, and
evaporated to yield a tan solid (58.0 g, quantitative). Mp 38-40 °C.
1H NMR (CDCl3, 300 MHz): δ (ppm) 1.30 (t, 3J ) 7.5 Hz, 6H), 2.78

7810 J. Am. Chem. Soc., Vol. 121, No. 34, 1999
Seiders et al.
1
3
(q, 3J ) 7.5 Hz, 4H), 7.26 (d, 3J ) 8.4 Hz, 2H), 7.55 (s, 2H), 7.71 (d,
3J ) 8.4 Hz, 2H). 13C NMR (CDCl3, 300 MHz): δ (ppm)15.7, 29.1,
125.0, 126.1, 127.4, 130.3, 133.8, 141.6. HRMS m/z: found 184.1256;
calcd (C14H16) 184.1252.
131-133 °C. H NMR (300 MHz, CDCl3): δ 1.35 (t, J ) 7.5 Hz,
3
3
3
6H), 3.29 (q, J ) 7.5 Hz, 4H), 7.56 (d, J ) 8.4 Hz, 2H), 8.08 (d, J
) 8.4 Hz, 2H). 13C NMR (125 MHz, CDCl3): δ (ppm) 15.1, 25.1,
124.0, 127.9, 129.2, 132.3, 144.3, 147.7, 188.8. IR (KBr): 1710 cm-1
(CdO). HRMS m/z: found 238.0993; calcd (C16H14O2) 238.0994.
1,6-Diethyl-7,10-dimethylfluoranthene (27). A 20% solution of
potassium hydroxide in methanol (100 mL) was added to a solution of
3,8-diethylacenaphthenequinone (26) (18.0 g, 75.6 mmol) and 3-pen-
tanone (50 mL) in methanol (500 mL). The mixture was stirred at
ambient temperature for 1 h, diluted with water (500 mL), and extracted
with dichloromethane (400 mL). The organic layer was washed once
with 10% aqueous hydrochloric acid (100 mL) and 3 times with water
(250 mL), dried with magnesium sulfate, filtered, and evaporated. The
crude oil was transferred to a 200 mL sealable reaction vessel and 2,5-
norbornadiene (50 mL) and acetic anhydride (100 mL) were added.
The vessel was sealed and placed in an oil bath at 130 °C for 4 days.
The reaction was cooled to ambient temperature, diluted with benzene
(100 mL), and extracted 3 times with 10% sodium hydroxide (100 mL)
and then water (100 mL). The organic layer was dried with magnesium
sulfate, filtered, and evaporated to yield a dark brown oil. The oil was
purified by flash chromatography with cyclohexane as the eluent to
yield a golden yellow oil that solidifies upon standing (9.7 g, 46%, 2
steps). Mp 36-38 °C. 1H NMR (500 MHz, CDCl3) δ 1.28 (t, 3J ) 7.5
Hz, 6H), 2.67 (s, 6H), 3.12 (q, 3J ) 7.5 Hz, 4H), 7.06 (s, 2H), 7.39 (d,
1-(Chloromethyl)-2,7-diethylnaphthalene (22). 2,7-Diethylnaph-
thalene (41.6 g, 226 mmol), paraformaldehyde (8.1 g, 270 mmol), and
a solution of hydrogen chloride (16 g, 450 mmol) in acetic acid (125
mL) (prepared by bubbling hydrogen chloride through acetic acid) in
a sealable reaction vessel were heated and stirred in an oil bath at 50
°C for 20 h. The reaction was neutralized with an aqueous solution of
sodium bicarbonate, extracted with benzene (100 mL), washed 3 times
with water (125 mL), dried with magnesium sulfate, filtered, and
1
evaporated to yield a brown oil (49.9 g, 95%). H NMR (300 MHz,
CDCl3): δ (ppm) 1.29 (t, 3J ) 7.5 Hz, 3H), 1.33 (t, 3J ) 7.5 Hz, 3H),
2.83 (q, 3J ) 7.5 Hz, 2H), 2.87 (q, 3J ) 7.5 Hz, 2H), 5.07 (s, 2H), 7.23
(d, 3J ) 8.4 Hz, 1H), 7.29 (d, 3J ) 7.4 Hz, 1H), 7.69 (d, 3J ) 8.1 Hz,
3
1H), 7.70 (d, J ) 8.1 Hz, 1H), 7.87 (s, 1H). 13C NMR (125 MHz,
CDCl3): δ (ppm) 15.6, 15.8, 26.6, 29.8, 39.6, 121.3, 126.3, 126.8, 128.6,
128.7, 129.3, 131.0, 132.1, 141.6, 142.9. MS m/z (rel intensity): 234
(15, M + 2), 232 (40, M+), 197 (100, M - Cl+).
1-(Cyanomethyl)-2,7-diethylnaphthalene (23). 1-(Chloromethyl)-
2,7-diethylnaphthalene (22) (49.9 g, 214 mmol) and potassium cyanide
(28.0 g, 429 mmol) in a mixture of water (25 mL) and acetone (250
mL) were refluxed for 18 h. The solution was diluted with benzene
(100 mL), washed 3 times with water (100 mL), dried with magnesium
sulfate, filtered, and evaporated to yield a brown oil (46.6 g, 97%). 1H
NMR (300 MHz, CDCl3): δ (ppm) 1.27 (t, 3J ) 7.5 Hz, 3H), 1.33 (t,
3J ) 7.5 Hz, 3H), 2.82 (q, 3J ) 7.5 Hz, 2H), 2.84 (q, 3J ) 7.5 Hz, 2H),
4.02 (s, 2H), 7.24 (d, 3J ) 8.4 Hz, 1H), 7.33 (d, 3J ) 8.1 Hz, 1H), 7.70
3J ) 7.5 Hz, 2H), 7.66 (d, J ) 7.5 Hz, 2H). 13C NMR (125 MHz,
CDCl3): δ (ppm) 15.9, 23.7, 29.3, 126.5, 126.7, 129.8, 129.9, 130.5,
133.8, 134.0, 138.8, 140.1. HRMS m/z: found 286.1713; calcd (C22H22)
286.1722.
3
1,6-Bis(1-bromoethyl)-7,10-bis(bromomethyl)fluoranthene (28)
(Mixture of Diastereomers). 1,6-Diethyl-7,10-dimethylfluoranthene
(27) (3.27 g, 11.4 mmol), N-bromosuccinimide (8.14 g, 45.7 mmol),
and benzoyl peroxide (10 mg) in carbon tetrachloride (250 mL) were
irradiated with incandescent light and refluxed for 3 h. The solution
was extracted 3 times with water (200 mL), dried over magnesium
sulfate, filtered, and evaporated to yield a golden solid (6.89 g,
3
3
(s, 1H), 7.71 (d, J ) 8.1 Hz, 1H), 7.73 (d, J ) 8.4 Hz, 1H). 13C
NMR (125 MHz, CDCl3): δ (ppm) 15.3, 15.5, 16.2, 27.1, 29.4, 118.0,
120.6, 121.9, 126.5, 126.7, 128.7, 128.8, 130.9, 131.8, 140.6, 143.3.
MS m/z (rel intensity): 223 (100, M+), 208 (95, M - CH3+).
1-(Carboxymethyl)-2,7-diethylnaphthalene (24). 1-(Cyanomethyl)-
2,7-diethylnaphthalene (23) (46.6 g, 208 mmol), concentrated sulfuric
acid (80 mL), acetic acid (150 mL),and water (150 mL) were refluxed
for 1 day. The solution was neutralized with 10% aqueous sodium
hydroxide, extracted with dichloromethane (500 mL), washed 3 times
with water (100 mL), dried with magnesium sulfate, filtered, and
evaporated to yield a light yellow solid (41.0 g, 80%). Mp 78-80 °C.
1H NMR (300 MHz, CDCl3): δ (ppm) 1.24 (t, 3J ) 7.5 Hz, 3H), 1.28
1
3
quantitative). H NMR (300 MHz, CDCl3): δ 2.04 (d, J ) 6.6 Hz,
6H), 2.13 (d, 3J ) 6.6 Hz, 6H), 4.73 (d, 3J ) 11.1 Hz, 2H), 4.86 (d, 3J
3
3
) 11.1 Hz, 2H), 4.96 (d, J ) 11.4 Hz, 2H), 5.00 (d, J ) 11.1 Hz,
3
3
2H), 5.87 (q, J ) 6.6 Hz, 2H), 6.02 (q, J ) 6.9 Hz, 2H), 7.64 (s,
3
3
2H), 7.66 (s, 2H), 7.88 (d, J ) 8.4 Hz, 2H), 7.89 (d, J ) 8.7 Hz,
3
2H), 7.97 (d, J ) 8.7 Hz, 4H).
3
3
3
(t, J ) 7.5 Hz, 3H), 2.79 (q, J ) 7.5 Hz, 2H), 2.83 (q, J ) 7.5 Hz,
1,6-Dimethyl-1,2,5,6-tetrahydrocorannulene (Mixture of Cis/
Trans Isomers). Titanium trichloride(DME)1.5 (8.79 g, 30.4 mmol) and
zinc-copper couple (6.26 g, 96.3 mmol) in DME (400 mL) were
refluxed for 2 h yielding a black suspension. A solution of 1,6-bis(1-
bromoethyl)-7,10-bis(bromomethyl)fluoranthene (28) (3.00 g, 4.98
mmol) in 1,2-dimethoxyethane (150 mL) was added to the refluxing
black suspension over a period of 3 days and the solution was refluxed
an additional 3 h after the addition was complete. The reaction was
diluted with cyclohexane (400 mL) and filtered through a plug of silica
gel, then the plug was washed with additional cyclohexane (500 mL).
3
3
2H), 4.13 (s, 2H), 7.27 (d, J ) 8.4 Hz, 1H), 7.28 (d, J ) 8.4 Hz,
3
3
1H), 7.68 (d, J ) 7.8 Hz, 1H), 7.71 (d, J ) 7.8 Hz, 1H), 7.72 (s,
1H), 10.53 (bs, 1H). 13C NMR (125 MHz, CDCl3): δ (ppm) 15.4, 15.6,
27.0, 29.5, 33.7, 121.5, 125.7, 126.1, 126.8, 128.0, 128.6, 130.9, 132.9,
141.0, 142.6, 178.1. HRMS m/z: found 242.1301; calcd (C16H18O2)
242.1307.
3,8-Diethylacenaphthenone (25). 1-(Carboxymethyl)-2,7-diethyl-
naphthalene (24) (30.5 g, 126 mmol) and thionyl chloride (15.8 g, 133
mmol) in dichloromethane (600 mL) were refluxed for 45 min.
Aluminum chloride (16.8 g, 126 mmol) was added slowly and the
resulting mixture was stirred for an additional 30 min. The solution
was carefully quenched by slow addition of water (100 mL), washed
3 times with water (500 mL), dried with magnesium sulfate, filtered,
and evaporated to yield a light brown solid (26.8 g, 95%). Mp 71-73
1
The solvent was evaporated to yield a yellow solid (1.58 g, 78%). H
3
3
NMR (300 MHz, CDCl3): δ 1.42 (d, J ) 6.9 Hz, 6H), 1.57 (d, J )
6.9 Hz, 6H), 2.7-3.6 (m, 12H), 6.9 (s, 4H), 7.27 (d, J ) 8.7 4H), 7.61
(d, J ) 8.7, 4H).
1,6-Dimethylcorannulene (3). 1,6-Dimethyl-1,2,5,6-tetrahydro-
corannulene (2.13 g, 7.55 mmol) and 2,3-dichloro-5,6-dicyanoquinone
(3.43 g, 15.1 mmol) in benzene (250 mL) were stirred at ambient
temperature for 8 h. The solution was diluted with cyclohexane (250
mL) and filtered through a plug of silica gel, then the plug was washed
with additional cyclohexane (250 mL). The solvent was evaporated to
1
3
°C. H NMR (500 MHz, CDCl3): δ (ppm) 1.30 (t, J ) 7.5 Hz, 3H),
1.31 (t, 3J ) 7.5 Hz, 3H), 2.78 (q, 3J ) 7.5 Hz, 2H), 3.24 (q, 3J ) 7.5
Hz, 2H), 3.70 (s, 2H), 7.39 (d, 3J ) 8.5 Hz, 1H), 7.45 (d, 3J ) 8.5 Hz,
1H), 7.72 (d, J ) 8.5 Hz, 1H), 7.93 (d, J ) 8.5 Hz, 1H). 13C NMR
(125 MHz, CDCl3): δ (ppm) 14.9, 15.1, 24.7, 26.4, 41.0, 124.3, 127.9,
128.5, 128.8, 130.3, 131.0, 131.2, 136.7, 143.8, 143.9, 203.9. MS m/z
(rel intensity): 224 (100, M+), 209 (80, M - CH3+).
3
3
1
yield a pale yellow solid (1.30 g, 61%). Mp 206-208 °C. H NMR
(500 MHz, CDCl3): δ 2.81 (s, 6H), 7.54 (s, 2H), 7.68 (s, 2H), 7.83 (d,
3J ) 9.0 Hz, 2H), 7.91 (d, J ) 9.0 Hz, 2H). 13C NMR (125 MHz,
3
3,8-Diethylacenaphthenequinone (26). 3,8-Diethylacenaphthenone
(25) (26.8 g, 120 mmol) and selenium dioxide (27.9 g, 251 mmol) in
a mixture of 1,4-dioxane (500 mL) and water (20 mL) were heated to
70 °C for 5 h. The solution was cooled to ambient temperature, filtered,
and diluted with benzene (200 mL). The organic layer was washed 3
times with water (250 mL), dried with magnesium sulfate, filtered,
evaporated, and filtered through a plug of silica gel with dichlo-
romethane as the eluent to yield an orange solid (17.0 g, 61%). Mp
CDCl3): δ 18.7, 124.9, 125.8, 126.8, 126.9, 130.2, 131.0, 131.1, 134.9,
135.4, 135.9, 136.3. HRMS m/z: found 278.1094; calcd (C22H14)
278.1096.
1,6,7,10-Tetraethylfluoranthene (29). A 20% solution of potassium
hydroxide in methanol (100 mL) was added to a solution of 3,8-
diethylacenaphthenequinone (26) (5.0 g, 21 mmol) and 4-heptanone
(20 mL) in methanol (250 mL). The solution was stirred at ambient

Synthesis of Corannulene and Its Alkyl DeriVatiVes
J. Am. Chem. Soc., Vol. 121, No. 34, 1999 7811
temperature for 1 h, diluted with water (250 mL), and extracted with
dichloromethane. The organic layer was washed once with 10% aqueous
hydrochloric acid (100 mL) and 3 times with water (250 mL), dried
with magnesium sulfate, filtered, and evaporated. The crude oil was
transferred to a 200 mL sealable reaction vessel and 2,5-norbornadiene
(30 mL) and acetic anhydride (60 mL) were added. The vessel was
sealed and placed in an oil bath at 140 °C for 3 days. The reaction was
cooled to ambient temperature, diluted with benzene (100 mL), and
extracted 3 times with 10% aqueous sodium hydroxide (100 mL) and
then water (100 mL). The organic layer was dried with magnesium
sulfate, filtered, and evaporated to yield a dark brown oil. The oil was
purified by flash chromatography with cyclohexane as the eluent to
378 (30, M+), 380 (65, M + 2), 382 (60, M + 4), 384 (25, M + 6),
220 (100, M - 2Br+).
3,8-Dibromo-5,6-dichloroacenaphthenequinone (34). Chromium
trioxide (45.9 g, 460 mmol) was added in 3 portions over 2 h to the
vigorously stirred solution of 3,8-dibromo-5,6-dichloroacenaphthene
(33) (35.0 g, 91.9 mmol) and acetic anhydride (500 mL) at 0 °C.
Between the additions the solution was allowed to warm to room
temperature for 45 min. Note: Care must be giVen to aVoid a highly
exothermic reaction if the temperature is not moderated or the solution
is not stirred well. After the additions were complete, the reaction was
carefully heated to 80 °C for 30 min. The solution was poured into 1.5
L of water and stirred for 30 min, and the precipitate was collected
and washed thoroughly with water to yield golden yellow solid (35.5
g, 90%). Mp 208 °C dec (lit. mp 286-287 °C).35 1H NMR (500 MHz,
DMSO-d6): δ 8.25 (s, 2H). 13C NMR (125 MHz, DMSO-d6): δ 118.1,
123.0, 126.1, 135.0, 136.0, 148.4, 182.9. IR (KBr) 1725 cm-1 (CdO).
HRMS m/z: found 405.7807; calcd (C12H2Br2Cl2O2) 405.7799.
1,6-Dibromo-3,4-dichloro-7,10-dimethylfluoranthene (35). A 20%
solution of potassium hydroxide in methanol (50 mL) was added to a
solution of 3,8-dibromo-5,6-dichloroacenaphthenequinone (34) (35.2
g, 86.0 mmol) and 3-pentanone (15 mL) in methanol (500 mL). The
solution was stirred at ambient temperature for 1 h, diluted with water
(500 mL), and neutralized with a 10% aqueous hydrochloric acid
solution. The precipitate formed was collected by filtration, washed
with water, dried in air, split into two roughly equal portions, and
transferred to two 200 mL sealable reaction vessels. 2,5-Norbornadiene
(50 mL) and acetic anhydride (100 mL) were added to each vessel.
The vessels were sealed and placed in an oil bath at 130 °C for 4 days,
cooled to ambient temperature, combined, diluted with benzene (100
mL), neutralized slowly with 10% aqueous sodium hydroxide (100 mL),
and extracted 3 times with water (100 mL). The organic layer was
dried with magnesium sulfate, filtered and evaporated to yield a dark
brown oil. The oil was purified by column chromatography with 2:1
cyclohexane/benzene as the eluent to yield a golden yellow solid (9.5
1
yield a golden yellow solid (2.8 g, 45% 2 steps). Mp 60-61 °C. H
3
3
NMR (CDCl3, 300 MHz): δ 1.32 (t, J ) 7.5 Hz, 6H), 1.35 (t, J )
7.5 Hz, 6H), 3.06 (q, 3J ) 7.5 Hz, 4H), 3.11 (q, 3J ) 7.5 Hz, 4H), 7.27
(s, 2H), 7.46 (d, J ) 8.4 Hz, 2H), 7.72 (d, J ) 8.4, 2H). 13C NMR
(100 MHz, CDCl3): δ 15.7, 15.8, 28.3, 29.2, 126.0, 126.4, 128.0, 129.4,
133.3, 133.9, 136.2, 138.3, 139.0. HRMS m/z: found 314.2034; calcd
(C24H26) 314.2035.
3
3
1,6,7,10-Tetrakis(bromoethyl)fluoranthene (30) (Mixture of Di-
astereomers). 1,6,7,10-Tetraethylfluoranthene (29) (2.76 g, 8.78 mmol),
N-bromosuccinimide (6.22 g, 34.90 mmol), and benzoyl peroxide (10
mg) in carbon tetrachloride (125 mL) were irradiated with incandescent
light and refluxed for 3 h. The solution was cooled to ambient
temperature, extracted 3 times with water (200 mL), dried over
magnesium sulfate, and evaporated to yield a golden solid (5.40 g,
98%). 1H NMR (300 MHz, CDCl3): δ (ppm) 1.9-2.3 (m, 12H), 5.7-
5.9 (m, 4H), 7.7-8.0 (m, 6H).
1,2,5,6-Tetramethylcorannulene (4). Titanium trichloride(DME)1.5
(18.3 g, 63.4 mmol) and zinc-copper couple (13.1 g, 201 mmol) in
DME (400 mL) were refluxed for 2 h to yield a black suspension. A
solution of 1,6,7,10-tetrakis(bromoethyl)fluoranthene (30) (6.68 g, 10.6
mmol) in DME (100 mL) was added to the refluxing black suspension
over a period of 3 days and the mixture was refluxed an additional 3
h. The solution was diluted with cyclohexane (400 mL) and filtered
through a plug of silica gel, then the plug was washed with additional
cyclohexane (500 mL). The solvent was evaporated to yield a yellow
solid. The yellow solid and 2,3-dichloro-5,6-dicyanoquinone (4.13 g,
18.2 mmol) in benzene (100 mL) were stirred at ambient temperature
for 8 h, diluted with cyclohexane (250 mL), and filtered through a
plug of silica gel, then the plug was washed with additional cyclohexane
(250 mL). The solvent was evaporated to yield a pale yellow solid
(0.16 g, 6%, 2 steps). Mp 168-171 °C. 1H NMR (400 MHz, CDCl3):
δ 2.71 (s, 12H), 7.76 (d, 3J ) 8.6 Hz, 2H), 7.85 (d, 3J ) 8.6, 2H), 7.90
(s, 2H). 13C NMR (100 MHz, CDCl3): δ 15.11, 15.13, 124.3, 124.6,
126.5, 129.0, 130.5, 131.3, 132.0, 132.3, 133.4, 133.8, 135.3. HRMS
m/z: found 306.1414; calcd (C24H18) 306.1409.
1
g, 20% for 2 steps). Mp 148-151 °C. H NMR (300 MHz, CDCl3):
δ 2.83 (s, 6 H), 7.17 (s, 2 H), 7.96 (s, 2H). 13C NMR (125 MHz,
CDCl3): δ 25.7, 116.3, 122.7, 130.6, 131.4, 133.0, 136.9, 137.0, 137.3,
138.6. HRMS m/z: found 453.8530; calcd (C18H10Br2Cl2) 453.8526.
3,4-Dichloro-1,6,7,10-tetramethylfluoranthene (36). Trimethyl-
aluminum (2.7 mL, 2 M in hexanes, 5.43 mmol) was added dropwise
to a solution of 1,6-dibromo-3,4-dichloro-7,10-dimethylfluoranthene
(35) (1.13 g, 2.47 mmol) and tetrakis(triphenylphosphine) palladium-
(0) (0.074 g, 0.064 mmol) in DME (50 mL). The solution was warmed
to 60 °C for 30 min, quenched slowly with ethanol, extracted with
dichloromethane (50 mL), and washed 3 times with water (100 mL).
The organic layer was dried with magnesium sulfate, filtered, and
evaporated. The crude product was purified by filtration through a plug
of silica gel with benzene as the eluent to yield a golden yellow solid
(0.65 g, 80%). Mp 162-164 °C. 1H NMR (300 MHz, CDCl3): δ 2.67
(s, 6H), 2.73 (s, 6H), 7.11 (s, 2H), 7.44 (s, 2H). 13C NMR (125 MHz,
CDCl3): δ 23.9, 24.2, 121.4, 129.2, 129.6, 131.2, 132.8, 134.8, 134.9,
136.8, 138.8. HRMS m/z: found 326.0617; calcd (C20H16Cl2) 326.0629.
1,6,7,10-Tetrakis(dibromomethyl)-3,4-dichlorofluoranthene (37).
3,4-Dichloro-1,6,7,10-tetramethylfluoranthene (36) (2.00 g, 6.12 mmol),
N-bromosuccinimide (13.1 g, 73.4 mmol), and benzoyl peroxide (10
mg) in carbon tetrachloride (250 mL) were irradiated with incandescent
light and refluxed for 12 h. The solvent was evaporated and the solid
was triturated 3 times with methanol (50 mL) to yield a golden solid
5,6-Dichloroacenaphthene (32). Sulfuryl chloride (110 g, 66 mL,
815 mmol) was added dropwise over a period of 2 h to a solution of
acenaphthene (31) (60 g, 390 mmol) and aluminum chloride (10.4 g,
78 mmol) in nitrobenzene (250 mL). The solution was stirred an
additional 2 h and then poured into 600 mL of a 5:1 mixture of methanol
and water. The precipitate was collected, washed with methanol
thoroughly, and dried to yield a tan solid (52 g, 60%). Mp 167-169
°C (lit. mp 166-168 °C).21 1H NMR (500 MHz, CDCl3): δ 3.27 (s,
3
3
4H), 7.09 (d, J ) 7.5 Hz, 2H), 7.44 (d, J ) 7.5 Hz, 2H). 13C NMR
(125 MHz, CDCl3): δ (ppm) 30.0, 120.3, 125.7, 126.0, 131.4, 142.1,
145.9. MS m/z (rel intensity): 226 (10, M + 4), 224 (66, M + 2), 222
(60, M+), 187 (80, M - Cl+), 152 (100, M - 2Cl+).
1
(5.90 g, quantitative). Mp >300 °C. H NMR (400 MHz, C2D2Cl4 at
80 °C): δ (ppm) 6.98 (s, 2H), 7.05 (s, 2H), 8.20 (s, 2H), 8.29 (s, 2H).
13C NMR (100 MHz, C2D2Cl4 at 80 °C): δ (ppm) 39.7, 40.5, 128.0,
129.8, 133.2, 135.3, 136.1, 136.4, 137.0, 139.7, 140.5.
3,8-Dibromo-5,6-dichloroacenaphthene (33). Bromine (35.9 g, 224
mmol) was added in five portions (every 30 min) to a refluxing solution
of 5,6-dichloroacenaphthene (32) (25.0 g, 112 mmol) and ferric chloride
(1.82 g, 11.2 mmol) in dichloromethane (500 mL). The solution was
stirred at reflux for an additional 2 h after the last addition, cooled to
ambient temperature, extracted 2 times with water (500 mL), and
evaporated. The brownish solid was triturated with methanol (250 mL)
thoroughly to yield of a light brown solid (40.0 g, 90%). Mp 201-203
°C (lit. mp 201-202 °C).35 1H NMR (400 MHz, CDCl3): δ (ppm)
3.28 (s, 4H), 7.62 (s, 2H). 13C NMR (100 MHz, CDCl3): δ (ppm)
31.3, 115.2, 123.8, 127.6, 133.6, 141.9, 145.5. MS m/z (rel intensity):
2,3-Dichlorocorannulene (38). Zinc-copper couple (28.7 g, 442
mmol) and titanium tetrachloride (12.2 mL, 110 mmol) in DME (250
mL) were refluxed for 2 h to yield a black suspension. In 10 portions,
solid 1,6,7,10-tetrakis(dibromomethyl)-3,4-dichlorofluoranthene (37)
(35) Our reported melting point of acenaphthenequinone (34) is consider-
ably different than the literature value. The only other characterization
provided in the original work is the bromine elemental analysis. Kri-
voshapko, N. G.; Karishin, A. P.; Samusenko, Y. V.; Dryanitsa, T. F.;
Lykho, V. P. Ukr. Khim. Zh. 1973, 39, 49-52.

7812 J. Am. Chem. Soc., Vol. 121, No. 34, 1999
Seiders et al.
(5.92 g, 6.13 mmol) was added to the refluxing black suspension over
a period of 2 days. The mixture was refluxed an additional 3 h after
the last addition, diluted with cyclohexane (250 mL), and filtered
through a plug of silica gel, then the plug was washed with additional
benzene (500 mL). The solvent was evaporated to yield a pale yellow
rated. The crude product was purified by column chromatography on
silica gel with cyclohexane as the eluent to yield a golden yellow solid
(1.85 g, 85%). Mp 113-116 °C. 1H NMR (400 MHz, CDCl3): δ 2.69
(s, 6H), 2.73 (s, 6H), 2.85 (s, 2H), 7.07 (s, 2H), 7.11 (s, 2H). 13C NMR
(100 MHz, CDCl3): δ 24.3, 24.4, 24.7, 126.2, 128.8, 130.0, 131.3,
133.5, 134.2, 135.1, 135.4, 139.3. HRMS m/z: found 286.1730; calcd
(C22H22) 286.1716.
1
solid (1.65 g, 85%). Mp 210-213 °C. H NMR (300 MHz, CDCl3):
δ 7.73 (d, J ) 8.7 Hz, 2H), 7.82 (s, 2H), 7.85 (d, J ) 8.7 Hz, 2H),
7.92 (s, 2H). 13C NMR (125 MHz, CDCl3): δ 124.2, 125.9, 127.4,
128.6, 128.8, 130.8, 130.9, 131.0, 133.4, 135.4, 135.8. HRMS m/z:
found 318.0006; calcd (C20H8Cl2) 318.0003.
1,3,4,6,7,10-Hexakis(dibromomethyl)fluoranthene (43). 1,3,4,6,7,-
10-Hexamethylfluoranthene (42) (0.40 g, 1.4 mmol), N-bromosuccin-
imide (5.97 g, 33.6 mmol), and benzoyl peroxide (22 mg) in carbon
tetrachloride (225 mL) were irradiated with incandescent light and
refluxed for 70 h. The solvent was evaporated and the solid was
triturated 3 times with methanol (50 mL), to yield a golden solid (1.75
g, quantitative). Mp >300 °C. 1H NMR (500 MHz, CDCl3): δ (ppm)
3,4-Dichloro-1,6,diethyl-7,10-dimethylfluoranthene (39). Triethyl-
aluminum (70 mL, 1 M in hexanes, 70 mmol) was added dropwise to
a solution of 1,6-dibromo-3,4-dichloro-7,10-dimethylfluoranthene (35)
(14.8 g, 32.4 mmol) and tetrakis(triphenylphosphine)palladium(0) (2.0
g, 1.7 mmol) in DME (1 L). The solution was warmed to 70 °C for 15
h, slowly quenched with methanol, neutralized with 10% aqueous
hydrochloric acid, and extracted with ether (250 mL). The organic layers
were combined, washed 3 times with water (250 mL), dried with
magnesium sulfate, filtered, and evaporated. The product was purified
by column chromatography with cyclohexane as the eluent to yield a
golden yellow solid (5.73 g, 50%). Mp 70-72 °C. 1H NMR (400 MHz,
6.99 (s, 2H), 7.06 (s, 2H), 7.58 (s, 2H), 8.21 (s, 2H), 9.91 (s, 2H). 13
C
NMR (125 MHz, CDCl3): δ (ppm) 36.9, 37.2, 37.3, 120.8, 129.8, 131.2,
131.4, 133.3, 136.9, 138.6, 138.7, 140.0.
Acecorannulylene (7). Zinc-copper couple (7.82 g, 120 mmol) and
titanium tetrachloride (3.3 mL, 30 mmol) in DME (200 mL) were
refluxed for 2 h to yield a black suspension. 1,3,4,6,7,10-Hexakis-
(dibromomethyl)-3,4-dichlorofluoranthene (43) (1.15 g, 0.93 mmol) in
toluene (25 mL) was added to the refluxing black suspension over a
period of 12 h. The mixture was refluxed an additional 3 h after the
last addition, diluted with cyclohexane (250 mL), and filtered through
a plug of silica gel, then the plug was washed with additional benzene
(500 mL). The product was further purified by column chromatography
on silica gel with 30:1 cyclohexane/benzene as the eluent. The solvent
3
3
CDCl3): δ 1.30 (t, J ) 7.6 Hz, 6H), 2.64 (s, 6H), 3.06 (q, J ) 7.6
Hz, 4H), 7.10 (s, 2H), 7.52 (s, 2H). 13C NMR (100 MHz, CDCl3): δ
15.5, 23.7, 28.8, 121.4, 129.5, 129.7, 130.8, 132.6, 133.9, 136.8, 138.8,
139.1. HRMS m/z: found 354.0958; calcd (C22H20Cl2) 354.0942.
1,6-Bis(1-bromoethyl)-7,10-bis(bromomethyl)-3,4-dichlorofluo-
ranthene (40) (Mixture of Diastereomers). 3,4-Dichloro-1,6,diethyl-
7,10-dimethylfluoranthene (39) (5.69 g, 16.1 mmol), N-bromosuccin-
imide (11.4 g, 64.1 mmol), and benzoyl peroxide (10 mg) in carbon
tetrachloride (250 mL) were irradiated with incandescent light and
refluxed for 2 h. The solution was cooled to ambient temperature and
filtered through a plug of silica, then the plug was washed with
additional 1:1 dichloromethane/cyclohexane mixture (250 mL). The
solvent was evaporated to yield a golden solid (10.5 g, 98%). 1H NMR
(400 MHz, CDCl3): δ 2.01 (d, 3J ) 6.8 Hz, 6H), 2.09 (d, 3J ) 6.8 Hz,
1
was evaporated to yield a pale yellow solid (0.020 g, 20%). H NMR
(300 MHz, CDCl3): δ 6.49 (s, 2H), 7.32 (s, 2H), 7.38 (s, 2H), 7.44 (d,
J ) 8.8 Hz, 2H), 7.50 (d, J ) 8.8 Hz, 2H).
2,3-Dimethylcorannulene (5). Trimethylaluminum (2.0 mL, 2.0 M
in hexanes, 4.0 mmol) was added dropwise to a solution of 2,3-
dichlorocorannulene (38) (0.50 g, 1.57 mmol) and 1,3-bis(diphen-
ylphosphino)nickel(II) chloride(0.017 g, 0.031 mmol) in DME (50 mL)
and the solution was heated to reflux for 12 h. The solution was
quenched slowly with ethanol, diluted with dichloromethane (50 mL),
washed 3 times with water (100 mL), dried with magnesium sulfate,
filtered, and evaporated. The product was purified by passage through
a plug of silica gel with benzene as the eluent to yield a white solid
(0.41 g, 95%). Mp 130-132 °C. 1H NMR (300 MHz, CDCl3): δ 2.99
(s, 6H), 7.59 (s, 2H), 7.72 (d, 3J ) 8.7 Hz, 2H), 7.78 (s, 2H), 7.79 (d,
3J ) 8.7 Hz, 2H). 13C NMR (100 MHz, CDCl3): δ 24.2, 126.2, 126.5,
127.1, 127.2, 130.0, 130.3, 130.6, 134.3, 135.62, 135.64, 137.5. HRMS
m/z: found 278.1093; calcd (C22H14) 278.1095.
3
3
6H), 4.67 (d, J ) 11.6 Hz, 2H), 4.80 (d, J ) 11.6 Hz, 2H), 4.86 (d,
3J ) 8.0 Hz, 2H), 4.89 (d,3J ) 8.0 Hz, 2H), 5.70 (q, 3J ) 6.8 Hz, 2H),
5.83 (q, J ) 6.8 Hz, 2H), 7.64 (s, 2H), 7.66 (s, 2H), 7.99 (s, 2H).
3
2,7-Dimethyl-1,2,6,7-tetrahydro-4,5-dichlorocorannulene (Mix-
ture of Cis/Trans Isomers). Zinc-copper couple (35.7 g, 548 mmol)
and titanium tetrachloride (15 mL, 137 mmol) in DME (1.2 L) were
refluxed for 2 h yielding a black suspension. A solution of 1,6-bis(1-
bromoethyl)-7,10-bis(bromomethyl)-3,4-dichlorofluoranthene (40) (10.5
g, 15.7 mmol) in toluene (30 mL) was added to the refluxing black
suspension over a period of 3 days and the solution was refluxed an
additional 3 h after the addition was complete. The reaction was diluted
with cyclohexane (400 mL) and filtered through a plug of silica gel,
then the plug was washed with additional cyclohexane (500 mL). The
solvent was evaporated to yield a yellow solid (4.9 g, 90%). 1H NMR
2,4,5,7-Tetramethylcorannulene (6). Trimethylaluminum (0.15 mL,
2.0 M in hexane, 0.3 mmol) was added dropwise to a solution of 4,5-
dichloro-2,7-dimethylcorannulene (41) (0.041 g, 0.144 mmol) and 1,3-
bis(diphenylphosphino)nickel(II) chloride(0.008 g, 0.014 mmol) in
DME (15 mL) and the solution was heated to 60 °C for 15 h. The
solution was quenched with methanol slowly, diluted with benzene (10
mL), washed 3 times with water (25 mL), dried over magnesium sulfate,
and evaporated. The product was purified by passage through a plug
of silica with a 1:1 mixture of benzene/hexanes as the eluent to yield
as a pale yellow solid (0.035 g, 95%). Mp 188-190 °C. 1H NMR (400
3
3
(400 MHz, CDCl3): δ 1.42 (d, J ) 7.2 Hz, 6H), 1.50 (d, J ) 6.8,
3
3
6H), 2.79-3.32 (m, 8H), 3.39 (q, J ) 7.6 Hz, 2H), 3.48 (q, J ) 7.6
Hz, 2H), 6.91 (s, 2H), 7.35 (s, 2H).
4,5-Dichloro-2,7-dimethylcorannulene (41). 2,7-Dimethyl-1,2,6,7-
tetrahydro-4,5-dichlorocorannulene (4.8 g, 14 mmol) and 2,3-dichloro-
5,6-dicyanoquinone (7.5 g, 33 mmol) in benzene (500 mL) were stirred
at ambient temperature for 2 days. The solution was diluted with
cyclohexane (250 mL) and passed through a plug of silica gel, then
the plug was washed with additional cyclohexane (250 mL). The solvent
4
4
MHz, CDCl3): δ 2.79 (d, J ) 1 Hz, 6H), 2.79 (d, J ) 1 Hz, 6H),
7.51 (d, J ) 1 Hz, 2H), 7.64 (s, 2H), 7.66 (d, J ) 1 Hz, 2H). 13C
NMR (75 MHz, CDCl3): δ 18.9, 24.6, 124.9, 125.7, 126.1, 129.3,
130.3, 130.5, 134.2, 134.5, 135.1, 135.3, 137.1. HRMS m/z: found
306.1398; calcd (C24H18) 306.1409.
4
4
1
was evaporated to yield a pale yellow solid (2.36 g, 50%). H NMR
4
4
(400 MHz, CDCl3): δ 2.76 (d, J ) 1 Hz, 6H), 7.54 (d, J ) 1 Hz,
2H), 7.66 (s, 2H), 7.96 (s, 2H). 13C NMR (100 MHz, CDCl3): δ 18.7,
123.5, 126.5, 126.7, 126.8, 130.1, 130.7, 130.9, 133.1, 134.1, 135.1,
135.2. HRMS m/z: found 346.0309; calcd (C22H12Cl2) 346.0316.
1,3,4,6,7,10-Hexamethylfluoranthene (42). Trimethylaluminum
(23.0 mL, 2 M in hexanes, 46.0 mmol) was added dropwise to a solution
of 1,6-dibromo-3,4-dichloro-7,10-dimethylfluoranthene (35) (3.50 g,
7.7 mmol) and 1,3-bis(diphenylphosphino)propane nickel(II) chloride
(0.21 g, 0.38 mmol) in DME (125 mL). The solution was warmed to
reflux for 24 h, quenched slowly with ethanol, extracted with dichlo-
romethane (50 mL), and washed 3 times with water (100 mL). The
organic layer was dried with magnesium sulfate, filtered, and evapo-
Bromocorannulene (44). Bromine (0.35 g, 2.2 mmol) was added
dropwise over 5 min to a solution of corannulene (1) (0.52 g, 2.1 mmol)
and ferric bromide (0.062 g, 0.21 mmol) in dichloromethane (50 mL)
at -80 °C. The solution was allowed to warm to ambient temperature
over 4 h, quenched with a saturated solution of sodium bisulfite, washed
3 times with water, dried over magnesium sulfate, filtered, and
evaporated. The crude product was purified by passage through a plug
of silica gel with benzene as the eluent to yield a pale yellow solid
(0.65 g, 95%). This material was used as isolated; however, a
spectroscopically pure sample can be obtained by column chromatog-
raphy with cyclohexane as the eluent. Mp 174-176 °C (lit. mp 180-
3
182 °C).27 1H NMR (400 MHz, CDCl3): δ (ppm) 7.71 (d, J ) 8.8

Synthesis of Corannulene and Its Alkyl DeriVatiVes
J. Am. Chem. Soc., Vol. 121, No. 34, 1999 7813
Hz, 1H), 7.78-7.82 (m, 5H), 7.87 (d, 3J ) 8.8 Hz, 1H), 7.93 (d, 3J )
8.8 Hz, 1H), 8.03 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 121.1,
125.7, 126.2, 126.7, 126.95, 126.99, 127.5 (127.5), 127.8, 129.1, 129.9,
130.5, 130.7, 130.8, 131.6, 134.4, 134.7, 135.37, 135.4, 135.5. HRMS
m/z: found 327.9886; calcd (C20H9Br) 327.9888.
dissolved in DME (10 mL), and heated to reflux for 12 h. The solution
was cooled to ambient temperature and filtered to yield a yellow solid
(0.110 g, 60%). Mp >300 °C. Due to the extremely poor solubility the
product has not yet been characterized by 13C NMR. Our experience
is in contrast to the literature report;29 however, no solvent for the NMR
was reported therein. HRMS m/z: found 589.6884; calcd (C20Cl10)
589.6885
Methylcorannulene (8). Trimethylaluminum (0.15 mL 2.0 M in
hexanes, 0.30 mmol) was added dropwise to a solution of bromo-
corannulene (44) (0.05 g, 0.15 mmol) and 1,3-bis(diphenylphosphino)-
nickel(II) chloride(0.004 g, 0.007 mmol) in DME (15 mL). The solution
was heated to reflux for 2 h, quenched slowly with ethanol, diluted
with dichloromethane (50 mL), washed 3 times with water (100 mL),
dried with magnesium sulfate, filtered, and evaporated. The product
was purified by column chromatography on silica gel with hexane as
the eluent to yield of a white solid (0.035 g, 90%). Mp 123-129 °C.
1H NMR (400 MHz, CDCl3): δ 2.92 (d, J ) 0.8 Hz, 3H), 7.64 (d, J
) 0.8 Hz, 1H), 7.80 (d, J ) 8.4 Hz, 1H), 7.83-7.92 (m, 6H), 7.99 (d,
J ) 8.8 Hz, 1H). 13C NMR (100 MHz, CDCl3): δ 19.0, 124.7, 125.6,
126.4, 126.5, 126.7, 126.8, 126.88, 126.90, 130.2, 130.3, 130.7, 130.8,
131.3, 134.6, 135.4, 135.5, 135.6, 135.7, 135.8, 136.6. HRMS m/z:
found 264.0926; calcd (C21H12) 264.0939.
1,3,5,7,9-Pentamethylcorannulene (9). Trimethylaluminum (0.71
mL, 1.42 mmol, 2 M solution in hexanes) was added to a solution of
1,3,5,7,9-pentachlorocorannulene (45) (0.050 g, 0.118 mmol) and 1,3-
bis(diphenylphosphino)nickel(II) chloride(0.020 g, 0.037 mmol) in
DME (50 mL). The solution was refluxed for 24 h, quenched slowly
with methanol then 10% aqueous hydrochloric acid, diluted with
benzene (20 mL), washed 2 times with water (20 mL), dried with
magnesium sulfate, filtered, and evaporated. The product was purified
by column chromatography with cyclohexane as the eluent to yield a
1
pale yellow solid (0.012 g, 33%). Mp 179-182 °C. H NMR (400
4
4
MHz, CDCl3): δ 2.78 (d, J ) 0.8 Hz, 15H), 7.55 (d, J ) 0.8 Hz,
5H). 13C NMR (100 MHz, CDCl3): δ 19.1, 122.8, 130.5, 134.4, 136.1.
HRMS m/z: found 320.1560; calcd (C25H20) 320.1565.
1,3,5,7,9-Pentachlorocorannulene (45). Iodine monochloride (25
mL, 25 mmol, 1 M in dichloromethane) was cooled to -78 °C and
corannulene (1) (0.480 g, 1.92 mmol) was added. The mixture was
allowed to warm to room temperature over 10 h and stirred an additional
3 days at ambient temperature. The solution was poured into 50 mL of
chloroform and washed 2 times with 5% aqueous sodium thiosulfate
(20 mL) and 2 times with water (20 mL). The resulting yellow
suspension was evaporated to dryness and triturated 2 times with
hexanes (20 mL) and 3 times with dichloromethane (10 mL). The
resulting yellowish solid was recrystallized from 1,1,2,2-tetrachloro-
Decamethylcorannulene (10). Trimethylaluminum (2.73 mL, 2 M
in hexanes, 5.46 mmol) was added dropwise to a solution of decachlo-
rocorannulene (46) (0.130 g, 0.219 mmol) and 1,3-bis(diphenylphos-
phino)nickel(II) chloride(0.020 g, 0.037 mmol) in DMEU (25 mL).
The solution was heated to 90 °C for 18 h, quenched with ethanol
slowly, diluted with benzene, washed 5 times with water, dried over
magnesium sulfate, filtered, and evaporated. The product was purified
by passage through a plug of silica with benzene as the eluent. The
solvent was evaporated to yield a yellow solid (0.025 g, 30%). Mp
310-312 °C. 1H NMR (500 MHz, CDCl3): δ 2.89 (s, 30H). 13C NMR
(125 MHz, CDCl3) δ (ppm): 20.5, 129.6, 130.5, 133.7. HRMS m/z:
found 390.2347; calcd 390.2348.
1
ethane to yield a pale yellow solid (0.420 g, 52%). Mp >300 °C. H
NMR (400 MHz, 1,1,2,2-C2D2Cl4, 80 °C): δ 8.02 (s, 5H). MS m/z
(rel intensity): 419.7 (63, M+), 0.421.7 (100, M + 2), 423.7 (70, M +
4), 425.7 (23, M + 6).
Acknowledgment. This work was supported by the National
Science Foundation (CHE-9628565; ASC-8902827). This work
was also supported by a stipend of the German Academic
Exchange Service (DAAD) for G.H.G.
Decachlorocorannulene (46). A solution of 2,3-dichlorocorannulene
(38) (0.100 g, 0.314 mmol), sulfuryl chloride (2.5 mL), and sulfur
monochloride (0.100 g, 0.735 mmol) was added over 5 min to a solution
of aluminum chloride (0.025 g, 0.188 mmol) in sulfuryl chloride (7.5
mL). The solution was heated to a gentle reflux for 12 h. After all of
the liquid evaporates, additional sulfuryl chloride (5 mL) was added
and the solution was reflux for and an additional 5 h. The solution was
cooled then poured onto water and neutralized with potassium carbonate
and the solid collected by filtration. The solid was dried in air for 1 h,
Supporting Information Available: 1H and 13C NMR
spectra for compounds 22, 23, and 24 (PDF). This material is
available free of charge via the Internet at http://pubs.acs.org.
JA991310O