Synthesis and characterization of the three dicyclopentapyrenes

Full text of DOI:10.1021/jo9516087

3
86
J . Org. Chem. 1996, 61, 386-388
1
Ta ble 1. H NMR P a tter n s for Dicyclop en ta p yr en es 1, 2,
Syn th esis a n d Ch a r a cter iza tion of th e
a n d 3a
Th r ee Dicyclop en ta p yr en es1
average chemical shiftsb
Lawrence T. Scott* and Atena Necula
compd
6-membered rings
5-membered rings
1
2
3
8.26
7.55
7.58
7.35
6.66
6.91
Department of Chemistry, Merkert Chemistry Center,
Boston College, Chestnut Hill, Massachusetts 02167-3860
Received September 5, 1995
a
Measured in CDCl3. b In ppm downfield from tetramethylsi-
lane.
Polycyclic aromatic hydrocarbons containing fully un-
saturated five-membered rings as integral components
of their trigonal carbon networks (CP-PAHs) have at-
Several years ago, we extended the synthetic utility of
this method by introducing the 1-chlorovinyl side chain
as a superior “masked ethynyl group” for flash pyrolyses
tracted considerable attention recently in a variety of
scientific circles.2
-10
Some of these novel nonalternant
(
Scheme 1) and exploited this technology in a three-step
hydrocarbons exhibit unusual photophysical behavior,
1
2
3
synthesis of corannulene. We have subsequently em-
ployed the same methodology for the synthesis of numer-
ous CP-PAHs,1 including those reported here, and other
workers have adopted our method to prepare such
e.g., anomalous fluorescence, and/or pronounced biologi-
4
cal activity, e.g., acute cyctotoxicity. Many have been
,7
identified or are believed to be formed as products of
5
incomplete combustion, either in flames or in cigarette
1
3
6
compounds as cyclopentapyrene and a C30
H12 double
smoke, and a few have been produced by flash pyrolyses
corannulene.14
of other hydrocarbons.7,8 Five-membered rings fully
encircled by benzene rings impart a curvature to the
Friedel-Crafts acylation of pyrene with excess acetyl
chloride and aluminum chloride in carbon disulfide gives
1,3-diacetylpyrene (4), 1,6-diacetylpyrene (5), and 1,8-
diacetylpyrene (6), all of which can be isolated in usable
quantities through a combination of crystallization and
chromatographic purification methods.15 Separate treat-
trigonal carbon network that gives rise to the bowl-
shaped geometry of corannulene9 and to the closed
polyhedral surfaces of the fullerenes.10 Herein we report
the syntheses and a preliminary spectroscopic examina-
tion of the three isomeric dicyclopentapyrenes 1, 2, and
1
5
ment of each diketone with PCl in dichloromethane at
3
, all of which were unknown until now. The H NMR
room temperature gives the corresponding bis(1-chlo-
rovinyl)pyrenes 7, 8, and 9, and flash vacuum pyrolysis
of these at 1000 °C/0.75-1.0 mmHg in separate experi-
ments gives the title compounds 1, 2, and 3, respectively
properties of isomer 1 differ markedly from those of 2
and 3 (Table 1).
(
Scheme 2).
1
A full listing of all the H NMR chemical shifts and
coupling constants for the title compounds can be found
together with the 13C NMR data in the Experimental
1
Section; however, the striking difference in the gross H
NMR spectroscopic properties of isomer 1 vis- a` -vis those
of 2 and 3 (Table 1) deserves comment. Even a casual
inspection of the NMR spectra reveals that the reso-
nances of all the hydrogens in 2 and 3 are shifted upfield
The key step in our syntheses takes advantage of the
intramolecular trapping of vinylidenes generated ther-
mally from terminal acetylenes, a powerful method for
1
1
(8) Neilen, R. H. G.; Wiersum, U. E. J anssen Chim. Acta 1992, 10,
ring construction first reported by R. F. C. Brown.
3
1
. Brown, R. F. C.; Eastwood, F. W.; Wong, N. R. Tetrahedron Lett.
993, 34, 3607-8. Brown, R. F. C.; Choi, N.; Coulston, K. J .; Eastwood,
F. W.; Wiersum, U. E.; J enneskens, L. W. Tetrahedron Lett. 1994, 35,
4405-8.
(1) Presented at the Symposium on Synthetic Hydrocarbon Chem-
istry, Loker Hydrocarbon Research Institute, University of Southern
California, Los Angeles, December, 1994, and at the Eighth Interna-
tional Symposium on Novel Aromatic Compounds, Braunschweig,
Germany, August, 1995.
(9) Lawton, R. G.; Barth, W. E. J . Am. Chem. Soc. 1971, 93, 1730-
45. Hanson, J . C.; Nordman, C. E. Acta Crystallogr., Sect. B 1976, B32,
1147-53. Scott, L. T.; Hashemi, M. M.; Bratcher, M. S. J . Am. Chem.
Soc. 1992, 114, 1920-1. Borchardt, A.; Fuchicello, A.; Kilway, K. V.;
Baldridge, K. K.; Siegel, J . S. J . Am. Chem. Soc. 1992, 114, 1921-3.
Siegel, J . S.; Seiders, T. J . Chem. Br. 1995, 313-316.
(10) Curl, R. F.; Smalley, R. E. Sci. Am. 1991, 265, 54-63. Kroto,
H. W.; Allaf, A. W.; Balm, S. P. Chem. Rev. 1991, 91, 1213-35. Kroto,
H. W. Angew. Chem. 1992, 104, 113-33 (See also Angew. Chem., Int.
Ed. Engl. 1992, 31 (2), 111-29). Billups, W. E., Ciufolini, M. A., Eds.
Buckminsterfullerenes; VCH: New York, 1993. Hirsch, A. Chemistry
of the Fullerenes; Thieme: Stuttgart, Germany, 1994.
(11) Brown, R. F. C.; Harrington, K. J .; McMullen, G. L. J . Chem.
Soc., Chem. Commun. 1974, 123-4. Brown, R. F. C.; Eastwood, F. W.;
J ackman, G. P. Aust. J . Chem. 1977, 30, 1757-67. Brown, R. F. C.
Recl. Trav. Chim. Pays-Bas 1988, 107, 655-61. Brown, R. F. C. Pure
Appl. Chem. 1990, 62, 1981-6. Brown, R. F. C.; Eastwood, F. W.
Synlett 1993, 9-19.
(12) Scott, L. T.; Cheng, P.-C.; Bratcher, M. S. Eighth International
Symposium on Novel Aromatic Compounds, Victoria, British Columbia,
Canada, J uly 19-24, 1992; Abstract No. 64. Cheng, P.-C. M.S. Thesis,
University of Nevada, Reno, 1992.
(13) Sarobe, M.; Zwikker, J . W.; Snoeijer, J . D.; Wiersum, U. E.;
J enneskens, L. W. J . Chem. Soc., Chem. Commun. 1994, 89-90.
(14) Rabideau, P. W.; Abdourazak, A. H.; Folsom, H. J . Am. Chem.
Soc. 1994, 116, 7891-2.
(15) Harvey, R. G.; Pataki, J .; Lee, H. Org. Prep. Proced. Int. 1984,
16, 144-8.
(
2) Plummer, B. F.; Steffen, L. K.; Herndon, W. C. Struct. Chem.
993, 4, 279-85. Tucker, S. A.; Acree, W. E., J r.; Fetzer, J . C.; Harvey,
R. G.; Tanga, M. J .; Cheng, P.-C.; Scott, L. T. Appl. Spectrosc. 1993,
1
4
7, 715-22.
(
3) Plummer, B. F.; Al-Saigh, Z. Y. J . Phys. Chem. 1983, 87, 1579-
8
1
9
2. Plummer, B. F.; Al-Saigh, Z. Y.; Arfan, M. Chem. Phys. Lett. 1984,
04, 389-92. Plummer, B. F.; Singleton, S. F. J . Phys. Chem. 1990,
4, 7363-6.
(4) Cavalieri, E.; Rogan, E.; Toth, B.; Munhall, A. Carcinogenesis
1
1
981, 2, 277-81. Raveh, D.; Slaga, T. J .; Huberman, E. Carcinogenesis
982, 3, 763-6.
(5) Lam, F. W.; Howard, J . B.; Longwell, J . P. Chem. Phys. Processes
Combust. 1987, 93, 1-93. Pope, C. J .; Marr, J . A.; Howard, J . B. J .
Phys. Chem. 1993, 97, 11001-13. Lafleur, A. L.; Howard, J . B.; Marr,
J . A.; Yadav, T. J . Phys. Chem. 1993, 97, 13539-43. Marr, J . A.;
Giovane, L. M.; Longwell, J . P.; Howard, J . B.; Lafleur, A. L. Combust.
Sci. Technol. 1994, 101, 301-9.
(
6) Lam, J .; Pedersen, B. O.; Thomasen, T. Beitr. Tabakforsch. Int.
1
8
985, 13, 1-9. Mitra, S.; Wilson, N. K. Environ. Int. 1992, 18, 477-
7.
(
7) Necula, A.; Scott, L. T. Unpublished results presented at the
Northeast Regional Meeting of the American Chemical Society, Bur-
lington, VT, J une 19-21, 1994. Necula, A.; Scott, L. T. Unpublished
results presented at the National Meeting of the American Chemical
Society, Washington, DC, August 21-26, 1994.
0
022-3263/96/1961-0386$12.00/0 © 1996 American Chemical Society

Notes
J . Org. Chem., Vol. 61, No. 1, 1996 387
Sch em e 1
In this respect, isomers 2 and 3 resemble dicyclopen-
tanaphthalene (pyracylene), in which the hydrogens are
significantly shielded by the paramagnetic ring current
contribution of an antiaromatic 4N π-electron perim-
eter.19 Isomer 1 should feel no such paramagnetic ring
current effect, and this may well contribute to the lower-
field resonances of its protons. High-level molecular
orbital calculations ought to shed further light on the
differences between these isomers.
Sch em e 2
The syntheses described herein make it possible to
confirm or refute experimentally the presence of these
dicyclopentapyrenes in flames and smoke as well as to
test their carcinogenicity. The possibility that hydrocar-
bon 3 might isomerize to corannulene (also C20H10) by a
Stone-Wales-type rearrangement20 under suitable condi-
tions can now also be tested.
Exp er im en ta l Section
Gen er a l. High-resolution mass spectra were obtained from
the Mass Spectroscopy Laboratory, School of Chemical Sciences,
University of Illinois.
Gen er a l P r oced u r e for th e P r ep a r a tion of Bis(1-ch lo-
r ovin yl)p yr en es. A mixture of 0.1 g (0.35 mmol) of the
diacetylpyrene,15 0.218 g (1.05 mmol) of phosphorous pentachlo-
ride, and 10 mL of methylene chloride was stirred at room
temperature for 3 h. The reaction was quenched with water and
extracted with methylene chloride. The crude product was
purified by column chromatography on silica gel with pentane.
A small amount (2-7%) of over-chlorinated product could
1
generally be detected in the chromatographed material by
H
NMR spectroscopy (singlet at 6.6-6.7 ppm), but this minor
contaminant caused no apparent problem in the next step.
1
,3-Bis(1-ch lor ovin yl)p yr en e (7): yield of 66 mg (44%) from
1
1
35 mg of 1,3-diacetylpyrene; mp ) 130 °C; H NMR (400 MHz,
CDCl ) δ 8.42 (d, 2H, J ) 9.2 Hz), 8.25 (d, 2H, J ) 7.7 Hz), 8.18
d, 2H, J ) 9.2 Hz), 8.08 (s, 1H), 8.06 (t, 1H, J ) 7.6 Hz), 6.01
d, 2H, J ) 1.3 Hz), 5.71 (d, 2H, J ) 1.3 Hz); 13C NMR (100
) δ 138.1, 133.2, 130.7, 128.8, 127.1, 126.4, 126.1,
24.1, 118.8; HRMS calcd for C20 322.0316, found 322.0315.
,6-Bis(1-ch lor ovin yl)p yr en e (8): yield of 69 mg (62%) from
3
(
(
MHz, CDCl
3
1
H12Cl
2
g
1
1
1
00 mg of 1,6-diacetylpyrene; mp ) 185 °C; H NMR (400 MHz,
) δ 8.47 (d, 2H, J ) 9.2 Hz), 8.18 (d, 2H, J ) 7.8 Hz), 8.13
d, 2H, J ) 9.2 Hz), 8.07(d, 2H, J ) 7.9 Hz), 6.01 (d, 2H, J ) 1.2
CDCl
3
by 0.4-0.7 ppm relative to the resonances of the corre-
sponding hydrogens in 1.
(
1
3
Hz), 5.68 (d, 2H, J ) 1.2 Hz); C NMR (100 MHz, CDCl
38.5, 134.4, 131.4, 128.3, 127.9, 126.8, 125.2, 124.9, 124.7, 110.5;
HRMS calcd for C20 322.0316, found 322.0315.
3
) δ
As a first-order explanation for this curious difference,
we note that two of the seven resonance structures of
isomers 2 and 3 can be viewed as antiaromatic [16]-
annulene perimeters with a closed-shell butadiene moiety
1
H
12Cl
2
1,8-Bis(1-ch lor ovin yl)p yr en e (9): yield of 58 mg (52%) from
100 mg of 1,8-diacetylpyrene; mp ) 105 °C; H NMR (400 MHz,
3
CDCl ) δ 8.52 (s, 2H), 8.16 (d, 2H, J ) 7.8 Hz), 8.07 (d, 2H, J )
1
in the core (s-trans and s-cis, respectively).1
6-18
Isomer
7
1
1
.3 Hz), 8.06 (s, 2H), 6.02 (d, 2H, J ) 1.2 Hz), 5.68 (d, 2H, J )
.2 Hz); 13C NMR (100 MHz, CDCl
) δ 138.4, 134.2, 131.8, 127.9,
27.8, 126.8, 125.2, 125.0, 124.6, 118.5; HRMS calcd for C20
322.0316, found 322.0315.
Gen er a l P r oced u r e for th e P r ep a r a tion of Dicyclop en -
1
, on the other hand, has no resonance structures with
3
an antiaromatic [16]annulene perimeter that leave a
closed-shell moiety in the core; perimeter delocalization
in 1 would leave a trimethylenemethane core (contrast
12
H -
Cl
2
1
0 with 11 and 12).
ta p yr en es. Compounds 7, 8, and 9 were submitted to flash
vacuum pyrolysis at 1000 °C, with a slow bleed of nitrogen
(
16) Though the “perimeter model” of Platt17 has fallen into disfavor
as a method for predicting the overall aromaticity of PAHs, the
presence or absence of closed conjugated circuits around the perimeter
of a PAH in one or more of its valence bond resonance structures does
make a weighted contribution to the overall electronic properties of
the molecule.18
(19) Trost, B. M.; Bright, G. M. J . Am. Chem. Soc. 1967, 89, 4244-
5. Trost, B. M.; Bright, G. M.; Frihart, C. J . Am. Chem. Soc. 1971, 93,
737-45.
(20) Stone, A. J .; Wales, D. J . Chem. Phys. Lett. 1986, 128, 501-3.
Murry, R. L.; Strout, D. L.; Odom, G. K.; Scuseria, G. E. Nature 1993,
366, 665-7. Murry, R. L.; Strout, D. L.; Scuseria, G. E. Int. J . Mass
Spectrom. Ion Processes 1994, 138, 113-31. Hawkins, J . M.; Nambu,
M.; Meyer, A. J . Am. Chem. Soc. 1994, 116, 7642-5 and references
cited therein.
(
17) Platt, J . R. J . Chem. Phys. 1954, 22, 1448.
(18) Randic, M. J . Am. Chem. Soc. 1977, 99, 444-50. Randic, M.
Tetrahedron 1977, 33, 1905-20. Randic, M.; Trinajstic, N. J . Am.
Chem. Soc. 1984, 106, 4428-34.

3
88 J . Org. Chem., Vol. 61, No. 1, 1996
Notes
carrier gas (final pressure: 0.75-1.0 mmHg), as previously
250.0782, Found 250.0784. Anal. Calcd for C20
H, 4.03. Found: C, 95.66; H, 4.31.
H
10: C, 95.97;
1
2
described.
The dicyclopentapyrenes were purified by flash
vacuum chromatography on silica gel with pentane. All three
dicyclopentapyrenes are sensitive to air oxidation, but decom-
position can be retarded by storage under nitrogen in the dark
at -20 °C.
Dicyclop en ta [cd ,fg]p yr en e (3): yield of 40 mg (51%) from
1
°
7
6
1
00 mg of 1,8-bis(1-chlorovinyl)pyrene; brown crystals; mp ) 190
1
C dec; H NMR (400 MHz, CDCl
3
) δ 7.70 (d, 2H, J ) 7.6 Hz),
.61 (d, 2H, J ) 7.6 Hz), 7.45 (s, 2H), 7.02 (d, 2H, J ) 5.3 Hz),
Dicyclop en ta [cd ,m n ]p yr en e (1): yield of 30 mg (78%) from
13
.79 (d, 2H, J ) 5.3 Hz); C NMR (100 MHz, acetone-d
6
) δ 141.2,
6
1
0 mg of 1,3-bis(1-chlorovinyl)pyrene; brick red crystals; mp )
38.7, 138.2, 131.6, 131.4, 128.6, 128.1, 127.8, 124.5, 121.3; UV-
1
80 °C dec; H NMR (400 MHz, CDCl ) δ 8.44 (d, 2H, J ) 7.7
3
vis (hexane) λmax (log ꢀ) 418 (3.58), 400 (3.96), 386 (4.30), 366
4.21), 350 (3.88), 319 (4.32), 304 (4.40), 296 (4.36), 279 (4.39),
39 (4.80); HRMS calcd for C20 10 250.0782, found 250.0784.
Hz), 8.30 (s, 2H), 8.11 (s, 1H), 7.99 (t, 1H, J ) 7.7 Hz), 7.49 (d,
H, J ) 5.0 Hz), 7.20 (d, 2H, J ) 5.0 Hz); 13C NMR (100 MHz,
CDCl ) δ 138.5, 135.6, 134.9, 132.6, 131.4, 127.9, 126.9, 126.4,
25.6, 120.0, 118.6, 114.6; UV-vis (hexane) λmax (log ꢀ) 367
3.30), 350 (3.26), 332 (3.04), 278 (3.50), 232 (3.67); HRMS calcd
for C20 10 250.0782, found 250.0781.
(
2
2
H
3
1
(
Ack n ow led gm en t. We thank the Department of
Energy for financial support of this work.
H
Dicyclop en ta [cd ,jk]p yr en e (2): yield of 62 mg (80%) from
00 mg of 1,6-bis(1-chlorovinyl)pyrene; dark brown crystals; mp
1
)
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
1
210 °C dec; H NMR (400 MHz, CDCl
3
) δ 7.71 (d, 2H, J ) 7.7
spectra for compounds 1, 2, 3, 7, 8, and 9 (22 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
Hz), 7.49 (s, 2H), 7.45 (d, 2H, J ) 7.7 Hz), 6.69 (d, 2H, J ) 5.1
1
3
Hz), 6.61 (d, 2H, J ) 5.1 Hz); C NMR (100 MHz, CDCl
40.7, 140.2, 133.2, 131.8, 131.3, 130.4, 129.3, 125.4, 122.1, 121.2;
UV-VIS (hexane) λmax (log ꢀ) 490 (3.47), 459 (3.42), 435 (3.21),
98 (3.97), 388 (3.50), 376 (3.68), 355 (3.30), 323 (sh, 3.53), 308
sh, 3.75), 287 (3.94), 240 (4.40); HRMS calcd for
3
) δ
1
3
(
C
20
H
10
J O9516087