J. Am. Chem. Soc. 2001, 123, 355-356
355
Scheme 1
Palladium-Catalyzed Formation of Aceanthrylenes:
A Simple Method for Peri-Cyclopentenelation of
Aromatic Compounds
Hung Dang and Miguel A. Garcia-Garibay*
Department of Chemistry and Biochemistry
UniVersity of California, Los Angeles, California 90095-1569
Table 1. Palladium-Catalyzed Reaction of 1 with Terminal
Alkynesa
ReceiVed June 28, 2000
bp of
alkyne
(°C)
total
Many efforts have been directed toward the synthesis of
polynuclear aromatic hydrocarbons (PAH) that have peri-fused
five- and six-membered-ring carbon fragments corresponding to
portions of the fullerene surface.1 These include polycyclic
aromatic systems with potentially interesting fullerene-like photo-
physical properties such as acenaphthalene (I), pyracylene (II),
aceanthrylene (III), and several cyclopentapyrenes (e.g., IV and
V). Previously reported syntheses to construct the two carbon
etheno bridges highlighted in the examples involve multistep
processes2 or flash vacuum pyrolysis (FVP);3 the latter often
results in relatively low yields. In this communication, we report
a novel transformation that may ultimately lead to the facile
synthesis of these PAH’s.
yield
entry
alkyne (R)
rxn conds
(%)b 2 (%)c 3 (%)c
a
b
c
d
e
f
-C(CH3)2OH
-C(CH3)2OH
-C6H5
-Si(CH3)3
-Si(CH3)3
-Si(CH2CH3)3
-Si(CH(CH3)2)3
-Si(CH(CH3)2)3
104 reflux
80-90 91
99
4
sealed tubed 50
96
0
84
93
38
37
42
143 reflux
53 reflux
62
18
10012
1613
7
sealed tubed 75
136 reflux
51 reflux
76
16
62
63
58
g
h
sealed tubed 67
a Conditions: PdCl2(PPh3)2 (4.5 mol %), PPh3 (23 mol %), CuSO4/
Al2O3 (17 mol %), alkyne (400 mol %), Et3N (400 mol %), benzene
(deoxygenated), refluxed 16 h. b Total isolated yield of 2 and 3 after
chromatography. c Relative ratios determined by 1H NMR. d Sealed tube
reactions were carried out at 110 °C with no copper.
We describe here the first example of the preparation of
2-substituted aceanthrylenes 2 via a one-step Pd(0)-catalyzed
coupling of 9-bromoanthracene (1) with monosubstituted acetyl-
enes (Scheme 1). While preparing 9-ethynylanthracenes 3 using
Sonogashira reaction conditions,4 we discovered that Pd(0)-
catalyzed coupling of 9-bromoanthracene (1) with 2-methyl-3-
butyn-2-ol formed 9-alkynylanthracene (3a, R ) -C(CH3)2OH)
(Scheme 1 and Table 1) and the unexpected 2-(1-hydroxy-1-
methylethyl)aceanthrylene (2a) (R ) -C(CH3)2OH) in 71%
purified overall yield, with a 72:28 ratio.5,6 Compound 3a is pale
yellow (λmax at 347, 364, 383, and 405 nm) and highly fluorescent.
In contrast, aceanthrylene 2a is a reddish-orange material with
no detectable fluorescence emission. Compound 2a is highly
crystalline and gives large ruby-red prisms by slow evaporation
from a mixture of ethyl acetate and hexanes. The molecular
Figure 1. X-ray crystal structure of 2a (ORTEP diagram, left). The
packing view shows four aceanthrylene molecules hydrogen bonding in
the crystal lattice (right).
structure of 2a was determined and characterized by 1H and 13
C
NMR and further confirmed by X-ray analysis.7 The ORTEP
diagram (Figure 1, left) of aceanthrylene 2a shows a planar
nonalternant aceanthrylene core.8 The crystal packing (Figure 1,
right) reveals a hydrogen-bonding network of four aceanthrylene
molecules in a cyclic array, with two crystallographically
independent molecules in the asymmetric unit cell.
(1) (a) Scott, L. T.; Bratcher, M. S.; Hagen, S. J. Am. Chem. Soc. 1996,
118, 8743. (b) Liu, C. Z.; Rabideau, P. W. Tetrahedron Lett. 1996, 37, 3437.
(c) Clayton, M. D.; Rabideau, P. W. Tetrahedron Lett. 1997, 38, 741. (d)
Sygula, A.; Rabideau, P. W. J. Am. Chem. Soc. 1998, 120, 12666. (e) Seiders,
T. J.; Elliott, E. L.; Grube, G. H.; Siegel, J. S. J. Am. Chem. Soc. 1999, 121,
7804. (f) Sygula, A.; Rabideau, P. W. J. Am. Chem. Soc. 1999, 121, 7800.
(2) (a) Becker, H. -D.; Hansen, L.; Andersson, K. J. Org. Chem. 1985, 50,
277. (b) Mulder, P. P. J.; Boerrigter, J. O.; Boere, B. H.; Zuilhof, H.; Erkelsens,
C.; Cornelisse, J.; Lugtenburg, J. Recl. TraV. Chim. Pays-Bas 1993, 112, 287.
(c) Plummer, B. F.; Al-Saigh, Z. Y.; Arfan, M. J. Org. Chem. 1984, 49, 2069.
(d) Sangaiah, R.; Gold, A. Org. Prep. Proced. Int. 1985, 17, 53.
(3) (a) Brown, R. F. C.; Eastwood, F. W.; Kissler, B. E. Tetrahedron Lett.
1988, 29, 6861. (b) Sarobe, M.; Flink, S.; Jenneskens, L. W.; Zwikker, J. W.;
Wesseling, J. J. Chem. Soc., Perkin Trans. 2 1996, 2125. (c) Brown, R. F.
C.; Eastwood, F. W.; Wong, N. R. Tetrahedron Lett. 1993, 34, 3607. (d) Scott,
L. T. Pure Appl. Chem. 1996, 68, 291. (e) Scott, L. T.; Necula, A. J. Org.
Chem. 1996, 61, 386. (f) Sarobe, M.; Havenith, R. W. A.; Jenneskens, L. W.
Chem. Commun. 1999, 11, 1021. (g) Jenneskens, L. W.; Sarobe, M.; Zwikker,
J. W. Pure Appl. Chem. 1996, 68, 219.
The reaction was originally carried out in refluxing deoxygen-
ated benzene in the presence of 4.5 mol % of PdCl2(PPh3)2, 23
mol % of PPh3, 17 mol % of CuI, 2 equiv of Et3N, and 1.1 equiv
of the alkyne.4a We were surprised and delighted to discover the
formation of aceanthrylene 2a and we decided to explore the
conditions to improve its selectivity. We first found that the yields
of reaction were dependent on the amount of base used. When
triethylamine was omitted, no reaction was observed and starting
material 1 was recovered. Increasing the amount of base up to
(7) 2a: C19H16O, MW ) 260.32, monoclinic, space group P21/c, a )
12.2402(13) Å, b ) 12.6193(13) Å, c ) 18.4528(18) Å, â ) 102.93(3)o, V )
2777.9(5) Å3, Z ) 4, Fcalcd ) 1.245 Mg/m3, F(000) ) 1104, λ ) 0.7173 Å,
µ(Mo ΚR) ) 0.075 mm-1, T ) 20 °C, crystal size ) 0.3 × 0.2 × 0.2 mm3.
Of the 17847 reflections collected (1.71e 2θ e 28.31°), 6631 [R(int) )
0.0560)] were independent reflections; max/min residual electron density 132
and -129 e nm-3, R1 ) 0.0389 (I > 2σ(I)) and wR2 ) 0.0607.
(8) Dewar, M. J. S. The Molecular Orbital Theory of Organic Chemistry;
McGraw-Hill: New York, 1969; p 199.
(4) (a) Pugh, C.; Percec, V. J. Polym. Sci. A Polym. Chem. 1990, 28, 1101.
(b) Sonogashira, K.; Yatake, T.; Tohda, Y.; Takahashi, S.; Nagihara, N. Chem.
Commun. 1977, 291.
(5) The remaining 29% is mostly recovered starting material 1.
(6) Full chracterization (1H NMR, 13C NMR, UV-vis, MS, IR, M.P.) for
2a and 3a is included in the Supporting Information.
10.1021/ja002329q CCC: $20.00 © 2001 American Chemical Society
Published on Web 12/19/2000