Palladium-catalyzed naphthylation of acenaphthylene

Article abstract of DOI:10.1055/s-2007-970785

A bisnaphthyl-substituted acenaphthylene is synthesized via two independent two-step procedures, Pd-catalyzed and classically with Grignard reagents. The subsequent dehydrocyclization stops after the first carbon-carbon bond formation, leading to an octacyclic π-system as the main product. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2007-970785

LETTER
897
Palladium-Catalyzed Naphthylation of Acenaphthylene
P
d-Catalyze
d
Nap
e
o
r
f
A
cena
a
phthylene ld Dyker,* Klaus Merz, Iris M. Oppel, Enrico Muth
Fakultät Chemie, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
Fax +49(234)3214353; E-mail: Gerald.Dyker@rub.de
Received 1 December 2006
Dedicated to R. F. Heck on the occasion of his 75th birthday
Abstract: A bisnaphthyl-substituted acenaphthylene is synthesized
via two independent two-step procedures, Pd-catalyzed and classi-
cally with Grignard reagents. The subsequent dehydrocyclization
stops after the first carbon–carbon bond formation, leading to an oc-
tacyclic p-system as the main product.
Key words: palladium, Heck reaction, polycyclic aromatic, hydro-
carbons, annulated cyclopentadienes
5
4
The discovery of the fullerenes has motivated numerous
6
studies of the synthesis and the properties of polycyclic
Figure 1 Additional products from the Pd-catalyzed naphthylation
of acenaphthylene (2, 1 mmol) with 1-bromonaphthalene (4 mmol).
Reagents and conditions: 5 mol% Pd(OAc)2, 20 mol% P(t-Bu)3,
Cs2CO3, DMF, 140 °C, 2 d.
aromatic hydrocarbons with integrated five-membered
carbocyles, thus representing partial structures of these
nanospheres.1–3 Our palladium-catalyzed single-step syn-
theses of the mononaphthyl-substituted acenaphthylene 14
and of the strained hexacyclic hydrocarbon
acenaphth[1,2-a]acenaphthylene (3) with two annulated
pentagons (Scheme 1)4 prompted us to investigate the
naphthylation of acenaphthylene (2) in detail, targeting
for the bisnaphthylacenaphthylene 5, as an interesting
candidate for oxidative ring-closing reactions.5
Br
H
Pd Ar
Ar
Ar
Pd Ar
– Pd0
+ ArPdBr
– HBr
5
1
Ar = 1-naphthyl
7
8
Scheme 2 A Heck-type reaction without carbopalladation step as
mechanistic rationale.
a
b
The target molecule 5 was obtained with 19% yield, a re-
markable result, since the intermolecular Heck reaction is
known to be sensitive towards steric hindrance. In addi-
tion, the stereochemical requirements of the standard
mechanism for the Heck reaction – involving syn-carbo-
metallation and syn-b-hydrogen elimination – obviously
are not in accord with the formation of 5, and already for
the formation of 1. In both cases we assume that the elec-
trophilic attack of the aryl-Pd species does not lead to a
carbometalation step but to the formation of an intermedi-
ary benzyl cation 7 with subsequent elimination and inter-
mediary aryl vinyl palladium complex 8 (Scheme 2) as
suggested earlier in a review on palladacycles.7
In the 1H NMR and 13C NMR spectra of 5, a double set of
signals of a 1:1 mixture of rotamers was registered; this
was in agreement with our PM3 calculation, which esti-
mated the rotational barrier to about 20 kcal/mol. In addi-
tion, this calculation confirms our result, that the rotamers
are not isolable by flash chromatography at room temper-
ature, in contrast to the rotamers of the sterically some-
what more hindered bisnaphthylphenanthrene8 (rotational
barrier about 30 kcal/mol). However, by crystallizing 5
70%
42%
1
2
3
Scheme
1
a) 1-Iodonaphthalene, b) 1,8-diiodonaphthalene.
Reagents and conditions: 5 mol% Pd(OAc)2, K2CO3, DMF, 100 °C,
3 d.
Acenaphthylene (2) was arylated on a 1 mmol scale with
an excess of 1-bromonaphthalene in the presence of palla-
dium acetate as precatalyst under the optimized reaction
conditions outlined in Figure 1, which had been success-
fully applied previously for the arylation of cyclopenta-
dienes.6 We were able to isolate four different products by
flash chromatography: the monoarylation product 1 with
42% yield and the Ullmann coupling product 44 from ex-
cess bromonaphthalene, as anticipated.
SYNLETT 2007, No. 6, pp 0897–0900
Advanced online publication: 26.03.2007
DOI: 10.1055/s-2007-970785; Art ID: S19306ST
© Georg Thieme Verlag Stuttgart · New York
0
3.
0
4.
2
0
0
7

898
G. Dyker et al.
LETTER
out of a pentane solution, exclusively the chiral rotamer
trans-5 (Figure 2)was obtained as single crystals, obvi-
ously being favored in the centrosymmetric crystal lattice
with the space group P21/n.9
Byproduct 6 was identified by X-ray crystal-structure
analysis (Figure 3). The mechanistic rationale10 for the
domino process to 6 involves carbopalladation, cyclomet-
alation and even retro-carbopalladation steps with the
acenaphthylene moiety as template for C–C-coupling pro-
cesses, closely related to Heck-type reactions at the nor-
bornene moiety, which have been convincingly explained
and preparatively utilized by Catellani et al.11
10 (76%)
a
b
HO
OH
5
78%
9
11 (22%)
Scheme 3 Independent access to 5 and subsequent cyclodehydra-
tion. Reagents and conditions: a) MeSiCl3, NaI, MeCN, 3 h, r.t.;
b) CuCl2, AlCl3, CS2, 5 min, r.t.
Figure 2 Structure of the chiral rotamer trans-5 in the crystal.9
Figure 4 Structure of rearrangement product 11 in the crystal.9
Therefore this procedure is somewhat superior to the one-
step transformation of 9 to 10 in superacidic medium, re-
ported to give a 39% yield.15 In addition, we isolated spi-
rocycle 11 (Figure 4) as byproduct and confirmed its
structure by X-ray crystal analysis. While details of the
mechanism of its formation have yet to be revealed, rear-
rangement product 11 is about 19 kcal/mol thermodynam-
Figure 3 Structure of domino product 6 in the crystal.9
ically favored to
calculations (PM3).
5 according to semiempirical
As an independent access to the bisnaphthyl acenaphthyl-
ene 5 we successfully reduced diol 912 with sodium io-
dide/trichloromethyl silane13 in acetonitrile (Scheme 3).
Subsequent dehydrocyclization14 with AlCl3/CuCl2 gave
the octacyclic p-system 10 in 59% yield (over two steps).
The Pd-catalyzed synthesis of the bisnaphthyl-substituted
acenaphthylene 5 is another example for the capacity of
this type of reactions for the arylation in sterically hin-
dered positions, closely related to the one-step synthesis
Synlett 2007, No. 6, 897–900 © Thieme Stuttgart · New York

LETTER
Pd-Catalyzed Naphthylation of Acenaphthylene
899
of pentakisnaphthyl cyclopentadiene.6 The dehydrocy-
clization of 5 under moderate conditions stops after one
C–C bond formation; further cyclization steps would
cause a curvature, certainly requiring higher activation en-
ergies.
(40 mL) each. The organic layer was treated with an aq Na2S2O3
solution, washed with brine, dried with MgSO4 and concentrated in
vacuo. Flash chromatography of the residue (silica, PE–MTBE, 2:1)
gave 631 mg (78%) of 5 orange crystals with mp 268–270 °C.
Acenaphthyleno[1,2-i]picene (10) and 13H-Spiro-[acenaph-
then-1,13¢-dibenzo[a,i]fluorene] (11)
CuCl2 (269 mg, 2.00 mmol), AlCl3 (267 mg, 2.00 mmol), and the
disubstituted acenaphthylene (5, 404 mg 1.00 mmol) in CS2 (200
mL) were stirred under argon at r.t. for 5 min. Then, EtOH (200 mL)
was added, the resulting suspension was filtered and the residue was
extracted with EtOAc (100 mL). The combined solution was con-
centrated and the crude product mixture separated by flash chroma-
tography; TLC (silica, PE–MTBE 2:1); Rf = 0.12 (11), 0.10 (10),
0.00). First fraction: spirocycle 11 (89 mg 22%) as slightly yellow
crystals with mp 218 °C. 1H NMR (400 MHz, CDCl3): d = 4.19 (s,
2 H, H-2), 6.51 (d, J = 7.0 Hz, 1 H, H-8), 6.82 (d, J = 8.5 Hz, 2 H,
H-1¢), 6.99 (ddd, J = 1.5, 8.5 Hz, 2 H, H-2¢), 7.20 (dd, J = 7.0 Hz, 1
H, H-7), 7.27 (ddd, J = 1.5, 8.5 Hz, 2 H, H-3¢), 7.64 (d, J = 6.5 Hz,
1 H, H-3), 7.70 (d, J = 8.0 Hz, 1 H, H-6), 7.76 (dd, J = 7.0 Hz, 1 H,
H-4), 7.87 (d, J = 8.5 Hz, 2 H, H-4¢), 7.90 (d, J = 6.5 Hz, 1 H, H-5),
NMR spectroscopic data were recorded either at a Bruker DPX 200
(200 MHz) or at a Bruker DPX 400 (400 MHz). Mass spectrosco-
metric data were recorded on a VG Instruments Autospec mass
spectrometer.
Pd-Catalyzed Arylation of Acenaphthylene (2) with 1-Bromo-
naphthalene (3)
A mixture of acenaphthylene (2, 152 mg, 1.00 mmol), 1-bro-
monaphthalene (828 mg, 4.00 mmol), Cs2CO3 (1.30 g, 4.00 mmol),
Pd(OAc)2 (12 mg, 50 mmol), and tris-tert-butylphosphane (41 mg,
200 mmol) in anhyd DMF (10 mL) were stirred for 2 d at 140 °C un-
der argon in a screw-capped flask. The reaction mixture was diluted
with of EtOAc (90 mL) and acidified with PTSA monohydrate
(2.28 g, 12.0 mmol). After filtration through a pad of silica (4 g) the
organic phase was extracted three times with H2O (50 mL), dried
with Na2SO4 and the solvent was removed by rotatory evaporation.
TLC of the crude product: silica, PE–MTBE (2:1), Rf = 0.35 (4),
0.28 (1), 0.18 (5), 0.16 (6), 0.00. The products were separated by
flash chromatography and dried in vacuo (0.2 mbar, 50 °C); 1st frac-
tion: 1,1¢-binaphthyl 4 as colorless crystals (290 mg, 57% based on
the amount of aryl bromide) with mp 159 °C; 2nd fraction: the
monoarylated product 1 (117 mg, 42%) as yellow crystals with mp
92 °C; 3rd fraction: the bisarylated product 5 (77 mg, 19%) as or-
ange crystals with mp 268–270 °C.1H NMR (400 MHz, CDCl3,
25 °C, double set of signals): d = 7.09–7.13 (m, 1 H), 7.22–7.24 (m,
2 H), 7.30–7.39 (m, 4 H), 7.44–7.57 (m, 5 H), 7.70–7.76 (m, 3 H),
7.84 (d, J = 8.0 Hz, 1 H), 7.89 (d, J = 8.5 Hz, 1 H), 7.90 (d, J = 8.0
7.95 (d, J = 8.5 Hz, 2 H, H-5¢), 8.07 (d, J = 8.5 Hz, 2 H, H-6¢). 13
C
NMR (100 MHz, CDCl3): d = 43.88 (t, C-2), 63.34 (s, C-1), 118.45
(d, C-6¢), 119.60 (d, C-8), 121.03 (d, C-3), 122.95 (d, C-1¢), 123.72
(d, C-6), 123.77 (d, C-5), 124.99 (d, C-3¢), 126.80 (d, C-2¢), 128.50
(d, C-7), 128.61 (d, C-4), 129.14 (s, C-13b¢), 129.53 (d, C-5¢),
129.58 (d, C-4¢), 132.25 (s, C-5a), 133.99 (s, C-4a¢), 138.21 (s, C-
6a¢), 139.85 (s, C-8b), 143.51 (s, C-2a), 148.70 (s, C-13a¢), 149.54
(s, C-8a). UV/Vis (MeCN): l (log e) = 220 (4.10), 226 (4.11), 268
(4.24), 282 (3.90), 292 (3.74), 332 (3.42) nm. MS–FAB: m/z (%):
406 (6), 405 (36), 404 (100) [M+], 329 (5), 307 (16), 289 (9), 176
(18), 154 (74), 136 (54). Anal. Calcd for C32H20 (404.50): C, 95.02;
H, 4.98. Found: C, 94.76; H, 4.97. Second fraction: the angularly
fused aromatic hydrocarbon 10 (305 mg, 76%) as orange crystals
with mp 309 °C (lit.15: mp 306–310 °C).
Hz, 1 H), 8.07 (d, J = 8.5 Hz, 1 H), 8.10 (d, J = 8.0 Hz, 1 H). 13
C
NMR (100 MHz, CDCl3, 25 °C, double set of signals): d = 124.55
(d), 124.63 (d), 125.23 (d), 125.48 (d), 125.65 (d), 125.70 (d),
125.80 (d), 126.87 (d), 127.18 (d), 127.42 (d), 127.46 (d), 127.92
(d), 127.97 (d), 128.06 (d), 128.13 (d), 128.26 (d), 128.55 (d),
132.19 (s), 133.09 (s), 133.18 (s), 133.49 (s), 133.78 (s), 133.84 (s),
139.39 (s), 140.27 (s), 141.38 (s), 141.44 (s). UV/Vis (MeCN):
l (log e) = 220 (4.23), 308 (3.46) nm. MS–FAB: m/z (%) = 406 (7),
405 (36), 404 (100), 276 (4). Anal. Calcd for C32H20 (404.50): C,
95.02; H, 4.98. Found: C, 94.66; H, 5.04; 4th fraction: the 2,2¢-bis-
naphthyl derivative 6 (20 mg, 5%) as dark yellow crystals with mp
279 °C. 1H NMR (400 MHz, CDCl3, 25 °C): d = 6.78 (s, 1 H), 7.27
(d, J = 7.0 Hz, 1 H), 7.32–7.40 (m, 5 H), 7.44–7.52 (m, 4 H), 7.63–
7.69 (m, 2 H), 7.73 (d, J = 8.0 Hz, 1 H), 7.75 (d, J = 8.5 Hz, 2 H),
7.87 (s, 1 H), 7.94 (d, J = 8.5 Hz, 1 H), 7.96 (d, J = 8.5 Hz, 1 H),
8.00 (d, J = 8.5 Hz, 1 H). 13C NMR (100 MHz, CDCl3, 25 °C):
d = 124.01 (d), 124.23 (d), 125.74 (d), 125.93 (d), 126.04 (d),
126.29 (d), 127.04 (d), 127.17 (d), 127.33 (d), 127.45 (d), 127.63
(d), 127.66 (d), 127.83 (d), 128.03 (d), 128.06 (d), 128.10 (d),
128.23 (d), 128.30 (s), 128.39 (d), 128.61 (s), 128.83 (d), 130.66
(d), 131.92 (s), 132.16 (s), 133.02 (s), 133.35 (s), 133.49 (s), 139.27
(s), 139.60 (s), 140.23 (s), 141.24 (s), 141.55(s). UV/Vis (MeCN):
l (log e) = 220 (4.19), 224 (4.18), 296 (3.34), 328 (3.36) nm. MS–
FAB: m/z (%) = 406 (8), 405 (35), 404 (100), 276 (4). Anal. Calcd
for C32H20 (404.50): C, 95.02; H, 4.98. Found: C, 94.78; H, 4.53.
References and Notes
(1) Scott, L. T.; Hashemi, M. M.; Meyer, D. T.; Warren, H. B.
J. Am. Chem. Soc. 1991, 113, 7082.
(2) Stoddart, M. W.; Brownie, J. H.; Baird, M. C.; Schmider, H.
L. J. Organomet. Chem. 2005, 690, 3440.
(3) Sakurai, H.; Daiko, T.; Sakane, H.; Amaya, T.; Hirao, T. J.
Am. Chem. Soc. 2005, 127, 11580.
(4) Dyker, G. J. Org. Chem. 1993, 58, 234.
(5) Waldvogel, S. R.; Mirk, D. In Handbook of C–H
Transformations; Wiley-VCH: Weinheim, 2005, 251–261.
(6) Dyker, G.; Heiermann, J.; Miura, M.; Pivsa-Art, S.; Satoh,
T.; Nomura, M. Chem. Eur. J. 2000, 6, 3426.
(7) Dyker, G. Chem. Ber./Recl. 1997, 130, 1567.
(8) Gundermann, K. D. Z. Naturforsch., B: Chem. Sci. 1992, 47,
1764.
(9) X-ray data for 5 were collected on a Bruker AXS-SMART
1000 (Mo Ka radiation). The structure was solved by direct
methods and refined by full matrix least squares using
SHELXTL-97 All non-hydrogen atoms were refined using
anisotropic thermal parameters.
Crystal Data for 5
T = 213(2) K, C32H20, M = 404.48, monoclinic space group
P21/n, a = 12.190(5) Å, b = 10.104(4) Å, c = 17.237(7) Å,
b = 102.484(9)°, V = 2072.9(15) Å3, Z = 4, DC = 1.296 g/
cm3, m = 0.073 mm–1, 2.35° < Q < 25.15°, reflections
collected/unique 10788/3646 [Rint = 0.0489], data/restraints/
parameters 3646/0/289, GOF 1.021, final R[I > 2s(I)]
R1 = 0.0416, wR2 (all data) = 0.1082, residual density 0.134
and –0.190 e A–3.
Independent Synthesis of 1,2-Dinaphthalen-1-yl-acenaphthyl-
ene (5)
To a solution of NaI (1.50 g, 1.00 mmol) in anhyd MeCN (20 mL)
MeSiCl3 (1.49 g, 1.00 mmol) and 1,2-dinaphthalen-1-yl-acenaph-
thylen-1,2-diol (12,12 877 mg, 2.00 mmol) were successively added
under stirring. After 3 h at r.t. the reaction mixture was poured onto
crushed ice (50 g), followed by threefold extraction with MTBE
Synlett 2007, No. 6, 897–900 © Thieme Stuttgart · New York

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G. Dyker et al.
LETTER
using SHELXTL-97 (G. M. Sheldrick, Universität
Crystal Data for 6
The crystals were of poor quality, twinned and weakly
diffracting. C32H20, M = 404.48, monoclinic space group
P21/c, a = 11.352(3) Å, b = 24.248(4) Å, c = 7.835(2) Å,
b = 96.80(2)°, V = 2141.4(8) Å3, Z = 4, T = 293(2) K,
m = 0.071 mm–1, 32624/3877/2025 reflections collected/
unique/observed, Rint = 0.1775, R1 = 0.1268, wR2 (all
data) = 0.2319, 290 parameters. All non-hydrogen atoms
calculated anisotropic; positions of the H atoms calculated
for idealized positions. The structure was solved and refined
using SHELXTL-97 (G. M. Sheldrick, Universität
Göttingen 1997).
Göttingen 1997).
X-ray data have been deposited at the Cambridge
Crystallographic Data Centre (deposition numbers CCDC-
611565 for 5, CCDC-614432 for 6 and CCDC-614433 for
11. Copies of the data can be obtained free of charge at
www.ccdc.cam.uk/data_request/cif or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ [fax: +44 (1223)336033; e-mail:
deposit@ccdc.cam.ac.uk].
(10) Muth, E. Ph.D. Thesis; Bochum University: Germany, 2004.
(11) Catellani, M.; Motti, E. New J. Chem. 1998, 22, 759.
(12) Alder, R. W.; Colclough, D.; Grams, F.; Orpen, A. G.
Tetrahedron 1990, 46, 7933.
(13) Olah, G. A.; Husain, A.; Gupta, B. G. B.; Narang, S. C.
Angew. Chem. 1981, 93, 705.
(14) Simpson, C. D.; Brand, J. D.; Berresheim, A. J.; Przybilla,
L.; Räder, H. J.; Müllen, K. Chem. Eur. J. 2002, 8, 1424.
(15) Klumpp, D. A.; Baek, D. N.; Prakash, G. K. S.; Olah, G. A.
J. Org. Chem. 1997, 62, 6666.
Crystal Data for 11
Again, the crystals were of poor quality and weakly
diffracting. C32H20, M = 404.48, tetragonal space group I–4,
a = 20.673(2) Å, c = 10.448(1) Å, V = 4465.4(9) Å3, Z = 8,
T = 293(2) K, m = 0.068 mm–1, 2380/1798/934 reflections
collected/unique/observed, Rint = 0.0670, R1 = 0.1283, wR2
(all data) = 0.3307, 289 parameters. All non-hydrogen atoms
calculated anisotropic; positions of the H atoms calculated
for idealized positions. The structure was solved and refined
Synlett 2007, No. 6, 897–900 © Thieme Stuttgart · New York

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