Palladium-catalyzed [3+2] cycloaddition reaction of (diarylmethylene) cyclopropa[b]naphthalenes with arynes: An efficient synthesis of 11-(diarylmethylene)-11H-benzo[b]fluorenes

Article abstract of DOI:10.1002/ejoc.201100035

A Pd-catalyzed [3+2] cycloaddition reaction of (diarylmethylene) cyclopropa[b]naphthalenes with arynes provided an efficient approach for the synthesis of 11-(diarylmethylene)-11H-benzo[b]fluorenes with good to excellent yields under mild conditions. From

Full text of DOI:10.1002/ejoc.201100035

FULL PAPER
DOI: 10.1002/ejoc.201100035
Palladium-Catalyzed [3+2] Cycloaddition Reaction of (Diarylmethylene)-
cyclopropa[b]naphthalenes with Arynes: An Efficient Synthesis of
11-(Diarylmethylene)-11H-benzo[b]fluorenes
Ying Lin,[a] Luling Wu,*[a] and Xian Huang[a][‡]
Keywords: Arynes / Palladium / Cycloaddition
A Pd-catalyzed [3+2] cycloaddition reaction of (diarylmethyl-
ene)cyclopropa[b]naphthalenes with arynes provided an ef-
ficient approach for the synthesis of 11-(diarylmethylene)-
11H-benzo[b]fluorenes with good to excellent yields under
mild conditions.
tive palladium-catalyzed [3+2] cycloaddition reaction of
(diarylmethylene)cyclopropa[b]naphthalenes 1 with alkenes
and alkynes in 2008, which provided an efficient method
for the synthesis of 1(3)-alkylidene-2,3-dihydro-1H-cy-
clopenta[b]naphthalenes and 1-alkylidene-1H-cyclopenta-
[b]naphthalenes under mild conditions[8] (Scheme 1).
Introduction
The chemistry of polycyclic aromatic hydrocarbons
(PAHs) has become a field of increasing interest during the
past decades due to their unique properties in material sci-
ence.[1] For example, the charge transport properties of
PAHs make them potential candidates for organic optoelec-
tronic devices such as light-emitting diodes, field-effect
transistors, photovoltaics, acenes, nanographenes and dis-
cotic liquid crystals.[2] In addition, PAHs with benzo[b]fluo-
rene skeletons are also of considerable interest due to their
applications as bioactive compounds and synthetic interme-
diates in organic synthesis.[3] Thus, much attention has been
focused on the synthesis of benzo[b]fluorenes in recent
years. Although some known methods provide reliable
routes, most of them require multiple steps or harsh condi-
tions.[4] Thus, there is high demand for development of ef-
ficient methods for their synthesis.
During our recent systematic study of methylenecyclo-
propane (MCP) chemistry,[5] we became interested in the
chemistry of the analogous (diarylmethylene)cyclopropa-
[b]naphthalenes. Because of their unusual structure, which
contains a triafulvene, a [3]radialene, and a cycloproparene,
they have attracted much attention from physical, theoreti-
cal, and synthetic viewpoints.[6] However, for transition-
metal-mediated reactions, only one example of the reactions
of (diarylmethylene)cyclopropa[b]naphthalenes 1 with stoi-
chiometric rhodium(I) and platinum(0) reagents has been
reported.[7] We first reported a catalytic, highly regioselec-
Scheme 1. Previous work and our proposal.
Arynes are highly reactive intermediates.[9] Since the in-
novation of F–-induced in-situ generation of aryne from 2-
(trimethylsilyl)phenyl triflate in 1983,[10] the application of
arynes under mild conditions in organic synthesis has at-
tracted increasing attention.
The transition-metal-catalyzed reactions of arynes, espe-
cially the transition-metal-catalyzed annulation of arynes,
have proved to be very useful in organic synthesis.[11] It was
reported that arynes readily undergo cyclotrimerization un-
der palladium catalysis to form polycyclic aromatic hydro-
carbons.[12] Related studies demonstrated that in the pres-
ence of transition-metal catalysts, cocyclizations of arynes
could be performed with a variety of alkynes,[13] diynes,[14]
[17]
allenes,[15] allyl derivatives,[16] CO2
and CO.[18] To the
[a] Department of Chemistry, Zhejiang University (Xixi Campus),
Hangzhou 310028, China
best of our knowledge, there are few reports of the cocycli-
zation of arynes and methylenecyclopropanes.[19] In this pa-
per, we wish to report a highly efficient palladium-catalyzed
[3+2] cycloaddition reaction of (diarylmethylene)cyclo-
propa[b]naphthalenes with arynes, providing an easy access
to 11-(diarylmethylene)-11H-benzo[b]fluorenes in good to
excellent yields under mild conditions.
Fax: +86-571-88807077
E-mail: wululing@zju.edu.cn
[‡] Professor Huang passed away on March 6, 2010. He was fully
in charge of this project. Professor Luling Wu is helping to fin-
ish all the projects with assistance from Professor Shengming
Ma.
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201100035.
Eur. J. Org. Chem. 2011, 2993–3000
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Y. Lin, L. Wu, X. Huang
FULL PAPER
Results and Discussion
We first employed 1-(diphenylmethylene)-1H-cyclopropa-
[b]naphthalene (1a)[20] to react with 2.0 equiv. of 2-(trimeth-
ylsilyl)phenyl triflate 2a in the presence of 5 mol-% of
Pd(dba)2 and 4.0 equiv. of CsF in MeCN at 25 °C. The de-
sired [3+2] cycloaddition product 3a was obtained in 88%
yield (entry 2, Table 1). The structure of the product 3a was
confirmed by X-ray diffraction studies (Figure 1). The reac-
tion was further investigated to optimize the reaction condi-
tions, and the results are summarized in Table 1. We found
that Pd2(dba)3·CHCl3 was almost as effective as Pd(dba)2
in furnishing 3a, while the use of PdCl2 gave an inferior
yield (entries 3 and 4, Table 1). When we used Pd(PPh3)4 as
the catalyst, the reaction was complete within 3 h, and the
yield of 3a was improved to 98% (entry 5, Table 1). Gratify-
ingly, upon using a combination of Pd(dba)2 and PPh3, we
could obtain the expected product 3a within 1.5 h with the
same excellent yield (entry 6, Table 1). However, when we
decreased the amount of Pd(dba)2 to 1 mol-%, the starting
material 1a was not completely consumed (entry 7, Table 1).
When we reduced the amount of 2a from 2.0 equiv. to
1.2 equiv., the yield dropped to 75% (entry 8, Table 1).
Among the solvents examined, MeCN was the best (entries
6 and 9–10, Table 1). Therefore, the reaction in the presence
of 5 mol-% of Pd(dba)2, 10 mol-% of PPh3 and 4 equiv. of
CsF in MeCN at 25 °C was established as standard condi-
tions to explore the reaction scope (entry 6, Table 1). Here
it should also be noted that the reaction did not occur in
the absence of the palladium catalyst (entry 1, Table 1).
Figure 1. ORTEP representation of 3a.
1b–1h, which bear substituted phenyl rings as the Ar group
in 1, all efficiently underwent annulation to generate the
corresponding products in high to excellent yields (entries
2–8, Table 2): The reaction of 1b with 2a gave a 98% yield
of the desired compound 3b (entry 2, Table 2). (Diarylmeth-
ylene)cyclopropa[b]naphthalenes with m-tolyl (1c) and o-
tolyl (1d) as the aryl groups gave their corresponding prod-
ucts in 84 and 85% yields, respectively (entries 3 and 4,
Table 2). The reduced yield may result from the steric hin-
drance of the methyl groups. Substrate 1e, which incorpo-
rated two electron-donating p-methoxy groups, gave a yield
of 93% (entry 5, Table 2). Electron-withdrawing groups
such as fluorine (1f) were tolerated in the reaction to give
3f in 96% yield (entry 6, Table 2). The substrate 1i, upon
reacting with the aryne precursor 2a, gave the desired com-
pounds 3i and 3j as a 1:1 mixture of inseparable isomers in
an 81% overall yield (entry 9, Table 2).
Table 1. Optimization of reaction conditions for the Pd-catalyzed
[3+2] cycloaddition reaction of 1-(diphenylmethylene)-1H-cy-
clopropa[b]naphthalene (1a) with 2-(trimethylsilyl)phenyl triflate
(2a).[a]
Table 2. Pd-catalyzed [3+2] cycloaddition reaction of (diarylmeth-
ylene)cyclopropa[b]naphthalenes 1 with 2a.[a]
Entry Catalyst
1a/2a
Solvent
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
THF
Time Yield of 3a
[h]
[%][b]
1
2
3
4
5
6
7
8
9
10
–
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:1.2
1:2
1:2
24
1
1
0
88
87
Pd(dba)2
Pd2(dba)3·CHCl3
PdCl2
2.5
3
70
98
Pd(PPh3)4
Pd(dba)2/PPh3
Pd(dba)2/PPh3
Pd(dba)2/PPh3
Pd(dba)2/PPh3
Pd(dba)2/PPh3
1.5
24
2
98
40[c]
75
24
12
12
MeCN/toluene
85[d]
[a] The reactions were conducted with 1a (0.2 mmol), CsF
(4.0 equiv.), catalyst (5 mol-%), and ligand (10 mol-%) in 5 mL of
solvent. [b] Isolated yield. [c] 1 mol-% of catalyst and 2 mol-% of
ligand were used, and 32% of 1a was recovered. [d] The reaction
was conducted in MeCN (2.5 mL) and toluene (2.5 mL).
[a] The reactions were conducted with 1 (0.2 mmol), 2a (2.0 equiv.),
Under the optimized reaction conditions, we next exam-
ined the scope of this reaction with various substrates. In
CsF (4.0 equiv.), Pd(dba)2 (5 mol-%), and PPh3 (10 mol-%) in
CH3CN (5 mL) at room temp. [b] Isolated yield. [c] The ratio of
1
addition to 1a, (diarylmethylene)cyclopropa[b]naphthalenes products was determined by H NMR spectral analysis.
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Cycloaddition of Cyclopropa[b]naphthalenes with Arynes
Scheme 2. The synthetic utilities of 3g and 3h.
The reactions of substrates bearing other halogen atoms used to react with 1a, a mixture of inseparable isomers 3n
(1g and 1h) with 2a also proceeded smoothly to afford ex- and 3o was obtained in an 92% overall yield, with an iso-
cellent yields of the corresponding compounds 3g and 3h, meric ratio of 1:1 (entry 4, Table 3Ͻxtabr3 pos="x22"Ͼ).
providing opportunities for further elaboration (entries 7
On the basis of the known organopalladium chemistry
and 8, Table 2). Our further experiments have applied the of arynes and our previous work on Pd-catalyzed [3+2] cy-
HBF4 salt of a monophosphane ligand, that is, dicyclo- cloaddition reactions of (diarylmethylene)cyclopropa[b]-
hexyl-(2,4,6-trimethoxyphenyl)phosphane, to the Suzuki naphthalenes with alkenes and alkynes,[8] a possible mecha-
coupling reaction of 3g and 3h with different organo- nism for the reaction of 1 with aryne precursors 2 catalyzed
boronic acids in high yields.[21] Furthermore, the combina- by Pd(dba)2 and PPh3 is shown in (Scheme 3). First, oxidat-
tion of PdCl2(PPh3)2 and AuCl(PPh3) made a unique cata- ive addition of palladium(0) with the highly strained three-
lytic system that allowed Sonogashira-type cross-coupling membered ring in (diarylmethylene)cyclopropa[b]naphtha-
of 3h with 1-ethynylbenzene to afford 4d in a yield of lenes 1 leads to the palladacyclobutene compound A. Sub-
90%.[22] The reaction of 3h with hex-1-yne afforded 4e in sequently, the insertion reaction of A with aryne B, which
86% yield by using an efficient catalytic system of is generated from the triflate 2 in the presence of the fluo-
PdCl2(PPh3)2 and CuI in piperidine[23] (Scheme 2).
ride source, gives the palladacyclohexene compound C or
We further examined the reaction of 1a by using a variety D. Then, reductive elimination gives the [3+2] cycloadduct
of substituted aryne precursors. Treatment of aryne precur- 3, and regenerates the catalytically active Pd0 catalyst.
sor 2b with 1a gave the targeted product 11-(diphenylmeth-
ylene)-2,3-dimethyl-11H-benzo[b]fluorene (3k) smoothly in
a 90% isolated yield (entry 1, Table 3). When 2c and 2d
were used as aryne precursors under the established reac-
Conclusions
tion conditions, the reaction led to lower yields, and a large
amount of an unknown mixture was detected. Thus, in or-
der to optimize the reaction further, a mixture of the two
In conclusion, we have disclosed a Pd-catalyzed [3+2] cy-
substrates (1a and aryne precursor) in MeCN was added cloaddition reaction of (diarylmethylene)cyclopropa[b]-
slowly to the reaction system by a micro infusion pump naphthalenes 1 with arynes, providing an efficient method
over 1 h at 80 °C. To our delight, the yields of 3l and 3m for the synthesis of 11-(diarylmethylene)-11H-benzo[b]fluo-
were dramatically increased to 70% and 85%, respectively renes 3 in good to excellent yields under mild conditions.
(entries 2 and 3, Table 3). When an unsymmetrical aryne Further studies on the reaction mechanism and the scope
precursor 2-methyl-6-(trimethylsilyl)phenyl triflate 2e was of the reaction are in progress.
Eur. J. Org. Chem. 2011, 2993–3000
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Y. Lin, L. Wu, X. Huang
FULL PAPER
Petroleum ether refers to the fraction with a boiling range of 60–
90 °C. Unless otherwise specified, 1H NMR (400 MHz, CDCl3)
and 13C NMR (100 MHz, CDCl3) spectra were measured in CDCl3
with TMS as the internal standard. Chemical shifts are expressed in
ppm and J values are given in Hz. Melting points were uncorrected.
Starting materials: 1a–1i[20] and 2a–2e[24] were prepared following
the known procedures.
Table 3. Pd-catalyzed [3+2] cycloaddition reaction of 1a with sub-
stituted aryne precursor 2.[a]
Synthesis of 11-(Diphenylmethylene)-11H-benzo[b]fluorene (3a) as a
Representative General Procedure for the Preparation of 11-(Diaryl-
methylene)-11H-benzo[b]fluorenes 3a–3k, 3n and 3o: A rubber-
capped Schlenk vessel containing CsF (121 mg, 0.8 mmol) was
flame-dried under vacuum and backfilled with nitrogen three times,
then 1-(diphenylmethylene)-1H-cyclopropa[b]naphthalene (1a)
(61 mg, 0.2 mmol), PPh3 (6 mg, 0.02 mmol), 2-(trimethylsilyl)-
phenyl triflate (2a) (119 mg, 0.4 mmol), and dry MeCN (2 mL)
were added sequentially to the Schlenk vessel. After being stirred
for about 1 min at room temperature, Pd(dba)2 (6 mg, 0.01 mmol),
and another portion of dry MeCN (3 mL) were added sequentially
in one portion. The resulting mixture was then allowed to stir at
room temperature. After 1.5 h, the reaction was complete as moni-
tored by TLC. The reaction mixture was filtered through a shot
pad of silica gel. The filtrate was concentrated under reduced pres-
sure, and the residue was purified by silica gel chromatography (pe-
troleum ether) to afford 3a (74 mg, 98%) as a yellow solid; m.p.
208–210 °C (petroleum ether). 1H NMR (400 MHz, CDCl3, 25 °C):
δ = 8.05 (s, 1 H), 7.84–7.78 (m, 2 H), 7.44–7.34 (m, 12 H), 7.28–
7.24 (m, 2 H), 7.00–6.94 (m, 2 H), 6.69 (d, J = 8.0 Hz, 1 H) ppm.
13C NMR (100 MHz, CDCl3, 25 °C): δ = 144.1, 143.3, 143.0, 140.2,
140.1, 138.5, 137.3, 133.6, 133.1, 132.7, 129.5, 129.4, 129.1, 129.0,
128.9, 128.1, 128.0, 127.9, 127.8, 127.1, 126.0, 125.1, 125.0, 124.4,
120.0, 117.0 ppm. MS: m/z (%) = 380 (100) [M+]. IR (neat): ν =
˜
3054, 1592, 1493, 1465, 1436, 1264, 1073, 1026, 884 cm–1. HRMS:
calcd. for C30H20 (M+) 380.1565; found 380.1563.
[a] Unless otherwise specified, the reactions were conducted with
1a (0.2 mmol), 2 (2.0 equiv.), CsF (4.0 equiv.), Pd(dba)2 (5 mol-%),
and PPh3 (10 mol-%) in 5 mL of CH3CN at room temp. [b] Isolated
yield. [c] A mixture of 1 and 2 was added by a micro infusion pump
The following compounds were prepared according to this pro-
cedure.
11-[Bis(p-tolyl)methylene]-11H-benzo[b]fluorene (3b): The reaction
of 1b (66 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), PPh3 (6 mg,
0.02 mmol), CsF (121 mg, 0.8 mmol), and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded 3b (80 mg, 98%) as a yellow
solid (eluent: petroleum ether); m.p. 236–238 °C (petroleum ether).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.07 (s, 1 H), 7.85–7.79
(m, 2 H), 7.40–7.19 (m, 12 H), 7.13 (s, 1 H), 6.99 (t, J = 7.6 Hz, 1
H), 6.80 (d, J = 8.0 Hz, 1 H), 2.46 (s, 3 H), 2.41 (s, 3 H) ppm. 13C
NMR (100 MHz, CDCl3, 25 °C): δ = 144.5, 140.5, 140.4, 140.3,
140.0, 138.5, 138.0, 137.9, 137.6, 133.1, 133.0, 132.7, 129.8, 129.7,
129.6, 129.5, 129.1, 127.8, 127.6, 127.0, 125.9, 125.0, 124.9, 124.1,
120.0, 116.9 ppm. MS: m/z (%) = 408 (67) [M+], 55 (100). IR (neat):
1
over 1 h at 80 °C. [d] The ratio of products was determined by H
NMR spectral analysis.
ν = 2916, 1908, 1592, 1502, 1464, 1427, 1272, 1182, 1109, 1019,
˜
950, 887 cm–1. HRMS: calcd. for C32H24 (M+) 408.1878; found
408.1871.
11-[Bis(m-tolyl)methylene]-11H-benzo[b]fluorene (3c): The reaction
of 1c (66 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), PPh3 (6 mg,
0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded 3c (69 mg, 84%) as a yellow
solid (eluent: petroleum ether); m.p. 210–212 °C (petroleum ether).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.06 (s, 1 H), 7.85–7.79
(m, 2 H), 7.39–7.19 (m, 12 H), 7.01–6.69 (m, 2 H), 6.69 (d, J =
8.0 Hz, 1 H), 2.37–2.36 (m, 6 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 144.6, 143.2, 143.0, 140.2, 140.1, 138.8, 138.7,
138.7, 138.6, 138.6, 138.5, 137.4, 133.3, 133.1, 132.8, 129.8, 129.7,
129.1, 128.9, 128.8, 127.8, 127.7, 127.1, 126.5, 126.4, 126.0, 125.1,
Scheme 3. Proposed mechanism.
Experimental Section
General Experimental Procedures: All reactions were performed un-
der a N2 atmosphere. Dry solvents were distilled prior to use: THF,
toluene and dioxane were distilled from sodium–benzophenone;
MeCN was distilled from CaH2; DMF was distilled from MgSO4. 124.5, 120.0, 116.9, 21.5, 21.4 ppm. MS: m/z (%) = 408 (100) [M+].
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Eur. J. Org. Chem. 2011, 2993–3000

Cycloaddition of Cyclopropa[b]naphthalenes with Arynes
IR (neat): ν = 2982, 1595, 1429, 1268, 1165, 1050, 889 cm–1. (%) = 448 (35,35Cl, 100) [M+], 450 (35,37Cl, 73) [M+], 452 (37,37Cl,
˜
HRMS: calcd. for C32H24 (M+) 408.1878; found 408.1875.
16) [M+]. IR (neat): ν = 2922, 1586, 1484, 1428, 1395, 1270, 1089,
˜
1013, 957, 891 cm–1. HRMS: calcd. for C30H1835Cl2 (M+) 448.0786;
found 448.0778.
11-[Bis(o-tolyl)methylene]-11H-benzo[b]fluorene (3d): The reaction
of 1d (66 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), PPh3 (6 mg,
0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded of 3d (70 mg, 85%) as a
yellow oil (eluent: petroleum ether). 1H NMR (500 MHz, [D6]-
DMSO, 80 °C): δ = 8.31 (s, 1 H), 7.98 (d, J = 7.0 Hz, 1 H), 7.89
(d, J = 8.5 Hz, 1 H), 7.44–7.21 (m, 12 H), 7.02 (t, J = 8.0 Hz, 1
H), 6.78 (s, 0.4 H), 6.71 (s, 0.6 H), 6.51 (d, J = 8.0 Hz, 0.4 H), 6.45
(d, J = 8.0 Hz, 0.6 H), 2.30 (s, 1.7 H), 2.29 (s, 1.7 H), 2.17 (s, 1.3
H), 2.16 (s, 1.3 H) ppm. 13C NMR (125 MHz, [D6]DMSO, 80 °C):
δ = 142.4, 142.4, 142.1, 141.5, 141.1, 140.5, 140.0, 139.8, 139.5,
138.3, 138.3, 137.1, 136.8, 136.4, 136.4, 135.3, 134.7, 134.5, 133.4,
133.3, 132.9, 132.9, 131.6, 131.5, 131.3, 131.2, 130.3, 129.1, 129.0,
128.9, 128.9, 128.7, 128.7, 128.6, 128.6, 128.4, 128.3, 128.2, 127.5,
127.3, 127.2, 127.1, 126.9, 126.9, 126.2, 126.2, 124.2, 123.9, 123.5,
123.2, 121.0, 118.0, 117.9, 20.2, 20.2, 20.1, 20.0 ppm. MS: m/z (%)
11-[Bis(4-bromophenyl)methylene]-11H-benzo[b]fluorene (3h): The
reaction of 1h (92 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), PPh3
(6 mg, 0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded 3h (101 mg, 94%) as a yel-
low solid (eluent: petroleum ether); m.p. 198–199 °C (petroleum
ether). 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.05 (s, 1 H), 7.84–
7.80 (m, 2 H), 7.59–7.23 (m, 12 H), 7.10 (s, 1 H), 7.02 (t, J = 7.6 Hz,
1 H), 6.76 (d, J = 8.0 Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 141.7, 141.4, 140.7, 140.4, 139.6, 138.4, 136.8, 134.6,
133.3, 132.7, 132.3, 132.2, 131.6, 131.5, 129.2, 128.4, 127.9, 127.3,
126.4, 125.5, 124.9, 124.4, 122.6, 122.6, 120.2, 117.3 ppm. MS: m/z
(%) = 536 (79,79Br, 50) [M+], 538 (79,81Br, 100) [M+], 540 (81,81Br,
53) [M+]. IR (neat): ν = 2910, 1576, 1482, 1390, 1273, 1069, 1008,
˜
882 cm–1. HRMS: calcd. for C30H1879Br2 (M+) 535.9775; found
535.9758.
= 408 (100) [M+]. IR (neat): ν = 3054, 2920, 1578, 1428, 1377,
˜
1264, 1114, 1035, 949, 886 cm–1. HRMS: calcd. for C32H24 (M+)
408.1878; found 408.1882.
(Z)-11-(1-Phenylethylidene)-11H-benzo[b]fluorene (3i) and (E)-11-
(1-Phenylethylidene)-11H-benzo[b]fluorene (3j): The reaction of 1i
(49 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), of PPh3 (6 mg,
0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded a mixture of 3i and 3j (1:1)
11-[Bis(4-methoxyphenyl)methylene]-11H-benzo[b]fluorene (3e): The
reaction of 1e (73 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), PPh3
(6 mg, 0.02 mmol), CsF (121 mg, 0.8 mmol), and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded 3e (82 mg, 93%) as a yellow
solid (eluent: petroleum ether/CH2Cl2 = 10:1); m.p. 238–239 °C
1
(52 mg, 81%) as a yellow oil (eluent: petroleum ether). H NMR
(400 MHz, CDCl3, 25 °C): δ = 8.32 (s, 1 H), 8.11 (s, 1 H), 8.01–
7.74 (m, 7 H), 7.49–7.17 (m, 19 H), 6.88 (t, J = 7.6 Hz, 1 H), 6.57
(s, 1 H), 6.30 (d, J = 8.0 Hz, 1 H), 2.80 (s, 3 H), 2.72 (s, 3 H) ppm.
1
(petroleum ether/CH2Cl2). H NMR (400 MHz, CDCl3, 25 °C): δ
= 8.08 (s, 1 H), 7.87–7.80 (m, 2 H), 7.45–7.24 (m, 9 H), 7.02–6.84
(m, 6 H), 3.88 (s, 3 H), 3.85 (s, 3 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 159.8, 159.7, 144.1, 140.7, 139.9, 138.5, 137.8,
135.9, 135.7, 132.9, 132.8, 131.7, 131.6, 129.1, 127.8, 127.4, 127.0,
125.8, 125.0, 124.7, 123.7, 120.0, 116.9, 114.2, 114.1, 55.4,
11-(Diphenylmethylene)-2,3-dimethyl-11H-benzo[b]fluorene
(3k):
The reaction of 1a (61 mg, 0.2 mmol), 2b (130 mg, 0.4 mmol), PPh3
(6 mg, 0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded 3k (73 mg, 90%) as a yellow
solid (eluent: petroleum ether); m.p. 220–222 °C (petroleum ether).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.00 (s, 1 H), 7.79 (d, J
= 8.4 Hz, 1 H), 7.61 (s, 1 H), 7.45–7.23 (m, 13 H), 6.89 (s, 1 H),
6.39 (s, 1 H), 2.30 (s, 3 H), 2.01 (s, 3 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 143.3, 143.2, 142.8, 138.9, 138.3, 138.2, 137.7,
136.8, 135.6, 133.7, 133.2, 132.5, 129.6, 129.5, 129.1, 128.9, 128.8,
128.0, 127.9, 127.7, 126.2, 125.9, 124.9, 124.3, 121.0, 116.3, 20.4,
55.3 ppm. MS: m/z (%) = 440 (100) [M+]. IR (neat): ν = 2919, 2849,
˜
1601, 1505, 1459, 1365, 1283, 1245, 1178, 1107, 1027, 892 cm–1.
HRMS: calcd. for C32H24O2 (M+) 440.1776; found 440.1781.
11-[Bis(4-fluorophenyl)methylene]-11H-benzo[b]fluorene (3f): The
reaction of 1f (68 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), PPh3
(6 mg, 0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded 3f (80 mg, 96%) as a yellow
solid (eluent: petroleum ether); m.p. 224–226 °C (petroleum ether).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.06 (s, 1 H), 7.85–7.80
(m, 2 H), 7.43–7.27 (m, 8 H), 7.17–7.07 (m, 5 H), 7.00 (t, J =
7.6 Hz, 1 H), 6.71 (d, J = 8.0 Hz, 1 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 162.8 (d, J = 246.7 Hz), 162.7 (d, J = 246.7 Hz),
141.4, 140.3, 139.9, 139.0 (d, J = 3.2 Hz), 138.8 (d, J = 2.8 Hz),
138.5, 137.1, 134.3, 133.2, 132.7 (d, J = 9.0 Hz), 131.6 (d, J =
8.9 Hz), 131.5, 129.1, 128.2, 127.9, 127.2, 126.3, 125.4, 124.8, 124.2,
120.2, 117.2, 116.1 (d, J = 21.3 Hz), 116.0 (d, J = 21.3 Hz) ppm.
20.1 ppm. MS: m/z (%) = 408 (100) [M+]. IR (neat): ν = 3052, 2918,
˜
1595, 1501, 1488, 1441, 1264, 1073, 1018, 874 cm–1. HRMS: calcd.
for C32H24 (M+) 408.1878; found 408.1873.
11-(Diphenylmethylene)-4-methyl-11H-benzo[b]fluorene (3n) and 11-
(Diphenylmethylene)-1-methyl-11H-benzo[b]fluorene (3o): The reac-
tion of 1a (61 mg, 0.2 mmol), 2e (125 mg, 0.4 mmol), PPh3 (6 mg,
0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg,
0.01 mmol) in MeCN (5 mL) afforded a mixture of 3n and 3o (1:1,
1
72 mg, 92%) as a yellow solid (eluent: petroleum ether). H NMR
MS: m/z (%) = 416 (100) [M+]. IR (neat): ν = 3050, 1594, 1499,
˜
(400 MHz, CDCl3, 25 °C): δ = 8.21 (s, 1 H), 8.06 (s, 1 H), 7.83–
7.73 (m, 3 H), 7.54–7.05 (m, 31 H), 6.92–6.85 (m, 2 H), 6.70 (s, 1
H), 6.63 (d, J = 8.0 Hz, 1 H), 2.79 (s, 3 H), 1.53 (s, 3 H) ppm.
1428, 1274, 1217, 1155, 1092, 1015, 950, 891 cm–1. HRMS: calcd.
for C30H18F2 (M+) 416.1377; found 416.1371.
11-[Bis(4-chlorophenyl)methylene]-11H-benzo[b]fluorene (3g): The
reaction of 1g (75 mg, 0.2 mmol), 2a (119 mg, 0.4 mmol), PPh3
Synthesis of 11-(Diphenylmethylene)-2,3-difluoro-11H-benzo[b]fluo-
rene (3l) as a Representative General Procedure for the Preparation
(6 mg, 0.02 mmol), CsF (121 mg, 0.8 mmol) and Pd(dba)2 (6 mg, of 11-(Diarylmethylene)-11H-benzo[b]fluorenes 3l and 3m: A rub-
0.01 mmol) in MeCN (5 mL) afforded 3g (86 mg, 96%) as a yellow
ber-capped Schlenk vessel containing CsF (121 mg, 0.8 mmol) was
flame-dried under vacuum and backfilled with nitrogen three times.
solid (eluent: petroleum ether); m.p. 210–211 °C (petroleum ether).
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.07 (s, 1 H), 7.86–7.81 PPh3 (6 mg, 0.02 mmol), Pd(dba)2 (6 mg, 0.01 mmol), and dry
(m, 2 H), 7.45–7.24 (m, 12 H), 7.12 (s, 1 H), 7.02 (t, J = 7.6 Hz, 1
MeCN (2 mL) were added sequentially to the Schlenk vessel. After
H), 6.76 (d, J = 8.0 Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3, being stirred for about 1 min at 80 °C, a mixture of 1a (61 mg,
25 °C): δ = 141.3, 141.1, 140.7, 140.4, 139.7, 138.5, 136.8, 134.6,
134.4, 134.3, 133.3, 132.7, 131.4, 131.3, 129.3, 129.3, 129.2, 128.4,
127.9, 127.3, 126.4, 125.4, 124.9, 124.4, 120.2, 117.3 ppm. MS: m/z
0.2 mmol) and 2c (134 mg, 0.4 mmol) in dry MeCN (5 mL) was
added by a micro infusion pump over 1 h at 80 °C. The reaction
was complete as monitored by TLC. The reaction mixture was fil-
Eur. J. Org. Chem. 2011, 2993–3000
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2997

Y. Lin, L. Wu, X. Huang
FULL PAPER
tered through a shot pad of silica gel. The filtrate was concentrated
under reduced pressure, and the residue was purified by silica gel
chromatography (eluent: petroleum ether) to afford 3l (58 mg,
70%) as a yellow solid; m.p. 215–217 °C (petroleum ether). 1H
= 8.0 Hz, 1 H), 2.73–2.64 (m, 4 H), 1.74–1.61 (m, 4 H), 1.48–1.36
(m, 4 H), 1.02–0.94 (m, 6 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 144.8, 143.0, 142.9, 140.8, 140.4, 140.3, 140.1, 138.6,
137.6, 133.3, 133.0, 132.8, 129.5, 129.4, 129.0, 129.0, 128.8, 127.8,
NMR (400 MHz, CDCl3, 25 °C): δ = 7.93 (s, 1 H), 7.80 (d, J = 127.6, 127.0, 125.8, 125.0, 124.9, 124.3, 120.0, 116.8, 35.5, 33.7,
8.4 Hz, 1 H), 7.56–7.24 (m, 14 H), 7.00 (s, 1 H), 6.40–6.35 (m, 1 33.5, 22.4, 22.3, 14.0, 14.0 ppm. MS: m/z (%) = 492 (73) [M+], 363
H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 150.7 (dd, J = (100). IR (neat): ν = 2954, 2925, 2855, 1580, 1501, 1461, 1427,
˜
248.2, 14.2 Hz), 149.6 (dd, J = 243.5, 12.7 Hz), 144.8, 144.7, 142.7,
142.2, 137.1, 137.0, 136.7 (dd, J = 7.0, 2.1 Hz), 136.2 (dd, J = 6.8,
2.9 Hz), 133.1, 132.6, 132.3, 129.4, 129.3, 129.2, 129.1, 128.6, 128.4,
127.8, 126.4, 125.5, 124.5, 117.1, 113.9, 113.7, 108.2, 108.0 ppm.
1267, 1182, 1108, 1019, 955, 884 cm–1. HRMS: calcd. for C38H36
(M+) 492.2817; found 492.2820.
11-{Bis[4-(2-phenylethynyl)phenyl]methylene}-11H-benzo[b]fluorene
(4c): The reaction of 3h (81 mg, 0.15 mmol), (E)-styrylboronic acid
(88 mg, 0.6 mmol), Pd(OAc)2 (1 mg, 0.02 mmol), L (4 mg,
0.009 mmol), K3PO4 (111 mg, 0.525 mmol) and water (8 mg,
0.45 mmol) in dioxane (1 mL) afforded 4c (79 mg, 90%) as a yellow
solid (eluent: petroleum ether/CH2Cl2 = 10:1); m.p. 245–246 °C
MS: m/z (%) = 416 (100) [M+]. IR (neat): ν = 2922, 1592, 1474,
˜
1446, 1415, 1345, 1315, 1272, 1155, 1054, 1027, 881 cm–1. HRMS:
calcd. for C30H18F2 (M+) 416.1377; found 416.1376.
9-(Diphenylmethylene)-9H-tribenzo[a,c,h]fluorene (3m): According
to this procedure, the reaction of 1a (61 mg, 0.2 mmol), 2d (159 mg,
0.4 mmol), PPh3 (6 mg, 0.02 mmol), CsF (121 mg, 0.8 mmol) and
Pd(dba)2 (6 mg, 0.01 mmol) in MeCN (5 mL) afforded 3m (82 mg,
85%) as a yellow solid (eluent: petroleum ether); m.p. 240–242 °C
(petroleum ether). 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.99
(d, J = 8.0 Hz, 1 H), 8.69–8.64 (m, 2 H), 8.47 (d, J = 8.4 Hz, 1 H),
7.86 (d, J = 8.0 Hz, 1 H), 7.76–7.25 (m, 12 H), 7.07–6.93 (m, 6 H),
6.83 (s, 1 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 145.4,
143.6, 143.5, 139.5, 138.6, 137.3, 135.5, 135.3, 133.0, 132.4, 132.1,
131.8, 131.2, 130.4, 128.9, 128.8, 128.7, 128.5, 128.2, 127.9, 127.8,
127.2, 127.1, 126.5, 125.8, 125.4, 125.3, 125.2, 124.8, 123.6, 122.8,
1
(petroleum ether/CH2Cl2). H NMR (400 MHz, CDCl3, 25 °C): δ
= 8.07 (s, 1 H), 7.86–7.80 (m, 2 H), 7.58–7.52 (m, 8 H), 7.43–7.34
(m, 10 H), 7.30–7.25 (m, 5 H), 7.21–7.16 (m, 4 H), 7.01 (t, J =
7.8 Hz, 1 H), 6.91 (d, J = 8.0 Hz, 1 H) ppm. 13C NMR (100 MHz,
CDCl3, 25 °C): δ = 143.4, 142.4, 142.2, 140.3, 140.2, 138.5, 137.4,
137.3, 137.2, 137.1, 133.9, 133.1, 132.8, 130.6, 130.5, 129.3, 129.3,
129.2, 128.7, 128.2, 128.1, 127.9, 127.8, 127.8, 127.1, 127.0, 126.9,
126.6, 126.1, 125.2, 125.0, 124.4, 120.1, 117.1 ppm. MS: m/z (%) =
584 (38) [M+], 580 (100). IR (neat): ν = 2983, 2903, 1595, 1502,
˜
1406, 1262, 1072, 964, 885 cm–1. HRMS: calcd. for C46H32 (M+)
584.2504; found 584.2512.
121.7, 120.5 ppm. MS: m/z (%) = 480 (100) [M+]. IR (neat): ν =
˜
11-{Bis[4-(3-methoxyphenyl)phenyl]methylene}-11H-benzo[b]-
fluorene (4f): The reaction of 3h (67 mg, 0.15 mmol), 3-methoxy-
phenylboronic acid (109 mg, 0.6 mmol), Pd(OAc)2 (1 mg,
0.0045 mmol), L (4 mg, 0.009 mmol), K3PO4 (111 mg, 0.525 mmol)
and water (8 mg, 0.45 mmol) in dioxane (1 mL) afforded 4f (81 mg,
83%) as a yellow solid (eluent: petroleum ether/CH2Cl2 = 5:1); m.p.
135–137 °C (petroleum ether/CH2Cl2). 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 8.06 (s, 1 H), 7.85–7.78 (m, 2 H), 7.69–7.64 (m,
4 H), 7.52–7.47 (m, 4 H), 7.41–7.18 (m, 11 H), 6.99 (t, J = 8.0 Hz,
1 H), 6.94–6.90 (m, 3 H) ppm. 13C NMR (100 MHz, CDCl3,
25 °C): δ = 160.1, 160.0, 143.2, 142.4, 142.1, 142.0, 141.9, 140.8,
140.7, 140.3, 140.1, 138.5, 137.3, 134.0, 133.1, 132.8, 130.3, 130.2,
129.9, 129.8, 129.1, 128.0, 127.8, 127.6, 127.5, 127.2, 126.1, 125.2,
125.0, 124.5, 120.1, 119.6, 119.5, 117.1, 112.9, 112.9, 112.8, 55.3,
3052, 1562, 1488, 1441, 1404, 1264, 1159, 1074, 947, 872 cm–1.
HRMS: calcd. for C38H24 (M+) 480.1878; found 480.1869.
Suzuki Coupling of C–Br Bonds and C–Cl Bonds in 3g and 3h
11-{Bis[4-(p-tolyl)phenyl]methylene}-11H-benzo[b]fluorene (4a): A
rubber-capped Schlenk vessel containing K3PO4 (111 mg,
0.525 mmol) was flame-dried under vacuum and backfilled with
nitrogen three times. Pd(OAc)2 (1 mg, 0.0045 mmol), L[21] (4 mg,
0.009 mmol), p-tolylboronic acid (88 mg, 0.6 mmol), 3h (81 mg,
0.15 mmol), dioxane (1 mL) and water (8 μL, 8 mg, 0.45 mmol)
were added sequentially to the Schlenk vessel. The resulting mix-
ture was heated at 110 °C for 10 h. After the reaction was complete
as monitored by TLC, the reaction mixture was filtered through a
shot pad of silica gel. The filtrate was concentrated under reduced
pressure, and the residue was purified by silica gel chromatography
(petroleum ether/CH2Cl2 = 10:1) to afford 4a (77 mg, 92%) as a
yellow solid; m.p. 290–291 °C (petroleum ether/CH2Cl2). 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 8.06 (s, 1 H), 7.84–7.77 (m, 2 H),
7.66–7.54 (m, 8 H), 7.48–7.44 (m, 4 H), 7.36–7.18 (m, 9 H), 6.98
(t, J = 7.4 Hz, 1 H), 6.90 (d, J = 8.0 Hz, 1 H) ppm. 13C NMR
(100 MHz, CDCl3, 25 °C): δ = 143.6, 141.9, 141.6, 140.8, 140.7,
140.2, 138.6, 137.7, 137.5, 137.4, 137.3, 133.8, 133.1, 132.8, 130.4,
130.3, 129.6, 129.5, 129.2, 127.9, 127.8, 127.3, 127.2, 126.9, 126.8,
126.0, 125.1, 125.0, 124.4, 120.1, 117.0, 21.1 ppm. MS: m/z (%) =
55.3 ppm. MS: m/z (%) = 592 (100) [M+]. IR (neat): ν = 2985, 2903,
˜
1594, 1478, 1427, 1395, 1295, 1217, 1051, 866 cm–1. HRMS: calcd.
for C44H32O2 (M+) 592.2402; found 592.2405.
Sonogashira Coupling of the C–Br Bonds in 3h
11-{Bis[4-(E)-styrylphenyl]methylene}-11H-benzo[b]fluorene (4d):[22]
A rubber-capped Schlenk vessel containing 3h (81 mg, 0.15 mmol),
PdCl2(PPh3)2 (6 mg, 0.01 mmol) and AuCl(PPh3 ) (6 mg,
0.01 mmol) was dried under vacuum and backfilled with nitrogen
three times. Et3N (92 mg, 0.9 mmol), 1-ethynylbenzene (34 mg,
0.33 mmol), and dry DMF (1 mL) were added sequentially to the
Schlenk vessel. The resulting mixture was then allowed to stir at
80 °C. After 12 h, the reaction was complete as monitored by TLC.
The reaction mixture was then cooled to room temp. and diluted
with diethyl ether (5 mL). The mixture was poured into water, and
the aqueous layer was extracted with diethyl ether (10 mLϫ3). The
combined organic layer was dried with anhydrous MgSO4, and the
solvent was evaporated under reduced pressure. The residue was
560 (100) [M+]. IR (neat): ν = 2982, 2905, 1360, 1910, 1493, 1394,
˜
1260, 1050, 1004, 887 cm–1. HRMS: calcd. for C44H32 (M+)
560.2504; found 560.2505.
The following compounds were prepared according to this pro-
cedure.
11-[Bis(4-butylphenyl)methylene]-11H-benzo[b]fluorene (4b): The re-
action of 3h (81 mg, 0.15 mmol), butylboronic acid (61 mg,
0.6 mmol), Pd(OAc)2 (1 mg, 0.0045 mmol), L (4 mg, 0.009 mmol),
K3PO4 (111 mg, 0.525 mmol) and water (8 mg, 0.45 mmol) in diox-
ane (1 mL) afforded 4b (59 mg, 80%) as a yellow oil (eluent: petro-
leum). 1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.04 (s, 1 H), 7.83–
purified by silica gel chromatography (petroleum ether/CH2Cl2
=
10:1) to afford 4d (78 mg, 90%) as a yellow solid; m.p. 240–241 °C
1
(petroleum ether/CH2Cl2). H NMR (400 MHz, CDCl3, 25 °C): δ
= 8.07 (s, 1 H), 7.85–7.80 (m, 2 H), 7.63–7.55 (m, 8 H), 7.46–7.28
7.77 (m, 2 H), 7.43–7.18 (m, 12 H), 7.00–6.94 (m, 2 H), 6.74 (d, J (m, 14 H), 7.22 (s, 1 H), 7.01 (t, J = 7.8 Hz, 1 H), 6.84 (d, J =
2998
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2993–3000

Cycloaddition of Cyclopropa[b]naphthalenes with Arynes
7.6 Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 142.8,
142.6, 142.2, 140.4, 139.9, 138.5, 137.0, 134.5, 133.3, 132.8, 132.2,
132.1, 131.7, 131.6, 130.3, 130.2, 129.3, 128.4, 128.4, 128.3, 127.9,
127.2, 126.3, 125.3, 125.1, 124.5, 123.3, 123.2, 123.1, 123.0, 120.1,
117.2, 90.6, 90.5, 89.3, 89.2 ppm. MS: m/z (%) = 580 (100) [M+].
Chem. Rev. 1960, 60, 313–330; e) S. Sergeyev, W. Pisula, Y. H.
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Chem. 2001, 11, 1618–1624; b) L. Schmidt-Mende, A. Fecht-
enkötter, K. Müllen, E. Moons, R. H. Friend, J. D. MacKenzie,
Science 2001, 293, 1119–1122; c) A. M. van de Craats, N.
Stutzmann, O. Bunk, M. M. Nielsen, M. Watson, K. Müllen,
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˜
879 cm–1. HRMS: calcd. for C46H28 (M+) 580.2191; found
580.2193.
11-{Bis[4-(hex-1-ynyl)phenyl]methylene}-11H-benzo[b]fluorene
(4e):[23] A rubber-capped Schlenk vessel containing 3h (81 mg,
0.15 mmol), PdCl2(PPh3)2 (5 mg, 0.075 mmol) and CuI (3 mg,
0.015 mmol) was dried under vacuum and backfilled with nitrogen
three times. Piperdine (1 mL) and hex-1-yne (49 mg, 0.6 mmol)
were added sequentially to the Schlenk vessel. The resulting mix-
ture was then allowed to stir at 60 °C. After 7 h, the reaction was
complete as monitored by TLC. The reaction mixture was cooled
to room temp. and diluted with diethyl ether (5 mL). The mixture
was poured into water, and the aqueous layer was extracted with
diethyl ether (10 mLϫ3). The combined organic layer was dried
with anhydrous MgSO4, and the solvent was evaporated under re-
duced pressure. The residue was purified by silica gel chromatog-
raphy (petroleum ether) to afford 4e (63 mg, 86%) as a yellow oil.
1H NMR (400 MHz, CDCl3, 25 °C): δ = 8.07 (s, 1 H), 7.85–7.81
(m, 2 H), 7.48–7.27 (m, 12 H), 7.20 (s, 2 H), 6.99 (t, J = 7.8 Hz, 1
H), 6.81 (d, J = 8.0 Hz, 1 H), 2.49–2.44 (m, 4 H), 1.68–1.61 (m, 4
H), 1.55–1.48 (m, 4 H), 1.00–0.95 (m, 6 H) ppm. 13C NMR
(100 MHz, CDCl3, 25 °C): δ = 142.7, 142.1, 142.0, 140.3, 140.0,
138.5, 137.1, 134.1, 133.2, 132.8, 132.1, 132.0, 130.1, 130.0, 129.3,
128.1, 127.8, 127.2, 126.2, 125.2, 125.1, 124.4, 124.1, 124.0, 120.1,
117.1, 91.7, 91.7, 80.5, 80.4, 30.8, 30.8, 22.1, 22.0, 19.2, 19.1, 13.7,
[3]
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13.6 ppm. MS: m/z (%) = 540 (28) [M+], 185 (100). IR (neat): ν =
˜
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3054, 2956, 2928, 2865, 1501, 1462, 1428, 1325, 1104, 1017,
885 cm–1. HRMS: calcd. for C42H36 (M+) 540.2817; found
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X-ray Crystal Data for 3a: C30H20, Mr = 380.46, crystal system:
orthorhombic, space group: Pca21, final R indices [IϾ2σ(I)]: R1
= 0.0446, wR2 = 0.0843, R indices (all data): R1 = 0.0800, wR2 =
0.1005, a = 18.7779(13) Å, b = 13.4178(7) Å, c = 8.1839(5) Å, α =
90.00°, β = 90.00°, γ = 90.00°, V = 2062.0(2) Å3, T = 293(2) K, Z
= 4, reflections collected/unique: 9118/2029 [R(int) = 0.0556],
number of observations [IϾ2σ(I)]:1372, parameters: 271.
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CCDC-807039 (for 3a) contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Supporting Information (see footnote on the first page of this arti-
1
cle): H NMR and 13C NMR spectra of all the products.
Acknowledgments
We are grateful to the National Natural Science Foundation of
China (project numbers 20732005 and 20872127), the National Ba-
sic Research Program of China (973 Program, 2009CB825300),
CAS Academician Foundation of Zhejiang Province and the Fun-
damental Research funds for the Central Universities for financial
support.
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Received: January 11, 2011
Published Online: April 19, 2011
3000
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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