Palladium(0)-catalyzed cyclization of 1,6-diyn-3-yl carbonates with a nucleophilic functionality: Efficient synthesis of polycyclic benzo[b]fluorene derivatives via allene intermediates

Article abstract of DOI:10.1039/c2ob07148g

We report in this paper an interesting tandem reaction involving sequential palladium(0)-catalyzed decarboxylation of diynylic carbonates, intramolecular nucleophilic cyclization and Schmittel reaction, which provides a facile method for the synthesis of a variety of polycyclic benzo[b]fluorene derivatives from easily accessible starting materials.

Full text of DOI:10.1039/c2ob07148g

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PAPER
Palladium(0)-catalyzed cyclization of 1,6-diyn-3-yl carbonates with a
nucleophilic functionality: efficient synthesis of polycyclic benzo[b]fluorene
derivatives via allene intermediates†
Shugao Zhu,a Luling Wu*a and Xian Huang‡a,b
Received 21st December 2011, Accepted 1st March 2012
DOI: 10.1039/c2ob07148g
We report in this paper an interesting tandem reaction involving sequential palladium(0)-catalyzed
decarboxylation of diynylic carbonates, intramolecular nucleophilic cyclization and Schmittel reaction,
which provides a facile method for the synthesis of a variety of polycyclic benzo[b]fluorene derivatives
from easily accessible starting materials.
efficient synthesis of structurally complex polycycles with 2,3-
Introduction
dihydrofuran units,7 structurally diverse fused dihydroisobenzo-
furan derivatives,8 and other structurally complex polycycles.9
Construction of polycyclic aromatic ring skeletons has attracted
considerable attention in recent years due to their increasing
importance in organic material science.1 The utility of polycyclic
aromatic hydrocarbons (PAHs) as organic optoelectronic devices
such as light-emitting diodes, field-effect transistors, photovol-
taics, acenes, nanographenes and discotic liquid crystals is also
important.2 In addition, PAHs with benzo[b]fluorene skeletons
are also of considerable interest due to their applications as bio-
active compounds and synthetic intermediates in organic syn-
thesis.3 Therefore, new methods for the efficient synthesis of
benzo[b]fluorenes are still highly desired.
In the past decades, many novel and useful reactions have
been developed based on the chemistry of allenes for the syn-
thesis of useful molecules,4,5 and some of these reactions have
been successfully applied for the synthesis of natural products.6
It is obvious that the chemistry of allenes will further be exten-
sively explored to show their potential in organic chemistry. The
development of novel cascade reactions involving in situ-gener-
ated reactive functional groups such as allene intermediates is an
intensively pursued goal in our group. In this aspect, we pre-
viously established a series of sequential reactions wherein an
allene intermediate, generated in situ, would undergo [4 + 2]
cycloaddition reaction under mild conditions, providing an
Recently we also developed a convenient sequential palladium
(0)-catalyzed coupling, propargyl–allenyl isomerization and
Schmittel cyclization reaction, leading to polycyclic fluorene
derivatives from easily accessible starting materials under mild
conditions (Scheme 1).10
Based on these studies, we envisioned that palladium(0) cata-
lyst may initially promote decarboxylation of diynylic carbonates
1 to generate an allenylpalladium complex 3, which would
undergo an intramolecular nucleophilic attack by the carbanion
to form an allene intermediate 4. This intermediate 4 may prefer-
entially cyclize to produce a benzofulvene diradical 5 via
Schmittel reaction; then an intramolecular 1,6-diradical coupling
reaction and 1,5-H shift may proceed to furnish benzo[b]fluorene
derivatives 2 (Scheme 2). By this strategy three new carbon–
carbon bonds can be formed to construct the benzene ring in a
single stroke meanwhile five rings could be efficiently
assembled, affording an attractive synthesis of benzo[b]fluorene
derivatives. In this paper we wish to report the realization of
aDepartment of Chemistry, Zhejiang University, Hangzhou 310028,
P.R. China. E-mail: Wululing@zju.edu.cn
bState Key Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032,
P.R. China
†Electronic supplementary information (ESI) available. CCDC 821990.
For ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/c2ob07148g
‡Professor Huang passed away on March 6, 2010. He was fully in
charge of this project. Professor Luling Wu is helping to finish all the
projects with assistance from Professor Shengming Ma.
Scheme 1 Palladium-catalyzed coupling, propargyl–allenyl isomeriza-
tion, and Schmittel cyclization reaction for the synthesis of polycyclic
fluorene derivatives.
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the reaction was performed at 60 °C, a trace amount of 2a was
detected (entry 3). In the presence of Cs2CO3, the expected
product 2a was isolated in 35% yield (entry 4). With the
additional study using different catalyst precursors (entries 5 and
6), we found that Pd(PPh3)4 provided better product yield. Fur-
thermore, K2CO3 was also investigated as the base, although
lower yield was obtained, while Et3N was totally ineffective
(entries 7 and 8). THF was less effective (entry 9). When the
reaction was performed at 60 °C, the yield was improved to 75%
(entry 10). Although 1 mol% of Pd(PPh3)4 was proved to be
effective, the yield was slightly lower (entry 11). Thus, we chose
the following reaction conditions as optimum for further study:
1a, 2.0 equiv of Cs2CO3, and 5 mol% of Pd(PPh3)4 in DMF at
60 °C in N2).
Scheme 2 Concept of tandem Pd-catalyzed cyclization, and Schmittel
cyclization reaction for the synthesis of benzo[b]fluorene derivatives.
With the optimal conditions in hand, we next examined the
reaction scope. Typical results are summarized in Table 2. As for
propargylic carbonate 1 wherein R3 is an aromatic group such as
phenyl, p-methylphenyl, p-methoxyphenyl, p-chlorophenyl and
p-fluorophenyl group, the reactions proceeded smoothly under
the established conditions, delivering the benzo[b]fluorenes 2 in
good yields (Table 3, entries 1–5). However, when R3 is an alkyl
group, e.g. 1i, the reaction did not give the expected product,
instead, an unidentified mixture was formed (Scheme 3). Fur-
thermore, diynylic carbonates with different electron withdraw-
ing groups (1f), (1g) and (1h), have also been subjected to the
standard conditions, affording the corresponding products 2f, 2g
and 2h in moderate yields (Table 3, entries 6, 7 and 8). The sub-
stituents R have significant effect on this reaction. When R =
CO2Me, the reaction proceeded smoothly to afford the corre-
sponding product 2j in 70% yield (Table 3, entry 9). However,
when R was acetate, the reaction gave the product 2j very poor
yield (Scheme 3). All of the products were characterized by
spectroscopic methods, and 2j was further confirmed by X-ray
crystallography§ (Fig. 1).
Table 1 Preparation of acyclic precursors 1a
9
Entry R1
R2
R3
Yield of 1 (%)b
1
2
3
4
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
C6H5
9a
9b
9c
9d
9e
9f
9g
9h
9j
82 (1a)
85 (1b)
90 (1c)
76 (1d)
82 (1e)
70 (1f)
60 (1g)
65 (1h)
80 (1j)
85 (1l)
CO2Et
CO2Et
CO2Et
CO2Et
p-MeC6H4
p-MeOC6H4
p-ClC6H4
p-FC6H4
5
6
7
8
CO2Me CO2Me C6H5
COMe
CN
CO2Et
CO2Et
C6H5
C6H5
9
CO2Me CO2Me p-MeOC6H4
10
11
12
13
CO2Et
CO2Et
CO2Et
CO2Et
COMe
CO2Et
Cyclohex-2-enyl
Cyclohex-2-enyl
Cyclopent-2-enyl 9n
9l
To further expand the scope of this reaction, the group of R3
(eqn in Table 4), the benzene ring (R3) in 1a was replaced by a
cyclic double bond. The reaction afforded several polycyclic
benzo[b]fluorene derivatives in satisfactory yields.
9m 88 (1m)
75 (1n)
78 (1o)
CO2Me CO2Me Cyclopent-2-enyl 9o
a Reactions were carried out using propargylic alcohol (1.0 mmol),
pyridine (4.0 mmol), and DMAP (0.2 mmol) in CH2Cl2 (10 mL), ethyl
chloroformate (4.0 mmol) was added at 0 °C, then stirred for 2 h at
room temperature. b Isolated yields.
Finally, a control experiment for the current Pd-catalyzed
cyclization of 1a was also carried out under the standard con-
ditions as described above except with the use of additional
radical scavenger. It was found that the presence of a radical sca-
venger, 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO) or
hydroquinone, led to an obvious decrease in the yield of cyclized
product 2a (Scheme 4). This result may account for the proposed
reaction pathway involving radical intermediates as described in
Scheme 2.
such a synthesis for benzo[b]fluorene derivatives from diynylic
carbonates 1.
Results and discussion
Malonates 9 could be conveniently prepared via Sonogashira
coupling of iodo-derivatives 7 with propargylic alcohols 8. Treat-
ment of 9 with ethyl chloroformate afforded propargylic com-
pounds 1 in moderate yields (Table 1).
Conclusions
In conclusion, we have developed a convenient sequential
Pd-catalyzed decarboxylation of propargylic carbonate,
Our initial study began with the reaction of diethyl 2-(2-(3-
(methoxycarbonyloxy)-3-(2-(phenylethynyl)phenyl)prop-1-
ynyl)benzyl)malonate (1a, 0.2 mmol) using Pd2(dba)3·CHCl3
(0.05 equiv) as a catalyst in DMF at room temperature. However,
no reaction occurred and 78% of 1a was recovered (entry 1).
When PPh3 was added, no expected product was observed at
room temperature and 64% of 1a was recovered (entry 2). When
§X-ray crystal data for 2j: C30H24O5; M = 464.49; crystal system: mono-
clinic; space group: C2/c; final R indices (I > 2σ(I)) R1 = 0.0465, wR2 =
0.1154, R indices (all data) R1 = 0.0613, wR2 = 0.1252; a = 8.3183(2)
Å, b = 25.3594(6) Å, c = 10.8216(2) Å; α = 90.00, β = 90.076, γ =
90.00, V = 2282.78(9) Å3, T = 293(2) K, Z = 4; reflections collected/
unique: 21 130/4165 (R(int) = 0.0291); number of observations (>2σ(I)):
3338; parameters: 319.
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Table 2 Optimization of the Pd-catalyzed cyclization of propargylic carbonate 1aa
Entry
Catalyst (mol%)
Base
Solvent
Temp T (°C)
Time
Yield of 2ab (%)
1
2
3
4
5
6
7
8
Pd2(dba)3·CHCl3 (5)
Pd2(dba)3·CHCl3/PPh3 (5)
Pd2(dba)3·CHCl3/PPh3 (5)
Pd2(dba)3·CHCl3 (5)
Pd(PPh3)4 (5)
Pd(OAc)2/PPh3 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (5)
Pd(PPh3)4 (1)
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
THF
rt
rt
60
rt
rt
rt
rt
rt
rt
48 h
48 h
6 h
48 h
16 h
24 h
12 h
48 h
24 h
1 h
0
0
Trace
35
72
38
22
—
19
75
65
Cs2CO3
Cs2CO3
Cs2CO3
K2CO3
Et3N
Cs2CO3
Cs2CO3
Cs2CO3
9
10
11
DMF
DMF
60
60
3 h
a Reactions were carried out on a 0.2 mmol scale in 3.0 mL of solvent at 60 °C in N2 for the specified period of time with 1.0 equiv of 1a, 2.0 equiv
of base, and [Pd]. b Isolated yields.
Table 3 Pd-catalyzed cyclization of propargylic carbonate 1a
1
Entry
R1
R2
R3
Yield of 2b (%)
Scheme 3
1
2
3
4
5
6
7
8
9
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
CO2Me
COMe
CN
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
CO2Me
CO2Et
CO2Et
CO2Me
C6H5
1a
1b
1c
1d
1e
1f
1g
1h
1j
75 (2a)
72 (2b)
73 (2c)
78 (2d)
65 (2e)
72 (2f)
62 (2g)
45 (2h)
70 (2j)
p-MeC6H4
p-MeOC6H4
p-ClC6H4
p-FC6H4
C6H5
C6H5
C6H5
CO2Me
p-MeOC6H4
a Reactions were carried out using 1 (0.2 mmol), Cs2CO3 (2.0 equiv),
and Pd(PPh3)4 (5 mol%) in DMF (3 mL) at 60 °C in N2. b Isolated
yields.
intramolecular nucleophilic attack and Schmittel cyclization,
leading to a facile and efficient synthesis of polycyclic benzo[b]-
fluorene derivatives from easily accessible starting materials
under mild conditions.
Fig. 1 ORTEP representation of 2j.
sodium–benzophenone; DMF was distilled from CaH2. Pet-
roleum ether refers to the fraction with the boiling point in the
range 60–90 °C. All 1H NMR and 13C NMR spectra were
measured in CDCl3 with TMS as the internal standard. Chemical
shifts are expressed in ppm and J values are given in Hz. Starting
materials: Propargylic alcohols were prepared according to the
literature.
Experimental section
General
All reactions were performed under an N2 atmosphere. Anhy-
drous solvents were distilled prior to use: THF was distilled from
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prop-1-ynyl)benzyl)malonate as an oil: 1H NMR (400 MHz,
CDCl3): δ = 7.82 (d, J = 7.6 Hz, 1H), 7.58–7.55 (m, 3H),
7.39–7.14 (m, 9H), 6.21 (d, J = 5.2 Hz, 1H), 4.15–4.10 (m, 4H),
3.86 (t, J = 8.0 Hz, 1H), 3.76 (d, J = 5.6 Hz, 1H), 3.37 (d, J =
7.2 Hz, 2H), 1.19–1.15 (m, 6H) ppm; 13C NMR (100 MHz,
CDCl3): δ = 169.2, 169.1, 142.3, 140.0, 132.3, 132.0, 131.5,
129.9, 128.8, 128.5, 128.4, 128.3, 128.0, 126.7, 126.4, 122.9,
122.2, 121.4, 94.8, 94.1, 86.6, 84.0, 63.2, 61.5, 61.5, 52.4, 33.8,
13.9 ppm; MS: m/z (%) = 480 (M+, 12.79), 262 (100); IR (neat):
3468, 2981, 1726, 1490, 1370, 1153 cm−1; HRMS calcd for
C31H28O5 (M+): 480.1937; found: 480.1993.
Table 4 Sequential reaction for the synthesis of polycyclic benzo[b]-
fluorene derivatives 2aa
1
Compounds 9b–o were prepared according to this typical pro-
cedure, and used directly after column purification.
Entry
R1
R2
n
Yield of 2b (%)
1
2
3
4
CO2Et
CO2Et
CO2Et
CO2Me
CO2Et
COMe
CO2Et
CO2Me
2
2
1
1
1l
80 (2l)
64 (2m)
75 (2n)
78 (2o)
1m
1n
1o
General procedure for the preparation of propargylic
compounds 1a–o
a Reactions were carried out using 1 (0.2 mmol), Cs2CO3 (2.0 equiv),
and Pd(PPh3)4 (5 mol%) in DMF (3 mL) at 60 °C in N2. b Isolated
yields.
To a solution of propargylic alcohol (1.0 mmol), pyridine
(0.32 g, 4.0 mmol), and DMAP (22.4 mg, 0.2 mmol) in CH2Cl2
(10 mL) was added at 0 °C ethyl chloroformate (0.44 g,
4.0 mmol). After being stirred for 2 h at room temperature, the
reaction mixture was diluted with CH2Cl2. The CH2Cl2 solution
was washed with a saturated aqueous copper sulfate solution,
water, dried over anhydrous sodium sulfate, filtered and concen-
trated. The residue was purified by column chromatography on
silica gel (petroleum ether–ethyl acetate 20 : 1) to afford the cor-
responding propargylic compounds.
(1) Diethyl 2-(2-(3-(methoxycarbonyloxy)-3-(2-(phenylethy-
nyl)phenyl)prop-1-ynyl)benzyl)malonate (1a). The reaction of
diethyl
2-(2-(3-hydroxy-3-(2-(phenylethynyl)phenyl)prop-1-
ynyl)benzyl)malonate (0.48 g, 1 mmol), pyridine (0.32 g,
4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl chlorofor-
mate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded 0.43 g
(80%) of 1a as an oil: 1H NMR (400 MHz, CDCl3): δ =
7.90–7.88 (m, 1H), 7.60–7.58 (m, 3H), 7.40 (m, 1H), 7.37–7.35
(m, 5H), 7.26–7.22 (m, 3H), 7.10 (s, 1H), 4.12–4.08 (m, 4H),
3.85 (t, J = 8.0 Hz, 1H), 3.78 (s, 3H), 3.37 (d, J = 8.0 Hz, 2H),
1.17–1.13 (m, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ =
168.8, 168.7, 154.8, 140.2, 137.3, 132.8, 132.3, 131.7, 129.8,
129.1, 129.0, 128.7, 128.6, 128.3, 128.1, 126.7, 122.8, 122.7,
121.6, 95.1, 89.1, 86.2, 86.0, 68.3, 61.3, 55.0, 52.1, 33.5,
13.9 ppm; MS: m/z (%) = 538 (M+, 5.56), 315 (100); IR (neat):
2927, 1748, 1494, 1256, 1105, 948, 857, 756 cm−1; HRMS
calcd for C33H30O7 (M+): 538.1992; found: 538.1998.
Scheme 4
Typical procedure: diethyl 2-(2-(3-hydroxy-3-(2-(phenylethynyl)-
phenyl)prop-1-ynyl)benzyl)malonate (9a)
An oven-dried Schlenk tube containing a Teflon-coated stirring
bar was charged with Pd(PPh3)2Cl2 (70 mg, 5 mol%), CuI
(19 mg,
5 mol%), and diethyl 2-(2-iodobenzyl)malonate
(2) Diethyl 2-(2-(3-(methoxycarbonyloxy)-3-(2-(p-tolylethynyl)
phenyl)prop-1-ynyl)benzyl)malonate (1b). The reaction of
(2 mmol, 0.75 g). The Schlenk tube was sealed, evacuated and
backfilled with N2 (3 cycles). A solution of 1-(2-(phenylethy-
nyl)phenyl)prop-2-yn-1-ol (2.4 mmol, 0.56 g) in 10 mL of THF
and 3 mL of Et3N was subsequently injected to the Schlenk
tube. The reaction mixture was stirred for 1 h at room tempera-
ture. After 1 h the reaction was complete as monitored by TLC,
the reaction was quenched with an aqueous saturated solution of
NH4Cl and extracted with diethyl ether (3 × 20 mL). The com-
bined organic phase was washed with brine and dried over
Na2SO4. Filtration, evaporation and column chromatography on
silica gel (petroleum ether–ethyl acetate 4 : 1) afforded 0.78 g
(82%) of diethyl 2-(2-(3-hydroxy-3-(2-(phenylethynyl)phenyl)-
diethyl
2-(2-(3-hydroxy-3-(2-(p-tolylethynyl)phenyl)prop-1-
ynyl)benzyl)malonate (0.49 g, 1 mmol), pyridine (0.32 g,
4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl chlorofor-
mate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded 0.47 g
(85%) of 1b as an oil: 1H NMR (400 MHz, CDCl3): δ =
7.90–7.88 (m, 1H), 7.58–7.56 (m, 1H), 7.50–7.47 (m, 3H),
7.40–7.36 (m, 2H), 7.24–7.12 (m, 6H), 4.12–4.08 (m, 4H), 3.87
(m, 1H), 3.77 (s, 3H), 3.38 (d, J = 8.4 Hz, 2H), 2.35 (s, 3H),
1.17–1.12 (m, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ =
168.7, 168.6, 154.7, 140.1, 138.7, 137.1, 132.7, 132.1, 131.5,
129.7, 129.0, 129.0, 128.9, 128.4, 128.0, 126.7, 122.9, 121.6,
This journal is © The Royal Society of Chemistry 2012
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(6) Dimethyl 2-(2-(3-(methoxycarbonyloxy)-3-(2-(phenylethy-
nyl)phenyl)prop-1-ynyl)benzyl)malonate (1f). The reaction of
dimethyl 2-(2-(3-hydroxy-3-(2-(phenylethynyl)phenyl)prop-1-
ynyl)benzyl)malonate (0.45 g, 1 mmol), pyridine (0.32 g,
4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl chlorofor-
mate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded 0.36 g
(70%) of 1f as an oil: 1H NMR (400 MHz, CDCl3): δ =
7.89–7.87 (m, 1H), 7.60–7.58 (m, 3H), 7.49–7.34 (m, 6H),
7.26–7.12 (m, 3H), 7.11 (s, 1H), 3.90 (t, J = 7.6 Hz, 1H), 3.77
(s, 3H), 3.63–3.62 (m, 6H), 3.38 (d, J = 7.6 Hz, 2H) ppm; 13C
NMR (100 MHz, CDCl3): δ = 169.1, 169.0, 154.8, 140.0, 137.3,
132.7,132.2, 131.6, 129.7, 129.1, 129.0, 128.7, 128.5, 128.3,
128.0, 126.8, 122.7, 122.6, 121.5, 95.1, 89.2, 86.0, 85.9, 68.2,
55.0, 52.3, 51.8, 33.6 ppm; MS: m/z (%) = 510 (M+, 8.58), 43
119.6, 95.3, 89.1, 86.0, 85.3, 68.3, 61.2, 54.9, 52.0, 33.5, 21.4,
13.8 ppm; MS: m/z (%) = 552 (M+, 11.52), 333 (100); IR (neat):
2981, 2216, 1748, 1484, 1150, 948, 788 cm−1; HRMS calcd for
C34H32O7 (M+): 552.2148; found: 552.2142.
(3) Diethyl 2-(2-(3-(methoxycarbonyloxy)-3-(2-((4-methoxy-
phenyl)ethynyl)phenyl)prop-1-ynyl)benzyl)malonate (1c). The
reaction of diethyl 2-(2-(3-hydroxy-3-(2-((4-methoxyphenyl)
ethynyl)phenyl)prop-1-ynyl)benzyl)malonate (0.51 g, 1 mmol),
pyridine (0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and
ethyl chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2
afforded 0.51 g (90%) of 1c as an oil: 1H NMR (400 MHz,
CDCl3): δ = 7.89–7.87 (m, 1H), 7.57–7.48 (m, 4H), 7.40–7.35
(m, 2H), 7.26–7.19 (m, 3H), 7.11–7.10 (m, 1H), 6.90–6.87 (m,
2H), 4.15–4.07 (m, 4H), 3.87 (t, J = 8.0 Hz, 1H), 3.79 (s, 3H),
3.78 (s, 3H), 3.38 (d, J = 7.6 Hz, 2H), 1.17–1.13 (m, 6H) ppm;
13C NMR (100 MHz, CDCl3): δ = 168.7, 168.7, 159.8, 154.8,
140.1, 137.0, 133.2, 132.8, 132.0, 129.8, 129.1, 129.0, 128.3,
128.0, 126.7, 123.2, 121.6, 114.8, 113.9, 95.2, 89.1, 86.1, 84.8,
68.3, 61.3, 55.2, 55.0, 52.1, 33.5, 13.9 ppm; MS: m/z (%) = 568
(M+, 11.81), 349 (100); IR (neat): 2980, 2214, 1747, 1441,
1029, 784 cm−1; HRMS calcd for C34H32O8 (M+): 568.2097;
found: 568.2095.
(100); IR (neat): 1749, 1701, 1492, 1441, 1102, 922 cm−1
HRMS calcd for C31H26O7 (M+): 510.1679; found: 510.1674.
;
(7) Ethyl 2-(2-(3-(methoxycarbonyloxy)-3-(2-(phenylethynyl)-
phenyl)prop-1-ynyl)benzyl)-3-oxobutanoate (1g). The reaction
of ethyl 2-(2-(3-hydroxy-3-(2-(phenylethynyl)phenyl)prop-1-
ynyl)benzyl)-3-oxobutanoate (0.45 g, 1 mmol), pyridine (0.32 g,
4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl chlorofor-
mate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded 0.31 g
(60%) of 1g as an oil: 1H NMR (400 MHz, CDCl3): δ =
7.86–7.84 (m, 1H), 7.58–7.57 (m, 3H), 7.48–7.34 (m, 6H),
7.25–7.16 (m, 3H), 7.10 (s, 1H), 4.12–3.98 (m, 3H), 3.77 (m,
3H), 3.36–3.20 (m, 2H), 2.15–2.12 (m, 3H), 1.15–1.11 (m, 3H)
ppm; 13C NMR (100 MHz, CDCl3): δ = 202.3, 202.3, 168.9,
154.8, 140.6, 140.5, 137.4, 137.4, 132.8, 132.8, 132.3, 131.6,
130.0, 129.1, 129.1, 129.1, 128.8, 128.7, 128.6, 128.3, 127.8,
127.8, 126.7, 122.7, 121.4, 95.2, 95.2, 89.2, 86.3, 86.0, 68.3,
61.2, 59.5, 55.0, 32.8, 29.3, 29.3, 13.9 ppm; MS: m/z (%) = 508
(M+, 7.68), 319 (100); IR (neat): 1746, 1715, 1492, 1442, 1103,
923 cm−1; HRMS calcd for C32H28O6 (M+): 508.1886; found:
508.1887.
(4) Diethyl 2-(2-(3-(2-((4-chlorophenyl)ethynyl)phenyl)-3-
(methoxycarbonyloxy)prop-1-ynyl)benzyl)malonate (1d). The
reaction of diethyl 2-(2-(3-(2-((4-chlorophenyl)ethynyl)phenyl)-
3-hydroxyprop-1-ynyl)benzyl)malonate (0.51 g, 1 mmol), pyri-
dine (0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl
chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
1
0.44 g (76%) of 1d as an oil: H NMR (400 MHz, CDCl3): δ =
7.90–7.88 (m, 1H), 7.58–7.32 (m, 8H), 7.26–7.19 (m, 3H), 7.09
(s, 1H), 4.15–4.07 (m, 4H), 3.85 (t, J = 8.0 Hz, 1H), 3.80 (s,
3H), 3.37 (d, J = 8.0 Hz, 2H), 1.17–1.13 (m, 6H) ppm; 13C
NMR (100 MHz, CDCl3): δ = 168.7, 168.7, 154.8, 140.1, 137.4,
134.6, 132.9, 132.8, 132.2, 129.8, 129.2, 129.1, 128.9, 128.6,
128.1, 126.8, 122.4, 121.6, 121.2, 93.9, 88.9, 87.0, 86.2, 68.2,
61.3, 55.0, 52.1, 33.5, 13.9 ppm; MS: m/z (%) = 572 (M+, 6.30),
(8) Ethyl 2-(2-(3-(methoxycarbonyloxy)-3-(2-(phenylethynyl)-
phenyl)prop-1-ynyl)benzyl)-3-oxobutanoate (1i). The reaction
of diethyl 2-(2-(3-(2-(cyclopropylethynyl)phenyl)-3-hydroxy-
43 (100); IR (neat): 2955, 1746, 1440, 1090, 948, 758 cm−1
;
HRMS calcd for C33H29O735Cl (M+): 572.1602; found:
572.1605.
prop-1-ynyl)benzyl)malonate (0.44 g, 1 mmol), pyridine
(0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl
chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
1
(5) Diethyl 2-(2-(3-(2-((4-fluorophenyl)ethynyl)phenyl)-3-
0.34 g (68%) of 1i as an oil: H NMR (400 MHz, CDCl3): δ =
(methoxycarbonyloxy)prop-1-ynyl)benzyl)malonate
(1e). The
7.81–7.79 (m, 1H), 7.48–7.46 (m, 2H), 7.42–7.18 (m, 5H), 6.94
(s, 1H), 4.12–4.09 (m, 4H), 3.88–3.83 (m, 4H), 3.37 (d, J = 8.4
Hz, 2H), 1.48–1.47(m, 1H), 1.18–1.13 (m, 6H), 0.88–0.86 (m,
4H) ppm; 13C NMR (100 MHz, CDCl3): δ = 168.5, 154.6,
140.0, 137.2, 132.5, 132.0, 129.6, 128.8, 127.7, 127.6, 127.5,
126.6, 123.3, 121.5, 99.5, 89.2, 85.7, 72.3, 68.1, 61.0, 54.7,
51.9, 33.4, 13.7, 8.55, 8.49, 0.10 ppm; MS: m/z (%) = 502 (M+,
2.36), 239 (100); IR (neat): 2984, 2228, 1748, 1443, 1152, 951,
754 cm−1; HRMS calcd for C30H30O7 (M+): 502.1992; found:
502.1992.
reaction of diethyl 2-(2-(3-(2-((4-fluorophenyl)ethynyl)phenyl)-
3-hydroxyprop-1-ynyl)benzyl)malonate (0.50 g, 1 mmol), pyri-
dine (0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl
chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
1
0.46 g (82%) of 1e as an oil: H NMR (400 MHz, CDCl3): δ =
7.90–7.88 (m, 1H), 7.60–7.56 (m, 3H), 7.50–7.38 (m, 3H),
7.26–7.17 (m, 3H), 7.09–7.04 (m, 3H), 4.14–4.06 (m, 4H), 3.85
(t, J = 8.0 Hz, 1H), 3.78 (s, 3H), 3.37 (d, J = 7.6 Hz, 2H),
1.18–1.13 (m, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ =
168.8, 168.7, 163.9, 161.4, 154.8, 140.1, 137.3, 133.7,133.6,
132.8, 132.2, 129.8, 129.2, 129.1, 128.8, 128.1, 126.8, 122.6,
121.6, 118.8, 115.7, 115.5, 94.0, 89.0, 86.2, 85.7, 68.3, 61.3,
55.0, 52.1, 33.5, 13.9 ppm; MS: m/z (%) = 556 (M+, 15.43), 481
(100); IR (neat): 2982, 1747, 1596, 1369, 1257, 1094,
948 cm−1; HRMS calcd for C33H29O7F (M+): 556.1897; found:
556.1898.
(9) Ethyl 2-(2-(3-(methoxycarbonyloxy)-3-(2-(phenylethynyl)-
phenyl)prop-1-ynyl)benzyl)-3-oxobutanoate (1j). The reaction
of dimethyl 2-(2-(3-hydroxy-3-(2-((4-methoxyphenyl)ethynyl)
phenyl)prop-1-ynyl)benzyl)malonate (0.48 g, 1 mmol), pyridine
(0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl
chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
3700 | Org. Biomol. Chem., 2012, 10, 3696–3704
This journal is © The Royal Society of Chemistry 2012

View Article Online
1
0.43 g (80%) of 1j as an oil: H NMR (400 MHz, CDCl3): δ =
ppm; 13C NMR (100 MHz, CDCl3): δ = 202.3, 202.3, 168.8,
154.7, 140.4, 140.4, 136.9, 136.9, 135.9, 132.7, 132.6, 132.0,
130.0, 129.0, 128.1, 128.1, 127.6, 126.6, 123.1, 123.1, 121.4,
120.4, 97.1, 89.2, 85.9, 83.3, 68.2, 61.1, 59.3, 54.9, 32.7, 29.3,
29.2, 28.8, 25.7, 22.1, 21.3, 13.8 ppm; MS: m/z (%) = 512 (M+,
1.52), 43 (100); IR (neat): 2934, 1745, 1715, 1483, 1442, 1256,
1147, 1101, 1009 cm−1; HRMS calcd for C32H32O6 (M+):
512.2199; found: 512.2206.
7.87–7.85 (m, 1H), 7.57–7.48 (m, 4H), 7.40–7.37 (m, 2H),
7.26–7.19 (m, 3H), 7.10 (s, 1H), 6.90–6.88 (m, 2H), 3.89 (t, J =
8.0 Hz, 1H), 3.83 (s, 3H), 3.78 (s, 3H), 3.64–6.63 (m, 6H), 3.38
(d, J = 8.0 Hz, 2H) ppm; 13C NMR (100 MHz, CDCl3): δ =
169.1, 169.1, 159.9, 154.8, 140.0, 137.1, 133.2, 132.8, 132.0,
129.7, 129.1, 129.1, 128.3, 128.0, 126.9, 123.2, 121.6, 114.8,
114.0, 95.3, 89.3, 86.0, 84.8, 68.4, 55.3, 55.0, 52.4, 51.9,
33.6 ppm; MS: m/z (%) = 540 (M+, 10.50), 59 (100); IR (neat):
2954, 2214, 1958, 1512, 1245, 1027, 785 cm−1; HRMS calcd
for C32H28O8 (M+): 540.1874; found: 540.1873.
(13) Diethyl 2-(2-(3-(2-(cyclopentenylethynyl)phenyl)-3-(meth-
oxycarbonyloxy)prop-1-ynyl)benzyl)malonate (1n). The reaction
of diethyl 2-(2-(3-(2-(cyclopentenylethynyl)phenyl)-3-hydroxy-
(10)
Dimethyl
2-(2-(3-acetoxy-3-(2-((4-methoxyphenyl)-
prop-1-ynyl)benzyl)malonate (0.47 g,
1 mmol), pyridine
ethynyl)phenyl)prop-1-ynyl)benzyl)malonate (1k). The reaction
of dimethyl 2-(2-(3-acetoxy-3-(2-((4-methoxyphenyl)ethynyl)
phenyl)prop-1-ynyl)benzyl)malonate (0.48 g, 1 mmol), pyridine
(0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and acetic
anhydride (0.41 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
(0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl
chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
0.40 g (75%) of 1n as an oil: H NMR (400 MHz, CDCl3): δ =
1
7.86–7.84 (m, 1H), 7.49–7.47 (m, 2H), 7.37–7.32 (m, 2H),
7.22–7.18 (m, 3H), 6.98 (s, 1H), 6.21–6.20 (m, 1H), 4.15–4.08
(m, 4H), 3.88–3.81 (m, 4H), 3.37 (d, J = 8.0 Hz, 2H), 2.58–2.47
(m, 4H), 1.98–1.91 (m, 2H), 1.18–1.13 (m, 6H) ppm; 13C NMR
(100 MHz, CDCl3): δ = 168.6, 168.6, 154.6, 140.0, 139.0,
137.0, 132.7, 131.9, 129.7, 128.9, 128.9, 128.3, 127.8, 126.6,
124.1, 123.0, 121.6, 92.5, 89.1, 86.9, 85.9, 68.2, 61.3, 54.8,
52.0, 36.1, 33.4, 33.3, 23.2, 13.8 ppm; MS: m/z (%) = 528 (M+,
8.67), 305 (100); IR (neat): 2958, 1748, 1370, 1257, 1102,
915 cm−1; HRMS calcd for C32H32O7 (M+): 528.2148; found:
528.2155.
1
0.32 g (60%) of 1k as an oil: H NMR (400 MHz, CDCl3): δ =
7.89–7.87 (m, 1H), 7.58–7.47 (m, 4H), 7.40–7.37 (m, 2H),
7.26–7.19 (m, 4H), 6.90–6.87 (m, 2H), 3.91 (t, J = 8.0 Hz, 1H),
3.82 (s, 3H), 3.65–6.63 (m, 6H), 3.38 (d, J = 7.6 Hz, 2H), 2.11
(s, 3H) ppm; 13C NMR (100 MHz, CDCl3): δ = 169.7, 169.1,
159.8, 139.9, 137.5, 133.2, 132.7, 132.1, 129.7, 128.9, 128.2,
128.1, 126.8, 123.2, 121.8, 114.8, 114.0, 95.2, 89.9, 85.1, 84.9,
64.5, 55.2, 52.4, 52.4, 51.9, 33.7, 20.8 ppm; MS: m/z (%) = 524
(M+, 24.18), 43 (100); IR (neat): 2952, 2214, 1735, 1486, 1150,
953, 757 cm−1; HRMS calcd for C32H28O7 (M+): 524.1835;
found: 524.1829.
(14) Dimethyl 2-(2-(3-(2-(cyclopentenylethynyl)phenyl)-3-
(methoxycarbonyloxy)prop-1-ynyl)benzyl)malonate (1o). The
reaction of dimethyl 2-(2-(3-(2-(cyclopentenylethynyl)phenyl)-
3-hydroxyprop-1-ynyl)benzyl)malonate (0.44 g, 1 mmol), pyri-
dine (0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl
chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
(11) Diethyl 2-(2-(3-(2-(cyclohexenylethynyl)phenyl)-3-(meth-
oxycarbonyloxy)prop-1-ynyl)benzyl)malonate (1l). The reaction
of diethyl 2-(2-(3-(2-(cyclohexenylethynyl)phenyl)-3-hydroxy-
prop-1-ynyl)benzyl)malonate (0.48 g,
1 mmol), pyridine
1
(0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and ethyl
chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2 afforded
0.39 g (78%) of 1o as an oil: H NMR (400 MHz, CDCl3): δ =
7.84–7.82 (m, 1H), 7.49–7.47 (m, 2H), 7.39–7.19 (m, 5H), 6.98
(s, 1H), 6.21 (s, 1H), 3.90–3.82 (m, 4H), 3.65–3.64 (m, 6H),
3.37 (d, J = 7.6 Hz, 2H), 2.57–2.47 (m, 4H), 1.99–1.91 (m, 2H)
ppm; 13C NMR (100 MHz, CDCl3): δ = 169.1, 169.0, 154.7,
139.9, 139.1, 137.1, 132.7, 132.0, 129.6, 129.0, 128.3, 127.8,
126.8, 124.1, 123.0, 121.6, 92.6, 89.3, 86.9, 85.8, 68.2, 54.9,
52.3, 51.8, 36.1, 33.5, 33.4, 23.2 ppm; MS: m/z (%) = 500 (M+,
8.64), 59 (100); IR (neat): 2954, 1749, 1486, 1153, 1009,
853 cm−1; HRMS calcd for C30H28O7 (M+): 500.1835; found:
500.1829.
1
0.46 g (85%) of 1l as an oil: H NMR (400 MHz, CDCl3): δ =
7.84–7.82 (m, 1H), 7.49–7.45 (m, 2H), 7.36–7.32 (m, 2H),
7.27–7.19 (m, 3H), 6.97 (s, 1H), 6.28–6.27 (m, 1H), 4.14–4.09
(m, 4H), 3.85–3.82 (m, 4H), 3.36 (d, J = 8.4 Hz, 2H), 2.24–2.15
(m, 4H), 1.68–1.61 (m, 4H), 1.19–1.14 (m, 6H) ppm; 13C NMR
(100 MHz, CDCl3): δ = 168.7, 168.7, 154.7, 140.0, 136.9,
135.9, 132.7, 132.0, 129.7, 128.9, 128.9, 128.1, 127.9, 126.7,
123.2, 121.6, 120.4, 97.0, 89.2, 85.9, 83.3, 68.2, 61.2, 54.9,
52.0, 33.5, 28.8, 25.7, 22.2, 21.4, 13.9 ppm; MS: m/z (%) = 542
(M+, 3.49), 466 (100); IR (neat): 2935, 1748, 1483, 1256, 1008,
788 cm−1; HRMS calcd for C33H34O7 (M+): 542.2305; found:
542.2316.
Typical procedure for the preparation of fluorene derivatives 2
General experimental procedure: (1) Diethyl 6-phenyl-1H-
(12) Ethyl 2-(2-(3-(2-(cyclohexenylethynyl)phenyl)-3-(methoxy-
carbonyloxy)prop-1-ynyl)benzyl)-3-oxobutanoate
(1m). The
indeno[1,7-ab]fluorene-1,1(2H,11H)-dicarboxylate
(2a). An
reaction of ethyl 2-(2-(3-(2-(cyclohexenylethynyl)phenyl)-3-
hydroxyprop-1-ynyl)benzyl)-3-oxobutanoate (0.45 g, 1 mmol),
pyridine (0.32 g, 4.0 mmol), DMAP (22.4 mg, 0.2 mmol), and
ethyl chloroformate (0.44 g, 4.0 mmol) in 10 mL of CH2Cl2
oven-dried Schlenk tube containing a Teflon-coated stirring bar
was charged with Pd(PPh3)4 (10 mg, 5 mol%), Cs2CO3
(130 mg, 0.4 mmol). The Schlenk tube was sealed, evacuated
and backfilled with N2 (3 cycles). A solution of propargylic
compound 1a (108 mg, 0.2 mmol) in DMF (3.0 mL) was sub-
sequently injected to the Schlenk tube. The reaction mixture was
stirred at 60 °C. When the reaction was complete as determined
by TLC analysis, the resulting mixture was allowed to cool to
room temperature and quenched with a saturated aqueous
1
afforded 0.45 g (88%) of 1m as an oil: H NMR (400 MHz,
CDCl3): δ = 7.80–7.78 (m, 1H), 7.48–7.45 (m, 2H), 7.36–7.32
(m, 2H), 7.27–7.18 (m, 3H), 6.96 (s, 1H), 6.27 (s, 1H),
4.10–4.00 (m, 3H), 3.82 (s, 3H), 3.31–3.22 (m, 2H), 2.24 (m,
2H), 2.17–2.15 (m, 5H), 1.69–1.60 (m, 4H), 1.17–1.12 (m, 3H)
This journal is © The Royal Society of Chemistry 2012
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solution of ammonium chloride, and the mixture was extracted
with EtOAc. The combined organic extracts were washed with
water and saturated brine. The organic layers were dried over
Na2SO4 and filtered. Solvents were evaporated under reduced
pressure. The residue was purified by chromatography on silica
gel to afford 69 mg (75%) of 2a. Solid; m.p. 128–131 °C (pet-
= 7.6 Hz, 1H), 4.36–4.26 (m, 4H), 4.25 (s, 2H), 4.18 (s, 2H),
1.32 (t, J = 7.0 Hz, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ =
169.7, 144.6, 140.8, 140.3, 140.2, 138.1, 137.0, 136.8, 134.7,
133.8, 131.4, 131.1, 130.9, 129.3, 127.6, 127.2, 126.3, 124.9,
123.5, 121.7, 119.3, 65.0, 62.1, 41.5, 35.3, 14.1 ppm; MS: m/z
(%) = 498 (M+(37Cl), 15.73), 496 (M+(35Cl), 40.35), 84 (100);
IR (neat): 2981, 1728, 1482, 1244, 1013, 911, 773 cm−1; HRMS
calcd for C31H25O435Cl (M+): 496.1441; found: 496.1440.
1
roleum ether–ethyl acetate); H NMR (400 MHz, CDCl3): δ =
7.60–7.50 (m, 4H), 7.44–7.41 (m, 2H), 7.38–7.26 (m, 3H),
7.24–7.19 (m, 1H), 7.00 (t, J = 7.4 Hz, 1H), 6.59 (d, J = 8.0 Hz,
1H), 4.34–4.26 (m, 4H), 4.26 (s, 2H), 4.18 (s, 2H), 1.31 (t, J =
7.0 Hz, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ = 169.8,
144.5, 141.1, 140.2, 138.3, 138.1, 137.1, 134.3, 132.7, 131.1,
129.9, 129.0, 127.7, 127.4, 127.0, 126.2, 124.7, 123.7, 122.0,
119.2, 65.0, 62.0, 41.5, 35.3, 14.1 ppm; MS: m/z (%) = 462
(M+, 95.64), 315 (100); IR (neat): 2977, 1721, 1468, 1251,
1122, 915, 769 cm−1; HRMS calcd for C31H26O4 (M+):
462.1831; found: 462.1837.
(5) Diethyl 6-(4-fluorophenyl)-1H-indeno[1,7-ab]fluorene-1,1-
(2H,11H)-dicarboxylate (2e). The reaction of 1e (112 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 62 mg (65%) of 2e. Solid;
m.p. 126–129 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.54 (d, J = 8.0 Hz, 1H), 7.42–7.35 (m,
3H), 7.34–7.22 (m, 5H), 7.05 (t, J = 7.6 Hz, 1H), 6.61 (d, J =
7.6 Hz, 1H), 4.37–4.27 (m, 4H), 4.25 (s, 2H), 4.18 (s, 2H), 1.32
(t, J = 7.2 Hz, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ =
169.8, 162.5 (d, J = 244 Hz), 144.6, 140.9, 140.4 (d, J = 19.5
Hz), 138.1, 137.1, 134.6, 134.1 (d, J = 2.6 Hz), 131.7 (d, J = 7.9
Hz), 131.5, 131.1, 127.5, 127.2, 126.3, 124.9, 123.5, 121.7,
119.3, 116.2, 116.0, 65.0, 62.1, 41.5, 35.3, 14.2 ppm; MS: m/z
(%) = 480 (M+, 14.34), 84 (100); IR (neat): 2964, 1728, 1599,
1467, 1177, 911 cm−1; HRMS calcd for C31H25O4F (M+):
480.1737; found: 480.1732.
The following compounds were prepared according to this
procedure.
(2) Diethyl 6-p-tolyl-1H-indeno[1,7-ab]fluorene-1,1(2H,11H)-
dicarboxylate (2b). The reaction of 1b (110 mg, 0.2 mmol), Pd
(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg, 0.4 mmol) in
DMF (3.0 mL) afforded 68 mg (72%) of 2b. Solid; m.
p. 142–145 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.52 (d, J = 7.6 Hz, 1H), 7.42–7.28 (m,
7H), 7.23 (t, J = 7.4 Hz, 1H), 7.04 (t, J = 7.6 Hz, 1H), 6.67 (d, J
= 8.0 Hz, 1H), 4.37–4.25 (m, 4H), 4.24 (s, 2H), 4.18 (s, 2H),
2.54 (s, 3H), 1.32 (t, J = 7.2 Hz, 6H) ppm; 13C NMR (100 MHz,
CDCl3): δ = 169.9, 144.5, 141.2, 140.24, 140.16, 138.1, 137.4,
137.1, 135.2, 134.2, 132.8, 131.2, 129.7, 127.3, 127.0, 126.2,
124.7, 123.7, 122.1, 119.2, 65.0, 62.0, 41.6, 35.3, 21.5,
14.2 ppm; MS: m/z (%) = 476 (M+, 40.79), 84 (100); IR (neat):
2980, 1729, 1466, 1243, 1121, 910, 728 cm−1; HRMS calcd for
C32H28O4 (M+): 476.1988; found: 476.1980.
(6)Dimethyl 6-phenyl-1H-indeno[1,7-ab]fluorene-1,1(2H,11H)-
dicarboxylate (2f). The reaction of 1f (102 mg, 0.2 mmol, Pd
(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg, 0.4 mmol) in
DMF (3.0 mL) afforded 62 mg (72%) of 2f. Solid; m.
p. 168–171 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.60–7.52 (m, 4H), 7.43–7.21 (m, 6H),
7.01 (t, J = 7.8 Hz, 1H), 6.59 (d, J = 7.6 Hz, 1H), 4.20 (s, 2H),
4.19 (s, 2H), 3.82 (s, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ
= 170.3, 144.5, 141.0, 140.2, 140.0, 138.2, 138.0, 137.0, 134.2,
132.8, 131.1, 129.9, 129.0, 127.8, 127.4, 127.1, 126.3, 124.8,
123.7, 122.1, 119.3, 64.7, 53.0, 41.6, 35.1 ppm; MS: m/z (%) =
434 (M+, 52.54), 315 (100); IR (neat): 2954, 1745, 1492, 1255,
1105, 922, 752, cm−1; HRMS calcd for C29H22O4 (M+):
434.1518; found: 434.1510.
(3) Diethyl 6-(4-methoxyphenyl)-1H-indeno[1,7-ab]fluorene-
1,1(2H,11H)-dicarboxylate (2c). The reaction of 1c (114 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 72 mg (73%) of 2c. Solid;
m.p. 135–138 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.52 (d, J = 7.6 Hz, 1H), 7.40–7.29 (m,
5H), 7.25–7.20 (m, 1H), 7.12 (d, J = 8.8 Hz, 2H), 7.04 (t, J =
7.6 Hz, 1H), 6.70 (d, J = 7.6 Hz, 1H), 4.32–4.25 (m, 4H), 4.25
(s, 2H), 4.18 (s, 2H), 3.94 (s, 3H), 1.32 (t, J = 7.0 Hz, 6H) ppm;
13C NMR (100 MHz, CDCl3): δ = 169.9, 159.2, 144.5, 141.2,
140.5, 140.2, 138.1, 137.1, 134.2, 132.4, 131.4, 131.0, 130.3,
127.3, 127.0, 126.3, 124.7, 123.7, 122.1, 119.1, 114.4, 65.0,
62.0, 55.3, 41.5, 35.3, 14.2 ppm; MS: m/z (%) = 492 (M+,
29.48), 84 (100); IR (neat): 2980, 1728, 1607, 1242, 1049, 852,
729 cm−1; HRMS calcd for C32H28O5 (M+): 492.1937; found:
492.1933.
(7) Ethyl 1-acetyl-6-phenyl-2,11-dihydro-1H-indeno[1,7-ab]-
fluorene-1-carboxylate (2g). The reaction of 1g (102 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 54 mg (62%) of 2g. Solid;
m.p. 116–119 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.62–7.48 (m, 4H), 7.45–7.28 (m, 5H),
7.22 (t, J = 7.4 Hz, 1H), 7.01 (t, J = 7.6 Hz, 1H), 6.59 (d, J =
8.0 Hz, 1H), 4.38–4.27 (m, 4H), 4.00 (d, J = 23.2 Hz, 1H), 3.85
(d, J = 18.0 Hz, 1H), 2.18 (s, 3H), 1.33 (t, J = 7.2 Hz, 3H) ppm;
13C NMR (100 MHz, CDCl3): δ = 201.9, 170.4, 144.5, 140.9,
140.3, 139.9, 138.3, 138.2, 137.7, 134.4, 132.7, 131.3, 130.0,
129.9, 129.1, 129.0, 127.8, 127.5, 127.2, 126.3, 124.8, 123.7,
122.3, 119.4, 72.0, 62.0, 40.3, 35.3, 26.0, 14.2 ppm; MS: m/z
(%) = 432 (M+, 65.64), 317 (100); IR (neat): 2981, 1712, 1465,
1246, 1123, 1074, 908, 775 cm−1; HRMS calcd for C30H24O3
(M+): 432.1725; found: 432.1733.
(4) Diethyl 6-(4-chlorophenyl)-1H-indeno[1,7-ab]fluorene-1,1-
(2H,11H)-dicarboxylate (2d). The reaction of 1d (114 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 77 mg (78%) of 2d. Solid;
m.p. 141–144 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.60 (t, J = 9.8 Hz, 3H), 7.41–7.30 (m,
4H), 7.25 (t, J = 7.6 Hz, 2H), 7.06 (t, J = 7.4 Hz, 1H), 6.66 (d, J
(8) Methyl 1-cyano-6-phenyl-2,11-dihydro-1H-indeno[1,7-ab]-
fluorene-1-carboxylate (2h). The reaction of 1h (95 mg,
3702 | Org. Biomol. Chem., 2012, 10, 3696–3704
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0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 36 mg (45%) of 2h. Solid;
m.p. 216–219 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.64–7.56 (m, 4H), 7.46–7.24 (m, 6H),
7.05 (t, J = 7.6 Hz, 1H), 6.61 (d, J = 8.4 Hz, 1H), 4.41 (d, J =
16.8 Hz, 1H), 4.38 (d, J = 22.0 Hz, 1H), 4.14 (d, J = 17.2 Hz,
1H), 4.07 (d, J = 22.0 Hz, 1H), 3.89 (s, 3H) ppm; 13C NMR
(100 MHz, CDCl3): δ = 167.4, 143.8, 140.6, 140.5, 138.6,
137.6, 136.8, 135.9, 133.6, 132.1, 131.6, 129.8, 129.7, 129.2,
129.1, 128.1, 127.6, 126.7, 125.1, 123.8, 122.8, 119.9, 117.7,
54.0, 50.4, 43.6, 33.7, 29.7 ppm; MS: m/z (%) = 401 (M+,
37.77), 342 (100); IR (neat): 2978, 2240, 1754, 1430, 1247,
903 cm−1; HRMS calcd for C28H19NO2 (M+): 401.1416; found:
401.1417.
124.9, 123.8, 121.8, 119.25, 119.22, 71.9, 61.9, 40.3, 35.3, 29.4,
29.3, 26.0, 25.9, 25.6, 23.3, 22.2, 14.2 ppm; cm−1; MS: m/z (%)
= 436 (M+, 8.06), 43 (100); IR (neat): 2923, 1719, 1377, 1242,
1159, 1072 cm−1; HRMS calcd for C30H28O3 (M+): 436.2038;
found: 436.2036.
(12) Diethyl 6-cyclopentenyl-1H-indeno[1,7-ab]fluorene-1,1-
(2H,11H)-dicarboxylate (2n). The reaction of 1n (106 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 68 mg (75%) of 2n as an
1
oil: H NMR (400 MHz, CDCl3): δ = 7.95 (t, J = 4.0 Hz, 1H),
7.70 (d, J = 8.4 Hz, 1H), 7.56 (d, J = 5.6 Hz, 1H), 7.45 (t, J =
7.8 Hz, 1H), 7.38–7.28 (m, 3H), 5.89 (s, 1H), 4.34–4.22 (m,
4H), 4.20 (s, 2H), 4.14 (s, 2H), 2.89–2.64 (m, 4H), 2.32–2.24
(m, 2H), 1.30 (t, J = 7.0 Hz, 6H) ppm; 13C NMR (100 MHz,
CDCl3): δ = 169.9, 144.4, 141.2, 140.4, 139.3, 138.1, 137.2,
133.7, 130.6, 130.3, 130.2, 127.2, 127.0, 126.6, 124.8, 123.5,
121.6, 119.1, 64.9, 62.0, 41.5, 36.8, 35.2, 33.7, 24.0, 14.1 ppm;
MS: m/z (%) = 452 (M+, 16.87), 43 (100); IR (neat): 2981,
1723, 1428, 1249, 1176, 1051, 948, 767 cm−1; HRMS calcd for
C30H28O4 (M+): 452.1988; found: 452.1979.
(9) Dimethyl 6-(4-methoxyphenyl)-1H-indeno[1,7-ab]fluorene-
1,1(2H,11H)-dicarboxylate (2j). The reaction of 1j (108 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 65 mg (70%) of 2j. Solid;
m.p. 210–213 °C (petroleum ether–ethyl acetate); 1H NMR
(400 MHz, CDCl3): δ = 7.53 (d, J = 7.6 Hz, 1H), 7.41–7.29 (m,
5H), 7.24 (t, J = 7.2 Hz, 1H), 7.13 (d, J = 8.8 Hz, 2H), 7.05 (t, J
= 7.6 Hz, 1H), 6.70 (d, J = 8.0 Hz, 1H), 4.19 (s, 4H), 3.95 (s,
3H), 3.82 (s, 6H) ppm; 13C NMR (100 MHz, CDCl3): δ =
170.4, 159.2, 144.5, 141.2, 140.6, 140.0, 138.1, 137.0, 134.1,
132.6, 131.5, 131.0, 130.3, 127.4, 127.1, 126.3, 124.8, 123.8,
(13) Dimethyl 6-cyclopentenyl-1H-indeno[1,7-ab]fluorene-1,1-
(2H,11H)-dicarboxylate (2o). The reaction of 1o (100 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 66 mg (78%) of 2o as an
1
122.2, 119.2, 114.4, 64.7, 55.3, 53.0, 41.6, 35.2 ppm; cm−1
;
oil: H NMR (400 MHz, CDCl3): δ = 7.94 (d, J = 7.2 Hz, 1H),
MS: m/z (%) = 464 (M+, 100); IR (neat): 2980, 2903, 1732,
1403, 1247, 1055, 894 cm−1; HRMS calcd for C30H24O5 (M+):
464.1624; found: 464.1629.
7.70 (d, J = 8.4 Hz, 1H), 7.57 (d, J = 6.4 Hz,1H), 7.46 (t, J =
7.8 Hz, 1H), 7.39–7.30 (m, 3H), 5.89 (s, 1H), 4.15 (s, 4H), 3.80
(s, 6H), 2.91–2.66 (m, 4H), 2.34–2.22 (m, 2H) ppm; 13C NMR
(100 MHz, CDCl3): δ = 170.4, 144.4, 141.2, 140.3, 140.2,
139.3, 138.1, 137.1, 133.6, 130.7, 130.2, 130.28, 127.3, 127.1,
126.7, 124.9, 123.5, 121.7, 119.2, 64.7, 53.0, 41.6, 36.8, 35.1,
33.8, 24.0 ppm; MS: m/z (%) = 424 (M+, 13.37), 43 (100); IR
(neat): 2950, 1732, 1608, 1115, 950, 772 cm−1; HRMS calcd for
C28H24O4 (M+): 424.1675; found: 424.1667.
(10) Diethyl 6-cyclohexenyl-1H-indeno[1,7-ab]fluorene-1,1-
(2H,11H)-dicarboxylate (2l). The reaction of 1l (108 mg,
0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3 (130 mg,
0.4 mmol) in DMF (3.0 mL) afforded 75 mg (80%) of 2l as an
1
oil: H NMR (400 MHz, CDCl3): δ = 8.11 (d, J = 7.2 Hz, 1H),
7.77 (d, J = 8.0 Hz, 1H), 7.57 (d, J = 7.2 Hz, 1H), 7.46 (t, J =
7.6 Hz, 1H), 7.39–7.28 (m, 3H), 5.86 (d, J = 1.2 Hz, 1H),
4.34–4.21 (m, 4H), 4.20 (s, 2H), 4.14 (s, 2H), 2.44–2.21 (m,
4H), 2.04–1.80 (m, 4H), 1.34–1.26 (m, 6H) ppm; 13C NMR
(100 MHz, CDCl3): δ = 169.9, 144.4, 141.3, 140.3, 138.8,
138.2, 137.3, 135.2, 134.9, 133.4, 130.2, 127.5, 127.1, 126.9,
126.5, 124.8, 123.7, 121.6, 119.0, 64.9, 61.9, 41.5, 35.3, 29.3,
25.6, 23.2, 22.2, 14.1 ppm; MS: m/z (%) = 466 (M+, 29.48), 43
Acknowledgements
We are grateful to the National Natural Science Foundation of
China (Project Nos. 20732005 and 20872127) and National
Basic Research Program of China (973 Program,
2009CB825300) for financial support.
(100); IR (neat): 2928, 1729, 1445, 1336, 1094, 908, 726 cm−1
HRMS calcd for C31H30O4 (M+): 466.2144; found: 466.2141.
;
Notes and references
(11) Ethyl 1-acetyl-6-cyclohexenyl-2,11-dihydro-1H-indeno-
[1,7-ab]fluorene-1-carboxylate (2m). The reaction of 1m
(102 mg, 0.2 mmol), Pd(PPh3)4 (10 mg, 5 mol%), and Cs2CO3
(130 mg, 0.4 mmol) in DMF (3.0 mL) afforded 55 mg (64%) of
1 (a) H. E. Katz, Z. Bao and S. L. Gilat, Acc. Chem. Res., 2001, 34, 359;
(b) C. D. Dimitrakopoulos and P. R. L. Malenfant, Adv. Mater., 2002, 14,
99.
2 (a) R. Freundenmann, B. Behnisch and M. Hanack, J. Mater. Chem.,
2001, 11, 1618; (b) L. Schmidt-Mende, A. Fechtenkötter, K. Müllen,
E. Moons, R. H. Friend and J. D. MacKenzie, Science, 2001, 293, 1119;
(c) A. M. van de Craats, N. Stutzmann, O. Bunk, M. M. Nielsen,
M. Watson, K. Müllen, H. D. Chanzy, H. Sirringhaus and R. H. Friend,
Adv. Mater., 2003, 15, 495; (d) J. E. Anthony, Angew. Chem., Int. Ed.,
2008, 47, 452; (e) W. Pisula, X. Feng and K. Müllen, Chem. Rev., 2011,
23, 554; (f) J. Wu, W. Pisula and K. Müllen, Chem. Rev., 2007, 107, 718;
(g) B. R. Kaafarani, Chem. Mater., 2011, 23, 378.
3 (a) S. J. Gould, C. R. Melville, M. C. Cone, J. Chen and J. R. Carney, J.
Org. Chem., 1997, 62, 320.
4 For a most recent monograph, see: Modern Allene Chemistry, ed. N.
Krause and A. S. K. Hashmi, Wiley-VCH, Weinheim, 2004, vols. 1, 2.
1
2m (dr = 1 : 1) as an oil: H NMR (400 MHz, CDCl3): δ = 8.11
(d, J = 7.6 Hz, 1H), 7.80–7.77 (m, 1H), 7.55 (d, J = 6.8 Hz,
1H), 7.48 (d, J = 7.4 Hz, 2H), 7.40–7.30 (m, 3H), 5.86 (s, 1H),
4.37–4.20 (m, 4H), 3.94 (dd, J1 = 22.4 Hz, J2 = 4.4 Hz, 1H),
3.81 (dd, J1 = 17.6 Hz, J2 = 2.8 Hz, 1H), 2.50–2.30 (m, 4H),
2.13 (d, J = 9.6 Hz, 3H), 2.05–1.89 (m, 4H), 1.36–1.25 (m, 3H)
ppm; 13C NMR (100 MHz, CDCl3): δ = 202.2, 202.1, 170.5,
144.4, 141.1, 140.0, 139.0, 138.4, 138.0, 137.9, 135.3, 135.2,
134.9, 134.8, 133.4, 130.54, 130.51, 127.7, 127.2, 127.1, 126.6,
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5 For reviews, see: (a) K. K. Wang, Chem. Rev., 1996, 96, 207; (b) J.
A. Marshall, Chem. Rev., 2000, 100, 3163; (c) A. S. K. Hashmi, Angew.
Chem., Int. Ed., 2000, 39, 3590; (d) R. Zimmer, C. U. Dinesh,
E. Nandanan and F. A. Khan, Chem. Rev., 2000, 100, 3067; (e) X. Lu,
C. Zhang and Z. Xu, Acc. Chem. Res., 2001, 34, 535; (f) R. W. Bates
and V. Satcharoen, Chem. Soc. Rev., 2002, 31, 12; (g) S. Ma, Acc. Chem.
Res., 2003, 36, 701; (h) L. K. Sydnes, Chem. Rev., 2003, 103, 1133;
(i) L. Brandsma and N. A. Nedolya, Synthesis, 2004, 735; ( j) M.
A. Tius, Acc. Chem. Res., 2003, 36, 284; (k) L. L. Wei, H. Xiong and R.
P. Hsung, Acc. Chem. Res., 2003, 36, 773; (l) S. Ma, Palladium-Cata-
lyzed Two or Three-Component Cyclization of Functionalized Allenes in
Palladiumin Organic Synthesis, ed. J. Tsuji, Springer, Berlin, Heidelberg,
2005, pp. 183–210; (m) S. Ma, Chem. Rev., 2005, 105, 2829; (n) S. Ma,
Aldrichimica Acta, 2007, 40, 91; (o) H. Kim and L. J. Williams, Curr.
Opin. Drug Discovery Dev., 2008, 11, 870; (p) M. Brasholz, H.-
U. Reissig and R. Zimmer, Acc. Chem. Res., 2009, 42, 45; (q) S. Ma,
Acc. Chem. Res., 2009, 42, 1679.
6 For reviews on the natural products and pharmaceuticals containing
allene unit(s), see: (a) A. Hoffmann-Röder and N. Krause, Angew.
Chem., Int. Ed., 2004, 43, 1196; (b) N. Krause and A. Hoffmann-Röder,
Chapter 18 in ref. 1 (c) G. Hu, K. Liu and L. Williams, Org. Lett., 2008,
10, 5493; (d) S. Wang, W. Mao, Z. She, C. Li, D. Yang, Y. Lin and L. Fu,
Bioorg. Med. Chem. Lett., 2007, 17, 2785; (e) E. G. Lyakhova, A.
I. Kalinovsky, A. S. Dmitrenok, S. A. Kolesnikova, S. N. Fedorov, V.
E. Vaskovsky and V. A. Stonik, Tetrahedron Lett., 2006, 47, 6549;
(f) X. Jiang, C. Fu and S. Ma, Eur. J. Org. Chem., 2010, 687;
(g) W. Kong, C. Fu and S. Ma, Chem.–Eur. J., 2011, 17, 13134.
7 (a) R. Shen and X. Huang, Org. Lett., 2008, 10, 3283; (b) R. Shen,
S. Zhu and X. Huang, J. Org. Chem., 2009, 74, 4118.
8 (a) R. Shen, X. Huang and L. Chen, Adv. Synth. Catal., 2008, 350, 2865.
9 (a) F. Sha and X. Huang, Angew. Chem., Int. Ed., 2009, 48, 3458;
(b) X. Huang, S. Zhu and R. Shen, Adv. Synth. Catal., 2009, 351, 3118;
(c) J. Cao and X. Huang, Org. Lett., 2010, 12, 5048.
10 (a) R. Shen, X. Huang and L. Chen, Adv. Synth. Catal., 2009, 351, 2833.
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