A simple and efficient synthesis of 9-arylfluorenes via metal-free reductive coupling of arylboronic acids and N-tosylhydrazones in situ

Article abstract of DOI:10.1039/c5ra12099c

A general, yet efficient synthesis method of 9-arylfluorenes via metal-free reductive coupling of N-tosylhydrazones and arylboronic acids has been developed. This methodology is realized by a one-pot protocol in two steps involving the preparation of N-tosylhydrazones by reacting tosylhydrazide with 9-fluorenone derivatives, followed by the reductive coupling of arylboronic acid in the presence of potassium carbonate to afford various 9-arylfluorenes analogues in moderate to excellent yields. Importantly, the catalytic system presented here enables the use of easily accessible starting materials and can be employed on a wide variety of substrates with good functional group tolerance. This protocol could also be particularly useful for the synthesis of 9-fluorenyl-substituted carbazolyl compounds.

Full text of DOI:10.1039/c5ra12099c

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ARTICLE
A simply and efficient synthesis of 9-arylfluorenes via metal-free
reductive coupling of arylboronic acids and N-tosylhydrazones in
situ
Received 00th January 20xx,
Accepted 00th January 20xx
Xu Shen, Ningning Gu, Ping Liu*, Xiaowei Ma, Jianwei Xie, Yan Liu*, Lin He and Bin Dai
DOI: 10.1039/x0xx00000x
A general, yet efficient synthesis of 9-arylfluorenes via metal-free reductive coupling of N-tosylhydrazones and arylboronic
acids has been developed. This methodology is realized by a one-pot protocol in two steps involving the preparation of N-
tosylhydrazones by reacting tosylhydrazide with 9-fluorenone derivatives, followed by the reductive coupling of
arylboronic acid in the presence of potassium carbonate to afford various 9-arylfluorenes analogues in moderate to
excellent yields. Importantly, the catalytic system presented here enables the use of easily accessible starting materials
and can be employed on a wide variety of substrates with good functional group tolerance. This protocol could also be
www.rsc.org/
particularly
useful
for
the
synthesis
of
9-fluorenyl-substituted
carbazolyl
compounds.
also been shown to furnish 9-arylfluorenes (cf. Method 4).[6]
Moreover, 9-arylfluorenes can be obtained from 9-
bromofluorene through p-toluenesulfonic acid catalyzing the
intermolecular coupling reaction (cf. Method 5),[7] and the
zinc-mediated radical reaction (cf. Method 6).[8] Although the
methods listed above prove to be effective for the synthesis of
9-arylfluorenes, certain disadvantages particularly involving a
narrow substrate scope and poor functional group tolerance
need to be addressed. The 9-arylfluorene scaffold is usually
constructed via multi-step reactions that sometimes require
the use of a strongly acidic medium or a stoichiometric
amount of a Lewis acid. However, it is worth noting that a
transition metal catalyzed coupling reaction has been
developed for the direct synthesis of 9-arylfluorenes. For
example, Chandrasekhar et al. developed a catalytic protocol
for the synthesis of 9-arylfluorenes via palladium-catalyzed
Suzuki-Miyaura coupling of 9-bromofluorene with arylboronic
acids (cf. Method 7).[9] Wu et al. reported a catalytic system
consisting of palladium(II) acetate and tricyclohexylphosphine
with the reaction of fluorene with haloarenes to provide 9-
arylfluorenes in good to excellent yields (cf. Method 8). [10]
The synthetic protocol proposed here will not only mitigate
the mentioned disadvantages of Methods 1-6, but will also
efficiently reduce the number of reaction steps needed to
carry out the synthesis.
Introduction
Fluorene proves to be an important structural scaffold and can
be found in a variety of applications involving advanced
materials, mostly due to its unique electronic and photonic
properties.[1] Notably, 9-arylfluorenes have attracted
considerable attention as compounds with promising
properties to find use in, e.g., blue fluorescent organic light
emitting materials, thin film transistors, photovoltaic cells,
etc.[2] As a consequence, the development of new synthetic
methods for the preparation of 9-arylfluorenes has been the
main focus of related fields in recent years. In general, the
reaction between 9-fluorenone and organomagnesium or
organolithium compounds yields the corresponding carbinols,
which can be transformed into 9-arylfluorenes by treatment
with Et2O∙BF3/Et3SiH or TsOH (cf. Method 1).[3] Alternatively, a
catalytic system consisting of phenyl methyl sulfoxide (PMSO)
and the polyoxomolybdate [PMo12O40]3-, triphenylmethane
provides 9-phenylfluorene via a triphenylmethane cation (cf.
Method 2).[4] Recently, a novel strategy for the preparation of
9-arylfluorenes via intramolecular tandem reactions of 2-
arylbenzaldehydes with arenes catalyzed by CF3SO3H or a
combination of bimetallic “Pd–Sn” and AgPF6 system has been
reported (cf. Method 3).[5] Additionally, Friedel-Crafts
cyclization reactions of biaryl alcohols or acetates catalyzed by
a Brøsted or Lewis acid, such as HCl/HOAc or BF3∙Et2O, have
N-tosylhydrazones prove to be highly versatile synthetic
intermediates that have attracted considerable interest in a
variety of research fields in recent years.[11] In 2007, Valdés
[12] and coworkers from Wang’s group[13] developed a series
of transformation reactions with tosylhydrazones. To the best
of our knowledge, as early as 2009, Valdés et al. have
developed a new metal-free C-C bond formation reaction
between N-tosylhydrazones and boronic acid derivatives that
proved to be suitable for the preparation of biarylmethane
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Table 1 Optimized reaction conditionsa
Entry
1
Base
Solvent
Yield (%)b
34
K2CO3 (1.5 equiv.)
K2CO3 (1.5 equiv.)
1,4-dioxane
Toluene
DMF
2
80
K2CO3 (1.5 equiv.)
K2CO3 (1.5 equiv.)
K3PO4 (1.5 equiv.)
Na2CO3 (1.5 equiv.)
NaOH (1.5 equiv.)
KOH (1.5 equiv.)
Cs2CO3 (1.5 equiv.)
K2CO3 (2 equiv.)
3
trace
41
4c
5
THF
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
67
6
31
7
46
8
48
9
70
10
11
87
Scheme 1 Synthetic methods for 9-arylfluorenes.
K2CO3 (3 equiv.)
89
structures. This process can be carried out without the need
for a metal catalyst and adapting extremely simple reaction
conditions exhibiting remarkably versatile applications.[12b]
Inspired by this work and in contrast to the methods
mentioned above, requiring a multi-step process for the
preparation of 9-arylfluorenes and the use a strongly acidic
medium, a Lewis acid, or a palladium catalyst promote these
catalytic reactions, we herein report a new method that
employs 9-fluorenone derivatives as a simple and readily
available starting material for the one-pot, two-step synthesis
of 9-arylfluorenes through the metal-free reductive coupling of
N-tosylhydrazones and arylboronic acids (cf. Method 9).
aReaction conditions: Reaction conditions: 0.50 mmol 9-fluorenone,
tosylhydrazide (1.5 equiv.), 0.75 mmol phenylboronic acid, 5 mL toluene, T1 = 80
ºC/t1 = 2 h, T2 = 110 ºC/t2 = 5 h. b GC-MS yield. cT1 = T2 = 65 ºC, yield of GC-MS.
was also investigated, but the high volatility of the solvent
forced us to lower the reaction temperature to 65 ºC, resulting
in a particularly low yield obtained (cf. Table 1, entry 4). The
screening of different bases revealed that K2CO3 proves to be
the most appropriate base for delivering the desired product
in 89% yield (cf. Table 1, entry 11), while other bases such as
K3PO4, Na2CO3, NaOH, KOH, and Cs2CO3 afforded significantly
lower yields (31-70%, cf. Table 1, entries 5-9). Meanwhile, the
base loading was found to be another crucial parameter with
the product yield increasing from 80% to 89% as the base
loading increases from 1.5 equivalents to 3.0 equivalents (cf.
Table 1, entries 2, 10 and 11), respectively. In summary, the
combination of 9-fluorenone (0.5 mmol), tosylhydrazide (1.5
equiv.), phenylboronic acid (0.75 mmol), K2CO3 (2 equivalents)
at T1 = 80 °C (t1 = 2 hours) and T2 = 110 °C (t2 = 5 hours) in
toluene (5 mL) were found to be the most suitable reaction
conditions.
Results and discussion
Optimization of the reaction conditions
Initially, 9-fluorenone (0.5 mmol) and phenylboronic acid (0.75
mmol) were chosen as model substrates for the reductive
coupling in the presence of tosylhydrazide (1.5 equivalents)
and potassium carbonate (K2 CO3 , 2 equivalents).
Tosylhydrazones prove to be easily accessible by reacting
tosylhydrazide with a corresponding ketone. Therefore, we
focussed our studies on the reductive coupling in an effort to
answer the question if this reaction could be carried out in a
one-pot fashion directly from 9-fluorenone and without the
need to isolate the intermediate, tosylhydrazone. Indeed, this
process proves to be feasible and can be carried out by simply
heating 9-fluorenone with tosylhydrazide for 2 hours at 80 ºC
prior to the addition of phenylboronic acid. Heating was then
continued for another 5 hours at 110 ºC and the product of
this reductive coupling, 9-phenyl-9H-fluorene, was obtained in
34% yield using 1,4-dioxane as a solvent. Furthermore, the
intermediate tosylhydrazone did not have to be isolated (cf.
Table 1, entry 2). A short list of solvents with similar boiling
points as 1,4-dioxane have been screened for applicability in
this reaction. Notably, sgnificantly higher yields have been
obtained using nonpolar solvent such as toluene; a lower yield
has been observed using dimethylformamide (DMF, cf. Table
1, entries 2 and 3) as solvent. The use of tetrahydrofuran (THF)
Scope and limitations of substrates
Upon optimizing the reaction conditions, we further
investigated the substrate scope of this one pot, two-step
reductive coupling reaction. As shown in Table 2, the 4-
substituted arylboronic acid substrates bearing electron-
withdrawing or electron-donating groups constantly afford the
desired products 3b-3g in good to excellent yields (78-92%).
Moreover, (3,4,5-trifluorophenyl)boronic acid and m-
tolylboronic acid were found to produce the desired coupling
products 3h and 3i in 79% and 88% yields, respectively.
Naphthalene-2-ylboronic acid has also been used as a coupling
partner to provide the product 3j in 77% yield. Furthermore,
the reductive coupling reactions involving orth-substituted
arylboronic acids with 9-fluorenone have been investigated.
Both the electronic properties and the steric hindrance of the
substrates seem to influence the coupling reaction. For
example, the coupling reaction of o-tolylboronic acid with 9-
fluorenone to afford the product 3k proceeds in 75% yield.
2 | J. Name., 2012, 00, 1-3
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Table 2 One-pot reductive coupling of substituted 9-fluorenones with boronic acidsa
Scheme 1 A gram-scale synthesis of product 3c
3q-3u in yields ranging from 62% to 93%. The synthesis of
substituted carbazolyl compounds has attracted considerable
interest due to the importance of this compound in numerous
photo devices, electroluminescent devices and photorefractive
materials.[18] However, to the best of our knowledge no
reports on the synthesis of 9-fluorenyl-substituted carbazolyl
compounds via metal free reductive coupling reactions have
been published to date. Therefore, this method provided
further incentive to be applied to the synthesis of 9-fluorenyl-
substituted carbazolyl compounds. The reaction of 9-
fluorenone with (3-(9H-carbazol-9-yl)phenyl)boronic acid, (9-
phenyl-9H-carbazol-3-yl)boronic acid and (4-(9H-carbazol-9-
yl)phenyl)boronic acid was carried out efficiently and the
desired products 3v-3x have been isolated in high yields
3b, 87%
3f, 87%
3c, 92%
3g, 91%
3d, 82%
3h, 79%
3e, 78%
3i, 88%
3j, 77%
3n, 85%
3r, 73%
3k, 75%
3o, 29%
3s, 93%
3l, 35%
3p, 92%
3t, 62%
3m, 37%
3q, 75%
3u, 82%
ranging
from
62
to
91%.
Furthermore,
(4-
(diphenylamino)phenyl)boronic acid can also react with 9-
fluorenone to afford the functionalized coupling product 3y in
65% yield.
A gram-scale synthesis was performed to verify the practical
application using this synthesis system. Fortunately, the
reaction was performed using 5 mmol of 9-fluorenone and 7.5
mmol (4-methoxyphenyl)boronic acid, and proceeded in 80%
yield leading to 1.08 g of the desired product 3c(Scheme 1).
Conclusions
To summarize, a simple and efficient method for the synthesis
of 9-arylfluorenes via metal-free reductive coupling of
arylboronic acids with N-tosylhydrazones in situ has been
developed, affording the corresponding target molecules in
moderate to excellent yields. Moreover, isolation of the
desired tosylhydrazones is not required and the reaction can
be carried out in one pot and in two steps, directly from the 9-
fluorenone derivatives. Potential substrates for this reaction
are diverse, exhibiting a superior functional-group tolerance.
Furthermore, no sophisticated experimental setups, e.g.
involving inert gasses or dry solvents, are required. Notably,
this protocol also proves suitable for the synthesis of 9-
fluorenyl-substituted carbazolyl compounds. Further studies to
investigate employing this system to other related reactions
are currently underway in our laboratory.
3v, 62%
3w, 71%
3x, 91%
3y, 65%
aReaction conditions: 0.50 mmol substituted 9-fluorenone, 0.75 mmol
phenylboronic acid, 1.5 equiv. base, 5 mL toluene, T1 = 80 ºC/t1 = 2 h, T2 = 110
ºC/t2 = 5 h. The yields of isolated products are given.
However, (2,3-difluorophenyl)boronic acid and (2,4-
difluorophenyl)boronic acid as substrates result in the
formation of the corresponding coupling products 3l and 3m in
low yields of 35% and 37%, respectively. Similarly, while
thiophen-3-ylboronic acid shows good reactivity towards
conversion into the corresponding product 3n in 85% yield, the
use of furan-2-ylboronic acid as the substrate results in the
formation of product 3o only in 29% yield. Noteworthy, the
reaction of butylboronic acid with 9-fluorenone has also been
attempted using standard reaction conditions. The desired
product 3p was obtained in 92% yield. To further investigate
the range of substrates that can be used in this process, a
variety of substituted 9-fluorenone derivatives have been
studied. The results show that the coupling reactions involving
substituted 9-fluorenone and (4-methoxyphenyl)boronic acid
work to our satifsaction and afford the corresponding products
Experimental
Materials and instruments
Chemicals were obtained commercially and used as received.
NMR spectra were recorded on
a Bruker DPX–400
spectrometer using TMS as the internal standard. EI–Mass
spectrum was measured on a LC/Q–TOF MS (Micromass,
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England) All products were isolated by short chromatography J = 1.1 Hz), 141.16 (s), 131.22 (d, J = 11.9 Hz), 127.57 (d, J =
on a silica gel (200–300 mesh) column using petroleum ether 17.4 Hz), 125.19 (d, J = 1.2 Hz), 124.15 (dd, J = 7.0, 4.7 Hz),
(60–90 °C), unless otherwise noted. 9-fluorenone and its 123.80 (s), 120.07 (s), 115.58 (d, J = 17.0 Hz), 77.34 (s), 77.02
derivatives, and arylboronic acids were of analytical grade (s), 76.71 (s), 29.72 (s). 19F NMR (376 MHz, CDCl3) δ -137.94 – -
quality, purchased from Adamas-beta Pharmaceuticals, Inc.
138.01 (m), -143.90 (d, J = 19.9 Hz). HRMS(EI):m/z calcd for
General procedure for the one-pot two-steps reductive coupling of C19H12F2 [M]+ 278.0907, found 278.0909. IR (KBr, cm−1): 1485,
N-tosylhydrazones and arylboronic acids
1446, 1280, 945, 800, 779, 742.
A solution of the 9-fluorenone derivatives
1
(0.5 mmol) and 9-(2,4-difluorophenyl)-9H-fluorene[3m]
1
C. H NMR (400 MHz, CDCl3) δ 7.80 (d, J = 7.6
tosylhydrazide (0.75 mmol) in 5 mL of toluene was stirred at Mp. 94.6-95.3
º
80 ºC for 2 h in a reaction tube. Potassium carbonate (1.0 Hz, 2H), 7.40 (t, J = 7.4 Hz, 2H), 7.34 (d, J = 7.4 Hz, 2H), 7.28 (dd,
mmol) and the appropriate boronic acid (0.75 mmol) were J = 7.4, 1.0 Hz, 2H), 6.94 – 6.87 (m, 1H), 6.70 – 6.59 (m, 2H),
2
added to the reaction mixture. The system was refluxed at 110 5.42 (s, 1H). 13C NMR (101 MHz, CDCl3) δ 146.55 (s), 141.11 (s),
ºC for 5 h with stirring. When the reaction was complete, the 127.51 (d, J = 12.4 Hz), 125.13 (d, J = 1.2 Hz), 120.05 (s), 111.74
crude mixture was allowed to reach room temperature. – 111.25 (m), 104.12 (s), 103.87 (s), 77.34 (s), 77.02 (s), 76.70
Dichloromethane and a saturated solution of NaHCO3 were (s). 19F NMR (376 MHz, CDCl3) δ -112.22 (dd, J = 6.8, 1.1 Hz), -
added and the layers were separated. The aqueous phase was 114.77 (s). HRMS(EI):m/z calcd for C19H12F2 [M]+ 278.0907,
extracted three times with dichloromethane. The combined found 278.0909. IR (KBr, cm−1): 1620, 1604, 1500, 1447, 1267,
organic layers were washed with a saturated solution of 964, 852, 739.
NaHCO3, one portion of brine and then dried over Na2SO4 and 2-bromo-9-(4-methoxyphenyl)-9H-fluorene[3q]
filtered. The solvent was removed under reduced pressure. Mp. 107-108 º
C. 1H NMR (400 MHz, CDCl3) δ 7.75 (d, J = 7.6 Hz,
The products were purified by chromatography on silica gel.
1H), 7.64 (d, J = 8.1 Hz, 1H), 7.49 (ddd, J = 8.1, 1.8, 0.7 Hz, 1H),
9-(4-propylphenyl)-9H-fluorene[3d]
7.44 – 7.32 (m, 2H), 7.32 – 7.23 (m, 2H), 7.02 – 6.94 (m, 2H),
Mp. 88-89 º
C. 1H NMR (400 MHz, CDCl3) δ 7.79 (dd, J = 7.6, 0.8 6.86 – 6.79 (m, 2H), 4.97 (s, 1H), 3.78 (s, 3H). 13C NMR (101
Hz, 2H), 7.40 – 7.31 (m, 4H), 7.29 – 7.22 (m, 2H), 7.03 (ddd, J = MHz, CDCl3) δ 158.74 (s), 150.23 (s), 147.90 (s), 139.88 (d, J =
9.8, 7.2, 1.9 Hz, 4H), 5.02 (s, 1H), 2.57 – 2.51 (m, 2H), 1.61 (ddd, 2.1 Hz), 132.57 (s), 130.43 (s), 129.29 (s), 128.54 (s), 127.73 (s),
J = 9.1, 7.5, 4.1 Hz, 2H), 0.96 – 0.90 (m, 3H). 13C NMR (101 MHz, 127.47 (s), 125.35 (s), 121.11 (d, J = 14.6 Hz), 119.92 (s), 114.26
CDCl3) δ 148.09 (s), 141.20 (s), 140.98 (s), 138.68 (s), 128.76 (s), (s), 55.27 (s), 53.61 (s). HRMS(EI): m/z calcd for C20H15BrO [M]+
128.13 (s), 127.25 (dd, J = 3.0, 2.1 Hz), 125.35 (s), 119.83 (s), 350.0306, found 350.0305. IR (KBr, cm−1): 1508, 1460, 1258,
77.36 (s), 77.04 (s), 76.72 (s), 54.13 (s), 37.74 (s), 24.52 (s), 1176, 742.
13.94 (s). HRMS(EI):m/z calcd for C22H24 [M]+ 284.1565,found 2,7-dibromo-9-(4-methoxyphenyl)-9H-fluorene[3r]
284.1563. IR (KBr, cm−1): 2953, 2928, 2826, 1510, 1448, 738.
Mp. 153.5-155.5
Hz, 2H), 7.46 (ddd, J = 8.1, 1.8, 0.7 Hz, 2H), 7.40 – 7.36 (m, 2H),
º
C. 1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 8.1
9-(4-pentylphenyl)-9H-fluorene[3e]
1
Mp.74-75
º
C. H NMR (400 MHz, CDCl3) δ 7.79 (d, J = 7.6 Hz, 6.92 (s, 2H), 6.81 (s, 2H), 4.92 (s, 1H), 3.76 (s, 3H). 13C NMR
2H), 7.39 – 7.31 (m, 4H), 7.25 (td, J = 7.2, 1.1 Hz, 3H), 7.07 (d, J (101 MHz, CDCl3) δ 158.95 (s), 149.88 (s), 138.85 (s), 131.60 (s),
= 8.2 Hz, 2H), 7.00 – 6.97 (m, 2H), 5.02 (s, 1H), 2.58 – 2.52 (m, 130.69 (s), 129.29 (d, J = 1.0 Hz), 128.61 (s), 121.52 (s), 121.25
2H), 1.63 – 1.53 (m, 3H), 1.34 – 1.24 (m, 5H), 0.88 (t, J = 7.0 Hz, (s), 114.42 (s), 77.36 (s), 77.04 (s), 76.73 (s), 55.30 (s), 53.50 (s).
3H). 13C NMR (101 MHz, CDCl3) δ 148.07 (s), 141.45 (s), 140.97 HRMS(EI):m/z calcd for C20H14Br2O [M]+ 429.9391, found
(s), 138.61 (s), 128.68 (s), 128.13 (s), 127.23 (d, J = 4.2 Hz), 429.9387. IR (KBr, cm−1): 1510, 1456, 1258, 964, 806.
125.34 (s), 119.82 (s), 77.34 (s), 77.02 (s), 76.71 (s), 54.11 (s), 9-(4-methoxyphenyl)-2-nitro-9H-fluorene[3s]
1
C. H NMR (400 MHz, CDCl3) δ 8.30 (d, J =
35.61 (s), 31.61 (s), 31.14 (s), 22.56 (s), 14.05 (s). HRMS(EI):m/z Mp. 149.8-151.1
º
calcd for C24H24 [M]+ 312.1878, found 312.1873. IR (KBr, cm−1): 15.8 Hz, 1H), 8.15 (s, 1H), 7.88 (d, J = 8.4 Hz, 2H), 7.39 (dd, J =
3048, 2951, 2876, 1510, 1449, 739.
5.8, 1.0 Hz, 3H), 7.00 (d, J = 8.6 Hz, 2H), 6.84 (d, J = 8.8 Hz, 2H),
5.09 (s, 1H), 3.79 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 158.98
9-(3,4,5-trifluorophenyl)-9H-fluorene[3h]
1
C. H NMR (400 MHz, CDCl3) δ 7.79 (dd, J = (s), 149.76 (s), 149.22 (s), 147.22 (s), 138.63 (s), 131.39 (s),
Mp.115.7-116.8
º
6.9, 0.7 Hz, 2H), 7.43 – 7.38 (m, 2H), 7.30 – 7.27 (m, 4H), 6.70 129.33 (d, J = 19.9 Hz), 127.90 (s), 125.70 (s), 123.57 (s), 121.26
(dd, J = 8.5, 6.5 Hz, 2H), 4.95 (s, 1H). 13C NMR (101 MHz, CDCl3) (s), 120.77 (s), 119.97 (s), 114.46 (s), 77.33 (s), 77.01 (s), 76.69
δ 146.28 (s), 140.94 (s), 127.96 (s), 127.62 (s), 125.14 (s), (s), 55.29 (s), 53.72 (s). HRMS(EI):m/z calcd for C20H15NO3 [M-
120.18 (s), 112.20 (dd, J = 15.6, 5.8 Hz), 86.82 (s), 77.35 (s), H]+ 316.0968, found 316.0973. IR (KBr, cm−1): 1510, 1333, 1258,
77.03 (s), 76.71 (s), 53.39 (s). 19F NMR (376 MHz, CDCl3) δ - 1030, 752.
134.06 (d, J = 20.7 Hz), -162.77 (t, J = 20.6 Hz). HRMS(EI):m/z 2-bromo-9-(4-methoxyphenyl)-7-nitro-9H-fluorene[3t]
calcd for C19H11F3 [M]+ 296.0813, found 296.0810. IR (KBr, Mp. 191.5-192.8
1
C. H NMR (400 MHz, CDCl3) δ 8.32 (dd, J =
º
8.2, 1.8 Hz, 1H), 8.16 (s, 1H), 7.88 (d, J = 8.4 Hz, 1H), 7.76 (d, J =
cm−1): 3048, 2951, 2876, 1510, 1449, 739.
9-(2,3-difluorophenyl)-9H-fluorene[3l]
8.2 Hz, 1H), 7.64 – 7.52 (m, 2H), 7.03 – 6.98 (m, 2H), 6.90 –
Mp. 100-101 º
C. 1H NMR (400 MHz, CDCl3) δ 7.80 (d, J = 7.6 Hz, 6.85 (m, 2H), 5.10 (s, 1H), 3.82 (s, 3H). 13C NMR (101 MHz,
2H), 7.43 – 7.34 (m, 4H), 7.28 (td, J = 7.4, 1.1 Hz, 2H), 7.07 – CDCl3) δ 159.20 (s), 151.59 (s), 148.94 (s), 147.48 (s), 146.10 (s),
6.98 (m, 1H), 6.84 (tdd, J = 8.1, 5.0, 1.7 Hz, 1H), 6.42 (dd, J = 7.7, 137.55 (s), 131.23 (s), 130.45 (s), 129.24 (s), 129.02 (s), 123.70
6.3 Hz, 1H), 5.49 (s, 1H). 13C NMR (101 MHz, CDCl3) δ 146.20 (d, (d, J = 8.0 Hz), 122.50 (s), 120.85 (s), 120.12 (s), 114.63 (s),
4 | J. Name., 2012, 00, 1-3
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77.33 (s), 77.01 (s), 76.69 (s), 55.32 (s), 53.64 (s). HRMS(EI):m/z
calcd for C20H14BrNO3 [M-H]+ 394.0073, found 394.0080. IR
(KBr, cm−1): 1600, 1510, 1337, 1250, 1028, 818, 737.
Acknowledgements
We gratefully acknowledge financial support of this work by
the National Natural Science Foundation of China (No.
21103114, No. 21463022), and Shihezi University Training
9-(4-methoxyphenyl)-9H-fluoren-2-amine[3u]
1
C. H NMR (400 MHz, CDCl3) δ 7.63 (d, J = 7.5
Mp. 161.4-162
º
Programme
for
Distinguished
Youth
Scholars
Hz, 1H), 7.56 (d, J = 8.1 Hz, 1H), 7.30 (t, J = 7.5 Hz, 1H), 7.22 (d,
J = 7.4 Hz, 1H), 7.14 (dd, J = 7.4, 1.0 Hz, 1H), 7.03 – 6.99 (m, 2H),
6.83 – 6.78 (m, 2H), 6.70 (dd, J = 8.1, 2.2 Hz, 1H), 6.63 (s, 1H),
4.89 (s, 1H), 3.77 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 158.45
(s), 150.13 (s), 147.34 (s), 141.36 (s), 133.98 (s), 129.35 (s),
127.13 (s), 125.63 (s), 125.00 (s), 120.68 (s), 118.54 (s), 114.42
(s), 114.05 (s), 112.01 (s), 77.34 (s), 77.02 (s), 76.71 (s), 55.24
(s), 53.54 (s). HRMS(EI):m/z calcd for C20H17NO [M]+ 287.1305,
found 287.1311. IR (KBr, cm−1): 3564, 3412, 1609, 1510, 1456,
1252, 1179, 1034, 825, 741.
(No.2014ZRKXJQ05), Key Scientific and Technological Project of
Shihezi University (gxjs2013-zdgg0201), and Start-Up
Foundation for Young Scientists of Shihezi University
(RCZX201408).
Notes and references
1
(a) H. Reisch, U. Wiester, U. Scherf and N. Tuytuylkov,
Macromolecules., 1996, 29, 8204; (b) C. Xia and R. C.
Advincula, Macromolecules., 2001, 34, 6922; (c) M. Ranger,
9-(3-(9H-fluoren-9-yl)phenyl)-9H-carbazole[3v]
Mp. 200.3-201.1 º
C. 1H NMR (400 MHz, CDCl3) δ 8.27 – 8.00 (m,
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2426; (d) S. Merlet, M. Birau and Z. Y. Wang, Org. Lett., 2002,
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,
2H), 7.79 (dd, J = 7.5, 0.8 Hz, 2H), 7.52 – 7.47 (m, 1H), 7.46 –
7.23 (m, 14H), 7.19 (s, 1H), 5.15 (s, 1H). 13C NMR (101 MHz,
CDCl3) δ 147.39 (s), 143.82 (s), 141.08 (s), 140.69 (s), 137.96 (s),
130.13 (s), 127.53 (d, J = 15.0 Hz), 127.24 (s), 126.88 (s), 125.89
(s), 125.29 (d, J = 2.2 Hz), 123.35 (s), 120.38 – 119.80 (m),
109.76 (s), 77.36 (s), 77.04 (s), 76.72 (s), 54.17 (s).
HRMS(EI):m/z calcd for C31H21N [M]+ 407.1674, found
407.1672. IR (KBr, cm−1): 3045, 1599, 1449, 1334, 1226, 1179,
1034, 825, 741.
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3-(9H-fluoren-9-yl)-9-phenyl-9H-carbazole[3w]
Mp. 101.1-101.9 º
C. 1H NMR (400 MHz, CDCl3) δ 8.05 (d, J = 7.8
8
2
Hz, 1H), 7.93 (d, J = 1.6 Hz, 1H), 7.84 (d, J = 7.6 Hz, 2H), 7.59 –
7.51 (m, 4H), 7.39 (ddd, J = 11.5, 9.8, 7.3 Hz, 7H), 7.29 – 7.25
(m, 3H), 7.24 (d, J = 1.2 Hz, 1H), 7.03 (d, J = 1.7 Hz, 1H), 5.24 (s,
1H). 13C NMR (101 MHz, CDCl3) δ 148.72 (s), 141.04 (d, J = 19.5
Hz), 137.73 (s), 133.02 (s), 129.83 (s), 127.25 (dd, J = 22.9, 11.6
Hz), 126.33 (s), 125.92 (s), 125.47 (s), 123.61 (s), 123.14 (s),
120.37 (s), 120.07 (s), 119.86 (d, J = 2.3 Hz), 110.08 (s), 109.77
(s), 77.35 (s), 77.03 (s), 76.71 (s), 54.64 (s). HRMS(EI):m/z calcd
for C31H21N [M]+ 407.1674, found 407.1672. IR (KBr, cm−1):
3267, 1595, 1501, 1448, 1323, 1234, 806, 735.
8
Fang, C. C. Chu, C. H. Huang, G. Raffy, A. Del Guerzo, K. T.
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(a) G. C. Vougioukalakis, M. M. Roubelakis, M. Orfanopoulos,
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9-(4-(9H-fluoren-9-yl)phenyl)-9H-carbazole[3x]
4
5
1
C. H NMR (400 MHz, CDCl3) δ 8.13 (dd, J =
Mp. 243.5-244.7
º
7.7, 0.8 Hz, 2H), 7.84 (dd, J = 7.2, 1.4 Hz, 2H), 7.48 – 7.38 (m,
10H), 7.37 – 7.25 (m, 6H), 5.18 (s, 1H). 13C NMR (101 MHz,
CDCl3) δ 147.53 (s), 141.19 – 140.76 (m), 136.35 (s), 129.70 (s),
127.82 – 127.10 (m), 125.87 (s), 125.43 (s), 123.32 (s), 120.28
(s), 119.96 (d, J = 20.0 Hz), 109.85 (s), 77.35 (s), 77.04 (s), 76.72
(s), 54.07 (s). HRMS(EI):m/z calcd for C31H21N [M]+ 407.1674,
found 407.1672. IR (KBr, cm−1): 3059, 1599, 1510, 1450, 1223,
745.
under warm and efficient conditions. RSC Adv., 2014,
27722. (b) D. Das, S. Pratihar and S. Roy, Org. Lett., 2012, 14
4
,
,
4870.
6
(a) S. Sarkar, S. Maiti, K. Bera, S. Jalal and U. Jana,
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4-(9H-fluoren-9-yl)-N,N-diphenylaniline[3y]
7
8
9
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1
C. H NMR (400 MHz, CDCl3) δ 7.79 (s, 2H),
Mp. 174.2-175.1
º
7.38 (d, J = 8.3 Hz, 4H), 7.29 (s, 2H), 7.19 (s, 4H), 7.05 (ddd, J =
4.4, 3.4, 1.8 Hz, 4H), 6.95 (s, 6H), 5.00 (s, 1H). 13C NMR (101
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15.2 Hz), 127.26 (d, J = 2.8 Hz), 125.36 (s), 124.16 (d, J = 7.2 Hz),
122.61 (s), 119.87 (s), 77.34 (s), 77.02 (s), 76.70 (s), 53.84 (s).
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IR (KBr, cm−1): 3036, 1585, 1495, 1448, 1328, 1273, 738, 649.
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