Synthesis of fluorescent fluorene-isoindole-containing mono- and oligomers

Article abstract of DOI:10.1016/j.tet.2014.04.018

Novel fluorene-isoindole-containing light-emitting mono- and oligomers were prepared. The synthesis of the monomers N-(4-bromo-phenyl)-2-(7-bromo-9,9- diethylfluoren-2-yl)-isoindole-1-carboxamide, N-(7-bromo-9,9-dibutylfluoren-2- yl)-2-(7-bromo-9,9-dibutylfluoren-2-yl)-isoindole-1-carboxamide, and N-[7-bromo-9,9-bis(2-ethylhexyl)-fluoren-2-yl]-2-[7-bromo-9,9-bis(2-ethylhexyl) -fluoren-2-yl]-isoindole -1-carboxamide was carried out by a three-component reaction of ortho-phthalaldehyde with the corresponding amine and isocyanide partners. The Ni(0) mediated polymerization reactions of the obtained monomers gave the corresponding mixture of oligomers from two up to twelve repeat units. The optical properties were also studied and it was found that the phenylene-containing oligomer emitted green light in dichloromethane solution, while both difluorene-containing oligomers, under the same conditions, proved to be blue light-emitters with good quantum efficiency.

Full text of DOI:10.1016/j.tet.2014.04.018

Tetrahedron 70 (2014) 3691e3699
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis of fluorescent fluoreneeisoindole-containing mono- and
oligomers
*
ꢀ
ꢀ ꢀ ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Laszlo Lazar, Miklos Nagy, David Racz, Miklos Zsuga, Sandor Keki
ꢀ
Department of Applied Chemistry, University of Debrecen, H-4032 Debrecen, Egyetem ter 1., Hungary
a r t i c l e i n f o
a b s t r a c t
Article history:
Novel fluoreneeisoindole-containing light-emitting mono- and oligomers were prepared. The synthesis
of the monomers N-(4-bromo-phenyl)-2-(7-bromo-9,9-diethylfluoren-2-yl)-isoindole-1-carboxamide,
N-(7-bromo-9,9-dibutylfluoren-2-yl)-2-(7-bromo-9,9-dibutylfluoren-2-yl)-isoindole-1-carboxamide,
Received 29 January 2014
Received in revised form 24 March 2014
Accepted 7 April 2014
and
N-[7-bromo-9,9-bis(2-ethylhexyl)-fluoren-2-yl]-2-[7-bromo-9,9-bis(2-ethylhexyl)-fluoren-2-yl]-
Available online 13 April 2014
isoindole -1-carboxamide was carried out by a three-component reaction of ortho-phthalaldehyde with
the corresponding amine and isocyanide partners. The Ni(0) mediated polymerization reactions of the
obtained monomers gave the corresponding mixture of oligomers from two up to twelve repeat units.
The optical properties were also studied and it was found that the phenylene-containing oligomer
emitted green light in dichloromethane solution, while both difluorene-containing oligomers, under the
same conditions, proved to be blue light-emitters with good quantum efficiency.
Keywords:
Fluorescence
Isoindole
Fluorene
Light-emitting oligomer
Isocyanide
Ó 2014 Published by Elsevier Ltd.
1. Introduction
oxadiazole,15 triphenyl-amine,16 thiophene17 have been prepared.
Interestingly, we could not find any isoindole-containing poly-
The development of organic light-emitting diodes (OLEDs) as
base materials of future displays has attained much attention since
the first report of electroluminescence from poly(p-phenylene
vinylene)-based conjugated polymers by Burroughes et al. in 1990.1
OLED based displays possess several advantages compared to their
inorganic counterparts: they are flexible, transparent, light-weight
and easily processable at lower temperatures. Blue light-emitting
materials are the most important since blue light is easily con-
verted to any other visible color.2,3 The majority of efficient blue
light-emitters contain polyaromatic backbones.4 Fluorenes are
considered important building blocks of polymers, which have the
potential to act as both electroactive and photoactive materials.5e8
The conjugation across the molecule allows for a reduced band gap
the energy of which can be easily varied by the electron donating
character of its substituents.9
The problem with polyfluorenes is that they often show both
excimer and aggregate formation, which besides lowering the ef-
ficiency of the LEDs also causes a red shift in the emission spec-
trum.10 These undesirable phenomena can be overcome in two
ways (i) adding large substituents at the nine position of the fluo-
rene unit,11 (ii) copolymerizing polyfluorene with other fluorescent
units.12 A number of polyfluorenes with different homo- and het-
eroaromatic comonomers, such as anthracene,13 carbazole,14
fluorenes in the literature. This is peculiar considering that a num-
ber of aryl substituted isoindoles were characterized to show strong
fluorescence and electroluminescence in N,N-dimethylformamide
solution more than 40 years ago by Zweig et al.18
Substituted isoindoles, especially N-substituted ones, are of
more interest because they are more stable than the non-
substituted ones.19 Preparation of phenyl substituted poly-
isoindoles is reported from dibenzoylbenzenes with anilines, which
are highly fluorescent polymers with good thermal stability.20
Condensation methods offer a simple way to obtain substituted
isoindole derivatives. We recently reported the preparation of
phenylene-containing polyisoindoles via the catalyst free poly-
condensation between ortho-phthalaldehyde (OPA) and amino-
thiophenols.21
Zhang et al. recently published a three-component reaction
yielding 1-carboxamido-isoindoles via the reaction of OPA, amines,
and isocyanides.22 It is noteworthy that there was no example for
the use of an aromatic isocyanide component among the described
three-component reactions. It is also important to note that the
application of aromatic amine and isocyanide partners in the three-
component reaction allows us to combine the 1-carboxamido-
isoindole group with other fluorescent aromatic (e.g., phenylene,
fluorene) or heteroaromatic (e.g., thiophene, pyridine) groups.
Thus, employing bromo-substituted amine and isocyanide partners
in the three-component reaction we can obtain a series of new
fluorescent polymerizable monomers.
* Corresponding author. Fax: þ36 52 518662; e-mail address: keki.sandor@sci-
ꢀ
ence.unideb.hu (S. Keki).
0040-4020/$ e see front matter Ó 2014 Published by Elsevier Ltd.
http://dx.doi.org/10.1016/j.tet.2014.04.018

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3692
Here, we describe the synthesis of three new fluorene-1-
reacted for overnight at room temperature. After 12 h under these
conditions, we did not observe any noticeable formation of the
desired product 7a. Prolonging the reaction time still failed to
produce any desired product. Addition of acetonitrile in order to
increase the solubility of the isocyanide 5a proved to be also in-
sufficient to obtain 7a. Next we decided to increase the tempera-
ture, and after several attempts at different temperatures we found
that the best conversion could be achieved in 4 h at 100 ꢀC, and due
to the low solubility of the isocyanide 5a in the mixture of DMSO/
H2O (1:1), the addition of 1 part of acetonitrile was also needed.
Thus, we obtained the targeted compound 7a, by employing the
optimized conditions, in 65% isolated yield (Scheme 3).
The above established optimized conditions were used for the
preparation of isoindoles 7b and 7c starting from the amines 3b, 3c
and isocyanides 5b, 5c, respectively, as depicted in Scheme 3. In this
case, the moderate to low isolated yields obtained for compounds
7b and 7c were the consequence of partial decomposition of the
isoindole derivatives 7b and 7c during the work-up and purification
procedures owing to their low stability in solution, in the presence
of air and light (especially in the case of 7c). We tried to overcome
the undesirable decomposition by using neutral aluminum oxide in
the purification step instead of silica gel chromatography, but even
in these conditions the products (7b and 7c) partially decomposed.
It is noteworthy, however that below 0 ꢀC, in the dark and under
inert atmosphere, crystalline 7a and 7b or 7c in the form of solid
carboxamido-isoindole-containing monomers. We also report the
polymerization reactions of the obtained monomers by Yamamoto
coupling.23 Finally, the optical properties of the monomers are
compared with those of the obtained oligomers.
2. Results and discussion
2.1. Synthesis of the monomers 7aec and oligomers 8aec
The preparation of the targeted polymerizable fluorene-1-
carboxamido-isoindole-containing monomers 7aec was planned
by the aforementioned three-component reaction.22 First, the
bromo-substituted amine (3aec) and isocyanide (5aec) compo-
nents were synthesized.
The synthesis of the amines 3a,24 3b,25 and 3c26 was accom-
plished by using the same strategy as shown in Scheme 1. The known
2-bromo-9,9-dialkylfluorenes 1a,27 1b,28 and 1c29 were prepared
started from the commercially available 2-bromo-fluorene as re-
ported in the literature.30 Compounds 1aec were nitrated using
HNO3 in the presence of a supported catalyst of SiO2/H2SO431 to af-
ford the desired 2-bromo-9,9-dialkyl-7-nitrofluorenes 2a, 2b,32 and
2c with good regioselectivity. Reduction of nitrofluorenes (2aec) by
Fe/ammonium chloride33 gave 7-bromo-9,9-dialkylfluorenyl-2-
amines (3aec) in good yields.
Scheme 1. Synthesis of the amines 3aec. Reagents and conditions: (a) SiO2/H2SO4, HNO3, CH2Cl2, rt, 10 min, 67% for 2a, 63% for 2b, 62% for 2c; (b) Fe (powder), NH4Cl, EtOH/H2O
(18:5), 85 ꢀC, 2 h, 78% for 3a, 76% for 3b, 80% for 3c.
In order to obtain the aromatic isocyanide partners for the 1-
carboxamido-isoindole reactions amines 3b and 3c were con-
verted into the isocyanide derivatives 5b and 5c by a two-step
procedure (Scheme 2). N-Formylation of the amines 3b and 3c
was carried out by applying the procedure established by Dawane
et al.34 Thus, compounds 3b and 3c were treated with 6 equiv of
formic acid for 3 h at 70 ꢀC affording the corresponding formamides
4b and 4c in excellent yields, respectively. Dehydration of the
formamides 4b and 4c using phosphoryl chloride and diisopro-
pylamine35 resulted in the desired isocyanides 5b and 5c in high
yields.
spume can be stored for several months. Under these conditions we
have not observed noticeable decomposition during our
investigations.
Thereafter, we explored the possibility to polymerize the ob-
tained monomers (7ae7c) via Ni(0) mediated Yamamoto coupling
reaction.23 First, the monomer 7a dissolved in dry toluene was
reacted with a pretreated mixture of Ni(cod)2, 2,20-bipyridine, 1,5-
cyclooctadiene, and dry DMF at 85 ꢀC for 3 days under argon at-
mosphere, in the dark. Purification of the crude product gave
a mixture of oligomers 8a in 60% yield (Scheme 4). According to
MALDI-TOF MS spectra the obtained mixture contained a series of
Scheme 2. Synthesis of the isocyanides 5b and 5c. Reagents and conditions: (a) HCOOH, 70 ꢀC, 3 h, 91% for 4b, 97% for 4c; (b) POCl3, DIPA, CH2Cl2, 0 ꢀC, 1 h, 93% for 5b, 91% for 5c.
Next, we attempted to synthesize the target 1-carboxamido-
isoindole-containing monomer 7a using the general procedure
described by Zhang et al.22 Accordingly, a mixture of commercially
available OPA (6), 1 equiv of amine 3a, 2 equiv of 4-bromo-phenyl
isocyanide (5a)36 and 2 equiv of NaHSO3 in DMSO/H2O (1:1) was
monobrominated and bromine-free linear and cyclic oligomers
from two up to twelve repeat units (see Figs. 1Se3S in the
Supplementary data). The almost exclusive presence of mono-
brominated and bromine-free oligomers revealed the occurrence
of Ni-mediated hydrolysis of the bromines37 during the

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L. Lazar et al. / Tetrahedron 70 (2014) 3691e3699
3693
Scheme 3. Synthesis of the monomers 7aec. Reagents and conditions: (a) NaHSO3, DMSO/H2O/CH3CN (5:5:6), 100 ꢀC, 4 h, 65% for 7a, 46% for 7b, 10% for 7c.
8c, respectively, could be a result of the high susceptibility of 7b and
7c and their oligomer derivatives against the undesired side re-
action of the Ni-mediated hydrolysis of the bromines. Since bro-
mine hydrolysis occurred even at monomer level, the gradually
diminishing concentration of the monomer present in the reaction
mixture slowed down the product formation increasingly. The
molecular weights of the obtained oligomers (8aec) were charac-
terized by gel permeation chromatography (GPC) and are summa-
rized in Table 1.
Table 1
Characterization of the oligomers 8aec
PDIa
a
a
Oligomer
Mn (g/mol)
Mw (g/mol)
8a
8b
8c
2350
3760
2700
4610
5020
2930
2.0
1.3
1.1
a
The number average molecular weight (Mn), the weight average molecular
weight (Mw), and polydispersity index (PDI) were estimated by GPC in THF against
polystyrene standards.
Scheme 4. Polymerization of the monomers 7aec via Yamamoto coupling. Reagents
and conditions: (a) Ni(cod)2, 2,20-bipyridine, 1,5-cyclooctadiene, dry DMF/dry toluene
(3:5), 85 ꢀC, 72 h for 8a, 1 week for 8b and 8c, 60% for 8a, 30% for 8b, 28% for 8c.
2.2. Optical properties of the monomers 7aec and oligomers
8aec
polymerization reaction, causing the early termination of the
propagation of the polymer chain.
The UVevis and excitation spectra of the monomers 7aec and
oligomers 8aec were recorded in CH2Cl2 and are presented in
Fig. 1a. (The absorbance spectra match the excitation spectra.) All
monomers (7aec) exhibit similar absorption spectra containing
wide absorption bands ranging from 250 to 400 nm and three peaks
located at 285, 315, and 365 nm, with an absorption maximum at
285 nm. The absorption spectra of the oligomers 8aec are also
similar to each other containing a large peak at 355 nm as absorp-
tion maximum and a significant or moderate shoulder at 285 nm,
the intensity of the shoulders decrease in the order of 8a, 8c, and 8b,
respectively. Comparing the absorption spectra of the monomers
(7aec) with those of the oligomers (8aec) we can observe a sub-
stantial bathochromic shift (from 285 to 355 nm) of the absorption
maximum and significant changes in the structure of the absorption
Polymerization reactions of monomers 7b and 7c after 3 days,
under the same reaction conditions, showed approximately 30%
formation of the desired oligomers (8b and 8c). By increasing the
reaction time up to 1 week the conversions could be enhanced to
about 50%. Thus, 8b and 8c were isolated in 30% and 28% yields,
respectively. Our attempts to improve the yields of the desired 8b
and 8c by applying higher temperature, increasing the amount of
the reagents, and prolonging the reaction time were unsuccessful.
Like in the case of 8a, hydrolysis of the bromines in these reactions
could also be observed. In fact, APPI-TOF MS and ESI-HRMS mea-
surements of the crude products of 8b and 8c demonstrated that
partial and complete hydrolysis of the bromines occurred at both
monomer and oligomer levels (see ESI-HRMS data of mono-
brominated and bromine-free derivatives of 7b and 7c in the sub-
sections 4.19 and 4.20, respectively, and the APPI-TOF MS spectra of
8b and 8c in the Supplementary data, Fig. 4S and 5S, respectively,
show the presence of monobrominated and bromine-free
oligomers). Presumably, both the low conversion and the slow
transformation of the monomers 7b and 7c into oligomers 8b and
bands due to the extended
p-conjugation system along the whole
oligomer molecules (8aec) via the amide bridges38 (Fig. 1a).
The characteristics of the fluorescence emission spectra of the
monomers 7aec and oligomers 8aec are compiled in Table 2 (in-
cluding the excitation wavelengths at which the emission spectra
were recorded) and the emission spectra obtained in CH2Cl2 are

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L. Lazar et al. / Tetrahedron 70 (2014) 3691e3699
3694
Fig. 1. Normalized excitation (a) and emission (b) spectra of monomers 7aec and oligomers 8aec obtained in CH2Cl2.
Table 2
that relatively high quantum yields were obtained for both
difluorene-containing oligomers (FF¼0.17 for 8b and FF¼0.15 for
8c) in comparison with the fluorescence quantum yield values
obtained for the starting monomers (FF¼0.01 for 7b and FF¼0.01
for 7c), respectively. (Quantum yields were calculated by using
quinine sulfate reference with absolute quantum efficiency
The wavelengths of excitation (lex), fluorescence emission maxima (lem,max), Stokes
shifts and the quantum yield (FF) of monomers 7aec and oligomers 8aec in CH2Cl2.
The Stokes shift is defined as
wavenumbers of absorption (excitation) and emission maxima, respectively. The
error in the measurements of FF values were within ꢂ10%
D
n
¼
nabs.max nem.max, where nabs.max and nem.max are the
ꢁ
Compound Solvent lex
(nm) (nm)
lem,max ε (dm3/mol cm)a Stokes shift FF
(
D
n
, cmꢁ1
)
(FF¼55%). However, in the case of oligomer 8a low quantum yield
was obtained (FF¼0.03), which is three times higher than that of
the obtained for the monomer 7a (FF¼0.01). The fluorescence
properties of the monomers 7aec and oligomers 8aec demon-
strated in Fig. 2 are in good agreement with the data of Fig. 1b and
Table 2.
7a
8a
7b
8b
7c
8c
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
363
352
365
356
366
350
439
489
481
418
480
411
1.7ꢃ104
1.4ꢃ105
2.7ꢃ104
1.4ꢃ105
2.7ꢃ104
3.8ꢃ104
4769
7959
6607
4167
6489
4240
0.01
0.03
0.01
0.17
0.01
0.15
a
Molar extinction coefficient values (ε) were determined at the corresponding lex
values.
shown in Fig. 1b. As seen from the data of Fig. 1b and Table 2
emission spectra of the monomers, 7aec show low fluorescence
emission with wavelengths ranging from
l
¼390 nm up to
l¼570 nm. Monomers 7b and 7c show almost identical emission
spectra with emission maxima at 481 and 480 nm, respectively,
near to the green region. However, the monomer 7a with an
emission maximum at 439 nm presents emission predominantly in
the blue region of the visible light.
The fluorescence emission spectra of the oligomers 8a exhibit
a red shift of the emission maximum (from 439 to 489 nm) in
comparison with that of the monomer 7a. The shape of the emis-
sion spectra is also changed containing a large peak at 489 nm as
emission maximum and a moderate shoulder at 423 nm. Surpris-
ingly, the similar fluorescence emission spectra of the oligomers 8b
and 8c show a hypsochromic shift (blue shift) of the emission
maxima (from 481 to 418 nm and from 480 to 413 nm, respectively)
in comparison with those of the monomers 7b and 7c. The blue
shift of the emission maxima in the case of the oligomers 8b and 8c
can be explained by the different type of conjugation present in
monomers and oligomers. The fluorene units are separated by the
1-carboxamide-isoindolene moiety in the case of the monomers 7b
and 7c, while oligomers 8b and 8c contain alternating difluorene
and isoindolene units. Thus, the characteristic emission bands of
simple polyfluorenes (oligofluorenes from trimer up to heptamer
with lem,max in the range of 394e434 nm assigned to the 0-0 and 0-
1 intrachain singlet transitions)26 are more pronounced in the case
Fig. 2. Demonstration of the fluorescence properties of monomers 7aec and oligomers
8aec in CH2Cl2 illuminated by light of
are: 7a (pale blue), 8a (light green), 7b (pale green), 8b (sky blue), 7c (pale green), 8c
l
¼365 nm. Compounds from left to the right
(sky blue).
3. Conclusion
Three new fluoreneeisoindole-containing light-emitting mono-
and oligomers were prepared. The synthesis of the monomers 7aec
was accomplished by the three-component reaction of ortho-
phthalaldehyde with the amines 3aec and isocyanides 5aec, re-
spectively. The polymerization of the obtained monomers proceeds
via Ni(0) mediated Yamamoto coupling reaction. GPC, MALDI-TOF
MS, and APPI-TOF MS investigation showed the formation of a se-
ries of oligomers (8aec) from two up to twelve repeat units. The
degree of polymerization was limited by the undesirable side re-
action of partial or complete hydrolysis of the bromines. Optical
study of the oligomers showed green light emission when in so-
lution in dichloromethane for the phenylene-containing oligomer
(8a), while blue light emission could be observed for both
difluorene-containing oligomers (8b and 8c), under the same
conditions, with relatively good quantum efficiency. Unlike the
monomers, the oligomers proved to be stable even in solution for
several days. The reported procedure for 7aec and 8aec can serve
as a model for the synthesis of a series of novel fluorescent
of oligomers 8b and 8c, probably due to the direct
system between the aromatic fluorene rings.
p-conjugation
It is worth mentioning that the shape and the wavelength at the
maximum emission intensity are independent of the excitation
wavelength, i.e., similar emission spectra were obtained using
shorter excitation wavelengths (in the range of 280e315 nm), in-
dicating that electronic transition occurs from each excited state to
the same lowest ground state.
The optical properties of the monomers 7aec and oligomers
8aec are summarized in Table 2. It can be surmised from Table 2

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L. Lazar et al. / Tetrahedron 70 (2014) 3691e3699
3695
isoindole-containing light-emitting oligomers/polymers by com-
bining the 1-carboxamido-isoindole moiety with bromo-
substituted fluorescent aromatic or heteroaromatic groups.
in a quartz cuvette of 1 cm optical length. A 3.00 cm3 solution was
prepared from the sample. Fluorescence measurements were car-
ried out using a Jasco FP-8200 fluorescence spectrophotometer
equipped with a Xe lamp light source. The excitation and emission
spectra were recorded at room temperature, using 2.5 nm excita-
tion, 5.0 nm emission bandwidth, and 100 nm/min scanning speed.
Fluorescence quantum yields were calculated by using quinine-
sulfate in 0.1 mol/L sulfuric acid as the reference absolute quan-
tum efficiency (Fn¼55%). For UVevis and fluorescence measure-
ments of monomers 7aec and oligomers 8aec were dissolved in
CH2Cl2 at concentration of 0.2 mg/mL and was diluted to 4.00 mg/L
and 0.800 mg/L. Gel Permeation Chromatograms were recorded in
THF at a 144 flow rate of 0.5 cm3/min at 35 ꢀC with a Waters
chromatograph equipped with four gel columns (4.6ꢃ300 mm,
4. Experimental
4.1. General information
Compound 5a was prepared in our laboratory according to the
literature procedure.36 TLC was performed on Kieselgel 60 F254
(Merck) or aluminum oxide F254 neutral (type T, Merck) with de-
tection by UV lamps (emission at 254 nm or 365 nm). Column
chromatography was performed on Silica gel 60 (Merck
0.063e0.200 mm) or aluminum oxide acc. to Brockmann (II, neu-
tral; Reanal, Hungary). The 1H (360 MHz) and 13C NMR (90.54 MHz)
spectra were recorded with a Bruker DRX-360 spectrometer.
Chemical shifts are referenced to Me4Si (0.00 ppm for 1H) or to the
residual solvent signals (CDCl3: 77.00 ppm). IR spectra were
recorded on a PerkineElmer 16 PC FTIR spectrometer. The MALDI
MS measurements were performed with a Bruker BIFLEX IIIÔ mass
spectrometer equipped with a time-of-flight (TOF) mass analyzer.
In all cases 19 kV acceleration voltage was used with pulsed ion
extraction (PIEÔ). The positive ions were detected in the reflectron
mode (20 kV). A nitrogen laser (337 nm, 3 ns pulse width,
106e107 W/cm2) operating at 4 Hz was used to produce laser de-
sorption and 500 shots were summed. Samples were prepared with
a dithranol matrix (20 mg/cm3), analyte solution of 10 mg/cm3 and
sodium trifluoroacetate was added (5 mg/cm3) as the cationization
agent in tetrahydrofuran. ESI-HRMS analyses of the compounds
were carried out in Electrospray Quadrupole Time-of-Flight MS/MS
(ESI-QqTOF). MS measurements were performed with a MicroTOF-
Q type QqTOF MS instrument equipped with an ESI source from
Bruker (Bruker Daltoniks, Bremen, Germany). The sample solutions
were introduced directly into the ESI source with a syringe pump
4.6 mm Styragel columns: HR 0.5, 1, 2 and 4), a Waters Alliance
e2695 HPLC pump, and with Waters 2414 refractive index detector.
4.2. General method A for the synthesis of 2-bromo-9,9-
dialkyl-7-nitrofluorene derivatives (2aec)
2-Bromo-9,9-dialkylfluorene (10.0 mmol, 1a, 1b or 1c) was
dissolved in CH2Cl2 (60 mL), in the presence of a supported catalyst
of SiO2/H2SO4 (4.60 g) prepared according to the literature pro-
cedure.31 HNO3 (417
mL, 10.0 mmol) was added, and the heteroge-
neous mixture was stirred at room temperature for 10 min. The
solution was then filtered, and the filtrate was washed with aque-
ous saturated NaHCO3 solution (10 mL) and water (10 mL). The
organic layer was dried over anhydrous MgSO4 and the solvent was
evaporated under reduced pressure.
4.3. General method B for the preparation of 7-bromo-9,9-
dialkylfluorenyl-2-amine derivatives (3aec)
A mixture of nitrofluorene (10.0 mmol, 2a, 2b or 2c), iron
powder (1.68 g, 30.0 mmol), and NH4Cl (1.07 g, 20.0 mmol) was
refluxed in aqueous ethanol (144 mL of alcohol and 40 mL of water)
at 85 ꢀC for 2 h under inert atmosphere. The reaction mixture was
treated with 50 mL of aqueous saturated NaHCO3 solution and fil-
tered off through a pad of Celite. The obtained solution was con-
centrated in vacuum in order to remove ethanol. The formed
residue was extracted with CH2Cl2 (2ꢃ50 mL), and the organic
phase was dried over anhydrous MgSO4 and evaporated under re-
duced pressure.
(ColeeParmer Ins. Co.) at a flow rate of 3 mL/min. The temperature
of the drying gas (N2) was maintained at 180 ꢀC. The voltages ap-
plied on the ESI source were 4 kV. Each spectrum was calibrated
externally with the salt clusters produced from the electrosprayed
solution of sodium trifluoroacetate. In the case of compounds 5b
and 5c: Ion source for Atmospheric Pressure Chemical Ionization
(APCI) source was from Bruker (Bruker Daltoniks, Bremen, Ger-
many). The solutions were delivered directly into the APCI source
with a syringe pump (ColeeParmer Ins. Co., Vernon Hills, IL, USA) at
a flow rate of 15 mL/min together with a carrier flow of methanol at
a flow rate of 0.2 mL/min by means of a T-piece. The temperature of
the drying gas (N2) was maintained at 390 ꢀC. The APCI mass
spectra were calibrated by APCI/APPI calibrant solution from Agi-
lent, USA. Atmospheric pressure photoionization (APPI) measure-
ments were performed in negative ion modes with a MicroTOF-Q
type Qq-TOF MS instrument (Bruker Daltonik, Bremen, Germany)
equipped with an atmospheric pressure photoionization source
(PhotoMate, Kr discharge lamp, VUV photons of 10.0, and 10.6 eV in
intensity ratio of 4:1, respectively) from Syagen Ltd. (Syagen Tech-
nology, Inc., Tustin, CA). The samples were dissolved in toluene
(dopant) at a concentration of 1 mg/mL. The solutions were de-
4.4. General method C for the preparation of formamide de-
rivatives (4b, 4c)
Formic acid (2.26 mL, 60.0 mmol) was added to the amine
(10.0 mmol, 3b or 3c) and the resulting mixture was stirred for 3 h
at 70 ꢀC. Then, the reaction mixture was cooled and diluted with
EtOAc (50 mL). The obtained solution was washed carefully with
aqueous saturated NaHCO3 solution (10 mL), and water (10 mL).
The organic layer was dried over anhydrous MgSO4 and evaporated
under diminished pressure.
livered directly into the APPI source with
(ColeeParmer Ins. Co., Vernon Hills, IL, USA) at a flow rate of 25
min together with a carrier flow of CCl4 at a flow rate of 200 L/min
a
syringe pump
mL/
4.5. General method D for the preparation of isocyanide de-
rivatives (5b, 5c)
m
by means of a T-piece. The heater of the APPI source was kept at
450 ꢀC. The end-plate offset and capillary voltage were set to 500 V
and 2500 V, respectively. The accuracy of mass determination was
within 5 ppm. The mass spectra recorded were evaluated by the
Data Analysis 3.4 software from Bruker. The measured mono-
isotopic mass and isotopic distributions are in good agreement with
those calculated based on the composition proposed. The UVevis
spectra were recorded on a HP 8453 diode array spectrophotometer
To a solution of the formamide (10.0 mmol, 4b or 4c) in CH2Cl2
(10 mL) and diisopropylamine (3.78 mL, 27.0 mmol), phosphoryl
chloride (1.03 mL, 11.0 mmol) was added dropwise with stirring at
0
ꢀC. Stirring was continued for 1 h at 0 ꢀC. A solution of Na2CO3
(2 g) in water (20 mL) was added at a sufficiently slow rate in order
to maintain 25e30 ꢀC. After stirring for 1 h at rt, more water (10 mL)
and CH2Cl2 (5 mL) were added and the organic layer was washed

ꢀ ꢀ
L. Lazar et al. / Tetrahedron 70 (2014) 3691e3699
3696
with water (3ꢃ5 mL). The organic phase was dried over anhydrous
(d, 1H, J¼8.7 Hz, arom), 7.55e7.52 (m, 2H, arom), 2.10e1.95 (m, 4H,
2ꢃ CH2Cq), 1.15e1.04 (m, 4H, 2ꢃ CH2), 0.70e0.49 (m, 10H, 2ꢃ CH2,
MgSO4 and evaporated under reduced pressure.
2ꢃ CH3); 13C NMR (90 MHz, CDCl3):
d (ppm) 154.3, 151.5, 147.4,
4.6. General method E for the preparation of 1-carboxamido-
isoindole derivatives (7aec)
146.4,137.7, 130.7, 126.5,123.6,123.4,122.4,119.9,118.2 (12C, arom),
55.9 (Cq), 39.7 (2ꢃ CH2Cq), 25.8 (2ꢃ CH2), 22.8 (2ꢃ CH2), 13.7 (2ꢃ
CH3).
A mixture of 268 mg ortho-phthalaldehyde (2.00 mmol), 431 mg
NaHSO3 (4.14 mmol), and DMSO/H2O (5 mL/5 mL) was stirred at
room temperature in a reaction flask protected from light under
argon atmosphere. After 0.5 h amine (2.00 mmol, dissolved in 3 mL
of CH3CN, 3a, 3b or 3c) and isocyanide (4.00 mmol, dissolved in
3 mL of CH3CN, 5a, 5b or 5c) were added. The reaction mixture was
then heated to 100 ꢀC, and stirred for 4 h at this temperature. The
reaction mixture was diluted with 150 mL of EtOAc and extracted
with saturated NH4Cl (3ꢃ50 mL). The organic layer was dried over
anhydrous MgSO4 and evaporated under diminished pressure.
4.10. 2-Bromo-9,9-bis(2-ethylhexyl)-7-nitrofluorene (2c)
2-Bromo-9,9-bis-(ethylhexyl)-fluorene29 (1c, 26.1 g, 55.6 mmol),
SiO2/H2SO4 (13.0 g), and HNO3 (2.32 mL, 55.6 mmol) were reacted in
CH2Cl2 (250 mL) according to general method A. The crude product
was purified by silica gel chromatography in 9:1 n-hexane/CH2Cl2
and recrystallized from EtOH to give 2c (17.8 g, 62%) as yellow
crystals. Mp 69e71 ꢀC; Rf 0.36 (isomeric mixture, 9:1 n-hexane/
CH2Cl2); IR nmax (KBr): 3444, 2959, 2925, 2870, 2857, 1598, 1517,
1456, 1335, 1081, 1062, 901, 822, 739, 431 cmꢁ1; 1H NMR (360 MHz,
4.7. General method F for the Yamamoto coupling (8aec)
CDCl3, Me4Si): d (ppm) 8.28e8.26 (m, 2H, arom), 7.78 (d, 1H,
J¼8.6 Hz, arom), 7.66 (d, 1H, J¼8.1 Hz, arom), 7.62e7.58 (m, 1H,
arom), 7.54 (dd, 1H, J¼1.4 Hz, J¼8.1 Hz, arom), 2.10e1.98 (m, 4H, 2ꢃ
CH2Cq), 0.90e0.41 (m, 30H, 8ꢃ CH2, 2ꢃ CH, 4ꢃ CH3); 13C NMR
A solution of Ni(cod)2 (300 mg, 1.09 mmol), 2,20-bipyridine
(75 mg, 1.09 mmol), and 1,5-cyclooctadiene (134 mL, 1.09 mmol) in
dry DMF (6 mL) was heated at 75 ꢀC for 30 min in a flask protected
from light under argon atmosphere. A solution of the monomer
(1.00 mmol, 7a, 7b or 7c) in dry toluene (10 mL) was added under
argon to the DMF solution, and the polymerization was maintained
at 85 ꢀC for 72 h for 7a or 1 week for 7b and 7c in the dark. The
reaction mixture was then poured into a methanol/HCl(cc) (2:1)
mixture (150 mL). In the case of monomers 7a and 7b the pre-
cipitated crude products were collected by filtration and washed
with a MeOH/H2O 2:1 mixture (2ꢃ) and then with H2O (5ꢃ). The
obtained crude products were dried at 40 ꢀC under diminished
pressure. In the case of monomer 7c the crude product was col-
lected by extraction using CH2Cl2 (3ꢃ50 mL). The organic layer was
washed successively with water (50 mL), aqueous saturated
NaHCO3 solution (50 mL), and water (50 mL). The organic phase
was dried over anhydrous MgSO4 and evaporated under reduced
pressure.
(90 MHz, CDCl3): d (ppm) 154.2, 151.6, 151.5, 151.4, 146.8, 146.5, 137.7,
130.6, 127.8, 127.7, 127.7, 123.3, 123.3, 123.1, 122.3, 119.9, 119.4, 119.3,
119.3 (12C, arom), 55.7 (Cq), 44.2 (2ꢃ CH2Cq), 34.8 (2ꢃ CH), 33.7,
33.5 (2ꢃ CH2), 28.0 (2ꢃ CH2), 27.1, 26.9 (2ꢃ CH2), 22.6, 22.6 (2ꢃ CH2),
14.0, 13.8 (2ꢃ CH3), 10.3, 10.2 (2ꢃ CH3). ESI-HRMS: m/z calcd for
C
29H40BrNO2Naþ [MþNa]þ 536.213. Found: 536.213.
4.11. 2-Amino-7-bromo-9,9-diethylfluorene (3a)24
Compound 2a (1.40 g, 4.04 mmol), iron powder (676 mg,
12.1 mmol), and NH4Cl (432 mg, 8.08 mmol) were reacted in
aqueous ethanol (55 mL of alcohol and 15 mL of water) according to
general method B. The crude product was purified by silica gel
chromatography in 1:1 n-hexane/CH2Cl2, to give 3a (1.00 g, 78%) as
a yellow syrup; Rf 0.22 (1:1 n-hexane/CH2Cl2); 1H NMR (360 MHz,
CDCl3, Me4Si):
d (ppm) 7.41e7.37 (m, 4H, arom), 6.61e6.57 (m, 2H,
arom), 3.73 (br s, 2H, NH2), 1.96e1.81 (m, 4H, 2ꢃ CH2), 0.31 (t, 6H,
4.8. 2-Bromo-9,9-diethyl-7-nitrofluorene (2a)
J¼7.4 Hz, 2ꢃ CH3); 13C NMR (90 MHz, CDCl3):
d (ppm) 151.3, 151.1,
146.3, 140.9, 131.3, 129.6, 125.7, 120.4, 119.5, 118.8, 113.9, 109.4 (12C,
arom), 56.0 (Cq), 32.7 (2ꢃ CH2), 8.3 (2ꢃ CH3).
2-Bromo-9,9-diethylfluorene27 (1a, 2.26 g, 7.50 mmol), SiO2/
H2SO4 (3.45 g), and HNO3 (312
mL, 7.50 mmol) were reacted in
CH2Cl2 (45 mL) according to general method A. The crude product
was purified by silica gel chromatography in 7:3 n-hexane/CH2Cl2,
to give 2a (1.73 g, 67%) as yellow crystals; mp 142e144 ꢀC; Rf 0.45
(7:3 n-hexane/CH2Cl2); IR nmax (KBr): 3435, 2962, 2918, 2875, 2849,
4.12. 2-Amino-7-bromo-9,9-dibutylfluorene (3b)25
Compound 2b (4.00 g, 9.94 mmol), iron powder (1.66 g,
29.8 mmol), and NH4Cl (1.06 g, 19.9 mmol) were reacted in aqueous
ethanol (145 mL of alcohol and 40 mL of water) according to general
method B. The crude product was purified by silica gel chroma-
tography in 1:1 n-hexane/CH2Cl2, to give 3b (2.81 g, 76%) as white
crystals; mp 131 ꢀC, (mp 131 ꢀC; lit.25); Rf 0.20 (7:3 n-hexane/
1599, 1523, 1455, 1348, 1254, 1136, 1062, 823, 768, 739, 419 cmꢁ1
;
1H NMR (360 MHz, CDCl3, Me4Si):
d
(ppm) 8.28 (dd, 1H, J¼2.0 Hz,
J¼8.4 Hz, arom), 8.21 (d, 1H, J¼2.0 Hz, arom), 7.80 (d, 1H, J¼8.4 Hz,
arom), 7.68 (d, 1H, J¼8.8 Hz, arom), 7.56e7.53 (m, 2H, arom),
2.18e2.01 (m, 4H, 2ꢃ CH2), 0.32 (t, 6H, J¼7.4 Hz, 2ꢃ CH3); 13C NMR
CH2Cl2); 1H NMR (360 MHz, CDCl3, Me4Si):
d (ppm) 7.43 (dd, 1H,
(90 MHz, CDCl3):
d
(ppm) 153.4, 150.7, 147.3, 146.7, 138.0, 130.6,
J¼1.2 Hz, J¼7.3 Hz, arom), 7.38e7.36 (m, 3H, arom), 6.66e6.63 (m,
126.5, 123.6, 123.4, 122.4, 119.8, 118.2 (12C, arom), 56.9 (Cq), 32.3
(2ꢃ CH2), 8.3 (2ꢃ CH3). ESI-HRMS: m/z calcd for C17H16BrNO2Naþ
[MþNa]þ 368.026. Found: 368.023.
2H, arom), 3.76 (br s, 2H, NH2), 1.93e1.80 (m, 4H, 2ꢃ CH2Cq),
1.13e1.03 (m, 4H, 2ꢃ CH2), 0.70e0.53 (m, 10H, 2ꢃ CH2, 2ꢃ CH3); 13
C
NMR (90 MHz, CDCl3):
d (ppm) 152.3, 152.0, 146.3, 140.6, 131.3,
129.6, 125.8, 120.6, 119.6, 119.0, 114.0, 109.6 (12C, arom), 55.0 (Cq),
40.4 (2ꢃ CH2Cq), 25.8 (2ꢃ CH2), 23.0 (2ꢃ CH2), 13.8 (2ꢃ CH3).
4.9. 2-Bromo-9,9-dibuthyl-7-nitrofluorene (2b)32
2-Bromo-9,9-dibutylfluorene28 (1b, 8.00 g, 22.4 mmol), SiO2/
4.13. 2-Amine-7-bromo-9,9-bis(2-ethylhexyl)fluorene (3c)26
H2SO4 (10.3 g), and HNO3 (933 mL, 22.4 mmol) were reacted in
CH2Cl2 (135 mL) according to general method A. The crude product
was purified by silica gel chromatography in 7:3 n-hexane/CH2Cl2
and recrystallized from EtOH to give 2b (5.70 g, 63%) as yellow
crystals. Mp 127 ꢀC; Rf 0.50 (7:3 n-hexane/CH2Cl2); 1H NMR
Compound 2c (20.0 g, 38.9 mmol), iron powder (6.53 g,
117 mmol), and NH4Cl (4.16 g, 77.8 mmol) were reacted in aqueous
ethanol (540 mL of alcohol and 150 mL of water) according to
general method B. The crude product was purified by silica gel
chromatography in 65:35 n-hexane/CH2Cl2, to give 3c (15.1 g, 80%)
as a yellow syrup; Rf 0.24, 0.29 and 0.35 (isomeric mixture, 7:3 n-
(360 MHz, CDCl3, Me4Si):
d
(ppm) 8.27 (dd, 1H, J¼2.0 Hz, J¼8.3 Hz,
arom), 8.20 (d,1H, J¼1.8 Hz, arom), 7.78 (d,1H, J¼8.4 Hz, arom), 7.66

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L. Lazar et al. / Tetrahedron 70 (2014) 3691e3699
3697
hexane/CH2Cl2); 1H NMR (360 MHz, CDCl3, Me4Si):
d
(ppm)
J¼1.3 Hz, arom), 1.94 (t, 4H, J¼8.4 Hz, 2ꢃ CH2Cq), 1.14e1.04 (m, 4H,
2ꢃ CH2), 0.69 (t, 6H, J¼7.3 Hz, 2ꢃ CH3), 0.61e0.48 (m, 4H, 2ꢃ CH2);
7.42e7.35 (m, 4H, arom), 6.64e6.59 (m, 2H, arom), 3.66 (br s, 2H,
NH2), 1.95e1.81 (m, 4H, 2ꢃ CH2Cq), 0.94e0.70 (m, 22H), 0.60e0.52
13C NMR (90 MHz, CDCl3):
d (ppm) 164.1 (CN), 153.2, 151.7, 141.2,
(m, 8H); 13C NMR (90 MHz, CDCl3):
d
(ppm) 152.0, 151.9, 151.8,
138.3, 130.4, 126.3, 125.6, 122.4, 121.6, 121.0, 120.4 (12C, arom), 55.7
(Cq), 39.9 (2ꢃ CH2Cq), 25.8 (2ꢃ CH2), 22.9 (2ꢃ CH2), 13.7 (2ꢃ CH3).
ESI-HRMS: m/z calcd for C22H25BrNþ [MþH]þ 382.116. Found:
382.115.
145.9, 145.9, 145.8, 140.7, 131.4, 131.3, 131.3, 129.5, 127.0, 126.9,
126.8, 120.5, 119.5, 118.4, 118.4, 118.3, 114.0, 110.6 (12C, arom), 54.7
(Cq), 44.6, 44.6 (2ꢃ CH2Cq), 34.5 (2ꢃ CH), 33.5, 33.4 (2ꢃ CH2), 28.1,
27.9 (2ꢃ CH2), 27.0, 26.8 (2ꢃ CH2), 22.7 (2ꢃ CH2), 14.0 (2ꢃ CH3),
10.3, 10.1 (2ꢃ CH3).
4.17. 7-Bromo-9,9-bis(2-ethylhexyl)fluorenyl-2-isocyanide
(5c)
4.14. 7-Bromo-9,9-dibutylfluorenyl-2-formamide (4b)
Compound 4c (3.00 g, 5.85 mmol), diisopropylamine (2.21 mL,
Compound 3b (1.55 g, 4.16 mmol) and formic acid (943
mL,
15.8 mmol), and phosphoryl chloride (600 mL, 6.44 mmol) were
25.0 mmol) were reacted according to general method C. The crude
product was purified by silica gel chromatography in 97:3 CH2Cl2/
acetone, to give 4b (1.51 g, 91%) as white crystals; mp 150e152 ꢀC;
Rf 0.48 (95:5 CH2Cl2-acetone); IR nmax (KBr): 3444, 2955, 2928,
2858, 2370, 2351, 2320, 1680, 1615, 1543, 1456, 1303, 1219, 1131,
1062, 813, 772 cmꢁ1; 1H NMR (360 MHz, CDCl3, Me4Si, tautomeric
reacted in CH2Cl2 (6.5 mL) according to general method D. The
crude product was purified by silica gel chromatography in 96:4 n-
hexane/EtOAc, to give 5c (2.63 g, 91%) as greenish crystals; mp
57e61 ꢀC; Rf 0.55 (isomeric mixture, 96:4 n-hexane/EtOAc); IR nmax
(KBr): 3430, 2958, 2925, 2871, 2857, 2365, 2310, 2121, 1680, 1614,
1523, 1457, 1340, 1306, 1064, 814, 418 cmꢁ1
;
1H NMR (360 MHz,
mixture):
d
(ppm) 8.77 (d, 0.44H, J¼11.4 Hz), 8.50 (d, 0.44H,
CDCl3, Me4Si):
d
(ppm) 7.65 (d, 1H, J¼8.4 Hz, arom), 7.56e7.52 (m,
J¼11.3 Hz), 8.42 (d, 0.44H, J¼1.8 Hz), 7.64e7.42 (m, 5.24H), 7.08 (dd,
0.44H, J¼2.0 Hz, J¼8.1 Hz), 7.04 (d, 0.44H, J¼1.8 Hz), 1.96e1.91 (m,
4H, 2ꢃ CH2Cq), 1.79 (s, 0.56H, OH), 1.14e1.02 (m, 4H, 2ꢃ CH2),
0.70e0.48 (m, 10H, 2ꢃ CH2, 2ꢃ CH3); 13C NMR (90 MHz, CDCl3):
2H, arom), 7.48 (dd,1H, J¼1.6 Hz, J¼8.1 Hz, arom), 7.38e7.35 (m, 2H,
arom), 2.02e1.90 (m, 4H, 2ꢃ CH2Cq), 0.90e0.70 (m, 22H),
0.55e0.51 (m, 6H), 0.48e0.40 (m, 2H); 13C NMR (90 MHz, CDCl3):
d
(ppm) 164.0 (CN), 153.1, 153.0, 151.7, 151.6, 151.5, 141.3, 138.4,
d
(ppm) 162.6, 158.8 (O]CeN, OeC]N), 152.8, 152.6, 152.4, 151.6,
130.3, 127.6, 127.5, 127.4, 125.6, 125.5, 124.8, 122.1, 122.0, 122.0,
121.8, 121.5, 120.3 (12C, arom), 55.4 (Cq), 44.3 (2ꢃ CH2Cq), 34.7 (2ꢃ
CH), 33.6, 33.4 (2ꢃ CH2), 28.0, 27.9 (2ꢃ CH2), 27.1, 26.9 (2ꢃ CH2),
22.6 (2ꢃ CH2),14.0,13.9 (2ꢃ CH3),10.3,10.2 (2ꢃ CH3). ESI-HRMS: m/
z calcd for C30H41BrNþ [MþH]þ 494.242. Found: 494.237.
139.5, 139.2, 137.5, 136.7, 136.5, 136.1, 130.1, 129.9, 126.1, 121.0, 120.9,
120.8, 120.7, 120.2, 118.7, 117.9, 114.5, 113.4 (12C, arom), 55.5 (Cq),
40.0 (2ꢃ CH2Cq), 25.8 (2ꢃ CH2), 22.9 (2ꢃ CH2), 13.8 (2ꢃ CH3). ESI-
HRMS: m/z calcd for C22H26BrNONaþ [MþNa]þ 422.109. Found:
422.107.
4.18. N-(4-Bromo-phenyl)-2-(7-bromo-9,9-diethylfluoren-2-
4.15. 7-Bromo-9,9-bis(2-ethylhexyl)fluorenyl-2-formamide
yl)-isoindole-1-carboxamide (7a)
(4c)
Amine 3a (718 mg, 2.27 mmol), isocyanide (5a, 826 mg,
4.54 mmol), OPA (305 mg, 2.27 mmol), and NaHSO3 (489 mg,
4.70 mmol) were reacted in a mixture of DMSO/H2O/CH3CN (5 mL/
5 mL/6 mL) according to general method E. The crude product was
purified by silica gel chromatography in 1:1 n-hexane/CH2Cl2, to
give 7a (900 mg, 65%) as beige crystals; mp 230e232 ꢀC; Rf 0.56
(3:7 n-hexane/CH2Cl2); IR nmax (KBr): 3436, 3410, 3328, 3116, 3055,
2958, 2927, 2873, 2852, 1670, 1585, 1508, 1488, 1459, 1416, 1404,
1352, 1305, 1239, 1210, 1132, 1100, 1071, 1006, 876, 821, 767, 737,
Compound 3c (3.00 g, 6.19 mmol) and formic acid (1.40 mL,
37.1 mmol) were reacted according to general method C. The crude
product was purified by silica gel chromatography in 85:15 n-
hexane/EtOAc, to give 4c (3.09 g, 97%) as a colorless syrup; Rf 0.26,
0.32 and 0.37 (isomeric mixture, 8:2 n-hexane/EtOAc); IR nmax
(KBr): 3423, 2957, 2925, 2871, 2856, 1692, 1615, 1598, 1546, 1457,
1403, 1305, 1063, 812, 502 cmꢁ1; 1H NMR (360 MHz, CDCl3, Me4Si):
d
(ppm) 9.03 (d, 0.51H, J¼11.3 Hz), 8.78e8.74 (m, 0.52H), 8.43 (d,
0.38H, J¼1.6 Hz), 7.84e7.72 (m, 0.81H), 7.64e7.58 (m, 0.96H),
7.51e7.41 (m, 3.30H), 7.14e7.08 (m, 1.09H), 2.03e1.91 (m, 4H),
0.91e0.69 (m, 22H), 0.57e0.45 (m, 8H); 13C NMR (90 MHz, CDCl3):
553, 502, 441 cmꢁ1; 1H NMR (360 MHz, CDCl3, Me4Si):
d (ppm) 8.10
(dd,1H, J¼0.8 Hz, J¼8.7 Hz, NH), 7.82 (d,1H, J¼8.0 Hz, arom), 7.67 (d,
1H, J¼8.5 Hz, arom), 7.62 (d, 1H, J¼8.0 Hz, arom), 7.53e7.48 (m, 4H,
arom), 7.41 (d, 1H, J¼2.0 Hz, arom), 7.33e7.23 (m, 6H, arom),
7.17e7.13 (m, 1H, arom), 2.02e1.96 (q, 4H, 2ꢃ CH2), 0.32 (t, 6H,
d
(ppm) 162.8, 158.9, 158.8, 158.8 (O]CeN, OeC]N), 152.6, 152.4,
152.2, 152.2, 152.1, 151.5, 151.4, 151.3, 139.6, 139.3, 137.7, 136.8, 136.2,
136.1, 135.6, 130.0, 129.8, 127.3, 120.8, 120.7, 120.6, 120.4, 120.1,
120.1, 120.0, 118.6, 118.5, 118.4, 118.1, 118.1, 118.0, 115.7, 114.5 (12C,
arom), 55.3 (Cq), 44.4, 44.3 (2ꢃ CH2Cq), 34.6 (2ꢃ CH), 33.5 (2ꢃ
CH2), 28.0, 27.9 (2ꢃ CH2), 27.0, 26.9 (2ꢃ CH2), 22.6 (2ꢃ CH2), 14.0,
13.9 (2ꢃ CH3), 10.3, 10.2 (2ꢃ CH3). ESI-HRMS: m/z calcd for
J¼7.4 Hz, 2ꢃ CH3); 13C NMR (90 MHz, CDCl3):
d (ppm) 158.8 (CO),
152.5,151.2,141.4,139.0,139.0,137.2,131.8,130.5,128.2,126.4,125.7,
125.0,124.4,122.8,122.2,121.6,121.3,120.8,120.5,120.4,119.6,116.2
(26C, arom), 56.8 (Cq), 32.5 (2ꢃ CH2), 8.4 (2ꢃ CH3). ESI-HRMS: m/z
calcd for C32H26Br2N2ONaþ [MþNa]þ 635.030. Found: 635.031.
C
30H42BrNONaþ [MþNa]þ 534.234. Found: 534.233.
4.19. N-(7-Bromo-9,9-dibutylfluoren-2-yl)-2-(7-bromo-9,9-
dibutylfluoren-2-yl)-isoindole-1-carboxamide (7b)
4.16. 7-Bromo-9,9-dibutylfluorenyl-2-isocyanide (5b)
Compound 4b (1.45 g, 3.62 mmol), diisopropylamine (1.37 mL,
9.77 mmol), and phosphoryl chloride (371 mL, 3.98 mmol) were
Amine 3b (718 mg, 1.93 mmol), isocyanide (5b, 1.48 g,
3.86 mmol), OPA (259 mg, 1.93 mmol), and NaHSO3 (416 mg,
4.00 mmol) were reacted in a mixture of DMSO/H2O/CH3CN (4 mL/
4 mL/5 mL) according to general method E. The crude product was
purified by aluminum oxide chromatography in 94:6 n-hexane/
acetone, to give 7b (778 mg, 46%) as yellow crystals; mp
223e224 ꢀC; Rf 0.20 (94:6 n-hexane/acetone); IR nmax (KBr): 3402,
2954, 2928, 2857, 2119, 1634, 1591, 1530, 1489, 1458, 1429, 1404,
1349, 1302, 1253, 1207, 1129, 1062, 1005, 886, 812, 771, 732, 533,
reacted in CH2Cl2 (4 mL) according to general method D. The crude
product was purified by silica gel chromatography in CH2Cl2, to give
5b (1.29 g, 93%) as greenish crystals; mp 97e98 ꢀC; Rf 0.51 (98:2 n-
hexane/acetone); IR nmax (KBr): 3434, 2952, 2931, 2857, 2122, 1674,
1599, 1455, 1426, 1404, 1379, 1270, 1131, 1109, 1062, 1008, 886, 816,
741, 500, 446 cmꢁ1; 1H NMR (360 MHz, CDCl3, Me4Si):
d (ppm) 7.65
(d, 1H, J¼8.0 Hz, arom), 7.55 (d, 1H, J¼8.6 Hz, arom), 7.50e7.48 (m,
2H, arom), 7.36 (dd, 1H, J¼1.8 Hz, J¼8.0 Hz, arom), 7.32 (d, 1H,
436 cmꢁ1 1H NMR (360 MHz, Py-d, Me4Si):
; d (ppm) 10.71 (s, 1H,

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L. Lazar et al. / Tetrahedron 70 (2014) 3691e3699
3698
NH), 8.38 (d, 1H, J¼8.7 Hz, arom), 8.25 (br s, 1H, arom), 8.21 (dd, 1H,
J¼1.5 Hz, J¼8.3 Hz, arom), 7.95 (d, 1H, J¼1.5 Hz, arom), 7.90e7.87
(m, 3H, arom), 7.82e7.80 (m, 2H, arom), 7.76e7.71 (m, 3H, arom),
7.68 (dd, 1H, J¼1.6 Hz, J¼8.1 Hz, arom), 7.63e7.59 (m, 2H, arom),
7.27e7.14 (m, 2H, arom), 2.13e1.97 (m, 8H, 4ꢃ CH2Cq), 1.10e0.71
(m, 16H, 8ꢃ CH2) 0.63 (t, 6H, J¼7.2 Hz, 2ꢃ CH3), 0.56 (t, 6H, J¼7.2 Hz,
738, 522 cmꢁ1 1H NMR (360 MHz, CDCl3, Me4Si):
; d (ppm)
8.32e6.84 (m, 16H, NH, arom), 2.36e1.49 (m, 4H, 2ꢃ CH2),
0.62e0.28 (m, 6H, 2ꢃ CH3); 13C NMR (90 MHz, CDCl3):
d (ppm)
158.8 (CO), 151.8e116.4 (26C, arom), 56.6, 56.5 (Cq), 32.5 (2ꢃ CH2),
8.5 (2ꢃ CH3).
2ꢃ CH3); 13C NMR (90 MHz, Py-d):
d (ppm) 160.6 (CO), 154.5, 153.9,
4.22. Oligo[N-(9,9-dibutylfluorene-2,7-diyl)-2-(9,9-
dibutylfluorene-2,7-diyl)-isoindolene-1-carboxamide] (8b)
152.4,152.2,141.2,141.0,140.8,140.7,140.2,131.2,130.9,128.0,127.2,
127.0, 125.8, 125.2, 125.2, 123.0, 122.6, 122.6, 121.9, 121.8, 121.3,
121.2, 121.1, 120.8, 120.3, 119.7, 118.8, 114.9 (32C, arom), 56.5, 56.3
(2ꢃ Cq), 40.7, 40.4 (4ꢃ CH2Cq), 26.8 (4ꢃ CH2), 23.6 (4ꢃ CH2), 14.3,
14.3 (4ꢃ CH3). ESI-HRMS: m/z calcd for C51H54Br2N2ONaþ [MþNa]þ
891.250. Found: 891.249.
Monobrominated derivative of 7b: (N-(9,9-dibutylfluoren-2-yl)-
2-(7-bromo-9,9-dibutylfluoren-2-yl)-isoindole-1-carboxamide or
N-(7-bromo-9,9-dibutylfluoren-2-yl)-2-(9,9-dibutylfluoren-2-yl)-
Monomer 7b (250 mg, 0.287 mmol), Ni(cod)2 (86 mg,
0.313 mmol), 2,20-bipyridine (49 mg, 0.313 mmol), and 1,5-
cyclooctadiene (38 mL, 0.313 mmol) were reacted in a mixture of
dry DMF/dry toluene (3 mL/3 mL) according to general method F.
The crude product was purified by aluminum oxide chromatogra-
phy, first in 8:2 n-hexane/acetone and then in 9:1 CH2Cl2/MeOH, to
give 8b (61 mg, 30%) as a brownish gray powder; IR nmax (KBr):
3394, 2954, 2928, 2858, 1706, 1613, 1530, 1489, 1463, 1376, 1299,
isoindole-1-carboxamide):
C
ESI-HRMS:
m/z
calcd
for
51H55BrN2ONaþ [MþNa]þ 813.339. Found: 813.335.
1186, 1065, 1036, 991, 926, 887, 815, 755, 634 cmꢁ1
(360 MHz, CDCl3, Me4Si):
2.24e1.60 (m, 8H, 4ꢃ CH2Cq), 1.26e0.61 (m, 28H, 8ꢃ CH2, 4ꢃ CH3);
13C NMR (90 MHz, CDCl3):
(ppm) 158.7 (CO), 153.3e113.5 (32C,
;
1H NMR
Bromine-free derivative of 7b: (N-(9,9-dibutylfluoren-2-yl)-2-
d
(ppm) 8.31e6.77 (m, 18H, NH, arom),
(9,9-dibutylfluoren-2-yl)-isoindole-1-carboxamide): ESI-HRMS: m/
z calcd for C51H56N2ONaþ [MþNa]þ 735.428. Found: 735.425.
d
arom), 55.3, 55.2, 55.1, 55.0 (2ꢃ Cq), 40.0, 40.0, 39.9, 39.7 (4ꢃ
4.20. N-[7-Bromo-9,9-bis(2-ethylhexyl)-fluoren-2-yl]-2-[7-
bromo-9,9-bis(2-ethylhexyl)-fluoren-2-yl]-isoindole-1-
carboxamide (7c)
CH2Cq), 25.9, 25.8 (4ꢃ CH2), 22.9, 22.8 (4ꢃ CH2), 13.7, 13.6 (4ꢃ CH3).
4.23. Oligo{N-[9,9-bis(2-ethylhexyl)fluorene-2,7-diyl]-2-[9,9-
bis(2-ethylhexyl)fluorene-2,7-diyl]-isoindolene-1-
carboxamide} (8c)
Amine 3c (1.21 g, 2.50 mmol), isocyanide (5c, 2.47 g, 5.00 mmol),
OPA (335 mg, 2.50 mmol), and NaHSO3 (539 mg, 5.18 mmol) were
reacted in a mixture of DMSO/H2O/CH3CN (6 mL/6 mL/8 mL)
according to general method E. The crude product was purified by
aluminum oxide chromatography in 85:15 n-hexane/CH2Cl2, to
give 7c (280 mg, 10%) as a brown solid spume; Rf 0.44 (8:2 n-hex-
ane/CH2Cl2); IR nmax (KBr): 3415, 2956, 2925, 2855, 1668, 1615,
1589,1523,1486,1458,1425,1348,1302,1202,1127,1062,1006, 881,
Monomer 7c (250 mg, 0.228 mmol), Ni(cod)2 (68 mg,
0.249 mmol), 2,20-bipyridine (39 mg, 0.249 mmol), and 1,5-cyclo-
octadiene (31 mL, 0.249 mmol) were reacted in a mixture of dry
DMF/dry toluene (2 mL/2 mL) according to general method F. The
crude product was purified by aluminum oxide chromatography,
first in 7:3 n-hexane/CH2Cl2 and then in 95:5 CH2Cl2/MeOH, to give
8c (60 mg, 28%) as a brown syrup; IR nmax (KBr): 3389, 2956, 2925,
2856, 1768, 1706, 1613, 1531, 1456, 1377, 1302, 1255, 1194, 1064,
812, 765, 730, 535, 441 cmꢁ1
(ppm) 8.17e8.11 (m, 1H, NH), 7.78e7.11 (m, 17H, arom), 2.02e1.93
(m, 8H, 4ꢃ CH2Cq), 0.92e0.52 (m, 60H, 4ꢃ CH, 16ꢃ CH2, 8ꢃ CH3);
13C NMR (90 MHz, CDCl3):
(ppm) 158.4, 158.3 (CO), 153.1e151.3,
;
1H NMR (360 MHz, CDCl3, Me4Si):
d
d
1037, 887, 814, 756, 740, 695, 634, 500 cmꢁ1
CDCl3, Me4Si):
(m, 8H, 4ꢃ CH2Cq), 0.90e0.52 (m, 60H, 4ꢃ CH, 16ꢃ CH2, 8ꢃ CH3);
13C NMR (90 MHz, CDCl3):
(ppm) 158.4 (CO), 153.0e151.3 (9
;
1H NMR (360 MHz,
141.0e135.8,130.3e114.6 (32C, arom), 55.5, 55.4, 55.2 (2ꢃ Cq), 44.6,
44.4, 44.2 (4ꢃ CH2Cq), 34.8, 34.6, 34.5 (4ꢃ CH), 34.0, 33.7, 33.6, 33.5
(4ꢃ CH2), 28.4, 28.0 (4ꢃ CH2), 27.1, 27.0, 26.9 (4ꢃ CH2), 22.8, 22.7
(4ꢃ CH2), 14.3, 14.3 (4ꢃ CH3), 10.4, 10.2, 10.1 (4ꢃ CH3). ESI-HRMS:
d (ppm) 8.24e6.96 (m, 18H, NH, arom), 2.04e1.92
d
peaks), 142.2, 141.0e140.7 (5 peaks), 139.9, 138.8, 137.7, 137.6, 135.8,
135.8, 135.7, 130.3, 129.7, 128.6, 127.5e125.0 (11 peaks), 124.3, 122.6,
121.9, 121.8, 121.4, 120.3, 120.1, 119.9, 119.6, 119.5, 118.0, 117.9, 117.7,
117.1, 116.8, 116.7, 114.7 (32C, arom), 55.5, 55.4, 55.3, 55.2, 54.9 (2ꢃ
Cq), 44.6, 44.5, 44.4 (4ꢃ CH2Cq), 34.8, 34.6, 34.6 (4ꢃ CH), 34.0, 33.5
(4ꢃ CH2), 28.4, 28.0 (4ꢃ CH2), 27.1, 27.0, 26.8 (4ꢃ CH2), 22.8, 22.7
(4ꢃ CH2), 14.0 (4ꢃ CH3), 10.3, 10.2, 10.1 (4ꢃ CH3).
m/z calcd for
1115.499.
C
67H86Br2N2ONaþ [MþNa]þ 1115.500. Found:
Monobrominated derivative of 7c: (N-[9,9-bis(2-ethylhexyl)-flu-
oren-2-yl]-2-[7-bromo-9,9-bis(2-ethylhexyl)-fluoren-2-yl]-iso-
indole-1-carboxamide
or
N-[7-bromo-9,9-bis(2-ethylhexyl)-
fluoren-2-yl]-2-[9,9-bis(2-ethylhexyl)-fluoren-2-yl]-isoindole-1-
carboxamide): ESI-HRMS: m/z calcd for C67H87BrN2ONaþ [MþNa]þ
1037.589. Found: 1037.593.
Bromine-free derivative of 7c: (N-[9,9-bis(2-ethylhexyl)-fluoren-
2-yl]-2-[9,9-bis(2-ethylhexyl)-fluoren-2-yl]-isoindole-1-
carboxamide): ESI-HRMS: m/z calcd for C67H88N2ONaþ [MþNa]þ
959.679. Found: 959.680.
Acknowledgements
This work was financially supported by the grant K-101850
given by OTKA (National Found for Scientific Research De-
ꢀ
velopment, Hungary), and the grant TAMOP-4.2.2.A-11/1/KONV-
2012-0036 by the European Union. This research was realized in
the frames of TAMOP 4.2.4.A/2-11-1-2012-0001 National Excel-
lence Program (M.N.) elaborating and operating an inland student
and researcher personal support system convergence program. The
project was subsidized by the European Union and co-financed by
the European Social Fund.
4.21. Oligo[N-(1,4-phenylene)-2-(9,9-diethylfluorenene-2,7-
diyl)-isoindolene-1-carboxamide] (8a)
ꢀ
Monomer 7a (270 mg, 0.440 mmol), Ni(cod)2 (132 mg,
0.480 mmol), 2,20-bipyridine (75 mg, 0.480 mmol), and 1,5-
cyclooctadiene (59 mL, 0.480 mmol) were reacted in a mixture of
dry DMF/dry toluene (6 mL/10 mL) according to general method F.
The crude product was purified by recrystallization from 1:1
CH2Cl2/n-hexane, to give 8a (120 mg, 60%) as a gray powder; IR nmax
(KBr): 3410, 3030, 2961, 2922, 2874, 2852, 1655, 1590, 1520, 1500,
1468, 1418, 1339, 1313, 1237, 1203, 1128, 1107, 1004, 883, 816, 762,
Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.tet.2014.04.018.

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L. Lazar et al. / Tetrahedron 70 (2014) 3691e3699
3699
19. Lee, Y. S.; Hu, H. S.-W.; Kim, O.-K. Mol. Cryst. Liq. Cryst. Incorporating Nonlinear
Opt. 1990, 190, 9e18.
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