A facile convergent procedure for the preparation of triphenylamine-based dendrimers with truxene cores

Article abstract of DOI:10.1016/j.tet.2008.04.021

A simple convergent procedure has been developed for the preparation of triphenylamine dendrons containing an alkene at the center, which can be coupled in a single step to give dendrimers that contain truxene for the core without any protection-deprotection chemistry. These conjugated dendrimers exhibit similar absorption and emission behaviors in solutions and in thin films, which are indicative of the high isolation effect of well-organized three-dimensional dendrimers. They also have high fluorescence quantum yields and high glass transition temperatures, which indicate that these dendrimers are candidates for the application in OLED as light emitting materials.

Full text of DOI:10.1016/j.tet.2008.04.021

Tetrahedron 64 (2008) 5736–5742
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
A facile convergent procedure for the preparation of triphenylamine-based
dendrimers with truxene cores
*
Haijian Xia, Jiating He, Bin Xu, Shanpeng Wen, Yaowen Li, Wenjing Tian
State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A simple convergent procedure has been developed for the preparation of triphenylamine dendrons
containing an alkene at the center, which can be coupled in a single step to give dendrimers that contain
truxene for the core without any protection–deprotection chemistry. These conjugated dendrimers ex-
hibit similar absorption and emission behaviors in solutions and in thin films, which are indicative of the
high isolation effect of well-organized three-dimensional dendrimers. They also have high fluorescence
quantum yields and high glass transition temperatures, which indicate that these dendrimers are
candidates for the application in OLED as light emitting materials.
Received 10 January 2008
Received in revised form 1 April 2008
Accepted 7 April 2008
Available online 9 April 2008
Keywords:
Triphenylamine
Truxene
Ó 2008 Published by Elsevier Ltd.
Dendrimers
Fluorescence
1. Introduction
ability, and optoelectronic properties.6 Considerable effort in syn-
thetic chemistry, in particular by Shirota and co-workers, has led to
In the past few decades,
p
-conjugated dendrimers have been
the development of many classes of TPA-based compounds as hole-
transporting or electroluminescent materials.6a–c To our knowl-
edge, most of triphenylamine derivatives are connected by the N–C
single-bond and obtained either through palladium-catalyzed
cross-coupling reactions requiring expensive and extremely air-
sensitive palladium catalysts or through copper-catalyzed Ullmann
condensations usually involving high temperatures and prolonged
reaction time, but few papers about triphenylamine derivatives
connected by the C–C double bond were published.7 The triphe-
nylamine derivatives connected by the C–C double bond can be
easily synthesized by Heck reaction and Wittig–Horner reaction
without air-sensitive catalysts or high temperatures and prolonged
reaction time, and the structure similar to the p-phenylene vinylene
moiety has the interesting photochemical and photophysical
properties. Our group has previously reported triphenylamine-
based dendrimers with 1,3,5-triphenylbenzene cores connected by
the C–C double bond.7c
extensively studied because of their unusual molecular structures
and the potential of acting as the active chemical components, such
as organic light emitting diodes (OLEDs),1 photovoltaic cells,2 op-
tical power limiting,3 and field-effect transistors.4 One of the im-
portant challenging goals of dendritic materials chemistry is to
develop new families of
p-conjugated dendritic molecules with
novel branches and cores, to investigate their physical and chemical
properties, as well as to understand the structure–property re-
lationship within such structures. Compared with
p-conjugated
polymers, -conjugated dendritic systems possessing well-defined
p
conjugation lengths and structural models are characterized by the
uniformity, absence of chain defects, and ease of purification and
characterization, which make them superior to
polymers for systematic investigation of the structure–property
relationships. Further more, -conjugated dendritic systems with
large branching building blocks can exhibit intrinsic two- or three-
dimensional architectures, which can overcome the quenching of
luminescence, and such large dendritic structures also efficiently
improve the film formation ability.5
Triphenylamine (TPA) derivatives have been widely investigated
for almost two decades because these compounds have shown
excellent thermal and electrochemical stability, electron donating
p-conjugated
p
10,15-Dihydro-5H-diindeno[1,2-a;10,20-c]fluorene (truxene),
a
polycyclic aromatic system with C3 symmetry,8 has been recog-
nized as a potential starting material for the construction of bowl-
shaped fragments of the fullerenes,9 C3 tripodal materials in chiral
recognition,10 and liquid crystalline compounds.11,12 Some syn-
trialkylated truxenes (monoalkylated at each CH2 group) have been
shown to self-associate in solution through arene–arene in-
teractions.13 Recently, Pei and co-workers have successfully in-
troduced oligothiophene arms and oligophenylene to the truxene
* Corresponding author. Tel.: þ86 431 85166212; fax: þ86 431 85193421.
E-mail address: wjtian@mail.jlu.edu.cn (W. Tian).
core14a,b and developed novel
p-conjugated dendrimers based on
0040-4020/$ – see front matter Ó 2008 Published by Elsevier Ltd.
doi:10.1016/j.tet.2008.04.021

H. Xia et al. / Tetrahedron 64 (2008) 5736–5742
5737
truxene from the viewpoint of fundamental chemistry as well as
practical applicants in organic optics and electronics.14 Further-
more, Skabara and co-workers reported on employing the truxene
core for the construction of virtually ‘no-core’ star-shaped oligo-
fluorene architectures.15
AcOH at 85 ꢀC provided compound 2 in a yield of 95%,16 an im-
portant intermediate for the synthesis of larger triphenylamine
dendrons. The first generation alkene-focused dendron 3 was
prepared in an 88% yield from the reaction of 4-(diphenylamino)-
benzaldehyde 1 with the methyltriphenylphosphonium bromide.17
The first step in the procedure was the formation of the aldehyde 4,
which was prepared in an 88% yield from the coupling of 3 with 2
by the Heck reaction.18 The second step in the first cycle of the
In this paper, therefore, we report the design, synthesis, char-
acterization, and photophysical properties of two representative
conjugated dendrimers having truxene as the core with three tri-
phenylamine branches through a simple convergent procedure
without any protection–deprotection chemistry. These conjugated
dendrimers are readily soluble in common organic solvents,
exhibiting good film forming properties. They exhibit similar ab-
sorption and emission behaviors in solutions and in thin films,
which are indicative of the high isolation effect of well-organized
three-dimensional dendrimers. They also have high fluorescence
quantum yield and high glass transition temperatures, which in-
dicate that these dendrimers are candidates for the application in
OLED as light emitting materials.
procedure was the reaction of aldehyde
4 with methyl-
triphenylphosphonium bromide to give the second generation
alkene-focused dendron 5.
2.2. Synthesis of the dendrimers
The synthesis of dendritic triphenylamine-based truxene is
shown in Scheme 2. Firstly, truxene was alkylated to give readily
soluble hexabutylated truxene, which was subsequently converted
to hexabutylated truxene triiodide 7 in high yield by electrophilic
iodination as reported by Pei co-workers.14d The obtained alkenes 3
and 5 were converted into the corresponding dendritic truxenes
Tr-TPA3 and Tr-TPA9 with 7 by Heck reaction.18
2. Results and discussion
2.1. Synthesis of the triphenylamine-based dendrons
The dendrimers are soluble in common organic solvents such as
chloroform, dichloromethane, 1,2-dichloroethane, and THF, which
are helpful for separation and purification. All dendrons and den-
drimers were characterized by FTIR, elemental analysis, 1H NMR
spectroscopy, 13C NMR spectroscopy, and MALDI-TOF mass spec-
trometry. Both dendrons 3 and 5 possess a proton chemical shift at
5.77 ppm and 5.80 ppm and have the coupling constant
(Jw16.5 Hz), respectively, which prove to be the trans alkene
The strategy as reported by our group7c for the alkene-focused
dendron synthesis was illustrated in Scheme 1. The formation of
a dendron with an alkene at its center involves a Heck coupling
followed by a simple Wittig reaction. First, 4-(diphenylamino)-
benzaldehyde 1 was readily obtained from triphenylamine through
a Vilsmeier reaction in a yield of 79%. Iodination of 1 with KI/KIO3 in
I
KI (4/3 equiv), KIO3 (2/3 equiv)
N
CHO
AcOH, 85 °C, 5 h
2 95%
POCl3,DMF
45 °C,2.5h
I
N
N
CHO
1
Ph3PCH3Br, t-BuOK
THF,RT, 8 h
N
3 76%
N
N
Ph3PCH3Br, t-BuOK
THF,RT,8 h
N
CHO
N
Pd(OAc)2, K3PO4, DMAc
110 °C, 24 h
N
N
5 67%
4
55%
Scheme 1. Synthesis of triphenylamine dendrons 3 and 5.

5738
H. Xia et al. / Tetrahedron 64 (2008) 5736–5742
I
I
H5IO6,I2,CH3COOH
H2SO4,H2O,80 °C
I
7
6
N
N
Pd(OAc)2, K3PO4, DMAc
110 °C, 24 h
7 + 3
N
Tr-TPA3 41%
N
N
N
N
N
Pd(OAc)2, K3PO4, DMAc
110 °C, 24 h
5 +7
N
N
N
N
Tr-TPA9 24%
Scheme 2. Synthesis of the dendrimers Tr-TPA3 and Tr-TPA9.

H. Xia et al. / Tetrahedron 64 (2008) 5736–5742
5739
hydrogen. The coupling constant (Jw16.5 Hz) of olefinic protons in
Tr-TPA3
Tr-TPA9
Tr-TPA3
Tr-TPA9
Tr-TPA3 and Tr-TPA9 indicates that Heck reaction afforded the pure
all-trans isomer. The pure all-trans isomers of Tr-TPA3 and Tr-TPA9
were further confirmed by the characterization of vibration band of
trans double bond at 958 cmꢁ1and 960 cmꢁ1 in FTIR spectra, re-
spectively.19 Additional definitive evidence for the dendrimer mo-
lecular structures was obtained from MALDI-TOF mass spectra. The
deviation between the calculated and experimentally measured
m/z values was no more than one mass unit. For example, the
molecular formula of Tr-TPA9 is C231H209N9. The calculated average
for the peak of the molecular ion [MþH] is 3100.6 and we obtained
the value 3101.4. The MALDI-TOF mass spectrometry of Tr-TPA3 and
Tr-TPA9 are shown in Supplementary data.
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
2.3. Photophysical properties
250 300 350 400 450 500 550 600 650 700
Wavelength (nm)
In order to investigate their photophysical properties, the ab-
sorption and the photoluminescent (PL) spectra of Tr-TPA3 and Tr-
TPA9 both in dilute chloroform solutions and in the solid films were
recorded. Figure 1 illustrates the absorption and PL spectra of Tr-
TPA3 and Tr-TPA9 in dilute chloroform solutions. For the UV–vis
absorption spectrum in chloroform solution, Tr-TPA3 displays two
absorption peaks at 311 nm and 392 nm, which are ascribed to the
Figure 2. Normalized absorption (left) and fluorescence spectra (right) of novel con-
jugated dendrimers in the solid films. Emission spectra were obtained upon excitation
at the absorption maximum.
Table 1
Photophysical properties of Tr-TPA3 and Tr-TPA9
absorption of triphenylamine moiety and
p–
*
p transition, re-
labs/nm
lem/nm
4fa/%
labs/nm
lem/nm
spectively. It is also observed that Tr-TPA9 displays two absorption
peaks at 310 nm and 413 nm, which exhibits similar behaviors to
Tr-TPA3. Nevertheless, the intensity of the peak at about 310 nm of
Tr-TPA9 decreases in comparison with that of Tr-TPA3, because the
relative number of triphenylamine compared to the number of
Sol
Sol
Sol
Films
Films
Tr-TPA3
Tr-TPA9
392
413
445(465)
476
100
84.7
396
414
467(441)
500
a
Quinine sulfate was used as a standard (lexc¼365 nm; 4f¼0.546 in H2O).
p–
p transition in Tr-TPA9 is reduced. For the emission spectra in
*
dilute chloroform solutions, Tr-TPA3 and Tr-TPA9 also display
similar behaviors. The emission peaks of compounds Tr-TPA3 and
Tr-TPA9 locate at 445 nm (465 nm) and 476 nm, respectively. The
emission peak of Tr-TPA9 is red-shifted 31 nm from that of Tr-TPA3,
since multibranched configuration shows more tendency toward
the twisted geometry on the excited state, which might consume
the excited energy and reduce their quantum yield.
The absorption and emission spectra of Tr-TPA3 and Tr-TPA9 in
the solid films are presented in Figure 2. The absorption behaviors
of Tr-TPA3 and Tr-TPA9 in the solid films are quite similar to those in
solution. The absorption maxima of Tr-TPA3 and Tr-TPA9 in films
are red-shifted in relation to those in solution, due to the aggre-
gation effect, with the degree of red-shift depending on the
generation number of the dendrimer. The absorption maxima of
Tr-TPA3 and Tr-TPA9 in films, for example, are red-shifted by 4 nm
and 1 nm, respectively, or in other words, the higher the generation,
the smaller the red-shift in the absorption. These results indicate
the absence of aggregation in the dendrimers because of such large
sizes of the molecules with six butyl substituents in truxene and
lots of the noncoplanar triphenylamines. There is no significant
ordering of the dendrimers either from aggregation or crystalliza-
tion, and hence the dendrimers films are in a good amorphous
state,21 which are very important for the application of materials in
optical and electronic devices such as OLEDs. The emission peaks of
Tr-TPA3 and Tr-TPA9 in the solid films are red-shifted in comparison
with those in solutions. Moreover, the molecular vibronic features
disappeared for compound Tr-TPA9, gave out bright blue emission
with high quantum efficiency. The photophysical properties of
Tr-TPA3 and Tr-TPA9 are summarized in Table 1.
which shows that there is obvious
p–
*
p delocalization with the
increase of the generation of dendrimers. These results also dem-
onstrate that the effective conjugation length significantly im-
proves with the increasing generation of the dendrimers.20 The
fluorescence quantum yields (4f) of Tr-TPA3 and Tr-TPA9 in dilute
chloroform solution are measured to be 100% and 84.7%, by using
quinine sulfate as a standard, respectively. It is intelligible that the
Tr-TPA9, the multibranched molecules with higher generation, has
lower quantum yields than the Tr-TPA3 with lower generation,
Tr-TPA3
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
Tr-TPA9
Tr-TPA3
Tr-TPA9
2.4. Thermal analysis
For the photoelectronic applications, the thermal stability of
organic materials is critical for device stability and lifetime because
during the electroluminescent process, heat is generated that can
affect the material morphology and the device performance, finally
leading to the degradation of OLEDs. Hence, the relatively high Tg is
essential for materials used as emissive materials for optoelectronic
applications. We found that the two dendrimers were amorphous
250 300 350 400 450 500 550 600 650 700
Wavelength (nm)
Figure 1. Normalized absorption (left) and fluorescence spectra (right) of novel
conjugated dendrimers in dilute chloroform solution (1ꢂ10ꢁ6 M). Emission spectra
were obtained upon excitation at the absorption maximum.

5740
H. Xia et al. / Tetrahedron 64 (2008) 5736–5742
using a NETZSCH (DSC-204) instrument at 10 ꢀC minꢁ1 under ni-
Tr-TPA3
Tr-TPA9
trogen. Compounds of 1–3 were readily obtained according to the
literature procedures.16,17
4.2. Compound 2
Tg=140 °C
4-(N,N-Diphenylamino)benzaldehyde (14.00 g, 51.28 mmol),
potassium iodide (11.43 g, 68.85 mmol), and acetic acid (210 mL)
were heated to 85 ꢀC, and the solution was allowed to cool. Then
the potassium iodate (10.97 g, 51.26 mmol) was added and the re-
action mixture was heated at 85 ꢀC for 5 h. The solution was
allowed to cool to room temperature and poured into ice-water
under stirring. The yellow precipitated solid was collected by
filtration, and the collected solid was poured into 5% NaHSO3
(100 mL) to clear I2 and KIO3. The final filtrated yellow solid was
pure compound 2. Mp: 142–143ꢀC. 1H NMR (500 MHz, CDCl3)
Tg=115 °C
60
80
100
120
Temperature (°C)
140
160
180
200
d
9.85 (s, 1H, CHO), 7.71 (d, J¼8.5 Hz, 2H, Ar), 7.63 (d, J¼8.5 Hz, 4H,
Ar), 7.05 (d, J¼8.5 Hz, 2H, Ar), 6.89 (d, J¼8.5 Hz, 4H, Ar).
Figure 3. DSC curves (second run) of compounds Tr-TPA3 and Tr-TPA9.
4.3. Compound 3
4-(N,N-Diphenylamino)benzaldehyde 1 (5.46 g, 20 mmol) and
methyltriphenylphosphonium bromide (8.57 g, 24 mmol) were
dissolved in 100 mL of dry THF. t-BuOK (3.36 g, 30 mmol) in 30 mL
of dry THF was added dropwise slowly to the resulting solution at
0 ꢀC, then the reaction mixture was warmed to room temperature
and stirred under N2 for 12 h. The reaction mixture was poured
into water and extracted with CH2Cl2 (3ꢂ60 mL). The combined
organic extracts were washed with brine, dried (Mg2SO4), and
concentrated to dryness under vacuum. The crude product was
purified by flash column chromatography (petroleum ether/
CH2Cl2¼4:1) to give 4.12 g (76%) of product 3 as a white solid. Mp:
91–92ꢀC.
at room temperature. The glass transition temperatures (Tg) of the
dendrimers increased from 115 ꢀC to 140 ꢀC with the increase of the
generation of dendrimers because the multibranched molecules
with higher generation tend to hinder translational, rotational, and
vibrational motions of the molecule and result in Tg enhancement.
Furthermore, no transitions related to crystalline structures were
observed for the two dendrimers and upon cooling, the materials
stay in an amorphous glassy phase. The differential scanning
calorimetric thermogram of compounds Tr-TPA3 and Tr-TPA9 is
shown in Figure 3.
3. Conclusion
1H NMR (500 MHz, CDCl3)
d
7.28 (d, J¼8.5 Hz, 2H, Ar), 7.23–7.26
(m, 4H, Ar), 7.09 (d, J¼8.0 Hz, 4H, Ar), 6.98–7.03 (m, 4H, Ar), 6.63–
6.69 (m, 1H, CH), 6.63 (d, J¼16.5 Hz, 1H, CH]CH2), 5.15 (d, J¼8.5 Hz,
1H, CH]CH2).
In conclusion, we have synthesized two new conjugated den-
drimers bearing triphenylamine moiety as dendrons and truxene as
a core through a convergent synthetic strategy without any pro-
tection–deprotection chemistry. These conjugated dendrimers ex-
hibit similar absorption and emission behaviors in solutions and in
thin films, which demonstrate that these dendrimers form amor-
phous states. They also have high fluorescence quantum yields and
high glass transition temperatures, which indicate that these den-
drimers are candidates for the application in OLED as light emitting
materials. We are currently investigating the electroluminescent
properties of these dendrimers.
4.4. Compound 4
A round-bottomed flask (250 mL) was oven dried and cooled
under N2 atmosphere. 4-[N,N-Di(4-iodophenyl)amino]benzalde-
hyde 2 (5.25 g, 10 mmol), compound 3 (7.0 g, 26 mmol), K3PO4
(6.5 g, 30 mmol), and 10 mg Pd(OAc)2 were dissolved in dry DMAc
(50 mL). The reaction mixture was heated to 110 ꢀC in an oil bath
and stirred for 24 h at this temperature. After being cooled to room
temperature, the reaction mixture was poured into water and
extracted with CH2Cl2 (3ꢂ50 mL). The combined organic extracts
were washed with brine, dried (Mg2SO4), and concentrated to
dryness under vacuum. The crude product was purified by flash
column chromatography (petroleum ether/CH2Cl2¼1:1) to give
4.47 g (55%) of product 4 as a yellow solid.
4. Experimental section
4.1. Experimental
All chemicals, reagents, and solvents were used as received from
commercial sources without further purification. Tetrahydrofuran
(THF) was refluxed with sodium and benzophenone, and distilled.
1H NMR and 13C NMR spectra were recorded on an AVANCE 500
spectrometer and a Varian Mercury-300 NMR, respectively, with
tetramethylsilane (TMS) as the standard. The compounds were
characterized by Flash EA 1112, CHNS-O elemental analysis in-
strument. The FTIR spectra were recorded via the KBr pellet method
by using a Nicolet Impact 410 FTIR spectrophotometer. The mass
spectra were recorded on a Kratos MALDI TOF mass system, and the
spectrum was recorded in the linear or reflect mode with anthra-
cene-1,8,9-triol as the matrix. UV–vis absorption spectra were
measured using a Shimadzu UV-3100 spectrophotometer. The
photoluminescence were recorded on Shimadzu RF-5301PC fluo-
rescence spectrophotometer. The DSC analysis was determined
1H NMR (500 MHz, CDCl3)
d
9.83 (s, 1H, CHO), 7.71 (d, J¼8.5 Hz,
2H, Ar), 7.45 (d, J¼8.5 Hz, 4H, Ar), 7.38 (d, J¼8.5 Hz, 4H, Ar), 7.25–
7.28 (m, 12H, Ar), 7.10–7.15 (m, 12H, Ar), 7.00–7.06 (m, 8H, Ar), 6.96
(d, J¼16.5 Hz, 2H, Ar). MALDI/TOFMS: calcd for C59H45N3O: 812.0,
found: 812.9. Anal. Calcd for C59H45N3O: C, 87.27; H, 5.59; N, 5.17.
Found: C, 87.15; H, 5.70; N, 5.09.
4.5. Compound 5
Compound 4(2.02 g, 2.5 mmol) and methyltriphenylphosphonium
bromide (1.1 g, 3 mmol) were dissolved in 50 mL of dry THF. BuOK
(0.45 mg, 4 mmol) in 10 mL of dry THF was added dropwise slowly to
the resulting solution at 0 ꢀC, then the reaction mixturewas warmed to
room temperature and stirred under N2 for 12 h. The reaction mixture

H. Xia et al. / Tetrahedron 64 (2008) 5736–5742
5741
was poured into water and extracted with CH2Cl2 (3ꢂ50 mL). The
combined organic extracts were washed with brine, dried (Mg2SO4),
and concentrated to dryness under vacuum. The crude product was
purified by flash column chromatography (petroleum ether/
CH2Cl2¼4:1) to give 1.36 g (67%) of product 5 as a yellow solid.
ether/CH2Cl2¼4:1) to give 0.149 g (24%) of product Tr-TPA9 as
a yellow solid.
1H NMR (500 MHz, CDCl3)
d
8.36 (d, J¼7.0 Hz, 3H, Ar), 7.58 (d,
J¼9.0 Hz, 6H, Ar), 7.49 (d, J¼8.0 Hz, 6H, Ar), 7.37–7.42 (m, 24H, Ar),
7.25–7.28 (m, 24H, Ar), 7.20 (d, J¼8.0 Hz, 6H, Ar), 7.11–7.15 (m, 39H,
Ar), 6.98–7.06 (m, 39H, Ar), 2.99 (br, 3H, CH2), 2.14 (m, 3H, CH2),
0.88–0.93 (m, 12H, CH2), 0.58–0.64 (m, 12H, CH2), 0.47 (t, J¼7.0 Hz,
18H, CH3). 13C NMR (75 MHz, CDCl3) 13.87, 22.90, 26.57, 29.69,
55.54, 122.96, 123.67, 124.13, 124.42, 126.44, 126.90, 127.17, 127.32,
127.66, 129.26, 131.77, 132.49, 135.70, 138.20, 139.85, 145.10, 146.42,
147.12, 147.58, 154.18. MALDI/TOFMS: calcd for C231H209N9: 3100.6,
found: 3101.4. Anal. Calcd for C231H209N9: C, 89.41; H, 6.53; N, 4.06.
Found: C, 89.24; H, 6.72; N, 3.94.
1H NMR (500 MHz, CDCl3)
d 7.31–7.39 (m, 12H, Ar), 7.10–7.27 (m,
12H, Ar), 7.01–7.09 (m, 20H, Ar), 6.65–6.71 (m, 1H, CH), 6.70 (d,
J¼17.5 Hz, 1H, CH]CH2), 5.18(d, J¼11.0 Hz, 1H, CH]CH2). MALDI/
TOFMS: calcd for C60H47N3: 809.4, found: 811.4. Anal. Calcd
for C60H47N3: C, 88.96; H, 5.85; N, 5.19. Found: C, 88.85; H, 6.01; N,
5.07.
4.6. Compound 7
A mixture of compound 6 (2.00 g, 2.96 mmol) and 10 mL of
solvent mixture (CH3COOH/H2SO4/H2O¼100:40:3) was heated to
60 ꢀC with vigorous stirring, followed by addition of 3 mL of CHCl3,
H5IO6 (0.58 g, 2.45 mmol), and I2 (1.25 g, 4.93 mmol). The mixture
was stirred at 80 ꢀC under nitrogen atmosphere for 3 days. The
mixture was cooled to room temperature, and 100 mL of water was
added. The brown precipitate was filtered and purified by
recrystallization three times from ethanol to afford 7 (1.93 g, 61.8%)
as a white solid.
Acknowledgements
This work was supported by the State Key Development
Program for Basic Research of China (Grant No. 2002CB613401), the
National Natural Science Foundation of China (Grant No.
50673035), the Program for Changjiang Scholars and Innovative
Research Team in University (Grant No. IRT0422), Program for
New Century Excellent Talents in Universities of China Ministry
of Education, and the Science Fund of State Key Laboratory of
Polymer Physics and Chemistry (Changchun Institute of Applied
Chemistry).
1H NMR (500 MHz, CDCl3)
d
7.92–8.14 (3H, d, J¼12 Hz), 7.72–
7.80 (3H, s), 7.64–7.72 (3H, d, J¼12 Hz), 2.72–2.98 (6H, m), 1.88–2.16
(6H, m), 0.76–1.08 (36H, m), 0.59–0.76 (18H, t, J¼9.0 Hz), 0.29–0.58
(12H, m).
Supplementary data
4.7. Compound Tr-TPA3
Supplementary data associated with this article can be found in
the online version, at doi:10.1016/j.tet.2008.04.021.
A round-bottomed flask (25 mL) was oven dried and cooled
under N2 atmosphere. Compound 7 (0.21 g, 0.2 mmol), compound
3 (0.27 g, 1 mmol), K3PO4 (0.21 g, 1 mmol), and 0.5 mg Pd(OAc)2
were dissolved in dry DMAc (10 mL). The reaction mixture was
heated to 110 ꢀC in an oil bath and stirred for 24 h at this temper-
ature. After being cooled to room temperature, the reaction mix-
ture was poured into water and extracted with CH2Cl2 (3ꢂ40 mL).
The combined organic extracts were washed with brine, dried
(Mg2SO4), and concentrated to dryness under vacuum. The crude
product was purified by flash column chromatography (petroleum
ether/CH2Cl2¼4:1) to give 0.122 g (41%) of product Tr-TPA3 as
a yellow solid.
References and notes
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1H NMR (500 MHz, CDCl3)
d
8.35 (d, J¼8.0 Hz, 3H, Ar), 7.57 (d,
J¼9.0 Hz, 6H, Ar), 7.46 (d, J¼8.0 Hz, 6H, Ar), 7.26–7.32 (m, 12H, Ar),
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13C NMR (75 MHz, CDCl3) 13.86, 22.90, 26.57, 36.81, 55.53,120.08,
122.86, 123.60, 124.50, 124.86, 127.32, 127.70, 129.28, 131.79,
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4.8. Compound Tr-TPA9
A round-bottomed flask (25 mL) was oven dried and cooled
under N2 atmosphere. Compound 7 (0.21 g, 0.2 mmol), compound
5 (0.58 g, 0.72 mmol), K3PO4 (0.21 g, 1 mmol), and Pd(OAc)2 were
dissolved in dry DMAc (10 mL). The reaction mixture was heated to
110 ꢀC in an oil bath and stirred for 24 h at this temperature. After
being cooled to room temperature, the reaction mixture was
poured into water and extracted with CH2Cl2 (3ꢂ40 mL). The
combined organic extracts were washed with brine, dried
(Mg2SO4), and concentrated to dryness under vacuum. The crude
product was purified by flash column chromatography (petroleum

5742
H. Xia et al. / Tetrahedron 64 (2008) 5736–5742
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