Efficient one-step synthesis of C 3-symmetrical benzenoid compounds mediated by SOCl 2/EtOH

Article abstract of DOI:10.1080/00397911.2011.585731

An efficient one-step synthesis of branched functionalized benzenoid compounds from aryl methyl ketones mediated by SOCl₂/EtOH is described; some novel C ₃-symmetrical molecules were prepared with satisfactory yields. The method enjo

Full text of DOI:10.1080/00397911.2011.585731

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Efficient One-Step Synthesis of C 3-
Symmetrical Benzenoid Compounds
Mediated by SOCl2/EtOH
Sanhu Zhao a , Lina Kang a , Haixia Ge a , Feifei Yang a , Chenlu Wang
a , Chang Li a , Qiang Wang a & Minggen Zhao a
a Department of Chemistry, Xinzhou Teachers University, Xinzhou,
China
Accepted author version posted online: 01 Feb 2012.Version of
record first published: 20 Aug 2012.
To cite this article: Sanhu Zhao, Lina Kang, Haixia Ge, Feifei Yang, Chenlu Wang, Chang Li,
Qiang Wang & Minggen Zhao (2012): Efficient One-Step Synthesis of C 3-Symmetrical Benzenoid
Compounds Mediated by SOCl2/EtOH, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 42:24, 3569-3578
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Synthetic Communications1, 42: 3569–3578, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.585731
EFFICIENT ONE-STEP SYNTHESIS OF
C3-SYMMETRICAL BENZENOID COMPOUNDS
MEDIATED BY SOCl2/EtOH
Sanhu Zhao, Lina Kang, Haixia Ge, Feifei Yang,
Chenlu Wang, Chang Li, Qiang Wang, and Minggen Zhao
Department of Chemistry, Xinzhou Teachers University, Xinzhou, China
GRAPHICAL ABSTRACT
Abstract An efficient one-step synthesis of branched functionalized benzenoid compounds
from aryl methyl ketones mediated by SOCl2/EtOH is described; some novel C3-symmetri-
cal molecules were prepared with satisfactory yields. The method enjoys short reaction time
and simple operation, and avoids use of organometallic reagents.
Keywords Aryl methyl ketone; carbazole; C3-symmetrical molecules; cyclotrimerization;
thionyl chloride
INTRODUCTION
In recent years, C3-symmetrical molecules including polycyclic aromatic hydro-
carbons,[1] dendrimers,[2] and star polymers[3] have attracted considerable attention
because of their potential applications in electronics, physics, biology, and medical
diagnosis.[4] 1,3,5-Trisubstituted benzenes, which have a C3-symmetrical structure,
are versatile organic intermediates for the synthesis of fullerene precursors, electro-
luminescent materials, sensitizers for photographic processes, and conjugated star
polyaromatics.[5] As a result, a variety of methodologies have been developed to
design and synthesize 1,3,5-trisubstituted benzenes. To our knowledge, there are
three routes to access the product. One is transition metal–catalyzed [2 þ 2 þ 2]
Received February 8, 2011.
Address correspondence to Sanhu Zhao, Department of Chemistry, Xinzhou Teachers University,
Xinzhou, China. E-mail: sanhuzhao@yahoo.cn
3569

3570
S. ZHAO ET AL.
Scheme 1. Three pathways to access 1,3,5-trisubstituted benzenes.
Scheme 2. Condensation reaction of aryl methyl ketones mediated by SOCl2/EtOH.
cyclotrimerization of alkynes (path a, Scheme 1).[6] The other route is
metal-catalyzed cross-coupling reactions between 1,3,5-trihalobenzenes with organo-
metallic partners (path b, Scheme 1).[7] The methodologies mentioned often involve
transition metals or noble metals. The need for high catalyst loading in some of these
processes results in high economic cost. The presence of heavy transition-metal
impurities in the final products also presents a major problem for purification.
Compared with the former routes, the third route, synthesis of 1,3,5-triarylben-
zenes from monoacetylaromatic compounds, has been regarded as the most simple
and reliable way (path c, Scheme 1). Many catalysts such as hydrochloric acid,[8]
sodium or potassium pyrosulfate in H2SO4,[9] aniline hydrochloride,[10] TsOH,[11]
amberlyst-15,[12] titanium tetrachloride (TiCl4),[13] SiCl4,[14] SmCl3,[15] CuCl2,[16]
SiCl4–methanol,[17] and Cp2ZrCl2 have been reported in the literature. However,
[18]
except for a few examples, most of these procedures suffer from drawbacks such as
use of precious metal catalysts, long reaction times, or harsh operating conditions.
Herein, we report a novel and facile method to access the 1,3,5-trisubstituted
benzenes from aryl methyl ketones mediated by SOCl2=EtOH (Scheme 2).

C3-SYMMETRICAL BENZENOID COMPOUNDS
3571
RESULTS AND DISCUSSION
Thionyl chloride is the most attractive reagent for the chlorination of alcohols
because of the short reaction time, low reaction temperature, and low price.[19]
Recently, Chmielewski et al. reported utilization of thionyl chloride as a chlorination
agent to synthesize 3,6-dichlorocarbazole from carbazole with good yield.[20] Based
on this, we applied this method to introduce a chlorine atom at the 6-position of
3-acetyl-9-ethylcarbazole. The reaction was conducted in the presence of thionyl
chloride in CH2Cl2 at room temperature; however, the corresponding 3-acetyl-9-
ethyl-6-chlorocarbazole was not detected. To optimize the reaction conditions and
obtain the object product, some reagents such as tetrahydrofuran (THF), 1,4-
dioxane, toluene, and ethanol were employed as reaction solvents. When ethanol
was chosen as solvent, following the addition of thionyl chloride and reflux of the
reaction mixture, the reaction was detected by thin-layer chromatography (TLC).
After 8 h, the reaction mixture was treated with a saturated solution of sodium car-
1
bonate and the product was isolated. To our surprise, the H NMR and 13C NMR
spectram showed that the product was not the intended product. After careful com-
parison of the Fourier transform infrared (FTIR), 1H NMR, and 13C NMR spectram
of the unknown product with the reactant 3-acetyl-9-ethylcarbazole, we noticed that
the IR signal (1660 cmꢀ1, -COCH3), the 13C NMR signal (197.64 ppm, 26.57 ppm,
1
-COCH3), and the H NMR signal (2.65 ppm, -COCH3) of the reactant 3-acetyl-9-
ethylcarbazole apparently disappeared. Thus, we deduced that the reaction’s active
position may be the acetyl group. To further confirm the structure of the product,
the mass spectral (MS) data of the product were measured. According to the experi-
mental results, we presumed that the product was formed from triple condensation of
3-acetyl-9-ethylcarbazole (Scheme 3).
To verify the result, 4-iodoacetophenone was used in this system. To our
delight, under the same conditions, the reaction was completed after 1.5 h, and the
1
melt point and the data of H NMR and 13C NMR spectram of the product were
consistent with 1,3,5-tri-(p-iodophenl)-benzene as reported in the literature.[11]
To obtain the best results, the reaction of acetophenone mediated by SOCl2=
EtOH was carried out under different reaction conditions. The effect of molar ratio
Scheme 3. Triple condensation of 3-acetyl-9-ethylcarbazole.

3572
S. ZHAO ET AL.
of reaction reagents and the effect of reaction time were carefully investigated
(Table 1). The results indicate that the molar excess of thionyl chloride (1.67 equiva-
lent, Table 1, entry 8) and the controlled reaction time would be more useful to
obtain the best yield, Longer reaction times reduce the product yield while increasing
the by-product.
To elucidate the role of ethanol in this process, we conducted the reaction of
acetophenone with thionyl chloride in ethanol-free CH2Cl2. As a result, the conver-
sion (0%, Table 1, entry 1) was gained under this condition. It may seem obvious that
ethanol plays an important role in the formation of the cyclotrimerized product.
With the optimized reaction conditions in hand (Table 1, entry 8), various aryl
methyl ketones were tested to extend the utility of this reaction. It was found that
aryl methyl ketones carrying weak electron-donating groups or weak electron-
withdrawing groups could be smoothly converted to the desired products with excel-
lent isolated yields (82–87%, Table 2, entries 1–5). The triple condensation of
aryl methyl ketones containing strong electron-donating groups and electron-
withdrawing groups afforded 1,3,5-trisubstituted benzenes in poor to moderate
isolated yields (35% and 68%, Table 2, entries 6 and 8). This decrease of yields
can be attributed to the nature of the substituent group. The strong
electron-donating group (–OCH3) does not favor ethanol addition to the carbonyl
(Scheme 4) and the strong electron-withdrawing group (–NO2) does not favor the
oxygen of the carbonyl addition to the thionyl chloride. For aryl methyl ketones
carrying an ortho substituent (Table 2, entry 9), only trace product was found.
The reasons for the yield decrease could be attributed to the steric effect and
Table 1. Effects of the ratio of C6H5COCH3=SOCl2=EtOH and reaction time
Entry
n(C6H5COCH3)=n(SOCl2)=n(EtOH)
Time (min)
Yield (%)
1a
2
3:5:0
3:3:6
90
90
0
38
43
49
57
57
71
87
85
76
86
75
3
3:3:9
90
90
4
3:3:12
3:3:15
3:3:18
3:4:15
3:5:15
3:6:15
3:5:15
3:5:15
3:5:15
5
90
90
6
7
90
90
8
9
90
70
10
11
12
100
120
aThe reaction was run with acetophenone (0.075 mol), 25 mL CH2Cl2, and
9.1 mL SOCl2 (0.125 mol).

C3-SYMMETRICAL BENZENOID COMPOUNDS
3573
Table 2. SOCl2=EtOH-mediated synthesis of 1,3,5-trisubstituted benzenes from aryl
methyl ketonesa, b
Entry
Ar
2
Time (h)
Yieldc (%)
1
2
C6H5
2a
2b
2c
2d
2e
2f
1.5
1.5
1.5
1.5
1.5
3
87
84
p-CH3C6H5
p-ClC6H5
p-BrC6H5
p-IC6H5
3
82
83
4
5
85
35
6
p-NO2C6H5
p-NH2C6H5
p-CH3OC6H5
m-NO2C6H5
7
2g
2h
2i
3
Trace
68
8
3
9
3
Trace
42
47
10
11
12
9-Ethyl-3-carbazolyl
6-tert-Butyl-9-ethyl-3-carbazolyl
9-Ethyl-6-nitro-3-carbazolyl
2j
8
2k
2l
6
8
43
aThe reactions were run with aryl methyl ketone (0.075 mol), 22 mL absolute
ethanol, and 9.1 mL SOCl2 (0.125 mol).
bThe reaction was monitored by thin-layer chromatography (TLC).
cIsolated yields.
electronic effect. Recently, Hu and Zhang separately employed the thionyl chloride
in this condensation reaction, and the substrates containing strong electron-donating
group (–NO2) delivered poor yield.[21] Zhang reasoned that chalcone formed from
4-nitroacetophenone was insoluble in anhydrous ethanol and further stopped the
condensation. Indeed, the solubility of the reactant or intermediates is an important
role in the organic reaction; however, this type of condensation reaction may be
more similar to benzoin condensation reaction, and the electronic effect and steric
effect are probably the most important factors. In a previous report,[17] Elmorsy
Scheme 4. Possible mechanism.

3574
S. ZHAO ET AL.
et al. introduced a facile procedure to induce mixed condensation of aryl methyl ketones
with the aid of a tetrachlorosilane–ethanol system, and the reaction of 4-nitroacetophe-
none with acetophenone carried out in pure ethanol afforded the adduct
1-(4-nitrophenyl)-3,5-diphenylbenzene in 85% yield. The result showed that the solu-
bility of 4-nitroacetophenone in ethanol is not the key factor for this type of reaction.
To explore the scope of this reaction, some other heterocyclic compounds con-
taining carbazol units were employed in this reaction (Table 2, entries 11 and 12). To
our knowledge, these substrates play an important role in the field of luminescence
materials and never have been synthesized by this type of reaction. Interestingly,
when 1-(6-tert-butyl-9-ethylcarbazol-3-yl)-ethanone and 1-(9-ethyl-6-nitrocarbazol-
3-yl)-ethanone were used as starting materials, two novel heterocyclic 1,3,5-trisubsti-
tuted benzenes were formed in 47% and 43% yields (Table 2, entries 11 and 12).
A plausible mechanism for the formation of 1,3,5-trisubstituted benzene in the
presence of SOCl2=EtOH is depicted in Scheme 4. First, the aryl methyl ketone,
SOCl2, and EtOH would react to form chlorosulfite ester (a), and subsequent loss
of SO2[22] and HCl from the chlorosulfite ester (a) led to the formation of ethyl enol
ether (b). Then, 1,3,5-triaryl-1,3,5-triethoxy-cyclohexane was formed through cycli-
zation of three monomers (enol ether form). Finally, in the presence of HCl,
1,3,5-triarylbene was given by aromatization via elimination of three ethanol species.
CONCLUSIONS
In summary, we have developed an efficient SOCl2=EtOH-mediated trisannula-
tion and further aromatization of aryl methyl ketones, leading to 1,3,5-trisubstituted
benzenes under simple and experimental conditions. Some novel C3-symmetrical
molecules containing cabazole units were synthesized from easily available starting
materials via this practical synthetic procedure. As can be seen from the described
results, these reactions provide convenient and more efficient methods to prepare
highly branched molecules, and novel synthetic pathways have been elaborated.
EXPERIMENTAL
All chemical reagents were obtained from commercial suppliers and used without
further purification. Melting points were measured on a WRS-1B digital melting-point
meter and are uncorrected. The IR spectra were determined on an FTIR-8400 spec-
1
trometer by dispersing samples in KBr disks. H NMR and 13C NMR spectra were
measured on a DRX300 NMR spectrometer, Bruker ARX400 spectrometer, and Bru-
ker Avance 500-MHz spectrometer using tetramethylsilane (TMS) as an internal stan-
dard in CDCl3 or dimethylsulfoxide (DMSO-d6). Electron impact (EI)–MS were
determined with an Agilent 5975N mass spectrometer. The elemental analysis was per-
formed at the Institute of Chemistry, Chinese Academy of Sciences. Flash column
chromatography was performed using silica gel (300–400 mesh).
Synthesis of 1,3,5-Trisubstituted Benzenes 2a–l
To a 100-mL, two-necked, round-bottom bottle, 0.075 mol of aryl methyl
ketone and 22 mL of absolute ethanol were added. With vigorous stirring, 9.1 mL

C3-SYMMETRICAL BENZENOID COMPOUNDS
3575
(0.125 mol) of SOCl2 was added in a dropwise way over a period of about 30–40 min,
and then the reaction mixture was stirred, gently refluxed, and determined by TLC.
After completion of the reaction, the reaction mixture was neutralized by saturated
Na2CO3. The precipitate was collected by filtration, washed with 30 mL H2O and
30 mL ethanol, and dried in vacuum to yield the almost pure product. The products
2j, 2k, and 2l (Table 2, entries 10, 11, and 12) were further purified by column chro-
matography (PE=EA ¼ 8:1).
1,3,5-Triphenylbenzene (2a)
1
Light yellow solid; mp 172.3–172.8 ꢁC (lit.[11b] 172 ꢁC). H NMR (500 MHz,
CDCl3): d ¼ 7.71 (s, 3H), 7.63 (d, J ¼ 8.0 Hz, 6H), 7.42–7.39 (t, J ¼ 7.65 Hz, 6H),
7.33–7.30 (t, J ¼ 7.35 Hz, 3H).
1,3,5-Tri(4-methylphenyl)benzene (2b)
1
Light yellow solid; mp 177.1–178.4 ꢁC (lit.[8b] 178 ꢁC). H NMR (500 MHz,
CDCl3): d ¼ 7.73 (s, 3H), 7.62 (d, J ¼ 8.0 Hz, 6H), 7.28–7.30 (d, J ¼ 8.0 Hz, 6H),
2.44 (s, 9H).
1,3,5-Tri(4-chlorophenyl)benzene (2c)
1
Light yellow solid; mp 245.8–246.4 ꢁC (lit.[8b] 246 ꢁC). H NMR (500 MHz,
CDCl3): d ¼ 7.70 (s, 3H), 7.61 (d, J ¼ 8.5 Hz, 6H), 7.44 (d, J ¼ 8.5 Hz, 6H).
1,3,5-Tri(4-bromophenyl)benzene (2d)
Light yellow solid; mp 261.7–262.5 ꢁC (lit.[12] 260–261 ꢁC). 1H NMR (500 MHz,
CDCl3): d ¼ 7.61 (s, 3H), 7.53 (d, J ¼ 8.55 Hz, 6H), 7.45 (d, J ¼ 8.55 Hz, 6H).
1,3,5-Tri(4-iodophenyl)benzene (2e)
1
White solid; mp 265.1–265.7 ꢁC (lit.[11a] 265 ꢁC). H NMR (400 MHz, CDCl3):
d ¼ 7.83 (d, J ¼ 8.00 Hz, 6H), 7.71 (s, 3H), 7.42 (d, J ¼ 8.00 Hz, 6H). 13C NMR
(CDCl3, 100 MHz): d ¼ 141.6, 140.2, 138.0, 129.1, 124.9, 93.6.
1,3,5-Tri(4-nitrophenyl)benzene (2f)
1
Light yellow solid; mp 152.7–153.5 ꢁC (lit.[8b] 153 ꢁC). H NMR (300 MHz,
CDCl3): d ¼ 8.3 (d, J ¼ 9 Hz, 2H), 8.1 (d, J ¼ 9 Hz, 2H), 7.71 (s, 3H).
1,3,5-Tri(4-methoxyphenyl)benzene (2h)
1
Light yellow solid; mp 144.2–144.7 ꢁC (lit.[8b] 143 ꢁC). H NMR (300 MHz,
CDCl3): d ¼ 7.65 (s, 3H), 7.62 (d, J ¼ 9.0 Hz, 6H), 6.99 (d, J ¼ 9 Hz, 6H), 3.85 (s, 9H).

3576
S. ZHAO ET AL.
1,3,5-Tri(9-ethylcarbazol-3-yl)benzene (2j)
Yellow solid; mp> 300 ꢁC. 1H NMR (400MHz, DMSO-d6): d ¼ 8.80 (s, 3H), 8.36
(d, J ¼ 7.6 Hz, 3H), 8.17 (s, 3H), 8.08 (t, J ¼ 8.0 Hz, 6H), 7.75 (d, J ¼ 8.0 Hz, 3H), 7.64
(d, J ¼ 8.0Hz, 3H), 4.62 (d, J ¼ 6.8 Hz, 6H), 7.51–7.47 (t, J ¼ 7.6 Hz, 3H), 7.29–7.22 (m,
3H), 4.50 (t, J ¼ 6.8 Hz, 6H), 1.37 (t, J ¼ 6.8 Hz, 6H). 13C NMR (100MHz, DMSO-d6):
d ¼ 142.44, 140.03, 138.22, 131.58, 125.87, 125.22, 123.58, 122.90, 122.49, 120.85,
119.04, 109.40, 99.48, 79.14, 37.06, 13.70. EI-MS: m=z ¼ 658(Mþ).
1,3,5-Tri(6-tert-butyl-9-ethylcarbazol-3-yl)benzene (2k)
Yellow solid; mp 232.4–233.7 ꢁC. 1H NMR (500 MHz, DMSO-d6): d ¼ 8.75 (s,
3H), 8.30 (s, 3H), 8.04 (s, 3H), 7.93 (d, J ¼ 8.5 Hz, 3H), 7.42 (m, 6H), 4.34 (d,
J ¼ 6.8 Hz, 6H), 1.36–1.24 (m, 12H). 13C NMR (CDCl3, 75 MHz): d ¼ 143.22,
141.95, 139.86, 138.60, 132.39, 124.59, 122.78, 119.09, 116.69, 108.60, 108.08,
37.64, 34.68, 32.03, 13.93. EI-MS: m=z ¼ 826(Mþ).
1,3,5-Tri(9-ethyl-6-nitrocarbazol-3-yl)benzene (2l)
Yellow solid; mp 280.9–281.4 ꢁC. 1H NMR (400 MHz, DMSO-d6): d ¼ 9.40 (s,
3H), 9.10 (s, 3H), 8.39 (d, J ¼ 9.2 Hz, 3H), 8.25 (d, J ¼ 7.2 Hz, 6H), 7.92 (d,
J ¼ 8.4 Hz, 3H), 7.86 (d, J ¼ 9.2 Hz, 3H), 4.62 (d, J ¼ 6.8 Hz, 6H), 1.41 (m, 9H);
13C NMR (100 MHz, DMSO-d6): d ¼ 143.78, 142.39, 141.07, 133.69, 127.40,
124.54, 123.52, 122.81, 121.94, 120.69, 118.36, 111.09, 110.04, 99.98, 38.54, 14.39.
MS EI-MS: no signal. Anal. calcd. for C48H36N6O6: C, 72.72; H, 4.58; N, 10.60.
Found: C, 72.64; H, 4.61; N, 10.72.
ACKNOWLEDGMENTS
We gratefully acknowledge financial support from the Higher School Science and
Technology Development Project of Shanxi Province Education Department (No.
2010124), the Higher School Students Science and Technology Innovation Project of
Shanxi Province ([2011]11, No. 2011332), and the Project of Xinzhou Teachers
University ([2011]52).
REFERENCES
1. (a) Sakurai, H.; Daiko, T.; Hirao, T. A Synthesis of sumanene, a fullerene fragment.
Science 2003, 301, 1878; (b) Sakurai, H.; Daiko, T.; Sakane, H.; Amaya, T.; Hirao, T.
Structural elucidation of sumanene and generation of its benzylic anions. J. Am. Chem.
Soc. 2005, 127, 11580; (c) Higashibayashi, S.; Sakurai, H. Asymmetric synthesis of a chiral
buckybowl, trimethylsumanene. J. Am. Chem. Soc. 2008, 130, 8592; (d) Wei, J.; Jia, X.;
Yu, J.; Shi, X.; Zhang, C.; Chen Z. Synthesis of 1,4,5,8,9,12-hexabromododecahydrotri-
phenylene and its application in constructing polycyclic thioaromatics. Chem. Commun.
2009, 4714.
2. (a) Wang, J.-L.; Zhou, Y.; Li, Y.; Pei, J. Solution-processable gradient red-emitting p-con-
jugated dendrimers based on benzothiadiazole as core: Synthesis, characterization, and

C3-SYMMETRICAL BENZENOID COMPOUNDS
3577
device performances. J. Org. Chem. 2009, 74, 7449; (b) Kotha, S.; Kashinath, D.; Kumar,
S. Synthesis of liquid crystalline materials based on 1,3,5-triphenylbenzene and 2,4,6-
triphenyl-1,3,5-s-triazine. Tetrahedron Lett. 2008, 49, 5419; (c) Wanunu, M.; Vaskevich,
A.; Shanzer, A.; Rubinstein, I. Divergent growth of coordination dendrimers on surfaces.
J. Am. Chem. Soc. 2006, 128, 8341; (d) Cao, X.-Y.; Liu, X.-H.; Zhou, X.-H.; Zhang, Y.;
Jiang, Y.; Cao, Y.; Cui, Y.-X.; Pei, J. Giant extended p-conjugated dendrimers containing
the 10,15-dihydro-5H-diindeno[1, 2-a; 10,20-c]fluorene chromophore: Synthesis, NMR
behaviors, optical properties, and electroluminescence. J. Org. Chem. 2004, 69, 6050.
3. Kanibolotsky, A. L.; Berridge, R.; Skabara, P. J.; Perepichka, I. F.; Bradley, D. D. C.;
Koeberg, M. Synthesis and properties of monodisperse oligofluorene-functionalized trux-
enes: Highly fluorescent star-shaped architectures. J. Am. Chem. Soc. 2004, 126, 13695.
4. (a) Wu, Y.-T.; Siegel, J. S. Aromatic molecular-bowl hydrocarbons: Synthetic derivatives,
their structures, and physical properties. Chem. Rev. 2006, 106, 4843; (b) Tsefrikas, V. M.;
Scott, L. T. Geodesic polyarenes by flash vacuum pyrolysis. Chem. Rev. 2006, 106, 4868;
(c) Abe, H.; Aoyagi, Y.; Inouye, M. A rigid C3v-symmetrical host for saccharide recog-
nition: 1,3,5-Tris (2-hydroxyaryl)-2,4,6-trimethylbenzenes. Org. Lett. 2005, 7, 59.
5. (a) Kabdulov, M. A.; Amsharov, K. Y.; Jansen, M. A step toward direct fullerene synthesis:
C60 fullerene precursors with fluorine in key positions. Tetrahedron 2010, 66, 8587; (b) Pang,
J.; Marcotte, E. J.-P.; Seward, C.; Brown, R. S.; Wang, S. N. A blue luminescent star-shaped
Zn complex that can detect benzene. Angew. Chem., Int. Ed. 2001, 40, 4042.
6. (a) Teske, J. A.; Deiters, A. Microwave-mediated nickel-catalyzed cyclotrimerization
reactions: Total synthesis of illudinine. J. Org. Chem. 2008, 73, 342; (b) Yoshida, K.;
Morimoto, I.; Mitsudo, K.; Tanaka, H. RhCl3=amine-catalyzed [2 þ 2 þ 2] cyclization of
alkynes. Tetrahedron 2008, 64, 5800; (c) Grigg, R.; Scott, R.; Stevenson, P. Rhodium-catalysed
[2þ 2 þ 2] cycloadditions of acetylenes. Tetrahedron Lett. 1982, 23, 2691; (d) Li, J.; Jiang, H.;
Chen, M. CuCl2-induced regiospecifical synthesis of benzene derivatives in the
palladium-catalyzed cyclotrimerization of alkynes. J. Org. Chem. 2001, 66, 3627; (e) Jhingan,
A. K.; Maier, W. F. Homogeneous catalysis with a heterogeneous palladium catalyst: An
effective method for the cyclotrimerization of alkynes. J. Org. Chem. 1987, 52, 1161.
7. For selected examples of cross-coupling, see (a) Yoshikai, N.; Matsuda, H.; Nakamura, E.
Hydroxyphosphine ligand for nickel-catalyzed cross-coupling through nickel=magnesium
bimetallic cooperation. J. Am. Chem. Soc. 2009, 131, 9590; (b) Cornacchio, A. L. P.; Price,
J. T.; Jennings, M. C.; McDonald, R.; Staroverov, V. N.; Jones, N. D. Meta-substituted
thienyl benzenes: A comparative synthetic, structural, and computational study. J. Org.
Chem. 2009, 74, 530; (c) Bai, L.; Wang, J.-X. Reusable, polymer-supported,
palladium-catalyzed, atom-efficient coupling reaction of aryl halides with sodium tetra-
phenylborate in water by focused microwave irradiation. Adv. Synth. Catal. 2008, 350,
315; (d) Bonvallet, P. A.; Breitkreuz, C. J.; Kim, Y. S.; Todd, E. M.; Traynor, K.; Fry,
C. G.; Ediger, M. D.; McMahon, R. J. Organic glass-forming materials: 1,3,5-
Tris(naphthyl)benzene derivatives. J. Org. Chem. 2007, 72, 10051.
8. (a) Dehmlow, E. V.; Kelle, T. Synthesis of new truxene derivatives: Possible precursors of
fullerene partial structures? Synth. Commun. 1997, 27, 2021; (b) Lyle, R. E.; DeWitt, E. J.;
Nichols, N. M.; Cleland, W. Acid-catalyzed condensations, I: 1,3,5-triarylbenzenes. J.
Am. Chem. Soc. 1953, 75, 5959.
9. Sampey, J. R. Sym-tritolylbenzene. J. Am. Chem. Soc. 1940, 62, 1953.
10. Clapp, D.; Morton, A. The condensation of certain aromatic methyl ketones. J. Am.
Chem. Soc. 1936, 58, 2172.
11. (a) Zhao, Y.; Li, J.; Li, C.; Yin, K.; Yea, D.; Jia, X. PTSA-catalyzed green synthesis of
1,3,5-triarylbenzene under solvent-free conditions. Green Chem. 2010, 12, 1370; (b) Jing,
X.; Xu, F.; Zhu, Q. Novel method for the synthesis of 1,3,5-triarylbenzenes from ketones.

3578
S. ZHAO ET AL.
Synth. Commun. 2005, 35, 3167; (c) Jing, X.; Xu, F.; Zhu, Q.; Yang, J. Process for
preparation of 1,3,5-triphenylbenzene. CN Patent 1837168, 2006; (d) Jing, X.; Xu, F.;
Zhu, Q.; Ren, X.; Li, D.; Yan, C.; Shi, Y. New method for the synthesis of 1,3,5-triaryl-
benzenes. Indian J. Chem. 2006, 45B, 2781.
12. Kumar, A.; Dixit, M.; Singh, S. P.; Raghunandan, R.; Maulik, P. R.; Goel, A. Reusable
resin amberlyst 15–catalyzed new convenient protocol for accessing arylated benzene
scaffolds. Tetrahedron Lett. 2009, 50, 4335.
13. (a) Li, Z.; Sun, W.-H.; Jin, X.; Shao, C. Triple self-condensation of ketones yielding
aromatics promoted with titanium tetrachloride. Synlett 2001, 1947; (b) Iranpoor, N.;
Zeynizaded, B. TiCl3(OTf) catalyses the efficient conversion of acetophenones to
1,3,5-triaryl benzenes. Synlett 1998, 1079; (c) Volz, H.; Lecea, M. J. V. 1,3,5-Tris-
(diphenyl-hexachloroantimonylmethyl)-benzol, ein stabiles tricarboniumion. Tetrahedron
Lett. 1966, 7, 4683; (d) Ono, F.; Ishikura, Y.; Tada, Y.; Endo, M.; Sato, T. Efficient
conversion of acetophenones into 1,3,5-triarylbenzenes catalyzed by bismuth(III) trifluor-
omethanesulfonate tetrahydrate. Synlett 2008, 2365.
14. (a) Elmorsy, S. S.; Pelter, A.; Smith, K.; Hursthouse, M. B.; Ando, D. Investigations of
the tetrachlorosilane-ethanol-induced self-condensations of ketones. Tetrahedron Lett.
1992, 33, 821; (b) Elmorsy, S. S.; Pelter, A.; Smith, K. The direct production of tri- and
hexa-substituted benzenes from ketones under mild conditions. Tetrahedron Lett. 1991,
32, 4175; (c) Elmorsy, S. S.; Khalil, A. G. M.; Girges, M. M.; Salama, T. A. A new
approach to the stereoselective synthesis of methylchalcones. J. Chem. Res., Synth.
1997, 7, 232; (d) Dash, B. P.; Satapathy, R.; Gaillard, E. R.; Maguire, J. A.; Hosmane,
N. S. Synthesis and properties of carborane-appended C3-symmetrical extended p sys-
tems. J. Am. Chem. Soc. 2010, 132, 6578.
15. (a) Cheng, K. J.; Ding, Z. B.; Wu, S. H. A facile synthesis of 1,3,5-triaryl benzenes from
acetophenone diethyl ketals in the presence of acetyl chloride and SmCl3. Synth. Commun.
1997, 27, 11; (b) Cheng, K. J.; Wu, S. H. The reaction of acetophenone diethyl ketals and
acetyl chloride promoted by lanthanide trichlorides: A novel method for the synthesis of
1,3,5-triarybenzenes. Acta Chim. Sinica 1999, 57, 1162.
16. Mahmoodi, N. O.; Hajati, N. Trisannelated benzene synthesis by copper (II) chloride. J.
Chin. Chem. Soc. 2002, 49, 91.
17. Elmorsy, S. S.; Khalil, A. G. M.; Girges, M. M.; Salama, T. A. New routes for synthesis of
branched functionalized benzenoid compounds by using tetrachlorosilane–ethanol
reagent. Tetrahedron Lett. 1997, 38, 1071.
18. (a) Shirai, H.; Amano, N.; Hashimoto, Y.; Fukui, E.; Ishii, Y.; Ogawa, M. Trisannelated
benzene synthesis by zirconium halide–catalyzed cyclodehydration of cycloalkanones. J.
Org. Chem. 1991, 56, 2253; (b) Wei, J.; Gao, Y.; Ma, X.; Jia, X.; Shi, X.; Chen, Z. A novel
class of
C3d-symmetrical molecules synthesized by a six-fold substitution from
1,4,5,8,9,12-hexabromododecahydrotriphenylene. Chem. Commun. 2010, 46, 3738.
19. Whitmore, F. C.; Karnatz, F. A.; Popkin, A. H. Isomerization during the preparation of
n-amyl chloride. J. Am. Chem. Soc. 1938, 60, 2540.
20. Chmielewski, M. J.; Charon, M. Jurczak, J. 1,8-Diamino-3,6-dichlorocarbazole: A
promising building block for anion receptors. Org. Lett. 2004, 6, 3501
21. (a) Hu, Z.-G.; Liu, J.; Li, G. A.; Dong, Z. B. Synthesis of symmetric 1,3,5-triarylbenzenes.
J. Chem. Res., Synth. 2003, 12, 778; (b) Hu, Z.; Liu, J.; Dong, Z.; Li, W. Simple and
convenient synthesis of 1,3,5-triphenylbenzene. Huaxue Tongbao 2004, 67, 700; (c) Hu,
Z.-G.; Liu, J.; Li, W.; Dong, Z. B. Preparation of functional 1,3,5-triarylbenzene. Huaxue
Shiji 2004, 26, 351; (d) Hu, H.; Zhang, A.; Ding, L.; Lei, X.; Zhang, L. Simple and
convenient synthesis of 1,3,5-triarylbenzenes from ketones. J. Chem. Res. 2007, 12, 720.
22. SO2 formed in the reaction was detected by fuchsin solution.