Metal-free and solvent-free synthesis of: M -terphenyls through tandem cyclocondensation of aryl methyl ketones with triethyl orthoformate

Article abstract of DOI:10.1039/d0ra00578a

Reported here is a novel cyclocondensation of aryl methyl ketones and triethyl orthoformate for the simple synthesis of m-terphenyls. In the presence of a catalytic amount of TfOH, alkyl- and chloro-substituted acetophenones produced a series of terphenyls through a tandem reaction which merged six steps into a one-pot procedure. Moreover, the corresponding ester products were obtained when using other substituted acetophenones as the starting materials under the same reaction conditions.

Full text of DOI:10.1039/d0ra00578a

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Metal-free and solvent-free synthesis of m-
terphenyls through tandem cyclocondensation of
Cite this: RSC Adv., 2020, 10, 12113
aryl methyl ketones with triethyl orthoformate†
*
Xiaoqin Xiao, Juan Luo, Zongjie Gan, Wengao Jiang and Qiang Tang
Reported here is a novel cyclocondensation of aryl methyl ketones and triethyl orthoformate for the simple
synthesis of m-terphenyls. In the presence of a catalytic amount of TfOH, alkyl- and chloro-substituted
acetophenones produced a series of terphenyls through a tandem reaction which merged six steps into
a one-pot procedure. Moreover, the corresponding ester products were obtained when using other
substituted acetophenones as the starting materials under the same reaction conditions.
Received 19th January 2020
Accepted 18th March 2020
DOI: 10.1039/d0ra00578a
rsc.li/rsc-advances
Through an extensive literature research, we found that
diverse compounds have been reported as the main product for
Introduction
the reaction of aryl ketones and triethyl orthoformate in the
presence of acid under only slightly different conditions
(Scheme 2). Open-chain carboxonium ions 4 were obtained
when using an equivalent of HClO4 or HBF4.9 However, cyclic
carboxonium ions (i.e. pyryliums 5) were produced under
similar reaction conditions.10 Based on their strong uores-
cence and high conductivity, carboxonium ions have been
frequently employed as functional pigments, phototherapeutic
agents and nonlinear optical glasses. Generally, when using
trialkyl orthoformates for acetalization of carbonyl compounds
in the presence of a catalytic amount of Lewis or Brønsted acid,
both ketones and aldehydes could be transformed to their
corresponding acetals 6 with excellent yields.11 With the aid of
microwave and a catalytic amount of boron triuoride, three
equivalents of aryl ketones condensed with one equivalent of
triethyl orthoformate to afford the product 7 in moderate
yields.12 Herein, we surprisingly found that an abnormal
tandem cyclocondensation took place under strong acid and an
elevated temperature conditions to furnish m-terphenyls 3 as its
main product.
Owing to the amazing photophysical and optical properties, m-
terphenyls have been extensively applied in materials science,
for example in conducting polymers, OLEDs, laser dyes, textile
dye carriers, heat storage and transfer agents.1 In addition,
terphenyl scaffolds have also been found in several naturally
occurring compounds with interesting biological properties,
like dictyoterphenyl A, trifucol, dunnialol, etc.2
The simplest m-terphenyl, 1,3-diphenylbenzene, can be
synthesized by the addition of the Grignard agent to 1,3-cyclo-
hexanedione (Scheme 1, route a).3 To date, various methods
have been reported to construct m-terphenyl frameworks.4
Among these methods, the transition metal-catalyzed coupling
reactions have been the most widely used approaches, espe-
cially Suzuki–Miyaura cross-coupling reactions (Scheme 1,
route b).5 Another traditional and superior strategy is benzan-
nulation which can directly assemble acyclic precursors into
benzene derivatives.6 Various efficient benzannulation methods
have been used to construct the terphenyl derivatives7 (Scheme
1, route c). However, these methods are generally associated
with various drawbacks, which include harsh reaction condi-
tions, expensive metal catalysts, limited substrate scope, and
poor chemo- or regioselectivity. Thus, there is still a great
demand to develop simple, efficient and regioselective methods
for the synthesis of m-terphenyls. Herein, we report a novel
approach for the facile synthesis of m-terphenyls through
cyclocondensation reaction of aryl methyl ketones and triethyl
orthoformate.8
College of Pharmacy, Center for Lab Teaching and Management, Chongqing Research
Center for Pharmaceutical Engineering, Chongqing Medical University, No.
Yixueyuan Road, Chongqing 400016, P. R. China. E-mail: tangqiang@cqmu.edu.cn
1
† Electronic supplementary information (ESI) available. See DOI:
Scheme 1 Three types of synthetic strategy to m-terphenyls.
RSC Adv., 2020, 10, 12113–12118 | 12113
10.1039/d0ra00578a
This journal is © The Royal Society of Chemistry 2020

View Article Online
RSC Advances
Paper
Table 1 Optimization of reaction conditionsa
Results and discussion
In order to develop an efficient approach to m-terphenyls, ace-
tophenone (1a) and triethyl orthoformate (2) were selected as
model substrates (Table 1). When we chose three equivalents of
triuoroacetic acid (CF3COOH) as catalyst, the reaction pro-
ceeded smoothly at 50 ꢀC to furnish a moderate yield of 1,3-
diphenylbenzene (3a) (Entry 3). A lower temperature would
dramatically reduce the yield of 3a and benet the formation of
carboxonium ions (4 or 5) (Entries 1 and 2), while the self-
condensation of 1a would be accelerate to generate the
byproduct 1,3,5-triphenylbenzen (8a) at a higher temperature,13
thus nally decreased the yield of the desired product (Entry 4).
The choice of acids was of considerable importance in this
cyclocondensation reaction. In fact, there was a low or no yield
of 3a when inorganic acids or weak organic acids were employed
(Entries 5–7), and an excess amount of the acid was necessary to
guarantee the formation of the desired product (Entries 3 and
8–10). While using strong organic acids, the cyclocondensation
reaction with only one equivalent of the acid could produce 3a
Entry Acid
Solvent
T (ꢀC) Time (h) 3ab (%)
1
CF3COOH (3.0 eq.)
Neat
Neat
Neat
Neat
0
24
24
2
0
2
3
4
CF3COOH (3.0 eq.)
CF3COOH (3.0 eq.)
CF3COOH (3.0 eq.)
25
50
100
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
<10
54
42
0
1
5
6
CH3COOH (3.0 eq.) Neat
—
24
24
24
2
2
2
2
2
2
2
2
2
2
2
2
2
c
Neat
Neat
Neat
Neat
Neat
Neat
Neat
Neat
Neat
Neat
Neat
Neat
Neat
Neat
EtOH
NAd
0
7
8
9
10
11
12
13
14
con. HCl (3.0 eq.)
HClO4 (3.0 eq.)
HClO4 (1.0 eq.)
CF3COOH (1.0 eq.)
TsOH (3.0 eq.)
TsOH (1.0 eq.)
TfOH (3.0 eq.)
TfOH (2.0 eq.)
TfOH (1.0 eq.)
TfOH (0.2 eq.)
TfOH (0.02 eq.)
TfOH (0.2 eq)e
TfOH (0.2 eq.)f
TfOH (0.2 eq.)
TfOH (0.2 eq.)
TfOH (0.2 eq.)
TfOH (0.2 eq.)
23
0
<10
47
56
<10
20
62
81
<10
67
<10
73
46
61
52
in moderate yields (Entries 11–12). We believed that large 15
amount of acid would result in the formation of carboxonium
ions as byproducts. Therefore catalytic amount of a stronger
16
17
18
19
20
organic
acid
was
tested.
We
found
that
tri-
uoromethanesulfonic acid (TfOH, 0.2 eq.) led to much cleaner
reaction, and nally gave the best yields (Entries 13–17). 21
Surprisingly, we found that the best molar ratio between ace-
tophenone and orthoformate is 1 : 4 which is contradicted with
what is dictated by the reaction equation. When reducing the
amount of triethyl orthoformate, the yield of 3a was dramati-
cally decreased (Entries 18–19). Moreover, the reactions with
different solvents were also examined (Entries 20–23), and yet
both the reaction cleanness and the yields were not better than
those obtained without any solvent.
With an optimal set of catalysis conditions selected, we were
then poised to test the tandem cyclocondensation process and
evaluate the substrate scope. When the reaction was conducted
at 50 ꢀC in the presence of a catalytic amount of TfOH, we were
Toluene 50
THF
DCM
2
22
23
50
50
2
2
a
Reagents and conditions: 1a (1.0 mmol), 2 (4.0 mmol). b Isolated yield.
Without acid. d The starting materials were remained. e 2 (2.0 mmol).
2 (1.0 mmol).
c
f
delighted to discover that different alkyl substituted acetophe-
nones functioned efficiently in the reactions with triethyl
orthoformate (Table 2, 1a–1j). Chloro-substituted acetophe-
nones were also effective regardless of the para- or meta-position
on the phenyl ring (Table 2, 1k and 1l). Additionally, simple 2-
acetonaphthone was also reacted smoothly to produce 1,3-
dinaphthylbenzene in a moderate yield (Table 2, entry 13). It
was found that this tandem cyclocondensation reaction was
very sensitive to electronic factors as well as steric ones. In fact,
most acetophenones with electron donating or withdrawing
groups failed to give the desired terphenyl products.
It was conceived that there should be a complicated reaction
pathway for the formation of the desired m-terphenyls from aryl
methylketones and orthoformate (Scheme 3). And we believed
that the departure of a benzoyl ion V from the intermediate III
should be the key step.14 Therefore it is reasonable that an ester
product should be produced in this type of reaction.15 To our
delight, both terphenyl 3n and ester 9n were obtained for the
reaction of para-methoxyacetophenone 1n (Table 2, entry 14).
On the basis of our results and the related literatures,
a tentative mechanism for the reaction between acetophenone
(1a) and triethyl orthoformate under strong acidic conditions is
proposed in Scheme 3. Triethyl orthoformate is substituted by
Scheme 2 Various products for the reaction of aryl ketones with
triethyl orthoformate.
12114 | RSC Adv., 2020, 10, 12113–12118
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
Table 2 Synthesis of m-teraryls from aryl methyl ketones and triethyl
orthoformatea
Entry
1
Ketone 1
Product 3
Yieldb (%)
81
2
3
73
84
Scheme 3 Proposed mechanism.
4
75
82
69
78
79
75
71
68
two folds of 3a to form an intermediate I, which either
undergoes further substitution reaction to produce
a
5
compound 7a, or removes of an ethanol molecule to obtain the
intermediate II. There are also two pathways for the interme-
diate II to provide a self-condensed cation 5a and another
intermediate III respectively. Under the action of strong acid,
the intermediate III is cleaved to provide a benzoyl ion V and an
intermediate IV.14a The cation V is an active intermediate which
can easily react either with ethanol to provide the ester 9a, or
with other intermediates to form complex byproducts. While
the intermediate IV nally goes through an self-condensation
reaction to furnish the terphenyl product 3a. In addition,
there may be another proposal to explain the reaction mecha-
nism. The intermediate III proceeds directly through cyclo-
condensation and benzannulation to afford [1,10:30,100-
terphenyl]-20-yl(phenyl)methanone or [1,10:30,100-terphenyl]-40-
yl(phenyl)methanone intermediate, which undergoes decom-
position by nucleophiles to generate the nal product 3a and
the byproduct 9a.
6
7
8
9
10
11
Conclusions
In summary, a cascade cyclocondensation reaction merged six
steps into one-pot procedure has been disclosed. This reaction
demonstrates a new protocol for the synthesis of m-terphenyls
from simple starting materials without any metal catalysts and
solvents.
12
13
74
67
23
Experimental section
General information
Nuclear magnetic resonance spectra (1H and 13C) were recorded
on 600 MHz spectrometers with tetramethylsilane (TMS) as an
internal standard. The splitting patterns are designated as
singlet (s), doublet (d), triplet (t), quartet (q), dd (doublet of
doublets); m (multiplets), and etc. All rst-order splitting
14
a
Reagents and conditions: 1 (1.0 mmol), 2 (4.0 mmol), and TfOH (0.1
mmol). b Isolated yield.
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 12113–12118 | 12115

View Article Online
RSC Advances
Paper
4,400-Dipropyl-1,10:30,100-terphenyl (3e).18 The title compound
was obtained as white solid, 82% yield, mp: 71–72 C, and the
patterns were assigned on the basis of the appearance of the
multiplet. Splitting patterns that could not be easily interpreted
are designated as multiplet (m) or broad (br). High resolution
mass spectral analysis (HRMS) was performed on ESI-QTOP
mass spectrometer. Purication was done by column chroma-
tography and preparative TLC using silica gel. TLC analyses
were performed on commercial glass plates bearing a 0.25 mm
layer of silica gel GF254. Visualization was performed using a UV
lamp or chemical stains like KMnO4 and I2. Commercially
available materials were used as received.
ꢀ
analytical data are consistent with those in the literature. 1H
NMR (600 MHz, cdcl3) d 7.82 (s, 1H), 7.58 (dd, J ¼ 13.5, 7.7 Hz,
6H), 7.55–7.43 (m, 1H), 7.29 (d, J ¼ 7.9 Hz, 4H), 2.67 (t, J ¼
7.7 Hz, 4H), 1.72 (dd, J ¼ 15.1, 7.5 Hz, 4H), 1.01 (t, J ¼ 7.3 Hz,
6H); 13C NMR (151 MHz, CDCl3) d 141.96, 141.66, 138.61,
129.06, 128.90, 127.06, 125.84, 125.68, 37.71, 24.58, 13.90.
4,400-Diisopropyl-1,10:30,100-terphenyl
(3f).
The
title
compound was obtained as white solid, 69% yield, mp: 99–
100 ꢀC. 1H NMR (600 MHz, CDCl3) d 7.79 (d, J ¼ 1.6 Hz, 1H), 7.58
(d, J ¼ 8.2 Hz, 4H), 7.56–7.52 (m, 2H), 7.48 (dd, J ¼ 8.2, 6.9 Hz,
1H), 7.33 (d, J ¼ 8.1 Hz, 4H), 2.97 (dt, J ¼ 13.8, 6.9 Hz, 2H), 1.31
(d, J ¼ 6.9 Hz, 12H); 13C NMR (151 MHz, CDCl3) d 148.16,
141.71, 138.84, 129.12, 127.23, 126.94, 125.95, 125.79, 33.88,
24.09; HRMS (ESI) calcd for C18H13 (M + H)+: 229.1012, found:
229.1010.
General procedure for the reaction between phenol and a-
haloketone
To a 25 mL two necked ask under nitrogen atmosphere at
50 ꢀC was added triethyl orthoformate (4.0 mmol) and aceto-
phenones (1.0 mmol). Aer stirring for 0.5 hour, tri-
uoromethanesulfonic acid (0.1 mmol) was added into the
mixture. Aer completion of the reaction (monitored by TLC), it
was quenched with a saturated sodium carbonate (10 mL),
extracted with dichloromethane (3 ꢁ 10 mL) and dried with
anhydrous sodium sulphate. The organic mixture was concen-
trated under reduced pressure, and separated by silica-gel
column chromatography using ethyl acetate–hexane as eluent
in increasing polarity to yield the desired product.
4,400-Dibutyl-1,10:30,100-terphenyl (3g).19 The title compound
ꢀ
was obtained as yellowish solid, 78% yield, mp: 47–48 C, and
the analytical data are consistent with those in the literature. 1H
NMR (600 MHz, CDCl3) d 7.81 (d, J ¼ 1.4 Hz, 1H), 7.62–7.53 (m,
6H), 7.52–7.44 (m, 1H), 7.29 (d, J ¼ 7.8 Hz, 4H), 2.68 (t, J ¼
7.8 Hz, 4H), 1.74–1.61 (m, 4H), 1.42 (dd, J ¼ 14.9, 7.4 Hz, 4H),
0.97 (t, J ¼ 7.4 Hz, 6H); 13C NMR (151 MHz, CDCl3) d 142.21,
141.70, 138.60, 129.10, 128.89, 127.11, 125.87, 125.71, 35.35,
33.70, 22.46, 14.02.
4,400-Diisobutyl-1,10:30,100-terphenyl (3h). The title compound
was obtained as white solid, 79% yield, mp: 67–68 ꢀC. 1H NMR
(600 MHz, CDCl3) d 7.83 (d, J ¼ 1.5 Hz, 1H), 7.58 (dd, J ¼ 13.9,
4.9 Hz, 6H), 7.55–7.44 (m, 1H), 7.33–7.18 (m, 4H), 2.55 (d, J ¼
7.2 Hz, 4H), 1.94 (dt, J ¼ 13.5, 6.8 Hz, 2H), 0.97 (d, J ¼ 6.6 Hz,
12H); 13C NMR (151 MHz, CDCl3) d 141.68, 141.00, 138.63,
129.60, 129.11, 126.95, 125.86, 125.70, 45.14, 30.31, 22.47;
HRMS (ESI) calcd for C26H31 (M + H)+: 343.2420, found:
343.2425.
4,400-Dipentyl-1,10:30,100-terphenyl (3i).17 The titleꢀcompound
was obtained as white solid, 75% yield, mp: 56–57 C, and the
analytical data are consistent with those in the literature. 1H
NMR (600 MHz, CDCl3) d 7.81 (s, 1H), 7.61–7.53 (m, 6H), 7.49
(dd, J ¼ 8.2, 7.1 Hz, 1H), 7.29 (d, J ¼ 8.0 Hz, 4H), 2.78–2.55 (m,
4H), 1.75–1.64 (m, 4H), 1.47–1.32 (m, 8H), 0.93 (t, J ¼ 6.8 Hz,
6H); 13C NMR (151 MHz, CDCl3) d 142.25, 141.69, 138.60,
129.10, 128.88, 127.11, 125.87, 125.71, 35.64, 31.61, 31.24,
22.61, 14.09.
Characterizations of m-teraryls (Table 2)
1,10:30,100-Terphenyl (3a).16 The title compound was obtained
as white solid, 81% yield, mp: 83–84 ꢀC, and the analytical data
are consistent with those in the literature. H NMR (600 MHz,
1
CDCl3) d 7.83 (t, J ¼ 1.7 Hz, 1H), 7.71–7.63 (m, 4H), 7.60 (dd, J ¼
7.1, 1.6 Hz, 2H), 7.53 (dd, J ¼ 8.3, 7.0 Hz, 1H), 7.48 (dd, J ¼ 10.6,
4.8 Hz, 4H), 7.39 (t, J ¼ 7.4 Hz, 2H); 13C NMR (151 MHz, CDCl3)
d 141.82, 141.22, 129.23, 128.84, 127.44, 127.30, 126.20, 126.17.
4,400-Dimethyl-1,10:30,100-terphenyl (3b).17 The title compound
was obtained as white solid, 73% yield, mp: 125–126 ꢀC, and the
analytical data are consistent with those in the literature. 1H
NMR (600 MHz, CDCl3) d 7.78 (s, 1H), 7.59–7.52 (m, 6H), 7.52–
7.46 (m, 1H), 7.28 (d, J ¼ 7.7 Hz, 4H), 2.42 (s, 6H); 13C NMR (151
MHz, CDCl3) d 141.64, 138.36, 137.15, 129.50, 129.09, 127.09,
125.77, 125.68, 21.12.
3,300-Dimethyl-1,10:30,100-terphenyl (3c).17 The title compound
was obtained as colorless oil, 84% yield, and the analytical data
are consistent with those in the literature. H NMR (600 MHz,
1
3,300,4,400-Tetramethyl-1,10:30,100-terphenyl (3j). The title
compound was obtained as yellowish oil, 71% yield, mp: 57–
58 ꢀC. 1H NMR (600 MHz, CDCl3) d 7.78 (t, J ¼ 1.7 Hz, 1H), 7.56–
7.51 (m, 2H), 7.50–7.46 (m, 1H), 7.44 (s, 2H), 7.40 (dd, J ¼ 7.7,
CDCl3) d 7.82 (s, 1H), 7.59 (d, J ¼ 7.6 Hz, 2H), 7.55–7.45 (m, 5H),
7.38 (t, J ¼ 7.5 Hz, 2H), 7.22 (d, J ¼ 7.4 Hz, 2H), 2.47 (s, 6H); 13
C
NMR (151 MHz, CDCl3) d 141.82, 141.21, 138.36, 129.05, 128.69,
128.11, 128.05, 126.16, 126.04, 124.36, 21.55.
1.8 Hz, 2H), 7.24 (d, J ¼ 7.7 Hz, 2H), 2.36 (s, 6H), 2.33 (s, 6H); 13
C
4,400-Diethyl-1,10:30,100-terphenyl (3d).17 The title compound
was obtained as colorless crystal, 75% yield, mp: 86–87 ꢀC, and
the analytical data are consistent with those in the literature. 1H
NMR (600 MHz, cdcl3) d 7.82 (s, 1H), 7.59 (dd, J ¼ 17.9, 7.6 Hz,
6H), 7.54–7.48 (m, 1H), 7.33 (d, J ¼ 7.9 Hz, 4H), 2.83–2.63 (m,
4H), 1.32 (t, J ¼ 7.6 Hz, 6H); 13C NMR (151 MHz, CDCl3)
d 143.55, 141.71, 138.67, 129.12, 128.36, 127.21, 125.90, 125.75,
28.58, 15.64.
NMR (151 MHz, CDCl3) d 141.73, 138.91, 136.93, 135.79, 130.07,
128.99, 128.53, 125.82, 125.63, 124.60, 19.94, 19.45; HRMS (ESI)
calcd for C22H23 (M + H)+: 287.1794, found: 287.1791.
4,400-Dichloro-1,10:30,100-terphenyl (3k).20 The title compound
was obtained as white solid, 68% yield, mp: 112–113 ꢀC, and the
analytical data are consistent with those in the literature. 1H
NMR (600 MHz, CDCl3) d 7.71 (t, J ¼ 1.5 Hz, 1H), 7.59–7.49 (m,
12116 | RSC Adv., 2020, 10, 12113–12118
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
7H), 7.47–7.40 (m, 4H); HRMS (ESI) calcd for C18H13Cl2 (M +
H)+: 299.0389, found: 299.0388.
Acknowledgements
3,300-Dichloro-1,10:30,100-terphenyl (3l).21 The title compound
was obtained as yellowish oil, 74% yield, and the analytical data
We appreciate nancial support from the Fundamental and
Advanced Research Projects of Chongqing City (No.
cstc2018jcyjA0150).
1
are consistent with those in the literature. H NMR (600 MHz,
CDCl3) d 7.73 (s, 1H), 7.63 (s, 2H), 7.57 (d, J ¼ 6.8 Hz, 2H), 7.53
(dd, J ¼ 10.2, 7.7 Hz, 3H), 7.40 (t, J ¼ 7.8 Hz, 2H), 7.38–7.33 (m,
2H); 13C NMR (151 MHz, CDCl3) d 142.77, 140.58, 134.78,
130.10, 129.50, 127.57, 127.39, 126.65, 126.01, 125.42.
1,3-Di(naphthalen-2-yl)benzene (3m).22 The title compound
was obtained as white solid, 67% yield, mp: 144–145 ꢀC, and the
analytical data are consistent with those in the literature. 1H
NMR (600 MHz, CDCl3) d 8.15 (s, 2H), 8.08 (s, 1H), 7.96 (dd, J ¼
14.4, 8.2 Hz, 4H), 7.91 (d, J ¼ 7.7 Hz, 2H), 7.86 (d, J ¼ 8.4 Hz, 2H),
7.76 (d, J ¼ 7.6 Hz, 2H), 7.62 (t, J ¼ 7.6 Hz, 1H), 7.58–7.48 (m,
4H); 13C NMR (151 MHz, CDCl3) d 141.80, 138.50, 133.69,
132.71, 129.38, 128.51, 128.23, 127.67, 126.64, 126.48, 126.36,
126.02, 125.97, 125.65.
Notes and references
1 (a) C. W. Lee and J. Y. Lee, Org. Electron., 2014, 15, 399–404;
(b) C.-A. Wu, H.-H. Chou, C.-H. Shih, F.-I. Wu, C.-H. Cheng,
H.-L. Huang, T.-C. Chao and M.-R. Tseng, J. Mater. Chem.,
2012, 22, 17792–17799; (c) H. Sasabe, Y. Seino, M. Kimura
and J. Kido, Chem. Mater., 2012, 24, 1404–1406; (d) L. Fan,
Y. Zhang, J. Wang, L. Zhao, X. Wang, T. Hu and X. Zhang,
J. Solid State Chem., 2018, 260, 46–51.
2 (a) H. Kikuchi, Y. Matsuo, Y. Katou, Y. Kubohara and
Y. Oshima, Tetrahedron, 2012, 68, 8884–8889; (b)
A. Thirunarayanan, S. Raja, G. Mohanraj and
P. Rajakumar, RSC Adv., 2014, 4, 41778–41783; (c) W. Yan,
Wuringege, S.-J. Li, Z.-K. Guo, W.-J. Zhang, W. Wei,
R.-X. Tan and R.-H. Jiao, Bioorg. Med. Chem. Lett., 2017, 27,
51–54; (d) S.-M. Wang, J.-J. Han, K. Ma, T. Jin, L. Bao,
Y.-F. Pei and H.-W. Liu, Fitoterapia, 2014, 98, 149–155; (e)
K.-W. Glombitza, H.-W. Rauwald and G. Eckhardt,
Phytochemistry, 1975, 14, 1403–1405; (f) I. Kouno,
T. Morisaki, Y. Hara and C.-S. Yang, Chem. Pharm. Bull.,
1991, 39, 2606–2608.
4,400-Dimethoxy-1,10:30,100-terphenyl
(3n).17
The
title
compound was obtained as white solid, 23% yield, mp: 193–
194 ꢀC, and the analytical data are consistent with those in the
literature. 1H NMR (600 MHz, CDCl3) d 7.72 (d, J ¼ 1.6 Hz, 1H),
7.63–7.54 (m, 4H), 7.54–7.40 (m, 3H), 7.05–6.96 (m, 4H), 3.87 (s,
6H); 13C NMR (151 MHz, CDCl3) d 159.21, 141.32, 133.81,
129.11, 128.26, 125.33, 125.15, 114.22, 55.36.
Characterizations of other byproducts
3 (a) G. F. Woods and I. W. Tucker, J. Am. Chem. Soc., 1948, 70,
2174–2177; (b) C. J. F. Du, H. Hart and K. K. D. Ng, J. Org.
Chem., 1986, 51, 3162–3165.
3-(2-Oxo-2-phenylethyl)-1,5-diphenylpentane-1,5-dione
(7a).12a The title compound was obtained as white solid, mp:
139–140 ꢀC, and the analytical data are consistent with those in
4 (a) S. E. Shetgaonkar and F. V. Singh, Synth. Commun., 2019,
49, 1092–1102; (b) V. Y. Sosnovskikh, V. Y. Korotaev,
A. Y. Barkov, I. B. Kutyashev and A. V. Safrygin, Eur. J. Org.
Chem., 2015, 2015, 1932–1944; (c) M.-Y. Chang, C.-K. Chan,
S.-Y. Lin and M.-H. Wu, Tetrahedron, 2013, 69, 9616–9624;
(d) G. R. Ames, Chem. Rev., 1958, 58, 895–923; (e)
T. Yamamoto, M. Ammam, S. A. Roberts, G. S. Wilson and
R. S. Glass, Tetrahedron, 2016, 72, 2527–2534; (f) R. Panwar,
Shally, R. Shaw, A. Elagamy and R. Pratap, Org. Biomol.
Chem., 2018, 16, 8994–9002.
1
the literature. H NMR (600 MHz, CDCl3) d 8.01 (d, J ¼ 7.8 Hz,
6H), 7.55 (t, J ¼ 7.3 Hz, 3H), 7.45 (t, J ¼ 7.7 Hz, 6H), 3.44–3.31 (m,
1H), 3.26 (d, J ¼ 6.4 Hz, 6H); 13C NMR (151 MHz, CDCl3)
d 199.49, 136.81, 133.21, 128.63, 128.21, 42.39, 27.66.
50-Phenyl-1,10:30,100-terphenyl (8a).13b The title compound was
obtained as white solid, mp: 170–171 ꢀC, and the analytical data
1
are consistent with those in the literature. H NMR (600 MHz,
CDCl3) d 7.80 (s, 3H), 7.72 (d, J ¼ 8.0 Hz, 6H), 7.49 (t, J ¼ 7.6 Hz,
6H), 7.40 (t, J ¼ 7.3 Hz, 3H); 13C NMR (151 MHz, CDCl3)
d 142.35, 141.16, 128.85, 127.55, 127.36, 125.18.
5 J. M. Antelo Miguez, L. A. Adrio, A. Sousa-Pedrares, J. M. Vila
and K. K. Hii, J. Org. Chem., 2007, 72, 7771–7774.
6 (a) T. N. Poudel, R. J. I. Tamargo, H. Cai and Y. R. Lee, Asian J.
Org. Chem., 2018, 7, 985–1005; (b) R. A. Fernandes, A. Kumari
and R. S. Pathare, Synlett, 2020, 31, 403–420; (c) Y. Xia,
H. Huang, F. Zhang and G.-J. Deng, Org. Lett., 2019, 21,
7489–7492; (d) S. Yang, D. Lu, H. Huo, F. Luo and Y. Gong,
Org. Lett., 2018, 20, 6943–6947.
7 (a) S. Saito and Y. Yamamoto, Chem. Rev., 2000, 100, 2901–
2916; (b) H. Tsuji, K.-i. Yamagata, T. Fujimoto and
E. Nakamura, J. Am. Chem. Soc., 2008, 130, 7792–7793; (c)
R. J. I. Tamargo, T. N. Poudel and Y. R. Lee, RSC Adv.,
2016, 6, 70311–70319.
Characterizations of esters
Ethyl 4-methoxybenzoate (9n).23 The title compound was
obtained as colorless oil, 46% yield, and the analytical data are
consistent with those in the literature. 1H NMR (600 MHz,
CDCl3) d 8.00 (d, J ¼ 8.9 Hz, 2H), 6.91 (d, J ¼ 8.9 Hz, 2H), 4.35 (q,
J ¼ 7.1 Hz, 2H), 3.86 (s, 3H), 1.38 (t, J ¼ 7.1 Hz, 3H); 13C NMR
(151 MHz, CDCl3) d 166.43, 163.25, 131.55, 122.97, 113.55,
60.66, 55.43, 14.40.
8 A. I. Kovalev, Y. I. Lyakhovetskli, M. M. Teplyakov,
A. L. Rusanov, P. V. Petrovskii and S. O. Yakushin, Russ.
Chem. Bull., 1993, 42, 1529–1535.
Conflicts of interest
There are no conicts to declare.
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 12113–12118 | 12117

View Article Online
RSC Advances
Paper
9 (a) N. Obaya, C. Payrastre and Y. Madaule, Tetrahedron, 2001, 14 (a) R. C. Eldereld and T. P. King, J. Am. Chem. Soc., 1954, 76,
57, 9137–9147; (b) C. Payrastre, N. Obaya, Y. Madaule and
J.-G. Wolf, Tetrahedron Lett., 1994, 35, 3059–3062.
5437–5439; (b) S. A. Barker and T. Riley, J. Chem. Soc., Perkin
Trans. 1, 1972, 809–812.
10 (a) Y.-M. Hong, H.-O. Kim, K.-H. Kim and S.-I. Cho, Journal of 15 (a) M. W. Justik, Tetrahedron Lett., 2007, 48, 3003–3007; (b)
Sensor Science and Technology, 2012, 21, 13–20; (b) A. Bolag,
M. Mamada, J.-i. Nishida and Y. Yamashita, Chem. Mater.,
2009, 21, 4350–4352; (c) G. Doddi and G. Ercolani,
Synthesis, 1985, 1985, 789–790.
M. Suzuki, A. Yanagisawa and R. Noyori, Tetrahedron Lett.,
1982, 23, 3595–3596; (c) X. Huang, X. Li, M. Zou, S. Song,
C. Tang, Y. Yuan and N. Jiao, J. Am. Chem. Soc., 2014, 136,
14858–14865.
11 (a) T. H. Fife and L. K. Jao, J. Org. Chem., 1965, 30, 1492–1495; 16 K. Huang, X. Ke, H. Wang, J. Wang, C. Zhou, X. Xu, L. Liu and
(b) R. Kumar and A. K. Chakraborti, Tetrahedron Lett., 2005, J. Li, Org. Biomol. Chem., 2015, 13, 4486–4493.
46, 8319–8323; (c) N. Hamada, K. Kazahaya, H. Shimizu and 17 Q. Teng, S. Mo, J. Pan, N. Wu, H. Wang and Y. Pan, Synthesis,
T. Sato, Synlett, 2004, 2004, 1074–1076; (d) R. Gopinath, 2016, 48, 455–461.
S. J. Haque and B. K. Patel, J. Org. Chem., 2002, 67, 5842– 18 N. Gu, Y. Liu, P. Liu, X. Ma, L. Yan and B. Dai, Chin. J. Chem.,
5845. 2015, 33, 1189–1193.
12 (a) J. Yu, Y. Hu, Q. Huang, R. Ma and S. Yang, Synth. 19 T. Igarashi, A. Haito, N. Chatani and M. Tobisu, ACS Catal.,
Commun., 2000, 30, 2801–2806; (b) J. H. Yu, Y. Hu,
S. Y. Yang and Y. Q. Yin, Chin. Chem. Lett., 1998, 9, 1–4.
13 (a) Y. Sasaki and C. U. Pittman, J. Org. Chem., 1973, 38, 3723–
2018, 8, 7475–7483.
´
20 E. F. Corsico and R. A. Rossi, J. Org. Chem., 2002, 67, 3311–
3316.
3726; (b) R. Tayebee, M. Jarrahi, B. Maleki, M. Kargar Razi, 21 G. Ranjani and R. Nagarajan, Org. Lett., 2017, 19, 3974–3977.
Z. B. Mokhtari and S. M. Baghbanian, RSC Adv., 2015, 5, 22 R. K. Mohamed, S. Mondal, B. Gold, C. J. Evoniuk,
10869–10877; (c) R. Tayebee and M. Jarrahi, RSC Adv.,
2015, 5, 21206–21214; (d) R. Tayebee, K. Savoji, M. K. Razi
and B. Maleki, RSC Adv., 2016, 6, 55319–55326.
T. Banerjee, K. Hanson and I. V. Alabugin, J. Am. Chem.
Soc., 2015, 137, 6335–6349.
23 J. Salvadori, E. Balducci, S. Zaza, E. Petricci and M. Taddei, J.
Org. Chem., 2010, 75, 1841–1847.
12118 | RSC Adv., 2020, 10, 12113–12118
This journal is © The Royal Society of Chemistry 2020