Electrooxidative tandem cyclization ofN-propargylanilines with sulfinic acids for rapid access to 3-arylsulfonylquinoline derivatives

Article abstract of DOI:10.1039/d1gc00171j

A series ofN-propargylanilines (0.2 mmol) and sulfinic acids (0.5 mmol) afforded 3-arylsulfonylquinoline derivatives in high yields (70-93%) and low current efficiencies upon electrooxidation. Electrolyses were carried out in a one-compartment cell, under

Full text of DOI:10.1039/d1gc00171j

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Electrooxidative tandem cyclization of
N-propargylanilines with sulfinic acids for rapid
Cite this: DOI: 10.1039/d1gc00171j
access to 3-arylsulfonylquinoline derivatives†
a,b,c
Jie Liu,a Min Wang,*a Laiqiang Lia and Lei Wang
*
A series of N-propargylanilines (0.2 mmol) and sulfinic acids (0.5 mmol) afforded 3-arylsulfonylquinoline
derivatives in high yields (70–93%) and low current efficiencies upon electrooxidation. Electrolyses were
Received 16th January 2021,
Accepted 25th March 2021
carried out in
a one-compartment cell, under constant current and ambient conditions, in
methanol-nBu4NBF4 containing pyridine (0.4 mmol), without any added chemical oxidant. A scale-up
electrolysis carried out on 5 mmol of N-propargylaniline 1a gave 3-arylsulfonylquinoline 3aa in 65% yield
and 56% current efficiency. A mechanistic hypothesis is presented.
DOI: 10.1039/d1gc00171j
rsc.li/greenchem
tocol for the eosin Y-catalyzed three-component sulfonylation
of N-propargylanilines, diaryliodonium salts and DABCO
Introduction
The synthesis of quinoline derivatives is a subject of continu- (SO2)2.7b Very recently, a visible-light-induced cyclization of
ous interest and great importance because of their valued N-propargylamines with sulfinic acids for the synthesis of
application in drug discovery, natural product synthesis, and 3-sulfonated quinoline derivatives without an external photo-
materials science.1 Traditional methods to construct quinoline catalyst has been described by Li and co-workers.7c
scaffolds include some named reactions such as Skraup,
Oxidative tandem cyclization is of significant importance in
Combes, Povarov and Friedlander.2 Since Skraup reported the the synthesis of heteropolycyclic skeletons by avoiding the pre-
formation of quinoline for the first time by heating aniline functionalization process and has received considerable atten-
with glycerol, sulfuric acid and an oxidizing agent in 1880, tion due to its high atom economy.8 The design of oxidative
there have been great achievements by using aniline and its tandem processes is environmentally advantageous for the
derivatives as the basic starting materials.3 N-Propargylamines, dramatic reduction of waste and costs, but most of them
a type of efficient radical acceptor, have proven to be versatile usually need stoichiometric oxidants.9 Electroorganic syn-
starting materials for the construction of various substituted thesis, which employs electrons as oxidizing or reducing
quinolines,4 including biologically active 3-substituted reagents and avoids the use of stoichiometric oxidants, can
quinolones.5 Among them, 3-arylsulfonylquinoline derivatives offer sustainable alternatives to traditional redox reactions.10
are widely used in the pharmaceutical industry as they However, there is no report for the anodic electrooxidative
are efficient anti-obesity and central nervous system agents.6 tandem cyclization of N-propargylamines to prepare quinolone
However, the efficient synthesis of 3-arylsulfonylquinoline skeletons. In 2017, Lei’s group found an electrooxidative
derivatives is quite limited. Tang and co-workers discovered tandem cyclization of ynones with sulfinic acids to access sul-
a tert-butyl hydroperoxide mediated reaction of N-propargyl- fonated indenones with the anodic oxidation of iodide to
amines and arylsulfonylhydrazides for the synthesis of 3-aryl- iodine, which in turn oxidized the reagent (Scheme 1a).11
sulfonylquinolines.7a In 2018, Zhang’s group developed a pro- Inspired by this work and our previous works,7c,12 herein we
report an electrooxidative tandem cyclization reaction of
N-propargylanilines with sulfinic acids to afford 3-arylsulfonyl-
quinoline derivatives under constant current in a one-compart-
ment cell and in the absence of iodide (Scheme 1b).
aKey Laboratory of Green and Precise Synthetic Chemistry and Applications, Ministry
of Education, Department of Chemistry, Huaibei Normal University, Huaibei,
Anhui 235000, P. R. China. E-mail: wangmin204@chnu.edu.cn
bAdvanced Research Institute and Department of Chemistry, Taizhou University,
Taizhou, Zhejiang 318000, P. R. China. E-mail: leiwang@chnu.edu.cn
cState Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic
Chemistry, Shanghai 200032, P. R. China
In addition, great achievements in the field of electro-
chemical reactions of sulfinate salts have been made
(Scheme 2).13 However, these reported methods are all based
on sulfinate salts and are all coupling reactions.14–17
Therefore, the development of an electrooxidative tandem
cyclization based on sulfinic acids, which are more convenient
†Electronic supplementary information (ESI) available. See DOI: 10.1039/
d1gc00171j
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Table 1 Optimization of the reaction conditionsa
Entry
Deviation from the standard conditions
Yieldb (%)
1
2
3
4
5
6
7
8
Standard conditions
10.0 mA
2.5 mA
C(+) Pt(−)
C(+) C(−)
Replacing pyridine with Et3N
Replacing pyridine with DABCO
Replacing nBu4NBF4 with nBu4NPF6
Replacing CH3OH with DCE
Replacing CH3OH with CH3CN
No electricity
89
67
51
80c
23c
58
57
74
32
71
0
Scheme 1 Electrooxidative tandem cyclization reactions.
9
10
11
a Standard conditions: platinum electrodes (1.5 cm × 1.5 cm × 0.3 mm)
as both the anode and cathode, constant current = 5.0 mA, 1a
(0.20 mmol), 2a (2.5 equiv.), pyridine (2.0 equiv.), nBu4NBF4
(0.3 mmol), CH3OH (5.0 mL), undivided cell, room temperature, air,
5 h, 4.4 F mol−1 b Isolated yield. c Carbon rod electrode (∅ 6 mm).
.
mation of 3aa in 57–58% yield. For the choice of the electro-
lyte, using nBu4NPF6 instead of nBu4NBF4 resulted in a lower
yield (74%, entry 8). The solvent could also affect the efficiency
of product formation and the formation of 3aa was suppressed
by using acetonitrile or 1,2-dichloroethane (DCE) instead of
methanol as the solvent (entries 9 and 10). As expected, no
conversion occurred in the absence of electric current
(Table 1, entry 11). There is not any side product was obtained
during our investigation.
Scheme 2 Transformations of sulfinic salts.
to work with than sulfinate salts, is novel and of great interest
as a green synthetic method.
With the optimized reaction conditions in hand, the reac-
tion scope was probed next by varying the aromatic rings A
Results and discussion
As shown in Table 1, in the presence of an excess of pyridine, and B of N-propargylanilines (Scheme 3). First, phenyl ring I of
employing platinum electrodes (1.5 cm × 1.5 cm × 0.3 mm) as the aromatic alkyne moiety could be substituted at the para-
both the anode and cathode, the desired sulfonylated 3aa was position with an electron-donating group [MeO (3ba), Me (3ca)
t
produced in 89% yield with 5 mA constant current in an undi- or Bu (3da)], providing the corresponding products (3ba–3da)
vided cell containing an electrolyte solution of nBu4NBF4 in in 87–93% yields. Meanwhile, a halogen such as F, Cl or Br
CH3OH (Table 1, entry 1). When the model reaction was per- attached on phenyl ring I afforded the desired products (3ea–
formed at an operating current of 10 mA, over-oxidation due to 3ga) in 79–84 yields. Notably, an electron-withdrawing group
a large excess of charge (9.4 F mol−1) caused the formation of (CF3, COMe, CN, or NO2) also exhibited good reactivity towards
decomposition products (from TLC analysis), resulting in a the reaction, generating the anticipated products (3ha–3ka) in
lower yield (67%) of the desired product 3aa (Table 1, entry 2). 74–78% yields. Additionally, this system was also applied to
When the reaction was carried out at a current of 2.5 mA, the heterocyclic substrate 1l, allowing the formation of the desired
conversion was incomplete. A lower yield (51%) of 3aa was product 3la in 79% yield.
obtained and reactant 1a was recovered in 43% yield (Table 1,
Subsequently, an investigation into the effect of substitu-
entry 3). Slightly reduced but acceptable yields were obtained ents on phenyl ring II of the aniline unit was performed.
when a platinum electrode was used as the cathode and a The results showed that propargylamines 1 bearing both elec-
carbon rod electrode as the anode (entry 4). A significant tron-withdrawing and electron-donating groups at the para-
decline in the yield of 3aa (23%) was obtained when the reac- position were smoothly transformed into the desired pro-
tion was performed with carbon rod electrodes as both the ducts 3ma–3ra in 70–89% yields (Scheme 3). For the meta-
anode and cathode along with the recovery of 61% yield of 1a methyl substituted reactant 1s, only 7-methyl-4-phenyl-3-tosyl-
(entry 5). Other bases, such as Et3N (entry 6) and DABCO quinoline 3sa was obtained in 82% yield. No 5-methyl-4-
(entry 7), were less effective than pyridine leading to the for- phenyl-3-tosylquinoline isomer was detected because of the
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Scheme 3 The scope of N-propargylanilines [standard conditions:
platinum electrodes (1.5 cm × 1.5 cm × 0.3 mm) as both the anode and
cathode, constant current = 5.0 mA, 1 (0.20 mmol), 2a (0.50 mmol), pyr-
idine (0.4 mmol), nBu4NBF4 (0.3 mmol), CH3OH (5.0 mL), undivided cell,
room temperature, air, 5 h, 4.4 F mol−1; the isolated yield of the
product].
Scheme 4 The scope of sulfinic acids [standard conditions: platinum
electrodes (1.5 cm × 1.5 cm × 0.3 mm) as both the anode and cathode,
constant current = 5.0 mA, 1a (0.20 mmol), 2 (0.50 mmol), pyridine
(0.40 mmol), nBu4NBF4 (0.30 mmol), CH3OH (5.0 mL), undivided cell,
room temperature, air, 5 h, 4.4 F mol−1; the isolated yield of the
product].
peri steric interaction between the phenyl ring at position 4
and the methyl substituent at position 5. An ortho-substituent
on phenyl ring II had little influence on the yield of cyclisa-
tion. Indeed, propargylamines 1t and 1u afforded the cyclized
products 3ta and 3ua in 70% and 75% yields, respectively. It
should be noted that the highest yields were obtained with
the strong electron-donating MeO group (93% and 89% for
3ba and 3ma, respectively), indicating that the sulfinyl radical
is slightly electrophilic.
This electrochemical reaction also displayed a broad
scope with respect to sulfinic acids (Scheme 4). Sulfinic
acids with both electron-donating and electron-withdraw-
ing groups reacted well with N-(3-phenylprop-2-yn-1-yl)
aniline (1a), giving the desired 3-arylsulfonylquinolines
3ab–3ak in very good yields (from 73% for 3aj to 87% for
3ac). Generally, electron-donating groups give higher yields
than electron-withdrawing groups, meaning that the
tandem reaction efficiency is sensitive to the electronic
properties of not only N-propargylanilines, but also sulfi-
nic acids. The reaction exhibited considerable tolerance of
heteroaryl-substituted sulfinic acid, giving 75% yield of
3al. However, n-butanesulfinic acid did not work at all
(3am) and no product was obtained under the standard
conditions.
This electrochemical tandem cyclization was scaled up
25-fold (5.0 mmol, 1.1 g scale) with the same charge of 4.4 F
mol−1. As shown in Scheme 5, the desired product 3aa was iso-
lated in 65% yield. The current efficiency of 56% is worth
noting, which is nearly three times as high as that of the milli-
gram scale electrolysis. This result shows the potential of this
electrochemical transformation for larger scale syntheses.
Several experiments were conducted to gain some insights
into this tandem cyclization. When the radical scavenger
2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO, 0.40 mmol, 2.0
equiv.) was added into the reaction, the significant decrease of
the yield indicated that a radical process might be involved
under the standard conditions (Scheme 6a). Additionally,
when electrolysis of the model reaction was carried out under
a nitrogen atmosphere, arylsulfonylquinoline 3aa was isolated
Scheme 5 Gram-scale synthesis.
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Scheme 6 The control experiments.
in 12% yield (Scheme 6b). The results from the experiment
indicate that 12% of 3aa was formed via oxidation at the
anode and 88% of 3aa was formed via oxidation by oxygen in
the air.
After that, cyclic voltammetry (CV) of 1a, 2a, and 3aa in
CH3OH with nBu4NBF4 in the presence of pyridine, using
glassy carbon as the working electrode, and a Pt wire and Ag/
AgCl as the counter and reference electrodes, respectively, was
determined in the oxidation potential region of 0–4 V vs. Ag/
AgCl (Fig. S1 of the ESI†). It can be seen from Fig. S1† that sul-
fonylquinoline 3aa is not oxidized in this potential region. It is
also found that the oxidative potential of 4-methyl-
benzenesulfinate (anion of 2a) and 1a is at 1.05 V and 1.51 V,
respectively. In addition, CV of mixtures of 1a and 2a was also
recorded at the following 1a/2a molar ratios (1a/2a = 0, 0.5, 1.0,
and 2.0), as shown in Fig. S2 of the ESI.† This strongly suggests
that the electrooxidation of 4-methylbenzenesulfinate would
occur preferentially to that of 1a. Moreover, the molar ratio of
sulfinate/1a (sulfinate/1a = 2.5) also favors the oxidation of the
sulfinate prior to 1a.
Scheme 7 The proposed mechanism.
the hydroperoxyl radical to afford 3aa. Path B is for a one-elec-
tron mechanism involving dioxygen.
Conclusion
In conclusion, we have developed a friendly electrochemical
tandem cyclization protocol for the synthesis of 3-arylsulfonyl-
quinoline derivatives through the electrochemical oxidative
reaction of N-propargylanilines with sulfinic acids. Under
undivided electrolysis conditions, the reaction is compatible
with a series of N-propargylanilines and sulfinic acids contain-
ing various functional groups at room temperature. This study
will inspire us to extend electrochemical anodic oxidation to
other tandem reactions and they are underway in our
laboratory.
Based on the studies in this work and related reports,18,10h
a proposed mechanism of the electrooxidative tandem cycliza-
tion reaction is depicted in Scheme 7 using N-(3-phenylprop-2-
yn-1-yl)aniline (1a) and 4-methylbenzenesulfinic acid (2a) as
model substrates. First, when electricity was passed through
the cell, the sulfinyl anion (A), which was generated from the
reaction of 2a with pyridine as a base, was oxidized at the
anode to give a delocalized radical (B).19 The addition of
radical B to 1a through its S center as a soft “radicalophile” to
the carbon–carbon triple bond afforded the key carbon-cen-
tered radical C, which subsequently underwent an intra-
molecular radical cyclization to generate radical D. The
obtained radical (D) was then oxidized at the anode (path A) or
Experimental section
General remarks
was then oxidized by oxygen in the air (path B). In path A, All H NMR, 13C NMR and 19F NMR spectra were recorded on
radical D was then oxidized at the anode through single elec- a 600 MHz Bruker FT-NMR spectrometer (600 MHz or
tron transfer (SET) to afford the carbocation intermediate E. 150 MHz or 564 MHz, respectively). All chemical shifts are
Then, the formed E underwent a deprotonation, providing the given as δ value (ppm) with reference to tetramethylsilane
intermediate 4-phenyl-3-tosyl-1,2-dihydroquinoline (F). Finally, (TMS) as an internal reference. The peak patterns are indicated
F underwent oxidation–aromatization to afford the desired as follows: s, singlet; d, doublet; t, triplet; m, multiplet; q,
product 3aa in the presence of O2 as an oxidant. Path A is for a quartet. The coupling constants, J, are reported in Hertz (Hz).
two-electron mechanism. In path B, radical D was oxidized by High resolution mass spectroscopy data of the product were
oxygen in the air10h to generate radical G, which then released recorded on a Waters Micromass GCT instrument and an
1
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Agilent Technologies 6540 UHD Accurate-Mass Q-TOF LC/MS CDCl3): δ = 151.7, 150.1, 149.7, 147.6, 143.7, 137.8, 132.8,
(ESI). The chemicals and solvents were purchased from com- 132.0, 129.8, 129.6, 129.4, 129.0, 127.8, 127.6, 127.6, 127.5,
mercial suppliers, either from Aldrich (USA) or Shanghai 124.5, 34.7, 31.4, 21.5.
Chemical Company (China) without further purification. The
4-(4-Fluorophenyl)-3-tosylquinoline (3ea).7c Yield: 59.6 mg
1
starting materials, propargylamines (1a–1u), were prepared (79%). H NMR (600 MHz, CDCl3): δ = 9.78 (s, 1H), 8.21 (d, J =
according to the reported method.18 The chemicals were pur- 8.4 Hz, 1H), 7.84–7.82 (m, 1H), 7.50–7.48 (m, 1H), 7.35–7.33
chased from commercial suppliers either from Aldrich (USA) (m, 1H), 7.25 (d, J = 8.4 Hz, 2H), 7.11 (d, J = 8.4 Hz, 2H), 7.06
or Shanghai Chemical Company (China). All the solvents were (t, J = 8.4 Hz, 2H), 6.97–6.95 (m, 2H), 2.37 (s, 3H); 13C NMR
dried and freshly distilled prior to use. Products were purified (150 MHz, CDCl3): δ = 162.8 (d, J = 247.5 Hz), 149.6, 148.6,
by flash chromatography packed with 200–300 mesh silica 147.5, 144.2, 137.8, 132.7, 132.1, 131.8 (d, J = 8.4 Hz), 129.6,
gel, SiO2.
129.2, 128.3 (d, J = 3.0 Hz), 127.9, 127.6, 127.3, 127.0, 114.7 (d,
J = 21.0 Hz), 21.4. 19F NMR (564 MHz, CDCl3): δ = −112.14.
Experimental procedure
4-(4-Chlorophenyl)-3-tosylquinoline (3fa).7c Yield: 63.1 mg
1
N-(3-Phenyl-2-propynyl)aniline (1a, 0.20 mmol), sulfinic acid (80%). H NMR (600 MHz, CDCl3): δ = 9.76 (s, 1H), 8.22 (d, J =
(2, 0.50 mmol), pyridine (0.40 mmol), nBu4NBF4 (0.30 mmol) 8.4 Hz, 1H), 7.85–7.82 (m, 1H), 7.50–7.47 (m, 1H), 7.34–7.32
and CH3OH (5.0 mL) were sequentially added to a 15 mL oven- (m, 3H), 7.28–7.26 (m, 2H), 7.11 (d, J = 7.8 Hz, 2H), 6.92 (d, J =
dried undivided three-necked bottle equipped with a magnetic 8.4 Hz, 2H), 2.38 (s, 3H); 13C NMR (150 MHz, CDCl3): δ =
stir bar. The bottle was equipped with two platinum electrodes 149.7, 148.3, 147.7, 144.3, 137.9, 135.0, 132.8, 132.2, 131.4,
(1.5 cm × 1.5 cm × 0.3 mm) as an anode and a cathode, 131.1, 129.8, 129.3, 128.0, 127.9, 127.8, 127.1, 127.0, 21.5.
respectively. The reaction mixture was stirred and electrolyzed
4-(4-Bromophenyl)-3-tosylquinoline (3ga).7c Yield: 73.6 mg
1
at a constant current of 5 mA at room temperature for 5 h. (84%). H NMR (600 MHz, CDCl3): δ = 9.77 (s, 1H), 8.22 (d, J =
When the reaction was complete, the reaction solution was 8.4 Hz, 1H), 7.85–7.82 (m, 1H), 7.49–7.48 (m, 3H), 7.33 (d, J =
concentrated in a vacuum. The resulting crude mixture was 8.4 Hz, 1H), 7.26 (d, J = 7.2 Hz, 2H), 7.12 (d, J = 7.8 Hz, 2H),
purified by flash column chromatography (petroleum ether/ 6.85 (d, J = 8.4 Hz, 2H), 2.38 (s, 3H); 13C NMR (150 MHz,
ethyl acetate = 3 : 1 to 5 : 1) to give the desired product (3).
CDCl3): δ = 149.7, 148.3, 147.7, 144.4, 137.9, 132.7, 132.3,
131.6, 131.6, 130.9, 129.8, 129.3, 128.0, 127.9, 127.1, 127.0,
123.2, 21.6.
Characterization data for the products
4-Phenyl-3-tosylquinoline (3aa).7a Yield: 64.0 mg (89%).
3-Tosyl-4-(4-(trifluoromethyl)phenyl)quinolone (3ha).7a Yield:
1H NMR (600 MHz, CDCl3): δ = 9.79 (s, 1H), 8.21 (d, J = 8.4 Hz, 66.7 mg (78%). 1H NMR (600 MHz, CDCl3): δ = 9.79 (s, 1H),
1H), 7.83–7.80 (m, 1H), 7.48–7.44 (m, 2H), 7.35–7.33 (m, 3H), 8.24 (d, J = 8.4 Hz, 1H), 7.87–7.84 (m, 1H), 7.61 (d, J = 7.8 Hz,
7.21 (d, J = 8.4 Hz, 2H), 7.05 (d, J = 7.8 Hz, 2H), 6.96 (d, J = 2H), 7.52–7.49 (m, 1H), 7.27 (d, J = 8.4 Hz, 1H), 7.21 (d, J = 7.8
7.8 Hz, 2H), 2.35 (s, 3H); 13C NMR (150 MHz, CDCl3): δ = Hz, 2H), 7.13 (d, J = 7.8 Hz, 2H), 7.08 (d, J = 7.8 Hz, 2H), 2.38
149.7, 149.6, 147.7, 144.0, 137.9, 132.6, 132.1, 129.9, 129.6, (s, 3H); 13C NMR (150 MHz, CDCl3): δ = 149.7, 147.7, 147.5,
129.2, 128.6, 127.8, 127.7, 127.6, 127.4, 127.4, 21.5.
144.4, 137.6, 136.5, 132.6, 132.4, 130.8 (q, J = 33.0 Hz), 130.4,
4-(4-Methoxyphenyl)-3-tosylquinoline (3ba).7a Yield: 72.4 mg 129.8, 129.3, 128.2, 127.7, 126.8, 126.7, 124.5 (q, J = 4.5 Hz),
1
(93%). H NMR (400 MHz, CDCl3): δ = 9.55 (s, 1H), 8.02 (d, J = 123.8 (q, J = 271.5 Hz), 21.4. 19F NMR (564 MHz, CDCl3): δ =
9.6 Hz, 1H), 7.39–7.37 (m, 2H), 7.26 (t, J = 7.8 Hz, 2H), 7.12 −62.72.
(d, J = 8.4 Hz, 2H), 6.97 (d, J = 8.4 Hz, 2H), 6.87 (d, J = 7.8 Hz,
1-(4-(3-Tosylquinolin-4-yl)phenyl)ethan-1-one (3ia).7c Yield:
2H), 6.43 (d, J = 2.4 Hz, 1H), 3.52 (s, 3H), 2.27 (s, 3H); 13C NMR 59.4 mg (74%). 1H NMR (600 MHz, CDCl3): δ = 9.75 (s, 1H),
(100 MHz, CDCl3): δ = 158.5, 148.0, 146.0, 145.3, 143.9, 137.9, 8.22 (d, J = 8.4 Hz, 1H), 7.98 (d, J = 7.8 Hz, 2H), 7.85 (t, J = 7.8
132.8, 132.8, 130.9, 129.9, 129.2, 128.8, 128.6, 127.8, 127.7, Hz, 1H), 7.49 (t, J = 7.8 Hz, 1H), 7.29–7.27 (m, 3H), 7.14–7.10
124.8, 104.7, 55.3, 21.5.
(m, 4H), 2.74 (s, 3H), 2.38 (s, 3H); 13C NMR (150 MHz, CDCl3):
1
4-(p-Tolyl)-3-tosylquinoline (3ca).7a Yield: 65.0 mg (87%). H δ = 197.2, 149.4, 148.1, 147.4, 144.3, 137.6, 137.5, 136.8, 132.2,
NMR (600 MHz, CDCl3): δ = 9.77 (s, 1H), 8.20 (d, J = 8.4 Hz, 130.1, 129.6, 129.2, 128.0, 127.6, 127.3, 126.8, 126.6, 26.6, 21.4.
1H), 7.82–7.80 (m, 1H), 7.46–7.44 (m, 1H), 7.38–7.37 (m, 1H),
4-(3-Tosylquinolin-4-yl)benzonitrile (3ja).7a Yield: 59.2 mg
1
7.24 (d, J = 8.4 Hz, 2H), 7.15 (d, J = 7.2 Hz, 2H), 7.06 (d, J = 7.8 (77%). H NMR (600 MHz, CDCl3): δ = 9.75 (s, 1H), 8.25 (d, J =
Hz, 2H), 6.86 (d, J = 7.2 Hz, 2H), 2.48 (s, 3H), 2.36 (s, 3H); 8.4 Hz, 1H), 7.88–7.86 (m, 1H), 7.67 (d, J = 7.8 Hz, 2H),
13C NMR (150 MHz, CDCl3): δ = 150.1, 149.6, 147.8, 144.0, 7.53–7.50 (m, 1H), 7.28–7.27 (m, 2H), 7.21 (d, J = 8.4 Hz, 1H),
138.6, 138.0, 132.8, 132.0, 129.9, 129.7, 129.6, 129.1, 128.3, 7.15–7.14 (m, 4H), 2.40 (s, 3H); 13C NMR (150 MHz, CDCl3): δ
128.0, 127.7, 127.5, 21.5, 21.4.
= 149.7, 147.7, 147.1, 144.8, 137.8, 137.8, 132.5, 132.4, 131.4,
Yield: 130.8, 130.0, 129.5, 128.4, 127.8, 126.6, 126.5, 118.2, 112.8,
4-(4-(tert-Butyl)phenyl)-3-tosylquinoline
(3da).7a
73.1 mg (88%). 1H NMR (600 MHz, CDCl3): δ = 9.81 (s, 1H), 21.6.
8.21 (d, J = 8.4 Hz, 1H), 7.81 (td, J1 = 7.2 Hz, J2 = 1.2 Hz, 1H),
4-(4-Nitrophenyl)-3-tosylquinoline (3ka).7a Yield: 60.7 mg
1
7.47–7.45 (m, 1H), 7.39 (d, J = 7.8 Hz, 1H), 7.31 (d, J = 8.4 Hz, (75%). H NMR (600 MHz, CDCl3): δ = 9.66 (s, 1H), 8.19–8.15
2H), 7.14 (d, J = 8.4 Hz, 2H), 6.99 (d, J = 7.8 Hz, 2H), 6.87 (d, J = (m, 3H), 7.80 (t, J = 7.8 Hz, 1H), 7.44 (t, J = 9.0 Hz, 1H), 7.23 (d,
7.8 Hz, 2H), 2.34 (s, 3H), 1.42 (s, 9H); 13C NMR (150 MHz, J = 8.4 Hz, 2H), 7.15–7.13 (m, 3H), 7.07 (d, J = 7.8 Hz, 2H), 2.32
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(s, 3H); 13C NMR (150 MHz, CDCl3): δ = 149.6, 148.1, 147.8, Hz, 2H), 7.20 (d, J = 7.8 Hz, 2H), 7.08 (d, J = 7.8 Hz, 2H), 6.95
146.9, 144.9, 139.7, 137.9, 132.6, 132.6, 131.1, 130.0, 129.6, (d, J = 7.2 Hz, 2H), 2.37 (s, 3H); 13C NMR (150 MHz, CDCl3): δ
128.5, 127.8, 126.6, 126.4, 122.8, 21.6.
= 150.5, 150.3, 150.2, 144.5, 137.1, 134.4, 133.7, 132.3, 131.3,
4-(Thiophen-2-yl)-3-tosylquinoline (3la).7c Yield: 57.8 mg 131.1, 129.8, 129.3, 128.0, 127.9, 127.2, 117.8, 111.6, 21.5.
1
(79%). H NMR (600 MHz, CDCl3): δ = 9.78 (s, 1H), 8.19 (d, J =
7-Methyl-4-phenyl-3-tosylquinoline (3sa).7c Yield: 61.3 mg
1
8.4 Hz, 1H), 7.83–7.80 (m, 1H), 7.58 (d, J = 8.4 Hz, 1H), (82%). H NMR (600 MHz, CDCl3): δ = 9.80 (s, 1H), 8.20 (d, J =
7.51–7.49 (m, 2H), 7.31 (d, J = 8.4 Hz, 2H), 7.13–7.09 (m, 3H), 8.4 Hz, 1H), 7.82–7.80 (m, 1H), 7.46–7.44 (m, 1H), 7.36 (d, J =
7.00–6.99 (m, 1H), 2.35 (s, 3H); 13C NMR (150 MHz, CDCl3): δ 8.4 Hz, 1H), 7.28–7.25 (m, 2H), 7.21 (d, J = 8.4 Hz, 2H), 7.06 (d,
= 149.5, 147.7, 144.1, 143.0, 137.5, 134.3, 132.3, 131.7, 131.4, J = 7.8 Hz, 2H), 6.89 (d, J = 6.6 Hz, 1H), 6.54 (s, 1H), 2.36 (s,
129.5, 129.3, 128.6, 128.4, 128.1, 127.8, 127.1, 126.7, 21.5.
3H), 2.24 (s, 3H); 13C NMR (150 MHz, CDCl3): δ = 150.0, 149.6,
6-Methoxy-4-phenyl-3-tosylquinoline (3ma).7a Yield: 69.3 mg 147.5, 143.8, 137.9, 137.1, 132.5, 132.4, 132.0, 130.1, 129.5,
1
(89%). H NMR (600 MHz, CDCl3): δ = 9.78 (s, 1H), 8.20 (d, J = 129.2, 129.0, 127.9, 127.7, 127.6, 127.4, 127.2, 21.4, 21.2.
8.4 Hz, 1H), 7.81 (t, J = 7.2 Hz, 1H), 7.47–7.45 (m, 1H), 7.41 (d,
8-Methyl-4-phenyl-3-tosylquinoline (3ta).7a Yield: 52.3 mg
1
J = 8.4 Hz, 1H), 7.23 (d, J = 7.8 Hz, 2H), 7.07 (d, J = 7.8 Hz, 2H), (70%). H NMR (600 MHz, CDCl3): δ = 9.79 (s, 1H), 7.64 (d, J =
6.89–6.86 (m, 4H), 3.91 (s, 3H), 2.35 (s, 3H); 13C NMR 6.6 Hz, 1H), 7.44 (t, J = 7.8 Hz, 1H), 7.33–7.30 (m, 3H), 7.21 (d,
(150 MHz, CDCl3): δ = 159.8, 149.9, 149.5, 147.6, 143.9, 137.8, J = 8.4 Hz, 2H), 7.16 (d, J = 8.4 Hz, 1H), 7.04 (d, J = 7.8 Hz, 2H),
132.9, 132.0, 131.3, 129.4, 129.0, 127.8, 127.7, 127.6, 127.3, 6.94 (d, J = 7.2 Hz, 2H), 2.86 (s, 3H), 2.34 (s, 3H); 13C NMR
124.4, 113.0, 55.3, 21.4.
(150 MHz, CDCl3): δ = 149.7, 148.7, 146.5, 143.9, 138.1, 137.5,
6-Methyl-4-phenyl-3-tosylquinoline (3na).7a Yield: 64.9 mg 133.0, 132.3, 132.1, 130.0, 129.1, 128.4, 127.8, 127.5, 127.4,
1
(87%). H NMR (600 MHz, CDCl3): δ = 9.71 (s, 1H), 8.09 (d, J = 125.3, 21.4, 18.1.
9.0 Hz, 1H), 7.64 (dd, J1 = 8.4 Hz, J2 = 1.2 Hz, 1H), 7.46 (t, J =
8-Bromo-4-phenyl-3-tosylquinoline (3ua).7c Yield: 65.7 mg
7.2 Hz, 1H), 7.35–7.32 (m, 2H), 7.19 (d, J = 7.8 Hz, 2H), (75%). 1H NMR (600 MHz, CDCl3): δ = 9.87 (s, 1H), 8.13 (dd, J1
7.05–7.04 (m, 3H), 6.94 (d, J = 7.2 Hz, 2H), 2.36 (s, 3H), 2.35 (s, = 6.6 Hz, J2 = 1.8 Hz, 1H), 7.49 (t, J = 7.8 Hz, 1H), 7.36 (t, J = 7.8
3H); 13C NMR (150 MHz, CDCl3): δ = 149.0, 148.4, 146.8, 143.9, Hz, 2H), 7.33–7.29 (m, 2H), 7.21 (d, J = 8.4 Hz, 2H), 7.07 (d, J =
138.1, 134.5, 132.8, 132.6, 130.0, 129.3, 129.2, 128.5, 127.9, 8.4 Hz, 2H), 6.96 (d, J = 7.2 Hz, 2H), 2.36 (s, 3H); 13C NMR
127.6, 127.5, 125.9, 21.7, 21.5.
(150 MHz, CDCl3): δ = 150.3, 148.5, 146.6, 144.2, 137.6, 135.6,
6-Fluoro-4-phenyl-3-tosylquinoline (3oa).7a Yield: 52.8 mg 133.6, 132.3, 129.9, 129.3, 129.0, 128.8, 128.0, 127.9, 127.7,
(70%). 1H NMR (600 MHz, CDCl3): δ = 9.66 (s, 1H), 8.13 (dd, J1 127.3, 125.2, 21.5.
= 9.6 Hz, J2 = 5.4 Hz, 1H), 7.51–7.48 (m, 1H), 7.39 (t, J = 7.2 Hz,
4-Phenyl-3-(phenylsulfonyl)quinolone (3ab).7a Yield:
1H), 7.27 (t, J = 7.8 Hz, 2H), 7.12 (d, J = 8.4 Hz, 2H), 6.98 (d, J = 57.3 mg (83%). 1H NMR (600 MHz, CDCl3): δ = 9.82 (s, 1H),
7.8 Hz, 2H), 6.87–6.83 (m, 3H), 2.27 (s, 3H); 13C NMR 8.22 (d, J = 9.0 Hz, 1H), 7.84–7.82 (m, 1H), 7.47–7.44 (m, 3H),
(150 MHz, CDCl3): δ = 161.0 (d, J = 249.3 Hz), 149.1 (d, J = 6.0 7.35–7.31 (m, 5H), 7.27–7.25 (m, 2H), 6.94 (d, J = 7.8 Hz, 2H);
Hz), 147.1 (d, J = 1.5 Hz), 146.8, 144.2, 137.6, 133.4, 132.2, 13C NMR (150 MHz, CDCl3): δ = 150.0, 149.8, 147.7, 140.8,
132.2, 129.8, 129.2, 128.9, 128.6 (d, J = 10.5 Hz), 127.9, 127.8, 133.0, 132.5, 132.3, 132.2, 130.0, 129.7, 128.6, 128.6, 127.8,
122.4 (d, J = 27.0 Hz), 110.6 (d, J = 24.0 Hz), 21.5. 19F NMR 127.8, 127.7, 127.5, 127.4.
(564 MHz, CDCl3): δ = −109.67.
3-((4-(tert-Butyl)phenyl)sulfonyl)-4-phenylquinoline
(3ac).
1
6-Chloro-4-phenyl-3-tosylquinoline (3pa).7a Yield: 55.2 mg Yield: 69.9 mg (87%). H NMR (600 MHz, CDCl3): δ = 9.80 (s,
1
(70%). H NMR (600 MHz, CDCl3): δ = 9.77 (s, 1H), 8.15 (d, J = 1H), 8.21 (d, J = 8.4 Hz, 1H), 7.81 (t, J = 7.8 Hz, 1H), 7.45 (t, J =
9.0 Hz, 1H), 7.74 (dd, J1 = 9.0 Hz, J2 = 2.4 Hz, 1H), 7.49 (t, J = 7.8 Hz, 2H), 7.34–7.29 (m, 3H), 7.27–7.25 (m, 4H), 6.95 (d, J =
7.8 Hz, 1H), 7.36 (t, J = 7.8 Hz, 2H), 7.28 (d, J = 2.4 Hz, 1H), 7.2 Hz, 2H), 1.29 (s, 9H); 13C NMR (150 MHz, CDCl3): δ =
7.20 (d, J = 8.4 Hz, 2H), 7.06 (d, J = 7.8 Hz, 2H), 6.96–6.94 (m, 156.9, 149.7, 147.6, 137.7, 132.7, 132.6, 132.1, 130.0, 129.6,
2H), 2.36 (s, 3H); 13C NMR (150 MHz, CDCl3): δ = 148.9, 148.1, 128.5, 127.7, 127.7, 127.6, 127.4, 127.3, 125.6, 35.1, 31.0.
148.0, 144.2, 137.7, 134.0, 133.6, 132.9, 132.0, 131.3, 129.9, HRMS (ESI) ([M + H]+) calcd for C25H23NO2S: 402.1522, found:
129.3, 128.9, 128.3, 127.9, 127.8, 126.0, 21.5.
402.1523.
6-Bromo-4-phenyl-3-tosylquinoline (3qa).7a Yield: 71.0 mg
3-((4-Fluorophenyl)sulfonyl)-4-phenylquinoline (3ad).7a
1
1
(81%). H NMR (600 MHz, CDCl3): δ = 9.78 (s, 1H), 8.08 (d, J = Yield: 59.6 mg (82%). H NMR (600 MHz, CDCl3): δ = 9.80 (s,
9.0 Hz, 1H), 7.87 (dd, J1 = 9.0 Hz, J2 = 1.8 Hz, 1H), 7.49 (t, J = 1H), 8.23 (d, J = 8.4 Hz, 1H), 7.86–7.83 (m, 1H), 7.50–7.47 (m,
7.8 Hz, 1H), 7.45 (d, J = 1.8 Hz, 1H), 7.36 (t, J = 7.8 Hz, 2H), 2H), 7.38–7.34 (m, 3H), 7.33–7.30 (m, 2H), 6.97 (d, J = 7.2 Hz,
7.19 (d, J = 8.4 Hz, 2H), 7.06 (d, J = 7.8 Hz, 2H), 6.95 (d, J = 7.2 2H), 6.93 (t, J = 8.4 Hz, 2H); 13C NMR (150 MHz, CDCl3): δ =
Hz, 2H), 2.36 (s, 3H); 13C NMR (150 MHz, CDCl3): δ = 148.8, 165.2 (d, J = 255.0 Hz), 149.8 (d, J = 13.5 Hz), 147.4, 136.7 (d, J
148.3, 148.1, 144.2, 137.6, 135.5, 133.5, 131.8, 131.3, 129.9, = 3.0 Hz), 132.4, 132.3, 132.2, 130.7 (d, J = 9 Hz), 130.0, 129.7,
129.3, 129.0, 128.7, 127.9, 127.8, 122.2, 21.5.
129.3, 128.8, 128.0, 127.8, 127.3, 122.0, 115.8 (d, J = 22.5 Hz).
Yield: 19F NMR (564 MHz, CDCl3): δ = −103.89.
4-Phenyl-3-tosylquinoline-6-carbonitrile
(3ra).7a
60.8 mg (79%). 1H NMR (600 MHz, CDCl3): δ = 9.89 (s, 1H),
3-((4-Chlorophenyl)sulfonyl)-4-phenylquinoline (3ae).7a
1
8.31 (d, J = 9.0 Hz, 1H), 7.95 (dd, J1 = 9.0 Hz, J2 = 1.8 Hz, 1H), Yield: 60.8 mg (80%). H NMR (600 MHz, CDCl3): δ = 9.79 (s,
7.73 (d, J = 1.8 Hz, 1H), 7.54 (t, J = 7.8 Hz, 1H), 7.39 (t, J = 7.8 1H), 8.23 (d, J = 8.4 Hz, 1H), 7.84 (t, J = 7.8 Hz, 1H), 7.50–7.47
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(m, 2H), 7.38–7.34 (m, 3H), 7.24–7.21 (m, 4H), 6.97 (d, J = 7.2 2H), 6.99–6.98 (m, 1H), 6.87–6.85 (m, 1H); 13C NMR (150 MHz,
Hz, 2H); 13C NMR (150 MHz, CDCl3): δ = 149.9, 149.9, 147.4, CDCl3): δ = 149.9, 149.7, 147.4, 142.0, 134.5, 134.2, 132.8,
139.7, 139.3, 132.4, 132.0, 130.1, 129.7, 129.3, 128.8, 128.0, 132.6, 132.3, 129.8, 129.6, 128.8, 127.9, 127.8, 127.5, 127.4,
127.8, 127.4, 127.3.
127.2.
3-((4-Bromophenyl)sulfonyl)-4-phenylquinoline (3af).7a Yield:
66.2 mg (78%). 1H NMR (600 MHz, CDCl3): δ = 9.79 (s, 1H),
8.22 (d, J = 8.4 Hz, 1H), 7.84 (t, J = 7.8 Hz, 1H), 7.50–7.46 (m, Conflicts of interest
2H), 7.39–7.34 (m, 5H), 7.16 (d, J = 8.4 Hz, 2H), 6.97 (d, J = 7.8
There are no conflicts to declare.
Hz, 2H); 13C NMR (150 MHz, CDCl3): δ = 149.9, 149.8, 147.4,
139.8, 132.4, 132.0, 131.8, 130.0, 129.7, 129.3, 128.8, 128.3,
128.0, 127.8, 127.3, 127.3.
4-((4-Phenylquinolin-3-yl)sulfonyl)benzonitrile (3ag).7b Yield:
56.3 mg (76%). 1H NMR (600 MHz, CDCl3): δ = 9.80 (s, 1H),
8.25 (d, J = 8.4 Hz, 1H), 7.87 (t, J = 7.2 Hz, 1H), 7.55–7.53 (m,
2H), 7.50–7.49 (m, 2H), 7.41–7.40 (m, 2H), 7.35–7.34 (m, 3H),
6.95–6.94 (m, 2H); 13C NMR (150 MHz, CDCl3): δ = 150.2,
150.1, 147.2, 144.8, 132.8, 132.2, 132.2, 131.2, 130.1, 129.8,
129.1, 128.4, 128.2, 127.9, 127.4, 127.2, 117.1, 116.5.
Acknowledgements
We gratefully acknowledge the National Natural Science
Foundation of China (21901081 and 22071171) and the
Natural Science Foundation of Anhui Province (2008085QB90)
for financial support.
4-Phenyl-3-(m-tolylsulfonyl)quinolone (3ah).7c Yield: 57.5 mg
Notes and references
1
(80%). H NMR (600 MHz, CDCl3): δ = 9.82 (s, 1H), 8.21 (d, J =
9.0 Hz, 1H), 7.82 (t, J = 7.2 Hz, 1H), 7.48–7.44 (m, 2H),
7.35–7.32 (m, 3H), 7.26–7.25 (m, 1H), 7.16–7.15 (m, 2H), 7.05
(s, 1H), 6.95 (d, J = 7.8 Hz, 2H), 2.23 (s, 3H); 13C NMR
(150 MHz, CDCl3): δ = 149.8, 149.6, 147.4, 140.3, 138.6, 133.8,
132.4, 132.3, 132.1, 129.9, 129.5, 128.5, 128.4, 128.2, 127.7,
127.5, 127.3, 127.3, 124.8, 21.0.
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3-((3-Chlorophenyl)sulfonyl)-4-phenylquinoline (3ai).7c Yield:
60.0 mg (79%). 1H NMR (600 MHz, CDCl3): δ = 9.80 (s, 1H),
8.22 (d, J = 8.4 Hz, 1H), 7.86–7.83 (m, 1H), 7.53–7.47 (m, 2H),
7.43–7.41 (m, 1H), 7.38–7.36 (m, 3H), 7.27–7.21 (m, 2H),
7.16–7.15 (m, 1H), 6.97–6.95 (m, 2H); 13C NMR (150 MHz,
CDCl3): δ = 150.0, 149.8, 147.2, 142.2, 134.6, 133.1, 132.4,
131.9, 131.8, 129.9, 129.9, 129.6, 129.0, 128.0, 127.9, 127.7,
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55.5 mg (73%). 1H NMR (600 MHz, CDCl3): δ = 9.85 (s, 1H),
8.25 (d, J = 8.4 Hz, 1H), 7.85 (t, J = 7.2 Hz, 1H), 7.47 (t, J = 7.8
Hz, 1H), 7.38–7.36 (m, 1H), 7.33–7.31 (m, 2H), 7.30–7.26 (m,
2H), 7.18 (t, J = 7.2 Hz, 2H), 7.02 (t, J = 7.8 Hz, 1H), 6.91 (d, J =
7.8 Hz, 2H); 13C NMR (150 MHz, CDCl3): δ = 149.7, 149.4,
148.6, 138.0, 134.2, 132.3, 132.0, 131.8, 131.5, 131.1, 131.0,
129.8, 129.7, 128.7, 127.9, 127.6, 127.4, 127.2, 126.8.
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3-(Naphthalen-2-ylsulfonyl)-4-phenylquinoline (3ak).7a Yield:
61.7 mg (78%). 1H NMR (600 MHz, CDCl3): δ = 9.80 (s, 1H),
8.13 (d, J = 8.4 Hz, 1H), 7.74–7.71 (m, 2H), 7.65–7.62 (m,
2H), 7.58 (d, J = 7.8 Hz, 1H), 7.53–7.51 (m, 1H), 7.48–7.45 (m,
1H), 7.35–7.32 (m, 2H), 7.30–7.27 (m, 1H), 7.22–7.21 (m, 1H),
7.09 (t, J = 7.8 Hz, 2H), 6.78 (dd, J1 = 8.4 Hz, J2 = 1.3 Hz, 2H);
13C NMR (150 MHz, CDCl3): δ = 150.2, 149.8, 147.8, 137.3,
134.8, 132.4, 132.3, 132.2, 131.7, 130.2, 130.0, 129.7, 129.5,
129.2, 129.0, 128.9, 127.9, 127.8, 127.6, 127.5, 127.5, 127.4,
122.4.
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4-Phenyl-3-(thiophen-2-ylsulfonyl)quinolone (3al).7c Yield:
52.7 mg (75%). 1H NMR (600 MHz, CDCl3): δ = 9.74 (s, 1H),
8.22 (d, J = 8.4 Hz, 1H), 7.84 (t, J = 7.8 Hz, 1H), 7.55–7.54 (m,
1H), 7.51–7.43 (m, 2H), 7.43–7.37 (m, 3H), 7.10 (d, J = 7.2 Hz,
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