RETRACTED ARTICLE: Design, synthesis, and biological evaluation of heterotetracyclic quinolinone derivatives as anticancer agents targeting topoisomerases

Article abstract of DOI:10.1016/j.ejmech.2020.112074

A series of thiochromeno[2,3-c]quinolin-12-one derivatives with various substitutions were synthesized and evaluated as topoisomerase (Topo) inhibitors. Six (8, 10, 12, 14, 19, and 26) of 23 compounds showed strong inhibitory activities against Topo-media

Full text of DOI:10.1016/j.ejmech.2020.112074

Journal Pre-proof
Design, synthesis, and biological evaluation of heterotetracyclic quinolinone
derivatives as anticancer agents targeting topoisomerases
Jiann-Fong Lee, Ting-Yu Chang, Zheng-Fang Liu, Nian-Zhe Lee, Yen-Hsiu Yeh, Yi-
Song Chen, Tsung-Chih Chen, Hao-Syun Chou, Tsai-Kun Li, Sung-Bau Lee, Mei-
Hsiang Lin
PII:
S0223-5234(20)30041-6
DOI:
https://doi.org/10.1016/j.ejmech.2020.112074
EJMECH 112074
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 17 October 2019
Revised Date: 24 December 2019
Accepted Date: 14 January 2020
Please cite this article as: J.-F. Lee, T.-Y. Chang, Z.-F. Liu, N.-Z. Lee, Y.-H. Yeh, Y.-S. Chen, T.-
C. Chen, H.-S. Chou, T.-K. Li, S.-B. Lee, M.-H. Lin, Design, synthesis, and biological evaluation of
heterotetracyclic quinolinone derivatives as anticancer agents targeting topoisomerases, European
Journal of Medicinal Chemistry (2020), doi: https://doi.org/10.1016/j.ejmech.2020.112074.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition
of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of
record. This version will undergo additional copyediting, typesetting and review before it is published
in its final form, but we are providing this version to give early visibility of the article. Please note that,
during the production process, errors may be discovered which could affect the content, and all legal
disclaimers that apply to the journal pertain.
© 2020 Published by Elsevier Masson SAS.

Graphic Abstract
MCF-10A
Control
#26
MDA-MB-231
Control
30
20
10
0
15
10
5
#26
0
26
0
24 48
hours
72
0
24
48
72
hours
26
VP-16
10 (μM)
26
CPT
0.4 10 (μM)
10
3
+
1
+
10
+
3
+
1
+
TOPO II
-
+
+
+
TOPO I
-
+
+
+
Relaxed
Relaxed
Supercoiled
Supercoiled

European Journal of Medicinal Chemistry
Design, synthesis, and biological evaluation of heterotetracyclic quinolinone
derivatives as anticancer agents targeting topoisomerases
Jiann-Fong Leea,b*, Ting-Yu Changc*, Zheng-Fang Liud*, Nian-Zhe Leed, Yen-Hsiu
Yehe, Yi-Song Chene, Tsung-Chih Chenf, Hao-Syun Chouf, Tsai-Kun Lie, Sung-Bau
Leec,d‡, Mei-Hsiang Lina‡
a
School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei,
Taiwan
b School of Pharmacy, National Defense Medical Center, Taipei, Taiwan
c
PhD Program in Biotechnology Research and Development, Taipei Medical
University, Taipei, Taiwan
d Master Program in Clinical Pharmacogenomics and Pharmacoproteomics, Taipei
Medical University, Taipei, Taiwan
e
Graduate Institute of Microbiology, College of Medicine, National Taiwan
University, Taipei, Taiwan
f 3SM Biotron, Taipei, Taiwan
*These authors contributed equally to this work
‡To whom correspondence should be addressed:
S. B. Lee: (Phone) 886-2-7361661 ext. 6107; (e-mail) sbl@tmu.edu.tw
M. H. Lin: (Phone) 886-2-7361661 ext. 6138; (e-mail) mhl00001@tmu.edu.tw;

Abstract
A series of thiochromeno[2,3-c]quinolin-12-one derivatives with various
substitutions were synthesized and evaluated as topoisomerase (Topo) inhibitors. Six
(8, 10, 12, 14, 19, and 26) of 23 compounds showed strong inhibitory activities
against Topo-mediated DNA relaxation and proliferation of five human cell lines
including breast (MDA-MB-231, MDA-MB-468 and MCF7), colorectal (HCT116)
and non-small cell lung (H1299) cancers. Among these, compounds 14 and 26
exhibited full inhibitory activities against Topo I at 3 µM and Topo IIα at 1 µM.
Cancer cells treated with 26 accumulated DNA damage and were arrested at the
G2/M phase. With time, cells proceeded to apoptosis, as revealed by increased
amounts of cells with fragmented DNA and cleavage of caspase-8 and -9. In contrast,
normal breast epithelial cells showed low sensitivity to 26. Taken together, our study
identifies 26 as a potent Topo dual-inhibitor with low toxicity to normal cells, and
elucidates that the terminal amino group of N-2-aminoethylamino or
N-3-aminopropylamino at the 6th position and 8,10-di-halogen substituents on
thiochromeno[2,3-c]quinolin-12-one are critical for the Topo-inhibiting and
cancer-killing activities.
Keywords: thiochromeno[2,3-c]quinolin-12-one, topoisomerase, dual inhibitor

1. Introduction
Cancer is defined as malignant cells that divide out of control and can invade and
spread to other tissues. Cancer cells thus possess high levels of stress generated from
various cellular metabolic pathways that are essential for cell growth. To bypass these
impediments for survival, cancer cells highly rely on mechanisms that can overcome
such problems [1]. During genome replication, segregation, transcription and
recombination, the super-helical doubled-stranded DNA needs to be unwound for
factor accessibility. This in turn triggers over-winding of downstream DNA that
prevents the metabolic event from moving forward [2]. Topoisomerases (Topos) are
the key factors that resolve the topologic stresses. In mammals, Topo I and II
respectively create single- and double-strand DNA breaks, which allows the passage
or rotation of the unbroken DNA through sites of breakage and thus relieves the
stresses due to DNA hyper-winding. Through transesterification, Topo transiently
forms a covalent binary complex with one broken end of DNA. After supercoil
disengagement, another broken end of DNA nucleophilically attacks the protein-DNA
bond, followed by re-ligation of the two DNA ends and release of Topo [2, 3].
Given that suppressing Topo activity can hinder genome functions, jeopardize
chromosome stability, and therefore trigger deleterious cytotoxicity, several agents
targeting Topos have been developed and used in clinic as cancer therapeutics [4, 5].

Among these agents, Topo poisons disturb Topo functions by binding and stabilizing
the covalently linked enzyme-DNA complex to limit DNA re-ligation. This generates
toxic DNA lesions in collision with replication/transcription machineries or when
chromosomes are segregating, ultimately leading to cell apoptosis ([3]and references
therein). Many Topo poisons, such as camptothecin (CPT), podophyllotoxin and
anthracycline, are derived from natural products. CPT is a well-known Topo
I-specific poison with a planar pentacyclic structure. However, its insolubility and
instability have limited its clinical evaluation [6, 7]. Subsequently synthesized
water-soluble analogs irinotecan and topotecan were approved by the US Food and
Drug Administration (FDA), but the dose-dependent toxicities like neutropenia and
diarrhea are still observed [7]. FDA-approved Topo II poisons include
etoposide/teniposide and doxorubicin/daunorubicin, which respectively are
podophyllotoxin and anthracycline drugs [7]. Although these drugs have been in
long-term use in cancer chemotherapeutics, severe cardiac toxicity and secondary
malignancies, possibly resulting from inhibition of the Topo IIβ isoform and
generation of reactive oxygen species, are the main challenges in their use as
medications [8-10]. The emerging Topo II inhibitor pixantrone, an anthracenedione
agent structurally closed to mitoxantrone, exhibits a higher inhibitory activity toward
Topo IIα than IIβ and a reduced iron-binding ability [11, 12], potentially providing a

safer way to avoid side effects that result from anthracycline treatment.
Several studies have made great efforts to discover agents with dual
Topo-inhibitory activities [13-16]. Topopyrones, the anthraquinone polyphenols
initially identified from fungal culture broths, possess poisonous activity toward Topo
I and IIα, which relies on the orientation of the 1,4-pyrone ring moiety and the chloro
substituent at C7 [14, 17, 18]. In addition, the naturally occurring
quinazoline-carboline alkaloid evodiamine and its derivative, thio-evodiamine, were
shown to interfere with relaxation of supercoiled DNA by both Topos probably
through a non-poison mechanism [19, 20]. Recently, Chen et al. synthesized and
evaluated a series of tetracyclic heterocyclic azathioxanthone compounds [13,
21-23]. Most of these compounds, unfortunately, exhibited weak Topo-inhibitory
activities and no or low toxicity in over 60 tested cell lines. Only
10-chloro-6-(piperazin-1-yl)-12H-thiochromeno[2,3-c]quinolin-12-one
(CPTQ)
showed a significant cytotoxicity, with IC50 values of 5.01 ± 1.68 µM in DU-145
cells and 2.84 ± 0.64 µM in PC-3 cells. CPTQ displayed dual inhibitory activities at
10 and 25 µM to Topo I and IIα, respectively [13]. According to clues, further
structural optimization is thus required for new drug development.
In this study, we based on the scaffold structure of CPTQ to design and
synthesize a series of thiochromeno[2,3-c]quinolin-12-one derivatives with various

substituents. A variety of substituents are summarized in Figure 1 and Chart 1. Our
work reveals that the amino end (-NH2) of the ethyl/propyl chain substituted at the 6th
position together with 8,10-dual halogen substituents contribute to the high
cytotoxicity and dual Topo inhibition. This study also discoveries 26 as a potent
anticancer agent with low toxicity to normal cells.
2. Chemistry
The synthesis processes of target compounds 5~27 were shown in Scheme 1. The
starting compound, 2- or 4-substituted thiophenol, was reacted with chloroacetic acid
in NaOH (aq) to give substituted phenylthioacetic acids 2a~2i. The phenylthioacetic
acid compounds were treated with isatin in the presence of sodium acetate in the
process of the Pfitzinger reaction while being heated to 150 °C for 1~5 h to obtain
intermediate
quinoline-4-carboxylic
acids
3a~3i.
These
intermediates,
thiochromeno[2,3-c]quinolin-12-ones 4a~4i, were produced from cyclization and
chlorination of quinolone-4-carboxylic acids reacted with POCl3. The title compounds
5 and 7~27 were afforded via substitution of compounds 4a~4i with various
appropriate amines in dimethyl sulfoxide. Compound 6 was yielded from compound 5
via debenzylation by trifluoroacetic acid (TFA), followed by an amide coupling
reaction. Analytical purification of each product was achieved by silica gel

chromatography. All new compounds were characterized and determined by nuclear
magnetic resonance (NMR), High-resolution mass spectrometry (HRMS), and high
pressure liquid chromatography (HPLC). The yields of title compounds 5~27 from
compounds 4a~4i are listed in Chart 1. We observed that compounds 26 and 27 had
low yields, which may be because of the presence of dual halogens, F and Cl, on C8
and C10, respectively. Given that these atoms belong to deactivating groups, the
reactivity is typically lower than other substituents, such as methyl and methoxy. This
probably makes it difficult to produce compounds possessing such substituents,
especially ones possessing both, like 26 and 27. Moreover, to obtain purified products,
we needed to repeat the purification process several times, which further lowered the
yields of these compounds.
3. Biological evaluation
3.1. Quick compound selection
Our synthesized thiochromeno[2,3-c]quinolin-12-one derivatives were
previously found to suppress FMS-like tyrosine kinase 3 (FLT-3), a receptor tyrosine
kinase [24]. However, their inhibitory activities toward FLT-3 in vitro did not
correlate with the cytotoxicities ([24] and unpublished data), suggesting that FLT-3
is not the main target of these compounds in cells. CPTQ, the compound with a

similar scaffold structure as our synthesized compounds, was reported to inhibit
Topo I at 10 µM in vitro [13]. We thus evaluated our compounds by determining the
efficiency of in vitro Topo I-mediated relaxation of the supercoiled plasmid DNA at
10 µM. CPT was used as a positive control in this assay. As shown in Figure 2A, six
(8, 10, 12, 14, 19, and 26) of our designed compounds almost completely suppressed
Topo I activity, whereas CPT exhibited only a partial inhibitory activity against
Topo I at 10 µM.
We then assayed the in vitro cytotoxicity of our compounds. We primarily
focused on triple-negative breast cancers (TNBCs) as they are often highly malignant
and lack efficient therapeutics. MDA-MB-231 cells were treated with 10 µM of each
compound, followed by an analysis of cell survival through measuring the cellular
NAD(P)H-dependent oxidoreductase activity. As shown in Figure 2B, about three
quarters of these thiochromeno[2,3-c]quinolin-12-one derivatives exhibited moderate
cytotoxic activities. Seven (6, 11, 13, 15, 16, 22, and 23) were able to reduce <20% of
cell viability, whereas ten (5, 7, 9, 17, 18, 20, 21, 24, 25, and 27) were able to reduce
21~40% of cell viability. We found that alkylamino and benzylamino groups at the C6
are more potent than picolinamido group (7≒5>6). In addition, chloro group on
position 10 of thiochromeno[2,3-c]quinolin-12-one had higher impact on cytotoxicity
than positions 8 (R1), 9 (R2) and 11 (R4) (7>15≒16≒13). Moreover, substituents of

electron-attracting halogens at the C10 were more toxic than electron-donating methyl
and methoxy groups, with the following sequence: Cl ≒ F > CH3 > OCH3
(7≒9>20>11). In contrast, substitution at the C8 by either OCH3 or Cl behaved more
active than F (24≒27>22).
Strikingly, six compounds (8, 10, 12, 14, 19, and 26) with strong Topo I-
suppressing activities (Figure 2A) displayed a very high cytotoxicity, reducing more
than 95% viability at 10 µM. The latter six compounds possess a terminal amino
group on propylamino or ethylamino side chain substituted on C6 (R5) of
thiochromeno[2,3-c]quinolin-12-one. These results indicate that this amino group is
essential for Topo inhibition and cytotoxicity, suggesting that the side chain may
contribute to a special interaction with the Topo I.
3.2. In vitro anti-proliferation activities
Next, we assessed the anticancer potency of the selected compounds in five
human cell lines from breast cancers (MDA-MB-231, MDA-MB-468 and MCF7),
colorectal cancer (HCT116) and non-small cell lung carcinoma (H1299) by
measuring the values of the half-maximal inhibitory concentration (IC50). As shown
in Table 1, these six compounds exhibited strong anti-proliferation activities, and
two TNBC lines (MDA-MB-231 and MDA-MB-468) were more susceptible to

these compounds compared to MCF7, HCT116 and H1299 cells. This suggests that
different cell types or expression levels of receptors for estrogen or progesterone
may contribute to the compound sensitivity of cells. Consistent with previous results
(Figure 2B), substituents of electron-attracting halogens at C10 produced better
cytotoxicity than the electron-donating methyl and methoxy groups (8, 10 >12, 19)
in all test cell lines. It is worthy to note that compound 14 showed a greater activity
than compound 8, perhaps because of the chlorine group existed at C8. Accordingly,
compound 26 with 8,10-di electron-attracting halogens exhibited the strongest and
non-differential toxicities in all tested cell lines, with IC50 values of 1.14±0.04,
0.22±0.04, 0.80±0.21, 0.53±0.31 and 0.53±0.08 µM in MDA-MB-231,
MDA-MB-468, MCF7, HCT116 and H1299 cells, respectively. The inhibition of
DNA relaxation catalyzed by Topo I and IIα by these six potent compounds were
further evaluated in detail, as both enzymes were found to be oncogenes in several
cancers, and Topo IIα is generally highly expressed in proliferating and tumor cells
[25-27].
3.3. Topo inhibition
We determined the lowest concentration of selected compounds inhibiting
Topo-mediated DNA relaxation. We showed that compounds 8, 10, 12, and 19 fully

suppressed Topo I at 10 µM and displayed a partial inhibitory activity at 3 µM
(Figure 3A). Importantly, compounds 14 and 26, the two most toxic derivatives, had
at least 3-fold higher activity of Topo inhibition compared to the other selected
compounds, sharply and partially inhibiting Topo I at 3 and 1 µM, respectively
(Figure 3A). Similar results were obtained from assays of Topo IIα inhibitory
activity. All six selected compounds strongly reduced DNA relaxation by Topo IIα
at 3 µM, and compounds 14 and 26 exhibited full inhibitory activity against Topo
IIα even at 1 µM (Figure 3B). These results indicate that the Topo-suppressive
activities of these compounds are highly correlated with their cytotoxicity. These
structure-activity relationship (SAR) results were summarized in Figure 3C.
To determine if the new compounds are Topo poisons that stabilize the Topo-DNA complex, we p
relaxation, leading to accumulation of supercoiled DNA. The mobility of the
accumulated DNA was reduced, as shown by band up-shifting, when Topo I
remained during gel electrophoresis. Increasing the amount of 26 further restricted
DNA mobility and gave rise to DNA stuck in wells (Figure 4A). Moreover, we
observed that levels of Topo I and IIα loading on chromatin significantly increased
when cells were treated with 26 (Figure 4B). These findings strongly suggest that 26
functions as a poison that traps topoisomerases on DNA, perhaps stabilizing the
cleavage intermediates and preventing DNA re-ligation.

3.4. Anti-proliferation activities in MDA-MB-231 and MCF-10A cells
Both growth efficiency and cell death can contribute to cell viability. We thus
measured DNA content using propidium iodide (PI) staining to monitor the status of
MDA-MB-231 cells treated with the most potent compounds, 14 and 26, followed by
flow cytometric analysis. Figure 5A shows that, 24 hours after compound treatment,
a large portion of cells treated with 26 at 4 µM accumulated in the sub-G1 phase
with fragmented DNA, indicative of cell death. This phenotype was also observed
when cells were treated with 20 µM of 14 (Figure 5A). We further examined the
cleaved caspases, the active forms in mammalian apoptosis pathways, and found
that treatment of 26 clearly triggered cleavages of caspase-8 and -9 (Figure 5B).
To compare the toxicities of 26 in normal and cancer cells, we examined
proliferation of MDA-MB-231 breast cancer cells and the normal MCF-10A
epithelial cells in the absence and presence of 26. As shown in Figure 5C, treatment
with 26 completely stopped proliferation of MDA-MB-231 cells, whereas MCF-10A
cells displayed only a weak response to 26, showing a slight reduction in the growth
rate (Figure 5C). Consistently, FACS analysis showed that treatment with 26
increased the sub-G1 population in MDA-MB-231 but not MCF-10A cells (Figure
5D). These results indicate that 26 is a potent cancer-killing tetracyclic heterocyclic

azathioxanthone with low toxicity to normal cells.
3.5. Mitotic arrest and DNA damage
Topo inhibition was found to interfere with chromosome segregation in mitosis
due to accumulation of DNA lesions [28, 29]. To specifically assess cell cycle
progression, we synchronized cells in the early-S phase with a high concentration of
thymidine and then treated cells with 26 two hours after release from thymidine
blockage (T2). The untreated cells reached the G2/M phase and the subsequent G1
phase 8 and 12 h after release (T8 and T12), respectively (Figure 6A). In contrast,
upon treatment with 26, most cells failed to exit mitosis, remaining in the G2/M
phase at T12. Consistent with the observations from asynchronized cells (Figure 5A),
the sub-G1 population largely increased after long-term treatment with 26 (T24;
Figure 6A). In addition, we detected the phosphorylation of Ser 139 of histone
H2AX (γH2AX), a marker of DNA damage, in 26-treated cells (Figure 6B). These
results indicate that 26 triggers DNA damage and impairs mitosis, further supporting
that 26 behaves as a Topo inhibitor in cells.
4. Conclusions
We designed and synthesized a series of tetracyclic azathioxanthones targeting

both Topo I and IIα. Six compounds were found to effectively suppress proliferation
of cancer cells and activity of Topos, indicating that the terminal amino group of
6-N-2-aminoethylamino or 6-N-3-aminopropylamino is important for topo targeting.
In addition, 14 and 26 exhibited strong inhibitory activities against Topos and 26
showed the highest cytotoxicity. These reveal that dual modifications of
electron-attracting halogens at C8 and C10 (8-chloro and 10-fluoro) can significantly
enhance anti-cancer effect of thiochromeno[2,3-c]quinolin-12-ones.Production of
these desired compounds, however, is in a very lower yield, which remains to be
resolved in the future. Our data show that 26 is a potent anticancer agent with low
toxicity to normal cells. Treatment with 26 in cancer cells triggered DNA damage
and impaired mitosis, ultimately leading to apoptosis. Further detailed molecular
pharmacological studies examining derivative 26 are currently underway.
5. Materials and methods
5.1. Chemistry
All materials were commercially available and purchased from Sigma-Aldrich
and Merck without further purification. The reaction was monitored using thin layer
chromatography (TLC) as performed with Merck silica gel 60 coated with the F254
fluorescent indicator. Nuclear magnetic resonance (NMR) spectra were recorded on

Agilent 400 MR DD2 (400 MHz), Bruker: Avance DRX (500 MHz), and Agilent (600
MHz DD2 NMR) using DMSO-d6, CDCl3, and CF3COOD as deuterated solvents.
Multiplicities were recorded as singlet (s), doublet (d), triplet (t), quartet (q), quintet
(quin), sextet, and double doublet (dd). Coupling constants (J) are indicated in Hz.
Liquid chromatography (LC)-MS analysis of compounds was conducted as per one of
the following methods: Column: Symmetry- C18 4.6 x 75 mm, 3.5 µm; wavelength:
254 nm; flow: 0.8 mL/min; run time: 12 min; time (in min) and mobile
phase-gradient/B (%): 0/50, 3/95, 9/95, 10/50, 12/50 [B: Acetonitrile;
A: Ammonium formate (20 mmol in water)]; LC-Agilent technologies- 1260 Infinity
II Series; MASS: Agilent technologies- 6120 Quadrupole LC/MS-API-ESI. Spectral
data of MS are recorded as m/z values. High-resolution mass spectra (HRMS) were
recorded with a JEOL (JMS-700) electron impact (EI) mass spectrometer.
5.2.1. Synthesis of compounds 3a~3i
Step 1: An aqueous solution of chloroacetic acid (1.1 eq.) and aq. NaOH (3.0 eq.
dissolved in ~2 vol. of water) were simultaneously added to a solution of
corresponding substituted thiophenol (1.0 eq.) in water, and the mixture was heated to
50 °C for 4~5 hours. After completing the reaction, as monitored by TLC, the reaction
mixture was cooled to room temperature and slowly diluted with 5 N HCl (pH 4~5).

The resulting suspension was filtered, washed with dilute acidic water, and
vacuum-dried to afford compounds 2a~2i as off-white solids.
Step 2: A mixture of isatin (0.9 eq.), 2a~2i (1.0 eq.), and sodium acetate (0.2 eq.) in
acetic acid (4~5 vol.) was heated at 150 °C for 24 hours. After cooling, the solid
formed was suspended in acetic acid (10 vol.), filtered and washed with acetic
acid/water (1:9) to remove unreacted isatin. The remaining solid was again washed
with water and dried under a vacuum to afford compounds 3a~3i.
5.2.1.1. 3-((4-Chlorophenyl)thio)-2-hydroxyquinoline-4-carboxylic acid (3a). Physical
data of compound 3a matched those of a previous report [13].
5.2.1.2. 3-((4-Fluorophenyl)thio)-2-hydroxyquinoline-4-carboxylic acid (3b). 1H
NMR (500 MHz, DMSO6) δ 12.16 (s, 1H), 7.59 (t, J = 8.0 Hz, 1H), 7.44 (d, J = 7.5
Hz, 1H), 7.38 (d, J = 8.0 Hz, 1H), 7.33 (d, J = 9.0 Hz, 1H), 7.32 (d, J = 8.5 Hz, 1H),
7.27 (t, J = 8.0 Hz, 1H), 7.11 (t, J = 9.0 Hz, 1H).
1
5.2.1.3. 2-Hydroxy-3-((4-methoxyphenyl)thio)quinoline-4-carboxylic acid (3c). H
NMR (500 MHz, DMSO-d6) δ 12.08 (s, 1H), 7.57 (t, J = 7.5 Hz, 1H), 7.43 (d, J = 7.5
Hz, 1H), 7.36 (d, J = 8.5 Hz, 1H), 7.31 (d, J = 9.0 Hz, 2H), 7.26 (t, J = 7.5 Hz, 1H),

6.86 (d, J = 9.0 Hz, 2H), 3.69 (s, 3H).
5.2.1.4. 3-((2-Chlorophenyl)thio)-2-hydroxyquinoline-4-carboxylic acid (3d). 1H
NMR (500 MHz, DMSO-d6) δ 12.33 (s, 1H), 7.65 (t, J = 7.5 Hz, 1H), 7.49~7.44 (m,
3H), 7.30 (t, J = 8.0 Hz, 1H), 7.21~7.16 (m, 2H), 6.90~6.88 (m, 1H).
5.2.1.5. 3-((3-Chlorophenyl)thio)-2-hydroxyquinoline-4-carboxylic acid (3e). 1H
NMR (500 MHz, DMSO-d6) δ 12.26 (s, 1H), 7.63 (td, J = 8.0, 1.0 Hz, 1H), 7.48 (d, J
= 7.5 Hz, 1H), 7.41 (d, J = 8.5 Hz, 1H), 7.32~7.21 (m, 4H), 7.20 (d, J = 7.5 Hz, 1H).
1
5.2.1.6. 2-Hydroxy-3-(p-tolylthio)quinoline-4-carboxylic acid (3f). H NMR (500
MHz, DMSO-d6) δ 12.14 (s, 1H), 7.59 (t, J = 7.5 Hz, 1H), 7.45 (d, J = 8.0 Hz, 1H),
7.38 (d, J = 8.5 Hz, 1H), 7.27 (t, J = 7.5 Hz, 1H), 7.18 (d, J = 8.0 Hz, 2H), 7.38 (d, J =
8.0 Hz, 2H), 2.23 (s, 3H).
5.2.1.7. 3-((2-Fluorophenyl)thio)-2-hydroxyquinoline-4-carboxylic acid (3g). 1H
NMR (500 MHz, DMSO-d6) δ 12.24 (s, 1H), 7.62 (t, J = 8.0 Hz, 1H), 7.47 (d, J = 8.0
Hz, 1H), 7.40 (d, J = 8.0 Hz, 1H), 7.29 (t, J = 7.5 Hz, 1H), 7.25~7.19 (m, 2H),
7.09~7.06 (m, 2H).

1
5.2.1.8. 2-Hydroxy-3-((2-methoxyphenyl)thio)quinoline-4-carboxylic acid (3h). H
NMR (500 MHz, DMSO-d6) δ 14.18 (brs, 1H), 12.22 (s, 1H), 7.62 (t, J = 7.5 Hz, 1H),
7.44 (d, J = 8.0 Hz, 1H), 7.41 (d, J = 8.5 Hz, 1H), 7.28 (t, J = 7.5 Hz, 1H), 7.12 (td, J
= 8.5, 1.5 Hz, 1H), 6.99 (d, J = 8.0 Hz, 1H), 6.80 (t, J = 7.5 Hz, 1H), 6.71 (dd, J = 7.5,
1.0 Hz, 1H), 3.84 (s, 3H).
5.2.1.9. 3-((2-Chloro-4-fluorophenyl)thio)-2-hydroxyquinoline-4-carboxylic acid (3i).
1H NMR (500 MHz, DMSO-d6) δ 14.40 (brs, 1H), 12.31 (s, 1H), 7.64 (t, J = 7.5 Hz,
1H), 7.50 (dd, J = 9.0, 2.5 Hz, 1H), 7.48 (d, J = 9.0 Hz, 1H), 7.42 (d, J = 8.5 Hz, 1H),
7.30 (t, J = 8.0 Hz, 1H), 7.12 (td, J = 8.5, 2.5 Hz, 1H), 7.00 (dd, J = 9.0, 5.5 Hz, 1H).
5.2.2. Synthesis of compounds 4a~4i
A solution of 3a~3i in POCl3 (3~4 vol.) was heated to 160 °C for 48 h. After cooling,
the mixture was carefully poured into ice at 0 °C. The resulting precipitate that
separated out was collected by filtration. The filtered cake was suspended in a 10%
NaHCO3 solution and stirred vigorously for 1 h. The resulting precipitate was
collected and washed with H2O. The crude solid was washed with an EtOAc/THF
mixture (1:1) and vacuum-dried to afford the following scaffold compounds 4a~4i.

5.2.2.1. 6,10-Dichloro-12H-thiochromeno[2,3-c]quinolin-12-one (4a). Physical data
of compound 4a is matched with previously report [13].
1
5.2.2.2. 6-Chloro-10-fluoro-12H-thiochromeno[2,3-c]quinolin-12-one (4b). H NMR
(400 MHz, DMSO-d6) δ 9.52 (d, J = 8.8 Hz, 1H), 8.04 (d, J = 2.8 Hz, 1H), 7.79 (d, J
= 8.4 Hz, 1H), 7.61 (t, J = 8.0 Hz, 1H), 7.57 (d, J = 8.8 Hz, 1H), 7.45 (t, J = 8.0 Hz,
1H), 7.31 (dd, J = 8.8, 2.8 Hz, 1H).
5.2.2.3. 6-Chloro-10-methoxy-12H-thiochromeno[2,3-c]quinolin-12-one (4c). 1H
NMR (500 MHz, CDCl3) δ 9.76~9.74 (m, 1H), 8.09~8.07 (m, 1H), 8.03 (d, J = 3.0 Hz,
1H), 7.78~7.74 (m, 2H), 7.63 (d, J = 9.0 Hz, 1H), 7.34 (dd, J = 9.0, 3.0 Hz, 1H), 3.97
(s, 3H).
1
5.2.2.4. 6,8-Dichloro-12H-thiochromeno[2,3-c]quinolin-12-one (4d). H NMR (500
MHz, CDCl3) δ 9.67 (dd, J = 9.5, 2.0 Hz, 1H), 8.55 (dd, J = 7.5, 1.0 Hz, 1H), 8.11 (dd,
J = 7.5, 1.0 Hz, 1H), 7.83~7.77 (m, 3H), 7.58 (t, J = 7.5 Hz, 1H).
5.2.2.5.
6,9-Dichloro-12H-thiochromeno[2,3-c]quinolin-12-one
(4e1)
and

1
6,11-Dichloro-12H-thiochromeno[2,3-c]quinolin-12-one (4e2). H NMR (500 MHz,
CDCl3) δ 9.67 (dd, J = 8.5, 1.0 Hz, 1H), 8.97 (d, J = 9.0 Hz, 1H), 8.51 (d, J = 8.5 Hz,
1H), 8.08 (dd, J = 9.0, 1.5 Hz, 1H), 8.06 (d, J = 8.0 Hz, 1H), 7.81~7.75 (m, 3H),
7.73~7.70 (m, 2H), 7.62~7.57 (m, 2H), 7.55~7.51 (m, 2H).
1
5.2.2.6. 6-Chloro-10-methyl-12H-thiochromeno[2,3-c]quinolin-12-one (4f). H NMR
(500 MHz, CDCl3) δ 9.68 (dd, J = 8.5, 2.0 Hz, 1H), 8.38 (s, 1H), 8.07 (dd, J = 7.5, 2.0
Hz, 1H), 7.78~7.73 (m, 2H), 7.61 (d, J = 8.5 Hz, 1H), 7.53 (dd, J = 8.0, 1.5 Hz, 1H),
2.52 (s, 3H).
1
5.2.2.7. 6-Chloro-8-fluoro-12H-thiochromeno[2,3-c]quinolin-12-one (4g). H NMR
(500 MHz, CF3COOD) δ 9.75~9.78 (m, 1H), 8.33 (d, J = 8.0 Hz, 1H), 8.34~8.36 (m,
1H), 8.15~8.20 (m, 2H), 7.82~7.86 (m, 1H), 7.71~7.74 (m, 1H); 13C NMR (125 MHz,
CF3COOD) δ 119.83 (d, J = 19.3 Hz), 121.15, 123.27 (d, J = 17.4 Hz), 125.36 (d, J =
3.2 Hz), 125.83, 126.82, 129.91 (d, J = 7.8 Hz), 131.38, 132.88, 133.80, 134.19,
135.46, 137.65, 147.79, 157.75 (d, J = 248.9 Hz), 182.0.
5.2.2.8. 6-Chloro-8-methoxy-12H-thiochromeno[2,3-c]quinolin-12-one (4h). 1H NMR
(500 MHz, CDCl3) δ 9.70 (dd, J = 8.0, 1.5 Hz, 1H), 8.17 (d, J = 8.5 Hz, 1H), 8.07 (dd,

J = 7.5, 1.5 Hz, 1H), 7.75 (ddd, J = 8.0, 7.0, 1.0 Hz, 1H), 7.52 (t, J = 8.0 Hz, 1H),
7.16 (d, J = 8.0 Hz, 1H), 4.06 (s, 3H).
5.2.2.9. 6,8-Dichloro-10-fluoro-12H-thiochromeno[2,3-c]quinolin-12-one (4i). 1H
NMR (500 MHz, CDCl3) δ 9.65 (d, J = 8.0 Hz, 1H), 8.24 (dd, J = 9.0, 2.5 Hz, 1H),
8.10 (dd, J = 9.0, 2.5 Hz, 1H), 7.83~7.76 (m, 2H), 7.60 (dd, J = 7.5, 2.5 Hz, 1H).
5.2.3. Synthesis of compounds 5~27
5.2.3.1.
10-Chloro-6-((4-methoxybenzyl)amino)-12H-thiochromeno[2,3-c]quinolin-12-one (5).
A suspension of 4a (1.0 eq.) in DMSO (4~5 vol.) was added drop-wise to a stirred
solution of (4-methoxyphenyl)methanamine (5.0 eq.) in DMSO (~ 5 vol.) at 120 °C,
and the mixture was maintained at the same temperature for 2~3 hours. After
completion of the reaction, as monitored by TLC, the reaction mixture was cooled to
room temperature (RT) and quenched in water. The resulting precipitate was diluted
with a 10% MeOH/CH2Cl2 mixture and extracted. The aqueous layer was separated,
and then extracted with 10% MeOH/CH2Cl2. The combined organic extract was
washed with brine solution, dried over anhydrous Na2SO4, and then concentrated to
give the crude compounds. The crude mixtures were purified by flash column

chromatography (FCC) using MeOH/CH2Cl2/aq. NH3 mixtures to afford target
compounds as pale-yellow to yellow solids. Yield: 300 mg (92%). ES-MS [M+1]+:
1
432.9; tR: 6.31 min (purity: 94.5%), H NMR (500 MHz, CDCl3): δ 9.44 (d, J = 8.5
Hz, 1H), 8.55 (d, J = 2.5 Hz, 1H), 7.85 (d, J = 8.5 Hz, 1H), 7.86~7.59 ((m, 2H), 7.55
(d, J = 8.5 Hz, 1H), 7.45 (td, J = 8.0, 1.0 Hz, 1H), 7.39, 7.40 (d, J = 8.5 Hz, 2H), 6.91
(dd, J = 9.0, 2.0 Hz, 2H), 5.05 (t, J = 5.0 Hz, 1H), 4.83 (d, J = 5.0 Hz, 1H), 3.80 (s,
3H);13C NMR (125 MHz, CDCl3): δ 46.02, 55.33, 114.17, 120.95, 123.54, 124.81,
125.88, 127.24, 127.46, 129.40, 129.54, 129.61, 129.79, 130.84, 131.05, 132.52,
132.55, 134.15, 145.53, 150.33, 159.18, 180.95. HRMS (ESI) for C24H18N2O2SCl
([M+1]+): calcd., 433.0778; found, 433.0778.
5.2.3.2.
N-(10-Chloro-12-oxo-12H-thiochromeno[2,3-c]quinolin-6-yl)picolinamide
(6). A mixture of TFA (~10 vol.) and 5 (1.0 eq.) was stirred at RT for 4~5 hours.
After completion of the reaction, as monitored by TLC, the reaction mixture was
concentrated on a rotary evaporator. The resulting residue was quenched in ice-cold
water, and the resulting solid was then filtered. The filtered cake was suspended in sat.
NaHCO3(aq) (pH ~8) and stirred for 30 min. The suspension was filtered; washed with
water
and
vacuum-dried
to
afford
intermediate
6-amino-12H-thiochromeno[2,3-c]quinolin-12-one as a pale-yellow to yellow solid in

an almost pure form. 6-Amino-12H-thiochromeno[2,3-c]quinolin-12-one (1.0 eq.)
was added at once to a stirred mixture of 2-picolinic acid (1.3 eq.) and CDI (1.9 eq.)
in DMSO (4~5 vol.) at 70 °C, and stirring continued at the same temperature for 30
min. The temperature was raised to 140 °C, and the reaction mixture was further
stirred at same temperature for 16 hours. After completion of the reaction, as
monitored by TLC, the reaction mixture was cooled and quenched in water. The
resulting precipitate was diluted with a 10% MeOH/CH2Cl2 mixture and extracted.
The aqueous layer was separately extracted with 10% MeOH/CH2Cl2. The combined
organic extract was washed with brine solution, dried over anhydrous Na2SO4, and
then concentrated to give the crude compound 6. The crude mixture was purified by
FCC using a MeOH/CH2Cl2/NH3(aq) mixture to afford the target compound as a
yellow solid. Yield: 120 mg (36%). ES-MS [M+1]+: 417.9; tR: 4.77 min (purity:
95.3%), 1H NMR (500 MHz, CDCl3): δ 10.56 (s, 1H), 9.69 (dd, J = 9.0, 1.0 Hz, 1H),
8.73 (d, J = 4.5 Hz, 1H), 8.58 (d, J = 1.0 Hz, 1H), 8.36 (d, J = 7.5 Hz, 1H), 8.15 (dd, J
= 9.0, 1.5 Hz, 1H), 7.97 (td, J = 8.0, 1.0 Hz, 1H), 7.80~7.74 (m, 2H), 7.64~7.57 (m,
3H);; 13C NMR (125 MHz, CDCl3): δ 123.09, 124.56, 125.93, 127.26, 127.68, 129.31,
129.35, 129.54, 129.85, 130.54, 130.71, 132.30, 132.70, 132.75, 134.05, 137.83,
144.97, 145.51, 148.42, 148.80, 163.45, 180.92. HRMS (ESI) for C22H13N3O2SCl
([M+1]+): calcd., 418.0417; found, 418.0418.

5.2.3.3. 10-Chloro-6-(propylamino)-12H-thiochromeno[2,3-c]quinolin-12-one (7).
The title compound was synthesized from n-propylamine in a similar manner as
described for 5. Yield: 120 mg (75%). ES-MS [M+1]+: 355.0; tR: 6.84 min (purity:
95.2%); 1H NMR (500 MHz, CDCl3): δ 9.42 (d, J = 8.5 Hz, 1H), 8.54 (d, J = 2.0 Hz,
1H), 7.81 (d, J = 8.0 Hz, 1H), 7.62~7.56 (m, 3H), 7.42 (t, J = 7.5 Hz, 1H), 4.85 (s,
1H), 3.67 (q, J = 7.0 Hz, 2H), 1.79 (sextet, J = 7.0 Hz, 2H), 1.08 (t, J = 7.5 Hz, 3H);
13C NMR (125 MHz, CDCl3): δ 11.67, 22.65, 44.14, 120.69, 123.52, 124.53, 125.84,
127.17, 127.46, 129.39, 129.45, 129.68, 131.06, 132.48, 132.54, 134.12, 145.68,
150.64, 181.00. HRMS (ESI) for C19H16N2OSCl ([M+1]+): calcd., 355.0672; found,
355.0676.
5.2.3.4.
6-((3-Aminopropyl)amino)-10-chloro-12H-thiochromeno[2,3-c]quinolin-12-one (8).
The title compound was synthesized from 1,3-diaminopropane in a similar manner as
described for 5. Yield: 295 mg (88%). ES-MS [M+1]+: 370.0; tR: 2.52 min (purity:
1
97.3%); H NMR (600 MHz, DMSO-d6): δ 9.37 (d, J = 9.0 Hz, 1H), 8.43 (d, J = 1.2
Hz, 1H), 8.02 (d, J = 8.4 Hz, 1H), 7.92 (dd, J = 8.4, 2.4 Hz, 1H), 7.72 (d, J = 8.4 Hz,
1H), 7.63 (td, J = 8.4, 1.2 Hz, 1H), 7.35 (td, J = 8.0, 1.5 Hz, 1H), 6.65 (brs, 2H), 3.68

13
(t, J = 6.6 Hz, 2H), 2.86 (t, J = 6.6 Hz, 2H), 1.94 (quin, J = 6.6 Hz, 2H); C NMR
(150 MHz, DMSO-d6): δ 28.1, 37.8, 40.0, 119.8, 123.7, 124.8, 125.4, 126.5, 128.0,
128.5, 128.9, 129.3, 131.7, 131.9, 132.7, 132.9, 145.0, 150.9, 180.2. HRMS (ESI) for
C19H17N3OSCl ([M+1]+): calcd., 370.0781; found, 370.0786.
5.2.3.5. 10-Fluoro-6-(propylamino)-12H-thiochromeno[2,3-c]quinolin-12-one (9).
The title compound was synthesized from 4b and n-propylamine in a similar manner
as described for 5. Yield: 190 mg (71%). ES-MS [M+1]+: 339.0; tR: 5.87 min (purity:
1
95.8%); H NMR (500 MHz, CDCl3): δ 9.46 (dd, J = 8.5, 1.0 Hz, 1H), 8.26 (dd, J =
9.5, 2.5 Hz, 1H), 7.82 (d, J = 7.5, 1.0 Hz, 1H), 7.65 (dd, J = 9.0, 5.0 Hz, 1H), 7.60 (td,
J = 8.5, 1.0 Hz, 1H), 7.44~7.41 (m, 2H), 4.88 (s, 1H), 3.70~3.66 (m, 2H), 1.79 (sextet,
J = 7.5 Hz, 2H), 1.08 (t, J = 7.5 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 11.63, 22.61,
44.10, 115.46 (J = 23.6 Hz), 120.77 (J = 25.0 Hz), 121.07, 123.81, 124.47, 125.84,
127.11, 128.10 (J = 7.9 Hz), 128.23, 128.99, 129.34, 133.25 (J = 6.8 Hz), 145.63,
150.62, 162.06 (J = 247.3 Hz), 181.19. HRMS (ESI) for C19H16N2OSF ([M+1]+):
calcd., 339.0967; found, 339.0968.
5.2.3.6. 6-(3-Aminopropylamino)-10-fluoro-12H-thiochromeno[2,3-c]quinolin-12-one
(10). The title compound was synthesized from 1,3-diaminopropane in a similar

manner as described for 9.Yield: 210 mg (75%). ES-MS [M+1]+: 354.0; tR: 2.35 min
(purity: 96.7%); 1H NMR (600 MHz, DMSO-d6): δ 9.39 (d, J = 9.0 Hz, 1H), 8.18 (dd,
J = 9.6, 2.8 Hz, 1H), 8.05 (dd, J = 8.4, 4.8 Hz, 1H), 7.80 (td, J = 8.4, 2.8 Hz, 1H),
7.71 (d, J = 7.8 Hz, 1H), 7.62 (t, J = 7.5 Hz, 1H), 7.39 (t, J = 7.2 Hz, 1H), 3.68 (t, J =
6.6 Hz, 2H), 2.82 (t, J = 6.6 Hz, 2H), 1.86 (quin, J = 6.6 Hz, 2H);13C NMR (150 MHz,
DMSO-d6): δ 29.1, 38.3, 40.0, 114.2 (J = 23.0 Hz), 119.8, 121.6 (J = 24.2 Hz), 123.6,
125.1, 125.4, 126.5, 127.8, 129.0 (J = 2.3 Hz), 129.2, 129.5 (J = 8.1 Hz), 132.2 (J =
6.9 Hz), 145.1, 151.0, 161.8 (J = 245.0 Hz), 180.5. HRMS (ESI) for C19H17N3OSF
([M+1]+): calcd., 354.1076; found, 354.1077.
5.2.3.7. 10-Methoxy-6-(propylamino)-12H-thiochromeno[2,3-c]quinolin-12-one (11).
The title compound was synthesized from 4c and n-propylamine in a similar manner
as described for 5. Yield: 120 mg (45%). ES-MS [M+1]+: 351.0; tR: 5.71 min (purity:
98.5%); 1H NMR (500 MHz, CDCl3): δ 9.52 (d, J = 8.5, 1H), 8.04 (d, J = 2.5 Hz, 1H),
7.82 (dd, J = 8.5, 1.0 Hz, 1H), 7.59 (td, J = 8.0, 1.0 Hz, 1H), 7.55 (d, J = 9.0 Hz, 1H),
7.42 (td, J = 8.0, 1.0 Hz, 1H), 7.28 (dd, J = 8.5, 2.5 Hz, 1H), 4.89 (t, J = 4.5 Hz, 1H),
3.96 (s, 3H), 3.70~3.66 (m, 2H), 1.79 (sextet, J = 7.5 Hz, 2H), 1.08 (t, J = 7.5 Hz, 3H);
13C NMR (125 MHz, CDCl3): δ 11.67, 22.67, 44.08, 55.75, 110.29, 121.02, 122.65,
124.13, 124.26, 124.73, 125.94, 127.08, 127.34, 129.02, 129.07, 132.76, 145.51,

150.80, 159.47, 181.76. HRMS (ESI) for C20H19N2O2S ([M+1]+): calcd., 351.1167;
found, 351.1167.
5.2.3.8.
6-(3-Aminopropylamino)-10-methoxy-12H-thiochromeno[2,3-c]quinolin-12-one (12).
The title compound was synthesized from 4c and 1,3-diaminopropane in a similar
manner as described for 5. Yield: 130 mg (46%). ES-MS [M+1]+: 366.0; tR: 2.12 min
1
(purity: 99.0%); H NMR (600 MHz, DMSO-d6): δ 9.44 (dd, J = 8.4, 1.2 Hz, 1H),
7.95 (d, J = 2.4 Hz, 1H), 7.90 (d, J = 9.0 Hz, 1H), 7.71 (d, J = 7.8 Hz, 1H), 7.61 (td, J
= 8.4, 1.2 Hz, 1H), 7.51 (dd, J = 8.4, 2.4 Hz, 1H), 7.36 (td, J = 8.4, 1.2 Hz, 1H), 3.95
(s, 3H), 3.69 (t, J = 6.6 Hz, 2H), 2.82 (t, J = 6.6 Hz, 2H), 1.89 (quin, J = 6.6 Hz, 2H);
13C NMR (150 MHz, DMSO-d6): δ 28.97, 38.28, 40.05, 55.64,110.14, 120.06, 122.49,
123.49, 124.89, 125.03, 125.43, 126.48, 127.83, 128.21, 128.96, 131.83, 144.95,
151.08, 159.13, 180.85. HRMS (ESI) for C20H20N3O2S ([M+1]+): calcd., 366.1276;
found, 366.1276.
5.2.3.9. 8-Chloro-6-(propylamino)-12H-thiochromeno[2,3-c]quinolin-12-one (13).
The title compound was synthesized from 4d and n-propylamine in a similar manner
as described for 5. Yield: 630 mg (84%). ES-MS [M+1]+: 355.0; tR: 6.57 min (purity:

99.2%); 1H NMR (500 MHz, CDCl3): δ 9.41 (dd, J = 8.5, 0.5 Hz, 1H), 8.51 (d, J = 8.5
Hz, 1H), 7.81 (d, J = 8.5 Hz, 1H), 7.72 (dd, J = 8.0, 1.0 Hz, 1H), 7.60 (td, J = 8.5, 1.0
Hz, 1H), 7.52 (t, J = 7.5 Hz, 1H), 7.341 (td, J = 7.0, 1.0 Hz, 1H), 5.05 (t, J = 4.5 Hz,
1H), 3.70 (quin, J = 5.5 Hz, 2H), 1.82 (sextet, J = 7.5 Hz, 2H), 1.09 (t, J = 7.5 Hz,
3H); 13C NMR (125 MHz, CDCl3): δ 11.69, 22.67, 44.17, 120.40, 123.09, 124.44,
125.79, 127.13, 127.59, 128.35, 129.34, 129.51, 130.44, 132.35, 132.43, 133.27,
145.80, 150.84, 181.90. HRMS (ESI) for C19H16N2OSCl ([M+1]+): calcd., 355.0672;
found, 355.0672.
5.2.3.10.
6-(3-Aminopropylamino)-8-chloro-12H-thiochromeno[2,3-c]quinolin-12-one
(14).
The title compound was synthesized from 4d and 1,3-diaminopropane in a similar
manner as described for 5. Yield: 400 mg (47%). ES-MS [M+1]+: 370.0; tR: 2.34 min
(purity: 99.1%); 1H NMR (600 MHz, DMSO-d6): δ 9.33 (d, J = 8.4 Hz, 1H), 8.46 (d,
J = 8.4 Hz, 1H), 8.06 (d, J = 7.8 Hz, 1H), 7.73 (d, J = 8.4 Hz, 1H), 7.70 (d, J = 8.4 Hz,
1H), 1H), 7.62 (td, J = 7.8, 0.6 Hz, 1H), 7.38 (t, J = 7.2 Hz, 1H), 3.69 (t, J = 6.6 Hz,
2H), 2.76 (t, J = 6.6 Hz, 2H), 1.84 (quin, J = 6.6 Hz, 3H); 13C NMR (150 MHz,
DMSO-d6): δ 30.9, 39.1, 40.0, 119.4, 123.5, 123.8, 125.3, 126.5, 128.0, 128.3, 128.35,
129.4, 129.5, 132.4, 132.5, 132.9, 145.4, 151.1, 181.2. HRMS (ESI) for