Structure-based discovery of novel 4-(2-fluorophenoxy)quinoline derivatives as c-Met inhibitors using isocyanide-involved multicomponent reactions

Article abstract of DOI:10.1016/j.ejmech.2020.112241

The c-Met kinase has emerged as a promising target for the development of small molecule antitumor agents because of its close relationship with the progression of many human cancers, poor clinical outcomes and even drug resistance. In this study, two novel series of 6,7-disubstitued-4-(2-fluorophenoxy)quinoline derivatives containing α-acyloxycarboxamide or α-acylaminoamide scaffolds were designed, synthesized, and evaluated for their in vitro biological activities against c-Met kinase and four cancer cell lines (H460, HT-29, MKN-45, and MDA-MB-231). Most of the target compounds exhibited moderate to significant potency and possessed selectivity for H460 and HT-29 cancer cell lines. The preliminary structure-activity relationships indicated that α-acyloxycarboxamide or α-acylaminoamide as 5-atom linker contributed to the antitumor potency. Among these compounds, compound 10m (c-Met IC₅₀ = 2.43 nM, a multitarget tyrosine kinase inhibitor) exhibited the most potent inhibitory activities against H460, HT-29 and MDA-MB-231 cell lines with IC₅₀ of 0.14 ± 0.03 μM, 0.20 ± 0.02 μM and 0.42 ± 0.03 μM, which were 1.7-, 1.3- and 1.6-fold more active than foretinib, respectively. In addition, concentration-dependent assay and time-dependent assay indicated compound 10m can inhibit the proliferation of H460 cell in a time and concentration dependent manner. Moreover, docking studies revealed the common mode of interaction with the c-Met binding site, suggesting that 10m is a potential candidate for cancer therapy deserving further study.

Full text of DOI:10.1016/j.ejmech.2020.112241

European Journal of Medicinal Chemistry 193 (2020) 112241
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Research paper
Structure-based discovery of novel 4-(2-fluorophenoxy)quinoline
derivatives as c-Met inhibitors using isocyanide-involved
multicomponent reactions
,
b
,
,
,
, b, *
Xiang Nan a, Hui-Jing Li a **, Sen-Biao Fang c ***, Qin-Ying Li a b, Yan-Chao Wu a
a School of Marine Science and Technology, Harbin Institute of Technology, Weihai, 264209, PR China
b Weihai Institute of Marine Biomedical Industrial Technology, Wendeng District, Weihai, 264400, PR China
c School of Computer Science and Engineering, Central South University, Changsha, 410082, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
The c-Met kinase has emerged as a promising target for the development of small molecule antitumor
agents because of its close relationship with the progression of many human cancers, poor clinical
outcomes and even drug resistance. In this study, two novel series of 6,7-disubstitued-4-(2-
Received 31 January 2020
Received in revised form
1 March 2020
Accepted 13 March 2020
Available online 16 March 2020
fluorophenoxy)quinoline derivatives containing
a-acyloxycarboxamide or a-acylaminoamide scaffolds
were designed, synthesized, and evaluated for their in vitro biological activities against c-Met kinase and
four cancer cell lines (H460, HT-29, MKN-45, and MDA-MB-231). Most of the target compounds exhibited
moderate to significant potency and possessed selectivity for H460 and HT-29 cancer cell lines. The
Keywords:
preliminary structure-activity relationships indicated that a-acyloxycarboxamide or a-acylaminoamide
4-(2-fluorophenoxy)quinoline derivatives
c-Met inhibitors
Isocyanide-involved multicomponent
reactions
as 5-atom linker contributed to the antitumor potency. Among these compounds, compound 10m (c-Met
IC50 ¼ 2.43 nM, a multitarget tyrosine kinase inhibitor) exhibited the most potent inhibitory activities
against H460, HT-29 and MDA-MB-231 cell lines with IC50 of 0.14
0.03
m
M, 0.20
0.02 mM and
Biological evaluation
Docking study
0.42 0.03 mM, which were 1.7-, 1.3- and 1.6-fold more active than foretinib, respectively. In addition,
concentration-dependent assay and time-dependent assay indicated compound 10m can inhibit the
proliferation of H460 cell in a time and concentration dependent manner. Moreover, docking studies
revealed the common mode of interaction with the c-Met binding site, suggesting that 10m is a potential
candidate for cancer therapy deserving further study.
© 2020 Elsevier Masson SAS. All rights reserved.
1. Introduction
pathways, including Ras/MEK/MAPK, PI3K/AKT and Ras/RAC1/PAK
pathways [3e5]. However, HGF/c-Met axis deregulation through
Mesenchymal-epithelial transition factor (c-Met) is a prototype
member of a heterodimeric receptor tyrosine kinase subfamily and
the only known high-affinity receptor for hepatocyte growth fac-
tor/scatter factor (HGF/SF) [1,2]. The HGF/c-Met signaling has been
identified to play a vital role in many normal physiological pro-
cesses (Fig. 1), such as mitogenesis, motogenesis and morphogen-
esis, by activating multiple downstream signal transduction
constitutive activation, gene amplification, mutations, and activa-
tion of an autocrine loop plays a key role in numerous malignancies
and promotes tumor growth, invasion, dissemination and/or
angiogenesis [6e12]. Additionally, dysregulated HGF/c-Met
signaling has been also associated with poor clinical outcomes
and resistance acquisition to some approved targeted therapies
[13e17]. Thus, c-Met has attracted consistent interest as a potential
target for cancer drug discovery. As c-Met tyrosine kinase inhibitors
(TKIs) are believed to be effective for both ligand-dependent and
independent activation of c-Met, they are the most attractive
methods for targeting the c-Met pathway, and have made a
respectable number of c-Met TKIs into clinical trials or approved as
anticancer drugs [18e20]. In general, the c-Met TKIs can be cate-
gorized into two types based on the chemical types and different
binding modes of the DFG motif of the c-Met activation loop
* Corresponding author. School of Marine Science and Technology, Harbin Insti-
tute of Technology, Weihai, 264209, PR China.
** Corresponding author. School of Marine Science and Technology, Harbin
Institute of Technology, Weihai, 264209, PR China.
*** Corresponding author.
E-mail addresses: lihuijing@iccas.ac.cn (H.-J. Li), fangsb@csu.edu.cn (S.-B. Fang),
ycwu@iccas.ac.cn (Y.-C. Wu).
https://doi.org/10.1016/j.ejmech.2020.112241
0223-5234/© 2020 Elsevier Masson SAS. All rights reserved.

2
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
[21e26], and Type II inhibitors may be more effective than Type I
inhibitors against the mutations near the active site of c-Met
[27e33]. This is because Type II inhibitors not only bind to the same
area occupied by the Type I inhibitors, but also utilize the hydrogen
bonding and hydrophobic interaction with the allosteric site, which
is beyond the entrance of the c-Met active site.
Accordingly, various Type II c-Met inhibitors have been devel-
oped, amongst which 6,7-disubstituted-4-(2-fluorophenoxy)quin-
olines are drawing the most attention. Many of these derivatives
are under clinical or preclinical research, such as cabozantinib, Kirin
Brewery, Amgen, MG10, MethylGene and foretinib [34e38]. As
shown in Fig. 2, the structure-activity relationships of quinoline-
disadvantage. Thus, the development of a new protocol for the
facile synthesis of the 5-atom linker becomes a high priority.
Multicomponent reactions (MCRs) [48e53] deemed to satisfy this
criterion due to their utility in rapid construction of structurally
diverse, complex, and chemical libraries of “drug-like” molecules
from simple precursors [54e56]. In particular, MCRs that involve
isocyanides (IMCRs) are by far the most versatile reactions in terms
of scaffolds and number of accessible compounds, and they form
the basis of the well-known Passerini and Ugi reactions [57e59].
Passerini and Ugi reactions could provide one-pot synthesis of a-
acyloxycarboxamide and
tively. Inspiringly, the
a
-acylaminoamide fragments, respec-
a
-acyloxycarboxamide and a-acylaminoa-
based
inhibitors
disclosed
that
6,7-disubstituted-4-
mide framework conformed to the characteristic of the ‘5 atoms
regulation’ and contained both hydrogen-bond donor and
acceptor, indicating that they could be the suitable linkers
phenoxyquinoline framework (moiety A) and an aryl fragment
(moiety B) should be preserved as the privileged scaffolds in that
the quinoline core formed hydrogen bonds and maintained vander
Waals interactions with the backbone of c-Met kinase, and the
moiety B probably fitted into the hydrophobic pocket [39e42].
More importantly, these 6,7-disubstituted-4-phenoxyquinoline
derivatives have two common structural features in their linkers
between moiety A and moiety B which is known as ‘5 atoms
regulation/hydrogen-bond donors or acceptors’ [43e47]. These
structural characteristics suggested that the exploration of a suit-
able linker might be a feasible way to discover new quinoline-based
Type II c-Met inhibitors.
mentioned above. In addition, compounds bearing
a-acylox-
ycarboxamide or -acylaminoamide scaffold have been reported to
a
exhibit a broad spectrum of biological activities (Fig. 3), including
antitumor, antiinflammatory, antimalarial and antituberculosis, etc
[60,61]. Accordingly, we envisioned that the utilization of IMCRs
(Passerini and Ugi reactions) would provide a rapid and effective
synthetic way for the construction of the suitable 5-atom linkers,
thus facilitating the discovery of new c-Met inhibitors [62,63].
Herein, we first report the use of Passerini (P-3CR) and Ugi (Ugi-
4CR) reactions as a versatile approach towards the synthesis of 6,7-
Although many endeavors have been paid to the construction of
the 5-atom linker, one-step synthesis of the 5-atom linker is still a
significant challenge. The multi-step synthetic strategies put
preparation of sufficient quantities of quinoline-based Type II c-
Met inhibitors for biological evaluation and medical studies at a
disubstituted-4-phenoxyquinoline derivatives that bearing
a-acy-
loxycarboxamide and -acylaminoamide, respectively. Meanwhile,
a
various substituents were introduced into the moiety B as well as
the 5-atom linkers to investigate their effects on activity. All target
compounds were evaluated for their c-Met kinase activity and
Fig. 1. The signaling pathways of c-Met.

X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
3
Fig. 2. The representative c-Met kinase inhibitors of different types.
Fig. 3. Structures of a-acyloxycarboxamide/a-acylaminoamide and its mimics.
antiproliferative activities against four cancer cell lines, including
H460, HT-29, MKN-45 and MDA-MB-231. Subsequently, the kinase
selectivity and docking study of the representative compound 10m
was further explored.
in the presence of iron powder and acetic acid to afford the desired
4-quinolin-ol 4. 4-Chloro-quinoline 5 was obtained in 83% yield
just by treating 4-quinolin-ol 4 on exposure of phosphours oxy-
chloride [65]. Subsequently, 4-chloro-quinoline 5 was etherified
with 2-fluoro-4-nitrophenol to give nitro 6, which was then
reduced by treating with SnCl2$2H2O in ethanol to give amide 7 in
36% overall yield [66]. Compound 7 was converted to formamide 8
in 76% yield by reaction with ethyl formate under reflux. Finally, the
dehydration of 8, after the optimization of reaction conditions
(Table 1), was accomplished by treating with phosphours oxy-
chloride at room temperature in the presence of triethylamine in
chloroform to afford the key intermediate isocyanide 9 in 92% yield
[67].
2. Results and discussion
2.1. Chemistry
2.1.1. Synthesis of 3-fluoro-4-(6,7-dimethoxyquinolin-4-yloxy)
phenylisocyanide (9)
As shown in Scheme 1, 3-fluoro-4-(6,7-dimethoxyquinolin-4-
yloxy)phenylisocyanide 9 was synthesized from readily available
4-hydroxy-3-methoxy-acetophenone. 4-Hydroxy-3-methoxy-ace-
tophenone was alkylated with iodomethane under basic reaction
conditions to afford disubstituted acetophenone 1 in 91% yield.
Regioselective nitration of disubstituted acetophenone 1 and sub-
sequent aminomethylenation with N,N-dimethylformamide
dimethyl acetal (DMF-DMA) provided 3-(dimethylamino)-prop-2-
en-1-one 3 [64], which underwent an intramolecular cyclization
2.1.2. Synthesis of the target compounds of
-acylaminoamide-based 6,7-dimethoxy-4-(2-fluorophenoxy)
quinoline
a-acyloxycarboxamide/
a
Two novel series of target compounds 10a-y and 11a-g were
obtained in moderate to excellent yields via Passerini and Ugi re-
actions, respectively [68]. The Passerini reaction (Scheme 2)

4
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
Scheme 1. Reagents and conditions: (a) CH3I, K2CO3, acetone, r.t., 4 h; (b) concentrated nitric acid, 0 ꢀC, overnight; (c) DMF-DMA, toluene, reflux; (d) Fe (powder), AcOH, 80 ꢀC, 2 h;
(e) POCl3, reflux, DMF (cat.); (f) 2-fluoro-4-nirophenol, PhCl, 140 ꢀC, 20 h; (g) SnCl2$2H2O, EtOH, 70 ꢀC, 6 h; (h) ethyl formate, TEA, refluxing, 18 h; (i) POCl3, TEA, CHCl3, 0 ꢀC.
Table 1
2.2. Biological evaluation
Optimization of the reaction conditions for the dehydration of formamide 8.
2.2.1. In vitro enzymatic assays and structure-activity relationships
The c-Met enzymatic assays of all newly prepared target com-
pounds were evaluated in vitro using homogeneous time-resolved
fluorescence (HTRF) assay, taking foretinib as a positive control.
The results expressed as the half-maximal inhibitory concentration
(IC50) values presented in Table 2, as mean values of experiments
performed in triplicate.
Entry
Dehydrant/base
Solvent
Temp (oC)
Yield (%)
1
2
3
4
5
6
7
8
9
PhSO2Cl/C5H5N
Ph3P/Et3N
Ph3P/Et3N
SOCl2/Na2CO3
Cyanuric/Et3N
EtOPOCl2/Et3N
POCl3/C5H5N
POCl3/Et3N
C5H5N
CCl4
CCl4
rt
rt
40
0
45
45
0
trace
18
22
26
35
28
54
74
92
DMF
CH2Cl2
CH2Cl2
CHCl3
CHCl3
CHCl3
As illustrated in Table 2, these novel 6,7-dimethoxy-4-(2-
0
rt
POCl3/Et3N
fluorophenoxy)quinoline derivatives bearing
amide/ -acylaminoamidemoiety were found to be active against c-
Met kinase with IC50 values ranging from 2.43 to 66.54 nM; three of
them (10m, IC50 2.43 nM; 10n, IC50 4.72 nM; 10o,
a-acyloxycarbox-
a
¼
¼
involved three components: aldehyde/ketone, carboxylic acid, and
isocyanide 9. The reaction gave a series of novel 6,7-dimethoxy-4-
(2-fluorophenoxy)quinoline derivatives with an a-acyloxycarbox-
amide group. The Ugi reaction (Scheme 2) involved four compo-
nents: aldehyde, amine, carboxylic acid, and isocyanide 9. This
reaction mixture afforded another series of 6,7-dimethoxy-4-(2-
IC50 ¼ 3.13 nM) showed comparable potency with foretinib
(IC50 ¼ 1.75 nM), indicating that the introduction of the new moiety
a
-acyloxycarboxamide or a-acylaminoamide as ‘five-atom linker’
to
6,7-dimethoxy-4-(2-fluorophenoxy)quinoline
framework
maintained the potent c-Met kinase inhibitory efficacy. The
a
-
acyloxycarboxamide-contained target compounds 10a-y exhibited
relatively higher c-Met kinase inhibitory efficacy in comparison
with a-acylaminoamide-contained target compounds 11a-g.
As seen from the data in Table 2, compound 10h (IC50 ¼ 8.35 nM;
R1 ¼ t-Butyl, R2 ¼ Phenyl) possessed greater potency than com-
pound 10d (IC50 ¼ 22.74 nM; R1 ¼ Methyl, R2 ¼ Phenyl), compound
fluorophenoxy)quinoline derivatives with a
a-acylaminocarbox-
amide group. All newly synthesized compounds were purified by
column chromatography and their structures were characterized
by NMR and MS.
Scheme 2. Reagents and conditions: (j) THF/H2O ¼ 3:1, 0.4 M, 40 ꢀC, 24 h; (k) MeOH, 0.2 M, 60 ꢀC, 24 h.

X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
5
Table 2
c-Met kinase activities of the target compounds 10a-y and 11a-g.
Compd.
R1
R2
R3
C-Met IC50 (nM)
10a
10b
10c
10d
10e
10f
10g
10h
10i
10j
10k
10l
10m
(R)-10m
(S)-10m
10n
10o
10p
10q
10r
10s
10t
10u
10v
10w
10x
Methyl
Methyl
Methyl
Methyl
n-Propyl
Cyclohexyl
Phenyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
Cyclopentyl
2-Thienyl
2-Naphthyl
Ph
Ph
Ph
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
52.86 3.48
37.46 4.27
48.36 3.25
22.74 1.58
19.45 1.90
30.38 2.56
54.42 4.65
8.35 0.82
12.35 0.94
21.48 1.65
35.64 3.86
18.45 1.35
2.43 0.31
2.56 0.28
2.49 0.19
4.72 0.52
3.13 0.42
7.43 1.16
7.86 0.92
8.12 0.85
18.44 2.63
36.62 2.46
18.66 1.95
32.74 3.34
42.68 3.45
66.54 4.26
46.87 3.44
10.46 0.84
18.46 1.34
20.54 1.68
30.92 2.57
24.45 3.68
36.46 2.57
9.12 0.76
1.75 0.14
Ph
Ph
4-Me-Ph
4-OMe-Ph
3,4,5-(OMe)3-Ph
4-(t-Butyl)-Ph
4-F-Ph
4-F-Ph
4-F-Ph
3-F-Ph
2-F-Ph
4-Cl-Ph
3-Cl-Ph
2-Cl-Ph
4-Br-Ph
4-CF3-Ph
3,4-(Cl)2-Ph
2-Thienyl
2-Furanyl
Cyclopentyl
2-Naphthyl
4-F-Ph
/
/
/
10y
11a
11b
11c
11d
11e
11f
11g
Foretinib
n-Butyl
t-Butyl
cylcohexyl
Ph
3,4-(OMe)2-Ph
4-F-Ph
H
4-F-Ph
4-F-Ph
4-F-Ph
4-F-Ph
4-F-Ph
4-F-Ph
10e (IC50 ¼ 19.45 nM; R1 ¼ n-Propyl, R2 ¼ Phenyl), compound 10f
(IC50 ¼ 30.38 nM; R1 ¼ Cyclohexyl, R2 ¼ Phenyl) and
donating groups, the lower the activities, such as 10j and 10k. In
view of these results, the utilization of EDGs was not further
pursed. Gratifyingly, the introduction of EWGs exhibited positive
effect on the c-Met inhibitory activity. In particular, incorporation of
the mono-EWGs at the 4-position of phenyl ring (10m, R2 ¼ 4-F-
Phenyl, IC50 ¼ 2.43 nM, increased 3.4-fold) showed a higher po-
tency than that of mono-EWGs at 3-position and 2-position of the
phenyl (10o, R2 ¼ 3-F-Ph, IC50 ¼ 4.72 nM, increased 1.8-fold; 10p,
R2 ¼ 2-F-Ph, IC50 ¼ 3.13 nM, increased 2.7-fold), and the same trend
was observed for the series of chloro-substituted phenyl com-
pounds 10p (R2 ¼ 4-Cl-Phenyl, IC50 ¼ 7.43 nM), 10q (R2 ¼ 3-Cl-
Phenyl, IC50 ¼ 7.86 nM), and 10r (R2 ¼ 2-Cl-Phenyl, IC50 ¼ 8.12 nM).
However, the introduction of double electron-withdrawing groups
(10u, R2 ¼ 3,4-Cl-Phenyl, IC50 ¼ 18.66 nM) showed opposite trend
in potency of the compound compared with 4-chloro derivative
Compound 10g (IC50 ¼ 54.42 nM; R1 ¼ Phenyl, R2 ¼ Phenyl). The
t-butyl group could bind mainly with the hydrophobic binding
pocket in protein. On the basic understanding of the structural of c-
Met, the t-butyl group in compound 10h may possess a larger
spaced structure with hydrophobic properties. This tightly struc-
tural variation made compound 10h bind tightly with surrounding
residues, which resulted in lower binding free energy. Accordingly,
t-butyl derivatives were further studied in the following work.
Comprehensive t-butyl analogs with diverse R2 substituents,
including fourteen aryl rings, an aromatic fused ring, two hetero-
cyclic groups and a cyclopentyl were investigated to further
discover the structure-activity relationships. The SARs based on
IC50 values indicated that the R2 group played an important role for
the c-Met kinase inhibitory efficacy. Indeed, the introduction of
mono-EDGs 4-methyl 10i (R2 ¼ 4-Me-Phenyl, IC50 ¼ 12.35 nM) and
4-methoxy 10j (R2 ¼ 4-OMe-Phenyl, IC50 ¼ 21.48 nM) led to a 1.5-
and 2.6-fold decrease in potency in comparison with 10h that no
substituent on the phenyl ring (R2 ¼ Phenyl, IC50 ¼ 8.35 nM). The
introduction of trisubstituted-EDGs 10k (R2 ¼ 3,4,5-(OMe)3-Phenyl,
IC50 ¼ 35.64 nM) reduced the potency by another 1.7-fold
compared to 10j. The results showed that the presence of
electron-donating group decreased the c-Met inhibitory activity of
the target compounds. Moreover, the more the number of electron-
10p and 3-chloro derivative 10q, which indicated
a mono-
substituted phenyl ring is more preferred than a disubstituted
phenyl ring. The introduction of strong EWGs to the phenyl ring led
to a significantly decrease in activities compared with 10h (R2 ¼ Ph,
IC50
¼
8.35 nM), such as compound 10t (R2
¼
4-CF3-Ph,
IC50 ¼ 36.62 nM) that caused the potency to be lowered by 4.4-fold,
suggesting that the phenyl probably need medium electron density.
The bulky effect of the substituents likely weakened the potency
since the more steric analogs 4-(t-butyl)phenyl 10l
(IC50
¼
18.45 nM, decreased 2.2-fold) and 2-naphthyl 10y

6
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
(IC50 ¼ 46.87 nM, decreased 5.6-fold) showed obvious decreased
activity compared with 10h (R2 ¼ Phenyl). The loss of activity might
due to that the hydrophobic pocket of c-Met was probably not
sufficiently large to accommodate with the bulky groups.
acylaminoamide-contained target compounds 11a-g. It was note-
worthy that most of the target compounds displayed good anti-
proliferative potency against H460 and HT-29, and relatively poor
potency toward the other two cell lines, which suggested that these
two series of target compounds may possessed selectivity for H460
and HT-29 cancer cell lines. Particularly, the most promising com-
pound 10m displayed excellent cytotoxicity against H460, HT-29
Compared with 10h (R2 ¼ Phenyl), five-membered heterocyclic
groups were also explored, such as 2-thienyl derivative 10v
(IC50 ¼ 32.74 nM) and 2-furanyl analogue 10w (IC50 ¼ 42.68 nM),
which led to 3.9- to 5.1-fold loss activity against c-Met kinase,
suggesting that the electron-rich five membered ring made an
adverse effect. More importantly, the replacement of the phenyl
ring with cyclopentyl group 10x (IC50 ¼ 66.54 nM) resulted in 7.9-
and MDA-MB-231 cell lines with IC50 values of 0.14
0.20 0.02 M and 0.42 0.03 M, respectively, which were
1.3e1.7 times superior to foretinib (IC50 0.24 0.04 M,
0.26 0.03 M, and 0.65 0.05 M, respectively). The study of
0.03 mM,
m
m
:
m
m
m
fold loss activity, indicating that
p-aryl interaction really plays an
structure-activity relationships (SARs) indicated that these analogs
showed similar SARs as summarized in the c-Met kinase level: (a)
essential role in the biological activity.
Having identified well tolerated groups on R1 (t-Butyl) and R2 (4-
F-Phenyl), respectively, our attention was turned to focus on the
linker in the subsequent efforts, and seven target compounds 11a-g
target compounds bearing
exhibited higher potency than compounds bearing
a
-acyloxycarboxamide generally
-acylaminoa-
a
mide linkage; (b) the target compounds showed excellent selec-
tivity toward H460 and HT-29 cancer cell lines; (c) the EWGs (such
as F, Cl) on moiety B benefited to the potency; (c) compounds
bearing mono-electron-withdrawing groups (mono-EWGs, such as
F and Cl) were generally more active than those with no substitu-
ent, EDGs or double-EWGs; (d) introduction of steric hindrance (4-
(t-Butyl)-Ph and 2-naphthyl) or bulky electron-withdrawing
groups to phenyl ring (suchas Br and CF3) led to an obvious
decrease in cytotoxicity; (e) the cytotoxicity of compounds with
substituent (mono-EWGs) at 4-positionof phenyl ring (moiety B)
was higher than those with substituents at other positions.
were prepared. To our delight,
a-acylaminoamide derivative 11a
(R3 ¼ n-Butyl, IC50 ¼ 10.46 nM) exhibited moderate c-Met kinase
inhibitory efficacy. Encouraged by the remarkably potency of com-
pound 11a, it was continued for further investigation focused on R3
group. Compared to target compound 11a, the introduction of
diverse substitution patterns on R3 including t-butyl (11b,
IC50 ¼ 18.46 nM), cylcohexyl (11c, IC50 ¼ 20.54 nM), phenyl rings
(11d, R3 ¼ Phenyl, IC50 ¼ 30.92 nM; 11e, R3 ¼ 3,4-(OMe)2-Phenyl,
IC50 ¼ 24.45 nM; 11f, R3 ¼ 4-F-Phenyl, IC50 ¼ 36.46 nM) caused
significantly activity decreases. However, with the introduction of H
atom on R3, compound 11g (R3 ¼ H, IC50 ¼ 9.12 nM, increased 1.1-
fold) displayed a slight increase on c-Met inhibitory efficacy in
comparison with 11a (R3 ¼ n-Butyl, IC50 ¼ 10.46 nM). The results
suggested that electronic effect and steric hindrance of R3 group
were fairly sensitive tothe c-Met kinase inhibitory activities. Further
2.2.3. Enzymatic selectivity assays
To examine the selectivity of compound 10m on c-Met kinase
over other kinases, it was screened against 6 other tyrosine kinases
(Table 4). Compared with its high potency against c-Met
(IC50 ¼ 2.43 nM), 10m also exhibited high inhibitory effects against
studies about the effect of R3 group (a-acylaminoamide) are in
progress in our laboratory and will be reported upon in the future.
Considering the enantiomers of candidate compounds might
display different activities, the two enantiomers of the represen-
tative compound 10m were prepared by chiral chromatography,
which were used for the investigation of the effect of the enan-
tiomers on c-Met inhibition. Unexpectedly, the two enantiomers
displayed similar activity on c-Met inhibition. Thus, racemic 10m
was used for further biological evaluation in vitro.
The pharmacological data suggested that a suitable degree of
electron density and steric hindrance on the 5-atom linker was
essential to improve the c-Met kinase inhibitory activity. Moreover,
the data showed that the hydrophobic pocket can accommodate
the mono-EWGs of phenyl (moiety B), especially F or Cl at para-
position of phenyl rings.
c-Kit (IC50
¼
4.42 nM), Flt-3 (IC50
¼
6.15 nM) and Ron
(IC50 ¼ 18.64 nM). 10m exhibited less inhibitory effects against
VEGFR-2 and Flt-4, the potency was 121- and 222-fold lower than
against c-Met, respectively. Additionally, 10m exhibited a slight or
no tyrosine kinase inhibitory activity against EGFR (IC50 > 10 mM).
These data suggested that compound 10m is a promising multi-
target inhibitor of tyrosine kinase, and might act through some
other mechanism rather than only by inhibiting c-Met kinase.
Further studies on the mechanism of these compounds are in
progress.
2.2.4. Concentration-dependent assay
In order to investigate the relationship between activity and
concentration, seven concentrations of compound 10m were set
and the inhibitory rate of compound 10m against four cancer cell
lines for 72 h was measured by MTT assay, and the results were
shown in Fig. 4. It can be seen that the inhibition rate of compound
10m against four cancer cell lines increased with the increase of
concentration. The results showed that the target compound 10m
inhibited the growth of the four tumor cell lines in a concentration-
dependent manner.
2.2.2. In vitro antiproliferative activity
The synthesized thirty-two target compounds (10a-y, 11a-g)
were evaluated for their cytotoxicity in vitro against c-Met-addicted
cancer cell lines, including H460 (human lung cancer), HT-29 (hu-
man colon cancer), MKN-45 (human gastric cancer) and a c-Met
less sensitive MDA-MB-231 (human breast cancer) by the MTT-
based assay, taking foretinib as positive control. The results
expressed as half-maximal inhibitory concentration (IC50) values
and were presented in Table 3, as mean values of experiments
performed in triplicate.
As illustrated in Table 3, most of the target compounds showed
moderate-to-excellent cytotoxic activity against different cancer
cells, and four of them exhibited more or similar potent activities
against certain cancer lines in comparison with foretinib, indicating
2.2.5. Time-dependent assay
In order to examine whether the time can affect the inhibitory
effect of the compound against tumor cells, five concentrations of
compound 10m and three time gradients were set and the inhibi-
tion rate of H460 cell was measured by MTT assay. The results were
shown in Fig. 5. At each concentration, the inhibition rate of com-
pound 10m against H460 cell increased with time. In addition, at
the same time, the inhibition rate of compound 10m against
H460 cell increased with increasing concentration. Therefore,
compound 10m can inhibit the proliferation of H460 cell in a time
and concentration dependent manner.
that the introduction of
mide moiety as the 5-atom linker maintained remarkably the
potent cytotoxicity, and -acyloxycarboxamide-contained target
compounds 10a-y exhibited higher potency than
a-acyloxycarboxamide or a-acylaminoa-
a
a
-

X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
7
Table 3
Structures and cytotoxic activities of compounds 10a-y and 11a-g against H460, HT-29, MKN-45 and MDA-MB-231 cell lines in vitro.
Compd.
R1
R2
R3
IC50
(
m
mol/L) SD
H460
HT-29
MKN-45
MDA-MB-231
10a
10b
10c
10d
10e
10f
10g
10h
10i
10j
10k
10l
10m
10n
10o
10p
10q
10r
Methyl
Methyl
Methyl
Methyl
n-Propyl
Cyclohexyl
Phenyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
t-Butyl
Cyclopentyl
2-Thienyl
2-Naphthyl
Ph
Ph
Ph
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
15.19 1.34
2.46 0.27
9.43 1.16
1.29 0.22
0.89 0.15
10.32 0.65
22.45 2.56
0.40 0.10
0.78 0.11
1.25 0.11
2.70 0.36
2.06 0.12
0.14 0.03
0.26 0.04
0.21 0.05
0.20 0.04
0.31 0.06
0.22 0.02
0.48 0.12
1.84 0.26
0.78 0.08
0.96 0.13
2.68 0.25
11.56 0.78
3.34 0.36
0.47 0.07
1.30 0.05
4.34 0.25
7.56 0.78
6.42 0.67
8.42 0.64
0.38 0.06
0.24 0.04
24.56 1.40
4.02 0.33
11.57 1.34
1.92 0.17
1.24 0.22
15.64 1.13
25.62 1.89
0.45 0.04
0.85 0.13
1.54 0.17
3.03 0.28
2.45 0.34
0.20 0.02
0.30 0.05
0.24 0.03
0.24 0.03
0.39 0.05
0.29 0.04
0.56 0.14
2.16 0.18
0.90 0.12
1.26 0.22
2.96 0.30
9.27 0.65
4.38 0.24
0.52 0.05
1.45 0.09
5.35 0.45
9.27 0.65
6.21 0.78
10.23 0.56
0.44 0.07
0.26 0.03
28.20 2.47
6.39 0.29
15.65 1.21
2.39 0.19
1.87 0.25
20.54 1.95
ND
0.56 0.06
1.08 0.09
1.86 0.14
3.87 0.15
3.95 0.52
0.26 0.04
0.54 0.11
0.38 0.06
0.32 0.05
0.60 0.07
0.46 0.08
0.75 0.10
2.87 0.23
1.12 0.21
1.70 0.23
ND
ND
8.24 0.56
13.26 1.09
3.21 0.18
2.48 0.21
17.95 1.31
ND
Ph
Ph
0.65 0.14
1.42 0.16
2.58 0.33
4.92 0.36
4.45 0.29
0.42 0.03
0.49 0.06
0.44 0.05
0.48 0.06
0.86 0.16
0.76 0.12
0.90 0.14
3.52 0.34
1.56 0.14
1.89 0.38
3.56 0.26
13.98 1.85
6.75 0.68
0.86 0.05
1.70 0.13
8.48 0.72
13.98 1.35
8.87 0.92
14.77 1.46
0.96 0.14
0.65 0.05
4-Me-Ph
4-OMe-Ph
3,4,5-(OMe)3-Ph
4-(t-Butyl)-Ph
4-F-Ph
3-F-Ph
2-F-Ph
4-Cl-Ph
3-Cl-Ph
2-Cl-Ph
4-Br-Ph
4-CF3-Ph
3,4-(Cl)2-Ph
2-Thienyl
2-Furanyl
Cyclopentyl
2-Naphthyl
4-F-Ph
4-F-Ph
4-F-Ph
4-F-Ph
4-F-Ph
4-F-Ph
4-F-Ph
10s
10t
10u
10v
10w
10x
10y
11a
11b
11c
11d
11e
11f
11.54 1.10
ND
/
n-Butyl
t-Butyl
cylcohexyl
Ph
3,4-(OMe)2-Ph
4-F-Ph
H
0.68 0.04
1.58 0.11
6.65 0.52
11.54 1.10
7.52 0.51
12.43 1.62
0.65 0.03
0.050 0.005
11g
Foretiniba
Bold values show the IC50 values of the prepared compounds lower than the values of the positive controlforetinib.ND: Not determined.
a
Used as a positive control.
Table 4
compound 10m in the cocrystal structure of foretinib bound to the
c-Met kinase were performed simultaneously. It was found that
most parts of the compound 10m overplayed perfectly except for
the 3-morpholinopropoxy group in foretinib. The alignment of the
two structures showed that they occupy the same area of the
protein, and thus result in adonor-acceptor interaction with
Met1160 and Asp1222, respectively. In general, these results of the
molecular docking study showed that 4-phenoxyquinoline de-
Kinase selectivity profile of compound 10m and foretinib.
Enzyme
Enzyme IC50 (nM)
10m
Foretinib
c-kit
Flt-3
Ron
VEGFR-2
Flt-4
4.42
6.15
18.64
295
540
6.74
5.56
3.62
4.96
1.67
3020
1.75
rivatives containing
ergistically to interact with the binding site of c-Met, suggesting
that -acyloxycarboxamide moiety could serve as a scaffold from
a-acyloxycarboxamide moiety could act syn-
EGFR
c-Met
>10,000
2.43
a
which to build a novel series of c-Met inhibitors.
2.3. Molecular docking studies
3. Conclusion
To further explore the binding mode of target compounds with
the active site of c-Met, molecular docking simulation studies were
carried out by using Autodock 4.2 package. Based on the in vitro
inhibition results, we selected compound 10m, the best c-Met in-
hibitor in this study, as ligand example, and the structure of c-Met
was selected as the docking model (PDB ID code: 3LQ8). The
binding modes of compound 10m and c-Met was shown in Fig. 6,
and the nitrogen atom of quinoline, the oxygen atom of a-acylox-
ycarboxamide moiety in compound 10m formed two H-bond in-
teractions with protein residue Met1160 and Asp1222, respectively.
At the same time, one p-p interaction between the phenyl ring and
In summary, isocyanide-involved multicomponent reactions
have been used for the rapid and efficient synthesis of two series of
structurally diverse derivatives based on 6,7-disubstituted-4-(2-
fluorophenoxy)quinoline. This approach is a valuable tool in
design and synthesis of novel c-Met inhibitors with advantages of
simplicity, atom-economy, and good yields. The entire target
compounds were investigated for their in vitro biological activities
against c-Met kinase and four cancer cell lines (H460, HT-29, MKN-
45 and MDA-MB-231). Most of compounds displayed moderate-to-
excellent activity against H460, HT-29 cancer cell lines and rela-
tively poor potent towards MKN-45 and MDA-MB-231 cell lines. In
particular, the most promising compound 10m (c-Met
IC50 ¼ 2.43 nM) demonstrated excellent c-Met inhibitory activity
and remarkable cytotoxicities against H460, HT-29 and MDA-MB-
the Phe1223 has been formed. Moreover, the terminal 4-
fluorophenyl ring fitted into the hydrophobic pocket that was
formed Phe1200, Gln1123, Ile1130 and Phe1124, etc. To gain more
structural information for further optimization, docking model of

8
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
Fig. 4. Relationship between activity and concentration of compound 10m against four cancer cell lines.
Fig. 5. The inhibitory effect of compound 10m on H460 cell line at different time points.
231 with IC50 values of 0.14
m
M, 0.20
m
M, 0.42
m
M, which were 1.7-,
and R3 (R1 ¼ t-butyl, R3 ¼ H) were favorable to activity, and mono-
EWGs (such as 4-F, 4-Cl) on the terminal phenyl rings (moiety B)
were also beneficial for improving antitumor activity. Future ap-
plications could also involve development of versatile biologically
significant 4-phenoxyquinoline fragments into MCR products,
chemical libraries created via MCRs, and heterocycles built from
isocyanides.
1.3- and 1.6-fold superior to positive foretinib, respectively. The
preliminary SARs studies indicated that the introduction of -acy-
loxycarboxamide or -acylaminoamide as the 5-atom linker
maintained the potent activity, and the potency of -acylox-
ycarboxamide analogs was generally more active than that of
acylaminoamide analogs. The target compounds modified with R1
a
a
a
a
-

X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
9
Fig. 6. Binding model comparison of designed compounds with foretinib. (A) Binding pose of compound 10m with c-Met active site. Compound 10m was showed in colored sticks,
green: carbon atom, blue: nitrogen atom, pink: oxygen atom. (B) The interaction details between compound 10m and c-Met. (C) Binding pose of foretinib with c-Met active site. (D)
Overlay of 10m (pink color) in the same cavity along with foretinib (green color) as the reference molecule. (For interpretation of the references to color in this figure legend, the
reader is referred to the Web version of this article.)
4. Experimental
d ¼ doublet, t ¼ triplet, q ¼ quartet, m ¼ multiplet, br ¼ broad),
integration, and coupling constant in Hertz (Hz). Elemental analysis
was performed on an Elemental Analyzer vario EL Cube instrument.
4.1. Chemistry
Unless otherwise noted, all common reagents and materials
were purchased from commercial sources and were used without
further purification. Organic solvents were routinely dried and/or
distilled prior to use and stored over molecular sieves under argon.
Organic extracts were, in general, dried over anhydrous sodium
sulfate (Na2SO4). TLC plates were visualized by exposure to ultra
violet light (UV). Column chromatography was run on silica gel
(200e300 mesh) from Qingdao Ocean Chemicals (Qingdao, Shan-
dong, China). Mass spectra were recorded on a BrukerDaltonics
APEXII49e spectrometer with ESI source as ionization. Melting
points were measured by using a Gongyi X-5 microscopy digital
melting point apparatus and are uncorrected. 1H NMR and 13C NMR
spectra were obtained by using a Bruker Advance III 400 MHz NMR
spectrometer with TMS as an internal standard. Data are repre-
4.1.1. General procedure for preparation of4-((6,7-
dimethoxyquinolin-4-yl)oxy)-3-fluoroaniline (7)
The
preparation
of
the
key
intermidiate4-((6,7-
Dimethoxyquinolin-4-yl)oxy)-3-fluoroaniline 7 was achieved in
seven steps from commercially available 1-(4-hydroxy-3-
methoxyphenyl)ethanone as shown in Scheme 1, which was illus-
trated in detail in our previous study [69] and thus was not be listed
here.
4.1.2. Synthesis of N-(3-fluoro-4-(6,7-dimethoxyquinolin-4-yloxy)
phenyl)formamide (8)
A round-bottomed flask fitted with a reflux condenser was
treated with 7 (1.57 g, 5.0 mmol) and 4.60 g (5.0 mL) of ethyl
formate. The mixture was stirred and heated at reflux while 0.55 g
(0.75 mL) of triethylamine was added, and afterward for another
sented as follows: chemical shift, multiplicity (s
¼
singlet,

10
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
18 h. After cooling at room temperature, the reaction mixture was
concentrated, followed by addition of water (25 mL). The obtained
residue was submitted to extraction with EtOAc (3 ꢁ 50 mL). The
organic layer was separated, dried over anhydrous sodium sulfate,
filtered, and concentrated. The crude product was purified by silica
gel chromatography eluted with ethyl acetate/hexane (2:1) to give
compound 8 (1.40 g) as a white solid, yield: 81.8%,.m.p: 201e203 ꢀC.
5.84. ESI-MS: m/z 483.2 [MþH]þ.
4.1.4.2. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-1-oxopropan-2-yl
White solid, yield: 76.8%, m.p.: 105e107 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
thiophene-2-carboxylate
(10b).
d
10.70 (s, 1H), 8.45 (d, J ¼ 4.8 Hz, 1H), 7.99 (d, J ¼ 4.8 Hz,
1H), 7.88e7.85 (m, 2H), 7.52 (s, 1H), 7.49e7.43 (m, 2H), 7.39 (s, 1H),
7.25e7.24 (m, 1H), 6.44 (d, J ¼ 4.8 Hz, 1H), 5.27 (q, J ¼ 6.4 Hz, 1H),
3.93 (s, 6H), 1.57 (d, J ¼ 6.4 Hz, 3H). 13C NMR (100 MHz, DMSO‑d6)
1H NMR (400 MHz, DMSO‑d6)
d
10.52 (s, 1H), 8.46 (d, J ¼ 4.4 Hz,1H),
8.34 (s,1H), 8.12 (s,1H), 7.83 (d, J ¼ 12.4 Hz,1H), 7.51 (s,1H), 7.42 (m,
2H), 6.44 (d, J ¼ 3.6 Hz, 1H), 3.93 (s, 6H). 13C NMR (100 MHz,
d
169.0,161.0,159.3,153.5 (d, J ¼ 244.0 Hz),152.7,149.5,148.9,146.4,
DMSO‑d6)
d
163.1, 160.1, 159.3, 153.5 (d, J ¼ 244.8 Hz), 152.7, 149.5,
137.7 (d, J ¼ 9.8 Hz), 135.8 (d, J ¼ 12.3 Hz), 134.5, 134.3, 132.4, 128.5,
124.2, 116.2, 114.5, 108.2 (d, J ¼ 23.0 Hz), 107.9, 102.1, 99.0, 70.9, 55.8
(2C), 17.4. Anal. Calcd. For C25H21FN2O6S: C, 60.48; H, 4.26; N, 5.64.
Found: C, 60.51; H, 4.27; N, 5.66. ESI-MS: m/z 497.1 [MþH]þ.
148.9, 146.4, 135.9 (d, J ¼ 12.2 Hz), 124.3, 116.0 (d, J ¼ 2.6 Hz), 114.5,
108.1 (d, J ¼ 22.7 Hz), 107.9, 102.1, 99.0, 55.8 (2C). Anal. Calcd. For
C
18H15FN2O4: C, 63.15; H, 4.42; N, 8.18. Found: C, 63.16; H, 4.44; N,
8.17. ESI-MS: m/z 343.1 [MþH]þ.
4.1.4.3. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-1-oxopropan-2-yl 2-naphthoate (10c). White solid, yield:
4.1.3. Synthesis of 3-fluoro-4-(6,7-dimethoxyquinolin-4-yloxy)
phenylisocyanide (9)
81.6%, m.p.: 122e124 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
d 10.66 (s,
A solution of 8 (1.36 g, 4.0 mmol) and Et3N (1.68 mL, 12.0 mmol)
in CHCl3 (12.0 mL) was cooled at 0 ꢀC, then phosphorous oxy-
chloride (0.44 mL, 4.8 mmol) was added dropwise. The reaction
was allowed to proceed at 0 ꢀC for 30 min and then at room tem-
perature for an additional 8 h with continuous stirring. After the
reaction was completed, an aqueous saturated solution of sodium
carbonate was added to quench the reaction at a sufficiently slow
rate in order to maintain 10e15 ꢀC. After stirring for 1 h at room
temperature, more water (20 mL) and CHCl3 (20 mL) were added
and the organic layer was washed with water (3 ꢁ 20 mL), dried
with sodium sulfate, and evaporated. The residue was purified by
column chromatography (hexane/ethyl acetate ¼ 1:2) to yield the
compound 9 (1.20 g) as a pale yellow solid, yield: 92.0%, m.p.:
1H), 8.70 (s, 1H), 8.46 (d, J ¼ 5.2 Hz, 1H), 8.17 (d, J ¼ 8.0 Hz, 1H),
8.08e8.01 (m, 3H), 7.88 (d, J ¼ 12.8 Hz, 1H), 7.70e7.61 (m, 2H), 7.52
(s, 1H), 7.49e7.41 (m, 2H), 7.39 (s, 1H), 6.45 (d, J ¼ 4.8 Hz, 1H), 5.37
(q, J ¼ 6.8 Hz, 1H), 3.93 (s, 6H), 1.66 (d, J ¼ 6.4 Hz, 3H). 13C NMR
(100 MHz, DMSO‑d6)
d
169.3, 165.5, 159.4, 153.5 (d, J ¼ 244.4 Hz),
152.7, 149.5, 148.8, 146.3, 137.6 (d, J ¼ 9.8 Hz), 135.8 (d, J ¼ 12.1 Hz),
135.2, 132.1, 130.9, 129.4, 128.8, 128.5, 127.8, 127.1, 126.5, 124.9,
124.2, 116.2, 114.5, 108.2 (d, J ¼ 22.9 Hz), 107.8, 102.1, 99.0, 71.0, 55.8
(2C), 17.5. Anal. Calcd. For C31H25FN2O6: C, 68.88; H, 4.66; N, 5.18.
Found: C, 68.85; H, 4.67; N, 5.20. ESI-MS: m/z 541.2 [MþH]þ.
4.1.4.4. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-1-oxopropan-2-yl benzoate (10d). White solid, yield: 72.4%,
164e167 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
d
8.49 (d, J ¼ 4.8 Hz, 1H),
m.p.: 91e93 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
d 10.70 (s, 1H), 8.46
7.94 (d, J ¼ 10.8 Hz, 1H), 7.57e7.54 (m, 2H), 7.47 (s, 1H), 7.41 (s, 1H),
(d, J ¼ 5.6 Hz, 1H), 8.02 (d, J ¼ 7.2 Hz, 2H), 7.87 (dd, J ¼ 2.0, 12.8 Hz,
1H), 7.68 (t, J ¼ 7.2 Hz, 1H), 7.56 (d, J ¼ 7.6 Hz, 2H), 7.53 (s, 1H), 7.50
(dd, J ¼ 1.6, 9.2 Hz, 1H), 7.44 (d, J ¼ 8.8 Hz, 1H), 7.40 (s, 1H), 6.46 (d,
J ¼ 4.8 Hz,1H), 5.31 (q, J ¼ 6.8 Hz,1H), 3.94 (s, 6H),1.61 (d, J ¼ 6.8 Hz,
6.57 (d, J ¼ 5.2 Hz, 1H), 3.94 (s, 6H). 13C NMR (100 MHz, DMSO‑d6)
d
165.3, 158.3, 153.4 (d, J ¼ 249.0 Hz), 152.8, 149.7, 148.8, 146.6,142.3
(d, J ¼ 11.7 Hz), 124.7, 124.5 (d, J ¼ 3.5 Hz), 116.7, 116.4, 114.7, 107.9,
103.1, 98.6, 55.8 (2C). Anal. Calcd. For C18H13FN2O3: C, 66.66; H,
4.04; N, 8.64. Found: C, 66.68; H, 4.03; N, 8.66. ESI-MS: m/z 325.1
[MþH]þ.
3H). 13C NMR (100 MHz, DMSO‑d6)
d 169.2, 165.3, 159.5, 153.5 (d,
J ¼ 244.2 Hz), 152.8,149.6, 148.6, 146.1, 137.7 (d, J ¼ 9.9 Hz), 135.8 (d,
J ¼ 12.3 Hz), 133.6, 129.4 (2C), 129.3, 128.8 (2C), 124.2, 116.2 (d,
J ¼ 2.5 Hz), 114.5, 108.2 (d, J ¼ 23.0 Hz), 107.6, 102.1, 99.0, 70.8, 55.8
(2C), 17.4. Anal. Calcd. For C27H23FN2O6: C, 66.12; H, 4.73; N, 5.71.
Found: C, 66.13; H, 4.75; N, 5.72. ESI-MS: m/z 491.2 [MþH]þ.
4.1.4. General procedure for synthesis of 6,7-dimethoxy-4-(2-
fluorophenoxy)quinoline derivatives bearing
moiety 10a-y
a-acyloxycarboxamide
To a solution of aldehyde/ketone (0.4 mmol) in THF/H2O (0.5 mL,
v/v ¼ 3:1) was added carboxylic acid (0.4 mmol) and 9 (0.2 mmol)
at room temperature. The reaction mixture was subsequently
heated at 40 ꢀC for 24 h. Upon completion of the reaction (TLC
monitoring), the mixture was cooled to room temperature and
solvent was evaporated. The residue was purified by chromatog-
raphy on silica gel using ethyl acetate/hexaneas eluent to give 10a-
y.
4.1.4.5. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-1-oxopentan-2-yl benzoate (10e). White solid, yield: 68.3%,
m.p.: 99e101 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
d 10.62 (s, 1H), 8.45
(d, J ¼ 4.8 Hz, 1H), 8.03 (d, J ¼ 7.6 Hz, 2H), 7.86 (d, J ¼ 13.2 Hz, 1H),
7.69 (t, J ¼ 7.6 Hz, 1H), 7.58e7.54 (m, 2H), 7.52 (s, 1H), 7.48e7.41 (m,
2H), 7.39 (s, 1H), 6.45 (d, J ¼ 5.2 Hz, 1H), 5.19 (t, J ¼ 7.2 Hz, 1H), 3.93
(s, 6H), 1.98e1.91 (m, 2H), 1.56e1.49 (m, 2H), 0.97 (t, J ¼ 7.2 Hz, 3H).
13C NMR (100 MHz, DMSO‑d6)
d 168.7, 165.5, 159.4, 153.5 (d,
J ¼ 244.3 Hz), 152.7, 149.5, 148.9, 146.4, 137.6 (d, J ¼ 9.7 Hz), 135.8 (d,
J ¼ 12.3 Hz), 133.8, 129.5 (2C), 129.2, 128.9 (2C), 124.3, 116.2 (d,
J ¼ 1.5 Hz), 114.6, 108.2 (d, J ¼ 22.6 Hz), 107.9, 102.1, 99.0, 74.2, 55.8
(2C), 33.4, 18.3, 13.7. Anal. Calcd. For C29H27FN2O6: C, 67.17; H, 5.25;
N, 5.40. Found: C, 67.18; H, 5.27; N, 5.41. ESI-MS: m/z 519.2 [MþH]þ.
4.1.4.1. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-1-oxopropan-2-yl
White solid, yield: 65.6%, m.p.: 82e85 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
cyclopentanecarboxylate
(10a).
d
10.53 (s, 1H), 8.46 (d, J ¼ 5.2 Hz, 1H), 7.84 (dd, J ¼ 1.6,
12.8 Hz, 1H), 7.52 (s, 1H), 7.47 (dd, J ¼ 2.0, 9.2 Hz, 1H), 7.43 (d,
J ¼ 8.8 Hz, 1H), 7.40 (s, 1H), 6.45 (d, J ¼ 5.2 Hz, 1H), 5.05 (q,
J ¼ 6.8 Hz, 1H), 3.94 (s, 6H), 2.87e2.79 (m, 1H), 1.86e1.68 (m, 4H),
1.62e1.51 (m, 4H), 1.45 (d, J ¼ 6.8 Hz, 3H). 13C NMR (100 MHz,
4.1.4.6. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
carbamoyl)cyclohexyl benzoate (10f). White solid, yield: 45.2%,
m.p.: 203e205 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
d 10.24 (s, 1H),
DMSO‑d6)
d
175.4, 169.4, 159.5, 153.5 (d, J ¼ 244.1 Hz), 152.8, 149.6,
8.44 (d, J ¼ 4.8 Hz, 1H), 8.06 (d, J ¼ 7.6 Hz, 1H), 7.85 (d, J ¼ 12.8 Hz,
2H), 7.69 (t, J ¼ 6.8 Hz,1H), 7.59e7.54 (m, 3H), 7.51 (s,1H), 7.39e7.35
(m, 2H), 6.43 (d, J ¼ 4.8 Hz, 1H), 3.93 (s, 6H), 2.34e2.31 (m, 2H),
1.93e1.88 (m, 2H), 1.69e1.57 (m, 4H), 1.35e1.28 (m, 2H). 13C NMR
148.6, 146.1, 137.7 (d, J ¼ 10.0 Hz), 135.7 (d, J ¼ 12.4 Hz), 124.2, 116.1
(d, J ¼ 2.9 Hz), 114.5, 108.1 (d, J ¼ 23.0 Hz), 107.6, 102.1, 99.0, 69.8,
55.8 (2C), 42.6, 29.5, 29.3, 25.5, 25.4, 17.3. Anal. Calcd. For
C
26H27FN2O6: C, 64.72; H, 5.64; N, 5.81. Found: C, 64.74; H, 5.65; N,
(100 MHz, DMSO‑d6)
d
171.2, 164.5, 159.4, 153.3 (d, J ¼ 244.1 Hz),

X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
11
152.7, 149.5, 148.8, 146.4, 137.9 (d, J ¼ 9.4 Hz), 135.7 (d, J ¼ 12.1 Hz),
133.6, 130.0, 129.6 (2C), 128.8 (2C), 123.8, 116.9 (d, J ¼ 2.3 Hz), 114.5,
108.9 (d, J ¼ 22.9 Hz), 107.8, 102.1, 99.0, 81.7, 55.8 (2C), 31.5 (2C),
24.6, 21.2 (2C). Anal. Calcd. For C31H29FN2O6: C, 68.37; H, 5.37; N,
5.14. Found: C, 68.38; H, 5.37; N, 5.16. ESI-MS: m/z 545.2 [MþH]þ.
(10k). White solid, yield: 78.6%, m.p.: 123e125 ꢀC. 1H NMR
(400 MHz, DMSO‑d6)
d
10.63 (s, 1H), 8.45 (d, J ¼ 5.2 Hz, 1H), 7.87
(dd, J ¼ 1.6, 12.8 Hz, 1H), 7.51 (s, 1H), 7.47 (dd, J ¼ 2.0, 9.2 Hz, 1H),
7.44 (d, J ¼ 8.8 Hz, 1H), 7.39 (s, 1H), 7.29 (s, 2H), 6.46 (d, J ¼ 5.2 Hz,
1H), 4.86 (s, 1H), 3.93 (s, 6H), 3.84 (s, 6H), 3.74 (s, 3H), 1.13 (s, 9H).
13C NMR (100 MHz, DMSO‑d6)
d 167.2, 165.1, 159.4, 153.5 (d,
4.1.4.7. 2-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-2-oxo-1-phenylethyl benzoate (10g). White solid, yield:
J ¼ 244.2 Hz), 152.9 (2C), 152.7, 149.5, 148.9, 146.4, 142.2, 137.4 (d,
J ¼ 9.8 Hz), 135.9 (d, J ¼ 12.5 Hz), 124.3 (d, J ¼ 4.6 Hz), 116.3, 114.5,
108.2 (d, J ¼ 23.2 Hz), 107.9, 106.6 (2C), 102.2, 99.0, 81.2, 60.3, 56.0
(2C), 55.8 (2C), 34.0, 26.2 (3C). Anal. Calcd. For C33H35FN2O9: C,
63.66; H, 5.67; N, 4.50. Found: C, 63.68; H, 5.68; N, 4.48. ESI-MS: m/
z 623.2 [MþH]þ.
40.8%, m.p.: 93e95 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
d 10.96 (s, 1H),
8.42 (d, J ¼ 3.6 Hz, 1H), 8.07 (d, J ¼ 7.2 Hz, 2H), 7.84 (d, J ¼ 12.8 Hz,
1H), 7.73e7.69 (m, 3H), 7.59e7.55 (m, 2H), 7.50e7.41 (m, 6H), 7.39
(s, 1H), 6.44 (d, J ¼ 4.4 Hz, 1H), 6.26 (s, 1H), 3.93 (s, 6H). 13C NMR
(100 MHz, DMSO‑d6)
d
167.1, 165.3, 159.3, 153.5 (d, J ¼ 244.7 Hz),
152.7, 149.5, 148.8, 146.3, 137.4 (d, J ¼ 9.8 Hz), 135.9 (d, J ¼ 12.5 Hz),
134.9, 133.9, 129.5 (2C), 129.1, 129.0 (2C), 128.8 (2C), 128.6, 127.5
(2C), 124.3, 116.1 (d, J ¼ 2.6 Hz), 114.5, 108.1 (d, J ¼ 21.7 Hz), 107.8,
102.1, 99.0, 75.8, 55.8 (2C). Anal. Calcd. For C32H25FN2O6: C, 69.56;
H, 4.56; N, 5.07. Found: C, 69.57; H, 4.55; N, 5.10. ESI-MS: m/z 553.2
[MþH]þ.
4.1.4.12. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl 4-(tert-butyl)benzoate (10l).
White solid, yield: 75.2%, m.p.: 133e135 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
d
10.59 (s, 1H), 8.44 (d, J ¼ 5.2 Hz, 1H), 7.96 (d, J ¼ 8.8 Hz,
2H), 7.87 (dd, J ¼ 2.0, 13.2 Hz, 1H), 7.58 (d, J ¼ 8.4 Hz, 2H), 7.51 (s,
1H), 7.48 (dd, J ¼ 2.0, 8.8 Hz, 1H), 7.44 (d, J ¼ 8.8 Hz, 1H), 7.39 (s, 1H),
6.46 (d, J ¼ 4.8 Hz, 1H), 4.87 (s, 1H), 3.93 (s, 6H), 1.29 (s, 9H), 1.12 (s,
4.1.4.8. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl benzoate (10h). White solid,
yield: 85.6%, m.p.: 129e131 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
9H). 13C NMR (100 MHz, DMSO‑d6)
d 167.3, 165.5, 159.4, 156.9, 153.5
(d, J ¼ 244.9 Hz), 152.7, 149.5, 148.9, 146.4, 137.4 (d, J ¼ 10.3 Hz),
135.8 (d, J ¼ 12.1 Hz),129.4 (2C),126.6,125.8 (2C),124.3,116.3,114.5,
108.2 (d, J ¼ 23.1 Hz), 107.9, 102.2, 99.0, 80.9, 55.8 (2C), 35.0, 34.0,
30.9 (3C), 26.2 (3C). Anal. Calcd. For C34H37FN2O6: C, 69.37; H, 6.34;
N, 4.76. Found: C, 69.39; H, 6.36; N, 4.77. ESI-MS: m/z 589.3
[MþH]þ.
d
10.65 (s, 1H), 8.45 (d, J ¼ 5.2 Hz, 1H), 8.04 (d, J ¼ 8.0 Hz, 2H), 7.87
(dd, J ¼ 1.6, 12.8 Hz, 1H), 7.70 (t, J ¼ 7.2 Hz, 1H), 7.57 (t, J ¼ 7.6 Hz,
2H), 7.51 (s, 1H), 7.48 (dd, J ¼ 2.0, 9.2 Hz, 1H), 7.44 (d, J ¼ 8.8 Hz, 1H),
7.39 (s, 1H), 6.46 (d, J ¼ 5.2 Hz, 1H), 4.90 (s, 1H), 3.93 (s, 6H), 1.13 (s,
9H). 13C NMR (100 MHz, DMSO‑d6)
d 167.3, 165.5, 159.4, 153.5 (d,
J ¼ 244.5 Hz), 152.7, 149.5, 148.9, 146.4, 137.4 (d, J ¼ 9.8 Hz), 135.9 (d,
J ¼ 12.3 Hz), 133.8, 129.4 (2C), 129.2, 129.0 (2C), 124.3, 116.3 (d,
J ¼ 2.2 Hz), 114.5, 108.3 (d, J ¼ 22.9 Hz), 107.9, 102.2, 99.0, 81.5, 55.8
(2C), 34.0, 26.2 (3C). Anal. Calcd. For C30H29FN2O6: C, 67.66; H, 5.49;
N, 5.26. Found: C, 67.67; H, 5.48; N, 5.27. ESI-MS: m/z 532.2 [M]þ.
4.1.4.13. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 74.7%, m.p.: 122e124 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
4-fluorobenzoate
(10m).
d
10.72 (s, 1H), 8.44 (d, J ¼ 5.2 Hz,1H), 8.11 (td, J ¼ 2.0, 3.2,
3.6 Hz, 2H), 7.88 (dd, J ¼ 2.4, 13.2 Hz, 1H), 7.51 (s, 1H), 7.49e7.45 (m,
1H), 7.42 (d, J ¼ 4.0 Hz, 1H), 7.40e7.37 (m, 3H), 6.45 (d, J ¼ 4.8 Hz,
1H), 4.91 (s, 1H), 3.93 (s, 6H), 1.12 (s, 9H). 13C NMR (100 MHz,
4.1.4.9. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 81.4%, m.p.: 118e120 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
4-methylbenzoate
(10i).
DMSO‑d6)
d
167.2, 165.5 (d, J ¼ 250.8 Hz), 164.6, 159.4, 153.5 (d,
J ¼ 244.3 Hz), 152.7, 149.5, 148.9, 146.4, 137.4 (d, J ¼ 9.6 Hz), 135.8 (d,
J ¼ 12.5 Hz),132.4 (d, J ¼ 9.6 Hz, 2C),125.8 (d, J ¼ 2.1 Hz),124.3,116.3
(2C), 116.1, 114.6, 108.3 (d, J ¼ 23.1 Hz), 107.9, 102.2, 99.0, 81.2, 55.8
(2C), 34.0, 26.2 (3C). Anal. Calcd. For C30H28F2N2O6: C, 65.45; H,
5.13; N, 5.09. Found: C, 65.43; H, 5.15; N, 5.10. ESI-MS: m/z 551.2
[MþH]þ.
d
10.64 (s, 1H), 8.44 (d, J ¼ 5.6 Hz, 1H), 7.92 (d, J ¼ 8.0 Hz,
2H), 7.87 (dd, J ¼ 2.0, 12.8 Hz, 1H), 7.51 (s, 1H), 7.48 (dd, J ¼ 2.0,
9.2 Hz, 1H), 7.44 (d, J ¼ 8.8 Hz, 1H), 7.39 (s, 1H), 7.36 (d, J ¼ 8.0 Hz,
2H), 6.46 (d, J ¼ 5.2 Hz, 1H), 4.88 (s, 1H), 3.93 (s, 6H), 2.38 (s, 3H),
1.12 (s, 9H). 13C NMR (100 MHz, DMSO‑d6)
d 167.3, 165.5, 159.4,
153.5 (d, J ¼ 244.2 Hz), 152.7, 149.5, 148.9, 146.4, 144.2, 137.4 (d,
J ¼ 9.6 Hz), 135.8 (d, J ¼ 12.2 Hz), 129.6 (2C), 129.5 (2C), 126.6, 124.3,
116.3 (d, J ¼ 1.9 Hz), 114.6, 108.2 (d, J ¼ 22.8 Hz), 107.9, 102.2, 99.0,
80.9, 55.8 (2C), 34.0, 26.2 (3C), 21.3. Anal. Calcd. For C31H31FN2O6: C,
68.12; H, 5.72; N, 5.13. Found: C, 68.14; H, 5.70; N, 5.15. ESI-MS: m/z
547.2 [MþH]þ.
4.1.4.14. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 74.5%, m.p.: 111e113 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
3-fluorobenzoate
(10n).
d
10.57 (s, 1H), 8.46 (d, J ¼ 5.2 Hz, 1H), 7.90 (d, J ¼ 7.6 Hz,
1H), 7.86 (dd, J ¼ 2.0, 12.8 Hz, 1H), 7.75 (d, J ¼ 8.8 Hz, 1H), 7.66e7.55
(m, 2H), 7.52 (s, 1H), 7.47 (dd, J ¼ 2.0, 9.2 Hz, 1H), 7.44 (d, J ¼ 8.4 Hz,
1H), 7.40 (s,1H), 6.48 (d, J ¼ 5.2 Hz,1H), 4.91 (s,1H), 3.94 (s, 6H),1.13
4.1.4.10. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl 4-methoxybenzoate (10j).
White solid, yield: 82.7%, m.p.: 127e129 ꢀC. 1H NMR (400 MHz,
(s, 9H). 13C NMR (100 MHz, DMSO‑d6)
d 167.0, 164.4, 162.0 (d,
J ¼ 244.1 Hz), 159.4, 153.5 (d, J ¼ 244.4 Hz), 152.7, 149.5, 148.7, 146.2,
137.2 (d, J ¼ 9.8 Hz), 135.9 (d, J ¼ 12.3 Hz), 131.4 (d, J ¼ 7.5 Hz), 131.3
(d, J ¼ 7.9 Hz), 125.6 (d, J ¼ 2.4 Hz), 124.2, 120.9 (d, J ¼ 21.0 Hz), 116.3
(d, J ¼ 2.9 Hz), 115.9 (d, J ¼ 22.8 Hz), 114.5, 108.3 (d, J ¼ 22.9 Hz),
107.7, 102.2, 99.0, 81.4, 55.8 (2C), 33.9, 26.1 (3C). Anal. Calcd. For
DMSO‑d6)
d
10.62 (s, 1H), 8.44 (d, J ¼ 5.2 Hz, 1H), 7.98 (d, J ¼ 8.8 Hz,
2H), 7.87 (d, J ¼ 13.2 Hz, 1H), 7.51 (s, 1H), 7.48 (dd, J ¼ 2.0, 9.2 Hz,
1H), 7.43 (d, J ¼ 8.8 Hz, 1H), 7.39 (s, 1H), 7.08 (d, J ¼ 8.8 Hz, 2H), 6.45
(d, J ¼ 4.8 Hz, 1H), 4.85 (s, 1H), 3.93 (s, 6H), 3.83 (s, 3H), 1.11 (s, 9H).
13C NMR (100 MHz, DMSO‑d6)
d
167.4, 165.2, 163.5, 159.4, 153.5 (d,
C30H28F2N2O6: C, 65.45; H, 5.13; N, 5.09. Found: C, 65.46; H, 5.14; N,
J ¼ 244.3 Hz), 152.7, 149.5, 148.9, 146.4, 137.5 (d, J ¼ 10.1 Hz), 135.8
(d, J ¼ 12.3 Hz), 131.6 (2C), 124.3, 121.4, 116.3, 114.6, 114.3 (2C), 108.2
(d, J ¼ 23.1 Hz), 107.9, 102.2, 99.0, 80.8, 55.8 (2C), 55.7, 34.0, 26.2
(3C). Anal. Calcd. For C31H31FN2O7: C, 66.18; H, 5.55; N, 4.98. Found:
C, 66.20; H, 5.58; N, 4.99. ESI-MS: m/z 563.2 [MþH]þ.
5.08. ESI-MS: m/z 573.2 [MþNa]þ.
4.1.4.15. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 62.5%, m.p.: 113e115 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
2-fluorobenzoate
(10o).
d
10.58 (s, 1H), 8.45 (d, J ¼ 5.2 Hz, 1H), 7.98 (td, J ¼ 1.6,
4.1.4.11. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl 3,4,5-trimethoxybenzoate
7.6 Hz, 1H), 7.86 (dd, J ¼ 2.0, 12.8 Hz, 1H), 7.75e7.70 (m, 1H), 7.52 (s,
1H), 7.48 (dd, J ¼ 2.0, 8.8 Hz, 1H), 7.44 (d, J ¼ 8.4 Hz, 1H), 7.41e7.36

12
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
(m, 3H), 6.47 (d, J ¼ 5.2 Hz, 1H), 4.90 (s, 1H), 3.94 (s, 6H), 1.12 (s, 9H).
13C NMR (100 MHz, DMSO‑d6)
167.0, 163.3, 161.3 (d, J ¼ 256.9 Hz),
4.1.4.20. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl 4-(trifluoromethyl)benzoate
(10t). White solid, yield: 74.8%, m.p.: 129e131 ꢀC. 1H NMR
d
159.3, 153.5 (d, J ¼ 244.3 Hz), 152.6, 149.5, 148.8, 146.4, 137.3 (d,
J ¼ 9.8 Hz), 153.9 (d, J ¼ 12.3 Hz), 132.0, 124.8 (d, J ¼ 3.5 Hz), 124.2,
117.5 (d, J ¼ 9.6 Hz), 117.4, 117.2, 116.3 (d, J ¼ 2.9 Hz), 114.5, 108.3 (d,
J ¼ 22.9 Hz), 107.9, 102.2, 99.0, 81.5, 55.8, 55.7, 33.8, 26.0 (3C). Anal.
Calcd. For C30H28F2N2O6: C, 65.45; H, 5.13; N, 5.09. Found: C, 65.47;
H, 5.11; N, 5.11. ESI-MS: m/z 551.2 [MþH]þ.
(400 MHz, DMSO‑d6)
d
10.69 (s, 1H), 8.45 (d, J ¼ 5.2 Hz, 1H), 8.23 (d,
J ¼ 8.0 Hz, 2H), 7.95 (d, J ¼ 8.0 Hz, 2H), 7.87 (dd, J ¼ 2.0, 13.2 Hz, 1H),
7.51 (s, 1H), 7.48 (dd, J ¼ 2.0, 9.2 Hz, 1H), 7.44 (d, J ¼ 8.8 Hz, 1H), 7.39
(s, 1H), 6.46 (d, J ¼ 5.2 Hz, 1H), 4.95 (s, 1H), 3.93 (s, 6H), 1.14 (s, 9H).
13C NMR (100 MHz, DMSO‑d6)
d 166.9, 164.5, 159.3, 153.5 (d,
J ¼ 244.4 Hz), 152.7, 149.5, 148.9, 146.4, 137.3 (d, J ¼ 9.9 Hz), 136.0 (d,
J ¼ 12.2 Hz), 133.2 (q, J ¼ 31.8 Hz), 132.9, 130.3 (2C), 126.0 (q,
J ¼ 3.2 Hz, 2C), 124.2, 123.8 (q, J ¼ 271.4 Hz), 116.3 (d, J ¼ 2.2 Hz),
114.6, 108.3 (d, J ¼ 22.8 Hz), 107.9, 102.2, 99.0, 81.5, 55.6 (2C), 34.0,
26.1 (3C). Anal. Calcd. For C31H28F4N2O6: C, 62.00; H, 4.70; N, 4.66.
Found: C, 62.02; H, 4.68; N, 4.67. ESI-MS: m/z 601.2 [MþH]þ.
4.1.4.16. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 70.8%, m.p.: 128e130 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
4-chlorobenzoate
(10p).
d
10.67 (s, 1H), 8.44 (d, J ¼ 5.2 Hz, 1H), 8.03 (d, J ¼ 8.4 Hz,
2H), 7.87 (dd, J ¼ 2.0, 12.8 Hz, 1H), 7.63 (d, J ¼ 8.4 Hz, 2H), 7.51 (s,
1H), 7.49 (dd, J ¼ 2.0, 8.8 Hz, 1H), 7.44 (d, J ¼ 8.8 Hz, 1H), 7.39 (s, 1H),
6.45 (d, J ¼ 4.8 Hz,1H), 4.91 (s,1H), 3.93 (s, 6H), 1.12 (s, 9H). 13C NMR
4.1.4.21. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl 3,4-dichlorobenzoate (10u).
White solid, yield: 74.9%, m.p.: 119e121 ꢀC. 1H NMR (400 MHz,
(100 MHz, DMSO‑d6)
d
167.1, 164.7, 159.4, 153.5 (d, J ¼ 245.0 Hz),
152.7, 149.5, 148.9, 146.4, 138.8, 137.4 (d, J ¼ 9.8 Hz), 135.9 (d,
J ¼ 12.2 Hz), 131.3 (2C), 129.2 (2C), 128.0, 124.3, 116.3 (d, J ¼ 1.3 Hz),
114.6, 108.3 (d, J ¼ 20.6 Hz), 107.9, 102.2, 99.0, 81.3, 55.8 (2C), 34.0,
26.2 (3C). Anal. Calcd. For C30H28ClFN2O6: C, 63.55; H, 4.98; N, 4.94.
Found: C, 63.56; H, 5.01; N, 4.92. ESI-MS: m/z 567.2 [MþH]þ.
DMSO‑d6)
d
10.56 (s, 1H), 8.45 (d, J ¼ 4.0 Hz, 1H), 8.14 (s, 1H), 7.99 (d,
J ¼ 8.0 Hz,1H), 7.86e7.83 (m, 2H), 7.51 (s,1H), 7.45 (t, J ¼ 9.2 Hz, 2H),
7.39 (s, 1H), 6.46 (d, J ¼ 4.4 Hz, 1H), 4.91 (s, 1H), 3.93 (s, 6H), 1.13 (s,
9H). 13C NMR (100 MHz, DMSO‑d6)
d 166.8, 163.7, 159.3, 153.5 (d,
J ¼ 244.1 Hz), 152.7, 149.5, 148.8, 146.4, 137.2 (d, J ¼ 9.9 Hz), 136.8,
136.0 (d, J ¼ 12.3 Hz), 131.9, 131.4, 130.9, 129.6, 129.4, 124.2, 116.4 (d,
J ¼ 1.9 Hz), 114.5, 108.4 (d, J ¼ 22.9 Hz), 107.8, 102.2, 99.0, 81.6, 55.8
(2C), 33.9, 26.1 (3C). Anal. Calcd. For C30H27Cl2FN2O6: C, 59.91; H,
4.52; N, 4.66. Found: C, 59.90; H, 4.54; N, 4.67. ESI-MS: m/z 601.2
[MþH]þ.
4.1.4.17. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 72.3%, m.p.: 108e110 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
3-chlorobenzoate
(10q).
d
10.55 (s, 1H), 8.45 (d, J ¼ 4.8 Hz, 1H), 8.01e7.98 (m, 2H),
7.88e7.78 (m, 2H), 7.62 (t, J ¼ 8.0 Hz, 1H), 7.51 (s, 1H), 7.47e7.42 (m,
2H), 7.39 (s,1H), 6.46 (d, J ¼ 4.8 Hz,1H), 4.90 (s,1H), 3.93 (s, 6H),1.13
4.1.4.22. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl thiophene-2-carboxylate
(10v). Pale yellow solid, yield: 82.6%, m.p.: 124e126 ꢀC. 1H NMR
(s, 9H). 13C NMR (100 MHz, DMSO‑d6)
d 166.9, 164.3, 159.3, 153.5 (d,
J ¼ 244.4 Hz), 152.7, 149.5, 148.8, 146.4, 137.2 (d, J ¼ 9.6 Hz), 135.9 (d,
J ¼ 12.2 Hz), 133.6, 131.2, 131.0, 128.8, 128.1, 124.2, 116.3 (d,
J ¼ 2.6 Hz), 114.5, 108.4 (d, J ¼ 23.0 Hz), 107.9, 102.2, 99.0, 81.5, 55.8
(2C), 33.9, 26.1 (3C). Anal. Calcd. For C30H28ClFN2O6: C, 63.55; H,
4.98; N, 4.94. Found: C, 63.54; H, 5.00; N, 4.96. ESI-MS: m/z 567.2
[MþH]þ.
(400 MHz, DMSO‑d6)
d
10.65 (s, 1H), 8.44 (d, J ¼ 5.2 Hz, 1H), 8.01
(dd, J ¼ 1.2, 5.2 Hz, 1H), 7.90e7.85 (m, 2H), 7.51 (s, 1H), 7.47 (dd,
J ¼ 2.0, 9.2 Hz,1H), 7.44 (d, J ¼ 8.4 Hz,1H), 7.39 (s,1H), 7.26e7.24 (m,
1H), 6.46 (d, J ¼ 5.2 Hz, 1H), 4.85 (s, 1H), 3.93 (s, 6H), 1.10 (s, 9H). 13
C
NMR (100 MHz, DMSO‑d6)
d 167.0, 161.3, 159.4, 153.5 (d,
J ¼ 244.5 Hz), 152.7, 149.5, 148.9, 146.4, 137.4 (d, J ¼ 9.8 Hz), 135.9 (d,
J ¼ 12.3 Hz), 134.7, 134.4, 132.2, 128.7, 124.3, 116.3, 114.6, 108.3 (d,
J ¼ 23.1 Hz), 107.9, 102.2, 99.0, 81.1, 55.8 (2C), 34.0, 26.1 (3C). Anal.
Calcd. For C28H27FN2O6S: C, 62.44; H, 5.05; N, 5.20. Found: C, 62.45;
H, 5.07; N, 5.18. ESI-MS: m/z 539.2 [MþH]þ.
4.1.4.18. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 58.6%, m.p.: 103e105 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
2-chlorobenzoate
(10r).
d
10.59 (s, 1H), 8.45 (d, J ¼ 5.2 Hz, 1H), 7.95 (d, J ¼ 8.0 Hz,
1H), 7.87 (dd, J ¼ 2.0, 12.8 Hz, 1H), 7.65e7.60 (m, 2H), 7.54e7.51 (m,
2H), 7.48 (dd, J ¼ 2.4, 9.2 Hz, 1H), 7.44 (d, J ¼ 8.4 Hz, 1H), 7.40 (s, 1H),
6.47 (d, J ¼ 5.2 Hz,1H), 4.92 (s,1H), 3.94 (s, 6H),1.12 (s, 9H). 13C NMR
4.1.4.23. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl furan-2-carboxylate (10w).
White solid, yield: 79.8%, m.p.: 105e107 ꢀC. 1H NMR (400 MHz,
(100 MHz, DMSO‑d6)
d
166.9, 164.6, 159.3, 153.5 (d, J ¼ 244.6 Hz),
152.6, 149.5, 148.8, 146.4, 137.2 (d, J ¼ 9.9 Hz), 135.9 (d, J ¼ 12.1 Hz),
133.8, 132.4, 131.7, 131.1, 128.9, 127.6, 124.2, 116.2 (d, J ¼ 3.3 Hz),
114.5, 108.2 (d, J ¼ 22.7 Hz), 107.9, 102.1, 98.9, 81.7, 55.7 (2C), 33.8,
26.1 (3C). Anal. Calcd. For C30H28ClFN2O6: C, 63.55; H, 4.98; N, 4.94.
Found: C, 63.55; H, 5.00; N, 4.92. ESI-MS: m/z 567.2 [MþH]þ.
DMSO‑d6)
d
10.54 (s, 1H), 8.45 (d, J ¼ 5.2 Hz, 1H), 8.03 (d, J ¼ 0.8 Hz,
1H), 7.85 (dd, J ¼ 2.0, 12.8 Hz, 1H), 7.52 (s, 1H), 7.47 (dd, J ¼ 2.4,
9.2 Hz, 1H), 7.44e7.42 (m, 2H), 7.39 (s, 1H), 6.74 (dd, J ¼ 1.6, 3.6 Hz,
1H), 6.47 (d, J ¼ 4.8 Hz, 1H), 4.85 (s, 1H), 3.94 (s, 6H), 1.09 (s, 9H). 13
C
NMR (100 MHz, DMSO‑d6)
d 166.9, 159.3, 157.6, 153.5 (d,
J ¼ 244.4 Hz), 152.7, 149.5, 148.8, 148.2, 146.4, 143.3, 132.2 (d,
J ¼ 9.5 Hz), 135.9 (d, J ¼ 12.3 Hz), 124.2, 119.3, 116.3 (d, J ¼ 2.8 Hz),
114.5, 112.5, 108.3 (d, J ¼ 22.8 Hz), 107.9, 102.2, 99.0, 80.8, 55.8 (2C),
33.9, 26.0 (3C). Anal. Calcd. For C28H27FN2O7: C, 64.36; H, 5.21; N,
5.36. Found: C, 64.37; H, 5.20; N, 5.36. ESI-MS: m/z 523.2 [MþH]þ.
4.1.4.19. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 75.8%, m.p.: 114e116 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
4-bromobenzoate
(10s).
d
10.57 (s, 1H), 8.45 (d, J ¼ 4.4 Hz, 1H), 7.96 (d, J ¼ 7.6 Hz,
2H), 7.85 (d, J ¼ 12.8 Hz, 1H), 7.78 (d, J ¼ 7.2 Hz, 2H), 7.51 (s, 1H),
7.48e7.42 (m, 2H), 7.39 (s, 1H), 6.46 (d, J ¼ 4.8 Hz, 1H), 4.89 (s, 1H),
4.1.4.24. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
3.93 (s, 6H), 1.12 (s, 9H). 13C NMR (100 MHz, DMSO‑d6)
d
167.0,
amino)-3,3-dimethyl-1-oxobutan-2-yl
(10x). White solid, yield: 50.7%, m.p.: 106e108 ꢀC. 1H NMR
(400 MHz, DMSO‑d6)
cyclopentanecarboxylate
164.9, 159.3, 153.5 (d, J ¼ 244.4 Hz), 152.6, 149.5, 148.9, 146.4, 137.2
(d, J ¼ 9.8 Hz), 135.9 (d, J ¼ 12.3 Hz), 132.1 (2C), 131.3 (2C), 128.4,
127.9, 124.2, 116.3 (d, J ¼ 2.6 Hz), 114.5, 108.3 (d, J ¼ 22.8 Hz), 107.9,
102.2, 99.0, 81.3, 55.8 (2C), 34.0, 26.1 (3C). Anal. Calcd. For
d
10.48 (s, 1H), 8.44 (d, J ¼ 5.2 Hz, 1H), 7.86 (d,
J ¼ 13.2 Hz, 1H), 7.51 (s, 1H), 7.47e7.41 (m, 2H), 7.39 (s, 1H), 6.45 (d,
J ¼ 5.2 Hz, 1H), 4.65 (s, 1H), 3.93 (s, 6H), 2.90e2.82 (m, 1H),
1.87e1.72 (m, 4H), 1.59e1.54 (m, 4H), 1.02 (s, 9H). 13C NMR
C
30H28BrFN2O6: C, 58.93; H, 4.62; N, 4.58. Found: C, 58.91; H, 4.63;
N, 4.59. ESI-MS: m/z 611.1 [MþH]þ.
(100 MHz, DMSO‑d6)
d
175.5, 167.4, 159.4, 153.5 (d, J ¼ 244.4 Hz),

X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
13
152.7, 149.5, 148.9, 146.4, 137.4 (d, J ¼ 10.0 Hz), 135.8 (d, J ¼ 12.3 Hz),
124.3, 116.2 (d, J ¼ 1.7 Hz), 114.5, 108.2 (d, J ¼ 22.9 Hz), 107.9, 102.1,
99.0, 80.2, 55.8 (2C), 42.9, 33.7, 29.5, 29.2, 26.0 (3C), 25.5, 25.4. Anal.
Calcd. For C29H33FN2O6: C, 66.40; H, 6.34; N, 5.34. Found: C, 66.38;
H, 6.35; N, 5.33. ESI-MS: m/z 525.2 [MþH]þ.
fluorobenzamide (11c). White solid, yield: 61.2%, m.p.: 108e110 ꢀC.
1H NMR (400 MHz, CDCl3)
7.81 (d, J ¼ 11.6 Hz, 1H), 7.60 (s, 1H), 7.53 (m, 2H), 7.45 (s, 1H),
7.31e7.22 (m, 2H), 7.16 (t, J ¼ 8.0 Hz, 2H), 6.44 (d, J ¼ 4.0 Hz, 1H),
4.07 (s, 3H), 4.05 (s, 3H), 3.82 (s, 1H), 3.64e3.57 (m, 1H), 1.96e1.65
(m, 6H), 1.30 (s, 9H), 1.25e1.07 (m, 4H). 13C NMR (100 MHz, CDCl3)
d
11.31 (s, 1H), 8.49 (d, J ¼ 4.0 Hz, 1H),
4.1.4.25. 1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
d
174.6, 171.0, 163.9 (d, J ¼ 250.0 Hz), 160.1, 154.3 (d, J ¼ 247.8 Hz),
amino)-3,3-dimethyl-1-oxobutan-2-yl
White solid, yield: 84.6%, m.p.: 134e136 ꢀC. 1H NMR (400 MHz,
DMSO‑d6)
2-naphthoate
(10y).
152.8, 149.4, 148.5, 146.5, 137.0 (d, J ¼ 9.5 Hz), 136.7 (d, J ¼ 12.5 Hz),
132.5, 128.8 (d, J ¼ 8.5 Hz, 2C), 123.6, 116.1 (d, J ¼ 3.0 Hz), 115.9 (d,
J ¼ 21.8 Hz, 2C), 115.4, 109.4 (d, J ¼ 22.6 Hz), 107.5, 102.1, 99.3, 72.4,
62.9, 56.0 (2C), 36.0, 31.7, 30.8, 29.6 (3C), 25.6, 25.2, 24.5. Anal.
Calcd. For C36H39F2N3O5: C, 68.45; H, 6.22; N, 6.65. Found: C, 68.46;
H, 6.20; N, 6.68. ESI-MS: m/z 632.3 [MþH]þ.
d
10.71 (s, 1H), 8.70 (s, 1H), 8.45 (d, J ¼ 5.2 Hz,1H), 8.18 (d,
J ¼ 8.0 Hz, 1H), 8.09e8.01 (m, 3H), 7.90 (dd, J ¼ 2.4, 13.2 Hz, 1H),
7.70e7.61 (m, 2H), 7.52e7.50 (m, 2H), 7.44 (t, J ¼ 8.8 Hz, 1H), 7.39 (s,
1H), 6.46 (d, J ¼ 5.2 Hz, 1H), 4.98 (s, 1H), 3.93 (s, 6H), 1.18 (s, 9H). 13
C
NMR (100 MHz, DMSO‑d6)
d 167.3, 165.7, 159.4, 153.5 (d,
J ¼ 244.5 Hz), 152.7, 149.5, 148.9, 146.4, 137.4 (d, J ¼ 9.6 Hz), 135.9 (d,
J ¼ 12.3 Hz),135.3,132.1,131.0,129.6,128.9,128.7,127.8,127.2,126.5,
124.9, 124.3, 116.3 (d, J ¼ 2.5 Hz), 114.6, 108.3 (d, J ¼ 22.5 Hz), 107.9,
102.2, 99.0, 81.3, 55.8 (2C), 34.1, 26.3 (3C). Anal. Calcd. For
4.1.5.4. N-(1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl)-4-fluoro-N-
benzamide (11d). White solid, yield: 48.5%, m.p.: 84e86 ꢀC. 1H NMR
(400 MHz, CDCl3)
Phenyl-
d
9.79 (s, 1H), 8.52 (d, J ¼ 4.0 Hz, 1H), 7.87 (d,
C
34H31FN2O6: C, 70.09; H, 5.36; N, 4.81. Found: C, 70.07; H, 5.38; N,
J ¼ 11.6 Hz, 1H), 7.61 (s, 1H), 7.48 (s, 1H), 7.33e7.24 (m, 8H), 6.87 (t,
J ¼ 8.0 Hz, 3H), 6.47 (d, J ¼ 4.4 Hz, 1H), 5.00 (s, 1H), 4.09 (s, 3H), 4.07
4.83. ESI-MS: m/z 583.2 [MþH]þ.
(s, 3H), 1.22 (s, 9H). 13C NMR (100 MHz, CDCl3)
d 172.6, 169.0, 163.2
4.1.5. General procedure for synthesis of 6,7-dimethoxy-4-(2-
(d, J ¼ 250.1 Hz), 160.2, 154.4 (d, J ¼ 248.2 Hz), 152.9, 149.6, 148.5,
146.5, 137.1 (d, J ¼ 12.4 Hz), 136.8 (d, J ¼ 9.6 Hz), 131.8 (d, J ¼ 3.3 Hz),
130.6 (d, J ¼ 8.6 Hz, 2C), 129.2 (2C), 128.8, 127.9 (2C), 123.7, 116.2 (d,
J ¼ 3.0 Hz), 115.5, 115.0 (d, J ¼ 21.8 Hz, 2C), 109.5 (d, J ¼ 22.8 Hz),
107.5, 102.2, 99.4, 65.5, 56.1 (2C), 35.7, 28.6 (3C). Anal. Calcd. For
fluorophenoxy)quinoline derivatives bearing
moiety 11a-g
a-acylaminoamide
Pivaldehyde (0.4 mmol), carboxylic acid (0.4 mmol), and 9
(0.2 mmol) were added sequentially to a solution of amine
(0.4 mmol) in MeOH (1.0 mL) at room temperature. The reaction
mixture was heated at 60 ꢀC for 24 h. Upon completion of the re-
action (TLC monitoring), the mixture cooled to room temperature
and solvent was evaporated. The crude reaction mixture was pu-
rified by column chromatography (ethyl acetate/hexane) to give the
target products 11a-g.
C
36H33F2N3O5: C, 69.11; H, 5.32; N, 6.72. Found: C, 67.13; H, 5.34; N,
6.73. ESI-MS: m/z 626.2 [MþH]þ.
4 .1. 5 . 5 . N - ( 3 , 4 - D i m e t h o x y p h e n y l ) - N - ( 1 - ( ( 4 - ( ( 6 , 7 -
dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)amino)-3,3-dimethyl-
1- oxobutan-2-yl)-4-fluorobenzamide (11e). Pale red solid, yield:
65.4%, m.p.: 102e104 ꢀC. 1H NMR (400 MHz, DMSO‑d6)
d 10.69 (s,
4.1.5.1. N-Butyl-N-(1-((4-((6,7-dimethoxyquinolin-4-yl)oxy)-3-
fluorophenyl)amino)-3,3-dimethyl-1-oxobutan-2-yl)-4-
fluorobenzamide (11a). White solid, yield: 67.3%, m.p.: 97e99 ꢀC. 1H
1H), 8.47 (d, J ¼ 5.2 Hz, 1H), 7.89 (d, J ¼ 13.2 Hz, 1H), 7.58 (d,
J ¼ 8.8 Hz, 1H), 7.52 (s, 1H), 7.44 (d, J ¼ 8.8 Hz, 1H), 7.40 (s, 1H),
7.32e7.29 (m, 3H), 7.01 (t, J ¼ 8.8 Hz, 2H), 6.70e6.66 (m, 2H), 6.43
(d, J ¼ 5.2 Hz, 1H), 5.47 (s, 1H), 3.94 (s, 6H), 3.64 (s, 3H), 3.55 (s, 3H),
NMR (400 MHz, DMSO‑d6)
d
10.76 (s, 1H), 8.46 (d, J ¼ 4.8 Hz, 1H),
7.87 (d, J ¼ 12.8 Hz, 1H), 7.51 (m, 4H), 7.44 (d, J ¼ 9.2 Hz, 1H), 7.40 (s,
1H), 7.28 (t, J ¼ 8.0 Hz, 2H), 6.45 (d, J ¼ 4.8 Hz, 1H), 5.27 (s, 1H), 3.93
(s, 6H), 3.49 (m, 2H), 1.26e0.95 (m, 13H), 0.51 (t, 3H). 13C NMR
1.04 (s, 9H). 13C NMR (100 MHz, DMSO‑d6)
d 170.9, 168.5, 161.8 (d,
J ¼ 245.0 Hz), 159.4, 153.4 (d, J ¼ 244.2 Hz), 152.7, 149.5, 148.9, 147.8,
147.7, 146.5, 137.9 (d, J ¼ 9.7 Hz), 135.8 (d, J ¼ 12.3 Hz), 133.8 (d,
J ¼ 2.2 Hz), 133.6, 132.1 (d, J ¼ 9.5 Hz), 130.2 (d, J ¼ 8.5 Hz, 2C), 124.1,
116.7, 115.6 (d, J ¼ 21.6 Hz), 114.6 (d, J ¼ 14.9 Hz, 2C), 114.5, 110.4,
108.7 (d, J ¼ 22.5 Hz), 107.9, 102.1, 99.0, 69.8, 65.7, 55.8 (2C), 55.4,
35.6, 27.9 (3C). Anal. Calcd. For C38H37F2N3O7: C, 66.56; H, 5.44; N,
6.13. Found: C, 66.55; H, 5.46; N, 6.13. ESI-MS: m/z 686.3 [MþH]þ.
(100 MHz, DMSO‑d6)
d
171.4, 168.2, 162.3 (d, J ¼ 245.0 Hz), 159.3,
153.4 (d, J ¼ 244.3 Hz), 152.7, 149.5, 148.9, 146.4, 135.9 (d,
J ¼ 11.5 Hz), 133.8 (d, J ¼ 3.2 Hz), 132.1 (d, J ¼ 9.2 Hz), 129,1 (d,
J ¼ 7.6 Hz, 2C), 124.1, 116.6, 115.5 (d, J ¼ 21.4 Hz, 2C), 114.6, 108.5 (d,
J ¼ 25.2 Hz), 107.9, 102.1, 99.0, 69.8, 55.8 (2C), 46.1, 36.9, 32.2, 27.2
(3C), 19.3, 13.1. Anal. Calcd. For C34H37F2N3O5: C, 67.42; H, 6.16; N,
6.94. Found: C, 67.40; H, 6.15; N, 6.95. ESI-MS: m/z 606.3 [MþH]þ.
4.1.5.6. N-(1-((4-((6,7-Dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
amino)-3,3-dimethyl-1-oxobutan-2-yl)-4-fluoro-N-(4-fluorophenyl)
benzamide (11f). White solid, yield: 47.4%, m.p.: 201e203 ꢀC. 1H
4.1.5.2. N-(tert-Butyl)-N-(1-((4-((6,7-dimethoxyquinolin-4-yl)oxy)-
3-fluorophenyl)amino)-3,3-dimethyl-1-oxobutan-2-yl)-4-
fluorobenzamide (11b). White solid, yield: 70.6%, m.p.: 90e92 ꢀC.
NMR (400 MHz, CDCl3)
d 9.67 (s, 1H), 8.52 (d, 1H), 7.82 (d,
J ¼ 11.6 Hz, 1H), 7.60 (s, 1H), 7.49 (s, 1H), 7.30 (t, J ¼ 8.0 Hz, 1H), 7.21
1H NMR (400 MHz, CDCl3)
d
11.77 (s, 1H), 8.50 (d, J ¼ 4.8 Hz, 1H),
(m, 5H), 6.94e6.86 (m, 4H), 6.44 (d, J ¼ 3.6 Hz, 1H), 5.16 (s, 1H), 4.07
7.83 (d, J ¼ 11.2 Hz, 1H), 7.61 (m, 3H), 7.47 (s, 1H), 7.35 (d, J ¼ 8.0 Hz,
1H), 7.28e7.22 (m, 1H), 7.14 (t, J ¼ 7.2 Hz, 2H), 6.46 (d, J ¼ 4.4 Hz,
1H), 4.08 (s, 3H), 4.06 (s, 3H), 3.98 (s, 1H), 1.31 (s, 9H), 1.29 (s, 9H).
(s, 3H), 4.06 (s, 3H), 1.16 (s, 9H). 13C NMR (100 MHz, CDCl3)
d 172.5,
168.8, 163.0 (d, J ¼ 250.3 Hz), 161.5 (d, J ¼ 250.2 Hz), 160.2, 154.3 (d,
J ¼ 248.2 Hz), 153.0, 149.6, 148.4, 146.5, 138.2, 137.1 (d, J ¼ 12.4 Hz),
136.6 (d, J ¼ 9.4 Hz), 131.6 (d, J ¼ 3.4 Hz), 130.9 (d, J ¼ 6.1 Hz, 2C),
130.4 (d, J ¼ 8.5 Hz, 2C), 123.7, 116.2, 116.1 (d, J ¼ 25.7 Hz, 2C), 115.5,
115.1 (d, J ¼ 21.8 Hz, 2C), 109.5 (d, J ¼ 22.9 Hz), 107.4, 102.1, 99.4,
60.3, 56.1 (2C),35.5, 28.3 (3C). Anal. Calcd. For C36H32F3N3O5: C,
67.18; H, 5.01; N, 6.53. Found: C, 67.16; H, 5.02; N, 6.55. ESI-MS: m/z
644.2 [MþH]þ.
13C NMR (100 MHz, CDCl3)
d
176.5, 172.2, 164.3 (d, J ¼ 250.9 Hz),
160.3, 154.5 (d, J ¼ 247.8 Hz), 152.9, 149.6, 148.6, 146.6, 137.4 (d,
J ¼ 9.6 Hz), 136.8 (d, J ¼ 12.4 Hz), 136.2 (d, J ¼ 3.2 Hz), 130.3 (2C),
123.7, 116.3 (d, J ¼ 2.9 Hz), 115.5 (2C), 109.5 (d, J ¼ 22.6 Hz), 107.6,
102.2, 99.5, 75.4, 60.7, 56.1 (2C), 37.0, 31.1 (3C), 30.1 (3C). Anal.
Calcd. For C34H37F2N3O5: C, 67.42; H, 6.16; N, 6.94. Found: C, 67.43;
H, 6.14; N, 6.95. ESI-MS: m/z 606.3 [MþH]þ.
4.1.5.7. N-(1-((4-((6,7-dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)
4.1.5.3. N-Cyclohexyl-N-(1-((4-((6,7-dimethoxyquinolin-4-yl)oxy)-3-
fluorophenyl)amino)-3,3-dimethyl-1-oxobutan-2-yl)-4-
amino)-3,3-dimethyl-1-oxobutan-2-yl)-4-fluorobenzamide
(11g).
Pale yellow solid, yield: 28.6%, m.p.: 123e125 ꢀC. 1H NMR

14
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
(400 MHz, CDCl3)
d
11.23 (br s,1H), 8.41 (d, J ¼ 4.0 Hz,1H), 8.09 (br s,
docking analysis was carried out by the Autodock 4.2 package to
explore the binding model for the active site of c-Met with its
ligand. All atoms located within the range of 5.0 Å from any atom of
the cofactor were selected into the active site, and the corre-
sponding amino acid residue was, therefore, involved into the
active site if only one of its atoms was selected. Other parameters
were all set as default in the docking calculations. All calculations
were performed on Silicon Graphics workstation.
1H), 7.73 (d, J ¼ 11.6 Hz, 1H), 7.52 (s, 1H), 7.45 (t, J ¼ 6.0 Hz, 2H), 7.37
(s, 1H),7.23e7.14 (m, 2H), 7.10e7.06 (m, 2H), 6.36 (d, J ¼ 4.0 Hz, 1H),
3.99 (s, 3H), 3.97 (s, 3H), 3.74 (s,1H),1.22 (s, 9H). 13C NMR (100 MHz,
CDCl3)
d
174.8, 171.2, 164.1 (d, J ¼ 250.0 Hz), 160.3, 154.5 (d,
J ¼ 247.8 Hz), 153.0, 149.6, 148.7, 146.7, 137.2 (d, J ¼ 9.5 Hz), 136.9 (d,
J ¼ 12.5 Hz), 132.7, 129.0 (d, J ¼ 8.5 Hz, 2C), 123.8, 116.3 (d,
J ¼ 3.0 Hz), 116.1 (d, J ¼ 21.8 Hz, 2C), 115.6, 109.6 (d, J ¼ 22.6 Hz),
107.7, 102.3, 99.5, 70.6, 56.2 (2C), 31.9, 29.8 (3C). Anal. Calcd. For-
C
30H29F2N3O5: C, 65.56; H, 5.32; N, 7.65. Found: C, 65.57; H, 5.34; N,
Author contributions
7.65. ESI-MS: m/z 550.3 [MþH]þ.
X. Nan, S.B. Fang, H.J. Li and Q.Y. Li conducted the research,
analyzed the data, and wrote the manuscript. H.J. Li, S.B. Fang and
Y.C. Wu designed the study, analyzed the data, wrote the manu-
script and commented on the manuscript.
4.2. Biology
4.2.1. Cytotoxicity against tumor cells assay
The cancer cells were cultured in minimum essential medium
(MEM) supplemented with 10% fetal bovine serum (FBS) [70e72].
Approximately 4 ꢁ 103 cells per well, suspended in MEM medium,
were plated onto each well of a 96-well plate and incubated in 5%
CO2 at 37 ꢀC for 24 h. The test compounds were added to the culture
medium at the indicated final concentrations and the cell cultures
were continued for 72 h. Fresh MTT was added to each well at a
Declaration of competing interest
The authors declare no competing financial interest or personal
relationships that could have appeared to influence the work re-
ported in this paper.
final concentration of 5
4 h. The formazan crystals were dissolved in 100
m
g/mL and incubated with cells at 37 ꢀC for
L DMSO per each
Acknowledgements
m
well, and the absorbency at 492 nm (for the absorbance of MTT
formazan) and 630 nm (for the reference wavelength) was
measured with the ELISA reader. All compounds were tested three
times in each of the cell lines. The results expressed as IC50
(inhibitory concentration of 50%) were the average of three de-
terminations calculated by using the Bacus Laboratories Incorpo-
rated Slide Scanner (Bliss) software.
This work was supported by the Key Research and Development
Program of Shandong Province (2019GSF108089), the Natural Sci-
ence Foundation of Shandong Province (ZR2019MB009), the Na-
tional Natural Science Foundation of China (21672046, 21372054),
and the Found from the Huancui District of Weihai City.
Appendix A. Supplementary data
4.2.2. Tyrosine kinases assay
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.ejmech.2020.112241.
The tyrosine kinases activities were evaluated using homoge-
neous time-resolved fluorescence (HTRF) assays, as previously re-
ported protocol [73,74]. Briefly, 20 mg/mL poly (Glu, Tyr) 4:1
References
(Sigma) was preloaded as a substrate in 384-well plates. Then 50 mL
of 10 mM ATP (Invitrogen) solution diluted in kinase reaction buffer
(50 mM HEPES, pH 7.0, 1 M DTT, 1 M MgCl2, 1 M MnCl2, and 0.1%
NaN3) was added to each well. Various concentrations of com-
[1] D.P. Bottaro, J.S. Rubin, D.L. Faletto, A.M.-L. Chan, T.E. Kmiecik, G.F. Vande
Woude, S.A. Aaronson, Identification of the hepatocyte growth factor receptor
as the c-met proto-oncogene product, Science 251 (1991) 802e804.
[2] M. Dean, M. Park, M.M. Le Beau, T.S. Robins, M.O. Diaz, J.D. Rowley, D.G. Blair,
G.F. Vande Woude, The human met oncogene is related to the tyrosine kinase
oncogenes, Nature 318 (1985) 385e388.
[3] L. Trusolino, P.M. Comoglio, Scatter-factor and semaphorin receptors: cell
signaling for invasive growth, Nat. Rev. Canc. 2 (2002) 289e300.
[4] C. Birchmeier, W. Birchmeier, E. Gherardi, G.F. Vande Woude, Met, metastasis,
motility and more, Nat. Rev. Mol. Cell Biol. 4 (2003) 915e925.
pounds diluted in 10
control. The kinase reaction was initiated by the addition of purified
tyrosine kinase proteins diluted in 39 L of kinase reaction buffer
solution. The incubation time for the reactions was 30 min at 25 ꢀC,
and the reactions were stopped by the addition of 5 L of
Streptavidin-XL665 and 5 L Tk Antibody Cryptate working solu-
mL of 1% DMSO (v/v) were used as the negative
m
m
[5] W. Gao, J.K. Han, Overexpression of ING5 inhibits HGF-induced proliferation,
invasion and EMT in thyroid cancer cells via regulation of the c-Met/PI3K/Akt
signaling pathway, Biomed. Pharmacother. 98 (2018) 265e270.
m
tion to all of wells. The plates were read using Envision (Perki-
nElmer) at 320 nm and 615 nm. The inhibition rate (%) was
ꢀ
[6] J.A. Aguirre Ghiso, D.F. Alonso, E.F. Farías, D.E. Gomez, E.B. de Kier Joffe,
calculated using the following equation:
%
inhibition
Deregulation of the signaling pathways controlling urokinase production, Eur.
J. Biochem. 263 (1999) 295e304.
100 ¼ [(Activity of enzyme with tested compounds - Min)/(Max
-Min)] ꢁ 100 (Max: the observed enzyme activity measured in the
presence of enzyme, substrates, and cofactors; Min: the observed
enzyme activity in the presence of substrates, cofactors and in the
absence of enzyme). IC50 values were calculated from the inhibition
curves.
[7] S. Rong, S. Segal, M. Anver, J.H. Resau, G.F. Vande Woude, Invasiveness and
metastasis of NIH 3T3 cells induced by Met-hepatocyte growth factor/scatter
factor autocrine stimulation, Proc. Natl. Acad. Sci. U.S.A. 91 (1994) 4731e4735.
[8] M. Jeffers, S. Rong, M. Anver, G.F. Vande Woude, Autocrine hepatocyte growth
factor/scatter factor-Met signaling induces transformation and the invasive/
metastastic phenotype in C127 cells, Oncogene 13 (1996) 853e856.
[9] H. Takayama, W.J. LaRochelle, R. Sharp, T. Otsuka, P. Kriebel, M. Anver,
S.A. Aaronson, G. Merlino, Diverse tumorigenesis associated with aberrant
development in mice overexpressing hepatocyte growth factor/scatter factor,
Proc. Natl. Acad. Sci. U.S.A. 94 (1997) 701e706.
4.3. Docking studies
[10] T. Otsuka, H. Takayama, R. Sharp, G. Celli, W.J. LaRochelle, D.P. Bottaro,
N. Ellmore, W. Vieira, J.W. Owens, M. Anver, G. Merlino, c-Met autocrine
activation induces development of malignant melanoma and acquisition of
the metastatic phenotype, Canc. Res. 58 (1998) 5157e5167.
[11] S. Baldaccia, Z. Kherrouchec, V. Cockenpotb, L. Stovena, M.C. Copinb,
E. Werkmeisterf, N. Marchandc, M. Kyheng, D. Tulasnec, A.B. Cortot, MET
amplification increases the metastatic spread of EGFR-mutated NSCLC, Lung
Canc. 125 (2018) 57e67.
For docking purposes, the three-dimensional structure of the c-
Met (PDB code: 3LQ8) were obtained from RCSB Protein Data Bank
[75]. Hydrogen atoms were added to the structure allowing for
appropriate ionization at physiological pH. The protonated state of
several important residues, such as CYS919, and ASP1046 were
adjusted by using SYBYL 6.9.1 (Tripos, St. Louis, USA) in favor of
forming reasonable hydrogen bond with the ligand. Molecular
[12] G. Tsakonas, J. Botling, P. Micke, C. Rivardc, L. LaFleur, J. Mattsson, T. Boyle,
F.R. Hirsch, S. Ekman, c-MET as a biomarker in patients with surgically

X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
15
resected non-small cell lung cancer, Lung Canc. 133 (2019) 69e74.
[13] Y. Toiyama, C. Miki, Y. Inoue, Y. Okugawa, K. Tanaka, M. Kusunoki, Serum
hepatocyte growth factor as a prognostic marker for stage II or III colorectal
cancer patients, Int. J. Canc. 125 (2009) 1657e1662.
H. Iwata, K. Nakamura, S. Yamasaki, H. Miki, A. Hori, S. Imamura, Structure-
based design, synthesis, and evaluation of imidazo[1,2-b]pyridazine and
imidazo[1,2-a]pyridine derivatives as novel dual c-Met and VEGFR2 kinase
inhibitors, Bioorg. Med. Chem. 21 (2013) 7686e7698.
[14] Y.D. Liao, R. Grobholz, U. Abel, L. Trojan, M.S. Michel, P. Angel, D. Mayer, In-
crease of AKT/PKB expression correlates with gleason pattern in human
prostate cancer, Int. J. Canc. 107 (2003) 676e680.
[15] J.G. Christensen, J. Burrows, R. Salgia, c-Met as a target for human cancer and
characterization of inhibitors for therapeutic intervention, Canc. Lett. 225
(2005) 1e26.
[16] F. Cappuzzo, A. Marchetti, M. Skokan, E. Rossi, S. Gajapathy, L. Felicioni, M. del
Grammstro, M.G. Sciarrotta, F. Buttitta, M. Incarbone, L. Toschi, G. Finocchiaro,
A. Destro, L. Terracciano, M. Roncalli, M. Alloisio, A. Santoro, M. Varella-Garcia,
Increased MET gene copy number negatively affects survival of surgically
resected non-small-cell lung cancer patients, J. Clin. Oncol. 27 (2009)
1667e1674.
[17] J.R. Graff, B.W. Konicek, A.M. McNulty, Z.J. Wang, K. Houck, S. Allen, J.D. Paul,
A. Hbaiu, R.G. Goode, G.E. Sandusky, R.L. Vessella, B.L. Neubauer, Increased
AKT activity contributes to prostate cancer progression by dramatically
accelerating prostate tumor growth and diminishing p27Kip1 expression,
J. Biol. Chem. 275 (2000) 24500e24505.
[33] B.H. Qi, Y. Yang, G.W. Gong, H. He, X.P. Yue, X. Xu, Y. Hu, J.M. Li, T. Chen,
X.B. Wan, A.M. Zhang, G.B. Zhou, Discovery of N1-(4-((7-(3-(4-ethylpiperazin-
1-yl)propoxy)-6-methoxyquinolin-4-yl)oxy)-3,5-difluorophenyl)-N3-(2-(2,6-
difluorophenyl)-4-oxothiazolidin-3-yl)urea as a multi-tyrosine kinase inhibi-
tor for drug-sensitive and drug-resistant cancers treatment, Eur. J. Med. Chem.
163 (2019) 10e27.
ꢁ
[34] J.J. Cui, M. Tran-Dube, H. Shen, M. Nambu, P.P. Kung, M. Pairish, L. Jia, J. Meng,
L. Funk, I. Botrous, M. McTigue, N. Grodsky, K. Ryan, E. Padrique, G. Alton,
S. Timofeevski, S. Yamazaki, Q.H. Li, H. Zou, J. Christensen, B. Mroczkowski,
S. Bender, R.S. Kania, M.P. Edwards, Structure based drug design of crizotinib
(PF-02341066),
a potent and selective dual inhibitor of mesenchymal-
epithelial transition factor (c-MET) kinase and anaplastic lymphoma kinase
(ALK), J. Med. Chem. 54 (2011) 6342e6363.
[35] M.M. Liu, Y.L. Hou, W.L. Yin, S.G. Zhou, P. Qian, Z. Guo, L.Y. Xu, Y.F. Zhao,
Discovery of a novel 6,7-disubstituted-4-(2-fluorophenoxy)quinolines bearing
1,2,3-triazole-4-carboxamide moiety as potent c-Met kinase inhibitors, Eur. J.
Med. Chem. 119 (2016) 96e108.
[18] T. Burgess, A. Coxon, S. Meyer, J. Sun, K. Rex, T. Tsuruda, Q. Chen, S.Y. Ho, L. Li,
S. Kaufman, K. McDorman, R.C. Cattley, J. Sun, G. Elliott, K. Zhang, X. Feng,
X.C. Jia, L. Green, R. Radinsky, R. Kendall, Fully human monoclonal antibodies
to hepatocyte growth factor with therapeutic potential against hepatocyte
growth factor/c-Metedependent human tumors, Canc. Res. 66 (2006)
1721e1729.
[19] H.K. Jin, R.H. Yang, Z. Zheng, M. Romero, J. Ross, H. Bou-Reslan, R.A.D. Carano,
I. Kasman, E. Mai, J. Young, J.P. Zha, Z.M. Zhang, S. Ross, R. Schwall, G. Colbern,
M. Merchant, MetMAb, the one-armed 5D5 anti-c-Met antibody, inhibits
orthotopic pancreatic tumor growth and improves survival, Canc. Res. 68
(2008) 4360e4368.
[20] E.H. van der Horst, L. Chinn, M. Wang, T. Velilla, H. Tran, Y. Madrona, A. Lam,
M. Ji, T.C. Hoey, A.K. Sato, Discovery of fully human anti-MET monoclonal
antibodies with antitumor activity against colon cancer tumor models in vivo,
Neoplasia 11 (2009) 355e364.
[21] I. Dussault, S.F. Bellon, From concept to reality: the long road to c-Met and
RON receptor tyrosine kinase inhibitors for the treatment of cancer, Anti Canc.
Agents Med. Chem. 9 (2009) 221e229.
[22] S.F. Bellon, P. Kaplan-Lefko, Y.J. Yang, Y.H. Zhang, J. Moriguchi, K. Rex,
C.W. Johnson, P.E. Rose, A.M. Long, A.B. O’Connor, Y. Gu, A. Coxon, T. Kim,
A. Tasker, T.L. Burgess, I. Dussault, c-Met inhibitors with novel binding mode
show activity against several hereditary papillary renal cell carcinoma-related
mutations, J. Biol. Chem. 283 (2008) 2675e2683.
[23] X. Zhai, G.L. Bao, L.M. Wang, M.K. Cheng, M. Zhao, S.J. Zhao, H.Y. Zhou, P. Gong,
Design, synthesis and biological evaluation of novel 4-phenoxy-6,7-
disubstituted quinolines possessing (thio) semicarbazones as c-Met kinase
inhibitors, Bioorg. Med. Chem. 24 (2016) 1331e1345.
[24] Y.F. Yang, Y. Zhang, L.Y. Yang, L.L. Zhao, L.H. Si, H.B. Zhang, Q.S. Liu, J.P. Zhou,
Discovery of imidazopyridine derivatives as novel c-Met kinase inhibitors:
synthesis, SAR study, and biological activity, Bioorg. Chem. 70 (2017)
126e132.
[25] M.H. El-Wakil, H.M. Ashour, M.N. Saudi, A.M. Hassan, I.M. Labouta, Design,
synthesis and molecular modeling studies of new series of antitumor 1,2,4-
triazines with potential c-Met kinase inhibitory activity, Bioorg. Chem. 76
(2018) 154e165.
[26] F. Zhao, L.D. Zhang, Y. Hao, N. Chen, R. Bai, Y.J. Wang, C.C. Zhang, G.S. Li,
L.J. Hao, C. Shi, J. Zhang, Y. Mao, Y. Fan, G.X. Xia, J.X. Yu, Y.J. Liu, Identification of
3-substituted-6-(1-(1H-[1,2,3]triazolo[4,5-b]pyrazin-1-yl)ethyl)quinoline de-
rivatives as highly potent and selective mesenchymal-epithelial transition
factor (c-Met) inhibitors via metabolite profiling-based structural optimiza-
tion, Eur. J. Med. Chem. 134 (2017) 147e158.
[27] H.L. Yuan, Q.F. Liu, L. Zhang, S.H. Hu, T.T. Chen, H.F. Li, Y.D. Chen, Y.C. Xu, T. Lu,
Discovery, optimization and biological evaluation for novel c-Met kinase in-
hibitors, Eur. J. Med. Chem. 143 (2018) 491e502.
[28] L.S. Zhuo, H.C. Xu, M.S. Wang, X.E. Zhao, Z.H. Ming, X.L. Zhu, W. Huang,
G.F. Yang, 2,7-naphthyridinone-based MET kinase inhibitors: a promising
novel scaffold for antitumor drug development, Eur. J. Med. Chem. 178 (2019)
705e714.
[29] A.A. Boezio, K.W. Copeland, K. Rex, B.K. Albrecht, D. Bauer, S.F. Bellon,
C. Boezio, M.A. Broome, D. Choquette, A. Coxon, I. Dussault, S. Hirai, R. Lewis,
M.J. Lin, J. Lohman, J.Z. Liu, E.A. Peterson, M. Potashman, R. Shimanovich,
Y. Teffera, D.A. Whittington, K.R. Vaida, J. Harmange, Discovery of (R)-6-(1-(8-
fluoro-6-(1-methyl-1H-pyrazol-4-yl)-[1,2,4]triazolo[4,3-a]pyridin-3-yl)
[36] T.L. Underiner, T. Herbertz, S.J. Miknyoczki, Discovery of small molecule c-Met
inhibitors: evolution and profiles of clinical candidates, Anti Canc. Agents
Med. Chem. 10 (2010) 7e27.
[37] J. Liu, M.H. Nie, Y.J. Wang, J.X. Hu, F. Zhang, Y.L. Gao, Y.J. Liu, P. Gong, Design,
synthesis and structure-activity relationships of novel 4-phenoxyquinoline
derivatives containing 1,2,4-triazolone moiety as c-Met kinase inhibitors,
Eur. J. Med. Chem. 123 (2016) 431e446.
[38] B.K. Albrecht, J.C. Harmange, D. Bauer, L. Berry, C. Bode, A.A. Boezio, A. Chen,
D. Choquette, I. Dussault, C. Fridrich, S. Hirai, D. Hoffman, J.F. Larrow,
P. Kaplan-Lefko, J. Lin, J. Lohman, A.M. Long, J. Moriguchi, A. O’Connor,
M.H. Potashman, M. Reese, K. Rex, A. Siegmund, K. Shah, R. Shimanovich,
S.K. Springer, Y. Teffera, Y.J. Yang, Y.H. Zhang, S.F. Bellon, Discovery and
optimization of triazolopyridazines as potent and selective inhibitors of the c-
Met kinase, J. Med. Chem. 51 (2008) 2879e2882.
[39] N.D. D’Angelo, S.F. Bellon, S.K. Booker, Y. Chen, A. Coxon, C. Dominguez,
I. Fellows, D. Hoffman, R. Hungate, P. Kaplan-Lefko, M.R. Lee, C. Li, L.B. Liu,
E. Rainbeau, P.J. Reider, K. Rex, A. Siegmund, Y.X. Sun, A.S. Tasker, N. Xi,
S.M. Xu, Y.J. Yang, Y.H. Zhang, T.L. Burgess, I. Dussault, T.S. Kim, Design, syn-
thesis, and biological evaluation of potent c-Met inhibitors, J. Med. Chem. 51
(2008) 5766e5779.
[40] S.J. Zhao, Y. Zhang, H.Y. Zhou, S.C. Xi, B. Zou, G.L. Bao, L.M. Wang, J. Wang,
T.F. Zeng, P. Gong, X. Zhai, Synthesis and biological evaluation of 4-(2-
fluorophenoxy)-3,30-bipyridine derivatives as potential c-met inhibitors,
Eur. J. Med. Chem. 120 (2016) 37e50.
[41] L.X. Wang, S. Xu, X.B. Liu, X.Y. Chen, H.H. Xiong, S.S. Hou, W.S. Zou, Q.D. Tang,
P.W. Zheng, W.F. Zhu, Discovery of thinopyrimidine-triazole conjugates as c-
Met targeting and apoptosis inducing agents, Bioorg. Chem. 77 (2018)
370e380.
[42] X.Q. Wang, N. Jiang, S.J. Zhao, S.C. Xi, J. Wang, T.F. Jing, W.Y. Zhang, M. Guo,
P. Gong, X. Zhai, Design, synthesis and biological evaluation of novel 4-(2-
fluorophenoxy)quinoline derivatives as selective c-Met inhibitors, Bioorg.
Med. Chem. 25 (2017) 886e896.
[43] S. Li, Y.F. Zhao, K.W. Wang, Y.L. Gao, J.M. Han, B.B. Cui, P. Gong, Discovery of
novel 4-(2-fluorophenoxy)quinoline derivatives bearing 4-oxo-1,4-
dihydrocinnoline-3-carboxamide moiety as c-Met kinase inhibitors, Bioorg.
Med. Chem. 21 (2013) 2843e2855.
[44] B.H. Qi, Y. Yang, H. He, X.P. Yue, Y.T. Zhou, X. Zhou, Y.Y. Chen, M. Liu,
A.M. Zhang, F.C. Wei, Identification of novel N1-(2-aryl-1,3-thiazolidin-4-one)-
N3-aryl ureas showing potent multi-tyrosine kinase inhibitory activities, Eur. J.
Med. Chem. 146 (2018) 368e380.
[45] Q.D. Tang, Y.L. Duan, H.H. Xiong, T. Chen, Z. Xiao, L.X. Wang, Y.Y. Xiao,
S.M. Huang, Y.H. Xiong, W.F. Zhu, P. Gong, P.W. Zheng, Synthesis and anti-
proliferative activity of 6,7-disubstituted-4-phenoxyquinoline derivatives
bearing the 1,8-naphthyridin-2-one moiety, Eur. J. Med. Chem. 158 (2018)
201e213.
[46] W.K. Liao, G. Hu, Z. Guo, D.Y. Sun, L.X. Zhang, Y.X. Bu, Y.X. Li, Y.J. Liu, P. Gong,
Design and biological evaluation of novel 4-(2-fluorophenoxy)quinoline de-
rivatives bearing an imidazolone moiety as c-Met kinase inhibitors, Bioorg.
Med. Chem. 23 (2015) 4410e4422.
[47] J. Liu, D. Yang, X.X. Yang, M.H. Nie, G.D. Wu, Z.C. Wang, W. Li, Y.J. Liu, P. Gong,
Design, synthesis and biological evaluation of novel 4-phenoxyquinoline de-
rivatives containing 3-oxo-3,4-dihydroquinoxaline moiety as c-Met kinase
inhibitors, Bioorg. Med. Chem. 25 (2017) 4475e4486.
ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6H)-one (AMG 337),
a
[48] R.W. Armstrong, A.P. Combs, P.A. Tempest, S.D. Brown, T.A. Keating, Multiple-
component condensation strategies for combinatorial library synthesis, Acc.
Chem. Res. 29 (1996) 123e131.
Potent and Selective Inhibitor of MET with high unbound target coverage and
robust in vivo antitumor activity, J. Med. Chem. 59 (2016) 2328e2342.
[30] I. Dussault, S.F. Bellon, c-Met inhibitors with different binding modes: two is
better than one, Cell Cycle 7 (2008) 1157e1160.
[31] S. Berthou, D.M. Aebersold, L.S. Schmidt, D. Stroka, C. Heigl, B. Streit, D. Stalder,
G. Gruber, C.X. Liang, A.R. Howlett, D. Candinas, R.H. Greiner, K.E. Lipson,
Y. Zimmer, The Met kinase inhibitor SU11274 exhibits a selective inhibition
pattern toward different receptor mutated variants, Oncogene 23 (2004)
5387e5393.
€
[49] A. Domling, Recent developments in isocyanide based multicomponent re-
actions in applied chemistry, Chem. Rev. 106 (2006) 17e89.
[50] K.C. Nicolaou, D.J. Edmonds, P.G. Bulger, Cascade reactions in total synthesis,
Angew. Chem. Int. Ed. 45 (2006) 7134e7186.
[51] D. Enders, C. Grondal, M.R.M. Hüttl, Asymmetric organocatalytic domino re-
actions, Angew. Chem. Int. Ed. 46 (2007) 1570e1581.
ꢁ
[52] B.B. Toure, D.G. Hall, Natural product synthesis using multicomponent reac-
[32] S. Matsumoto, N. Miyamoto, T. Hirayama, H. Oki, K. Okada, M. Tawada,
tion strategies, Chem. Rev. 109 (2009) 4439e4486.

16
X. Nan et al. / European Journal of Medicinal Chemistry 193 (2020) 112241
€
ꢁ
ꢁ
[53] A. Domling, W. Wang, K. Wang, Chemistry and biology of multicomponent
reactions, Chem. Rev. 112 (2012) 3083e3135.
[67] V. Estevez, M. Villacampa, J.C. Menendez, Recent advances in the synthesis of
pyrroles by multicomponent reactions, Chem. Soc. Rev. 43 (2014) 4633e4657.
[68] L. Kou, M.J. Wang, L.T. Yan, X.B. Zhao, X. Nan, L. Yang, Y.Q. Liu, S.L. Morris-
Natschke, K.H. Lee, Toward synthesis of third-generation spin-labeled podo-
phyllotoxin derivatives using isocyanide multicomponent reactions, Eur. J.
Med. Chem. 75 (2014) 282e288.
[54] I. Akritopoulou-Zanze, Isocyanide-based multicomponent reactions in drug
discovery, Curr. Opin. Chem. Biol. 12 (2008) 324e331.
[55] L. Weber, The application of multi-component reactions in drug discovery,
Curr. Med. Chem. 9 (2002) 2085e2093.
[56] C. Hulme, V. Gore, Multi-component reactions: emerging chemistry in drug
discovery ‘from xylocain to crixivan’, Curr. Med. Chem. 10 (2003) 51e80.
[57] A. Domling, I. Ugi, Multicomponent reactions with isocyanides, Angew. Chem.
[69] X. Nan, Y.F. Jiang, H.J. Li, J.H. Wang, Y.C. Wu, Design, synthesis and evaluation
of sulfonylurea-containing 4-phenoxyquinolines as highly selective c-Met
kinase inhibitors, Bioorg. Med. Chem. 27 (2019) 2801e2812.
€
Int. Ed. 39 (2000) 3168e3210.
[58] A. Domling, Recent advances in isocyanide-based multicomponent chemistry,
[70] Z.F. Zhang, J.C. Lee, L.P. Lin, V. Olivas, V. Au, T. LaFramboise, M. Abdel-Rahman,
X.Q. Wang, A.D. Levine, J.K. Rho, Y.J. Choi, C.M. Choi, S.W. Kim, S.J. Jang,
Y.S. Park, W.S. Kim, D.H. Lee, J.S. Lee, V.A. Miller, M. Arcila, M. Ladanyi,
P. Moonsamy, C. Sawyers, T.J. Boggon, P.C. Ma, C. Costa, M. Taron, R. Rosell,
B. Halmos, T.G. Bivona, Activation of the AXL kinase causes resistance to EGFR
targeted therapy in lung cancer, Nat. Genet. 44 (2012) 852e860.
[71] R. Tiedt, E. Degenkolbe, P. Furet, B.A. Appleton, S. Wagner, J. Schoepfer,
E. Buck, D.A. Ruddy, J.E. Monahan, M.D. Jones, J. Blank, D. Haasen, P. Drueckes,
M. Wartmann, C. McCarthy, W.R. Sellers, F. Hofmann, A drug resistance screen
using a selective MET inhibitor reveals a spectrum of mutations that partially
overlap with activating mutations found in cancer patients, Canc. Res. 71
(2011) 5255e5264.
[72] T. Nakagawa, O. Tohyama, A. Yamaguchi, T. Matsushima, K. Takahashi,
S. Funasaka, S. Shirotori, M. Asada, H. Obaishi, E7050: a dual c-Met and
VEGFR-2 tyrosine kinase inhibitor promotes tumor regression and prolongs
survival in mouse xenograft models, Canc. Sci. 101 (2010) 210e215.
[73] L.B. Liu, A. Siegmund, N. Xi, P. Kaplan-Lefko, K. Rex, A. Chen, J. Lin, J. Moriguchi,
L. Berry, L.Y. Huang, Y. Teffera, Y.J. Yang, Y.H. Zhang, S.F. Bellon, M. Lee,
R. Shimanovich, A. Bak, C. Dominguez, M.H. Norman, J.C. Harmange,
I. Dussault, T.S. Kim, Discovery of a potent, selective, and orally bioavailable c-
Met inhibitor: 1-(2-Hydroxy-2-methylpropyl)-N-(5-(7-methoxyquinolin-4-
yloxy)pyridin-2-yl)-5-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-
carboxamide (AMG 458), J. Med. Chem. 51 (2008) 3688e3691.
€
Curr. Opin. Chem. Biol. 6 (2002) 306e313.
[59] V. Nair, C. Rajesh, A.U. Vinod, S. Bindu, A.R. Sreekanth, J.S. Mathen,
L. Balagopal, Strategies for heterocyclic construction via novel multicompo-
nent reactions based on isocyanides and nucleophilic carbenes, Acc. Chem.
Res. 36 (2003) 899e907.
[60] J. Zhang, S.X. Lin, D.J. Cheng, X.Y. Liu, B. Tan, Phosphoric acid-catalyzed
asymmetric classic passerini reaction, J. Am. Chem. Soc. 137 (2015)
14039e14042.
[61] X.H. Zeng, H.M. Wang, M.W. Ding, Unexpected synthesis of 5,6-
dihydropyridin-2(1H)-ones by a domino Ugi/Aldol/Hydrolysis reaction start-
ing from Baylis-Hillman phosphonium salts, Org. Lett. 17 (2015) 2234e2237.
€
[62] I. Ugi, B. Werner, A. Domling, The chemistry of isocyanides, their multicom-
ponent reactions and their libraries, Molecules 8 (2003) 53e66.
[63] M. Main, J.S. Snaith, M.M. Meloni, M. Jauregui, D. Sykes, S. Faulkner,
A.M. Kenwright, Using the Ugi multicomponent condensation reaction to
prepare families of chromophore appended azamacrocycles and their com-
plexes, Chem. Commun. (2008) 5212e5214.
[64] S.G. Zhou, H.M. Liao, C. He, Y.N. Dou, M.Y. Jiang, L.X. Ren, Y.F. Zhao, P. Gong,
Design, synthesis and structureeactivity relationships of novel 4-
phenoxyquinoline derivatives containing pyridazinone moiety as potential
antitumor agents, Eur. J. Med. Chem. 83 (2014) 581e593.
[65] L.M. Miller, S.C. Mayer, D.M. Berger, D.H. Boschelli, F. Boschelli, L. Di, X.M. Du,
M. Dutia, M.B. Floyd, M. Johnson, C. Hess Kenny, G. Krishnamurthy, F. Moy,
S. Petusky, D. Tkach, N. Torres, B.Q. Wu, W.X. Xu, Lead identification to
generate 3-cyanoquinoline inhibitors of insulin-like growth factor receptor
(IGF-1R) for potential use in cancer treatment, Bioorg. Med. Chem. Lett. 19
(2009) 62e66.
[66] L.B. Liu, M.H. Norman, M. Lee, N. Xi, A. Siegmund, A.A. Boezio, S. Booker,
D. Choquette, N.D. D’Angelo, J. Germain, K. Yang, Y.J. Yang, Y.H. Zhang,
S.F. Bellon, D.A. Whittington, J.C. Harmange, C. Dominguez, T.S. Kim,
I. Dussault, Structure-based design of novel class II c-Met inhibitors: 2. SAR
and kinase selectivity profiles of the pyrazolone series, J. Med. Chem. 55
(2012) 1868e1897.
[74] M.L. Peach, N. Tan, S.J. Choyke, A. Giubellino, G. Athauda, T.R. Burke Jr.,
M.C. Nicklaus, D.P. Bottaro, Directed discovery of agents targeting the Met
tyrosine kinase domain by virtual screening, J. Med. Chem. 52 (2009)
943e951.
[75] K.S. Kim, L.P. Zhang, R. Schmidt, Z.W. Cai, D. Wei, D.K. Williams, L.J. Lombardo,
G.L. Trainor, D. Xie, Y.Q. Zhang, Y. An, J.S. Sack, J.S. Tokarski, C. Darienzo,
A. Kamath, P. Marathe, Y.P. Zhang, J. Lippy, R. Jeyaseelan Sr., B. Wautlet,
B. Henley, J. Gullo-Brown, V. Manne, J.T. Hunt, J. Fargnoli, R.M. Borzilleri,
Discovery of pyrrolopyridine-pyridone based inhibitors of Met kinase: syn-
thesis, X-ray crystallographic analysis, and biological activities, J. Med. Chem.
51 (2008) 5330e5341.