Discovery of 8-amino-substituted 2-phenyl-2,7-naphthyridinone derivatives as new c-Kit/VEGFR-2 kinase inhibitors

Article abstract of DOI:10.3390/molecules24244461

The 2,7-naphthyridone scaffold has been proposed as a novel lead structure ofMETinhibitors by our group. To broaden the application of this new scaffold, a series of 8-amino-substituted 2-phenyl-2,7-naphthyridin-1(2H)-one derivatives were designed and synthesized. Preliminary biological screening resulted in the discovery of a new lead of c-Kit and VEGFR-2 kinase inhibitors. Compound 9k exhibited excellent c-Kit inhibitory activity, with an IC₅₀ value of 8.5 nM, i.e., it is 38.8-fold more potent than compound 3 (IC₅₀ of 329.6 nM). Moreover, the compounds 10l and 10r exhibited good VEGFR-2 inhibitory activity, with IC₅₀ values of 56.5 and 31.7 nM, respectively, i.e., they are 5.0-8.8-fold more potent than compound 3 (IC₅₀ of 279.9 nM). Molecular docking experiments provided further insight into the binding interactions of the new lead compounds with c-Kit and VEGFR-2 kinase. In this study, an 8-amino-substituted 2-phenyl-2,7-naphthyridin-1(2H)-one scaffold was identified as the new lead structure of c-Kit and VEGFR-2 kinase inhibitors.

Full text of DOI:10.3390/molecules24244461

molecules
Article
Discovery of 8-Amino-Substituted 2-Phenyl-2,7-
Naphthyridinone Derivatives as New c-Kit/VEGFR-2
Kinase Inhibitors
Haiyan Sun * , Linsheng Zhuo , Huan Dong , Wei Huang * and Nengfang She 2,*
1
, ,†
2,†
2
2,
1
Nanjing Polytechnic Institute, Nanjing 210048, China
Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China
2
Normal University, Wuhan 430079, China; zhuolinsheng199010@126.com (L.Z.); d824002958@163.com (H.D.)
*
Correspondence: jinqiu1982@126.com (H.S.); weihuangwuhan@126.com (W.H.);
nfshe@mail.ccnu.edu.cn (N.S.)
†
These authors contributed equally to this paper.
ꢀ
ꢁꢂꢀꢃꢄꢅꢆꢇ
Academic Editor: Giuseppe Manfroni
Received: 12 November 2019; Accepted: 3 December 2019; Published: 5 December 2019
ꢀ
ꢁꢂꢃꢄꢅꢆ
Abstract: The 2,7-naphthyridone scaffold has been proposed as a novel lead structure of MET inhibitors
by our group. To broaden the application of this new scaffold, a series of 8-amino-substituted
2-phenyl-2,7-naphthyridin-1(2H)-one derivatives were designed and synthesized. Preliminary
biological screening resulted in the discovery of a new lead of c-Kit and VEGFR-2 kinase inhibitors.
Compound 9k exhibited excellent c-Kit inhibitory activity, with an IC50 value of 8.5 nM, i.e., it is
3
8.8-fold more potent than compound
exhibited good VEGFR-2 inhibitory activity, with IC50 values of 56.5 and 31.7 nM, respectively, i.e.,
they are 5.0–8.8-fold more potent than compound (IC50 of 279.9 nM). Molecular docking experiments
3 (IC50 of 329.6 nM). Moreover, the compounds 10l and 10r
3
provided further insight into the binding interactions of the new lead compounds with c-Kit and
VEGFR-2 kinase. In this study, an 8-amino-substituted 2-phenyl-2,7-naphthyridin-1(2H)-one scaffold
was identified as the new lead structure of c-Kit and VEGFR-2 kinase inhibitors.
Keywords: 2,7-naphthyridone; kinase inhibitor; c-Kit; VEGFR-2
1
. Introduction
N-Heterocyclic scaffolds are ubiquitous building blocks that are used for pharmaceuticals and
agrochemicals and in materials science. Novel ring structures may exhibit unique biological or
physical properties [ ]. Naphthyridines, which act as bioisosteres of quinolone, universally exist in
nature and form an important class of nitrogen-containing heterocyclic compounds [ ]. They possess
a conjugated -system and coplanar stiffness, and are therefore a highly valued building block.
1
2
π
Since 1893, a number of naphthyridine derivatives have been synthesized and explored for their
biological activities in the search for novel drugs. A broad spectrum of biological activities has
been associated with the functional derivatives of naphthyridines [
antibacterial agent, is the most successful example of a naphthyridine-based drug [
many naphthyridine derivatives have been reported to inhibit protein kinase activity (e.g., PI3K
CK2 [ ], Akt1/2 [ ], Tpl2 [ 10], and MET [11 13]) for the treatment of many types of human diseases,
including inflammation and cancer [14–18].
3
]. Gemifloxacin (
]. In recent years,
],
1, Figure 1), an
4,5
δ [6
7
8
9,
–
Among the six isomeric sub-classes of naphthyridines, 2,7-naphthyridine derivatives have received
increasing attention. A typical pharmaceutically and biologically active derivative is lophocladine
A (2, Figure 1) [19–22]. In addition, 2,7-naphthyridine derivatives are widely used as inhibitors of
Pdk-1 [23], lumazine synthase [24], PDE-5 [25], TNFα [26], SYK [27], MET [12,13], and other targets.
Molecules 2019, 24, 4461; doi:10.3390/molecules24244461
www.mdpi.com/journal/molecules

Molecules 2019, 24, 4461
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However, the functionalization of 2,7-naphthyridine was found to be especially difficult and only a
few methods are available [28], so its application in drug discovery is greatly limited.
Figure 1. Examples of biologically active compounds containing a naphthyridine scaffold.
In our previous work, a novel 2,7-naphthyridone scaffold was designed to conformationally
restrain the key pharmacophoric groups of class II MET inhibitors, resulting in the discovery of the
potent preclinical candidate compound
3, which targets MET kinase with a favorable drug-likeness [11].
To further expand the application of the 2,7-naphthyridone scaffold, a series of 8-amino-substituted
2
2
-phenyl-2,7-naphthyridin-1(2H)-one derivatives were designed (Figure 2). A small library of
,7-naphthyridones with structural diversity in its 8-amino groups, substituted 2-phenyl groups,
and 3-substituents was constructed to discover new kinase inhibitors.
Figure 2. The design of 8-amino-2-phenyl-2,7-naphthyridones.
2
. Results and Discussion
2
.1. Chemistry
The synthetic pathway of compounds 9a–k and 10a–s is schematically shown in Scheme 1.
According to our reported procedures [11], the key step to constructing the 2-phenyl-2,7-naphthyridone
scaffold is the introduction of a 2-phenyl group into the framework. The Ullmann-type coupling
of pyridone
condensation of 2-cyano-N-phenylacetamide
. The key building block 8-chloro-2-phenyl-2,7-naphthyridone
condensation–cyclization–chlorination reaction using substance as the substrate. With intermediate
in hand, compounds 9a and 10a were smoothly synthesized through the direct palladium-catalyzed
coupling reactions of substance 7 and the corresponding aromatic amine 8.
4
with 1-fluoro-4-iodobenzene produced 1-phenyl-pyridine-2-one 6a, while the
with 2,4-pentanedione produced pyridine-2-ones
was successfully produced by a
5
6
b
–f
7
6
7
–k
–s
Scheme 1. Synthesis of target compounds 9a
–k and 10a–s. Reaction conditions and reagents:
◦
(
i) 1-fluoro-4-iodobenzene, CuI, DMEDA, K PO , dioxane, 100 C; (ii) 2,4-pentanedione, piperidine,
3
4
◦
◦
◦
◦
EtOH, 90 C; (iii) DMF-DMA, DMF, 90 C; (iv) H SO , 110 C; (v) POCl , 110 C; (vi) Pd (dba) , dppp,
2
4
3
2
3
◦
t-BuONa, dioxane, 100 C.

Molecules 2019, 24, 4461
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2
.2. Biological Evaluation
The ability of the synthesized compounds to inhibit MET, c-Kit, and VEGFR-2 activities was
evaluated using an enzyme assay with a recombinant kinase domain [29]. Based on the structure
activity relationship (SAR) of MET inhibitors [30], we proposed that the removal of the key diaryl ether
fragments in compound
exhibited no obvious MET inhibitory activity at 5000 nM, while our previously reported lead compound
exhibited excellent MET inhibitory activity (IC50 of 9.9 nM). Interestingly, compound 9g (n = 1, block
A-6/4-pyridyl group) exhibited a moderate inhibitory activity against c-Kit (IC50 of 832.0 nM) that was
only 2.5-fold less potent than that of compound (IC50 of 329.6 nM). More importantly, 9k (n = 1, block
A-9/4-quinolyl group) exhibited excellent c-Kit inhibitory activity (IC50 of 8.5 nM); 9k is 38.8-fold more
potent than compound . Moreover, compounds 9c (n = 0, block A-3/2, 6-dichloro-phenyl group),
(block A-6), and 9k (block A-9) exhibited moderate VEGFR-2 inhibitory activity (IC50 values of
3 would result in a loss of MET activity. As shown in Table 1, compounds 9a–k
3
3
3
9
g
2
38.5–691.2 nM), which was comparable to compound 3 (IC50 of 279.9 nM).
Table 1. Inhibitory activity of 9a–k against MET, c-Kit, and VEGFR-2.
a
Inhibitory Activity, IC , nM
5
0
No.
Block A
n
MET
c-Kit
VEGFR-2
9
a
A-1
A-2
A-3
A-4
A-5
A-1
A-6
A-4
A-7
A-8
A-9
3
0
0
0
0
0
1
1
1
1
1
1
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
9.9
>5000
>5000
>5000
>5000
>5000
>5000
832.0
>5000
>5000
>5000
8.5
>5000
>5000
691.2
>5000
>5000
>5000
601.3
>5000
>5000
>5000
238.5
9
b
9
c
9
d
9
e
9
f
9
g
9
h
9
9
i
j
9
k
329.6
279.9
a
In vitro kinase assays were performed with the indicated purified recombinant MET, c-Kit, or VEGFR-2 kinase
domains (nM).
2
To further study the structure activity relationship (SAR) of the 2-phenyl group and the R group,
compounds 10a were screened for their inhibitory activities against MET, c-Kit, and VEGFR-2 (Table 2).
Similar to compounds 9a , compounds 10a showed no obvious MET inhibitory activity. Compound
0d (2-(4-fluoro)-phenyl group and n = 1, block A-9/4-quinolyl group) exhibited weak c-Kit inhibitory
–
s
–
k
–s
1
activity, while compounds 10l (2-(4-chloro)-phenyl group) and 10r (2-(4-trifluoromethyoxy)phenyl
group) bearing the same block A-9 (4-quinolyl group) exhibited slightly stronger c-Kit inhibitory activity
than compound
group) or A-9 (4-quinolyl group) showed different degrees of inhibiting VEGFR-2. For examples,
compounds 10d 10k, and 10o exhibited comparable VEGFR-2 inhibitory activity (IC50 values of
08–538 nM) to compound (IC50 of 279.9 nM). More importantly, compounds 10l and 10r exhibited
3 (IC50 of 329.6 nM). Interestingly, most compounds 10 bearing block A-6 (4-pyridyl
,
2
3
excellent VEGFR-2 inhibitory activity (IC50 values of 31.7–56.5 nM)—i.e., they are 5.0–8.8-fold more
potent than compound 3.

Molecules 2019, 24, 4461
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Table 2. Inhibitory activity of 10a–s against MET, c-Kit, and VEGFR-2.
a
Inhibitory Activity, IC , nM
5
0
R1
No.
Block A
n
c-Met
c-Kit
VEGFR-2
1
1
1
1
1
1
1
1
0a
0b
0c
0d
0e
0f
0g
0h
A-4
A-4
A-6
A-9
A-4
A-4
A-6
A-9
A-4
A-4
A-6
A-9
A-4
A-4
A-6
A-7
A-8
A-9
A-9
0
1
1
1
0
1
1
1
0
1
1
1
0
1
1
1
1
1
1
4-F
4-F
4-F
4-F
H
H
H
H
4-Cl
4-Cl
4-Cl
4-Cl
4-OCF3
4-OCF3
4-OCF3
4-OCF3
4-OCF3
4-OCF3
2,4-F2
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
>5000
9.9
>5000
>5000
>5000
1609
>5000
>5000
>5000
>5000
>5000
>5000
>5000
107
>5000
>5000
>5000
>5000
>5000
169
>5000
>5000
>5000
208
>5000
>5000
>5000
1031
1
1
0i
0j
>5000
>5000
263
1
0k
1
0l
0m
0n
56.5
1
1
>5000
>5000
538
>5000
>5000
31.7
1
1
1
0o
0p
0q
1
1
0r
0s
>5000
329.6
887
279.9
3
a
In vitro kinase assays were performed with the indicated purified recombinant MET, c-Kit, or VEGFR-2 kinase
domains (nM).
2
.3. Molecular Modeling
Molecular docking experiments were further performed to determine the SAR [31–37]. As shown
in Figure 3A–C and Table 3, the entire molecules of 9g
binding pocket. The main weak interactions between 9g and c-Kit included: (1) the H-bond interactions
with residues Asp810 and Cys673; (2) the ion– interaction with Lys623; and (3) the hydrophobic
, 9k, and 10r were favorably located in the c-Kit
π
interaction with Leu799. The stronger H-bond interactions with Cys673 and additional hydrophobic
interactions with residues Leu595 and Tyr672 of compound 10r rendered 10r five-times more potent
than compound 9g. The further enhancement of key H-bond interactions with residues Asp810 and
Cys673 resulted in the significantly improved c-Kit inhibitory activity of 9k.
Table 3. Individual energy components of the free energies of ligand with c-Kit and VEGFR-2.
N.O.
Compound
∆Eele
∆Evdw ∆Gnp
∆Gpol
∆H
-T∆S
∆Gcal
IC50 (nM)
9
g
−
18.60
21.78
18.78
−
−
−
−
−
−
52.83 −5.49
60.09 −5.91
59.91 −6.52
53.91 −5.36
60.46 −5.86
64.08 −6.37
42.12
44.37
45.23
−
−
−
34.81
43.42
39.98
14.67
13.19
15.90
−
−
−
20.13
30.23
24.08
832
8.5
169
c-Kit (4U0I)
9k
0r
−
1
−
−
−
−
9g
26.32
26.56
27.82
40.44
42.55
43.36
−45.15
−50.34
−54.92
15.18
15.55
16.38
−29.97
−34.79
−38.54
601
238.5
31.7
VEGFR-2 (3EFL)
9k
10r

Molecules 2019, 24, 4461
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Figure 3. The proposed binding mode of: (
with c-Kit (magenta); ( 9g with VEGFR-2 (green); (
magenta). The red dashed line represents a hydrogen bond. For clarity, only key residues are shown.
A
)
9g with c-Kit (green); (
B
)
9k with c-Kit (cyan); (
C) 10r
D)
E
)
9k with VEGFR-2 (cyan); (
F)
10r with VEGFR-2
(
As shown in Figure 3D–F and Table 3, compounds 9g
, 9k, and 10r were entirely located in the
VEGFR-2 binding pocket. The main weak interactions between compound 9g and VEGFR-2 included:
(1) the H-bond interactions with residues Asp1046 and Cys919; (2) ion–π interaction with Lys868;
(
3) the hydrophobic interaction with Leu1035. The stronger H-bond interactions with residues Cys919
and additional hydrophobic interactions with residues Leu840 and Tyr918 rendered compound 9k
more potent than 9g. The further enhancement of key H-bond interactions with residues Asp1046
and additional hydrophobic interaction with residues Ile892 and Leu1019 resulted in the significantly
improved VEGFR-2 inhibitory activity of 10r.
Taking the molecular docking results into account, we hypothesize that the hydrogen bond acceptor
(N containing heterocycle) and hydrophobic effects (fused aromatic ring) of 8-amino substituents are
crucial to improve the inhibitory activity for c-Kit and VEGFR-2 kinase.
3
. Conclusions
In summary, we described the design and synthesis of a series of 8-amino-substituted 2-phenyl-2,7-
naphthyridin-1(2H)-one derivatives to broaden the application of this new 2,7-naphthyridone scaffold.
Preliminary biological screening resulted in the discovery of new lead compounds 9k 10l, and 10r
which exhibit more potent c-Kit and VEGFR-2 kinase inhibitory activity than the previously reported
lead compound, . Molecular docking results provided further insight into the binding interactions
of the new lead compounds with c-Kit and VEGFR-2 kinase. We identified 8-amino-substituted
,
,
3
2
4
4
-phenyl-2,7-naphthyridin-1(2H)-one as a new lead scaffold of c-Kit and VEGFR-2 kinase inhibitors.
. Materials and Methods
.1. Biochemical Kinase Assays
The ability of compounds to inhibit the activity of three kinases (MET, c-Kit, and VEGFR-2) was
tested in vitro [30]. Enzyme assays were run in homogeneous time-resolved fluorescence (HTRF)
format in 384-well microtiter plates using purified kinases purchased from Invitrogen (Carlsbad, CA,
US). The HTRF KinEASE TK kit (contains substrate-biotin, antibody-cryptate, streptavidin-XL665,

Molecules 2019, 24, 4461
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5 enzymatic buffer, and detection buffer) was purchased from Cisbio (Codolet, France), and the
×
kinase assays were performed according to the manufacturer’s instructions. After the kinases and
◦
the compounds incubated at 25~30 C for 5 min, the reactions were initiated by the addition of 2
µL
of mixed substrate solution (mixed solution of ATP (Sigma, Shanghai, China) and substrate-biotin).
The final concentrations of kinases were at EC80 and the total reaction volume was 8
incubated at 30 C for 30~60 min, then the reactions were quenched by the addition 8
µ
L. Plates were
◦
µL mixed
detection solution (mixed solution of antibody-cryptate and streptavidin-XL665 in detection buffer).
The fluorescence excitation wavelength was 320 nM. The fluorescence at 665 nm (acceptor emission
wavelength) and 620 nm (donor emission wavelength) was measured with a PHERAstar FS plate reader
(
BMG, LABTECH, Ortenberg, Germany) using a time delay of 50 µs. All kinase assays were conducted
using ATP concentrations below the enzyme Kmapp and kinase-specific biotinylated substrate peptides.
The data for dose responses were plotted as percentage of inhibition calculated with the data
reduction formula 100
×
[1
−
(U1
−
C )/(C1
−
C )] versus concentration of compound, where U is the
2
2
emission ratio of 665 nm and 620 nm of test sample, C is the average value obtained for solvent control
1
(
2% DMSO), and C is the average value obtained for no reaction control (no kinase sample). Inhibition
2
curves were generated by plotting percentage of control activity versus log10 of the concentration
of each kinase. The IC50 values were calculated by nonlinear regression with Graphpad Prism 5
(GraphPad Software, San Diego, CA).
4
.2. Molecular Modeling
The three-dimensional structures of the small molecules were constructed and primarily optimized
by Sybyl 2.0 software. Steepest descent and conjugate gradient methods were used in the optimization
process. Autodock Tools was used to assign Gasteiger charges for both the receptors and inhibitors.
The optimized probes were docked into the crystal structures of c-Kit (PDB ID: 4U0I) and VEGFR-2
(
PDB ID: 3EFL) with Autodock 4.2.5, 1, respectively. The gird size was set to be 70
×
70
×
70 and
the grid point spacing was set at default value 0.375 Å. A total of 256 runs were performed by using
Lamarkian genetic algorithm (LGA) for conformational search. The best poses were selected for the
binding model analysis for all the inhibitors. The figures were prepared with PyMOL 2.2.3 [31–37].
4
.3. Chemistry
4
.3.1. General Information
Unless otherwise noted, all chemical reagents were commercially available and treated with
standard methods. Silica gel column chromatography (CC). Silica gel (200–400 Mesh; Qingdao Makall
Group Co., Ltd.; Qingdao; China). Solvents were dried in a routine way and redistilled. All reactions
involving air- or moisture-sensitive reagents were performed under a nitrogen or argon atmosphere.
1
13
HNMR spectra (400 MHz) and CNMR (100 MHz) spectra were recorded on a Bruker BioSpin AG
Ultrashield Plus AV 400, Fällanden, Switzerland) spectrometer as deuterochloroform (CDCl ) or
(
3
dimethyl sulfoxide-d (DMSO-d ) solutions using tetramethylsilane (TMS) as an internal standard
6
6
(δ = 0) unless noted otherwise. MS spectra were obtained on an Agilent technologies 6120 quadrupole
LC/MS (ESI). All reactions were monitored using thin-layer chromatography (TLC) on silica gel plates.
Yields were of purified compounds and were not optimized.
4
.3.2. General Procedure for the Preparation of Intermediates 7a–f
The intermediates 7a–f were prepared according to our previous report [11].
4
.3.3. General Procedure for the Preparation of Targets 9a–k and 10a–s
An oven-dried Schlenk tube was charged with
0.04 mmol), t-BuONa (0.8 mmol), and amine (0.48 mmol), and then purged with argon three times.
Ultra-dry dioxane (15 mL) was added to the Schlenk tube with a syringe at argon atmosphere.
7 (0.4 mmol), Pd (dba) (0.02 mmol), xantphos
2 3
(

Molecules 2019, 24, 4461
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◦
The mixture was stirred at 110 C overnight. After cooling to room temperature, the mixture was
concentrated in vacuo and the residue purified by flash chromatography on silica gel using DCM/MeOH
(100:1) as eluent to obtain 9a–k and 10a–s.
2
-(4-fluorophenyl)-8-(phenylamino)-2,7-naphthyridin-1(2H)-one (9a): Yellow solid (72% yield). HPLC
1
purity: 98.3%. H NMR (400 MHz, DMSO-d )
δ: 11.79 (s, 1H), 8.30 (d, J = 5.3 Hz, 1H), 7.81 (m, 2H),
6
7
.69 (d, J = 7.3 Hz, 1H), 7.61–7.31 (m, 6H), 7.02 (m, 1H), 6.95 (d, J = 5.3 Hz, 1H), 6.68 (d, J = 7.3 Hz, 1H);
13
C NMR (100 MHz, DMSO-d6)
δ: 162.59, 160.32, 155.89, 150.22, 145.72, 139.81, 137.53, 136.66, 129.47,
+
1
28.74, 120.33, 119.81, 109.91, 116.00, 109.91, 105.36; ESI-MS m/z: 332.3 ([M + H] ).
8
-((2,6-dimethylphenyl)amino)-2-(4-fluorophenyl)-2,7-naphthyridin-1(2H)-one (9b): Yellow solid (82% yield).
1
H NMR (400 MHz, CDCl3) δ: 10.57 (s, 1H), 8.14 (d, J = 5.6 Hz, 1H), 7.44 (m, 2H), 7.22 (m, 2H); 7.24(d,
13
J = 7.2 Hz, 1H), 7.10 (m, 3H), 6.56 (d, J = 5.6 Hz, 1H), 6.42 (d, J = 7.2 Hz, 1H), 2.23 (s, 6H); C NMR
100 MHz, DMSO-d6) : 162.76, 162.66, 160.22, 157.44, 150.50, 145.73, 137.35, 136.81, 135.23, 129.52,
(
δ
+
1
27.72, 125.91, 116.05, 108.49, 104.96, 104.71, 18.40; ESI-MS m/z: 360.4 ([M + H] ).
8
-((2,6-dichlorophenyl)amino)-2-(4-fluorophenyl)-2,7-naphthyridin-1(2H)-one (9c): Yellow solid (72% yield).
1
HPLC purity: 95.7%. H NMR (400 MHz, CDCl )
8
δ
: 10.84 (s, 1H), 8.19 (d, J = 5.6 Hz, 1H), 7.43–7.13 (m,
3
13
H), 6.70 (d, J = 5.6 Hz, 1H), 6.46 (d, J = 7.2 Hz, 1H); C NMR (100 MHz, DMSO-d6) δ: 162.72, 162.54,
1
1
60.28, 156.45, 150.44, 145.62, 137.66, 136.58, 134.56, 133.64, 129.55, 128.50, 116.09, 115.86, 110.07, 105.17,
04.93; ESI-MS m/z: 401.2 ([M + H] ).
+
2
-(4-fluorophenyl)-8-(pyridin-3-ylamino)-2,7-naphthyridin-1(2H)-one (9d): Yellow solid (85% yield). HPLC
1
purity: 92.1%. H NMR (400 MHz, DMSO-d ) δ: 11.81 (s, 1H), 8.89 (s, 1H), 8.37 (d, J = 8 Hz, 1H), 8.33
6
(
3
d, J = 5.2 Hz, 1H), 8.23 (d, J = 3.6 Hz, 1H), 7.71 (d, J = 7.2 Hz, 1H), 7.61–7.58 (m, 2H), 7.44–7.35 (m,
H), 7.03 (d, J = 5.2 Hz, 1H), 6.71 (d, J = 7.2 Hz, 1H); C NMR (100 MHz, DMSO-d6) δ: 160.35, 155.77,
13
1
1
50.06, 145.76, 143.02, 141.50, 137.74, 136.58, 129.53, 129.44, 126.57, 123.52, 116.15, 115.92, 110.67, 105.85,
05.17; ESI-MS m/z: 333.3 ([M + H] ).
+
2
-(4-fluorophenyl)-8-(isoquinolin-7-ylamino)-2,7-naphthyridin-1(2H)-one (9e): Yellow solid (85% yield).
1
HPLC purity: 96.0%. H NMR (400 MHz, DMSO-d6)
δ: 11.99 (s, 1H), 9.22 (s, 1H), 8.84 (s, 1H), 8.41 (m,
2
H), 7.82 (dd, J = 8.8 Hz, J = 8.8 Hz, 2H), 7.56 (d, J = 5.2 Hz, 1H), 7.43–7.40 (m, 2H), 7.30 (d, J = 7.2 Hz,
1 2
1
H), 7.28 (d, J = 8.8 Hz, 1H), 7.24 (d, J = 8.8 Hz, 1H), 6.80(d, J = 5.2 Hz, 1H), 6.50 (d, J = 7.2 Hz, 1H);
1
3
C NMR (100 MHz, DMSO-d6)
δ: 162.62, 155.68, 151.44, 150.13, 145.71, 141.72, 138.55, 137.74, 136.60,
1
3
31.27, 129.54, 129.19, 127.15, 125.54, 119.98, 116.14, 115.92, 113.83, 110.74, 105.95, 105.24; ESI-MS m/z:
83.3 ([M + H] ).
+
8
-(benzylamino)-2-(4-fluorophenyl)-2,7-naphthyridin-1(2H)-one (9f): Yellow solid (87% yield). HPLC
1
purity: 96.6%. H NMR(400 MHz, DMSO-d )
δ: 9.59 (t, J = 5.2 Hz, 1H), 8.16 (d, J = 5.2 Hz, 1H), 7.59 (d,
6
J = 7.2 Hz, 1H), 7.54–7.51 (m, 2H), 7.38–7.25 (m, 7H), 6.70 (d, J = 5.2 Hz, 1H), 6.56 (d, J = 7.2 Hz, 1H),
.70 (d, J = 5.2 Hz, 2H); 13C NMR (100 MHz, DMSO-d6)
: 162.39, 160.15, 158.40, 151.01, 145.66, 139.62,
37.23, 136.75, 129.33, 128.37, 127.33, 126.78, 115.79, 107.47, 104.85, 104.64, 43.91; ESI-MS m/z: 346.3
4
δ
1
+
([M + H] ).
2
-(4-fluorophenyl)-8-((pyridin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (9g): Yellow solid (87% yield).
1
HPLC purity: 99.8%. H NMR (400 MHz, CDCl )
δ
: 9.71 (t, J = 5.6 Hz, 1H), 8.51 (d, J = 5.2 Hz, 1H), 8.16
3
(
(
d, J = 5.2 Hz, 1H), 7.39 (d, J = 7.2 Hz, 1H), 7.37 (m, 4H), 7.28 (d, J = 5.2 Hz, 1H), 7.26–7.18 (m, 2H), 6.56
d, J = 5.2 Hz, 1H), 6.40 (d, J = 7.2 Hz, 1H), 4.79 (d, J = 5.6 Hz, 2H); 13C NMR (100 MHz, DMSO-d6)
δ:
1
4
62.33, 160.14, 158.33, 150.83, 149.45, 149.14, 145.65, 137.33, 136.72, 129.43, 122.07, 115.98, 107.85, 104.80,
2.77; ESI-MS m/z: 347.3 ([M + H] ).
+
2
-(4-fluorophenyl)-8-((pyridin-3-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (9h): Yellow solid (77% yield).
1
HPLC purity: 99.8%. H NMR (400 MHz, DMSO-d6)
δ: 9.69 (t, J = 5.6 Hz, 1H), 8.62 (s, 1H), 8.49 (m,
1
1
H), 8.19 (d, J = 5.2 Hz, 1H), 7.79 (m, 1H), 7.63 (d, J = 7.2 Hz, 1H), 7.58–7.37 (m, 5H), 6.75 (d, J = 5.2 Hz,
H), 6.60 (d, J = 7.2 Hz, 1H), 4.77 (d, J = 5.6 Hz, 2H); C NMR (100 MHz, DMSO-d6) δ: 160.14, 158.29,
13

Molecules 2019, 24, 4461
8 of 13
1
1
50.88, 148.89, 147.79, 145.66, 137.25, 136.71, 135.34, 135.12, 129.40, 128.79, 128.52, 123.46, 115.79, 107.75,
04.83, 41.42; ESI-MS m/z: 347.3 ([M + H] ).
+
2
-(4-fluorophenyl)-8-((furan-2-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (9i): Yellow solid (79% yield).
1
HPLC purity: 95.6%. H NMR (400 MHz, CDCl )
δ: 9.48 (t, J = 5.2 Hz, 1H), 8.22 (d, J = 5.2 Hz, 1H),
3
7
.36 (d, J = 7.2 Hz, 1H), 7.34–7.32 (m, 2H), 7.21–7.17 (m, 3H), 6.54 (d, J = 5.2 Hz, 1H), 6.36 (d, J = 7.2 Hz,
13
1
1
H), 6.27 (m, 2H), 4.74 (d, J = 5.2 Hz, 2H); C NMR (100 MHz, DMSO-d6) δ: 162.59, 162.32, 160.15,
58.05, 152.40, 150.85, 145.62, 142.19, 137.27, 136.69, 129.40, 115.98, 110.43, 107.72, 106.84, 104.83, 104.74,
+
3
7.18; ESI-MS m/z: 336.3 ([M + H] ).
2
-(4-fluorophenyl)-8-((naphthalen-1-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (9j): Yellow solid (81%
1
yield). HPLC purity: 99.5%. H NMR(400 MHz, DMSO-d )
δ: 9.60 (t, J = 5.6 Hz, 1H), 8.19 (d, J = 5.2 Hz,
6
1
6
δ
H), 8.10 (m, 1H), 7.95 (m, 1H), 7.85 (m, 1H), 7.56 (d, J = 7.2 Hz, 1H), 7.55–7.43 (m, 6H), 7.31 (m, 2H),
.71 (d, J = 5.2 Hz, 1H), 6.55 (d, J = 7.2 Hz, 1H), 5.16 (d, J = 5.6 Hz, 2H); 13C NMR (100 MHz, DMSO-d6)
: 145.74, 137.26, 136.67, 136.64, 134.76, 133.38, 131.03, 129.61, 129.37, 129.29, 129.00, 128.55, 127.59,
+
126.32, 125.81, 125.50, 125.44, 123.39, 115.95, 107.53, 104.88, 104.70, 41.88; ESI-MS m/z: 396.4 ([M + H] ).
2
-(4-fluorophenyl)-8-((quinolin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (9k): Yellow solid (87% yield).
1
HPLC purity: 99.8%. H NMR (400 MHz, CDCl )
δ: 9.72 (t, J = 5.6 Hz, 1H), 8.81 (d, J = 4.4 Hz, 1H),
3
8
.19 (d, J = 5.2 Hz, 1H), 8.13–8.10 (m, 2H), 7.71 (t, J = 15.2 Hz, 1H), 7.57 (t, J = 15.2 Hz, 1H), 7.44 (d,
J = 4.4 Hz, 1H), 7.38 (d, J = 7.2 Hz, 1H), 7.37–7.35(m, 1H), 7.24–7.17 (m, 3H), 6.58 (d, J = 5.2 Hz, 1H), 6.41
d, J = 7.2 Hz, 1H), 5.29 (d, J = 5.6 Hz, 2H); 13C NMR (100 MHz, DMSO-d6)
: 162.59, 162.40, 160.15,
58.37, 150.87, 150.31, 147.59, 145.72, 145.12, 137.34, 136.71, 129.61, 129.42, 126.60, 126.16, 123.51, 118.82,
(
δ
1
1
+
15.98, 115.75, 107.89, 104.91, 40.71; ESI-MS m/z: 397.4 ([M + H] ).
2
-(4-fluorophenyl)-3-methyl-8-(pyridin-3-ylamino)-2,7-naphthyridin-1(2H)-one (10a): Yellow solid (77%
1
yield). HPLC purity: 94.4%. H NMR (400 MHz, DMSO-d )
δ: 11.72 (s, 1H), 8.87 (s, 1H), 8.36 (m, 1H),
6
8
.25 (d, J = 5.6 Hz, 1H), 8.20 (m, 1H), 7.50–7.32 (m, 5H), 6.90 (d, J = 5.6 Hz, 1H), 6.64 (s, 1H), 1.98 (s, 3H);
+
ESI-MS m/z: 347.3 ([M + H] ).
2
-(4-fluorophenyl)-3-methyl-8-((pyridin-3-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10b): Yellow solid
1
(74% yield). HPLC purity: 96.3%. H NMR (400 MHz, DMSO-d )
δ: 9.53 (t, J = 5.6 Hz, 1H), 8.55 (s,
6
1
(
H), 8.43 (m, 1H), 8.08 (d, J = 5.2 Hz, 1H), 7.72 (m, 1H), 7.40–7.30 (m, 5H), 6.58 (d, J = 5.2 Hz, 1H), 6.49
: 162.89, 160.45, 158.09,
s, 1H), 4.68 (d, J = 5.6 Hz, 2H), 1.92 (s, 3H). 13C NMR (100 MHz, DMSO-d6)
δ
1
1
50.67, 148.91, 147.96, 145.19, 144.84, 135.39, 135.11, 134.43, 130.85, 130.76, 123.44, 116.33, 107.12, 104.31,
03.39, 21.18; ESI-MS m/z: 361.4 ([M + H] ).
+
2
-(4-fluorophenyl)-3-methyl-8-((pyridin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10c): Yellow solid
1
(77% yield). HPLC purity: 99.8%. H NMR (400 MHz, DMSO-d )
δ
: 9.59 (t, J = 5.6 Hz, 1H), 8.46 (d,
6
J = 5.0 Hz, 2H), 8.04 (d, J = 5.6 Hz, 1H), 7.45–7.35 (m, 4H), 7.28 (d, J = 5.0 Hz, 2H), 6.59 (d, J = 5.6 Hz,
1
1
2
H), 6.49 (s, 1H), 4.70 (d, J = 5.6 Hz, 2H), 1.94 (s, 3H). 13C NMR (100 MHz, DMSO-d6)
δ: 160.47, 158.17,
50.63, 149.45, 149.16, 145.20, 144.89, 134.45, 130.88, 130.79, 122.11, 116.34, 107.23, 104.31, 103.44, 42.73,
+
1.20; ESI-MS m/z: 361.4 ([M + H] ).
2
-(4-fluorophenyl)-3-methyl-8-((quinolin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10d): Yellow solid
1
(78% yield). HPLC purity: 95.9%. H NMR (400 MHz, DMSO-d )
δ
: 9.64 (t, J = 5.6 Hz, 1H), 8.79 (d,
6
J = 4.0 Hz, 1H), 8.21 (m, 1H), 8.06 (d, J = 4.0 Hz, 1H), 8.03 (m, 1H), 7.77 (t, J = 15.2 Hz, 1H), 7.64 (t,
J = 15.2 Hz, 1H), 7.44 (d, J = 5.2 Hz, 1H), 7.42–7.34 (m, 4H), 6.60 (d, J = 5.2 Hz, 1H), 6.50 (s, 1H), 5.21 (d,
J = 5.6 Hz, 2H), 1.94 (s, 3H). 13C NMR (100 MHz, DMSO-d6)
δ: 163.60, 162.91, 160.47, 158.14, 150.61,
1
1
47.58, 145.27, 144.98, 134.42, 130.86, 129.23, 126.61, 126.17, 124.20, 123.53, 118.90, 118.38, 116.35, 107.27,
04.35, 103.54, 40.64, 21.21; ESI-MS m/z: 411.4 ([M + H] ).
+
3
-methyl-2-phenyl-8-(pyridin-3-ylamino)-2,7-naphthyridin-1(2H)-one (10e): Yellow solid (80% yield). HPLC
1
purity: 90.1%. H NMR (400 MHz, DMSO-d6)
δ: 11.76 (s, 1H), 8.86 (s, 1H), 8.36 (m, 1H), 8.25 (d,
J = 5.2 Hz, 1H), 8.19 (m, 1H), 7.64–7.50 (m, 4H), 7.39 (m, 1H), 7.34 (m, 1H), 6.90 (d, J = 5.2 Hz, 1H), 6.63

Molecules 2019, 24, 4461
9 of 13
(
s, 1H), 1.98 (s, 3H); 13C NMR (100 MHz, DMSO-d6)
δ: 164.14, 158.29, 150.68, 145.37, 142.82, 141.34,
1
3
38.04, 136.64, 132.19, 131.50, 129.56, 128.67, 126.38, 123.48, 110.01, 104.71, 104.47, 21.23; ESI-MS m/z:
29.3 ([M + H] ).
+
3
-methyl-2-phenyl-8-((pyridin-3-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10f): Yellow solid (78% yield).
1
HPLC purity: 97.9%. H NMR (400 MHz, DMSO-d )
δ: 9.55 (t, J = 4.8 Hz, 1H), 8.55 (m, 1H), 8.43 (m,
6
1
2
1
H), 8.08 (d, J = 4.4 Hz, 1H), 7.72–7.31 (m, 7H), 6.59 (d, J = 4.4 Hz, 1H), 6.48 (s, 1H), 4.68 (d, J = 4.8 Hz,
H), 1.92 (s, 3H); 13C NMR (100 MHz, DMSO-d6)
: 163.44, 158.12, 150.60, 148.91, 147.97, 145.17, 144.80,
38.23, 135.38, 135.10, 129.39, 128.55, 123.45, 107.11, 104.24, 103.45, 41.35, 21.18; ESI-MS m/z: 343.4
δ
+
([M + H] ).
3
-methyl-2-phenyl-8-((pyridin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10g): Yellow solid (67%
1
yield). HPLC purity: 97.7%. H NMR (400 MHz, DMSO-d )
δ
: 9.60 (t, J = 5.6 Hz, 1H), 8.46 (d, J = 5.0 Hz,
6
2
H), 8.04 (d, J = 5.6 Hz, 1H), 7.56–7.46 (m, 3H), 7.34 (m, 2H), 7.28 (d, J = 5.0 Hz, 2H), 6.59 (d, J = 5.6 Hz,
1
1
H), 6.49 (s, 1H), 4.70 (d, J = 5.6 Hz, 2H), 1.93 (s, 3H); 13C NMR (100 MHz, DMSO-d6)
δ
: 163.47, 158.19,
50.55, 149.44, 149.17, 145.18, 144.85, 138.24, 129.40, 128.58, 126.56, 122.15, 107.23, 104.23, 103.51, 42.74,
+
2
1.19; ESI-MS m/z: 343.4 ([M + H] ).
3
-methyl-2-phenyl-8-((quinolin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10h): Yellow solid (88%
1
yield). H NMR (400 MHz, DMSO-d )
δ: 9.66 (t, J = 5.6 Hz, 1H), 8.79 (d, J = 4.0 Hz, 1H), 8.21 (m,
6
1
7
3
H), 8.06 (d, J = 4.0 Hz, 1H), 8.03 (d, J = 5.2 Hz, 1H), 7.77 (t, J = 15.2 Hz, 1H), 7.64 (t, J = 15.2 Hz, 1H),
.56–7.33 (m, 6H), 6.60 (d, J = 5.2 Hz, 1H), 6.51 (s, 1H), 5.20 (d, J = 5.6 Hz, 2H), 1.94 (s, 3H); ESI-MS m/z:
+
93.4 ([M + H] ).
2
-(4-chlorophenyl)-3-methyl-8-(pyridin-3-ylamino)-2,7-naphthyridin-1(2H)-one (10i): Yellow solid (86%
1
yield). HPLC purity: 91.1%. H NMR (400 MHz, DMSO-d )
δ: 11.70 (s, 1H), 8.86 (s, 1H), 8.36 (m, 1H),
6
8
1
1
.25 (d, J = 5.2 Hz, 1H), 8.19 (m, 1H), 7.82–7.46 (m, 4H), 7.39 (m, 1H), 6.90 (d, J = 5.2 Hz, 1H), 6.65 (s,
H), 1.98 (s, 3H); 13C NMR (100 MHz, DMSO-d6)
:163.14, 155.29, 149.89, 145.37, 142.82, 141.34, 138.04,
36.64, 132.19, 131.50, 129.56, 128.67, 126.38, 123.48, 110.01, 104.71, 104.47, 21.23; ESI-MS m/z: 363.8
δ
+
([M + H] ).
2
-(4-chlorophenyl)-3-methyl-8-((pyridin-3-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10j): Yellow solid
1
(
74% yield). HPLC purity: 92.1%. H NMR (400 MHz, DMSO-d )
δ
: 9.50 (t, J = 5.6 Hz, 1H), 8.55 (s, 1H),
6
8.43 (d, J = 4.4 Hz, 1H), 8.08 (d, J = 5.2 Hz, 1H), 7.71 (d, J = 7.6 Hz, 1H), 7.61 (d, J = 8.4 Hz, 2H), 7.39 (d,
J = 8.4 Hz, 2H), 7.32 (dd, J = 4.4 Hz, J = 7.6 Hz, 1H), 6.58 (d, J = 5.2 Hz, 1H), 6.49 (s, 1H), 4.68 (d,
1
2
13
J = 5.6 Hz, 2H), 1.92 (s, 3H); C NMR (100 MHz, DMSO-d6)
δ: 163.40, 158.08, 150.73, 148.88, 147.97,
1
45.21, 144.59, 137.09, 135.37, 135.14, 133.20, 130.63, 129.43, 123.47, 107.17, 104.42, 103.34, 41.35, 21.13;
+
ESI-MS m/z: 377.8 ([M + H] ).
-(4-chlorophenyl)-3-methyl-8-((pyridin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10k): Yellow solid
77% yield). HPLC purity: 99.8%. 1H NMR (400 MHz, DMSO-d6)
: 9.59 (t, J = 5.6 Hz, 1H), 8.46
d, J = 4.0 Hz, 2H), 8.04 (d, J = 5.6 Hz, 1H), 7.61 (d, J = 8.4 Hz, 2H), 7.41 (d, J = 8.4 Hz, 2H), 7.28 (d,
2
(
(
δ
J = 5.0 Hz, 2H), 6.59 (d, J = 5.6 Hz, 1H), 6.49 (s, 1H), 4.70 (d, J = 5.6 Hz, 2H), 1.94 (s, 3H); 13C NMR
(
1
100 MHz, DMSO-d6) δ: 163.42, 158.15, 150.68, 149.44, 149.15, 145.21, 144.63, 137.11, 133.21, 130.66,
29.43, 122.13, 107.27, 104.41, 103.40, 42.74, 21.15; ESI-MS m/z: 377.8 ([M + H] ).
+
2
-(4-chlorophenyl)-3-methyl-8-((quinolin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10l): Yellow solid
1
(84% yield). HPLC purity: 98.0%. H NMR (400 MHz, DMSO-d )
δ
: 9.62 (t, J = 5.6 Hz, 1H), 8.79 (d,
6
J = 4.0 Hz, 1H), 8.21 (m, 1H), 8.06 (d, J = 5.2 Hz, 1H), 8.03 (m, 1H), 7.77 (t, J = 15.2 Hz, 1H), 7.64 (t,
J = 15.2 Hz, 1H), 7.61 (d, J = 8.4 Hz, 2H), 7.40 (d, J = 8.4 Hz, 2H), 7.37 (d, J = 4.0 Hz, 1H), 6.60 (d,
J = 5.2 Hz, 1H), 6.51 (s, 1H), 5.21 (d, J = 5.6 Hz, 2H), 1.94 (s, 3H); 13C NMR (100 MHz, DMSO-d6)
δ:
1
1
62.91, 158.14, 150.73, 150.31, 147.60, 145.28, 145.15, 144.69, 137.10, 133.22, 130.65, 129.61, 129.44, 129.23,
26.62, 126.17, 123.52, 118.91, 107.30, 104.44, 103.49, 40.63, 21.16; ESI-MS m/z: 427.9 ([M + H] ).
+

Molecules 2019, 24, 4461
10 of 13
3
-methyl-8-(pyridin-3-ylamino)-2-(4-(trifluoromethoxy)phenyl)-2,7-naphthyridin-1(2H)-one (10m): Yellow
1
solid (79% yield). HPLC purity: 99.1%. H NMR (400 MHz, DMSO-d )
δ: 11.67 (s, 1H), 8.87 (s, 1H),
6
8
.36 (d, J = 8.0 Hz, 1H), 8.25 (d, J = 5.6 Hz, 1H), 8.20 (d, J = 4.0 Hz, 1H), 7.59 (s, 4H), 7.34 (dd, J = 8.0 Hz,
1
13
J2 = 4.0 Hz, 1H), 6.90 (d, J = 5.6 Hz, 1H), 6.65 (s, 1H), 1.98 (s, 3H); C NMR (100 MHz, DMSO-d6) δ:
1
1
63.62, 155.54, 149.94, 148.24, 145.29, 142.88, 141.38, 136.99, 136.58, 130.83, 126.45, 123.49, 122.14, 121.31,
18.76, 110.05, 104.91, 104.38, 21.20; ESI-MS m/z: 413.3 ([M + H] ).
+
3
-methyl-8-((pyridin-3-ylmethyl)amino)-2-(4-(trifluoromethoxy)phenyl)-2,7-naphthyridin-1(2H)-one (10n):
1
Yellow solid (74% yield). H NMR (400 MHz, DMSO-d )
δ
: 9.50 (t, J = 5.6 Hz, 1H), 8.55 (s, 1H), 8.43
6
(
d, J = 4.0 Hz, 1H), 8.08 (d, J = 5.2 Hz, 1H), 7.72 (d, J = 7.6 Hz, 1H), 7.59 (s, 4H), 7.32 (dd, J = 4.0 Hz,
1
13
J2 = 7.6 Hz, 1H), 6.58 (d, J = 5.2 Hz, 1H), 6.50 (s, 1H), 4.68 (d, J = 5.6 Hz, 2H), 1.93 (s, 3H); C NMR
100 MHz, DMSO-d6) : 163.43, 158.08, 150.78, 148.92, 148.06, 147.98, 145.22, 144.52, 137.21, 135.36,
(
1
δ
+
30.89, 123.44, 121.97, 121, 30, 107.14, 104.43, 103.33, 41.34, 21.14; ESI-MS m/z: 427.4 ([M + H] ).
3
-methyl-8-((pyridin-4-ylmethyl)amino)-2-(4-(trifluoromethoxy)phenyl)-2,7-naphthyridin-1(2H)-one (10o):
1
Yellow solid (79% yield). HPLC purity: 99.4%. H NMR (400 MHz, DMSO-d )
δ: 9.56 (t, J = 5.6 Hz, 1H),
6
8
.46 (d, J = 5.2 Hz, 2H), 8.04 (d, J = 5.2 Hz, 1H), 7.54 (s, 4H), 7.28 (d, J = 5.2 Hz, 2H), 6.59 (d, J = 5.2 Hz,
1
1
H), 6.50 (s, 1H), 4.70 (d, J = 5.6 Hz, 2H), 1.95 (s, 3H); 13C NMR (100 MHz, DMSO-d6)
δ
: 163.18, 158.36,
50.71, 149.39, 148.08, 145.50, 144.58, 137.21, 130.97, 123.85, 122.13, 121.30, 118.75, 107.27, 104.44, 103.38,
+
4
2.74, 21.16; ESI-MS m/z: 427.4 ([M + H] ).
8
-((furan-2-ylmethyl)amino)-3-methyl-2-(4-(trifluoromethoxy)phenyl)-2,7-naphthyridin-1(2H)-one
(
10p):
1
Yellow solid (82% yield). HPLC purity: 96.3%. H NMR (400 MHz, DMSO-d )
δ: 9.32 (t, J = 5.6 Hz,
6
1
(
H), 8.12 (d, J = 5.6 Hz, 1H), 7.55–7.49 (m, 5H), 6.60 (d, J = 5.6 Hz, 1H), 6.50 (s, 1H), 6.37 (m, 1H), 6.28
m, 1H), 4.65 (d, J = 5.6 Hz, 2H), 1.93 (s, 3H); 13C NMR (100 MHz, DMSO-d6)
δ: 163.43, 157.84, 152.41,
1
3
50.76, 148.07, 145.20, 144.53, 142.19, 137.18, 130.87, 121.98, 110.42, 107.13, 106.85, 104.48, 103.31, 66.33,
7.10, 21.15; ESI-MS m/z: 416.3 ([M + H] ).
+
3
-methyl-8-((naphthalen-1-ylmethyl)amino)-2-(4-(trifluoromethoxy)phenyl)-2,7-naphthyridin-1(2H)-one (10q):
1
Yellow solid (79% yield). HPLC purity: 97.0%. H NMR (400 MHz, DMSO-d )
δ: 9.43 (t, J = 5.6 Hz,
6
1
H), 8.15 (d, J = 5.2 Hz, 1H), 8.10 (d, J = 8.4 Hz, 1H), 7.93 (dd, J = 8.4 Hz, J = 8.0 Hz, 1H), 7.84 (d,
1 2
J = 8.0 Hz, 1H), 7.54–7.42 (m, 8H), 6.60 (d, J = 5.2 Hz, 1H), 6.50 (s, 1H), 5.13 (d, J = 5.6 Hz, 2H), 1.91
13
(
s, 3H); C NMR(100 MHz, DMSO-d )δ: 158.06, 150.94, 148.01, 145.29, 144.50, 137.14, 134.82, 133.37,
6
1
4
31.03, 130.83, 128.55, 127.59, 126.32, 125.80, 125.50, 123.39, 121.93, 121.26, 118.71, 106.93, 104.52, 103.24,
1.76, 21.14; ESI-MS m/z: 476.4 ([M + H] ).
+
3
-methyl-8-((quinolin-4-ylmethyl)amino)-2-(4-(trifluoromethoxy)phenyl)-2,7-naphthyridin-1(2H)-one (10r):
1
Yellow solid (80% yield). HPLC purity: 94.0%. H NMR (400 MHz, DMSO-d )
δ: 9.62 (t, J = 5.6 Hz,
6
1
H), 8.81 (d, J = 4.0 Hz, 1H), 8.21 (m, 1H), 8.06 (d, J = 5.2 Hz, 1H), 8.05 (m, 1H), 7.77 (t, J = 15.2 Hz, 1H),
7
.64 (t, J = 15.2 Hz, 1H), 7.55 (s, 4H), 7.37 (d, J = 4.0 Hz, 1H), 6.63 (d, J = 5.2 Hz, 1H), 6.54 (s, 1H), 5.22 (d,
13
J = 5.6 Hz, 2H), 1.96 (s, 3H); C NMR (100 MHz, DMSO-d6)
δ: 163.12, 158.66, 151.28, 150.80, 148.12,
1
1
45.80, 145.64, 145.12, 137.69, 131.40, 130.12, 129.71, 127.10, 126.68, 124.02, 122.46, 119.43, 107.80, 104.98,
03.99, 41.12, 21.66; ESI-MS m/z: 477.4 ([M + H] ).
+
2
-(2,4-difluorophenyl)-3-methyl-8-((quinolin-4-ylmethyl)amino)-2,7-naphthyridin-1(2H)-one (10s): Yellow
1
solid (88% yield). HPLC purity: 99.1%. H NMR (400 MHz, DMSO-d )
δ
: 9.54 (t, J = 5.6 Hz, 1H),
6
8
(
.80 (d, J = 4.4 Hz, 1H), 8.21 (d, J = 8.0 Hz, 1H), 8.09 (d, J = 5.6 Hz, 1H), 8.05 (d, J = 8.0 Hz, 1H), 7.77
t, J = 15.2 Hz, 1H), 7.64 (t, J = 15.2 Hz, 1H), 7.61 (s, 1H), 7.55 (t, J = 14.8 Hz, 1H), 7.36 (d, J = 4.4 Hz,
H), 7.29 (t, J = 14.8 Hz, 1H), 6.63 (d, J = 5.6 Hz, 1H), 6.56 (s, 1H), 5.21 (d, J = 5.6 Hz, 2H), 1.99 (s, 3H);
1
13
C NMR (100 MHz, DMSO-d6) δ: 163.02, 158.10, 151.19, 150.32, 147.59, 145.41, 145.09, 144.56, 132.19,
1
4
32.09, 129.60, 129.23, 126.61, 126.16, 123.51, 122.04, 118.88, 122.57, 107.41, 105.31, 105.04, 104.80, 103.05,
0.68, 20.51; ESI-MS m/z: 429.4 ([M + H] ).
+

Molecules 2019, 24, 4461
11 of 13
Author Contributions: H.S., L.Z., H.D., W.H. and N.S. conceived and designed the experiments; L.Z. and H.D.,
performed synthesis; H.S. performed biological work and molecular modelling; W.H. and N.S. analyzed the data;
W.H. and N.S. wrote the paper. W.H. were responsible for the correspondence of the manuscript. All authors
discussed, edited and approved the final version.
Funding: This work was supported by the National Natural Science Foundation of China (No. 21272086), and the
Fundamental Research Funds for the Central Universities (No. CCNU19QN073 & CCNU18TS009).
Conflicts of Interest: The authors declare no conflict of interest.
Abbreviations
MET: mesenchymal
vascular endothelial growth factor receptor 2; PI3K
CK2; Akt1/2, protein kinase B1/2; Tpl-2, Tumor Progression Loci-2; Pdk-1, phosphoinositide-dependent
protein kinase-1; PDE-5, phosphodiesterase type 5; TNF , tumor necrosis factor alpha; SYK, spleen tyrosine
−
epithelial transition factor; c-Kit, receptor tyrosine kinase for the stem cell factor; VEGFR-2,
δ
, phosphatidylinositol 3-kinase delta; CK2, protein kinase
α
kinase; DMEDA, N,N’-Dimethyl-1,2-ethanediamine; DMF-DMA, N,N-dimethylformamide dimethyl acetal; DMF,
N,N-dimethylformamide; ATP, adenosine triphosphate; DMSO, dimethyl sulfoxide; HNMR, hydrogen nuclear
magnetic resonance; CNMR, carbon nuclear magnetic resonance; MS, mass spectrum; LC/MS (ESI), liquid
chromatography-mass spectrometry (Electrospray ionization).
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