Design, synthesis and biological evaluation of hydroxypyridinone-coumarin hybrids as multimodal monoamine oxidase B inhibitors and iron chelates against Alzheimer's disease

Article abstract of DOI:10.1016/j.ejmech.2019.07.031

A series of hybrids of hydroxypyridinone and coumarin were rationally designed, synthesized and biologically evaluated for their iron ion chelating and MAO-B inhibitory activities. Most of the compounds displayed excellent iron ion chelating effects and moderate to good anti-MAO-B activities. Compound 27a exhibited the most potent activity against MAO-B, with an IC₅₀ value of 14.7 nM. Importantly, 27a showed good U251 cell protective effect and significantly ameliorated the cognitive dysfunction of scopolamine-induced AD mice. Moreover, molecular docking was performed to elucidate the probable ligand-receptor interaction, and the structure-activity relationships were also summarized.

Full text of DOI:10.1016/j.ejmech.2019.07.031

Accepted Manuscript
Design, synthesis and biological evaluation of hydroxypyridinone-coumarin hybrids
as multimodal monoamine oxidase B inhibitors and iron chelates against Alzheimer's
disease
Changjun Zhang, Ke Yang, Sihang Yu, Jing Su, Shengli Yuan, Jiaxin Han, Yan Chen,
Jinping Gu, Tao Zhou, Renren Bai, Yuanyuan Xie
PII:
S0223-5234(19)30652-X
DOI:
https://doi.org/10.1016/j.ejmech.2019.07.031
EJMECH 11528
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 23 June 2019
Revised Date: 9 July 2019
Accepted Date: 9 July 2019
Please cite this article as: C. Zhang, K. Yang, S. Yu, J. Su, S. Yuan, J. Han, Y. Chen, J. Gu, T. Zhou,
R. Bai, Y. Xie, Design, synthesis and biological evaluation of hydroxypyridinone-coumarin hybrids as
multimodal monoamine oxidase B inhibitors and iron chelates against Alzheimer's disease, European
Journal of Medicinal Chemistry (2019), doi: https://doi.org/10.1016/j.ejmech.2019.07.031.
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ACCEPTED MANUSCRIPT
Graphic abstract
Design, synthesis and biological evaluation of hydroxypyridinone-coumarin hybrids as
multimodal monoamine oxidase B inhibitors and iron chelates against Alzheimer's disease
a, #
b, #
c
c
b
b
b
Changjun Zhang , Ke Yang , Sihang Yu , Jing Su , Shengli Yuan , Jiaxin Han , Yan Chen ,
b
d
b, *
a, b, *
Jinping Gu , Tao Zhou , Renren Bai , Yuanyuan Xie
a
Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceutical, Zhejiang
University of Technology, Hangzhou, China
b
College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
c
Department of Pathophysiology, College of Basic Medical Sciences, Jilin University, Changchun,
China
d
School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
These authors contributed equally to this work
#

ACCEPTED MANUSCRIPT
Design, synthesis and biological evaluation of hydroxypyridinone-coumarin
hybrids as multimodal monoamine oxidase B inhibitors and iron chelates against
Alzheimer's disease
a, #
b, #
c
c
b
b
Changjun Zhang , Ke Yang , Sihang Yu , Jing Su , Shengli Yuan , Jiaxin Han ,
b
b
d
b, *
a, b, *
Yan Chen , Jinping Gu , Tao Zhou , Renren Bai , Yuanyuan Xie
a
Collaborative Innovation Center of Yangtze River Delta Region Green
Pharmaceutical, Zhejiang University of Technology, Hangzhou, China
b
College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou,
China
c
Department of Pathophysiology, College of Basic Medical Sciences, Jilin University,
Changchun, China
d
School of Food Science and Biotechnology, Zhejiang Gongshang University,
Hangzhou, China
#
These authors contributed equally to this work
Correspondence:
Dr. Yuanyuan Xie, Key Laboratory for Green Pharmaceutical Technologies and
Related Equipment of Ministry of Education, College of Pharmaceutical Science,
Zhejiang University of Technology, Hangzhou 310014, China. Email:
xyycz@zjut.edu.cn
Dr. Renren Bai, College of Pharmaceutical Science, Zhejiang University of
Technology, Hangzhou 310014, China. Email: renrenbai@zjut.edu.cn

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Abstract
A series of hybrids of hydroxypyridinone and coumarin were rationally designed,
synthesized and biologically evaluated for their iron ion chelating and MAO-B
inhibitory activities. Most of the compounds displayed excellent iron ion chelating
effects and moderate to good anti-MAO-B activities. Compound 27a exhibited the
most potent activity against MAO-B, with an IC value of 14.7 nM. Importantly, 27a
5
0
showed good U251 cell protective effect and significantly ameliorated the cognitive
dysfunction of scopolamine-induced AD mice. Moreover, molecular docking was
performed to elucidate the probable ligand-receptor interaction, and the
structure-activity relationships were also summarized.
Keywords: Alzheimer’s disease; Iron ion chelator; MAO-B inhibitor; Coumarin
derivatives; Hydroxypyridinones
1
. Introduction
Alzheimer’s disease (AD) is a typical progressive neurodegenerative disorder
[
1]
characterized by dementia, cognitive impairment, and memory loss . Although it has
been discovered more than 100 years, the etiology of AD remains ambiguous. The
accumulative formation of β-amyloid (Aβ) deposits, hyper-phosphorylated τ-protein
aggregation, oxidative stress, dyshomeostasis of biometals, and low levels of
[
2-4]
acetylcholine (ACh) are considered to play crucial roles in the pathogenesis of AD
.
To date, the therapeutic options for AD patients were limited within one
N-methyl-D-aspartate (NMDA) receptor antagonist (Memantine) and three
acetylcholinesterase (AChE) inhibitors (Donepezil, Rivastigmine and Galantamine).
However, the therapeutic effects are limited due to the multifactorial and complex
[
5]
nature of AD .
In recent years, monoamine oxidases (MAOs), the important enzymes involved

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in monoamine neurotransmitters metabolism and oxidative stress, have received
[
6, 7]
increasing attention for their potential roles in the treatment of AD
. MAOs are
flavin adenine dinucleotide (FAD)-containing enzymes that are responsible for the
oxidative deamination of various biogenic and dietary amines. MAO-B is one of the
enzymatic isoforms, which accelerates the oxidative deamination of
[
8, 9]
β-phenethylamine and benzylamine
. MAO-B inhibitors are employed to treat
neurodegenerative diseases. For example, safinamide is a well-known MAO-B
[
10]
inhibitor recently approved for Parkinson's therapy
. The oxidative deamination
catalyzed by MAO-B leads to the higher levels of neurotoxic products, such as
hydrogen peroxide and aldehydes, which promote the formation of reactive oxygen
[
11, 12]
species (ROS) and may contribute to neuronal damage
. Studies have shown that
MAO-B expression in neuronal tissues increases 4-fold in the elderly, and its activity
elevated in brains of AD patients increases the rate of neurotransmitters consumption
[
8, 13]
and neuronal damage
. Meanwhile, evidence has shown that MAO-B inhibitors
can significantly improve learning memory deficits in animal models due to the
[14]
inhibition of the oxidative stress in AD . Overall, these observations suggest that
MAO-B inhibitors demonstrate great potential for the treatment of AD.
The dyshomeostasis of brain metal-ion is one of the important hallmarks of AD,
[
15-17]
related to the formation of both amyloid plaques and neurofibrillary tangles
.
Recently, studies found that transition metals, especially for iron and copper ions,
bind to amyloid plaques directly, which suggests that overloaded metal ions in the
neuropil and plaques of the brain closely associated with the formation of Aβ plaques
[
18]
and neurofibrillary tangles
. Additionally, the high concentration of redox-active
metal ions might work as a catalyst involved in the production of reactive oxygen
[
19]
species (ROS), resulting in oxidative stress
. Thus, chelating agents have been
proposed as a potential therapeutic option for the treatment of AD by modulating the
[
20, 21]
level of biometals in the brain
.
On the account of the insufficiency of traditional “one drug, one target” therapy
methods, the multi-target-directed ligand (MTDL) strategy based on the “one
molecule, multiple target” paradigm has been developed by acting on multitarget

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[
5, 22]
simultaneously for the efficient treatment of the multifaceted disease
. In view of
the importance of MAO-B, biometals, and oxidative stress in the treatment of AD,
designing MTDLs with MAO-B inhibition, iron chelation, and antioxidative ability
[
23, 24]
received much attention in recent years
. Previously, we reported the rapid
construction of dual-target anti-Alzheimer’s disease agents with both iron ion
chelating and MAO-B inhibitory activity by click chemistry, and most of the
compounds showed efficient iron ion chelating ability and favorable MAO-B
[
25]
inhibitory activity
. Inspired by these drug design strategies, in this work, we
designed a novel series of hydroxypyridinone-coumarin hybrids as multimodal
monoamine oxidase-B inhibitors and iron chelates against AD.
2
. Results and discussion
2
.1. Design of the hydroxypyridinone-coumarin hybrids
Researchers have demonstrated that coumarin is one of the most privileged
scaffolds of MAO-B, and the structure-activity relationships (SARs) of coumarin
derivatives, especially for 3-phenyl, and 7-benzyloxy substituted derivatives have
[
26-29]
been comprehensively investigated
. Therefore, the planar coumarin scaffold was
chosen and the C-7 of coumarin ring was modified to enhance the anti-MAO-B
[
30-35]
efficacy as well as promote the selectivity over MAO-A
.
Deferiprone is a widely used iron-selective chelator for the treatment of systemic
(III)
iron overload, which can effectively chelate oxidative iron
from the
[15, 36]
iron-overloaded tissues without disturbing the normal cytosolic labile iron pool
.
Coumarin derivatives usually show high lipophilicity, resulting in preferable
membrane penetrating ability, but their water solubility is poor. While
hydroxypyridinone derivatives possess excellent water solubility but display low
[
17]
membrane penetrating ability and bioavailability
. Overall, the rational
combination of hydroxypyridinone and coumarin is a promising strategy for the
treatment of neurodegenerative diseases.
Based on the multitarget directed ligand strategy, a novel molecular framework
was rationally designed by integrating the structures of hydroxypyridin-4-one groups

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with C-7 substituted coumarin derivatives.
(Fig. 1)
2
.2. Chemistry
The synthesis of the novel hybrids 8a-c, 13a-c, and 24-29(a-c) are depicted in
Schemes 1 to 3. Intermediates 3a to 3c were easily prepared from market available
precursors maltol, ethyl maltol, and 5-hydroxy-2-methyl-4H-pyran-4-one,
respectively (Scheme 1). The protection of hydroxyl groups at the pyrone rings of
1
a-c provided the methyl or benzyl protected derivatives 2a-c. Subsequently, the ring
oxygen was substituted by nitrogen via reaction with ammonium hydroxide to obtain
[
37]
the corresponding pyridinone derivatives 3a-c
. Coumarin derivatives were
prepared following the reported methods via reaction of propionic anhydride with
[38]
benzaldehyde 4, 9, and 14 respectively, to afford intermediates 5, 10, and 15 . Then,
the 3-methyl moiety was substituted with the bromomethyl group to give
[
39]
3
-bromomethyl coumarin 6, 11, 16
.
According to Scheme 2 and 3, coumarin-based hybrids 7a-c, 12a-c, 18 a-c, and
3a-c were synthesized by a nucleophilic substitution reaction between the
2
pyridin-4(1H)-one (3a-3c) and 3-bromomethyl coumarin. The desired compounds
a-c and 13a-c were obtained via demethylation of 7a-c, 12a-c by treatment with
8
boron tribromide (BBr ). In terms of compounds 24-29(a-c), the gathered
3
intermediates 17a-c were refluxed in 50% acetone-water solution, subsequently
treated with propargyl bromide or corresponding benzyl bromide in the presence of
potassium carbonate to afford the key intermediate 18-23(a-c). Then the protecting
group of pyridinone moiety was selectively removed to obtain the final compounds.
(Scheme 1)
(Scheme 2)
(Scheme 3)

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(III)
2
.3. Acid dissociation constants and iron affinity constants test of the hybrids
An automated spectrophotometric titration system was applied to test the pK and
a
3
+
[36, 40]
logKeq (Fe ) values
. The determined pK values and affinity constants for
a
(
III)
3+
iron are presented in Table 1. Most of the compounds showed the promising pFe
3
+
chelating effect with pFe values around 18. Compounds 26c and 28a, displayed the
3
+
most potent chelating activity with pFe values of 18.75 and 18.65, respectively,
3
+
superior to that of the reference drug deferiprone (pFe = 17.26). Thus, in general, all
the hybrids inherited the excellent iron chelating ability of the deferiprone
pharmacophore.
(Table 1)
(Scheme 4)
For all of the synthesized compounds, the UV profiles yielded two pK values.
a
The lower pK value (< 3.26) is assigned to the protonation of the 4-oxo group and
a1
the higher pK value in the range of 8.87-9.76 is assigned to the dissociation of 3- (or
a2
[
41]
5
- ) hydroxyl group (Scheme 4)
. Since the acid dissociation constant was
evaluated in a saline system, the detected pKa values indicate the remarkable
enhancement of water solubility of the parent coumarin structure. The UV profile of
2
7a over the pH range of 2.0-10.5 (Fig. 2) yielded two pK values, 3.10 and 9.65,
a
(
III)
respectively. When the titration was proceeded in the presence of iron , over the pH
range of 1.2-8.0, the visible profile was indicative of three species, FeL, FeL , and
2
[
42]
FeL (Fig. 3)
. Resolution of the spectra of these three species led to the
3
determination of the corresponding three affinity constants: logK (14.26), logK
1
2
3
+
(
25.32) and logK (34.25). The pFe value (18.04) was then calculated based on the
3
above three affinity constants. It is obvious that under most physiological conditions,
III
(III)
the dominant species is the neutral Fe L complex, even when the iron and 27a
2
[
41]
concentrations are below the micromolar level . Comparatively, both pK values of
a
the hybrids are lower than the corresponding value of deferiprone, resulting from the
delocalization of the negative charge on 4-oxygen across the ring to the ring nitrogen

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cation (Scheme 4).
(
Fig. 2)
Fig. 3)
(
2
.4. Discussion
The MAO-B inhibitory activities of all the targeted compounds were
preliminarily evaluated at 10 µM and pargyline (a MAO-B inhibitor) was selected as
the reference drug. As shown in Table 2, most of the compounds exhibited significant
MAO-B inhibitory effect at the concentration of 10 µM. Subsequently, compounds
with favorable anti-MAO-B activity (more than 75% inhibition) were submitted to the
following IC50 test (Table 3). As illustrated in Table 2 and 3, although the
hydroxypyridinone moiety was introduced to the parent structure of coumarin, the
obtained hybrids successfully maintained the inhibitory activity against MAO-B, and
there are slight differences among the three chemical series of hydroxypyridinones. In
general, compounds modified at C-7 of the coumarin ring exhibited better MAO-B
inhibitory activities, with IC50 values ranging from submicromolar to lower
nanomolar concentrations. Compound 27a was proved to be the most potent hybrid
displaying the highest MAO-B inhibitory activity (IC = 14.7 nM), which was even
5
0
more efficient than that of pargyline (IC50 = 85.8 nM). Compounds 8a-c were
approximately two-fold less potent than that of the methoxyl (13a-c) and propargyl
(24a-c) substituted hybrids at the side chain of C-7. Moreover, it was obvious that
with the lengthen and the substitution group such as benzyloxy resulted in remarkable
potency enhancement. Additionally, after the introduction of electron-withdrawing
groups (Cl and F) at meta- or para-position of the benzyloxy phenyl ring, the obtained
hybrids exhibited better MAO-B inhibition. Interestingly, compound 13a showed a
lower IC value of 91.9 nM.
5
0
(
Table 2)
Table 3)
(

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2
.5.Molecular modeling
In order to elucidate the probable binding modes, docking simulations were
performed using the CDOCKER program of the Discovery Studio 2016 software. The
X-ray crystal structure of human MAO-B (PDB entry 2v5z) was used acquired from
[43]
the PDB . Based on the in vitro inhibitory results, compounds 13a and 27a were
selected as typical ligands for the evaluation. As shown in Fig. 4, several lipophilic
interactions anchoring the coumarin moiety of the hybrids at the aromatic substrate
cavity of both 13a and 27a, and the hydroxypyridinone moiety was toward the FAD
cofactor. The binding mode showed important interactions between
hydroxypyridinone moiety and residues around it, which indicated that
hydroxypyridinone moiety, not only rendering chelating ability but also worked as a
key fragment in binding with MAO-B. There were two hydrogen bonds between
furan-carbonyl oxygen and the residues GLN 206 and TYR 326. These interactions,
in part, might explain the good inhibitory activity of 13a. In the case of 27a, the
ligand crossed both the entrance and substrate cavities of the enzyme. The C-7
3
-F-benzyloxy of compound 27a occupied the hydrophobic entrance cavity of the
enzyme and interacted with the lipophilic residues ILE 199, ILE 316, LEU 164, PRO
04 and PHE 103. Besides, the fluorine atom established a halogen interaction with
1
residue PRO102. Moreover, the hydroxyl of pyridinone formed a hydrogen bond with
residue GLN 206, and Pi-alkyl interaction was observed between the methyl of
pyridinone and TYR 435 as well as FAD. Those observations might explain the best
activity of the 27a.
(Fig. 4)
2
.6.Cytotoxicity and cytoprotective effects of the compound 27a on U251 cells.
The safety is important for the CNS drugs, so the potential toxic effect of 27a
was investigated on human glioma cell line U251. The cells were exposed to
compound 27a at the concentration of 10 nM, 1 µM, and 100 µM respectively for 24

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[
44, 45]
h and the cell viability was determined by the MTS assay
. As shown in Fig. 5A,
compound 27a showed no cytotoxicity even at the concentration of 100 µM.
Meanwhile, we evaluated the cytoprotective effects of compound 27a on
[
35]
H O -induced cell damage (Fig. 5B)
. Treatment with 100 µM H O for 1 h
2 2
2
2
resulting in over 50% death of U251 cells. When cells pretreated with 27a (100 µM)
for 24 h, the cell viability increased to 57.8 ± 3.9%, close to that of pargyline (100 µM,
6
1.5 ± 4.7%) or vitamin C (100 µM, 57.6 ± 3.5%) pretreated group. These results
indicated that 27a had cytoprotective activity against antagonizing oxidative stress.
(Fig. 5)
2
.7. Behavioral studies
The improvement of cognitive ability is of great importance for the development
of anti-AD agents. Based on the multiple evaluations mentioned above, 27a showed
the best multipotent activity and was selected for in vivo behavioral study by using a
[
46]
Morris water maze test
.
Scopolamine was selected to build the cognition-impaired adult ICR mice animal
-1
model, which was applied for the behavioral evaluation of 27a. Pargyline (10 mg·kg )
was used as a reference drug. 30 min before the intraperitoneal administration of
-1
scopolamine (1 mg·kg ) or blank solution, 27a and pargyline were intraperitoneally
injected to the ICR mice for two consecutive weeks to adapt the apparatus. The test
included 2 days of learning and memory training, followed by a probe trial on the fifth
day. For all of the groups, the data on the fifth day was presented in mean ± SEM and
are shown in Table 4 and Fig. 6.
Compared to the control group, scopolamine led to a remarkable delay of the
#
latency to target (15.3 ± 1.2 seconds vs. 40.2 ± 10.5 seconds, p < 0.05), indicating
that the cognitive impairment mouse model was successfully built. For the pargyline
*
treated group, the latency to target reduced to 5.6 ± 2.0 seconds ( p < 0.05), showing
pargyline could ameliorate the impairment. Compared to the control group, animals
treated with compound 27a resulted in a significant reduction in the latency to target

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(9.6 ± 3.4 seconds, *p < 0.05), which demonstrated that 27a considerably ameliorated
the cognitive impairment of the mice with comparable efficacy to pargyline. From this
observation, we can roughly conclude that 27a could penetrate the blood-brain barrier
(BBB) and target the MAO-B in the central nervous system (CNS).
The distance of the mice motion track to the target (Table 4 and Fig. 6B) and the
the times that mice entered the target quadrant (Table 4 and Fig. 6C) were also
analyzed. Compared to the control group, administration of scopolamine significantly
led to the extended distance of the mice motion track (10.4 ± 1.2 m vs. 5.8 ± 0.7 m,
#
#
p < 0.005). Moreover, the enter target quadrant times were markedly decreased (16.5
###
±
0.8 vs. 9.0 ± 0.8, p < 0.001). Pargyline slightly shortened the distance to target
*
(
6.6 ± 0.6 m, p < 0.05). When treated with compound 27a, the distance to target was
remarkably shortened (4.2 ± 0.6 m, ***p < 0.001). Compared to the control group,
both pargyline and 27a increased the times enter target quadrant of the mice, even
close to a normal level (16.3 ± 1.5, ***p< 0.001, 16.6 ± 0.8, ***p< 0.001,
respectively). These results were also supported by trajectory analysis. As shown in
Fig. 6B, the trajectories of the mice in scopolamine model group was very long and in
a muddle, while 27a and pargyline groups (Fig. 6C and D) displayed a shortened
track (Fig. 6A). Taken together, these results supported that 27a remarkably
ameliorated the cognition impairment caused by scopolamine.
(Table 4)
(Fig. 6)
3
. Conclusion
In summary, a novel series of hydroxypyridinone-coumarin hybrids were
designed and prepared by pharmacophore fusion strategy, acting as
multi-target-directed agents for the treatment of Alzheimer’s disease. The designed
compounds showed promising anti-MAO-B activities and biometal chelating effects
in the in vitro assays. Compound 27a was proved to be the most effective MAO-B
inhibitor (IC50 = 14.7 nM), superior to that of the reference drug pargyline (IC50
=

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8
5.8 nM). The molecular docking analysis demonstrated that 27a could bind to both
the entrance cavity and the substrate cavity of MAO-B. Additionally, compound 27a
displayed cytoprotective activity against oxidative stress and could significantly
ameliorate the cognition impairment in a Morris water maze test model. The present
study indicates that 27a is a promising multifunctional agent with potential anti-AD
activity, and the design of dual MAO-B inhibitor and iron ion chelator is a useful
strategy for the treatment of AD.
4
. Experimental section
4
.1. General information
All starting materials and reference compounds were obtained from commercial
1
13
sources without further purification. The H NMR and C NMR spectra were
recorded on a Bruker BioSpin GmbH spectrometer (Bruker, Germany) at 600 and 150
MHz respectively, where CDCl3 or DMSO-d6 was used as the solvent.
Tetramethylsilane was used as standard and chemical shifts are reported in parts per
million (ppm), coupling constants J are given in Hertz (Hz), and spin multiplicities
are given as singlet (s), broad singlet (br s), doublet (d), doublet of doublets (dd),
doublet of doublets of doublets (ddd), triplet (t), doublet of triplets (dt), quartet (q),
and multiplet (m). Electrospray ionization mass spectrometry (ESI-MS) was
performed on an amazon speed (Bruker, Germany) in positive polarity. Data were
+
listed as mass number ([M+H] ) and relative intensity (%). High-resolution mass
spectra were obtained using a Shimadzu LCMS-IT-TOF mass spectrometer. Melting
points (m.p., uncorrected) were determined on a M-564 Büchi melting point apparatus
(Büchi, Germany). All the reactions were routinely monitored by thin layer
chromatography on silica gel and visualized using UV light (254 nm light source).
4
.2. General procedure for the preparation of compounds 3a-3c.
A mixture of suitable Maltol (7.56 g, 60 mmol), anhydrous K CO (9.12 g, 66
2
3
mmol), benzyl bromide (10.78 g, 63 mmol) and acetone (150 mL) was refluxed for 8
h. Once the reaction was completed, the mixture was cooled to room temperature.

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After the solvent was removed under reduced pressure, water (100 mL) was added
and the mixture was extracted four times with dichloromethane (50 mL). The
combined organic layer was dried over anhydrous sodium sulfate and the solvent was
removed under reduced pressure to afford intermediate 2a as yellow oil. Intermediates
2
b, 2c wasprepared followed the similar procedure of 2a. 2a, 2b or 2c (4.33 g, 40
mmol) was then dissolved in ethanol 45 mL and then 25% ammonia aqueous solution
60 mL) was added, and the mixture was refluxed for 12 h. Afterward, The solvent
(
was evaporated off to obtain a pale brown solid residue, which was recrystallized
from acetone/ ethyl acetate, leaving the pure target compound as a pale colored solid.
1
4
.2.1. 3-Methoxy-2-methylpyridin-4(1H)-one (3a )
1
Yield: 75%, m.p. = 154.8°C, H NMR (600 MHz, Chloroform-d), δ (ppm): 13.50
(s, 1H), 7.52 (d, J = 7.1, 0.9 Hz, 1H), 6.44 (d, J = 7.0, 1.1 Hz, 1H), 3.79 (s, 3H), 2.42
(s, 3H).
2
4
.2.2. 3-(Benzyloxy)-2-methylpyridin-4(1H)-one (3a )
1
Yield: 82%, m.p. = 123.1°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 13.38
(s, 1H), 7.42 (d, J = 7.0 Hz, 1H), 7.31 - 7.26 (m, 5H), 6.37 (d, J = 6.9 Hz, 1H), 5.03 (s,
2
4
H), 2.16 (s, 3H).
1
.2.3. 2-Ethyl-3-methoxypyridin-4(1H)-one (3b )
1
Yield: 73%, m.p. = 148.5°C. H NMR (500 MHz, Chloroform-d), δ (ppm): 13.28
(s, 1H), 7.44 (d, J = 7.0 Hz, 1H), 6.36 (d, J = 6.8 Hz, 1H), 5.09 (s, 2H), 2.69 (q, J =
7
.2 Hz, 2H), 1.12 (t, J = 7.5 Hz, 3H).
2
4
.2.4. 3-(Benzyloxy)-2-ethylpyridin-4(1H)-one (3b )
1
Yield: 76%, m.p. = 140.7°C. H NMR (500 MHz, Chloroform-d), δ (ppm): 13.20
(s, 1H), 7.44 (d, J = 7.0 Hz, 1H), 7.26 (m, 5H), 6.36 (d, J = 6.8 Hz, 1H), 5.09 (s, 2H),
2
.60 (q, J = 7.5 Hz, 2H), 1.08 (t, J = 7.5 Hz, 3H).
1
4
.2.5. 5-Methoxy-2-methylpyridin-4(1H)-one (3c )
1
Yield: 76%, m.p. = 96.7°C. H NMR (600 MHz, DMSO-d6), δ (ppm): 11.29 (s,
1
4
H), 7.28 (s, 1H), 5.98 (s, 1H), 3.63 (s, 3H), 2.17 (s, 3H).
2
.2.6. 5-(Benzyloxy)-2-methylpyridin-4(1H)-one (3c )
1
Yield: 80%, m.p. = 184.3°C. H NMR (400 MHz, DMSO-d ), δ (ppm): 11.21 (s,
6

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1
H), 7.9-7.31 (m, 6H), 6.00 (s, 1H), 4.97 (s, 2H), 2.16 (s, 3H).
4
.3. General procedure for the preparation of compounds 5, 10 and 15.
A 250 mL round-bottom flask was charged with appropriate salicylaldehyde (60
mmoL), propionic anhydride (23.43 g, 180 mmoL) and sodium propionate (11.53 g,
20 mmoL). Triethylamine (6.07 g, 60 mmoL) was then added, and the recation
1
mixture was refluxed for 10 h. The resulting brown mixture was recrystallized from
ethyl acetate (50 mL) afforded a white solid which subsequently was washed by water,
obtaining a white product.
4
.3.1. 3-Methyl-2H-chromen-2-one (5)
1
Yield: 48%, m.p. = 116.5°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.50
(s, 1H), 7.44 (td, J = 7.3, 1.3 Hz, 1H), 7.40 (dd, J = 7.7, 1.6 Hz, 1H), 7.29 (d, J = 8.3
Hz, 1H), 7.24 (td, 1H), 2.20 (s, 3H).
4
.3.2. 7-Methoxy-3-methyl-2H-chromen-2-one (10)
1
Yield: 45%, m.p. = 117.8°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45
(s, 1H), 7.30 (d, J = 8.3 Hz, 1H), 6.83 - 6.80 (m, 2H), 3.86 (s, 3H), 2.17 (s, 3H).
4
.3.3. 3-Methyl-2-oxo-2H-chromen-7-yl propionate (15)
1
Yield: 56%, m.p. = 127.3°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.52 -
7
.48 (m, 1H), 7.41 (d, J = 8.4 Hz, 1H), 7.09 (d, J = 2.2 Hz, 1H), 7.01 (dd, J = 8.4, 2.2
Hz, 1H), 2.62 (q, J = 7.5 Hz, 2H), 2.21 (d, J = 1.4 Hz, 3H), 1.28 (t, J = 7.5 Hz, 3H).
4
.4. General procedure for the preparation of compounds 6, 11 and 16.
To a solution of compound 5 (4.65 g, 20 mmol) in 40 mL of CCl was added
4
NBS (3.74 g, 21 mmol) and a trace amount of BPO (0.1 g), and the mixture was
allowed to refluxed for 12 h. After the reaction, 40 mL dichloromethane was added,
and the mixture was washed five times with water (60 mL), and the organic layer was
dried by anhydrous sodium sulfate. Subsequently, The solvent was evaporated off to
afford white colored solid, which was re-crystallized from ethyl acetate/ petroleum,
leaving the pure desired product.
4
.4.1. 3-(Bromomethyl)-2H-chromen-2-one (6)

ACCEPTED MANUSCRIPT
1
Yield: 75%, m.p. = 120°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.86 (s,
1
H), 7.55 (td, 1H), 7.51 (dd, J = 7.8, 1.6 Hz, 1H), 7.35 (dd, J = 7.8, 0.6 Hz, 1H), 7.31
13
(
td, J = 7.5, 1.0 Hz, 1H), 4.44 (s, 2H). C NMR (150 MHz, CDCl ), δ (ppm): 161.46,
3
1
53.36, 138.76, 131.53, 128.01, 124.79, 119.22, 116.78, 61.27, 29.84.
4
.4.2. 3-(Bromomethyl)-7-methoxy-2H-chromen-2-one (11)
1
Yield: 52%, m.p. = 133.0°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.79
(s, 1H), 7.39 (d, J = 8.6 Hz, 1H), 6.86 (dd, J = 8.6, 2.4 Hz, 1H), 6.82 (d, J = 2.4 Hz,
1
3
1
1
4
H), 4.42 (s, 2H), 3.88 (s, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 163.32, 160.39,
3
55.82, 142.31, 129.17, 121.87, 113.17, 112.62, 100.79, 55.99, 28.30.
.4.3. 3-(Bromomethyl)-2-oxo-2H-chromen-7-yl propionate (16)
1
Yield: 95%, m.p. = 118.3°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.84
(s, 1H), 7.50 (d, J = 8.5 Hz, 1H), 7.13 (d, J = 2.2 Hz, 1H), 7.07 (dd, J = 8.5, 2.2 Hz,
1
3
1
H), 4.42 (s, 2H), 2.63 (q, J = 7.6 Hz, 2H), 1.28 (t, J = 15.1 Hz, 3H). C NMR (100
MHz, CDCl ), δ (ppm): 172.19, 159.64, 154.34, 153.55, 141.45, 128.79, 124.82,
3
1
18.82, 116.59, 110.28, 27.75, 27.56, 8.92.
4
.5. General procedure for the preparation of compounds 7a-c, 12a-c, 17a-c.
1
A mixture of 6 (239 mg, 1.5 mmol), 3a (139 mg, 1.0 mmol), anhydrous
potassium carbonate (207 mg, 1.5 mmol), and acetonitrile (15 mL) was refluxed for 6
h, and the progress of the reaction was monitored by TLC (eluent: dichloromethane/
methanol = 15: 1 solvent mixture). The reaction mixture was concentrated under
reduce pressure to afford yellow solid residue, which was purified by chromatography
on silica gel to obtain the desired compound.
4
.5.1. 3-(Methyloxy)-2-methyl-1-((2-oxo-2H-chromen-3-yl) methyl)
pyridin-4(1H)-one (7a)
1
Yield: 55%, m.p. = 192.0°C. H NMR (600 MHz, DMSO-d ), δ (ppm): 7.76 (dd,
6
J = 7.8, 1.5 Hz, 1H), 7.69 (d, J = 7.6 Hz, 1H), 7.61 (ddd, J = 8.5, 7.4, 1.6 Hz, 1H),
.48 (s, 1H), 7.43 (d, J = 8.3 Hz, 1H), 7.34 (td, J = 7.5, 1.0 Hz, 1H), 6.19 (d, J = 7.5
7
1
3
Hz, 1H), 5.02 (d, J = 1.5 Hz, 2H), 3.71 (s, 3H), 2.27 (s, 3H). C NMR (150 MHz,
DMSO), δ (ppm): 172.08, 159.45, 152.68, 146.94, 140.73, 140.04, 138.83, 131.90,
1
28.68, 124.68, 124.35, 118.64, 116.37, 116.03, 58.55, 51.69, 11.76. HRMS m/z: calc.

ACCEPTED MANUSCRIPT
+
for C H NO Na [M+Na] , 320.0893, found 320.0903.
1
7
15
4
4
.5.2. 3-(Methyloxy)-2-ethyl-1-((2-oxo-2H-chromen-3-yl) methyl)
pyridin-4(1H)-one (7b)
1
Yield: 33%, m.p. = 193.1°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.56
(ddd, J = 8.6, 7.3, 1.6 Hz, 1H), 7.44 (dd, J = 7.7, 1.5 Hz, 1H), 7.36 (d, J = 8.3 Hz, 1H),
7
.31 (td, J = 7.5, 1.1 Hz, 2H), 7.03 (d, J = 1.7 Hz, 1H), 6.52 (d, J = 7.5 Hz, 1H), 4.96
1
3
(
d, J = 1.6 Hz, 2H), 3.96 (s, 3H), 2.68 (t, J = 7.5 Hz, 2H), 1.22 (t, J = 7.5 Hz, 3H). C
NMR (150 MHz, CDCl ), δ (ppm): 173.85, 159.88, 153.26, 147.99, 145.67, 139.03,
3
1
1
4
38.76, 132.54, 128.37, 125.22, 124.40, 118.39, 118.36, 116.83, 60.01, 51.85, 19.97,
+
4.03. HRMS m/z: calc. for C H NO [M+H] , 312.1230, found 312.1217.
1
8
18
4
.5.3. 5-(Methyloxy)-2-methyl-1-((2-oxo-2H-chromen-3-yl) methyl)
pyridin-4(1H)-one (7c)
1
Yield: 52%, m.p. = 257.1°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.57
(ddd, J = 8.7, 7.4, 1.6 Hz, 1H), 7.46 (dd, J = 7.8, 1.6 Hz, 1H), 7.36 (d, J = 8.3 Hz, 1H),
7
.32 (td, J = 7.5, 1.1 Hz, 1H), 7.06 (d, J = 1.6 Hz, 1H), 7.01 (s, 1H), 6.39 (s, 1H), 4.93
13
(
d, J = 1.7 Hz, 2H), 3.78 (s, 3H), 2.27 (s, 3H). C NMR (150 MHz, CDCl ), δ (ppm):
3
1
1
2
4
72.91, 159.96, 153.27, 150.14, 145.51, 138.71, 132.57, 128.38, 125.24, 123.77,
+
22.61, 118.39, 117.52, 56.47, 52.18, 19.16. HRMS m/z: calc. for C H NO [M+H] ,
17
16
4
98.1070, found 298.1074.
.5.4. 3-(Methyloxy)-1-((7-methoxy-2-oxo-2H-chromen-3-yl)methyl)-2-methylpyrid
in-4(1H)-one (12a)
1
Yield: 48%, m.p. = 174.0°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.33 (dd,
J = 8.1, 5.8 Hz, 2H), 7.03 (d, J = 1.6 Hz, 1H), 6.87 (dd, J = 8.7, 2.4 Hz, 1H), 6.83 (d,
J = 2.4 Hz, 1H), 6.49 (d, J = 7.5 Hz, 1H), 4.91 (d, J = 1.5 Hz, 2H), 3.89 (s, 3H), 3.87
1
3
(
s, 3H), 2.33 (s, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.72, 163.45, 160.31,
3
1
1
3
4
55.22, 148.38, 140.60, 139.11, 139.04, 129.31, 119.85, 118.07, 113.32, 112.02,
+
00.88, 59.76, 56.03, 52.41, 12.40. HRMS m/z: calc. for C H NO [M+H] ,
1
8
18
5
28.1179, found 328.1182.
.5.5. 3-(Methyloxy)-2-ethyl-1-((7-methoxy-2-oxo-2H-chromen-3-yl)methyl)pyridin
4(1H)-one(12b)
-

ACCEPTED MANUSCRIPT
1
Yield: 49%, m.p. = 177.4°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.34 (d,
J = 8.7 Hz, 2H), 7.06 (s, 1H), 6.87 (dd, J = 8.7, 2.4 Hz, 1H), 6.82 (d, J = 2.4 Hz, 1H),
6
.53 (d, J = 7.5 Hz, 1H), 4.94 (d, J = 1.5 Hz, 2H), 3.96 (s, 3H), 3.87 (s, 3H), 2.70 (q, J
1
3
=
7.5 Hz, 2H), 1.22 (t, J = 7.5 Hz, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.60,
3
1
63.44, 160.32, 155.19, 147.84, 146.07, 139.28, 139.16, 129.40, 120.24, 118.10,
113.29, 112.04, 100.87, 60.05, 56.02, 51.88, 19.98, 14.00. HRMS m/z: calc. for
+
C H NO [M+H] , 342.1336, found 342.1347.
19
20
5
4
.5.6. 5-(Methyloxy)-1-((7-methoxy-2-oxo-2H-chromen-3-yl)methyl)-2-methylpyrid
in-4(1H)-one (12c)
1
Yield: 72%, m.p. = 195.3°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.37 (d,
J = 8.6 Hz, 1H), 7.14 (s, 1H), 7.11 (s, 1H), 6.88 (dd, J = 8.7, 2.4 Hz, 1H), 6.83 (d, J =
2
3
1
5
4
.4 Hz, 1H), 6.43 (s, 1H), 4.94 (d, J = 1.4 Hz, 2H), 3.88 (s, 3H), 3.79 (s, 3H), 2.31 (s,
1
3
H). C NMR (150 MHz, CDCl ), δ (ppm): 172.26, 163.50, 160.46, 155.29, 149.85,
3
45.83, 139.57, 129.44, 123.08, 119.60, 117.30, 113.32, 112.06, 100.89, 56.63, 56.04,
+
2.31, 19.33. HRMS m/z: calc. for C H NO [M+H] , 328.1179, found 328.1167.
1
8
18
5
.5.7. 3-((3-(Benzyloxy)-2-methyl-4-oxopyridin-1(4H)-yl)methyl)-2-oxo-2H-chrom
en-7-yl propionate (17a)
1
Yield: 54%, m.p. = 196.1°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.43 -
7
.37 (m, 4H), 7.33 - 7.21 (m, 3H), 7.14 (d, J = 2.2 Hz, 1H), 7.08 (dd, J = 8.5, 2.2 Hz,
H), 6.88 (s, 1H), 6.53 (d, J = 7.5 Hz, 1H), 5.27 (s, 2H), 4.86 (d, J = 1.6 Hz, 2H), 2.63
1
1
3
(
q, J = 7.5 Hz, 2H), 2.05 (s, 3H), 1.27 (t, J = 7.5 Hz, 3H). C NMR (125 MHz,
Chloroform-d), δ (ppm): 173.68, 172.26, 159.52, 153.80, 153.78, 146.28, 141.10,
39.04, 138.11, 137.39, 129.34, 129.03, 128.41, 128.28, 123.12, 119.14, 118.01,
16.05, 110.40, 73.12, 52.43, 27.84, 12.64, 9.00. HRMS m/z: calc. for C H NO
6
1
1
26
24
+
[
M+H] , 446.1598, found 446.1590.
4
.5.8. 3-((3-(Benzyloxy)-2-ethyl-4-oxopyridin-1(4H)-yl)methyl)-2-oxo-2H-chromen
7-yl propionate (17b)
-
1
Yield: 47%, m.p. = 199.3°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45 -
.41 (m, 2H), 7.39 (d, J = 8.5 Hz, 1H), 7.31 (dd, J = 8.1, 6.6 Hz, 2H), 7.29 - 7.26 (m,
H), 7.14 (d, J = 2.2 Hz, 1H), 7.07 (dd, J = 8.5, 2.2 Hz, 1H), 6.83 (s, 1H), 6.53 (d, J =
7
2

ACCEPTED MANUSCRIPT
7
.5 Hz, 1H), 5.34 (s, 2H), 4.89 (d, J = 1.7 Hz, 2H), 2.63 (q, J = 7.5 Hz, 2H), 2.50 (q, J
1
3
=
7.5 Hz, 2H), 1.27 (t, J = 7.5 Hz, 3H), 1.02 (t, J = 7.5 Hz, 3H). C NMR (150 MHz,
CDCl ), δ (ppm): 173.94, 172.27, 159.52, 153.74, 146.02, 145.90, 139.25, 139.06,
3
1
39.02, 137.92, 137.61, 129.04, 128.43, 128.20, 123.71, 119.15, 118.26, 116.04,
10.39, 72.93, 51.86, 27.84, 19.94, 13.56, 9.00. HRMS m/z: calc. for C H NO
6
1
27
26
+
[
M+H] , 460.1755, found 460.1748.
4
.5.9. 3-((5-(Benzyloxy)-2-methyl-4-oxopyridin-1(4H)-yl)methyl)-2-oxo-2H-chrom
en-7-yl propionate (17c)
1
Yield: 47%, m.p. = 104.9°C. H NMR (400 MHz, Chloroform-d), δ (ppm): 7.39 (d,
J = 8.5 Hz, 1H), 7.34 (d, J = 6.9 Hz, 2H), 7.22 (t, J = 7.4 Hz, 2H), 7.18 - 7.09 (m, 2H),
7
4
3
1
.07 (dd, J = 8.5, 2.2 Hz, 1H), 7.00 (s, 1H), 6.92 (s, 1H), 6.41 (s, 1H), 5.14 (s, 2H),
.80 (d, J = 1.5 Hz, 2H), 2.63 (q, J = 7.5 Hz, 2H), 2.23 (s, 3H), 1.27 (t, J = 7.5 Hz,
1
3
H). C NMR (100 MHz, CDCl ), δ (ppm): 173.40, 172.23, 159.51, 153.73, 153.67,
3
47.69, 145.52, 138.45, 136.30, 129.13, 128.49, 128.13, 127.88, 127.33, 122.67,
119.01, 118.41, 115.96, 110.26, 71.48, 51.64, 27.74, 19.02, 8.90. HRMS m/z: calc. for
+
C H NO [M+H] , 446.1595, found 446.1593.
26
24
6
4
.6.General procedure for the preparation of compounds 18a-c, 19a-c, 20a-c,
1a-c, 22a-c, 23a-c.
K CO (415 mg, 3 mmol) was added to the solution of 17a (445 mg, 1 mmol) in 8
2
2
3
mL 50% acetone-water. The mixture was refluxed for 30 min. subsequently, propargyl
bromide or corresponding substituted benzyl bromide (1.5 eq) was added, and then
the mixture was refluxed for another 6h. The solvent was removed under reduce
pressure to obtain yellow solid residue, which was purified by chromatography on
silica gel to obtain the corresponding compounds.
4
.6.1. 3-(Benzyloxy)-2-methyl-1-((2-oxo-7-(prop-2-yn-1-yloxy)-2H-chromen-3-yl)
methyl)pyridin-4(1H)-one (18a)
1
Yield: 55%, m.p. = 155.4°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.40 (d,
J = 1.6 Hz, 1H), 7.39 - 7.36 (m, 2H), 7.35 - 7.33 (m, 1H), 7.31 - 7.26 (m, 1H), 7.25 (d,
J = 8.9 Hz, 1H), 6.94 (m, 2H), 6.57 (d, J = 7.4 Hz, 1H), 5.26 (s, 2H), 4.90 - 4.84 (m,
13
2
H), 4.76 (d, J = 2.4 Hz, 2H), 2.58 (t, J = 2.4 Hz, 1H), 2.16 (s, 2H), 2.08 (s, 3H). C

ACCEPTED MANUSCRIPT
NMR (150 MHz, CDCl ), δ (ppm): 173.37, 161.09, 160.10, 154.90, 146.18, 141.47,
3
1
1
39.14, 139.00, 137.39, 129.32, 128.42, 128.27, 120.41, 117.78, 113.75, 112.66,
02.16, 77.25, 76.90, 73.20, 56.43, 52.53, 31.06, 12.70. HRMS m/z: calc. for
+
C H NO [M+H] , 428.1492, found 428.1484.
26
22
5
4
.6.2. 3-(Benzyloxy)-2-ethyl-1-((2-oxo-7-(prop-2-yn-1-yloxy)-2H-chromen-3-yl)met
hyl)pyridin-4(1H)-one (18b)
1
Yield: 48%, m.p. = 155.4°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45 (d,
J = 1.7 Hz, 1H), 7.44 (d, J = 1.1 Hz, 1H), 7.35 - 7.24 (m, 6H), 6.96 (d, J = 2.1 Hz, 1H),
6
.85 (s, 1H), 6.58 (d, J = 7.5 Hz, 1H), 5.35 (s, 2H), 4.89 (s, 2H), 4.77 (d, J = 2.4 Hz,
13
2
H), 2.58 (t, J = 2.4 Hz, 1H), 2.53 (q, J = 7.6 Hz, 2H), 1.03 (t, J = 7.5 Hz, 3H). C
NMR (100 MHz, DMSO), δ (ppm): 169.18, 156.15, 155.22, 149.92, 141.19, 141.03,
1
1
34.22, 133.60, 132.83, 124.48, 124.16, 123.57, 123.31, 116.29, 113.37, 108.83,
07.81, 97.27, 72.42, 72.06, 68.04, 51.56, 46.96, 15.05, 8.70. HRMS m/z: calc. for
+
C H NO [M+H] , 442.1654, found 442.1650.
27
24
5
4
.6.3. 5-(Benzyloxy)-2-methyl-1-((2-oxo-7-(prop-2-yn-1-yloxy)-2H-chromen-3-yl)
methyl)pyridin-4(1H)-one (18c)
1
Yield: 46%, m.p. = 121.2°C. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.36 (d,
J = 1.5 Hz, 1H), 7.35 (d, 1H), 7.30 (d, J = 9.3 Hz, 1H), 7.25 - 7.21 (m, 2H), 7.17 -
.13 (m, 1H), 6.96 - 6.92 (m, 3H), 6.86 (s, 1H), 6.39 - 6.37 (m, 1H), 5.16 (s, 2H), 4.77
7
1
3
(
d, J = 2.4 Hz, 2H), 4.75 (d, J = 1.5 Hz, 2H), 2.58 (t, J = 2.4 Hz, 1H), 2.23 (s, 3H). C
NMR (100 MHz, CDCl ), δ (ppm): 173.35, 160.98, 160.05, 154.81, 147.61, 145.48,
3
1
39.00, 136.44, 129.37, 128.48, 128.08, 127.94, 127.69, 120.10, 118.51, 113.59,
112.53, 102.01, 77.15, 76.80, 71.61, 56.32, 51.64, 19.04. HRMS m/z: calc. for
+
C H NO [M+H] , 428.1492, found 428.1486.
26
22
5
4
.6.4. 3-(Benzyloxy)-1-((7-(benzyloxy)-2-oxo-2H-chromen-3-yl)methyl)-2-methylp
yridin-4(1H)-one (19a)
1
Yield: 70%, yellow oil. H NMR (500 MHz, Chloroform-d), δ (ppm): 7.43 - 7.35
(m, 7H), 7.35 - 7.26 (m, 3H), 7.26 - 7.20 (m, 3H), 6.93 (dd, J = 8.7, 2.4 Hz, 1H), 6.84
(d, J = 2.4 Hz, 1H), 6.46 (d, J = 7.5 Hz, 1H), 5.23 (s, 2H), 5.10 (s, 2H), 4.79 (d, J =
1
3
1
.5 Hz, 2H), 2.03 (s, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.54, 162.14,
3

ACCEPTED MANUSCRIPT
1
1
7
4
4
59.99, 154.85, 146.08, 140.93, 139.07, 138.80, 137.34, 135.52, 129.19, 129.07,
28.71, 128.38, 128.19, 128.01, 127.43, 119.91, 117.63, 113.62, 112.11, 101.68, 72.87,
+
0.54, 52.17, 12.42. HRMS m/z: calc. for C H NO [M+H] , 480.1805, found
30
26
5
80.1808.
.6.5. 3-(Benzyloxy)-1-((7-(benzyloxy)-2-oxo-2H-chromen-3-yl)methyl)-2-ethylpyri
din-4(1H)-one (19b)
1
Yield: 37%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45 (d, J =
1
.6 Hz, 1H), 7.44 (s, 1H), 7.44 - 7.40 (m, 3H), 7.40 (d, J = 0.9 Hz, 1H), 7.41 - 7.25 (m,
H), 6.95 (dd, J = 8.7, 2.4 Hz, 1H), 6.89 (d, J = 2.4 Hz, 1H), 6.82 (s, 1H), 6.55 (d, J =
.4 Hz, 1H), 5.35 (s, 2H), 5.14 (s, 2H), 4.89 - 4.85 (m, 2H), 2.52 (q, J = 7.5 Hz, 2H),
6
7
1
3
1
.03 (t, J = 7.5 Hz, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.86, 162.40,
3
1
60.21, 155.02, 146.04, 139.03, 138.69, 137.70, 135.63, 129.33, 129.04, 128.93,
28.84, 128.62, 128.44, 128.18, 127.62, 120.60, 118.18, 113.92, 112.21, 101.94,
1
+
7
2.99, 70.77, 51.90, 19.95, 13.55. HRMS m/z: calc. for C H NO [M+H] , 494.1962,
3
1
28
5
found 494.1951.
4
.6.6. 5-(Benzyloxy)-1-((7-(benzyloxy)-2-oxo-2H-chromen-3-yl)methyl)-2-methylp
yridin-4(1H)-one (19c)
1
Yield: 40%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.44 - 7.27
(m, 9H), 7.22 (t, J = 7.7 Hz, 2H), 7.03 (s, 1H), 6.97 - 6.92 (m, 2H), 6.88 (d, J = 2.4 Hz,
1
3
1
H), 6.42 (s, 1H), 5.17 (s, 2H), 5.14 (s, 2H), 4.78 (s, 2H), 2.25 (s, 3H). C NMR (150
MHz, CDCl ), δ (ppm): 173.11, 162.42, 160.29, 155.13, 147.59, 145.71, 139.53,
3
1
36.50, 135.61, 129.49, 128.92, 128.61, 128.56, 128.17, 128.03, 127.91, 127.60,
119.61, 118.45, 113.87, 112.19, 101.88, 71.73, 70.75, 51.81, 19.17. HRMS m/z: calc.
+
for C H NO [M+H] , 480.1805, found 480.1804.
3
0
26
5
4
.6.7. 3-(Benzyloxy)-1-((7-((3-chlorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-
2-methylpyridin-4(1H)-one (20a)
1
Yield: 38%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.42 (d, J =
.1 Hz, 1H), 7.40 (d, J = 1.7 Hz, 1H), 7.39 - 7.38 (m, 1H), 7.37 - 7.22 (m, 8H), 6.94
2
(dd, J = 8.7, 2.4 Hz, 1H), 6.91 (s, 1H), 6.86 (d, J = 2.4 Hz, 1H), 6.54 (d, J = 7.4 Hz,
1
3
1
H), 5.26 (s, 2H), 5.10 (s, 2H), 4.85 (s, 2H), 2.07 (s, 3H). C NMR (150 MHz,

ACCEPTED MANUSCRIPT
CDCl ), δ (ppm): 173.41, 162.00, 160.13, 155.02, 146.16, 141.44, 139.15, 139.01,
3
1
1
37.67, 137.37, 134.86, 130.20, 129.45, 129.31, 128.71, 128.40, 128.25, 127.52,
25.48, 120.15, 117.77, 113.78, 112.40, 101.88, 73.18, 69.80, 52.49, 12.69. HRMS
+
m/z: calc. for C H ClNO [M+H] , 514.1416, found 514.1423.
3
0
25
5
4
.6.8. 3-(Benzyloxy)-1-((7-((3-chlorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-
2-ethylpyridin-4(1H)-one (20b)
1
Yield: 43%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45 (d, 1H),
.44 (d, J = 1.8 Hz, 1H), 7.37 (td, J = 8.0, 5.8 Hz, 1H), 7.34 - 7.25 (m, 5H), 7.20 -
.17 (m, 1H), 7.13 (dt, J = 9.5, 2.1 Hz, 1H), 7.04 (td, J = 8.5, 2.9 Hz, 1H), 6.94 (dd, J
7
7
=
8.7, 2.4 Hz, 1H), 6.87 (d, J = 2.4 Hz, 1H), 6.83 (d, J = 2.4 Hz, 1H), 6.54 (d, J = 7.3
Hz, 1H), 5.34 (s, 2H), 5.13 (s, 2H), 4.87 (s, 2H), 2.52 (q, J = 7.4 Hz, 2H), 1.03 (t, J =
1
3
7
.5 Hz, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.78, 163.84, 161.91, 160.01,
3
1
54.86, 145.89, 138.91, 138.49, 138.11, 137.58, 130.45, 130.39, 129.30, 128.91,
28.32, 128.06, 122.74, 115.44, 115.30, 114.32, 114.17, 113.69, 112.28, 101.82, 72.86,
1
+
6
9.74, 51.76, 19.83, 13.43. HRMS m/z: calc. for C H ClNO [M+H] , 528.15726,
31
27
5
found 528.1587.
4
.6.9. 5-(Benzyloxy)-1-((7-((3-chlorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-
2-methylpyridin-4(1H)-one (20c)
1
Yield: 42%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.43 (d, J =
.1 Hz, 1H), 7.38 - 7.27 (m, 6H), 7.22 (t, J = 7.5 Hz, 2H), 7.13 (t, J = 7.4 Hz, 1H),
.06 (s, 1H), 6.99 (s, 1H), 6.95 (dd, J = 8.7, 2.4 Hz, 1H), 6.86 (d, J = 2.4 Hz, 1H),
2
7
6
1
3
.45 (s, 1H), 5.17 (s, 2H), 5.12 (s, 2H), 4.81 (s, 2H), 2.27 (s, 3H). C NMR (150
MHz, CDCl ), δ (ppm): 172.93, 162.06, 160.24, 155.13, 147.55, 145.82, 139.63,
3
1
1
37.68, 136.46, 134.90, 130.22, 129.64, 128.75, 128.58, 128.19, 128.04, 127.98,
27.54, 125.49, 119.81, 118.39, 113.77, 112.41, 101.89, 71.76, 69.83, 51.87, 19.22.
+
HRMS m/z: calc. for C H ClNO [M+H] , 514.1416, found 514.1409.
3
0
25
5
4
.6.10. 3-(Benzyloxy)-1-((7-((3-fluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-2
-methylpyridin-4(1H)-one (21a)
1
Yield: 71%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.42 - 7.39
(m, 2H), 7.38 - 7.34 (m, 1H), 7.33 - 7.22 (m, 5H), 7.20 - 7.17 (m, 1H), 7.13 (dt, J =

ACCEPTED MANUSCRIPT
9
.4, 2.1 Hz, 1H), 7.04 (td, J = 8.5, 2.6, 0.9 Hz, 1H), 6.94 (dd, J = 8.7, 2.4 Hz, 1H),
.86 (t, J = 2.3 Hz, 2H), 6.51 (d, J = 7.5 Hz, 1H), 5.27 (s, 2H), 5.13 (s, 2H), 4.83 (d, J
6
1
3
=
1.5 Hz, 2H), 2.05 (s, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.65, 163.12 (d,
3
1
JC-F = 244.5Hz), 162.03, 160.11, 155.01, 146.27, 141.11, 139.02, 138.74, 138.18 (d,
3
3
JC-F = 7.5 Hz), 137.46, 130.54 (d, JC-F = 7.5 Hz), 129.39, 129.33, 128.40, 128.23,
4
2
2
1
22.87 (d, J = 3.0Hz), 120.26, 117.95, 115.48 (d, J = 22.5Hz), 114.36 (d, J
C-F C-F C-F
=
22.5Hz), 113.81, 112.38, 101.92, 73.11, 69.85, 52.42, 12.64. HRMS m/z: calc. for
+
C H FNO [M+H] , 498.1711, found 498.1711.
30
25
5
4
.6.11. 3-(Benzyloxy)-2-ethyl-1-((7-((3-fluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)m
ethyl)pyridin-4(1H)-one (21b)
1
Yield: 48%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45 (d, 1H),
7
.44 (d, J = 1.8 Hz, 1H), 7.37 (td, J = 8.0, 5.8 Hz, 1H), 7.34 - 7.25 (m, 5H), 7.20 -
.17 (m, 1H), 7.13 (dt, J = 9.5, 2.1 Hz, 1H), 7.04 (td, J = 8.5, 2.9 Hz, 1H), 6.94 (dd, J
7
=
8.7, 2.4 Hz, 1H), 6.87 (d, J = 2.4 Hz, 1H), 6.83 (d, J = 2.4 Hz, 1H), 6.54 (d, J = 7.3
Hz, 1H), 5.34 (s, 2H), 5.13 (s, 2H), 4.87 (s, 2H), 2.52 (q, J = 7.4 Hz, 2H), 1.03 (t, J =
13
1
7
.5 Hz, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.78, 163.02(d, J = 246.0
3 C-F
3
Hz), 161.91, 160.01, 154.86, 145.91, 138.91, 138.49, 138.08(d, JC-F = 7.5 Hz),
3
1
37.58, 130.42(d, J = 7.5 Hz), 129.30, 128.92, 128.32, 128.24, 128.06, 122.75(d,
C-F
4
2
2
JC-F = 3.0 Hz), 120.73,118.09, 115.37(d, J = 21.0 Hz), 114.24(d, J = 22.5 Hz),
C-F
C-F
113.69, 112.28, 101.82, 72.86, 69.73, 51.76, 19.83, 13.43. HRMS m/z: calc. for
+
C H FNO [M+H] , 512.1868, found 512.1845.
31
27
5
4
.6.12. 5-(Benzyloxy)-1-((7-((3-fluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-2
-methylpyridin-4(1H)-one (21c)
1
Yield: 38%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.39 - 7.33
(m, 3H), 7.31 (d, J = 8.6 Hz, 1H), 7.22 (t, J = 7.6 Hz, 2H), 7.20 - 7.18 (m, 1H), 7.16 -
7
.10 (m, 2H), 7.08 - 7.01 (m, 2H), 6.99 (s, 1H), 6.95 (dd, J = 8.7, 2.4 Hz, 1H), 6.86 (d,
1
3
J = 2.4 Hz, 1H), 6.45 (s, 1H), 5.17 (s, 2H), 5.14 (s, 2H), 4.81 (s, 2H), 2.27 (s, 3H). C
1
NMR (150 MHz, CDCl ), δ (ppm): 172.86, 163.14(d, J
= 246.0 Hz), 162.09,
3
C-F
3
1
60.24, 155.13, 147.53, 145.83, 139.68, 138.20(d, JC-F = 7.5 Hz), 136.46, 130.55(d,
3
4
JC-F = 9.0 Hz), 129.63, 128.57, 128.18, 128.05, 128.02, 122.87(d, J = 3.0 Hz),
C-F

ACCEPTED MANUSCRIPT
2
2
1
19.78, 118.38, 115.50(d, J = 21.0 Hz), 114.36(d, J = 22.5 Hz), 113.79, 112.40,
C-F C-F
+
1
4
4
01.90, 71.77, 69.86, 51.88, 19.21. HRMS m/z: calc. for C H FNO [M+H] ,
30 25 5
98.1711, found 498.1712.
.6.13. 3-(Benzyloxy)-1-((7-((4-fluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-2
-methylpyridin-4(1H)-one (22a)
1
Yield: 39%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.42 - 7.38
(m, 5H), 7.32 (d, J = 8.7 Hz, 1H), 7.30 - 7.23 (m, 3H), 7.11 - 7.06 (m, 2H), 6.94 (dd, J
=
8.7, 2.4 Hz, 2H), 6.87 (d, J = 2.4 Hz, 1H), 6.57 (d, J = 7.4 Hz, 1H), 5.26 (s, 2H),
1
3
5
1
1
1
7
4
4
.09 (s, 2H), 4.86 (s, 2H), 2.08 (s, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.26,
3
1
62.84 (d, J = 245.7 Hz), 162.21, 160.19, 155.07, 146.13, 141.65, 139.20, 137.34,
C-F
4
3
31.39 (d, J = 3.3 Hz), 129.58(d, J = 8.3 Hz), 129.43, 129.32, 128.45, 128.42,
C-F
C-F
2
28.28, 119.98, 117.69, 115.89 (d, JC-F = 21.45 Hz), 113.85, 112.29, 101.86, 73.25,
+
0.06, 52.57, 12.73. HRMS m/z: calc. for C H FNO [M+H] , 498.1711, found
30
25
5
98.1708.
.6.14. 3-(Benzyloxy)-2-ethyl-1-((7-((4-fluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)m
ethyl)pyridin-4(1H)-one (22b)
1
Yield: 37%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45 (d, J =
1.6 Hz, 1H), 7.44 (d, J = 1.3 Hz, 1H), 7.40 (dd, J = 8.6, 5.4 Hz, 2H), 7.34 - 7.27 (m,
5H), 7.09 (t, J = 8.6 Hz, 2H), 6.93 (dd, J = 8.7, 2.4 Hz, 1H), 6.88 (d, J = 2.4 Hz, 1H),
6.83 (s, 1H), 6.55 (d, J = 7.4 Hz, 1H), 5.35 (s, 2H), 5.09 (s, 2H), 4.87 (s, 2H), 2.52 (q,
1
3
J = 7.5 Hz, 2H), 1.03 (t, J = 7.5 Hz, 3H). C NMR (150 MHz, CDCl ), δ (ppm):
3
1
1
1
1
7
5
4
73.30, 162.74(d, J = 246 Hz), 162.07, 160.04, 154.88, 145.94, 138.91, 138.54,
C-F
4
3
37.57, 131.28(d, J = 3.0 Hz), 129.46(d, J = 7.5 Hz), 129.47, 129.26, 128.92,
C-F
C-F
2
28.33, 128.07, 120.61, 118.06, 115.78(d, J = 21.0Hz), 113.73, 112.18, 101.77,
C-F
+
2.88, 69.95, 51.78, 19.83, 13.43. HRMS m/z: calc. for C H FNO [M+H] ,
3
1
27
5
12.1868, found 512.1860.
.6.15. 5-(Benzyloxy)-1-((7-((4-fluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-2
-methylpyridin-4(1H)-one (22c)
1
Yield: 55%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.41 (dd, J =
.4, 5.3 Hz, 2H), 7.36 (d, J = 7.6 Hz, 2H), 7.31 (d, J = 8.6 Hz, 1H), 7.22 (t, J = 7.6 Hz,
8

ACCEPTED MANUSCRIPT
2
3
5
H), 7.14 (d, J = 7.5 Hz, 1H), 7.09 (t, J = 8.6 Hz, 2H), 7.06 (s, 1H), 6.99 (q, J = 4.9,
.7 Hz, 1H), 6.94 (dd, J = 8.6, 2.4 Hz, 1H), 6.87 (d, J = 2.4 Hz, 1H), 6.44 (s, 1H),
1
3
.17 (s, 2H), 5.10 (s, 2H), 4.80 (s, 2H), 2.27 (s, 3H). C NMR (150 MHz, CDCl ), δ
3
1
(
ppm): 172.96, 163.85(d, J = 244.5 Hz), 162.24, 160.27, 155.15, 147.55, 145.86,
C-F
4
3
1
1
1
4
4
39.69, 136.45, 131.40(d, J = 3.0 Hz), 129.59, 129.58(d, J = 9.0 Hz), 128.57,
C-F C-F
2
28.18, 128.04, 127.97, 119.66, 118.36, 115.90(d, JC-F = 21.0 Hz), 113.81, 112.30,
+
01.84, 71.76, 70.07, 51.88, 19.22. HRMS m/z: calc. for C H FNO [M+H] ,
3
0
25
5
98.1711, found 498.1708.
.6.16. 3-(Benzyloxy)-1-((7-((3,5-difluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)meth
yl)-2-methylpyridin-4(1H)-one (23a)
1
Yield: 69%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.40 (d, J =
1
1
6
5
.6 Hz, 1H), 7.39 (d, J = 1.2 Hz, 1H), 7.33 (d, J = 8.7 Hz, 1H), 7.31 (d, J = 7.7 Hz,
H), 7.30 - 7.27 (m, 2H), 7.26 - 7.23 (m, 1H), 6.94 (ddd, J = 8.7, 3.9, 2.1 Hz, 3H),
.88 (s, 1H), 6.85 (d, J = 2.4 Hz, 1H), 6.81 - 6.75 (m, 1H), 6.51 (d, J = 7.5 Hz, 1H),
13
.27 (s, 2H), 5.11 (d, J = 2.6 Hz, 2H), 4.83 (d, J = 1.5 Hz, 2H), 2.06 (s, 3H). C NMR
1
3
(
150 MHz, CDCl ), δ (ppm): 173.67, 163.36 (dd, J = 247.5, J = 13.5 Hz),
3 C-F C-F
3
1
61.67, 160.04, 154.99, 146.29, 141.10, 139.64(t, JC-F = 9 Hz), 139.04, 138.71,
1
37.46, 129.50, 129.32, 128.40, 128.23, 120.48, 117.96, 113.68, 112.58, 109.98(dd,
2
3
2
JC-F = 19.5, J = 4.5 Hz), 103.88(t, J = 25.5 Hz), 101.93, 73.11, 69.26, 52.41,
C-F
C-F
+
1
2.65. HRMS m/z: calc. for C H F NO [M+H] , 516.1617, found 516.1614.
30 24 2 5
4
.6.17. 3-(Benzyloxy)-1-((7-((3,5-difluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)meth
yl)-2-ethylpyridin-4(1H)-one (23b)
1
Yield: 40%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.45 (d, J =
1
.6 Hz, 1H), 7.43 (d, 1H), 7.34 - 7.26 (m, 5H), 6.94 (ddd, J = 8.6, 5.5, 2.3 Hz, 3H),
.85 (d, J = 2.4 Hz, 1H), 6.83 (s, 1H), 6.78 (tt, J = 8.8, 2.3 Hz, 1H), 6.53 (d, J = 7.4
6
Hz, 1H), 5.34 (s, 2H), 5.11 (s, 2H), 4.87 (s, 2H), 2.52 (q, J = 7.5 Hz, 2H), 1.03 (t, J =
13
1
7
.5 Hz, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 173.86, 163.37(dd, J = 249,
3 C-F
3
3
JC-F = 13.5 Hz), 161.66, 160.04, 154.94, 146.04, 145.99, 139.65(t, J = 9.0 Hz),
C-F
1
39.03, 138.53, 137.69, 129.51, 129.02, 128.44, 128.18, 121.07, 118.19, 113.68,
2
3
2
1
12.59, 109.98(dd, J = 19.5, J = 4.5 Hz), 103.88(t, J = 25.5 Hz), 101.94,
C-F C-F C-F

ACCEPTED MANUSCRIPT
+
7
5
4
2.97, 69.26, 51.86, 19.94, 13.55. HRMS m/z: calc. for C H F NO [M+H] ,
31 26 2 5
30.1774, found 530.1753.
.6.18. 5-(Benzyloxy)-1-((7-((3,5-difluorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)meth
yl)-2-methylpyridin-4(1H)-one (23c)
1
Yield: 45%, yellow oil. H NMR (600 MHz, Chloroform-d), δ (ppm): 7.37 (d, J =
1
.5 Hz, 1H), 7.36 (s, 1H), 7.33 (d, J = 8.7 Hz, 1H), 7.23 (t, J = 7.5 Hz, 2H), 7.14 (t, J
=
7.4 Hz, 1H), 7.06 (s, 1H), 6.99 (s, 1H), 6.95 (ddd, J = 8.6, 4.7, 2.3 Hz, 3H), 6.85 (d,
J = 2.4 Hz, 1H), 6.78 (tt, J = 8.8, 2.4 Hz, 1H), 6.44 (s, 1H), 5.18 (s, 2H), 5.12 (s, 2H),
1
3
4
.81 (s, 2H), 2.26 (s, 3H). C NMR (150 MHz, CDCl ), δ (ppm): 172.80, 163.26 (dd,
3
1
3
3
JC-F = 247.5, J = 13.5 Hz ), 161.61, 160.04, 154.98, 147.45, 145.67, 139.5 (t, J
C-F
C-F
=
9.0 Hz), 136.36, 129.60, 128.46, 128.06,127.96, 127.94, 127.88, 119.93, 118.30,
2
3
2
1
1
5
4
13.54, 112.47, 109.87(dd, J = 27.0, J = 6.0 Hz), 103.78(t, J = 25.5Hz),
C-F C-F C-F
+
01.79, 71.65, 69.15, 51.74, 19.09. HRMS m/z: calc. for C H F NO [M+H] ,
3
0
24
2
5
16.1617, found 516.1621.
.7.General procedure for the preparation of compounds 8a-c, 13a-c.
a was dissolved in anhydrous CH Cl (10 mL) and flushed with nitrogen. After
7
2
2
the flask was cooled to -48℃ , boron tribromide (1M in CH Cl , 1.5eq) was added
2
2
slowly, and the reaction mixture was allowed to stir at room temperature for 12 h. The
reaction mixture was eliminated by the addition of methanol (10 mL) and left to stir
for another 0.5 h. The solvent was then evaporated under reduced pressure, and the
residues were purified by recrystallization from methanol/ ether to afford the target
compound.
4
.7.1. 3-Hydroxy-2-methyl-1-((2-oxo-2H-chromen-3-yl)methyl)pyridin-4(1H)-one
hydrobromide (8a)
1
Yield: 90%, m.p. = 269.9℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.54 (s, 1H),
6
8
8
.34 (d, J = 7.1 Hz, 1H), 7.78 (s, 1H), 7.73 (dd, J = 7.8, 1.6 Hz, 1H), 7.65 (ddd, J =
.7, 7.3, 1.6 Hz, 1H), 7.45 (d, J = 8.2 Hz, 1H), 7.37 (td, J = 7.5, 1.1 Hz, 1H), 7.20 (d,
1
3
J = 7.0 Hz, 1H), 5.47 (d, J = 1.3 Hz, 2H), 2.54 (s, 3H). C NMR (150 MHz, DMSO),
δ (ppm): 159.39, 159.35, 152.91, 143.16, 142.05, 140.89, 139.25, 132.31, 128.77,
1
24.78, 122.12, 118.54, 116.13, 110.83, 54.83, 12.72. HRMS m/z: calc. for

ACCEPTED MANUSCRIPT
+
C H NO [M+H] 284.0917, found 284.0919.
16
14
4
4
.7.2. 2-Ethyl-3-hydroxy-1-((2-oxo-2H-chromen-3-yl)methyl)pyridin-4(1H)-one
hydrobromide (8b)
1
Yield: 85%, m.p. = 219.7℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.60 (s, 1H),
6
8
.29 (d, J = 7.0 Hz, 1H), 7.77 (s, 1H), 7.74 (dd, J = 7.8, 1.6 Hz, 1H), 7.65 (ddd, J =
.7, 7.4, 1.6 Hz, 1H), 7.47 (d, J = 8.3 Hz, 1H), 7.38 (td, J = 7.5, 1.0 Hz, 1H), 7.19 (d,
8
J = 7.0 Hz, 1H), 5.45 (d, J = 1.4 Hz, 2H), 2.95 (q, J = 7.4 Hz, 2H), 1.15 (t, J = 7.5 Hz,
1
3
3
1
H). C NMR (150 MHz, DMSO), δ (ppm): 159.67, 159.29, 152.88, 146.11, 143.14,
40.74, 139.05, 132.38, 128.77, 124.87, 122.82, 118.50, 116.17, 111.17, 54.28, 19.88,
+
1
1.72. HRMS m/z: calc. for C H NO [M+H] 298.1074, found 298.1073.
1
7
16
4
4
.7.3. 5-Hydroxy-2-methyl-1-((2-oxo-2H-chromen-3-yl)methyl)pyridin-4(1H)-one
hydrobromide (8c)
1
Yield: 73%, m. p. = 257.1℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.90 (s,
6
1
H), 8.25 (s, 1H), 7.84 (s, 1H), 7.75 (dd, J = 7.8, 1.6 Hz, 1H), 7.65 (ddd, J = 8.7, 7.3,
.6 Hz, 1H), 7.46 (d, J = 8.2 Hz, 1H), 7.38 (td, J = 7.6, 1.1 Hz, 1H), 7.17 (s, 1H), 5.39
1
1
3
(
d, 2H), 2.60 (s, 3H). C NMR (150 MHz, DMSO), δ (ppm): 161.46, 159.95, 153.43,
1
49.01, 144.19, 141.61, 132.84, 132.21, 129.29, 125.29, 122.56, 119.01, 116.63,
+
1
2
4
14.69, 54.73, 19.26. HRMS m/z: calc. for C H NO [M+H] 284.0917, found
16
14
4
84.0911.
.7.4. 3-Hydroxy-1-((7-methoxy-2-oxo-2H-chromen-3-yl)methyl)-2-methylpyridin-
4(1H)-one hydrobromide (13a)
1
Yield: 43%, m.p. = 253.6℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.53 (s, 1H),
6
8
1
2
1
5
4
.33 (d, J = 7.0 Hz, 1H), 7.80 (s, 1H), 7.65 (d, J = 8.7 Hz, 1H), 7.19 (d, J = 6.9 Hz,
H), 7.05 (d, J = 2.4 Hz, 1H), 6.98 (dd, J = 8.7, 2.5 Hz, 1H), 5.42 (d, 2H), 3.86 (s, 3H),
1
3
.54 (s, 3H). C NMR (150 MHz, DMSO), δ (ppm): 162.80, 159.79, 159.28, 154.93,
43.10, 141.97, 141.76, 139.18, 129.90, 118.02, 112.76, 112.06, 110.73, 100.53, 56.06,
+
4.86, 12.74. HRMS m/z: calc. for C H NO [M+H] 314.1023, found 314.1025.
1
7
16
5
.7.5. 2-Ethyl-3-hydroxy-1-((7-methoxy-2-oxo-2H-chromen-3-yl)methyl)pyridin-4(
1
H)-one hydrobromide (13b)
1
Yield: 61%, m.p. = 214.9℃ . H NMR (500 MHz, Chloroform-d), δ (ppm): 10.55 (s,

ACCEPTED MANUSCRIPT
1
7
2
H), 8.29 (d, J = 7.1, 2.4 Hz, 1H), 7.80 (d, J = 2.0 Hz, 1H), 7.66 (d, J = 8.8 Hz, 1H),
.22 - 7.14 (m, 1H), 7.07 (d, J = 2.4 Hz, 1H), 6.98 (dd, J = 8.7, 2.4 Hz, 1H), 5.41 (s,
1
3
H), 3.86 (s, 3H), 2.96 (q, J = 7.5 Hz, 2H), 1.13 (t, J = 7.5 Hz, 3H). C NMR (100
MHz, DMSO), δ (ppm): 163.36, 160.32, 160.19, 155.42, 146.32, 143.63, 142.21,
1
39.46, 130.40, 119.16, 113.34, 112.51, 111.55, 101.07, 56.57, 54.75, 20.33, 12.18.
+
HRMS m/z: calc. for C H NO [M+H] 328.1179, found 328.1173.
1
8
18
5
4
.7.6. 5-Hydroxy-2-methyl-1-((2-oxo-2H-chromen-3-yl)methyl)pyridin-4(1H)-one
hydrobromide (13c)
1
Yield: 78%, m.p. = 257.1℃ . H NMR (500 MHz, Chloroform-d), δ (ppm): 10.89 (s,
1
H), 8.23 (s, 1H), 7.86 (s, 1H), 7.67 (d, J = 8.7 Hz, 1H), 7.15 (s, 1H), 7.06 (d, J = 2.4
1
3
Hz, 1H), 6.98 (dd, J = 8.7, 2.4 Hz, 1H), 5.34 (d, 2H), 3.86 (s, 3H), 2.60 (s, 3H). C
NMR (150 MHz, DMSO), δ (ppm): 162.84, 160.90, 159.87, 154.98, 148.40, 143.63,
1
42.09, 131.59, 129.93, 117.98, 114.16, 112.80, 112.03, 100.55, 56.07, 54.26, 18.82.
+
HRMS m/z: calc. for C H NO [M+H] 284.0917, found 284.0911.
1
6
14
4
4
.8.General procedure for the preparation of compounds 24a-c, 25a-c, 26a-c,
7a-c, 28a-c, 29a-c.
8a was dissolved in anhydrous CH Cl (10 mL) and flushed with nitrogen.
2
1
2
2
After the flask was cooled to -48℃ , boron trichloride (1M in CH Cl , 1.5eq) was
2
2
added slowly, and the reaction mixture was allowed to stir at room temperature for 12
h. The reaction mixture was eliminated by the addition of methanol (10 mL) and left
to stir for another 0.5 h. The solvent was then evaporated under reduced pressure, and
the residues were purified by recrystallization from methanol/ether to afford the target
compound.
4
.8.1. 3-Hydroxy-2-methyl-1-((2-oxo-7-(prop-2-yn-1-yloxy)-2H-chromen-3-yl)meth
yl)pyridin-4(1H)-one hydrochloride (24a)
1
Yield: 77%, m.p. = 228.7℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.55 (s, 1H),
6
8
.35 (d, J = 7.1 Hz, 1H), 7.76 (s, 1H), 7.67 (d, J = 8.7 Hz, 1H), 7.44 (d, J = 7.0 Hz,
H), 7.10 (d, J = 2.4 Hz, 1H), 7.01 (dd, J = 8.7, 2.5 Hz, 1H), 5.46 - 5.38 (m, 2H), 4.94
1
1
3
(
d, J = 2.4 Hz, 2H), 3.66 (t, J = 2.4 Hz, 1H), 2.53 (s, 3H). C NMR (150 MHz,
DMSO), δ (ppm): 160.44, 159.66, 159.41, 154.58, 143.08, 141.96, 141.36, 139.03,

ACCEPTED MANUSCRIPT
1
29.92, 118.62, 113.21, 112.65, 110.78, 101.61, 78.99, 78.42, 56.19, 54.79, 12.72.
+
HRMS m/z calc. for C H NO [M+H] 338.1023, found 338.1012.
1
9
16
5
4
.8.2. 2-Ethyl-3-hydroxy-1-((2-oxo-7-(prop-2-yn-1-yloxy)-2H-chromen-3-yl)methyl
)pyridin-4(1H)-one hydrochloride (24b)
1
Yield: 78%, m.p. = 192.1℃ . H NMR (400 MHz, DMSO-d ), δ (ppm): 10.57 (s,
6
1
H), 8.31 (d, J = 7.0 Hz, 1H), 7.79 (s, 1H), 7.71 (d, J = 8.7 Hz, 1H), 7.36 (d, J = 6.9
Hz, 1H), 7.14 (d, J = 2.5 Hz, 1H), 7.05 (dd, J = 8.7, 2.5 Hz, 1H), 5.42 (s, 2H), 4.98 (d,
J = 2.5 Hz, 2H), 3.69 (t, J = 2.4 Hz, 1H), 2.98 (q, J = 7.3 Hz, 2H), 1.17 (t, J = 7.4 Hz,
1
3
3
1
5
3
4
H). C NMR (100 MHz, DMSO), δ (ppm): 160.98, 160.41, 160.03, 155.04, 146.26,
43.58, 141.77, 139.32, 130.38, 119.75, 113.75, 113.07, 111.60, 102.13, 79.44, 78.88,
+
6.67, 54.64, 20.32, 12.16. HRMS m/z calc. for C H NO [M+H] 352.1179, found
2
0
18
5
52.1191.
.8.3. 5-Hydroxy-2-methyl-1-((2-oxo-7-(prop-2-yn-1-yloxy)-2H-chromen-3-yl)meth
yl)pyridin-4(1H)-one hydrochloride (24c)
1
Yield: 65%, m.p. = 200.9℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.90 (s,
6
1
H), 8.26 (s, 1H), 7.79 (s, 1H), 7.69 (d, J = 8.7 Hz, 1H), 7.23 (s, 1H), 7.11 (d, J = 2.4
Hz, 1H), 7.02 (dd, J = 8.7, 2.4 Hz, 1H), 5.31 (s, 2H), 4.95 (d, J = 2.4 Hz, 2H), 3.67 (t,
1
3
J = 2.4 Hz, 1H), 2.57 (s, 3H). C NMR (100 MHz, DMSO), δ (ppm): 162.18, 160.93,
60.22, 155.09, 148.44, 144.45, 141.90, 131.56, 130.42, 119.27, 114.60, 113.72,
13.11, 102.10, 79.48, 78.91, 56.66, 54.48, 19.25. ESI-MS m/z calc. for C H NO
1
1
1
9
16
5
+
[
M+H] 338.1023, found 338.1012.
4
.8.4. 1-((7-(Benzyloxy)-2-oxo-2H-chromen-3-yl)methyl)-3-hydroxy-2-methylpyridi
n-4(1H)-one hydrochloride (25a)
1
Yield: 70%, m.p. = 224.4°C. H NMR (600 MHz, DMSO-d ), δ (ppm): 10.52 (s,
6
1
2
-
H), 8.32 (d, J = 7.1 Hz, 1H), 7.75 (s, 1H), 7.65 (d, J = 8.7 Hz, 1H), 7.48 - 7.45 (m,
H), 7.43 - 7.31 (m, 4H), 7.14 (d, J = 2.4 Hz, 1H), 7.04 (dd, J = 8.7, 2.4 Hz, 1H), 5.42
1
3
5.37 (m, 2H), 5.23 (s, 2H), 2.52 (s, 3H). C NMR (150 MHz, DMSO), δ (ppm):
1
1
61.69, 159.75, 159.60, 154.79, 143.14, 141.66, 141.46, 139.04, 136.17, 129.94,
28.53, 128.13, 127.91, 118.29, 113.37, 112.26, 110.77, 101.45, 69.93, 54.75, 12.69.
+
HRMS m/z: calc. for C H NO [M+H] , 390.1336, found 390.1336.
2
3
20
5

ACCEPTED MANUSCRIPT
4
.8.5. 1-((7-(Benzyloxy)-2-oxo-2H-chromen-3-yl)methyl)-2-ethyl-3-hydroxypyridin
-4(1H)-one hydrochloride (25b)
1
Yield: 64%, m.p. = 214.7°C. H NMR (600 MHz, DMSO-d ), δ (ppm): 10.53 (s,
6
1H), 8.27 (d, J = 7.1 Hz, 1H), 7.75 (s, 1H), 7.66 (d, J = 8.7 Hz, 1H), 7.48 - 7.44 (m,
2H), 7.43 - 7.38 (m, 2H), 7.37 - 7.32 (m, 2H), 7.15 (d, J = 2.4 Hz, 1H), 7.05 (dd, J =
8.7, 2.4 Hz, 1H), 5.39 (s, 2H), 5.23 (s, 2H), 2.95 (q, J = 7.4 Hz, 2H), 1.13 (t, J = 7.5
1
3
Hz, 3H). C NMR (150 MHz, DMSO), δ (ppm): 161.75, 159.77, 159.66, 154.77,
45.94, 143.07, 141.42, 138.85, 136.16, 129.94, 128.53, 128.14, 127.93, 118.89,
13.44, 112.22, 111.11, 101.48, 69.96, 54.24, 19.90, 11.71. HRMS m/z: calc. for
1
1
+
C H NO [M+H] , 404.1492, found 404.1502.
24
22
5
4
.8.6. 1-((7-(Benzyloxy)-2-oxo-2H-chromen-3-yl)methyl)-5-hydroxy-2-methylpyridi
n-4(1H)-one hydrochloride (25c)
1
Yield: 72%, m.p. = 254.3℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.85 (s, 1H),
6
8
.25 (s, 1H), 7.80 (s, 1H), 7.68 (d, J = 8.7 Hz, 1H), 7.47 (d, J = 7.1 Hz, 2H), 7.41 (t, J
7.5 Hz, 2H), 7.38 - 7.33 (m, 1H), 7.22 (s, 1H), 7.15 (d, J = 2.3 Hz, 1H), 7.06 (dd, J
=
=
13
8.7, 2.4 Hz, 1H), 5.31 (s, 2H), 5.24 (s, 2H), 2.57 (s, 3H). C NMR (150 MHz,
DMSO), δ (ppm): 162.21, 162.10, 160.30, 155.31, 148.38, 144.45, 142.17, 136.65,
1
7
3
4
31.62, 130.45, 129.00, 128.60, 128.38, 118.83, 114.60, 113.87, 112.72, 101.95,
+
0.43, 54.51, 19.29. HRMS m/z calc. for C H NO [M+H] 390.1336, found
2
3
20
5
90.1347.
.8.7. 1-((7-((3-Chlorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-3-hydroxy-2-m
ethylpyridin-4(1H)-one hydrochloride (26a)
1
Yield: 75%, m.p. = 224.4℃ . H NMR (600 MHz, DMSO-d ), δ (ppm): 10.54 (s, 1H),
6
8
.32 (d, J = 7.1 Hz, 1H), 7.74 (s, 1H), 7.66 (d, J = 8.7 Hz, 1H), 7.54 (t, J = 1.3 Hz,
H), 7.47 - 7.34 (m, 4H), 7.14 (d, J = 2.4 Hz, 1H), 7.05 (dd, J = 8.7, 2.4 Hz, 1H), 5.40
1
1
3
(
s, 2H), 5.25 (s, 2H), 2.52 (s, 3H). C NMR (150 MHz, DMSO), δ (ppm): 161.88,
1
1
1
4
60.20, 160.08, 155.24, 143.62, 142.16, 141.91, 139.51, 139.25, 133.64, 130.94,
30.47, 128.50, 127.97, 126.85, 118.90, 113.78, 112.90, 111.26, 101.99, 69.40, 55.21,
+
3.17. HRMS m/z calc. for C H NO [M+H] 390.1336, found 390.1336.
2
3
20
5
.8.8. 1-((7-((3-Chlorobenzyl)oxy)-2-oxo-2H-chromen-3-yl)methyl)-2-ethyl-3-hydro