Synthesis and structure-activity relationship study of benzofuran-based chalconoids bearing benzylpyridinium moiety as potent acetylcholinesterase inhibitors

Article abstract of DOI:10.1016/j.ejmech.2015.08.061

A series of benzofuran-based chalconoids 6a-v were designed and synthesized as new potential AChE inhibitors. The in vitro assay of synthesized compounds 6a-v showed that most compounds had significant anti-AChE activity at micromolar or sub-micromolar levels. Among the tested compounds, 3-pyridinium derivative 6m bearing N-(2-bromobenzyl) moiety and 7-methoxy substituent on the benzofuran ring exhibited superior activity. This compound with IC₅₀ value of 0.027 μM was as potent as standard drug donepezil.

Full text of DOI:10.1016/j.ejmech.2015.08.061

Accepted Manuscript
Synthesis and structure-activity relationship study of benzofuran-based chalconoids
bearing benzylpyridinium moiety as potent acetylcholinesterase inhibitors
Manizheh Mostofi, Ghodsi Mohammadi Ziarani, Mohammad Mahdavi, Alireza Moradi,
Hamid Nadri, Saeed Emami, Heshmatollah Alinezhad, Alireza Foroumadi, Abbas
Shafiee
PII:
S0223-5234(15)30244-0
10.1016/j.ejmech.2015.08.061
EJMECH 8097
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 17 June 2015
Revised Date: 30 August 2015
Accepted Date: 31 August 2015
Please cite this article as: M. Mostofi, G.M. Ziarani, M. Mahdavi, A. Moradi, H. Nadri, S. Emami, H.
Alinezhad, A. Foroumadi, A. Shafiee, Synthesis and structure-activity relationship study of benzofuran-
based chalconoids bearing benzylpyridinium moiety as potent acetylcholinesterase inhibitors, European
Journal of Medicinal Chemistry (2015), doi: 10.1016/j.ejmech.2015.08.061.
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ACCEPTED MANUSCRIPT
Synthesis and structure-activity relationship study of benzofuran-based chalconoids
bearing benzylpyridinium moiety as potent acetylcholinesterase inhibitors
ManizhehMostofi, GhodsiMohammadiZiarani, Mohammad Mahdavi, , Alireza Moradi,
Hamid Nadri, Saeed Emami, HeshmatollahAlinezhad , Alireza Foroumadi, Abbas Shafiee*
O
O
Br
N
O
X
O
N
Br
6
a-v
6m
IC50 = 0.027 µM
R
Ar
OMe
A series of benzofuran-based chalconoids bearing 3-pyridinium and 4-pyridinium moiety
were synthesized as AChE inhibitors. Among them, 3-pyridinium derivative 6m with IC =
5
0
0
.027 µM was as potent as donepezil.

ACCEPTED MANUSCRIPT
Synthesis and structure-activity relationship study of benzofuran-based
chalconoids bearing benzylpyridinium moiety as potent acetylcholinesterase
inhibitors
a
a
b
c
Manizheh Mostofi , Ghodsi Mohammadi Ziarani , Mohammad Mahdavi , Alireza Moradi ,
c
d
e
b
Hamid Nadri , Saeed Emami , Heshmatollah Alinezhad
, Alireza Foroumadi , Abbas
b
Shafiee *
a
Department of Chemistry, Alzahra University, Vanak Square, P.O. Box 1993891176, Tehran,
Iran
b
Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences
Research Center, Tehran University of Medicinal Sciences, Tehran, Iran
c
Department of Medicinal Chemistry, Faculty of Pharmacy, Shahid Sadoughi University of
Medical Sciences, Yazd, Iran
d
Department of Medicinal Chemistry and Pharmaceutical Sciences Research Center, Faculty of
Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
e
Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
Abstract: A series of benzofuran-based chalconoids 6a-v were designed and synthesized as new potential
AChE inhibitors. The in vitro assay of synthesized compounds 6a-v showed that most compounds had
significant anti-AChE activity at micromolar or sub-micromolar levels. Among the tested compounds, 3-
pyridinium derivative 6m bearing N-(2-bromobenzyl) moiety and 7-methoxy substituent on the
benzofuran ring exhibited superior activity. This compound with IC50 value of 0.027 µM was as potent as
standard drug donepezil.
Keywords: Acetylcholinesterase; Alzheimer’s disease; Benzofuran; Docking study; Pyridinium
*
Corresponding author. Tel: +98 21 66406757; Fax: +98 21 66461178.
E-mail address: ashafiee@ams.ac.ir (A. Shafiee).
1

ACCEPTED MANUSCRIPT
1
. Introduction
Alzheimer’s disease (AD) is a fatal and age-related neurodegenerative disease causes a
progressive dementia in the elderly population and is characterized by progressive cognitive
impairments including memory loss, decline in motor and language skills and learning problems
[
1, 2]. The reported data by WHO demonstrated that more than 30 million people are afflicted
with AD worldwide, and the number of patients is expected to increase up to 100 million by
050 [3].
2
Although extensive efforts have been made to understand the complex pathophysiology of AD
but its etiology is not completely known. However, several factors have been identified which
involved in the onset and progression of AD. The main factors are oxidative stress, biometals
dysfunctions, deposit of abnormal proteins such as amyloid beta-peptide (Aβ) and τ-protein, and
degeneration of cholinergic neurons in the central nervous system [4, 5]. Particularly, the
impairment of the cholinergic neurotransmission in the brain, results in a substantial
acetylcholine (ACh) deficiency which leads to cognitive and memory deficits associated in AD
patients [6-8]. Accordingly, one approach to improve cholinergic neurotransmission in the AD
patients is to break down the ACh metabolism. ACh can be mainly hydrolyzed by
acetylcholinesterase (AChE) at the cholinergic synapses. Consequently, several AChE inhibitors
such as donepezil, tacrine, rivastigmine, and galanthamine have been developed and approved by
FDA for AD treatment. These agents have some beneficial effects on cognitive and
neuropsychiatric symptoms of AD [9,10].
2

ACCEPTED MANUSCRIPT
The X-ray crystallographic study of AChE structure indicates that it consists of two distinct
ligand binding sites, a catalytic active site (CAS) at the bottom, and a peripheral cationic site
(PAS) at the entrance [11]. While the AChE Inhibitors binding to either site can restrain the
activity of AChE, but dual binding site inhibitors are more promising compounds for developing
disease-modifying drugs for treating of AD [12]. Recently, a series of donepezil-tacrine,
oxoisoaporphine-tacrine hybrids, and coumarin derivatives have been designed as potent AChE
inhibitors. These compounds were able to bind simultaneously to both sites of the enzyme,
exhibiting high AChE inhibitory activity [13-15].
In the search for finding new potent and selective AChE inhibitors as potential anti-Alzheimer
drugs [16-18], we have previously reported coumaranone- or coumarin-based chalconoids
bearing benzyl pyridinium scaffold as donepezil analogs (Fig. 1) [19-21]. The experiences on the
binding mode of donepezil with AChE revealed that the benzyl piperidine moiety of the
molecule which protonated at the physiologic pH can interact with the CAS, and the indanone
part of donepezil binds to the PAS [22,23]. Similarly, the computational studies on the binding
interactions of coumaranone- or coumarin-based chalconoids with AChE indicated that the N-
benzylpyridinium part of the molecules interacts with the catalytic site of AChE, and the
aromatic part of coumaranone or coumarin ring engages in π-π stacking with the peripheral
cationic site of the enzyme [19-21]. In the present report, we describe synthesis, biological
activity and docking study of new benzofuran-based AChE inhibitors containing N-
benzylpyridinium motif (Fig. 1). Indeed, the coumaranone or coumarin part of the primary hits
was replaced with benzofuran ring which recently has been considered in many designed multi-
potent AD modifying agents [24].
<
Figure 1>
3

ACCEPTED MANUSCRIPT
2
. Chemistry
The synthesis of designed compounds 6a-v was outlined in Scheme 1. The intermediate
compounds 2-acetylbenzofurans 3a-c were prepared according to the literature method [25].
Thus, the reaction of salicylaldehyde derivatives 1a-c with chloroacetone (2) in the presence of
K CO afforded 2-acetylbenzofurans 3a-c. Condensation of 2-acetylbenzofurans 3a-c with either
2
3
pyridine-3-carboxaldehyde or pyridine-4-carboxaldehyde in n-butanol under microwave
irradiation gave selectively (E)-isomers of α,β-unsaturated ketones 4a-c or 5a,b, respectively
(Scheme 1). Compound 4a was reported in the literature [26] and compounds 4b,c and 5a,b were
new compounds. Finally, compounds 4a-c or 5a,b were reacted with appropriate benzyl halide in
refluxing acetonitrile to give N-benzylpyridinium halide salts 6a-v in good yields. The (E)-
geometry of final compounds 6a-v was assigned based on coupling constants of vinylic
hydrogens (Jα,β > 15 Hz).
<Scheme 1>
3
. Results and discussion
3
.1. Anti-AChE activity
The inhibitory activity of synthesized compounds 6a-v was evaluated in vitro against AChE
enzyme and presented as IC values in Table 1. Donepezil was used as standard drug.
5
0
<Table 1>
As seen in Table 1, the obtained IC values for tested compounds were in the range of 0.027-31
5
0
µM, indicating the potential of compounds for anti-AChE activity. Unfortunately, fluorine-
4

ACCEPTED MANUSCRIPT
substituted compounds 6e, 6g, 6s, and 6v were not soluble in the test conditions and their
inhibitory activity was not reported.
Structurally, the synthesized compounds 6a-p and 6q-v were 3-pyridinium and 4-pyridinium
derivatives, respectively. The two parent 3- and 4-pyridinium compounds as represented by 6a
and 6q were potent AChE inhibitors (IC s 0.058 and 0.064 µM, respectively). Substitution at the
5
0
benzyl residue was largely controversial and depended on the other structural features of the
molecule. For example, while the 2,3-dichloro substituent on the N-benzyl-3-pyridinium
derivatives improved the activity (compare 6j and 6p to 6f and 6l), this substituent diminished
the activity in the 4-pyridinium series. Exceptionally, the 2-Br substituent on the benzyl moiety
offered a modest improvement over 2-H analog. The 2-bromobenzyl derivatives 6b, 6h, 6m, and
6
r were more potent than their benzyl congeners 6a, 6f, 6l, and 6q. Displacement of bromo from
2
- to 4-position on the benzyl group dramatically decreased the activity.
Substitution at the 5- or 7-position of the benzofuran ring was generally not tolerated. The only
exception to this SAR was demonstrated by compound 6m where the preferred 2-bromobenzyl
substituent then led to the tolerance of the 7-methoxy substituent on the benzofuran ring,
providing the most potent compound in the series (IC = 0.027 µM). The activity of 2-
5
0
bromobenzyl derivative 6m was comparable to that of standard drug donepezil.
By comparing the IC50 values of related regioisomers in the 3-pyridinium and 4-pyridinium
series (6a vs. 6q, 6b vs. 6r, and 6f vs. 6u), it was revealed that they were equipotent.
3
.2. Molecular docking study
In order to understanding the interactions of our new compounds in the active site of the AChE,
the title compounds were investigated computationally to define their binding profile. For
5

ACCEPTED MANUSCRIPT
instance, the most active compound 6m was subjected for further analysis. The best pose of
docking was selected in terms of free energy of binding. The interaction of compound 6m and
residues in the gorge of enzyme was simply illustrated in Figure 2. Particularly, three aromatic
and hydrophobic patch of the active site namely CAS (catalytic anionic site), AS (anionic site) or
mid-gorge recognition site and PAS (peripheral anionic site) were involved in the interaction.
<
Figure 2>
As shown in Figure 2, compound 6m exhibited gorge-binding mode, in which the compound
spans the narrow hydrophobic gorge from the bottom to the rim. The main stabilizing forces
were hydrophobic interactions including π-π stacking and halogen bonding. CAS amino acid
residue Trp83 was found to have π-π stacking with benzofuran ring. Similarly, the pendant
bromophenyl end of the molecule was involved in the π-π stacking with PAS amino acid residue
Trp278. While the pendant phenyl ring was stacked with Trp278, 2-bromo substituent interacted
with Arg288 through halogen bonding. Being locked the molecule in the gorge of the enzyme;
the pyridinium ring was accommodated in the active site through π-cation interaction with
Tyr333.
4
. Conclusion
We have designed and synthesized a series of benzofuran-based chalconoids as new potential
AChE inhibitors. Most compounds showed significant anti-AChE activity at micromolar or sub-
micromolar levels. Among the tested compounds, 3-pyridinium derivative 6m bearing N-(2-
bromobenzyl) moiety and 7-methoxy substituent on the benzofuran ring was the most active
compound. Compound 6m with IC50 value of 0.027 µM was as potent as standard drug
6

ACCEPTED MANUSCRIPT
donepezil. The SAR study revealed that the 3-pyridinium and 4-pyridinium regioisomers were
equipotent and both of them could be considered as a parent scaffold for structural optimization
on the benzofuran ring and benzyl residue.
5
. Experimental
5
.1. Chemistry
The commercially available reagents were purchased from Merk AG, Aldrich or Acros Organics
and used without further purification. For the synthesis of compounds 4 and 5, the experiments
were performed using a microwave oven (ETHOS 1600, Milestone) with a power of 600 W
specially designed for an organic synthesis and modified with a condenser and mechanical
stirrer. Melting points were measured on a Kofler hot stage apparatus and are uncorrected. The
IR spectra were taken using Nicolet FT-IR Magna 550 spectrographs (KBr disks). Mass spectra
of the products were obtained with an HP (Agilent technologies) 5937 Mass Selective Detector
1
13
(
in positive mode). H NMR and C NMR spectra were recorded on Bruker 400 or 500 NMR
instrument. The atom numbering of target compounds used for NMR data interpretation is
depicted in Figure 3. The chemical shifts (δ) and coupling constant (J) are expressed in parts per
million (ppm) and Hertz (Hz), respectively.
5
.1.1. General procedure for the preparation of 2-acetylbenzofuran derivatives 3a-c [25]
A mixture of salicylaldehyde derivative 1a-c (5 mmol) and anhydrous potassium carbonate (5.5
mmol) in dry acetone (30 ml) were refluxed for 2 h. Chloroacetone (2, 5.5 mmol) was added
7

ACCEPTED MANUSCRIPT
dropwise within 2-3 h and reflux was continued for another 5 h. Then, the potassium salts were
filtered off and triturated with warm acetone. The solution was concentrated by evaporating part
of the solvent and the obtained precipitate was filtered and washed with cold ethanol to give the
pale yellow crystals of 2-acetylbenzofuran derivatives 3a-c.
5
.1.1.1. 1-(Benzofuran-2-yl)ethan-1-one (3a). Yield 72%, pale yellow solid; mp 75-76 ºC (lit.
-
1
1
[
25] mp 76 ºC); IR (KBr, cm ) νmax: 1673 (C=O); H NMR (DMSO-d
CH ), 7.36 (td, 1H, H benzofuran, J= 8.0 Hz , J= 1.2 Hz), 7.53 (td, 1H, H
Hz, J= 1.2 Hz) 7.71 (dd, 1H, H benzofuran, J= 8.0 Hz, J= 1.2 Hz), 7.83 (dd, 1H, H benzofuran,
6
, 400 MHz), 2.50 (s, 3H,
3
5
6
benzofuran, J= 8.0
7
4
1
3
J= 8.0 Hz, J= 1.2 Hz), 7.89 (s, 1H, H benzofuran), C NMR (DMSO-d , 100 MHz) δ: 26.8,
3
6
1
12.6, 114.7, 124.1, 124.4, 127.3, 128.8, 152.5, 155.4, 188.3.
5
.1.1.2. 1-(5-Bromobenzofuran-2-yl)ethan-1-one (3b). Yield 75%, yellow solid; mp 110-111 ºC
-
1
1
(
lit. [25] mp 110 ºC); IR (KBr, cm ) νmax: 1661 (C=O); H NMR (DMSO-d
H, CH ), 7.70 (m, 2H, H6,7 benzofuran,), 7.83 (s, 1H, H benzofuran), 8.06 (s, 1H, H
benzofuran), C NMR (DMSO-d , 125 MHz) δ: 26.3, 113.1, 114.2, 116.0, 125.8, 128.9, 130.8,
6
, 500 MHz), 2.50 (s,
3
3
3
4
1
3
6
1
53.0, 153.6, 187.7.
5
.1.1.3. 1-(7-Methoxybenzofuran-2-yl)ethan-1-one (3c). Yield 78%, white solid; mp 91-93 ºC
-1
1
(
lit. [25] mp 91 ºC); IR (KBr, cm ) νmax: 1660 (C=O); H NMR (DMSO-d
6
, 500 MHz), 2.50 (s,
3
H, CH
3
), 3.97 (s, 3H, OCH
3
), 7.12 (d, 1H, H
6
benzofuran, J= 8.0 Hz), 7.27 (t, 1H, H
5
1
3
benzofuran, J= 8.0 Hz), 7.36 (d, 1H, H
4
3
benzofuran, J= 8.0 Hz), 7.84 (s, 1H, H benzofuran), C
NMR (DMSO-d , 125 MHz) δ: 26.3, 55.8, 109.8, 114.1, 115.0, 124.6, 128.3, 144.4, 145.4,
6
1
52.1, 187.6.
8

ACCEPTED MANUSCRIPT
5
2
.1.2. General procedure for the preparation of (E)-1-(benzofuran-2-yl)-3-(pyridine-3-yl) prop-
-en-1-ones (4a-c) or (E)-1-(benzofuran-2-yl)-3-(pyridine-4-yl)prop-2-en-1-ones (5a,b).
To a mixture of 2-acetylbenzofuran derivative 3a-c (6 mmol) and pyridine carbaldehyde (6
mmol) in n-butanol (10-15 ml), was added catalytic amount of piperidine (5-6 drops). Then, the
mixture was heated under microwave irradiation at 160 ºC for 30 min. After completion of the
reaction (monitored by tlc), ether was added and extracted two times with 5% HCl. To the
aqueous layer was added 5% aqueous KOH portion wise until it precipitated. The precipitated
solid was isolated by filtration and crystallized from ethanol to afford corresponding compounds
4
a-c or 5a,b.
5
.1.2.1. (E)-1-(Benzofuran-2-yl)-3-(pyridin-3-yl)prop-2-en-1-one (4a). Yield 75%, light yellow
-1
1
solid; mp 155-157 ºC (lit. [26] mp 154-156 ºC), IR (KBr, cm ) ν : 1657 (C=O), H NMR
max
(
CDCl
benzofuran, J= 8.0 Hz , J= 2.0 Hz), 7.51 (m, 1H, H
Hz), 7.69 (dd, 1H, H benzofuran, J= 8.0 Hz, J= 2.0 Hz), 7.92 (d, 1H, H vinylic, J= 16.0 Hz),
3
, 500 MHz), 7.27 (s, 1H, H
3
benzofuran), 7.34 (m, 1H, H
5
benzofuran), 7.38 (dd, 1H, H
7
6
benzofuran), 7.63 (d, 1H, H
α
vinylic, J= 15.5
4
β
8
.13 (m, 1H, H -pyridine), 8.35 (d, 1H, H -pyridine, J= 7.0 Hz), 8.64 (d, 1H, H -pyridine, J= 5.5
c d b
1
3
Hz), 9.05 (s, 1H, H -pyridine), C NMR (CDCl , 125 MHz) δ: 112.4, 113.6, 123.1, 123.3, 123.8,
a
3
1
24.0, 127.2, 128.4, 130.5, 134.8, 140.7, 150.0, 151.2, 153.4, 155.8, 179.1. Anal. Calcd for
C H NO : C, 77.10; H, 4.45; N, 5.62; Found C, 76.74; H, 4.67; N, 5.74.
16
11
2
5
.1.2.2. (E)-1-(5-Bromobenzofuran-2-yl)-3-(pyridin-3-yl)prop-2-en-1-one (4b). Yield 70%,
-1
1
yellow solid; mp 191-193 ºC; IR (KBr, cm ) ν : 1665 (C=O); H NMR (DMSO-d , 500 MHz),
max
6
7
.52 (s, 1H, H benzofuran), 7.66-7.76 (m, 2H, H benzofuran), 7.86 (d, 1H, H vinylic, J= 15.5
4 6,7 α
Hz), 8.00 (d, 1H, H vinylic, J= 15.5 Hz), 8.13 (m, 1H, H -pyridine), 8.27 (s, 1H, H benzofuran),
β
c
3
9

ACCEPTED MANUSCRIPT
8
.35 (d, 1H, H
d
-pyridine, J= 7.5 Hz), 8.64 (d, 1H, H
b a
-pyridine, J= 5.5 Hz), 9.05 (s, 1H, H -
1
3
pyridine), C NMR (DMSO-d , 125 MHz) δ: 113.2, 114.4, 116.2, 123.4, 123.8, 125.8, 126.0,
6
1
5
29.0, 130.0, 131.2, 135.1, 140.4, 150.3, 151.1, 154.0, 178.1. Anal. Calcd for C H BrNO : C,
16 10 2
8.56; H, 3.07; N, 4.27; Found C, 58.65; H, 3.33; N, 4.03.
5
.1.2.3. (E)-1-(7-Methoxybenzofuran-2-yl)-3-(pyridin-3-yl)prop-2-en-1-one (4c). Yield 72%,
-
1
1
yellow solid; mp 135-137 ºC; IR (KBr, cm ) νmax: 1663 (C=O); H NMR (CDCl
.06 (s, 3H, OCH ), 6.98 (dd, 1H, H benzofuran, J= 8.0 Hz, J= 1.0 Hz), 7.25 (t, 1H, H
benzofuran, J= 8.0 Hz), 7.31 (dd, 1H, H benzofuran, J= 8.0 Hz, J= 1.0 Hz), 7.43 (m, 1H, H -
3
, 500 MHz),
4
3
6
5
4
c
pyridine), 7.67 (s, 1H, H benzofuran), 7.73 (d, 1H, H vinylic, J= 16.0 Hz), 7.92 (d, 1H, H
β
3
α
vinylic, J= 16.0 Hz), 8.05 (d, 1H, H -pyridine, J= 8.0 Hz), 8.13 (dd, 1H, H -pyridine, J= 7.5 Hz,
d
c
1
3
J= 5.0 Hz), 8.69 (d, 1H, H -pyridine, J= 5.0 Hz), 8.96 (s, 1H, H -pyridine), C NMR (CDCl ,
b
a
3
1
1
25 MHz) δ: 56.1, 109.6, 113.6, 115.1, 123.4, 124.7, 128.9, 135.2, 140.5, 146.1, 148.2, 149.7,
50.7, 153.6, 168.6, 176.8, 179.1. Anal. Calcd for C16 : C, 73.11; H, 4.69; N, 5.02;
H
10BrNO
2
Found C, 72.94; H, 4.84; N, 4.79.
5
.1.2.4. (E)-1-(Benzofuran-2-yl)-3-(pyridin-4-yl)prop-2-en-1-one (5a). Yield 77%, cream solid;
-1
1
mp 143-145 ºC; IR (KBr, cm ) ν : 1658 (C=O); H NMR (CDCl , 500 MHz), 7.27 (s, 1H, H
3
max
3
benzofuran), 7.34 (t, 1H, H benzofuran, J= 8.0 Hz), 7.52 (d, 1H, H vinylic, J= 15.5 Hz), 7.53
5
α
(
d, 2H, H pyridine, J= 4.0 Hz), 7.63 (d, 1H, H benzofuran, J= 8.5 Hz), 7.70 (m, 1H, H
b-
7
6
benzofuran), 7.74 (d, 1H, H
d, 2H, H
24.1, 125.3, 127.1, 128.6, 141.3, 141.9, 150.5, 153.2, 155.9, 179.0. Anal. Calcd for
C H BrNO : C, 77.10; H, 4.45; N, 5.62; Found C, 76.84; H, 4.67; N, 5.74.
4
benzofuran, J= 8.5 Hz), 7.83 (d, 1H, H
β
vinylic, J= 15.5 Hz), 8.71
1
3
(
a 3
-pyridine, J= 4.0 Hz), C NMR (CDCl , 125 MHz) δ: 112.4, 113.9, 122.1, 123.4,
1
16
10
2
10

ACCEPTED MANUSCRIPT
5
.1.2.5. (E)-1-(5-Bromobenzofuran-2-yl)-3-(pyridin-4-yl)prop-2-en-1-one (5b). Yield 70%, light
-1
1
yellow solid, mp 189-191 ºC, IR (KBr, cm ) ν : 1658 (C=O), H NMR (CDCl , 500 MHz),
max
3
7
.27 (s, 1H, H benzofuran),7.50 (d, 1H, H benzofuran, J=8.0 Hz), 7.54 (d, 1H, H benzofuran,
3 7 4
J= 2.0 Hz), 7.60 (dd, 1H, H benzofuran, J=8.0 Hz, J= 2.0 Hz), 7.69 (d, 1H, H vinylic, J= 15.5
6
α
Hz), 7.83 (d, 1H, H vinylic, J= 15.5 Hz), 7.87 (d, 2H, H -pyridine, J= 5.0 Hz), 8.72 (d, 2H, H -
β
b
a
1
3
pyridine, J= 5.0 Hz), C NMR (CDCl , 125 MHz) δ: 112.7, 113.9, 117.2, 122.3, 123.1, 125.2,
3
1
25.8, 129.0, 131.6, 141.5, 142.2, 149.1, 150.0, 154.0, 154.4, 178.7. Anal. Calcd for
: C, 58.56; H, 3.07; N, 4.27; Found C, 58.39; H, 3.22; N, 4.04.
16 2
C H10BrNO
5
.1.3. General procedure for the synthesis of pyridinium halide derivatives 6a-v
Compounds 4a-c or 5a,b (1 mmol) and potassium iodide (0.3g) were dissolved in freshly
distilled dry acetonitrile (7 ml) in a 25 ml flask by heating under reflux. Then, appropriate benzyl
halide (1.8 mmol) was added dropwise. After heating under reflux for 2-4 h, it was left to cool to
room temperature. The precipitated solid was separated by filtration, washed with diethyl ether
and dried to afford corresponding compounds 6a-p and 6q-v respectively.
5
.1.3.1. (E)-3-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-benzylpyridinium bromide (6a).
From compound 4a (R= H, 1 mmol, 0.249 g) and benzyl bromide (1.2 mmol, 0.205 g), for 3 h,
-1
product 6a was obtained, yield 72%, cream solid, mp > 300 ºC; IR (KBr, cm ) νmax: 2922, 2854
1
(
CH ), 1741, 1663 (C=O), 1609 (C=C alkene); H NMR (DMSO-d , 400 MHz), 5.99 (s, 2H, -
2
6
+
CH N ), 7.45-7.38 (m, 4H, 3H phenyl and H benzofuran), 7.59 (t, 1H , H benzofuran, J=7.6
2
5
6
Hz), 7.69 (d, 2H, 2H phenyl, J= 7.6 Hz), 7.75 (d, 1H, H benzofuran, J= 7.6 Hz), 7.90 (d, 1H, Hα
7
vinylic, J= 15.6 Hz), 7.88 (d, 1H, H benzofuran, J= 7.6 Hz), 8.28 (m, 1H, H -pyridine), 8.42 (d,
4
c
11

ACCEPTED MANUSCRIPT
1
9
H, H
β 3 d
vinylic, J= 15.6 Hz), 8.61 (s, 1H, H benzofuran), 9.16 (d, 1H, H -pyridine, J= 7.0 Hz),
1
3
.28 (d, 1H, H -pyridine, J= 5.2 Hz), 10.16 (s, 1H, H -pyridine); C NMR (DMSO-d , 100
b
a
6
MHz) δ: 63.7, 112.8, 117.6, 124.5, 124.8, 127.2, 128.5, 128.9, 129.4, 129.6, 129.7, 129.9, 134.5,
1
35.4, 136.2, 144.6, 145.2, 145.3, 153.1, 156.0, 178.0. Anal. Calcd for C H BrNO : C, 65.73;
23 18 2
H, 4.32; N, 3.33. Found: C, 65.94; H, 4.08; N, 3.62.
5
.1.3.2. (E)-3-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(2-bromobenzyl)pyridinium bromide
(6b). From compound 4a (R= H, 1.0 mmol, 0.249 g) and 2-bromobenzyl bromide (1.2 mmol,
-1
0
.205 g), for 2 h, product 6b was obtained, yield 78%, cream solid, mp > 300 ºC; IR (KBr, cm )
1
νmax: 2919, 2850 (CH ), 1720, 1661 (C=O), 1609 (C=C alkene); H NMR (DMSO-d , 400 MHz),
2
6
+
6
.09 (s, 2H, -CH N ), 7.45-7.40 (m, 3H, 2H phenyl and H benzofuran), 7.49 (d, 1H, H
2 5 7
benzofuran, J= 7.8 Hz), 7.60 (t, 1H, H benzofuran, J= 7.8 Hz), 7.77 (m, 2H, 2H phenyl), 7.92 (d,
6
1
8
6
1
1
H, H benzofuran, J= 7.8 Hz), 7.94 (d, 1H, H vinylic, J= 16.0 Hz), 8.32 (m, 1H, H -pyridine),
4
α
c
.39 (d, 1H, H
β
vinylic, J=16.0 Hz), 8.56 (s, 1H, H
3
benzofuran), 9.11 (d, 1H, H
d
-pyridine, J=
1
3
b a 6
.8 Hz), 9.28 (d, 1H, H -pyridine, J= 5.5 Hz), 9.93 (s, 1H, H -pyridine); C NMR (DMSO-d ,
00 MHz) δ: 63.9, 112.8, 117.5, 123.8, 124.5, 124.8, 127.2, 128.6, 128.8, 129.1, 129.7, 131.8,
31.9, 133.2, 133.7, 135.4, 136.1, 144.9, 145.8, 146.0, 153.1, 156.0, 178.1. Anal. Calcd for
C H Br NO : C, 55.34; H, 3.43; N, 2.81. Found: C, 55.43; H, 3.69; N, 3.14.
23
17
2
2
5
.1.3.3. (E)-3-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(4-bromobenzyl)pyridinium bromide
(6c). From compound 4a (R= H, 1.0 mmol, 0.249 g) and 4-bromobenzyl bromide (1.2 mmol,
-1
0
.300 g), for 2 h, product 6c was obtained, yield 75%, cream solid, mp > 300 ºC; IR (KBr, cm )
1
ν
max: 2925, 2852 (CH
2
), 1739, 1662 (C=O), 1610 (C=C alkene); H NMR (DMSO-d
6
, 400 MHz),
+
5
.94 (s, 2H, -CH2N ), 7.47-7.41 (m, 3H, 2H phenyl and H benzofuran) , 7.64-7.59 (m, 3H, 2H
5
phenyl and H benzofuran), 7.77 (d, 1H, H benzofuran, J= 8.4 Hz), 7.91 (d, 1H, H benzofuran,
6
7
4
12

ACCEPTED MANUSCRIPT
J= 8.4 Hz), 7.92 (d, 1H, H
α
c β
vinylic, J= 16.0 Hz), 8.29 (m, 1H, H -pyridine), 8.33 (d, 1H, H
vinylic, d, J= 16.0 Hz), 8.47 (s, 1H, H benzofuran), 9.16 (d, 1H, H -pyridine, J= 7.0 Hz), 9.24
3
d
1
3
(
d, 1H, H -pyridine, J= 5.6 Hz), 9.96 (s, 1H, H -pyridine); C NMR (DMSO-d , 100 MHz) δ:
b a 6
6
1
3
4.0, 112.8, 117.3, 124.5, 124.8, 127.2, 128.5, 128.9, 129.3, 129.6, 129.7, 129.9, 134.4, 135.5,
36.2, 144.4, 145.3, 145.4, 153.2, 156.0, 178.1. Anal. Calcd for C H Br NO : C, 55.34; H,
23
17
2
2
.43; N, 2.81. Found: C, 55.08; H, 3.51; N, 3.07.
5
.1.3.4. (E)-3-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(4-nitrobenzyl)pyridinium bromide
(6d). From compound 4a (R= H, 1.0 mmol, 0.249 g) and 4-nitrobenzyl bromide (1.2 mmol,
-1
0
.259 g), for 2 h, product 6d was obtained, yield 85%, white solid, mp > 300 ºC; IR (KBr, cm )
1
νmax: 2923, 2851 (CH ), 1741 (C=O), 1616 (C=C alkene); H NMR (DMSO-d , 400 MHz), 6.24
2
6
+
(
s, 2H, -CH N ), 7.41 (d, 2H, 2H phenyl, J= 8.8 Hz), 7.60 (t, 1H, H benzofuran, J= 7.6 Hz), 7.76
2 5
(
t, 1H, H benzofuran, J= 7.6 Hz), 7.90 (d, 2H, 2H phenyl, J= 8.8 Hz), 7.99 (m, 2H, H
6
4,7
benzofuran), 8.29 (dd, 1H, H
Hz), 8.50 (d, 1H, H vinylic, J= 16.4 Hz), 8.73 (s, 1H, H
J= 7.4 Hz), 9.37 (d, 1H, H - pyridine, J= 4.8 Hz), 10.34 (s, 1H, H
d6, 100 MHz) δ: 62.9, 100.9, 106.3, 119.4, 120.1, 124.1, 127.3, 129.8, 130.5, 131.2, 131.5, 133.4,
c
-pyridine, J= 7.4 Hz, J= 4.8 Hz), 8.30 (d, 1H, H
α
vinylic, J= 16.4
-pyridine,
a
-pyridine); C NMR (DMSO-
β
3
benzofuran), 9.24 (d, 1H, H
d
1
3
b
1
5
33.6, 137.9, 141.8, 143.6, 146.2, 150.2, 155.2, 164.8, 171.5. Anal. Calcd for C H BrN O : C,
23 17 2 4
9.37; H, 3.68; N, 6.02. Found: C, 59.24; H, 3.57; N, 6.24.
5
.1.3.5.
(E)-3-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(2,5-difluorobenzyl)pyridinium
bromide (6e). From compound 4a (R= H, 1.0 mmol, 0.249 g) and 2,5-difluorobenzyl bromide
(1.2 mmol, 0.248 g), for 2 h, product 6e was obtained, yield 85%, white solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) ν : 2923, 2854 (CH ), 1739 (C=O), 1638 (C=C alkene); H NMR (DMSO-d , 400
max
2
6
+
MHz), 5.95 (s, 2H, -CH N ), 7.78-7.70 (m, 3H, phenyl), 7.90 (d, 1H, H vinylic, J= 16.0 Hz),
2
α
13

ACCEPTED MANUSCRIPT
7
5 6
.50 (t, 1H, H benzofuran, J= 7.4 Hz), 7.60 (t, 1H, H benzofuran, J= 7.4 Hz), 7.78 (m, 2H, H4,7
benzofuran), 7.95 (d, 1H, Hα vinylic, J= 16.0 Hz), 8.29 (m, 1H, H -pyridine), 8.44 (d, 1H, H
c
β
vinylic, J= 16.0 Hz), 8.55 (s, 1H, H benzofuran), 9.12 (d, 1H, H - pyridine, J= 7.0 Hz), 9.24 (d,
3
d
1
3
1
1
1
3
H, H - pyridine, J= 5.4 Hz), 9.76 (s, 1H, H - pyridine), C NMR (DMSO-d 100 MHz) δ: 89.1,
b a 6,
09.2, 114.1, 116.6, 117.0, 120.9, 123.3, 124.7, 126.3, 127.3, 127.8, 129.8, 137.0, 143.0, 143.6,
45.1, 150.2, 155.2, 157.4, 163.5, 169.2, 177.8. Anal. Calcd for C H BrF NO : C, 60.54; H,
2
3
16
2
2
.53; N, 3.07. Found: C, 60.18; H, 3.87; N, 2.83.
5
.1.3.6. (E)-1-Benzyl-3-(3-(5-bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)pyridinium bromide
(6f). From compound 4b (R= 5-Br, 1.0 mmol, 0.328 g) and benzyl bromide (1.2 mmol, 0.205 g),
-1
for 3 h, product 6f was obtained, yield 73%, orange solid, mp > 300 ºC; IR (KBr, cm ) νmax:
1
2
928, 2855 (CH ), 1740, 1661 (C=O), 1608 (C=C alkene); H NMR (DMSO-d , 400 MHz), 5.90
2
6
+
(
s, 2H, -CH N ), 7.50-7.44 (m, 3H, 3H phenyl), 7.61 (d, 2H, 2H phenyl, J= 8.0 Hz ), 7.72 (d, 1H,
2
H
7
benzofuran, J= 7.8 Hz), 7.78-7.74 (dd, 1H, H
H, H vinylic, J= 15.6 Hz), 8.19 (d, 1H, H benzofuran, J= 2.0 Hz), 8.24 (d, 1H, H
5.6 Hz), 8.31 (m, 1H, H -pyridine), 8.31 (s, 1H, H benzofuran), 9.16 (d, 1H, H -pyridine, J=
.4 Hz), 9.23 (d, 1H, H -pyridine, J= 5.4 Hz), 9.80 (s, 1H, H -pyridine); C NMR (DMSO-d ,
6
benzofuran, J= 7.8 Hz and J= 2.0 Hz), 7.92 (d,
1
α
4
β
vinylic, J=
1
c
3
d
1
3
7
b
a
6
1
00 MHz) δ: 64.1, 114.9, 116.1, 117.0, 126.7, 128.1, 128.9, 129.3, 129.4, 129.7, 129.9, 132.2,
1
34.3, 135.4, 136.5, 144.3, 145.5, 154.0, 154.7, 178.0. Anal. Calcd for C H Br NO : C, 55.34;
2
3
17
2
2
H, 3.43; N, 2.81. Found: C, 55.57; H, 3.37; N, 3.06.
5
.1.3.7. (E)-3-(3-(5-Bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(2-fluorobenzyl)pyridinium
chloride (6g). From compound 4b (R= 5-Br, 1.0 mmol, 0.328 g) and 2-fluorobenzyl chloride
(1.2 mmol, 0.173 g), for 3 h, product 6g was obtained, yield 84%, white solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) ν : 2922, 2851 (CH ), 1749 (C=O), 1637 (C=C alkene); H NMR (DMSO-d , 400
max
2
6
14

ACCEPTED MANUSCRIPT
+
MHz), 6.03 (s, 2H, -CH
2
-N ), 7.37-7.31 (m, 2H, H6,7 benzofuran), 7.53 (m, 1H, 1H Phenyl), 7.72
(
m, 1H, 1H Phenyl), 7.78 (m, 1H, 1H phenyl), 7.95 (d, 1H, H vinylic, J= 15.6 Hz), 8.19 (d, 1H,
α
H benzofuran, J= 1.2 Hz), 8.30 (m, 1H, 1H phenyl), 8.38 (d, 1H, H vinylic, J= 15.6 Hz), 8.46
4
β
(
s, 1H, H benzofuran), 9.18 (d, 1H, H -pyridine, J= 7.4 Hz), 9.21 (d, 1H, H -pyridine, J= 5.5
3 d b
13
Hz), 9.95 (s, 1H, H -pyridine); C NMR (DMSO-d , 100 MHz) δ: 53.3, 110.1, 114.1, 115.6,
a
6
1
1
18.5, 121.3, 124.2, 124.7, 127.3, 129.8, 130.5, 130.6, 136.3,137.0, 143.0, 143.6, 145.1, 150.2,
55.2, 159.5, 172.4, 178.5. Anal. Calcd for C23 16BrClFNO : C, 58.44; H, 3.41; N, 2.96. Found:
H
2
C, 58.27; H, 3.69; N, 3.09.
5
.1.3.8. (E)-3-(3-(5-Bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(2-bromobenzyl)pyridinium
bromide (6h). From compound 4b (R= 5-Br, 1.0 mmol, 0.328 g) and 2-bromobenzyl bromide
(1.2 mmol, 0.300 g), for 2 h, product 6h was obtained, yield 77%, yellow solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) ν : 2905, 2850 (CH ), 1740, 1663 (C=O), 1609 (C=C alkene); H NMR (DMSO-
max 2
+
d
6
, 400 MHz), 6.03 (s, 2H, -CH
2
N ), 7.39 (d, 1H, 1H phenyl, J= 7.6 Hz), 7.64-7.42 (m, 1H
benzofuran, J= 7.6 Hz), 7.75 (d, 1H, H
benzofuran, J= 7.6 Hz), 7.80-7.77 (m,1H, 1H phenyl), 7.95 (d, 1H, H vinylic, J= 15.6 Hz), 8.19
s, 1H, H benzofuran), 8.28 (d, 1H, H vinylic, J= 15.6 Hz), 8.32 (dd, 1H, H -pyridine, J= 7.0
phenyl), 7.53-7.49 (m, 1H phenyl), 7.73 (d, 1H, H
7
6
α
(
4
β
c
Hz, J= 5.4 Hz), 8.35 (s, 1H, H benzofuran), 9.11 (d, 1H, H -pyridine, J= 7.0 Hz), 9.24 (d, 1H,
3
d
1
3
H -pyridine, J= 5.4 Hz), 9.75 (s, 1H, H -pyridine); C NMR (DMSO-d , 100 MHz) δ: 64.1,
b
a
6
1
15.0, 116.1, 117.0, 123.8, 126.7, 128.3, 128.8, 129.1, 129.3, 131.7, 131.9, 132.2, 133.2, 133.8,
35.4, 136.5, 144.7, 146.0, 146.1, 154.0, 154.7, 178.1. Anal. Calcd for C H Br NO : C, 47.79;
1
2
3
16
3
2
H, 2.79; N, 2.42. Found: C, 48.04; H, 2.94; N, 2.64.
5
.1.3.9. (E)-3-(3-(5-Bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(4-bromobenzyl)pyridinium
bromide (6i). From compound 4b (R= 5-Br, 1.0 mmol, 0.328 g) and 4-bromobenzyl bromide
15

ACCEPTED MANUSCRIPT
(1.2 mmol, 0.300 g), for 2 h, product 6i was obtained, yield 80%, yellow solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) ν : 2905, 2851 (CH ), 1731, 1663 (C=O), 1609 (C=C alkene); H NMR (DMSO-
max
2
+
d , 400 MHz), 5.99 (s, 2H, -CH N ), 7.67 (m, 4H, 2H phenyl and H benzofuran), 7.78-7.72 (m,
6
2
6,7
2
H, 2H Phenyl), 7.90 (d, 1H, Hα vinylic, J= 15.6 Hz), 8.15 ( s, 1H, H benzofuran), 8.29 (m, 1H,
4
H -pyridine), 8.41 (d, 1H, H vinylic, J= 15.6 Hz), 8.56 (s, 1H, H benzofuran), 9.18 (d, 1H, H -
c
β
3
d
1
3
pyridine, J= 7.2 Hz), 9.31 (d, 1H, H -Pyridine, J= 5.2 Hz), 10.16 (s, 1H, H -pyridine); C NMR
b
a
6
(DMSO-d , 100 MHz) δ: 62.3, 113.7, 116.4, 116.6, 120.1, 124.1, 127.3, 129.8, 130.5, 131.2,
1
31.5, 133.4, 133.6, 137.0, 143.0, 143.6, 145.1, 150.2, 155.2, 159.5, 177.8. Anal. Calcd for
C
23
H
16Br
3
NO
2
: C, 47.79; H, 2.79; N, 2.42. Found: C, 48.01; H, 2.90; N, 2.21.
5
.1.3.10.
(E)-3-(3-(5-Bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(2,3-dichlorobenzyl)
pyridinium chloride (6j). From compound 4b (R= 5-Br, 1.0 mmol, 0.328 g) and 2,3-
dichlorobenzyl chloride (1.2 mmol, 0.234 g), for 4 h, product 6j was obtained, yield 75%, light
-1
yellow solid, mp > 300 ºC; IR (KBr, cm ) νmax: 2914 (CH
2
), 1740, 1661 (C=O), 1609 (C=C
1
+
alkene); H NMR (DMSO-d
6
, 400 MHz), 6.12 (s, 2H, -CH
2
N ), 7.47 (d, 1H, H
7
benzofuran, J=
benzofuran), 7.95 (d,
H, H vinylic, J= 15.6 Hz), 8.19 (d, 1H, H benzofuran, J= 1.2 Hz), 8.32 (dd, 1H, H -pyridine,
7
1
.2 Hz),7.51-7.46 (m ,1H, 1H phenyl) 7.80-7.75 (m, 3H, 2H phenyl and H
6
α
4
c
J= 7.0 Hz, J= 4.8 Hz), 8.36 (d, 1H, H vinylic, J= 15.6 Hz), 8.44 (s, 1H, H benzofuran), 9.16 (d,
β
3
1
3
1
H, H -pyridine, J= 7.0 Hz), 9.26 (d, 1H, H -pyridine, J= 4.8 Hz), 9.85 (s, 1H, H -pyridine);
C
d
b
a
NMR (DMSO-d , 100 MHz) δ: 62.6, 115.0, 116.2, 117.0, 126.4, 126.7, 128.4, 128.8, 129.3,
6
1
1
2
29.5,130.4, 131.4, 131.8, 132.0, 132.2, 133.0, 134.1, 135.4, 136.5, 144.8, 146.0, 154.0, 154.7,
78.1. Anal. Calcd for C23
.53.
3 2
H15BrCl NO : C, 52.76; H, 2.89; N, 2.67. Found: C, 52.98; H, 3.11; N,
16

ACCEPTED MANUSCRIPT
5
.1.3.11.
(E)-3-(3-(5-Bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(3,4-dichlorobenzyl)
pyridinium chloride (6k). From compound 4b (R= 5-Br, 1.0 mmol, 0.328 g) and 3,4-
dichlorobenzyl chloride (1.2 mmol, 0.234 g), for 4 h, product 6k was obtained, yield 79%, light
-1
yellow solid, mp > 300 ºC; IR (KBr, cm ) ν : 2917, 2854 (CH ), 1738, 1660 (C=O), 1612
max
2
1
+
(
C=C alkene); H NMR (DMSO-d , 400 MHz), 5.95 (s, 2H, -CH N ), 7.78-7.70 (m, 4H, 2H
6
2
phenyl and H , benzofuran), 7.91 (d, 1H, H vinylic, J= 16.0 Hz), 8.07 (d, 1H phenyl, J= 7.6
6
7
α
Hz), 8.17 (d, 1H, H
4
c β
benzofuran, J= 1.2 Hz), 8.29 (m, 1H, H -pyridine), 8.39 (d, 1H, H vinylic,
J= 16.0 Hz), 8.48 (s, 1H, H
3
benzofuran), 9.16 (d, 1H, H
d
-pyridine, J= 8.0 Hz), 9.28 (d, 1H, H
-pyridine); C NMR (DMSO-d , 100 MHz) δ: 62.3, 115.0,
16.3, 117.0, 126.7, 128.3, 128.9, 129.4, 130.1, 131.7, 132.0,132.1, 132.2, 132.8, 135.0, 135.5,
b
-
1
3
pyridine, J= 5.5 Hz), 10.07 (s, 1H, H
a
6
1
1
4
+
+
36.6, 144.5, 145.5, 145.8, 154.1, 154.7, 178.1. EI-MS m/z (%) 493 (M +6, 1), 491 (M +4, 4),
+
+
89 (M +2, 9), 487 (M , 7), 327 (83), 300 (44), 262 (12), 250 (26), 238 (12), 225 (27), 159
(
100), 77 (22). Anal. Calcd for C H BrCl NO : C, 52.76; H, 2.89; N, 2.67. Found: C, 52.49, H,
23 15 3 2
3
.04, N, 2.39.
5
.1.3.12.
(E)-1-Benzyl-3-(3-(7-methoxybenzofuran-2-yl)-3-oxoprop-1-en-1-yl)pyridinium
bromide (6l). From compound 4c (R= 7-OMe, 1.0 mmol, 0.279 g) and benzyl bromide (1.2
mmol, 0.234 g), for 3 h, product 6l was obtained, yield 70%, light yellow solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) ν : 2923, 2854 (CH ), 1752, 1665 (C=O), 1613 (C=C alkene); H NMR (DMSO-
max 2
+
d , 400 MHz), 3.97 (s, 3H, -OCH ), 6.05 (s, 2H, -CH N ), 7.19 (d, 1H, H benzofuran, J= 8.0
6
3
2
6
Hz), 7.32 (t, 1H, H benzofuran, J= 8.0 Hz), 7.44-7.41 (m, 4H, 3H phenyl and H benzofuran),
5
4
7
1
.73 (dd, 2H, 2H phenyl, J= 7.0 Hz, J= 2.0 Hz), 7.90 (d, 1H, H
α
vinylic, J= 16.0 Hz), 8.28 (dd,
c β 3
H, H -pyridine, J= 8.0 Hz, J= 5.5 Hz), 8.49 (d, 1H, H vinylic, J= 16.0 Hz), 8.73 (s, 1H, H
benzofuran). 9.19 (d, 1H, H -pyridine, J= 8.0 Hz), 9.34 (d, 1H, H -pyridine, J= 5.5Hz), 10.34, (s,
d
b
17

ACCEPTED MANUSCRIPT
1
3
1
a 6
H, H -pyridine); C NMR (DMSO-d , 100 MHz) δ: 56.2, 62.3, 107.4, 111.7, 114.3, 116.2,
1
17.8, 125.7, 127.3, 128.5, 129.0, 129.6, 134.5, 135.7, 143.0, 143.6, 145.3, 145.8, 150.2, 151.5,
58.1, 175.9. Anal. Cald for C H BrNO : C, 64.01; H, 4.48; N, 3.11. Found: C, 63.80; H, 4.71;
1
2
4
20
3
N, 3.30
5
.1.3.13.
(E)-1-(2-Bromobenzyl)-3-(3-(7-methoxybenzofuran-2-yl)-3-oxoprop-1-en-1-
yl)pyridinium bromide (6m). From compound 4c (R= 7-OMe, 1.0 mmol, 0.279 g) and 2-
bromobenzyl bromide (1.2 mmol, 0.234 g), for 2 h, product 6m was obtained, yield 78%, light
-1
yellow solid, mp > 300 ºC; IR (KBr, cm ) ν : 2933 (CH ), 1757, 1662 (C=O), 1611 (C=C
max
2
1
+
alkene); H NMR (DMSO-d , 400 MHz), 3.36 (s, 3H, -OCH ), 6.06 (s, 2H, -CH N ), 7.20 (d,
6
3
2
1
H, H benzofuran, J= 8.0 Hz), 7.33 (t, 1H, H benzofuran, J= 8.0 Hz), 7.46-7.41 (m, 3H, 3H
6 5
Phenyl), 7.52-7.48 (m, 1H, 1H Phenyl), 7.78 (d, 1H, H benzofuran, J= 8.0Hz), 7.94 (d, 1H, Hα
4
vinylic, J= 15.6 Hz), 8.31 (d, 1H, H vinylic, J= 15.6 Hz), 8.33 (dd, 1H, H -pyridine, J= 8.0 Hz,
β
c
J= 5.5 Hz), 8.47 (s, 1H, H
3
benzofuran), 9.10 (d, 1H, H
d
b
-pyridine, J= 8.0 Hz), 9.25 (d, 1H, H -
1
3
a 6
pyridine, J= 5.5 Hz), 9.83 (s, 1H, H -pyridine); C NMR (DMSO-d , 100 MHz) δ: 56.4, 46.0,
1
11.1, 115.9, 117.6, 123.8, 125.6, 128.5, 128.7, 128.8, 129.1, 131.8, 131.9, 133.2, 133.8, 135.4,
36.2, 144.8, 145.6, 145.8, 145.9, 146.0, 153.2, 177.9. Anal. Calcd for C H Br NO : C, 54.47;
1
2
4
19
2
3
H, 3.62; N, 2.65. Found: C, 54.30; H, 3.38; N, 2.97.
5
.1.3.14.
(E)-1-(4-Bromobenzyl)-3-(3-(7-methoxybenzofuran-2-yl)-3-oxoprop-1-en-1-
yl)pyridinium bromide (6n). From compound 4c (R= 7-OMe, 1.0 mmol, 0.279 g) and 4-
bromobenzyl bromide (1.2 mmol, 0.234 g), for 2 h, product 6n was obtained, yield 75%, orange
-1
solid, mp > 300 ºC; IR (KBr, cm ) νmax: 2929, 2847 (CH
2
), 1720, 1665 (C=O), 1613 (C=C
1
+
alkene); H NMR (DMSO-d , 400 MHz), 3.97 (s, 3H, -OCH ), 6.03 (s, 2H, -CH N ), 7.19 (d,
6
3
2
1
H, H benzofuran, J= 7.6 Hz), 7.32 (t, 1H, H benzofuran, J= 7.6 Hz), 7.42 (d, 1H, H
6 5 4
18

ACCEPTED MANUSCRIPT
benzofuran, J= 7.6 Hz), 7.65 (d, 2H, 2H Phenyl, J= 8.4 Hz), 7.71 (d, 2H, 2H Phenyl, J= 8.4 Hz),
7
.89 (d, 1H, H vinylic, J= 15.6 Hz), 8.28 (m, 1H, H -pyridine), 8.46 (d, 1H, H vinylic, J= 15.6
α c β
Hz), 8.69 (s, 1H, H benzofuran), 9.18 (d, 1H, H -pyridine, J= 8.0 Hz), 9.31 (d, 1H, H -pyridine,
3
d
b
1
3
J=5.5 Hz), 10.27 (s, 1H, H -pyridine); C NMR (DMSO-d , 100 MHz) δ: 58.5, 62.6, 111.2,
a
6
1
1
15.8, 118.0, 123.4, 125.6, 128.5, 128.7, 128.9, 131.9, 132.5, 133.8, 135.4, 136.2, 144.9, 145.2,
+
45.6, 145.9, 153.2, 177.9. EI-MS m/z (%) 450 (M +2, 10), 448 (M , 11), 434 (9), 417 (16), 369
(42), 353 (10), 339 (23), 313 (32), 279 (100), 264 (49), 250 (51), 236 (42). Anal. Calcd for
C
24
H
19Br
2
NO
3
: C, 54.47; H, 3.62; N, 2.65. Found: C, 54.36; H, 3.44; N, 2.83.
5
.1.3.15.
(E)-1-(4-Chlorobenzyl)-3-(3-(7-methoxybenzofuran-2-yl)-3-oxoprop-1-en-1-
yl)pyridinium chloride (6o). From compound 4c (R= 7-OMe, 1.0 mmol, 0.279 g) and 4-
chlorobenzyl chloride (1.2 mmol, 0.234 g), for 3 h, product 6o was obtained, yield 70%, light
-1
yellow solid, mp > 300 ºC; IR (KBr, cm ) ν : 2924, 2856 (CH ), 1731, 1661 (C=O), 1624
max
2
1
+
(
C=C alkene); H NMR (DMSO-d
6
, 400 MHz), 3.34 (s, 3H, -OCH
3
2
), 5.95 (s, 2H, -CH N ), 7.21
(
d, 1H, H
6
5 4
benzofuran, J= 7.6 Hz), 7.34 (t, 1H, H benzofuran, J= 7.6 Hz), 7.45 (d, 1H, H
benzofuran, J= 7.6 Hz), 7.54 (d, 2H, 2H Phenyl, J= 8.4 Hz), 7.74 (d, 2H, 2H Phenyl, J= 8.4 Hz),
.91 (d, 1H, H vinylic, J= 16.0 Hz), 8.30 (dd, 1H, H -pyridine, J= 8Hz, J= 5.5 Hz), 8.44 (d, 1H,
7
α
c
H vinylic, J= 16.0 Hz), 8.59 (s, 1H, H benzofuran), 9.14 (d, 1H, H -pyridine, J= 8 Hz), 9.26 (d,
β
3
d
1
3
1
5
1
3
H, H -pyridine, J= 5.5 Hz),10.19 (s, 1H, H -pyridine); C NMR (DMSO-d , 100 MHz) δ: 53,
b a 6
6.1, 108.9, 113.2, 125.4, 127.3, 128.4, 129.0, 132.4, 133.6, 135.9, 137.0, 141.5, 142.4, 143.0,
44.9, 145.1, 151.5, 155.2, 157.5, 177.8. Anal. Calcd for C H Cl NO : C, 65.47; H, 4.35; N,
24
19
2
3
.18. Found: C, 65.74; H, 4.24; N, 3.39.
5
.1.3.16.
(E)-1-(2,3-Dichlorobenzyl)-3-(3-(7-methoxybenzofuran-2-yl)-3-oxoprop-1-en-1-
yl)pyridinium chloride (6p). From compound 4c (R= 7-OMe, 1.0 mmol, 0.279 g) and 2,3-
19

ACCEPTED MANUSCRIPT
dichlorobenzyl chloride (1.2 mmol, 0.234 g), for 4 h, product 6p was obtained, yield 75%,
-1
yellow solid, mp > 300 ºC; IR (KBr, cm ) ν : 2924, 2852 (CH ), 1745, 1664 (C=O), 1613
max
2
1
+
(
C=C alkene); H NMR (DMSO-d , 400 MHz), 3.98 (s, 3H, -OCH ), 6.12 (s, 2H, -CH N ), 7.20
6 3 2
(
d, 1H, H benzofuran, J= 7.8 Hz), 7.34 (t, 1H, H benzofuran, J= 7.8 Hz), 7.52-7.44 (m, 3H, 2H
6
5
phenyl and H benzofuran), 7.79 (m, 1H, Ph), 7.94 (d, 1H, H vinylic, J= 15.6 Hz), 8.32 (dd, H -
4
α
c
pyridine, J= 8.0 Hz, J= 5.5 Hz), 8.37 (d, 1H, H vinylic, J= 15.6 Hz), 8.51 (s, 1H, H
β
3
benzofuran), 9.15 (d, 1H, H
d
-pyridine, J= 7.5 Hz), 9.25 (d, 1H, H
b
-pyridine, J= 5.5 Hz), 9.89 (s,
1
3
1
1
1
2
3
H, H
a
-pyridine); C NMR (DMSO-d , 100 MHz) δ: 56.4, 62.1, 111.1, 115.9, 117.6, 125.6,
6
28.3, 128.6, 128.7, 128.8, 129.5, 130.4, 131.7, 132.0, 133.0, 134.2, 135.5, 136.2, 144.8, 145.6,
+
45.9, 146.1, 153.2, 178.0. EI-MS m/z (%) 444 (M +4, 1), 442 (M +2, 3), 440 (M , 4), 308 (22),
79 (100), 236 (11), 175 (14), 159 (99), 148 (3). Anal. Calcd for C H Cl NO : C, 60.72; H,
2
4
18
3
3
.82; N, 2.95. Found: C, 60.41; H, 3.91; N, 2.62.
5
.1.3.17. (E)-4-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-benzylpyridinium bromide (6q).
From compound 5a (R= H, 1.0 mmol, 0.249 g) and benzyl bromide (1.2 mmol, 0.205 g), for 3 h,
-1
product 6q was obtained, yield 70%, orange solid, mp > 300 ºC, IR (KBr, cm ) νmax: 2922, 2853
1
(
CH ), 1743, 1664 (C=O), 1635 (C=C alkene), H NMR (DMSO-d , 400 MHz), 5.92 (s, 2H, -
2
6
+
CH N ), 7.44 (m, 3H, 3H phenyl), 7.61 (d, 2H, 2H phenyl, J= 7.2 Hz), 7.79-7.73 (m, 2H, H
2
5,6
benzofuran), 7.92 (d, 1H, H vinylic, J= 15.6 Hz), 7.94 (d, 1H, H benzofuran, J= 7 Hz), 8.20 (d,
α
7
1
8
d
1
H, H benzofuran, J= 7.2 Hz), 8.43 (d, 1H, H vinylic, J= 15.6 Hz), 8.51 (s, 1H, H benzofuran),
4 β 3
1
3
.68 (d, 2H, H - pyridine, J= 5.5 Hz), 9.41 (d, 2H, H - pyridine, J= 5.5 Hz); C NMR (DMSO-
b
a
6
, 100 MHz) δ: 63.2, 115.0, 117.0, 120.9, 123.3, 124.7, 124.8, 125.7, 127.3, 127.8, 129.3, 129.6,
31.9, 137.6, 145.5, 155.2, 157.0, 160.5, 177.8. Anal. Calcd for C23 : C, 65.73; H, 4.32;
H18BrNO
2
N, 3.33. Found: C, 66.03; H, 4.66; N, 3.65.
20

ACCEPTED MANUSCRIPT
5
.1.3.18.
(E)-4-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(2-bromobenzyl)pyridinium
bromide (6r). From compound 5a (R= H, 1.0 mmol, 0.249 g) and 2-bromobenzyl bromide (1.2
mmol, 0.300 g), for 2 h, product 6r was obtained, yield 75%, dark yellow solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) ν : 2940, 2858 (CH ), 1723, 1663 (C=O), 1634 (C=C alkene); H NMR (DMSO-
max
2
+
d , 400 MHz), 6.00 (s, 2H, -CH N ), 7.38 (d, 1H, 1H phenyl, J= 7.6 Hz), 7.42 (t, 2H, 2H phenyl,
6
2
J= 7.6 Hz), 7.50 (t, 1H, H benzofuran, J= 7.6 Hz), 7.61 (t, 1H, H benzofuran, J= 7.4 Hz), 7.78
5
6
(
m, 2H, 1H phenyl and H
benzofuran, J= 8.0 Hz), 8.44 (d, 1H, H
d, 2H, H -pyridine, J= 5.8 Hz), 9.21 (d, 2H, H
7
benzofuran), 7.94 (d, 1H, H
α
vinylic, J= 15.6 Hz), 7.94 (d, 1H, H
4
β
vinylic, J= 15.6 Hz), 8.54 (s, 1H, H
3
benzofuran), 8.68
1
3
(
b
a
-pyridine, J= 5.8 Hz); C NMR (DMSO-d , 100
6
MHz) δ: 63.4, 112.8, 118.0, 123.7, 124.6, 124.9, 127.1, 127.2, 129.1, 130.0, 131.6, 131.9, 132.6,
+
1
6
5
33.6, 133.8, 137.0, 146.1, 151.2, 153.1, 156.1, 177.9. EI-MS m/z (%) 420 (M +2, 4), 418 (M ,
), 169 (41), 152 (100), 118 (59), 89 (51), 63 (32), 43 (38). Anal. Calcd for C H Br NO : C,
2
3
17
2
2
5.34; H, 3.43; N, 2.81. Found: C, 55.21; H, 3.72; N, 2.98.
5
.1.3.19. (E)-4-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(4-fluorobenzyl)pyridinium chloride
(6s). From compound 5a (R= H, 1.0 mmol, 0.249 g) and 4-fluorobenzyl chloride (1.2 mmol,
-1
0
.173 g), for 3 h, product 6s was obtained, yield 82%, white solid, mp > 300 ºC; IR (KBr, cm )
1
νmax: 2954, 2918 (CH ), 1738, 1684 (C=O), 1643 (C=C alkene); H NMR (DMSO-d , 400 MHz),
2
6
+
5
7
.94 (s, 2H, -CH N ), 7.21 (d, 2H, 2H phenyl, J= 7.6 Hz), 7.23 (t, 1H, H benzofuran, J= 7.6 Hz),
2 5
.39 (t,1H, H benzofuran, J= 7.6 Hz), 7.59-7.64 (m, 2H, H benzofuran), 7.69 (d, 2H, 2H
6
4,7
phenyl, J= 7.6 Hz), 7.80 (d, 1H, H vinylic, J= 15.6 Hz), 8.10 (d, 1H, H vinylic, J= 15.6 Hz),
α
β
8
5
.50 (s, 1H, H
3
benzofuran), 8.66 (d, 2H, H
b
a
- pyridine, J= 5.8 Hz), 9.01 (d, 2H, H - pyridine, J=
1
3
6
.8 Hz), C NMR (DMSO-d , 100 MHz) δ: 65.4, 111.5, 114.0, 116.6, 120.9, 122.6, 124.7,
21

ACCEPTED MANUSCRIPT
1
24.8, 127.3, 127.8, 130.0, 130.6, 145.1, 146.3, 153.6, 157.0, 159.9, 160.5, 177.8. Anal. Calcd
for C H ClFNO : C, 70.14; H, 4.35; N, 3.56. Found: C, 69.96; H, 4.57; N, 3.23.
2
3
17
2
5
.1.3.20.
(E)-4-(3-(Benzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(2,3-dichlorobenzyl)pyridinium
chloride (6t). From compound 5a (R= H, 1.0 mmol, 0.249 g) and 2,3-dichlorobenzyl chloride
(1.2 mmol, 0.234 g), for 4 h, product 6t was obtained, yield 73%, orange solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) νmax: 2964 (CH
2
), 1708, 1658 (C=O), 1633 (C=C alkene); H NMR (DMSO-d
6
, 400
+
MHz), 6.07 (s, 2H, -CH
2
N ), 7.43-7.38 (m, 2H phenyl), 7.48 (t, 1H, H
5
benzofuran, J= 7.6 Hz),
7
7
.62 (t, 1H, H benzofuran, J= 7.6 Hz), 7.78 (d, 2H, 1H phenyl and H benzofuran, J= 7.6 Hz),
6 7
.95 (d, 1H, H benzofuran, J= 7.6 Hz), 7.95 (d, 1H, H vinylic, J= 15.6 Hz), 8.48 (d, 1H, H
β
4
α
vinylic, J= 15.6 Hz), 8.57 (s, 1H, H benzofuran), 8.69 (d, 2H, H pyridine, J= 5.5 Hz), 9.24 (d,
3
b
1
3
2
1
1
3
H, H pyridine, J= 5.5 Hz); C NMR (DMSO-d , 100 MHz) δ: 61.6, 112.8, 118.1, 124.6, 124.9,
a 6
27.2, 129.5, 130.0, 130.1, 131.6, 131.9, 132.7, 133.0, 134.6, 137.0, 146.1, 151.3, 153.1, 156.1,
78.0. Anal. Calcd for C23
.44.
3 2
H16Cl NO : C, 62.12; H, 3.63; N, 3.15. Found: C, 62.33; H, 3.39; N,
5
.1.3.21. (E)-1-Benzyl-4-(3-(5-bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)pyridinium bromide
(6u). From compound 5b (R= 5-Br, 1.0 mmol, 0.328 g) and benzyl bromide (1.2 mmol, 0.205 g),
-1
for 3 h, product 6u was obtained, yield 71%, yellow solid, mp > 300 ºC; IR (KBr, cm ) νmax:
1
2
924, 2858 (CH ), 1740, 1657 (C=O), 1636 (C=C alkene); H NMR (DMSO-d , 400 MHz), 5.87
2
6
+
(
s, 2H, -CH
2
N ), 7.43 (t, 1H, 1H phenyl, J= 7.6 Hz), 7.57 (d, 2H, 2H phenyl, J= 8.4 Hz), 7.62 (t,
H, 1H phenyl, J= 7.6 Hz), 7.67 (m, 2H, 1H phenyl and H benzofuran,), 7.77 (d, 1H, H
vinylic, J= 16.0 Hz), 7.94 (s, 1H, H benzofuran,), 8.42
d, 1H, H vinylic, J= 16.0 Hz), 8.54 (s, 1H, H benzofuran), 8.66 (d, 2H, H -pyridine, J= 5.2
1
6
7
benzofuran, J= 8.4 Hz), 7.91 (d, 1H, H
α
4
(
β
3
b
1
3
Hz), 9.34 (d, 2H, H -pyridine, J= 5.2 Hz); C NMR (DMSO-d , 100 MHz) δ: 62.53, 112.8,
a
6
22

ACCEPTED MANUSCRIPT
1
1
3
18.0, 123.3, 124.6, 124.9, 127.2, 130.0, 131.5, 132.4, 132.5, 137.0, 145.6, 150.9, 156.1, 159.9,
77.9. Anal. Calcd for C H Br NO : C, 55.34; H, 3.43; N, 2.81. Found: C, 55.43, H, 3.69, N,
2
3
17
2
2
.14.
5
.1.3.22. (E)-4-(3-(5-Bromobenzofuran-2-yl)-3-oxoprop-1-en-1-yl)-1-(4-fluorobenzyl)pyridinium
chloride (6v). From compound 5b (R= 5-Br, 1.0 mmol, 0.328 g) and 4-fluorobenzyl chloride (1.2
mmol, 0.173g), for 3 h, product 6v was obtained, yield 82%, dark yellow solid, mp > 300 ºC; IR
-1
1
(
KBr, cm ) νmax: 2924, 2847 (CH
2
), 1751, 1663 (C=O), 1637 (C=C alkene); H NMR (DMSO-
+
d , 400 MHz), 5.87 (s, 2H, -CH N ), 7.31 (m, 2H, 2H Phenyl),7.70 (m, 2H, 2H phenyl), 7.80-
6
2
7
.76 (m, 2H, H benzofuran), 7.92 (d, 1H, H vinylic, J= 15.6 Hz), 8.21 (d, 1H, H benzofuran,
6,7 α 4
J= 1.6 Hz), 8.43 (d, 1H, H vinylic, J= 15.6 Hz), 8.47 (s, 1H, H benzofuran), 8.65 (d, 2H, H -
β
3
b
13
pyridine, J= 5.5 Hz), 9.36 (d, 2H, H -pyridine, J= 5.5 Hz); C NMR (DMSO-d , 100 MHz) δ:
a
6
6
1
2.5, 115.0, 116.4, 116.7, 116.8, 117.0, 126.9, 127.3, 129.3, 131.8, 131.9, 132.2, 132.4, 137.4,
45.5, 150.7, 154.0, 154.8, 178.0. Anal. Calcd for C23 16BrClFNO : C, 58.44; H, 3.41; N, 2.96.
H
2
Found: C, 58.18; H, 3.49; N, 3.22.
5
.2. Cholinesterase inhibition assay
Electric-eel (Torpedo californica) AChE (type VI-S), acetylthiocholine iodide, 5,5’-dithiobis [2-
nitrobenzoic acid] (DTNB), and donepezil were obtained from Sigma-Aldrich (Steinheim,
Germany). To measure AChE inhibiting activities the slightly modified Ellman method was used
[21]. All the compounds with the exception of 6e, 6g, 6s, and 6v were dissolved in the mixture of
methanol/DMSO (4/1) and then diluted in the phosphate buffer (0.1 M, pH= 8) to obtain desired
assay concentrations. Compounds 6e, 6g, 6s, and 6v were not soluble in the assay conditions and
23

ACCEPTED MANUSCRIPT
not tested. The assay concentrations were prepared in such a way that produced the inhibition in
the range of 20-80 %. The reaction mixture contained 3 ml of potassium phosphate buffer,
1
00µL of DTNB, 50 µl of compound solution and 50 µl of enzyme which were mixed and
incubated for 15 min at 25°C. The reaction was then started by the addition of 10 µl
acetylthiocholine. The hydrolysis rate of acetylthiocholine was determined at 412 nm through
measuring the yellow 5-thio-2-nitrobenzoate anion resulting from enzyme catalysis. To compare
the potency of the compounds, donepezil hydrochloride was used as the positive control. The
obtained data was then further analyzed by GraphPad Prism version 6 for Windows (GraphPad
Software, San Diego California USA, www.graphpad.com) to achieve IC50 values (mean ± S.E.).
5
.3. Docking study
The three-dimensional structures of compounds was constructed and optimized using the
HyperChem7 (Hypercube, Inc.). Energy minimization was performed with a distance gradient
algorithm with convergence criterion of 0.05 kcal/(mol.Å) and a maximum of 1000 inter-actions,
respectively. The Autodock 4.0 [27] was applied to dock compounds in the aromatic gorge of
AChE co-crystallized with N-saccharinohexyl-galanthamine (PDB id; 3I6Z). The geometric
center of the ligand was used to define the active site interactions points. The docking result was
analyzed by Accelrys Discovery Studio Visualizer 3.0 (AccelrysSoftware Inc., San Diego).
24

ACCEPTED MANUSCRIPT
Acknowledgments
This research has been supported by a grant from the Research Council of Tehran University of
Medical Sciences and Iran National Science Foundation (INSF).
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[
[
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Captions:
Figure 1. Structural similarity of donepezil hydrochloride as a FDA-approved AChE inhibitor
and N-benzylpyridinium chalconoids derived from coumaranone, and coumarin as potent anti-
AChE agents, and benzofuran-based chalconoid as newly designed AChE inhibitors.
Figure 2. Interaction of compound 6m in the active site of AChE. Key residues are shown green.
1
Figure 3. Atom numbering of the target compounds 6a-v used for H NMR data.
Scheme 1. Synthesis of benzofuran-based chalconoids 6a-p and 6q-v bearing 3-pyridinium or 4-
pyridinium moiety.
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