Design, synthesis and AChE inhibitory activity of indanone and aurone derivatives

Article abstract of DOI:10.1016/j.ejmech.2008.03.003

A new series of indanone and aurone derivatives have been synthesized and tested for in vitro AChE inhibitory activity by modified Ellman method. Most of them exhibit AChE inhibitory activities superior to rivastigmine. Further, the most potent compound 1g was selected to evaluate the effect on the acquisition and memory impairment by mice step-down passive avoidance test.

Full text of DOI:10.1016/j.ejmech.2008.03.003

Available online at www.sciencedirect.com
European Journal of Medicinal Chemistry 44 (2009) 7e17
http://www.elsevier.com/locate/ejmech
Original article
Design, synthesis and AChE inhibitory activity of
indanone and aurone derivatives
Rong Sheng a, Yu Xu a, Chunqi Hu a, Jing Zhang b, Xiao Lin a, Jingya Li c,
Bo Yang b, Qiaojun He b, Yongzhou Hu a,
*
a ZJU-ENS joint laboratory of Medicinal Chemistry, School of Pharmaceutical Sciences, Zijingang Campus, Zhejiang University
Hangzhou 310058, People’s Republic of China
b Department of Pharmacology, School of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, People’s Republic of China
c The National Center for Drug Screening, Shanghai 201203, People’s Republic of China
Received 26 November 2007; received in revised form 6 March 2008; accepted 6 March 2008
Available online 16 March 2008
Abstract
A new series of indanone and aurone derivatives have been synthesized and tested for in vitro AChE inhibitory activity by modified Ellman
method. Most of them exhibit AChE inhibitory activities superior to rivastigmine. Further, the most potent compound 1g was selected to evaluate
the effect on the acquisition and memory impairment by mice step-down passive avoidance test.
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords: Indanone; Aurone; Synthesis; AChE inhibitory activity
1. Introduction
with two separate ligand binding sites, a catalytic site (active
site) and a peripheral anionic site (PAS) [2], the latter was
found to be related with the no-catalytic function of AChE,
accelerating b-amyloid peptide deposition and promoting the
formation of b-amyloid fibril. It was postulated that AChE
binds through its peripheral site to the nonamyloidogenic
form of Ab protein acting as a chaperone protein and inducing
conformational change to the amyloidogenic form with subse-
quent amyloid fibril formation [3e5]. Moreover, it has been
shown that molecules that were able to interact with both ac-
tive and peripheral sites of AChE could prevent the aggregat-
ing activity of AChE toward Ab besides the inhibitory activity
[6]. All these findings stimulated a great interest in designing
dual-site binding AChE inhibitors [7e9].
In our previous study, a series of 2-phenoxy-indan-1-one
derivatives were proven as potent and selective AChE inhibi-
tors in vitro (Fig. 1c), which were characterized by combining
5,6-dimethoxy-indan-1-one from donepezil (Fig. 1a) and dia-
lkylbenzyl amine from rivastigmine (Fig. 1b), with oxygen
as the linkage. The docking study reveals that these series
compounds are able to bind the active and peripheral sites
simultaneously [10]. It was reported that chalcone and aurone
Alzheimer’s disease (AD) is a progressive neurodegenera-
tive disorder and one of the most common causes of mental de-
terioration in the elderly. Considerable research efforts have
been devoted to elucidate the molecular, biochemical, and cel-
lular mechanisms of AD in the past decades. Several hypothe-
ses have been proposed attempting to explain the pathogenesis
of AD, including b-amyloid deposition, tau hyperphosphoryla-
tion, acetylcholine deficiency, inflammation, and oxidative
stress, while the etiology of this disease is not known, and in-
terventions able to halt or slow disease progression are as yet
unproven. Up to now, AChE inhibitors are still the major and
most developed class of drugs approved for AD therapy, such
as donepezil, rivastigime, and galanthamine have been ap-
proved by FDA and EMEA for the symptomatic treatment of
AD [1]. The X-ray crystallography of AChE (TcAChE) has
˚
demonstrated that it possesses a long and narrow 20 A gorge
* Corresponding author. Tel./fax: þ86 571 8820 8460.
E-mail address: huyz@zju.edu.cn (Y. Hu).
0223-5234/$ - see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.03.003

8
R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
O
with LiAlH4eEt2NH in pentane to yield key intermediate
6aej [14]. Then, the reaction of 6aej with 5,6-dimethoxy-in-
dan-1-one [15] or 5,6-dimethoxy-benzo-furan-3(2H)-one [16]
was carried out in the presence of KOH or Al2O3, to provide
1aep [17,18]. The trans-conformation of compounds 1aep
could be confirmed by the chemical shift of vinyl proton in
1H NMR, because of the deshielding effect resulting from
the carbonyl group, the vinyl protons should give a signal at
a greater chemical shift than in the cis isomer, the value is
higher than 7.0 [19]. Finally, 2aep were obtained through
catalytic hydrogenation of 1aep with 5% Pd/C as catalyst in
THF. All the newly synthesized compounds were character-
N
O
O
H3CO
H3CO
N
N
a
b
O
H3CO
H3CO
O
R2
N
R3
R1
c
Fig. 1.
1
ized by H NMR, ESIeMS and IR spectroscopy.
derivatives exhibit high binding affinity to Ab aggregates in vi-
tro [11,12], therefore, introduction of these moieties into the
molecules may increase the affinity to Ab and enhance the
therapeutic efficacy. Following these reasons, a series of new
indanone and aurone derivatives were designed, synthesized
and evaluated for ChE inhibitory activities, in which 5,6-di-
methoxy-indan-1-one was remained or replaced by its bioisos-
tere 5,6-dimethoxy-benzofuran-3(2H)-one, ]CH or eCH2
was chosen as the linkage, with different sort of aminoalkyl
groups substituted at the para or meta position of the benzene.
Besides study on the pharmacological activities of these deriv-
atives, the docking program by computational modeling was
also performed.
2.2. Biological activities
All the newly synthesized indanone and aurone derivatives
were tested for their inhibitory activities toward AChE and
BuChE in vitro according to the modified Ellman method
using rat cortex homogenate (AChE) and rat serum (BChE)
with commercially available donepezil and rivastigmine as
the reference standard [20]. The ChE inhibitory results are
summarized in Table 1.
Most of the tested compounds demonstrated higher inhibi-
tory activities against AChE than rivastigmine and high selec-
tivity for AChE over BuChE. Some general conclusions can be
drawn from the results, as follows: (1) The variation of linkage
exhibits obvious effect on the AChE inhibitory activities, com-
pounds containing ]CH linkage (i.e. 1g, 1l, 1n, 1p) were
more potent than that of containing CH2 linkage (i.e. 2g, 2l,
2n, 2p). (2) The compounds with aminomethyl at the para-
position of benzene ring (i.e. 1d, 1g, 2b, 2k) were more effec-
tive than those substituted at meta-position (1c, 1f, 2a, 2j). (3)
The compounds having dimethylamine group (i.e. 1a, 2b)
showed less activity than those having other groups (1g, 1o,
2k, 2p). (4) The change of Y did not show obvious effect on
AChE inhibition, aurone derivatives (i.e. 1l, 2i) demonstrated
similar activities to indanone derivatives (i.e. 1j, 2g).
2. Results and discussion
2.1. Chemistry
The target compounds 1aep and 2aep were synthesized as
illustrated in Scheme 1. The readily available materials methyl
3- (or 4-) methyl benzoates 3a,b were brominated with NBS
following previously reported method to give 4a,b in high
yield [13]. The obtained 4a,b reacted with various secondary
amines (dimethylamine, pyrrolidine, etc.) in CH2Cl2 at reflux
conditions to afford 5aej, followed by selective reduction
COOCH3
COOCH3
CHO
COOCH3
a
b
c
R1
R2
R1
R2
CH3
CH2N
CH2Br
CH2N
5a-j
6a-j
3a,b
4a,b
O
Y
O
Y
H3CO
H3CO
H3CO
H3CO
d
e
R1
R2
R1
R2
CH2N
CH2N
1a-p
2a-p
CH3
CH3
CH2CH3
CH2CH3
R1
N
N
N
N
=
Y= O, CH2
N
N
(
)
CH3
CH2CH3
R2
Scheme 1. (a) NBS, CCl4, hn, reflux 4 h; (b) secondary amine, CH2Cl2, reflux 2 h; (c) LiAlH4eEt2NH, pentane, r.t. 2e3 h; (d) Y]CH2, 5,6-dimethoxyindan-1-
one, KOH, CH3OH, r.t. 2e4 h; Y]O, 5,6-dimethoxybenzofuran-3(2H)-one, Al2O3, CH2Cl2, r.t. 2e4 h; (e) 5% Pd/C, THF, r.t. 6e8 h.

R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
9
Table 1
Structures and ChE inhibitory activities of 1aep and 2aep
Compound
NR1R2
X
Y
Substituted position
IC50 for AChE (mM)a
IC50 for BChE (mM)b
Selectivity for AChE
Donepezil
Rivastigmine
0.012
2.07
2.77
1.41
231
0.7
CH3
N
N
1a
1b
]CH
]CH
CH2
CH2
meta
para
2.14
0.42
89.3
315
42
750
CH3
CH3
1c
1d
1e
meta
para
para
0.49
0.27
0.70
36.8
20.1
23.6
75
74
34
CH2CH3
O
CH2CH3
CH3CH3
N
1f
1g
1h
1i
]CH
]CH
]CH
CH2
meta
para
meta
para
0.44
0.035
1.18
0.14
71
82
161
2342
55
O
65.1
47.9
342
1j
CH2
O
meta
para
meta
para
0.24
0.045
0.29
0.16
41.6
26.6
72.0
36.4
173
591
248
227
N
N
1k
1l
1m
1n
1o
1p
CH2
meta
para
para
0.16
0.10
0.082
55.2
84.6
45
345
846
549
O
CH3
N
N
2a
2b
eCH2
eCH2
CH2
meta
para
3.74
1.38
25.2
40.7
7
29
CH3
CH3
2c
2d
2e
CH2
meta
para
para
0.69
0.38
1.54
18.5
34.5
25.9
27
91
17
CH2CH3
O
CH2CH3
CH2CH3
N
2f
2g
2h
2i
eCH2
eCH2
eCH2
CH2
meta
para
meta
para
1.48
0.29
1.07
0.44
32.0
11.7
38.2
16.4
22
40
36
37
O
2j
CH2
O
meta
para
meta
para
2.58
0.15
7.02
0.62
42.2
33.2
57.6
49.8
16
221
8
N
N
2k
2l
2m
80
2n
2o
2p
a
CH2
O
meta
para
meta
0.66
0.12
0.24
70.4
48.3
98.1
107
402
408
Assay performed using rat cortex homogenate. Values are means of three different experiments.
Assay performed using rat serum.
b
The most potent AChE inhibitory activity in vitro was
2.3. Molecular docking
observed for the compounds 1g with the IC50 values of
0.035 mM, which was chosen as the typical compound and
evaluated for its pharmacological effects on cognitive en-
hancement in vivo. Mice step-down passive avoidance test
was used to evaluate the effects of 1g on the acquisition and
memory impairment induced by scopolamine [21]. Table 2
disclose that, in the acquisition memory process, scopolamine
markedly reduced the escape latency on the platform and in-
creased the times of step-down. Similar to donepezil and
rivastigmine, 1g significantly ameliorate scopolamine-induced
deficit at different concentrations (2, 5, 10 mg/kg, i.g.). There-
fore, new indanone derivative 1g demonstrated as a potent,
reversible, and highly selective AChE inhibitor and it could
remarkably improve the acquisition and memory deficits. All
the results suggest that indanone derivative 1g might be
a promising candidate in the treatment of AD.
To gain insight into the molecular determinants that modu-
late the inhibitory activity of these compounds, molecular
docking simulations for 1g to TcAChE were performed using
the flexX program in Sybyl 6.9.1 software based on the X-
ray crystal structure of TcAChE-E2020 complex [22]. The
docking and subsequent scoring were performed using the de-
fault parameters of the FlexX program, and the binding gorge
of TcAChE composed of the central catalytic pocket and
peripheral sites were taken as the binding site for docking.
Fig. 2 demonstrated that 1g has a nice fit in the active-site gorge
of AChE similar to donepezil, binding to the central subsite and
the peripheral anionic site simultaneously. As shown in Fig. 3,
near the bottom of the gorge (the central subsite), besides the
charged nitrogen makes a cation-p interaction with Trp84,
the diethylamine moiety also displays hydrophobic contacts

10
R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
Table 2
Effect of donepezil, rivastigmine and 1g on memory deficit of acquisition pro-
cess induced by scopolamine as evaluated by step-down passive avoidance test
4. Experimental protocols
All solvents used were of analytical grade. Melting points
were recorded on a Buchi apparatus and were not corrected,
IR spectra, KBr pellets, 400e4000 cmꢀ1 were recorded on
a Bruker VECTOR 22 FTIR spectrophotometer. 1H NMR
and 13C NMR spectra were recorded on a Bruker AM 400 in-
strument (chemical shifts are expressed as d values relative to
TMS as internal standard). Mass spectra (MS) and ESI (posi-
tive) were recorded on an Esquire-LC-00075 spectrometer.
Drugs
Dose/
Number Memory
Escape
latency
(s)
mg kgꢀ1 of mice abilities
(times)
Saline
Scopolamine
0
10
10
10
10
10
10
10
0.80 ꢃ 0.77 142 ꢃ 52
2.0
2.0
2.0
2.0
5.0
10.0
4.20 ꢃ 1.40a
1.90 ꢃ 1.52c
2.00 ꢃ 1.05d
2.67 ꢃ 1.87
2.00 ꢃ 1.41c
1.60 ꢃ 1.17d
5 ꢃ 6a
Scopolamine þ donepezil
Scopolamine þ rivastigmine
Scopolamine þ 1g
75 ꢃ 73c
73 ꢃ 49d
47 ꢃ 45b
55 ꢃ 56c
60 ꢃ 68c
4.1. Synthesis
ap < 0.001 vs vehicle group.
c
d
bp < 0.05, p < 0.01, p < 0.001 vs model group.
4.1.1. Procedure for preparation of 4a, 4b
Methyl 3-methyl-benzoate (15.0 g, 0.1 mol) was dissolved
in 150 mL carbon tetrachloride and N-bromosuccinimide
(20.0 g, 0.11 mol) was added. The mixture was refluxed for
6 h accompanied with illumination and the white succinimide
residue was filtered off. The solvent was evaporated under re-
duced pressure to give a yellow liquid, which was purified
with ether at ꢀ78 ꢁC to get 4a as a yellow liquid at room tem-
perature (21.6 g, 94.3% yield). Compound 4b was obtained
from methyl 4-methyl-benzoate with the yield of 91.3%, yel-
low solid, m.p. 52e54 ꢁC (52e53 ꢁC [23]).
with Asp72 and Phe331. In the middle of the gorge, the phenyl
ring formed p-p stacking with Tyr334 and Phe330, respec-
tively. At the top of the gorge (the PAS), the indanone ring
stacks against the indole ring of Trp279 through classical p-
p interaction, and the oxygen of indanone makes a hydrogen
bond with the nitrogen of the Phe288.
3. Conclusion
4.1.2. General procedure for preparation of
compounds 5aej
In summary, on the basis of designing dual-site binding
AChE inhibitors, a series of indanone and aurone derivatives
were prepared and evaluated ChE inhibitory activities in vitro.
Most of them demonstrated high activities against AChE,
while almost no activities were observed against BChE in vi-
tro. Compound 1g exhibited high AChE inhibitory activity
(IC50 ¼ 0.035 mM) in vitro and can remarkably improve the
memory deficits induced by scopolamine in mice step-down
passive avoidance test. The modeling studies clearly indicated
that 1g was nicely accommodated by AChE. Further seeking
the AD candidates based on these results is in progress and
will be reported in due course.
To a solution of 4a (2.29 g, 0.01 mol) in 20 mL CH2Cl2, was
added 33% dimethylamine solution (3.1 mL, 0.02 mol) at r.t.,
the mixture was refluxed for 2 h, the solvent was removed
under vacuum to nearly dryness. The residue was acidified
with 20 mL of 2 mol/L hydrochloric acid. The acid solution
was washed with ethyl acetate (10 mL ꢂ 3), and concentrated
ammonium hydroxide was added thereto up to clearly basic,
the product was extracted with ethyl acetate (20 mL ꢂ 3).
The extract was washed with brine and dried over anhydrous
Na2SO4. The solvent was removed under reduced pressure to
give crude product and then purified by silica gel column chro-
matography eluting with petroleum, ethyl acetate and triethyl-
amine (20:10:1) to afford compound 5a (1.11 g, 57.5%) as oil.
4.1.2.1. Methyl 3-[(dimethylamino)methyl]-benzoate 5a.
Yield: 57.5%; 1H NMR (CDCl3) d 7.92 (m, 2H, H-2 and H-6),
7.49 (d, 1H, J ¼ 7.2 Hz, H-4,), 7.37 (t, 1H, J ¼ 7.6 Hz, H-5),
3.90 (s, 3H, OCH3), 3.45 (s, 2H, benzylic-CH2), 2.23 (s, 6H,
2NCH3); MS (ESI), m/z ¼ 194 [M þ 1]; IR (KBr): 3021,
2949, 2855, 2817, 1725, 1589, 1434, 1286, 749, 694 cmꢀ1
.
4.1.2.2. Methyl 4-[(dimethylamino)methyl]-benzoate 5b.
1
Yield: 50.4%; H NMR (CDCl3) d 7.99 (d, 2H, J ¼ 8.0 Hz,
H-2 and H-6), 7.38 (d, 2H, J ¼ 8.0 Hz, H-3 and H-5), 3.91
(s, 3H, OCH3), 3.47 (s, 2H, benzylic-CH2), 2.25 (s, 6H,
2NCH3); MS (ESI), m/z ¼ 194 [M þ 1]; IR (KBr): 3012,
2976, 2817, 1723, 1611, 1435, 1279, 865 cmꢀ1
.
4.1.2.3. Methyl 3-[(ethylmethylamino)methyl]-benzoate 5c.
1
Yield: 51.7%; H NMR (CDCl3) d 7.97 (s, 1H, H-2), 7.90
Fig. 2. Topography of the constricted region in the gorge of AChE.

R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
11
Fig. 3. The binding modes of 1g in the gorge of AChE.
(d, 1H, J ¼ 7.6 Hz, H-6,), 7.51 (d, 1H, J ¼ 7.6 Hz, H-4,), 7.36
(t, 1H, J ¼ 7.6 Hz, H-5,), 3.90 (s, 3H, OCH3), 3.51 (s, 2H, ben-
zylic-CH2), 2.43 (q, 2H, J ¼ 6.8 Hz, CH2CH3,), 2.17 (s, 3H,
NCH3), 1.07 (t, 3H, J ¼ 6.8 Hz, CH2CH3); MS (ESI), m/
z ¼ 208 [M þ 1]; IR (KBr): 3025, 2971, 2950, 2839, 1725,
(KBr): 3024, 2970, 2873, 1725, 1589, 1433, 1284, 745,
692 cmꢀ1
.
4.1.2.6. Methyl 4-(diethylaminomethyl)-benzoate 5f. Yield:
68.7%; 1H NMR (CDCl3) d 7.97 (d, 2H, J ¼ 8.0 Hz, H-2
and H-6), 7.41 (d, 2H, J ¼ 8.0 Hz, H-3 and H-5), 3.91 (s,
3H, OCH3), 3.60 (s, 2H, benzylic-CH2), 2.49 (q, 4H, J ¼
7.2 Hz, 2CH2eCH3), 1.02 (t, 6H, J ¼ 7.2 Hz, 2CH2-CH3);
MS (ESI), m/z ¼ 222 [M þ 1]; IR (KBr): 3047, 2970, 2873,
1589, 1434, 1285, 748, 693 cmꢀ1
.
4.1.2.4. Methyl 4-[(ethylmethylamino)methyl]-benzoate 5d.
Yield: 54.1%; 1H NMR (CDCl3)
7.97 (d, 2H,
d
J ¼ 8.0 Hz, H-2 and H-6), 7.38 (d, 2H, J ¼ 8.0 Hz, H-3
and H-5), 3.90 (s, 3H, OCH3), 3.53 (s, 2H, benzylic-CH2),
2.42 (q, 2H, J ¼ 7.2 Hz, CH2CH3), 2.19 (s, 3H, NCH3),
1.08 (t, 3H, J ¼ 7.2 Hz, CH2eCH3); MS (ESI), m/z ¼ 208
[M þ 1]; IR (KBr): 3016, 2971, 2842, 1725, 1611, 1435,
1724, 1611, 1435, 1278, 858 cmꢀ1
.
4.1.2.7. Methyl 3-[(pyrrolidin-1-yl)methyl]-benzoate 5g.
1
Yield: 69.4%; H NMR (CDCl3) d 8.00 (s, 1H, H-2), 7.92
(d, 1H, J ¼ 7.6 Hz, H-6), 7.54 (d, 1H, J ¼ 8.0 Hz, H-4), 7.37
(t, 1H, J ¼ 7.6 Hz, H-5), 3.91 (s, 3H, OCH3), 3.65 (s, 2H, ben-
zylic-CH2), 2.49 (m, 4H, pyrrolidine-CH2, H-2 and H-5), 1.77
(m, 4H, pyrrolidine-CH2, H-3 and H-4); MS (ESI), m/z ¼ 220
[M þ 1]. IR (KBr): 3018, 2951, 2870, 1723, 1588, 1433, 1283,
1278, 859 cmꢀ1
.
4.1.2.5. Methyl 3-(diethylaminomethyl)-benzoate 5e. Yield:
1
76.0%; H NMR (CDCl3) d 7.99 (s, 1H, H-2), 7.90 (d, 1H,
J ¼ 7.6 Hz, H-6), 7.55 (d, 1H, J ¼ 7.6 Hz, H-4), 7.36 (t, 1H,
J ¼ 7.6 Hz, H-5), 3.91 (s, 3H, OCH3), 3.60 (s, 2H, benzylic-
CH2), 2.49 (q, 4H, J ¼ 7.6 Hz, 2CH2CH3), 1.02 (t, 6H,
J ¼ 7.6 Hz, 2CH2CH3); MS (ESI), m/z ¼ 222 [M þ 1]; IR
749, 699 cmꢀ1
.
4.1.2.8. Methyl 4-[(pyrrolidin-1-yl)methyl]-benzoate 5h.
1
Yield: 59.8%; H NMR (CDCl3) d 7.98 (d, 2H, J ¼ 8.0 Hz,

12
R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
H-2 and H-6), 7.40 (d, 2H, J ¼ 8.0 Hz, H-3 and H-5), 3.91 (s,
3H, OCH3), 3.66 (s, 2H, benzylic-CH2), 2.49 (m, 4H, pyrroli-
dine-CH2, H-2 and H-5), 1.77 (m, 4H, pyrrolidine-CH2, H-3
and H-4); MS (ESI), m/z ¼ 220 [M þ 1]; IR (KBr): 3027,
J ¼ 7.6 Hz, H-4), 7.47 (t, 1H, J ¼ 7.6 Hz, H-5), 3.56 (s, 2H,
benzylic-CH2), 2.45e2.50 (q, 4H, J ¼ 7.2 Hz, 2CH2-CH3),
2.20 (s, 3H, NeCH3), 1.10e1.13 (t, 3H, J ¼ 7.2 Hz, 2CH2e
CH3); MS (ESI), m/z ¼ 178 [M þ 1]; IR (KBr): 3020, 2970,
2954, 2783, 1723, 1612, 1435, 1278, 855 cmꢀ1
.
2924, 2848, 2726, 1699, 1604, 1588, 1450, 784, 690 cmꢀ1
.
4.1.2.9. Methyl 3-[(piperidin-1-yl)methyl]-benzoate 5i. Yield:
4.1.3.4.
4-[(Ethylmethylamino)methyl]-benzaldehyde
6d.
1
78.9%; H NMR (CDCl3) d 7.97 (s, 1H, H-2), 7.91 (d, 1H,
1
Yield: 47.8%; H NMR (CDCl3) d 10.00 (s, 1H, CHO), 7.83
(d, 2H, J ¼ 7.6 Hz, H-2 and H-6), 7.50 (d, 2H, J ¼ 8.0 Hz,
H-3 and H-5), 3.57 (s, 2H, benzylic-CH2), 2.45 (q, 2H,
J ¼ 7.2 Hz, 2CH2eCH3), 2.21 (s, 3H, NeCH3), 1.10 (t, 3H,
J ¼ 7.2 Hz, 2CH2eCH3); MS (ESI), m/z ¼ 178 [M þ 1]; IR
(KBr): 3031, 2969, 2926, 2847, 2735, 1700, 1607, 1577,
J ¼ 7.6 Hz, H-6), 7.53 (d, 1H, H-4, J ¼ 8.0 Hz), 7.36 (t, 1H,
H-5, J ¼ 7.6 Hz), 3.91 (s, 3H, OCH3), 3.50 (s, 2H, benzylic-
CH2), 2.37 (m, 4H, piperidine-CH2, H-20 and H-60), 1.54 (m,
4H, H-30and H-50), 1.43 (m, 2H, H-40); MS (ESI), m/z ¼ 234
[M þ 1]; IR (KBr): 3026, 2935, 2853, 1725, 1589, 1434,
1285, 748, 694 cmꢀ1
.
1456, 835 cmꢀ1
.
4.1.2.10. Methyl 4-[(piperidin-1-yl)methyl]-benzoate 5j. Yield:
4.1.3.5. 3-[(Diethylamino)methyl]-benzaldehyde 6e. Yield:
52.8%; 1H NMR (CDCl3) d 10.02 (s, 1H, CHO), 7.86 (s,
1H, H-2), 7.75 (d, 1H, J ¼ 7.6 Hz, H-6), 7.62 (d, 1H,
J ¼ 7.6 Hz, H-4), 7.45 (t, 1H, J ¼ 7.6 Hz, H-5), 3.63 (s, 2H,
benzylic-CH2), 2.51 (q, 4H, J ¼ 6.8 Hz, 2CH2eCH3), 1.03
(t, 6H, J ¼ 6.8 Hz, 2CH2eCH3); MS (ESI), m/z ¼ 192
[M þ 1]; IR (KBr): 3024, 2970, 2934, 2724, 1703, 1604,
1
76.8%; H NMR (CDCl3) d 7.97 (d, 2H, J ¼ 8.0 Hz, H-2 and
H-6), 7.39 (d, 2H, J ¼ 8.0 Hz, H-3 and H-5), 3.91 (s, 3H,
OCH3), 3.51 (s, 2H, benzylic-CH2), 2.37 (m, 4H, piperi-
dine-CH2, H-2 and H-6), 1.55 (m, 4H, piperidine-CH2, H-3
and H-5), 1.43 (m, 2H, H-4); MS (ESI), m/z ¼ 234
[M þ 1]; IR (KBr): 3031, 2935, 2853, 1724, 1612, 1435,
1279, 866 cmꢀ1
.
1588, 1449, 785, 689 cmꢀ1
.
4.1.3. General procedure for preparation of compounds
6aej
4.1.3.6. 4-[(Diethylamino)methyl]-benzaldehyde 6f. Yield:
1
55.4%; H NMR (CDCl3) d 10.00 (s, 1H, CHO), 7.82 (d,
LiAlH4 (97%, 78 mg, 2.0 mmol) was dissolved in 10 mL
THF, then, the THF solvent was pumped off, and diethylamine
(0.41 mL, 4.0 mmol) in 5 mL of pentane was added. To this
slurry was added 5a (0.39 g, 2.0 mmol) and the mixture was
stirred vigorously for 2 h at room temperature. Then, the reac-
tion mixture was cooled to 0 ꢁC, and the precipitate was fil-
tered and washed with cold pentane several times. The
separated pentane portion was washed with brine and dried
over anhydrous Na2SO4. The solvent was removed under vac-
uum to give crude product, which was purified by silica gel
column chromatography eluting with petroleum and acetone
(20:1) to afford compound 6a (0.15 g, 46%) as oil.
2H, J ¼ 8.0 Hz, H-2 and H-6), 7.52 (d, 2H, J ¼ 8.0 Hz, H-3
and H-5), 3.64 (s, 2H, benzylic-CH2), 2.51 (q, 2H,
J ¼ 7.2 Hz, 2CH2eCH3), 1.03 (t, 3H, J ¼ 7.2 Hz, 2CH2e
CH3); MS (ESI), m/z ¼ 192 [M þ 1]; IR (KBr): 3014, 2969,
2934, 2730, 1701, 1607, 1577, 1454, 831 cmꢀ1
.
4.1.3.7. 3-[(Pyrrolidin-1-yl)methyl]-benzaldehyde 6g. Yield:
47.6%; 1H NMR (CDCl3) d 10.02 (s, 1H, CHO), 7.86 (s,
1H, H-2), 7.77 (d, 1H, J ¼ 7.6 Hz, H-6), 7.62 (d, 1H,
J ¼ 7.6 Hz, H-4), 7.46 (t, 1H, J ¼ 7.2 Hz, H-5), 3.69 (s, 2H,
benzylic-CH2), 2.51 (m, 4H, pyrrolidine-CH2, H-2 and H-5),
1.79 (m, 4H, H-3 and H-4); MS (ESI), m/z ¼ 190 [M þ 1];
IR (KBr): 3026, 2962, 2927, 2732, 1699, 1605, 1588, 1460,
4.1.3.1. 3-[(Dimethylamino)methyl]-benzaldehyde 6a. Yield:
46.0%; 1H NMR (CDCl3) d 10.02 (s, 1H, CHO), 7.83 (s,
1H, H-2), 7.78 (d, 1H, J ¼ 7.6 Hz, H-6), 7.59 (d, 1H,
J ¼ 7.6 Hz, H-4), 7.47 (t, 1H, J ¼ 7.6 Hz, H-5), 3.50 (s, 2H,
CH2), 2.26 (s, 6H, 2 NeCH3); MS (ESI), m/z ¼ 164
[M þ 1]; IR (KBr): 3021, 2942, 2855, 2818, 2725, 1697,
783, 692 cmꢀ1
.
4.1.3.8. 4-[(Pyrrolidin-1-yl)methyl]-benzaldehyde 6h. Yield:
1
54.1%; H NMR (CDCl3) d 10.00 (s, 1H, CHO), 7.83 (d,
2H, J ¼ 7.6 Hz, H-2 and H-6), 7.51 (d, 2H, J ¼ 7.6 Hz,
H-3 and H-5), 3.70 (s, 2H, benzylic-CH2), 2.52 (m, 4H,
pyrrolidine-CH2, H-2 and H-5), 1.79 (m, 4H, pyrrolidine-
CH2, H-3 and H-4); MS (ESI), m/z ¼ 190 [M þ 1]; IR
(KBr): 3024, 2964, 2875, 2733, 1699, 1607, 1577, 1461,
1589, 1457, 797, 691 cmꢀ1
.
4.1.3.2. 4-[(Dimethylamino)methyl]-benzaldehyde 6b. Yield:
44.4%; H NMR (CDCl3) d 10.03 (s, 1H, CHO), 7.84 (d,
825 cmꢀ1
.
1
2H, J ¼ 7.6 Hz, H-2 and H-6), 7.48 (d, 2H, J ¼ 7.6 Hz, H-3
and H-5), 3.50 (s, 2H, benzylic-CH2), 2.26 (s, 6H, 2 N-
CH3); MS (ESI), m/z ¼ 164 [M þ 1]; IR (KBr): 3006, 2943,
4.1.3.9. 3-[(Piperidin-1-yl)methyl]-benzaldehyde 6i. Yield:
1
43.9%; H NMR (d, CDCl3) 10.02 (s, 1H, CHO), 7.83 (s,
2849, 2731, 1700, 1607, 1577, 1456, 817 cmꢀ1
.
1H, H-2), 7.76e7.78 (d, 1H, H-6 J ¼ 7.6 Hz), 7.61e7.63 (d,
1H, H-4, J ¼ 7.6 Hz), 7.46e7.49 (t, 1H, H-5, J ¼ 7.6 Hz),
3.54 (s, 2H, benzylic-CH2), 2.39 (m, 4H, piperidine-CH2,
H-20 and H-60), 1.56e1.61 (m, 4H, H-30and H-50), 1.44e
1.45 (m, 2H, H-40); MS (ESI), m/z ¼ 204 [M þ 1]; IR
4.1.3.3.
3-[(Ethylmethylamino)methyl]-benzaldehyde
6c.
1
Yield: 44.9%; H NMR (CDCl3) d 10.02 (s, 1H, CHO), 7.84
(s, 1H, H-2), 7.77 (d, 1H, J ¼ 8.0 Hz, H-6), 7.61 (d, 1H,

R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
13
(KBr): 3031, 2935, 2852, 2723, 1699, 1604, 1588, 1450, 801,
691 cmꢀ1
(KBr): 3068, 2968, 2835, 1689, 1631, 1606, 1588, 1501,
1304, 1217, 805, 695 cmꢀ1
.
.
4.1.3.10. 4-[(Piperidin-1-yl)methyl]-benzaldehyde 6j. Yield:
4.1.4.4.
(E )-2-{4-[(Ethylmethylamino)methyl]benzylidene}-
1
48.8%; H NMR (CDCl3) d 10.00 (s, 1H, CHO), 7.82 (d,
5,6-dimethoxy-2,3-dihydroinden-1-one 1d. Yield: 82.6%;
m.p. 105e107 ꢁC; H NMR (CDCl3) d 7.58 (m, 3H, H-7, H-
1
2H, J ¼ 7.2 Hz, H-2 and H-6), 7.49 (d, 2H, J ¼ 7.2 Hz, H-3
and H-5), 3.55 (s, 2H, benzylic-CH2), 2.39 (m, 4H, piperi-
dine-CH2, H-2 and H-6), 1.57 (m, 4H, piperidine-CH2, H-3
and H-5), 1.44 (m, 2H H-40); MS (ESI), m/z ¼ 204 [M þ 1];
IR (KBr): 3024, 2935, 2852, 2732, 1702, 1607, 1577,
20 and H-60), 7.40 (d, 2H, J ¼ 8.4 Hz, H-30and H-50), 7.34 (s,
1H, C]CH), 6.99 (s, 1H, H-4), 4.00 (s, 3H, OCH3), 3.96 (s,
2H, H-3), 3.95 (s, 3H, OCH3), 3.53 (s, 2H, benzylic-CH2),
2.45 (q, 4H, J ¼ 7.2 Hz, CH2-CH3), 2.22 (s, 3H, N-CH3),
1.10 (t, 3H, J ¼ 7.2 Hz, CH2eCH3); MS (ESI), m/z ¼ 352
[M þ 1]; IR (KBr): 3063, 2969, 2836, 1683, 1629, 1606,
863 cmꢀ1
.
4.1.4. General procedure for preparation of indanone
derivatives 1aed, 1f, 1g, 1j, 1k, 1n and 1o
1590, 1501, 837 cmꢀ1
4.1.4.5.
.
To a solution of KOH (84 mg, 1.5 mmol) in 10 mL meth-
anol, 6a (0.16 g, 1.0 mmol) and 5,6-dimethoxy- indanone
(0.21 g, 1.1 mmol) were added, the mixture was stirred for
3 h at r.t., then, the solvent was evaporated to dryness, the
residue was treated with 15 mL, 2 M HCl and 15 mL Et2O,
shacked, the aqueous layer was separated, alkalinized with
K2CO3, then extracted with EtOAc, the organic phase was
separated and washed with brine, dried over anhydrous
Na2SO4, then evaporated under reduced pressure to give crude
product, which was purified by silica gel column chromatog-
raphy eluting with petroleum, ethyl acetate and triethylamine
(20:10:1) to afford compound 1a (0.27 g, 80%) as a white
solid.
(E )-2-{3-[(Diethylamino)methyl]benzylidene}-5,6-
dimethoxy-2,3-dihydroinden-1-one 1f. Yield: 79.4%; m.p.
78e80 ꢁC; H NMR (CDCl3) d 7.64 (s, 1H, H-7), 7.61 (s,
1
1H, H-20), 7.53 (d, 1H, J ¼ 6.8 Hz, H-40), 7.36 (m, 3H, H-50,
H-60 and C]CH), 6.99 (s, 1H, H-4), 4.00 (s, 3H, OCH3),
3.98 (s, 2H, H-3), 3.95 (s, 3H, OCH3), 3.63 (s, 2H, ben-
zylic-CH2), 2.53 (q, 4H, J ¼ 7.2 Hz, 2CH2eCH3), 1.06 (t,
6H, J ¼ 7.2 Hz, 2CH2eCH3); MS (ESI), m/z ¼ 366 [M þ 1];
IR (KBr): 3071, 2967, 2932, 1681, 1630, 1605, 1588, 1501,
1305, 1233, 804, 691 cmꢀ1
.
4.1.4.6. (E )-2-{4-[(Diethylamino)methyl]benzylidene}-5,6-
dimethoxy-2,3-dihydroinden-1-one 1g. Yield: 76.7%, m.p.
116e118 ꢁC; H NMR (CDCl3) d 7.60 (m, 3H, H-7, H-20
1
4.1.4.1. (E )-2-{3-[(Dimethylamino)methyl]benzylidene}-5,6-
and H-60), 7.42 (d, 2H, J ¼ 7.6 Hz, H-30and H-50), 7.36 (s,
1H, C]CH), 6.99 (s, 1H, H-4), 4.00 (s, 3H, OCH3), 3.97 (s,
2H, H-3), 3.96 (s, 3H, OCH3), 3.61 (s, 2H, benzylic-CH2),
2.52 (q, 4H, J ¼ 7.2 Hz, 2CH2eCH3,), 1.05 (t, 6H,
J ¼ 7.2 Hz, 2CH2eCH3); 13C NMR (CDCl3, 100 MHz)
d 192.9, 155.1, 149.4, 144.7, 141.8, 134.6, 133.8, 132.1,
130.9, 130.28, 129.1, 107.0, 104.8, 57.1, 56.1, 55.9, 46.7,
32.0, 11.6; MS (ESI), m/z ¼ 366 [M þ 1]; IR (KBr): 3061,
2967, 2932, 1690, 1629, 1606, 1500, 1223, 832 cmꢀ1. Anal.
Calcd for C23H27NO3: C 75.59, H 7.45, N 3.83. Found: C
75.29, H 7.16, N 3.60.
dimethoxy-2,3-dihydroinden-1-one 1a. Yield: 80.1%; m.p.
1
96e98 ꢁC; H NMR (CDCl3) d 7.56 (m, 3H, H-7, H-20 and
H-40), 7.41 (t, 1H, H-50, J ¼ 7.6 Hz), 7.34 (m, 2H, H-60 and
C]CH), 7.00 (s, 1H, H-4), 4.00 (s, 3H, OCH3), 3.98 (s, 2H,
H-3), 3.95 (s, 3H, OCH3), 3.49 (s, 2H, benzylic-CH2), 2.28
(s, 6H, 2 N-CH3); MS (ESI), m/z ¼ 338 [M þ 1]; IR (KBr):
3066, 2940, 2816, 1687, 1630, 1605, 1588, 1501, 1233, 806,
695 cmꢀ1
.
4.1.4.2. (E )-2-{4-[(Dimethylamino)methyl]benzylidene}-5,6-
dimethoxy-2,3-dihydroinden-1-one 1b. Yield: 79.2%; m.p.
1
135e137 ꢁC; H NMR (CDCl3) d 7.60e7.63 (m, 3H, H-7,
4.1.4.7.
(E )-5,6-Dimethoxy-2-{3-[(pyrrolidin-1-yl)methyl]-
H-20 and H-60), 7.39 (d, 2H, J ¼ 7.6 Hz, H-30and H-50), 7.36
(s, 1H, C]CH), 6.99 (s, 1H, H-4), 4.01 (s, 3H, OCH3), 3.97
(s, 2H, H-3), 3.96 (s, 3H, OCH3), 3.47 (s, 2H, benzylic-
CH2), 2.27 (s, 6H, 2N-CH3); MS (ESI), m/z ¼ 338 [M þ 1];
IR (KBr): 3058, 2924, 2805, 1690, 1629, 1605, 1586,
benzylidene}-2,3-dihydroinden-1-one 1j. Yield: 82.6%, m.p.
1
112e113 ꢁC; H NMR (CDCl3) d 7.61 (s, 2H, H-7 and H-
20), 7.55 (d, 1H, J ¼ 7.2 Hz, H-40), 7.36 (m, 3H, H-50, H-60
and C]CH), 7.00 (s, 1H, H-4), 4.01 (s, 3H, OCH3), 3.99 (s,
2H, H-3), 3.97 (s, 3H, OCH3), 3.69 (s, 2H, benzylic-CH2),
2.56 (m, 4H, pyrrolidine-CH2, H-2 and H-5), 1.82 (m, 4H, pyr-
rolidine-CH2, H-3 and H-4); MS (ESI), m/z ¼ 364 [M þ 1]; IR
(KBr): 3064, 2960, 2825, 1689, 1630, 1601, 1585, 1234, 809,
824 cmꢀ1
.
4.1.4.3.
(E )-2-{3-[(Ethylmethylamino)methyl]benzylidene}-
5,6-dimethoxy-2,3-dihydroinden-1-one 1c. Yield: 79.8%;
688, cmꢀ1
.
1
m.p. 75e77 ꢁC; H NMR (d, CDCl3) 7.61 (s, 2H, H-7 and
H-20), 7.55 (d, 1H, J ¼ 7.6 Hz, H-40), 7.39 (t, 1H,
J ¼ 7.6 Hz, H-50), 7.35 (m, 2H, H-60 and C]CH), 7.00 (s,
1H, H-4), 4.00 (s, 3H, OCH3), 3.98 (s, 2H, H-3), 3.96 (s,
3H, OCH3), 3.57 (s, 2H, benzylic-CH2), 2.48 (q, 2H,
J ¼ 7.2 Hz, CH2eCH3), 2.24 (s, 3H, NeCH3), 1.12 (t, 3H,
J ¼ 7.2 Hz, CH2eCH3); MS (ESI), m/z ¼ 352 [M þ 1]; IR
4.1.4.8.
(E )-5,6-Dimethoxy-2-{4-[(pyrrolidin-1-yl)methyl]-
benzylidene}-2,3-dihydroinden-1-one 1k. Yield: 77.1%, m.p.
138e140 ꢁC; H NMR (CDCl3) d 7.60 (m, 3H, H-7, H-20
and H-60), 7.42 (d, 2H, J ¼ 8.0 Hz, H-30and H-50), 7.35 (s,
1H, C]CH), 6.99 (s, 1H, H-4), 4.00 (s, 3H, OCH3), 3.97 (s,
2H, H-3), 3.96 (s, 3H, OCH3), 3.66 (s, 2H, benzylic-CH2),
1

14
R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
2.54 (m, 4H, pyrrolidine-CH2, H-2 and H-5), 1.81 (m, 4H, pyr-
rolidine-CH2, H-3 and H-4); MS (ESI), m/z ¼ 364 [M þ 1]; IR
(KBr): 3066, 2969, 2928, 1682, 1628, 1606, 1590, 1224, 826,
J ¼ 7.2 Hz, 2 ꢂ CH2), 1.05 (t, 6H, J ¼ 7.2 Hz, 2 ꢂ CH3); MS
(ESI), m/z ¼ 368 [M þ 1]; IR (KBr): 3071, 2967, 2793,
1690, 1648, 1605, 1482, 1280, 1139, 804, 698 cmꢀ1
.
cmꢀ1
.
4.1.5.3.
(Z )-2-{4-[(Diethylamino)methyl]benzylidene}-5,6-
4.1.4.9.
(E )-5,6-Dimethoxy-2-{3-[(piperidin-1-yl)methyl]-
dimethoxybenzofuran-3(2H)-one 1i. Yield: 82.9%, m.p. 117e
1
benzylidene}-2,3-dihydroinden-1-one 1n. Yield: 84.9%, m.p.
127e129 ꢁC; H NMR (CDCl3) d 7.61 (s, 2H, H-7 and H-
121 ꢁC; H NMR (CDCl3) d 7.84 (d, 2H, J ¼ 7.6 Hz, H-20
1
and H-60), 7.43 (d, 2H, J ¼ 8.0 Hz, H-30and H-50), 7.20 (s,
1H, C]CH), 6.84 (s, 1H, H-4), 6.82 (s, 1H, H-7), 4.04 (s,
3H, OCH3), 3.93 (s, 3H, OCH3), 3.62 (s, 2H, benzylic-CH2),
2.53 (q, 4H, J ¼ 7.6 Hz, 2 ꢂ CH2), 1.05 (t, 6H, J ¼ 7.6 Hz,
2 ꢂ CH3); MS (ESI), m/z ¼ 368 [M þ 1]; IR (KBr): 3061,
20), 7.54 (d, 1H, J ¼ 6.8 Hz, H-40), 7.35 (m, 3H, H-50, H-60
and C]CH), 6.99 (s, 1H, H-4), 4.01 (s, 3H, OCH3), 3.98 (s,
2H, H-3), 3.95 (s, 3H, OCH3), 3.52 (s, 2H, benzylic-CH2),
2.41 (m, 4H, piperidine-CH2, H-2 and H-6), 1.57 (m, 4H,
piperidine-CH2, H-3 and H-5), 1.45 (m, 2H, piperidine-CH2,
H-4); MS (ESI), m/z ¼ 378 [M þ 1]; IR (KBr): 3068, 2934,
2966, 2934, 1693, 1652, 1606, 1498, 1276, 814 cmꢀ1
.
2851, 1686, 1628, 1601, 1584, 1234, 809, 687 cmꢀ1
.
4.1.5.4.
(Z )-5,6-Dimethoxy-2-{3-[(pyrrolidin-1-yl)methyl]-
benzylidene}-benzofuran-3(2H)-one 1l. Yield: 63.4%, m.p.
1
4.1.4.10.
(E )-5,6-Dimethoxy-2-{4-[(piperidin-1-yl)methyl]-
125e130 ꢁC; H NMR (CDCl3) d 7.83 (m, 1H, H-60), 7.78
benzylidene}-2,3-dihydroinden-1-one 1o. Yield: 82.2%, m.p.
(s, 1H, H-20), 7.39 (m, 2H, H-40 and H-50), 7.18 (s, 1H,
C]CH), 6.83 (s, 1H, H-4), 6.82 (s, 1H, H-7), 4.03 (s, 3H,
OCH3), 3.91 (s, 3H, OCH3), 3.68 (s, 2H, benzylic-CH2),
2.53 (m, 4H, pyrrolidine-CH2, H-2 and H-5), 1.79 (m, 4H, pyr-
rolidine-CH2, H-3 and H-4); MS (ESI), m/z ¼ 366 [M þ 1]; IR
(KBr): 3064, 2964, 2783, 1691, 1653, 1608, 1499, 1281,1135,
1
124e126 ꢁC; H NMR (CDCl3) d 7.59 (m, 3H, H-7, H-20
and H-60), 7.40 (d, 2H, J ¼ 7.6 Hz, H-30and H-50), 7.34 (s,
1H, C]CH), 6.98 (s, 1H, H-4), 4.00 (s, 3H, OCH3), 3.95 (s,
5H, H-3 and OCH3), 3.52 (s, 2H, benzylic-CH2), 2.38 (m,
4H, piperidine-CH2, H-2 and H-6), 1.57e1.61 (m, 4H, piper-
idine-CH2, H-3 and H-5), 1.44 (m, 2H, piperidine-CH2, H-
4); MS (ESI), m/z ¼ 378 [M þ 1]; IR (KBr): 3064, 2969,
818, 697 cmꢀ1
.
2933, 2852, 1689, 1633, 1606, 1589, 1222, 863 cmꢀ1
.
4.1.5.5. (Z )-5,6-Dimethoxy-2-{4-[(pyrrolidin-1-yl)methyl]-
benzylidene}-benzofuran-3(2H)-one 1m. Yield: 71.9%, m.p.
1
4.1.5. General procedure for preparation of aurone
derivatives 1e, 1h, 1i, 1l, 1m and 1p
149e152 ꢁC; H NMR (CDCl3) d 7.83 (d, 2H, J ¼ 8.0 Hz,
H-20 and H-60), 7.40 (d, 2H, J ¼ 8.0 Hz, H-30and H-50), 7.18
(s, 1H, C]CH), 6.83 (s, 1H, H-4), 6.82 (s, 1H, H-7), 4.02
(s, 3H, OCH3), 3.90 (s, 3H, OCH3), 3.66 (s, 2H, benzylic-
CH2), 2.53 (m, 4H, pyrrolidine-CH2, H-2 and H-5), 1.80 (m,
4H, pyrrolidine-CH2, H-3 and H-4); MS (ESI), m/z ¼ 366
[M þ 1]; IR (KBr): 3066, 2955, 2786, 1690, 1650, 1605,
5,6-Dimethoxybenzofuran-3(2H)-one (0.12 g, 0.62 mmol)
and compound 6c (0.104 g, 0.59 mmol) were dissolved in
5 mL CH2Cl2, then 0.3 g Al2O3 (neutral) was added, the mix-
ture was stirred for 3 h at r.t. filtered to remove Al2O3, washed
with 15 mL CH2Cl2, the organic phase was separated and
washed with brine, dried over anhydrous Na2SO4, then evapo-
rated under reduced pressure to dryness, the residue was puri-
fied by silica gel column chromatography eluting with
petroleum, ethyl acetate and triethylamine (10:10:1) to afford
compound 1e (0.16 g, 76.9%) as a yellow solid.
1499, 1277, 818 cmꢀ1
4.1.5.6.
.
(Z )-5,6-Dimethoxy-2-{3-[(piperidin-1-yl)methyl]-
benzylidene}-benzofuran-3(2H)-one 1p. Yield: 87.2%, m.p.
1
153e156 ꢁC; H NMR (CDCl3) d 7.82 (d, 2H, J ¼ 8.4 Hz,
H-20 and H-60), 7.39 (d, 2H, J ¼ 8.0 Hz, H-30and H-50),
7.18 (s, 1H, C]CH), 6.83 (s, 1H, H-4), 6.82 (s, 1H, H-7),
4.02 (s, 3H, OCH3), 3.91 (s, 3H, OCH3), 3.51 (s, 2H, ben-
zylic-CH2), 2.39 (m, 4H, piperidine-CH2, H-2 and H-6),
1.56 (m, 4H, piperidine-CH2, H-3 and H-5), 1.44 (m, 2H, pi-
peridine-CH2, H-4); MS (ESI), m/z ¼ 380 [M þ 1]; IR (KBr):
3064, 2935, 2793, 2756, 1690, 1649, 1601, 1498, 1276,
4.1.5.1. (Z )-2-{3-[(Ethylmethylamino)methyl]benzylidene}-5,6-
dimethoxy-benzofuran-3(2H)-one 1e. M.p. 138e141 ꢁC; 1H
NMR (CDCl3) d 7.83 (d, 2H, J ¼ 8.0 Hz, H-20 and H-60),
7.39 (d, 2H, J ¼ 8.0 Hz, H-30and H-50), 7.18 (s, 1H,
C]CH), 6.83 (s, 1H, H-4), 6.81 (s, 1H, H-7), 4.02 (s, 3H,
OCH3), 3.91 (s, 3H, OCH3), 3.53 (s, 2H, benzylic-CH2),
2.44 (q, 2H, J ¼ 7.2 Hz, CH2eCH3), 2.22 (s, 3H, NeCH3),
1.09 (t, 3H, J ¼ 7.2 Hz, CH2eCH3); MS (ESI), m/z ¼ 354
[M þ 1]; IR (KBr): 3063, 2971, 2838, 1695, 1656, 1607,
824 cmꢀ1
.
4.1.6. General procedure for preparation of
compounds 2aep
1501, 1280, 816 cmꢀ1
4.1.5.2.
.
A mixture of compound 1a (0.17 g, 0.5 mmol) in THF
(20 mL) and 5% palladium on carbon (10 mg) was stirred un-
der hydrogen (balloon) for 6 h, The mixture was then filtered
through diatomaceous earth, the filter cake was washed with
methanol, and the combined filtrates were concentrated to
give a slight yellow solid. Purification by silica gel column
chromatography eluting with petroleum ether, ethyl acetate
(Z )-2-{3-[(Diethylamino)methyl]benzylidene}-5,6-
dimethoxybenzofuran-3(2H)-one 1h. Yield: 73.1%, m.p. 95e
1
98 ꢁC; H NMR (CDCl3) d 7.81 (m, 1H, H-60), 7.78 (s, 1H,
H-20), 7.38 (m, 2H, H-40 and H-50), 7.18 (s, 1H, C]CH),
6.82 (s, 1H, H-4), 6.81 (s, 1H, H-7), 4.02 (s, 3H, OCH3),
3.91 (s, 3H, OCH3), 3.62 (s, 2H, benzylic-CH2), 2.53 (q, 4H,

R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
15
and triethylamine (10:10:1) afforded compound 2a as a white
solid.
(s, 1H, H-4), 6.54 (s, 1H, H-7), 4.74 (dd, 1H, J1 ¼ 8.4 Hz,
J2 ¼ 3.2 Hz, H-2), 3.93 (s, 3H, OCH3), 3.84 (s, 3H, OCH3),
3.51 (s, 2H, PhCH2N), 3.32 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼
3.2 Hz, PheCH2-a), 2.91 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼ 8.4 Hz,
PheCH2-b), 2.44 (q, 2H, J ¼ 7.2 Hz, CH2eCH3), 2.20 (s,
3H, NeCH3), 1.09 (t, 3H, J ¼ 7.2 Hz, CH2eCH3); MS
(ESI), m/z ¼ 356 [M þ 1]; IR (KBr): 3072, 2970, 2938,
4.1.6.1. 2-{3-[(Dimethylamino)methyl]benzyl}-5,6-dimethoxy-
2,3-dihydroinden-1-one 2a. Yield: 70.6%, m.p. 76e78 ꢁC;
1H NMR (CDCl3) d 7.19 (m, 3H, H-7, H-20 and H-50), 7.14
(d, 2H, J ¼ 8.0 Hz, H-40 and H-60), 6.81 (s, 1H, H-4), 3.94
(s, 3H, OCH3), 3.91 (s, 3H, OCH3), 3.35e3.45 (m, 3H,
PhCH2N and PheCH2-a), 3.03 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼
7.6 Hz, H-3a), 2.97 (m, 1H, H-2), 2.75 (d, 1H, J ¼ 16.4 Hz,
H-3b), 2.62 (dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 10.0 Hz, PheCH2-
b), 2.23 (s, 6H, 2 NeCH3); MS (ESI), m/z ¼ 340 [M þ 1];
IR (KBr): 3073, 2927, 2852, 1681, 1606, 1591, 1501, 1455,
2838, 1698, 1616, 1486, 1440, 1270, 826 cmꢀ1
.
4.1.6.6. 2-{3-[(Diethylamino)methyl]benzyl}-5,6-dimethoxy-
1
2,3-dihydroinden-1-one 2f. Yield: 76.3%, m.p. 75e77 ꢁC, H
NMR (CDCl3) d 7.17 (m, 4H, H-7, H-20, H-40 and H-50),
7.18 (d, 1H, J ¼ 7.6 Hz, H-60), 6.80 (s, 1H, H-4), 3.94 (s, 3H,
OCH3), 3.92 (s, 3H, OCH3), 3.55 (s, 2H, PhCH2N), 3.35 (dd,
1H, J1 ¼ 14.0 Hz, J2 ¼ 4.0 Hz, PheCH2-a), 3.03 (dd, 1H,
J1 ¼ 16.4 Hz, J2 ¼ 7.2 Hz, H-3a), 2.97 (m, 1H, H-2), 2.75
(dd, 1H, J1 ¼ 16.4 Hz, J2 ¼ 2.8 Hz, H-3e), 2.61 (dd, 1H,
J1 ¼ 14.0 Hz, J2 ¼ 10.0 Hz, PheCH2-b), 2.48 (q, 4H,
J ¼ 6.8 Hz, 2CH2eCH3), 1.02 (t, 6H, J ¼ 6.8 Hz, 2CH2e
CH3); 13C NMR (CDCl3) d 206.5, 155.4, 149.3, 148.9, 140.0,
139.5, 129.3, 129.2, 128.2, 127.2, 126.8, 107.3, 104.3, 57.4,
56.1, 56.0, 49.0, 46.6, 37.2, 31.8, 11.6; MS (ESI), m/z ¼ 368
[M þ 1]; IR (KBr): 3023, 2967, 2930, 2871, 1680, 1605,
780, 706 cmꢀ1
.
4.1.6.2. 2-{4-[(Dimethylamino)methyl]benzyl}-5,6-dimethoxy-
2,3-dihydroinden-1-one 2b. Yield: 76.6%, m.p. 99e101 ꢁC;
1H NMR (CDCl3) d 7.18 (m, 5H, H-7, H-20, H-30, H-50and
H-60), 6.81 (s, 1H, H-4), 3.94 (s, 3H, OCH3), 3.92 (s, 3H,
OCH3), 3.41 (s, 2H, PhCH2N), 3.34 (dd, 1H, J1 ¼ 14.0 Hz,
J2 ¼ 4.0 Hz, PheCH2-a), 3.04 (dd, 1H, J1 ¼ 16.4 Hz,
J2 ¼ 7.6 Hz, H-3a), 2.96e3.01 (m, 1H, H-2), 2.74 (dd, 1H,
J1 ¼ 16.4 Hz, J2 ¼ 3.2 Hz, H-3b), 2.61 (dd, 1H, J1 ¼ 14.0 Hz,
J2 ¼ 10.0 Hz, PheCH2-b), 2.25 (s, 6H, 2 N-CH3); MS (ESI),
m/z ¼ 340 [M þ 1]; IR (KBr): 3073, 2928, 2853, 1681, 1605,
1590, 1502, 1477, 763, 704 cmꢀ1
.
1592, 1502, 1472, 1454, 805 cmꢀ1
4.1.6.3.
.
4.1.6.7. 2-{4-[(Diethylamino)methyl]benzyl}-5,6-dimethoxy
2,3-dihydroinden-1-one 2g. Yield: 70.8%, m.p. 98e100 ꢁC
1H NMR (CDCl3) d 7.24 (d, 2H, J ¼ 8.0 Hz, H-2 and H-6),
7.17 (m, 3H, H-7, H-3 and H-5), 6.81 (s, 1H, H-4), 3.94 (s,
3H, OCH3), 3.92 (s, 3H, OCH3), 3.54 (s, 2H, PhCH2N),
3.34 (dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 4.0 Hz, PheCH2-a), 3.04
(dd, 1H, J1 ¼ 16.8 Hz, J2 ¼ 7.6 Hz, H-3a), 2.96 (m, 1H, H-
2), 2.75 (dd, 1H, J1 ¼ 16.8 Hz, J2 ¼ 2.8 Hz, H-3b), 2.60 (dd,
1H, J1 ¼ 14.0 Hz, J2 ¼ 10.0 Hz, PheCH2-b), 2.49 (q, 4H,
J ¼ 7.2 Hz, 2CH2eCH3), 1.02 (t, 6H, J ¼ 7.2 Hz, 2CH2e
CH3); 13C NMR (CDCl3) d 206.5, 155.4, 149.3, 148.9,
138.0, 137.7, 129.2, 129.0, 128.6, 107.3, 104.3, 57.0, 56.1,
56.0, 49.1, 46.5, 36.9, 31.8, 11.6; MS (ESI), m/z ¼ 368
[M þ 1]; IR (KBr): 3073, 2931, 2874, 1683, 1606, 1593,
2-{3-[(Ethylmethylamino)methyl]benzyl}-5,6-dime-
thoxy-2,3-dihydroinden-1-one 2c. Yield: 74.1%, m.p. 68e
1
69 ꢁC; H NMR (CDCl3) d 7.22 (d, 1H, J ¼ 7.6 Hz, H-40),
7.20 (m, 2H, H-7 and H-20), 7.12 (m, 2H, H-60 and H-50),
6.81 (s, 1H, H-4), 3.94 (s, 3H, OCH3), 3.92 (s, 3H, OCH3),
3.57 (s, 2H, PhCH2N), 3.34 (dd, 1H, J1 ¼ 14.0 Hz, J2 ¼
4.0 Hz, PheCH2-a), 3.04 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼ 7.2 Hz,
H-3a), 2.96 (m, 1H, H-2), 2.75 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼
2.8 Hz, H-3b), 2.62 (dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 10.0 Hz,
PheCH2-b), 2.42 (q, 2H, J ¼ 7.2 Hz, CH2eCH3), 2.18 (s,
3H, NeCH3), 1.09 (t, 3H, J ¼ 7.2 Hz, CH2eCH3); MS
(ESI), m/z ¼ 354 [M þ 1]; IR (KBr): 3056, 2970, 2931,
2837, 1681, 1591, 1502, 1443, 774, 706 cmꢀ1
.
1505, 1474, 821 cmꢀ1
.
4.1.6.4.
2-{4-[(Ethylmethylamino)methyl]benzyl}-5,6-dime-
4.1.6.8. 2-{3-[(Diethylamino)methyl]benzyl}-5,6-dimethoxy
thoxy-2,3-dihydroinden-1-one 2d. Yield: 79.3%, m.p. 92e
benzofuran-3(2H)-one 2h. Yield: 36.9%; oil; 1H NMR
(CDCl3) d 7.18 (m, 4H, H-20, H-40, H-50and H-60), 6.96 (s,
1H, H-4), 6.53 (s, 1H, H-7), 4.76 (dd, 1H, J1 ¼ 8.8 Hz,
J2 ¼ 4.0 Hz, H-2), 3.93 (s, 3H, OCH3), 3.84 (s, 3H, OCH3),
3.53 (s, 2H, PhCH2N), 3.33 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼
4.0 Hz, PheCH2-a), 2.92 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼ 8.8 Hz,
PheCH2-b), 2.46 (q, 4H, J ¼ 7.2 Hz, 2 ꢂ CH2), 1.01 (t, 6H,
J ¼ 7.2 Hz, 2 ꢂ CH3); MS (ESI), m/z ¼ 370 [M þ 1]; IR
(KBr): 3023, 2969, 2935, 2836, 1697, 1616, 1485, 1440,
1
94 ꢁC; H NMR (CDCl3) d 7.18 (m, 5H, H-7, H-20, H-30, H-
50and H-60), 6.81 (s, 1H, H-4), 3.94 (s, 3H, OCH3), 3.92 (s,
3H, OCH3), 3.50 (s, 2H, PhCH2N), 3.34 (dd, 1H, J1 ¼
14.0 Hz, J2 ¼ 4.0 Hz, PheCH2-a), 3.04 (dd, 1H, J1 ¼ 16.8 Hz,
J2 ¼ 7.6 Hz, H-3a), 2.96 (m, 1H, H-2), 2.75 (dd, 1H,
J1 ¼ 16.8 Hz, J2 ¼ 2.4 Hz, H-3b), 2.61 (dd, 1H, J1 ¼ 14.0 Hz,
J2 ¼ 10.0 Hz, PheCH2-b), 2.44 (q, 4H, J ¼ 7.2 Hz, 2CH2e
CH3), 2.20 (s, 3H, NeCH3), 1.09 (t, 3H, J ¼ 7.2 Hz, 2CH2e
CH3); MS (ESI), m/z ¼ 354 [M þ 1]; IR (KBr): 3072, 2963,
1270, 782, 712 cmꢀ1
.
2926, 2853, 1682, 1606, 1592, 1501, 1455, 820 cmꢀ1
.
4.1.6.9.
2-{4-[(Diethylamino)methyl]benzyl}-5,6-dimethoxy
4.1.6.5.
2-{3-[(Ethylmethylamino)methyl]benzyl}-5,6-dime-
benzofuran-3(2H)-one 2i. Yield: 32.8%; oil; 1H NMR
(CDCl3) d 7.23 (m, 4H, H-20, H-30, H-50and H-60), 6.95 (s,
1H, H-4), 6.53 (s, 1H, H-7), 4.74 (dd, 1H, J1 ¼ 8.4 Hz,
1
thoxy-benzofuran-3(2H)-one 2e. Yield: 29.8%; oil; H NMR
(CDCl3) d 7.25 (m, 4H, H-20, H-30, H-50and H-60), 6.96

16
R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
J2 ¼ 3.6 Hz, H-2), 3.92 (s, 3H, OCH3), 3.83 (s, 3H, OCH3),
3.52 (s, 2H, PhCH2N), 3.31 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼
3.6 Hz, PheCH2-a), 2.90 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼ 8.4 Hz,
PheCH2-b), 2.45 (q, 4H, J ¼ 7.2 Hz, 2 ꢂ CH2), 0.99 (t, 6H,
J ¼ 6.8 Hz, 2 ꢂ CH3); MS (ESI), m/z ¼ 370 [M þ 1]; IR
(KBr): 3073, 2968, 2931, 1699, 1616, 1485, 1440, 1270,
m/z ¼ 368 [M þ 1]; IR (KBr): 3072, 2930, 2784, 1697, 1616,
1487, 1440, 1270, 824 cmꢀ1
.
4.1.6.14. 5,6-Dimethoxy-2-{3-[(piperidin-1-yl)methyl]-benzyli-
dene}-2,3-dihydroinden-1-one 2n. Yield: 84.4%, m.p. 81e
1
83 ꢁC; H NMR (CDCl3) d 7.16 (m, 4H, H-7, H-20, H-40 and
825 cmꢀ1
.
H-50), 7.11 (d, 1H, H-60, J ¼ 7.6 Hz), 6.80 (s, 1H, H-4), 3.94
(s, 3H, OCH3), 3.92 (s, 3H, OCH3), 3.49 (s, 2H, PhCH2N),
3.34 (dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 3.2 Hz, PheCH2-a), 3.04
(dd, 1H, J1 ¼ 16.0 Hz, J2 ¼ 7.2 Hz, H-3a), 2.97 (m, 1H, H-
2), 2.75 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼ 2.4 Hz, H-3b), 2.63 (dd,
1H, J1 ¼ 14.0 Hz, J2 ¼ 10.0 Hz, PheCH2-b), 2.35 (m, 4H, pi-
peridine-CH2, H-2 and H-6), 1.56 (m, 4H, piperidine-CH2, H-
3 and H-5), 1.42 (m, 2H, piperidine-CH2, H-4); MS(ESI), m/
z ¼ 380 [M þ 1]; IR (KBr1): 3073, 2927, 2853, 1682, 1605,
4.1.6.10. 5,6-Dimethoxy-2-{3-[(pyrrolidin-1-yl)methyl]-benzyl}-
1
2,3-dihydroinden-1-one 2j. Yield: 76.7%, m.p. 79e81 ꢁC; H
NMR (CDCl3) d 7.19 (m, 4H, H-7, H-20, H-40 and H-50),
7.13 (d, 1H, J ¼ 7.6 Hz, H-60), 6.80 (s, 1H, H-4), 3.94 (s,
3H, OCH3), 3.92 (s, 3H, OCH3), 3.60 (s, 2H, PhCH2N), 3.33
(dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 4.0 Hz, PheCH2-a), 3.04 (dd,
1H, J1 ¼ 16.4 Hz, J2 ¼ 7.2 Hz, H-3a), 2.97 (m, 1H, H-2),
2.75 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼ 2.8 Hz, H-3b), 2.65 (dd,
1H, J1 ¼ 14.0 Hz, J2 ¼ 10.0 Hz, PheCH2-b), 2.54 (m, 4H,
pyrrolidine-CH2, H-2 and H-5), 1.80 (m, 4H, pyrrolidine-
CH2, H-3 and H-4); MS (ESI), m/z ¼ 366 [M þ 1]; IR (KBr):
3075, 2968, 2927, 1681, 1606, 1591, 1502, 1472, 778,
1591, 1502, 1472, 1455, 773, 702 cmꢀ1
.
4.1.6.15. 5,6-Dimethoxy-2-{4-[(piperidin-1-yl)methyl]-benzyl}-
2,3-dihydroinden-1-one 2o. Yield: 73.9%, m.p. 92e94 ꢁC; 1H
NMR (d, CDCl3): 7.22e7.26 (d, 2H, J ¼ 8.0 Hz, H-2 and H-
6), 7.17 (m, 3H, H-7, H-3 and H-5), 6.81 (s, 1H, H-4), 3.94
(s, 3H, OCH3), 3.92 (s, 3H, OCH3), 3.65 (s, 2H, PhCH2N),
3.34 (dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 4.0 Hz, PheCH2-a), 3.03
(dd, 1H, J1 ¼ 16.8 Hz, J2 ¼ 7.2 Hz, H-3a), 2.96 (m, 1H, H-
2), 2.75 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼ 2.8 Hz, H-3b), 2.59 (dd,
1H, J1 ¼ 14.0 Hz, J2 ¼ 10.4 Hz, PheCH2-b), 2.36 (m, 4H, pi-
peridine-CH2, H-2 and H-6), 1.54 (m, 4H, piperidine-CH2, H-
3 and H-5), 1.42 (m, 2H, piperidine-CH2, H-4); MS (ESI), m/
z ¼ 380 [M þ 1]; IR (KBr): 3072, 2936, 2853, 1681, 1605,
704 cmꢀ1
.
4.1.6.11. 5,6-Dimethoxy-2-{4-[(pyrrolidin-1-yl)methyl]-ben-
zyl}-2,3-dihydroinden-1-one 2k. Yield: 82.2%, m.p. 122e
124 ꢁC; 1H NMR (CDCl3) d 7.26 (d, 2H, J ¼ 8.0 Hz, H-2
and H-6), 7.18 (m, 3H, H-7, H-3 and H-5), 6.81 (s, 1H, H-
4), 3.94 (s, 3H, OCH3), 3.92 (s, 3H, OCH3), 3.65 (s, 2H,
PhCH2N), 3.34(dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 4.0 Hz, PheCH2-
a), 3.04 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼ 7.2 Hz, H-3a), 2.95 (m,
1H, H-2), 2.74 (dd, 1H, J1 ¼ 16.4 Hz, J2 ¼ 3.2 Hz, H-3b),
2.61 (dd, 1H, J1 ¼ 14.0 Hz, J2 ¼ 10.0 Hz, PheCH2-b), 2.58
(m, 4H, pyrrolidine-CH2, H-2 and H-5), 1.82 (m, 4H, pyrroli-
dine-CH2, H-3 and H-4); MS (ESI), m/z ¼ 366 [M þ 1]; IR
(KBr): 3072, 2926, 2852, 1682, 1605, 1592, 1502, 1471,
1591, 1502, 1472, 1454, 866 cmꢀ1
.
4.1.6.16. 5,6-Dimethoxy-2-{3-[(piperidin-1-yl)methyl]-benzyl}-
benzofuran-3(2H)-one 2p. Yield: 40.8%; oil; 1H NMR
(CDCl3) d 7.23 (m, 4H, H-20, H-30, H-50and H-60), 6.96 (s,
1H, H-4), 6.54 (s, 1H, H-7), 4.74 (dd, 1H, J1 ¼ 8.8 Hz,
J2 ¼ 3.6 Hz, H-2), 3.93 (s, 3H, OCH3), 3.84 (s, 3H, OCH3),
3.43 (s, 2H, PhCH2N), 3.31 (dd, 1H, J1 ¼ 14.8 Hz,
J2 ¼ 3.6 Hz, PheCH2-a), 2.90 (dd, 1H, J1 ¼ 14.8 Hz,
J2 ¼ 8.8 Hz, PheCH2-b), 2.31 (m, 4H, piperidine-CH2, H-2
and H-6), 1.52-(m, 4H, piperidine-CH2, H-3 and H-5),
1.41e1.42 (m, 2H, piperidine-CH2, H-4); MS (ESI), m/
z ¼ 382 [M þ 1]; IR (KBr): 3072, 2928, 2852, 1695, 1614,
1454, 863 cmꢀ1
.
4.1.6.12. 5,6-Dimethoxy-2-{3-[(pyrrolidin-1-yl)methyl]-ben-
zyl}-benzofuran-3(2H)-one 2l. Yield: 48.8%; oil; 1H NMR
(CDCl3) d 7.16e7.26 (m, 4H, H-20, H-40, H-50and H-60),
6.95 (s, 1H, H-4), 6.53 (s, 1H, H-7), 4.76 (dd, 1H, J1 ¼
8.4 Hz, J2 ¼ 3.6 Hz, H-2), 3.92 (s, 3H, OCH3), 3.83 (s, 3H,
OCH3), 3.57 (s, 2H, PhCH2N), 3.32(dd, 1H, J1 ¼ 14.8 Hz,
J2 ¼ 3.2 Hz, PheCH2-a), 2.93 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼
8.4 Hz, PheCH2-b), 2.44 (m, 4H, pyrrolidine-CH2, H-2 and
H-5), 1.75e1.78 (m, 4H, pyrrolidine-CH2, H-3 and H-4);
MS (ESI), m/z ¼ 368 [M þ 1]; IR (KBr): 3075, 2928, 2785,
1483, 1268, 822 cmꢀ1
4.2. Pharmacology
4.2.1. ChE assay
.
1695, 1614, 1485, 1438, 1269, 778, 710 cmꢀ1
.
AChE and BuChE activities were measured by the spectro-
photometric method with slight modification with rat cortex
homogenate and rat serum was used as the resource of
AChE and BuChE, respectively. The brain homogenate was
preincubated for 5 min with tetraisopropyl pyrophosphora-
mide (isoOMPA) (0.04 mmol/L), a selective inhibitor of
BuChE. For assay of AChE or BuChE activity, a reaction mix-
ture of 200 ml containing acetylthiocholine iodide 0.3 mmol/L
or butyrylthiocholine iodide 0.4 mmol/L, sodium phosphate
buffer (0.1 mmol/L, pH 7.4) 100 ml, homogenate or serum
4.1.6.13. 5,6-Dimethoxy-2-{4-[(pyrrolidin-1-yl)methyl] ben-
zyl}-benzofuran-3(2H)-one 2m. Yield: 50.7%; oil; H NMR
1
(CDCl3) d 7.24 (m, 4H, H-20, H-30, H-50and H-60), 6.96 (s,
1H, H-4), 6.54 (s, 1H, H-7), 4.73 (dd, 1H, J1 ¼ 8.4 Hz,
J2 ¼ 3.6 Hz, H-2), 3.93 (s, 3H, OCH3), 3.84 (s, 3H, OCH3),
3.59 (s, 2H, PhCH2N), 3.31 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼
3.2 Hz, PheCH2-a), 2.90 (dd, 1H, J1 ¼ 14.8 Hz, J2 ¼ 8.4 Hz,
PheCH2-b), 2.49 (m, 4H, pyrrolidine-CH2, H-2 and H-5),
1.75 (m, 4H, pyrrolidine-CH2, H-3 and H-4); MS (ESI),

R. Sheng et al. / European Journal of Medicinal Chemistry 44 (2009) 7e17
17
20 ml and different concentrations of test compounds 20 ml
References
were incubated at 37 ꢁC for 15 min. The reaction was termi-
nated by adding 50 ml 3% sodium lauryl sulfate, then, 50 ml
0.2% 5,50-dithio-bis(2-nitrobenzoic acid) was added to pro-
duce the yellow anion of 5-thio-2-nitrobenzoic acid. The rate
of color production was measured spectrophotometrically at
440 nm. Assays were performed with at least seven concentra-
tions of compounds and IC50 (nM drug concentration that in-
hibits 50% AChE activity) was calculated according to the
inhibition curve. Donepezil and rivastigmine were applied as
positive drugs. All samples were assayed in duplicate.
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This study was financially supported by the National Natu-
ral Science Foundation of China (30572239), the Specialized
Research Fund for the Doctoral Program of Higher Education
(20050335045), the Science and Technology Department of
Zhejiang Province of China (2005C23008) and Health Bureau
of Zhejiang Province Foundation (No.WKJ2007-016).
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