Synthesis and structure-activity relationships of novel arylalkyl 4- benzyl piperazine derivatives as σ site selective ligands

Article abstract of DOI:10.1016/S0223-5234(00)00113-6

Continuing our previous work that established that some chromones substitued by an aryl alkyl piperazino alkyl side chain are potent and selective sigma ligands and could be interesting in the treatment of psychosis, we synthesized 60 new compounds, replacing the chromone moiety by various cyclic systems. Many derivatives bind to the sigma sites in the nanomolar range and are generally selective in comparison with 5HT(1A) and the D₂ receptors. One of the most potent ligands of these series, 1-(2- naphthyl methyl)-4-benzyl piperazine 29, has been studied in various pharmacological tests. Although it doesn't have potential in the treatment of psychosis, the results we obtained confirm the data which indicates that such derivatives could be interesting in the treatment of inflammatory diseases. (C) 2000 Editions scientifiques et medicales Elsevier SAS.

Full text of DOI:10.1016/S0223-5234(00)00113-6

Eur. J. Med. Chem. 35 (2000) 107−121
© 2000 Éditions scientifiques et médicales Elsevier SAS. All rights reserved
S0223523400001136/FLA
107
Original article
Synthesis and structure–activity relationships of novel arylalkyl 4-benzyl
piperazine derivatives as σ site selective ligands
Salomé Younesa, Youssef Labssitaa, Geneviève Baziard-Mouysseta, Marc Payarda,
Marie-Claire Rettorib, Pierre Renardb, Bruno Pfeifferb, Daniel-Henri Caignardb*
aLaboratoire de chimie pharmaceutique, faculté de pharmacie, 35, chemin des Maraîchers, 31062 Toulouse, France
bInstitut de recherches international servier, 1, rue Carle Hébert, 92415 Courbevoie cedex, France
Received 5 January 1999; accepted 26 April 1999
Abstract – Continuing our previous work that established that some chromones substitued by an aryl alkyl piperazino alkyl side chain are
potent and selective sigma ligands and could be interesting in the treatment of psychosis, we synthesized 60 new compounds, replacing the
chromone moiety by various cyclic systems. Many derivatives bind to the sigma sites in the nanomolar range and are generally selective in
comparison with 5HT1A and the D2 receptors. One of the most potent ligands of these series, 1-(2-naphthyl methyl)-4-benzyl piperazine 29,
has been studied in various pharmacological tests. Although it doesn’t have potential in the treatment of psychosis, the results we obtained
confirm the data which indicates that such derivatives could be interesting in the treatment of inflammatory diseases. © 2000 Éditions
scientifiques et médicales Elsevier SAS
sigma ligand / benzylpiperazine / psychosis / inflammation
1. Introduction
For all these compounds the affinity for the sigma site
is reported, as well as for the 5HT1A and the D2 receptors.
For one of the most potent ligands, 1-(2-naphthylmethyl)-
4-benzyl piperazine 29, some complementary pharmaco-
logical tests directed to the central nervous system and
inflammation areas have been carried out to check their
potential in the treatment of psychosis and to examine the
interest of such derivatives in the inflammatory diseases
according to the results of previous works [2, 3].
ln a previous paper [1], we reported the reasons why
the synthesis of selective sigma ligands interested us after
theresultofarandomscreeningshowingthat2-[(4-benzyl-
piperazinyl)methyl]chromone 1 was a sigma ligand in the
nanomolar range. In the first part of this work we carried
out the synthesis of 28 new compounds keeping the
chromone moiety of the molecule. Their pharmacological
study proved that many of these derivatives are potent
ligands to the sigma sites and that some of them are
potentially interesting for the treatment of psychosis.
Because of these encouraging results we decided to
continue with the pharmacomodulation of the chromone
ring.
2. Chemistry
Compounds have been synthesized according to figure 1.
The synthesis of N-arylalkyl-benzylpiperazine com-
pounds has been carried out two ways. The first one
includes the step of the acyl chloride that is treated with
1-benzylpiperazine optionally substituted (method 1) to
give compounds 2, 4–6, 8, 9, 11, 13, 15, 18, 24, 28, 30, 31,
33, 35, 37, 39, 40, 42, 45, 47, 48, 50, 51, 53, 54, 56, 57
and 59. Reduction of the amidic function of some of these
compounds by lithium aluminium hydride (method 2)
First we replaced it by a chroman or a 2H-chromene.
Then we decreased the steric hindrance of this structure
and synthesized the phenoxy alkane analogues, and in a
more general way, we introduced on the 1-benzyl pipera-
zine moiety various heterocyclic or arylalkyl systems.
*Correspondence and reprints

108
Figure 1
gives compounds 3, 7, 10, 12, 14, 16, 19, 20, 23, 25, 34,
36, 38, 41, 43, 44, 46, 52, 55 and 60 in base form. The
third method consists of halogenating the primary alco-
holic function by thionyl chloride. The halogenated
compound is then reacted with 1-benzyl piperazine op-
tionally substituted to obtain the desired tertiary amine in
base form 1, 17, 21, 22, 26, 27, 29, 32, 49, 58 and 61
(method 3). Bases are transformed into hydrochloride
salts in hydrochloric isopropanol with almost quantitative
yields.
Physico-chemical data for the hydrochlorides are sum-
marized in table I.
Table I. Physico-chemical data of compounds 1–61.
Compound
A
B
R
Prepa
Yield
Base
M.p. (°C) Formula
HCI
1
2
3
4
5
6
7
8
2-chromone methyl
2-chromane carbonyl
2-chromane methyl
CH2
CH2
CH2
CH2
CO
H
H
H
OCH3
F
H
H
OCH3
H
H
H
H
H
H
H
H
H
H
3
1
2
1
1
1
2
1
1
2
1
2
1
2
1
2
3
1
2
2
3
3
2
36
52
83
65
73
63
85
31
72
85
82
77
79
88
75
86
70
87
81
81
82
78
85
238
230
> 230
198
114
237
240
222
234
216
258
203
210
229
212
189
218
235
234
> 250
246
246
214
C21H22N2O2·2HCl
C21H24N2O2·HCl
C21H26N2O·2HCl
C22H26N2O3·HCl
C21H21FN2O3
2-chromane carbonyl
2-chromane carbonyl
3-(5-methoxychromane)carbonyl
3-(5-methoxychromane)methyl
3-(5-methoxychromane)carbonyl
3-(5-methoxychromene)carbonyl
3-(5-methoxychromene)methyl
2-phenoxypropionyl
2-phenoxypropyl
2-phenoxybutyryl
2-phenoxybutyl
2-methyl-2-phenoxypropionyl
2-methyl-2-phenoxypropyl
3-phenyl propyl
2-phenoxyacetyl
2-phenoxyethyl
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
C22H26N2O3·HCl
C22H28N2O2·2HCl
C23H28N2O4·HCl
C22H24N2O3·HCl
C22H26N2O2·2HCl
C20H24N2O2·HCl
C20H26N2O·2HCl
C21H26N2O2·HCl
C21H28N2O·2HCl
C21H26N2O2·HCl
C21H28N20·2HCl
C20H26N2·2HCl
C19H22N2O2·HCl
C19H24N2O·2HCl
C20H22N2O·2HCl
C20H24N2O·2HCl
C21H26N202·2HCl
C20H23FN2O·2HCl
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
H
H
H
OCH3
H
2-benzofurylmethyl
2-dihydrobenzofurylmethyl
2-dihydrobenzofurylmethyl
2-(5-fluorodihydrobenzofurylmethyl) CH2

109
Table I. Continued.
Compound
A
B
R
Prepa
Yield
Base
M.p. (°C) Formula
HCI
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
2-tetrahydronaphtoyl
2-tetrahydronaphtylmethyl
7-methoxycoumarinylmethyl
7-methoxycoumarinylmethyl
2-naphthoyl
2-naphthylmethyl
1-naphthoyl
2-quinolylcarbonyl
2-quinolylmethyl
α-methylcinnamoyl
α-methylcinnamyl
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
ÌΗ2
ÌΗ2
ÌΗ2
ÌΗ2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
H
H
H
OCH3
H
H
H
H
H
H
H
OCH3
OCH3
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
1
2
3
3
1
3
l
60
79
80
83
73
76
76
65
83
85
78
89
82
70
78
81
56
86
81
80
81
75
88
86
65
71
83
88
86
80
64
80
82
75
68
66
82
64
197
191
246
208
238
230
212
188
216
202
246
238
248
220
> 260
250
211
> 210
256
246
238
254
222
230
240
250
258
> 260
248
240
154
> 220
> 260
213
248
250
> 250
264
C22H26N2O·HCl
C22H28N2·2HCl
C22H24N2O3·2HCl
C23H26N2O4·2HCl
C22H22N2O·HCl
C22H24N2·2HCl
C22H22N2O·HCl
C21H21N3O·2HCl
C21H23N3·3HCl
C21H24N2O.HCl
C21H26N2·2HCl
C22H26N2O2·HCl
C22H28N2O·2HCl
C20H21ClN2O·HCl
C20H23ClN2·2HCl
C21H24N2O2·HCl
C22H26N2O3·HCl
C22H28N2O2·2HCl
C2lH22N2O3·HCl
C21H24N2O2·2HCl
C23H30N2O3·2HCl
C18H20N2O2·HCl
C18H22N2O·2HCl
C18H20N2OS·HCl
C20H24N2O2·HCl
C20H26N2O·2HCl
C18H19ClN2O·HCl
C19H22N2O2·HCl
C19H24N2O·2HCl
C19H22N2O2·HCl
C20H24N2O3·HCl
C20H26N2O2·2HCl
C19H20N2O3·HCl
C17H19N3O·2HCl
C17H21N3·3HCl
C22H30N2O·HCl
C16H20N2O·2HCl
C16H20N4O2·2HCl
1
3
1
2
1
2
1
2
1
1
2
1
2
2
1
2
1
1
3
1
1
2
1
1
2
1
1
3
1
2
3
α-methylcinnamoyl
α-methylcinnamyl
4-chlorocinnamoyl
4-chlorocinnamyl
4-methoxycinnamoyl
3,4-dimethoxycinnamoyl
3,4-dimethoxycinnamyl
3,4-methylene dioxycinnamoyl
3,4-methylene dioxycinnamyl
3,4,5-trimethoxycinnamyl
2-(2-furyl)propenoyl
2-(2-furyl)propenyl
2-(2-thienyl)propenoyl
4-methoxyphenylacetyl
4-methoxyphenylethyl
4-chlorobenzoyl
2-methoxybenzoyl
2-methoxybenzyl
4-methoxybenzoyl
3,4-dimethoxybenzoyl
3,4-dimethoxybenzyl
3,4-methylene dioxybenzoyl
2-pyridylcarbonyl
2-pyridylmethyl
1-adamantane carbonyl
2-furylmethyl
H
H
H
H
6-uracyl methyl
aPreparation = preparation method (see Experimental Section).
3. Pharmacology
Compound 29 has also been studied on two tests
predictive for antipsychotic activity.
— a biochemical one researching the effect on
N-methyl-D-aspartate (NMDA).
— a behavioural one looking at the potential effect on
hyperactivity induced by amphetamine and research for
its potential cataleptic effect.
All the compounds 1–61 were evaluated for their
affinity for the sigma sites as well as for the 5HT1A and
the D2 receptors.
For compounds 16, 29 and 38, having the highest
affinity for the sigma sites, the binding for the two sigma
subtypes was determined.
After the evidence that compound 29 had no antipsy-
chotic activity we decided to research its anti-

110
inflammatory potential, since recent works mention this
possibility for sigma ligands. The test we used is the
carrageenan planta oedema.
according to the value of the A group. Some compounds
have a binding affinity for the sigma site that is in the
subnanomolar range. These are compounds 16, 20, 29,
34, 36 and 38. The most potent compounds, 20 and 38,
have an IC50 between 0.3 and 0.4 nM. It appears that
these six derivatives are all amines. In comparison, the
most potent amides, 28 and 35, have an IC50 which is 2
nM, that is to say almost ten-fold higher than that of the
best amines. The most potent amines, except 29, do not
correspond exactly to the amides that best bind to the
sigma sites.
4. Results and discussion
The results of binding of the 60 new compounds are
indicated in table II. There are 30 amides and 30 amines
Table II. Binding of 1-benzylpiperazines and related derivatives.
Compound
A
B
R
H
σ
5ΗΤ1A
> 105
D2
1
CH2
3
> 105
2
3
4
CH2
CH2
CH2
H
H
9
2 × 104
2 000
100
10
10
OCH3
300
> 105
> 105
5
6
CO
F
3 × 104
> 105
> 105
> 105
> 105
CH2
H
300
7
8
9
CH2
CH2
CH2
H
OCH3
H
20
50
400
200
800
> 105
> 105
> 105
> 105

111
Table II. Continued.
Compound
A
B
R
H
σ
5ΗΤ1A
D2
10
CH2
10
300
300
11
CH2
H
30
> 105
> 105
12
13
CH2
CH2
H
H
4
1 000
700
20
> 105
> 105
14
15
CH2
CH2
H
H
30
40
300
> 105
> 105
> 105
16
CH2
H
0.9
> 105
> 105
17
18
CH2
CH2
H
H
20
40
> 105
> 105
> 105
> 105
19
20
CH2
CH2
H
H
3
200
600
0.4
5 000
1 000
21
22
23
CH2
CH2
CH2
H
OCH3
H
7
9
9
> 105
80
> 105
600
300
200

112
Table II. Continued.
Compound
A
B
R
H
σ
5ΗΤ1A
> 105
D2
24
CH2
400
> 105
25
26
CH2
CH2
H
H
3
1
100
104
200
2 × 104
27
28
CH2
CH2
OCH3
H
1
2
5 × 104
8 × 104
4 000
900
29
30
CH2
CH2
H
H
0.6
7
3 000
2 000
4 × 104
3 × 104
31
32
CH2
CH2
H
H
1 000
1
5 000
2 000
5 000
9 000
33
CH2
H
5
3 × 104
6 000
34
35
CH2
CH2
H
0.7
2
300
400
OCH3
> 105
3 000
36
CH2
OCH3
0.8
900
500

113
Table II. Continued.
Compound
A
B
R
H
σ
5ΗΤ1A
> 105
D2
37
CH2
70
2 × 104
38
39
CH2
CH2
H
H
0.3
8 000
8 × 104
> 105
3 000
> 105
40
CH2
H
5 000
> 105
> 105
41
42
CH2
CH2
H
H
40
10
> 105
> 105
2 × 104
3 × 104
43
44
CH2
CH2
H
H
30
> 105
> 105
> 105
> 105
100
45
CH2
H
1 000
> 105
> 105
46
47
CH2
CH2
H
H
0.9
600
3 000
1 000
> 105
> 105
48
CH2
H
104
> 105
> 105
49
50
CH2
CH2
H
H
100
20
> 105
> 105
> 105
> 105
51
CH2
H
40
> 105
> 105

114
Table II. Continued.
Compound
A
B
R
H
σ
5ΗΤ1A
2 × 104
D2
52
CH2
2
800
53
54
CH2
CH2
H
H
100
> 105
> 105
> 105
> 105
1 000
55
56
CH2
CH2
H
H
90
> 105
> 105
> 105
> 105
200
57
58
CH2
CH2
H
H
1 000
50
> 105
> 105
> 105
2 × 104
59
CH2
H
5 000
> 105
8 000
60
61
CH2
CH2
H
H
4
5 × 104
2 × 104
104
100
> 105
However, it appears that the replacement for an amine
derivative of the methylene group by a carbonyl, i.e., the
change from an amine to the corresponding amide almost
always decreases the affinity for the sigma site, but the
importance of the loss is very variable. The most impor-
tant diminution noticed after this structural change con-
cerns compounds 31 and 32, and 45 and 46. For these two
paires, the loss is approximately 1 000-fold. In some
particular cases this structural change does not modify, or
even slightly increases the affinity for the sigma sites. See
compounds 2 and 3, 13 and 14, and 42 and 43.
The worst ligands for the sigma sites (IC50 higher than
or equal to 1 000 nM) are compounds 5, 31, 39, 40, 45,
47, 48, 54, 57 and 59. All are amides, this confirms that
this chemical function is not as good as the amine one for
obtaining a sigma ligand.
In a small homogeneous series it appears that the
increase of the aromaticity of the A group enhances the
affinity for the sigma sites. For instance the benzofuran
derivative 20 has an IC50 that is 0.4 nM instead of 7 nM
for the dihydrobenzofuran compound 21. Tetralin deriva-
tives 24 and 25, respectively, have IC50 equal to 400 and

115
3 nM, instead of 2 and 0.6 nM for the corresponding
naphthalenic analogues 28 and 29.
Gi/o proteins were inactivated with pertussis toxin
(PTX), and the potentiation of NMDA response induced
by compound 29 was completely abolished, showing that
compound 29 interacted on the σ site coupled to Gi/o
proteins, i.e. the σ1 site.
Introduction of a carbonyl group in the 4 position of
the piperazine moiety instead of a methylene group
dramatically decreases the affinity for the sigma sites
(compound 5). Introduction of a methoxy group on the
benzyl substituent of the piperazine modifies in various
ways the affinity for the sigma sites (4, 8, 22, 27, 35, 36).
Most of our sigma ligands are selective over 5HT1A
and D2 receptors. If we consider only those of our sigma
ligands that have an IC50 lower than 1 000 nM, it appears
that among these 51 compounds only six have a ratio
[IC50 D2]:[IC50 σ] and a ratio [IC50 5HT1A]:[IC50 σ]
lower than 100, they are compounds 3, 7, 10, 22, 23, 25;
two more have only the ratio [IC50 5HT1A]:[IC50 σ]
lower than 100, they are 14 and 19.
Using electrophysiological methods compound 29
dose dependently potentiated the NMDA response after
intravenous administration, the minimal effective dose
was 10 mg/kg, while the dose of 3 mg/kg induced a slight
but not significant increase of the NMDA response. The
maximum effect was obtained with the dose of 100 mg/
kg, which induced a 50% increase of the NMDA re-
sponse. In about 70% of the neurones tested, compound
29 also increased the neuronal response to quisqualate.
The effects described above were also partially reversed
with a dose of haloperidol of 100 mg/kg iv.
Except for the fact that all these nonselective deriva-
tives are diamines, it seems quite hard to disclose other
structure–activity relationships concerning the selectivity
of our sigma ligands. Even the fact that all our nonselec-
tive σ ligands are amines is sufficient to predict nonse-
lective derivatives, since many amines are very potent
and selective sigma ligands over 5HT1A and D2. See for
instance compounds 1, 12, 16, 20, 46, 52 and 60, and
even the most selective 38, which has a ratio 2.6 × 104
over 5HT1A and 2.6 × 105 over D2.
Compound 16 is a better σ1 selective ligand since its
IC50 for the σ1 site is 0.69 nM and its IC50 for the σ2 site
is over 77 nM. Compounds 29 and 38 have IC50 values
for the σ1 site that are, respectively, 1.3 nM and 1.6 nM
and for the σ2 site, 23 nM and 15 nM. These compounds
preferentially bind to the σ1 over the σ2 binding sites.
According to the binding data we decided to submit
one compound to complementary studies in order to
research its antipsychotic potential in accordance with
our previous work [1]. We selected compound 29, one of
the most potent sigma ligands according to the results of
table II.
4.2. Behavioural tests
Compound 29 was tested for its potential effect on
hyperactivity induced by amphetamine, which is thought
to result from dopaminergic activation in the limbic
system. Selective antagonism of amphetamine induced
hyperactivity is therefore considered to be predictive of
an antipsychotic activity in the absence of extrapyramidal
side-effects. Compound 29 poorly antagonized the hyper-
activity induced by amphetamine in mice. At doses of 8,
16 and 32 mg.kg–1 ip, the antagonism was, respectively,
3%, 14% and 21% (NS). In comparison, Haloperidol
(0.125 mg.kg–1 ip) completely antagonized the amphet-
amine induced hyperactivity.
4.3. Inflammation
In the carrageenan planta oedema test at a 100 mg.kg–1
po dose, compound 29 significantly reduced the oedema
volume. Two hours after administration, the percentage of
reduction was 52.9% (42.3% with a 10 mg.kg–1 po
indomethacin dose) and 4 h after administration this
value was 30.7% (39.2% with a 10 mg.kg–1 indomethacin
po dose).
4.1. Biochemical tests
Compound 29 was tested for its potential effect on
N-methyl-D-aspartate (NMDA) induced release of
[3H]noradrenaline (NA) from preloaded hippocampal
slices made from Sprague-Dawley (SD) rats. Compound
29 potentiated, in a concentration-dependent manner,
NMDA-induced [3H]NA release without affecting the
basal out flows. The maximal response observed at the
concentration of 1 mmol/L was an 800% increase of the
NMDA response. Haloperidol, which did not modify
NMDA-evoked [3H]NA release by itself partially pre-
vented the effects of compound 29 (63–78% prevention).
Compound 29 showed a high affinity and selectivity
for the σ sites and it reduces oedema volume. Therefore,
owing to the selectivity of this compound 29 for σ sites,
it can be assumed that oedema volume reduction and
affinity are related. Compound 29 presents an original
pharmacological profile of potential drug, at low doses,
for treatment of inflammation disease.

116
5. Experimental protocols
recrystallized from isopropanol. IR (KBr) ν cm–1: 3 025,
3 000, 2 995, 2 850, 2 800 (CH, CH2, CH3); 1 600 (C=C).
5.1. Chemistry
5.1.1.1. 1-(2-Chromanylmethyl)-4-benzylpiperazine 1
All melting points were determined on a Kofler appa-
ratus and are uncorrected. Infrared spectra were obtained
on a Perkin-Elmer 983 G apparatus using films for liquids
1H-NMR (CDCl3), δ ppm: 2.63 (m, 8H, piperaz.); 3.48
(s, 2H, Ar–CH2–N); 3.52 (s, 2H, Ar–CH2–N); 6.43 (s,
1H, H3); 7.52 (m, 8H, Ar); 8.20 (dd, 1H, H5).
1
or inclusion in KBr pellets for solids. H-NMR spectra
were recorded using a Bruker AC-200 spectrometer using
Me4Si as an internal standard. Silica-gel TLC was per-
formed on Merck 60 F-254 precoated sheets. Elemental
analyses are in agreement with the accepted norms.
5.1.1.2. 1-(2-Chromanylcarbonyl)-4-
benzylpiperazine hydrochloride 2
1H-NMR (DMSO-d6),
δ
ppm: 2.42 (m, 2H,
CH2–CH2–CH); 2.51–2.82 (m, 8H, piperaz.); 2.89 (t, 2H,
CH2–CH2–CH); 3.52 (s, 2H, CH2–Ar); 4.74 (m, 1H,
O–CH–CO); 7.54 (m, 9H, Ar); 11.62 (s broad, 1H, NH+).
5.1.1. General procedure
Method 1:
A solution of acyl chloride (0.01 mol) in methylene
chloride (100 mL) was added to
a solution of
5.1.1.3. 1-(2-Chromanylmethyl)-4-benzylpiperazine 3
1H-NMR (CDCl3), δ ppm: 1.66–1.82 (m, 2H,
CH2–CH–O); 1.97–2.88 (m, 12H, 8H piperaz., N–CH2
and Ar–CH2); 3.52 (s, 2H, CH2–N); 4.18 (m, 1H,
CH2–CH–O); 6.78–7.33 (m, 9H, Ar).
1-benzylpiperazine (0.01 mol) in the same solvent. The
mixture was stirred at room temperature for 5 h or until
thin layer chromatography showed the reaction to be
complete. After filtration, the compound obtained in
hydrochloride form was crystallized from ethanol. IR
(KBr) ν cm–1: 3 150, 3 090, 3 035, 2 810 (CH, CH2);
2 600–2 400 (NH+); 1 650 (CO); 1 610 (C=C).
5.1.1.4. 1-(2-Chromanylcarbonyl)-4-
(4≠-methoxybenzyl) piperazine hydrochloride 4
Method 2:
1H-NMR (DMSO-d6),
δ
ppm: 2.60 (m, 4H,
0.03 mol of amide, obtained according to method 1,
was dissolved in 150 mL of anhydrous tetrahydrofuran.
1 g (0.03 mol) of lithium aluminium hydride in pellet
form was added. The mixture was stirred at room
temperature for 24 h. Then, the excess hydride was
destroyed by addition of 6 mL of ethyl acetate, 6 mL of
methanol and 2 mL of water. Solvents were evaporated
under reduced pressure and the residue was taken off with
150 mL of water and extracted by 3 × 30 mL of methyl-
ene chloride. After drying (MgS04) and concentration
under reduced pressure, the residue was purified by silica
gel column chromatography using methylene chloride as
eluent. The isolated free base was further converted into
its required hydrochloride salt with hydrochloric isopro-
panol and recrystallized from isopropanol.
–CH2–CH2–CH–O); 3.40 (m, 6H, piperaz.); 3.90 (s, 3H,
OCH3); 4.17–4.26 (m, 4H, 2H piperaz. and CH2–Ar);
5.18 (m, 1H, CH–CO); 6.81–7.68 (m, 8H, Ar); 11.67 (s
broad, 1H, NH+).
5.1.1.5. 1-(2-Chromanylcarbonyl)-4-
(4≠-fluorobenzoyl) piperazine 5
1H-NMR (CDCl3), δ ppm: 2.23 (m, 2H, CH2–CH2–O);
2.88 (m, 2H, CH2–CH); 3.68 (m, 8H, piperaz.); 4.77 (t,
1H, O–CH–CO); 7.13 (m, 8H, Ar).
5.1.1.6. 1-[3-(5-Methoxychromanyl)carbonyl-
4-benzylpiperazine hydrochloride 6
1H-NMR (DMSO-d6), δ ppm: 2.84 (m, 3H, Ar–CH2
and CH–CO); 3.28 (m, 8H, piperaz.); 3.88 (s, 3H, OCH3);
4.39 (m, 2H, OCH2); 4.60 (m, 2H, CH2–Ar); 6.51–7.72
(m, 8H, Ar); 11.64 (s broad, 1H, NH+).
Method 3:
0.03 mol of 4-benzylpiperazine optionally methoxy-
lated, 0.03 mole of halogenomethylated compound and
0.03 mol (4.14 g) of potassium carbonate were added to
150 mL of anhydrous tetrahydrofuran. The reaction mix-
ture was refluxed for 24 h or until thin layer chromatog-
raphy showed the reaction to be complete. The solution
was filtered and evaporated under reduced pressure. The
solid so obtained was purified by silica gel column
chromatography using methylene chloride as eluent. The
isolated free base was further converted into its required
hydrochloride salt with hydrochloric isopropanol and
5.1.1.7. 1-[3-(5-Methoxychromanyl)methyl]-
4-benzylpiperazine 7
1H-NMR (CDCl3), δ ppm: 2.20–2.82 (m, 13H,
CH2–N,
8H
piperaz.,
CH2–CH–CH2–O
and
CH2–CH–CH2–O); 3.41 (s, 2H, N–CH2–Ar); 3.89 (s, 3H,
O-CH3); 4.27 (m, 2H, CH2–CH–CH2–O); 6.37 (m, 8H,
Ar).

117
5.1.1.8. 1-[3-(5-Methoxy-3-chromanyl]carbonyl-4-(4≠-
methoxybenzyl)piperazine hydrochloride 8
5.1.1.16. 1-(2-Phenoxy-2-methylpropyl)-
4-benzylpiperazine 16
1H-NMR (CDCl3), δ ppm: 1.26 (s, 6H, –C(CH3)2);
2.46 (t, 4H, piperaz.); 2.52 (s, 2H, CH2–N); 2.67 (t, 4H,
piperaz.); 3.50 (S, 2H, N–CH2–Ar); 6.95–7.34 (m, 10H,
Ar).
1H-NMR (DMSO-d6), δ ppm: 2.77 (m, 3H, Ar–CH2
and CH–CO); 3.34 (m, 8H, piperaz.); 3.78 (s, 6H,
2OCH3); 4.09–4.12 (m, 4H, OCH2 and N–CH2–Ar);
6.40–7.50 (m, 7H, Ar); 11.14 (s, 1H, NH+).
5.1.1.17. 1-(2-Phenylethyl)-4-benzylpiperazine 17
1H-NMR (CDCl3), δ ppm: 1.79 (m, 2H, Ar–CH2–
CH2–CH2–N); 2.35 (t, 2H, Ar–CH2–CH2–CH2–N), 2.46
(m, 8H, piperaz.); 2.60 (t, 2H, Ar–CH2–CH2–CH2–N);
3.48 (s, 2H, N–CH2–Ar); 7.10–7.34 (m, 10H, Ar).
5.1.1.9. 1-[3-(5-Methoxy-∆3-chromenyl)carbonyl-
4-benzylpiperazine hydrochloride 9
1H-NMR (DMSO-d6), δ ppm: 3.42 (m, 8H, piperaz.);
3.81 (s, 3H, OCH3); 4.23 (s, 1H, CH=C–CO); 4.31 (s, 2H,
N–CH2–Ar); 4.74 (s, 2H, CH2–O); 7.43 (m, 8H, Ar);
11.68 (s, 1H, NH+).
5.1.1.18. 1-(2-Phenoxyacetyl)-4-benzylpiperazine
hydrochloride 18
5.1.1.10. 1-[3-(5-Methoxy-D3-chromenyl)methyl-
4-benzylpiperazine 10
1H-NMR (DMSO-d6), δ ppm: 3.44 (m, 8H, piperaz.);
4.44 (s, 2H, CH2–Ar); 4.99 (s, 2H, O–CH2–CO); 7.54 (m,
10H, Ar); 11.73 (s broad, 1H, NH+).
1H-NMR (CDCl3), δ ppm: 2.46 (m, 8H, piperaz.); 3.06
(s, 2H, CH2–N); 3.51 (s, 2H, N–CH2–Ar); 3.80 (1s, 3H,
O–CH3), 4.70 (s, 2H, O–CH2); 6.39–7.32 (m, 9H, Ar and
H4).
5.1.1.19. 1-(2-Phenoxyethyl)-4-benzylpiperazine 19
1H-NMR (CDCl3), δ ppm: 2.75 (t, 2H, CH2N); 3.45 (s,
2H, N–CH2–Ar); 3.48 (m, 8H, piperaz.); 4.02 (t, 2H,
CH2–O–Ar); 7.54 (m, 10H, Ar).
5.1.1.11. 1-(2-Phenoxypropionyl)-4-benzylpiperazine
hydrochloride 11
1H-NMR (DMSO-d6), δ ppm: 1.65 (d, 3H, CH3);
3.47–4.46 (m, 10H, piperaz. and CH2–Ar); 5.37 (m, 1H,
O–CH–CO) 6.90–7.68 (m, 10H, Ar); 11.11 (s broad, 1H,
NH+).
5.1.1.20. 1-(2-Benzofurylmethyl)-4-benzylpiperazine 20
1H-NMR (CDCl3), δ ppm: 2.57 (m, 8H, piperaz.); 3.36
(s, 2H, CH2–N); 3.55 (s, 2H, N–CH2–Ar); 6.43 (s, 1H,
CH=C); 6.98 (m, 9H, Ar).
5.1.1.21. 1-[2-(2,3-Dihydrobenzofuryl)methyl-
4-benzylpiperazine 21
5.1.1.12. 1-(2-Phenoxy-n-propyl)-4-benzylpiperazine 12
1H-NMR (CDCl3), δ ppm: 1.27 (d, 3H, CH3–CH);
3.47 (s, 2H, CH2–Ar); 3.51 (m, 10H, CH2–N and 8H
piperaz.); 4.52 (q, 1H, CH–CH3); 6.84–7.30 (m, 10H,
Ar).
1H-NMR (CDCl3), δ ppm: 2.53 (m, 8H, piperaz.);
2.69–3.26 (m, 4H, CH2–CH–CH2–N); 3.49 (s, 2H,
N–CH2–Ar); 4.93 (m, 1H, O–CH–CH2–N); 6.74–7.32
(m, 9H, Ar).
5.1.1.13. 1-(2-Phenoxybutyryl)-4-benzylpiperazine
hydrochloride 13
5.1.1.22. 1-[2-(2,3-Dihydrobenzofuryl)methyl]-
4-(4≠-methoxybenzyl)piperazine 22
1H-NMR (DMSO-d6), δ ppm: 1.13 (t, 3H, CH2–CH3);
1.89 (q, 2H, CH2–CH3); 3.55 (m, 8H, piperaz.); 4.44 (s,
2H, CH2–Ar); 5.15 (t, 1H, CH–C2H5); 7.65 (m, 10H, Ar);
12.04 (s, 1H, NH+).
1H-NMR (CDCl3), δ ppm: 2.52 (m, 8H, piperaz.);
2.71–3.30 (m, 4H, –CH2–CH–CH2–N), 3.51 (1s, 2H,
N–CH2–Ar); 3.80 (s, 3H, Ar–OCH3); 4.94 (m, 1H,
O–CH–CH2); 6.63–7.34 (m, 8H, Ar).
5.1.1.14. 1-(2-Phenoxy-n-butyl)-4-benzylpiperazine 14
1H-NMR (CDCl3), δ ppm: 0.94 (t, 3H, CH2–CH3);
1.70 (q, 2H, CH2–CH3) 2.43–2.70 (m, 10H, CH2–N and
8H piperaz.); 3.46 (s, 2H, CH2–Ar); 4.26–4.37 (m, 1H,
CH–CH2–N); 6.84–7.30 (m, 10H, Ar).
5.1.1.23. 1-[2-(5-Fluoro-2,3-dihydrobenzofuryl)methyl]-
4-benzylpiperazine 23
1H-NMR (CDCl3), δ ppm: 2.50–2.79 (m, 10H, CH2–N
and 8H piperaz.); 3.05 (2dd, 2H, CH2–CH–O); 3.51 (s,
2H, N–CH2–Ar); 4.94 (m, 1H, CH2–CH–O); 6.63–7.34
(m, 8H, Ar).
5.1.1.15. 1-(2-Phenoxyisobutyryl)-4-benzylpiperazine
hydrochloride 15
5.1.1.24. 1-[2-(1,2,3,4-Tetrahydronaphthoyl)]-4-
1H-NMR (DMSO-d6), δ ppm: 1.66 (s, 6H, 2CH3);
3.47–4.68 (m, 10H, piperaz. and CH2–Ar); 7 42 (m, 10H,
Ar), 11.56 (s broad, 1H, NH+).
benzylpiperazine hydrochloride 24
1H-NMR (DMSO-d6),
δ
ppm: 1.76 (m, 2H,
Ar–CH2–CH2); 2.79 (m, 5H, Ar–CH2–CH2 and Ar–CH2–

118
CH); 3.13 (m, 6H, piperaz.); 4.31 (m, 4H, 2H piperaz.
and Ar–CH2); 7.35 (m, 9H, Ar); 11.63 (s broad, 1H,
NH+).
N–CH2–Ar); 6.71 (s, 1H, CH=C); 7.56 (m, 10H, Ar);
11.53 (s broad, 1H, NH+).
5.1.1.34. 1-(α-Methylcinnamyl)-4-benzylpiperazine 34
1H-NMR (CDCl3), δ ppm: 1.89 (S, 3H, CH3–C=CH);
2.48 (m, 8H, piperaz.); 3.00 (s, 2H, C=C–CH2); 3.52, (s,
2H, N–CH2–Ar); 6.41 (s, 1H, CH=); 7.14–7.35 (m, 10H,
Ar).
5.1.1.25. 1-[2-(1,2,3,4-Tetrahydronaphthylmethyl)]-
4-benzylpiperazine 25
1H-NMR (CDCl3),
δ
ppm: 1.35 (m, 2H,
Ar–CH2–CH2); 1.94 (m, 2H, Ar–CH2); 2.25 (d, 2H,
CH2–N); 2.37 (m, 8H, piperaz.); 2.73–2.93 (m, 3H,
CH2–CH); 3.49 (s, 2H, N–CH2–Ar); 7.05–7.33 (m, 9H,
Ar).
5.1.1.35. 1-[3-(3-Phenyl-2-methylacryloyl)-4-(4≠-
methoxybenzyl)]piperazine hydrochloride 35
1H-NMR (DMSO-d6),
δ
ppm: 2.13 (s, 3H,
5.1.1.26. 1-[4-(7-Methoxy-4-coumarinyl)methyl]-
4-benzylpiperazine 26
CH3–C=CH); 3.34 (m, 6H, piperaz.); 3.89 (s, 3H, OCH3);
4.37 (m, 4H, 2H piperaz. and N–CH2–Ar); 6.70 (s, 1H,
CH=); 7.40 (m, 9H, Ar); 11.72 (s broad, 1H, NH+).
1H-NMR (CDCl3), δ ppm: 2.29 (m, 8H, piperaz.);
3.58–4.04 (2s, 4H, 2CH2–N); 3.86 (s, 3H, O–CH3); 4.70
(s, 1H, CO–CH); 6.85–7.70 (m, 8H, Ar).
5.1.1.36. 1-(α-Methylcinnamyl)-4-(4≠-
5.1.1.27. 1-[4-(7-Methoxy-4-coumarinyl)methyl]-
4-(4≠-methoxybenzyl)piperazine 27
methoxybenzyl) piperazine 36
1H-NMR (CDCl3), δ ppm: 1.87 (s, 3H, CH3–C=CH);
2.46 (m, 8H, piperaz.); 3.00 (s, 2H, C=C–CH2); 3.46 (s,
2H, N–CH2–Ar); 3.79 (s, 3H, OCH3); 6.41 (s, 1H, CH=);
6.81–7.36 (m, 9H, Ar).
1H-NMR (CDCl3), δ ppm: 2.50 (m, 8H, piperaz.);
3.45–3.48 (2s, 4H, 2CH2–N); 3.78 and 3.81 (2s, 6H,
2OCH3); 6.15 (s, 1H, CO–CH); 6.78–7.70 (m, 7H, Ar).
5.1.1.28. 1-(2-Naphthoyl)-4-benzylpiperazine
hyrochloride 28
5.1.1.37. 1-(4-Chlorocinnamoyl)-4-benzylpiperazine
hydrochloride 37
1H-NMR (DMSO-d6), δ ppm: 3.53 (m, 8H, piperaz.);
4.34 (s, 2H, CH2–Ar); 7.73 (m, 12H, Ar); 11.55 (s broad,
1H, NH+).
1H-NMR (DMSO-d6), δ ppm: 3.30 (m, 6H, piperaz.);
4.34 (s, 2H, –CH2–Ar); 4.56 (m, 2H, piperaz.); 7.54 (m,
11H, Ar and CH=CH); 11.81 (s broad, 1H, NH+).
5.1.1.29. 1-(2-Naphthylmethyl)-4-benzylpiperazine 29
1H-NMR (CDCl3), δ ppm: 2.51 (m, 8H, piperaz.); 3.52
(s, 2H, N–CH2–Ar); 3.66 (s, 2H, Ar–CH2–N); 7.25–7.82
(m, 12H, Ar).
5.1.1.38. 1-(4-Chlorocinnamyl)-4-benzylpiperazine 38
1H-NMR (CDCl3), δ ppm: 2.61 (m 8H, piperaz.); 3.15
(d, 2H, CH2–C=CH, J = 6 Hz); 3.54 (s, 2H, Ar–CH2–N);
6.13 (dt, 1H, Ar–CH=CH–CH2); 6.46 (d, 1H,
Ar–CH=CH–CH2); 6.92 (m, 9H, Ar).
5.1.1.30. 1-(1-Naphthoyl)-4-benzylpiperazine
hydrochloride 30
1H-NMR (DMSO-d6), δ ppm: 3.47 (m, 8H, piperaz.);
4.34 (m, 2H, CH2–Ar); 7.73 (m, 12H, Ar); 11.78 (s broad,
1H, NH+).
5.1.1.39. 1-(4-Methoxycinnamoyl)-4-benzylpiperazine
hydrochloride 39
1H-NMR (DMSO-d6), δ ppm: 3.45–4.65 (m, 10H,
piperaz. and CH2–Ar); 3.91 (s, 3H, CH3O); 7.08 (d, 2H,
Ar); 7.23 (d, 1H, CH=CH–CO); 7.61 (d, 1H,
CH=CH–CO); 7.63 (m, 5H, Ar); 7.72 (d, 2H, Ar); 11.14
(s broad, 1H, NH+).
5.1.1.31. 1-(2-Quinolinylcarbonyl)-4-benzylpiperazine
hydrochloride 31
1H-NMR (DMSO-d6), δ ppm: 3.70 (m, 8H, piperaz.);
4.38 (s, 2H, CH2–Ar); 8.01 (m, 11H, Ar); 11.83 (s broad,
2H, NH+).
5.1.1.32. 1-(2-Quinolinylmethyl)-4-benzylpiperazine 32
1H-NMR (CDCl3), δ ppm: 2.53 (m, 8H, piperaz.); 3.53
and 3.84 (2s, 4H, 2CH2); 7.25–8.00 (m, 11H, Ar).
5.1.1.40. 1-(3,4-Dimethoxycinnamoyl)-4-
benzylpiperazine hydrochloride 40
1H-NMR (DMSO-d6), δ ppm: 3.57 (m, 6H, piperaz.);
3.90 and 3.93 (2s, 6H, 2OCH3); 4.45 (s, 2H, CH2–Ar);
4.66 (m, 2H, piperaz.); 7.25 (d, 1H, CH=CH–CO); 7.52
(d, 1H, CH–C=O); 7.56 (m, 8H, Ar); 11.87 (s broad, 1H,
NH+).
5.1.1.33. 1-(3-Phenyl-2-methylacryloyl)-4-
benzylpiperazine hydrochloride 33
1H-NMR (DMSO-d6), δ ppm: 2.13 (s, 3H, CH3); 3.33
(m, 6H, piperaz.); 4.40 (m, 4H, 2H piperaz. and

119
5.1.1.41. 1-(3,4-Dimethoxycinnamyl)-4-
benzylpiperazine 41
5.1.1.48. 1-(4-Methoxyphenylacetyl)-4-benzylpiperazine
hydrochloride 48
1H-NMR (CDCl3), δ ppm: 3.04 (m, 8H, piperaz.); 3.88
and 3.89 (2s, 6H, 2OCH3); 3.11 (d, 2H, CH=CH–CH2);
1H-NMR (DMSO-d6), δ ppm: 3.48–4.43 (m, 12H,
piperaz. and 2CH2–Ar); 3.91 (s, 3H, CH3O); 7.35 (m, 9H,
Ar); 11.82 (s broad, 1H, NH+).
3.52
(s,
2H,
N–CH2–Ar);
6.10
(td,
1H,
Ar–CH=CH–CH2); 6.41 (d, 1H, Ar–CH=CH–CH2);
6.29–7.30 (m, 8H, Ar).
5.1.1.49. 1-[2-(4-Methoxyphenyl)ethyl)]-4-
benzylpiperazine 49
1H-NMR (CDCl3), δ ppm: 2.55 (m, 10H, piperaz. and
CH2–N); 2.73 (t, 2H, Ar–CH2–CH2–N); 3.49 (s, 2H,
N–CH2–Ar); 3.72 (s, 3H, CH3O–Ar); 6.77–7.30 (m, 9H,
Ar).
5.1.1.42. 1-(3,4-Methylenedioxycinnamoyl)-4-
benzylpiperazine hydrochloride 42
1H-NMR (DMSO-d6), δ ppm: 3.84 (m, 10H, piperaz.
and CH2–Ar); 6.07 (s, 2H, CH2O2), 7.18 (d, 1H,
CH=CH–CO); 7.50 (d, 1H, CH=CH–CO); 7.24 (m, 8H,
Ar); 11.04 (s broad, 1H, NH+).
5.1.1.50. 1-(4-Chlorobenzoyl-4-benzylpiperazine
hydrochloride 50
1H-NMR (DMSO-d6), δ ppm: 3.71 (m, 10H, piperaz.
and CH2–Ar); 7.49 (m, 9H, Ar); 11.27 (s broad, 1H,
NH+).
5.1.1.43. 1-(3,4-Methylenedioxycinnamyl)-4-
benzylpiperazine 43
1H-NMR (CDCl3), δ ppm: 2.25 (m, 8H, piperaz.); 3.14
(d, 2H, CH2–CH=CH); 3.52 (s, 2H, N–CH2–Ar); 6.01 (s,
2H, CH2O2); 6.12 (td, 1H, Ar–CH=CH–CH2); 6.45 (d,
1H, Ar–CH=CH–CH2); 6.37–7.32 (m, 8H, Ar).
5.1.1.51. 1-(2-Methoxybenzoyl)-4-benzylpiperazine
hydrochloride 51
1H-NMR (DMSO-d6), δ ppm: 3.90 (s, 3H, OCH3);
3.96 (m, 10H, piperaz. and CH2–Ar); 7.42 (m, 9H, Ar);
11.82 (s broad, 1H, NH+).
5.1.1.44. 1-(3,4,5-Trimethoxycinnamyl)-4-
benzylpiperazine 44
1H-NMR (CDCl3), δ ppm: 3.04 (m, 8H, piperaz.); 3.13
(d, 2H, CH2–CH=CH); 3.48 (s, 2H, N–CH2–Ar); 3.70 (s,
3H, OCH3); 3.85 (s, 6H, 2OCH3); 6.35 (s, 2H, Ar); 6.39
5.1.1.52. 1-(2-Methoxybenzyl)-4-benzylpiperazine 52
1H-NMR (CDCl3), δ ppm: 2.51 (m, 8 H, piperaz.);
3.51 and 3.58 (2s, 4H, CH2N and CH2Ar); 3.80 (s, 3H,
CH3O–Ar); 6.83–7.35 (m, 9H, Ar).
(d,
1H,
Ar–CH=CH–CH2);
6.55
(td,
1H,
Ar–CH=CH–CH2); 7.32–7.40 (m, 5H, Ar).
5.1.1.45. 1-[3-(2-Furyl)acryloyl]-4-benzylpiperazine
5.1.1.53. 1-(4-Methoxybenzoyl)-4-benzylpiperazine
hydrochloride 53
hydrochloride 45
1H-NMR (DMSO-d6), δ ppm: 3.13–4.44 (m, 10H,
piperaz. and CH2–Ar); 6.73 (dd, 1H, H4≠); 7.00 (d, 1H,
H3≠); 7.03 (d, 1H, CH=CH–CO); 7.50 (d, 1H, CH–CO);
7.60 (m, 5H, Ar); 7.93 (d, 1H, H5≠); 11.30 (s broad, 1H,
NH+).
1H-NMR (DMSO-d6), δ ppm: 3.91 (s, 3H, OCH3);
3.95 (m, 10H, piperaz. and CH2–Ar); 7.40 (m, 9H, Ar);
11.32 (s broad, 1H, NH+).
5.1.1.54. 1-(3,4-Dimethoxybenzoyl)-4-benzylpiperazine
hydrochloride 54
5.1.1.46. 1-[3-(2-Furyl-2-propenyl)]-4-
benzylpiperazine 46
1H-NMR (DMSO-d6), δ ppm: 3.50 (m, 8H, piperaz.);
3.90 (s, 6H, 2OCH3); 4.43 (m, 2H, CH2–Ar), 7.43 (m,
8H, Ar); 11.54 (s broad, 1H, N+).
1H-NMR (CDCl3), δ ppm: 2.51 (m, 8H, piperaz.); 3.11
(d, 2H, CH=CH–CH2); 3.51 (s, 2H, N–CH2–Ar); 6.18 (dt,
1H, Ar–CH=CH–CH2); 6.25 (d, 1H, H2); 6.34 (dd, 1H,
H4≠); 6.38 (d, 1H, Ar–CH=CH–CH2); 7.28–7.32 (m, 6H,
Ar and H5≠).
5.1.1.55. 1-(3,4-Dimethoxybenzyl)-4-benzylpiperazine 55
1H-NMR (CDCl3), δ ppm: 2.49 (m, 8H, piperaz.);
3.50–3.55 (2s, 4H, CH2N and CH2Ar), 3.68–3.80 (2s, 6H,
2CH3O); 6.80–7.31 (m, 8H, Ar).
5.1.1.47. 1-[3-(2-Thienyl)acryloyl]-4-benzylpiperazine
hydrochloride 47
5.1.1.56. 1-(3,4-Methylenedioxybenzoyl)-4-
1H-NMR (DMSO-d6), δ ppm: 3.16–4.57 (m, 10H,
piperaz. and CH2–Ar); 7.04 (d, 1H, CH=CH–CO); 7.61
(d, 1H, CH–C=O); 7.56–7.72 (m, 8H, Ar); 11.14 (s broad
1H, NH+).
benzylpiperazine hydrochloride 56
1H-NMR (DMSO-d6), δ ppm: 3.25 (m, 8H, piperaz.);
4.31 (s, 2H, N–CH2–Ar); 6.08 (s, 2H, CH2O); 6.97 (m,
3H, Ar); 7.56 (m, 5H, Ar); 11.25 (s broad, 1H, NH+).

120
5.1.1.57. 1-(2-Pyridylcarbonyl)-4-benzylpiperazine
hydrochloride 57
5.2.4. Affınity to D2 binding sites in vitro
The affinity of test compounds for D2 binding sites was
estimated by their ability to displace [3H]Raclopride from
bovine striatum homogenates, as described by Köhler et
al. [8].
1H-NMR (DMSO-d6), δ ppm: 2.45 (m, 8H, piperaz.);
3.53 and 3.66 (2s, 4H, CH2N and CH2Ar); 7.67 (m, 9H,
Ar).
5.2.5. Antagonism of amphetamine-induced
hyperactivity in mice and rats
Swiss mice or Wistar rats were pretreated with
d-amphetamine (4 mg/kg IP) and the compounds to be
tested, and were placed 30 minutes later in an activity
meter for a 30 minutes test according to Costall et al. [9].
5.1.1.58. 1-(2-Pyridylmethyl)-4-benzylpiperazine 58
1H-NMR (CDCl3), δ ppm: 2.45 (m, 8H, piperaz.); 3.53
(s, 2H, CH2–N), 3.66 (s, 2H, N–CH2Ar); 7.67 (m, 9H,
Ar).
5.1.1.59. 1-(Adamantylcarbonyl)-4-benzylpiperazine
hydrochloride 59
5.2.6. Modulation by σ ligands of N-methyl-D-aspartate-
induced [3H]noradrenaline release in rat hippocampus
The experiment was carried out in hippocampal slices
from Sprague-Dawley (SID) rats. The [3H]NA release
was evoked once by a 4 min exposure to NMDA, 40 min
after the beginning of superfusion with an Mg2+-free
Krebs solution. Gi/o proteins were inactivated with per-
tussis toxin, injected locally from 3–11 days prior to the
experiment, to assess the possible involvment of Gi/o
proteins in the modulation of NMDA evoked [3H]NA
release.
1H-NMR (DMSO-d6), δ ppm: 1.79–2.08 (m, 15H,
Ad–CO); 3.37 (m, 8H, piperaz.); 4.43 (s, 2H, CH2–Ar);
7.69 (m, 5H, Ar); 11.06 (s broad, 1H, NH+).
5.1.1.60. 1-(2-Furylmethyl)-4-benzylpiperazine 60
1H-NMR (CDCl3), δ ppm: 2.42 (m, 8 H, piperaz.);
3.41 and 3.45 (2s, 4H, CH2N and CH2Ar); 6.10–6.22 (m,
3H, –CH–CH=CH–O); 7.28 (m, 5H, Ar).
5.1.1.61. 1-(6-Uracylmethyl)-4-benzylpiperazine 61
1H-NMR (CDCl3), δ ppm: 2.52 (m, 8H, piperaz.); 3.31
(s, 2H, CH2–N); 3.53 (1s, 2H, N–CH2–Ar); 5.54 (1s, 1H,
CO–CH=); 7.31 (m, 7H, 5H Ar and 2NH).
Compound 29 was tested at different concentrations,
ranging from 10–1 000 nmol, in continuous perfusion
according to Monnet et al. [10, 11].
5.2. Pharmacology
5.2.7. Modulation of the neuronal response to
N-methyl-D-aspartate electrophysiological studies
in the rat dorsal hippocampus
5.2.1. Affınity to σ binding sites in vitro
The affinity of test compounds for σ binding sites was
estimated by their ability to displace [3H](+)(PPP) 3-(3-
hydroxyphenyl)-N-(n-propyl) piperidine (3-PPP) from
guinea-pig cortex homogenates, as described by Karbon
et al. [4].
Electrophysiological experiments in Sprague-Dawley
rats. Microiontophoretic applications and extracellular
unitary recordings were performed with 5 barrelled glass
micropipettes as described by Haigler and Aghajan-
ian [12]. The central barrel, used for extracellular unitary
recordings of the activity of the CA1 or CA3 hippocampal
pyramidal neurones was filled with 2 M NaCl solution
saturated with fast green FCF.
Compounds were dissolved in NaCl: compound 29,
2 mM in 200 mM NaCl, pH 4; NMDA, 10 nM in
200 mM NaCl, pH 8; quisqualate, 1.5 mM in 400 mM
NaCl, pH 8. The neuronal activity was monitored as
described by Bergeron et al. [13]. Action potentials were
detected and square pulses were fed to a computer which
generated integrated firing rate histograms. Neurons from
the CA1 and CA3 region of the hippocampus were
identified according to the criteria of Kandal and Spen-
cer [14]. The duration of the microiontophoretic applica-
tions of NMDA and Quisqualate was kept constant at
50 s.
5.2.2. Specific σ1 and σ2 binding assays in vitro
The affinity of test compounds for σ1 binding sites was
estimated by their ability to displace [3H](+)-pentazocine
from Hartley guinea-pig brain homogenates minus cer-
ebellum as described by De Haven-Hudkins et al. [5].
The affinity of test compounds for σ2 binding sites was
estimated by their ability to displace [3H]1,3-di(o-
tolyl)guanidine (DTG) from rat liver membranes, as
described by Weber et al. [6].
5.2.3. Affınity to 5HT1A binding sites in vitro
The affinity of test compounds for 5HT1A binding sites
was estimated by their ability to displace [3H]-8-hydroxy-
3-(di-n-propylamino)tetraline (8-OH DPAT) from bovine
frontal cortex and hippocampus homogenates, as de-
scribed by Hoyer et al. [7].
The effect of compound 29, administered intrave-
nously (0.5–1 000 mg/kg) were assessed by determining

121
the ratio (N2/N1) of the number of spikes generated per
nC by each excitatory substance (Quis or NMDA) before
(N1) and after (N2) the injection. The effect of the
microiontophoretic application of compound 29 was also
assessed by determining the ratio (N2/N1) of the number
of spikes generated per nC by each of the excitatory
substances before (N1) and during (N2) the application.
The potential ‘antagonist’ effect was assessed by com-
paring the number of spikes generated per nC of each
excitatory substance following the administration of a σ
agonist and after the injection of the putative σ antago-
nist.
difference between the volume at 2 and 4 h and the initial
volume. Indomethacin at 10mg.kg–1 po is used as a
reference. Results are expressed as percentage of inhibi-
tion of the oedema.
References
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were compared using the paired Student’s t-test. Each
series of experiments was carried out in 8–12 rats.
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[6] Weber E., Sonders M., Quarum M., McLean S., Pou S., Keana
J.F.W., Proc. Natl. Acad. Sci. USA 83 (1986) 8784–8788.
Study of the anti-inflammatory activity was carried out
according to Winter’s method [15]. Male Wistar rats
weighing from 180–220 g were used in this study. A local
oedema was created with an injection into the sole of the
right paw of 0.1 mL of a 2% carrageenan suspension in
0.9% saline solution. The saline solution is also injected
into the sole of the left paw which acts as a control.
Compound 29 is orally administrated at 100 mg.kg–1 in
a 0.05% suspension of mixture and water used before the
oedemator induction.
Inflammation is characterized by an increase in the
volume of the paw, which is determined using a plethys-
mometer (UGO Basile). An initial measurement of the
volume of the paw is carried out just before oedemator
induction, other measurements are carried out 2 and 4 h
later. The oedemator volume (in mL) is obtained by the
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