New orally effective 3-(2-nitro)phenylpropanamide analgesic derivatives: Synthesis and antinociceptive evaluation

Article abstract of DOI:10.1016/j.ejmech.2013.08.041

A series of substituted 6-nitrophenylpropanamide derivatives (1-20) were synthesized using either the TDAE strategy or classical organic reactions. All these compounds were characterized by fusion point, ¹H NMR, ¹³C NMR, elemental an

Full text of DOI:10.1016/j.ejmech.2013.08.041

European Journal of Medicinal Chemistry 69 (2013) 728e734
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
New orally effective 3-(2-nitro)phenylpropanamide analgesic
derivatives: Synthesis and antinociceptive evaluation
,
b
,
,
Marc Since a , Thomas Freret c, Gerald Nee b c, Thierry Terme a, Patrice Vanelle a,
*
Michel Boulouard b
,
c
a Aix-Marseille Univ, UMR CNRS 7273, Institut de Chimie Radicalaire, Equipe Pharmaco-Chimie Radicalaire (LPCR), Faculté de Pharmacie, 27 Boulevard Jean
Moulin, CS 30064, 13385 Marseille Cedex 5, France
b Normandie Université, France
c UNICAEN, GMPc (Groupe Mémoire et Plasticité Comportementale, EA-4259, UFR des Sciences Pharmaceutiques), Campus 5 ‘Santé’, Jules Horowitz,
Boulevard Becquerel, F-14032 Caen Cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of substituted 6-nitrophenylpropanamide derivatives (1e20) were synthesized using either the
TDAE strategy or classical organic reactions. All these compounds were characterized by fusion point, 1
H
Received 23 April 2013
Received in revised form
19 August 2013
Accepted 25 August 2013
Available online 13 September 2013
NMR, 13C NMR, elemental analysis or mass spectrometry data. Because of their structural analogy with
recently published compounds possessing antinociceptive properties, our derivatives were screened for
peripheral analgesic activities on acetic acid-induced writhing in mice. Compound 13 showed the best
result at 100 mmol/kg ip (50% inhibition vs 59% for aspirin). This antinociceptive activity was maintained
after oral administration (40% inhibition vs 31.6% for aspirin). Both hot-plate and actimetry-based tests
were non-significant suggesting the analgesic activity of 13 linked to a peripheral mechanism.
Ó 2013 Elsevier Masson SAS. All rights reserved.
Keywords:
6-Nitrophenylpropanamide
TDAE
Analgesic
Peripheral antinociceptive activity
Writhing test
Hot-plate test
1. Introduction
Among the non-steroidal anti-inflammatory agents, arylalka-
noic acids are the most widely investigated compounds. A typical
Pain is an unpleasant and a subjective sensation resulting from a
harmful sensorial stimulation that alerts the body about current or
potential damage to its tissues and organs [1]. Prescribing analge-
sics is the first response of health professionals, before removal of
the underlying causes. The World Health Organization classifies
analgesic drugs into three categories, by analgesic strength [2]. The
first category includes paracetamol, aspirin and other non-steroidal
anti-inflammatory drugs (NSAIDs). The second and the third are
composed of opioid drugs such as codeine and morphine acting
against moderate and severe pain respectively.
molecule offer valuable features like a carboxyl group separated by
one or more carbon atoms from an aromatic nucleus. The lead
compound for aryl acetic acids is ibuprofen.
However, although these drugs are very effective and abun-
dantly prescribed, they have revealed some gastric or intestinal
adverse effects leading to numerous hospitalizations or death [3].
As a solution, many research groups transformed the carboxylic
acid moiety of commercially available NSAIDs into carboxamide or
ester forms in order to increase their cyclooxygenase-2 selectivity
and their oral absorption, and to hide the irritant carboxylic acid
group. Derivatizations studies of this kind were performed on
indometacine [4] and mefenamic acid [5,6], profens [7], and phe-
nylacetic acids [8].
In parallel, three research groups developed alternative ary-
lalkanoic scaffolds bearing a carboxamide moiety which showed
promising analgesic and anti-inflammatory activity combined with
a safe ulcerogenic profile (Fig. 1, formula A, B and C) [9e14]. Kwak
* Corresponding author. Present address: UNICAEN, CERMN (Centre d’Etudes et
de Recherche sur le Médicament de Normandie, FR CNRS INC3M e SF ICORE,
Université de Caen Basse-Normandie, UFR des Sciences Pharmaceutiques Bd Bec-
querel), F-14032 Caen, France. Tel.: þ33 231566819.
E-mail addresses: marc.since@unicaen.fr, marcsince@yahoo.fr (M. Since).
0223-5234/$ e see front matter Ó 2013 Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2013.08.041

M. Since et al. / European Journal of Medicinal Chemistry 69 (2013) 728e734
729
B
X
Y
O
O
H
N
N
O
X= H, NO2
Y= O, CH2
A
Cl
NO2
C
NR2R3
R1
O
NR2R3
R1
NR2R3
MeO
MeO
O
R1 = 4,5-(OMe)2
4,5-OCH2O
O
NR2R3
O
D
O
NH2
O
N
N
R1
O
Fig. 1. Design of 3-(2-nitrophenyl)propanamides.
et al. developed carbamic acid derivatives bearing similar scaffolds
and phenylpiperazinyl moiety (Fig. 1 formula D). These derivatives
not only showed peripheral antinociceptive property but also anti-
anxiety and antidepressant activities on mice [15].
Combining these promising structures enabled us to reveal the
N-substituted 3-(2-nitrophenyl)propanamide skeleton as a new
potentially analgesic scaffold (Fig. 1).
Recently, we developed a new synthesis methodology using
tetrakis(dimethylamino)ethylene (TDAE) to prepare N,N-disubsti-
tuted 3-(6-nitrobenzo[d][1,3]dioxol-5-yl)propanamide and 3-(4,5-
dimethoxy-2-nitrophenyl)propanamide derivatives [16]. This and
previous studies [17,18] demonstrated the nitro group requirement
in ortho- or in para- position from chloride to performed the
carbon-halide reduction via the TDAE strategy. Consequently, we
focus our interest on the synthesis of nitrated compounds. In
continuation of our work directed towards the development of
original synthetic methods in medicinal chemistry [19e25] and the
preparation of new potentially analgesic active compounds [26,27],
we report herein the synthesis of new 3-(2-nitrophenyl)prop-
anamide derivatives and their analgesic properties.
synthesis alternatives such as un-nitrated derivatives or 2-
substituted amides, via a simple, quick and cost-effective strategy.
The 3-(benzo[d][1,3]dioxol-5-yl)propanoic acid was first reacted
with nitric acid in dichloromethane, leading to nitrated derivatives
in quantitative yield. These, or the starting propanoic acid, were
reacted with thionyl chloride to obtain acyl chlorinated in-
termediates. After evaporation of the solvent, the crude was reacted
with the corresponding amine reagent, leading to the expected
products 7e17 in moderate to good yields (34e95%) (Table 1).
To complete the pharmacomodulation of compound 13, reduc-
tion of its nitro group appeared an attractive option and was per-
formed using molecular hydrogen in dioxane leading to compound
20 in 36% yield.
2.2. Analgesic activity
2.2.1. Antinociceptive screening
Antinociceptive activity of synthesized compounds was first
assessed through the acetic acid-induced writhing test. A screening
protocol was used to select structures possessing analgesic activity
after 3 mg/kg intra-peritoneal (ip) administration in mice (Table 2).
No toxic effect was observed during the protocol.
2. Resultsediscussion
In 6-nitrobenzo[d][1,3]dioxol-5-yl series (1e4, 8e20), non-
significant results were observed with the non-substituted car-
boxamide derivative 8 or with compounds bearing an aromatic ring
(9, 10). However, substitution by aliphatic groups such as n-hexyl
(11), piperidinyl (1), morpholinyl (2), piperazinyl (12, 13) led to
better results. Focusing on compound 13, analogous derivatives
with periodic structural changes were synthezised and screened (3,
14e17, 20). These compounds did not show improved anti-
nociceptive activity. We can observe that derivatives 17 and 20, the
2.1. Chemistry
Preparation of the 3-(2-nitrophenyl)propanamides and esters
(1e20) was realized via two different pathways (Scheme 1).
First, we used the SN2 initiated by TDAE. This methodology led
us to previously synthesize compounds 1e6 [16].
The second pathway used phenylpropanoic acids as starting
materials using classical organic reactions. This yielded more

730
M. Since et al. / European Journal of Medicinal Chemistry 69 (2013) 728e734
NO2
O
X
R1
42-92 %
1-6
a
NO2
Cl
+
R1
Br
X
Y
X= OEt, NR2R3
R1 = 4,5-OCH2O-
4,5-(OCH3)2
O
R1
R1
OH
R3
N
O
c, d
R2
b
O
Y = H, NO2
34-95 %
NO2
7-19
R1
OH
O
NO2
OMe
O
NH2
OMe
O
O
O
N
e
N
N
N
O
O
13
20 36 %
Scheme 1. Reagents and conditions: a) TDAE (1 equiv.), DMF, ꢀ20 ꢁC 1 h then 50 ꢁC 1 h; b) HNO3, CH2Cl2, 1.5 h; c) SOCl2, N2, CH2Cl2, 1 h; d) Amine derivatives, TEA, CH2Cl2; e) H2/Ni
Raney, dioxane, 40 ꢁC.
Table 1
Formula and yield of compounds 1e20.
X
R1
Table 2
Acetic acid-induced writhing assay after ip administration at 3 mg/kg of compound
1e20.
Y
Compound
Dose (mg/kg)
Writhing ꢂ SEM
% Inhibitiona
O
Control
Aspirin
1
2
3
4
5
6
7
e
15
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
21.0 ꢂ 5.2
7.9 ꢂ 0.63
15.7 ꢂ 1.2
14.4 ꢂ 1.7
16.4 ꢂ 1.5
12.5 ꢂ 1.6
14.0 ꢂ 1.7
18.2 ꢂ 0.6
22.0 ꢂ 4.0
18.1 ꢂ 1.2
18.3 ꢂ 2.1
18.9 ꢂ 1.6
12.9 ꢂ 1.2
14.1 ꢂ 2.3
13.2 ꢂ 2.5
18.0 ꢂ 1.3
20.2 ꢂ 1.3
16.7 ꢂ 1.8
20.5 ꢂ 2.6
9.9 ꢂ 2.5
Compound R1
X
Y
Yield (%)a
62.3***
25.2**
31.4***
22.0*
40.5***
33***
15.3
<0
14.8
12.9
10
38.6***
32.9***
37.2***
14.3
4.8
21.5*
2.4
53.0***
20.1*
21.5*
1b
2b
3b
4b
5b
6b
7c
4,5-OCH2Oe NO2 Piperidin-1-yl
4,5-OCH2Oe NO2 Morpholin-1-yl
4,5-OCH2Oe NO2 4-(3,4-Di-Cl-Ph)-piperazin-1-yl 62
4,5-OCH2Oe NO2 OEt
4,5-(OCH3)2e NO2 Piperidin-1-yl
4,5-(OCH3)2e NO2 Morpholin-1-yl
42
68
85
65
62
82
81
81
76
95
4,5-(OCH3)2e
H
Piperidin-1-yl
8
4,5-OCH2Oe NO2 NH2
8
9
9
4,5-OCH2Oe NO2 NH-Ph
10
11
12
13
14
15
16
17
18c
19
20
4,5-OCH2Oe NO2 NH-Pyridin-2-yl
4,5-OCH2Oe NO2 NH-n-hexyl
4,5-OCH2Oe NO2 (2-Hydroxyethyl)piperazin-1-yl 73
4,5-OCH2Oe NO2 4-(4-MeOPh)piperazin-1-yl
4,5-OCH2Oe NO2 4-(4-F-Ph)piperazin-1-yl
4,5-OCH2Oe NO2 4-(2-MeOPh)piperazin-1-yl
4,5-OCH2Oe NO2 4-Ph-piperazin-1-yl
4,5-OCH2Oe
4,5-OCH2Oe
4,5-OCH2Oe
10
11
12
13
14
15
16
17
18
19
20
72
34
75
68
62
74
70
36
H
H
H
4-(4-MeOPh)piperazin-1-yl
Piperidin-1-yl
2-Me-piperidin-1-yl
15.1 ꢂ 2.2
16.5 ꢂ 2.0
4,5-OCH2Oe NH2 4-(4-MeOPh)piperazin-1-yl
a
a
% All yields refer to the chromatographically isolated pure products.
Synthesis and analytical description previously performed by our team [16].
Compounds previously described [28,29].
Statistical significance between control and treated groups (ANOVA þ PLSD of
Fischer: *p < 0.05; **p < 0.01; ***p < 0.001). n ¼ 50 mice for control and aspirin
groups, n ¼ 10 for other treatment groups.
b
c

M. Since et al. / European Journal of Medicinal Chemistry 69 (2013) 728e734
731
Table 3
Acetic acid-induced writhing assay after ip administration at 100
pounds 1, 5, 11, 13.
m
mol/kg of com-
% Inhibitiona
Molecule
Dose (mg/kg)
Writhings ꢂ SEM
Control
Aspirin
1
5
11
13
e
21.2 ꢂ 1.0
8.7 ꢂ 1.1
100
100
100
100
100
m
m
m
m
m
mol/kg
mol/kg
mol/kg
mol/kg
mol/kg
59.0***
44.8***
39.1***
26.0**
11.7 ꢂ 1.1
12.9 ꢂ 1.4
15.7 ꢂ 1.2
10.6 ꢂ 1.3
50.0***
a
Statistical significance between control and treated groups (ANOVA þ PLSD of
Fischer: *p < 0.05; **p < 0.01; ***p < 0.001). n ¼ 50 mice for control and aspirin
groups, n ¼ 10 for other treatment groups.
un-nitrated and the aniline analog compound of 13, were not or less
active than 13.
In 4,5-dimethoxyphenyl series, only compound 18 showed
effective biological action.
These promising results led us to investigate compounds 1, 5, 11
and 13 more closely, all at the same higher dose (100 mmol/kg; at
least 10 times higher than the screening dose) to compare their
analgesic activity and determine to what extent dose explained the
observed the antinociceptive effect (Table 3).
Surprisingly, derivative 11 did not show a significant activity at a
higher dose than during screening, while the analgesic activity of
compounds 1, 5 and 13 was slightly better. Compound 13, which
showed the best analgesic activity (in term of percentage of
Fig. 3. The analgesic activity results of the hot plate experiment for compound 13 at
100
mmol/kg, physiological serum and morphine at 5 mg/kg. *p < 0.05 vs vehicle
control group data expressed as mean ꢂ SEM, one-way ANOVA followed by a Fisher
PLSD test.
Interestingly, while a decrease was observed in the percentage of
inhibition after oral administration of aspirin compared to the same
100
mmol/kg dose administrated intraperitonally (59% after ip
administration versus 31.2% after oral administration) the decrease
is not as great under the same conditions for compound 13 (50%
versus 40.3%) suggesting that compound 13 offers slightly better
oral biodisponibility.
writhing inhibition) at 100 mmol/kg, was then further investigated.
In addition, to assess the pharmacological mechanism (periph-
eral and/or central) involved in the analgesic effect of compound 13,
a hot plate test using a 100 mmol/kg intraperitoneal injection was
2.2.2. Investigation of compound 13
First, in order to distinguish any locomotor effect in the inhibi-
tion of writhing by derivatives 13, an actimetry-based test was
performed. Compound 13 did not produce any significant increase
in hot-plate latency compared to control group (Fig. 3). This result
suggested that the compound 13 antinociceptive activity may be
related to a peripheral mechanism.
performed. No effect was observed at 33 and 100 mmol/kg (data not
shown). Inhibition of writhing was then not related to any loco-
motor inhibition but rather to an analgesic effect. Second, com-
pound 13 was tested for inhibition of acetic acid-induced writhing
test at gradual increased oral dosages (10, 33.3, 100
mmol/kg)
(Fig. 2). Positive control was aspirin at the highest dose (100
kg).
mmol/
3. Conclusion
Compound 13 showed a significant antinociceptive activity at
the three doses, respectively with 28.6, 35.7, 40.3% inhibition of
constrictions. This result does not reveal a clear dose-dependent
effect, since almost maximum analgesic action was obtained from
the lowest dose tested. However, results obtained at 100 mmol/kg
were slightly better than for aspirin at the same dose (31.2%).
20 new 3-(2-nitrophenyl)propanamide derivatives were syn-
thesized using either classical methodology or an original TDAE
strategy. When screened, 8 of them bearing aliphatic substituent on
the carboxamide group showed a significant peripheral analgesic
activity at a very low dose (3 mg/kg). One of the 8, compound 13
was more thoroughly investigated. Its analgesic activity was
demonstrated and was clearly maintained through oral adminis-
tration contrary to aspirin. Although the mechanism was not
elucidated, it appeared to be mediated in a peripheral way. The
structural analogy with other new derivatives showing anti-
inflammatory activity makes the hypothesis of
a peripheral
mechanism plausible. 3-(2-nitrophenyl)propanamide compounds
require further investigation to confirm them as new potent anal-
gesic therapeutics agent and demonstrated their anti-inflammatory
activity.
4. Experimental section
4.1. Chemistry
Melting points were determined on a Büchi capillary melting
point apparatus and are uncorrected. Element analyses were per-
formed by the centre de Microanalyse of the Aix-Marseille Uni-
versity. Both 1H and 13C NMR spectra were determined on a Bruker
AC 200 spectrometer. The 1H the 13C chemical shifts are reported
from CDCl3 peaks: 1H (7.26 ppm) and 13C (76.9 ppm). Absorptions
Fig. 2. Acetic acid-induced writhing assay after oral administration: analgesic activity
of compound 13. n ¼ 8 mice per treatment groups. *p < 0.05, **p < 0.01 versus control
group (ANOVA and PLSD of Fischer).

732
M. Since et al. / European Journal of Medicinal Chemistry 69 (2013) 728e734
are reported with the following notations: s, singlet; d, doublet; t,
triplet; q, quartet; m, a more complex multiplet or overlapping
multiplets. The following adsorbents were used for column chro-
matography: silica gel 60 (Merck, particle size 0.063e0.200 mm,
70e230 mesh ASTM). TLC was performed on 5 cm ꢃ 10 cm
aluminum plates coated with silica gel 60 F254 (Merck) in an
appropriate solvent.
29.3 (CH2); 29.9 (CH2); 31.3 (CH2); 36.9 (CH2); 39.4 (CH2); 102.7
(CH2); 105.4 (CH); 110.9 (CH); 133.5 (C); 142.3 (C); 146.4 (C); 151.7
(C); 171.3 (CO). Anal. Calcd for C16H22N2O5: C, 59.61; H, 6.88; N,
8.69. Found: C, 59.64; H, 7.13; N, 8.59.
4.1.2.5. 1-(4-(2-Hydroxyethyl)piperazin-1-yl)-3-(6-nitrobenzo[d]
[1,3]dioxol-5-yl)propan-1-one (12). Yellow solid, mp 103 ꢁC. 1H
NMR (200 MHz, CDCl3)
d
2.45 (m, 5H, OH, 2ꢃ CH2); 2.53 (t,
4.1.1. Procedure for nitration 3-(benzo[d][1,3]dioxol-5-yl)propanoic
acid and 3-(3,4-dimethoxyphenyl)propanoic acid
J ¼ 5.3 Hz, 2H, CH2); 2.67 (t, J ¼ 7.2 Hz, 2H, CH2); 3.15 (t, J ¼ 7.2 Hz,
2H, CH2); 3.46 (t, J ¼ 5.3 Hz, 2H, CH2); 3.62 (t, J ¼ 5.2 Hz, 4H, 2ꢃ
CH2); 6.06 (s, 2H, CH2); 6.84 (s, 1H, CH); 7.47 (s, 1H, CH). 13C NMR
3-(Benzo[d] [1,3]dioxol-5-yl)propanoic acid and 3-(3,4-
dimethoxyphenyl)propanoic acid was nitrated in 6 position of the
phenyl moiety according to the procedure described by Bezerra-
Netto [13].
(50 MHz, CDCl3)
d 29.9 (CH2); 33.9 (CH2); 41.6 (CH2); 45.4 (CH2);
52.5 (CH2); 53.0 (CH2); 57.8 (CH2); 59.3 (CH2); 102.8 (CH2); 105.6
(CH); 111.2 (CH); 133.7 (C); 142.7 (C); 146.6 (C); 151.8 (C); 170.1
(CO). Anal. Calcd for C16H21N3O6: C, 54.69; H, 6.02; N, 11.96. Found:
C, 54.77; H, 6.31; N, 11.58.
4.1.2. Procedure for carboxamide synthesis
A solution of 1 mmol of the corresponding propanoic acid mixed
with one drop of pyridine in 10 mL of dichloromethane (DCM),
cooled at 0 ꢁC, was added dropwise to 1.2 mmol of thionyl chloride.
After stirring for 1 h at rt, the crude was evaporated at reduced
pressure. The crude was dissolved in DCM at 0 ꢁC and mixed with
1.2 mmol of the corresponding amine reagent and with 0.8 mmol of
triethylamine. After stirring for 3 h, the crude was diluted with
40 mL of DCM and washed with water (3 ꢃ 100 mL). The organic
phase was separated, dried with Na2SO4 and concentrated at
reduced pressure. Purification was performed by silica gel
chromatography.
4.1.2.6. 1-(4-(4-Methoxyphenyl)piperazin-1-yl)-3-(6-nitrobenzo[d]
[1,3]dioxol-5-yl)propan-1-one (13). Yellow solid, mp 143 ꢁC. 1H
NMR (200 MHz, CDCl3)
d
2.75 (t, J ¼ 7.3 Hz, 2H CH2); 2.96e3.05 (m,
4H, 2ꢃ CH2); 3.21 (t, J ¼ 7.3 Hz, 2H CH2); 3.63 (m, 2H, CH2); 3.77 (s,
3H, CH3); 3.78 (m, 2H, CH2); 6.08 (s, 2H, CH2); 6.82e6.94 (m, 5H, 5ꢃ
CH); 7.50 (s, 1H, CH). 13C NMR (50 MHz, CDCl3)
d 30.0 (CH2); 34.0
(CH2); 41.7 (CH2); 45.5 (CH2); 51.1 (CH2); 51.4 (CH2); 55.6 (CH3);
102.9 (CH2); 105.7 (CH); 111.4 (CH); 114.6 (2ꢃ CH); 119.0 (2ꢃ CH);
133.8 (C); 142.8 (C); 144.8 (C); 146.7 (C); 151.9 (C); 154.5 (C); 170.1
(CO). Anal. Calcd for C21H23N3O6: C, 61.01; H, 5.61; N, 10.16. Found:
C, 61.00; H, 5.77; N, 10.10.
4.1.2.1. 3-(6-Nitrobenzo[d][1,3]dioxol-5-yl)propanamide
(8).
2.36 (t,
Yellow solid, mp 182 ꢁC. 1H NMR (200 MHz, DMSO-d6)
d
4.1.2.7. 1-(4-(4-Fluorophenyl)piperazin-1-yl)-3-(6-nitrobenzo[d][1,3]
J ¼ 7.8 Hz, 2H, CH2); 2.96 (t, J ¼ 7.8 Hz, 2H, CH2); 6.17 (s, 2H, CH2);
dioxol-5-yl)propan-1-one (14). Yellow solid, mp 159 ꢁC. 1H NMR
6.77 (s, 1H, NH); 7.00 (s, 1H, CH); 7.27 (s, 1H, NH); 7.54 (s, 1H, CH).
(200 MHz, CDCl3)
d
2.74 (t, J ¼ 7.2 Hz, 2H CH2); 2.99e3.08 (m, 4H, 2ꢃ
13C NMR (50 MHz, DMSO-d6)
d
28.4 (CH2); 35.6 (CH2); 103.2 (CH2);
CH2); 3.20 (t, J ¼ 7.2 Hz, 2H CH2); 3.63 (t, J ¼ 4.6 Hz, 2H CH2); 3.70 (t,
105.1 (CH); 110.5 (CH); 133.3 (C); 142.6 (C); 146.3 (C); 151.5 (C);
173.0 (C). Anal. Calcd for C10H10N2O5: C, 50.42; H, 4.23; N, 11.76.
Found: C, 50.88; H, 4.07; N, 11.32.
J ¼ 4.6 Hz, 2H CH2); 6.06 (s, 2H, CH2); 6.87e7.02 (m, 5H, 5ꢃ CH); 7.50
(s, 1H, CH). 13C NMR (50 MHz, CDCl3)
d 30.0 (CH2); 33.9 (CH2); 41.4
(CH2); 45.3 (CH2); 50.7 (CH2); 51.0 (CH2); 102.8 (CH2); 105.6 (CH);
111.3 (CH); 115.8 (d, J ¼ 22.3 Hz, 2ꢃ CH); 118.8 (d, J ¼ 8.0 Hz, 2ꢃ CH);
133.6 (C); 142.7 (C); 147.0 (C); 151.9 (C); 155.6 (C); 157.4 (d,
J ¼ 202.7 Hz, C); 170.1 (CO). Anal. Calcd for C20H20FN3O6: C, 59.85; H,
5.02; N, 10.47. Found: C, 59.77; H, 5.16; N, 10.47.
4.1.2.2. 3-(6-Nitrobenzo[d][1,3]dioxol-5-yl)-N-phenylpropanamide
(9). Yellow solid, mp 148 ꢁC. 1H NMR (200 MHz, CDCl3)
d 2.71 (t,
J ¼ 7.5 Hz, 2H, CH2); 3.26 (t, J ¼ 7.5 Hz, 2H, CH2); 6.07 (s, 2H, CH2);
6.85 (s, 2H, CH2); 7.09 (t, J ¼ 7.3 Hz, 1H, CH); 7.26e7.33 (m, 2H, 2ꢃ
CH); 7.47e7.50 (m, 3H, 3ꢃ CH). Amidic proton did not appear in
4.1.2.8. 1-(4-(2-Methoxyphenyl)piperazin-1-yl)-3-(6-nitrobenzo[d]
theses experimental conditions. 13C NMR (50 MHz, CDCl3)
d
30.0
[1,3]dioxol-5-yl)propan-1-one (15). Yellow solid, mp 143 ꢁC. 1H
(CH2); 38.2 (CH2); 102.9 (CH2); 105.7 (CH); 111.2 (CH); 119.9 (2ꢃ
CH); 124.3(CH); 128.9 (2ꢃ CH); 133.4 (C); 137.7 (C); 142.6 (C); 146.8
(C); 152.0 (C); 169.9 (CO). Anal. Calcd for C16H14N2O5: C, 61.14; H,
4.49; N, 8.91. Found: C, 61.39; H, 4.48; N, 8.77.
NMR (200 MHz, CDCl3)
d
2.74 (t, J ¼ 7.3 Hz, 2H CH2); 2.94e3.02 (m,
4H, 2ꢃ CH2); 3.20 (t, J ¼ 7.3 Hz, 2H CH2); 3.63 (t, J ¼ 4.7 Hz, 2H, CH2);
3.79 (t, J ¼ 4.7 Hz, 2H, CH2); 3.86 (m, 3H, CH3); 6.05 (s, 2H, CH2);
6.84e6.90 (m, 4H, 4ꢃ CH); 6.98e7.02 (m, 1H, CH); 7.48 (s, 1H, CH).
13C NMR (50 MHz, CDCl3)
d 29.9 (CH2); 33.8 (CH2); 41.8 (CH2); 45.7
4.1.2.3. 3-(6-Nitrobenzo[d][1,3]dioxol-5-yl)-N-(pyridine-2-yl)prop-
(CH2); 50.5 (CH2); 50.9 (CH2); 55.3 (CH3); 102.8 (CH2); 105.5 (CH);
111.3 (2ꢃ CH); 118.3 (CH); 120.9 (CH); 123.5 (CH); 133.7 (C); 140.4
(C); 142.7 (C); 146.6 (C); 151.7 (C); 152.2 (C); 170.1 (CO). Anal. Calcd
for C21H23N3O6: C, 61.01; H, 5.61; N, 10.16. Found: C, 61.16; H, 5.60;
N, 10.24.
1
anamide (10). Yellow solid, mp 177 ꢁC. H NMR (200 MHz, CDCl3)
d
2.79 (t, J ¼ 7.3 Hz, 2H, CH2); 3.26 (t, J ¼ 7.3 Hz, 2H, CH2); 6.07 (s, 2H,
CH2); 6.84 (s, 1H, CH); 7.04e7.07 (m, 1H, CH); 7.50 (s, 1H, CH); 7.67e
7.76 (m, 1H, CH); 8.19e8.24 (m, 2H, CH); 8.75 (s, 1H, NH). 13C NMR
(50 MHz, CDCl3)
d 29.4 (CH2); 38.0 (CH2); 102.9 (CH2); 105.8 (CH);
111.0 (CH); 114.3 (CH); 119.8 (CH); 133.0 (C); 138.8 (CH); 142.8 (C);
146.8 (C); 147.1 (C); 151.8 (C); 152.2 (C); 170.4 (CO). Anal. Calcd for
4.1.2.9. 3-(6-Nitrobenzo[d][1,3]dioxol-5-yl)-1-(4-phenylpiperazin-1-
yl)propan-1-one (16). Yellow solid, mp 186 ꢁC. 1H NMR (200 MHz,
C
15H13N3O5: C, 57.14; H, 4.16; N, 13.33. Found: C, 56.52; H, 4.15; N,
CDCl3)
d
2.75 (t, J ¼ 7.2 Hz, 2H CH2); 3.07e3.14 (m, 4H, 2ꢃ CH2); 3.19
12.77.
(t, J ¼ 7.2 Hz, 2H CH2); 3.62 (m, 2H, CH2); 3.78 (m, 2H, CH2); 6.05 (s,
2H, CH2); 6.87e6.93 (m, 3H, 3ꢃ CH); 7.24e7.32 (m, 3H, 3ꢃ CH); 7.51
4.1.2.4. N-Hexyl-3-(6-nitrobenzo[d][1,3]dioxol-5-yl)propanamide
(s, 1H, CH). 13C NMR (50 MHz, CDCl3)
d 30.0 (CH2); 34.0 (CH2); 41.7
(11). Yellow solid, mp 105 ꢁC. 1H NMR (200 MHz, CDCl3)
d
0.80 (t,
(CH2); 45.5 (CH2); 49.4 (CH2); 49.6 (CH2); 102.8 (CH2); 105.7 (CH);
111.4 (CH); 116.6 (2ꢃ CH); 120.5 (CH); 129.2 (2ꢃ CH); 133.7 (C);
142.8 (C); 146.7 (C); 150.9 (C); 151.9 (C); 170.2 (CO). Anal. Calcd for
J ¼ 6.7 Hz, 3H, CH3); 1.19 (m, 6H, 3ꢃ CH2); 1.38 (m, 2H, CH2); 2.46 (t,
J ¼ 7.3 Hz, 2H, CH2); 3.10 (t, J ¼ 7.3 Hz, 2H, CH2); 3.11e3.18 (m, 2H,
CH2); 6.02 (s, 2H, CH2); 6.03 (s, 1H, NH); 6.76 (s, 1H, CH); 7.40 (s, 1H,
C20H21N3O5: C, 62.62; H, 5.52; N, 10.96. Found: C, 62.72; H, 5.61; N,
CH). 13C NMR (50 MHz, CDCl3)
d 13.8 (CH3); 22.3 (CH2); 26.3 (CH2);
10.76.

M. Since et al. / European Journal of Medicinal Chemistry 69 (2013) 728e734
733
4.1.2.10. 3-(Benzo[d][1,3]dioxol-5-yl)-1-(4-(4-methoxyphenyl)piper-
times, PLSD of Fisher). Analgesic activity was quantified for each
mouse by calculating the percentage of the maximum possible ef-
fect (MPE%, where MPE% ¼ [(test latency ꢀ control latency)/(cut-off
point ꢀ control latency) ꢃ 100]).
azin-1-yl)propan-1-one (17). Yellow solid, mp 143 ꢁC. 1H NMR
(200 MHz, CDCl3)
d
2.59 (t, J ¼ 7.1 Hz, 2H CH2); 2.86e2.99 (m, 6H,
3ꢃ CH2); 3.50(t, J ¼ 4.9 Hz, 2H CH2); 3.73e3.74 (m, 5H, CH3, CH2);
5.85 (s, 2H, CH2); 6.83e6.73 (m, 3H, 3ꢃ CH); 6.78e6.88 (s, 4H, 4ꢃ
CH). 13C NMR (50 MHz, CDCl3)
d
31.0 (CH2); 34.9 (CH2); 41.4 (CH2);
4.2.3. Locomotor activity
45.4 (CH2); 50.6 (CH2); 50.8 (CH2); 55.3 (CH3); 100.6 (CH2); 108.1
(CH); 108.8 (CH); 114.2 (2ꢃ CH); 118.6 (2ꢃ CH); 121.0 (CH); 134.7
(C); 145.5 (C); 145.7 (C); 147.4 (C); 154.1 (C); 171.3 (CO). Anal. Calcd
for C21H24N2O4: C, 68.46; H, 6.47; N, 7.60. Found: C, 68.21; H, 6.54;
N, 7.34.
Motor activity was measured in Plexiglas cages (1911 14 cm)
placed in frames mounted with computer-monitored photocell
beams (IMETRONIC). Horizontal locomotion was measured by the
number of cage crossings. Behavioral data were collected by an
Imetronic interface connected to a PC. Mice were injected intraper-
itoneally with drug or saline and immediately placed back into the
chamber for 1 h. The device (PC) allows a posteriori analysis of po-
tential modifications in of locomotion occurring during a period
25 mine35 min post-treatment (i.e. the same period post-treatment
as that used to the number of constrictions in the writhing test).
Methylphenidate (10 mg/kg) and haloperidol (0.5 mg/kg) used as
stimulating and depressive references, respectively, produce an in-
crease (280% increase, p < 0.001, PLSD of Fischer) and a decrease
(80%, p < 0.001, PLSD of Fischer) in horizontal locomotion.
4.1.2.11. 3-(Benzo[d][1,3]dioxol-5-yl)-1-(2-methylpiperidin-1-yl)
propan-1-one (19). Yellow oil. Mixture of 2 rotamers. 1H NMR
(200 MHz, CDCl3) d 1.15 (m, 6H, CH3); 1.53e1.62 (m, 12H, CH2); 2.53
(t, J ¼ 7.7 Hz, 2H, CH2); 2.64 (m, 1H, CH2); 2.88 (t, J ¼ 7.7 Hz, 2H,
CH2); 3.03 (m, 1H, CH2); 3.03 (m, 1H, CH2); 3.57 (d, J ¼ 12.9 Hz, 1H,
CH2); 4.09 (m, 1H, CH2); 4.52 (d, J ¼ 12.9 Hz, 1H, CH2); 4.93 (m, 1H,
CH2); 5.91 (s, 4H, CH2); 6.64e6.75 (m, 6H, CH). 13C NMR (50 MHz,
CDCl3)
d
15.4 (CH3); 16.5 (CH3); 18.6 (2ꢃ CH2); 25.4 (CH2); 26.1
(CH2); 29.7 (CH2); 30.6 (CH2); 31.3 (2ꢃ CH2); 35.3 (CH2); 35.7 (CH2);
36.2 (CH2); 40.6 (CH2); 43.6 (CH); 48.1 (CH); 100.7 (CH2); 108.1
(CH); 108.8 (CH); 121.1 (CH); 135.2 (C); 145.7 (C); 147.5 (C); 170.4
(CO). HRMS (EI): calcd for C16H21NO3: [M þ H]þ: 276.1594, found:
276.1593.
4.2.4. Statistical analyses
All quantitative data were expressed as mean ꢂ SEM and were
analyzed using analysis of variance (ANOVA) followed, when sig-
nificant effects were found by post-hoc multiple comparison tests
(PLSD of Fisher). p-values less than 0.05 were considered to be
significant. Statistical analysis was performed with STATVIEWÒ
software.
4.1.2.12. 3-(6-Aminobenzo[d][1,3]dioxol-5-yl)-1-(4-(4-
methoxyphenyl)piperazin-1-yl)propan-1-one (20). Brown solid, mp
102 ꢁC. 1H NMR (200 MHz, CDCl3)
d
2.63 (t, J ¼ 7.1 Hz, 2H CH2);
2.78e2.89 (m, 4H, 2ꢃ CH2); 2.96 (t, J ¼ 4.9 Hz, 2H CH2); 3.52 (t,
J ¼ 4.9 Hz, 2H CH2); 3.72e3.75 (m, 7H, NH2, CH2, CH3); 5.78 (s, 2H,
CH2); 6.26 (s, 1H, CH); 6.54 (s, 1H, CH); 6.84 (m, 4H, 4ꢃ CH). 13C
Acknowledgments
This work was supported by the CNRS and Aix-Marseille Uni-
versity. The authors thank V. Remusat for 1H and 13C spectra
recording.
NMR (50 MHz, CDCl3)
d 26.5 (CH2); 32.8 (CH2); 41.7 (CH2); 45.6
(CH2); 50.9 (2ꢃ CH2); 55.4 (CH3); 98.2 (CH2); 100.4 (CH); 109.5
(CH); 114.4 (2ꢃ CH); 117.6 (C); 118.8 (2xCH); 139.0 (C); 140.3 (C);
145.1 (C); 146.5 (C); 154.3 (C); 171.1 (CO). HRMS (EI): calcd for
Appendix A. Supplementary data
C
21H25N3O4: [M þ H]þ: 384.1918, found: 384.1923.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2013.08.041.
4.2. In vivo biology
4.2.1. Writhing test
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