Design of new potent and selective secretory phospholipase A2 inhibitors. Part 5: Synthesis and biological activity of 1-alkyl-4-[4,5-dihydro-1,2,4-[4H]-oxadiazol-5-one-3-ylmethylbenz-4′-yl(oyl)] piperazines

Article abstract of DOI:10.1016/j.bmc.2007.10.077

Among the different PLA₂s identified to date, the group IIA secretory PLA₂ (sPLA₂ GIIA) is implied in diverse pathological conditions. In this work we describe the synthesis, inhibitory activities, and structure-activity relationships (SAR) of a new class of substituted piperazine derivatives. The in vitro fluorimetric assay using two groups of enzymes, GIB and GIIA, revealed several compounds as highly potent inhibitors (IC₅₀ = 0.1 μM). The in vivo activity assessed by ip or per os administration in a carrageenan-induced edema test in rats showed that two compounds proved to be as potent as indomethacin (10 mg/kg).

Full text of DOI:10.1016/j.bmc.2007.10.077

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry 16 (2008) 1242–1253
Design of new potent and selective secretory phospholipase
A2 inhibitors. Part 5: Synthesis and biological activity
of 1-alkyl-4-[4,5-dihydro-1,2,4-[4H]-oxadiazol-
5-one-3-ylmethylbenz-40-yl(oyl)] piperazines
a
a
a
a
´
´
Latifa Boukli, Mohamed Touaibia, Nadia Meddad-Belhabich, Atime Djimde,
Chang-Ha Park,b Jung-Joo Kim,b Joo-Hyoung Yoon,b
Aazdine Lamouria and Franc¸oise Heymansa,*
a
`
Laboratoire de Pharmacochimie Mole´culaire, Unite´ de Pharmacochimie Mole´culaire et Systemes Membranaires E.A. 2381,
Universite´ Paris 7-Denis Diderot, Case 7066, 2 Place Jussieu, 75251 Paris Cedex 05, France
bYang Ji Chemical Co., Ltd, 638-6 Sungkok-Dong Danwon-Gu, Ansan, Kyunggi-Do, Republic of Korea
Received 3 April 2007; revised 11 October 2007; accepted 23 October 2007
Available online 13 November 2007
Abstract—Among the different PLA2s identified to date, the group IIA secretory PLA2 (sPLA2 GIIA) is implied in diverse patho-
logical conditions. In this work we describe the synthesis, inhibitory activities, and structure–activity relationships (SAR) of a new
class of substituted piperazine derivatives. The in vitro fluorimetric assay using two groups of enzymes, GIB and GIIA, revealed
several compounds as highly potent inhibitors (IC50 = 0.1 lM). The in vivo activity assessed by ip or per os administration in a car-
rageenan-induced edema test in rats showed that two compounds proved to be as potent as indomethacin (10 mg/kg).
ꢀ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
spite that all enzymes in each group share a number of
characteristics, the calcium-dependent sPLA2s which
are worth attention demonstrate a diverse range of func-
tions and properties. Some appear to be tissue-specific.5
Group IIA, V, and X secretory PLA2s (sPLA2s) are rec-
ognized to be involved in AA release and subsequent
eicosano¨ıd production under inflammatory conditions.6
Particularly group IIA PLA2 (GIIA PLA2) was demon-
strated to play an important pathophysiological role in
various inflammatory diseases, such as arthritis,7 septic
shock,8 adult respiratory distress syndrome,9 multiple
injuries,10 diffuse peritonitis,11,12 and acute pancreati-
tis.13–15 In these human pathologies, highly significant
increases in serum catalytic PLA2 activity have been de-
scribed which correlate well with the severity of the dis-
ease. Furthermore, sPLA2s play a pivotal role in
propagation and amplification of other inflammatory
disorders. The observation that many tumors have ele-
vated eicosano¨ıd levels16,17 shows their central role in
cancer development. Then the importance to find a drug
able to neutralize the sPLA2 involved is undeniable. An-
other advantage of PLA2 inhibitors is the reduction of
PAF levels. A multitude of structurally diverse com-
pounds described in the literature18–22 have been
The phospholipases A2 (PLA2) super family is a wide
variety of enzymes that by definition hydrolyze the sn–
2 ester bond of membrane glycerophospholipids, leading
to a lysophospholipid and releasing a fatty acid. When
the latter is arachidonic acid (AA),1 it is further metab-
olized by cyclooxygenases (COX-1 and COX-2) or
lipoxygenase (LOX) to give prostaglandins, thrombox-
ans, and leukotrienes, well-known mediators of inflam-
mation. When the lysophospholipid is the lyso-PAF, it
can be converted by the acetyltransferase into Platelet-
Activating Factor (PAF), another mediator of inflam-
matory process and tissue injury.2 PLA2 enzymes are
classified into four types (12 groups): cytosolic cal-
cium-dependent PLA2 (cPLA2), calcium-independent
PLA2 (iPLA2), low molecular-weight secretory PLA2
(sPLA2), and PAF acetylhydrolase (PAF-AH).3,4 De-
Keywords: Phospholipase; A2 inhibitors; Structure–activity; Relation-
ships; Piperazine; Indomethacin.
*
Corresponding author. Tel.: +33 (0)1 44 27 56 26; fax: +33 (0)1 44 27
56 41; e-mail: heymans@ccr.jussieu.fr
0968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.10.077

L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
1243
reported to be PLA2 inhibitors in vitro and some have
shown anti-inflammatory activity,23 but the multiple
forms of PLA2 tend to complicate the elucidation of
the cellular mechanisms that regulate AA release and
the subsequent eicosano¨ıd production. We have demon-
strated previously24–26 that a good GIIA PLA2 inhibitor
must respect a number of parameters, among them: (i)
an adequate length of chain26 which allows a good inter-
action with the hydrophobic pocket of the active site; (ii)
an aromatic ring able to induce a p–p stacking interac-
tion; and (iii) an oxadiazolone heterocycle24 whose role
is capital by interacting with calcium in its anionic form
and which seems largely responsible for the selectivity.25
This might explain the high affinity and the good activity
of compound II (Fig. 1), our first leader.26
priate alkyl halide in very good yields. To avoid dialky-
lation, this reaction was carried out, by drop by drop
addition of the alkyl halide to a large excess of
piperazine.
The alkyl piperazines 1a–c were then alkylated on N-4
position using either bromo-p-tolunitrile or 4-bromom-
ethylphenylacetonitrile 7 leading to compounds 2a–c
and 3a–c, respectively. The 1a–e derivatives were also
acylated either with 4-cyanobenzoyl chloride to give
the intermediates 4a–c or with 4-chloro (or
bromo)methylbenzoyl chloride at low temperature to
prevent a nucleophilic substitution at the 4-chlorometh-
ylene level leading to 5a–e. This latter was then treated
by sodium cyanide to give the nitriles 6a–e.
In this new series (Scheme 4) we first introduce a piper-
azine ring in the alkyl chain of II and modulate chemi-
cally the piperazine nitrogen substituent which carries
the oxadiazolone heterocycle in order to rigidify more
or less the system. Furthermore, a possible protonation
of the nitrogen atom(s) of the piperazinic cycle might be
able to lower lipophilicity as compared to our inhibitors
reported before24–26 presaging a better biodisponibility.
In fact, this series is a combination of previously de-
scribed families of active but not selective inhibitors of
GIB and GIIA sPLA2s as I,19 and active, selective but
highly lipophilic inhibitor of GIIA PLA2 as II24–26
(Fig. 1).
4-Bromomethylphenylacetonitrile 7 which is not com-
mercially available was prepared as outlined in Scheme
1, from 4-methylphenylacetonitrile using N-bromosuc-
cinimide (NBS) and a catalytic amount of 2,20-azobis-
2-methylpropionitrile (AIBN). Due to the presence of
two bromation sites in the molecule and the radicalar
process of the reaction, this step was hardly controllable.
The bad yield (35%) in the obtention of 7 is explained by
the formation of two supplementary derivatives in
nearly equivalent amounts: the 4-bromomethylphenylb-
romo acetonitrile (23%) and the 4-methylphenylbromo-
acetonitrile (25%). Nevertheless, the isolation of 7 was
possible using distillation.
All the synthesized compounds were evaluated as sPLA2
inhibitors (GIB and GIIA) in an in vitro enzymatic test
(see biological section). Some of them were then selected
and an in vivo activity was assayed using the carra-
geenan-induced paw edema test in rats. We report here
the synthesis and SAR study of this novel series and dis-
cuss with regard to the anti-PLA2 and in vivo activities.
Compounds without a linker between piperazine and
phenyl were prepared in five steps from diethanolamine
(Scheme 2). N-Alkylation by an alkyl bromide accord-
ing to Jerzy et al.27 led to the derivatives 8a–c. The hy-
droxyl groups were converted into chlorides 9a–c using
thionyl chloride according to Newman et al.28 Cycliza-
tion into piperazines 10a–c was then performed by ac-
tion of the 4-aminophenylacetonitrile on the
corresponding dichloride.
2. Chemistry
The introduction of two methylenes between phenyl and
oxadiazolone moieties was performed through the prep-
aration of the nitrile carboxylic acid derivative 14a by
the method of Brouard et al.29 adapted to our use. Cou-
pling 14a with the alkyl piperazine 1a gave the interme-
diate 15a (Scheme 3). To introduce one more methylene
group, the method above was unsuccessful. However, a
solution was found by the preparation of the bromide
derivative 11 from action of phosphore tribromide on
3-phenylpropan-1-ol (Scheme 3). Treatment of 11 with
acetyl chloride under Friedel and Crafts conditions gave
This new series of molecules displays piperazine dissym-
metric derivatives with one of the two nitrogens substi-
tuted by an alkyl chain and the second carrying an
oxadiazolone cycle through the benzyl(oyl) group. The
key intermediates of the synthesis are the nitriles 2–4,
6, 10, and 15 which were prepared using different meth-
ods as described below. Nearly all compounds shown in
Table 1 were synthesized starting from the correspond-
ing substituted piperazines 1a–e (Scheme 1) prepared
by direct monoalkylation of piperazine with the appro-
H2N
O
O
N
O
O
CH3(CH2)13
O
CH2 C
HN
N
C
OCH3
C
N
O
HO
P
N
O
OH
H
C13H27
II
I
LY311727
Figure 1. Synthetic PLA2 inhibitors.

1244
L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
Table 1. Inhibition of the enzymatic activity of porcine pancreatic PLA2 (GIB) PPLA2 and human PLA2 (GIIA) HPLA2 by piperazine derivatives of
PMS 1062, using the fluorimetric assay
N
O
R
Z
N
(CH2)n
N
N
O
H
Compound
R
Z
n
Log,Pa
IC50 (lM)
HPLA2
PPLA2
23a
23b
23c
C14H29
C16H33
C18H37
CH2
CH2
CH2
CH2
CH2
CH2
CO
0
0
0
1
1
1
0
0
0
1
1
1
1
1
1
1
1
2
3
5.301
6.339
7.370
5.593
6.631
7.669
5.480
6.526
7.564
5.780
6.814
7.856
8.894
9.932
5.949
6.983
8.017
6.297
6.814
7.08b
>100
>100
5.08
>10
10
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
8
24a
24b
24c
C14H29
C16H33
C18H37
2.2
25a
25b
25c
C
14H29
16H33
>100
>100
1.1
C
CO
CO
C18H37
C14H29
C16H33
26a
26b
26c
CO
CO
9
4
0.8
C18H37
CO
CO
26d
26e
C20H41
C22H45
C14H29
0.1
0.1
CO
27a
27b
27c
Deleted
Deleted
Deleted
CO
4.5
3.5
C
16H33
C18H37
14H29
C14H29
2.71
18.7
5.3
28a
29a
II
C
CO
4
0.47
LY311727
a LogP of the free base was calculated using the Rekker’s hydrophobic fragmental constants method.33
b See Ref. 25.
b
R
N
N CH2
CN
2a-c
c
R
N
N
CH2
CH2 CN
3a-c
a
R
N
NH
1a-e
HN
NH
d
R
N
N C
CN
O
4a-c
e
R
N
N C
O
CH2 Cl
R N
N C
O
H CN
C
2
5a-e
6a-e
CN
Br
Br
CN
CN
Br
g
CN
+
+
Br
7
Scheme 1. Reagents and conditions: (a) R–Br, THF, CH2Cl2, rt; (b) BrCH2pC6H4CN, K2CO3, KI, CH3CN, reflux; (c) 7, K2CO3, KI, CH3CN,
reflux; (d) ClCOpC6H4CN, Et3N, anhyd C6H6; (e) ClCOpC6H4CH2Cl, Et3N, C6H6, rt; (f) NaCN, DMSO, 60 ꢁC; (g) NBS, AIBN, CCl4, reflux.

L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
1245
CH2CH2OH
CH2CH2OH
a
CH2CH2OH
CH2CH2Cl
c
b
HN
R
N
R N
R
N
N
CH2 CN
CH2CH2OH
CH2CH2Cl
10a-c
9a-c
8a-c
Scheme 2. Reagents and conditions: (a) R–Br, K2CO3, KI, CH3CN; (b) SOCl2, CHCl3, rt; (c) H2NpC6H4CH2CN, KI, CH3CN, reflux.
c
a
b
(CH2)3 OH
CH3CO
(CH2)3 Br
12
(CH2)3 Br
11
O
N C
d
e
C
HO2
C14H29
N
(CH2)3 CN
(CH2)2 CN
(CH2)3 Br
13
HO2C
(CH2)3 CN
14b
15b
O
e
C14H29
N
N C
HO2C
(CH2)2 CN
14a
15a
Scheme 3. Reagents: (a) PBr3, CH2Cl2; (b) CH3COCl, AlCl3, CS2; (c) NaOH, Br2, H2O, dioxane; (d) NaCN, DMF; (e) 1a, DCC, Et3N, CH2Cl2.
the ketone 12 which was transformed into the corre-
sponding acid 13 by a bromoform reaction. Substitution
of the bromide using sodium cyanide led to the cyano-
acid 14b which was then coupled with the alkyl pipera-
zine to give the nitrile 15b.
of dicyclohexylcarbodiimide (DCC), a coupling agent lar-
gely used in peptide synthesis.
3. Results and discussion
Treatment of all these nitrile derivatives as described
previously,24 that is, first by hydroxylamine to lead to
the expected amidoximes 16–22, second using phenyl-
chloroformate, then heating the carbonate obtained in
refluxing toluene for cyclization (Scheme 4), trans-
formed them into the final oxadiazolones 23–29.
In our previous publications leading to II,24–26 our home
reference, we showed on one hand the necessity of an
optimal length of 14 carbons for hydrophobic interac-
tions26 with the sub-sites of the enzyme, an aromatic
ring probably for the interactions p–p or cation–p and
on the other hand, a heterocycle: the oxadiazolone, a
polar hydrophilic head24 which could interact with the
calcium ion inside the active site and would be responsi-
In order to improve the yields of different steps (synthesis
of compounds 28a and 29a), we chose to follow another
strategy consisting in condensation of alkylpiperazine
1a–e with the oxadiazolylmethylbenzoic acid, prepared
as previously reported by Kitamura et al.30 in the presence
25
ble for the selectivity.
In this work, we introduce the piperazinic ring while
keeping the same modifications as those studied for II,
a
N
OH b,c
R
N
N Z
(CH2)n CN
R
N
N Z
(CH2)n
NH2
2-4, 6, 10, 15
16-22
n
0
1
0
1
1
2
3
Z
N
O
CH2
CH2
CO
CO
deleted
CO
16
17
18
19
20
21
22
23
R
N
N Z
(CH2)n
24
25
26
27
28
29
N
O
H
23-29
CO
Scheme 4. Reagents and conditions: (a) NH2OH, HCl, K2CO3, EtOH, reflux; (b) ClCOOPh, NEt3, CH2Cl2; (c) toluene, reflux.

1246
L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
that is, number of methylenes between the oxadiazolyl
and phenyl groups (compounds 23a, 24a, 28a, and
29a) and variation of the alkyl chain length between
14 and 22 carbon atoms. The piperazine ring, relatively
flexible but supposed to be a little more rigid, due to the
privileged chair conformations, than the alkyl chain in
II, was also introduced to estimate the variation of the
flexibility at this level on activity. For this reason, we
rendered this cycle less flexible by substitution of the
nitrogen carrying the oxadiazolyl bearing part by a car-
bonyl group (compounds 25a–c and 26a–e) or branching
directly the phenyl group (compounds 27a–c). Our prin-
cipal aim was also to reduce the global lipophilicity ren-
dered possible by nitrogen protonation at physiological
pH, for a better biodisponibility compared to that of II
which appeared inactive in vivo.
erazinic cycle, obtained when the nitrogen branched to
the oxadiazolyl carrying moiety looses its sp3 character
to sp2, was favorable to this activity. Good results are
also obtained when Z is deleted and the phenyl directly
branched to the nitrogen (27a–c), probably for the same
reasons. Several hypothesis can explain this fact: (i) a
beneficial change of the conformation due to the amide
function in one case and the conjugation between the
nitrogen doublet and the phenyl in the second, to adapt
the most effective position in the catalytic site; (ii) a new
electronic distribution with the presence of the carbonyl
induced a negative electrostatic potential which can
interact with a sub-site of the enzyme; (iii) a hydrogen
bond formation between this same carbonyl and the cat-
alytic site. Effectively, following the works of Poi et al.31
which demonstrated the evidence and characterized a
unique low barrier hydrogen bond (LBHB) between
the imidazole ring of the histidine 48 and the oxygen
of a transition state analog inhibitor, a conformational
calculation study would certainly show whether the car-
bonyl group of the amidified piperazine is involved or
not in a hydrogen bond with histidine 48 or another res-
idue near the active site of the enzyme.
3.1. In vitro activity
All the synthesized compounds were tested on group IIA
versus IB enzymes. As shown in Table 1, all compounds
23–29 are, at the first glance, either inactive on the PLA2
of the two groups (23a, 23b, 25a–25b) or, like the refer-
ence product II, only inhibitors of group II sPLA2, thus
with the required selectivity. Several of them, 26a–c, are
twice less (26a, IC50 = 9 lM) to 40 times more active
(26d and 26e, IC50 = 0.1 lM) than the reference II
(IC50 = 4 lM) and the more active 26d and 26e are as
potent as Lilly’s Laboratories, LY31172721 a compound
very structurally different from ours which was de-
scribed in the literature as very potent and that we in-
cluded in our assay for comparison, being then tested
in the same conditions as ours.
Concerning the lipophilicity, most of the active com-
pounds of this series need a logP value for the free base
(from 7.5 to 10 U) at least as high as reference II and in
the homogenous series 26a–e, by example, the activity
increases as a function of this log P value. This is not
surprising as the in vitro activity is measured directly
on purified enzymes where the catalytic site is well
known to be located at the end of a highly hydrophobic
channel adapted to accommodate long alkyl chains of
phospholipids.
In this study, we can verify that, in agreement with our
previous results,24 a methylene spacer between the phe-
nyl ring and the oxadiazolone is favorable to inhibition:
23a and 23b as well as 25a and 25b (n = 0) are inactive
while 26a, 26b, 27a, and 27b (n = 1) are as active as
the reference II. Nevertheless, this can be compensated
by an increase of the lipophilicity as shown for 23c
and 25c which have curiously the same logP (close to
7 units) as our leader II. This improvement is necessarily
due not only to the adequate lipophilic character, but it
can be postulated that introduction of more flexibility
between those cycles allows a better access of the oxa-
diazolone to the calcium binding site. But, no increase
of the activity appears anymore with the addition of
one or two methylenes to this linker (28a and 29a).
3.2. In vivo activities
They were measured in two different models of inflam-
mation, in one hand, in the classical carrageenan-in-
duced edema test; compounds were administered ip or
per os 1 h before the injection of carrageenan into the
hind leg of the rats and the volume of edema was mea-
sured 0, 3 and 5 h after the injection of carrageenan. In
the other hand, to evaluate the topical anti-inflamma-
tory activity cutaneous inflammation was induced on
the inner surface of the ear of anaesthetized mice by
application of croton oil and the reduction of the edema
by the selected compounds was measured after local
application or per os administration.
Just introducing the piperazinic moiety in the alkyl
chain of II, as shown in 24b and 24c, while keeping
the same lipophilicity does not afford any improvement
as the IC50s are of the same order of magnitude. This is
not surprising as; in this case, the sp3 hybridization of
the nitrogens is the same as, for the carbon atoms of
the alkyl chain, leading to a rather high flexibility. On
the other hand, as already described with non-selective
inhibitors before,19 compounds with Z = CO (25c,
IC50 = 1.1 lM, 26c, IC50 = 0.8 lM) are between two
and three times more active than their analogs having
Z = CH2 (23c, IC50 = 5.08 lM and 24c, IC50 = 2.2 lM).
Then it looks like if the partial rigidification of the pip-
In spite of its moderate in vitro activity, compound 26a
was selected by the pharmacologists, mainly for its low
lipophilicity in this series, to research possible anti-
inflammatory properties in a complementary pharmaco-
logical test. Compound 24a was also selected for com-
parison because it has a similar lipophilicity to 26a
and as previous studies showed us some derivatives, in
spite of no in vitro activity, sometimes presented surpris-
ingly sometimes interesting effects in vivo. The two com-
pounds administrated ip or po were evaluated on acute
responses where mammalian group II sPLA2 is sup-
posed to be involved and compared to indomethacin,
a well-known anti-inflammatory agent which acts at

L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
1247
Table 2. Local anti-inflammatory effect by topical administration of the
pms compounds in the ear edema test induced by croton oil
the local edema experimental model induced by croton
oil. They have a good potency to reduce the topical
inflammatory effect due to the same agent, compared
to indomethacin. Our synthetic work and the consecu-
tive biological evaluation of the oxadiazolone–pipera-
zine derivatives demonstrate the originality of this new
class of compounds. Their potential therapeutic effect
in the inflammatory process is promising. The explora-
tion in the design of these new potent derivatives may al-
low a greater understanding of the structural parameters
required for activity and may shed the light on the role
of the oxadiazolone in the selectivity. It is possible that
the effect of this oxadiazolone series on GIIA PLA2 re-
sults from its interaction with a novel type of oxadiazo-
lone-binding sub-site.
Compound
Dose (mg/ear)/
(mmol)
Number
of animalsa
Edema
inhibition (%)
24a
26a
1/0.00212
1/0.00206
0.5/0.00139
56 (7)
56 (7)
72 (9)
51.45 11.67
47.83 12.34
43.11 8.79
Indomethacin
a The numbers in parentheses imply the number of performed
experiments.
the COX level rather than inhibiting PLA2. In the carra-
geenan-induced edema formation test, preliminary re-
sults by the intraperitoneal route show that the two
compounds possessed an equivalent activity. Thus, at
a 10-mg/kg dose, the inhibitions of edema by indometh-
acin and 24a were 79% and 73%, respectively. By the
oral route, 24a had also a longer activity in time than
that of indomethacin. In addition, 5 h after carrageenan
injection, 26a inhibited always 65% of the edema against
16% remaining effect for indomethacin, when the two
products were administered orally at a dose of 10 mg/
kg. In the same conditions the activity of II (logP-
cal = 7), our home reference, disappeared completely.
These results suggest that the high lipophilic character
of II could prevent this latter totally and the indometh-
acin (logPexp = 4.27) partially, from a good biodistribu-
tion. The protonation ability at physiological pH of our
piperazinic derivatives leading to lower lipophilic com-
pounds could explain the best per os activity. The same
compounds were assayed for local anti-inflammatory ef-
fect by topical administration in the ear edema induced
by croton oil and the data are reported in Table 2.
Further chemical modulations to obtain more active
compounds and develop structure-activity relationships
are required to verify our hypothesis on the possible
contribution of the piperazine ring to the PLA2 inhibi-
tory effect. For this purpose, the synthesis of new com-
pounds is in progress particularly with the aim to
rigidify the piperazine ring as suggested by results in
the present work. We are also investigating electronic
and structural modifications using a molecular modeling
approach to understand these requirements.
5. Experimental
5.1. Chemistry
All materials were obtained from commercial suppliers
and used without further purification. Thin-layer chro-
matography was performed on TLC plastic sheets of sil-
ica gel 60F254 (layer thickness 0.2 mm) from Merck.
Column chromatography purification was carried out
on silica gel 60 (70–230 mesh ASTM, Merck). All melt-
ing points were determined on a digital melting point
apparatus (Electrothermal) and were uncorrected. The
structure of all compounds was confirmed by IR and
1H and 13C NMR spectra. IR spectra were obtained in
paraffin oil or KBr with an ATI Mattson Genesis Series
FTIR spectrometer, and 1H NMR or 13C NMR spectra
were recorded in CDCl3 or DMSO-d6 on a BRUCKER
AC 200 spectrometer using hexamethyldisiloxane
(HMDS) as an internal standard. Chemical shifts are gi-
ven in ppm and peak multiplicities are described as fol-
lows: s, singlet; ls, large singlet; d, doublet; t, triplet; br,
broad; m, multiplet. Elemental analyses were performed
According to these results, 26a and 24a present equiva-
lent activities. After administration of 1 mg/ear of these
derivatives, 50% inhibition of the edema was observed
compared to 40% obtained with indomethacin, 0.5 mg/
ear.
However, in the oral edema experimental model induced
by croton oil, compounds 24a and 26a were inactive and
this suggests that oral administration of these com-
pounds did not induce a systemic anti-inflammatory
effect.
The difference in these in vivo results is probably due to
the biodisponibility of the drug candidates in both
inflammatory tissues.
´
´
by the ‘Service Regional de Microanalyse’, Universite
Pierre et Marie Curie, Paris, France, and were within
0.4% of theoretical values.
4. Conclusions
As the result of this SAR investigation, we discovered
more than twenty novel potent piperazinic derivatives
that showed improved anti-PLA2 activity with a high
selectivity for GIIA versus GIB PLA2s compared to
the reference compound of Lilly LY311727 and more ac-
tive than our home reference II. In addition, two com-
pounds 24a and 26a tested in vivo show interesting
long-lasting activities in the carrageenan-induced edema
formation as well after ip or per os administration. They
also decreased significantly the inflammatory effect in
5.2. In vitro biological activity assay
PLA2 activity was evaluated by the method of Radvanyi
et al.32 using our reference II and using the reference
control LY311727 of Lilly company.21 Enzymes tested
were two secretory enzymes of human recombinant
PLA2 (group II) and a secretory enzyme of porcine pan-
creatic (group I) PLA2. Palmitoyl-2-(10-pyrenyldeca-
noyl)-sn-glycero-3-phosphatidyl gly-cerolic acid was

1248
L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
used as a fluorescent substrate in the fluorometric assay
which was performed with a Perkin-Elmer LS50 lumi-
nescence spectrometer in a unit dosage polystyrene cell
having a size of 1 cm. The concentration of the fluores-
cent substrate was determined by UV Unicam spectrom-
etry in a quartz cell. The experimental protocol was the
same as described in our previous publications.24–26 The
logP values were calculated using the Rekker’s hydro-
phobic fragmental constants method.33
to 1c (4.5 g, 89%) as white crystals: mp 61.5 ꢁC; IR
1
(KBr, m cmꢀ1): 3440 (NAH); H NMR (CDCl3) d: 6–8
(1s, 1H, NH), 2.85 and 2.33 (2t, 8H, J = 4.88 and
4.50 Hz, H of piperazine), 2.21 (t, 2H, J = 7.56 Hz,
CH2AN), 1.40 (m, 2H, CH2ACH2AN), 1.20 (1s, 30H,
CH2), 0.80 (t, 3H, J = 6.6 Hz, CH3).
5.5. 1-(4-Cyanobenzyl)-4-tetradecylpiperazine (2a)
A vigorously stirred suspension of 1-tetradecylpiperazine
1a (6 g, 21 mmol), 4-cyanobenzyl bromide (4.93 g,
25 mmol), K2CO3 (9 g, 65 mmol), and KI (0.5 g) in
CH3CN (200 mL) was heated to reflux until TLC analysis
showed the reaction to be complete. The mixture was fil-
tered, and K2CO3 washed several times with CH2Cl2.
The solvents were evaporated under vacuum, the result-
ing residue was diluted withCH2Cl2 (150 mL) and washed
with water until neutral pH. The organic phase was dried
over MgSO4, filtered and concentrated under reduced
pressure. The product was recrystallized in acetone to
provide 2a (7.4 g, 88%) as white crystals: mp 49.1 ꢁC, IR
(KBr, m cmꢀ1): 2248 (CN), 1607 (C@Car); 1H NMR
(CDCl3) d: 7.52 and 7.37 (2d, 4H, J = 8.06 Hz, Ar H),
3.49 (s, 2H, PhACH2AN), 2.44 (ls, 8H, piperazine H),
2.35 (t, 2H, J = 7.64 Hz, CH2AN), 1.65–1.42 (m, 2H,
CH2ACH2AN), 1.18 (1s, 22H, CH2), 0.80 (t, 3H,
J = 6.66 Hz, CH3). Compounds 2b (89%) and 2c (74%),
mp 42 ꢁC, were prepared using the same process.
5.3. In vivo biological activity assay
5.3.1. Carrageenan-induced edema. In vivo activity of
compounds was assessed by a classical carrageenan-in-
duced edema test in rats, with indomethacin as a posi-
tive control. They were administered intraperitoneally
or orally 1 h before the injection of carrageenan into
the hind leg of the rats. The volume of edema was mea-
sured 0, 3, and 5 h after the injection of carrageenan.
The doses used were 5, 10, and 20 mg/kg for the two
products tested.
5.3.2. In vivo anti-inflammation. It concerns an assay for
the in vivo anti-inflammatory activity of two com-
pounds of those series, by the ear edema test as an acute
inflammatory experimental model. Different samples of
studied compounds were prepared.
After inducing edema on one ear of mice by the applica-
tion of croton oil, the samples of each compound as de-
scribed above were dissolved in 80% chloroform. The
resulting solution was applied on the ear at a dose of
1 mg of each compound per ear. The other ear was ap-
plied only with the solvent, that is, 80% chloroform. At
the end of 5 h of the initiation of the experiment, the ear
tissue at the level of edema was collected by a gimlet
from the skin, and the tissue collected was compared
with that collected from the control ear by a gimlet, to
calculate the percent inhibition.
5.6. 1-(4-Cyanomethylbenzyl)-4-tetradecylpiperazine (3a)
5.6.1. 4-Bromomethylphenylacetonitrile (7). In a 1-L
Erlenmeyer flask, 4-methylphenyl acetonitrile (25 g,
0.19 mol) was dissolved in CCl4 (300 mL). To the solu-
tion, NBS (41 g, 0.23 mol) freshly crystallized in acetic
acid prior to use and 2,20-Azobis(2-methylpropionitrile)
(AIBN) 0.5 g were added. After refluxing for 3 h, the
solution was cooled and washed three times with water.
The organic phase was dried over MgSO4, filtered and
evaporated in vacuum. Distillation of the residue under
reduced pressure (1 mmHg) allowed successive recovery
of three fractions at 95, 110, and 140 ꢁC. The last one
(Teb = 140 ꢁC) corresponding to the desired compound
was crystallized from diethyl ether at ꢀ18 ꢁC, to pro-
duce 7 (14 g, 35%) as white crystals: mp 63 ꢁC; IR
(KBr, m cmꢀ1): 2224 (CN), 1594 (C@Car); 1H NMR
(CDCl3) d: 7.34 and 7.24 (2d, 4H, J = 8.28 Hz, Ar H),
4.41 (s, 2H, CH2ABr), 3.68 (s, 2H, CH2ACN).
5.3.3. Systemic anti-inflammatory effect. The samples of
the compounds (Table 2) were suspended in CMS, and
administered orally at a ratio of 80 mg of each com-
pound per mouse. At 1 h after the initiation of the
experiment, edema was induced by the application of
croton oil. At 5 h after the application of croton oil,
the tissues where edema had been developed were col-
lected by a gimlet, and compared with the tissue col-
lected from a control part, to calculate the percent
inhibition. To calculate the statistical significance, the
results obtained in each of the control group and the
tested group were evaluated by Student’s t-test.
5.6.2. 1-Tetradecylpiperazine 1a (7 g, 24 mmol), 4-bro-
momethylphenylacetonitrile (6 g, 28 mmol), K2CO3
(9.93 g, 71 mmol), and KI (0.5 g) were mixed in acetoni-
trile (200 mL) and refluxed for 6 h. The suspension was
then filtered, and the solid was washed several times
with CH2Cl2. The solvents were evaporated, and the res-
idue taken up in CH2Cl2 (150 mL) was washed with
water until neutral pH. The organic phase was dried
over MgSO4, filtered, and concentrated under reduced
pressure. The residue was purified by chromatography
on silica gel eluted by MeOH/CH2Cl2 (1:99, v/v) as elu-
ent, to afford the title nitrile (8.2 g, 83%) as a brown oil:
5.4. 1-Alkylpiperazines (1a–e)
One example is given for 1-octadecylpiperazine 1c. To a
solution of piperazine (13 g, 0.15 mol) in a mixture of
THF/CH2Cl2 (3:1) (100 mL) was added 1-bromooctade-
cane (5 g, 15 mmol) and the solution was stirred at room
temperature for 1 h. The solvents were evaporated and
the residue solubilized in CH2Cl2 was then washed twice
with water. The organic layer was dried (MgSO4), fil-
tered, and evaporated. Recrystallization in acetone led
1
IR (film, m cmꢀ1): 2248 (CN), 1607 (C@Car); H NMR
(CDCl3) d: 7.25 and 7.18 (2d, 4H, J = 8.23 Hz, Ar H),

L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
1249
3.63 (s, 2H, CH2ACN), 3.42 (s, 2H, PhACH2AN), 2.40
(ls, 8H, piperazine H), 2.27 (t, 2H, J = 7.64 Hz,
CH2AN), 1.55–1.4 (m, 2H, CH2ACH2AN), 1.17 (ls,
22H, CH2), 0.80 (t, 3H, J = 6.7 Hz, CH3).
Ar H), 3.71 (s, 2H, CH2ACN), 3.72 and 3.38 (2ls, 4H,
CH2ANACAO of piperazine), 2.37 (ls, 4H, H of piper-
azine), 2.29 (t, 2H, J = 7.65 Hz, CH2AN), 1.41–1.35 (m,
2H, CH2ACH2AN), 1.18 (ls, 30H, CH2), 0.81 (t, 3H,
J = 6.6 Hz, CH3).
5.7. 1-(4-Cyanobenzoyl)-4-tetradecylpiperazine (4a)
5.9. 1-(4-Cyanomethylphenyl)-4-octadecylpiperazine
(10c)
Tetradecylpiperazine 1a (6.5 g, 23 mmol) and Et3N
(4.79 mL, 34 mmol) were dissolved in dry benzene
(100 mL) and the mixture was stirred at 0 ꢁC. 4-Cya-
nobenzoyl chloride (4.95 g, 29 mmol) solubilized in ben-
zene (20 mL) was then added dropwise. After 2 h
stirring at room temperature, the solvent was evaporated;
the residue was taken up in CH2Cl2, washed with an alka-
line solution and with water until neutrality. The organic
phase was dried over MgSO4, filtered and concentrated in
vacuum. The product was then purified by chromatogra-
phy on a silica gel column with CH2Cl2 as eluent, to afford
4a as a brownish oil (6 g, 63%): IR (film, m cmꢀ1): 2251
5.9.1. N-Octadecyldiethanolamine (8c). This derivative
was prepared according to Jerzy et al.,27 starting from
diethanolamine (10 g, 95 mmol), octadecyl bromide
(37.96 g, 0.114 mol), K2CO3 (39.33 g, 0.285 mol) and
KI (0.5 g) in CH3CN (200 mL) to afford 8c, after crystal-
lization from acetone, as 33 g (quantitative) of white
crystals: mp 49 ꢁC; IR (KBr, m cmꢀ1): 3310 (OAH); H
1
NMR (CDCl3) d: 3.53 (t, 4H, J = 5.43 Hz, CH2AO),
3.27 (1s, 2H, OH), 2.57 (t, 4H, J = 5.43 Hz,
NACH2ACAO), 2.44 (t, 2H, J = 7.06 Hz, CH2AN),
1.41–1.34 (m, 2H, CH2ACH2AN), 1.18 (ls, 30H, CH2),
0.80 (t, 3H, J = 5.85 Hz, CH3).
1
(CN), 1620 (NCAO), 1607 (C@Car); H NMR (CDCl3)
d: 7.63 and 7.42 (2d, 4H, J = 8.48 Hz, Ar H), 3.72 and
3.30 (2ls, 4H, CH2ANACAO of piperazine), 2.44 (ls,
4H, H of piperazine), 2.29 (t, 2H, J = 7.9 Hz, CH2AN),
1.55–1.35 (m, 2H, CH2ACH2AN), 1.18 (ls, 22H, CH2),
0.81 (t, 3H, J = 6.7 Hz, CH3). Compounds 4b (71%) and
4c (76%) were obtained in the same manner from 1b and
1c, respectively.
5.9.2. N,N0-Di(chloroethyl)octadecylamine (9c). In this
step we adapted to our use the method of Newman
et al.28 The diol 8c (13 g, 36 mmol) was dissolved in CHCl3
(100 mL) and cooled to 0 ꢁC, and, thionyl chloride
(7.95 mL, 0.109 mmol) was added dropwise. After com-
pletion of the addition, the reaction mixture was refluxed
for 3 h. The solvent and excess of thionyl chloride were
evaporated and the residue taken up in CH2Cl2 was
washed with a Na2CO3 saturated aqueous solution and
several times with water until neutralization. The organic
phase was dried over MgSO4, filtered, and concentrated
under vacuum. The residue was purified by chromatogra-
phy on silica gel eluted by ether/petroleum ether (5:95, v/v)
and yielded the chloride derivative 9c (10 g, 70%) as an oil:
IR (film, m cmꢀ1): no hydroxyle; 1H NMR (CDCl3) d: 3.38
(t, 4H, J = 5.43 Hz, CH2ACl), 2.75 (t, 4H, J = 7.30 Hz,
NACH2ACH2ACl), 2.43 (t, 2H, J = 6.67 Hz, CH2AN),
1.40–1.36 (m, 2H, CH2ACH2AN), 1.16 (ls, 30H, CH2),
0.80 (t, 3H, J = 5.95 Hz, CH3).
5.8. 1-(4-Cyanomethylbenzoyl)-4-octadecylpiperazine (6c)
5.8.1. 1-(40-Bromomethylbenzoyl)-4-octadecylpiperazine
(5c). Octadecylpiperazine 1c (4.4 g, 13 mmol) and Et3N
(2.7 mL, 19 mmol) were dissolved in anhydrous benzene
(100 mL). The mixture was stirred at 0 ꢁC, and 4-bro-
momethylbenzoyl chloride (3.04 g, 13 mmol) was added
dropwise. After stirring for 2 h at room temperature,
the solvent was evaporated and the resulting residue was
diluted in CH2Cl2. It was then washed with alkaline solu-
tion, and several times with water until neutralization.
The organic phase was dried over MgSO4, filtered, and
concentrated under vacuum. The crude product was puri-
fied by chromatography on silica gel eluted with CH2Cl2
and yielded 5 g (72%) of pure 5c as an oil: IR (film,
m cmꢀ1): 1624 (NCAO), 1607 (C@Car); 1H NMR (CDCl3)
d: 7.38 and 7.31 (2d, 4H, J = 3 Hz, Ar H), 4.42 (s, 2H,
CH2ABr), 3.72 and 3.38 (2ls, 4H, CH2ANACAO of
piperazine), 2.41 (ls, 4H, H of piperazine), 2.29 (t, 2H,
J = 8 Hz, CH2AN), 1.55–1.35 (m, 2H, CH2ACH2AN),
1.18 (ls, 30H, CH2), 0.81 (t, 3H, J = 6.75 Hz, CH3).
5.9.3. Compound 9c (3 g, 7.6 mmol), 4-aminophenyl-
acetonitrile (2 g, 15 mmol), and KI (0.2 g) in CH3CN
(100 mL) were mixed and the suspension was stirred un-
der reflux for 16 h. The solvent was then evaporated and
the residue was diluted in CH2Cl2, washed with alkaline
solution and then several times with water. The organic
phase was dried over MgSO4, filtered, and concentrated
under vacuum. The resulting residue was crystallized
from acetone to produce the title substituted 10c piper-
azine (2.66 g, 77%) as white crystals: mp 94 ꢁC; IR (KBr,
m cmꢀ1): 2252 (CN), 1607 (C@Car); 1H NMR (CDCl3) d:
7.17 and 6.84 (2d, 4H, J = 8.61 Hz, Ar H), 3.62 (s, 2H,
CH2ACN), 3.61 and 3.22 (2ls, 8H, H of piperazine),
2.92 (t, 2H, J = 8.32 Hz, CH2AN), 1.88–1.82 (m, 2H,
CH2ACH2AN), 1.19 (ls, 30H, CH2), 0.81 (t, 3H,
J = 5.95 Hz, CH3).
5.8.2. The bromide derivative 5c (5.35 g, 10 mmol) pre-
pared in the step above was dissolved in dimethylsulfox-
ide (70 mL). The solution was stirred at 0 ꢁC and sodium
cyanide (1.96 g, 40 mmol) was added by portions. The
mixture was then heated at 80 ꢁC for 1 h. The reaction
medium was diluted with CH2Cl2 and water. The organ-
ic phase was washed several times with water, dried over
MgSO4, filtered, and concentrated under vacuum. The
residue was purified by chromatography on a silica gel
column, with CH2Cl2 as eluent. This yielded the title ni-
trile 6c (3 g, 61%) as a thick honey-colored oil: IR (film,
5.10. 4-(3-Cyanopropyl)benzoic acid (14b)
1
m cmꢀ1): 2251 (CN), 1620 (NCAO), 1607 (C@Car); H
5.10.1. 1-Bromo-3-phenylpropane (11). To a solution of
3-phenylpropan-1-ol (10 g, 73 mmol) in anhydrous
NMR (CDCl3) d: 7.36 and 7.30 (2d, 4H, J = 8.50 Hz,

1250
L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
CH2Cl2 (150 mL), a solution of PBr3 1M in CH2Cl2
(36 mmol, 50 mL) was added dropwise. The reaction
mixture was stirred at room temperature for 1 h. After
washing several times with water, the organic phase
was dried and evaporated. The residue was purified by
chromatography on silica gel eluted with ether/petro-
leum ether (5:95, v/v) to give the bromide derivative 11
(11.6 g, 80%) as a viscous liquid: IR (film, m cmꢀ1):
pound 14a (5.68 g, 68%) as a white solid: mp 165 ꢁC; IR
(KBr, m cmꢀ1): 1700 (CAO), 2252 (CN); 1H NMR
(CDCl3) d: 7.9 (d, 2H, J = 8.17 Hz, Ar H), 7.25 (d,
2H, J = 8.13 Hz, Ar H), 2.95 (t, 2H, J = 7.22 Hz,
CH2CN), 2.6 (t, 2H, J = 7.36 Hz, CH2CH2CN).
5.12. 1-[4-N-(Hydroxyamidino)benzyl]-4-tetradecylpiper-
azine (16a)
1
1605 (C@Car); H NMR (CDCl3) d: 7.25–7.06 (m, 5H,
Ar H), 3.29 (t, 2H, J = 6.59 Hz, CH2Br), 2.68 (t, 2H,
J = 7.34 Hz, PhCH2CH2CH2Br), 2.14–1.99 (m, 2H,
CH2CH2CH2Br).
To a suspension of K2CO3 (8 g, 57 mmol) and NH2OH,
HCl (3.2 g, 46 mmol) in refluxing absolute EtOH
(150 mL), was added dropwise the nitrile 2a (3.7 g,
9.2 mmol) dissolved in absolute EtOH (50 mL) and the
mixture was refluxed for 6 h. Salts were filtered and
washed several times with CH2Cl2. The filtrate was con-
centrated under reduced pressure and the crude product
was taken up in CH2Cl2. The organic phase was washed
with water until neutrality, dried over MgSO4, then fil-
tered. After evaporation of the solvent, the product
was crystallized in acetone to lead to the amidoxime
16a (2.7 g, 69%) as white crystals: mp 104.7 ꢁC, IR
(KBr, m cmꢀ1): 3490 (OAH), 3374 (NH2), 1655 (CAN),
5.10.2. 4-(3-Bromopropyl)acetophenone (12). The bro-
mide derivative 11 (25 g, 125 mmol) solubilized in acetyl
chloride (20 mL) was added dropwise at 0 ꢁC to a solution
of aluminum trichloride (17.5 g, 88 mmol) and acetyl
chloride (50 mL) in CS2 (100 mL). The mixture was stir-
red at room temperature for 2 h. Excess of acetyl chloride
and CS2 were removed by evaporation under reduced
pressure. The residue was diluted in CH2Cl2, washed suc-
cessively with alkaline solution, several times with water,
dried over MgSO4 and concentrated under vacuum, to
yield the title substituted acetophenone 12 (23.8 g, 79%)
as a yellow liquid: bp3 mm Hg 140–145 ꢁC; Rf 0.25 (ether/
petroleum ether, 50:50, v/v); IR (film, m cmꢀ1): 1670
1
1607 (CACar); H NMR (CDCl3) d: 7.50 and 7.28 (2d,
4H, J = 8 Hz, Ar H), 4.78 (s, 2H, NH2), 3.46 (s, 2H,
PhACH2AN), 2.43 (ls, 8H, piperazine H), 2.25 (t, 2H,
J = 8 Hz, CH2AN), 1.5–1.35 (m, 2H, CH2ACH2AN),
1.18 (1s, 22H, CH2), 0.80 (t, 3H, J = 7 Hz, CH3). Com-
pounds 16b and 16c were obtained following the same
process with approximately the same yield.
1
(CAO), 1605 (C@Car); H NMR (CDCl3) d: 7.79 (ls,
2H, Ar H), 7.23 (ls, 2H, Ar H), 3.26 (t, 2H, J = 6.49 Hz,
CH2Br), 2.7 (t, 2H, J = 6.26 Hz, PhCH2CH2CH2Br),
2.48 (s, 3H, CH3), 2.08–1.9 (m, 2H, CH2CH2CH2Br).
5.13. 1-[4-(N-Hydroxyamidinomethyl)benzyl]-4-tetradecyl-
piperazine (17a)
5.10.3. 4-(3-Bromopropyl)benzoic acid (13). To a NaOH
(33 g, 82.5 mmol) solution in water (200 mL), Br2
(50 mL) and dioxane (100 mL) were successively added
dropwise. The mixture was cooled to 0 ꢁC and 12 (22 g,
91.2 mmol) was added dropwise. Stirring was maintained
at room temperature until the brown color ofbromide dis-
appeared (1 h). The mixture was then carefully acidified
with an aqueous solution of 12 N HCl (20 mL). The pre-
cipitate was filtered, washed several times with water, and
dried to afford 26 (18 g, 85%) as a yellow solid: mp 120 ꢁC;
This intermediate was obtained in the same conditions as
16a using K2CO3 (13.08 g, 94 mmol), NH2OH, HCl
(5.48 g, 78 mmol) in absolute ethanol (150 mL), and the
nitrile 3a (6.5 g, 15 mmol). After evaporation of the sol-
vent, the residue was crystallized from acetone to give
the title amidoxime 17a (4.62 g, 65%) as white crystals:
mp 74 ꢁC; IR (KBr, m cmꢀ1): 3490 (OAH), 3374 (NH2),
1
1655 (CAN), 1607 (C@Car); H NMR (CDCl3) d: 7.20
1
IR (KBr, m cmꢀ1): 3340 (OH), 1700 (CAO); H NMR
and 7.15 (2d, 4H, J = 6 Hz, Ar H), 4.38 (s, 2H, NH2),
3.43 (s, 2H, CH2ACAN), 3.35 (s, 2H, PhACH2AN),
2.41 (m, 8H, piperazine H), 2.25 (t, 2H, J = 8 Hz,
CH2AN), 1.55–1.36 (m, 2H, CH2ACH2AN), 1.18 (ls,
22H, CH2), 0.80 (t, 3H, J = 6.13 Hz, CH3).
(CDCl3) d: 7.9 (d, 2H, J = 8.16 Hz, Ar H), 7.2 (d, 2H,
J = 8.3 Hz, Ar H), 3.3 (t, 2H, J = 6.47 Hz, CH2Br), 2.78
(t, 2H, J = 7.7 Hz, Ph CH2CH2CH2Br), 2.18–2.04 (m,
2H, CH2CH2CH2Br).
5.10.4. The bromide derivative 13 (18 g, 77.5 mmol) pre-
pared above was converted into the nitrile 14b by the
same procedure as described for the preparation of 6c
and yielded 14b (11 g, 75%) with a viscous appearance.
IR (film, m cmꢀ1): 3345 (OH), 1700 (CAO), 2253 (CN);
1H NMR (CDCl3) d: 7.9 (d, 2H, J = 8.09 Hz, Ar H),
7.2 (d, 2H, J = 8.09 Hz, Ar H), 2.8 (t, 2H, J = 7.44 Hz,
CH2CN), 2.28 (t, 2H, J = 6.99 Hz, PhCH2CH2CH2CN),
2.02–1.91 (m, 2H, CH2CH2CH2CN).
5.14. 1-[4-(N-Hydroxyamidino)benzoyl]-4-tetradecylpip-
erazine (18a)
1-[4-(N-Hydroxyamidino)benzoyl]-4-tetradecylpiper-
azine (18a) was prepared in the same conditions as for
16a, from 4a (6 g, 14 mmol), to give 18a (4 g, 64%) as
white crystals (acetone): mp 143.6 ꢁC; IR (KBr, m cmꢀ1):
3486 (OAH), 3373 (NH2), 1657 (NCAO), 1625 (CAN),
1
1582 (C@Car); H NMR (CDCl3) d: 7.58 and 7.34 (2d,
4H, J = 8 Hz, Ar H), 4.43 (s, 2H, NH2), 3.73 and 3.40
(2m, 4H, CH2ANACAO of piperazine), 2.55 (m, 4H,
H of piperazine), 2.29 (t, 2H, J = 6.64 Hz, CH2AN),
1.39 (m, 2H, CH2ACH2AN), 1.18 (ls, 30H, CH2), 0.81
(t, 3H, J = 6.03 Hz, CH3). Starting from nitriles 4b
and 4c compounds: 18b (34%), mp 130 ꢁC and 18c
(23%), mp 130.2 ꢁC, were obtained by the same manner.
5.11. 4-(2-Cyanoethyl)benzoic acid (14a)
This intermediate was prepared according to the method
of Brouard et al.29 starting from 4-(2-chloro-2-cyano-
ethyl)benzoic acid (10 g, 47 mmol), glacial acetic acid
(250 mL), zinc powder (1.56 g, 23 mmol) and gave com-

L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
1251
5.15. 1-[4-(N-Hydroxyamidinomethyl)benzoyl]-4-octade-
cylpiperazine (19c)
57.84 (CH2N), 52.43 (CH2NACH2APh), 50.79
(CH2NC13), 31.88 (CH2CH2N), 29.30 (CH2), 27.03
(CH2), 24.88 (CH2), 22.65 (CH2), 14.09 (CH3).
The same procedure was used as described for 12a starting
from 6c (6 g, 12 mmol), K2CO3 (10.26 g, 74 mmol) and
NH2OH, HCl (4.30 g, 61 mmol). The crude product was
crystallizedfromacetonetogive4 g(67%)ofthetitleoxime
19c as white crystals: mp 105.2 ꢁC; IR (KBr, m cmꢀ1): 3486
(OAH), 3373 (NH2), 1657 (NCAO), 1625 (CAN), 1582
Anal. Calcd for C27H44N4O2/0.5H2O (465): C, 69.67; H,
9.67; N, 12.04. Found: C, 69.70; H, 9.89; N, 11.87.
Final compounds 23b (63%), mp 120.6 ꢁC, and 23c
(37%), mp 109 ꢁC, were prepared by the same reaction
starting from the corresponding amidoximes 16b and
16c, respectively.
1
(C@Car); H NMR (CDCl3) d: 7.30 and 7.24 (2d, 4H,
J = 8 Hz, Ar H), 4.44 (s, 2H, NH2), 3.42 (s, 2H,
CH2ACAN), 3.73 and 3.40 (2ls, 4H, CH2ANACAO of
piperazine), 2.37 (ls, 4H, H of piperazine), 2.29 (t, 2H,
J = 8 Hz, CH2AN), 1.50–1.35 (m, 2H, CH2ACH2AN),
1.18 (ls, 30H, CH2), 0.81 (t, 3H, J = 7 Hz, CH3).
Compound 23b, Anal. Calcd for C29H48N4O2 (484): C,
71.90; H, 9.91; N, 11.57. Found: C, 71.85; H, 10.09; N, 11.47.
Compound 23c, Anal. Calcd for C31H52N4O2/0.5H2O
(521): C, 71.40; H, 10.17; N, 10.34. Found: C, 71.10;
H, 10.21; N, 10.06.
5.16. 1-[4-(N-Hydroxyamidinomethyl)phenyl]-4-octade-
cylpiperazine (20c)
The same procedure as described for 16a was used to pre-
pare 20c starting from NH2OH, HCl (1.52 g, 21 mmol),
K2CO3 (3.64 g, 26 mmol) and the nitrile 10c (2 g) pre-
pared above. The crude product was purified by chroma-
tography on a silica gel column with CH2Cl2 as eluent,
and the resulting oil was crystallized from acetone to af-
ford the title amidoxime 20c (600 mg, 28%) as white crys-
tals: mp 110.1 ꢁC; IR (KBr, m cmꢀ1): 3489 (OAH), 3375
5.18. 1-[4-(4,5-Dihydro-1,2,4-[4H]-5-oxo-oxadiazol-3-ylme-
thyl)benzyl]-4-tetradecylpiperazine (24a)
1-[4-(4,5-Dihydro-1,2,4-[4H]-5-oxo-oxadiazol-3-ylmethyl)-
benzyl]-4-tetradecylpiperazine (24a) was obtained in 26%
yield as described for 23a from the amidoxime 17a (1.8 g,
4 mmol) and Et3N (0.66 mL, 4 mmol), while a mixture of
acetone and ether was used for crystallization: mp 98 ꢁC;
IR (KBr, m cmꢀ1): 1732 (NCAO), 1688 (CAN), 1599
1
(NH2), 1655 (CAN), 1607 (CACar); H NMR (CDCl3)
1
d: 7.08 and 6.80 (2d, 4H, J = 8.60 Hz, Ar H), 4.36 (s,
2H, NH2), 3.44 (s, 2H, CH2ACAN), 3.14 and 2.56 (2ls,
8H, H of piperazine), 2.34 (t, 2H, J = 7.34 Hz, CH2AN),
1.52–1.41 (m, 2H, CH2ACH2AN), 1.19 (ls, 30H, CH2),
0.81 (t, 3H, J = 7 Hz, CH3).
(C@Car); H NMR (CDCl3) d: 8–12 (ls, 1H, NH), 7.27
and 7.18 (2d, 4H, J = 8.07 and 9.12 Hz, Ar H), 3.67 (s,
2H, CH2ACAN), 3.35 (s, 2H, PhACH2AN), 2.56 and
2.34 (2m, 8H, piperazine H), 2.46 (t, 2H, J = 7.64 Hz,
CH2AN), 1.47 (m, 2H, CH2ACAN), 1.18 (ls, 22H,
CH2), 0.80 (t, 3H, J = 6.13 Hz, CH3).
5.17. 1-[4-(4,5-Dihydro-1,2,4-[4H]-5-oxo-oxadiazol-3-
yl)benzyl]-4-tetradecylpiperazine (23a)
13C NMR (CDCl3) d: 167.51 (CAO), 163.26 (CAN),
135.80 (CqarACH2ACAN), 134.39 (Cqar), 129.41
(CHar), 128.84 (CHar), 61.68 (NACH2APh), 57.79
(CH2N), 52.15 (CH2NACH2APh), 50.80 (CH2NC13),
32.40(CH2CAN), 31.89 (CH2CH2N), 29.53 (CH2),
27.21 (CH2), 25.08 (CH2), 22.66 (CH2), 14.08 (CH3).
This synthesis was carried out in two steps as described
elsewhere.24 In a 100-mL round-bottomed flask, 16a (1 g,
2.3 mmol) and Et3N (279 mg, 2.75 mmol) were dissolved
in dry CH2Cl2 (40 mL). The solution was stirred at 0 ꢁC
for 1 h and phenyl chloroformate (431 mg, 2.75 mmol)
was added. After stirring at 0 ꢁC 1 h more, the solution
was washed successively with saturated aqueous Na2CO3
and three times with water, dried over MgSO4, filtered,
and then concentrated in vacuum. The carbonate interme-
diateobtainedwas taken up inanhydrous toluene (40 mL),
and heated to reflux for 12 h. The toluene was evaporated
under reduced pressure, and the resulting residue was puri-
fied by chromatography on a silica gel column using
CH2Cl2/MeOH (98:2, v/v) as eluent and crystallization in
acetone, to produce the title compound 23a (717 mg,
26%) as white crystals: mp 118.7 ꢁC; IR (KBr, m cmꢀ1):
Anal. Calcd for C28H46N4O2 (470): C, 71.48; H, 9.78; N,
11.91. Found: C, 71.71; H, 10.06; N, 11.68.
Final compounds 24b (20%), mp 99 ꢁC, and 24c (21%), mp
101 ꢁC, were prepared by the same reaction starting from
the corresponding amidoximes 17b and 17c, respectively.
Compound 24b, Anal. Calcd for C30H50N4O2/1.5H2O
(525): C, 68.57; H, 10.09; N, 10.06. Found: C, 68.50;
H, 9.97; N, 10.00.
1
1732 (NCAO), 1688 (CAN), 1599 (C@Car); H NMR
Compound 24c, Anal. Calcd for C32H54N4O2 /0.5 H2O
(535): C, 71.77; H, 10.28; N, 10.46. Found: C, 71.45;
H, 10.16; N, 10.18.
(CDCl3) d: 8.77 (ls, 1H, NH), 7.75 and 7.26 (2d, 4H,
J = 8 Hz, Ar H), 3.51 (s, 2H, PhACH2AN), 2.9 and 2.65
(2ls, 8H, piperazine H), 2.5 (t, 2H, J = 7.64 Hz, CH2AN),
1.7–1.45(m, 2H, CH2ACH2AN), 1.18(1s, 22H, CH2), 0.80
(t, 3H, J = 6 Hz, CH3).
5.19. 1-[4-(4,5-Dihydro-1,2,4-[4H]-5-oxo-oxadiazol-3-yl)
benzoyl]-4-tetradecylpiperazine (25a)
13C NMR (CDCl3) d: 169.09 (CAO), 163.50 (CAN),
139.84 (CqarACH2ACAN), 129.39 (CHar), 126.56
(CHar), 126.31 (NCH2Cqar), 61.88 (NACH2APh),
This compound was obtained under the same conditions
as for 23a from 18a (4 g, 9 mmol). The residue was puri-
fied by chromatography on a silica gel column eluted

1252
L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
with CH2Cl2/MeOH (98:2, v/v), then crystallization in
acetone, leading to 25a (2.5 g, 59%) as white crystals:
mp 114.8 ꢁC; IR (KBr, m cmꢀ1): 1780 (OCAO), 1734
(CAN), 1640 (NCAO), 1607 (C@Car); 1H NMR
(CDCl3) d: 8–12 (most, 1H, NH), 7.16 (s, 4H, Ar H),
3.77 and 3.36 (2m, 4H, CH2ANACAO of piperazine),
Compound 26a, Anal. Calcd for C28H44N4O3 (484): C,
69.42;H,9.09;N,11.57. Found:C, 69.26;H,9.29;N,11.58.
Compound 26b, Anal. Calcd for C30H56N4O3 (508): C,
70.86; H, 11.02; N, 11.02. Found: C, 70.69; H, 11.20;
N, 10.93.
2.52 (m, 4H,
H
of piperazine), 2.35 (t, 2H,
J = 5.86 Hz, CH2AN), 1.43 (m, 2H, CH2ACH2AN),
1.18 (ls, 30H, CH2), 0.81 (t, 3H, J = 6.21 Hz, CH3).
Compound 26d, Anal. Calcd for C34H56N4O3/1H2O
(586): C, 69.62; H, 9.89; N, 9.55. Found: C, 69.44; H,
9.80; N, 9.46.
13C NMR (CDCl3) d: 169.26 (CAO), 162.88 (CAO),
158.36 (CAN), 138.17 (CHarACAN), 127.36 (CHar),
126.71 (CHar), 125.69 (COACqar), 58.37 (CH2N),
53.09 (CH2NCO), 52.55 (CH2NC13), 31.85 (CH2CH2N),
29.43 (CH2), 27.31 (CH2), 26.32 (CH2), 22.63 (CH2),
14.08 (CH3).
Compound 26e, Anal. Calcd for C36H60N4O3 (596): C,
72.48;H,10.06;N,9.39. Found:C, 72.38;H,10.21;N,9.20.
5.21. 1-[4-(4,5-Dihydro-1,2,4[4H]-5-oxo-oxadiazol-3-
ylmethyl)phenyl]-4-octadecylpiperazine (27c)
Anal. Calcd for C27H41N4O2/1H2O/1HCl (524): C, 61.83;
H, 8.58; N, 10.68. Found: C, 62.10; H, 8.64; N, 10.50.
The same procedure as described for 23a was used starting
from the amidoxime 20c (600 mg, 1.2 mmol), NEt3
(0.22 mL, 1.6 mmol), and phenyl chloroformate (0.2 mL,
1.6 mmol). The crude product was crystallized from ace-
tone to obtain the final compound 27c (210 mg, 33%) as
white crystals: mp 147.3 ꢁC; IR (KBr, m cmꢀ1): 1740
Compounds 25b (52%), mp 111.4 ꢁC, and 25c (20%), mp
113.6 ꢁC, were obtained using the same procedure from
the corresponding amidoximes 18b and 18c.
1
(OCAO), 1716 (CAN), 1607 (C@Car) cmꢀ1; H NMR
Compound 25b, Anal. Calcd for C29H46N4O3 (498): C,
69.87; H, 9.23; N, 11.24. Found: C, 70.03; H, 9.27; N,
11.06.
(CDCl3) d: 7.33 (s, 1H, NH), 7.12 and 6.74 (2d, 4H,
J = 8.62 and 8.60 Hz, Ar H), 3.71 (s, 2H, CH2ACAN),
3.14 and 2.56 (2ls, 8H, H of piperazine), 2.34 (t, 2H,
J = 7.34 Hz, CH2AN), 1.47 (m, 2H, CH2ACAN), 1.19
(ls, 30H, CH2), 0.81 (t, 3H, J = 6.05 Hz, CH3).
Compound 25c, Anal. Calcd for C31H50N4O3 (526): C,
68.38;H,9.55;N,10.29. Found:C, 68.54;H,9.40;N,10.05.
13C NMR (CDCl3) d: 163.71 (CAO), 160.53 (CAN),
134.76 (NCqar), 132.33 (Cqar), 129.32 (CHar), 127.34
(CHar), 62.52 (CH2NPh), 61.19 (CH2NC13), 58.54
(CH2N), 31.80 (PhACH2), 31.70 (CH2CH2N), 29.50–
26.39 (CH2), 27.39 (CH2), 26.42 (CH2), 22.65 (CH2),
14.06 (CH3).
5.20. 1-[40-(4,5-dihydro-1,2,4[4H]-5-oxo-oxadiazol-3-
ylmethyl)benzoyl]-4-octadecylpiper azine (26c)
The same procedure as described for 23a was followed
starting from the amidoxime 19c (1.3 g, 2.53 mmol),
NEt3 (0.45 mL, 3.28 mmol) and phenyl chloroformate
(0.4 mL, 3.03 mmol). The product was crystallized from
acetone to give 500 mg (37%) of the final compound 26c
as white crystals: mp 121 ꢁC; IR (KBr, m cmꢀ1): 1780
(OCAO), 1734 (CAN), 1640 (NCAO), 1607 (C@Car);
1H NMR (CDCl3) d: 8–12 (most, 1H, NH), 7.16 (s,
4H, Ar H), 3.79 (s, 2H, CH2ACAN), 3.77 and 3.36
(2m, 4H, CH2ANACAO of piperazine), 2.52 (m, 4H,
H of piperazine), 2.35 (t, 2H, J = 5.86 Hz, CH2AN),
1.43 (m, 2H, CH2ACAN), 1.18 (ls, 30H, CH2), 0. 81
(t, 3H, J = 6.21 Hz, CH3).
Anal. Calcd for C31H52N4O2/1H2O (530): C, 70.20; H,
10.18; N, 10.56. Found: C, 70.60; H, 10.41; N, 10.48.
Compounds 27a (42%), mp 123.4 ꢁC, and 27b (35%), mp
132.6 ꢁC, were obtained using the same procedure from
the corresponding amidoximes 20a and 20b.
Compound 27a, Anal. Calcd for C27H44N4O2 (456): C,
71.05;H,9.64;N,12.28. Found:C, 71.31;H,9.70;N,12.00.
Compound 27b, Anal. Calcd for C29H48N4O2 (484): C,
71.90;H,9.91;N,11.57. Found:C, 72.00;H,9.72;N,11.50.
13C NMR (CDCl3) d: 170.11 (CAO), 163.81 (CAO),
160.43 (CAN), 135.76 (COACqar), 133.33 (Cqar),
129.00 (CHar), 127.36 (CHar), 58.40 (CH2N), 53.19
(CH2NCO), 52.54 (CH2NC13), 31.79 (CH2CAN),
31.68 (CH2CH2N), 29.47 (CH2), 27.36 (CH2), 26.33
(CH2), 22.68 (CH2), 14.11 (CH3).
5.22. 1-[4-(4,5-Dihydro-1,2,4[4H]-5-oxo-oxadiazol-3-
ylpropyl)benzoyl]-4-tetradecylpiperazine (29a)
A mixture of 4-(3-cyanopropyl)benzoic acid 14b (2.5 g,
13.2 mmol) and 4-tetradecylpiperazine 1a (3.75 g,
13.2 mmol) in 50 mL CH2Cl2 was cooled to 0 ꢁC. Dicy-
clohexylcarbodiimide (DCC) (2.7 g, 13.2 mmol) was
added and the mixture was stirred overnight warming
to room temperature. The solution was washed with sat-
urated NaHCO3 (2· 50 mL), 10% HCl (2· 50 mL) and
water. The organic layer was then dried over MgSO4, fil-
tered, and evaporated to dryness. The resulting residue
was purified by chromatography on a silica gel column
Anal. Calcd for C32H52N4O3/1.5H2O (540): C, 69.94; H,
9.65; N, 10.20. Found: C, 70.09; H, 9.80; N, 9.90.
Final compounds 26a (41%), mp 120.7 ꢁC, 26b (35%),
mp 120.2 ꢁC, 26d (40%), mp 123.7 ꢁC, and 26e (44%),
mp 121.3 ꢁC, were prepared by the same reaction start-
ing from the corresponding amidoximes 19a, 19b, 19d,
and 19e, respectively.

L. Boukli et al. / Bioorg. Med. Chem. 16 (2008) 1242–1253
1253
8. Vadas, P. Biochim. Biophys. Acta 1997, 1346, 193.
using MeOH/CH2Cl2 (5:95, v/v) as eluent and yielded
the final compound 29a (3.95 g, 60%) as an oil: IR (film,
m cmꢀ1): 3422 (NH), 1774 (OCON), 1730 (CAN), 1613
9. Baur, M.; Schmid, O.; Landauer, B. Klin. Wochenschr.
1989, 67, 196.
10. Uhl, W.; Buchler, M.; Nevalainen, T. J.; Deller, A.; Beger,
¨
H. G. J. Trauma 1990, 30, 1285.
11. Buchler, M.; Deller, A.; Malfertheiner, P.; Kleine, H. O.;
¨
1
(C@Car); H NMR (CDCl3) d: 8.41 (ls, 1H, NH), 7.2
(d, 2H, J = 7.89 Hz, ArH), 7.05 (d, 2H, J = 7.92 Hz,
ArH), 3.73 (ls, 2H, CONCH2), 3.43 (ls, 2H, CONCH2),
2.58 (t, 2H, J = 7.2 Hz, CONCH2), 2.58 (t, 2H,
J = 7.30 Hz, CH2CAN), 2.54–2.35 (m, 8H, 2C14NCH2,
NCH2C13, CH2CH2CH2CAN), 1.89–1.82 (m, 2H,
CH2CH2CH2CAN), 1.42 (ls, 2H, NCH2CH2C12), 1.4–
1.1 (m, 22H, CH2), 0.81 (t, 3H, J = 6.76 Hz, CH3).
Uhl, W. Klein. Wochenschr. 1989, 67, 217.
12. Uhl, W.; Beger, H. G.; Hoffman, G.; Hanisch, E.; Schild, A.;
Waydhas, C.; Entholzner, E.; Muller Kellermann, W.;
Vogeser, M. J. Am. Coll. Surg. 1995, 180, 323.
13. Buchler, M.; Malfertheiner, P.; Scha¨dlich, H.; Nevalainen, T.
¨
J.; Fress, H.; Berger, H. G. Gastroenterology 1989, 97, 1521.
14. Bird, N. C.; Goodman, A. J.; Johnson, A. G. Br. J. Surg.
1989, 76, 731.
13C NMR (CDCl3) d: 170.53 (CAO), 161.17 (CAO),
159.71 (CAN), 142.84 (OCqar), 132.85 (Cqar), 128.57
(CHar), 127.01 (CHar), 58.31 (NCH2C13), 52 (NCH2),
48 (NCH2), 34.4 (CH2), 31.75 (CH2CAN), 29.50–26.39
(CH2), 22.41 (CH2), 22.52 (CH2), 13.97 (CH3).
15. Kortesuo, P. T.; Nevalainen, T. J.; Buchler, M.; Uhl, W.
¨
Eur. J. Clin. Chem. Clin. Biochem. 1992, 30, 263.
16. Marks, F.; Muller-Decker, K.; Furstenberger, G. Toxi-
cology 2000, 153, 11.
17. Tapiero, H.; Ba, G. N.; Couvreur, P.; Tew, K. D. Biomed.
Pharmacother. 2002, 56, 215.
Anal. Calcd for C30H48N4O3/0.25 AcOEt (534): C, 69.66;
H, 9.36; N, 10.48. Found: C, 69.33; H, 9.43; N, 10.54.
18. Uhl, W.; Schrag, H.; Schmitter, J. N.; Aufenanger, J. Br.
J. Surg. 1998, 85, 618.
19. Binisti, C.; Assogba, L.; Touboul, E.; Mounier, C.; Huet, J.;
Ombetta, J. E.; Dong, C.-Z.; Redeuilh, C.; Heymans, F.;
Godfroid, J.-J. Eur. J. Med. Chem. 2001, 36, 809.
20. Dillard, R. D.; Bach, N. J.; Draheim, S. E.; Berry, D. M.;
Carlson, D. G.; Chirgadze, N. Y.; Clawson, D. K.;
Hartley, L. W.; Johnson, L. M.; Jones, N. D.; McKinney,
E. R.; Mihelich, E. D.; Olkowski, J. L.; Schevitz, R. W.;
Smith, A. C.; Snyder, D. W.; Sommers, C.; Wery, J.-P. J.
Med. Chem. 1996, 39, 5137.
5.23. 1-[4-(4,5-Dihydro-1,2,4[4H]-5-oxo-oxadiazol-3-
ylethyl)benzoyl]-4-tetradecylpiperazine (28a)
Compound 28a was obtained as a yellow powder in 60%
yield following the same procedure as used for the syn-
thesis of 29a from the corresponding cyanoacid 14a. Mp
97 ꢁC; IR (KBr, m cmꢀ1): 1700 (CAO), 2252 (CN); H
1
NMR (CDCl3) d 9.33 (ls, 1H, NH), 7.2 (d, 2H,
J = 8 Hz, ArH), 7.01 (d, 2H, J = 8.03 Hz, ArH), 3.75
(ls, 2H, CONCH2), 3.39 (ls, 2H, CONCH2) 2.82 (t,
2H, J = 8.2 Hz, CH2CAN), 2.54 (t, 2H, J = 7.19 Hz,
CH2CH2CAN), 2.36–2.28 (m, 6H, 2C14NCH2,
NCH2C13), 1.42 ( ls, 2H, NCH2CH2C12), 1.3–1.1 (m,
22H, CH2), 0.81 (t, 3H, J = 6.76 Hz, CH3).
21. Dillard, R. D.; Bach, N. J.; Draheim, S. E.; Berry, D. M.;
Carlson, D. G.; Chirgadze, N. Y.; Clawson, D. K.;
Hartley, L. W.; Johnson, L. M.; Jones, N. D.; McKinney,
E. R.; Mihelich, E. D.; Olkowski, J. L.; Schevitz, R. W.;
Smith, A. C.; Snyder, D. W.; Sommers, C.; Wery, J.-P. J.
Med. Chem. 1996, 39, 5119.
22. Maguire, A. R.; Plunkett, S. J.; Papot, S.; Clynes, M.;
O’Connor, R.; Touley, S. Bioorg. Med. Chem. 2001, 9, 745.
23. Glaser, K. B. Adv. Pharmacol. 1995, 32, 31.
24. Assogba, L.; Ahamada-Himidi, A.; Meddad-Bel Habich, N.;
Aoun, D.; Boukli, L.; Massicot, F.; Mounier, C.; Huet, J.;
Lamouri, A.; Ombetta, J.-E.; Godfroid, J.-J.; Dong, C.-Z.;
Heymans, F. Eur. J. Med. Chem. 2005, 40, 850.
13C NMR (CDCl3) d 170.41 (CAO), 160.81 (CAO),
158.9 (CAN), 141.54 (OCqar), 133.42 (Cqar), 128.55
(CHar), 127.1 (CHar), 58.36 (NCH2C13), 53 (NCH2),
50 (NCH2), 31.81 (CH2), 31.06 (CH2CAN), 29.56–
26.52 (CH2), 22.58 (CH2), 14.02 (CH3).
25. Dong, C.-Z.; Ahamada-Himidi, A.; Plocki, S.; Aoun, D.;
Touaibia, M.; Meddad-Bel Habich, N.; Huet, J.; Rede-
uilh, C.; Ombetta, J.-E.; Godfroid, J.-J.; Massicot, F.;
Heymans, F. Bioorg. Med. Chem. 2005, 13, 1989.
Anal. Calcd for C29H46N4O3/0.25 AcOEt (520): C, 69.13;
H, 9.22; N, 11.06. Found: C, 69.30; H, 9.52; N, 11.06.
`
26. Plocki, S.; Aoun, D.; Ahamada-Himidi, A.; Tavares-Camar-
inha, F.; Dong, C.-Z.; Massicot, F.; Huet, J.; Adolphe-Pierre,
S.; Chau, F.; Godfroid, J.-J.; Gresh, N.; Ombetta, J.-E.;
Heymans, F. Eur. J. Org. Chem. 2005, 2747.
Acknowledgments
27. Jerzy, R.; Pietraseiwick, M.; Duszynska, B.; Cegla, M. T.
J. Med. Chem. 1992, 35, 2369.
We acknowledge Stephanie Huet, Laurence Bisiaux, and
Catherine Redeuilh for their technical contribution.
28. Newman, A. H.; Kline, R. H.; Allen, A. C.; Izenwasser, S.;
Clifford, G.; Katz, J. L. J. Med. Chem. 1995, 38, 3933.
29. Brouard, C; Dupont, B.; Leroy, J. M.; Sito, J. P. Ger.
Offen. 1975, Deutsches Patent No. GWXXBX DE,
243809, 19750220.
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