Synthesis and evaluation of new hydrazide derivatives as neuropeptide Y Y5 receptor antagonists for the treatment of obesity

Article abstract of DOI:10.1016/j.bmc.2004.06.023

NPY is the most potent orexigenic agent known to man, with NPY Y1 and NPY Y5 being the receptor subtypes that are most likely responsible for centrally-mediated NPY-induced feeding responses. Based on the aforementioned, novel hydrazide derivatives were prepared for the purpose of searching new NPY Y5 receptor antagonists. Many of the compounds exhibited nanomolar binding affinity for this receptor, affording trans-N-{4-[N′-(3,4-dichlorophenyl) hydrazinocarbonyl]cyclohexylmethyl}-4-fluorobenzenesulfonamide, which showed the best activity (IC₅₀=0.43 nM). NPY is the most potent orexigenic agent known to man, with NPY Y1 and NPY Y5 being the receptor subtypes that are most likely responsible for centrally-mediated NPY-induced feeding responses. Based on the aforementioned, novel hydrazide derivatives were prepared for the purpose of searching new NPY Y5 receptor antagonists. Many of the compounds exhibited nanomolar binding affinity for this receptor, affording trans-N-{4-[N′-(3,4-dichlorophenyl)hydrazinocarbonyl]cyclohexylmethyl} -4-fluorobenzenesulfonamide, which showed the best activity (IC ₅₀=0.43 nM).

Full text of DOI:10.1016/j.bmc.2004.06.023

Bioorganic & Medicinal Chemistry 12 (2004) 4717–4723
Synthesis and evaluation of new hydrazide derivatives as
neuropeptide Y Y5 receptor antagonists for the treatment of obesity
´
Laura Juanenea, Silvia Galiano, Oihana Erviti, Antonio Moreno, Silvia Perez,
Ignacio Aldana* and Antonio Monge
´ ´ ´
Unidad en Investigacion y Desarrollo de Medicamentos, Centro de Investigacion en Farmacobiologıa Aplicada (CIFA),
Universidad de Navarra, c/Irunlarrea s/n, 31080 Pamplona, Spain
Received 12 December 2003; accepted 14 June 2004
Abstract—NPY is the most potent orexigenic agent known to man, with NPY Y1 and NPY Y5 being the receptor subtypes that are
most likely responsible for centrally-mediated NPY-induced feeding responses. Based on the aforementioned, novel hydrazide deriv-
atives were prepared for the purpose of searching new NPY Y5 receptor antagonists. Many of the compounds exhibited nanomolar
binding affinity for this receptor, affording trans-N-{4-[N0-(3,4-dichlorophenyl)hydrazinocarbonyl]cyclohexylmethyl}-4-fluorobenz-
enesulfonamide, which showed the best activity (IC50=0.43nM).
ꢀ 2004 Published by Elsevier Ltd.
1. Introduction
ionic sympathetic neurons, adrenal medulla, enteric neu-
rons, cardiac nonsympathetic neurons, certain
nonadrenergic perivascular neurons and parasympath-
etic neurons. In sympathetic neurons and adrenal
medulla, the peptide is colocalized with the classical
sympathetic neurotransmitter noradrenaline. In the
brain, neuropeptide Y-containing neuronal cell bodies
are found primarily in the locus coeruleus, the nucleus
of the solitary tract and the arcuate nucleus of the hypo-
thalamus. In addition, these neuropeptide Y-containing
neuronal cell bodies often contain other neurotransmit-
ters, such as noradrenaline, and send projections
throughout the brain; hence, neuropeptide Y can be
found in most brain regions, particularly in the cortex,
hippocampus, thalamus, hypothalamus and brainstem.
The physiological effects of NPY are mediated by a ser-
ies of NPY receptor subtypes (Y1, Y2, Y4, Y5 and Y6)
that are members of the G-protein coupled receptor
(GPCR) family. It is assumed that NPY regulates a vari-
ety of physiological processes, including vasoconstric-
tion, nasal congestion, blood pressure, intestinal
motility, anxiety, depression, pain, feeding, reproductive
endocrinology, neuronal excitability and memory reten-
tion. For this reason it is though that NPY receptor-spe-
cific ligands may ultimately have value in several
therapeutic areas including the treatment of obesity.4,5
The receptor most likely subypes responsible for cen-
trally-mediated NPY-induced feeding responses are
Obesity is now a major health problem in advanced na-
tions and even mild obesity enhances the risk of
premature death, hypertension, diabetes mellitus, hyper-
lipidaemia, atherosclerosis, coronary heart disease,
arthritis, sleep apnea and certain types of cancer.1 The
exact aetiology of obesity still remains unclear although
it appears to be caused mainly by a combination of ge-
netic factors, inappropriate eating, and reduced activ-
ity.2
Neuropeptide Y (NPY), a 36 amino acid peptide was
first isolated and sequenced from porcine brain by Tate-
moto et al. in 1982 and belongs to a family of structur-
ally related peptides that includes pancreatid
polypeptide (PP) and peptide YY (PYY).3
This peptide is one of the most potent feeding stimulat-
ing hormones known that can be found in both the
peripheral and central nervous system. In the peripheral
nervous system, neuropeptide Y is located in postgangl-
Keywords: Obesity; NPY; Y5 receptor antagonists; Hydrazide; Food
intake.
*
Corresponding author. Tel.: +34-948-425653; fax: +34-948-
425652; e-mail: ialdana@unav.es
0968-0896/$ - see front matter ꢀ 2004 Published by Elsevier Ltd.
doi:10.1016/j.bmc.2004.06.023

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L. Juanenea et al. / Bioorg. Med. Chem. 12 (2004) 4717–4723
O
O
S
N
H
N
H
N
N
O
CGP 71683A
NH2
O
O
O
F
S
S
N
H
H
N
N
H
N
H
1
2
N
O
O
NH2
H
N
S
N
H
F
OH
3
O
O
O
S
O
N
H
H
O
O
H
N
H
N
OH
S
N
N
H
O
H
4
5
Figure 1. Antecedents.
NPY Y1 and NPY Y5. Antagonists at the NPY Y5
receptor have been shown to be effective in reducing
food intake in various animal models of feeding.6,7
1), which consisted of a nucleophilic attack of amines
6 that was carried out against sulfonyl chlorides 7,12 fol-
lowed by a subsequent acylation of the different hydra-
zine 9 derivatives previous activation of the carboxylic
group with carbodiimide 1-ethyl-3-(3Õ-dimethylamino-
propyl)carbodiimide HCl (EDC).13
Recently, it has been reported that there are many di-
verse structural types (Fig. 1), which antagonize the
NYP Y5 receptor and are considered potential antiobes-
ity agents due to their notable in vitro activity. Com-
pounds such as CGP71683A, Synaptic PharmÕs tetralin
derivative 1, a-substituted-b-aminotetralin derivative 2,
3, 4 and 5 compounds antagonize the Y5 receptor and
are reported to be effective in reducing food intake in
ob/ob mice and Zucker obese rat models.6,8–10
The structures and biological evaluation results of
the different hydrazide derivative compounds in terms
of potency as Y5 receptor antagonists are shown in
Table 2.
All of the compounds were chemically characterized by
thin layer chromatography (TLC), melting point, infra-
red, nuclear magnetic resonance (1H NMR), elemental
microanalysis and HPLC.
Consequently, we attempted to discover a novel com-
pound that possesses antagonist activity on the Y5 re-
ceptor. This led us to synthesize new hydrazide
derivatives, all of which have
a common aryl-
sulfonamidomethylcyclohexyl nucleus, due to the fact
that the sulfonamide group and the cyclohexyl linker
were found to be essential in the concession of biological
activity.11
3. Pharmacology
Binding assays for both receptors, NPY Y1 and NPY
Y5, were carried out as described by Duhault et al.14
In brief, for the human Y1 receptor binding assay, using
iodinated Peptide YY (NEN), incubations were per-
formed at 30ꢁC for 90min with various competitor con-
centrations in Buffer A (Hepes/NaOH 20mM, pH7.4,
NaCl 10mM, KH2PO4 220lM, CaCl2 1.26mM, MgSO4
0.81mM and bovine serum albumin 0.1%) with SK-N-
MC cell membranes (50lg of protein/mL of assay) in
a total volume of 500lL. Nonspecific binding was deter-
mined in the presence of 1lM NPY. The reaction was
2. Chemistry
The aforementioned compounds were prepared accord-
ing to the synthetic route illustrated in Scheme 1.
Hydrazide derivatives 10–81 were obtained by the for-
mation reaction of the primary sulfonamides 8 (Table

L. Juanenea et al. / Bioorg. Med. Chem. 12 (2004) 4717–4723
4719
H2N
O
O
OH
i. NaOH 2M
ii. HCl (c)
S
O
O
6
N
H
R1
OH
O
8(a-p)
O
S
R1
Cl
7
CH2Cl2
i.EDC
ii.R2-NH-NH2
9
O
O
S
N
H
R1
H
N
R2
N
H
O
10-81
Scheme 1. Synthetic route.
then stopped by filtration. The filters (GF/B, Whatman,
precoated in 0.3% PEI) were washed thoroughly with
buffer A and then counted in a gamma counter (Pack-
ard). The human Y5 receptor binding assay was carried
out with iodinated peptide YY (NEN) as follows: COS
cells transfected with the human Y5 NPY receptor were
lysed and the membranes were prepared by differential
centrifugation. These membranes contained about
2pmol per mg of protein of this receptor. Incubations
were performed in a solution of 500lL comprising,
20pM final of [125I]PYY in 50lL, 400lL of membrane
suspension (0.15mg/mL) and competitor dilutions in
50lL, at 30ꢁC for 2h. The reaction was stopped by fil-
tration using GF/C filters (Whatman). The results in
both assays are expressed in IC50.
In general, when R1 was not a halogenated phenyl
group, the compounds were found to be less potent
NPY ligands than the halogenated ones, with IC50 val-
ues >80nM for all of them. In the same way, the in-
crease of volume and rigidness of the molecule with
naphthyl groups as R1 (compounds 72 and 73) led to
a decrease in potency.
In particular, the best affinity was found when R1 was
2-fluorophenyl or 4-fluorophenyl (compounds 46 and
65).
Nevertheless, the increase of volume of R1 due to the di-
substitution with chloro in the benzene ring improved
affinity for the NPY Y5 receptor as shown for com-
pounds 33 and 35, with IC50 values of 37.0 and
2.79nM, respectively.
4. Results and discussion
Variations were also made to R2. Nonsubstituted phen-
yl as R2 led us to hydrazide derivatives with very low
affinity for the NPY Y5 receptor, as observed for 23,
57 and 79, among others.
Seventy-two new hydrazide derivative compounds have
been synthesized and their affinities for the NPY Y1
and Y5 receptors have been evaluated in vitro. The com-
pounds presented showed no antagonist activity on the
Y1 receptor because their IC50 values are greater than
105 nM. Several of the compounds reported here show
high affinity for the human neuropeptide Y5 receptor.
Common to this set of structures are two hydrophobic
aromatic groups that are connected via the sul-
fonamidomethylcyclohexylhydrazide nucleus. The sul-
fonamide group and the cyclohexyl linker are known
to be essential in the concession of biological activity.
Substitution at the para-position of the arylhydrazide
moiety with electron-withdrawing groups, such as 4-
chloro and 4-bromo, led to a better affinity for the
Y5 receptor than the substitution at the ortho- or
meta-position with the same groups. Curiously, this
behaviour was not observed when the substituent was
4-fluoro.
Direct comparison between mono- and disubstitution
revealed an increase of activity in almost all of the cases
when R2 was a disubstituted phenyl group.
A structure–activity relationship study was carried
out introducing different aromatic groups, such as R1
and R2.
The most potent compounds among those we prepared
were those with the 3,4-dichlorophenyl, 2,4-dichloro-
phenyl or 2,3,4,5,6-pentafluorophenyl groups as R2.
Compounds 46 and 65 have the best affinity for the
NPY Y5 receptor, with 0.68 and 0.43nM IC50 values,
respectively, with both of them containing 3,4-dichloro-
phenyl as the R2 group.
5. Conclusion
This publication shows new hydrazide derivatives as
antagonist compounds of the NPY Y5 receptor, charac-
terized by their selectivity on the Y5 receptor due to their
nonaffinity on the receptor Y1.

4720
L. Juanenea et al. / Bioorg. Med. Chem. 12 (2004) 4717–4723
Table 1. Sulfonamide compounds
6. Experimental protocols
O
O
6.1. General
S
N
R1
H
Melting points were determined using a Mettler
FP82+FP80 apparatus (Greifense, Switzerland) and
OH
1
have not been corrected. The H NMR spectra were re-
O
corded on a Bruker AC-200E/AC-400E instrument
(Rheinstetten, Germany), using TMS as the internal
standard and with DMSO-d6 as the solvent; the chemi-
cal shifts are reported in parts per miilion (d) and cou-
pling constants (J) values are given in hertz (Hz).
Signal multiplicities are represented by: s (singlet), d
(doublet), t (triplet), m (multiplet), ds (double singlet),
dd (double doublet) and dt (double triplet). The IR spec-
tra were performed on a Perkin–Elmer 1600 FTIR (Nor-
walk, CT, USA) in KBr pellets; the frequencies are
expressed in cmꢀ1. Signal intensities are expressed by:
s (strong), m (medium) and w (weak). Elemental micro-
analyses were obtained on an Elemental Analyzer (Carlo
Erba 1106, Milan, Italy) from vacuum-dried samples.
The analytical results for C, H and N, were within
0.4 of the theoretical values.
Compd
R1
8a
Br
8b
8c
8d
Br
Cl
8e
8f
Cl
Cl
Alugramꢂ SIL G/UV254 (layer: 0.2mm) (Macherey-
Nagel GmbH & Co. KG. Postfach 101352. D-52313
Duren, Germany) was used for thin layer chromatogra-
¨
phy and Silica gel 60 (0.040–0.063mm) was used for
column chromatography (Merck). HPLC conditions:
Column Nova Pack C18 60 A 4lm (3.9·150mm); mo-
bile phase: methanol/water 60/40; flow: 1mL/min.
Cl
Cl
8g
8h
Cl
F
Chemicals were purchased from E. Merck (Darmstadt,
Germany), Scharlau (F.E.R.O.S.A., Barcelona, Spain),
Panreac Qu´ımica S.A. (Montcada i Reixac, Barcelona,
Spain), Sigma–Aldrich Qu´ımica, S.A., (Alcobendas,
Madrid), Acros Organics (Janssen Pharmaceuticalaan
3a, 2440 Geel, Belgie¨) and Lancaster (Bischheim-Stras-
bourg, France).
8i
8j
F
I
8k
8l
6.1.1. General procedure for the synthesis of trans-4-(R-
sulfonylaminomethyl)cyclohexanecarboxylic acid (8). A
solution of R-Sulfonyl chloride 7 (1.5equiv) in a mini-
mum amount of CHCl3 was added, alternately and
portionwise, to a solution of trans-4-(aminomethyl)-
cyclohexanecarboxylic acid 6 (1equiv) in NaOH 2M
(150mL), with stirring for 30min. After the addition,
the mixture was stirred at room temperature for 72h.
The aqueous layer was acidified with HCl(c) to pH1–
2. The residue obtained was filtered and washed with
H2O (5·20mL) and n-hexane (5·20mL) in order to ob-
tain sulfonamides 8. When necessary, the compounds
were purified by recrystallization using the appropriate
solvent.
NO2
8m
8n
8o
O2N
H3C
H3C
8p
6.1.2. Synthesis of trans-4-(benzenesulfonylaminometh-
yl)cyclohexanecarboxylic acid (8a). From benzenes-
ulfonyl chloride (6.11mL, 47.70mmol), in order to
obtain the compound as a white solid (3.46g, 24%);
mp 160–162ꢁC. IR (KBr): m 3289 (s, NH); 2929 (m, ali-
phatic C–H); 1698 (vs, hydrazide C@O); 1326 and 1162
CH3
Several compounds showed potent antagonistic activity
for human NPY Y5 receptors, some of which nano-
molar binding affinities. Nevertheless, we are continuing
our search for more improved compounds.
1
(vs, SO2–N). H NMR (DMSO-d6, 400MHz): d 0.73–
0.90 (m, 2H, Ha of CH–CH2–CH2–CH–CO); 1.09–1.27

L. Juanenea et al. / Bioorg. Med. Chem. 12 (2004) 4717–4723
4721
Table 2. IC50 (NPY5) results of the hydrazide derivatives
Table 2 (continued)
Cl
O
O
––
25
S
Cl
F
N
R1
H
H
N
R2
N
H
Cl
26
76.2
O
Compd
R1
R2
IC50 (nM)
1360
10
27
1020
––
Cl
Cl
Br
11
751
28
Cl
Br
Br
29
29.0
12
13
80.5
126
Cl
Cl
Br
30
188
315
Cl
Cl
31
Br
Br
Cl
Cl
14
15
35.9
11.0
Cl
32
––
Cl
Cl
33
37.0
Cl
F
Cl
Br
Br
16
17
18
19
20
21
35.3
8520
523
Cl
F
34
––
Cl
Cl
Cl
35
2.79
Cl
F
Cl
Br
36
10.7
55.9
Cl
21.3
483
Br
Br
Br
Br
Br
Cl
37
Cl
Br
F
Cl
Cl
38
251
Cl
32.7
Cl
F
F
Br
39
150
22
23
––
F
Br
Br
Cl
40
21.4
3250
F
Cl
Cl
41
7.64
24
33.0
(continued on next page)

4722
L. Juanenea et al. / Bioorg. Med. Chem. 12 (2004) 4717–4723
Table 2 (continued)
Table 2 (continued)
Br
Br
F
Cl
59
40.1
17.0
42
76.3
F
60
F
F
Cl
43
38.7
Cl
61
429
F
F
44
13.3
Cl
62
F
Cl
Cl
236
179
Cl
F
45
3.79
Cl
Cl
63
64
65
66
67
68
69
70
71
72
73
74
75
76
F
F
F
F
F
F
F
F
I
F
Cl
46
0.681
1.03
Cl
Cl
Cl
Cl
F
47
57.9
0.431
Cl
Cl
Cl
F
Cl
48
954
54.4
Cl
Cl
Cl
F
Cl
F
49
>105
427
105
235
220
345
Cl
F
50
F
83.9
Cl
Cl
F
F
51
1400
F
F
F
F
F
F
52
6.52
F
F
F
53
405
423
F
F
F
F
F
F
54
58.0
F
F
55
54.4
1450
1350
109
F
F
F
F
F
F
NO2
NO2
NO2
56
3.62
F
Cl
57
2150
F
Br
38.7
58
230
F
Cl

L. Juanenea et al. / Bioorg. Med. Chem. 12 (2004) 4717–4723
4723
Table 2 (continued)
1.75 (t, 4H, He of CH–CH2–CH2–CH–CO); 2.13 (t,
1H, CH–CH2–CH2–CH–CO); 2.59 (t, 2H, SO2–NH–
CH2); 6.63 (dd, 1H, H6 of C6H3Cl2, J6–5=8.8Hz, J6–
2=2.5Hz); 6.78 (ds, 1H, H2 of C6H3Cl2, J2ꢀ6=2.5Hz);
7.33 (d, 1H, H5 of C6H3Cl2, J5–6=8.8Hz); 7.44 (t, 2H,
H3 and H5 of C6H4F); 7.66 (s, 1H, CO–NH–NH–
C6H3Cl2); 7.85 (dd, 2H, H2 and H6 of C6H4F, J2–
3=6.8Hz, J2–6=3.1Hz); 8.11 (s, 1H, SO2–NH); 9.68
77
1050
696
O2N
78
O2N
Cl
(s,
1H,
CO–NH–NH–C6H3Cl2)
ppm.
Anal.
C20H22Cl2FN3O3S (C, H, N); C (%): calcd: 50.64;
found: 50.41. H (%): calcd: 4.64; found: 4.52. N (%): cal-
cd: 8.86; found: 9.13 (27% yield).
79
4760
712
H3C
80
H3C
F
Acknowledgements
This group of authors wishes to thank the Gobierno de
Navarra for the grant given to Laura Juanenea.
81
108
Cl
Supplementary material
Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/
j.bmc.2004.06.023.
(m, 3H, Ha of CH–CH2–CH2–CH–CO); 1.69 (d, 4H, He
of CH–CH2–CH2–CH–CO); 1.84 (d, 2H, He of CH–
CH2–CH2–CH–CO); 2.07 (t, 1H, CH–CH2–CH2–CH–
CO); 2.56 (t, 2H, SO2–NH–CH2); 7.59 (br s, 4H, H3,
H4 and H5 of C6H5 and SO2–NH); 7.78 (d, 2H, H2
and H6 of C6H5, J2–3=6.6Hz); 12.00 (s, 1H, COOH)
ppm. Anal. C20H22Cl2FN3O3S (C, H, N); C (%): calcd:
50.64; found: 50.41. H (%): calcd: 4.64; found: 4.52. N
(%): calcd: 8.86; found: 9.13 (24% yield).
References and notes
1. Itani, H.; Ito, H.; Sakata, Y.; Hatakeyama, Y.; Oohashi,
H.; Satoh, Y. Bioorg. Med. Chem. Lett. 2002, 12, 757.
2. Farriol, M.; Nogues, R.; Benarroch, G. Nutr. Hosp. 2001,
XVI(4), 113.
3. Haynes, A. C.; Arch, J. R. S.; Wilson, S.; McClue, S.;
Buckingham, R. E. Regul. Pept. 1998, 75–76, 355.
4. Parker, E.; Van Heek, M.; Stamford, A. Eur. J. Pharma-
col. 2002, 440, 173.
5. Finn, J.; Pelham, D.; Walker, M. W.; Gluchowski, C.
Bioorg. Med. Chem. Lett. 2002, 12, 1771.
6. Kordik, C. P.; Luo, C.; Zanoni, B. C.; Dax, S. L.;
McNally, J. J.; Lovenberg, T. W.; Wilson, S. J.; Reitz, A.
B. Bioorg. Med. Chem. Lett. 2001, 11, 2283.
7. Silva, A. P. et al. Clin. Chim. Acta 2002, 326, 3.
8. Tabuchi, S.; Itani, H.; Sakata, Y.; Oohashi, H.; Satoh, Y.
Bioorg. Med. Chem. Lett. 2002, 12, 1171.
9. Rueger, H.; Schmidlin, T.; Rigollier, P.; Yamaguchi, Y.;
Tintelnot-Blomley, M.; Schilling, W; Criscione, L.; Mah,
R.; PCT WO 97/20823, Novartis AG, 1997.
10. Hofbauer, K. G.; Schaffhauser, A. O.; Batel-Hartmann,
C.; Stricker-Krongrad, A.; Whitebread, S.; Cumin, F.;
Rigollier, P.; Yamaguchi, Y.; Chiesi, M.; Levens, N.;
Schilling, W.; Walker, M.; Gerald, C.; Rueger, H.;
Criscione, L. Regul. Pept. 1997, 71, 211.
11. Islam, I.; Dhanoa, D.; Finn, J.; Du, P.; Walker, M. W.;
Salon, J. A.; Zhang, J.; Gluchowski, C. Bioorg. Med.
Chem. Lett. 2002, 12, 1767.
12. MarchÕs Advanced Chemistry; Smith, M. B., March, J.,
Eds.; 5th ed.; Wiley–Interscience: New York, 2001, pp
574.
6.1.3. General procedure for the synthesis of trans-N-{4-
[N0-(R1-yl)hydrazinocarbonyl]cyclohexylmethyl}-R-sul-
fonamide (10–81). trans-4-(R-Sulfonylaminomethyl)cy-
clohexanecarboxylic acid 8 (1equiv) in dry CH2Cl2
(150mL) at 0ꢁC, under N2 atmosphere, was treated with
EDC (1.13equiv). After 1h at 0ꢁC, the corresponding
hydrazine 9 (1.13equiv) was added. The reaction was
stirred at room temperature for 24h. The solvent was
evaporated in vacuo and the residue was taken up with
H2O (20mL) and diethyl ether (5mL). The precipitate
obtained was filtered and washed with H2O (5·20mL)
and diethyl ether (1·10mL) in order to obtain com-
pounds 10–81. When necessary, the compounds were
purified by recrystallization using MeOH/H2O or by col-
umn chromatography (CH2Cl2 to CH2Cl2/MeOH).
6.1.4. Synthesis of trans-N-{4-[N0-(3,4-dichlorophenyl)hy-
drazinocarbonyl]cyclohexylmethyl}-4-fluorobenzenesul-
fonamide (65). From trans-4-(4-fluorosulfonylamino-
methyl)cyclohexanecarboxylic acid (3.17mmol, 1.00g),
EDC (3.59mmol, 0.69g), 3,4-dichlorophenylhydrazine
hydrochloride (3.59mmol, 0.76g) and triethylamine
(3.59mmol, 0.36g) in order to obtain 65 as a white solid
(0.40g, 27%); mp 223–225ꢁC. IR (KBr): m 3251 (s, NH);
2937 (m, aliphatic C–H); 1655 (vs, hydrazide C@O);
1322 and 1153 (vs, SO2–N). 1H NMR (DMSO-d6,
400MHz): d 0.81–0.90 (m, 2H, Ha of CH–CH2–CH2–
CH–CO); 1.32 (t, 3H, Ha of CH–CH2–CH2–CH–CO);
13. Rebek, J.; Feitler, D. J. Am. Chem. Soc. 1973, 95, 4052.
14. Duhault, J.; Boulanger, M.; Chamorro, S.; Boutin, J. A.;
Della Zuana, O.; Douillet, E.; Fauchere, J. L.; Feletou,
M.; Germain, M.; Husson, B.; Renard, P.; Tisserand, F.
Can. J. Biochem. Physiol. 2000, 78, 173.