Progresses in the pursuit of aldose reductase inhibitors: The structure-based lead optimization step

Article abstract of DOI:10.1016/j.ejmech.2012.02.045

Aldose reductase (ALR2) is a crucial enzyme in the development of the major complications of diabetes mellitus. Very recently it has been demonstrated that the ARL2 inhibitor, fidarestat, significantly prevents inflammatory signals (TNF-α, LPS) that cause cancer (colon, breast, prostate and lung), metastasis, asthma, and other inflammatory diseases. Currently, fidarestat is in phase III clinical trial for diabetic neuropathy and was found to be safe. Thus the finding of novel, potent ARL2 inhibitors is today more than in the past in great demand as they can pave the way for a novel therapeutic approach for a number of diseases besides the diabetes. Herein, starting from the virtual screening-derived ALR2 inhibitor S12728 (1), a rational receptor-based lead optimization has been undertaken. The design and synthetic efforts here reported led to the discovery of several new compounds endowed with low micromolar/submicromolar activities.

Full text of DOI:10.1016/j.ejmech.2012.02.045

European Journal of Medicinal Chemistry 51 (2012) 216e226
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Progresses in the pursuit of aldose reductase inhibitors: The structure-based lead
optimization step
Anna Ramunno b, Sandro Cosconati d, Stefania Sartini c, Vita Maglio b, Sara Angiuoli b, Valeria La Pietra a,
Salvatore Di Maro a, Mariateresa Giustiniano a, Concettina La Motta c, Federico Da Settimo c,
,
a
Luciana Marinelli a , Ettore Novellino
*
a Dipartimento di Chimica Farmaceutica e Tossicologica, Università di Napoli, “Federico II” Via D. Montesano 49, 80131 Napoli, Italy
b Dipartimento di Scienze Farmaceutiche, Università di Salerno, Via Ponte Don Melillo 11c, 84084 Fisciano, Italy
c Dipartimento di Scienze Farmaceutiche, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy
d Dipartimento di Scienze Ambientali, Seconda Università di Napoli, Via Vivaldi 43, 81100 Caserta, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
Aldose reductase (ALR2) is a crucial enzyme in the development of the major complications of diabetes
Received 27 June 2011
Received in revised form
20 February 2012
Accepted 21 February 2012
Available online 5 March 2012
mellitus. Very recently it has been demonstrated that the ARL2 inhibitor, fidarestat, significantly prevents
inflammatory signals (TNF-a, LPS) that cause cancer (colon, breast, prostate and lung), metastasis,
asthma, and other inflammatory diseases. Currently, fidarestat is in phase III clinical trial for diabetic
neuropathy and was found to be safe. Thus the finding of novel, potent ARL2 inhibitors is today more
than in the past in great demand as they can pave the way for a novel therapeutic approach for a number
of diseases besides the diabetes. Herein, starting from the virtual screening-derived ALR2 inhibitor
S12728 (1), a rational receptor-based lead optimization has been undertaken. The design and synthetic
efforts here reported led to the discovery of several new compounds endowed with low micromolar/
submicromolar activities.
Keywords:
Aldose reductase
Inflammation
Diabetes
Ó 2012 Elsevier Masson SAS. All rights reserved.
Docking
Enzyme
1. Introduction
complications and downstream effects of osmotic and oxidative
stress resulting from polyol pathway hyperactivation inhypergli-
Diabetes mellitus, alone or in combination with other metabolic
disorders as obesity and/or hypercholesterolemia, is recognized as
one of the major health problems worldwide in terms of socio-
economic impact [1,2]. Despite different therapeutic options to
reduce hyperglycemia (eginsulines, oral hypoglycemics) it is often
difficult to achieve a normoglycemic status even in patients with
a careful control of their glucose levels. As a consequence, both
micro- and macrovascular alterations can occur and may increase
the risk of diabetes-specific long-term complications as blindness,
cardiovascular and chronic renal diseases, peripheral vascular
diseases with gangrene of lower limbs, as well as debilitating
neuropathies. Of particular interest is neuropathy, the most
common complication seen in the ambulatory care setting in
patients with type 2 diabetes mellitus [3].
cemic conditions [4,5].
The first and rate-limiting enzyme of this pathway is aldose
reductase (ARL2), a member of the aldo-ketoreductase superfamily
[6]. Under normoglycemic conditions this enzyme exerts beneficial
effects by acting as an extra hepatic detoxifying enzyme in various
tissues. Actually, ALR2 has been shown to be involved in the
reduction of a variety of reactive aldhehydes deriving from in vivo
lipid peroxidation, as well as from some xenobiotics [7]. Never-
theless, in hyperglycemic conditions, ARL2 catalyzes an NADPH-
dependent reduction of glucose to sorbitol, which in turn is
oxidized to fructose by an NADþ-dependent sorbitol dehydroge-
nase. Intracellular accumulation of sorbitol creates a loss of osmotic
integrity and cellular damage, while depletion of NADPH and NADþ
cofactors compromises body’s antioxidant defence systems. In
addition, high blood levels of fructose may account for increased
glycation and accelerating aging [8,9].
Although the exact mechanisms of these injuries are unknown,
several evidences suggest a correlation between diabetes-related
Notably, it has been recently found that inhibition of aldose
reductase significantly prevented the inflammatory signals induced
by cytokines, growth factors, endotoxins, high glucose, allergens
and auto-immune reactions in cellular as well as animal models
* Corresponding author. Fax: þ39 081 678619.
E-mail address: lmarinel@unina.it (L. Marinelli).
0223-5234/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2012.02.045

A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
217
[10]. Very recently it has been demonstrated that the ALR2 inhib-
itor, fidarestat, significantly prevents tumor necrosis factor-alpha
(TNF-a), growth factors, lipopolysaccharide (LPS), and environ-
In this respect, our research group has recently undertaken
a virtual screening (VS) campaign by integrating a receptor-based
approach with a ligand-based one in order to discover new che-
motypes able to inhibit ALR2 [14]. Such a strategy revealed to be
successful in the identification of twelve new leads with IC50
values ranging from 1.19 mM to 107.30 mM. Herein we report the
design and synthetic efforts aimed at optimizing the effectiveness
of one of these leads, the carboxylate-type inhibitor S12728 (1)
(IC50 58.8 mM) (Fig. 1).
mental allergens-induced inflammatory signals that cause various
inflammatory diseases. Indeed, in animal models of asthma, cancer
(colon, breast, prostate and lung) and metastasis, inhibition of
aldose reductase significantly ameliorated the disease. Particularly,
it has been very recently demonstrated that inhibition of ARL2
prevents colon cancer metastasis [10]. Thus, the finding of novel,
potent ARL2 inhibitors can pave the way for a novel therapeutic
approach for a number of diseases besides long-term diabetic
complications.
2. Results and discussion
Today, a variety of structurally different compounds have been
identified as potent in vitro ALR2 inhibitors (ARIs) and a number of
them are in clinical trials to test their efficacy in the prevention and
treatment of peripheral neuropathy in diabetes [11]. They can be
classified into three general groups based on their structures: acetic
acid derivatives (e.g. epalrestat, tolrestat, zenarestat, zopolrestat,
NZ-314), cyclic imides (especially spirohydantoins, e.g. sorbinil,
fidarestat) and phenolic derivatives (e.g. quercetin) (Fig. 1). Despite
being structurally different, all ARIs possess two peculiar pharma-
cophoric elements: i) an acidic moiety which is able to interact with
the “anion-binding site” of the catalytic site (Y48, H110, W111 and
the flanking cofactor NADPþ), and ii) a lipophilic scaffold which can
bind to the highly flexible specificity pocket of the catalytic site
lined by L300, W111, T113 residues.
2.1. Receptor-based design of S12728 derivatives
The lead optimization campaign presented herein was rationally
designed by taking into account the theoretical binding pose of 1 in
the ALR2-binding site. Most precisely, in our previous study, this
compound was found by the Autodock (AD4) docking program to
preferentially bind the ALR2 ultrahigh resolution structure (PBD
code 1US0) [15] with respect to other enzyme conformations (PBD
codes: 2FZD, 2PDK). As shown in Fig. 2a, the carboxylate of 1 is well
inserted in the protein “anion-binding pocket” H-bonding with Y48,
Regardless the numerous efforts made over recent decades, to
date epalrestat is the only ARI commercially available and in Japan
alone, while fidarestat has already undergone phase III clinical trial
for diabetic neuropathy and was found to be safe. In many cases the
failure of new candidates can be ascribed to poor pharmacokinetic
properties and/or unacceptable side effects [11]. Furthermore, the
limited efficacy of many reported ARIs may also be related to
reduced binding affinity to ARL2 as a consequence of the oxidation
of a critical residue of cysteine (C298) in hyperglycemia-induced
oxidative stress [12,13]. For these reasons and for the newly
described therapeutic potentials of ARIs, there is still a great
interest in the identification of novel ARL2 inhibitors.
Fig. 2. (a) Theoretical-binding mode of compound S12728 (cyan) into the ALR2 cata-
lytic site represented as orange ribbons. The ligand and the interacting residues are
shown in stick representation and colored by atom type. H-bonds are represented with
dashed blue lines. All hydrogens were removed for clarity. (b) Superposition of IDD594
experimental-binding mode (violet) with the S12728 (cyan) theoretical binding mode.
(For interpretation of the references to colour in this figure legend, the reader is
referred to the web version of this article.)
Fig. 1. Chemical structures of known ARL2I together with S12728.

218
A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
H110 and W111 side chains and engaging an electrostatic interaction
with NADPþ nicotinamide moiety. On the other hand, the sulpho-
namide group well orients the tolyl substituent in the specificity
pocket making charge transfer interactions with W111 and hydro-
phobic contacts with W79, F122 and L300 side-chains. Additionally,
the thiophenylethyl group of 1 extends towards a rather hydro-
phobic cleft made up by W20, V47 and Y48 residues (Fig. 2a). The
availability of the ternary complex ARL2eNADPþeIDD594 at sub-
atomic resolution revealed a number of fine details at the active site
region of ARL2 that on one hand helped deciphering the reasons for
inhibitor potency and selectivity and, on the other, paved the way for
a rational optimization of our VS-derived lead compound (1). Thus,
as first step in our lead optimization process, we compared the
above-described theoretical binding mode of 1 with the experi-
mentally determined one of IDD594 [15]. As shown in Fig. 2b, it is
clear that the two structurally different inhibitors occupy the same
part of the ALR2 active site spanning from the anion-binding site to
the specificity pocket. Predictably, in both inhibitors the carboxylate
group is firmly anchored in the active site, with hydrogen bonds to
H110, Y48, and W111, and with an electrostatic interaction with
NADPþ. As shown in Fig. 2b, the sulfonamide moiety of 1 allows the
tolyl ring to adopt the same orientation of the IDD594 halogenated
aromatic ring (2-F-4-Br-phenyl) so that the same stacking interac-
tions with W111 side-chain can be established. However, while
resulting phenyl-containing derivative (2h) was optimized following
the above-illustrated criteria (2aeh). From the superposition of the
binding poses of IDD594 and 1 in ALR2, it also emerges that the
pendant thiophene ring of 1 does not overlap with the central flu-
orophenyl ring of IDD594, thus a third series of compounds was also
designed and synthesized where the ethyl linker was shortened and
the attached thiophene ring was substituted with a phenyl one
resulting in the benzyl derivatives 3aei.
2.2. Chemistry
The synthesis of the target compounds 1aeg, iel, 2aeh and
3aeh, j was accomplished as outlined in Scheme 1. Commercially
available 2-(thiophen-2-yl)ethylamine, 4, 2-phenylethylamine, 5,
and benzylamine, 6, were converted to the corresponding sulfon-
amides 8aeg, iel, 9aeh and 10aeh, j by reaction with the suitably
substituted sulfonyl chlorides 7ael in the presence of triethyl-
amine. Alkylation of sulfonamides with methyl bromoacetate
provided the methyl esters 11aeg, iel, 12aeh and 13aeh, j which
were hydrolyzed with sodium hydroxide to obtain, after acidifica-
tion, the title inhibitors 1aeg, iel, 2aeh and 3aeh, j in good yields.
An alternative procedure for the preparation of 2h, 3aec, 3feh, j is
reported in literature [17].
IDD594 can establish a favorable interaction with the T113 Og due to
2.3. Biology
the high polarization of the bromine atom [16], in our lead the tolyl
moiety is unable to engage such an interaction which is critical for
enzyme binding and selectivity [16]. Thus, the 4-Br-phenyl (1c) and
2-F-4-Br-phenyl (1e) analogues were designed and synthesized.
Moreover, to investigate the effect of other halogen substituents,
a fluorine (1a) and a chlorine (1b) atom were inserted in position 4 of
the phenyl ring of 1 as well as electron withdrawing groups such as
trifluoromethyl (1d) and a nitro (1f) moiety. The nitro moiety was
inserted also in position 3 bearing in mind the known activity of
several nitro-containing ARL2 inhibitors [16]. Furthermore, with the
aim of enhancing the staking interactions between W111 and the
phenyl ring of 1 the latter was substituted with a naphthyl,
a biphenyl or a dansyl group (compounds 1iel). As regards the
thiophene ring of 1 we attempted a bioisosteric replacement and the
All the synthesized compounds were tested for efficacy against
ALR2 and selectivity for ALR1 through a spectrophotometric assay,
performed exploiting D,L-glyceraldehyde as the substrate and epal-
restat asthe referencestandard. The inhibitoryactivity wasassayed at
a routine concentration of 100
active were tested at additional concentration between 10 and
0.01 M. Results of the biological evaluation are given in Table 1.
mM. Those compounds found to be
m
2.4. Structure activity relationships
As shown in Table 1, the optimization process was successful
resulting in a set of analogues that generally possess higher
inhibitory activities against ALR2 with respect to the lead
Scheme 1. Synthesis of compounds 1aeg, iel, 2aeh and 3aeh, j: (a) TEA, DCM, rt, overnight; (b) BrCH2COOCH3, K2CO3, DMF, rt, 24e48 h; (c) NaOH (10 M), reflux, 1 h; (d) HCl (3N), rt.

A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
219
Table 1
interact with the T113. Also the major inhibitory potencies of 1g vs
1f and 2g vs 2f would support the binding position of the tolyl ring
depicted in Fig. 2. In fact, the 3-NO2-phenyl moiety (see 1g) which
is common to other ARIs has been shown to positively affect the
interactions with the selectivity pocket allowing this group to
establish an H-bond with T113 [16,18]. The attempt to increase the
charge-transfer interactions with W111 by enlarging the ligand
aromatic surface (1i, 1j, 1k, 1l) proved to be a less successful
strategy. Nevertheless a certain increment in inhibitory potencies
with respect to the lead compound has been detected especially in
Inhibition of ARL2 and ALR1 by the carboxylate-type inhibitor S12728 and its
derivatives.
the case of 1j (4.27 mM).
As detailed above, in the case of compounds 1aeg, iel and 2aeh
SARs data would support the theoretical-binding mode found for 1.
Conversely, biological data achieved for compounds 3aej, that
feature the substitution of the thiophenetyl group with a benzyl one,
would indicate a different binding interaction with the enzyme; even
though the 3-NO2-analogue 3g is still the most active compound
among the benzyl derivatives. Docking studies performed on
compounds 3aej are not helpful in clarifying such a discrepancy and
only X-ray studies, which are beyond our possibilities, will unam-
biguously demonstrate the viability of these predictions.
All the above-mentioned compounds were tested for their
ability to inhibit aldehyde reductase (EC 1.1.1.2, ALR1), a member of
the AKR superfamily possessing the highest structural homology
with ALR2. As both ALR1 and ALR2 play a key detoxification role,
being involved in the maintenance of specific control over reactive
aldehydes, clinically effective and safe ARIs must necessarily
combine high levels of ALR2 inhibition with a significant selectivity
for ALR1, to keep unaltered its physiological role.
While the lead compound, 1, showed no appreciable activity,
derivatives 1a, cel proved to inhibit ALR1, with IC50 values in the
micromolar/high micromolar range. Nevertheless, compounds
showing the best ALR2 inhibitory activity, like 1e and 1g, turned out
the most selective ones, inhibiting ALR1 with almost 20-fold less
potency. Moreover, in the 2aeh and 3aej series, most of the
synthesized compounds proved to be completely selective inhibi-
tors of ALR2, showing no activity towards ALR1.
Compound
Ar
ALR2 (IC50
,
m
M)a
ALR1 (IC50
n.a.b
, m
M)a
S12728
1a
e
58.8 ꢀ 4.11
10.8 ꢀ 0.54
22.4 ꢀ 1.56
4.55 ꢀ 0.18
73.2 ꢀ 5.12
4-F-phenyl
61.2 ꢀ 3.06
1b
1c
1d
1e
1f
1g
4-Cl-phenyl
n.a.b
4-Br-phenyl
4-CF3-phenyl
2-F-4-Br-phenyl
4-NO2-phenyl
3-NO2-phenyl
1-naphthyl
57.8 ꢀ 3.45
52.5 ꢀ 3.27
57.6 ꢀ 3.44
84.7 ꢀ 4.22
7.56 ꢀ 0.30
14.7 ꢀ 0.88
5.93 ꢀ 0.25
16.0 ꢀ 0.89
2.20 ꢀ 0.044
11.9 ꢀ 0.71
0.431 ꢀ 0.012
12.4 ꢀ 0.52
4.27 ꢀ 0.26
13.3 ꢀ 0.93
26.5 ꢀ 1.85
47.1 ꢀ 2.83
45.4 ꢀ 2.72
3.56 ꢀ 0.11
68.3 ꢀ 2.73
5.48 ꢀ 0.37
21.0 ꢀ 1.26
1.09 ꢀ 0.043
84.7 ꢀ 5.08
29.0 ꢀ 2.32
23.4 ꢀ 1.18
70.4 ꢀ 4.92
74.7 ꢀ 5.22
18.0 ꢀ 1.08
17.3 ꢀ 1.38
5.51 ꢀ 0.33
24.8 ꢀ 1.74
6.51 ꢀ 0.39
0.17 ꢀ 0.01
1i
1j
2-naphthyl
1k
1l
2a
5-N(CH3)2-1-naphthyl
4-(1,10-biphenyl)
4-F-phenyl
1.15 ꢀ 0.069
74.5 ꢀ 3.79
n.a.b
2b
2c
2d
2e
2f
2g
4-Cl-phenyl
4-Br-phenyl
4-CF3-phenyl
2-F-4-Br-phenyl
4-NO2-phenyl
3-NO2-phenyl
4-CH3-phenyl
4-F-phenyl
n.a.b
n.a.b
65.9 ꢀ 3.22
n.a.b
10.4 ꢀ 0.41
n.a.b
2h
3a
33.9 ꢀ 1.36
3b
3c
3d
3e
3f
3g
4-Cl-phenyl
n.a.b
4-Br-phenyl
4-CF3-phenyl
2-F-4-Br-phenyl
4-NO2-phenyl
3-NO2-phenyl
4-CH3-phenyl
2-naphthyl
n.a.b
n.a.b
80.4 ꢀ 4.08
n.a.b
88.1 ꢀ 4.48
n.a.b
3h
3j
8.32 ꢀ 0.33
Epalrestat
0.94 ꢀ 0.04
a
IC50 values, means ꢀ SEM, represent the concentration required to produce 50%
enzyme inhibition.
2.5. In silico evaluation of the pharmacokinetic properties of the
new ARIs
b
n.a.: not active. Inhibition occurred at a concentration higher than 100 mM.
To achieve optimum therapeutic efficacy, ARIs should possess
not only a high degree of potency towards the target enzyme, but
also the capability to reach a certain concentration in tissues. In our
case ARIs could be in principle administered through topical
applications to treat diabetic visual impairments or through oral
administration for other diabetic complications. Therefore, to
provide a qualitative prediction of the pharmacokinetic properties
of our ARIs, in silico calculations were performed by means of the
Qikprop software (Schrödinger, LLC New York). The predicted
physicochemical features (MW, SASA, donor HB, log P, Caco-2
permeability reported in Table 1 in SI) are expected to influence
bioavailability through dissolution, cell permeation, and metabo-
lism. Interestingly all the most active compounds were predicted to
share similar in silico physicochemical features with epalrestat
which is the only ARI approved so far on the Japanese market (see
Table 1 in SI).
compound 1. The structure activity relationships (SARs) data pre-
sented here allowed on one hand to identify the nature and the
position of the substituents that can, in our lead 1, produce better
inhibitory potencies and on the other hand fully validate its theo-
retical binding mode. In fact, although only an X-ray analysis could
unambiguously determine at an atomic level the enzyme rear-
rangement upon our inhibitor binding, the binding pose of 1 as
identified by AD4 program seems to be strongly supported by all
the SARs here presented. Indeed, the interaction between the
carboxylate group and enzyme anionic site seems to be highly
reasonable. On the other hand, the placement of the tolyl ring in the
proximity of T113 is soundly supported by the lower IC50 values of
the bromurated analogs 1c and 2c with respect to 1. In fact, in
perfect line with the supposed interaction with the T113 Og, SARs
data clearly indicate that, among the compounds sharing a halogen
on the ligand phenyl ring (1aee) the ones with a 4-Br substitution
(1c and 1e) gave the best IC50 values. Moreover, the ranking in
potency observed for derivatives 1aed and 2aed is in accordance
with ab-initio studies performed in our previous work [18] which
indicate that the fluorine atom (1a and 1d), due to its small atomic
radius, is entirely electronegative and consequently unable to
3. Conclusion
The recent finding that the ARL2 inhibitor, fidarestat, signifi-
cantly prevents inflammatory signals (TNF-
a, LPS) that cause cancer
(colon, breast, prostate and lung) metastasis, asthma, and other
inflammatory diseases has been a further prompt for the finding of
novel ARL2 inhibitors. Herein, starting from the virtual screening-
engage the interaction with the oxygen atom lone pair of T113 O
g,
while the larger bromine due to its electropositive crown, can

220
A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
derived ALR2 inhibitor S12728 (1), a rational receptor-based lead
optimization has been undertaken. The optimization process has
been successful resulting in a set of analogues that generally
possess higher inhibitory activities against ALR2 with respect to the
lead compound 1. Our future research will focus on in vivo inves-
tigations on the effect of the newly discovered ARIs in inflamma-
tory-related diseases as well as in the diabetes-specific long-term
complications.
6.79 (s, 1H), 6.94 (t, J ¼ 4.3 Hz, 1H), 7.18 (d, J ¼ 5.1 Hz, 1H), 7.80 (d,
J ¼ 8.2 Hz, 2H), 7.96 (d, J ¼ 8.2 Hz, 2H).
4.1.1.5. N-[2-(2-thienyl)ethyl]-2-fluoro-4-bromobenzenesulfonamide
(8e). White solid; yield 95%; mp 60e62 ꢁC; 1H NMR (CDCl3):
d 3.05
(t, J ¼ 6.6 Hz, 2H), 3.32 (t, J ¼ 6.6 Hz, 2H), 4.84 (br s, 1H), 6.82 (s, 1H),
6.94 (m, 1H), 7.19 (d, J ¼ 5.1 Hz, 1H), 7.37e7.46 (m, 2H), 7.77 (t,
J ¼ 8.0 Hz, 1H).
4.1.1.6. N-[2-(2-thienyl)ethyl]-4-nitrobenzenesulfonamide (8f). Pale
yellow solid; yield 68%; mp 82e84 ꢁC; 1H NMR (CDCl3):
d 3.04 (t,
4. Experimental section
J ¼ 6.4 Hz, 2H), 3.33 (q, J ¼ 6.3 Hz, 2H), 4.87 (br s, 1H), 6.80 (s, 1H),
6.94 (t, J ¼ 3.5 Hz,1H), 7.17 (d, J ¼ 5.1 Hz,1H), 8.01 (d, J ¼ 8.6 Hz, 2H),
8.35 (d, J ¼ 7.9 Hz, 2H).
4.1. Materials
Melting points were taken on a Gallenkamp melting point
apparatus and are uncorrected. 1H NMR and 13C NMR were recor-
ded with a Varian 400 spectrometer, operating at 400 and 100 MHz
respectively. Mass spectra were obtained by electrospray ionization
(ESIMS) using a ThermoFinningan LCQ Deca XP Max ion-trap mass
spectrometer equipped with Xcalibur software. Chromatographic
separations were performed on silica gel (Kieselgel 40,
00.040e0.063 mm, Merck). Reactions and products mixtures were
routinely monitored by thin-layer chromatography (TLC) on Merck
0.2 mm precoated silica (60 F254) aluminum sheets, with visuali-
zation by irradiation with a UV lamp. Elemental analyses agreed
with theoretical values to within ꢀ0.4%. All starting materials,
reagents and solvents (reagent grade) were purchased from
SigmaeAldrich and used without further purification.
4.1.1.7. N-[2-(2-thienyl)ethyl]-3-nitrobenzenesulfonamide (8g). White
solid; yield 92%; mp 84e86 ꢁC; 1H NMR (CDCl3):
d 3.04
(t, J ¼ 6.5 Hz, 2H), 3.34 (q, J ¼ 6.4 Hz, 2H), 4.99 (br s, 1H), 6.79
(s, 1H), 6.90 (t, J ¼ 4.3 Hz, 1H), 7.13 (d, J ¼ 5.1 Hz, 1H), 7.74 (t,
J ¼ 8.0 Hz, 1H), 8.16 (d, J ¼ 7.8 Hz, 1H), 8.43 (d, J ¼ 8.2 Hz, 1H), 8.64
(s, 1H).
4.1.1.8. N-[2-(2-thienyl)ethyl]-1-naphthalenesulfonamide (8i). White
solid; yield 86%; mp 107e108 ꢁC; 1H NMR (CDCl3):
d 2.90 (t,
J ¼ 6.6 Hz, 2H), 3.22 (q, J ¼ 6.5 Hz, 2H), 4.72 (br t, J ¼ 4.5 Hz, 1H), 6.62
(s,1H), 6.84 (m,1H), 7.08 (d, J ¼ 5.0 Hz,1H), 7.57e7.65 (m, 3H), 7.98 (d,
J ¼ 6.6 Hz, 1H), 8.10 (d, J ¼ 8.1 Hz, 1H), 8.29 (d, J ¼ 7.6 Hz, 1H), 8.55 (d,
J ¼ 8.2 Hz, 1H).
4.1.1. General procedure for the preparation of sulfonamides 8aeg,
iel, 9aeh and 10aeh, j
4.1.1.9. N-[2-(2-thienyl)ethyl]-2-naphthalenesulfonamide (8j). White
solid; yield 83%; mp 102e103 ꢁC; 1H NMR (CDCl3):
d 3.01 (t,
A solution of appropriate sulfonyl chloride 7ael (10 mmol) in
dichloromethane (15 mL) was slowly added to a cooled (0 ꢁC)
solution of amine 4e6 (15 mmol) in dichloromethane (10 mL) and
triethylamine (15 mmol). The resulting mixture was stirred at room
temperature overnight. The solvent was removed at reduced
pressure, then the resulting residue was taken up in ethyl acetate
and washed with a solution of HCl (1 M, 2 ꢂ 25 mL) and brine
(2 ꢂ 25 mL). The organic phase was dried over anhydrous Na2SO4,
and the solvent was removed under reduced pressure. The title
compounds were purified by crystallization from ethyl acetate/
petroleum ether 40e60 ꢁC. A similar procedure has been employed
for the synthesis of 9feh, 10feg, while a different synthetic
approach has been described for 10aee, 10hek; in all cases our 1H
NMR spectral data matched those previously reported for these
compounds [19].
J ¼ 6.6 Hz, 2H), 3.31 (q, J ¼ 6.4 Hz, 2H), 4.63 (br t, J ¼ 5.1 Hz, 1H), 6.77
(s,1H), 6.91 (t, J ¼ 5.1 Hz,1H), 7.15 (d, J ¼ 5.1 Hz,1H), 7.66 (m, 2H), 7.80
(m, 1H), 7.97 (m, 3H), 8.44 (s, 1H).
4.1.1.10. N-[2-(2-thienyl)ethyl]-5-dimethylamino-1-naphthalenesulfon-
amide (8k). Yellow solid; yield 87%; mp 107e108 ꢁC; 1H NMR (CDCl3):
d
2.93 (m, 8H), 3.20 (m, 2H), 4.73 (br s, 1H), 6.63 (s, 1H), 6.85 (m, 1H),
7.09 (m, 1H), 7.21 (d, J ¼ 7.3 Hz, 1H), 7.56 (m, 2H), 8.21 (d, J ¼ 8.4 Hz,
1H), 8.27 (d, J ¼ 7.1 Hz, 1H), 8.59 (d, J ¼ 8.1 Hz, 1H).
4.1.1.11. N-[2-(2-thienyl)ethyl]-(1,10-biphenyl)-4-sulfonamide (8l). White
solid; yield 77%; mp 102e104 ꢁC; 1H NMR (CDCl3):
d
3.04 (t, J ¼ 6.4 Hz,
2H), 3.31 (m, 2H), 4.53 (br s, 1H), 6.81 (s, 1H), 6.94 (t, J ¼ 4.9 Hz, 1H), 7.17
(d, J ¼ 5.2 Hz, 1H), 7.42e7.53 (m, 3H), 7.63 (d, J ¼ 6.7 Hz, 2H), 7.73 (d,
J ¼ 8.2 Hz, 2H), 7.91 (d, J ¼ 8.2 Hz, 2H).
4.1.1.1. N-[2-(2-thienyl)ethyl]-4-fluorobenzenesulfonamide (8a). White
solid; yield 73%; mp 85e87 ꢁC; 1H NMR (CDCl3):
d
3.01 (t, J ¼ 6.6 Hz,
4.1.1.12. N-(2-phenylethyl)-4-fluorobenzenesulfonamide (9a). White
solid; yield 97%; mp 81e82 ꢁC; 1H NMR (CDCl3):
d
2.80 (t, J ¼ 6.7 Hz,
2H), 3.27 (t, J ¼ 6.6 Hz, 2H), 4.77 (br s, 1H), 6.78 (s, 1H), 6.94 (t,
J ¼ 4.2 Hz, 1H), 7.18e7.23 (m, 3H), 7.84e7.89 (m, 2H).
2H), 3.26 (m, 2H), 4.37 (br s, 1H), 7.09e7.31 (m, 7H), 7.83 (m, 2H).
4.1.1.13. N-(2-phenylethyl)-4-chlorobenzenesulfonamide (9b). White
4.1.1.2. N-[2-(2-thienyl)ethyl]-4-chlorobenzenesulfonamide (8b). White
solid; yield 93%; mp 89e90 ꢁC; 1H NMR (CDCl3):
d
2.80 (t, J ¼ 6.7 Hz,
solid; yield 95%; mp 87e89 ꢁC; 1H NMR (CDCl3):
d
3.02 (t, J ¼ 6.5 Hz,
2H), 3.26 (m, 2H), 4.44 (br s, 1H), 7.10 (d, J ¼ 7.3 Hz, 2H), 7.30 (m, 3H),
2H), 3.27 (m, 2H), 4.69 (br s, 1H), 6.79 (s, 1H), 6.94 (t, J ¼ 4.1 Hz, 1H),
7.17 (d, J ¼ 4.9 Hz, 1H), 7.49 (d, J ¼ 8.4 Hz, 2H), 7.78 (d, J ¼ 8.4 Hz, 2H).
7.48 (d, J ¼ 7.0 Hz, 2H), 7.74 (d, J ¼ 7.0 Hz, 2H).
4.1.1.14. N-(2-phenylethyl)-4-bromobenzenesulfonamide (9c). White
4.1.1.3. N-[2-(2-thienyl)ethyl]-4-bromobenzenesulfonamide (8c). White
solid; yield 88%; mp 88e90 ꢁC; 1H NMR (CDCl3):
d
2.80 (t, J ¼ 6.9 Hz,
solid; yield 94%; mp 96e98 ꢁC; 1H NMR (CDCl3):
d
3.01 (t, J ¼ 6.6 Hz,
2H), 3.26 (m, 2H), 4.59 (br s,1H), 7.10 (d, J ¼ 7.6 Hz, 2H), 7.25e7.32 (m,
2H), 3.27 (q, J ¼ 6.5 Hz, 2H), 4.72 (br t, J ¼ 5.7 Hz, 1H), 6.78 (s, 1H), 6.94
3H), 7.62e7.69 (m, 4H).
(t, J ¼ 4.2 Hz, 1H), 7.17 (d, J ¼ 5.1 Hz, 1H), 7.64e7.72 (m, 4H).
4.1.1.15. N-(2-phenylethyl)-4-trifluoromethylbenzenesulfonamide
(9d). White solid; yield 89%; mp 109e111 ꢁC; 1H NMR (CDCl3):
4.1.1.4. N-[2-(2-thienyl)ethyl]-4-trifluoromethylbenzenesulfonamide
(8d). White solid; yield: 89%; mp 90e92 ꢁC; 1H NMR (CDCl3):
d
3.04
d
2.81 (t, J ¼ 6.8 Hz, 2H), 3.29 (q, J ¼ 6.7 Hz, 2H), 4.77 (br s, 1H), 7.09
(t, J ¼ 6.5 Hz, 2H), 3.31 (q, J ¼ 6.4 Hz, 2H), 4.65 (br t, J ¼ 5.6 Hz, 1H),

A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
221
(d, J ¼ 7.7 Hz, 2H), 7.28 (m, 3H), 7.76 (d, J ¼ 8.3 Hz, 2H), 7.92
(d, J ¼ 8.4 Hz, 2H).
4.1.1.28. N-benzyl-2-napthalenesulfonamide (10j). White solid; yield
80%; mp 94e96 ꢁC [Lit 133 ꢁC] [19f]; 1H NMR (CDCl3):
4.20 (d,
d
J ¼ 6.0 Hz, 2H), 4.72 (br s, 1H), 7.22 (m, 5H), 7.68 (m, 2H), 7.88e8.01
4.1.1.16. N-(2-phenylethyl)-2-fluoro-4-bromobenzenesulfonamide
(9e). White solid; yield: 79%; mp 82e84 ꢁC; 1H NMR (CDCl3):
(m, 4H), 8.47 (s, 1H).
d
2.83 (t, J ¼ 6.8 Hz, 2H), 3.31 (q, J ¼ 6.7 Hz, 2H), 4.68 (br
4.1.2. General procedure for the preparation of compounds 11aeg,
iel, 12aeh, 13aeh, j
t, J ¼ 5.7 Hz, 1H), 7.12 (d, J ¼ 7.8 Hz, 2H), 7.26e7.45 (m, 5H), 7.76
(t, J ¼ 8.0 Hz, 1H).
Methyl bromoacetate (15 mmol) and anhydrous K2CO3
(25 mmol) were added to a solution of sulfonamides 8aeg, iel,
9aeh, 10aeh, j (5 mmol) in N,N-dimethylformamide (5 mL), and
the resulting mixture was stirred at room temperature until start-
ing material was not detected by TLC. The solvent was removed
under reduced pressure and the resulting residue was taken up in
ethyl acetate, and washed with HCl (1 M, 2 ꢂ 25 mL) and brine
(2 ꢂ 25 mL). The title compounds were obtained after purification
by flash chromatography.
4.1.1.17. N-(2-phenylethyl)-4-nitrobenzenesulfonamide (9f). White
solid; yield 87%; mp 89e91 ꢁC [Lit. 92.5e93.5 ꢁC] [20]; 1H NMR
(CDCl3):
(d, J ¼ 7.2 Hz, 2H), 7.28 (m, 3H), 7.97 (d, J ¼ 8.9 Hz, 2H), 8.32 (d,
J ¼ 8.9 Hz, 2H).
d
2.84 (t, J ¼ 6.7 Hz, 2H), 3.32 (m, 2H), 4.79 (br s, 1H), 7.10
4.1.1.18. N-(2-phenylethyl)-3-nitrobenzenesulfonamide (9g). Pale
yellow solid; yield 97%; mp 90e92 ꢁC; 1H NMR (CDCl3):
d 2.83 (t,
J ¼ 6.8 Hz, 2H), 3.34 (q, J ¼ 6.7 Hz, 2H), 4.75 (br t, J ¼ 5.5 Hz, 1H),
7.09 (d, J ¼ 6.5 Hz, 2H), 7.28 (m, 3H), 7.71 (t, J ¼ 8.0 Hz, 1H), 8.12 (d,
J ¼ 7.3 Hz, 1H), 8.42 (d, J ¼ 8.2 Hz, 1H), 8.61 (s, 1H).
4.1.2.1. N-[2-(2-thienyl)ethyl]-N-[(4-fluorophenyl)sulfonyl]glycine
methyl ester (11a). White solid; yield 77%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC, 1:1 v/v); mp 43e45 ꢁC; 1H NMR
(CDCl3):
d
3.12 (t, J ¼ 7.4 Hz, 2H), 3.53 (t, J ¼ 7.4 Hz, 2H), 3.63 (s, 3H),
4.1.1.19. N-(2-phenylethyl)-4-methylbenzenesulfonamide (9h). White
solid; yield 96%; mp 62e64 ꢁC [Lit. 51e53 ꢁC] [21]; 1H NMR
4.04 (s, 2H), 6.82 (s, 1H), 6.92 (t, J ¼ 4.0 Hz, 1H), 7.15 (m, 3H), 7.86
(m, 2H).
(CDCl3):
d
2.44 (s, 3H), 2.78 (t, J ¼ 7.0 Hz, 2H), 3.22 (m, 2H), 4.74
(br s, 1H), 7.10 (d, J ¼ 7.7 Hz, 2H), 7.23e7.32 (m, 5H), 7.72
4.1.2.2. N-[2-(2-thienyl)ethyl]-N-[(4-chlorophenyl)sulfonyl]glycine
methyl ester (11b). White solid; yield 96%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC,1:1 v/v); mp 80e82 ꢁC; 1H NMR (CDCl3):
(d, J ¼ 8.2 Hz, 2H).
4.1.1.20. N-benzyl-4-fluorobenzenesulfonamide (10a). White solid;
d
3.14 (t, J ¼ 7.4 Hz, 2H), 3.54 (t, J ¼ 7.4 Hz, 2H), 3.65 (s, 3H), 4.04 (s,
yield 97%; mp 96e98 ꢁC [Lit. 99.4 ꢁC] [19e]; 1H NMR (CDCl3):
d
4.18
2H), 6.84 (s, 1H), 6.94 (t, J ¼ 4.2 Hz, 1H), 7.17 (t, J ¼ 5.1 Hz, 1H), 7.49
(d, J ¼ 8.5 Hz, 2H), 7.79 (d, J ¼ 8.7 Hz, 2H).
(d, J ¼ 6.0 Hz, 2H), 4.83 (br s, 1H), 7.16e7.31 (m, 7H), 7.89 (m, 2H).
4.1.1.21. N-benzyl-4-chlorobenzenesulfonamide (10b). White solid;
4.1.2.3. N-[2-(2-thienyl)ethyl]-N-[(4-bromophenyl)sulfonyl]glycine
methyl ester (11c). White solid; yield 86%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC,1:1 v/v); mp 75e77 ꢁC; 1H NMR (CDCl3):
yield 95%; mp 104e106 ꢁC; 1H NMR (CDCl3):
d
4.18 (d, J ¼ 5.9 Hz,
2H), 4.78 (br s, 1H), 7.21 (m, 2H), 7.30 (m, 3H), 7.49 (d, J ¼ 8.6 Hz,
2H), 7.81 (d, J ¼ 8.6 Hz, 2H).
d
3.14 (t, J ¼ 7.4 Hz, 2H), 3.52 (t, J ¼ 7.4 Hz, 2H), 3.65 (s, 3H), 4.04 (s,
2H), 6.83 (s, 1H), 6.93 (t, J ¼ 4.3 Hz, 1H), 7.17 (d, J ¼ 5.1 Hz, 1H),
7.63e7.73 (m, 4H).
4.1.1.22. N-benzyl-4-bromobenzenesulfonamide (10c). White solid;
yield 91%; mp 118e120 ꢁC [Lit. 101 ꢁC] [19f]; 1H NMR (CDCl3):
d 4.18
(d, J ¼ 6.1 Hz, 2H), 4.79 (br t, J ¼ 5.7 Hz, 1H), 7.21 (m, 2H), 7.30 (m,
4.1.2.4. N-[2-(2-thienyl)ethyl]-N-[(4-trifluoromethylphenyl)sulfonyl]
glycine methyl ester (11d). White solid; yield 93%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC,1:1 v/v); mp 58e60 ꢁC; 1H NMR (CDCl3):
3H), 7.65 (d, J ¼ 8.7 Hz, 2H), 7.73 (d, J ¼ 8.6 Hz, 2H).
4.1.1.23. N-benzyl-4-trifluoromethylbenzenesulfonamide (10d). White
solid; yield 79%; mp 121e122 ꢁC [Lit 113e114 ꢁC] [19g]; 1H NMR
d
3.15 (t, J ¼ 7.3 Hz, 2H), 3.56 (t, J ¼ 7.3 Hz, 2H), 3.64 (s, 3H), 4.07 (s,
2H), 6.83 (s, 1H), 6.94 (t, J ¼ 4.0 Hz, 1H), 7.16 (d, J ¼ 4.2 Hz, 1H), 7.77
(d, J ¼ 7.9 Hz, 2H), 7.97 (d, J ¼ 7.8 Hz, 2H).
(CDCl3):
d
4.22 (d, J ¼ 6.0 Hz, 2H), 4.87 (br t, J ¼ 5.6 Hz, 1H), 7.20 (m,
2H), 7.29 (m, 3H), 7.77 (d, J ¼ 8.2 Hz, 2H), 7.98 (d, J ¼ 8.2 Hz, 2H).
4.1.2.5. N-[2-(2-thienyl)ethyl]-N-[(2-fluoro-4-bromophenyl)sulfonyl]
glycine methyl ester (11e). White solid; yield 98%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC, 7:3 v/v); mp 68e70 ꢁC; 1H NMR (CDCl3):
4.1.1.24. N-benzyl-2-fluoro-4-bromobenzenesulfonamide (10e). White
solid; yield 91%; mp 103e105 ꢁC; 1H NMR (CDCl3):
d 4.23 (d,
J ¼ 6.1 Hz, 2H), 5.00 (br t, J ¼ 6.1 Hz, 1H), 7.20e7.37 (m, 6H), 7.42 (d,
d
3.14 (t, J ¼ 7.3 Hz, 2H), 3.64 (t, J ¼ 7.7 Hz, 2H), 3.67 (s, 3H), 4.11 (s,
J ¼ 8.4 Hz, 1H), 7.76 (t, J ¼ 8.3 Hz, 1H).
2H), 6.82 (s, 1H), 6.93 (t, J ¼ 4.2 Hz, 1H), 7.15 (d, J ¼ 4.9 Hz, 1H), 7.39
(m, 2H), 7.76 (t, J ¼ 7.9 Hz, 1H).
4.1.1.25. N-benzyl-4-nitrobenzenesulfonamide (10f). Pale yellow
solid; yield 87%; mp 126e128 ꢁC [Lit. 126.6e127 ꢁC] [22]; 1H NMR
4.1.2.6. N-[2-(2-thienyl)ethyl]-N-[(4-nitrophenyl)sulfonyl]glycine
(CDCl3):
d
4.25 (d, J ¼ 6.0 Hz, 2H), 5.07 (br t, J ¼ 5.7 Hz, 1H), 7.19 (m,
methyl ester (11f). Pale yellow oil; yield 87%; SiO2 (ethyl ether/
2H), 7.28 (m, 3H), 8.00 (d, J ¼ 8.9 Hz, 2H), 8.32 (d, J ¼ 8.9 Hz, 2H).
petroleum ether 40e60 ꢁC, 1:1 v/v); 1H NMR (CDCl3):
d 3.17 (t,
J ¼ 7.1 Hz, 2H), 3.59 (t, J ¼ 7.1 Hz, 2H), 3.65 (s, 3H), 4.11 (s, 2H), 6.86
(s, 1H); 6.96 (t, J ¼ 4.7 Hz, 1H), 7.19 (d, J ¼ 4.8 1H), 8.03 (d, J ¼ 8.4 Hz,
2H), 8.36 (d, J ¼ 8.4 Hz, 2H).
4.1.1.26. N-benzyl-3-nitrobenzenesulfonamide (10g). White solid;
yield 93%; mp 95e97 ꢁC; 1H NMR (CDCl3):
d
4.28 (d, J ¼ 6.0 Hz, 2H),
4.99 (br t, J ¼ 5.2 Hz,1H), 7.19 (m, 2H), 7.28 (m, 3H), 7.70 (t, J ¼ 8.0 Hz,
1H), 8.15 (d, J ¼ 7.9 Hz, 1H), 8.40 (d, J ¼ 8.1 Hz, 1H), 8.62 (s, 1H).
4.1.2.7. N-[2-(2-thienyl)ethyl]-N-[(3-nitrophenyl)sulfonyl]glycine
methyl ester (11g). White solid; yield 76%; SiO2 (dichloromethane);
4.1.1.27. N-benzyl-4-methylbenzenesulfonamide (10h). White solid;
mp 65e67 ꢁC; 1H NMR (CDCl3):
d
3.13 (t, J ¼ 7.2 Hz, 2H), 3.56 (t,
yield 88%; mp 112e114 ꢁC [Lit. 117 ꢁC] [19f]; 1H NMR (CDCl3):
d
2.46
J ¼ 7.2 Hz, 2H), 3.63 (s, 3H), 4.11 (s, 2H), 6.82 (s, 1H), 6.89 (t,
J ¼ 4.3 Hz, 1H), 7.12 (d, J ¼ 5.1 Hz, 1H), 7.72 (t, J ¼ 8.0 Hz, 1H), 8.15 (d,
J ¼ 7.9 Hz, 1H), 8.41 (d, J ¼ 8.2 Hz, 1H), 8.62 (s, 1H).
(s, 3H), 4.14 (d, J ¼ 5.9 Hz, 2H), 4.76 (br s, 1H), 7.20e7.34 (m, 7H),
7.78 (d, J ¼ 8.2 Hz, 2H).

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A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
4.1.2.8. N-[2-(2-thienyl)ethyl]-N-[(1-naphthalenyl)sulfonyl]glycine
methyl ester (11i). White solid; yield 92%; SiO2 (ethyl ether/petro-
leum ether 40e60 ꢁC, 7:3 v/v); mp 69e71 ꢁC; 1H NMR (CDCl3):
3.54 (t, J ¼ 7.4 Hz, 2H), 3.65 (s, 3H), 4.08 (s, 2H), 7.17 (d, J ¼ 7.8 Hz,
2H), 7.21e7.43 (m, 3H), 7.99 (d, J ¼ 8.7 Hz, 2H), 8.32 (d, J ¼ 8.8 Hz,
2H).
d
3.04 (t, J ¼ 7.5 Hz, 2H), 3.51 (s, 3H), 3.66 (t, J ¼ 7.5 Hz, 2H), 4.15 (s,
2H), 6.71 (s, 1H), 6.85 (t, J ¼ 5.1 Hz, 1H), 7.08 (d, J ¼ 5.1 Hz, 1H),
7.53e7.60 (m, 3H), 7.93 (d, J ¼ 8.0 Hz, 1H), 8.08 (d, J ¼ 8.2 Hz, 1H),
8.31 (d, J ¼ 7.4 Hz, 1H), 8.65 (d, J ¼ 8.6 Hz, 1H).
4.1.2.18. N-(2-phenylethyl)-N-[(3-nitrophenyl)sulfonyl]glycine
methyl ester (12g). Pale yellow oil; yield 95%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC, 7:3 v/v); 1H NMR (CDCl3):
d 2.92 (t,
J ¼ 7.5 Hz, 2H), 3.54 (t, J ¼ 7.5 Hz, 2H), 3.65 (s, 3H), 4.10 (s, 2H),
7.15e7.31 (m, 5H), 7.69 (t, J ¼ 8.0 Hz,1H), 8.15 (d, J ¼ 7.9 Hz,1H), 8.42
(d, J ¼ 8.1 Hz, 1H), 8.64 (s, 1H).
4.1.2.9. N-[2-(2-thienyl)ethyl]-N-[(2-naphthalenyl)sulfonyl]glycine
methyl ester (11j). White solid; yield 77%; SiO2 (ethyl ether/petro-
leum ether 40e60 ꢁC, 1:1 v/v); mp 63e65 ꢁC; 1H NMR (CDCl3):
d
3.16 (t, J ¼ 7.5 Hz, 2H), 3.57e3.63 (m, 5H), 4.09 (s, 2H), 6.82 (s, 1H),
4.1.2.19. N-(2-phenylethyl)-N-[(4-methylphenyl)sulfonyl]glycine
6.91 (t, J ¼ 5.1 Hz, 1H), 7.14 (d, J ¼ 5.1 Hz, 1H), 7.68 (m, 2H), 7.82 (m,
methyl ester (12h). Colorless oil; yield 92%; SiO2 (ethyl ether/
1H), 7.98 (m, 3H), 8.44 (s, 1H).
petroleum ether 40e60 ꢁC, 7:3 v/v); 1H NMR (CDCl3):
d 2.43 (s, 3H),
2.89 (t, J ¼ 7.8 Hz, 2H), 3.63 (s, 3H), 4.01 (s, 2H), 7.17e7.31 (m, 7H),
4.1.2.10. N-[2-(2-thienyl)ethyl]-N-[(5-dimethylamino-1-naphthalenyl)
7.73 (d, J ¼ 8.3 Hz, 2H).
sulfonyl]glycine methyl ester (11k). Yellow oil; yield 94%; SiO2
(dichloromethane); 1H NMR (CDCl3):
d
2.91 (s, 6H), 3.03 (t, J ¼ 7.3 Hz,
4.1.2.20. N-benzyl-N-[(4-fluorophenyl)sulfonyl]glycine methyl ester
(13a). White solid; yield 91%; SiO2 (ethyl ether/petroleum ether
2H), 3.55 (s, 2H), 3.66 (t, J ¼ 7.3 Hz, 2H), 4.14 (s, 2H), 6.70 (s, 1H), 6.85
(m, 1H), 7.08 (m, 1H), 7.24 (m, 1H), 7.51e7.59 (m, 3H), 8.30 (d,
J ¼ 7.5 Hz, 2H), 8.55 (d, J ¼ 8.0 Hz, 1H).
40e60 ꢁC, 1:1 v/v); mp 49e51 ꢁC; 1H NMR (CDCl3):
d 3.59 (s, 3H),
3.96 (s, 2H), 4.51 (s, 2H), 7.20e7.38 (m, 7H), 7.94 (m, 2H).
4.1.2.11. N-[2-(2-thienyl)ethyl]-N-[(1,10-biphenyl)-4-sulfonyl]glycine
4.1.2.21. N-benzyl-N-[(4-chlorophenyl)sulfonyl]glycine methyl ester
methyl ester (11l). Colorless oil; yield 93%; SiO2 (ethyl ether/
(13b). White solid; yield 96%; SiO2 (dichloromethane); mp
petroleum ether 40e60 ꢁC, 1:1 v/v); 1H NMR (CDCl3):
d
3.16 (t,
44e46 ꢁC; 1H NMR (CDCl3):
d 3.59 (s, 3H), 3.96 (s, 2H), 4.51 (s, 2H),
J ¼ 7.4 Hz, 2H), 3.58 (t, J ¼ 7.4 Hz, 2H), 3.64 (s, 3H), 4.06 (s, 2H), 6.84
(s, 1H), 6.93 (m, 1H), 7.16 (d, J ¼ 4.03 Hz, 1H), 7.43e7.52 (m, 3H), 7.62
(d, J ¼ 7.0 Hz, 2H), 7.72 (d, J ¼ 8.4 Hz, 2H), 7.91 (d, J ¼ 8.2 Hz, 2H).
7.26e7.35 (m, 5H), 7.52 (d, J ¼ 8.3 Hz, 2H), 7.85 (d, J ¼ 8.3 Hz, 2H).
4.1.2.22. N-benzyl-N-[(4-bromophenyl)sulfonyl]glycine methyl ester
(13c). White solid; yield 88%; SiO2 (dichloromethane); mp
4.1.2.12. N-(2-phenylethyl)-N-[(4-fluorophenyl)sulfonyl]glycine
methyl ester (12a). Pale yellow oil; yield 93%; SiO2 (ethyl ether/
71e73 ꢁC; 1H NMR (CDCl3):
d 3.59 (s, 3H), 3.96 (s, 2H), 4.51 (s,
2H), 7.26e7.36 (m, 5H), 7.69 (d, J ¼ 8.6 Hz, 2H), 7.80 (d,
petroleum ether 40e60 ꢁC, 1:1 v/v); 1H NMR (CDCl3):
d 2.90 (t,
J ¼ 8.6 Hz, 2H).
J ¼ 7.7 Hz, 2H), 3.50 (t, J ¼ 7.7 Hz, 2H), 3.64 (s, 3H), 4.03 (s, 2H),
7.15e7.32 (m, 7H), 7.86 (m, 2H).
4.1.2.23. N-benzyl-N-[(4-trifluoromethylphenyl)sulfonyl]glycine
methyl ester (13d). White solid; yield 81%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC,1:1 v/v); mp 73e75 ꢁC; 1H NMR (CDCl3):
4.1.2.13. N-(2-phenylethyl)-N-[(4-chlorophenyl)sulfonyl]glycine
methyl ester (12b). White solid; yield 96%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC,1:1 v/v); mp 72e73 ꢁC; 1H NMR (CDCl3):
d
3.57 (s, 3H), 3.99 (s, 2H), 4.53 (s, 2H), 7.26e7.34 (m, 5H), 7.81 (d,
J ¼ 8.3 Hz, 2H), 8.04 (d, J ¼ 8.2 Hz, 2H).
d
2.90 (t, J ¼ 7.6 Hz, 2H), 3.50 (t, J ¼ 7.7 Hz, 2H), 3.65 (s, 3H), 4.03 (s,
2H), 7.16 (d, J ¼ 7.3 Hz, 2H), 7.24e7.32 (m, 3H), 7.47 (d, J ¼ 8.2 Hz,
2H), 7.77 (d, J ¼ 8.2 Hz, 2H).
4.1.2.24. N-benzyl-N-[(2-fluoro-4-bromophenyl)sulfonyl]glycine
methyl ester (13e). White solid; yield 96%; SiO2 (dichloromethane);
mp 52e54 ꢁC; 1H NMR (CDCl3):
d 3.60 (s, 3H), 4.02 (s, 2H), 4.62 (s,
4.1.2.14. N-(2-phenylethyl)-N-[(4-bromophenyl)sulfonyl]glycine
methyl ester (12c). White solid; yield 93%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC,1:1 v/v); mp 65e67 ꢁC; 1H NMR (CDCl3):
2H), 7.26e7.44 (m, 7H), 7.78 (t, J ¼ 8.0 Hz, 1H).
4.1.2.25. N-benzyl-N-[(4-nitrophenyl)sulfonyl]glycine methyl ester
d
2.90 (t, J ¼ 7.6 Hz, 2H), 3.50 (t, J ¼ 7.6 Hz, 2H), 3.79 (s, 3H), 4.02 (s,
(13f). Pale yellow solid; yield 82%; SiO2 (ethyl ether/petroleum
2H), 7.16 (d, J ¼ 7.4 Hz, 2H), 7.21e7.32 (m, 3H), 7.62 (d, J ¼ 8.7 Hz,
2H), 7.69 (d, J ¼ 8.7 Hz, 2H).
ether 40e60 ꢁC, 1:1 v/v); mp 88e90 ꢁC; 1H NMR (CDCl3):
d 3.60 (s,
3H), 4.02 (s, 2H), 4.54 (s, 2H), 7.27e7.37 (m, 5H), 8.08 (d, J ¼ 8.6 Hz,
2H), 8.39 (d, J ¼ 8.6 Hz, 2H).
4.1.2.15. N-(2-phenylethyl)-N-[(4-trifluoromethylphenyl)sulfonyl]
glycine methyl ester (12d). White solid; yield 97%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC,1:1 v/v); mp 61e63 ꢁC; 1H NMR (CDCl3):
4.1.2.26. N-benzyl-N-[(3-nitrophenyl)sulfonyl]glycine methyl ester
(13g). White solid; yield 87%; SiO2 (ethyl acetate/dichloromethane
d
2.92 (t, J ¼ 7.5 Hz, 2H), 3.54 (t, J ¼ 7.5 Hz, 2H), 3.63 (s, 3H), 4.06 (s,
0.5:9.5 v/v); mp 67e69 ꢁC; 1H NMR (CDCl3):
d 3.61 (s, 3H), 4.04 (s,
2H), 7.16 (d, J ¼ 6.9 Hz, 2H), 7.24e7.30 (m, 3H), 7.75 (d, J ¼ 8.2 Hz,
2H), 7.95 (d, J ¼ 8.2 Hz, 2H).
2H), 4.54 (s, 2H), 7.28e7.39 (m, 5H), 7.77 (t, J ¼ 8.0 Hz, 1H), 8.23 (d,
J ¼ 7.8 Hz, 1H), 8.48 (d, J ¼ 8.2 Hz, 1H), 8.73 (s, 1H).
4.1.2.16. N-(2-phenylethyl)-N-[(2-fluoro-4-bromophenyl)sulfonyl]
glycine methyl ester (12e). White solid; yield 81%; SiO2 (ethyl ether/
petroleum ether 40e60 ꢁC, 1:1 v/v); mp 72e74 ꢁC; 1H NMR (CDCl3):
4.1.2.27. N-benzyl-N-[(4-methylphenyl)sulfonyl]glycine methyl ester
(13h). White solid; yield 90%; SiO2 (dichloromethane); mp
45e48 ꢁC; 1H NMR (CDCl3):
d 2.47 (s, 3H), 3.56 (s, 3H), 3.94 (s, 2H),
d
2.89 (t, J ¼ 7.5 Hz, 2H), 3.61 (t, J ¼ 7.5 Hz, 2H), 3.67 (s, 3H), 4.10 (s,
4.50 (s, 2H), 7.25e7.36 (m, 7H), 7.80 (d, J ¼ 8.1 Hz, 2H).
2H), 7.15 (d, J ¼ 7.8 Hz, 2H), 7.23e7.41 (m, 5H), 7.75 (t, J ¼ 8.0 Hz,1H).
4.1.2.28. N-benzyl-N-[(2-napthalenyl)sulfonyl]glycine methyl ester
4.1.2.17. N-(2-phenylethyl)-N-[(4-nitrophenyl)sulfonyl]glycine
(13j). White solid; yield 66%; mp 82e84 ꢁC; 1H NMR (CDCl3):
d 3.49
methyl ester (12f). White solid; yield 98%; SiO2 (dichloro-
(s, 3H), 4.00 (s, 2H), 4.59 (s, 2H), 7.30 (m, 5H), 7.65 (m, 2H),
7.87e8.03 (m, 4H), 8.49 (s, 1H).
methane); mp 97e99 ꢁC; 1H NMR (CDCl3):
d
2.92 (t, J ¼ 7.4 Hz, 2H),

A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
223
4.1.3. General procedure for the preparation of acids 1aeg, iel,
2aeh, 3aeh, j
1H), 6.93 (t, J ¼ 4.8 Hz,1H), 7.16 (d, J ¼ 5.0 Hz,1H), 7.99 (d, J ¼ 8.4 Hz,
2H), 8.33 (d, J ¼ 8.6 Hz, 2H); 13C NMR (DMSO-d6):
d 29.08, 49.08,
To a solution of methyl esters 11aeg, iel, 12aeh, 13aeh, j
(5 mmol) in methanol (10 mL) was added NaOH (10 M, 25 mmol)
and the resulting mixture was refluxing for 1 h. After cooling at
room temperature, the mixture was concentrated under reduced
pressure and then HCl (3N) was added (pH w 2). After extraction
with ethyl acetate, the organic solvent was dried over anhydrous
Na2SO4 and removed under reduced pressure. The resulting residue
was purified by flash chromatography (methanol/ethyl acetate, 2:8
v/v as eluent) and recrystallized from ethyl acetate/petroleum ether
40e60 ꢁC to give the title compounds in good yields.
50.53, 125.09, 125.10, 126.38, 127.74, 129.21, 140.75, 145.72, 150.30,
170.70. ESIMS m/z: 369.1 [M ꢃ H]ꢃ. Anal. calcd. for C14H14N2O6S2: C,
45.40; H, 3.81; N, 7.56. Found: C, 45.62; H, 3.49; N, 7.38.
4.1.3.7. N-[2-(2-thienyl)ethyl]-N-[(3-nitrophenyl)sulfonyl]glycine
(1g). White solid; yield 88%; mp 134e137 ꢁC; 1H NMR (CDCl3):
d
3.16 (t, J ¼ 7.1 Hz, 2H), 3.57 (t, J ¼ 7.1 Hz, 2H), 4.15 (s, 2H), 6.84 (s,
1H), 6.92 (t, J ¼ 4.2 Hz, 1H), 7.15 (d, J ¼ 5.1 Hz, 1H), 7.73 (t, J ¼ 4.0 Hz,
1H), 8.16 (d, J ¼ 7.7 Hz, 1H), 8.42 (d, J ¼ 8.0 Hz, 1H), 8.65 (s, 1H); 13C
NMR (DMSO-d6):
d 28.95, 48.91, 50.48, 122.37, 125.06, 126.39,
127.70, 128.02, 131.93, 133.72, 140.76, 141.84, 148.46, 170.87. ESIMS
m/z: 369.1 [M ꢃ H]ꢃ. Anal. calcd. for C14H14N2O6S2: C, 45.40; H,
3.81; N, 7.56. Found: C, 45.63; H, 3.53; N, 7.27.
4.1.3.1. N-[2-(2-thienyl)ethyl]-N-[(4-fluorophenyl)sulfonyl]glycine
(1a). White solid; yield 80%; mp 164e166 ꢁC; 1H NMR (CDCl3):
d
3.14 (t, J ¼ 7.3 Hz, 2H), 3.55 (t, J ¼ 7.4 Hz, 2H), 4.06 (s, 2H), 6.81 (d,
J ¼ 3.2 Hz, 1H), 6.95 (t, J ¼ 4.2 Hz, 1H), 7.19 (m, 3H), 7.86 (m, 2H); 13C
4.1.3.8. N-[2-(2-thienyl)ethyl]-N-[(1-naphthalenyl)sulfonyl]glycine
NMR (DMSO-d6):
d
29.17, 48.99, 50.52, 117.05 (d, JC-F ¼ 22.5 Hz),
(1i). White solid; yield 84%; mp 120e122 ꢁC; 1H NMR (CDCl3):
125.02, 126.28, 127.76, 130.70 (d, JC-F ¼ 9.5 Hz), 136.59 (d, JC-
d
3.01 (t, J ¼ 7.0 Hz, 2H), 3.67 (t, J ¼ 6.9 Hz, 2H), 4.16 (s, 2H), 6.68 (s,
¼ 3.0 Hz), 140.90, 165.05 (d, JC-F ¼ 249.6 Hz), 170.93. ESIMS m/z:
1H), 6.85 (m, 1H), 7.09 (d, J ¼ 4.9 Hz, 1H), 7.53e7.70 (m, 3H), 7.95 (d,
J ¼ 8.0 Hz, 1H), 8.08 (d, J ¼ 7.8 Hz, 1H), 8.30 (d, J ¼ 7.0 Hz, 1H), 8.60
F
342.0 [M ꢃ H]ꢃ. Anal. calcd. for C14H14FNO4S2: C, 48.97; H, 4.11; N,
4.08. Found: C, 48.74; H, 3.97; N, 4.31.
(d, J ¼ 8.2 Hz, 1H); 13C NMR (CDCl3):
d 29.10, 48.37, 50.15, 124.27,
124.36, 124.96, 125.74, 127.16, 127.20, 128.53, 128.76, 129.26, 130.17,
134.63, 134.67, 134.85, 140.10, 174.13. ESIMS m/z: 374.0 [M ꢃ H]ꢃ.
Anal. calcd. for C18H17NO4S2: C, 57.58; H, 4.56; N, 3.73. Found: C,
57.75; H, 4.21; N, 3.96.
4.1.3.2. N-[2-(2-thienyl)ethyl]-N-[(4-chlorophenyl)sulfonyl]glycine
(1b). White solid; yield 71%; mp 196e198 ꢁC; 1H NMR (DMSO-d6):
d
3.05 (t, J ¼ 7.7 Hz, 2H), 3.44 (t, J ¼ 7.7 Hz, 2H), 4.01 (s, 2H), 6.87 (s,1H),
6.94 (t, J ¼ 4.2 Hz, 1H), 7.33 (d, J ¼ 5.0 Hz, 1H), 7.64 (d, J ¼ 8.5 Hz, 2H),
7.82 (d, J ¼ 8.5 Hz, 2H); 13C NMR (DMSO-d6):
d
23.60, 49.15, 50.47,
4.1.3.9. N-[2-(2-thienyl)ethyl]-N-[(2-naphthalenyl)sulfonyl]glycine
125.03, 126.28, 127.76, 129.57, 130.00, 138.32, 139.13, 140.92, 170.92.
(1j). White solid; yield 74%; mp 121e123 ꢁC; 1H NMR (CDCl3):
ESIMS m/z: 358.0 [M ꢃ H]ꢃ, 360.0 [M ꢃ H]ꢃ. Anal. calcd. for C14H14
-
d
3.14 (t, J ¼ 7.6 Hz, 2H), 3.60 (t, J ¼ 7.2 Hz, 2H), 4.07 (s, 2H), 6.82 (s,
1H), 6.91 (m, 1H), 7.14 (m, 1H), 7.62 (m, 2H), 7.68 (m, 1H), 7.96 (m,
3H), 8.43 (s, 1H); 13C NMR (CDCl3):
29.61, 48.96, 50.68, 122.71,
ClNO4S2: C, 46.73; H, 3.92; N, 3.89. Found: C, 46.54; H, 3.78; N, 3.65.
d
4.1.3.3. N-[2-(2-thienyl)ethyl]-N-[(4-bromophenyl)sulfonyl]glycine
124.37, 125.89, 127.32, 127.80, 128.13, 128.97, 129.13, 129.52, 129.66,
132.29, 135.13, 136.40, 140.26, 173.84. ESIMS m/z: 374.1 [M ꢃ H]ꢃ.
Anal. calcd. for C18H17NO4S2: C, 57.58; H, 4.56; N, 3.73. Found: C,
57.84; H, 4.17; N, 3.49.
(1c). White solid; yield 74%; mp 189e190 ꢁC; 1H NMR (DMSO-d6):
d
3.05 (t, J ¼ 7.3 Hz, 2H), 3.45 (t, J ¼ 7.3 Hz, 2H), 4.04 (s, 2H), 6.87 (s,
1H), 6.93 (m, 1H), 7.32 (d, J ¼ 4.3 Hz, 1H), 7.76 (m, 4H); 13C NMR
(DMSO-d6):
d 29.18, 48.96, 50.25, 125.02, 126.29, 127.38, 127.72,
129.61, 132.96, 139.44, 140.85, 170.84. ESIMS m/z: 401.9 [M ꢃ H]ꢃ,
403.9 [M ꢃ H]ꢃ. Anal. calcd. for C14H14BrNO4S2: C, 41.59; H, 3.49; N,
3.46. Found: C, 41.75; H, 3.22; N, 3.67.
4.1.3.10. N-[2-(2-thienyl)ethyl]-N-[(5-dimethylamino-1 naphthalenyl)
sulfonyl]glycine (1k). Yellow solid; yield 64%; mp 113e115 ꢁC; 1H
NMR (CDCl3):
d
2.98e3.04 (m, 8H), 3.66 (t, J ¼ 7.4 Hz, 2H), 4.16 (s,
2H), 4.89 (br s, 1H), 6.69 (s, 1H), 6.86 (t, J ¼ 4.9 Hz, 1H), 7.10 (d,
4.1.3.4. N-[2-(2-thienyl)ethyl]-N-[(4-trifluoromethylphenyl)sulfonyl]
glycine (1d). White solid; yield 93%; mp 132e134 ꢁC; 1H NMR
J ¼ 4.3 Hz, 1H), 7.28 (m, 1H), 7.59 (m, 2H), 8.33 (m, 2H), 8.64 (d,
J ¼ 8.6 Hz, 1H); 13C NMR (CDCl3):
d 29.07, 45.69, 48.50, 50.19, 115.61,
(CDCl3):
d
3.14 (t, J ¼ 7.3 Hz, 2H), 3.57 (t, J ¼ 7.3 Hz, 2H), 4.08 (s, 2H),
119.74, 123.50, 124.21, 125.73, 127.19, 128.50, 130.14, 130.17, 130.21,
130.83, 134.87, 140.20, 151.64, 174.02. ESIMS m/z: 417.1 [M ꢃ H]ꢃ.
Anal. calcd. for C20H22N2O4S2: C, 57.39; H, 5.30; N, 6.69. Found: C,
57.52; H, 4.98; N, 6.43.
6.82 (s, 1H), 6.93 (t, J ¼ 4.2 Hz, 1H), 7.16 (d, J ¼ 5.0 Hz, 1H), 7.77 (d,
J ¼ 8.2 Hz, 2H), 7.95 (d, J ¼ 8.2 Hz, 2H); 13C NMR (CDCl3):
d 29.47,
48.61, 50.55, 124.56, 126.01, 126.39 (q, JC-F ¼ 7.2 Hz), 127.41, 128.01,
134.49, 134.82, 139.90, 143.21, 173.80. ESIMS m/z: 392.0 [M ꢃ H]ꢃ.
Anal. calcd. for C15H14F3NO4S2: C, 45.80; H, 3.59; N, 3.56. Found: C,
45.59; H, 3.21; N, 3.28.
4.1.3.11. N-[2-(2-thienyl)ethyl]-N-[(1,10-biphenyl)-4-sulfonyl]glycine
(1l). White solid; yield 70%; mp 137e139 ꢁC; 1H NMR (CDCl3):
d
3.15 (t, J ¼ 7.4 Hz, 2H), 3.58 (t, J ¼ 7.4 Hz, 2H), 4.05 (s, 2H), 6.83 (s,
4.1.3.5. N-[2-(2-thienyl)ethyl]-N-[(2-fluoro-4-bromophenyl)sulfonyl]
glycine (1e). White solid; yield 79%; mp 170e171 ꢁC; 1H NMR
1H), 6.93 (m, 1H), 7.17 (d, J ¼ 5.1 Hz, 1H), 7.14e7.52 (m, 3H), 7.62 (d,
J ¼ 6.9 Hz, 2H), 7.71 (d, J ¼ 8.3 Hz, 2H), 7.90 (d, J ¼ 8.3 Hz, 2H); 13C
(CDCl3):
d
3.13 (t, ¼ 7.1 Hz, 2H), 3.63 (t, J ¼ 7.1 Hz, 2H), 4.16 (s, 3H),
NMR (CDCl3): d 29.60, 48.96, 50.72, 124.40, 125.91, 127.35, 127.57,
6.81 (s, 1H), 6.92 (t, J ¼ 4.2 Hz, 1H), 7.16 (d, J ¼ 5.1 Hz, 1H), 7.34e7.43
127.91, 128.07, 128.78, 129.31, 138.04, 138.45, 140.29, 146.07, 174.48.
ESIMS m/z: 400.0 [M ꢃ H]ꢃ. Anal. calcd. for C20H19NO4S2: C, 59.83;
H, 4.77; N, 3.49. Found: C, 58.85; H, 4.81; N, 3.66.
(m, 2H), 7.77 (t, J ¼ 7.9 Hz, 1H); 13C NMR (CDCl3):
d 29.21, 48.84,
50.28, 121.02 (d, JC-F ¼ 24.4 Hz), 124.39, 125.88, 127.30, 127.44,
127.91 (d, JC-F ¼ 3.6 Hz), 128.61 (d, JC-F ¼ 9.4 Hz), 131.72, 140.13,
158.74 (d, JC-F ¼ 258.2 Hz), 174.36. ESIMS m/z: 419.9 [M ꢃ H]ꢃ, 421.9
[M ꢃ H]ꢃ. Anal. calcd. for C14H13BrFNO4S2: C, 39.82; H, 3.10; N, 3.32.
Found: C, 39.98; H, 2.86; N, 3.67.
4.1.3.12. N-(2-phenylethyl)-N-[(4-fluorophenyl)sulfonyl]glycine
(2a). White solid; yield 67%; mp 173e175 ꢁC; 1H NMR (CDCl3):
d
2.89 (t, J ¼ 7.6 Hz, 2H), 3.51 (t, J ¼ 7.6 Hz, 2H), 4.04 (s, 2H), 7.16 (m,
4H), 7.28 (m, 3H), 7.84 (m, 2H); 13C NMR (DMSO-d6):
d
34.83, 48.84,
4.1.3.6. N-[2-(2-thienyl)ethyl]-N-[(4-nitrophenyl)sulfonyl]glycine
50.47, 116.90 (d, JC-F ¼ 22.5 Hz), 127.00, 129.10, 129.34, 130.67 (d, JC-
(1f). White solid; yield 91%; mp 168e170 ꢁC; 1H NMR (CDCl3):
¼ 9.5 Hz), 136.68 (d, JC-F ¼ 3.0 Hz), 139.05, 165.02 (d, JC-
F
d
3.15 (t, J ¼ 7.2 Hz, 2H), 3.60 (t, J ¼ 7.2 Hz, 2H), 4.11 (s, 2H), 6.82 (s,
¼ 250.3 Hz), 170.99. ESIMS m/z: 336.1 [M ꢃ H]. Anal. calcd. for
F

224
A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
C16H16FNO4S: C, 56.96; H, 4.78; N, 4.15. Found: C, 56.58; H, 4.39, N,
4.23.
2H); 13C NMR (CDCl3):
d 21.77, 35.27, 48.73, 50.51, 126.92, 127.57,
128.91, 128.95, 129.91, 136.56, 138.18, 143.97, 174.28. ESIMS m/z:
332.0 [M ꢃ H]ꢃ. Anal. calcd. for C17H19NO4S2: C, 61.24; H, 5.74; N,
4.20. Found: C, 61.59; H, 5.96; N, 4.54.
4.1.3.13. N-(2-phenylethyl)-N-[(4-chlorophenyl)sulfonyl]glycine
(2b). White solid; yield 90%; mp 196e199 ꢁC; 1H NMR (DMSO-d6):
d
2.80 (t, J ¼ 7.8 Hz, 2H), 3.41 (t, J ¼ 7.8 Hz, 2H), 4.03 (s, 2H),
7.17e7.27 (m, 5H), 7.62 (d, J ¼ 8.5 Hz, 2H), 7.81 (d, J ¼ 8.5 Hz, 2H);
13C NMR (DMSO-d6):
34.61, 50.00, 55.55, 126.94, 129.09, 129.28,
4.1.3.20. N-benzyl-N-[(4-fluorophenyl)sulfonyl]glycine (3a). White
solid; yield 65%; mp 137e139 ꢁC; 1H NMR (CDCl3):
d
4.00 (s, 2H),
d
4.52 (s, 2H), 7.25e7.54 (m, 7H), 7.85 (m, 2H); 13C NMR (DMSO-d6):
129.57, 129.78, 137.90, 139.30, 139.63, 171.79. ESIMS m/z: 352.0
[M ꢃ H]ꢃ, 354.1 [M ꢃ H]ꢃ. Anal. calcd. for C16H16ClNO4S: C, 54.31; H,
4.56; N, 3.96. Found: C, 54.25; H, 4.62; N, 4.18.
d
48.04, 51.76, 116.95 (d, JC-F ¼ 22.6 Hz), 128.42, 128.89, 129.16,
130.85 (d, JC-F ¼ 9.5 Hz), 136.28, 136.82 (d, JC-F ¼ 249.4 Hz), 170.32.
ESIMS m/z: 321.9 [M ꢃ H]ꢃ. Anal. calcd. for C15H14FNO4S: C, 55.72;
H, 4.36; N, 4.33. Found: C, 55.93; H, 4.41; N, 4.27.
4.1.3.14. N-(2-phenylethyl)-N-[(4-bromophenyl)sulfonyl]glycine
(2c). White solid; yield 70%; mp 186e187 ꢁC; 1H NMR (CDCl3):
4.1.3.21. N-benzyl-N-[(4-chlorophenyl)sulfonyl]glycine (3b). White
d
2.92 (t, J ¼ 7.4 Hz, 2H), 3.53 (t, J ¼ 7.5 Hz, 2H), 4.06 (s, 2H), 7.17 (m,
solid; yield 52%; mp 148 ꢁC; 1H NMR (CDCl3):
d 4.00 (s, 2H), 4.52
2H), 7.30 (m, 3H), 7.62e7.71 (m, 4H); 13C NMR (DMSO-d6):
d
34.85,
(s, 2H), 7.27 (m, 2H), 7.30 (m, 3H), 7.53 (d, J ¼ 8.5 Hz, 2H), 7.86 (d,
48.81, 50.49, 127.00, 127.31, 129.09, 129.36, 129.61, 132.92, 139.01,
139.53, 170.88. ESIMS m/z: 395.9 [M ꢃ H]ꢃ, 397.9 [M ꢃ H]ꢃ. Anal.
calcd. for C16H16BrNO4S: C, 48.25; H, 4.05; N, 3.52. Found: C, 48.53;
H, 3.86; N, 3.84.
J ¼ 8.5 Hz, 2H); 13C NMR (DMSO-d6):
d 48.04, 51.79, 128.44,
128.90, 129.18, 129.72, 129.93, 136.24, 138.39, 139.24, 170.25.
ESIMS m/z: 337.9 [M ꢃ H]ꢃ, 339.9 [M ꢃ H]ꢃ. Anal. calcd. for
C15H14ClNO4S: C, 53.02; H, 4.15; N, 4.12. Found: C, 52.76; H, 3.85;
N, 4.33.
4.1.3.15. N-(2-phenylethyl)-N-[(4-trifluoromethylphenyl)sulfonyl]
glycine (2d). White solid; yield 86%; mp 148e149 ꢁC; 1H NMR
4.1.3.22. N-benzyl-N-[(4-bromophenyl)sulfonyl]-glycine (3c). White
(CDCl3):
d
2.91 (t, J ¼ 7.5 Hz, 2H), 3.55 (t, J ¼ 7.5 Hz, 2H), 4.07 (s, 2H),
solid; yield 93%; mp 156e158 ꢁC; 1H NMR (CDCl3):
d 4.00 (s, 2H),
7.15 (d, J ¼ 7.3 Hz, 2H) 7.28 (m, 3H), 7.74 (d, J ¼ 8.3 Hz, 2H), 7.93 (d,
4.52 (s, 2H), 7.27 (m, 2H), 7.36 (m, 3H), 7.69 (d, J ¼ 8.5 Hz, 2H), 7.78
J ¼ 8.2 Hz, 2H); 13C NMR (CDCl3):
d
35.17, 48.29, 50.35, 122.07,
(d, J ¼ 8.6 Hz, 2H); 13C NMR (DMSO-d6):
d 48.03, 51.78, 127.41,
124.78, 126.34 (q, JC-F ¼ 7.1 Hz), 127.11, 127.98, 128.93 (d, JC-
128.44, 128.90, 129.18, 129.78, 132.87, 136.23, 139.63, 170.24. ESIMS
m/z: 382.2 [M ꢃ H]ꢃ, 384.2 [M ꢃ H]ꢃ. Anal. calcd. for C15H14BrNO4S:
C, 46.89; H, 3.67; N, 3.65. Found: C, 46.53; H, 3.41; N, 3.89.
¼ 9.5 Hz), 134.58 (d, JC-F ¼ 33 Hz), 137.81, 143.25, 173.90. ESIMS m/
F
z: 386.0 [M ꢃ H]ꢃ. Anal. calcd. for C17H16F3NO4S: C, 52.71; H, 4.16;
N, 3.62. Found: C, 52.96; H, 4.28; N, 3.49.
4.1.3.23. N-benzyl-N-[(4-trifluoromethylphenyl)sulfonyl]glycine
4.1.3.16. N-(2-phenylethyl)-N-[(2-fluoro-4-bromophenyl)sulfonyl]
glycine (2e). White solid; yield 75%; mp 175e177 ꢁC; 1H NMR
(3d). White solid; yield 70%; mp 136 ꢁC; 1H NMR (CDCl3):
d 4.02 (s,
2H), 4.54 (s, 2H), 7.26 (m, 2H), 7.37 (m, 3H), 7.81 (d, J ¼ 8.2 Hz, 2H),
(CDCl3):
d
2.89 (t, J ¼ 7.4 Hz, 2H), 3.61 (t, J ¼ 7.3 Hz, 2H), 4.16 (s, 3H),
8.03 (d, J ¼ 8.1 Hz, 2H); 13C NMR (CDCl3):
d 46.54, 51.72, 126.36 (q,
JC-F ¼ 7.2 Hz), 128.10, 128.78, 128.82, 129.20, 134.28, 134.69 (d, JC-
7.13 (d, J ¼ 7.3 Hz, 2H), 7.23e7.41 (m 4H), 7.75 (t, J ¼ 7.9 Hz, 1H); 13C
NMR (CDCl3):
d
35.10, 48.27, 50.06, 120.99 (d, JC-F ¼ 24.7 Hz),126.99,
¼ 32.8 Hz), 173.98. ESIMS m/z: 372.0 [M ꢃ H]ꢃ. Anal. calcd. for
F
127.48 (d, JC-F ¼ 14.5 Hz), 127.88 (d, JC-F ¼ 3.7 Hz), 128.60 (d, JC-
C16H14F3NO4S: C, 51.47; H, 3.78; N, 3.75. Found: C, 51.64; H, 3.39; N,
3.64.
¼ 9.1 Hz), 128.86, 128.93, 131.64, 137.84, 158.72 (d, JC-F ¼ 257.5 Hz),
F
174.05. ESIMS m/z: 413.9 [M ꢃ H]ꢃ, 415.9 [M ꢃ H]ꢃ. Anal. calcd. for
C16H15BrFNO4S: C, 46.17; H, 3.63; N, 3.36. Found: C, 46.26; H, 3.39;
N, 3.65.
4.1.3.24. N-benzyl-N-[(2-fluoro-4-bromophenyl)sulfonyl]-glycine
(3e). White solid; yield 57%; mp 147e148 ꢁC; 1H NMR (CDCl3):
d
4.09 (s, 2H), 4.63 (s, 2H), 7.28 (m, 2H), 7.36e7.46 (m, 5H), 7.81 (t,
d 46.57, 51.71, 120.89 (d, JC-
¼ 24.6 Hz), 127.73 (d, JC-F ¼ 14.4 Hz), 127.95 (d, JC-F ¼ 3.6 Hz),
4.1.3.17. N-(2-phenylethyl)-N-[(4-nitrophenyl)sulfonyl]glycine
J ¼ 8.1 Hz, 1H); 13C NMR (CDCl3):
(2f). White solid; yield 60%; mp 168e170 ꢁC; 1H NMR (CDCl3):
F
d
2.92 (t, J ¼ 7.5 Hz, 2H), 3.56 (t, J ¼ 7.5 Hz, 2H), 4.08 (s, 2H), 7.15 (d,
128.67, 128.73, 128.82, 129.17, 131.62, 134.57, 158.96 (d, JC-
J ¼ 7.4 Hz, 2H), 7.28 (m, 3H), 7.96 (d, J ¼ 8.7 Hz, 2H), 8.30 (d,
¼ 257.7 Hz), 174.05. ESIMS m/z: 399.9 [M ꢃ H]ꢃ, 401.0 [M ꢃ H]ꢃ.
F
J ¼ 8.7 Hz, 2H); 13C NMR (DMSO-d6):
d
34.75, 48.80, 50.53, 125.10,
Anal. calcd. for C15H13BrFNO4S: C, 44.79; H, 3.26; N, 3.48. Found: C,
44.85; H, 3.08; N, 3.59.
127.02, 129.07, 129.18, 129.40, 138.89, 145.75, 150.28, 170.75. ESIMS
m/z: 363.0 [M ꢃ H]ꢃ. Anal. calcd. for C16H16N2O6S: C, 52.74; H, 4.43;
N, 7.69. Found: C, 52.48; H, 4.13, N, 7.47.
4.1.3.25. N-benzyl-N-[(4-nitrophenyl)sulfonyl]glycine
(3f). White
4.05 (s, 2H),
solid; yield 76%; mp 157e159 ꢁC; 1H NMR (CDCl3):
d
4.1.3.18. N-(2-phenylethyl)-N-[(3-nitrophenyl)sulfonyl]glycine
4.56 (s, 2H), 7.30e7.37 (m, 5H), 8.08 (d, J ¼ 8.6 Hz, 2H), 8.40 (d,
(2g). White solid; yield 63%; mp 157e158 ꢁC; 1H NMR (CDCl3):
J ¼ 8.3 Hz, 2H); 13C NMR (DMSO-d6):
d 48.20, 51.94, 125.04, 128.55,
d
2.94 (t, J ¼ 7.4 Hz, 2H), 3.56 (t, J ¼ 7.4 Hz, 2H), 4.15 (s, 2H), 7.19 (d,
128.95, 129.24, 129.42, 135.97, 145.86, 150.35, 170.12. ESIMS m/z:
349.0 [M ꢃ H]ꢃ. Anal. calcd. for C15H14N2O6S: C, 51.42; H, 4.03; N,
8.00. Found: C, 51.76; H, 3.93; N, 8.31.
J ¼ 7.6 Hz, 2H), 7.26 (m, 3H), 7.72 (t, J ¼ 8.0 Hz, 1H), 8.15 (d,
J ¼ 8.0 Hz,1H), 8.43 (d, J ¼ 8.3 Hz,1H), 8.65 (s,1H); 13C NMR (DMSO-
d6):
d 34.63, 48.77, 50.41, 122.34, 126.97, 127.97, 129.02, 129.38,
131.87, 133.72, 138.92, 141.95, 148.44, 170.92. ESIMS m/z: 362.9
[M ꢃ H]ꢃ. Anal. calcd. for C16H16N2O6S: C, 52.74; H, 4.43; N, 7.69.
Found: C, 52.99; H, 4.72; N, 7.55.
4.1.3.26. N-benzyl-N-[(3-nitrophenyl)sulfonyl]glycine
(3g). White
4.09 (s, 2H),
solid; yield 60%; mp 125e127 ꢁC; 1H NMR (CDCl3):
d
4.53 (s, 2H), 7.29 (m, 2H), 7.37 (m, 3H), 7.77 (t, J ¼ 8.0 Hz, 1H), 8.23
(d, J ¼ 7.8 Hz, 1H), 8.45 (d, J ¼ 8.3 Hz, 1H), 8.73 (s, 1H); 13C NMR
4.1.3.19. N-(2-phenylethyl)-N-[(4-methylphenyl)sulfonyl]glycine
(DMSO-d6): d 48.52, 51.99, 122.60, 128.02, 128.48, 128.97, 129.18,
(2h). White solid; yield: 69%; mp 141e143 ꢁC; 1H NMR (CDCl3):
131.86, 133.93, 135.97, 142.08, 148.35, 170.37. ESIMS m/z: 348.9
[M ꢃ H]ꢃ. Anal. calcd. for C15H14N2O6S: C, 51.42; H, 4.03; N, 8.00.
Found: C, 51.30; H, 3.78; N, 8.23.
d
2.45 (s, 3H), 2.90 (t, J ¼ 7.8 Hz, 2H), 3.51 (t, J ¼ 7.8 Hz, 2H), 4.03 (s,
2H), 7.16 (d, J ¼ 7.1 Hz, 2H), 7.25e7.32 (m, 5H), 7.74 (d, J ¼ 8.1 Hz,

A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
225
4.1.3.27. N-benzyl-N-[(4-methylphenyl)sulfonyl]glycine (3h). White
solid; yield 80%; mp 120e122 ꢁC [Lit 192e194 ꢁC] [17b]; 1H NMR
and 10 nM. Epalrestat (100
m
Me1 nM) was used as the reference
standard. The determination of the IC50 values was performed by
linear regression analysis of the log doseeresponse curve, which
was generated using at least five concentrations of the inhibitor
causing an inhibition between 20% and 80%. Results are expressed
as means ꢀ SEM of percentage inhibition values, obtained through
two determinations carried out in triplicate.
(CDCl3):
d 2.46 (s, 3H), 3.95 (s, 2H), 4.49 (s, 2H), 7.23e7.35 (m, 7H),
7.79 (d, J ¼ 8.2 Hz, 2H); 13C NMR (CDCl3):
d 21.82, 46.57, 51.59,
127.68, 128.53, 128.87, 129.07, 129.91, 134.87, 136.74, 144.07, 174.70.
ESIMS m/z: 318.0 [M ꢃ H]ꢃ. Anal. calcd. for C16H17NO4S: C, 60.17; H,
5.37; N, 4.39. Found: C, 59.86; H, 5.11; N, 4.23.
4.1.3.28. N-benzyl-N-[(2-napthalenyl)sulfonyl]glycine
(3j). White
3.97 (s, 2H),
4.2.4. Modeling studies
solid; yield 75%; mp 149e150 ꢁC; 1H NMR (CDCl3):
d
4.2.4.1. AD4 docking calculations. The new version of the docking
program AutoDock (version 4, AD4) [23] as implemented through
the graphical user interface called AutoDockTools (ADT), was used
to dock 1f, 1g, 1j, 3g and 3h. Such a program has been successfully
used in studying the ligandeprotein as well as the ligandeDNA
interactions [24]. Ligand structures were built using the builder in
the Maestro package of Schroedinger Suite 2007 and optimized
using a version of MacroModel also included. The constructed
compounds and the receptor structure were converted to AD4
format files using ADT generating automatically all other atom
values. The docking area was centered around the enzyme active
site. A set of grids of 60 Å ꢂ 60 Å ꢂ 60 Å with 0.375 Å spacing was
calculated around the docking area for the ligand atom types using
AutoGrid4. For each ligand, 100 separate docking calculations were
performed. Each docking calculation consisted of 10 million energy
evaluations using the Lamarckian genetic algorithm local search
(GALS) method. The GALS method evaluates a population of
possible docking solutions and propagates the most successful
individuals from each generation into the subsequent generation of
possible solutions. A low-frequency local search according to the
method of Solis and Wets is applied to docking trials to ensure that
the final solution represents a local minimum. All dockings
described in this paper were performed with a population size of
250, and 300 rounds of Solis and Wets local search were applied
with a probability of 0.06. A mutation rate of 0.02 and a crossover
rate of 0.8 were used to generate new docking trials for subsequent
generations, and the best individual from each generation was
propagated over the next generation. The docking results from each
of the 100 calculations were clustered on the basis of root-mean
square deviation (rmsd) (solutions differing by less than 2.0 Å)
between the Cartesian coordinates of the atoms and were ranked
4.55 (s, 2H), 7.21 (m, 5H), 7.60e7.65 (m, 2H), 7.84e7.96 (m, 4H), 8.47
(s, 1H); 13C NMR (CDCl3):
d
46.81, 51.63, 122.90, 127.76, 128.14,
128.47, 128.87, 129.03, 129.10, 129.52, 129.56, 129.60, 132.28, 134.91,
135.12, 136.66, 173.91. ESIMS m/z: 354.0 [M ꢃ H]ꢃ. Anal. calcd. for
C19H17NO4S: C, 64.21; H, 4.82; N, 3.94. Found: C, 64.35; H, 4.93; N,
3.76.
4.2. Biology
4.2.1. Materials and methods
Aldose reductase (ALR2) and aldehyde reductase (ALR1) were
obtained from Sprague Dawley albino rats, 120e140 g b.w.,
supplied by Harlan Nossan, Italy. Enzymes preparation was carried
out as previously reported [18].
NADPH and D,L-glyceraldehyde were from SigmaeAldrich.
Epalrestat was from Haorui Pharma-Chem Inc. All other chem-
icals were of reagent grade.
4.2.2. Enzymatic assays
The activity of the two test enzymes was determined spectro-
photometrically by monitoring the change in absorbance at
340 nm, which is due to the oxidation of NADPH catalyzed by ALR2
and ALR1. The change in pyridine coenzyme concentration/min was
determined using a Beckman DU-64 kinetics software program
(Solf Pack TM Module).
ALR2 activity was assayed at 30 ꢁC in a reaction mixture con-
taining 0.25 mL of 10 mM D,L-glyceraldehyde, 0.25 mL of 0.104 mM
NADPH, 0.25 mL of 0.1 M sodium phosphate buffer (pH 6.2), 0.1 mL
of enzyme extract and 0.15 mL of deionized water in a total volume
of 1 mL. All the above reagents, except D,L-glyceraldehyde, were
incubated at 30 ꢁC for 10 min; the substrate was then added to start
the reaction, which was monitored for 5 min. Enzyme activity was
calibrated by diluting the enzymatic solution in order to obtain an
average reaction rate of 0.011 ꢀ 0.0010 absorbance units/min for
the sample.
on the basis of free energy of binding (
DGAD4). The top-ranked
compounds were visually inspected for good chemical geometry.
Since AD4 does not perform any structural optimization and energy
minimization of the complexes found, a molecular mechanics/
energy minimization (MM/EM) approach was applied to refine the
AD4 output. The computational protocol applied consisted of the
application of 100,000 steps of the PolakꢃRibiére conjugate
gradients (PRCG) or until the derivative convergence was 0.05 kJ/
mol. All complexes pictures were rendered employing the UCSF
Chimera software [25].
ALR1 activity was determined at 37 ꢁC in a reaction mixture
containing 0.25 mL of 20 mM sodium D-glucuronate, 0.25 mL of
0.12 mM NADPH, 0.25 mL of dialyzed enzymatic solution and
0.25 mL of 0.1 M sodium phosphate buffer (pH 7.2) in a total volume
of 1 mL. The enzyme activity was calibrated by diluting the dialyzed
enzymatic solution in order to obtain an average reaction rate of
0.015 ꢀ 0.0010 absorbance/min for the sample.
Appendix. Supplementary material
4.2.3. Enzymatic inhibition
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.ejmech.2012.02.045.
The inhibitory activity of the newly synthesized compounds
against ALR2 and ALR1 was assayed by adding 0.1 mL of the inhibitor
solution to the reaction mixture described above. All the inhibitors
were solubilized in water and the solubility was facilitated by
adjustment to a favorable pH. After complete solution, the pH was
readjusted to 7. To correct for the non-enzymatic oxidation of NADPH
and for absorption by the compounds tested, a reference blank con-
taining all the above assay components except the substrate was
prepared. The inhibitory effect of the new derivatives was routinely
References
[1] (a) A.F. Amos, D.J. McCarty, P. Zimmet, Diabet. Med. 14 (1997) S7eS85;
(b) P. Zimmet, K.G.M.M. Alberti, J. Shaw, Nature 4 (2001) 782e787.
[2] H. King, R.E. Aubert, W.H. Herman, Diabetes Care 21 (1998) 1414e1431.
[3] C.L. Triplitt, C.A. Reasner, W.L. Isley, in: R. Di Pirio, L. Talbert, G.C. Yee (Eds.),
Pharmacotherapy:
2005, p. 1361.
A Pathophysiologic Approach, McGrawHill, New York,
estimated at a concentration of 100
be active were tested at additional concentrations between 10
mM. Those compounds found to
[4] J.A. Scott, G.L. King, Ann. N. Y. Acad. Sci. 1031 (2004) 204e213.
[5] M. Brownlee, Nature 414 (2001) 813e820.
mM

226
A. Ramunno et al. / European Journal of Medicinal Chemistry 51 (2012) 216e226
[6] J.M. Jez, M.J. Bennett, B.P. Schlegel, M. Lewis, T.M. Penning, Biochem. J. 326
(1997) 625e636.
[17] (a) S.M. Dankwardt, D.B. Smith Jr., J.A. Porco, C.H. Nguyen, Synlett 7 (1997)
854e856;
[7] D.L. Vander Jagt, N.S. Kolb, T.J. Vander Jagt, J. Chino, F.J. Marlinez,
L.A. Hunsaker, R.E. Royer, Biochim. Biophys. Acta 1249 (1995) 117e126.
[8] A.M. Vincent, J.W. Russell, P. Low, E.L. Feldman, Endocr. Rev. 25 (2004) 612e628.
[9] (a) S.K. Srivastava, K.V. Ramana, A. Bhatnagar, Endocr. Rev. 26 (2005)
380e392;
(b) T.P. Degenhardt, S.R. Thorpe, J.W. Baynes, Cell. Mol. Biol. 44 (1998)
1139e1145.
[10] (a) S.K. Srivastava, U.C. Yadav, A.B. Reddy, A. Saxena, R. Tammali, M. Shoeb,
N.H. Ansari, A. Bhatnagar, M.J. Petrash, S. Srivastava, K.V. Ramana, Chem. Biol.
Interact. 191 (2011) 330e338;
(b) R.Tammali, A.B.Reddy, A.Saxena, P.G.Rychahou, M.B.Evers, S.Qiu, S.Awas-
thi, K.V.Ramana, S.K. Srivastava Carcinogenesis, (in press).
[11] (a) F. Da Settimo, G. Primofiore, C. La Motta, S. Sartini, S. Taliani, F. Simorini,
A.M. Marini, A. Lavecchia, E. Novellino, E. Boldrini, J. Med. Chem. 48 (2005)
6897e6907;
(b) A. Scozzafava, C.T. Supuran, Eur. J. Med. Chem. 35 (2000) 299e307.
[18] C. La Motta, S. Sartini, S. Salerno, F. Simorini, S. Taliani, A.M. Marini, F. Da
Settimo, L. Marinelli, V. Limongelli, E. Novellino, J. Med. Chem. 51 (2008)
3182e3193.
[19] (a) M. Schlitzer, M. Bohm, I. Sattler, H.-M. Dahse, Bioorg. Med. Chem. 8 (2000)
1991e2006;
(b) K. Kettler, J. Sakowski, J. Wiesner, R. Ortmann, H. Jomaa, M. Schlitzer,
Pharmazie 60 (2005) 323e327;
(c) S.S. Kinderman, M.T. Wekking, Jan H. van Maarseveen, H.E. Schoemaker,
H. Hiemstra, F.P.J.T. Rutjes, J. Org. Chem. 70 (2005) 5519e5527;
(d) T. Inoue, M. Ohmi, K. Kawamura, K. Ando, Y.Shishido PCT Int. Appl. WO
2010-JP3121. (e) F. Shi, M.K. Tse, S. Zhou, M.-M. Pohl, J. Radnik, S. Huebner,
K. Jaehnisch, A. Brueckner, M. Beller, J. Am. Chem. Soc. 131 (2009)
1775e1779;
(f) M. Zhu, K. Fujita, R. Yamaguchi, Org. Lett. 12 (2010) 1336e1339;
(g) F. Shi, M.-K. Tse, X. Cui, D. Goerdes, D. Michalik, K. Thurow, Y. Deng,
M. Beller, Ang. Chem. Int. Ed. 48 (2009) 5912e5915;
(b) F. Da Settimo, G. Primofiore, A. Da Settimo, C. La Motta, F. Simorini,
E. Novellino, G. Greco, A. Lavecchia, F. Boldrini, J. Med. Chem. 46 (2003)
1419e1428;
(c) P. Alexiou, K. Pegklidou, M. Chatzopoulou, I. Nicolaou, V.J. Demopoulos,
Curr. Med. Chem. 16 (2009) 734e752;
(d) O. El-Kabbani, V. Carbone, C. Darmanin, M. Oka, A. Mitschler, A. Podjarny,
C. Schulze-Briese, R.P.-T. Chung, J. Med. Chem. 48 (2005) 5536e5542;
(e) K.E. Schemmel, R.S. Padiyara, J.J. D’Souza, J. Diabet. Complications 24
(2010) 354e360.
(h) M. Harmata, P. Zheng, C. Huang, M.G. Gomes, W. Ying, K.-O. Ranyanil,
G. Balan, N.L. Calkins, J. Org. Chem. 72 (2007) 683e685;
(i) T. Kataoka, T. Iwama, T. Setta, A. Takagi, Synthesis 4 (1998) 423e426.
[20] P.J. DeChristopher, J.P. Adamek, G.D. Lyon, S.A. Klein, R.J. Baumgarten, J. Org.
Chem. 39 (1974) 3525e3532.
[21] M.K. Ghorai, A. Kumar, D.P. Tiwari, J. Org. Chem. 75 (2010) 137e151.
[22] B. Nyasse, L. Grehn, U. Ragnarsson, H.L.S. Maia, L.S. Monteiro, L. Leito,
J. Koppel, J. Chem. Soc. Perkin Trans. 1 (1995) 2025e2031.
[23] R. Huey, G.M. Morris, A.J. Olson, D.S. Goodsell, J. Comput. Chem. 28 (2007)
1145e1152.
[12] M. Cappiello, M. Voltarelli, I. Cecconi, P.G. Vilardo, M. Dal Monte, A. Del Corso,
D.K. Wilson, F.A. Quiocho, J.M. Petrash, U. Mura, J. Biol. Chem. 271 (1996)
33539e33544.
[13] C.E. Grimshaw, C.J. Lai, Arch. Biochem. Biophys. 327 (1996) 89e97.
[14] S. Cosconati, L. Marinelli, C. La Motta, S. Sartini, F. Da Settimo, A.J. Olson,
E. Novellino, J. Med. Chem. 52 (2009) 5578e5581.
[15] E.I. Howard, R. Sanishvili, R.E. Cachau, A. Mitschler, B. Chevrier, P. Barth,
V. Lamour, M. Van Zandt, E. Sibley, C. Bon, D. Moras, T.R. Schneider,
A. Joachimiak, A. Podjarny, Proteins 55 (2004) 792e804.
[16] H. Steuber, P. Czodrowski, C.A. Sotriffer, G. Klebe, J. Mol. Biol. 373 (2007)
1305e1320.
[24] (a) D. Simoni, N. Gebbia, F.P. Invidiata, M. Eleopra, P. Marchetti, R. Rondanin,
R. Baruchello, S. Provera, C. Marchioro, M. Tolomeo, L. Marinelli, V. Limongelli,
E. Novellino, A. Kwaasi, J. Dunford, S. Buccheri, N. Caccamo, F. Dieli, J. Med.
Chem. 51 (2008) 6800e6807;
(b) S. Cosconati, L. Marinelli, R. Trotta, A. Virno, L. Mayol, E. Novellino,
A.J. Olson, A. Randazzo, J. Am. Chem. Soc. 45 (2009) 16336e16337.
[25] E.F. Pettersen, T.D. Goddard, C.C. Huang, G.S. Couch, D.M. Greenblatt,
E.C. Meng, T.E. Ferrin, J. Comput. Chem. 25 (2004) 1605e1612.