Design, synthesis, and anticonvulsant activity of some sulfamides

Article abstract of DOI:10.1016/j.bmc.2007.05.024

As part of our search for potential anticonvulsant agents, a set of compounds were designed, synthesized, and evaluated against MES and PTZ tests. Bioisosteric functional group information was used to design a new functionality, sulfamides, that complies with the requirements of the pharmacophore previously defined. Some of the molecules showed a promising anticonvulsant profile as selective anti-MES drugs, being active at low concentrations (30 mg/kg). The biological data were confirmed in Phase II of the Anticonvulsant Drug Development Program of the National Institute of Health.

Full text of DOI:10.1016/j.bmc.2007.05.024

Bioorganic & Medicinal Chemistry 15 (2007) 5604–5614
Design, synthesis, and anticonvulsant activity of some sulfamides
L. Gavernet, I. A. Barrios, M. Sella Cravero and L. E. Bruno-Blanch*
Medicinal Chemistry, Department of Biological Sciences, National University of La Plata, 47 and 115, La Plata B1900BJW, Argentina
Received 26 September 2006; revised 9 May 2007; accepted 10 May 2007
Available online 17 May 2007
Abstract—As part of our search for potential anticonvulsant agents, a set of compounds were designed, synthesized, and evaluated
against MES and PTZ tests. Bioisosteric functional group information was used to design a new functionality, sulfamides, that com-
plies with the requirements of the pharmacophore previously defined. Some of the molecules showed a promising anticonvulsant
profile as selective anti-MES drugs, being active at low concentrations (30 mg/kg). The biological data were confirmed in Phase
II of the Anticonvulsant Drug Development Program of the National Institute of Health.
ꢀ
2007 Elsevier Ltd. All rights reserved.
1
. Introduction
The necessity for novel compounds with high potency
and specificity, as well as low toxicity, is also evidenced
by inspection of the marketed AED. Classical AED are
Epilepsy is not a specific disease, but a syndrome origi-
nated by different cerebral disorders of the central ner-
vous system. It is characterized by excessive
discharges of large number of neurons, that alter the
not ideal, and they present significant side effects in some
7–9
1
cases.
Recently, second generation AED were intro-
duced, but their efficacy is similar to classical AED
and they also have considerable adverse effects in several
2
brain’s normal electrochemical balance.
8
,9
cases.
Epileptic episodes are called seizures and have different
manifestations, ranging from brief lapses of lack of
attention to limited motor, sensory, or psychological
changes. In severe cases they include prolonged losses
The mechanism of action of AED is not always related
with a specific binding site, and most of the drugs inter-
act with more than one receptor. For that reason, it is
difficult to define a rigorous classification of AED
according to their mode of action. However, some of
the cellular mechanisms involved are: potentiation of
3
of consciousness with convulsive motor activity.
Researchers have concentrated their actions in develop-
ing therapies to control and prevent these seizures,
mainly with the use of medications. However, several
epileptic episodes cannot be controlled by currently
available antiepileptic drugs (AED), since 25% of
patients continue to have epileptic episodes despite opti-
mal therapy. Moreover, AED treatment is usually neces-
sary for several years and side effects may appear. Some
1
0
GABA-ergic transmission, blockade of voltage gated
1
1
sodium channel (VGSC), attenuation of excitatory
1
1–13
neurotransmission,
sensitive calcium channels.
and/or modulation of voltage-
1
4
Two main strategies have been employed to design new
AED: the search of new compounds that cause a modi-
fication of a certain stage of the cellular mechanism
(mechanism-based design) and the optimization of pre-
existing compounds (structure-based design). Some of
4
of them are detected immediately after drug exposure
and others are reversible by means of reduction of the
dose. However, chronic side effects appear only after
extended periods of treatment, and most of them are
the new generation AED have been developed following
15–17
5
,6
not dose-related.
these approaches.
Additionally, the use of new ani-
mal models of epilepsy (genetic or kindled models) has
demonstrated the efficacy and safety of a new com-
pound, levetiracetam, which presents a new mechanism
1
5
of action.
Keywords: Sulfamides; Anticonvulsant; Rational design; Bioisosteres;
Pharmacophore.
*
Corresponding author. Tel.: +54 02214235333; fax: +54
2214223409; e-mail: lbb@biol.unlp.edu.ar
However, among the experimental models developed to
evaluate the anticonvulsant activity, conventional acute
0
0
968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.05.024

L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
5605
seizure models are the most widely used. The maximal
electroshock (MES) test and the subcutaneous pentylen-
in absence of seizures, has been included as an inactive
analog; because it is inactive against MES test.
23
1
8
etetrazole (PTZ) test are the most popular. Related to
the biological target, AED that have a good response to
VGSC are active in MES test. Additionally, it is
accepted that active drugs against the MES test and
inactive against PTZ test present a pharmacological
profile analogous to phenytoin (PHE), and are named
We have used the knowledge acquired in the preceding
research about the active conformation determined by
the pharmacophore (Fig. 1). We have focused on the
design of sulfamides as novel ligands with anti-MES
activity, as part of our search for potential anticonvul-
1
9,20
27
phenytoin-like compounds.
sant agents.
Over the years we and other authors have advanced in
the knowledge of the molecular requirements of AED
associated with ligands that act through interactions
that cause this in-vivo profile. Since the knowledge of
the mechanism of action of this kind of ligands is not
straightforward, research on the origin of the activity
is centered on the analysis of the active compounds.
Accordingly, several pharmacophoric models have been
developed from different methodologies mainly associ-
ated with the comparison of structures and QSAR anal-
It may be interesting to examine whether different com-
pounds bearing this functionality reflect the conditions
derived from the previous pharmacophore model. The
results demonstrated the high quality of the pharmaco-
phore pattern proposed, and their ability to predict the
activity of the designed compounds.
Considered an attractive target for medicinal chemists,
sulfamides have been studied as HIV protease inhibi-
2
8,29
30
tors,
ponents in epinephrine analogs,
agonists of the 5-HTID receptor, active com-
31
2
1–27
ysis.
non-hydrolyzable
components of peptide-mimetics, and carbonic anhy-
drase inhibitors.
functionality as the result of the bioisosteric replacement
3
2
3
3–35
One of them has recognized a common pattern based on
the examination of 12 dissimilar compounds with anti-
MES activity, and the crucial electronic and structural
Recently we have considered this
2
7
for the polar portion of the pharmacophore. For a
quantitative verification of the presence of the pharma-
cophore polar end, the electronic characteristics of one
set of sulfamides were compared with the pharmaco-
phore corresponding atoms in AED. The set includes
sulfamides and sulfamide derivatives containing differ-
ent hydrocarbon chains. The compounds were synthe-
sized and anticonvulsant evaluations were performed.
2
3
features were identified.
This previous discussion
allowed the authors to define the 3D requirements for
the structures to manifest the anti-MES activity. They
can be summarized in: (1) a hydrophobic chain (atoms
5
placed in a well defined conformation.
–7, Fig. 1), (2) a polar moiety (atoms 1–3, Fig. 1);
2
7
From this study, new active compounds derived from
valpromides have been designed, synthesized, and eval-
2
3
uated. The training set of AED used to define these
requirements included models for structurally different
classes of compounds with similar action in the experi-
mental anticonvulsant model, MES test (Fig. 2). It com-
prised classical drugs, new generation ones, and
compounds that have overcome the development stage.
Most of them showed a PHE-like profile being active
against the MES test and inactive against PTZ. Drugs
like felbamate (FLB), remacemide (RMC), ethosuxi-
mide (ETH), and vinpocentine (VIN) are also active in
the PTZ test. ETH, one of the major antiepileptics used
2. Results and discussion
2.1. Pharmacophore polar end
We have based the criterion of considering different
chemical functions for the pharmacophore polar end
in the ability of their atoms to fulfill the requirements
defined for this portion.
First, we have considered some of the compounds in-
cluded in the training set used to define the pharmaco-
phore (Fig. 2). The compounds were selected so their
functionalities were varied. Charges among the atomic
centers of the polar end have been calculated by means
of density functional calculation GAUSSIAN 98
3
6
**
(
G98), using B3LYP functional and 6-31 G basis.
The electronic distribution was derived from calculated
potentials (Chelp G). The results are given in Table 1.
The organic functions considered were detailed. As
expected, the results correlated with the charge distribu-
tion defined in the pharmacophore: a negative end
distributed among two atomic centers defined by N or
O, and a positive end centered in a C or S atom.
Then, we have incorporated the sulfamide function to
the set. By inspection of the atoms that defined the polar
moiety of the pharmacophore (numbered 1–3 in Fig. 1),
we can assign a bioisosteric equivalence between the
functions involved. In other words, bioisosteres
Figure 1. Structure of the pharmacophore previously proposed.

5606
L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
NH2
O S O
O
NH2
O S O
O
H
N
O
NH2
O
O
HO
O
N
O
HN
O
N
O
O
O
O
O
CZ
PHE
VPA
TOP
ZON
H N
2
O
NH2
Cl
N
N
N
NH
O
2
N
O
NH
N
N
H N
2
N
S
7
Cl
Cl
F
F
N
O
RAL
LAM
RUF
OCZ
O
O
O
O
O
O
NH2
HN
H N
H
N
2
O
O
O
N
N
H N
N
2
FLB
RMC
ETH
VIN
Figure 2. Structures of the antiepileptic drugs that are active in the MES test and used to define the training set.
Table 1. Electronic distribution among the pharmacophore polar end
Compound
Function
Q
1
Q
2
Q
3
Compound
Function
Q
1
Q
2
Q
3
CZ
Urea
Amide
Acid
ꢀ0.563
ꢀ0.488
ꢀ0.559
ꢀ0.583
ꢀ0.551
ꢀ0.481
ꢀ0.518
ꢀ0.542
ꢀ0.487
ꢀ0.470
ꢀ0.468
ꢀ0.492
0.905
0.568
0.633
0.911
1.433
0.957
0.742
0.850
1.120
1.018
0.981
0.991
ꢀ0.928
ꢀ0.652
ꢀ0.535
ꢀ0.937
ꢀ1.043
ꢀ0.870
ꢀ0.468
ꢀ0.940
ꢀ0.721
ꢀ0.850
ꢀ0.615
ꢀ0.722
5a
6a
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
Sulfamide
ꢀ0.475
ꢀ0.464
ꢀ0.464
ꢀ0.466
ꢀ0.496
ꢀ0.460
ꢀ0.459
ꢀ0.454
ꢀ0.460
ꢀ0.489
ꢀ0.491
ꢀ0.486
ꢀ0.474
0.927
0.897
0.895
1.021
0.931
0.925
0.923
0.942
0.977
1.014
0.949
0.947
0.965
ꢀ0.285
ꢀ0.437
ꢀ0.433
ꢀ0.729
ꢀ0.724
ꢀ0.575
ꢀ0.859
ꢀ0.639
ꢀ0.648
ꢀ0.868
ꢀ0.764
ꢀ0.805
ꢀ0.807
PHE
VPA
FLB
TOP
ZON
VIN
OCZ
7a
8a
Carbamate
Sulfamate
Sulfonamide
Ester
9a
10b
11b
12b
13b
14c
15c
16c
Urea
1a
2a
3a
4a
Sulfamide
Sulfamide
Sulfamide
Sulfamide
1
7c
2
7,40
comprise the polar end in the pharmacophore definition
for anti-MES activity.
ties in MES test.
Their ability to comply with the
requirements of the pharmacophore pattern has been
demonstrated before, using the sulfate function as the
2
7,41
Groups CH, O, and NH are isosteres according to
3
polar end.
7–39
Grimm’s hydride displacement law.
sulfones are recognized as nonclassical bioisosteres suit-
Sulfoxides and
After defining this new functionality, seventeen sulfa-
mide derivatives have been selected and their atomic
charges have been calculated at the same level of theory.
The set includes mono-substituted sulfamides, di-substi-
tuted sulfamides, tetra-substituted sulfamides, and sul-
fonyl carbamates (Fig. 4).
3
9
able to replace a carbonyl group. The replacement of
the carbonyl group by a sulfoxide, and the substitution
of the groups CH and O by NH generate the sulfamide
functionality as a result of the bioisosteric replacement
(
Fig. 3).
Another function related may be sulfate (Fig. 3). This
functionality is included in active molecules like topira-
mate derivatives, which present anticonvulsant proper-
The analysis reveals that the charge distribution around
the atoms that define the pharmacophore polar end re-
mains constant in all sulfamides: the negative charges

L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
5607
O
O
O
O
O
S
O
S
O
S
O
S
C
N
N
O
C
O
N
N
C
N
N
O
O
O
N
N
O
O
O
O
amide carbamate
ester
urea
sulfonamide sulfamate
sulfate
sulfamide
Figure 3. Chemical functions involved in the pharmacophore polar end of the antiepileptic drugs used in the training set. Sulfamide and sulfate
functions were included.
1
O
1
1
O
1
O
4
2
S
O
2
S
7
O
O 5
O
7
5
O
5
2
S
S
6
N
N
3
6
N
H
N
H
3
4
3
1
N
H
N
H
4
3
2
4
H
H
6
7
N
N
5
7
6
H
H
1
a
2a
3a
4a
1
O
1
1
2
S
2
O
2
5
7
O
2
5
7
O
7
O
O
O
N
6
O
N
5
6
S
4
N3S
N3S
3
N
N
4
4
4
N
3
H
6
N
H
5
O
O 7
5
a
6
6a
7a
8a
3
1
O
O
O
1
O
1
1
O
O 5 6 7
7
2
S
O
O 5
O
2
S
O
N
5
O
7
S
5
6
6
S
N
H
N
4
N
3
2
N
N
N
H
N
O
4
O
3
4
O
4
H
2
H
3
H
H
6
H
7
9
a
1
0 b
11b
12b
1
1
O
N4
O
1
5
7
1
O
4N
1
O
O
O 5
2
S
7
5
7
2
S
5
2
S
O
6
O
2
O
2
S
O
O
N4
6
6
6
5
7
S
4
H N
N
4
H N
H N
O
N
3
2
3
2
2
3
3
H N
2
N
H
7
H
3
H
6
1
4c
15c
16c
17c
1
3b
Figure 4. Structures of the sulfamides synthesized and evaluated. Atoms are numbered for the centers that are implicated in the pharmacophoric
pattern.
are distributed among one N and O atoms, whereas the
positive center is focused on the S atom.
SO Cl
O O
S
2
2
R R NH
+ N R R .HCl
1 2
1
2
(excees)
R R
CH Cl
2
1
R R
1
2
2
2
1-9
In the model, the anti-MES biological response is con-
tingent on the presence of the polar fragment. The com-
pounds should also contain a hydrophobic region
consistent with the non-polar portion of the pharmaco-
phore. For verification of the entire pattern, and to
understand the influence of the hydrophilic portion,
the sulfamide derivatives were synthesized and evalu-
ated. Seventeen compounds were included in the set,
with aromatic or aliphatic chains chosen so that their
size was varied.
0
Scheme 1. Synthetic route for symmetric N,N -disubstituted sulfa-
mides and tetrasubstituted sulfamides. Method A: 1—R1 = nBu,
R2 = H; 2—R1 = cyclohexyl, R2 = H; 3—R1 = cyclopropyl, R2 = H;
4
7
—R1 = Benzyl R2=H; 5—R1R2 = Morpholin; 6—R1R2 = nPropyl ;
—R1R2 = n Butyl; 8—R1 = nPropyl, R2 = H; 9—R1 = Phenethyl,
R2 = H.
Initially N-alkoxycarbonyl sulfamides were prepared in
one-pot synthesis from chlorosulfonyl isocyanate, tert-
butanol, and the corresponding amine in presence of tri-
ethylamine. The tert-butoxy carbonyl group was then
removed via acidic hydrolysis.
2
.2. Synthesis
The synthetic route has been selected according to the
0
position of the subtituents. Symmetric N,N -disubsti-
The N-acyl-substituted products (Scheme 2, compounds
10b to 13b) were also included in the biological analysis,
as sulfamide derivatives.
tuted sulfamides and tetrasubstituted sulfamides were
prepared in concordance with typical procedures by
condensation of an excess of amine with sulfuryl chlo-
4
2–47
ride (Scheme 1 compounds 1a to 9a).
found a non-favorable effect of pyridine in the reac-
tion,
We have
2.3. Pharmacology
48,49
and it has not been used as a reactant.
Preliminary anticonvulsant evaluation (phase 1) of the
synthesized compounds was performed following the
standard procedure provided by the antiepileptic drug
Mono-substituted sulfamides and N,N-disubstituted sul-
famides were also synthesized following standard proce-
5
5
development program. It includes qualitative assays
using MES test and PTZ test. The first assay is related
5
0–54
dures (Scheme 2 compounds 14c to 17c).

5608
L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
O C N
O
O
R
1
NH
S
O
S
O
Cl
O
S
O
R1
R O
HN
Cl
R
2
R1
R-OH
R O
HN
H N S N
N
2
TFA
R2
TEA
R2
O
O
O
1
0b-13b
14c-17c
Scheme 2. Synthetic route for sulfamides type B and C: 10 and 17, R1 = nBu, R2 = H; 11 and 14, R1 = Benzyl R2 = H; 12 and 16, R1 = R2 = nBu,
3 and 15, R1R2 = nPropyl.
1
to electrical induction of the seizure and the second test
generates the convulsion by chemical induction. The
RotoRod test was used to determine the possible neuro-
toxic effects. The compounds were administered to ani-
mals intraperitoneally at three doses (30, 100, and
All the compounds mentioned above are able to adopt
the active conformation defined by the pharmacophore
for anti-MES activity, supporting the application of
the model.
3
00 mg/kg), and all the assays were performed at 0.5
Neither anti-MES activity nor neurological toxicity was
detected in 3a, 5a, 6a, 7a, and 11b. This behavior can be
explained for compounds 3a and 5a, which are not able
to adopt the pharmacopore conformation due to their
rigidity.
and 4 h. Details of the evaluation of anticonvulsant
activity are given in the Section 4. The results are sum-
marized in Table 2.
Due to the low solubility of five sulfamides at high
doses (1a, 2a, 4a, 5a, and 9a), intraperitoneal testing
was difficult and, in these cases, we reported only
reliable results. Taking into account that physico-
chemical properties like lipophlicity may have influ-
ence on the pharmacological properties of the
compounds, it has been expressed as partition coeffi-
cients (logP parameters) for each sulfamide of the set
No explanation can be given for the lack of activity pre-
sented in 11b and 7a, and ideas for future molecular
modification to improve the pharmacophore pattern
may be derived from these data.
As mentioned before, compounds 15c, 16c, and 17c
showed neurological toxicity in the RotoRod test.
According to the high toxicity found for 15c (3/3 ani-
mals affected at doses of 30 mg/kg) the MES and PTZ
test were performed only at low doses. We considered
this compound too toxic to continue the experimental
procedures at higher doses. The same criteria was ap-
plied for 16c and 17c. Related to their structures, all
(
the HyperChem QSAR Properties, version 7.01,
Table 2). The calculated values were estimated using
5
6
Hypercube, Inc.
As anticipated, the results of the pharmacological inves-
tigation reveal that the biological activity is related to
the presence and disposition of the lateral chains in
sulfamides.
of these compounds present a free NH group in the sul-
2
famide function. Although the number of evaluated
compounds is not significantly high, we could infer that
the presence of unsubstituted nitrogen in the sulfamide
function increases the neurological toxicity. Moreover,
the presence of the NH group could be important to
the activity as well as in the modulation of the toxicity.
This relation between the number and the position of
the substituents and the neurotoxic effect may indicate
key features to be considered in the further design of
new ligands.
The most active sulfamides against MES test were 1a,
2a, 4a, 10b, 12b, 14c, and 17c. They were active at
doses of 30 mg/kg: 1/3 animals protected in all cases
0
1
.5 h after administration (with exception of 12b and
7c); and 1/3 animals protected 4 h after administra-
tion for 12b, 14c, and 17c. For these molecules, toxic-
ity was only observed in case of 17c at the tested
doses.
Compound 9a showed significant protection against the
MES test at 100 mg/kg (3/3 animals protected) 0.5 h
after administration. Compound 16 c also showed
anti-MES activity at 100 mg/kg at the same time, in con-
junction with neurological toxicity at higher doses.
Compounds 8a and13b demonstrated a activity against
MES test at doses of 300 mg/kg at 0.5 h. Compound
According to the results in MES test, the molecules were
2
2
grouped into four classes (Table 2) : (1) anticonvulsant
activity at 100 mg/kg or less; (2) anticonvulsant activity
at doses higher than 100 mg/kg; (3) compound inactive
at any doses up to 300 mg/kg; (4) compound inactive at
300 mg/kg and toxic at 30 mg/kg or less.
8
(
a also showed a weak neurotoxicity at the same time
1/3 animals).
Biological data were derived to phase II testing for some
of the most active compounds in MES test: 1a, 2a, 4a,
9
standard procedures provided by the antiepileptic drug
a, and 14c. The assays were performed following the
Most of the active compounds present a PHE-like pro-
file, being active in the MES test and inactive in PTZ-in-
duced convulsions, at the doses and times evaluated.
However, sulfamides 8a and 16c showed protection
against both test. In PTZ test, both compounds were ac-
tive at 100 mg/kg (2/3 and 1/3 animals protected,
respectively).
5
5
development program. The results obtained are listed
in Table 3. The anticonvulsant activity was expressed
as ED50, which measures the dose that is effective in
50% of the tested animals. The ED50 values obtained
for 1a, 2a, and 4a have been reported by us in a previous
2
7
investigation.
Additionally, the neurotoxicity was

L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
Table 2. Pharmacological profile (phase I) of the sulfamides and their logP values
5609
A
B
TOX time (h)
C
Compound
Class
logP
Dose (mg/kg)
Activity MES
time (h)
Activity PTZ
time (h)
1, 2, 3, 4
0.5
4
0.5
4
0.5
4
1
2
3
4
5
6
7
8
9
a
a
a
a
a
a
a
a
a
1
1.23
2.59
0.21
1.45
ꢀ1.44
2.49
4.69
1.04
1.95
0.67
0.48
1.79
1.39
0.41
0.22
1.53
1.14
30
1/3
2/3
Nt
1/3
3/4
Nt
0/3
0/3
0/3
1/3
3/3
Nt
0/4
0/4
Nt
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
3/3
0/3
3/3
Nt
1/3
3/3
3/3
0/3
0/3
0/3
0/3
2/3
2/3
0/3
0/3
1/3
1/3
3/3
3/3
0/3
0/3
0/3
Nt
0/3
0/4
Nt
0/3
0/3
0/3
0/3
0/3
Nt
0/4
0/4
Nt
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
Nt
0/3
1/3
1/3
0/3
0/3
0/3
1/3
0/3
2/3
0/3
0/3
0/3
1/3
1/2
3/3
0/3
0/3
0/3
Nt
0/3
0/3
Nt
0/3
0/3
0/3
0/3
0/3
Nt
0/4
0/4
Nt
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
1/3
0/3
0/3
Nt
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
3/3
3/3
0/3
0/3
Nt
0/3
0/3
Nt
0/3
0/3
0/3
0/3
0/3
Nt
0/4
0/4
Nt
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
Nt
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
3/3
3/3
0/2
0/2
Nt
0/2
0/2
Nt
0/2
0/4
0/2
0/3
0/3
Nt
0/4
0/4
Nt
0/2
0/2
0/2
0/3
0/3
0/3
0/3
1/3
3/3
0/2
0/2
Nt
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
Nt
0/2
0/2
Nt
0/2
0/2
0/2
0/3
0/3
Nt
0/4
0/4
Nt
0/2
0/2
0/2
1/3
0/3
0/3
1/3
0/3
0/3
0/2
0/2
Nt
0/2
0/2
0/1
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
0/2
1
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
30
00
00
3
1
3
1
1
3
1
3
1
3
—
3
1
3
1
3
3
1
3
2
1
3
1
1
3
10b
11b
12b
13b
14c
15c
16c
17c
1
1
3
3
1
3
1
1
3
2
1
3
1
1
3
—
1
a
a
a
a
1
3
Nt
Nt
Nt
Nt
Nt
Nt
Nt
Nt
a
a
a
a
a
a
Nt
0/3
0/3
3/3
0/3
2/3
3/3
Nt
0/3
0/3
3/3
0/3
0/3
2/3
0/3
2/3
0/3
0/3
0/3
2/3
0/3
0/3
1
3
a
a
a
a
Nt
0/3
0/3
Nt
1/3
1/3
Nt
0/2
0/2
Nt
0/2
0/2
1
1
3
a
a
Nt
a
Nt
a
Nt
a
Nt
Nt, not tested due to the low solubility of the drug. Nt , not tested due to the high neurotoxicity of the drug.
A
Maximal electroshock seizure.
Toxicity evaluated in RotoRod test.
Pentylenetetrazol test.
B
C
quantified as TD , which measures the doses that pres-
5
ent neurotoxicity in 50% of the tested animals.
at high doses, and maximal concentrations evaluated
were reported in Table 3.
0
We were not able to determine the values of TD50 for
compounds 1a, 2a, 4a, and 9a due to solubility problems
The time of peak effect (TPE) was determined previously
to calculate the ED and TD values for the compounds,
5
0
50

5610
L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
Table 3. Time of peak effect (TPE), activity values (ED50, lmol/kg), and toxicity values (TD50, lmol/kg) determined (mice) for some of the most
active sulfamide derivatives designed in this research
a
Compound
MES test
ED50 (lmol/kg)
RotoRod test
TD50 (lmol/kg)
PI
PTZ test
ED50 (lmol/kg)
TPE (h)
TPEN (h)
TPE (h)
1
2
4
9
1
a
2
295
151
238
263
239
—
—
—
—
0.5
0% (481)
0% (385)
0% (362)
0% (329)
1422
>1.6
>2.5
>1.5
>1.3
5.9
—
—
—
—
—
Inactive (481)
Inactive (385)
Inactive (362)
Inactive (329)
Inactive (1613)
a
0.5
2
a
a
4c
0.5
0.5
Compounds are defined as Inactive when they are not effective at the maximal doses evaluated, expressed between brackets.
TPE, time of peak effect; TPEN, Neurotoxic time of peak effect.
a
PI (protective index) = TD50/ED50, calculated for the MES test.
and are expressed in Table 3. Details for determination of
TPE ED50 and TD50 are given in Section 4.
rected. Thin-layer chromatography (TLC) was per-
formed with aluminum backed sheets with silica gel 60
F254 (Merck, ref 1.05554), and the spots were visualized
with UV light and 5% aqueous solution of Ammonium
molybdate (VI) tetrahydrate. Column chromatography
was performed on silica gel 60 (70–230 mesh, Merck, ref
1.07734.1000).
3. Conclusions
Based on the results of molecular modeling, a set of sul-
famides were designed, synthesized, and evaluated.
1
Two hundred megahertz H NMR and 75.4 MHz
13
C
The selection of this functionality was supported by the
bioisosteric equivalence of this kind of molecules with
the groups that previously defined the polar portion of
the pharmacophore (Table 1). Compounds bearing this
functionality were synthesized and evaluated according
to the standard procedures. From this investigation we
have found nine compounds classified as class 1 anticon-
vulsants (anticonvulsant activity at 100 mg/kg or less),
the most potent class of antiepileptic drugs. Addition-
ally, most of the sulfamides that are able to adopt the
active conformation show the anti-MES profile and
some of them display the characteristic of phenytoin-like
compounds.
NMR spectra were recorded on a Varian Gemini 200
spectrometer.
The chemical shifts are reported in ppm (d scale) relative
to internal TMS, and coupling constants are reported in
Hertz (Hz). IR spectra were run on a FT/IR Perkin–Elmer
spectrophotometer. Absorption values are expressed as
ꢀ1
wave-numbers (cm ); only significant absorption bands
are given. Analytical grade solvents were used for crystal-
lization, while pure for synthesis solvents were used in the
reactions, extractions, and column chromatography. All
reactions were carried out in flame-dried glassware, under
positive pressure of Argon. Commercial amines were dis-
tilled prior to their use. Sulfuryl chloride was distilled and
stored under nitrogen at 5 ꢁC.
The ED50 values determined for the most active sulfa-
mides are comparable with classical and new generation
2
7
drugs.
Elemental analyses were carried out at the Mycroanaly-
sis Service of INQUIMAE (Argentine) and results were
within ±0.4% of the theoretical values.
No relation between logP and anticonvulsant activity
can be established. Lipophilicity can be related with
the capability of the drugs to be transported through
the biological membranes. In spite of the lack of a more
detailed conclusion, we can assume that the logP values
are high enough to allow the delivery of the compounds
to the active site.
0
4.2. General procedure A for the preparation of N,N -
disubstituted symmetric sulfamides (1a–9a)
Compounds 1–9 were prepared as described in the liter-
4
7
ature. The reaction was carried out by dropwise addi-
tion of a solution of sulfuryl chloride (16.5 mmol,
1 equiv) in dichloromethane (5 mL) to a solution of
the corresponding amine (4–6 equiv) in dichloromethane
(6-8 mL) at 0 ꢁC in dark condition. Gas evolution was
observed during the addition.
More sulfamide derivatives would be investigated in or-
der to offer a better understanding of the structural and
electronic characteristics that are responsible for the
activity.
The reaction mixture was warmed to room temperature,
stirred for 5–30 h, and monitored by TLC (SiO ). The
4. Experimental
2
crude was washed with acidic and basic aqueous solu-
tions and if it was necessary a column chromatography
was carried out. Purification was performed as indicated
in each example. The synthetic procedure for com-
4
.1. Chemistry
Melting points were determined using capillary tubes with
a Electrothermal melting point apparatus and are uncor-
2
7
pounds 1a to 5a was detailed in a previous paper.

L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
58
5611
0
0
0
58
4.2.1. N,N,N ,N -Tetrapropylsulfamide (6a). This com-
pound was prepared according to the general procedure
4.2.4. N,N -Diphenethylsulfamide (9a).
This com-
pound was prepared according to the general procedure
A, using a solution of N-phenethylamine (8.3 mL,
65.8 mmol, 5 equiv) in CH Cl (5 mL) and SO Cl
2
A, using a solution of N,N-dipropylamine (9.0 mL,
6.0 mmol, 4 equiv) in CH Cl (5 mL) and SO Cl
2 2 2 2
6
2
2
2
(
1.3 mL, 16.5 mmol, 1 equiv) in CH Cl (5 mL). After
2
(1.05 mL, 13.2 mmol, 1 equiv) in CH Cl (4 mL). After
2 2
2
2
4 h of reaction the resulting yellow solution was concen-
24 h of reaction solution was concentrated under re-
duced pressure to leave a solid crude, (10.1 g). Column
chromatography (CH Cl ) afforded (2.4 g, 70% yield)
trated under reduced pressure to leave a yellow solid
crude. Dichloromethane (20 mL) was added, the solution
was washed with 5% acetic acid (2·), brine (2·) and
dried (SO Na ). The solution was filtered, concentrated
under reduced pressure to leave a crude oil. Column
chromatography (CH Cl ) afforded (1.8 g, 41% yield)
of sulfamide 6a, as a colorless oil. R : 0.65 (SiO , CH Cl ).
2
2
sulfamide 9a, as a white solid, mp 100–101 ꢁC (CH Cl )
2
2
5
9
(described: 100–101 ꢁC). R : 0.48 [(SiO , CH Cl /
4
2
f
2
2
2
MeOH (20:1)], IR (KBr) : 3280 (NH), 1300 (S–O),
NMR (CDCl3): 2.80 (dd,
1
1137 (S–O).
0
H
2
2
0
J ffi J = 6.8 Hz, 4H:b-CH ), 3.20 (dd, J ffi J = 6.8 Hz,
f
2
2
2
2
1
IR (ClAg): 1372 (S–O), 1146 (S–O). H NMR (CDCl ):
3
0
4H: c-CH ), 4.31 [t broad, 2H, J ffi 6.2 Hz, NH), 7.17-
2
0
13
7.20 (m complex signal, 10 H, Ar (Ar )-H). C NMR
.88 (t, J = 7.7 Hz, 12H: CH ), 1.58 [ddd, J ꢁ 7.7 Hz,
3
0
4
J ꢁ 5.5 Hz, 8H: b-CH ], 3.05 [dd, J ꢁ 5.5 Hz, 8H:
(CDCl ): 35.9 (a-C), 44.4 (b-C), 127.0 (C -Ar), 129.0
2
3
1
3
2,6
(C -Ar), 129.05 (C -Ar), 138.3 (C -Ar). Anal. Calcd
3,5
1
a-CH ]. C NMR (CDCl ): 11.5 (CH ), 21.7 (b-C), 49.8
2
3
3
(
a-C).Anal. Calcd for C H N O S: C: 54.5%, H:
for C H N O S: C: 63.2, H: 6.6, N: 9.2, S: 10.5.
2
12 28 2 2
16 20
2
10.7, N: 10.6, S: 12.1. Found: C: 54.0, H: 11.0, N: 10.7,
S: 12.2.
Found: C: 63.1, H: 6.8, N: 9.3, S: 10.4.
4.3. General procedure B for the preparation of N-Boc-
sulfamides (10b–13b)
0
0
4.2.2. N,N,N ,N -Tetrabutylsulfamide (7a). This com-
pound was prepared according to the general procedure
A, using a solution of N,N-dibutylamine (6.1 mL,
6
The synthesis of N-Boc-sulfamides 10–13b is per-
formed in dried dichloromethane with successive addi-
tions of t-BuOH and RR NH/triethylamine (TEA) into
6.0 mmol, 4 equiv) in CH Cl (5 mL) and SO Cl
2
2
2
2
0
(
1.3 mL, 16.5 mmol, 1 equiv) in CH Cl (5 mL). After
2
2
1
1 h of reaction the resulting yellow solution was con-
chlorosulfonyl isocyanate (CSI). N-chlorosulfonyl
(tert-butyl) carbamate was prepared by addition of
tert-butanol (1.4 equiv, in 6 mL of dried dichlorometh-
ane) into a solution of CSI (1 equiv, in the same
solvent). This reagent was slowly added at 0 ꢁC into
a solution containing a primary (or secondary) amine
(1 equiv in dried dichloromethane) and 1.1 equiv of tri-
ethylamine. The reaction was achieved in 45–60 min at
0 ꢁC and 2–3 h at rt. The medium was diluted with
dichloromethane, washed with two fractions of HC1
0.1 N, dried (SO Na ), and concentrated under
centrated under reduced pressure to leave a yellow syrup
crude. Dichloromethane (20 mL) was added, the solu-
tion was washed with 5% acetic acid (2·), brine (2·)
and dried (SO Na ). The solution was filtered, concen-
trated under reduced pressure to leave a crude oil. Col-
umn chromatography (CH Cl ) afforded (2.5 g, 47%
4
2
2
2
yield) sulfamide 7a, as a colorless oil, bp 126–128 ꢁC/
mmHg. R : 0.65 [SiO , CH Cl /hexane (1:1)]. IR
1
f
2
2
2
1
(
ClAg): 1387 (S–O), 1101 (S–O). H NMR (CDCl ):
3
0
8
.95 (t, J = 7.3 Hz, 12H: CH ), 1.39 (m, 8H)], 1.67 (m,
3
4
2
1
3
H), 3.05 [t, J ꢁ 7.7 Hz, 8H: a-CH ].
C NMR
reduced pressure. The crude residue was then purified
by column chromatography and crystallization (yield
50–80%).
2
(CDCl ): 13.8 (CH ), 20.1 (a-C), 51.1 (b-C). Anal. Calcd
for C H N O S: C: 60.0.%, H: 11.3, N: 8.7, S: 10.0.
3 3
1
6
36
2
2
Found: C: 59.8, H: 11.4, N: 8.6, S: 10.4.
0
53
4
.3.1. N-(tert-Butoxycarbonyl)-N -(butyl)sulfamide (10b).
0
57
4
was prepared according to the general procedure A,
.2.3. N,N -Dipropylsulfamide (8a).
This compound
This compound was prepared according to the general pro-
cedure B, using a solution of CSI (1.2 mL, 14 mmol,
1 equiv) in CH Cl (7 mL), tert-butanol (1.3 mL, 19 mmol,
using a solution of N-propylamine (11 mL, 133.2 mmol,
2
2
6
2
equiv) in CH Cl (5 mL) and SO Cl (1.8 mL,
2
1.4 equiv), n-butylamine (1.4 mL, 14 mmol, 1 equiv), and
TEA (2,2 mL, 15,4 mmol, 1.1 equiv) in a solution of dried
CH Cl (28 mL).
2
2
2
2.5 mmol, 1 equiv) in CH Cl (4 mL). After 24 h of
2
2
reaction the resulting orange solution was concentrated
under reduced pressure to leave a yellow solid crude.
Dichloromethane (15 mL) was added, the solution
was washed with 5% acetic acid (2·), brine (2·) and
dried (SO Na ). The solution was filtered, concentrated
2
2
The solid obtained by evaporation of the reaction mix-
ture (6.0 g) was purified using column chromatography
(SiO , CH Cl /MeOH mixtures) affording the sulfamide
4
2
2
2
2
under reduced pressure to leave a yellow solid crude.
Column chromatography (CH Cl ) afforded (2.6 g,
10b as a white solid, (2,02 g, 58% yield), mp 144–145 ꢁC
60
[CH Cl /Hexano (1:3)], (described: 154–155 ꢁC). R :
2
2
2
2
f
6
1
5% yield) of sulfamide 8a, as a white solid, mp 118–
4
0.73 [SiO , CH Cl /MeOH (20:1)]. IR (KBr): 3366 y
2 2 2
6
19 ꢁC (described 119 ꢁC) R : 0.49 [SiO , CH Cl /
3222 (CONH and NH), 1701(C@O), 1347(S–O), 1140
f
2
2
2
1
(S–O). H NMR (CDCl ): 0.93 (t, J = 7.2 Hz, 3H:
MeOH (20:1)]. IR (KBr): 3280 (N–H), 1314 (S–O),
3
1
147 (S–O). H NMR (CDCl ): 0.98 (t, J = 7.3 Hz,
1
6
2
CH ), 1.29–1.62 [m, 13H: 4H: b and c-CH and 9H:
3
3
2
0
H: CH ), 1.53 (sext, J ꢁ J ꢁ 7.2 Hz, 4H: b-CH ),
CH tert-But, 3.06 (c, J = 6.8 Hz, 2H: a-CH ), 5.07 (t,
3
2
3
2
00
.97 (m, 4H: a-CH ), 4.54 (t broad, J ꢁ 5.8 Hz, 2H:
J ꢁ 6.0 Hz, 1H: NH), 7.25 (s broad signal, 1H: NH ).
3 3 2
2
2
1
3
NH).
C NMR (CDCl ): 13.7 (CH ), 19.9 (c-CH ), 28.2
(
CH , tert-Bu), 31.2 (b-CH ), 43.8 (a-CH ), 83.9
3 2 2
1
3
C NMR (CDCl ): 11.5 (c-C), 23.1 (b-C), 45.1 (a-C).
[C(CH3)3], 150.6 (C, C@O). Anal. Calcd for
3

5612
L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
C H N O S: C: 42.8, H: 8.0, N: 11.1, S: 12.7. Found:
9
C: 43.1, H: 8.1, N: 11.2, S: 12.3.
(C@O). Anal. Calcd for C H N O S: C: 47.1, H: 8.6,
20
2
4
11 24
2
4
N: 10.0, S: 11.4. Found: C: 47.5, H: 8.6, N: 9.7, S: 11.0.
0
4
(
.3.2.
11b).
N-(benzyl)-N -(tert-butoxycarbonyl)sulfamide
This compound was prepared according to
4.4. General procedure C for the preparation of N- and
N,N-substituted sulfamides (14c–17c)
5
1,54
the general procedure B, using a solution of CSI
2.13 mL, 24.0 mmol; 1 equiv) in CH Cl (25 mL), tert-
(
A solution of trifluoroacetic acid (50% in dried dichloro-
methane; 3–6 equiv) was added dropwise into a stirred
solution of substituted N-Boc-sulfamides (1 equiv), in
dried dichloromethane (15 mL) at 0 ꢁC. The reaction
mixture was stirred during 2 h at 0 ꢁC, and 6–24 h at
rt. Concentrated under reduced pressure and coevapo-
rated with diethyl ether. Purification was performed as
indicated in each example.
2
2
butanol (2.4 mL, 33.6 mmol, 1.4 equiv), benzylamine
2.62 mL, 24 mmol 1.1 equiv), and TEA (3.78 mL,
6.9 mmol, 1.1 equiv) in a solution of dried CH Cl
(
2
2
2
(
50 mL). The white solid (10.2 g) obtained by evapora-
tion of the reaction mixture was purified using column
chromatography (SiO , CH Cl ) affording the sulfamide
2
2
2
1
1b, as a white solid, (4.7 g, 68% yield), mp 129.5–
5
1,54
1
R : 0.52 [SiO , CH Cl /MeOH (60:1)]. IR (KBr): 3300,
30 ꢁC, (described: 137–139 ꢁC and 111–113 ꢁC).
5
8
4.4.1. N-Benzylsulfamide (14c). This compound was
prepared according to the general procedure C, using
a solution of 11b (1.48 g, 5.2 mmol, 1 equiv) in CH Cl
2
f
2
2
2
3
1
6
1
273 (NH), 3068, 3033 (CH arom a´ tico), 1713 (C@O),
1
358, 1148 (SO ). H NMR (CDCl ): 7.35–7.26 (m,
2
3
2
H: Ar-H and NH-Boc), 5.61 (t, broad signal, J ꢁ 6.1
(10 mL), and a solution of TFA 50% (1.16 mL,
15.6 mmol, 3 equiv). After 14 h of reaction the solution
was concentrated under reduced pressure to leave a
crude solid (1.3 g). Column chromatography [SiO2,
CH Cl /MeOH (25:1)] afforded (912 mg, 62% yield) sul-
H: NH- Bz), 4.25 (d, J = 6.1, 2H: CH ), 1.44 (s, 9H:
2
1
3
CH3 tert-Bu)
1
C NMR (CDCl ): 150.37 (C@O),
3
1
35.88 (C -Ar), 129.09, 128.36, 128.33 (C
2,3,4
-Ar),
4.09 (C(CH ) ), 45.81 (CH ), 28.20 (CH , tert-Bu).
8
Anal. Calcd for C H N O S: C: 50.3, H: 6.3, N: 9.8,
3
3
2
3
2
2
famide 14 c mp 104–105 ꢁC (CH Cl ) (described: 106–
1
2
18
2
4
2
2
59
S: 11.2. Found: C: 50.4, H: 6.1, N: 9.5, S: 11.2.
107 ꢁC). R : 0.50 [SiO , CH Cl /MeOH (30:1)]. IR
(KBr): 3325, 3273 (NH, NH ), 3039 (CH, Ar), 1334,
1153 (SO2). H NMR (DMSO-d ): 4.05 (d, J = 6.6,
f
2
2
2
2
0
1
4
.3.3. N,N-(Dibutyl)-N -(tert-butoxycarbonyl)sulfamide
6
(
12b). This compound was prepared according to the
general procedure B, using a solution of CSI (1.2 mL,
4 mmol, 1 equiv) in CH Cl2 (8 mL), tert-butanol
2H: CH ), 6.59 (s, 2H: NH ), 7.00 (t, J = 6.6 Hz, 1H:
2
2
1
3
NH-benzyl), 7.41–7.19 (m, 5H: Ar-H).
(DMSO-d ): 46.79 (CH ), 127.61, 128.35, 128.85
C NMR
1
2
6
2
2
,3,4
1
(C -Ar).
(1.4 mL, 19 mmol, 1.4 equiv), N,N-di-butylamine
(1.3 mL, 14 mmol, 1 equiv), and (TEA) (2.2 mL,
(C
-Ar),139.361
Anal.
Calcd
for
C H N O S: C: 45.2, H: 5.4, N: 15.0, S: 17.2. Found:
7 10 2 2
1
5.4 mmol, 1.1 equiv) in a solution of dried CH Cl
2
C: 45.3, H: 5.6, N: 15.0, O: 16.8, S: 17.3.
2
(
25 mL). The oil (6.8 g) obtained by evaporation of the
5
7
reaction mixture was purified using column chromato-
graphy (SiO , CH Cl /Hexane) affording the sulfamide
1
CH Cl ). IR (ClAg): 3273 (CON–H), 1701 (C@O),
1
4.4.2. N,N-Dipropylsulfamide (15c).
This compound
was prepared according to the general procedure C,
using a solution of 13b (1.41 g, 5.0 mmol, 1 equiv) in
CH Cl (10 mL) and TFA 50% (1.1 mL, 15.0 mmol,
3 equiv). After 6 h of reaction the solution was concen-
trated under reduced pressure to leave a solid crude
2
2
2
2b, as colorless oil (2.04 g, 48% yield). R : 0.49 (SiO ,
f 2
2
2
2
2
1
366, (S–O), 1140 (S–O). H NMR (CDCl ): 0.93 (t,
3
J ꢁ 7.3 Hz, 6H, CH ), 1.29–1.62 [m, 17H: 8H: b-CH
3
2
and c-CH ; 9H: CH tert-But, 3.31 (t, J ꢁ 7.6 Hz, 4H,
(824 mg). Crystallization with CH Cl
afforded
(442 mg, 49% yield) sulfamide 15c as a white solid, mp
2
3
2
2
1
3
a-CH ),7.16 (s, broad signal, 1H: NH). C NMR
2
5
7
(
3
CDCl ): 14.0 (CH ), 20.1 (c-C), 28.3 (CH , t-CH ),
67–68 ꢁC (described: 62–63 ꢁC).
Rf: 0.67 (SiO2,
CH Cl /MeOH 30:1). IR (KBr): 3358, 3270 (NH,
3
3
3
3
0.6 (b-C), 48.9 (a-C), 83.4 [C(CH ) ], 150.2 (C@O).
3
3
2
2
1
NH ), 1335, 1152 (SO ). H NMR (CDCl ): 0.92 (t,
2
2
3
0
4
.3.4. N,N-(Dipropyl)-N -(tert-butoxycarbonyl)sulfamide
J = 7.3 Hz, 6H: CH ), 1.62 (m, 4H: b-CH ), 3.12 (t,
3 2
13
J = 7.6 Hz, 4H: a-CH ), 4.65 (s, 2H: NH ). C NMR
2 2
(
13b). This compound was prepared according to the
general procedure B, using a solution of CSI (2.21 mL,
5 mmol, 1 equiv) in CH Cl (25 mL), tert-butanol
(CDCl ): 11.44 (CH ),21.70 (b-CH ), 50.38 (a-CH ).
3
3
2
2
2
Anal. Calcd for C H N O S: C: 40.0, H: 8.9, N: 15.5,
S: 17.8. Found: C: 40.1, H: 9.0, N: 15.5, S: 17.9.
2
2
6 16 2 2
(2.4 mL, 33.6 mmol, 1.4 equiv), N,N-di-propylamine
(3.5 mL, 25 mmol, 1 equiv), and (TEA) (3.86 mL,
5
7
2
7.5 mmol, 1.1 equiv) in a solution of dried CH Cl
2
4.4.3. N,N-Dibutylsulfamide (16c).
This compound
2
(
tion of the reaction mixture was purified using column
chromatography (SiO , hexane) affording the sulfamide
2
50 mL). The white solid (10.3 g) obtained by evapora-
was prepared according to the general procedure C
using a solution of 12b (741 mg, 2.4 mmol, 1 equiv) in
CH Cl (3.5 mL) and TFA 50% (0.53 mL, 7.2 mL,
2
2
1
3 b, as a white solid, (4.5 g, 66% yield), mp 52–53 ꢁC,
3 equiv). After 23 h of reaction the solution was concen-
trated under reduced pressure to leave a solid crude
(432 mg). Column chromatography (SiO , CH Cl )
5
9
(
(
(
described: 62–63 ꢁC). R : 0,57 [SiO , CH Cl ]. IR
f
2
2
2
ꢀ
1
KBr), cm : 3272 (NH), 1736 (C@O), 1350, 1130
2
2
2
1
SO2). H NMR (CDCl ): 0.91 (t, J = 7.4 Hz, 6H:
afforded sulfamide 16c (329 mg, 66% yield) as a white
solid, mp 65–65.5 ꢁC (CH Cl ). R : 0.33 (SiO , CH Cl ).
3
CH ), 1.47 (s, 9H: CH tert-Bu), 1.62 (m, 4H: b-CH ),
3
3
2
2
2
f
2
2
2
3
.27 (t, J = 7.6 Hz, 4H: a-CH ), 7.26 (s, 1H: NH-Boc).
IR (KBr): 3383 and 3260 (NH ), 1353 (S@O), 1147
2
2
1
3
1
C NMR (CDCl ): 11.32 (CH ), 21.75 (b-CH ), 28.26
(S@O). H NMR (CDCl ): 0.95 (t, J ꢁ 7.3 Hz, 6H:
3
3
2
3
(
CH , tert-Bu), 50.97 (a-CH ), 83.38 [C(CH ) ],150.20
CH ), 1.35 (m, 4 H: b-CH ), 1.60 (m, 4 H: c-CH ),
3
2
3 3
3
2
2

L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
5613
3
1
.14 (t, J ꢁ 7.4 Hz, 4H:a-CH ), 4.58 (s, broad signal,
de Investigaciones Cient ´ı ficas y T e´ cnicas de la Rep u´ blica
Argentina (CONICET). I. A. Barrios is a fellowship
holder of Universidad Nacional de La Plata. This
research was supported in part through grants from
2
1
H:NH). C NMR (CDCl ): 14.0 (CH ), 20.2 (CH ,
3
3
3
2
c-C), 30.5 (b-C), 48.3 (a-C). Anal. Calcd for
C H N O S: C: 46.1, H: 9.7, N: 13.4, S: 15.4. Found:
C: 46.3, H: 9.5, N: 13.4, S: 15.1.
8
20
2
2
Agencia de Promoci o´ n Cientıfica y Tecnol o´ gica (PICT
6-11985/2004), CONICET, and Universidad Nacional
´
0
5
7
4.4.4. N-Butylsulfamide (17c).
prepared according to the general procedure C using a
solution of 10b (1.00 g, 3.96 mmol, 1 equiv) in CH Cl
2
This compound was
de La Plata, Argentina. We thank the students M. Plou,
M. Minicucci, M. Peralta and acknowledge the technical
support of R. Grecco from Medicinal Chemistry
Laboratory, Facultad de Ciencias Exactas, Universidad
Nacional de La Plata (Argentine) for carrying out the
biological assays.
2
(
10 mL) and TFA 50% (0.9 mL, 12.0 mmol, 3 equiv).
After 23 h of reaction the solution was concentrated un-
der reduced pressure to leave a solid crude (700 mg).
Column chromatography (SiO , CH Cl ) afforded sulfa-
2
2
2
mide 17c (543 mg, 82% yield) as a white solid, mp 47–
5
7
4
0
3
8 ꢁC [CH Cl /Hexane (1:2)] (described: 52 ꢁC) Rf:
2
2
References and notes
.29 (SiO ), CH Cl /MeOH (20:1). IR (KBr): 3325,
318 and 3273 (NH, NH ), 1340 (S–O), 1160 (S–
2
2
2
2
ꢀ
1
1
1. McCormick, D. A.; Contreras, D. Annu. Rev. Physiol.
O) cm . H NMR (CDCl ): 0.91 (t, J ꢁ 7.3 Hz, 3H:
3
2
. Contreras, D. Rev. Neurol. 2000, 30, 370.
3. McNamara, J. O. In Las Bases Farmacol o´ gicas de la
Terap e´ utica; Hardman, J. G., Limbird, L. E., Goodman,
L. S., Gilman, A., Eds.; McGraw-Hill: Interamericana,
M e´ xico, 2001; pp 529–556.
001, 63, 815.
CH ), 1.23–1.61 (m, 4H: b and c -CH ), 3.08 (c,
3
2
2
J ꢁ 6.8 Hz, 2H: a-CH ), 4.74 (t broad, 1H: NH), 4.93
2
1
3
(
s broad, 2H: NH ). C NMR (CDCl ) d: 13.8
2 3
(
CH ), 20.0 (c-CH ), 31.6 (b-CH ), 43.6 (a-CH ).
3
2
2
2
4
.5. Biological data
4. Kulig, B.; Meinardi, H. In Effects of Antiepileptic Drugs on
Motor Activity and Learned Behavior in the Rat; Meinardi,
H., Rowan, A. J., Eds.; Swets & Zeitlinger: Amsterdam,
The evaluation of the anticonvulsant activity followed
the Anticonvulsant Drug Development (ADD) Program
1
977; pp 98–104.
5
6
. Estrada, E.; Pe n˜ a, A. Bioorg. Med. Chem. 2000, 8, 2755.
. Reijs, R.; Aldenkamp, A. P.; De Krom, M. Epilepsy
Behav. 2004, 5, S66.
5
5
of the National Institute of Health. Adult male and fe-
male albino mice (18–25 g) were used as experimental
animals. Animals of the same age and weight were se-
lected, in order to minimize biological variability. The
animals were maintained on a 12 h. light/dark cycle
and allowed free access to food and water, except during
the time they were removed from their cages for testing.
The test substance was administered in 30% polyethyl-
ene glycol 400 (PEG) and 10% water. The drugs were
administered intraperitoneally (ip) in mice in a volume
of 0.01 mL/g body weight.
7
. Krall, R. L.; Penry, J. K.; White, B. G.; Kupferberg, H. J.;
Swinyard, E. A. Epilepsia 1978, 19, 393.
8. Leppik, I. E. Epilepsia 1994, 35, S29.
9. Wagner, M. L. Am. J. Hosp. Pharm. 1994, 51, 1657.
10. Loscher, W. In GABA. Basic Research and Cellular
Applications; Bowery, N. G., Nistic o´ , G., Eds.; Pythagora
Press: Rome, 1989; pp 260–300.
1
1
1
1. Foster, A. C.; Fagg, G. E. Brain Res. Rev. 1984, 7, 103.
2. Meldrum, B. S. Epilepsy Res. 1992, 12, 189.
3. Rogawski, M. A.; Porter, R. J. Pharmacol. Rev. 1990, 42,
2
23.
14. Macdonald, R. L.; Kelly, K. M. Epilepsia 1995, 36, S2.
4
.6. Determination of median effective dose (ED )
50
1
5. Bialer, M.; Johannessen, S. I.; Kupferberg, H. J.; Levy, R.
H.; Perucca, E.; Tomson, T. Epilepsy Res. 2004, 61, 1.
All quantitative studies were conducted at the previously
determined time of peak effect (TPE). The ED50 was
determined by treating groups of six albino mice. Differ-
ent doses were used for each drug at TPE. The method
of Litchfield and Wilcoxon was used to compute the
ED50 and 95% confidence intervals.
16. Bialer, M.; Johannessen, S. I.; Kupferberg, H. J.; Levy, R.
H.; Loiseau, R. H.; Perucca, E. Epilepsy Res. 2002, 51, 31.
1
7. Bialer, M.; Johannessen, S. I.; Kupferberg, H. J.; Levy, R.
H.; Loiseau, R. H.; Perucca, E. Epilepsy Res. 2001, 41, 11.
8. Loscher, W.; Schmidt, D. Epilepsy Res. 1994, 17, 95.
9. Vamecq, J.; Bac, P.; Herrenknecht, C.; Maurois, P.;
Delcourt, P.; Stables, J. J. Med. Chem. 2000, 43, 1311.
0. Anger, T.; Madge, D.; Mulla, M.; Riddall, D. J. Med.
Chem. 2001, 44, 115.
6
0
1
1
4
.7. Determination of median neurotoxic dose (TD )
50
2
2
Groups of six animals per dose were injected and tested
with the RotoRod test. The percentages of animals
showing minimal neurotoxicity were recorded and the
higher dose producing neurotoxic effects is reported.
TD50 estimations could not be completed due to solubil-
ity problems with high doses.
1. Unverferth, K.; Engel, J.; H o¨ fgen, N.; Rostock, A.;
G u¨ nther, R.; Lankau, H.-J.; Menzer, M.; Rolfs, A.;
Liebscher, J.; M u¨ ler, B.; Hofmann, H.-J. J. Med. Chem.
1998, 41, 63.
2
2
2
2
2. Malawska, B.; Kulig, K.; Spiewak, A.; Stables, J. P.
Bioorg. Med. Chem. 2004, 12, 625.
3. Tasso, S. M.; Moon, S. Y.; Bruno-Blanch, L. E.; Esti u´ , G.
L. Bioorg. Med. Chem. 2004, 12, 3857.
4. Tasso, S. M.; Bruno-Blanch, L. E.; Moon, S. Y.; Esti u´ , G.
L. J. Mol. Struct. (Theochem) 2000, 504, 229.
5. Tasso, S.; Bruno-Blanch, L.; Esti u´ , G. L. J. Mol. Model
Acknowledgments
L.E. Bruno-Blanch is a member of the Facultad de Cien-
cias Exactas, Universidad Nacional de La Plata; L.
Gavernet is a fellowship holder of Consejo Nacional
2
001, 7, 231.
26. Barrios, I. A.; Bruno-Blanch, L. E.; Esti u´ , G. L. L. J. Mol.
Struct. (Theochem) 2002, 580, 243.

5614
L. Gavernet et al. / Bioorg. Med. Chem. 15 (2007) 5604–5614
2
2
7. Gavernet, L.; Dominguez Cabrera, M. J.; Bruno-Blanch,
40. Maryanoff, B.; Costanzo, M.; Nortey, S.; Greco, M.;
Shank, R.; Schupsky, J.; Ortegon, M.; Vaught, J. J. Med.
Chem. 1998, 41, 1315.
41. Barrios, I. A.; Bruno-Blanch, L. E.; Esti u´ , G. L. J. Mol.
Struc. (Theochem) 2002, 580, 243.
L. E.; Esti u´ , G. L. Bioorg. Med. Chem. 2007, 15, 1556.
8. B a¨ ckbro, K.; Lowgren, S.; Osterlund, K.; Atepo, J.; Unge,
T.; Hulten, J.; Bonham, N. M.; Schaal, W.; Hallberg, A.
J. Med. Chem. 1997, 40, 898.
2
9. Hulten, J.; Bonham, N. M.; Nillroth, U.; Hansson, T.;
Zuccarello, G.; Bouzide, A.; Aqvist, J.; Classon, B.;
Danielson, U. H.; Karlen, A.; Kvarnstrom, I.; Samuels-
son, B.; Hallberg, A. J. Med. Chem. 1997, 40, 885.
0. Castro, J. L.; Baker, R.; Giublin, A. R.; Hobbs, S. C.;
Jenkins, M. R.; Rusell, M. G. N.; Beer, M. S.; Stanton, J.
A.; Scholey, K.; Hargreaves, R. J. J. Med. Chem. 1994, 37,
42. Dougherty, J. M.; Probs, D. A.; Robinson, R. E.; Moore,
J. D.; Klein, T. A.; Snelgrove, K. A.; Hanson, P. R.
Tetrahedron 2000, 56, 9781.
43. Bermann, M.; Van Wazer, J. R. Synthesis 1972, 10, 576.
44. Gong, B.; Zheng, C.; Skrzpczak-Jankun, E.; Yan, Y.;
Zhang, J. J. Am. Chem. Soc. 1998, 120, 11194.
45. Gong, B.; Zheng, C.; Skrzypczak-Jankun, E.; Yan, Y.;
Zhang, J. J. Am. Chem. Soc. 1999, 121, 9766.
46. Vandi, A.; Moeller, T.; Audrieth, L. F. J. Org. Chem.
1961, 26, 1136.
3
3023.
3
3
1. Acheson, R. M.; Bite, M. G.; Kemp, J. E. G. J. Med.
Chem. 1981, 24, 1300.
2. Dougherty, J. M.; Probs, D. A.; Robinson, R. E.; Moore,
J. D.; Klein, T. A.; Snelgrove, K. A.; Hanson, P. R.
Tetrahedron 2000, 56, 9781.
47. Sowada, V. R. J. Prakt. Chem. 1963, 4, 310.
48. Ohme, R.; Preuschhof, H. Liebigs Ann. Chem. 1968, 713,
74.
3
3. Abbate, F.; Supuran, C. T.; Scozzafava, A.; Orioli, P.;
Stubbs, M. T.; Klebe, G. J. Med. Chem. 2002, 45, 3583.
4. Winum, J.-Y.; Innocenti, A.; Nasr, J.; Montero, J.-L.;
Scozzafava, A.; Vullo, D.; Supuran, C. T. Bioorg. Med.
Chem. Lett. 2005, 15, 2353.
49. Gavernet, L.; Sarav ´ı Cisneros, H.; Bruno-Blanch, L. E.;
Esti u´ , G. L. Theor. Chem. Acc. 2003, 110, 434.
50. Casini, A.; Winum, J.-Y.; Montero, J.-L.; Scozzafava, A.;
Supuran, C. T. Bioorg. Med. Chem. Lett. 2003, 13, 837.
51. Dewynter, G-F.; Montero, J. L. C.-R. Acad. Sci. Paris
Ser. II 1992, 315, 1675.
52. Picard, J. A.; O’Brien, P. M.; Sliskovic, D. R.; Anderson,
M. K.; Bousley, R. F.; Hamelehle, K. L.; Krause, B. R.;
Stanfield, R. L. J. Med. Chem. 1996, 39, 1243.
53. Winum, J.-Y.; Toupet, L.; Barragan, V.; Dewynter, G.;
Montero, J.-L. Org. Lett. 2001, 3, 2241.
54. Abdaoui, M.; Dewynter, G.; Aouf, N.; Favre, G.; Morere,
A.; Montero, J.-L. Bioorg. Med. Chem. 1996, 4, 1227.
55. Stables, J. P.; Kupferberg, H. J.; Avanzani, G.; Regesta,
G.; Tanganelli, P.; Avoli, M. In Molecular and Cellular
Targets for Anti-epileptic Drugs; John Libbey & Company
Ltd, 1997; pp 191–198.
56. QSAR Properties Version 7.00. HyperChem Release 7.01
for Windows Molecular Modeling System 2002. Hypecube
Inc. 1115 NW 4th Street, Gainesville, Florida 32601, USA.
57. Hirai, H.; Naito H.; Hara H.; Sato K. US Patent,
4,473,631, 1984.
3
3
5. Casini, A.; Winum, J.-Y.; Montero, J.-L.; Scozzafava, A.;
Supuran, C. T. Bioorg. Med. Chem. Lett. 2003, 13, 837.
6. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G.
E.; Robb, M. A.; Cheeseman, J. R.; Zakrzewski, V. G.;
Montgomery, J. A., Jr.; Stratmann, R. E.; Burant, J. C.;
Dapprich, S.; Millam, J. M.; Daniels, A. D.; Kudin, K. N.;
Strain, M. C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi,
M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.;
Clifford, S.; Ochterski, J.; Petersson, G. A.; Ayala, P. Y.;
Cui, Q.; Morokuma, K.; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B.; Cioslowski, J.; Ortiz,
J. V.; Baboul, A. G.; Stefanov, B. B.; Liu ,G.; Liashenko,
A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R.
L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.;
Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.;
Johnson, B.; Chen, W.; Wong, M. W.; Andres, J. L.;
Gonzalez, C.; Head-Gordon, M.; Replogle, E. S.; Pople, J.
A. Gaussian 98, Revision A.9 Gaussian: Pittsburgh, PA,
3
58. Chai-Ho, Lee; Harold, Kohn J. Org. Chem. 1990, 55,
6098.
1998.
37. Grimm, H. G. Z. Electrochem. 1925, 31, 474.
38. Grimm, H. G. Z. Naturwissenschaften 1929, 17, 557.
39. Patani, G. A.; LaVoie, E. J. Chem. Rev. 1996, 96, 3147.
59. Paquin, A. M. Angew. Chem. 1948, A60, 316.
60. Litchfield, J. T.; Wilcoxon, F. J. Pharmacol. Exp. Ther.
1949, 96, 99.