Synthesis and anticonvulsant activity of amino acid-derived sulfamides

Article abstract of DOI:10.1021/jm800764p

Sulfamides are promising functions for the design of new antiepileptic drugs (Bioorg. Med. Chem. 2007, 15, 1556-1567; 5604-5614). Following previous research in this line, a set of amino acid-derived sulfamides has been designed, synthesized, and tested a

Full text of DOI:10.1021/jm800764p

1592
J. Med. Chem. 2009, 52, 1592–1601
Synthesis and Anticonvulsant Activity of Amino Acid-Derived Sulfamides
Luciana Gavernet,*,† Juan E. Elvira,† Gisela A. Samaja,† Valentina Pastore,† Mariana Sella Cravero, Andrea Enrique,†
Guillermina Estiu,‡ and Luis E. Bruno-Blanch*,†
Medicinal Chemistry, Department of Biological Sciences, Faculty of Exact Sciences, National UniVersity of La Plata, 47 and 115,
La Plata B1900BJW, Argentina, Walther Cancer Research Center and Department of Chemistry and Biochemistry, UniVersity of Notre Dame,
Notre Dame, Indiana 46556-5670
ReceiVed June 23, 2008
Sulfamides are promising functions for the design of new antiepileptic drugs (Bioorg. Med. Chem. 2007,
15, 1556-1567; 5604-5614). Following previous research in this line, a set of amino acid-derived sulfamides
has been designed, synthesized, and tested as new anticonvulsant compounds. The experimental data confirmed
the ability of some of the structures to suppress the convulsions originated by the electrical seizure (MES
test) at low doses (100 mg/kg).
Introduction
The past decades have witnessed many advances in the
development of new strategies for the treatment of epilepsy,
mainly focused in the prevention of seizures. The new antiepi-
leptic drugs (AEDsa) presently used provide adequate seizure
control in a significant number of the patients.1-4 Unfortunately,
it is estimated that up to 30% of the affected people are still
resistant to the available medication.5,6 Furthermore, many
AEDs have serious side effects, increasing their toxic actions
when a lifelong medication is required.7 As a result, intensive
research efforts are being devoted to find new antiepileptic
Figure 1. Structure of the pharmacophore proposed.17 The 3D
requirements for the structures to manifest the anti-MES activity can
be summarized in: (1) a polar moiety (atoms 1-3, in yellow), (2) a
hydrophobic chain (atoms 5-7 in green), placed in a conformation
defined by τ1, τ2, τ3, and d and connected through a link atom (atom
4, in cyan).
compounds with more selective activity and lower toxicity.8
The incomplete information about the cellular basis of human
epilepsy makes it difficult to find a common way to design new
drugs. Current AEDs can be broadly classified into four
categories on the basis of the main molecular mechanisms
through which they act. Their actions include: (i) modulation
of voltage-dependent Na+ or Ca2+ channels, (ii) enhancement
of GABA-mediated inhibition or other effect on the GABA
system, (iii) inhibition of synaptic excitation mediated by
ionotropic glutamate receptors, (iv) modulation of synaptic
release.9 However, the use of rational methodologies of design
that need the knowledge of the mechanism of action of the active
compounds is limited because most of the AEDs interact with
more than one receptor. The alternative rational design of new
AEDs based on pharmacophoric patterns overcome this dif-
ficulty as it works on the optimization of the potency of a
particular mode of action and is therefore broadly used in the
discovery of new chemical entities.10-15
the requirements imposed by a pharmacophore for the activity
in the maximal electroshock (MES) test,18 one of the most
popular seizure models, usually used together with the subcu-
taneous pentylenetetrazol (PTZ) test.18 The pharmacophore
previously defined consists of a polar group with a well
determined charge distribution, attached to a hydrophobic chain
containing at least three carbon atoms (Figure 1), in a well
defined spatial orientation.17 When sulfamide defines the polar
function and aryl or alkyl chains are used to satisfy the lipophilic
requirements, the activity of the resulting structures in the MES
test has been confirmed.16,17 With a particular aim in improving
the physiological characteristics of the drugs, we decided to
increase the diversity of our set including amino acids as one
of the substituents.
Amino acids and their derivatives have been investigated
for their anticonvulsant action, and some of them were found
to be potent AEDs. Several second-generation drugs, as well
as drugs in development, have this functionality in their
structures (Figure 2).8
Amino acids, the fundamental units of peptides, play a
significant role in medicinal chemistry. Small peptides represent
excellent targets for the design of new drugs due to their
potential ability to minimize the difficulties related to the
pharmacokinetic of larger peptides without losing the charac-
teristics involved in molecular recognition.19-21 Unfortunately,
even small peptides undergo limitations related to their poor
stability toward proteolysis, limited transport properties, rapid
metabolism/excretion through the liver and kidneys, and their
Recent research in our group has analyzed aryl and alkyl
sulfamides as new targets of antiepileptic drugs.16,17 The
structures were chosen as potentially active as they comply with
* To whom correspondence should be addressed. Phone: +54 0221-
4235333. Fax: +54 02214223409. E-mail: lgavernet@biol.unlp.edu.ar
(L.G.); lbb@biol.unlp.edu.ar (L.E.B.-B.).
†
Medicinal Chemistry, Department of Biological Sciences, Faculty of
Exact Sciences, National University of La Plata.
‡
Walther Cancer Research Center and Department of Chemistry and
Biochemistry, University of Notre Dame.
a Abbreviations: MES, maximal electroshock seizure; AEDs, antiepileptic
drugs; GABA, γ-amino butyric acid; VPA, valproic acid; PTZ, pentyle-
netetrazol seizure; CSI, chlorosulfonyl isocyanate; NIH, National Institutes
of Health; ADD, anticonvulsant drug development; ASP, anticonvulsant
screening project; DIAD, diisopropylazodicarboxylate, PEG, polyethylene
glycol; VRL, valrocemide; TPE, time of peak effect.
10.1021/jm800764p CCC: $40.75
2009 American Chemical Society
Published on Web 02/27/2009

Amino Acid-DeriVed Sulfamides
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6 1593
Figure 2. Amino acids and their derivatives acknowledged as antiepileptic drugs.
Figure 3. Chemical structures of the compounds synthesized.
inherent flexibility that enables interaction with multiple recep-
tors besides the target (with undesired side-effects). The
diminution of the peptide characteristics by means of structural
modifications defines a good strategy for the design of new
compounds with more desirable physiological and physico-
chemical characteristics (peptide mimics). In relation to this
approach, the urea moiety has been demonstrated to be a useful
nonhydrolyzable linker and/or hydrogen bond acceptor.22-25
Similarly, the sulfamide functionality has been studied as a
nonhydrolyzable component of peptide mimetics, showing
selectivity and inhibitory activity against proteases.26-30
We report herein the synthesis and anticonvulsant activity
of a set of amino acid-derived sulfamides. In some compounds,
the sulfamide is a nonhydrolyzable linker of two amino ester
groups (compounds 1-3, Figure 3), whereas in other structures
it connects a lipophilic (alkyl/aryl) group with amino esters
(10-12 and 14-16, Figure 3). Figure 3 also include some
intermediates whose anticonvulsant activity has been determined
(compounds 4-9 and the sulfamate 13). Butyl, benzyl, or
cyclohexyl groups have been chosen for the lipophilic chains
on the basis of previous data16 that showed a higher anti-MES
potency for sulfamides bearing these substituents.
We have also chosen a 2-propylpentyl substituent to build
the lipophilic chain, which is homologous to the hydrophobic
backbone in 2-propylpentanoic acid (valproic acid, VPA), one
of the first-line AEDs used in the long-term treatment of
epilepsy. This decision is further justified by the need of
designing VPA related compounds that conserve its anticon-
vulsant action avoiding its dangerous side effects (mainly related
with teratogenicity and hepatotoxicity).31,32 Amino acid deriva-
tives of VPA have been tested with promising results.33-35 In
Scheme 1. Synthetic Route for Symmetric Sulfamidesa
a 1: N-Xaa-O ) L-alanine; 2: N- Xaa-O ) L-valine; 3: N-Xaa-O )
ꢀ-alanine.
particular, N-valproyl glycinamide (named valrocemide: VRL,
Figure 2) has a broad spectrum of action and is currently
undergoing phase II clinical trials in patients with drug-refractory
epilepsy.35
Chemistry. The synthetic processes have been selected
according to the sulfamide substituents. The route used for the
amino acid-derived symmetric sulfamides is outlined in Scheme
1. Condensation of the corresponding salts of amino esters with
sulfuryl chloride in presence of triethylamine produces the
sulfamides 1-3.36
N-alkyl/aryl, N′-sulfamoylaminoesters (compounds 10-12
Scheme 2) were prepared by means of the usual procedure:37,38
one pot synthesis of N-terbutoxycarbonyl sulfamides from
chlorosulfonyl isocyanate (CSI), tert-butanol and the corre-
sponding amino ester in presence of triethylamine; followed by
alkylation under Mitsunobu conditions39 and then acidic hy-
drolysis (Scheme 2). The greater nucleophilicity of the nitrogen
atom of the N-acyl group in N-terbutoxycarbonyl sulfamides
(compounds 4-6, Scheme 2) allows the selective alkylation by
means of the Mitsunobu tandem triphenylphosphine (PPh3) and
diisopropylazodicarboxylate (DIAD).
To promote a higher efficiency in the synthetic procedure,
an alternative route has been considered: The reaction between

1594 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6
GaVernet et al.
Scheme 2a
a Synthetic route for N-alkyl amino acid derived sulfamides. 4: N-Xaa-O ) L-alanine; 5: N-Xaa-O ) ꢀ-alanine; 6: N-Xaa-O ) glycine; 7: N-Xaa-O )
glycine, R ) 2-propylpentyl; 8: N-Xaa-O ) ꢀ-alanine, R ) 2-propylpentyl; 9: N-Xaa-O ) glycine, R ) benzyl; 10: N-Xaa-O ) glycine, R ) 2-propylpentyl;
11: N-Xaa-O ) ꢀ-alanine, R ) 2-propylpentyl; 12: N-Xaa-O ) glycine, R ) benzyl.
Scheme 3. Alternative Synthetic Route for N-Alkyl Amino Acid Derived Sulfamidesa
a 13: HN-Xaa-O ) ꢀ-alanine; 14: HN-Xaa-O ) ꢀ-alanine, cyclohexyl; 15: HN-Xaa-O ) ꢀ-alanine, benzyl; 16: HN-Xaa-O ) ꢀ-alanine, butyl.
catechol sulfate (prepared with catechol and sulfuryl chloride)40
and the corresponding amino ester under controlled reaction
conditions (Scheme 3) to yield a sulfamate ester derivative
(compound 13 Scheme 3). The resulting sulfamate compound
reacts with the alkyl/aryl amine to yield nonsymmetric sulfa-
mides (structures 14-16, Scheme 3). This method reduces the
number of the steps of the reaction relative to the synthetic route
previously considered and was successfully applied to the
synthesis of aliphatic N,N′-disubstituted sulfamides.41
According to the synthetic procedures selected, the prepara-
tion of nonsymmetric sulfamides involves the formation of
intermediate products (4-9, Scheme 2 and 13, Scheme 3), which
were included in the biological analysis. Compounds 4-9 were
considered as sulfamide derivatives. Compound 13 presents a
sulfamate function that is related to the sulfamide moiety as a
bioisosteric partner according to Grimm’s hydride displacement
law.42,43
Pharmacology. The biological evaluation of the synthesized
compounds was performed following the standard procedures
proposed by The NIH anticonvulsant drug development (ADD)
program, via the anticonvulsant screening project (ASP).18 The
initial evaluation (phase 1) includes the use of two convulsant
tests: maximal electroshock seizure test (MES) and pentylene-
tetrazole test (PTZ).
The compounds were administrated to animals (mice) intra-
peritoneally at three doses (30, 100, and 300 mg/Kg), and all
the assays were performed at 0.5 and 4 h.
Quantitative biological studies (phase II) were performed for
the most promising compounds from phase I (in MES test). At
this stage, the anticonvulsant activity was expressed as median
effective dose, ED50, which determines the drug concentration
that is effective in the 50% of the tested animals. The evaluations
were performed at the time of peak effect (TPE) previously
determined.
Details of the evaluation of anticonvulsant activity are given
in the Experimental Section.
Results
The results of the biological evaluations are summarized
in Tables 1 and 2. The experimental data obtained from the
initial evaluation (phase 1, Table 1) allowed us to select the
most promising compounds to be promoted to the next stage
of the program: quantitative in vivo anticonvulsant evalua-
tions (phase II).
The results presented in Table 1 pointed out that several
compounds of the set with positive response in the MES test
show a phenytoin-like profile: they exhibit activity in the MES
test but they did not show protection in PTZ-induced convul-
sions, at the same doses and times evaluated. Molecules 11,
13, and 15 showed protection against both MES and PTZ test,
with responses at doses of 30 mg/kg in the last assay.
No toxicity was observed for the molecules of the set at the
evaluated doses. The lack of sedative effects at this early stage
The MES test is associated with the electrical induction of
the seizure, whereas PTZ test involves a chemical induction to
generate the convulsion. Toxicity is primary detected using the
standardized RotoRod test, which is also included in the primary
phase.

Amino Acid-DeriVed Sulfamides
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6 1595
Table 1. Pharmacological Profile (Phase I) of the Synthesized Compounds
compd
classa
dose (mg/kg)
activity MESb time (h)
TOXc time (h)
activity PTZdtime (h)
1, 2, 3, 4
0.5
4
0.5
4
0.5
4
1
3
1
1
3
2
3
2
3
3
1
1
3
1
1
1
1
30
100
300
0/3
0/4
0/3
0/3
0/4
0/3
0/5
0/8
0/5
0/5
0/7
0/5
0/2
0/4
0/2
0/2
0/3
0/2
2
30
100
300
0/3
1/4
1/3
0/3
0/3
0/3
0/6
0/7
0/5
0/6
0/6
0/5
0/3
0/3
0/2
0/3
0/3
0/2
3
30
100
300
0/3
1/4
1/3
0/3
0/4
0/3
0/5
0/6
0/5
0/5
0/6
0/5
0/2
0/2
0/2
0/2
0/2
0/2
4
30
100
300
0/3
0/3
0/3
0/3
0/3
0/3
0/5
0/5
0/5
0/5
0/5
0/5
0/2
0/2
0/2
0/2
0/2
0/2
5
30
100
300
0/3
0/3
1/3
0/3
0/3
0/3
0/5
0/5
0/5
0/5
0/5
0/5
0/2
0/2
0/2
0/2
0/2
0/2
6
30
100
300
0/3
0/3
0/3
0/3
0/3
0/3
0/5
0/5
0/5
0/5
0/5
0/5
0/2
0/2
0/2
0/2
0/2
0/2
7
30
100
300
0/4
0/3
0/3
0/3
0/3
1/3
0/4
0/3
0/3
0/3
0/3
0/3
0/2
0/2
0/2
0/2
0/2
0/2
8
30
100
300
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/2
0/2
0/2
0/2
0/2
0/2
9
30
100
300
0/3
0/3
0/3
0/3
0/3
0/3
0/5
0/5
0/5
0/5
0/5
0/5
0/2
0/2
0/2
0/2
0/2
0/2
10
11
12
13
14
15
16
30
100
300
0/3
1/3
1/2
0/3
1/3
2/3
0/5
0/5
0/5
0/5
0/5
0/5
0/3
0/3
0/3
0/3
0/3
0/3
30
100
300
1/3
0/3
1/3
3/3
0/3
1/3
0/5
0/5
0/3
0/5
0/5
0/3
1/2
2/2
NT
0/2
0/2
NT
30
100
300
0/3
0/3
0/2
0/3
0/3
0/2
0/5
0/5
0/4
0/5
0/5
0/4
0/2
0/2
0/2
0/2
0/2
0/2
30
100
300
0/3
1/3
0/3
0/3
1/3
0/3
0/6
0/6
0/6
0/6
0/6
0/6
1/3
0/3
1/2
0/3
0/3
0/3
30
100
300
0/3
1/3
0/3
0/3
2/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
NT
NT
NT
NT
NT
NT
30
100
300
0/3
1/3
1/3
0/3
0/3
0/3
0/6
0/6
0/6
0/6
0/6
0/5
0/3
0/3
0/2
1/3
0/3
0/3
30
100
300
1/3
1/3
2/3
1/3
1/3
1/3
0/6
0/3
0/3
0/6
0/6
0/6
0/3
0/3
0/3
0/3
0/3
0/3
a The tested compounds can be classified into four classes according to their activity:44 (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. We have found eight molecules that belong to class 1 anticonvulsants, the most potent class of antiepileptic drugs. b Maximal electroshock seizure.
c Toxicity evaluated in rotorod test. d Pentylentetrazol test. NT: not tested.
of the evaluation process supports the use of amino acids as
suitable functionalities for the design of anticonvulsant
compounds.
The most promising compounds are 10, 11, and 16, and for
them the ED50 values for the anticonvulsant activity in the MES
test, were determined. As mentioned before, ED50 measures the

1596 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6
GaVernet et al.
Table 2. Activity Values against MES Test (ED50, µmol/kg) and Time
of Peak Effect (TPE) Determined in Mice for the Sulfamide Derivatives
Designeda
MES test
compd
TPE (h)
ED50 (µmol/kg)
RPb
10
11
16
13
VRL
VPA
2
2
2
4
0.5
0.25
139
79
71
374
755
1008
7.3
12.8
14.2
2.7
1.3
1
a Experimental data for VPA, and VRL were taken from literature.12,35
b RP (relative potency) ) ED50VPA/ED50compound
.
dose that is effective in 50% of the tested animals; details of its
determination are given in Experimental Section. Compounds
11 and 16 show positive response at the doses assayed in phase
1 (see Table 1). Compound 10 is similar to 11 in having the
same hydrocarbon chain, which is similar also to the hydro-
phobic backbone in VPA. Finally, ED50 was also determined
for compound 13 because it is the only structure of the set
having a sulfamate function. The results are listed in Table 2,
together with the experimental data previously reported for
known anticonvulsant drugs structurally related.12,35
Figure 4. Structures selected for ED50 determination (Table 2). Atoms
are numbered for the centers that define the pharmacophoric pattern.
In the case of compounds 11 and 16, the pattern can be satisfied in
two different ways.
In spite of the results found in phase I for compounds 11
and 13, where the number of protected animals remained
constant or decreased at the higher dosage, typical dose-response
curves were found in phase II for all the four selected
compounds and ED50 values were calculated based on six
animals per dose. These results are not surprising considering
that biological data obtained from phase I are not enough to
claim a compound active. Accordingly, the SAR analyses have
been mainly based on the more reliable phase II derived data.
The pharmacological profile of the new compounds shown
in Table 2 is attractive, as they at least duplicate the protection
of VPA or VRL at this stage of anticonvulsant biological
evaluation. Particularly, the active compounds 10 and 11 contain
the 2-propylpentyl hydrocarbon chain as the lipophilic group,
linked through the sulfamide function to the amino esters (Figure
3). These structures exhibit some similarities with VRL, a
valproic acid derivative with a glycinamide moiety linked to
the valpromide function (Figure 2), but significantly improve
the antiepileptic activity, which, for compound 11, is almost
10 times higher than for VRL.
The structures in Table 2 have at least one substituent
composed by no less than three carbon atoms attached to the
sulfamide/sulfamate function (Figure 4). A superposition analy-
sis (Figure 5) shows that they are able to comply with the
requirements defined by the pharmacophore for the anti-MES
activity,2 which further demonstrates the capacity of the model
for the design of new active compounds. It is worth mentioning
that previous investigations demonstrated that VPA, VRL, and
other valproic acid derivatives also complain with the pharma-
cophore requirements.12,16
No positive response was detected for the sulfamides 1, 4, 6,
8, 9, and 12 in the initial evaluations of anticonvulsant activity
(Table 1). The biological data obtained for these compounds
should be considered as preliminary because only phase 1 of
the anticonvulsant program has been yet performed. Neverthe-
less, the proposed pharmacophore allows us to justify the lack
of activity of compounds 1, 4, and 6, as they do not comply
with the requirements of lipophilicity. This is not the case of
compounds 5, 7, 8, and 9, whose superposition is shown in
Figure 6. The compounds in Figure 6 show, as a common
feature, a Boc substituent of a sulfamide nitrogen. The inhibition
of the activity by this substitution can be originated in either
steric or electronic constrains. We are at this time more prompt
to associate it with an electronic effect for the reasons that will
be further discussed when analyzing the lower activity of
compounds 10 and 13 vs compounds 11 and 16.
Compounds 11 and 16 can satisfy the pharmacophoric
requirements in two different manners. Conversely, compound
10 can only match the requirements if the valproyl moiety is
overlapped with the lipophilic portion (Figure 4). The compari-
son of 10 and 11 shows that, overlapping the 2-propylpentyl
chains, a Gly substituent in the first, rather than ꢀ-Ala in the
second, is attached to the sulfamide nitrogen numbered as 3 in
the pharmacophoric pattern (compound 11b, Figure 4). The
attachment of a polar, electron attractor substituent closer to
nitrogen 3 has a negative effect, decreasing the activity of
compound 10 relative to compound 11. This fact can also help
to understand the lack of protection of compound 12 in phase
I. Compound 13 can be brought to the similarity analysis to
demonstrate that it places an oxygen atom in the same region
as compound 10 (Figure 7), a characteristic not found for the
most active compounds 11 and 16. Compounds 2, 3, 14, and
15 show some activity in phase I, and they comply with the
requirements of the previously proposed pharmacophore. Any
further SAR analysis was considered tentative as the ED50 values
have not been determined.
The previous SAR analysis shows that a polar, electron
attractor substituent attached near the nitrogen atom 3 of the
pharmacophore (oxygen atom 3 in sulfamate) severely hampers
the activity (compounds 10 and 13 vs compounds 11 and 16).
Moreover, the lack of antiepileptic activity of compounds 5, 7,
8, and 9 can be originated in a similar effect, leading us to infer
that this effect may be distance dependent, and can also explain
the diminished activity of compound 3 relative to compound
16. The best activity has been determined for compounds 11
and 16, which combine lipophilic and polar moieties. A polar,
electron attractor substituent close to atom 7 of the pharma-
cophore increase the potency relative to N,N-dibutyl-sulfamide
(ED50 ) 295 µmol/kg), but similar substitutions on the second
sulfamide nitrogen have a negative effect. The dependence of
this effect on the distance has to be analyzed in more detail.

Amino Acid-DeriVed Sulfamides
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6 1597
Figure 7. Compounds 10 (green) and 13 (yelllow) aligned according
to the pharmacophore requirements. Hydrogen atoms were ommited.
Figure 5. Superposition of the compounds whose ED50 was deter-
mined, aligned in the conformation defined by the pharmacophore. For
molecules 11 and 16, the amino ester hydrocarbon chains were used
as the nonpolar requirement (structures 11a and 16a in Figure 4). Color
code as follow: compound 10, green; compound 11, orange; compound
13, yellow; compound 16, cyan. Atoms are numbered for the centers
that define the pharmacophoric pattern. Hydrogen atoms were omitted
for clarity.
Figure 8. New pharmacophoric pattern proposed, which establish
conditions for the group attached to the polar end, represented by atom
8. The anti-MES requirements can be summarized as: (1) a polar moiety
(atoms 1-3, in yellow), (2) a hydrophobic chain (atoms 5-7 in green),
placed in a conformation defined by t1, t2, t3 and d and connected to
the polar moiety through a link atom (atom 4, in cyan), (3) any group
attached to atom 3 should be nonpolar or H.
Figure 6. (A) Structures of the compounds 7 (green), 8 (yellow), and
9 (blue). Compound 8 was fitted using the hydrocarbon chain as
nonpolar requirement. (B) Structures of the compounds 5 (green) and
8 (yellow). Compound 8 was fitted using the amino ester hydrocarbon
chain as nonpolar requirement. Atoms are numbered for the centers
that define the pharmacophoric pattern. Hydrogen atoms were omitted.
It seems early in this research to establish uniquely new
pharmacophore requirements for anti-MES activity. This will
require a systematic analysis of a series of compounds bearing
polar substitutions at different distances of the sulfamide moiety.
Nevertheless, from this study, we can better tune the charac-
teristics of a possible substitution on N3, which are described
by the new pharmacophore shown in Figure 8.
We hope that the research presented here will guide rational
modifications that lead to new compounds of better potency,
achieved by a balanced combination of polar and nonpolar
groups in N,N′-disubstituted sulfamides.
On the basis of the previous analysis, a new requirement can
be proposed, associated with the nature a substituent attached
to N 3. This requirement is sketched in Figure 8.
Conclusions
Sulfamides have proven to be attractive targets for the design
of new antiepileptic drugs. Compounds containing this func-
tionality have been designed, synthesized, and evaluated in our
research group, with promising results.16,17 Along this research,
a pharmacophore has been proposed that has guided our further
efforts toward the optimization of the pharmacological profile
of new structures.16,17
Experimental Section
Chemistry: General Information. Melting points were deter-
mined using capillary tubes with an electrothermal melting point
apparatus and are uncorrected. Thin-layer chromatography (TLC)
was performed 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
With the aim of improving the physiological and physico-
chemical characteristics of the drugs, we have synthesized amino
acid-substituted sulfamides and tested them in their ability to
suppress the epileptic seizure. The results are encouraging, as
compounds as active as valpromide (ED50 ) 353 µmol/kg),
1
60 (70-230 mesh, Merck, ref 1.07734.1000). Then 200 MHz H
NMR and 75.4 MHz 13C NMR spectra were recorded on a Varian
Gemini 200 spectrometer. The chemical shifts were reported in ppm
(δ scale) relative to internal TMS, and coupling constants were
reported in Hertz (Hz). IR spectra were run on a FT/IR Perkin-
Elmer spectrophotometer. Absorption values were expressed as
wave numbers (cm-1); only significant absorption bands are given.
ES-MS spectra were recorded for some compounds with an Agilent
1100 series spectrometer; only molecular ions (M + H, M - H,
and M + Na) are given. Analytical grade solvents were used for
crystallization, while pure for synthesis solvents were used in the
reactions, extractions, and column chromatography. Commercial
amines were distilled prior to their use. All reagents used in the
present study were of analytical grade (Sigma-Aldrich, Fluka).
Elemental analyses were carried out at the Mycroanalysis Service
zonizamide (ED50 ) 92 µmol/kg), or phenobarbital (ED50
)
94 µmol/kg) have been attained.16 A SAR analysis has allowed
us to extrapolate new requirements for the activity, mainly
related to the characteristics of a second substituent in the
sulfamide function. The comparison of N,N-dibutyl-sulfamide
(ED50 ) 295 µmol/kg) and compound 16 (ED50 ) 71 µmol/
kg), shows that a carboxymethy substituent in the position 7 of
the pharmacophore has a positive effect in the activity.
Nevertheless, substitutions with polar, electron attractor sub-
stituents on both nitrogen atoms invert the trend, with a negative
effect in the activity.

1598 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6
GaVernet et al.
of INQUIMAE (Argentina) and results were within (0.3% of the
theoretical values.
(C(CH3)3), 51.98 (O-CH3), 39.34 (N-C ꢀ-Ala), 33.46 (C-CO),
27.94 (CH3 tert-butyl). Anal. calcd for C9H18N2O6S: C 38.3, H 6.4,
N 9.9, S 11.4; found: C 38.5, H 6.3, N 9.7, S 11.5.
Methyl Esters of Amino Acid Symmetric Sulfamides. The
synthesis of these compounds, starting from the corresponding salt
of the amino acid esters, triethylamine and sulfuryl chloride was
carried out according to the general procedures previously de-
scribed.36
Methyl [N-(N′-tert-Butoxycarbonyl)-sulfamoyl]-glycinate (6).37
Melting point 106-108 °C. IR (KBr) ν 3264, 1748, 1720, 1364,
1
1148. H NMR (CDCl3) δ 7.52 (s broad, 1H, NH-Boc), 5.79 (s
broad, 1H, NH-Gly), 3.99 (d, J ) 5.4 Hz, 2H, CH2), 3.78 (s, 3H,
O-CH3), 1.50 (s, 9H, CH3 tert-butyl). 13C NMR (CDCl3) δ 169.25
(CdO ester), 149.97 (CdO Boc), 84.06 (C(CH3)3), 52.61 (O-CH3),
44.91 (N-C), 27.96 (CH3 tert-butyl). Anal. calcd for C8H16N2O6S:
C 35.8, H 6.0, N 10.4, S 12.0; found: C 35.8, H 6.1, N 10.2, S
12.0.
N,N′-Sulfonyl Bis-L-alanine Dimethyl Ester (1).36 Melting
1
point 125-126 °C. IR (KBr) ν 3271, 1738, 1348, 1132 cm-1. H
NMR (CDCl3) δ 5.26 (d broad, J ≈ 7.0 Hz, 2H, NH), 4.10 (m,
2H, CH), 3.77 (s, 6H, O-CH3), 1.45 (d, J ) 7.1 Hz, 6H, CH3). 13
C
NMR (CDCl3) δ 173.66 (CdO), 52.69 (CH), 51.81 (O-CH3), 19.24
(CH3). Anal. calcd for C8H16N2O6S: C 35.8, H 6.0, N 10.4, S 12.0;
found: C 35.7, H 6.1, N 10.3, S 12.0.
General Procedure of Mitsunobu Reaction. The reactions were
performedfollowingtheexperimentaldataachievedfromliterature,37,38
using equimolar quantities of the tandem PPh3/DIAD.39
N,N′-Sulfonyl Bis-L-valine Dimethyl Ester (2).36 Melting point
1
78-79 °C. IR (KBr) ν 3321, 3268, 1738, 1327, 1138 cm-1. H
Methyl [N-(N′-2-Propylpentyl, N′-tert-Butoxycarbonyl)-sulfa-
moyl]-glycinate (7). To a cold solution (0 °C) of PPh3 (0.97 g, 3.7
mmol) and 2-propyl-1-pentanol (0.6 mL, 3.7 mmol) in THF (4.0
mL) was added a solution of the [Boc-sulfamide] amino ester 6
(1.00 g, 3.7 mmol) and DIAD (0.8 mL, 3.7 mmol) in THF (4 mL).
The reaction medium was stirred at 0 °C for 1 h under argon
atmosphere. The solvent was removed under reduced pressure, and
the crude residue was purified by chromatography (CH2Cl2)
followed by crystallization (hexane), affording the product as a
white solid (1.34 g, 74%). Melting point 57.5-58 °C. IR (KBr) ν
NMR (CDCl3) δ 5.10 (d, J ) 9.5 Hz, 2H, NH), 3.88 (dd, J ) 9.5,
4.5 Hz, 2H, CH-N), 3.77 (s, 6H, O-CH3), 2.13 (m, 2H, CH
isopropyl), 1.01 (d, J ) 6.8 Hz, 6H, CH3 isopropyl), 0.90 (d, J )
6.8 Hz, 6H, CH3 isopropyl). 13C NMR (CDCl3) δ 172.85 (CdO),
61.13 (C-N), 52.39 (O-CH3), 31.47 (CH isopropyl), 18.78 (CH3
isopropyl), 17.43 (CH3 isopropyl). Anal. calcd for C12H24N2O6S:
C 44.4, H 7.5, N 8.6, S 9.9; found: C 44.7, H 7.4, N 8.3, S 9.7.
N,N′-Sulfonyl Bis-ꢀ-alanine Dimethyl Ester (3). A solution of
H-ꢀ-Ala-OMe·HCl (2.08 g, 14.6 mmol) and CH2Cl2 (50 mL) was
cooled to 0 °C. Et3N (6.12 mL, 43.8 mmol) was added slowly, and
the resulting solution was stirred for 20 min. A solution of SO2Cl2
(0.6 mL, 7.31 mmol) in dichloromethane (5.0 mL) was added
dropwise in dark conditions over 40 min. The reaction mixture was
warmed to room temperature, stirred for 4 h, and monitored by
TLC (SiO2). The medium was diluted with 50.0 mL of CH2Cl2
and washed with aqueous NaHSO4 and brine (3×). The solution
was dried (Na2SO4), filtered, and concentrated under reduced
pressure. Crystallization with diethyl ether afforded the product as
a white solid (0.41 g, 21%). Melting point 40.5-41 °C. IR (KBr)
ν 3301, 1736, 1323, 1153 cm-1. 1H NMR (CDCl3), δ 5.01 (t, J )
6.4 Hz, 2H, NH), 3.72 (s, 6H, O-CH3), 3.31 (system AM2 × 2, J
) 6.4, 6.1 Hz, 4H, N-CH2), 2.03 (t, J ) 6.1 Hz, 4H, CH2-CO).
13C NMR (CDCl3) δ 172.55 (CdO), 51.94 (O-CH3), 38.72 (C-N),
33.76 (C-CO). Anal. calcd for C8H16N2O6S: C 35.8, H 6.0, N 10.4,
S 12.0; found: C 35.6, H 5.7, N 10.5, S 12.2.
1
3368, 2960, 2932, 2870, 1733, 1706, 1358, 1142 cm-1. H NMR
(CDCl3) δ 5.88 (t, J ) 5.4 Hz, 1H, NH-Gly), 3.87 (d, J ) 5.4 Hz,
2H, CH2 Gly), 3.78 (s, 3H, O-CH3), 3.54 (d, J ) 7.3 Hz, 2H, N-CH2
2-propylpentyl), 1.79 (m, 1H, CH 2-propylpentyl), 1.54 (s, 9H, CH3
tert-butyl), 1.39-1.19 (m, 8H, CH2-CH2 2-propylpentyl), 0.89 (t,
J ) 6.7 Hz, 6H, CH3 2-propylpentyl). 13C NMR (CDCl3), δ: 168.90
(CdO ester), 152.09 (CdO Boc), 84.19 (C(CH3)3), 52.62 (O-CH3),
52.00 (N-C 2-propylpentyl), 44.82 (N-C Gly), 37.56 (ꢀ-C
2-propylpentyl), 33.23 (γ-C 2-propylpentyl), 27.93 (CH3 tert-butyl),
19.34 (δ-C 2-propylpentyl), 14.38 (CH3 2-propylpentyl). Anal. calcd
for C16H32N2O6S: C 50.5, H 8.5, N 7.4, S 8.4; found: C 50.5, H
8.6, N 7.1, S 8.3.
Methyl [N-(N′-2-Propylpentyl, N′-tert-Butoxycarbonyl)-sulfa-
moyl]-ꢀ-alaninate (8). To a cold solution (0 °C) of PPh3 (4.52 g,
17.2 mmol) and 2-propyl-1-pentanol (2.7 mL, 17.2 mmol) in THF
(19.0 mL) was added a solution of the [Boc-sulfamide] amino ester
5 (4.86 g, 17.2 mmol) and DIAD (3.39 mL, 17.2 mmol) in THF
(19.0 mL). The reaction medium was stirred at 0 °C for 2 h under
argon atmosphere. The solvent was removed under reduced pressure
and the crude residue was purified by chromatography (CH2Cl2)
followed by crystallization (hexane), affording the product as a
white solid (3.97 g, 59%). Melting point 36-37 °C. IR (KBr) ν
MethylEstersof[N-(N′-tert-Butoxycarbonyl)-sulfamoyl]Ami-
no Acids. Typically the synthesis was carried out according to
literature procedures. The reaction involved the use of chlorosul-
fonyl isocianate (CSI), tert-butanol and the corresponding salt of
the amino acid esters.37
(S)(-)-Methyl [N-(N′-tert-Butoxycarbonyl)-sulfamoyl]-alaninate
(4).37 Melting point 126-127 °C. IR (KBr) ν 3296, 3267, 1745,
1
1
3368, 2960, 2933, 2872, 1762, 1704, 1358, 1141 cm-1. H NMR
1720, 1371, 1150 cm-1. H NMR (CDCl3) δ 7.56 (s, 1H, NH-
(CDCl3) δ 5.89 (t, J ) 6.6 Hz, 1H, NH-ꢀ-Ala), 3.71 (s, 3H, O-CH3),
3.57 (d, J ) 7.3 Hz, 2H, N-CH2 2-propylpentyl), 3.25 (system
AM2X2, J ) 6.6, 6.1 Hz, 2H, N-CH2 ꢀ-Ala), 2.60 (t, J ) 6.1 Hz,
2H, CH2-CO), 1.81 (m, 1H, CH 2-propylpentyl), 1.54 (s, 9H, CH3
tert-butyl), 1.39-1.22 (m, 8H, CH2-CH2 2-propylpentyl), 0.89 (t,
J ) 6.6 hz, 6H, CH3 2-propylpentyl). 13C NMR (CDCl3) δ 172.19
(CdO ester), 153.31 (CdO Boc), 84.33 (C(CH3)3), 52.20 (O-CH3),
52.10 (N-C 2-propylpentyl), 39.4 (N-C ꢀ-Ala), 37.81 (ꢀ-C
2-propylpentyl), 34.13, (C-CO), 33.67 (γ-C 2-propylpentyl), 28.20
(CH3 tert-butyl), 19.62 (δ-C 2-propylpentyl), 14.63 (CH3 2-pro-
pylpentyl). Anal. calcd for C17H34N2O6S: C 51.8, H 8.7, N 7.2, S
8.1; found: C 51.5, H 8.9, N 7.5, S 8.2.
Boc), 5.91 (d, J ) 8.1 Hz 1H, NH Ala), 4.26 (m, 1H, CH), 3.77 (s,
3H, O-CH3), 1.50 (s, 9H, CH3 tert-butyl), 1.47 (d, J ) 7.3 Hz, 3H,
CH3 Ala). 13C NMR (CDCl3) δ 172.44 (CdO ester), 149.95 (CdO
Boc), 83.92 (C(CH3)3), 52.73 (CH), 52.39 (O-CH3), 27.91 (CH3
tert-butyl), 19.31 (CH3 Ala). Anal. calcd for C9H18N2O6S: C 38.3,
H 6.4, N 9.9, S 11.4; found: C 38.2, H 6.4, N 9.8, S 11.5.
Methyl [N-(N′-tert-Butoxycarbonyl)-sulfamoyl]-ꢀ-alaninate
(5). A solution of CSI (2.5 mL, 28.7 mmol) and tert-butanol (4.8
mL, 71.8 mmol) in CH2Cl2 (40.0 mL) was added to a cold solution
(0 °C) of H-ꢀ-Ala-OMe·HCl (3.80 g, 27.8 mmol) and Et3N (8.0
mL, 56.9 mmol) in CH2Cl2 (60.0 mL). The reaction mixture was
warmed to room temperature, stirred for 18 h, and monitored by
TLC (SiO2). The medium was diluted with 50 mL CH2Cl2 and
washed with 1% acetic acid (2×) and brine (2×). The solution
was dried (Na2SO4), filtered, and concentrated under reduced
pressure. Crystallization with hexane/CH2Cl2 afforded the product
as a white solid (4.83 g, 62%). Melting point 103-105 °C. IR (KBr)
Methyl [N-(N′-Benzyl, N′-tert-Butoxycarbonyl)-sulfamoyl]-gly-
cinate (9).37 Melting point 114-115 °C. IR (KBr) ν 3331, 3091,
1
3035, 1734, 1369, 1154. H NMR (CDCl3), δ 7.38-7.24 (m, 5H,
Ar-H), 5.74 (t, J ) 5.4 Hz, 1H, NH Gly), 4.83 (s, 2H, CH2 benzyl),
3.69 (s, 3H, O-CH3), 3.62 (d, J ) 5.4 Hz, 2H, CH2 Gly), 1.52 (s,
9H, CH3 tert-butyl). 13C NMR (CDCl3) δ 168.81 (CdO ester),
1
ν 3279, 3208, 1736, 1701, 1370, 1147 cm-1. H NMR (CDCl3) δ
7.39 (s, 1H, NH-Boc), 5.74 (t, J ) 6.1 Hz, 1H, NH ꢀ-Ala), 3.72
(s, 3H, O-CH3), 3.38 (system AM2X2, J ) 6.1, 6.1 Hz, 2H, N-CH2),
2.64 (t, J ) 6.1 Hz 2H, CH2-CO), 1.51 (s, 9H, CH3 tert-butyl).
13C NMR (CDCl3) δ 172.05 (CdO ester), 150.07 (CdO Boc), 84.02
151.67 (CdO Boc), 137.48 (C1-Ar), 128.49, 128.11, 127.75 (C2,3,4
-
Ar), 84.71 (C(CH3)3), 52.50 (O-CH3), 50.59 (CH2 benzyl), 44.43
(N-C Gly), 27.95 (CH3 tert-butyl). Anal. calcd for C15H22N2O6S:
C 50.3, H 6.2, N 7.8, S 8.9; found: C 50.5, H 6.5, N 7.5, S 9.0.

Amino Acid-DeriVed Sulfamides
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6 1599
General Procedure for Acidic Decarbamylation. The N-Boc
(alkyl/aryl) sulfamides derivatives (7-9) were treated with a
solution of trifluoroacetic acid in CH2Cl2 as described in literature.37
Methyl [N-(N′-2-Propylpentyl)-sulfamoyl]-glycinate (10). A solu-
tion of 50% v/v of trifluoroacetic acid (1.5 mL, 18.9 mmol) in
CH2Cl2 was added dropwise to the N-Boc alkyl sulfamide 7 (0.79
g, 2.1 mmol), which was previously dissolved in 22.0 mL of CH2Cl2
and cooled to 0 °C. The reaction medium was warmed to room
temperature and stirred for 21 h, concentrated under reduced
pressure, and coevaporated with diethyl ether. The crude residue
was purified by chromatography (CH2Cl2), affording the product
as a white solid (0.24 g, 41%). Melting point 41-42 °C. IR (KBr)
13C NMR (CDCl3) δ 171.24 (CdO), 149.81 (C-OH), 137.69 (C1
Ar), 127.47, 123.58, 119.13, 117.38 (C2,3,4,5 Ar), 51.55 (O-CH3),
38.68 (N-C-ꢀ-Ala), 33.78 (C-CO). Anal. calcd for C10H13NO6S:
C 43.6, H 4.7, N 5.1, S 11.7; found: C 43.6, H 4.7, N 5.1, S 11.7.
MS (ES): m/z 274.0 (M - H).
Methyl [N-(N′Cyclohexyl)-sulfamoyl]-ꢀ-alaninate (14). A so-
lution of cyclohexylamine (0.44 g, 4.4 mmol) and acetonitrile (5.0
mL) was added dropwise to a solution of the sulfamate 13 (1.1 g.,
4 mmol) in 15.0 mL of acetonitrile at 0 °C under dry argon. The
reaction medium was stirred, warmed, and refluxed during 6 h. The
crude product was concentrated under reduced pressure and purified
by chromatography (CH2Cl2) to give white solid that was crystal-
lized with CH2Cl2 (0.61 g, 58%). Melting point 49-50 °C. IR (KBr)
ν 3300, 3264, 1740, 1325, 1140 cm-1. 1H NMR (CDCl3) δ 5.00 (t,
J ) 6.3 Hz, 1H, NH-ꢀ-Ala), 4.57 (d broad, 1H, NH-cyclohexyl),
3.68 (s, 3H, O-CH3), 3.27 (system AM2X2, J ) 6.3, 6.2 Hz 2H,
N-CH2 ꢀ-Ala), 2.60 (t, J ) 6.2, 2H: CH2-CO), 1.98-1.16 (m,
10H, CH2-cyclohexyl).13C NMR (CDCl3) δ 172.79 (CdO), 52.92
(O-CH3), 52.13 (N-C-cyclohexyl), 38.96 (N-C-ꢀ-Ala), 34.13 (C-
CO), 34.13 (ꢀ-C cyclohexyl), 25.48 (γ-C cyclohexyl), 25.00 (δ-C
cyclohexyl). Anal. calcd for C10H20N2O4S: C 45.5, H 7.6, N 10.6,
S 12.1; found: C 45.4, H 7.6, N 10.7, S 12.2. MS (ES): m/z 265.0
(M + H), 287.0 (M + Na).
γ 3350, 3285, 2971, 2928, 1734, 1328, 1143 cm-1 1H NMR
.
(CDCl3) δ 5.06 (s broad, 1H, NH-Gly), 4.40 (s broad, 1H, NH
2-propylpentyl), 3.83 (s, 3H, O-CH3), 3.80 (s broad, 2H, CH2 Gly),
2.97 (d, J ) 5.9 2H, N-CH2 2-propylpentyl), 1.55 (m, 1H, CH
2-propylpentyl), 1.37-1.20 (m, 8H, CH2-CH2 2-propylpentyl), 0.88
(t, J ) 6.7, CH3 2-propylpentyl). 13C NMR (CDCl3) δ 170.56 (CdO
ester), 52.83 (O-CH3), 46.49 (N-C 2-propylpentyl), 44.51 (N-C
Gly), 37.44 (ꢀ-C 2-propylpentyl), 34.01 (γ-C 2-propylpentyl), 19.86
(δ-C 2-propylpentyl), 14.38 (CH3 2-propylpentyl). Anal. calcd for
C11H24N2O4S: C 47.1, H 8.6, N 10.0, S 11.4; found: C 47.0, H 8.7,
N 10.2, S 11.5.
Methyl [N-(N′-2-Propylpentyl)-sulfamoyl]-ꢀ-alaninate (11). A
solution of 50% v/v of trifluoroacetic acid (2.5 mL, 33.9 mmol) in
CH2Cl2 was added dropwise to the N-Boc alkyl sulfamide 8 (3.97
g, 10.1 mmol), which was previously dissolved in 25.0 mL of
CH2Cl2 and cooled to 0 °C. The reaction medium was warmed to
room temperature and stirred for 44 h, concentrated under reduced
pressure. The crude residue was purified by chromatography
(CH2Cl2) followed by crystallization (hexane), affording the product
as a white solid (1.03, 36%). Melting point 48-49.5 °C. IR (KBr),
γ 3357, 3286, 2971, 2942, 1757, 1329, 1157. 1H NMR (CDCl3) δ
4.94 (s broad, 1H, NH-ꢀ-Ala), 4.32 (s broad, 1H, NH 2-propyl-
pentyl), 3.72 (s, 3H, O-CH3), 3.31 (t broad, J ) 6.1 Hz, 2H, N-CH2
ꢀ-Ala), 2.95 (d broad, J ) 5.8 Hz, 2H, N-CH2 2-propylpentyl),
2.64 (t, J ) 6.1 Hz, 2H, CH2-CO), 1.55 (m, 1H, CH 2-propyl-
pentyl), 1.49-1.20 (m, 8H, CH2-CH2 2-propylpentyl), 0.87 (t, J
) 6.6 Hz, 6H, CH3 2-propylpentyl). 13C NMR (CDCl3) δ 172.84
(CdO), 52.18 (O-CH3), 46.44 (N-C 2-propylpentyl), 38.95 (N-C-
ꢀ-Ala), 37.45 (ꢀ-C 2-propylpentyl), 34.13, (C-CO), 34.05 (γ-C
2-propylpentyl), 19.90 (δ-C 2-propylpentyl), 14.53 (CH3 2-propy-
lpentyl). Anal. calcd for C12H26N2O4S: C 49.0, H 8.8, N 9.5, S
10.9; found: C 49.0, H 8.9, N 9.4, S 10.9.
Methyl [N-(N′Benzyl)-sulfamoyl]-ꢀ-alaninate (15). A solution
of benzylamine (1.41 g, 13.2 mmol) and acetonitrile (5.0 mL) was
added dropwise to a solution of the sulfamate 13 (3.3 g., 12 mmol)
in 15.0 mL of acetonitrile at 0 °C under dry argon. The reaction
medium was stirred, warmed, and refluxed during 16 h. Workup
required washed with 1 N NaOH (2×), brine (1×), dried (Na2SO4),
and concentrated under reduced pressure. The crude product was
purified by chromatography (CH2Cl2) to give white solid, which
was crystallized with CH2Cl2 (1.63 g, 50%). Melting point: 59-60
°C. IR (KBr) γ 3264, 3250, 3030, 1744, 1319, 1154 cm-1. 1H NMR
(CDCl3), δ 7.35-7.25 (m, 5H, Ar-H), 5.03 (t, J ) 6.3, 1H, NH
ꢀ-Ala), 4.96 (t, J ) 6.3, 1H, NH-benzyl), 4.17 (d, J ) 6.3, 2H,
CH2-benzyl), 3.66 (s, 3H, O-CH3), 3.23 (system AM2X2, J ) 6.25,
6.25 N-CH2 ꢀ-Ala), 2.52 (t, J ) 6.3 2H, CH2-CO). 13C NMR
(CDCl3) δ 172.78 (CdO), 137.08 (C1 Ar), 128.97, 128.29, 128.13
(C2,3,4 Ar), 52.17 (O-CH3), 47.40 (CH2 benzyl), 38.90 (N-C ꢀ-Ala),
34.06 (C-CO). Anal. calcd for C11H16N2O4S: C 48.5, H 5.9, N 10.3,
S 11.8; found: C 48.6, H 5.8, N 10.3, S 11.7. MS (ES): m/z: 273.0
(M + H), 295.0 (M + Na).
Methyl [N-(N′Butyl)-sulfamoyl]-ꢀ-alaninate (16). A solution
of butylamine (0.64 g, 8.8 mmol) and acetonitrile (5.0 mL) was
added dropwise to a solution of the sulfamate 13 (2.2 g., 8 mmol)
in 15.0 mL of acetonitrile. The reaction medium was stirred,
warmed, and refluxed during 6 h. Workup required washed with 1
N NaOH (2×) and brine (1×), dried over Na2SO4, and concentrated
under reduced pressure. The crude product was purified by
chromatography (CH2Cl2) to give white solid, which was crystal-
lized with CH2Cl2 (0.94 g, 50%). Melting point: 47-48 °C. IR
(KBr) ν 3281, 3261, 1737, 1142. 1H NMR (CDCl3) δ 5.03 (t, J )
6.4, 1H, NH ꢀ-Ala), 4.60 (t, J ) 5.9 1H, NH-butyl), 3.68 (s, 3H,
O-CH3), 3.27 (system AM2X2, J ) 6.4, 6.4 N-CH2 ꢀ-Ala), 2.99
(m, 2H, N-CH2 butyl), 2.6 (t, J ) 6.4 2H, CH2-CO ꢀ-Ala),
1.55-1.28 (m, 4H, CH2-CH2 butyl), 0.89 (t, J ) 6.9 3H, CH3
butyl). 13C NMR (CDCl3) δ 172.78 (CdO ester), 52.12 (O-CH3),
43.12 (R-C butyl), 38.92 (N-C ꢀ-Ala), 34.16 (C-CO ꢀ-Ala), 31.74
(ꢀ-C butyl), 20.07 (γ-C butyl), 13.82 (CH3-butyl). Anal. calcd for
C8H18N2O4S: C 40.3, H 7.6, N 11.8, S 13.4; found: C 40.2, H 7.7,
N 11.8, S 13.4. MS (ES): m/z: 239.0 (M + H), 261.0 (M + Na).
Biological Data. The evaluation of the anticonvulsant activity
was performed by following the anticonvulsant drug development
(ADD) program of the National Institutes of Health.45 Adult male
albino mice (18-23 g) were used as experimental animals. Animals
of the same age and weight have been selected 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% polyethylene glycol 400 (PEG)
and 10% water. The structures tested were dissolved properly in
Methyl [N-(N′-Benzyl)-sulfamoyl]-glycinate (12).37 Melting point
72-72.5 °C. IR (KBr) ν 3297, 3280, 3064, 3034, 1741, 1359, 1154.
1H NMR (CDCl3) δ 7.65-7.26 (m, 5H: Ar-H), 5.02 (t, J ≈ 5.5
Hz, 1H, NH Gly), 4.81 (t, J ≈ 6.0 Hz, 1H, NH-benzyl), 4.17 (d, J
) 6.0 Hz, 2H, CH2 benzyl), 3.73 (d, J ) 5.5 Hz, 2H, CH2 Gly),
3.67 (s, 3H, O-CH3). 13C NMR (CDCl3) δ 170.44 (CdO ester),
136.86 (C1-Ar), 128.99, 128.27, 128.18 (C2,3,4-Ar), 52.83 (O-CH3),
47.50 (CH2 benzyl), 44.46 (N-C Gly). Anal. calcd for
C10H14N2O4S: C 46.5, H 5.5, N 10.8, S 12.4; found: C 46.4, H 5.6,
N 11.1, S 12.4.
General Procedure for the Synthesis via Catechol Sulfate.
The reaction starts with the preparation of the sulfamate intermediate
13, using procedures reported in literature.40 The product reacts
with the corresponding amine to give the expected sulfamide.
2-Hydroxyphenyl-N-ꢀ-alanine-methyl Ester Sulfamate (13). A
solution of catechol sulfate (5.68 g., 33.0 mmol) in 10.0 mL of
CH2Cl2 was added dropwise to a solution of H-ꢀ-Ala-OMe.HCl
(4.17 g, 30.0 mmol) and triethylamine (9.2 mL, 66.0 mmol) in 50.0
mL of CH2Cl2 with vigorous stirring at 0 °C under dry argon. After
6 h, the reaction mixture was washed with 15 mL of 5%
hydrochloric acid (3×), dried over MgSO4, and concentrated under
reduced pressure. Crystallization with CH2Cl2 afforded the product
as a white solid (6.60 g, 80.0%). Melting point 102-104 °C. IR
(KBr) ν 3484, 3208, 1712, 1374, 1151. 1H NMR (CDCl3) δ
7.26-6.87 (m, 4H, Ar-H), 6.45 (s broad, 1H, OH), 5.74 (s broad,
1H, NH-ꢀ-Ala), 3.78 (s, 3H, O-CH3), 3.52 (system AM2X2, J )
5.8, 5.8 Hz 2H, N-CH2 ꢀ-Ala), 2.65 (t, J ) 5.8, 2H, CH2-CO).

1600 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 6
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Quantitative studies were conducted at the previously determined
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groups of six albino mice. Different doses were used for each drug
at TPE. The method of Litchfield and Wilcoxon was used to
compute the ED50 values.46
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Acknowledgment. L. E. Bruno-Blanch is a member of the
Facultad de Ciencias Exactas, Universidad Nacional de La Plata;
L. Gavernet, G. A. Samaja, and V. Pastore are fellowship
holders of Consejo Nacional de Investigaciones Cient´ıficas y
Te´cnicas de la Repu´blica Argentina (CONICET); J. E. Elvira
is a fellowship holder of Agencia Nacional de Promocio´n
Cient´ıfica y Tecnolo´gica. We also thank the reviewers, who have
helped with the improvement of the quality of our work with
their valuable comments and suggestions. This research was
supported in part through grants from Agencia de Promocio´n
Cient´ıfica y Tecnolo´gica (PICT 06-11985/2004), CONICET, and
Universidad Nacional de La Plata, Argentina.
Supporting Information Available: Data from microanalysis
for all compounds and ES-MS spectra for structures 13 to 16 are
available. This material is available free of charge via the Internet
at http://pubs.acs.org.
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