Synthesis and biological evaluation of 4-chloro-3,5- dinitrobenzotrifluoride analogues as antileishmanial agents

Article abstract of DOI:10.1021/jm9804073

Desnitro analogues of 4-chloro-3,5-dinitrobenzotrifluoride (chloralin) (2), an in vitro microtubule inhibitor of several Leishmania species, have been synthesized from 2-halo-5-(trifluoromethyl)benzenesulfonyl chlorides 4 and 5. The analogues exhibited mo

Full text of DOI:10.1021/jm9804073

J . Med. Chem. 1998, 41, 4885-4889
4885
Syn th esis a n d Biologica l Eva lu a tion of 4-Ch lor o-3,5-d in itr oben zotr iflu or id e
An a logu es a s An tileish m a n ia l Agen ts
Kevin K. Pitzer,* Karl A. Werbovetz, J ames J . Brendle, and J ohn P. Scovill
Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Washington, D.C., 20307-5100
Received J uly 10, 1998
Desnitro analogues of 4-chloro-3,5-dinitrobenzotrifluoride (chloralin) (2), an in vitro microtubule
inhibitor of several Leishmania species, have been synthesized from 2-halo-5-(trifluoromethyl)-
benzenesulfonyl chlorides 4 and 5. The analogues exhibited moderate to excellent activity
when tested against Leishmania donovani amastigotes in vitro. Two representative compounds,
7f and 8, were tested against the Khartoum strain of L. donovani in a hamster model using
chloralin (2) and Glucantime (one of the current therapeutics of choice in the treatment of
Leishmania) as standards, the results of which will be discussed herein.
In tr od u ction
utilization of localized current field-radio frequencies.7
The more traditional approach of generating synthetic
analogues of existing drugs has led to the investigation
of dinitroanilines as antiparasitic agents,8 two of which,
trifluralin (1)9-13 and chloralin (2),9 have been reported
to be effective against Leishmania. Trifluralin is a
commercial herbicide used in the United States since
the 1960s.14 Chloralin, the industrial precursor to
trifluralin, has been reported to be 100 times more
potent than trifluralin against Leishmania promastig-
otes.9 The same investigators reported that trifluralin’s
activity is due solely to the chloralin impurity present
in commercial trifluralin preparations and postulated
that the molecular mechanism for activity is the inhibi-
tion of microtubule formation.
Leishmaniasis is a parasitic infection transmitted to
humans by the female phlebotomus sandfly. This
disease is endemic to both the tropical and subtropical
regions of Africa, Asia, the Mediterranean, Southern
Europe, and both Central and South Americas. The
clinical manifestations of this disease vary widely and
are categorized by symptoms such as lesions on the face,
arms, legs (cutaneous, diffuse cutaneous, disabling), and
mucous membranes of the nose and mouth (mucocuta-
neous, mutilating). The parasite can also invade the
spleen, liver, bone marrow, lymph nodes, and skin
(visceral, kala azar, fatal). The severity of the disease
is determined by factors such as host immunity, parasite
virulence, and host or vector behavior. It has been
estimated that 12 million people are infected with
leishmaniasis and that 350 million people are at risk
in about 88 countries. There are approximately 2
million new cases of leishmaniasis per year, of which
only 600 000 are officially reported. Hospitalization is
necessary for treatment to occur.1
The current chemotherapeutic treatments of choice
for leishmaniasis are two pentavalent antimony com-
pounds: sodium stibogluconate (Pentostam) and me-
glumine antimoniate (Glucantime).2 They are rapidly
excreted from the kidneys with virtually no accumula-
tion in the body. However, they have serious side effects
associated with them including nausea, diarrhea, con-
vulsions,3 and even cardiotoxicity.4 Antimony-resistant
strains have also been reported.5 Secondary treatment
agents include pentamidine and amphotericin B, which
also have serious side effects associated with them.3
Because of the adverse side effects of these treatment
regimes, much attention has been focused on the
discovery and development of new and less toxic che-
motherapeutic agents.
Tubulin assembles to form microtubules, which play
critical roles in chromosome segregation, organelle
transport, and cell structure maintenance. It has
previously been suggested that the C-4 chloro moiety
of chloralin is displaced by one or more of the 25 cysteine
residues present in leishmanial tubulin to form a
tubulin-deschlorochloralin complex thereby preventing
microtubule assembly.9 Recently, it has been shown
that chloralin interferes with microtubule assembly in
vitro, while trifluralin does not.15 Similar effects on
mammalian tubulin have also been described with the
small aromatic electrophiles 1-fluoro-2,4-dinitroben-
zene16 and 2,4-dichlorobenzyl thiocyanate.17
This effort has produced many novel and interesting
treatments such as liquid nitrogen therapy6 and the
The presence of nitro moieties in a chemotherapeutic
agent, such as chloralin, presents the potential for
carcinogenicity.18 We have therefore embarked upon
the syntheses of chloralin analogues that have substi-
tuted an electron-withdrawing sulfonamido functional-
ity in lieu of the nitro moieties in hopes of discovering
a chemotherapeutic agent that retains chloralin’s activ-
* To whom correspondence should be addressed: Department of
Medicinal Chemistry, Division of Experimental Therapeutics, Walter
Reed Army Institute of Research, Washington, DC, 20307-5100. Tel:
301-295-7796. Fax: 301-295-7755. E-mail: CPT_Kevin_Pitzer@wrsmtp-
ccmail.army.mil.
10.1021/jm9804073 This article not subject to U.S. Copyright. Published 1998 by the American Chemical Society
Published on Web 11/04/1998

4886 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 24
Pitzer et al.
Sch em e 1. Reaction Sequence for Sulfonamide
Formation
analogues 7a -h were similarly synthesized from fluoro
sulfonyl chloride 5 in order to determine the steric and
electronic requirements at position 4. Bipyrrolidyl-
substituted sulfonamide 8 was specifically generated
after being detected as a minor side product in the
pyrrolidyl addition-displacement reaction.
Initial experiments utilized a weak base (potassium
carbonate or triethylamine) and were conducted at room
temperature. These reactions provided the insight that
the weak bases neither assisted nor hindered the
reaction sequence. It was also noted that the attacking
amine displaced the C-4 halogen if ample reaction time
existed. Therefore, subsequent reactions excluded the
use of either weak base, were conducted at 0 °C, and
were shortened to 5 min or less. Yields ranged from
moderate (51%) in the initial trials to excellent (91%)
in the latter trials.
ity without its corresponding potential for toxicity. This
manuscript reports the results of that endeavor.
Resu lts a n d Discu ssion
Syn t h et ic Discu ssion . Recent structure-activity
relationship analysis of chloralin has revealed that the
C-4 chloride moiety as well one o-nitro functionality are
necessary for activity.9 It is therefore hypothesized that
a bioisostere of the nitro moiety, the sulfonamido group,
should retain the necessary electronic features contrib-
uting to chloralin’s activity without the corresponding
toxicity (or potential carcinogenicity) inherent to the
nitro moiety. Thus, eight different amines were reacted
with chloro sulfonyl chloride 4 in the addition-displace-
ment reaction, depicted in Scheme 1, to give compounds
6a -h . The amines varied from simple ammonia to
medium sized cyclic amines such as pyrrolidine and
hexamethyleneimine. The corresponding C-4 fluoro
Biologica l Discu ssion . The 17 potential chemo-
therapeutics were evaluated in vitro against amastigote-
like Leishmania donovani parasites (cf. Table 1), and
two (7f, 8) were further evaluated against L. donovani
amastigotes in a hamster model (cf. Table 2). The in
vitro evaluations used chloralin and Pentostam as
standards, while the standards for the hamster model
were Glucantime and chloralin. The in vitro IC50 value
for chloralin was determined to be 1.3 ( 0.1 µM against
the L. donovani parasites, while Pentostam had an IC50
value of 329 ( 8 µM (based on antimony content). Any
synthesized analogue whose in vitro IC50 value exceeded
Ta ble 1. Sulfonamide Activity and Log P Values
a
IA, the compound’s IC50 value exceeded 450 µM.

Chloralin Analogues as Antileishmanial Agents
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 24 4887
Ta ble 2. In Vivo Test Results against Visceral L. donovani in
Hamsters
antimony), and is an order of magnitude higher than
the IC50 value obtained for chloralin (IC50 ) 1.3 ( 0.1
µM). Therefore, analogue 8 could be considered a lead
compound for further development, provided, of course,
that it is nontoxic and displays in vivo activity.
The steric and electronic requirements at position C-4
were also explored. It was originally believed that the
C-4 fluoro derivatives would exhibit greater activity
than the corresponding C-4 chloro derivatives because
the fluoro moiety would impart less steric hindrance at
the C-4 displacement site and would also impart greater
electronegativity on the entire molecule thereby increas-
ing antiparasitic activity. The biological data proved
otherwise: the C-4 chloro substituents exhibited lower
IC50 in vitro values and hence greater therapeutic
potency than the C-4 fluoro analogues.
Finally, dipyrrolidyl analogue 8 and fluoro hexa-
methyleneimine analogue 7f were evaluated in vivo.
Neither of these two compounds nor chloralin displayed
activity against visceral L. donovani parasite in the
hamster model. This could be attributed to the lability
of the C-4 substituents. It is possible that an undeter-
mined nucleophile displaced the C-4 moiety at the
injection site. Another possible explanation is this class
of compounds simply has poor transportation in mam-
malian cells. However, the excellent in vitro activity
displayed by analogue 8 cannot be readily dismissed.
This analogue represents an entirely new structural
class of antileishmanial agents that should be expanded
upon and evaluated. Compound 8 might even signifi-
cantly suppress the L. donovani parasite if administered
by another route such as intravenously or by gavage.
Also, analogue 8 might be active against cutaneous
Leishmania when administered in ointment form since
trifluralin displays activity in that fashion.21
Finally, the proposed mechanism of action for this
class of compounds might not be microtubule inhibition.
Eight analogues (6a -g, 7e, 8) were tested against
purified tubulin at 50 µM to determine if microtubule
assembly was inhibited. None were found inhibitory
(chloralin’s IC50 ) 22 µM);15 therefore the observed in
vitro activity is ascribed to an as of yet unknown
mechanism of action.
dosage level
(mg/kg)
% suppression
of parasitemia
compound
glucantime
52
208
52
208
13
52
208
13
27
73
21
32
11
13
19
16
29
30
chloralin
7f
8
52
208
450 µM was designated inactive. The data indicate that,
as a group, the C-4 chloro analogues had greater activity
than the corresponding C-4 fluoro compounds, with only
one exception, analogue 7g. Both sets of amino (6a , 7a )
and methylamino (6b, 7b) analogues displayed inactiv-
ity. The two diethylenediamine compounds (6c, 7c)
were also inactive. Analogues which incorporated the
sulfonamido nitrogen into a five (6d , 7d ), six (6e, 7e),
or seven (6f, 7f) membered heterocyclic ring had better
activity. Of these six compounds, analogues 6f and 7f
demonstrated the best inhibition (6f, IC50 ) 56 ( 9 µM;
7f, IC50 ) 108 ( 9 µM).
The N-methylpiperazyl (6g, 7g) and 2-pyridylpipera-
zyl (6h , 7h ) derivatives demonstrated moderate to good
activity. The C-4 fluoro N-methylpiperazyl analogue
(7g) had activity in the 200 µM range, while the C-4
chloro 2-pyridylpiperazyl analogue (6h ) displayed the
lowest IC50 value (44 ( 5 µM) of the halogen C-4-
substituted analogues. Dipyrrolidine analogue (8) ex-
hibited the most potency against the L. donovani
parasites (IC50 ) 23 ( 12 µM).
The partition coefficient (log P) for each analogue,
including chloralin,19 was calculated and compared with
each analogue’s IC50 value in hopes of finding good
correlation between activity and log P values. Unfor-
tunately, no correlation could be extrapolated between
these two properties.
The dipyrrolidyl (8) and the 4-fluoro hexamethylene-
imine (7f) analogues were evaluated against the Khar-
toum strain of L. donovani in a hamster model,20 using
chloralin and Glucantime as standards. The animals,
six per group, were injected intracardially with 1.0 ×
107 amastigotes obtained from spleens of donor ham-
sters. Analogues 7f and 8, as well as the standards,
were introduced into the hamsters by intramuscular
injection on day 3 after infection and screened ‘blind’
at the indicated dosages (Table 2). The therapeutics
were administered for 4 consecutive days, and on day 7
after infection, the animals were sacrificed and the total
parasite number per liver was determined. Neither
chloralin nor either analogue suppressed the L. dono-
vani parasites in sufficient quantities at the indicated
dosage levels to be considered active in this evaluation.
Exp er im en ta l Section
P a r a site Dr u g Su scep tibility Assa y. 1. Gen er a l: The
Leishmania donovani parasites (WHO designation: MHOM/
SD/62/1S-CL2D) were maintained as axenic amastigote-like
forms by serial passage at 37 °C in a humid atmosphere
containing 5% CO2 using a slightly modified version of a known
medium.22
2. Dr u g Assa y: L. donovani amastigote-like forms were
seeded at 106 cells/mL in 96-well flat-bottom plates (Costar)
in the amastigote medium described earlier in the presence
or absence of drug. The maximum concentration of DMSO in
each well was 1.25% (v/v), which had no effect on the growth
of the parasites. Plates were incubated at 37 °C in a humid
5% CO2 atmosphere for 72 h; then 12 µL of the aqueous Cell
Titer solution (Promega) was added to each well according to
the instructions of the manufacturer. The Cell Titer solution
contains a compound that is reduced by cellular dehydroge-
nases to give a product that is measured spectrophotometri-
cally. Plates were returned to the 37 °C incubator for a further
8-12 h, and then the absorbance of each well was measured
at 490 nm using a Dynatech MR 5000 plate reader. IC50
values for each of the drugs were determined with the aid of
the program TableCurve 2D, version 3 (J andel Scientific). The
Con clu sion s
Nine analogues displayed in vitro activity against the
L. donovani parasite (IC50 < 450 µM). Their efficacies
varied widely with the most promising candidate,
analogue 8, exhibiting an IC50 value of 23 ( 12 µM. This
result is an order of magnitude lower than that of the
current therapeutic, Pentostam (IC50 ) 329 ( 8 µM

4888 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 24
Pitzer et al.
log dose-response equation y ) a + b/(1 + (x/c)d) was used to
calculate IC50 values, where x is drug concentration, y is
absorbance at 490 nm, a is lower asymptote, b is the difference
between the upper and lower asymptote, c is IC50, and d is
slope.
6H, J ) 7.1 Hz); MS m/e 323 (M+ - 19), 270, 227, 163. Anal.
(HCl salt) (C13H19ClF4N2O2S) C, H, Cl, N, S.
P yr r olid yl-2-ch lor o-5-(tr iflu or om eth yl)ben zen esu lfon -
a m id e (6d ): yield 90%; Rf ) 0.19 (9:1 hexane-EtOAc); mp
1
89-91 °C; IR (smear) 3103, 2983, 2883, 1604 cm-1; H NMR
Gen er a l Ch em ica l P r oced u r es. 2-Fluoro-5-(trifluoro-
methyl)benzenesulfonyl chloride and 2-chloro-5-(trifluorometh-
yl)benzenesulfonyl chloride were obtained under contract from
Ash-Stevens Inc., Detroit, MI. Melting points were determined
using a Thomas-Hoover capillary apparatus and are reported
uncorrected. 1H NMR spectra were recorded on a Bruker AC-
300 spectrometer at 300 K using tetramethylsilane as an
internal standard and are reported in parts per million. All
infared spectra were obtained using a Nicolet 20SXB FTIR
spectrometer and were recorded in wavenumbers (cm-1). Mass
spectra were obtained using a Hewlett-Packard 5970 series
mass selective detector. Microanalyses were conducted by
Atlantic Microlabs (Norcross, GA) and were within (0.40%
for elements indicated. Silica gel column chromatography was
carried out using Merck grade 9385 (230-400 mesh, 60 Å)
silica gel. Thin-layer chromatography was performed on
Analtech Uniplates HPTLC-HLF normal phase silica gel plates
with organic binder and indicated solvents.
(CDCl3) δ 8.36 (s, 1H), 7.73 (d, 1H, J ) 8.4 Hz), 7.65 (d, 1H, J
) 8.4 Hz), 3.44 (m, 4H), 1.93 (m, 4H); MS m/e 312 (M+ - 1),
243, 179, 70. Anal. (C11H11ClF3NO2S) C, H, Cl, N, S.
P yr r olid yl-2-flu or o-5-(tr iflu or om eth yl)ben zen esu lfon -
a m id e (7d ): yield 71%; Rf ) 0.20 (9:1 hexane-EtOAc); mp
71.5-72.5 °C; IR (smear) 3315, 3053, 2987, 2882, 1597 cm-1
;
1H NMR (CDCl3) δ 8.21 (dd, 1H, J ) 6.0, 2.0 Hz), 7.83 (m,
1H), 7.34 (t, 1H, J ) 9.0 Hz), 3.40 (m, 4H), 1.89 (m, 4H); MS
m/e 296 (M+ - 1), 278, 227, 163. Anal. (C11H11F4NO2S) C, H,
N, S.
P ip er a d yl-2-ch lor o-5-(tr iflu or om eth yl)ben zen esu lfon -
a m id e (6e): yield 64%; Rf ) 0.43 (9:1 hexane-EtOAc); mp
86.5-88 °C; IR (smear) 3100, 2943, 2859, 1606 cm-1; 1H NMR
(CDCl3) δ 8.32 (s, 1H), 7.72 (dd, 1H, J ) 8.3, 1.8 Hz), 7.65 (d,
1H, J ) 8.3 Hz), 3.30 (m, 4H), 1.61 (m, 6H); MS m/e 326 (M+
- 1), 308, 286, 243, 179. Anal. (C12H13ClF3NO2S) C, H, Cl,
N, S.
P ip er a d yl-2-flu or o-5-(tr iflu or om eth yl)ben zen esu lfon -
Gen er a l Meth od for Su lfon a m id e F or m a tion (6a -h ,
7a -h , 8). 2-Fluoro-5-(trifluoromethyl)benzenesulfonyl chlo-
ride or 2-chloro-5-(trifluoromethyl)benzenesulfonyl chloride
was dissolved in methylene chloride and brought to 0 °C. The
corresponding amine was added neat. After approximately
5-15 min (reaction times varied) the reactions were diluted
with water, transferred to a separatory funnel, and washed
with hydrochloric acid (1 M), aqueous sodium carbonate (10%),
and water. The combined organic layers were concentrated
in vacuo and subjected to flash chromatography (using indi-
cated TLC solvents) to yield crystalline compounds (except
where no melting point is given).
2-Ch lor o-5-(tr iflu or om eth yl)ben zen esu lfon a m id e (6a ):
yield 92%; Rf ) 0.51 (9:1 CHCl3-(CH3)2CO); mp 158.5-160
°C; IR (smear) 3396, 3284, 1606, 1575 cm-1; 1H NMR (acetone-
d6) δ 8.31 (s, 1H), 7.99 (dd, 1H, J ) 8.4, 1.8 Hz), 7.90 (d, 1H,
J ) 8.4 Hz), 7.05 (s, N-H), 2.79 (s, N-H); MS m/e 259 (M+),
243, 196, 179. Anal. (C7H5ClF3NO2S) C, H, N, Cl, S.
2-F lu or o-5-(tr iflu or om eth yl)ben zen esu lfon a m id e (7a ):
yield 97%; Rf ) 0.37 (9:1 CHCl3-(CH3)2CO); mp 125-127 °C;
IR (KBr) 3384, 3280, 3131, 3085, 1617 cm-1; 1H NMR (acetone-
d6) δ 8.15 (dd, 1H, J ) 6.3, 1.2 Hz), 8.08 (m, 1H), 7.63 (t, 1H,
J ) 9.1 Hz), 7.11 (s, N-H), 2.80 (s, N-H); MS m/e 243 (M+),
227, 179, 163. Anal. (C7H5F4NO2S) C, H, N, S.
a m id e (7e): yield 95%; Rf ) 0.15 (19:1 hexane-EtOAc); mp
84.5-85.5 °C; IR (smear) 3081, 2949, 2866, 1613, 1501 cm-1
;
1H NMR (CDCl3) δ 8.14 (dd, 1H, J ) 5.9, 1.8 Hz), 7.84 (m,
1H), 7.36 (t, 1H, J ) 9.0 Hz), 3.21 (m, 4H), 1.66 (m, 4H), 1.53
(m, 2H); MS m/e 310 (M+ - 1), 270, 227, 179, 163. Anal. (C12
-
H
13F4NO2S) C, H, N, S.
Hexam eth ylen eim in o-2-ch lor o-5-(tr iflu or om eth yl)ben -
zen esu lfon a m id e (6f): yield 86%; Rf ) 0.31 (9:1 hexane-
EtOAc); mp 53-55 °C; IR (smear) 3100, 2933, 2860, 1605 cm-1
;
1H NMR (CDCl3) δ 8.35 (s, 1H), 7.72 (d, 1H, J ) 8.3 Hz), 7.65
(d, 1H, J ) 8.3 Hz), 3.40 (t, 4H, J ) 5.6 Hz), 1.67 (m, 8H); MS
m/e 341 (M+), 322, 286, 243, 179. Anal. (C13H15ClF3NO2S) C,
H, Cl, N, S.
Hexa m eth ylen eim in o-2-flu or o-5-(tr iflu or om eth yl)ben -
zen esu lfon a m id e (7f): yield 73%; Rf ) 0.30 (7:3 hexane-
CHCl3); mp 75-76 °C; IR (smear) 3077, 2931, 2858, 1612, 1601
1
cm-1; H NMR (CDCl3) δ 8.19 (dd, 1H, J ) 6.1, 1.7 Hz), 7.81
(m, 1H), 7.32 (t, 1H, J ) 9.0 Hz), 3.38 (m, 4H), 1.65 (m, 8H);
MS m/e 325 (M+), 306, 270, 227, 163. Anal. (C13H15F4NO2S)
C, H, N, S.
N-Met h ylp ip er a zyl-2-ch lor o-5-(t r iflu or om et h yl)b en -
zen esu lfon a m id e (6g): yield 87%; Rf ) 0.33 (19:1 EtOAc-
MeOH); mp 64-66 °C; IR (neat) 3100, 3079, 2943, 2852, 2800,
1
1606 cm-1; H NMR (CDCl3) δ 8.31 (s, 1H), 7.73 (dd, 1H, J )
N-Meth yl-2-ch lor o-5-(tr iflu or om eth yl)ben zen esu lfon -
a m id e (6b): yield 82%; Rf ) 0.27 (4:1 hexane-EtOAc); mp
97.5-99 °C; IR (smear) 3319, 3106, 1607, 1575 cm-1; 1H NMR
(CDCl3) δ 8.37 (s, 1H), 7.78 (d, 1H, J ) 8.3 Hz), 7.68 (d, 1H, J
) 8.3 Hz), 5.04 (s, N-H), 2.69 (d, 3H, J ) 5.3 Hz); MS m/e
273 (M+), 254, 243, 209, 179. Anal. (C8H7ClF3NO2S) C, H,
N, Cl, S.
8.3, 1.9 Hz), 7.66 (d, 1H, J ) 8.3 Hz), 3.36 (t, 2H, J ) 5.0 Hz),
2.46 (t, 2H, J ) 5.0 Hz), 2.30 (s, 3H); MS m/e 342 (M+), 323,
179, 144. Anal. (C12H14ClF3N2O2S) C, H, Cl, N, S.
N-m et h ylp ip er a zyl-2-flu or o-5-(t r iflu or om et h yl)b en -
zen esu lfon a m id e (7g): yield 59%; Rf ) 0.34 (9:1 EtOAc-
hexane); mp 90.5-92 °C; IR (smear) 2943, 2855, 1612, 1499
1
cm-1; H NMR (CDCl3) δ 8.12 (dd, 1H, J ) 4.1, 1.9 Hz), 7.84
N-Meth yl-2-flu or o-5-(tr iflu or om eth yl)ben zen esu lfon -
a m id e (7b): yield 75%; Rf ) 0.28 (4:1 hexane-EtOAc); mp
(m, 1H), 7.35 (t, 1H, J ) 9.0 Hz), 3.26 (m, 2H), 2.49 (m, 2H),
2.30 (s, 3H); MS m/e 326 (M+), 307, 227, 163. Anal. (C12H14
-
88-89 °C; IR (KBr) 3276, 3119, 1614, 1495 cm-1 1H NMR
;
F4N2O2S) C, H, N, S.
(CDCl3) δ 8.20 (d, 1H, J ) 5.9 Hz), 7.86 (m, 1H), 7.63 (t, 1H,
J ) 9.0 Hz), 4.75 (s, N-H), 2.76 (d, 3H, J ) 5.2 Hz); MS m/e
257 (M+), 248, 227, 163. Anal. (C8H7F4NO2S) C, H, N, S.
N,N-Dieth ylen ed ia m in o-2-ch lor o-5-(tr iflu or om eth yl)-
ben zen esu lfon a m id e (6c): yield 94%; Rf ) 0.38 (MeOH, HCl
salt); mp (HCl) 147-149 °C; IR (neat) 3309, 3080, 2972, 2821,
N-(2-P yr id yl)p ip er a d yl-2-ch lor o-5-(t r iflu or om et h yl)-
ben zen esu lfon a m id e (6h ): yield 91%; Rf ) 0.28 (4:1 hexane-
EtOAc); mp 50.5-52.5 °C; IR (smear) 3099, 3006, 2919, 2858,
1
1604 cm-1; H NMR (CDCl3) δ 8.34 (s, 1H), 8.18 (dd, 1H, J )
4.8, 3.6 Hz), 7.74 (dd, 1H, J ) 8.3, 1.6 Hz), 7.66 (d, 1H, J )
8.3 Hz), 7.49 (td, 1H, J ) 8.7, 1.8 Hz), 6.65 (m, 2H), 3.64 (m,
1
1605 cm-1; H NMR (CDCl3) δ 8.37 (s, 1H), 7.75 (dd, 1H, J )
2H), 3.44 (m, 2H); MS m/e 405 (M+), 207, 179, 162. Anal. (C16
-
8.3, 1.5 Hz), 7.66 (d, 1H, J ) 8.3 Hz), 2.96 (t, 2H, J ) 5.6 Hz),
2.52 (t, 2H, J ) 5.6 Hz), 2.44 (q, 4H, J ) 7.1 Hz), 0.96 (t, 6H,
J ) 7.1 Hz); MS m/e 357 (M+ - 1), 341, 286, 243, 179. Anal.
(HCl salt) (C13H19Cl2F4N2O2S) C, H, Cl, N, S.
H
15ClF3N3O2S) C, H, Cl, N, S.
N-(2-P yr id yl)p ip er a d yl-2-flu or o-5-(t r iflu or om et h yl)-
ben zen esu lfon a m id e (7h ): yield 66%; Rf ) 0.30 (4:1 hexane-
EtOAc); mp 125.5-126.1 °C; IR (smear) 3051, 3008, 2984,
N,N-Dieth ylen ed ia m in o-2-flu or o-5-(tr iflu or om eth yl)-
ben zen esu lfon a m id e (7c): yield 36%; Rf ) 0.38 (MeOH, HCl
salt); mp (HCl) 140-141 °C; IR (smear) 3300, 3079, 2974, 2823,
1612, 1499 cm-1; 1H NMR (CDCl3) δ 8.21 (dd, 1H, J ) 6.3, 1.7
Hz), 7.84 (m, 1H), 7.35 (t, 1H, J ) 8.9 Hz), 3.03 (t, 2H, J ) 5.9
Hz), 2.53 (t, 2H, J ) 5.9 Hz), 2.43 (q, 4H, J ) 7.1 Hz), 0.96 (t,
2823, 1610 cm-1 1H NMR (CDCl3) δ 8.16 (m, 1H), 7.85 (m,
;
1H), 7.49 (td, 1H, J ) 7.4, 1.8 Hz), 7.35 (t, 1H, J ) 9.0 Hz),
6.65 (m, 2H), 3.67 (t, 2H, J ) 4.8 Hz), 3.35 (t, 2H, J ) 4.8 Hz);
MS m/e 389 (M+), 370, 227, 162. Anal. (C16H15F4N3O2S) C,
H, N, S.

Chloralin Analogues as Antileishmanial Agents
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P yr r olid yl-2-p yr r olid yl-5-(t r iflu or om et h yl)b en zen e-
su lfon a m id e (8): yield 90%; Rf ) 0.38 (CHCl3); mp 89-91
°C; IR (smear) 2973, 2876, 1614, 1547 cm-1; 1H NMR (CDCl3)
δ 7.77 (d, 1H, J ) 1.2 Hz), 7.49 (dd, 1H, J ) 8.9, 2.0 Hz), 6.95
(d, 1H, J ) 8.9 Hz), 3.61 (t, 4H, J ) 6.6 Hz), 3.42 (t, 4H, J )
6.6 Hz), 1.98 (m, 8H); MS m/e 348 (M+), 329, 278, 248, 213.
Anal. (C15H19F3N2O2S) C, H, N, S.
Ack n ow led gm en t. The authors would like to thank
Dr. William Hanson of the University of Georgia for
conducting the in vivo testing. We also thank Dr. Dennis
Dwyer of the NIH for the generous gift of the L.
donovani parasites. We would also like to thank Ash-
Stevens Inc. for synthesizing starting materials 4 and
5. Finally, we thank Dr. Heather Callahan for her
assistance. This work was funded by the United States
Army Medical Research and Material Command.
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