Novel structures derived from 2-[[(2-pyridyl)methyl]thio]-1H-benzimidazole as anti-Helicobacter pylori agents, part 2

Article abstract of DOI:10.1021/jm020868v

A parallel chemistry expansion of the 2-({3-[(1H-benzimidazol-2-ylsulfanyl)methyl]-phenyl}-sulfanyl)-1-ethanol scaffold (2) successfully provided a set of 2-({3-[(1H-benzimidazol-2-ylsulfanyl)methyl]-2-methylphenyl}sulfanyl)ethyl carbamates with the gener

Full text of DOI:10.1021/jm020868v

4300
J . Med. Chem. 2002, 45, 4300-4309
Novel Str u ctu r es Der ived fr om 2-[[(2-P yr id yl)m eth yl]th io]-1H-ben zim id a zole a s
An ti-Helicoba cter pylor i Agen ts, P a r t 2
Daniel Carcanague,† Youe-Kong Shue,† Mark A. Wuonola,† Maria Uria-Nickelsen,‡ Camil J oubran,†
J oseph K. Abedi,† J eanette J ones,‡ and Thomas C. Ku¨hler*,†
Department of Chemistry and Department of Microbiology, AstraZeneca R&D Boston, 35 Gatehouse Drive,
Waltham, Massachusetts 02451
Received March 8, 2002
A parallel chemistry expansion of the 2-({3-[(1H-benzimidazol-2-ylsulfanyl)methyl]-phenyl}-
sulfanyl)-1-ethanol scaffold (2) successfully provided a set of 2-({3-[(1H-benzimidazol-2-
ylsulfanyl)methyl]-2-methylphenyl}sulfanyl)ethyl carbamates with the generic structure 12,
which displayed potent and selective activities against the gastric pathogen Helicobacter pylori.
A prototype carbamate 12a was studied further and found to meet several significant in vitro
microbiological criteria required for a novel anti-H. pylori agent. The compound displayed low
minimal inhibition concentration (MIC) values against a panel of 27 different clinically relevant
H. pylori strains (MIC90 ) 0.25 µg/mL), including strains resistant to either metronidazole or
clarithromycin or both. Additionally, 12a was almost inactive against a wide range of commensal
or pathogenic microorganisms comprising panels of 25 aerobic bacterial strains including two
strains of methicillin resistant Staphylococcus aureus (MIC90 ) >64 µg/mL) and 18 anaerobic
bacterial strains (MIC90 ) >64 µg/mL). The measured rate of resistance development against
12a was found to be less than 10-9, a clinically acceptable level, and pharmacokinetic studies
revealed in vivo exposure levels comparable with those established for antimicrobials currently
used in H. pylori triple regimen.
In tr od u ction
other bacteria and that lack the common gastrointes-
tinal side effects often associated with antibacterials.
In an accompanying paper,8 we report finding a novel
chemical template, 2-[[(phenyl)methyl]thio]-1H-benz-
imidazole 1 (Chart 1), with antimicrobial activity selec-
tive for H. pylori. The substitution of hydrogen with a
sulfur in the 3-position of the phenyl ring of this
template proved to be beneficial in improving potency.
The tolerance of a larger chemical bulk such as iso-Bu,
-(CH2CH2O)3CH3, -(CH2CH2O)5CH3, and -CH2CH2-4-
morpholinyl attached to the sulfur suggested that there
was potential for further variation in this position.
We explored this possibility and opted for a parallel
chemistry approach to quickly map out the scope and
limitations. Three out of the four above bulky side
chains had the -CH2CH2Het (Het ) O or N) structural
motif implicating the ethyl alcohol 2 as a potential
starting point for the parallel chemistry effort. The
synthesis of this key compound (8), with a preferred
methyl group8 in the 2-position of the phenyl ring in
place, is shown in Scheme 1. This route immediately
suggested an additional two compounds that could lend
themselves to a parallel chemistry effort, namely, the
acid 9 and the amine 11, both of which become readily
accessible when preparing the alcohol 8.
The microaerophilic bacterium Helicobacter pylori has
been recognized as the major cause of gastritis, a
significant determinant in peptic and duodenal ulcer
disease,1-3 and as an important factor in the develop-
ment of gastric cancer.4 Since 1983 when H. pylori was
first isolated, it has consistently been recovered from
the gastric and duodenal mucosae of patients suffering
from these medical conditions. The eradication of the
bacterium in infected patients has resulted in good
healing rates for both active chronic gastritis and
duodenal ulcer disease.5
Although H. pylori is sensitive in vitro to many
antibacterials,6 single therapy regimens have not been
very effective in clinical settings. Rather, combination
therapies employing bismuth salts or omeprazole or
other proton pump inhibitors and two or three antibiot-
ics such as metronidazole, amoxicillin, clarithromycin,
or tetracycline have emerged as preferred treatments.7
While the efficacy of some of these combinations is
clinically acceptable, their effectiveness can fall off over
time because of the selection of antibiotic resistant
strains. Moreover, disrupting the natural population of
commensal microorganisms in the gastrointestinal tract
sometimes leads to undesired side effects such as
diarrhea.
The synthesis screen cycle identified the carbamate
12a (R ) Ph in 12) as a potent compound with many
desirable properties. Hence, some additional phenyl
carbamate analogues 17 were also prepared in which
the right-hand benzimidazole moiety of 12 was substi-
tuted with various other heterocycles.
Hence, there are unmet medical needs for novel,
efficacious, and selective eradication therapies that
minimize resistance problems in both H. pylori and also
* To whom correspondence should be addressed. Tel: +46 18
183630. Fax: +46 18 548566. E-mail thomas.kuhler@mpa.se.
† Department of Chemistry, AstraZeneca R&D Boston.
In this paper, we report on the parallel synthesis and
the microbiological profiling of several carbamates (12)
obtained from the alcohol 8, some amides (13) prepared
‡ Department of Microbiology, AstraZeneca R&D Boston.
10.1021/jm020868v CCC: $22.00 © 2002 American Chemical Society
Published on Web 08/09/2002

Novel Anti-Helicobacter pylori Agents
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19 4301
Sch em e 1. Synthetic Routes toward Target Compounds 12-17a
a
Reagents: (a) (i) NaNO2, HCl, H2O, 0 °C; (ii) HSCH2CO2CH3, CH3OH, 60 °C. (b) BH3‚THF, THF, 0 °C. (c) TBDMSCl, imidazole,
DMF, 20 °C. (d) LAH, THF, 0 °C. (e) Isocyanate, DMAP (catalytic), THF, 50 °C. (f) Bu4NF, THF, H2O, 20 °C. (g) SOCl2, THF, 0-20 °C.
(h) Heterocycle-SH, K2CO3, DMF, 20 °C. (i) 2-Mercaptobenzimidazole, NaOH, H2O, CH3OH, 0-20 °C. (j) LiOH, H2O, CH3OH, 20 °C. (k)
Amine, HBTU, DMF, 20 °C. (l) PPh3, NaN3, CBr4, 0-20 °C. (m) Acid, DIPEA, HBTU, DMF, 20 °C. (n) Sulfonyl chloride, Et3N, 1:1 THF:
DMF, 20 °C. (o) PhNCO, DMF, 20 °C.
Ch a r t 1. Structures of a Novel Chemical Template,
from the acid 9, and a number of amides (14) and
2-[[(Phenyl)methyl]thio]-1H-benzimidazole (1) with
sulfonamides (15) synthesized from the amine 11. The
Antimicrobial Activity Selective for the Bacterium H.
pylori and the Alcohol 2 that Was Chosen as a Starting
Point for a Parallel Chemistry Effort
synthesis and microbiological evaluation of some ad-
ditional heterocyclic phenyl carbamates 17 and one
follow up phenyl urea compound 16 are also reported.
A few select target compounds were studied further and
assessed with respect to their pharmacokinetic proper-
ties.
Ch em istr y
Syn th eses. The syntheses of the target compounds
as outlined in Scheme 1 were typically carried out in
parallel arrays on a 0.25-0.5 mmol scale. Crude prod-
ucts after aqueous workup were analyzed by high-
performance liquid chromatography (HPLC) and mass
spectrometry (MS) and if judged to be of sufficient purity
(generally >90%) submitted for biological testing. The
objective was to quickly scan the readily accessible
structure-activity relationships (SAR) to discover modi-
fications that would justify further focus.
Hence, the alcohol 8 was allowed to react with various
isocyanates (Chart 2) to yield the corresponding car-
bamates by the standard procedure given for compound
12a . Similarly, amides were prepared by diverting the
ester 7 to the acid 9 and coupling it with the appropriate
amines (Chart 3) employing HBTU as coupling reagent
according to the conditions given for target compound
13a . Reversed amides were prepared by converting the
alcohol 8 to the azide 10, which after reduction fur-
nished amine 11. This amine was then coupled with
carboxylic acids of choice (Chart 4) as exemplified for
compound 14. The sulfonamides were readily formed by
reacting amine 11 with a set of sulfonyl chlorides (Chart
5) as illustrated for compound 15. One follow up urea
compound 16 was also prepared by reacting amine 11
with phenyl isocyanate.
Compound 5 became an attractive starting point in
the pursuit of heterocyclic derivatives 17. Protection of
the benzyl alcohol with TBDMSCl furnished 18, which

4302 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19
Ch a r t 2. Isocyanates Used to Prepare the Carbamates 12
Carcanague et al.
Ch a r t 3. Amines Used to Prepare the Amides 13
was reduced to the alcohol 19, which in turn was
trapped by phenyl isocyanate to yield the carbamate 20.
Removal of the silyl group with fluoride ion gave the
benzyl alcohol 21, which was activated with SOCl2 to
yield the benzyl chloride 22. Reaction of 22 with the
heterocyclic thiolates shown in Chart 6 according to the
procedure given for 17a afforded the desired target
compounds.
Micr obiology
Ba cter ia l Str a in s. A panel of 27 H. pylori strains
was selected based on differences in pathophysiologic
history, variations in antibiotic resistance, and diversity
in geographical origin, cf. Table 1. Cultures from single
colonies containing no more that 5% coccoids were
stored at -70 °C in Brucella broth (BBL, Becton
Dickinson and Company, Cockeysville, MD) supple-

Novel Anti-Helicobacter pylori Agents
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19 4303
Ch a r t 4. Carboxylic Acids Used to Prepare the Reversed Amides 14
Ch a r t 5. Sulfonyl Chlorides Used to Prepare the Sulfonamides 15
Ch a r t 6. Heterocyclic Thiolates Used to Prepare Target Compounds 17
mented with 30% glycerol. Frozen cells were grown on
Trypticase Soy Agar (Beckton Dickinson and Company)
supplemented with 5% sheep blood (BAP, Remel, Len-
exa, KS) at 37 °C under microaerophilic conditions (5%
O2, 10% CO2, and 85% N2) in a Cellstar Trigas incubator
(Queue Systems, Asheville, NC) and transferred to new
medium twice prior to testing.
Similarly, panels of 25 aerobic bacterial strains,
including two strains of methicillin resistant Staphylo-
coccus aureus and 18 anaerobic bacterial strains, rep-
resenting rather wide ranges of commensal and patho-
genic microorganisms, were selected as detailed in Table
2. Aerobic single colonies were grown on Mueller Hinton
II Agar (MH, Beckton Dickinson and Company) at 37
°C under aerobic conditions and stored at 4 °C before
testing. Anaerobic cultures from single colonies were
stored at -70 °C in BBL (Becton Dickinson and Com-
pany) supplemented with 30% glycerol. Frozen cells
were grown on BAP at 37 °C under anaerobic conditions
in an anaerobic/environmental chamber (Sheldon Manu-
facturing, Inc., Cornelius, OR) and transferred to new
medium twice prior to testing.
An tim icr obia ls. Amoxicillin and metronidazole were
purchased from Sigma Chemical Company (St. Louis,
MO). Clarithromycin was obtained from Abbott Labo-
ratories (Chicago, IL). Compounds were dissolved in
dimethyl sulfoxide (DMSO) at 10 mg/mL and added to
the appropriate media to obtain the indicated concen-
trations in each experiment.
Deter m in a tion of H. pylor i Min im a l In h ibitor y
Con cen tr a tion s (MICs) in th e Micr od ilu tion Assa y.
Strains ARHp80, 81, 115, and 206, cf. Table 1, were used
in these experiments. Two-fold serial dilutions were
prepared in 24 well plates containing a total volume of

4304 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19
Carcanague et al.
Ta ble 1. List of Geographic Origin, Pathophysiologic History,
and Resistance Profile of H. pylori Strains Used in the
Microbiology Studies
lowest concentration of antimicrobials resulting in
complete inhibition of growth.
Det er m in a t ion of MICs in t h e Aga r Dilu t ion
Assa y. MICs were determined against a panel of 27
clinical H. pylori isolates, 13 aerobic and 16 anaerobic
bacterial species on BAP for H. pylori, Brucella Agar
supplemented with hemin, vitamin K, and 5% laked
sheep blood for anaerobes, and Mueller Hinton II Agar
for aerobes following NCCLS antimicrobial susceptibil-
ity testing methods.9,10
Deter m in a tion of H. pylor i Min im a l Ba cter icid a l
Con cen tr a tion s (MBCs). Strain ARHp206, cf. Table
1, was used in these experiments. Aliquots of culture
were taken from the wells in the microdilution assay
plates in which no growth had been detected and used
to seed BAP. MBCs were determined by visual inspec-
tion of the plates and identifying the concentration at
which maximum growth inhibition had occurred.
Det er m in a t ion of H . p ylor i Killin g Kin et ics.
Strain ARHp206, cf. Table 1, was used in these experi-
ments. The rates of bacterial killing of compounds at 1
µg/mL against log phase cultures containing 106 cells/
mL were determined over 24 h. Cultures were placed
in a shaking 24 well plate at 37 °C under microaero-
philic conditions, and viable counts were quantitatively
determined after incubation for 0, 2, 4, 6, and 24 h,
respectively.
strain
(ARHp no.)
sourcea
resistance toward
metronidazole
25
32
37
39
46
54
Australia, human
Australia, human
Sweden
Sweden, clinical isolate
U.S.A., duodenal ulcer
U.S.A., duodenal ulcer
metronidazole
metronidazole,
clarithromycin
clarithromycin
55b
56
U.S.A., duodenal ulcer
Argentina, nonulcer dyspepsia
65
78
Argentina, nonulcer dyspepsia clarithromycin
Sweden, mouse
Sweden, mouse
U.S.A., mouse
U.S.A., duodenitis
Sweden, screen strain
Sweden, gastritis
Bangladesh, gastritis
U.K., gastritis
U.K., gastritis
U.K., gastritis
U.S.A., human
U.S.A., human
U.S.A., human
U.S.A., human
Australia, mouse
Sweden
metronidazole
metronidazole
80b
81b
106
115c
116
124
128
130
133
136
137
143
147
206b,d
209
211
212
metronidazole
metronidazole
U.S.A., pig
U.S.A., pig
a
Deter m in a tion of H. pylor i Resista n ce Ra tes.
Resistance rates were determined after 7 days of
incubation in solid medium containing 10 times the MIC
of the test compound. Cultures were then resuspended
in BBL (OD600 of 1, 109 cells/mL), serially diluted, and
spread on plates with and without the compound.
Resistance rates were expressed as the ratio between
the number of viable counts on plates with compound
and the number of viable counts on plates without
compound.
The strains are part of our culture collection and come from
various clinical sources representing differences in pathopysiologic
history, variations in antibiotic resistance, and diversity in
b
geographical origin. Strains used in the microdilution assay.
c ARHp115 corresponds to strain ATCC 43504 in the accompany-
d
ing paper, ref 8. Strain used for determining minimum bacteri-
cidal concentrations and for studying killing kinetics.
Ta ble 2. List of Aerobic and Anaerobic Bacteria Used in the
Microbiology Studiesa
aerobes
anaerobes
Lactobacillus sp.
Aeromonas sobria
Pseudomonas aeruginosab
Enterobacter cloacaec
Escherichia colic
Prevotella melaninogenica
Prevotella bivia
Bacteroides ureolyticus
Bacteroides thetaiiotaomicron
Bacteroides fragilisc
Bacteroides ovatus
Bacteroides vulgatus
Bacteroides caccae
Bilophila wasdworthia
Fusobacterium mortiferumc
Clostridium difficile
Clostridium ramosum
Clostridium perfringes
Peptostreptococcus micros
Peptostreptococcus anaerobius
P h a r m a cok in etic Stu d ies
Compounds were given orally by gavage needle at 30
mg/kg in a vehicle of 85:15 (0.5% aqueous hydroxypro-
pylmethylcellulose:PEG-400) to C57BL/6NTac female
mice (6 weeks, 20 g) obtained from Taconic Inc., Ger-
mantown, NY. Three mice per time point were bled by
cardiac puncture at 15, 30, 60, 120, and 240 min,
respectively, after dosing. Blood samples were collected
in heparin tubes and centrifuged to yield plasma
samples. Aliquots of plasma (50 µL) were diluted with
MeCN (150 µL) and centrifuged to remove proteins. The
supernatants (20 µL) were analyzed by LC-MS, cf.
Experimental Section below, in single ion recording
mode to determine plasma concentrations of parent
compounds against recorded calibration curves. Lower
limits of quantitation were 10-50 ng/mL. LC was run
on Luna C8(2) columns (3 µm, 2 mm × 30 mm) obtained
from Phenomenex, Torrance, CA, using 0.05% aqueous
HCOOH/MeCN as eluent at a flow rate of 1 mL/min
with a gradient from 5 to 95% MeCN in 4 min followed
by another 1 min at 95% MeCN.
Klebsiella pneumoniac
Salmonella montevideo
Salmonella enteritidis
Serratia marcescensc
Xanthomonas maltophilia
Enterococcus faecium
Enterococcus faecalis
Streptococcus coagulansc
S. aureusd
S. aureuse
a
The strains are part of our culture collection and come from
different sources representing ranges of commensal and pathogenic
microorganisms. Three strains. c Two strains. Four strains.
b
d
e MRSA, two strains.
2 mL of BBL supplemented with 5% (v/v) heat-
inactivated fetal calf serum (FCS, Intergen, Purchase,
NY) per well. Cultures were resuspended in BBL at an
OD600 of 0.6, and 50 µL of these cultures was inoculated
into each well to give a final concentration of 107 cells
per mL (OD600 of less than 0.03, which is the same as
that of the noninoculated controls). Plates were then
incubated for 2 days, and the amount of growth was
recorded at OD600 with a plate reader (Molecular
Devices, Sunnyvale, CA). MICs were defined as the
Resu lts
In total, we prepared 36 carbamates 12, 27 amides
13, 13 reversed amides 14, 18 sulfonamides 15, one urea
16, and, in addition to 12a , 10 heterocyclic phenyl

Novel Anti-Helicobacter pylori Agents
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19 4305
Ta ble 3. Compounds Selected and Tested for Anti-H. pylori Activity
MIC (µg/mL)
ARHp strain no.
a
compd
no.
Het
no.
MBC
AUCa
Cmax
mp
R
80
1
>16
81
115c
206
1
>16
(µg/mL) (ng/mL‚h) (ng/mL) (°C) microanalysisb
8
9
CH2CH2OH
CH2COOH
1
1
1
1
>8
>8
NC
NC
NC
NC
146 C17H18N2OS2
227 C17H16N2O2S2‚
1/2H2O‚
>16
>16
1/4EtOAc
11
CH2CH2NH2
1
4
8
4
8
>8
NC
NC
245 C17H19N3S2‚H2O‚
2HCl
12a
12b
12c
12d
13a
CH2CH2OCONHPh
1
1
1
1
1
0.5
0.5
0.5
0.5
1.0
0.5
0.5
0.5
0.5
0.5
1.0
0.5
1
8
8
>8
>8
2074
1630
1127
299
906
797
398
331
57
122 C24H23N3O2S2
CH2CH2OCONH-(3-MeO-Ph)
CH2CH2OCONH-(3,4-di-F-Ph)
CH2CH2OCONH-(4-Me2N-Ph)
CH2CO-(1-piperidinyl)
0.25
0.25
0.5
0.25
0.25
0.5
58
C25H25N3O3S2
135 C24H21F2N3O2S2
133 C26H28N4O2S2
140 C22H25N3OS2‚
1/4H2O
0.25
0.25
135
13b
CH2CONHCH2-(2-thienyl)
1
0.5
1
0.5
1
8
ND
ND
177 C22H21N3OS3‚
1/4EtOAc
13c
14
15
CH2CONH-benzyl
1
1
1
1
2
3
1
0.25
4
0.5
0.25
0.5
1
1
0.5
8
0.5
0.5
0.5
1
1
0.25
4
0.5
0.25
0.5
1
1
0.5
8
0.5
0.5
0.5
1
1
>8
>8
8
8
8
ND
271
NC
283
NC
99
NC
NC
NC
1767
ND
471
NC
140
NC
74
NC
NC
NC
1000
156 C24H23N3OS2
120 C22H21N5OS2
CH2CH2NHCO-(2-pyrazinyl)
CH2CH2NHSO2-(8-quinolinyl)
CH2CH2NHCONHPh
CH2CH2OCONHPh
81
C26H24N4O2S3
16
174 C24H24N4OS2
175 C22H22N2O2S2
17a
17b
Tetd
Mete
Am f
Cla r ig
CH2CH2OCONHPh
79
C20H20N2O2S3
8
0.06
1
0.06
1
0.06
1
0.12
<0.06 <0.06 <0.06 <0.06
a
Compounds were given orally by gavage needle at 30 mg/kg in a vehicle of 85:15 (0.5% aqueous hydroxypropylmethylcellulose:PEG-
400) to C57BL/6NTac female mice (6 weeks, 20 g). C, H, N. c ARHp115 corresponds to strain ATCC 43504 in the accompanying paper,
b
ref 8. Tetracyclin. e Metronidazole. f Amoxicillin. Clarithromycin; NC, not checked; ND, not detected.
d
g
carbamates 17. All samples of sufficient purity were
subjected to evaluation as growth inhibitors in the
microdilution assay. Table 3 contains a summary of
results for representative compounds purified to obtain
satisfactory analytical data and accurate biological
testing results.
In general, we found that a rather large variety of
residues could be incorporated into the target molecules
while retaining microbiological potency. This was espe-
cially true for the sets of carbamates 12 and amides 13
and 14, where a preference for nonbulky hydrophobic
motifs was observed. The sulfonamide analogues 15
displayed poorer potencies as indicated for the quinoline
derivative (R ) quinoline-8-yl, 15). Among the ana-
logues tested, the phenyl carbamate 12a and the benzyl
amide 13c exhibited the most potent bactericidal activi-
ties, MBC ) 1 µg/mL.
To further assess the viability of selected compounds
as drug leads, mice were dosed orally and the plasma
concentrations of compounds were monitored over time.
The observed areas under the curve (AUC) and maxi-
mum plasma concentrations (Cmax) are shown in Table
3 where applicable. Among the tested compounds, the
aryl carbamates gave the best results in this assay. The
phenyl carbamate 12a was chosen as a prototype
because of the combination of an MBC of 1 µg/mL and
an AUC comparable to that of clarithromycin, an
antimicrobial frequently used clinically to control H.
pylori infections. To explore the effects of structural
modifications of 12a , the syntheses of the phenyl urea
analogue 16 and a set of heterocyclic phenyl carbamate
variants 17 were undertaken. The results indicate that
these modifications yielded compounds with similar
microbiological properties but with inferior pharmaco-
kinetic properties. The phenyl carbamate 12a therefore
remained the model compound and was submitted to a
more thorough evaluation.
Thus, 12a was evaluated for its effects on the growth
of a variety of clinically important aerobic (13 different
bacterial species including two strains of methicillin
resistant S. aureus) and anaerobic microorganisms (16
different bacterial species), cf. Table 2. No significant
growth inhibition effects were observed at concentra-
tions up to 64 µg/mL as evidenced in Figure 1. To
further assess the spectrum of activity, 12a was also
screened against a panel of 27 H. pylori strains, cf. Table
1. An MIC90 of 0.25 µg/mL was observed as illustrated
in Figure 1. Hence, a clear antibacterial selectivity for
strains of H. pylori over both aerobic and anaerobic
microorganisms was observed for compound 12a . The
kinetics of H. pylori ARHp206 killing of 12a were
evaluated at 1 µg/mL and found to be comparable to that
of clarithromycin (Figure 2). Furthermore, the rate of
spontaneous resistance development to 12a in a sus-
ceptible (H. pylori ARHp206) and a metronidazole
resistant (H. pylori ARHp80) strain was measured and
found to be less than 10-9
.
Discu ssion
Currently preferred H. pylori therapies call for a
combination of a proton pump inhibitor, e.g., omepra-
zole,7 and two antimicrobials. Amoxicillin, clarithromy-
cin, and metronidazole7,11 are the ones most frequently
used. Eradication rates for these therapies typically vary

4306 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19
Carcanague et al.
clarithromycin with an AUC of 1767 ng/mL‚h. Indeed,
many of the carbamates studied display AUCs between
1000 and 2000 ng/mL‚h. Additionally, the Cmax observed
for 12a of 0.9 µg/mL was approximately twice the MICs
measured for the four H. pylori strains used in the
microdilution assay (0.5 µg/mL) and was nearly equiva-
lent to the MBC (1 µg/mL).
Moreover, H. pylori exhibits an acceptable rate of
spontaneous resistance development against 12a . In
addition, strains that already are metronidazole or
clarithromycin resistant do not show increased resis-
tance rates. This finding suggests that preexisting
resistance found in H. pylori in the clinical setting could
be overcome by new chemical entities belonging to, e.g.,
the 12a carbamate family.
The entire biologically relevant chemical diversity
space21 might not have been fully probed or explored in
this study. Accordingly, we believe that a second round
of highly focused SAR work around the carbamate
family, applying appropriate property filters, scoring
functions, and experimental design algorithms,21 would
indeed identify compounds that meet additional criteria
such as metabolic stability and in vivo efficacy and
tolerability.
F igu r e 1. MIC distribution of compound 12a against panels
of 27 H. pylori strains (MIC90 ) 0.25 µg/mL), 25 aerobic
bacterial strains (MIC90 ) >64 µg/mL), and 18 anaerobic
bacterial strains (MIC90 ) >64 µg/mL), cf. Tables 1 and 2 for
a list of microorganisms.
To conclude, a parallel chemistry expansion of the
2-({3-[(1H-benzimidazol-2-ylsulfanyl)methyl]phenyl}-
sulfanyl)-1-ethanol scaffold (2) successfully rendered a
set of carbamates with the generic structure 12, which
displayed potent and selective activity against the
gastric pathogen H. pylori. The measured rate of
resistance development against 12a was found to be less
than 10-9, a clinically acceptable level, and pharmaco-
kinetic studies revealed in vivo exposure levels compa-
rable with those established for antimicrobials currently
used in H. pylori triple regimen. Further elaboration of
the carbamate family 12 to exploit its unusual selective
anti-H. pylori activity is therefore justified.
F igu r e 2. Killing kinetics of compound 12a and clarithro-
mycin against H. pylori strain ARHp206 determined at 1 µg/
mL of each compound. No H. pylori killing was observed in
the absence of compound.
between 80 and 95%,12-15 depending on which particular
H. pylori strain(s) are responsible for the infection.16,17
Infections caused by strains susceptible to amoxicillin,
clarithromycin, or metronidazole are generally more
easily cured, while those caused by clarithromycin or
metronidazole resistant strains are much more difficult
to clear. Over the past decade, increased resistance to
the antimicrobial components of the triple therapy
regimens has been observed,18,19 and these findings are
indeed major drivers for developing novel anti-H. pylori
agents.
We conclude that the phenyl carbamate 12a disclosed
in this paper does meet several significant in vitro
microbiological criteria required for a novel anti-H.
pylori agent. It displays low MIC values against a rather
broad panel of H. pylori strains, including strains
resistant to either metronidazole or clarithromycin, or
both, while it is almost inactive against a rather wide
range of commensal or pathogenic microorganisms. The
combination of such a selectivity for one species (H.
pylori) combined with a broad intraspecies antibacterial
activity is remarkable and does indeed provide a unique
opportunity for exploitation. This is especially true since
12a displays bactericidal activity and killing rates at
equally low concentrations as those of compounds
routinely used in the clinic, namely, clarithromycin and
amoxicillin.20 Moreover, pharmacokinetic exposure lev-
els were also in the same order of magnitude as, e.g.,
Exp er im en ta l Section
Gen er a l. Chemicals, reagents, and solvents were purchased
from any of the major vendors if nothing else is stated or
referenced. NMR spectra were recorded on a 500 MHz instru-
ment manufactured by Bruker, Switzerland. Mass spectra
were recorded on a VG Platform II equipped with an electro-
spray (ESI) source, both purchased from Micromass, U.K.
Compound purity was checked by chromatographic means and/
or microanalysis.
Ch r om a togr a p h y. Preparative HPLC was run on ODS-
AQ columns (5 µm, 30 mm × 250 mm) obtained from YMC
Inc., Wilmington, NC, using MeCN/0.1 M NH4OAc buffer (pH
7) as eluent at a flow rate of 30 mL/min with gradient from
10 to 100% MeCN in 20 min, followed by another 10 min at
100% MeCN.
Ch em istr y. Meth yl 2-{[3-(Hyd r oxym eth yl)-2-m eth yl-
p h en yl]su lfa n yl}a ceta te (5). An ice cold solution of 3-amino-
2-methylbenzoic acid (3), (11.3 g, 75 mmol) in H2O (100 mL)
was treated with concentrated HCl (15 mL), and NaNO2 (5.5
g, 80 mmol) in H2O (40 mL) was added over 30 min. The
incipient diazonium salt was kept at 0 °C and over 40 min
added to a solution of methyl thioglycolate (8.48 g, 80 mmol)
in methanol (50 mL) kept at 60 °C. During the addition, the
pH of the reaction medium was kept in the range of 5-6 by
very carefully adding saturated Na2CO3. After the end of
addition, the reaction was heated at 60-70 °C for an additional
45 min. The mixture was cooled to 0 °C, and the pH was
adjusted to approximately 1 with concentrated HCl and
extracted with EtOAc. The organic layer was collected, dried
over Na2SO4, filtered, and evaporated to leave 17.4 g of crude

Novel Anti-Helicobacter pylori Agents
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19 4307
3-[(2-methoxy-2-oxoethyl)sulfanyl]-2-methylbenzoic acid (4).
The acid was dissolved in tetrahydrofuran (THF, 120 mL) and
cooled on an ice bath. 1 M Borane-THF solution (130 mL, 130
mmol) was added, and the mixture was allowed to react for 1
h. The reaction was quenched with ice water and extracted
with EtOAc. The organic layer was collected, dried over Na2-
SO4, evaporated, and purified on silica gel (CH2Cl2/EtOAc, 20/
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylp h en yl}su lfa n yl)eth yla m in e (11). Compound 10,
2-({3-[(2-azidoethyl)sulfanyl]-2-methylbenzyl}sulfanyl)-1H-
benzimidazole (0.42 g, 1.2 mmol), was added to an ice cold
suspension of LAH (0.3 g, 7.9 mmol) in THF (10 mL). After 45
min, the reaction was carefully quenched with sodium sulfate
decahydrate and filtered. The filtrate was evaporated, and the
residue was dissolved in EtOAc and washed with 1 N HCl.
The aqueous layer was collected, washed with EtOAc, and
evaporated to give a white solid. The solid was dried in vacuo,
dissolved in MeOH, and reprecipitated with Et2O to yield 253
mg (58%) of the target compound a white powder; mp 245 °C.
1H NMR (H2O-d2): δ 2.5 (s, 3H), 3.13 (t, J ) 6.3 Hz, 2H), 3.18
(t, J ) 6.3 Hz, 2H), 4.62 (s, 2H), 7.08 (t, J ) 7.5 Hz, 1H), 7.13
(t, J ) 7.5 Hz, 1H), 7.38 (t, J ) 7.5 Hz, 1H), 7.56 (m, 2H), 7.68
(m, 2H). MS (ESI) for C17H19N3S2 m/z (relative intensity): 330
(M + H, 100). Anal. (C17H19N3S2‚H2O‚2HCl) C, H, N.
1
1) to give 5 g (22%) of the target compound. H NMR (CHCl3-
d): δ 2.45 (s, 3H), 3.62 (s, 2H), 3.71 (s, 3H), 4.72 (s, 2H), 7.18
(t, J ) 7.8 Hz, 1H), 7.28 (t, J ) 7.8 Hz, 1H), 7.35 (d, J ) 7.8
Hz, 1H).
Meth yl 2-({3-[(1H-Ben zim id a zol-2-ylsu lfa n yl)m eth yl]-
2-m eth ylp h en yl}su lfa n yl)a ceta te (7). Compound 5 (4.4 g,
19 mmol) was dissolved in methylene chloride (220 mL),
treated with thionyl chloride (5 mL, 68 mmol), and allowed to
react at ambient temperature for 4 h. The solvents were
evaporated to yield 4.3 g of crude methyl 2-{[3-(chloromethyl)-
2-methylphenyl]sulfanyl}acetate (6) as a slightly brown oil.
The chloride 6 was dissolved in methanol (50 mL) and mixed
with an ice cold solution of 2-mercaptobenzimidazole (2.69 g,
18 mmol) dissolved in a mixture of water (10 mL), methanol
(30 mL), and NaOH (0.71 g, 18 mmol). The methanolic solution
was allowed to react at ambient temperature for 6 h and then
taken to dryness. The residue was partitioned between CH2-
Cl2 (600 mL) and 5% Na2CO3 (300 mL). The organic layer was
collected, dried over Na2SO4, and evaporated to give 4.2 g (62%)
of the target compound as a light yellow solid. 1H NMR (CHCl3-
d): δ 2.49 (s, 3H), 3.60 (s, 2H), 3.75 (s, 3H), 4.54 (s, 2H), 7.00
(t, J ) 7.7 Hz, 1H), 7.08 (d, J ) 7.7 Hz, 1H), 7.24-7.28 (m,
2H), 7.31 (d, J ) 7.7 Hz, 1H), 7.57 (bm, 2H). MS (ESI) for
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylp h en yl}su lfa n yl)eth yl P h en ylca r ba m a te (12a ). A
solution of 2-({3-[(1H-benzimidazol-2-ylsulfanyl)methyl]-2-
methylphenyl}sulfanyl)-1-ethanol (100 mg, 0.3 mmol) and
phenyl isocyanate (35 mg, 0.3 mmol) in DMF (2 mL) was
allowed to react for 18 h at ambient temperature. The mixture
was concentrated in vacuo and purified by reversed phase LC
to yield 60 mg (44%) of the target compound as a white solid;
1
mp 122 °C. H NMR (DMSO-d6): δ 2.42 (s, 3H), 3.27 (t, J )
6.6 Hz, 2H), 4.25 (t, J ) 6.6 Hz, 2H), 4.62 (s, 2H), 7.00 (bt,
1H), 7.14-7.18 (m, 2H), 7.27-7.31 (m, 4H), 7.38-7.40 (m, 2H),
7.48 (m, 2H), 7.56 (m, 1H), 9.75 (s, 1H). MS (ESI) for
C
24H23N3O2S2 m/z (relative intensity): 450 (M + H, 100). Anal.
(C24H23N3O2S2) C, H, N.
C
18H18N2O2S2 m/z (relative intensity): 359 (M + H, 100).
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylp h en yl}su lfa n yl)eth yl 3-Meth oxyp h en ylca r ba m -
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylp h en yl}su lfa n yl)-1-eth a n ol (8). Compound 7 (5.7 g,
16 mmol) was dissolved in THF (100 mL) and cooled on a ice-
bath. LAH (0.5 g, 13 mmol) was added portion wise over 5
min. After it reacted for 30 min, the reaction was carefully
quenched with sodium sulfate decahydrate. Filtration and
evaporation afforded 4.1 g (78%) of the target copmound; mp
1
a te (12b). White solid; mp 54-58 °C. H NMR (DMSO-d6): δ
2.34 (s, 3H), 3.18 (t, J ) 6.5 Hz, 2H), 3.27 (s, 3H), 4.16 (t, J )
6.5 Hz, 2H), 4.53 (s, 2H), 6.50 (dd, J ) 8.2, 2.3 Hz, 1H), 6.96
(bd, 1H), 7.05-7.12 (m, 5H), 7.21 (d, J ) 7.4 Hz, 1H), 7.30 (m,
2H), 7.48 (bm, 1H), 9.66 (s, 1H). MS (ESI) for C25H25N3O3S2
m/z (relative intensity): 480 (M + H, 100). Anal. (C25H25N3O3S2)
C, H, N.
1
146 °C. H NMR (DMSO-d6): δ 2.40 (s, 3H), 3.03 (t, J ) 6.8
Hz, 2H), 3.60 (t, J ) 6.8 Hz, 2H), 4.63 (s, 2H), 7.13-7.16 (m,
3H), 7.26-7.30 (m, 2H), 7.48 (bm, 2H). MS (ESI) for C17H18N2-
OS2 m/z (relative intensity): 331 (M + H, 100). Anal. (C17H18N2-
OS2) C, H, N.
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylph en yl}su lfa n yl)eth yl 3,4-Diflu or op h en ylca r ba m -
a te (12c). White solid; mp 135 °C. 1H NMR (DMSO-d6): δ 2.33
(s, 3H), 3.19 (t, J ) 6.5 Hz, 2H), 4.17 (t, J ) 6.5 Hz, 2H), 4.53
(s, 2H), 7.05-7.49 (m, 10H), 9.92 (s, 1H). MS (ESI) for
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylp h en yl}su lfa n yl)a cetic Acid (9). Compound 7 (0.68
g, 1.9 mmol) was dissolved in MeOH (14 mL) and allowed to
react with LiOH (0.25 g, 10 mmol) dissolved in H2O (2 mL)
for 1 h. The solvents were evaporated, and the residue was
partitioned between 5% Na2CO3 (100 mL) and ethyl acetate
(100 mL). The aqueous layer was collected, and the pH was
adjusted to about 4 with 4 M HCl and extracted with a 2:1
EtOAc/THF mixture. The combined organic layers were dried
over MgSO4 and evaporated to 0.5 g (76%) of the title
C
24H21F2N3O2S2 m/z (relative intensity): 486 (M + H, 100).
Anal. (C24H21F2N3O2S2) C, H, N.
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylp h en yl}su lfa n yl)eth yl 4-(Dim eth yla m in o)p h en yl-
1
ca r ba m a te (12d ). White solid; mp 133 °C. H NMR (DMSO-
d6): δ 2.33 (s, 3H), 2.75 (s, 6H), 3.16 (t, J ) 6.6 Hz, 2H), 4.12
(t, J ) 6.6 Hz, 2H), 4.54 (s, 2H), 6.60 (d, J ) 9.0 Hz, 2H), 7.04-
7.09 (m, 3H), 7.18-7.22 (m, 3H), 7.30 (d, J ) 7.7 Hz, 2H), 7.47
(bs, 1H), 9.28 (s, 1H). MS (ESI) for C26H28N4O2S2 m/z (relative
intensity): 493 (M + H, 100). Anal. (C26H28N4O2S2) C, H, N.
1
compound as a white solid; mp 227 °C. H NMR (DMSO-d6):
δ 2.40 (s, 3H), 3.8 (s, 2H), 4.6 (s, 2H), 7.1-7.15 (m, 3H), 7.22
(d, J ) 7.5 Hz, 1H), 7.27 (d, J ) 7.5 Hz, 1H), 7.47 (bs, 2H). MS
(ESI) for C17H16N2O2S2 m/z (relative intensity): 345 (M + H,
100). Anal. (C17H16N2O2S2‚1/2H2O‚1/4EtOAc) C, H, N.
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylph en yl}su lfan yl)-1-(1-piper idin yl)-1-eth an on e (13a).
A mixture of 9 (100 mg, 0.29 mmol), piperidine (30 mg, 0.32
mmol), and HBTU (120 mg, 0.32 mmol) was dissolved in DMF
(2 mL) and allowed to react for 18 h. The mixture was taken
up in EtOAc and washed with 5% NaHC03 and brine. The
organic layer was collected, dried over MgSO4, and evaporated
2-({3-[(2-Azidoeth yl)su lfan yl]-2-m eth ylben zyl}su lfan yl)-
1H-ben zim id a zole (10). A mixture of 9 (0.165 g, 0.5 mmol),
triphenylphosphine (0.184 g, 0.7 mmol), and sodium azide (0.13
g, 2 mmol) in dimethylformamide (DMF, 4 mL) was stirred
on an ice bath. Carbon tetrabromide (0.25 g, 0.75 mmol) was
added, and the reaction was allowed to proceed for 18 h.
Methylene chloride (20 mL) was added, the resulting suspen-
sion was filtered, and the solids were rinsed with CH2Cl2. The
filtrate was washed with brine, dried over Na2SO4, and
evaporated. Purification on silica gel (EtOAc/hexane, 1/5) gave
85 mg (48%) of the title compound. 1H NMR (CHCl3-d): δ 2.49
(s, 3H), 3.05 (t, J ) 7 Hz, 2H), 3.45 (t, J ) 7 Hz, 2H), 4.61 (s,
2H), 7.07 (t, J ) 7.7 Hz, 1H), 7.21-7.26 (m, 3H), 7.29 (d, J )
8.4 Hz, 1H), 7.55 (bm, 2H). MS (ESI) for C17H17N5S2 m/z
(relative intensity): 356 (M + H, 100).
1
to furnish 110 mg (92%) of the title compound; mp 140 °C. H
NMR (DMSO-d6): δ 1.20 (bm, 2H), 1.29 (bm, 2H), 1.35 (bm,
2H), 2.20 (s, 3H), 3.20 (s, bm, 4H), 3.69 (s, 2H), 4.39 (s, 2H),
6.90-6.94 (bm, 3H), 7.05 (d, J ) 7.9 Hz, 1H), 7.13 (d, J ) 7.9
Hz, 1H), 7.25 (bm, 2H). MS (ESI) for C22H25N3OS2 m/z (relative
intensity): 412 (M + H, 100). Anal. (C22H25N3OS2‚1/4H2O) C,
H, N.
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m et h ylp h en yl}su lfa n yl)-N-(2-t h ien ylm et h yl)a cet a m id e
(13b). White solid; mp 177 °C. MS (ESI) for C22H21N3OS3 m/z
1
(relative intensity): 440 (M + H, 100). H NMR (DMSO-d6):
δ 2.44 (s, 3H), 3.73 (s, 2H), 4.49 (d, J ) 5.8 Hz, 2H), 4.66 (s,

4308 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 19
Carcanague et al.
2H), 6.98 (m, 2H), 7.14-7.20 (m, 3H), 7.30 (m, 2H), 7.43 (m,
2H), 7.60 (m, 1H), 8.80 (t, J ) 5.8 Hz, 1H). Anal. (C22H21N3-
OS3‚1/4EtOAc) C, H, N.
1H), 7.17-7.46 (m, 7H), 7.70 (d, J ) 3.3 Hz, 1H), 7.79 (d, J )
3.3 Hz, 1H), 9.74 (bs, 1H). MS (ESI) for C20H20N2O2S3 m/z
(relative intensity): 417 (M + H, 100). Anal. (C20H20N2O2S3)
C, H, N.
2-({3-[(1H -B e n z i m i d a z o l-2-y ls u lfa n y l)m e t h y l]-2-
m eth ylp h en yl}su lfa n yl)-N-ben zyla ceta m id e (13c). White
Meth yl 2-{[3-({[ter t-Bu tyl(d im eth yl)silyl]oxy}m eth yl)-
2-m eth ylp h en yl]su lfa n yl}a ceta te (18). A mixture of 5 (9.8
g, 43 mmol), imidazole (5 g, 74 mmol) and TBDMSCl (8 g, 53
mmol) in DMF (15 mL) was allowed to react at ambient
temperature for 45 min. The mixture was taken up in EtOAc
and washed with 1 N HCl, H2O, and brine. The organic layer
was collected, dried over MgSO4, and evaporated leaving 14 g
(95%) of the target compound as a yellow liquid. 1H NMR
(CHCl3-d): δ 0.11 (s, 6H), 0.97 (s, 9H), 2.39 (s, 3H), 3.62 (s,
2H), 3.72 (s, 2H), 4.72 (s, 2H), 7.20 (t, J ) 7.7 Hz, 1H), 7.34 (d,
J ) 7.7 Hz, 1H), 7.38 (d, J ) 7.7 Hz, 1H).
2-{[3-({[ter t-Bu tyl(d im eth yl)silyl]oxy}m eth yl)-2-m eth -
ylp h en yl]su lfa n yl}-1-eth a n ol (19). LAH (2 g, 53 mmol) was
slowly added to a stirred ice cold solution of 18 (14 g, 41 mmol)
in THF (50 mL) and allowed to react for 30 min. The reaction
was quenched with H2O (2 mL) and 4 M NaOH (1 mL). The
mixture was filtered, and the solids were rinsed with THF.
The filtrate was taken up in EtOAc and washed with 1 N HCl
and brine. The organic layer was collected, dried over MgSO4,
and evaporated to leave 11 g (86%) of title compound as a
yellow liquid. 1H NMR (CHCl3-d): δ 0.12 (s, 6H), 0.97 (s, 9H),
2.40 (s, 3H), 3.09 (t, J ) 6.0 Hz, 2H), 3.75 (t, J ) 6.0 Hz, 2H),
4.72 (s, 2H), 7.19 (t, J ) 7.7 Hz, 1H), 7.34 (d, J ) 7.7 Hz, 1H),
7.37 (d, J ) 7.7 Hz, 1H).
1
solid; mp 156 °C. H NMR (DMSO-d6): δ 2.41 (s, 3H), 3.72 (s,
2H), 4.28 (d, J ) 5.9 Hz, 2H), 4.62 (s, 2H), 7.09-7.23 (m, 10H),
7.38 (bs, 1H), 7.56 (bs, 1H), 8.65 (t, J ) 5.9 Hz, 1H), 12.61 (s,
1H). MS (ESI) for C24H23N3OS2 m/z (relative intensity): 434
(M + H, 100). Anal. (C24H23N3OS2) C, H, N.
N -[2-({3-[(1H -b e n zim id a zol-2-ylsu lfa n yl)m e t h yl]-2-
m et h ylp h en yl}su lfa n yl)et h yl]-2-p yr a zin eca r b oxa m id e
(14). A mixture of 11 (658 mg, 2 mmol), 2-pyrazinecarboxylic
acid (248 mg, 2 mmol), DIPEA (1 mL, 5.7 mmol), and HBTU
(829 mg, 2.2 mmol) in DMF (8 mL) was allowed to react
overnight. The mixture was diluted with EtOAc (200 mL) and
washed with water (2 × 100 mL) and brine. The organic layer
was dried over MgSO4 and taken to dryness. The residue was
purified by reversed phase LC to furnish 600 mg (69%) of the
1
title compound as a white solid; mp 120 °C. H NMR (DMSO-
d6): δ 2.39 (s, 3H), 3.17 (t, J ) 6.5 Hz, 2H), 3.54 (dt, J ) 6.5,
1.4 Hz, 2H), 4.61 (s, 2H), 7.14-7.55 (m, 7H), 8.75 (s, 1H), 8.89
(s, 1H), 9.21 (bs, 1H). MS (ESI) for C22H21N5OS2 m/z (relative
intensity): 436 (M + H, 100). Anal. (C22H21N5OS2) C, H, N.
N -[2-({3-[(1H -Be n zim id a zol-2-ylsu lfa n yl)m e t h yl]-2-
m et h ylp h en yl}su lfa n yl)et h yl]-8-q u in olin esu lfon a m id e
(15). A solution of 11 (100 mg, 0.3 mmol) dissolved in THF/
DMF (1:1, 2 mL) was allowed to react with 8-quinolinesulfonyl
chloride (70 mg, 0.3 mmol) and triethylamine (70 mg, 0.3
mmol) for 2 h. The mixture was taken to dryness, and the
residue was purified by reversed phase preparative LC to give
95 mg (61%) of the target compound as a white powder; mp
81 °C. 1H NMR (DMSO-d6): δ 2.27 (s, 3H), 2.93 (t, J ) 6.3 Hz,
2H), 3.04 (t, J ) 6.3 Hz, 2H), 4.57 (s, 2H), 7.01 (m, 2H), 7.15
(m, 2H), 7.22 (m, 1H), 7.38 (m, 1H), 7.48 (bt, 1H), 7.56 (m,
1H), 7.71-7.77 (m, 2H), 8.30 (dt, J ) 8.5, 1.5 Hz, 2H), 8.55
(dd, J ) 8.5, 1.5 Hz, 1H), 9.05 (m, 1H), 12.58 (s, 1H). MS (ESI)
for C26H24N4O2S3 m/z (relative intensity): 521 (M + H, 100).
Anal. (C26H24N4O2S3) C, H, N.
2-{[3-(H yd r oxym e t h yl)-2-m e t h ylp h e n yl]su lfa n yl}-
eth yl p h en ylca r ba m a te (21). A mixture of 19 (11 g, 35
mmol), phenyl isocyanate (6.58 g, 55 mmol), and 4-(dimethy-
lamino)pyridine (10 mg, 0.08 mmol) in THF (10 mL) was
allowed to react for 2 h at 50 °C. The mixture was taken up in
EtOAc and washed with 1 N HCl and brine. The organic layer
was collected, dried over MgSO4, and evaporated to afford
crude
2-{[3-({[tert-butyl(dimethyl)silyl]oxy}methyl)-2-
methylphenyl]sulfanyl}ethyl phenylcarbamate 20. 1H NMR
(CHCl3-d): δ 0.13 (s, 6H), 0.95 (s, 9H), 2.40 (s, 3H), 3.17 (t, J
) 6.6 Hz, 2H), 4.34 (t, J ) 6.6 Hz, 2H), 4.72 (s, 2H), 6.54 (bs,
1H), 7.11-7.41 (m, 8H). The crude carbamate was dissolved
in THF (10 mL) and allowed to react with 75% aqueous
tetrabutylammonium fluoride (17 mL, 47 mmol) at ambient
temperature for 1 h. The mixture was taken up in 1 N HCl
and extracted with EtOAc. The organic layer was collected,
washed with brine, and dried over MgSO4. Purification was
done on silica gel (EtOAc/hexane, 1/9 to 3/7). An oily yellowish
solid was obtained, which was triturated with hexane, collected
on a sintered glass frit, and rinsed with hexane to yield 4.43
N -[2-({3-[(1H -b e n zim id a zol-2-ylsu lfa n yl)m e t h yl]-2-
m eth ylp h en yl}su lfa n yl)eth yl]-N′-p h en ylu r ea (16). A soul-
tion of 11 (100 mg, 0.3 mmol) dissolved in DMF (2 mL) and
phenyl isocyanate (36 mg, 0.3 mmol) was allowed to react at
ambient temperature overnight. The solvent was evaporated,
and the residue was purified by reversed phase preparative
LC furnishing 85 mg (63%) of the target compound as a white
1
powder; mp 174 °C. H NMR (DMSO-d6): δ 2.33 (s, 3H), 2.98
(t, J ) 6.6 Hz, 2H), 3.22 (dt, J ) 6.6, 5.9 Hz, 2H), 4.54 (s, 2H),
6.39 (t, J ) 5.9 Hz, 1H), 6.91 (t, J ) 7.3 Hz, 1H), 7.13-7.17
(m, 3H), 7.22-7.28 (m, 3H), 7.37-7.41 (m, 4H), 7.56 (m, 1H),
8.62 (s, 1H); 12.61 (s, 1H). MS (ESI) for C24H24N4OS2 m/z
(relative intensity): 449 (M + H, 100). Anal. (C24H24N4OS2)
C, H, N.
1
g (40%) of the target compound as a white powder. H NMR
(CHCl3-d): δ 2.48 (s, 3H), 3.19 (t, J ) 6.7 Hz, 2H), 4.35 (t, J )
6.7 Hz, 2H), 4.72 (s, 2H), 6.55 (bs, 1H), 7.09-7.36 (m, 8H).
2-{[3-(Ch lor om et h yl)-2-m et h ylp h en yl]su lfa n yl}et h yl
P h en ylca r ba m a te (22). An ice cold solution of 21 (0.5 g, 1.6
mmol) in THF (3 mL) was treated with SOCl2 (1 mL, 14 mmol)
and allowed to react at ambient temperature for 45 min.
Evaporation of the solvent and trituration of the residue with
hexane gave 525 mg (98%) of the title compound as an off-
white solid. 1H NMR (CHCl3-d): δ 2.54 (s, 3H), 3.20 (t, J )
6.6 Hz, 2H), 4.35 (t, J ) 6.6 Hz, 2H), 4.63 (s, 2H), 6.52 (bs,
1H), 7.10-7.37 (m, 8H).
2-({2-Meth yl-3-[(4-p yr id in ylsu lfa n yl)m eth yl]p h en yl}-
su lfa n yl)eth yl p h en ylca r ba m a te (17a ). A vigorously stirred
solution of of 2-{[3-(chloromethyl)-2-methylphenyl]sulfanyl}-
ethyl phenylcarbamate (22) (135 mg, 0.4 mmol) in DMF (2 mL)
was treated with 4-thiopyridine (65 mg, 0.59 mmol) and K2-
CO3 (65 mg, 0.59 mmol) and allowed to react at ambient
temperature for 1.5 h. The mixture was diluted to 25 mL with
EtOAc, washed with H2O (15 mL), 2 × 1 N KOH (15 mL), and
brine (15 mL). The organic layer was collected, dried over
MgSO4, and taken to dryness leaving a thick oil. Purification
on silica gel (EtOAc/hexane, 1/9 to 3/7) furnished 130 mg (79%)
Ack n ow led gm en t. Mr. Matt Dube (AstraZeneca
R&D Boston) is appreciated for carrying out the mi-
crodilution assay experiments.
1
of the target compound as a waxy solid; mp 175 °C. H NMR
(DMSO-d6): δ 2.41 (s, 3H), 3.28 (t, J ) 6.5 Hz, 2H), 4.25 (t, J
) 6.5 Hz, 2H), 4.40 (s, 2H), 7.01 (t, J ) 7.3 Hz, 1H), 7.20-
7.49 (m, 9H), 8.40 (d, J ) 4.5 Hz, 2H), 9.75 (bs, 1H). MS (ESI)
for C22H22N2O2S2 m/z (relative intensity): 411 (M + H, 100).
Anal. (C22H22N2O2S2) C, H, N.
2-({2-Meth yl-3-[(1,3-th iazol-2-ylsu lfan yl)m eth yl]ph en yl}-
su lfa n yl)eth yl P h en ylca r ba m a te (17b). White solid; mp 79
°C. 1H NMR (DMSO-d6): δ 2.39 (s, 3H), 3.26 (t, J ) 6.5 Hz,
2H), 4.25 (t, J ) 6.5 Hz, 2H), 4.53 (s, 2H), 7.01 (t, J ) 7.3 Hz,
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