Studies of non-nucleoside HIV-1 reverse transcriptase inhibitors. Part 2: Synthesis and structure-activity relationships of 2-cyano and 2-hydroxy thiazolidenebenzenesulfonamide derivatives

Article abstract of DOI:10.1016/j.bmc.2004.11.045

In a previous study, we described the structure-activity relationships (SARs) for a series of thiazolidenebenzenesulfonamide derivatives. These compounds were found to be highly potent inhibitors of the wild type (WT) and Y181C mutant reverse transcriptas

Full text of DOI:10.1016/j.bmc.2004.11.045

Bioorganic & Medicinal Chemistry 13 (2005) 949–961
Studies of non-nucleoside HIV-1 reverse transcriptase
inhibitors. Part 2: Synthesis and structure–activity
relationships of 2-cyano and 2-hydroxy
thiazolidenebenzenesulfonamide derivatives
Naoyuki Masuda,a,* Osamu Yamamoto,a Masahiro Fujii,a Tetsuro Ohgami,a
Jiro Fujiyasu,a Toru Kontani,a Ayako Moritomo,a Masaya Orita,a
Hiroyuki Kurihara,a Hironobu Koga,a Shunji Kageyama,a Mitsuaki Ohta,a
Hiroshi Inoue,a Toshifumi Hatta,a Masafumi Shintani,a Hiroshi Suzuki,a
Kenji Sudo,a Yasuaki Shimizu,a Eiichi Kodama,b Masao Matsuoka,b
Masatoshi Fujiwara,c Tomoyuki Yokota,c Shiro Shigetad and Masanori Babae
aInstitute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd, 21 Miyukigaoka, Tsukuba, Ibaraki 305-8585, Japan
bLaboratory of Virus Immunology, Institute for Virus Research, Kyoto University, 53 Syogoin, Kawaramachi,
Sakyo-ku, Kyoto 606-8507, Japan
cRational Drug Design Laboratories, 4-1-1, Misato, Matsukawa-Machi, Fukushima 960-1242, Japan
dDepartment of Microbiology, School of Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima 960-1295, Japan
eDivision of Antiviral Chemotherapy, Center for Chronic Viral Diseases, Graduate School of Medical and Dental Sciences,
Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan
Received 13 October 2004; revised 24 November 2004; accepted 24 November 2004
Available online 18 December 2004
Abstract—In a previous study, we described the structure–activity relationships (SARs) for a series of thiazolidenebenzenesulfon-
amide derivatives. These compounds were found to be highly potent inhibitors of the wild type (WT) and Y181C mutant reverse
transcriptases (RTs) and modest inhibitors ofK103N RT. These molecules are thus considered to be a novel class ofnon-nucleoside
HIV-1 RT inhibitors (NNRTIs). In this paper, we have examined the effects ofsubstituents on both the thiazolidene and benzene-
sulfonamide moieties. Introduction of a 2-cyanophenyl ring into these moieties significantly enhanced anti-HIV-1 activity, whereas a
2-hydroxyphenyl group endowed potent activity against RTs, including K103N and Y181C mutants. Among the series ofmolecules
examined, 10l and 18b (YM-228855), combinations of2-cyanophenyl and 4-methyl-5-isopropylthiazole moieties, showed extremely
potent anti-HIV-1 activity. The EC50 values of 101 and 18b were 0.0017 and 0.0018 lM, respectively. These values were lower than
that ofefavirenz ( 3). Compound 11g (YM-215389), a combination of2-hydroxyphenyl and 4-chloro-5-isopropylthiazole moieties,
proved to be the most active against both K103N and Y181C RTs with IC50 values of0.043 and 0.013 lM, respectively.
ꢀ 2004 Elsevier Ltd. All rights reserved.
1. Introduction
considered to be an attractive target for inhibition of
HIV-1 replication.1 Non-nucleoside reverse transcrip-
tase inhibitors (NNRTIs), a group ofstructurally di-
verse compounds, have been reported to directly
inhibit the enzyme in an allosteric fashion by binding
to a pocket near the polymerase active site.2 To date,
many classes ofNNRTIs have been identified, and three
inhibitors, nevirapine, delavirdine, and efavirenz, have
been approved for the treatment of HIV-1 infection.
However, NNRTI-containing regimens are compro-
mised by rapid emergence ofdrug-resistant strains
Reverse transcriptase (RT) is a key enzyme, which plays
an essential and multifunctional role in the replication of
human immunodeficiency virus type 1 (HIV-1) and thus
Keywords: Thiazolidenebenzenesulfonamide; Non-nucleoside HIV-1
reverse transcriptase inhibitor; YM-215389.
*
Corresponding author. Tel.: +81 298 63 6752; fax: +81 298 52
2971; e-mail: masuda.naoyuki@yamanouchi.co.jp
0968-0896/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.11.045

950
N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
O
NC
MeOOC
a, b, c
O
S
O
O
S
O
d
N
N
N
N
HN
F3C
NO2
NO2
Cl
S
R
ClO2S
Cl
R
R
H2N
S
S
O
O
O
N
H
O
4a: R = Cl
4b: R = F
4c: R = Br
5a: R = Cl
5b: R = F
5c: R = Br
6n: R = Cl
6o: R = F
6p: R = Br
1
2
3
Figure 1. Structures ofthiazolidenebenzenesulfonamide derivatives ( 1,
2) and efavirenz (3).
MeOOC
H2N
MeOOC
ClO2S
a, b
CN
CN
carrying the amino acid mutations surrounding the
NNRTI binding pocket.
4d
6q
Scheme 1. Reagents and conditions: (a) NaNO2, HCl/AcOH; (b) SO2,
CuCl, CuCl2/AcOH–H2O; (c) NH3 aq; (d) PCl5.
The mutation oftyrosine to cysteine at position 181 in
HIV-1 RT (Y181C) following treatment with nevirapine
or delavirdine has been documented in cell culture
experiments.3 Furthermore, the mutation oflysine to
asparagine at position 103 (K103N) is frequently ob-
served in patients who do not respond to the treatment
with either NNRTI alone or in combination with other
inhibitors.4 The newest NNRTI, efavirenz (3) has been
shown significant clinical efficacy in combination with
both protease-containing and protease-sparing regi-
mens.5 Although the majority ofpatients receiving efavi-
renz-containing regimens show a sustained antiviral
response, more than 90% ofthe viruses isolated rfom
the patients whose viral loads have rebounded after an
initial drug response have the K103N mutation.6
vatives (10f–h, j, k, o, p) using BBr3 provided the corre-
sponding phenol analogues (11a–g).
As shown in Scheme 3, the nitro compound 10i was
converted into aniline 12 by catalytic hydrogenation.
Aniline 12 was reacted with acetyl chloride or
methanesulfonyl chloride to provide acetamide 13 and
methanesulfonamide 14, respectively. The triflates 15a
and 15b were prepared from the corresponding phenol
analogues (11e,f). A palladium-catalyzed carbon mon-
oxide insertion with triflate 15a afforded the methoxy-
carbonyl derivative 16.9 Hydrolysis ofthe ester
derivatives (16, 10q) followed by amidation gave the car-
bamoyl derivatives (17a,b). The cyano derivatives 18a
and 18b were obtained by dehydration ofcompounds
17a and 17b, respectively.
Our previously determined structure–activity relation-
ships (SARs) for a series of thiazolidenebenzenesulfon-
amide derivatives and docking studies have suggested
the importance ofa bulky 5-alkyl group on the thiazol-
idene ring for potent inhibitory activity against Y181C
RT.7 In addition, we found that 3-nitrobenzenesulfon-
amide derivatives (1, 2) possess potent activity against
the wild type (WT) and Y181C RTs, but that their acti-
vity against K103N RT was not satisfactory. In this
study, we have explored the SARs ofsubstituents in a
series ofthiazolidenebenzenesulofnamides, in order to
identify novel NNRTIs that are capable of inhibiting
both K103N and Y181C RT activity and HIV-1
replication (Fig. 1).
For the synthesis of2-cyanobenzenesulfonamide deriva-
tives (19, 20), we have efficiently applied palladium-cat-
alyzed cyanation ofthe aryl triflates with a combination
ofPd(dba) , dppf, Zn(CN)2 and Zn powder (Scheme
2
4).10 Mono- and di-cyano compounds (19, 20) were ob-
tained by controlling the amount ofZn(CN) . Use of
2
0.6 mol equiv ofZn(CN) , which provided 1.2 equiv of
2
cyanide anion, gave the mono-cyano compound 19
through reaction at the triflate group only. With use of
1.6 mol equiv ofZn(CN) , the major product was the
2
di-cyano compound 20.
2. Chemistry
3. Results and discussion
A series ofbenzenesulofnamide derivatives ( 1, 10a–q,
11a–g, 16a, 17a, 18a,b, 19, 20) was synthesized as shown
in Schemes 1–4. Cyanobenzenesulfonylchlorides 6n–p
were prepared from their corresponding substituted
methyl anthranilates (Scheme 1). Sandmeyer reactions
ofanthranilates 4a–c with ammonia provided saccharins
5a–c.8 Treatment ofsaccharins 5a–c with PCl5 afforded
2-cyanobenzenesulfonylchlorides 6n–p. Compound 4d
was converted to the methoxycarbonyl-substituted sul-
fonylchloride by a one-pot reaction (6q). Condensation
of2-aminothiazoles 8a–c with the substituted sulfonyl-
chlorides 6a–r, followed by selective methylation on
the thiazolidene ring ofcompounds 9a–s, afforded the
desired thiazolidenesulfonamide derivatives 1 and 10a–
r (Scheme 2).7 The demethylation ofthe methoxy deri-
Tables 1–3 summarize the inhibitory activities against
the WT, Y181C, and K103N RTs and HIV-1 replication
ofthiazolidenebenzenesulof namide derivatives carrying
different substituents on the phenyl ring, or at the 4-
position on the thiazolidene ring, or both.
We first investigated the effect on the inhibitory activity
ofsubstituents on the benzene ring, as shown in Table 1.
The RT inhibitory activity ofthe substituted benzene-
sulfonamide analogues varied considerably with differ-
ent substituents. Substituents at the meta-position were
favorable for the inhibition of RT and HIV-1 replica-
tion, and compounds that had a nitro (1) or chloro
(10c) group were most potent against all RTs. These

N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
951
NH2
N
O
S
O
R3
O
S
O
R3
H
N
R1
b
N
N
a
R3
O
S
O
N
Cl
+
S
R1
R1
S
S
R2
R2
R2
8a: R1 = Me, R2 = t-Bu
8b: R1 = Me, R2 = i-Pr
8c: R1 = Cl, R2 = i-Pr
6a: R3 = 3-NO
9a: R1 = Me, R2 = t-Bu, R3 = 3-NO
1: R1 = Me, R2 = t-Bu, R3 = 3-NO
2
10a: R1 = Me, R2 = t-Bu, R3 = 2-NO
10b: R1 = Me, R2 = t-Bu, R3 = 2-Cl
10c: R1 = Me, R2 = t-Bu, R3 = 3-Cl
10d: R1 = Me, R2 = t-Bu, R3 = 4-NO2
10e: R1 = Me, R2 = t-Bu, R3 = 4-Cl
10f: R1 = Me, R2 = t-Bu, R3 = 2-OMe
10g: R1 = Me, R2 = t-Bu, R3 = 3-OMe
10h: R1 = Me, R2 = t-Bu, R3 = 4-OMe
10i: R1 = Me, R2 = t-Bu, R3 = 2-NO2-5-Cl
10j: R1 = Me, R2 = t-Bu, R3 = 2-OMe-3-Cl
10k: R1 = Me, R2 = t-Bu, R3 = 2-OMe- 5-Cl
10l: R1 = Me, R2 = i-Pr, R3 = 2-CN-5-Cl
10m: R1 = Me, R2 = i-Pr, R3 = 2-CN-5-F
10n: R1 = Me, R2 = i-Pr, R3 = 2-CN-5-Br
10o: R1 = Cl, R2 = i-Pr, R3 = 2-OMe-5-Cl
10p: R1 = Cl, R2 = i-Pr, R3 = 2-OMe-5-Br
2
2
6b: R3 = 2-NO
9b: R1 = Me, R2 = t-Bu, R3 = 2-NO
2
2
2
6c: R3 = 2-Cl
6d: R3 = 3-Cl
6e: R3 = 4-NO
9c: R1 = Me, R2 = t-Bu, R3 = 2-Cl
9d: R1 = Me, R2 = t-Bu, R3 = 3-Cl
9e: R1 = Me, R2 = t-Bu, R3 = 4-NO2
9f: R1 = Me, R2 = t-Bu, R3 = 4-Cl
9g: R1 = Me, R2 = t-Bu, R3 = 2-OMe
9h: R1 = Me, R2 = t-Bu, R3 = 3-OMe
9i: R1 = Me, R2 = t-Bu, R3 = 4-OMe
9j: R1 = Me, R2 = t-Bu, R3 = 2-NO2-5-Cl
9k: R1 = Me, R2 = t-Bu, R3 = 2-OMe- 3-Cl
9l: R1 = Me, R2 = t-Bu, R3 = 2-OMe- 5-Cl
9m: R1 = Me, R2 = i-Pr, R3 = 2-CN-5-Cl
9n: R1 = Me, R2 = i-Pr, R3 = 2-CN-5-F
9o: R1 = Me, R2 = i-Pr, R3 = 2-CN-5-Br
9p: R1 = Cl, R2 = i-Pr, R3 = 2-OMe-5-Cl
2
6f: R3 = 4-Cl
6g: R3 = 2-OMe
6h: R3 = 3-OMe
6i: R3 = 4-OMe
6j: R3 = 2-NO2-5-Cl
6k: R3 = 2-OMe-3-Cl
6l:
R3 = 2-OMe-5-Cl
6m:
R3 = 2-OMe-5-Br
6n: R3 = 2-CN-5-Cl
6o: R3 = 2-CN-5-F
6p: R3 = 2-CN-5-Br
6q: R3 = 2-COOMe-5-CN 9q: R1 = Cl, R2 = i-Pr, R3 = 2-OMe-5-Br
6r: R3 = H
9r: R1 = Me, R2 = i-Pr, R3 = 2-COOMe-5-CN 10q: R1 = Me, R2 = i-Pr, R3 = 2-COOMe-5-CN
9s: R1 = Me, R2 = t-Bu, R3 = H
10r: R1 = Me, R2 = t-Bu, R3 = H
O
S
O
O
S
O
N
N
N
N
OMe
OH
c
S
S
10f: 2-OMe
10g: 3-OMe
10h: 4-OMe
11a: 2-OH
11b: 3-OH
11c: 4-OH
HO
O
S
MeO
O
S
N
N
N
N
c
R3
R3
R1
R1
S
O
S
O
R2
R2
11d: R1 = Me, R2 = t-Bu, R3 = 3-Cl
11e: R1 = Me R2 = t-Bu, R3 = 5-Cl
11f: R1 = Cl, R2 = i-Pr, R3 = 5-Cl
11g: R1 = Cl, R2 = i-Pr, R3 = 5-Br
10j: R1 = Me, R2 = t-Bu, R3 = 3-Cl
10k: R1 = Me R2 = t-Bu, R3 = 5-Cl
10o: R1 = Cl, R2 = i-Pr, R3 = 5-Cl
10p: R1 = Cl, R2 = i-Pr, R3 = 5-Br
Scheme 2. Reagents and conditions: (a) Py; (b) MeI, NaH/THF; (c) BBr3/CH2Cl2.
nitro and chloro substituents also resulted in more potent
anti-HIV-1 activity, and compounds 1 and 10c showed
anti-HIV-1 activity with EC50 values of0.085 and
0.20 lM, respectively. In contrast, ortho- and para-
substituted compounds were essentially inactive against
the WT RT, with an exception ofthe ortho-hydroxy
compound 11a, which showed a lower IC50 value than
that ofthe unsubstituted compound 10r. Compound
11a also exhibited moderate anti-HIV-1 activity
(EC50 = 2.3lM). Therefore, we concluded that the sub-
stitution ofa chloro or nitro group at the meta-position
or a hydroxy group at the ortho-position on the benzene
ring was favorable for RT inhibition.
6.3lM), substitution at the 2-position on a 5-chlorophen-
yl ring (11e, 12, 18a), resulted in an enhancement of
activity against the RTs. The introduction ofan amino
group at the 2-position ofthe phenyl ring ( 12) resulted
in a significant improvement ofanti-HIV-1 activity but
reduced activity against K103N and Y181C RTs, when
compared with 10c. On the other hand, compound 11e
was about 10-fold more potent against the WT and
K103N RTs, and 4-fold more potent against Y181C
RT, as compared to compound 10c. The cyano deriva-
tive 18a possessed the most potent antiviral activity
(EC50 = 0.0083lM) with a therapeutic index (TI) of
>960, but it showed no inhibition ofK103N RT.
Although the amino and cyano compounds (12, 18a)
showed less potent activity against WT RT than the hy-
droxy compound 11e, these compounds possessed more
potent anti-HIV-1 activity than 11e. We cannot explain
the exact reason for this phenomenon. One possibility,
We next focused on combinations of an ortho-substitu-
ent and a meta-chloro group, as shown in Table 2.
Although the 2-hydroxy-3-chloro derivative (11d) was
somewhat less active against the WT RT (IC50
=

952
N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
O2N
H2N
O
S
AcHN
O
S
a
b
O
S
N
N
N
N
N
N
Cl
Cl
Cl
Cl
S
O
S
O
S
O
10i
12
13
c
MsHN
O
S
N
N
S
O
14
MeOOC
HO
O
S
TfO
O
S
O
S
d
e
N
N
N
N
N
N
R3
R3
R3
R1
R1
R1
S
O
S
O
S
O
R2
R2
R2
16: R1 = Me, R2 = t-Bu, R3 = Cl
15a : R1 = Me, R2 = t-Bu, R3 = Cl
15b: R1 = Cl, R2 = i-Pr, R3 = Cl
11e : R1 = Me, R2 = t-Bu, R3 = Cl
11f: R1 = Cl, R2 = i-Pr, R3 = Cl
MeOOC
O
H2NOC
O
NC
O
S
h
f, g
N
N
N
N
N
N
S
R3
S
R3
R3
R1
R1
R1
S
O
S
O
S
O
R2
R2
R2
16: R1 = Me, R2 = t-Bu, R3 = Cl
10q: R1 = Me, R2 = i-Pr, R3 = CN
17a : R1 = Me, R2 = t-Bu, R3 = Cl
17b: R1 = Me, R2 = i-Pr, R3 = CN
18a : R1 = Me, R2 = t-Bu, R3 = Cl
18b: R1 = Me, R2 = i-Pr, R3 = CN
Scheme 3. Reagents and conditions: (a) H2, Pd–C/EtOH–THF; (b) AcCl, DMAP/Py; (c) MsCl, Et3N/THF; (d) Tf2O, 2,6-lutidine/CH2Cl2; (e) CO,
MeOH, Pd(OAc)2, dppp, Et3N/DMF; (f) NaOH aq, THF/MeOH, (g) NH4Cl, WSCÆHCl, i-Pr2NEt, HOBt/DMF; (h) POCl3/DMF.
TfO
O
S
NC
O
S
ofRT inhibition. Substitution ofthe cyano group with
an acetamide or methanesulfonamide group (13, 14),
which are known to be bioisosteres ofthe phenolic
hydroxy group, was also detrimental to inhibition with
all RTs. Thus, concerning the 5-chlorophenyl deriva-
tives, the introduction ofa hydroxy, amino, or cyano
group at the 2-position markedly enhanced the inhibi-
tion ofHIV-1 replication.
a
N
N
N
N
Cl
Cl
Cl
Cl
S
O
S
O
b
15b
19
NC
O
S
N
N
CN
Cl
S
O
We previously reported that compounds with 5-isoprop-
yl-4-methyl- and 4-chloro-5-isopropyl-substituted thia-
zolidene moieties had increased activity against the
WT and Y181C RTs.7 On the basis ofthe SARs de-
scribed in Table 2, we synthesized new compounds with
a combination of2-cyanophenyl or 2-hydroxyphenyl
moiety and 5-isopropyl-4-methyl or 4-chloro-5-isopro-
pyl thiazolidene moiety (10l–n, 11f,g, 18b, 19, 20; Table
3). Among these, compound 11f, having both 2-hydro-
xy-5-chlorophenyl and 4-chlorothiazolidene moieties,
was a more potent inhibitor ofall the RT enzymes, com-
pared to compound 11e. In addition, compound 11g
(YM-215389), which has 5-bromophenyl ring, showed
significantly more potent activity against all the RTs,
compared to compound 11f. Compound 11g also exhib-
ited strong anti-HIV-1 activity, with an EC50 value of
0.037 lM, and the TI value of 11g exceeded 680. With
the exception ofcompound 10m, the 2-cyanophenyl
derivatives (10l, 10n, and 18b), which all have 5-isoprop-
yl-4-methylthiazolidene moieties, exhibited extremely
potent anti-HIV-1 activity (EC50 = 0.0017–0.0021lM),
with TIs ranging from 6100 to >15,000. Interestingly,
20
Scheme 4. Reagents and conditions: (a) Zn(CN)2 (0.6 equiv), Zn,
Pd(dba)2, dppf/DMA; (b) Zn(CN)2 (1.6 equiv), Zn, Pd(dba)2, dppf/
DMA.
however, is that the increase in lipophilicity caused by
the substitution ofthe hydroxy group to the amino or
cyano group potentiated their cell membrane permeabil-
ity, which resulted in the increase ofanti-HIV-1 activity.
We also have to consider other possibilities, such as that
the introduction ofthese groups allow compound stabil-
ity to be maintained under the assay conditions, or that
they acquire the other anti-viral mechanism (inhibition
ofHIV-protease, integrase, RNaseH, or virus
adsorption).
On the other hand, replacement ofthe cyano group with
other electron-withdrawing groups, such as nitro (10i),
methoxycarbonyl (16) and carbamoyl (17a), led to loss

N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
Table 1. In vitro activities ofmono-substituted benzenesulfonamide derivatives
953
R
O
S
N
N
S
O
TId
a
b
c
Compounds
R
IC50 (lM)
EC50 (lM)
CC50 (lM)
WT
K103N
Y181C
1
3-NO2
2-NO2
2-Cl
0.27
>50
>10
0.30
>10
>10
50
13
0.066
36
0.085
>25
NTe
0.20
NTe
NTe
10
>25
>25
NTe
>25
NTe
NTe
>25
>25
>25
>25
>25
>25
>25
>290
—
—
10a
10b
10c
10d
10e
10f
10g
10h
10r
11a
11b
11c
>50
>10
11
>10
0.044
>10
>10
NTe
NTe
>10
5.1
3-Cl
4-NO2
4-Cl
>125
—
—
>10
>10
>50
>50
>10
>50
30
2-OMe
3-OMe
4-OMe
H
>3
>2
—
8.8
11
>10
4.9
>25
>25
2.3
—
2-OH
3-OH
4-OH
1.6
8.8
0.41
14
>11
—
>50
>10
>25
>25
>10
>10
—
a Compound concentration required to achieve 50% inhibition ofrecombinant HIV-1 RT activities.
b Compound concentration required to achieve 50% protection ofMT-4 cells from HIV-1 induced CPE, as determined by the MTT method.
c Compound concentration required to reduce the viability ofmock-infected MT-4 cells, as determined by the MTT method.
d Therapeutic index (CC50/EC50).
e NT: not tested.
Table 2. In vitro activities of2-substituted 5-chlorobenzenesulfonamide derivatives
Cl
R
O
S
HO
O
S
N
N
N
N
Cl
S
O
S
O
11d
TId
a
b
c
Compounds
R
IC50 (lM)
EC50 (lM)
CC50 (lM)
WT
K103N
Y181C
10c
10i
11d
11e
12
H
NO2
0.30
2.4
11
0.044
NTe
NTe
0.011
0.11
>50
>50
10
0.20
0.36
11
>25
22
>125
61
>2
>50
>50
1.1
6.3
>25
>25
>25
>25
>25
>25
NTe
8
OH
NH2
0.032
0.19
>50
>50
>10
>10
0.18
0.026
0.025
2.7
>960
>1000
>9
17
13
14
NHCOMe
NHSO2 Me
COOMe
CONH2
CN
>50
>50
>10
>10
>50
>25
>25
NTe
0.0083
—
—
16
17a
18a
>10
0.069
—
>960
a Compound concentration required to achieve 50% inhibition ofrecombinant HIV-1 RT activities.
b Compound concentration required to achieve 50% protection ofMT-4 cells from HIV-1 induced CPE, as determined by the MTT method.
c Compound concentration required to reduce the viability ofmock-infected MT-4 cells, as determined by the MTT method.
d Therapeutic index (CC50/EC50).
e NT: not tested.
the 2-cyanophenyl and 5-isopropyl-4-methylthiazolid-
ene derivatives, 10l and 18b (YM-228855), exhibited
strong anti-HIV-1 activity, with EC50 values of0.0017
and 0.0018 lM, respectively, both ofwhich were more
potent than that ofeafvirenz (EC 50 = 0.0027lM). The
replacement ofthe 5-chloro or 5-cyano group on the
phenyl ring with a 5-bromo group (10n) was tolerable
for anti-HIV-1 activity, but this derivative was found
to be a modest inhibitor ofK103N RT.
We also investigated the substitution ofthe methyl
group at the 4-position of 10l with a chloro group (19,
20), anticipating further increase in RT inhibitory activ-
ity and anti-HIV-1 activity. However, this attempt gave
slightly less potent compounds than their methyl coun-
terparts. Among the compounds shown in Table 3,
compound 11g was the most potent inhibitor against
the WT, Y181C, and K103N RTs, with IC50 values
of0.0043, 0.043, and 0.013 lM, respectively, and

954
N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
Table 3. In vitro activities of5-isopropylthiazolidenesulfonamide derivatives
R2
O
S
N
N
R3
R1
S
O
TId
a
b
c
Compounds
R1
R2
R3
IC50 (lM)
EC50 (lM)
CC50 (lM)
WT
K103N
Y181C
10l
10m
Me
Me
Me
Cl
CN
CN
CN
OH
OH
CN
CN
CN
Cl
0.011
0.092
0.018
0.0094
0.0043
0.012
0.0090
0.0095
0.27
5.9
>10
3.9
0.20
2.1
0.0017
0.0077
0.0021
0.027
>25
>25
>25
>25
>25
11
>15000
>3200
>12,000
>930
>680
6100
F
Br
10n
11f
0.26
Cl
Br
0.17
0.043
4.1
0.021
0.013
0.47
11g (YM-215389)
18b (YM-228855)
Cl
0.037
Me
Cl
CN
Cl
0.0018
0.0047
0.0036
0.085
19
20
1
3.7
3.0
0.091
0.21
3.8
810
6100
Cl
CN
22
13
0.066
0.13
0.0040
>25
24
>290
500
3200
2
0.077
0.0069
6.9
0.021
0.048
0.0027
Efavirenz (3)
8.5
a Compound concentration required to achieve 50% inhibition ofrecombinant HIV-1 RT activities.
b Compound concentration required to achieve 50% protection ofMT-4 cells from HIV-1 induced CPE, as determined by the MTT method.
c Compound concentration required to reduce the viability ofmock-infected MT-4 cells, as determined by the MTT method.
d Therapeutic index (CC50/EC50).
accompanying potent anti-HIV-1 activity (EC50: 0.037
lM). Consequently, the discovery ofan effective comp-
ound against the WT, K103N, and Y181C mutant RTs
as well as HIV-1 replication has been made by the explo-
ration ofthe optimum combination ofsubstituents on
both the thiazole and phenyl rings. This compound is
referred to as YM-215389. Further improvement of
anti-HIV-1 properties in this series ofcompounds and
their potential use as anti-HIV-1 agents will be reported
in due course.
5. Experimental
5.1. Chemistry
Melting points were determined on a Yanaco micro-
melting apparatus or Buchi B-545 melting point appara-
¨
tus and are uncorrected. Proton magnetic resonance (1H
NMR) spectra were obtained in CDCl3 or dimethylsulf-
oxide-d6 (DMSO-d6) using a JEOL JNM-EX90, JNM-
EX400, JNM-GX500, or JNM-A500 spectrometer.
Chemical shifts were expressed in d (ppm) values with
tetramethylsilane as an internal standard (in NMR
description, s: singlet, d: doublet, t: triplet, m: multiplet,
br: broad peak). Mass spectra (MS) were recorded on a
JEOL JMS-DX300 or a HITACHI M-80 mass spec-
trometer. Elemental analysis was carried out on Yanaco
MT-3 or MT-5 CHN analyzer and a Yokogawa
IC7000S Ion Chromatoanalyzer. Chromatographic sep-
arations were performed using a silica gel column
(Merck Kieselgel 60). Analytical thin-layer chromato-
graphy (TLC) was carried out on precoated glass plates
(Merck Kieselgel 60F254).
4. Conclusion
In this paper, the synthesis and SARs ofthiazolidene-
benzenesulfonamide derivatives have been described.
An interesting aspect ofthis study is that both potency
and spectrum ofthiazolidenebenzenesulofnamides var-
ied, depending on the number and position ofthe sub-
stituents on the phenyl ring. It was found that the
combination ofa hydroxy or cyano group at the 2-posi-
tion on the phenyl ring with a 5-isopropylthiazolidene
ring improved the inhibitory activities against RT en-
zymes and HIV-1 replication. The cyano derivatives
(10l and 18b) showed extremely potent anti-HIV-1 activ-
ity, with EC50 values of0.0017 and 0.0018 lM, respec-
tively. These values were significantly better than that
ofeafvirenz ( 3). However, the activity ofthe cyano
derivatives against the K103N mutant RT was insuffi-
cient. Compound 11g (YM-215389) possessed the most
potent activity against the WT, K103N, and Y181C
RTs, with IC50 values of0.0043, 0.043, and 0.013 lM,
respectively. This compound also strongly inhibited
HIV-1 replication in cell cultures (EC50 = 0.037 lM).
Because oftheir excellent potency, these thiazolidene-
benzenesulfonamide derivatives may have potential
and should be further pursued as next-generation
NNRTIs.
The following known materials were prepared as de-
scribed in the literature: (6j)11 or obtained from com-
mercial suppliers (6a–i, 6r). And the preparation of 1,
8a–c, 9a was described in our previous report.7
5.1.1. 6-Chloro-1,2-benzisothiazol-3(2H)-one-1,1-dioxide
(5a). To solution of 4a (7.42 g, 40 mmol) in acetic acid
(45 mL) and concentrated hydrochloric acid (90 mL)
was added sodium nitrite (2.90 g, 42 mmol) in water
(12 mL) at ꢀ5 ꢁC and the solution was stirred at
ꢀ5 ꢁC for 1 h. To a mixture of copper(II) chloride
(5.38 g, 40 mmol) and copper(I) chloride (3.96 g,
40 mmol) in acetic acid (120 mL) and concentrated
hydrochloric acid (15 mL), SO2 gas was bubbled at
ꢀ5 ꢁC. The suspension ofprepared diazonium salt was

N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
955
added dropwise to the mixture at ꢀ10 ꢁC and stirred at
room temperature for 3 h. The reaction mixture was
poured into water and 28% aqueous ammonia solution
(500 mL) was added under ice-bath cooling. The result-
ing mixture was extracted with chloroform and washed
with saturated aqueous sodium hydrogen carbonate
solution. The organic layer was dried over anhy-
drous sodium sulfate and solvent was removed under
reduced pressure to give 5a (3.90 g, 45%) as a color-
less powder. 1H NMR (DMSO-d6) d: 7.97 (3H, m,
benzene), 8.43 (1H, br s, NH); FAB-MS m/z: 218
(M++1).
dried under reduced pressure to give 6q (19.0 g, quanti-
tative) as a colorless powder. H NMR (DMSO-d6) d:
3.75 (3H, s, CH3 ofCOOMe), 7.52 (1H, d, J = 8.1 Hz,
benzene), 7.87 (1H, dd, J = 1.5, 8.1 Hz, benzene), 8.03
(1H, d, J = 1.5 Hz, benzene); EI-MS m/z: 259 (M+).
1
5.1.8. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-2-nitro-
benzenesulfonamide (9b). A solution of 8a. hydrochloride
(8.00 g, 38.7 mmol) in pyridine (100 mL) was added 6b
(10.3 g, 46.4 mmol) and the solution was stirred at room
temperature for 12 h. The reaction mixture was poured
into water. The resulting mixture was extracted with
ethyl acetate and washed with saturated aqueous so-
dium hydrogen carbonate solution, 1 M hydrochloric
acid and brine. The organic layer was dried over anhy-
drous sodium sulfate and solvent was removed under re-
duced pressure. The residue was purified by silica gel
column chromatography (ethyl acetate–hexane) to give
9b (10.89 g, 79%) as an orange solid. 1H NMR
(DMSO-d6) d: 1.30 (9H, s, t-Bu), 2.18 (3H, s, 4-Me),
7.80 (2H, m, benzene), 7.87 (1H, m, benzene), 8.03
(1H, m, benzene), 12.65 (1H, br s, NH); FAB-MS m/z:
356 (M++1).
The following compounds were obtained in the same
manner.
5.1.2. 6-Fluoro-1,2-benzisothiazol-3(2H)-one-1,1-dioxide
1
(5b). 31% yield; H NMR (DMSO-d6) d: 7.57 (1H, m,
benzene), 7.82 (2H, m, benzene), 7.90 (1H, m, NH);
FAB-MS m/z: 200 (Mꢀꢀ1).
5.1.3. 6-Bromo-1,2-benzisothiazol-3(2H)-one-1,1-dioxide
1
(5c). 56% yield; H NMR (DMSO-d6) d: 7.80 (1H, br s,
NH), 7.87 (1H, d, J = 8.3 Hz, benzene), 8.09 (1H, dd,
J = 1.5, 8.3 Hz, benzene), 8.51 (1H, d, J = 1.5 Hz, benz-
ene); FAB-MS m/z: 263 (M++1).
The following compounds were obtained in the same
manner.
5.1.4. 5-Chloro-2-cyanobenzenesulfonyl chloride (6n). A
mixture of 5a (3.90 g, 18.0 mmol) and phosphorus pen-
tachloride (22.4 g, 90.0 mmol) was heated to 120 ꢁC and
stirred for 7 h. The reaction mixture was poured into ice-
water. The resulting mixture was extracted with ethyl
acetate and washed with saturated aqueous sodium
hydrogen carbonate solution. The organic layer was
dried over anhydrous sodium sulfate and solvent was re-
moved under reduced pressure to give 6n (2.89 g, 68%)
as a pale yellow powder. This crude product was used
for next step without further purification.
5.1.9. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-2-chlo-
robenzenesulfonamide (9c). 34% yield; 1H NMR
(DMSO-d6) d: 1.30 (9H, s, CH3 of t-Bu), 2.16 (3H, s,
4-Me), 8.03 (2H, d, J = 8.8 Hz, benzene), 8.36 (2H, d,
J = 8.8 Hz, benzene), 12.58 (1H, br s, NH); FAB-MS
m/z: 345 (M++1).
5.1.10. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-3-chlo-
robenzenesulfonamide (9d). 99% yield; 1H NMR
(DMSO-d6) d: 1.29 (9H, s, CH3 of t-Bu), 2.16 (3H, s,
4-Me), 7.58 (1H, t, J = 7.8 Hz, benzene), 7.67 (1H, br
d, J = 7.8 Hz, benzene), 7.74 (1H, br s, benzene), 7.75
(1H, br d, J = 7.8 Hz, benzene), 12.46 (1H, br s, NH);
FAB-MS m/z: 345 (M++1).
The following compounds were obtained in the same
manner.
5.1.5. 5-Fluoro-2-cyanobenzenesulfonyl chloride (6o).
54% yield; 1H NMR (DMSO-d6) d: 7.40 (1H, dt,
J = 3.6, 11.2 Hz, benzene), 7.59 (1H, dd, J = 3.6,
12.0 Hz, benzene), 7.92 (1H, dd, J = 6.8, 11.2 Hz, ben-
zene); EI-MS m/z: 219 (M+).
5.1.11. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-4-nitro-
benzenesulfonamide (9e). 85% yield; H NMR (DMSO-
d6) d: 1.30 (9H, s, CH3 of t-Bu), 2.16 (3H, s, 4-Me),
8.03 (2H, d, J = 8.8 Hz, benzene), 8.36 (2H, d,
J = 8.8 Hz, benzene), 12.58 (1H, br s, NH); FAB-MS
m/z: 356 (M++1).
1
5.1.6. 5-Bromo-2-cyanobenzenesulfonyl chloride (6p).
Without isolation.
5.1.12. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-4-chlo-
robenzenesulfonamide (9f). 78% yield; 1H NMR
(DMSO-d6) d: 1.29 (9H, s, CH3 of t-Bu), 2.15 (3H, s,
4-Me), 7.60 (2H, d, J = 7.5 Hz, benzene), 7.78 (2H, d,
J = 7.5 Hz, benzene), 12.42 (1H, br s, NH); FAB-MS
m/z: 345 (M++1).
5.1.7. Methyl 2-chlorosulfonyl-4-cyanobenzoate (6q). So-
dium nitrite (5.10 g, 73.5 mmol) in water (25 mL) was
added to solution of 4d (12.3 g, 70 mmol) in concen-
trated hydrochloric acid (120 mL) at ꢀ5 ꢁC and the
solution was stirred at ꢀ5 ꢁC for 1.5 h. To a mixture
ofcopper(II) chloride dihydrate (2.60 g, 15.0 mmol) in
acetic acid (200 mL), SO2 gas was bubbled at ꢀ5 ꢁC.
The suspension ofprepared diazonium salt was added
dropwise to the mixture at ꢀ10 ꢁC and stirred at room
temperature for 3 h. The reaction mixture was poured
into water. The resulting precipitate was collected by fil-
tration and washed with water. The precipitate was
5.1.13. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-2-meth-
oxybenzenesulfonamide (9g). 50% yield; 1H NMR
(DMSO-d6) d: 1.31 (9H, s, CH3 of t-Bu), 2.15 (3H, s,
4-Me), 3.73 (3H, s, MeO), 7.03 (1H, t, J = 7.5 Hz, benz-
ene), 7.13 (1H, d, J = 7.5 Hz, benzene), 7.50 (2H, m,
benzene), 12.14 (1H, br s, NH); FAB-MS m/z: 341
(M++1).

956
N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
5.1.14. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-3-meth-
oxybenzenesulfonamide (9h). 61% yield; 1H NMR
(DMSO-d6) d: 1.29 (9H, s, CH3 of t-Bu), 1.98 (3H, s,
4-Me), 3.80 (3H, s, MeO), 7.14 (1H, dd, J = 2.5,
8.3 Hz, benzene), 7.26 (1H, t, J = 2.5 Hz, benzene),
7.36 (1H, br d, J = 7.8 Hz, benzene), 7.45 (1H, t,
J = 7.8 Hz, benzene), 12.34 (1H, br s, benzene); FAB-
MS m/z: 341 (M++1).
d, J = 8.8 Hz, benzene), 7.46 (1H, dd, J = 2.4, 8.8 Hz,
benzene), 7.94 (1H, d, J = 2.4 Hz, benzene); FAB-MS
m/z: 381 (M++1).
5.1.23.
N-(4-Chloro-5-isopropyl-1,3-thiazol-2-yl)-5-
bromo-2-methoxybenzenesulfonamide (9q). 59% yield;.
1H NMR (DMSO-d6) d: 1.20 (6H, d, J = 6.8 Hz, CH3
of i-Pr), 3.12 (1H, heptet, J = 6.8 Hz, CH of i-Pr), 3.76
(3H, s, MeO), 7.14 (1H, d, J = 9.0 Hz, benzene), 7.79
(1H, dd, J = 2.6, 9.0 Hz, benzene), 7.87 (1H, d,
J = 2.6 Hz, benzene); FAB-MS m/z: 427 (M++1).
5.1.15. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-4-meth-
oxybenzenesulfonamide (9i). Without isolation.
5.1.16.
N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-5-
5.1.24. Methyl 4-cyano-2-{[(5-isopropyl-4-methyl-1,3-
thiazol-2-yl)amino]sulfonyl}benzoate (9r). 68% yield; H
chloro-2-nitrobenzenesulfonamide (9j). 41% yield; 1H
NMR (DMSO-d6) d: 1.30 (9H, s, CH3 of t-Bu), 2.20
(3H, s, 4-Me), 7.91 (1H, dd, J = 2.0, 8.3 Hz, benzene),
7.98 (1H, d, J = 2.0 Hz, benzene), 7.99 (1H, d,
J = 8.8 Hz, benzene), 12.76 (1H, br s, NH); FAB-MS
m/z: 390 (M++1).
1
NMR (DMSO-d6) d: 1.15 (6H, d, J = 6.9 Hz, CH3 of
i-Pr), 2.07 (3H, s, 4-Me), 3.11 (1H, heptet, J = 6.9 Hz,
CH of i-Pr), 3.80 (3H, s, CH3 ofCOOMe), 7.78 (1H,
d, J = 7.8 Hz, benzene), 8.14 (1H, dd, J = 1.4, 7.8 Hz,
benzene), 8.28 (1H, d, J = 1.4 Hz, benzene), 12.59 (1H,
br s, NH); FAB-MS m/z: 380 (M++1).
5.1.17. N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-3-
chloro-2-methoxybenzenesulfonamide (9k). Without
isolation.
5.1.25.
N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)benz-
1
enesulfonamide (9s). 61% yield; H NMR (DMSO-d6)
d: 1.28 (9H, s, CH3 of t-Bu), 2.14 (3H, s, 4-Me), 7.54
(3H, m, benzene), 7.78 (2H, m, benzene), 12.32 (1H,
br s, NH); FAB-MS m/z: 311 (M++1).
5.1.18.
N-(5-tert-Butyl-4-methyl-1,3-thiazol-2-yl)-5-
1
chloro-2-methoxybenzenesulfonamide (9l). 94% yield; H
NMR (DMSO-d6) d: 1.32 (9H, s, CH3 of t-Bu), 2.17
(3H, s, 4-Me), 3.74 (3H, s, MeO), 7.18 (1H, d,
J = 8.8 Hz, benzene), 7.59 (1H, dd, J = 2.9, 8.8 Hz, benz-
ene), 7.73 (1H, d, J = 2.9 Hz, benzene), 12.30 (1H, br s,
NH); FAB-MS m/z: 375 (M++1).
5.1.26. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-2-nitrobenzenesulfonamide (10a). To a solution
of 9b (10.89 g, 30.6 mmol) in tetrahydrofuran (100 mL)
was added sodium hydride (60% dispersion in mineral
oil: 1.47 g, 36.8 mmol) and iodomethane (5.7 mL,
91.8 mmol) under ice-bath cooling. The solution was
warmed to room temperature and stirred for 12 h. The
reaction mixture was poured into ice-water and ex-
tracted with ethyl acetate. The organic layer was washed
with brine, and then dried over anhydrous sodium sul-
fate. The solvent was removed under reduced pressure
and the residue was purified by silica gel column chro-
matography (chloroform) and recrystalized from metha-
nol to give 10a (7.01 g, 62%) as a yellow powder. Mp
5.1.19.
5-Chloro-2-cyano-N-(5-isopropyl-4-methyl-1,3-
thiazol-2-yl)benzenesulfonamide (9m). 13% yield. 1H
NMR (DMSO-d6) d: 1.14 (6H, d, J = 6.8 Hz, CH3 of
i-Pr), 2.06 (3H, s, 4-Me), 3.11 (1H, heptet, J = 6.8 Hz,
CH of i-Pr), 7.88 (1H, dd, J = 2.5, 8.3 Hz, benzene),
8.00 (1H, d, J = 2.5 Hz, benzene), 8.09 (1H, d,
J = 8.3 Hz, benzene), 12.83 (1H, br s, NH); FAB-MS
m/z: 356 (M++1).
1
5.1.20.
5-Fluoro-2-cyano-N-(5-isopropyl-4-methyl-1,3-
138–139 ꢁC. H NMR (CDCl3) d: 1.36 (9H, s, CH3 of
thiazol-2-yl)benzenesulfonamide (9n). 20% yield; 1H
NMR (DMSO-d6) d: 1.14 (6H, d, J = 6.9 Hz, CH3 of
i-Pr), 2.06 (3H, s, 4-Me), 3.11 (1H, heptet, J = 6.9 Hz,
CH of i-Pr), 7.67 (1H, dt, J = 1.9, 8.8 Hz, benzene),
7.82 (1H, dd, J = 1.9, 8.8 Hz, benzene), 8.16 (1H, dd,
J = 5.4, 8.8 Hz, benzene), 12.82 (1H, br s, NH); FAB-
MS m/z: 340 (M++1).
t-Bu), 2.28 (3H, s, 4-Me), 3.45 (3H, s, 3-Me), 7.61 (3H,
m, benzene), 8.25 (1H, m, benzene); FAB-MS m/z: 370
(M++1). Anal. Calcd for C15H19N3O4S2: C, 48.76; H,
5.18; N, 11.37; S, 17.36. Found: C, 48.76; H, 4.99; N,
11.38; S, 17.69.
The following compounds were obtained in the same
manner.
5.1.21. 5-Bromo-2-cyano-N-(5-isopropyl-4-methyl-1,3-
thiazol-2-yl)benzenesulfonamide (9o). 27% yield from
8b; H NMR (DMSO-d6) d: 1.14 (6H, d, J = 6.8 Hz,
CH3 of i-Pr), 2.06 (3H, s, 4-Me), 3.11 (1H, heptet,
J = 6.8 Hz, CH of i-Pr), 8.01 (2H, m, benzene), 8.13
(1H, d, J = 1.4 Hz, benzene), 12.84 (1H, br s, NH).;
FAB-MS m/z: 400 (M++1).
5.1.27. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-2-chlorobenzenesulfonamide (10b). 86% yield;
mp 153–155 ꢁC (ethyl acetate–benzene).1H NMR
(CDCl3) d: 1.33 (9H, s, CH3 of t-Bu), 2.27 (3H, s, 4-
Me), 3.47 (3H, s, 3-Me), 7.46 (3H, m, benzene), 8.23
(1H, m, benzene); FAB-MS m/z: 359 (M++1). Anal.
Calcd for C15H19ClN2O2S2: C, 50.20; H, 5.34; N, 7.81;
S, 17.87; Cl, 9.88. Found: C, 50.15; H, 5.17; N, 7.82;
S, 17.80; Cl, 9.75.
1
5.1.22.
N-(4-Chloro-5-isopropyl-1,3-thiazol-2-yl)-5-
chloro-2-methoxybenzenesulfonamide (9p). 22% yield;
1H NMR (CDCl3) d: 1.25 (6H, d, J = 7.0 Hz, CH3 of
i-Pr), 2.67 (1H, br s, NH), 3.16 (1H, heptet,
J = 7.0 Hz, CH of i-Pr), 3.87 (3H, s, MeO), 6.94 (1H,
5.1.28. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-3-chlorobenzenesulfonamide (10c). 90% yield;

N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
957
1
mp 138–139 ꢁC (chloroform). H NMR (DMSO-d6) d:
5.1.34. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-5-chloro-2-nitrobenzenesulfonamide (10i). 49%
yield; mp 204–205 ꢁC (acetonitrile). H NMR (DMSO-
d6) d: 1.33 (9H, s, CH3 of t-Bu), 2.31 (3H, s, 4-Me),
3.45 (3H, s, 3-Me), 7.91 (1H, dd, J = 1.9, 8.3 Hz, benz-
ene), 7.98 (1H, d, J = 8.3 Hz, benzene), 8.01 (1H, d,
J = 1.9 Hz, benzene); FAB-MS m/z: 404 (M++1). Anal.
Calcd for C15H18ClN3O4S2: C, 44.60; H, 4.49; N,
10.40; S, 15.88; Cl, 8.78. Found: C, 44.44; H, 4.41; N,
10.34; S, 16.03; Cl, 8.82.
1.31 (9H, s, CH3 of t-Bu), 2.28 (3H, s, 4-Me), 3.42
(3H, s, 3-Me), 7.57 (1H, dd, J = 7.8, 8.3 Hz, benzene),
7.66 (1H, ddd, J = 1.0, 2.0, 8.3 Hz, benzene), 7.79 (1H,
br s, benzene), 7.80 (1H, br d, J = 7.8 Hz, benzene);
FAB-MS m/z: 359 (M++1). Anal. Calcd for
C15H19ClN2O2S2Cl: C, 50.20; H, 5.34; N, 7.81; S,
17.87; Cl, 9.88. Found: C, 50.01; H, 5.26; N, 7.76; S,
18.00; Cl, 10.04.
1
5.1.29. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-4-nitrobenzenesulfonamide (10d). 50% yield; mp
184–185 ꢁC (ethyl acetate–hexane). H NMR (CDCl3)
5.1.35. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-3-chloro-2-methoxybenzenesulfonamide
1
(10j).
1
d: 1.37 (9H, s, CH3 of t-Bu), 2.27 (3H, s, 4-Me), 3.46
(3H, s, 3-Me), 8.15 (2H, dt, J = 2.4, 8.8 Hz, benzene),
8.29 (2H, dt, J = 2.4, 8.8 Hz, benzene); FAB-MS m/z:
370 (M++1). Anal. Calcd for C15H19N3O4S2: C, 48.76;
H, 5.18; N, 11.37; S, 17.36. Found: C, 48.70; H, 4.98;
N, 11.51; S, 17.43.
60% yield from 8a; H NMR (DMSO-d6) d: 1.22 (9H,
s, CH3 of t-Bu), 2.22 (3H, s, 4-Me), 3.35 (3H, s, 3-
Me), 3.73 (3H, s, MeO), 7.38 (1H, dd, J = 7.8, 8.3 Hz,
benzene), 7.77 (1H, dd, J = 1.5, 8.3 Hz, benzene), 7.88
(1H, dd, J = 1.5, 7.8 Hz, benzene); FAB-MS m/z: 388
(M++1).
5.1.30. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-4-chlorobenzenesulfonamide (10e). 50% yield;
mp 157–158 ꢁC (ethyl acetate–hexane). 1H NMR
(CDCl3) d: 1.36 (9H, s, CH3 of t-Bu), 2.26 (3H, s, 4-
Me), 3.43 (3H, s, 3-Me), 7.41 (2H, dt, J = 2.4, 8.8 Hz,
benzene), 7.91 (2H, dt, J = 2.4, 8.8 Hz, benzene); FAB-
MS m/z: 359 (M++1). Anal. Calcd for C15H19ClN2O2S2:
C, 50.20; H, 5.34; N, 7.81; S, 17.87; Cl, 9.88. Found: C,
50.01; H, 5.10; N, 7.87; S, 17.86; Cl, 9.89.
5.1.36. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-5-chloro-2-methoxybenzenesulfonamide (10k).
81% yield; H NMR (DMSO-d6) d: 1.34 (9H, s, CH3
of t-Bu), 2.29 (3H, s, 4-Me), 3.38 (3H, s, 3-Me), 3.73
(3H, s, MeO), 7.19 (1H, d, J = 8.8 Hz, benzene), 7.59
(1H, dd, J = 2.5, 8.8 Hz, benzene), 7.73 (1H, d,
J = 2.5 Hz, benzene); FAB-MS m/z: 388 (M++1).
1
5.1.37.
5-Chloro-2-cyano-N-(5-isopropyl-3,4-dimethyl-
1,3-thiazol-2(3H)-ylidene)benzenesulfonamide (10l). 63%
yield; mp 180–182 ꢁC. 1H NMR (DMSO-d6) d: 1.15
(6H, d, J = 6.9 Hz, CH3 of i-Pr), 2.19 (3H, s, 4-Me),
3.22 (1H, heptet, J = 6.9 Hz, CH of i-Pr), 3.48 (3H, s,
3-Me), 7.88 (1H, dd, J = 1.9, 8.3 Hz, benzene), 8.02
(1H, d, J = 1.9 Hz, benzene), 8.10 (1H, d, J = 8.3 Hz,
benzene); FAB-MS m/z: 370 (M++1). Anal. Calcd for
C15H16ClN3O2S2: C, 48.71; H, 4.36; N, 11.36; S, 17.34;
Cl, 9.58. Found: C, 48.43; H, 4.24; N, 11.33; S, 17.45;
Cl, 9.38.
5.1.31. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-2-methoxybenzenesulfonamide (10f). 20% yield;
mp 197–198 ꢁC (diethyl ether–hexane). 1H NMR
(DMSO-d6) d: 1.33 (9H, s, CH3 of t-Bu), 2.28 (3H, s,
4-Me), 3.37 (3H, s, 3-Me), 3.73 (3H, s, MeO), 7.03
(1H, t, J = 7.9 Hz, benzene), 7.14 (1H, d, J = 8.3 Hz,
benzene), 7.52 (1H, dt, J = 1.5, 7.9 Hz, benzene), 7.79
(1H, dd, J = 1.5 Hz, benzene); FAB-MS m/z: 355
(M++1). Anal. Calcd for C16H22N2O3S2Æ0.1CHCl3: C,
52.77; H, 6.08; N, 7.65; S, 17.50; Cl, 2.90. Found: C,
52.84; H, 5.98; N, 7.59; S, 17.56; Cl, 2.50.
5.1.38.
1,3-thiazol-2(3H)-ylidene)benzenesulfonamide
5-Fluoro-2-cyano-N-(5-isopropyl-3,4-dimethyl-
(10m).
1
5.1.32. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-3-methoxybenzenesulfonamide (10g). 76% yield;
81% yield; mp 184–186 ꢁC (methanol–chloroform). H
NMR (DMSO-d6) d: 1.14 (6H, d, J = 6.8 Hz, CH3 of
i-Pr), 2.19 (3H, s, 4-Me), 3.20 (1H, heptet, J = 6.8 Hz,
CH of i-Pr), 3.49 (3H, s, 3-Me), 7.66 (1H, dt, J = 2.9,
8.3 Hz, benzene), 7.85 (1H, dd, J = 2.5, 8.3 Hz,
benzene), 8.16 (1H, dd, J = 5.3, 8.8 Hz, benzene);
FAB-MS m/z: 354 (M++1). Anal. Calcd for C15H16-
FN3O2S2: C, 50.97; H, 4.56; N, 11.89; S, 18.15; F,
5.38. Found: C, 51.05; H, 4.60; N, 11.76; S, 18.09; F,
5.63.
1
mp 192–193 ꢁC (diethyl ether). H NMR (DMSO-d6) d
1.31 (9H, s, CH3 of t-Bu), 2.27 (3H, s, 4-Me), 3.40
(3H, s, 3-Me), 3.81 (3H, s, MeO), 7.14 (1H, ddd,
J = 1.0, 2.5, 7.8 Hz, benzene), 7.29 (1H, t, J = 2.5 Hz,
benzene), 7.39 (1H, br d, J = 7.8 Hz, benzene), 7.44
(1H, t, J = 7.8 Hz, benzene); FAB-MS m/z: 355
(M++1). Anal. Calcd for C16H22N2O3S2: C, 54.21; H,
6.26; N, 7.90; S, 18.09. Found: C, 54.31; H, 6.25; N,
7.86; S, 18.17.
5.1.39.
5-Bromo-2-cyano-N-(5-isopropyl-3,4-dimethyl-
(10n).
5.1.33. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-4-methoxybenzenesulfonamide (10h). 81% yield
from 8a; mp 181–183 ꢁC (ethyl acetate–hexane). 1H
NMR (CDCl3) d: 1.34 (9H, s, CH3 of t-Bu), 2.24 (3H,
s, 4-Me), 3.42 (3H, s, 3-Me), 3.87 (3H, s, MeO), 6.92
(2H, d, J = 8.6 Hz, benzene), 7.91 (2H, d, J = 8.6 Hz,
benzene); FAB-MS m/z: 355 (M++1). Anal. Calcd for
C16H22N2O3S2: C, 54.21; H, 6.26; N, 7.90; S, 18.09.
Found: C, 54.23; H, 6.18; N, 7.89; S, 17.98.
1,3-thiazol-2(3H)-ylidene)benzenesulfonamide
56% yield; mp 179–181 ꢁC (isopropanol). 1H NMR
(DMSO-d6) d: 1.15 (6H, d, J = 6.9 Hz, CH3 of i-Pr),
2.18 (3H, s, 4-Me), 3.22 (1H, heptet, J = 6.9 Hz, CH
of i-Pr), 3.48 (3H, s, 3-Me), 8.01 (2H, m, benzene),
8.14 (1H, d, J = 1.0 Hz, benzene); FAB-MS m/z: 414
(M++1). Anal. Calcd for C15H16BrN3O2S2: C, 43.48;
H, 3.89; N, 10.14; S, 15.48; Br, 19.28. Found: C,
43.50; H, 3.70; N, 10.07; S, 15.51; Br, 18.91.

958
N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
5.1.40. 5-Chloro-N-(4-chloro-5-isopropyl-3-methyl-1,
3-thiazol-2(3H)-ylidene)-2-methoxybenzenesulfonamide
(10o). 60% yield; H NMR (DMSO-d6) d: 1.23 (6H, d,
The following compounds were obtained in the same
manner.
1
J = 6.8 Hz, CH3 of i-Pr), 3.20 (1H, heptet, J = 6.8 Hz,
CH of i-Pr), 3.43 (3H, s, 3-Me), 3.74 (3H, s, MeO),
7.22 (1H, d, J = 8.8 Hz, benzene), 7.63 (1H, dd,
J = 2.5, 8.8 Hz, benzene), 7.76 (1H, d, J = 2.4 Hz, benz-
ene); FAB-MS m/z: 395 (M++1).
5.1.45. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-3-hydroxybenzenesulfonamide (11b). 87% yield;
mp 145–146 ꢁC (diethyl ether–hexane). 1H NMR
(DMSO-d6) d: 1.32 (9H, s, CH3 of t-Bu), 2.27 (3H, s,
4-Me), 3.38 (3H, s, 3-Me), 6.88 (2H, m, benzene), 7.36
(1H, dt, J = 1.4, 7.3 Hz, benzene), 7.70 (1H, dd,
J = 1.4, 7.8 Hz, benzene), 10.12 (1H, s, OH); FAB-MS
m/z: 341 (M++1). Anal. Calcd for C15H20N2O3S2: C,
52.92; H, 5.92; N, 8.23; S, 18.84. Found: C, 52.78; H,
5.70; N, 8.16; S, 18.84.
5.1.41.
5-Bromo-N-(4-chloro-5-isopropyl-3-methyl-1,
3-thiazol-2(3H)-ylidene)-2-methoxybenzenesulfonamide
(10p). 73% yield; 1H NMR (CDCl3) d: 1.26 (6H, d,
J = 6.8 Hz, CH3 of i-Pr), 3.22 (1H, heptet, J = 6.8 Hz,
CH of i-Pr), 3.51 (3H, s, 3-Me), 3.82 (3H, s, MeO),
6.85 (1H, d, J = 8.8 Hz, benzene), 7.55 (1H, dd,
J = 2.4, 8.8 Hz, benzene), 8.16 (1H, d, J = 2.4 Hz, benz-
ene); FAB-MS m/z: 439 (M++1).
5.1.46. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-4-hydroxybenzenesulfonamide (11c). 60% yield;
mp 234–236 ꢁC (ethyl acetate–hexane). 1H NMR
(DMSO-d6) d: 1.31 (9H, s, CH3 of t-Bu), 1.99 (3H, s,
4-Me), 3.37 (3H, s, 3-Me), 6.84 (2H, d, J = 8.6 Hz, ben-
zene), 7.63 (1H, d, J = 8.6 Hz, benzene), 10.22 (1H, br s,
OH); FAB-MS m/z: 341 (M++1). Anal. Calcd for
C15H20N2O3S2: C, 52.92; H, 5.92; N, 8.23; S, 18.84.
Found: C, 52.68; H, 5.70; N, 8.02; S, 18.45.
5.1.42. Methyl 4-cyano-2-{[(5-isopropyl-3,4-dimethyl-1,3-
thiazol-2(3H)-ylidene)amino]sulfonyl}benzoate
(10q).
37% yield; mp 224–226 ꢁC (isopropanol–diethyl
ether). 1H NMR (DMSO-d6) d: 1.15 (6H, d, J =
6.9 Hz, CH3 of i-Pr), 3.22 (1H, heptet, J = 6.9 Hz,
CH of i-Pr), 2.19 (3H, s, 4-Me), 3.44 (3H, s, 3-Me),
3.81 (3H, s, MeO), 7.78 (1H, d, J = 7.8 Hz, benzene),
8.14 (1H, dd, J = 1.5, 7.8 Hz, benzene), 8.33 (1H, d,
J = 1.5 Hz, benzene); FAB-MS m/z: 394 (M++1).
Anal. Calcd for C17H19N3O4S2: C, 51.89; H, 4.87; N,
10.68; S, 16.30. Found: C, 51.65; H, 4.79; N, 10.72; S,
16.03.
5.1.47. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-3-chloro-2-hydroxybenzenesulfonamide
(11d).
64% yield; mp 147–148 ꢁC (methanol). 1H NMR
(DMSO-d6) d: 1.32 (9H, s, CH3 of t-Bu), 2.29 (3H, s,
4-Me), 3.41 (3H, s, 3-Me), 6.98 (1H, t, J = 7.8 Hz, benz-
ene), 7.59 (1H, dd, J = 1.5, 7.8 Hz, benzene), 7.69 (1H,
dd, J = 1.5, 7.8 Hz, benzene), 9.93 (1H, br s, OH);
FAB-MS m/z: 375 (M++1). Anal. Calcd for
C15H19ClN2O3S2: C, 48.05; H, 5.11; N, 7.47; S, 17.11;
Cl, 9.46. Found: C, 47.94; H, 5.07; N, 7.32; S, 17.16;
Cl, 9.38.
5.1.43. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)benzenesulfonamide (10r). 95% yield; mp 188–
189 ꢁC (ethyl acetate–hexane).1H NMR (DMSO-d6) d:
1.31 (9H, s, CH3 of t-Bu), 2.26 (3H, s, 4-Me), 3.40
(3H, s, 3-Me), 7.54 (3H, m, benzene), 7.82 (2H, m, benz-
ene); FAB-MS m/z: 325 (M++1). Anal. Calcd for
C15H20N2O2S2: C, 55.53; H, 6.21; N, 8.63; S, 19.77.
Found: C, 55.38; H, 6.32; N, 8.55; S, 19.79.
5.1.48. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-5-chloro-2-hydroxybenzenesulfonamide
(11e).
1
71% yield; mp 147–149 ꢁC (ethyl acetate–hexane). H
NMR (DMSO-d6) d: 1.32 (9H, s, CH3 of t-Bu), 2.28
(3H, s, 4-Me), 3.38 (3H, s, 3-Me), 6.92 (1H, d,
J = 8.7 Hz, benzene), 7.41 (1H, dd, J = 3.0, 8.7 Hz, benz-
ene), 7.65 (1H, d, J = 3.0 Hz, benzene), 10.56 (1H, br s,
OH); FAB-MS m/z: 375 (M++1). Anal. Calcd for
C15H19ClN2O3S2: C, 48.05; H, 5.11; N, 7.47; S, 17.11;
Cl, 9.46. Found: C, 48.04; H, 5.09; N, 7.61; S, 17.24;
Cl, 9.23.
5.1.44. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-2-hydroxybenzenesulfonamide (11a). Under
argon atmosphere, boron tribromide (0.17 mL,
1.71 mmol) was added dropwise to a solution of 10f
(200 mg, 0.57 mmol) in dichloromethane (20 mL) at
ꢀ78 ꢁC and stirred at the same temperature for
30 min. The mixture was warmed to room temperature
and stirred for 30 min. The reaction mixture was poured
into saturated aqueous sodium hydrogen carbonate
solution and extracted with chloroform. The organic
layer was washed with brine, then dried over anhydrous
sodium sulfate. The solvent was removed under reduced
pressure and the residue was recrystalized from metha-
nol to give 11a (167 mg, 86%) as a colorless crystals.
5.1.49.
5-Chloro-N-(4-chloro-5-isopropyl-3-methyl-1,
3-thiazol-2(3H)-ylidene)-2-hydroxybenzenesulfonamide
(11f). 53% yield; mp 132–133 ꢁC (diethyl ether). 1H
NMR (DMSO-d6) d: 1.21 (6H, d, J = 6.8 Hz, CH3 of
i-Pr), 3.18 (1H, heptet, J = 6.8 Hz, CH of i-Pr), 3.43
(3H, s, 3-Me), 6.88 (1H, d, J = 8.8 Hz, benzene), 7.56
(1H, dd, J = 2.4, 8.8 Hz, benzene), 7.79 (1H, d,
J = 2.4 Hz, benzene), 10.86 (1H, br s, OH); FAB-MS
m/z: 381 (M++1). Anal. Calcd for C13H14Cl2N2O3S2:
C, 40.95; H, 3.70; N, 7.35; S, 16.82; Cl, 18.60. Found:
C, 40.94; H, 3.49; N, 7.36; S, 16.75; Cl, 18.39.
1
Mp 201–202 ꢁC. H NMR (DMSO-d6) d: 1.31 (9H, s,
CH3 of t-Bu), 2.27 (3H, s, 4-Me), 3.39 (3H, s, 3-Me),
6.93 (1H, dd, J = 2.5, 7.8 Hz, benzene), 7.21 (1H, m,
benzene), 7.23 (1H, br d, J = 7.8 Hz, benzene), 7.31
(1H, t, J = 8.3 Hz, benzene), 9.95 (1H, s, OH); FAB-
MS m/z: 341 (M++1). Anal. Calcd for C15H20N2O3-
S2Æ0.2H2O: C, 52.36; H, 5.98; N, 8.14; S, 18.64. Found:
C, 52.45; H, 5.83; N, 7.94; S, 18.34.
5.1.50. 5-Bromo-N-(4-chloro-5-isopropyl-3-methyl-1,
3-thiazol-2(3H)-ylidene)-2-hydroxybenzenesulfonamide
(11g). 41% yield; mp 135–137 ꢁC (diethyl ether). 1H

N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
959
NMR (DMSO-d6) d: 1.21 (6H, d, J = 6.8 Hz, CH3 of
i-Pr), 3.18 (1H, heptet, J = 6.8 Hz, CH of i-Pr), 3.43
(3H, s, 3-Me), 6.93 (1H, d, J = 8.8 Hz, benzene), 7.44
(1H, dd, J = 2.9, 8.8 Hz, benzene), 7.67 (1H, d,
J = 2.9 Hz, benzene), 10.85 (1H, br s, OH); FAB-MS
m/z: 425 (M++1). Anal. Calcd for C13H14ClBrN2O3S2:
C, 36.67; H, 3.31; N, 6.58; S, 15.06; Cl, 8.33; Br,
18.77. Found: C, 36.67; H, 3.36; N, 6.54; S, 15.04; Cl,
8.49; Br, 18.53.
sure and the residue was purified by silica gel column
chromatography (ethyl acetate–toluene) and recrystal-
ized from methanol to give 14 (135 mg, 56%) as a color-
less powder. Mp 165–166 ꢁC. H NMR (DMSO-d6) d:
1.32 (9H, s, CH3 of t-Bu), 2.29 (3H, s, 4-Me), 3.24
(3H, s, CH3 ofMs), 3.44 (3H, s, 3-Me), 7.62 (1H, d,
J = 8.8 Hz, benzene), 7.69 (1H, dd, J = 2.4, 8.8 Hz, benz-
ene), 7.82 (1H, d, J = 2.4 Hz, benzene), 8.68 (1H, br s,
NH); FAB-MS m/z: 452 (M++1). Calcd for
C16H22ClN3O4S3: C, 42.51; H, 4.91; N, 9.30; S, 21.28;
Cl, 7.84. Found: C, 42.51; H, 4.87; N, 9.29; S, 21.41;
Cl, 7.66.
1
5.1.51. 2-Amino-N-(5-tert-butyl-3,4-dimethyl-1,3-thiazol-
2(3H)-ylidene)-5-chlorobenzenesulfonamide (12). To a
suspension of 10i (960 mg, 2.38 mol) in ethanol
(10 mL) and tetrahydrofuran (30 mL) was added 10%
palladium–charcoal. The reaction mixture was stirred
at room temperature for 1.5 h under hydrogen atmo-
sphere. The suspension was filtered through the Celite
pad and evaporated. The residue was purified with
recrystalization from isopropanol–diethyl ether to give
12 (548 mg, 62%) as a brown powder. Mp 163–164 ꢁC.
1H NMR (DMSO-d6) d: 1.31 (9H, s, CH3 of t-Bu),
2.27 (3H, s, 4-Me), 3.41 (3H, s, 3-Me), 5.94 (2H, br s,
NH2), 6.79 (1H, d, J = 8.8 Hz, benzene), 7.24 (1H, dd,
J = 2.4, 8.8 Hz, benzene), 7.49 (1H, d, J = 2.4 Hz, benz-
ene); FAB-MS m/z: 374 (M++1). Calcd for
C15H20ClN3O2S2: C, 48.18; H, 5.39; N, 11.24; S, 17.15;
Cl, 9.48. Found: C, 48.43; H, 5.36; N, 11.10; S, 17.05;
Cl, 9.19.
5.1.54. 2-{[(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)amino]sulfonyl}-4-chlorophenyl trifluoromethane-
sulfonate (15a). A solution of 11e (1.00 g, 2.67 mmol),
2,6-lutidine (0.47 mL, 4.01 mmol), and N,N-dimethyl-
aminopyridine (33 mg, 0.27 mmol) in dichloromethane
(15 mL) was added trifluoromethanesulfonic anhydride
(0.68 mL, 4.01 mmol) under ice-bath cooling. The
solution was stirred at the same temperature for
30 min. The reaction mixture was poured into water
and extracted with chloroform. The organic layer was
washed with saturated aqueous potassium hydrogen sul-
fate and brine, then dried over anhydrous sodium sul-
fate. The solvent was removed under reduced pressure
and the residue was recrystalized from diethyl ether to
give 15a (877 mg, 64%) as a colorless powder. This crude
product was used for next steps without further
purification.
5.1.52.
N-(2-{[(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-
2(3H)-ylidene)amino]sulfonyl}-4-chlorophenyl)acetamide
(13). A solution of 12 (330 mg, 0.88 mmol), N,N-dimeth-
ylaminopyridine (110 mg, 0.88 mmol) and acetyl chlo-
ride (0.13 mL, 1.76 mmol) in pyridine (7 mL) was
stirred at room temperature for 5 h. The reaction mix-
ture was evaporated and diluted with ethyl acetate.
The solution was washed with 1 M hydrochloric acid,
saturated aqueous sodium hydrogen carbonate solution
and brine, then dried over anhydrous sodium sulfate.
The solvent was removed under reduced pressure and
the residue was purified by silica gel column chromato-
graphy (chloroform–methanol) and recrystalized from
acetonitrile to give 13 (92 mg, 25%) as a colorless pow-
der. Mp 194–195 ꢁC. 1H NMR (DMSO-d6) d: 1.28
(9H, s, CH3 of t-Bu), 2.12 (3H, s, 4-Me), 2.28 (3H, s,
CH3 ofAc), 3.41 (3H, s, 3-Me), 7.63 (1H, dd, J = 2.5,
8.8 Hz, benzene), 7.81 (1H, d, J = 2.5 Hz, benzene),
8.11 (1H, d, J = 8.8 Hz, benzene), 9.24 (1H, br s, NH);
FAB-MS m/z: 416 (M++1). Calcd for C17H22ClN3O3S2:
C, 49.09; H, 5.23; N, 10.10; S, 15.42; Cl, 8.52. Found: C,
49.10; H, 5.25; N, 10.06; S, 15.49; Cl, 8.46.
5.1.55. 4-Chloro-2-{[(4-chloro-5-isopropyl-3-methyl-1,3-
thiazol-2(3H)-ylidene)amino]sulfonyl}phenyl trifluorome-
thanesulfonate (15b). Compound 15b was obtained from
11f in the same manner as described in the synthesis of
1
15a quantitative. H NMR (DMSO-d6) d: 1.18 (6H, d,
J = 6.8 Hz, CH3 of i-Pr), 3.17 (1H, heptet, J = 6.8 Hz,
CH of i-Pr), 3.48 (3H, s, 3-Me), 7.60 (1H, s,
J = 8.8 Hz, benzene), 7.88 (1H, dd, J = 2.4, 8.8 Hz,
benzene), 8.01 (1H, d, J = 2.4 Hz, benzene); FAB-MS
m/z: 513 (M++1).
5.1.56. Methyl 2-{[(5-tert-butyl-3,4-dimethyl-1,3-thiazol-
2(3H)-ylidene)amino]sulfonyl}-4-chlorobenzoate
(16).
Under argon atmosphere, 15a (25.4 g, 50.1 mmol) was
dissolved in N,N-dimethylformamide (280 mL) and
methanol (140 mL). Triethylamine (12.9 mL, 92.6
mmol), 1,3-bis(diphenylphosphino)propane (1.74 g,
4.2 mmol), palladium acetate (0.95 g, 4.2 mmol) was
added and carbon monoxide gas was bubbled. The reac-
tion mixture was stirred at 70 ꢁC for 2.5 h under carbon
monoxide atmosphere. The mixture was evaporated and
diluted with ethyl acetate. The organic layer was washed
with 1 M hydrochloric acid and brine, then dried over
anhydrous sodium sulfate. The solvent was removed
under reduced pressure and the residue was purified by
silica gel column chromatography (ethyl acetate–
toluene) and recrystalized from isopropanol–diethyl
ether to give 16 (7.32 g, 42%) as a colorless powder.
5.1.53. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-5-chloro-2-[(methylsulfonyl)amino]benzenesulfon-
amide (14). A solution of 12 (200 mg, 0.54 mmol), trieth-
ylamine (0.15 mg, 1.08 mmol), and methanesulfonyl
chloride (0.062 mL, 0.83 mmol) in tetrahydrofuran
(4 mL) was stirred at room temperature for 1 h. The
reaction mixture was evaporated and diluted with ethyl
acetate. The solution was washed with 1 M hydrochloric
acid, saturated aqueous sodium hydrogen carbonate
solution and brine, then dried over anhydrous sodium
sulfate. The solvent was removed under reduced pres-
1
Mp 142–143 ꢁC. H NMR (DMSO-d6) d: 1.32 (9H, s,
CH3 of t-Bu), 2.30 (3H, s, 4-Me), 3.43 (3H, s, 3-Me),
3.78 (3H, s, CH3 ofCOOMe), 7.61 (d, J = 8.3 Hz, benz-
ene), 7.75 (1H, dd, J = 2.0, 8.3 Hz, benzene), 7.91 (1H,

960
N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
d, J = 2.0 Hz, benzene); FAB-MS m/z: 417 (M++1).
Calcd for C17H21ClN2O4S2: C, 48.97; H, 5.08; N, 6.72;
S, 15.38; Cl, 8.50. Found: C, 49.02; H, 4.95; N, 6.78;
S, 15.43; Cl, 8.47.
5.1.60. N-(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)-5-chloro-2-cyanobenzenesulfonamide (18a).
Compound 18a was obtained from 17a in the same man-
ner as described in the synthesis of 18b. 67% yield; mp
1
160–162 ꢁC. H NMR (DMSO-d6) d: 1.32 (9H, s, CH3
5.1.57. 2-{[(5-tert-Butyl-3,4-dimethyl-1,3-thiazol-2(3H)-
ylidene)amino]sulfonyl}-4-chlorobenzamide (17a). To a
solution of 16 (100 mg, 0.248 mmol) in N,N-dimethyl-
formamide (2 mL), 1-hydroxybenzotriazole (50 mg,
0.372 mmol), 1-[3-(dimethylamino)propyl]-3-ethylcar-
of t-Bu), 2.30 (3H, s, 4-Me), 3.49 (3H, s, 3-Me), 7.88
(1H, dd, J = 2.0, 8.3 Hz, benzene), 8.02 (1H, d,
J = 2.0 Hz, benzene), 8.09 (1H, d, J = 8.3 Hz, benzene);
FAB-MS m/z: 384 (M++1). Anal. Calcd for
C16H18ClN3O2S2: C, 50.06; H, 4.73; N, 10.95; S, 16.70;
Cl, 9.23. Found: C, 49.84; H, 4.63; N, 10.75; S, 16.67;
Cl, 9.15.
bodiimide
hydrochloride
(WSCÆHCl,
71 mg,
0.372 mmol), N,N-diisopropylethylamine (0.17 mL,
0.992 mmol), and ammonium chloride (27 mg,
0.496 mmol) was added. The solution was stirred at
room temperature for 2.5 h. The reaction mixture was
poured into water and extracted with chloroform. The
organic layer was washed with 1 M hydrochloric acid
and brine, then dried over anhydrous sodium sulfate.
The solvent was removed under reduced pressure and
the residue was purified by silica gel column chromato-
graphy (methanol–chloroform) and recrystalized from
diethyl ether to give 17a (71 mg, 71%) as a colorless
5.1.61. 5-Chloro-N-(4-chloro-5-isopropyl-3-methyl-1,3-
thiazol-2(3H)-ylidene)-2-cyanobenzenesulfonamide (19).
Under argon atmosphere, 15b (3.64 g, 7.1 mmol) was
dissolved in N,N-dimethylformamide (100 mL) and pal-
ladium tris(dibenzylideneacetone)dipalladium (408 mg,
0.71 mmol), 1,10-bis(diphenylphosphino)ferrocene (787
mg, 14.2 mmol), zinc powder (56 mg, 0.85 mmol), and
zinc(II) cyanide (500 mg, 4.3 mmol) was added. The
reaction mixture was stirred at 130 ꢁC for 2.5 h under
argon atmosphere. The mixture was evaporated and
diluted with ethyl acetate. The organic layer was
washed with 2 M aqueous ammonia solution, water,
and brine, then dried over anhydrous sodium sulfate.
The solvent was removed under reduced pressure and
the residue was purified by silica gel column chromato-
graphy (ethyl acetate–toluene) and recrystalized from
isopropanol to give 19 (1.38 g, 50%) as a pale yellow
powder. Mp 181–182 ꢁC (isopropanol). 1H NMR
(DMSO-d6) d: 1.20 (6H, d, J = 6.8 Hz, CH3 of i-Pr),
3.18 (1H, heptet, J = 6.8 Hz, CH of i-Pr), 3.32 (3H,s,
3-Me), 7.92 (1H, dd, J = 1.9, 8.3 Hz, benzene), 8.04
(1H, d, J = 1.9 Hz, benzene), 8.12 (1H, d, J = 8.3 Hz,
benzene); FAB-MS m/z: 390 (M++1). Anal. Calcd for
C14H13Cl2N3O2S2: C, 43.08; H, 3.36; N, 10.77; S,
16.43; Cl, 18.17. Found: C, 43.03; H, 3.23; N, 10.70; S,
16.34; Cl, 18.21.
1
powder. Mp 196–198 ꢁC. H NMR (DMSO-d6) d: 1.31
(9H, s, CH3 of t-Bu), 2.28 (3H, s, 4-Me), 3.42 (3H, s,
3-Me), 7.47 (1H, d, J = 8.3 Hz, benzene), 7.61 (2H, br
s, NH2), 7.68 (1H, dd, J = 2.0, 8.3 Hz, benzene), 7.87
(1H, d, J = 2.0 Hz, benzene); FAB-MS m/z: 402
(M++1). Anal. Calcd for C16H20ClN3O3S2: C, 47.81;
H, 5.02; N, 10.45; S, 15.96; Cl, 8.82. Found: C, 47.72;
H, 4.78; N, 10.42; S, 15.82; Cl, 8.91.
5.1.58.
4-Cyano-2-{[(5-isopropyl-3,4-dimethyl-1,3-thi-
azol-2(3H)-ylidene)amino]sulfonyl}benzamide (17b). Com-
pound 17b was obtained from 10q in the same manner as
described in the synthesis of 17a. 68% yield. H NMR
1
(DMSO-d6) d: 1.15 (6H, d, J = 6.8 Hz, CH3 of i-Pr),
2.17 (3H, s, 4-Me), 3.21 (1H, heptet, J = 6.8 Hz, CH of
i-Pr), 3.43 (3H, s, 3-Me), 7.61 (1H, d, J = 8.3 Hz, ben-
zene), 7.72 (2H, br d, J = 6.3 Hz, NH2), 8.02 (1H, dd,
J = 1.9 Hz, benzene), 8.27 (1H, d, J = 1.9 Hz, benzene);
FAB-MS m/z: 379 (M++1).
5.1.62. N-(4-Chloro-5-isopropyl-3-methyl-1,3-thiazol-
2(3H)-ylidene)-2,5-dicyanobenzenesulfonamide (20).
5.1.59. 2,5-Dicyano-N-(5-isopropyl-3,4-dimethyl-1,3-thi-
azol-2(3H)-ylidene)benzenesulfonamide (18b). Phospho-
rous oxychloride (0.3 mL, 3.3 mmol) and N,N-
dimethylformamide (50 lL, 0.66 mmol) was added to a
solution of 17b (250 mg, 0.66 mmol) in chloroform
(30 mL). The reaction mixture was refluxed for 24 h.
The reaction mixture was poured into ice-water and ex-
tracted with chloroform. The organic layer was washed
with saturated aqueous sodium hydrogen carbonate and
brine, then dried over anhydrous sodium sulfate. The
solvent was removed under reduced pressure and the
residue was purified by silica gel column chromatogra-
phy (methanol–chloroform) to give 18b (52 mg, 22%)
as a yellow powder. Mp 222–224 ꢁC. 1H NMR
(DMSO-d6) d: 1.15 (6H, d, J = 6.8 Hz, CH3 of i-Pr),
2.19 (3H, s, 4-Me), 3.22 (1H, heptet, J = 6.8 Hz, CH
of i-Pr), 3.49 (3H, s, 3-Me), 8.28 (2H, m, benzene),
8.42 (1H, br s, benzene); FAB-MS m/z : 361 (M++1).
Anal. Calcd for C16H16N4O2S2: C, 53.31; H, 4.47; N,
15.54; S, 17.79. Found: C, 53.15; H, 4.39; N, 15.70; S,
17.74.
Compound 20 was obtained from 15b in the same man-
ner as described in the synthesis of 19 with 1.6 mol equiv
ofZn(CN) . 60% yield. Mp 205–207 ꢁC (isopropanol).
2
1H NMR (CDCl3): 1.27 (6H, d, J = 6.8 Hz, CH3 of i-
Pr), 3.22 (1H, heptet, J = 6.8 Hz, CH of i-Pr), 3.60
(3H, s, 3-Me), 7.87 (1H, dd, J = 1.9, 8.3 Hz, benzene),
7.92 (1H, d, J = 8.3 Hz, benzene), 8.47 (1H, d,
J = 1.9 Hz, benzene); FAB-MS m/z: 381 (M++1). Anal.
Calcd for C15H13ClN4O2S2: C, 47.30; H, 3.44; N,
14.71; S, 16.84; Cl, 9.31. Found: 47.15; H, 3.52; N,
15.00; S, 16.65; Cl, 9.35.
5.2. Pharmacology
5.2.1. In vitro RT inhibition assay. A expression plas-
mide, pG280, encoding HIV-1 RT proteins as LacZ fu-
sion proteins were used for the expression of the WT RT
and mutated RTs.12 The single amino acid-substituted
RTs (K103N RT and Y181C RT) were constructed
using pG280 from a QuikchangeTM Site-Directed Muta-
genesis Kit (Stratagene, La Jolla, CA). Recombinant

N. Masuda et al. / Bioorg. Med. Chem. 13 (2005) 949–961
961
RT enzymes were expressed in E. coli. UTX81 and
Acknowledgements
purified by the scheme described by Saitoh et al.12 In
vitro RT assays were conducted according to the previ-
ously described method with the following modifi
cations.13 Test compounds and 0.01 unit ofrecombinant
HIV-1 RT (either wild type or mutant) were incubated
in a reaction mixture (50 lL), containing 50 mM Tris–
HCl (pH 8.4), 100 mM KCl, 10 mM MgCl2, 0.1%
Triton X-100, 2 mM dithiothreitol, 0.01 OD260 of
poly(rC)/oligo(dG)12–18, and 1 lCi of[1 0,20-3H]dGTP
(33 Ci/mmol) at 37 ꢁC for 1 h. The reaction was
stopped with 200 lL of5% cold trichloroacetic acid.
The precipitated materials were analyzed for radio activ-
ity using a scintillation counter (Aloka Co., Ltd.,
Tokyo, Japan).
We wish to acknowledge helpful discussion with Dr.
Susumu Igarashi. We also thank members ofthe Divi-
sion of Analytical Research for performing instrumental
analysis.
References and notes
´
1. Jonckheere, H.; Anne, J.; De Clercq, E. Med. Res. Rev.
2000, 20, 129.
2. Esnouf, R.; Ran, J.; Ross, C.; Jones, Y.; Stammers, D.;
Stuart, D. Nat. Struct. Biol. 1995, 2, 303.
3. Richman, D. D.; Havlir, D.; Corbeil, J.; Looney, D.;
Ignacio, C.; Spector, S. A.; Sullivan, J.; Cheeseman, S.;
Barringer, K.; Pauletti, D. J. Virol. 1994, 68, 1660.
4. Bacheler, L. T. Drug Resist. Updates 1999, 2, 56.
5. Staszewski, S.; Morales-Ramirez, J.; Tashima, K. T.;
Rachlis, A.; Skiest, D.; Stanford, J.; Stryker, R.; Johnson,
P.; Labriola, D. F.; Farina, D.; Manion, D. J.; Ruiz, N.
M. N. Eng. J. Med. 1999, 341, 1865.
6. Bacheler, L. T.; Anton, E. D.; Kudish, P.; Baker, D.;
Bunville, J.; Krakowski, K.; Bolling, L.; Aujay, M.; Wang,
X. V.; Ellis, D.; Becker, M. F.; Lasut, A. L.; George, H. J.;
Spalding, D. R.; Hollis, G.; Abremski, K. Antimicrob.
Agents Chemother. 2000, 44, 2475.
5.2.2. Cells and viruses. MT-4 cells14 and HIV-1IIIB
were used for the anti-HIV-1 assays. MT-4 cells were
grown and maintained in RPMI-1640 medium supple-
mented with 10% heat-inactivated fetal bovine serum
(FBS), penicillin G (100 units/mL), and gentamicin
(20 mg/mL). MT-4 cells and HIV-1IIIB were obtained
from Rational Drug Design Laboratories (Fukushima,
Japan).
7. Masuda, N.; Yamamoto, O.; Fujii, M.; Ohgami, T.;
Fujiyasu, J.; Kontani, T.; Moritomo, A.; Kageyama, S.;
Ohta, M.; Orita, M.; Kurihara, H.; Koga, H.; Nakahara,
H.; Inoue, H.; Hatta, T.; Suzuki, H.; Sudo, K.; Shimizu,
Y.; Kodama, E.; Matsuoka, M.; Fujiwara, M.; Yokota,
T.; Shigeta, S.; Baba, M. Bioorg. Med. Chem. 2004, 12,
6171–6182.
8. Saari, W. S.; Schwering, J. E. J. Heterocycl. Chem. 1986,
23, 1253.
9. Gerlach, U.; Wollmann, T. Tetrahedron Lett. 1992, 33,
5499.
10. Fuqiang, J. F.; Confalone, P. N. Tetrahedron Lett. 2000,
41, 3271.
11. Ouedraogo, R.; Becker, B.; Boverie, S.; Somers, F.;
Antoine, M. H.; Pirotte, B.; Lebrun, P.; de Tullio, P.
Biol. Chem. 2002, 383, 1759.
5.2.3. Anti-HIV-1 assay. Determination ofthe antiviral
activity ofthe test compounds against HIV-1 IIIB replica-
tion was based on the inhibition ofvirus-induced
cytopathicity in MT-4 cells. Briefly, MT-4 cells were sus-
pended in culture medium at 1 · 105 cells/mL and
infected with virus at a multiplicity of infection (MOI)
of 0.02. Immediately after virus infection, the cell suspen-
sion (100 lL) was brought into each well ofa flat-
bottomed microtiter tray containing various concentra-
tions ofthe test compounds. Atfer a 5-day incubation
at 37 ꢁC, the number ofviable cells was determined
by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazo-
lium bromide (MTT) method.15 The HTS ofour com-
12. Saitoh, A.; Iwasaki, H.; Nakata, A.; Adachi, A.; Shina-
gawa, H. Microbiol. Immunol. 1990, 34, 509.
13. Baba, M.; De Clercq, E.; Tanaka, H.; Ubasawa, M.;
Takashima, H.; Sekiya, K.; Nitta, I.; Umezu, K.; Naka-
shima, H.; Mori, S.; Shigeta, S.; Walker, R. T.; Miyasaka,
T. Proc. Natl. Acad. Sci. U.S.A. 1991, 88, 2356.
14. Harada, S.; Koyanagi, Y.; Yamamoto, N. Science 1985,
229, 563.
pound library was also performed using the MTT
assay against HIV-1IIIB-R
14
.
The anti-HIV-1 activity
and cytotoxicity oftest compounds were expressed as
EC50 and CC50, respectively. EC50 is the concentra-
tion ofa test compound that was able to achieve 50%
protection ofMT-4 cells rfom HIV-1 induced CPE.
CC50 is the concentration ofa test compound that
reduced viable cell number by 50% in mock-infected
15. Pauwels, R.; Balzarini, J.; Baba, M.; Snoeck, R.; Schols,
D.; Herdewijn, P.; Desmyter, J.; De Clercq, E. J. Virol.
Methods 1988, 20, 309.
cells. The therapeutic index (TI) is the ratio ofCC to
50
EC50.