Design, synthesis and biological evaluation of benzo[1.3.2]dithiazolium ylide 1,1-dioxide derivatives as potential dual cyclooxygenase-2/5-lipoxygenase inhibitors

Article abstract of DOI:10.1016/j.bmc.2011.09.003

3-(4-Bromophenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide (5) was discovered as a new prototype for dual inhibitors of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). Thus, the structure-activity relationships of benzo[1.3.2]dithiazolium ylide 1,1-dioxide skeleton were carried out. The 6-NO2 group played an essential role in the inhibitory activity. In addition, moderate-sized lipophilic substituents at the para-position of the 3-aryl moiety were required for dual COX-2/5-LOX inhibitory activity. Among the identified potent dual inhibitors, 3-(4-tbutylphenyl) derivative 30c (IC₅₀ values of 0.27 μM and 0.30 μM against COX-2 and 5-LOX, respectively) and 3-(4-biphenyl) derivative 30f (IC₅₀ values of 0.50 μMand 0.15 μMagainst COX-2 and 5-LOX, respectively) were the most potent dual COX-2/ 5-LOX inhibitors. Intraperitoneal administration of 30c at 100 mg/kg demonstrated potent acute antiinflammatory activity. As a result, benzo[1.3.2]dithiazolium ylide 1,1-dioxide represented a novel scaffold for the exploitation in developing dual COX-2/5-LOX inhibitors.

Full text of DOI:10.1016/j.bmc.2011.09.003

Bioorganic & Medicinal Chemistry 19 (2011) 6316–6328
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Design, synthesis and biological evaluation of benzo[1.3.2]dithiazolium ylide
1,1-dioxide derivatives as potential dual cyclooxygenase-2/5-lipoxygenase
inhibitors
Chen-Ming Tan a, Grace Shiahuy Chen a,b, Chien-Shu Chen a,c, Pei-Teh Chang a, Ji-Wang Chern a,d,
⇑
a School of Pharmacy, National Taiwan University, Taipei 10051, Taiwan, ROC
b Department of Applied Chemistry, Providence University, Taichung 43301, Taiwan, ROC
c School of Pharmacy, China Medical University, Taichung 40402, Taiwan, ROC
d Department of Life Science, College of Life Science, National Taiwan University, Taipei 10617, Taiwan, ROC
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 21 June 2011
Revised 2 September 2011
Accepted 3 September 2011
Available online 10 September 2011
3-(4-Bromophenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide (5) was discovered as a new
prototype for dual inhibitors of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). Thus, the
structure–activity relationships of benzo[1.3.2]dithiazolium ylide 1,1-dioxide skeleton were carried
out. The 6-NO2 group played an essential role in the inhibitory activity. In addition, moderate-sized lipo-
philic substituents at the para-position of the 3-aryl moiety were required for dual COX-2/5-LOX inhib-
itory activity. Among the identified potent dual inhibitors, 3-(4-tbutylphenyl) derivative 30c (IC50 values
Keywords:
Cyclooxygenase-2
5-Lipoxygenase
Structure–activity relationship
Dual inhibitor
of 0.27
values of 0.50
l
M and 0.30
l
M against COX-2 and 5-LOX, respectively) and 3-(4-biphenyl) derivative 30f (IC50
M against COX-2 and 5-LOX, respectively) were the most potent dual COX-2/
l
M and 0.15
l
5-LOX inhibitors. Intraperitoneal administration of 30c at 100 mg/kg demonstrated potent acute anti-
inflammatory activity. As a result, benzo[1.3.2]dithiazolium ylide 1,1-dioxide represented a novel
scaffold for the exploitation in developing dual COX-2/5-LOX inhibitors.
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
COX-2/5-LOX inhibitors such as compounds 310 and 411 (Fig. 1) have
drawn attention. Dual COX-2/5-LOX inhibitors have been validated
Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used
for the treatment of pain and inflammation. NSAIDs inhibit the
cyclooxygenase (COX) enzymes to block arachidonic acid metabo-
lism. There are two isoforms of COX enzyme. COX-1 is a constitutive
isoform responsible for cytoprotective effects while COX-2 is an
inducible isoform for inflammatory effects.1 Classical NSAIDs may
cause gastroinstinal (GI) side effects due to the nonselective inhibi-
tion of both COX-1 and COX-2 isoforms.2 Selective COX-2 inhibitors
such as celecoxib (1)3,4 and rofecoxib (2)5 (Fig. 1) represent a new
generation of NSAIDs. However, rofecoxib was withdrawn from
the market due to increased cardiovascular risks such as myocardial
infarction and stroke.6,7 The adverse cardiovascular effects might
result from the inhibition of prostacyclin production by selective
COX-2 inhibitors.8 In addition to the COX enzymes, lipoxygenase
(LOX) is also responsible for the metabolism of arachidonic acid.
Thus, 5-LOX inhibitors are considered as potential therapeutic
anti-inflammatory agents as well.9 It is believed12 that dual inhibi-
tion of COX-2 and 5-LOX mechanistic pathways might be more
effective in anti-inflammation with less adverse effects. Dual
for the treatment of inflammation13 and inflammation-related dis-
eases such as acute pancreatitis,14 arthritis, and bronchospasm re-
sulted from physiological inflammation processes.15,16
6-Nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide 5 was dis-
covered as dual COX-2/5-LOX inhibitor in our previous study.17
Compound 5 possessed inhibitory activity with IC50 values of
1.7
tively. Interestingly, 5-nitro derivative 6 displayed high potency
against 5-LOX enzyme with an IC50 value of 0.47 M but it was
lM and 1.22 lM (Table 1) against COX-2 and 5-LOX, respec-
l
inactive against COX-2 enzyme. Replacement of the 5-NO2 group
by 5-SO2NH2 group did not improve the COX-2 inhibitory activity
but defeated the potency against 5-LOX (Table 1).17
Compound 5 exists in a racemic mixture, and docking model
revealed that (S)-enantiomer could fit into the active site of COX-2
enzyme.17 The (S)-5 was predicted to have two hydrogen bonds
via the SO2 group with Arg120 and Tyr355 and two hydrogen bonds
via the 6-NO2 group with His90 and Arg513 in the active site of
COX-2 ( Fig. 2). Docking model17 showed that the SO2 group of
compound 6 had two hydrogen bonds with Tyr355 but the 5-NO2
group was not hydrogen bonded to His90. Indeed, compound 5
possessed moderate inhibitory potency against COX-2 enzyme
(IC50 = 1.70
against COX-2 enzyme (23% at 10
l
M) while compound 6 exhibited very weak inhibition
M). Apparently, the 6-NO2 group
⇑
Corresponding author. Tel.: +886 223939462; fax: +886 223934221.
E-mail address: jwchern@ntu.edu.tw (J.-W. Chern).
l
0968-0896/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2011.09.003

C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
6317
H2NO2S
H3CO2S
N
N
CF3
O
O
H3C
2 (Rofecoxib)
1 (Celecoxib)
H3CO
F
H3CO2S
N
N
N
N
O
OCH3
O
O
OH
N
H3C
Cl
3 (Tepoxalin)
4 (Searle derivative)
Figure 1. COX-2 inhibitors (1 and 2) and dual COX-2/5-LOX inhibitors (3 and 4).
Table 1
Inhibitory activity of compounds 5–7 on human recombinant COX-2 and 5-LOXa
R2
R2
X
Br
Br
Br
b
a
R1
S
S
S
R1
R1
N
SO2NH2
SO2NH2
O
O2N
H2NO2S
O
S
S
S
S
S
S
N
N
N
Scheme 1. General synthesis of benzo[1.3.2]dithiazolium ylide 1,1-dioxidederiva-
tives. Reagents and conditions: (a) For X = I: aryl thiol, CuI (10 mol %), neocuproine
(10 mol %), K3PO4 (1.5 equiv), toluene, reflux; For X = Br: aryl thiol, K2CO3, ethanol,
reflux; (b) Br2, MeOH, rt.
O2N
O
O
O
O
O
O
5
6
7
Compd
COX-2
5-LOX
5
6
7
IC50 = 1.70
l
M
IC50 = 1.22
IC50 = 0.47
14% at 10 lM
l
l
M
M
23% at 10
27% at 10
lM
l
ylide 1,1-dioxide derivatives, and the in vivo anti-inflammatory
activity of potent dual COX-2/5-LOX inhibitor 30c was evaluated.
M
a
Data from Ref. 13.
2. Results and discussion
2.1. Chemistry
Hydrophobic
pocket
The construction of benzo[1.3.2]dithiazolium ylide 1,1-dioxide
skeleton consists of cross-coupling reaction by 2-halobenzenesulf-
onamides with aryl thiols and followed oxidative intramolecular
cyclization reaction (Scheme 1).17,18 The key intermediates
2-arylsulfanylbenzenesulfonamides were prepared by 2-bromo-
or 2-iodobenzenesulfonamides with thiols in different reaction
conditions. The cross-coupling of aryl iodides and thiols was
accomplished by the catalyst of 10 mol % copper iodide, the ligand
of 10 mol % neocuproine, and the base of K3PO4 at moderate tem-
perature.19 This coupling reaction condition is selective for aryl
iodides. For 2-bromobenzenesulfonamide derivatives, the bromo
substituent was easily substituted by thiols in the presence of
K2CO3 as the base (Scheme 1).
Br
S
S
N
O2N
O
O
Arg513
Arg120
H
N
OH
N
His90
Tyr355
Diazotization of aniline-2,5-disulfonic acid (8a) and followed io-
dide substitution afforded 2-iodobenzene-1,4-disulfonic acid (9a),
which was then converted to sulfonate 10a (Scheme 2). Chlorination
of 10a with PCl5 and then a treatment with ammonium hydroxide
provided the desired 2-iodobenzenesulfonamide 11a, which was
applied for the preparation of 5-sulfonamidobenzo[1.3.2]dithiazoli-
um ylide 1,1-dioxide derivatives 7 and 12a–o as shown in Scheme 1.
Compounds 13a,b without substitution at the 5- or 6-position, and
compound 14a with 6-CH3 group were synthesized from 8b and
8c, respectively, by the same reaction procedures as outlined in
Scheme 2.
Figure 2. Docking mode of compound 5 in the active site of COX-2 enzyme.
of (S)-5 played an important role in inhibiting COX-2 enzyme. Fur-
thermore, the aryl moiety at the 3-position of benzo[1.3.2]dithiazo-
lium ylide 1,1-dioxide derivatives was predicted to fit into the
hydrophobic pocket.17 The substitution at the 5- and 6-position
might associate with the inhibitory activity on COX-2 and 5-LOX,
and the aryl group on the sulfur atom at the 3-position may also play
roles in the inhibition. In the present study, we carried out the struc-
ture-activity relationship of a series of benzo[1.3.2]dithiazolium

6318
C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
R1
R2
NH2
R3
R1
R2
9a
9b
I
R1
R2
I
a
b
SO3H
SO3Na
1 = SO3Na, R2 = H
8a R1 = SO3H, R2 = H, R3 = SO3Na
8b R1 = R2 = H, R3 = SO3H
R
R
1 = SO3H, R2 = H 10a
R
1 = R2 = H
10b R1 = R2 = H
R = H, R = CH3, R3 = SO3H
1
2
9c R1 = H, R2 = CH3
10c R1 = H, R2 = CH3
8c
R3
R1
R2
I
c
d
R1
R2
S
N
SO2NH2
S
O
O
11a
11b
R
R
1 = SO2NH2, R2 = H
1 = R2 = H
7 & 12a-o R1 = SO2NH2, R2 = H
13a-b
14a
R
1 = R2 = H
11c R1 = H, R2 = CH3
1
2
R = H, R = CH3
Scheme 2. Preparation of 5-SO2NH2 and 6-CH3 substituted derivatives 7, 12a–o, 13a,b, and 14a. Reagents and conditions: (a) (i) Na2CO3, NaNO2; (ii) concd HCl, 0 °C; (iii) KI,
0–80 °C; (b) 10 N NaOH; (c) (i) PCl5, 80 °C; (ii) concd NH4OH, 0 °C; (d) (i) aryl thiol, CuI (10 mol %), neocuproine (10 mol %), K3PO4 (1.5 equiv), toluene, reflux; (ii) Br2, MeOH, rt.
R1
Br
R3
R2
a
R1
R2
Br
R1
R2
S
S
15a R1 = H, R2 = H
c
N
15b R1 = H, R2 = SO2CH3
SO2NH2
O
O
16a R1 = H, R2 = SO2NH2
16b R1 = H, R2 = SO2CH3
16c R1 = Cl, R2 = SO2NH2
17a-d R1 = H, R2 = SO2NH2
18a-b R1 = H, R2 = SO2CH3
19 R1 = Cl, R2 = SO2NH2
b
Cl
NH2
H2NO2S
SO2NH2
15c
Scheme 3. Preparation of 6-SO2NH2 and 6-SO2CH3 substituted derivatives 17a–d, 18a,b, and 19. Reagents and conditions: (a) (i) ClSO3H, 150 °C; (ii) concd NH4OH, 0 °C; (b) (i)
NaNO2; (ii) concd H2SO4, 0 °C; (iii) CuBr2, 0–80 °C; (c) (i) aryl thiol, K2CO3, ethanol, reflux; (ii) Br2, MeOH, rt.
The preparations of 6-SO2NH2 and 6-SO2CH3 derivatives 17a–d,
18a,b, and 19 are illustrated in Scheme 3. Sulfonation and the suc-
cessive chlorination of 15a,b in the presence of chlorosulfonic acid
at reflux in a one-pot system afforded the corresponding sulfonyl
chlorides. The resulted sulfonyl chloride was treated with concen-
trated ammonium hydroxide to give 2-bromobenzenesulfona-
mides 16a–c, which were converted to benzo[1.3.2]dithiazolium
ylide 1,1-dioxide derivatives according to the method in Scheme 1.
Benzo[1.2]isothiazole 1,1-dioxides 24a–c, bioisosteric analogs
of benzo[1.3.2]dithiazolium ylide 1,1-dioxides, were prepared as
shown in Scheme 4. p-Toluenesulfonic acid (20) underwent sulfo-
nation, chlorination, and amidation to give 2,4-disulfamyltoluene
(21). Compound 21 was oxidized to 22, which was then converted
to saccharin 23a in concentrated sulfuric acid. Treatment of
compound 23a and commercially available saccharin 23b with
Grignard reagents gave the expected benzo[1.2]isothiazole
1,1-dioxides 24a and 24b–c, respectively.
character were prepared from thiols 33a and 33b, respectively,
which were obtained according to the reported method21 for the
preparation of alkanethiol as illustrated in Scheme 7. Phenol 31b
containing methoxytetrahydropyran16 was prepared according to
the reported method.22 Then, commercially available 31a and pre-
pared 31b underwent nucleophilic substitution with ethylene
dibromide to afford phenoxyethyl bromides 32a and 32b, respec-
tively. Treatments of 32a and 32b with thiourea, NaOH, and HCl in
sequence gave the corresponding mercaptoethoxy derivatives 33a
and 33b, respectively.
2.2. Biological evaluation
In addition to nitro group, hydrogen bond acceptors SO2NH2,
SO2CH3, and carboxylic acid derivatives were introduced to
benzo[1.3.2]dithiazolium ylide 1,1-dioxide for hydrogen bonding
to His90, Initially, 5-SO2NH2 derivatives 12a–o were evaluated at
2-(4-Bromophenylsulfanyl)-5-methylbenzenesulfonamide (25)
was used for the preparation of benzo[1.3.2]dithiazolium ylide
1,1-dioxides 14b–d with carboxylic acid derivatives substituted
at the 6-potition (Scheme 5). It is found that oxidation condition
(KMnO4 in 5% NaOH at reflux) caused the ring-opening of dithiazo-
lium ylide 1,1-dioxide. Thus, 5-methylbenzenesulfonamide 25 was
firstly oxidized to benzoic acid 26, which was then cyclized to
benzo[1.3.2]dithiazolium ylide 1,1-dioxide 14b. Subsequently, car-
boxylic acid 14b was converted to methyl ester 14c and amide 14d.
6-Nitro derivatives 5 and 30a–j were obtained by 2-iodo-5-nitro-
benzenesulfonamide (29) (Scheme 6) according to our previously
described method.17,20 Compounds 30i and 30j with a phenoxyethyl
a concentration of 10 lM but they showed very weak or no inhibi-
tion against both COX-2 and 5-LOX (Table 2). Compounds 13a and
13b, without 5- or 6-substitution, showed no inhibition on COX-2
and 5-LOX (Table 3). Then, 6-SO2NH2 derivatives 17a–d were
investigated. Still, the 6-SO2NH2 group did not improve the inhib-
itory activity against COX-2 and 5-LOX as compared to the 6-NO2
derivative 5 (Table 3). Additional 5-chloro substituent (19) im-
proved the inhibitory activity on COX-2 (IC50 = 2.30 lM) as com-
pared to 17a. In comparison of 18a–17a, 6-SO2CH3 group was
favored in the inhibitory activity against COX-2 and 5-LOX with
IC50 = 1.80
lM and 13.5 lM, respectively. 6-Methyl derivative
14a had no inhibition on COX-2, as expected. However, compound

C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
6319
O
CH3
COOH
CH3
a
b
c
NH
S
H2NO2S
SO2NH2
R2
H2NO2S
HO3S
H2NO2S
SO2NH2
O
O
23a
20
21
22
O
d
NH
N
R1
S
S
O
R
O
O
O
24a R1 = SO2NH2, R2 = Et
24b R1 = H, R2 = Br
23a R = SO2NH2
23b R = H
24c R1 = H, R2 = CH3
Scheme 4. Preparation of benzo[1.2]isothiazole 1,1-dioxides 24a–c. Reagents and conditions: (a) (i) ClSO3H, 150 °C; (ii) concd NH4OH, 0 °C; (b) KMnO4, 5% NaOHaq, reflux; (c)
concd H2SO4, rt; (d) Grignard reagents (1–3 equiv).
Br
Br
Br
a
b
S
S
S
S
N
R
O
H3C
SO2NH2
HO2C
SO2NH2
O
25
26
14b R = CO2H
c
14c R = CO2CH3
d
14d
R = CONH2
Scheme 5. Preparation of benzo[1.3.2]dithiazolium ylide 1,1-dioxide derivatives with carboxylic acid derivative substituents 14b–d. Reagents and conditions: (a) KMnO4, 5%
NaOH, reflux; (b) Br2, MeOH, rt; (c) (i) SOCl2; (ii) MeOH, 0 °C to rt; (d) (i) SOCl2; (ii) concd NH4OH, 0 °C to rt.
R1
NH2
I
I
a
b
c
S
S
O2N
SO3Na
O2N
SO3H
O2N
SO2NH2
N
O2N
27
28
29
O
O
5 & 30a-j
Scheme 6. Preparation of 6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide derivatives 5 and 30a–j. Reagents and conditions: (a) (i) HCl, NaNO2, H2O, 0 °C; (ii) KI, rt; (b) (i)
SOCl2, DMF, reflux; (ii) NH4OH, rt; (c) (i) aryl thiol, CuI, neocuproine, t-BuONa or K3PO4, toluene, reflux; (ii) Br2, MeOH, rt.
R1
R1
R1
a
b
Br
HS
R2
HO
31a R1 = R2 = OCH3
31b R1 = F, R2
H3CO
R2
O
R2
O
32a R1 = R2 = OCH3
33a R1 = R2 = OCH3
32b R1 = F, R2
H3CO
=
33b R1 = F, R2
H3CO
=
=
O
O
O
Scheme 7. Preparation of mercaptoethoxy derivatives 33a and 33b. Reagents and conditions: (a) BrCH2CH2Br, reflux; (b) (i) thiourea, EtOH, reflux; (ii) 2.5 N NaOH, reflux; (iii)
1 N HCl.
14a somewhat inhibited 5-LOX (IC50 = 6.05
l
M, Table 3). Carbox-
24a–c had no or very weak inhibition against both COX-2 and
5-LOX enzymes (Table 4).
ylic acid derivatives 14b–d exhibited very weak or no inhibitory
activity against COX-2 and 5-LOX. Replacing the 3-sulfur atom of
benzo[1.3.2]dithiazolium ylide 1,1-dioxides by a carbon atom led
to benzo[1.2]isothiazole 1,1-dioxides 24a–c, which have planar
structure different from the chiral structure in benzo[1.3.2]dith-
iazolium ylide 1,1-dioxide. The results showed that compounds
The 6-NO2 group on benzo[1.3.2]dithiazolium ylide 1,1-dioxide
is essential for the inhibitory activity against COX-2 and 5-LOX.
From the docking model,17 the 3-(4-bromophenyl) group of com-
pound 5 entered the hydrophobic pocket. Thus, miscellaneous
groups eligible for the hydrophobic pocket were introduced onto

6320
C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
Table 2
Table 4
Inhibitory activity of 5-SO2NH2 derivatives on human recombinant COX-2 and 5-LOX
Inhibitory activity of benzo[1.2]isothiazole 1,1-dioxides 24a–c on human recombi-
nant COX-2 and 5-LOX
R
R2
H2NO2S
S
S
N
O
N
O
R1
S
O
O
Compd
R
%Inhibition at 10
COX-2
lM
Compd
R1
R2
%Inhibition at 10
COX-2 (%)
lM
5-LOX
5-LOX (%)
7
4-Br
3-Br
4-F
4-Cl
4-Me
4-Et
4-iPr
4-tBu
4-CF3
4-OMe
2,4-F
2,4-Cl
2,4-Me
3,4-Cl
3,4-Me
3,4-OMe
27%
7%
14%
28%
9%
19%
9%
12a
12b
12c
12d
12e
12f
12g
12h
12i
12j
12k
12l
12m
12n
12o
24a
24b
24c
SO2NH2
H
H
Et
Br
Me
0
0
16
8
11
9
2%
NIa
2%
NIa
10%
NIa
NIa
NIa
NIa
9%
7%
19%
25%
37%
21%
NIa
NIa
NIa
NIa
NIa
NIa
Table 5
Inhibitory activity of 6-NO2 derivatives on human recombinant COX-2 and 5-LOX
R
S
N
NIa
14%
15%
6%
S
O2N
O
O
Compd
R
IC50
(
l
M) or %inhibition at 10
5-LOX
lM
a
NI: no inhibition.
COX-2
5
Br
Et
1.7
1.22
0.18
0.36
0.30
0.35
Table 3
Inhibitory activity of 13a,b and 6-substituted derivatives on human recombinant
COX-2 and 5-LOX
30a
30b
30c
30d
1.70
0.73
0.27
0.88
R3
i
Pr
Bu
t
R1
R2
S
N
OMe
OMe
S
O
O
Compd
R1
R2
R3
IC50
(l
M) or %inhibition at 10
5-LOX
lM
30e
15%
0.68
COX-2
OMe
13a
13b
17a
17b
17c
17d
19
18a
18b
14a
14b
14c
H
H
H
H
H
H
Cl
H
H
H
H
H
H
H
H
H
0%
2%
0%
14%
33%
91.1
42%
23%
3.45
25.8
13.5
35%
6.05
2%
30f
30g
30h
0.50
2.99
15%
0.15
3.09
17%
Br
Br
iPr
tBu
Ph
Br
Br
Et
Br
Br
Br
Br
SO2NH2
SO2NH2
SO2NH2
SO2NH2
SO2NH2
SO2Me
SO2Me
Me
44%
21%
31%
2.30
1.80
43%
14%
7%
33%
0%
0.17
—
CF3
N
OMe
30i
30j
35%
25%
3.70
25%
CO2H
CO2Me
CONH2
4.10
15%
—
OMe
O
O
14d
F
Rofecoxib
NDGAa
0.025
a
NDGA, nordihydroguaiaretic acid.
MeO
O
Rofecoxib
NDGAa
0.17
—
—
0.025
the 3-phenyl moiety of 6-nitrobenzo[1.3.2]dithiazolium ylide 1,
1-dioxide. It was found that compounds 30a–d and 30f containing
substituents Et, iPr, tBu, OMe, and Ph were all potent dual COX-2/5-
LOX inhibitors and more potent than compound 5 (Table 5).
Among them, compound 30c with 3-(4-tbutylphenyl) substituent
a
NDGA, nordihydroguaiaretic acid.
like t-butyl and phenyl groups interacted with the hydrophobic
pocket better than other smaller alkyl groups. In the comparison
of 30d and 30e, an extra methoxy group on the meta-position of
phenyl ring caused a decrease activity. The CF3 group (30g) led
was the most potent COX-2 inhibitor (IC50 = 0.27
compound 30f with 3-(4-biphenyl) substituent was the most
potent 5-LOX inhibitor (IC50 = 0.15 M). Apparently, bulky group
lM) and
l

C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
6321
Table 6
3. Conclusions
Anti-inflammatory activity of compound 30c in
a
carrageenan-induced rat paw
edema assay
A series of benzo[1.3.2]dithiazolium ylide 1,1-dioxide deriva-
tives were prepared and evaluated for the COX-2 and 5-LOX inhib-
itory activity. 6-Nitro substituted derivatives 30a–d and 30f were
potent dual COX-2/5-LOX inhibitors. Compound 30c exhibited po-
tent in vivo anti-inflammatory activity. Our results demonstrated
that benzo[1.3.2]dithiazolium ylide 1,1-dioxide derivatives repre-
sented a novel prototype for dual COX-2/5-LOX inhibitors.
Compd
Routea
IP
Dose
—
%Inhibitionb
—
Vehiclec
30c
IP
IP
IP
PO
10 mg/kg
30 mg/kg
100 mg/kg
150 mg/kg
14%
27%
65%
38%
Aspirin
a
IP, intraperitoneal administration; PO, oral administration.
Compound 30c was administered intraperitoneally 30 min before the right hind
b
paw received intraplantar injection of carrageenan (0.1 mL of 1% suspension). The
hind paw edema was measured 3 h later. Reduction of hind paw edema by 30% or
greater (P30%) relative to the vehicle control group indicates significant acute anti-
inflammatory activity.
4. Experimental
4.1. Chemistry
c
Vehicle: 1% Tween 80/0.9% NaCl.
4.1.1. 2-Iodobenzene-1,4-disulfonic acid (9a)
A mixture of aniline-2,5-disulfonic acid monosodium salt (8a,
13.76 g, 50 mmol) and sodium carbonate (2.8 g, 26.4 mmol) in
60 mL water was stirred to a homogeneous solution, to which
was added sodium nitrite (4.0 g, 56 mmol) with vigorous stirring.
The solution was stirred at 0 °C for 30 min, to which was added
concd HCl (10 mL) dropwise. After the precipitate of diazonium
salts had appeared for 30 min, a solution of KI (10 g, 60 mmol)
in H2O (10 mL) was added to the reaction mixture. After stirring
for 1 h, the reaction was warmed to room temperature and then
heated to 80 °C to evolve nitrogen gas. When no further gas was
generated, the solution was evaporated in reduced pressure to
give a yellowish-orange solid 9a in 72% yield. Mp 185–186 °C.
1H NMR (200 MHz, D2O) d 8.30 (d, J = 1.8 Hz, 1H; ArH), 7.93 (d,
J = 8.4 Hz, 1H; ArH), 7.72 (dd, J = 1.8, 8.4 Hz, 1H; ArH). 13C NMR
(50 MHz, acetone-d6) d 150.9, 149.9, 138.7, 128.5, 125.3, 93.3.
MS (EI) m/z = 364 [M]+. Anal. (C6H5IO6S2): C, 19.79; H, 1.38. Found:
C, 19.65; H, 1.30.
Figure 3. Effect of compound 30c on carrageenan-induced paw edema. The vehicle,
1% Tween 80/0.9% NaCl, was tested at 5 mg/kg, associated with the net increase of
paw volume of 0.65 mL. Data represent the mean SEM of duplicate
determinations.
4.1.2. 2-Iodobenzene-1,4-disulfonamide (11a)
To a solution of 9a (5 g) in water (20 mL) at 0 °C was added 10 N
NaOH dropwise, and then the filtrate was collected and evaporated
in reduced pressure to afford 10a (90%). Without further purifica-
tion, 10a was mixed with excessive PCl5 (3 g) and heated to
80 °C till complete liquefaction. The resulting mixture was added
portionwise to crushed ices (25 g), and the precipitate was col-
lected and washed with ice water (10 mL). To the solid in an ice
bath was then added concd NH4OH (6 mL) dropwise, and the mix-
ture was stirred at 0 °C to room temperature. After 3 h, the reaction
mixture was partitioned with ethyl acetate (5 mL ꢀ 3), and the or-
ganic part was collected, evaporated and purified by column chro-
matography (silica gel; hexane/EtOAc 1:1) to afford 11a in 54%
yield. Mp 167–169 °C. 1H NMR (400 MHz, acetone-d6) d 8.54 (s,
1H; ArH), 8.27 (d, J = 8.0 Hz, 1H; ArH), 8.05 (d, J = 8.0 Hz, 1H;
ArH), 6.88 (br, 4H; 2SO2NH2). 13C NMR (100 MHz, acetone-d6) d
149.3, 148.0, 140.9, 140.8, 131.0, 92.3. MS (EI) m/z = 362 [M]+. Anal.
(C6H7IN2O4S2): C, 19.90; H, 1.95; N, 7.73. Found: C, 19.84; H, 1.58;
N, 7.82.
to a reduced inhibition on COX-2/5-LOX. Compound 30h having 4-
pyridinyl moiety at the 3-position was inactive, probably due to its
polar property and the insufficiency in bulkiness.
It was reported that introduction of methoxytetrahydropyran
onto a selective COX-2 inhibitors resulted in benefit on dual COX-
2/5-LOX inhibitors such as 4.16,23 Initially, the simpler side chain
was prepared from commercially available 3,5-dimethoxyphenol
for the replacement of the 4-bromophenyl group on the sulfur atom
by 3,5-dimethoxyphenoxyethyl group. However, 30i exhibited de-
creased inhibitory activity on both COX-2 and 5-LOX. Concurrently,
methoxytetrahydropyran16 was introduced onto the phenoxyethyl
group at the 3-position of 6-nitrobenzo[1.3.2]dithiazolium ylide
1,1-dioxide as compound 30j. Compounds 30i and 30j were inac-
tive to COX-2 and 5-LOX, probably resulted from the oversized side
chain.
The potent dual COX-2/5-LOX inhibitor 30c was evaluated for
anti-inflammatory activity in the carrageenan-induced paw edema
assay in male Wistar rats. Compound 30c was administered intra-
peritoneally (IP) 30 min before carrageenan challenge. At doses of
10, 30, and 100 mg/kg, compound 30c exhibited a dose-dependent
inhibition of 14%, 27%, and 65%, respectively, relative to the vehicle
group (Table 6 and Fig. 3). Compound 30c at 100 mg/kg (IP) was
associated with significant activity of 65% inhibition of the carra-
geenan-induced paw swelling in rats, an inhibitory activity more
potent than aspirin with 35% inhibition at 150 mg/kg administered
orally. This result demonstrates that benzo[1.3.2]dithiazolium
ylide 1,1-dioxide 30c was a potential lead for further development
as anti-inflammatory drugs.
4.1.3. 2-Iodo-benzenesulfonamide (11b)
To a homogeneous solution of aniline-2-sulfonic acid (8b,
12.63 g, 70 mmol) and sodium carbonate (3.5 g, 33.0 mmol) in
water (75 mL) was added sodium nitrite (5 g, 70 mmol). The solu-
tion was stirred at 0 °C for 30 min, to which was added concd HCl
(12.5 mL) and crushed ice (25 g) portionwise. After the precipitate
of diazonium salts had appeared for 30 min, to the reaction was
added a solution of KI (12.5 g, 75 mmol) in H2O (12.5 mL). After
1 h, the reaction was warmed to room temperature and then
heated to 80 °C to evolve nitrogen gas. When no further gas was
generated, the solution was evaporated to give a yellowish solid
9b. To a solution of 9b (4.7 g) in water (22 mL) at 0 °C was added

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C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
10 N NaOH (8 mL) dropwise, and then the filtrate was collected
and evaporated. Without further purification, the residue was
mixed with excess PCl5 (3 g) and heated to 80 °C till complete liq-
uidized. Subsequent reaction with concd NH4OH (12 mL) at 0 °C for
3 h and followed by the evaporation of water afforded 11b24 in 68%
yield. Mp 174 °C. 1H NMR (200 MHz, acetone-d6) d 8.15–8.11 (m,
2H; ArH), 7.59–7.55 (m, 1H; ArH), 7.31–7.26 (m, 2H; ArH), 6.75
(s, 2H; SO2NH2). 13C NMR (100 MHz, acetone-d6) d 145.8, 142.4,
133.1, 129.0, 128.6, 91.7. MS (EI) m/z = 283 [M]+. Anal. (C6H6I-
NO2S): C, 25.46; H, 2.14; N, 4.95. Found: C, 25.44; H, 2.25; N, 4.74.
4.1.7. 2-Bromo-4-chlorobenzene-1,5-disulfonamide (16c)
To solution of 2,4-disulfamyl-5-chloroaniline (15c, 3 g,
a
10 mmol) in acetonitrile (120 mL) at 40 °C was slowly added concd
sulfuric acid (13.5 mL). After 30 min, to the solution was added so-
dium nitrite (1.32 g, 19.1 mmol) portionwise. The solution was
stirred at 0 °C for 1 h, to which was then added a solution of CuBr2
(2.46 g, 11 mmol) in water (2 mL) in portions. After 1.5 h, the reac-
tion mixture was warmed to room temperature and then heated to
80 °C to evolve nitrogen gas. When no further gas was generated,
the solution was concentrated. Purification by flash column chro-
matography on a silica gel column with hexane/EtOAc (1:1) pro-
vided a pale yellowish solid 16c in 62% yield. Mp 291–292 °C
(lit:25 290 °C). 1H NMR (400 MHz, acetone-d6) d 8.67 (s, 1H; ArH),
8.36 (s, 1H; ArH), 7.03 (br, 4 H; SO2NH2). 13C NMR (100 MHz, ace-
tone-d6) d 145.0, 144.1, 140.7, 134.0, 128.8, 96.7.
4.1.4. 2-Iodo-5-methylbenzenesulfonamide (11c)
To a homogeneous solution of 2-amino-5-methylbenzenesulf-
onic acid (8c, 20 g, 107 mmol) and sodium carbonate (5.98 g,
56 mmol) in water (120 mL) was added sodium nitrite (8.27 g,
119.8 mmol). The solution was stirred at 0 °C for 30 min, to which
was added concd HCl (21.7 mL) and crushed ice (32 g) portionwise.
After the precipitate of diazonium salts had appeared for 30 min, to
the reaction was added a solution of KI (21.4 g, 128 mmol) in H2O
(25 mL). After 1 h, the reaction was warmed to room temperature
and then gradually heated to 80 °C to evolve nitrogen gas. When no
further gas was generated, the solution was concentrated to give a
yellow solid 9c. To a solution of 9c in water (27 mL) at 0 °C was
added 10 N NaOH (15 mL) dropwise, and then the filtrate was col-
lected and then evaporated. Without further purification, the resi-
due was mixed with excess PCl5 (7.2 g) and heated to 80 °C till
complete liquefaction. Subsequent reaction with concd NH4OH
(25 mL) at 0 °C for 3 h and followed by the evaporation of water
afforded a pale yellow solid 11c in 72% yield. Mp 169–170 °C. 1H
NMR (400 MHz, acetone-d6) d 7.98 (d, J = 8.0 Hz, 1H; ArH), 7.94
(d, J = 2.0 Hz, 1H; ArH), 7.12 (dd, J = 8.0, 2.0 Hz, 1H; ArH), 6.58 (s,
2H; SO2NH2), 2.36 (s, 3H; CH3). 13C NMR (100 MHz, acetone-d6) d
146.4, 142.8, 139.6, 134.4, 130.3, 88.1, 20.7. MS (EI) m/z = 297
[M]+. Anal. (C7H8INO2S): C, 28.30; H, 2.71; N, 4.71. Found: C,
28.42; H, 2.56; N, 4.78.
4.1.8. 2,4-Disulfamyltoluene (21)
A solution of p-toluene sulfonic acid (20, 1 g) in chlorosulfonic
acid (5 mL) was heated to 150 °C for 6 h. The solution was then
poured into ice/water (6 g/3 mL) portionwise, and the precipitate
was filtered, washed with cold water (3 mL), and evaporated. Sub-
sequent treatment of the solid with concd NH4OH (13 mL) at 0 °C
for 3 h afforded the product, which was then purified by flash col-
umn chromatography on a silica gel column with hexane/EtOAc
(1:3) to provide 21 as an off-white solid in 58% yield. Mp 198 °C.
1H NMR (400 MHz, acetone-d6) d 8.42 (d, J = 2.0 Hz, 1H; ArH),
7.95 (dd, J = 8.0, 2.0 Hz, 1H; ArH), 7.57 (d, J = 8.0 Hz, 1H; ArH),
6.79 (s, 2H; SO2NH2), 6.72 (s, 2H; SO2NH2), 2.74 (s, 3H; CH3).13
C
NMR (100 MHz, acetone-d6) d 143.1, 142.8, 141.4, 133.6, 129.7,
126.1, 19.9. MS (EI) m/z = 250 [M]+. Anal. (C7H10N2O4S2): C,
33.59; H, 4.03; N, 11.19. Found: C, 33.48; H, 4.18; N, 11.35.
4.1.9. 2-(4-Bromophenylsulfanyl)-5-(hydroxycarbony) benzenes
ulfonamide (26)
A
mixture of 25 (5 g, 14.2 mmol) and KMnO4 (7.34 g,
46.5 mmol) in 5% NaOH (123 mL) was heated at reflux for
30 min. The resulting mixture was filtered, and the filtrate was
acidified to pH 2 with concd HCl. After partition with CH2Cl2/MeOH
(18 mL/2 mL), the organic layer was evaporated to give 26 as a pale
yellow solid in 66% yield. Mp 272–274 °C. 1H NMR (400 MHz,
methanol-d4) d 8.74 (d, J = 1.6 Hz, 1H; ArH), 8.41 (d, J = 8.0 Hz,
1H; ArH), 8.31 (dd, J = 8.0, 1.6 Hz, 1H; ArH), 7.84 (dd, J = 7.0,
1.9 Hz, 2H; ArH), 7.64–7.67 (m, 2H; ArH). 13C NMR (100 MHz,
methanol-d4) d 173.0, 170.8, 144.8, 142.9, 141.1, 139.6, 134.2,
133.1, 132.0, 130.9, 129.5. MS (EI) m/z = 387 [M]+. Anal.
(C13H10BrNO4S2): C, 40.22; H, 2.60; N, 3.61. Found: C, 40.54; H,
2.52; N, 3.87.
4.1.5. 4-Bromobenzene-1,3-disulfonamide (16a)
Bromobenzene (15a, 5 mL, 47.8 mmol) in chlorosulfonic acid
(15 mL) was heated to 150 °C and the reaction was stirred for
3 h. The resulting mixture was cooled in ice bath and then added
to ice/water (30 g/5 mL) dropwise. Afterward, the solid was fil-
tered, washed with cold water (6 mL), and dried in reduced pres-
sure. Subsequent treatment of the solid with concd NH4OH
(15 mL) at 0 °C for 3 h and followed by the evaporation of water
afforded 16a in 75% yield. Mp 243 °C (lit:25 243–245 °C). 1H NMR
(200 MHz, acetone-d6) d 8.53 (d, J = 2.0 Hz, 1H; ArH), 8.06–7.92
(m, 2H; ArH), 6.96 (br, 2H; SO2NH2), 6.93 (br, 2H; SO2NH2). 13C
NMR (50 MHz, acetone-d6) d 143.4, 143.0, 135.8, 130.1, 126.9,
123.0.
4.1.10. Synthesis of 4-(3-Fluoro-5-hydroxyphenyl)-4-methoxy-
3,4,5,6-tetrahydro-2H-pyran (31b)
4.1.6. 2-Bromo-5-methylsulfonylbenzenesulfonamide (16b)
4-Bromophenyl methyl sulfone (15b, 2.5 g) in chlorosulfonic
acid (5 mL) was heated to 150 °C and stirred for 3 h. The resulting
solution was cooled to 0 °C, which was then added to ice/water
(10 g/4 mL) dropwise. The precipitate was washed with cold water
(3 mL), and dried. Subsequent treatment of the solid with concd
NH4OH (11 mL) at 0 °C for 3 h afforded the product, which was
purified by flash column chromatography on a silica gel column
with hexane/EtOAc (1:2) to provide a pale yellowish solid 16b in
82% yield. Mp 238–240 °C. 1H NMR (200 MHz, acetone-d6) d
8.56–8.52 (m, 1H; ArH), 8.15–7.92 (m, 2H; ArH), 7.04 (br, 2H;
SO2NH2), 3.25 (s, 3H; SO2CH3). 13C NMR (50 MHz, acetone-d6) d
144.2, 141.5, 136.9, 132.1, 128.8, 125.7, 43.7. MS (EI) m/z = 313
[M]+. Anal. (C7H8BrNO4S2): C, 26.76; H, 2.57; N, 4.46. Found: C,
26.85; H, 2.58; N, 4.26.
4.1.10.1. (3-Benzyloxy-5-fluorophenyl) bromide.
NaH (60%
dispersion in oil, 1.5 mmol) was added portionwise to a stirred
solution of benzyl alcohol (7.09 g, 65.6 mmol) in dry THF
(50 mL). After 1 h, 1-bromo-3,5-difluorobenzene (10.55 g,
54.67 mmol) was added at a slow rate to maintain the temperature
below 40 °C. The reaction mixture was stirred at room temperature
for 4 h, added to water (25 mL), and extracted with EtOAc
(7.5 mL ꢀ 2). The combined organic phase was evaporated, and
the residue was purified by flash column chromatography over sil-
ica gel (hexane as the eluent) to give the desired bromide as color-
less oil in 82% yield. 1H NMR (400 MHz, CDCl3) d 7.40–7.45 (m, 5H;
ArH), 6.99 (s, 1H; ArH), 6.91 (d, J = 8.0 Hz, 1H; ArH), 6.67 (d,
J = 8.0 Hz, 1H; ArH), 5.02 (s, 2H; CH2), consistent with the reported
data;19 13C NMR (100 MHz, CDCl3) d 135.7, 128.6, 128.3, 127.4,
114.29, 114.26, 111.8, 111.6, 101.9, 101.7, 70.4.

C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
6323
4.1.10.2. 4-(3-Benzyloxy-5-fluorophenyl)-4-hydroxy-3,4,5,6-tet-
rahydro-2H-pyran. To a stirred solution of (3-benzyloxy-5-
liquid in 38% yield. 1H NMR (400 MHz, acetone-d6) d 6.84 (d,
J = 2.0 Hz, 1H; ArH), 6.80–6.77 (m, 1H; ArH), 6.71–6.67 (m, 1H;
ArH), 4.41 (t, J = 5.6 Hz, 2H; CH2), 3.78 (t, J = 5.6 Hz, 2H; CH2),
3.75–3.71 (m, 4H; CH2), 2.97 (s, 3H; CH3), 2.05–1.91 (m, 4H;
CH2); 13C NMR (100 MHz, acetone-d6) d 165.7, 163.3, 149.8,
149.7, 109.5, 106.2, 101.7, 75.6, 69.1, 63.8, 50.0, 35.8.MS (EI) m/
z = 332 [M]+. Anal. Calcd (C14H18BrFO3): C, 50.47; H, 5.45. Found:
C, 50.73; H, 5.25.
fluorophenyl) bromide (3.94 g, 14 mmol) in dry THF (20 mL) was
added butyl lithium (5.6 mL, 2.5 M solution in hexanes, 14 mmol)
dropwise over 1 h to maintain the reaction temperature below
ꢁ70 °C. After stirring for an additional 1 hr at ꢁ70 °C, a clear solu-
tion of 3,4,5,6-tetrahydro-2H-pyran-4-one (1.3 mL, 14 mmol) in
dry THF (3 mL) was added dropwise over 10 min. The reaction mix-
ture was maintained at ꢁ70 °C for 1 h and then allowed to warm to
0 °C over 2 h. To the mixture was added saturated NH4C1 (10 mL),
and the mixture was then partitioned with ethyl acetate (15 mL).
The organic phase was collected, evaporated, and purified by flash
column chromatography over silica gel with hexane/EtOAc (3:1) to
give the desired product as oil in 52% yield. 1H NMR (400 MHz, ace-
tone-d6) d 7.46–7.48 (m, 2H; ArH), 7.30–7.40 (m, 3H; ArH), 7.04 (d,
J = 0.8 Hz, 1H; ArH), 6.89 (dd, J = 8.4, 0.8 Hz, 1H; ArH), 6.67 (s, 1H;
ArH), 5.13 (s, 2H; CH2), 4.18 (s, 1H; OH), 4.01–4.07 (m, 2H; CH2),
3.84–3.89 (m, 2H; CH2), 3.72–3.76 (m, 2H; CH2), 1.56–1.60 (m,
2H; CH2), consistent with the reported data;19 13C NMR
(100 MHz, acetone-d6) d 137.7, 129.0, 128.5, 128.2, 108.4, 104.8,
104.6, 100.9, 100.6, 70.5, 63.9, 60.3, 39.2, 20.6.
4.1.13. 2-(3,5-Dimethoxyphenoxy)ethanethiol (33a)
According to the reported procedure,17 to a solution of 32a
(5.43 g, 20.8 mmol) in 95% ethanol (15 mL) was added thiourea
(1.9 g, 25 mmol), and the reaction was heated at reflux for 3 h.
Then, 2.5 N NaOH (12.5 mL, 1.5 equiv) was added into the mixture
at reflux for 2 h. The resulting mixture was concentrated to a small
volume and then acidified to pH 1 by 10% HCl. The mixture was
partitioned with ether (45 mL), and the organic phase was then
concentrated to give 33a as a yellowish liquid with an irritant odor
in 57% yield, which was used without further purification.
4.1.14. 4-(3-Fluoro-5-(2-mercaptoethoxy)phenyl)-4-methoxy-
3,4,5,6-tetrahydro-2H-pyran (33b)
4.1.10.3. 4-(3-Benzyloxy-5-fluorophenyl)-4-methoxy-3,4,5,6-tet
To a solution of 32b (1.61 g, 4.83 mmol) in 95% ethanol (10 mL)
was added thiourea (0.44 g, 5.8 mmol), and the reaction was heated
at reflux for 3 h. Sodium hydroxide solution (2.5 N, 1.5 equiv) was
then added into the reaction mixture, and the reaction was heated
at reflux for additional 2 h. The resulting mixture was evaporated
to a small volume and acidified to pH 1 by 10% HCl. The mixture
was partitioned with ether (20 mL), and the organic phase was con-
centrated to give 33b as a yellowish liquid with an irritant odor in
42% yield, which was used without further purification.
rahydro-2H-pyran.
To a solution of 4-(3-benzyloxy-5-fluoro-
phenyl)-4-hydroxy-3,4,5,6-tetrahydro-2H-pyran (0.66 g, 2.18 mm
ol) in THF (40 mL) at 5 °C was added NaH (60% dispersion in oil,
0.11 g, 4.41 mmol) portionwise. After 1 h, to the reaction was added
methyl iodide (0.41 mL, 6.54 mmol) over 10 min. The reaction mix-
ture was allowed to warm to room temperature for 4 h, poured into
water (10 mL), and extracted with EtOAc (15 mL ꢀ 3). The combined
organic layer was washed with water (5 mL ꢀ 2) and brine (3 mL),
and then evaporated to give the product as a yellowish solid, which
was used without further purification.
4.2. General procedures for cross-coupling aryl iodide/bromide
with thiols: from aryl iodide
4.1.10.4. 4-(3-Fluoro-5-hydroxyphenyl)-4-methoxy-3,4,5,6-tet-
rahydro-2H-pyran (31b).
To a solution of 4-(3-benzyloxy-5-
Treatment of aryl iodide (1 mmol) with various aryl thiol
(1.1 mmol) in the presence of copper iodide (0.1 mmol), neocupro-
ine (0.1 mmol), and potassium phosphate (1.5 mmol) in toluene
(10 mL) at reflux under N2 for 8 h resulted in a sticky mixture.
The resulting mixture was neutralized by 1 N HCl (1.5 mL) and
then evaporated. The residue was extracted with ethyl acetate
(15 mL ꢀ 3), and the organic layers were concentrated to give
2-aryl- or 2-alkylsulfanylbenzenesulfonamide. From aryl bromide:
A mixture of aryl bromide (1 mmol), aryl thiol (1.1 mmol), and
K2CO3 (2 mmol) in ethanol (15 mL) was heated to reflux. After
24 h, the resulting mixture was neutralized to pH 7 with saturated
NH4Cl and then evaporated. The residue was extracted with ethyl
acetate (15 mL ꢀ 3), and the organic layers were concentrated to
give 2-aryl- or 2-alkylsulfanylbenzenesulfonamide.
fluorophenyl)-4-methoxy-3,4,5,6-tetrahydro-2H-pyran (0.5 g, 1.58
mmol) in methanol (6 mL) was added 10% palladium on charcoal
(0.05 g) in a closed system, followed by the duplicate degassing
and refilling of hydrogen. After stirring under hydrogen for 1 h,
the reaction mixture was filtered through Celite, and the filtrate
was concentrated and then purified by flash column chromatogra-
phy over silica gel with hexane/EtOAc (2:1) to give 31b as a white
solid in 85% yield. 1H NMR (400 MHz, acetone-d6) d 8.77 (s, 1H;
OH), 6.73–6.72 (m, 1H; ArH), 6.65–6.62 (m, 1H; ArH), 6.52–6.48
(m, 1H; ArH), 3.758–3.68 (m, 4H; CH2), 2.96 (s, 3H; CH3), 1.91–
1.88 (m, 4H; CH2), consistent with the reported data;19 13C NMR
(100 MHz, acetone-d6) d 163.3, 109.8, 104.6, 104.4, 102.2, 101.9,
75.4, 63.7, 49.8, 35.8.
4.1.11. 2-(3,5-Dimethoxyphenoxy)ethyl bromide (32a)
A mixture of 31a (8 g, 51.9 mmol), 1,2-dibromoethane (32.17 g,
171.2 mmol) and potassium carbonate (14.34 g, 103.8 mmol) in
acetone (50 mL) was brought to reflux for 24 h. The resulting mix-
ture was evaporated, washed with water, and partitioned with
ethyl acetate (60 mL). The organic phase was then collected and
concentrated to give 32a as a yellowish liquid, which was used
without further purification.
4.3. General procedures for intramolecular cyclization 2-aryl- or
2-alkylsulfanylbenzenesulfonamide
To 2-alkyl- or 2-arylsulfanylbenzenesulfonamide in methanol/
water (15 mL/5 mL) was added a solution of bromine (1 mmol) in
methanol (1 mL), and the reaction mixture was stirred at ambient
temperature for 30 min. The precipitate was collected and washed
with H2O to give the cyclized product. Otherwise the resulting
solution was neutralized with saturated NaHCO3 (3 mL), evapo-
rated, and extracted with ethyl acetate (10 mL ꢀ 3), and the organ-
ic phase was concentrated. Purification by flash chromatography
on a silica gel column with hexane/EtOAc (1:1) provided the de-
sired product. After recrystallization in acetone/hexane, desired
products were obtained in 51–65% yields (two steps from iodo/
bromobenzenesulfonamides).
4.1.12. 4-(3-(2-Bromoethoxy)-5-fluorophenyl)-4-methoxy-3,4,5,
6-tetrahydro-2H-pyran (32b)
A mixture of 31b (2.3 g, 10.2 mmol), 1,2-dibromoethane (6.3 g,
33.5 mmol) and potassium carbonate (2.81 g, 20.3 mmol) in ace-
tone (15 mL) was heated at reflux for 24 h. The resulting mixture
was evaporated and then purified by flash column chromatography
over silica gel with hexane/EtOAc (3:1) to give 32b as a yellowish

6324
C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
4.3.1. 5-Aminosulfonyl-3-(4-bromophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (7)
4.3.7. 5-Aminosulfonyl-3-(4-isopropylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12f)
A white solid in 62% yield. Mp 301 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.61 (d, J = 1.1 Hz, 1H; ArH), 8.40 (dd, J = 8.0, 1.1 Hz,
1H; ArH), 8.24 (d, J = 8.0 Hz, 1H; ArH), 7.96 (dd, J = 6.8, 2.0 Hz,
2H; ArH), 7.82 (dd, J = 6.8, 2.0 Hz, 2H; ArH), 6.97 (s, 2H; SO2NH2).
13C NMR (100 MHz, acetone-d6) d 150.0, 139.7, 138.3, 136.7,
134.2, 132.8 130.3, 128.4, 124.8, 124.6. MS (FAB) m/z = 421
[M+H]+. Anal. (C12H9BrN2O4S3): C, 34.21; H, 2.15; N, 6.65. Found:
C, 34.05; H, 2.51; N, 6.55.
A pale yellow solid in 55% yield. Mp 245 °C. 1H NMR (400 MHz,
acetone-d6) d 8.53 (s, 1H; ArH), 8.40 (dd, J = 8.0, 1.0 Hz, 1H; ArH),
8.23 (d, J = 8.0 Hz, 1H; ArH), 7.91–7.88 (m, 2H; ArH), 7.50 (d,
J = 8.4 Hz, 2H; ArH), 7.01 (s, 2H; SO2NH2), 2.99 (septet, J = 6.9 Hz,
1H; CH), 1.25 (d, J = 6.9 Hz, 6H; CH3). 13C NMR (100 MHz, ace-
tone-d6) d 155.7, 149.8, 139.9, 137.0, 135.5, 132.4, 129.1, 128.8,
124.6, 124.4, 34.6, 23.6. MS (EI) m/z = 384 [M]+. Anal.
(C15H16N2O4S3): C, 46.86; H, 4.19; N, 7.29. Found: C, 46.77; H,
4.21; N, 7.30.
4.3.2. 5-Aminosulfonyl-3-(3-bromophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12a)
4.3.8. 5-Aminosulfonyl-3-(4-tert-butylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12g)
A yellow-brown solid in 53% yield. Mp 144 °C. 1H NMR
(400 MHz, acetone-d6) d 8.19 (d, J = 8.4 Hz, 1H; ArH), 7.89–7.86
(m, 1H; ArH), 7.72–7.69 (m, 2H; ArH), 7.58–7.57 (m, 1H; ArH),
7.53–7.52 (m, 1H; ArH), 7.44–7.41 (m, 1H; ArH), 6.77 (s, 2H;
SO2NH2). 13C NMR (100 MHz, acetone-d6) d 147.9, 137.4, 135.7,
132.5, 132.3, 131.9, 129.8, 129.4, 129.3, 126.3, 124.5, 123.2. MS
(EI) m/z = 420 [M]+. Anal. (C12H9BrN2O4S3): C, 34.21; H, 2.15; N,
6.65. Found: C, 33.96; H, 2.09; N, 6.66.
A brown solid in 52% yield. Mp 229–230 °C. 1H NMR (400 MHz,
methanol-d4) d 8.36 (d, J = 1.2 Hz, 1H; ArH), 8.31 (dd, J = 8.0, 1.2 Hz,
1H; ArH), 8.17 (d, J = 1.2 Hz, 1H; ArH), 7.74 (dd, J = 6.8, 2.0 Hz, 2H;
ArH), 7.58 (dd, J = 6.8, 2.0 Hz, 2H; ArH), 1.25 (s, 9H; CH3). 13C NMR
(100 MHz, acetone-d6) d 157.7, 149.6, 139.6, 136.7, 134.9, 132.3,
128.3, 127.9, 124.4, 124.3, 35.4, 30.8. MS (EI) m/z = 398 [M]+. Anal.
(C16H18N2O4S3): C, 48.22; H, 4.55; N, 7.03. Found: C, 47.99; H, 4.60;
N, 7.15.
4.3.3. 5-Aminosulfonyl-3-(4-fluorophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12b)
4.3.9. 5-Aminosulfonyl-3-(4-trifluoromethylphenyl)benzo
[1.3.2]dithiazo-lium ylide 1,1-dioxide (12h)
A pale brown solid in 60% yield. Mp 279–281 °C. 1H NMR
(400 MHz, acetone-d6) d 8.57 (d, J = 1.2 Hz, 1H; ArH), 8.40 (dd,
J = 8.0, 1.4 Hz, 1H; ArH), 8.25 (d, J = 8.0 Hz, 1H; ArH), 8.11–8.06
(m, 2H; ArH), 7.44–7.38 (m, 2H; ArH), 6.97 (s, 2H; SO2NH2). 13C
NMR (100 MHz, acetone-d6) d 149.9, 139.7, 136.9, 132.6, 131.7,
131.5, 124.7, 124.5, 118.5, 118.0. MS (EI) m/z = 360 [M]+. Anal.
(C12H9FN2O4S3): C, 39.99; H, 2.52; N, 7.77. Found: C, 39.90; H,
2.63; N, 7.47.
A white solid in 64% yield. Mp 277–278 °C. 1H NMR (400 MHz,
acetone-d6) d 8.71 (d, J = 1.2 Hz, 1H; ArH), 8.42 (dd, J = 8.0, 1.1 Hz,
1H; ArH), 8.29–7.99 (m, 3H; ArH), 7.98 (d, J = 8.4 Hz, 2H; ArH),
6.98 (s, 2H; SO2NH2). 13C NMR (100 MHz, acetone-d6) d 136.3,
132.9, 132.8, 128.9, 127.9, 127.9, 125.7, 124.9, 124.7, 106.4, 98.1.
MS (EI) m/z = 410 [M]+. Anal. (C13H9F3N2O4S3): C, 38.04; H, 2.21;
N, 6.83. Found: C, 37.93; H, 2.10; N, 6.47.
4.3.4. 5-Aminosulfonyl-3-(4-chlorophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12c)
4.3.10. 5-Aminosulfonyl-3-(4-methoxyphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12i)
A white solid in 59% yield. Mp 278 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.63 (d, J = 1.5 Hz, 1H; ArH), 8.41 (dd, J = 8.0, 1.5 Hz,
1H; ArH), 8.25 (d, J = 8.0 Hz, 1H; ArH), 8.04 (dd, J = 6.7, 1.9 Hz,
2H; ArH), 7.67 (dd, J = 6.7, 1.9 Hz, 2H; ArH), 7.04 (s, 2H; SO2NH2).
13C NMR (100 MHz, acetone-d6) d 139.8, 139.5, 137.6, 136.7,
132.6, 131.1, 130.1, 125.7, 124.7, 124.5. MS (FAB) m/z = 377
[M+H]+. Anal. (C12H9ClN2O4S3): C, 38.24; H, 2.41; N, 7.43. Found:
C, 37.90; H, 2.13; N, 7.46.
A white solid in 62% yield. Mp 265 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.45 (d, J = 1.1 Hz, 1H; ArH), 8.40 (dd, J = 8.0, 1.1 Hz,
1H; ArH), 8.24 (d, J = 8.0 Hz, 1H; ArH), 7.91–7.87 (m, 2H; ArH),
7.15–7.10 (m, 2H; ArH), 6.96 (s, 2H; SO2NH2), 3.86 (s, 3H; OCH3).
13C NMR (100 MHz, acetone-d6) d 164.7, 149.7, 140.1, 137.5,
132.4, 131.4, 128.8, 124.5, 124.4, 116.5, 56.2. MS (EI) m/z = 372
[M]+. Anal. (C13H12N2O5S3): C, 41.92; H, 3.25; N, 7.52. Found: C,
41.73; H, 3.32; N, 7.33.
4.3.5. 5-Aminosulfonyl-3-(4-methylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12d)
4.3.11. 5-Aminosulfonyl-3-(2,3-difluorophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12j)
A pale yellow solid in 65% yield. Mp 269 °C. 1H NMR (200 MHz,
acetone-d6) d 8.53–8.21 (m, 3H; ArH), 7.87 (dd, J = 8.0, 6.0 Hz, 2H;
ArH), 7.42 (d, J = 8.0 Hz, 2H; ArH), 7.09 (s, 2H; SO2NH2), 2.38 (s, 1H;
CH3). 13C NMR (100 MHz, acetone-d6) d 167.1, 131.1, 130.5, 129.7,
129.3, 126.5, 126.3, 124.4, 124.2, 116.1, 21.1. MS (EI) m/z = 356
[M]+. Anal. (C13H12N2O4S3): C, 43.80; H, 3.39; N, 7.86. Found: C,
43.46; H, 3.56; N, 8.18.
A white solid in 52% yield. Mp 196 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.84 (s, 1H; ArH), 8.26–8.20 (m, 2H; ArH), 7.36 (m, 1H;
ArH), 7.17–7.05 (m, 4H; ArH and SO2NH2). 13C NMR (100 MHz, ace-
tone-d6) d 148.9, 144.8, 131.3, 131.2, 130.4, 130.0, 125.2, 124.8,
113.4, 113.2, 105.6, 105.3. MS (EI) m/z = 378 [M]+. Anal.
(C12H8F2N2O4S3): C, 38.09; H, 2.13; N, 7.40. Found: C, 37.97; H,
2.10; N, 7.37.
4.3.6. 5-Aminosulfonyl-3-(4-ethylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12e)
4.3.12. 5-Aminosulfonyl-3-(2,3-dichlorophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12k)
A white solid in 60% yield. Mp 277 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.52 (s, 1H; ArH), 8.39 (dd, J = 8.0, 1.2 Hz, 1H; ArH),
8.23 (d, J = 8.0 Hz, 1H; ArH), 7.91–7.88 (m, 2H; ArH), 7.46 (d,
J = 8.4 Hz, 2H; ArH), 6.98 (s, 2H; SO2NH2), 2.70 (q, J = 7.6 Hz, 2H;
CH2), 1.20 (d, J = 7.6 Hz, 3H; CH3). 13C NMR (100 MHz, acetone-
d6) d 151.4, 149.8, 140.0, 137.2, 135.6, 132.5, 130.6, 128.8, 124.7,
124.5, 28.8, 15.3. MS (EI) m/z = 370. [M]+. Anal. (C14H14N2O4S3):
C, 45.39; H, 3.81; N, 7.56. Found: C, 45.19; H, 4.06; N, 7.53.
A brownish solid in 52% yield. Mp 193 °C. 1H NMR (400 MHz,
acetone-d6) d 8.75 (d, J = 1.2 Hz, 1H; ArH), 8.48 (dd, J = 8.0, 1.2 Hz,
1H; ArH), 8.26 (d, J = 8.0 Hz, 1H; ArH), 7.82 (d, J = 2.0 Hz, 1H;
ArH), 7.70 (d, J = 8.8 Hz, 1H; ArH), 7.56 (dd, J = 8.8, 2.0 Hz, 1H;
ArH), 7.13 (s, 2H; SO2NH2). 13C NMR (100 MHz, acetone-d6) d
149.9, 140.2, 140.0, 136.0, 135.3, 134.7, 133.1, 131.3, 130.9,
130.0, 124.9, 124.7. MS (EI) m/z = 410 [M]+. Anal. (C12H8Cl2N2O4S3):
C, 35.04; H, 1.96; N, 6.81. Found: C, 35.01; H, 1.93; N, 6.76.

C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
6325
4.3.13. 5-Aminosulfonyl-3-(2,3-dimethylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12l)
7.93 (dd, J = 6.8, 2.0 Hz, 2H; ArH), 7.84–7.80 (m, 2H; ArH), 7.03 (s,
2H; SO2NH2). 13C NMR (100 MHz, acetone-d6) d 143.7, 138.6, 138.3,
137.9, 134.2, 132.0, 130.0, 128.4, 127.8, 121.5. MS (EI) m/z = 420
[M]+. Anal. (C12H9BrN2O4S3): C, 34.21; H, 2.15; N, 6.65. Found: C,
33.87; H, 2.40; N, 6.44.
A a pale yellow solid in 64% yield. Mp 230 °C. 1H NMR
(400 MHz, acetone-d6) d 8.73 (d, J = 1.2 Hz, 1H; ArH), 8.23–8.18
(m, 2H; ArH), 7.15 (s, 1H; ArH), 7.05–7.03 (m, 2H; ArH), 6.76 (s,
2H; SO2NH2), 2.64 (s, 3H; CH3), 2.30 (s, 3H; CH3). 13C NMR
(100 MHz, acetone-d6) d 171.8, 142.0, 135.1, 132.6, 130.4, 129.6,
129.5, 128.5, 127.4, 125.5, 106.5, 98.2, 21.1, 19.2. MS (EI)
m/z = 370 [M]+. Anal. (C14H14N2O4S3): C, 45.39; H, 3.81; N, 7.56.
Found: C, 45.75; H, 3.90; N, 7.33.
4.3.20. 6-Aminosulfonyl-3-(4-isopropylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (17b)
A white solid in 61% yield. Mp 241–242 °C. 1H NMR (400 MHz,
acetone-d6) d 8.40 (d, J = 0.8 Hz, 1H; ArH), 8.32–8.25 (m, 2H;
ArH), 7.88 (d, J = 8.4 Hz, 2H; ArH), 7.50 (d, J = 8.4 Hz, 2H; ArH),
7.02 (br, 2H; SO2NH2), 2.89 (septet, J = 6.8 Hz, 1H; CH), 1.22 (d,
J = 6.8 Hz, 6H; CH3). 13C NMR (100 MHz, acetone-d6) d 155.8,
152.7, 152.2, 149.1, 131.8, 129.2, 128.6, 127.6, 121.4, 109.7, 34.7,
23.7. MS (ESI) m/z = 383 [MꢁH]+. Anal. (C15H16N2O4S3): C, 46.86;
H, 4.19; N, 7.29. Found: C, 46.77; H, 3.97; N, 7.23.
4.3.14. 5-Aminosulfonyl-3-(3,4-dichlorophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12m)
A pale yellow solid in 59% yield. Mp 198–200 °C. 1H NMR
(400 MHz, acetone-d6)
d
8.68–8.65 (m, 1H; ArH), 8.41 (d,
J = 9.6 Hz, 1H; ArH), 8.28–8.26 (m, 1H; ArH), 8.26–8.17 (m, 1H;
ArH), 8.00–7.99 (m, 1H; ArH), 7.84–7.72 (m, 1H; ArH), 6.99 (s,
2H; SO2NH2). 13C NMR (100 MHz, acetone-d6) d 136.3, 133.0,
132.8, 132.2, 130.0, 129.9, 127.91, 127.88, 126.0, 124.8, 124.6,
123.9. MS (EI) m/z = 410 [M]+. Anal. (C12H8Cl2N2O4S3): C, 35.04;
H, 1.96; N, 6.81. Found: C, 34.81; H, 2.29; N, 6.49.
4.3.21. 6-Aminosulfonyl-3-(4-tert-butylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (17c)
A yellowish solid in 62% yield. Mp 173–175 °C. 1H NMR
(400 MHz, acetone-d6) d 8.39 (s, 1H; ArH), 8.28–8.20 (m, 2 Hz;
ArH), 7.86–7.72 (m, 2H; ArH), 7.63–7.49 (m, 2H; ArH), 7.02 (br,
2H; SO2NH2), 1.92 (s, 9H; CH3). 13C NMR (100 MHz, acetone-d6) d
157.8, 150.0, 131.6, 128.1, 128.0, 127.4, 126.9, 126.3, 125.8,
121.2, 35.5, 30.3. MS (ESI) m/z = 397 [MꢁH]+. Anal. (C16H18N2O4S3):
C, 48.22; H, 4.55; N, 7.03. Found, C, 48.43; H, 4.81; N, 7.25.
4.3.15. 5-Aminosulfonyl-3-(3,4-dimethylphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12n)
A
yellow-brown solid in 55% yield. Mp 184 °C. 1H NMR
(400 MHz, acetone-d6) d 8.54 (d, J = 1.2 Hz, 1H; ArH), 8.39 (dd,
J = 8.0, 1.2 Hz, 1H; ArH), 8.21 (d, J = 8.0 Hz, 1H; ArH), 7.79 (d,
J = 1.6 Hz, 1H; ArH), 7.70 (dd, J = 8.4, 1.6 Hz, 1H; ArH), 7.35 (d,
J = 8.4 Hz, 1H; ArH), 7.01 (s, 2H; SO2NH2), 2.29 (s, 3H; CH3), 2.24
(s, 3H; CH3). 13C NMR (100 MHz, acetone-d6) d 144.0, 140.1,
137.2, 135.4, 132.3, 132.0, 129.2, 126.0, 125.7, 124.5, 124.4,
123.9, 19.7, 19.6. MS (EI) m/z = 370 [M]+. Anal. (C14H14N2O4S3): C,
45.39; H, 3.81; N, 7.56. Found: C, 45.16; H, 3.77; N, 7.66.
4.3.22. 6-Aminosulfonyl-3-(4-biphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (17d)
A white solid in 56% yield. Mp 295 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.43 (d, J = 0.8 Hz, 1H; ArH), 8.33 (m, 2 Hz; ArH), 8.06
(d, J = 8.4 Hz, 2H; ArH), 7.89 (d, J = 8.8 Hz, 2H; ArH), 7.70 (dd,
J = 6.8, 1.6 Hz, 2H; ArH), 7.51–7.41 (m, 5H; ArH and SO2NH2). 13C
NMR (100 MHz, acetone-d6) d 150.2, 139.1, 137.3, 134.9, 132.3,
131.9, 130.5, 129.9, 129.5, 128.9, 128.0, 127.7, 121.5, 114.6. MS
(ESI) m/z = 418 [M+H]+. Anal. (C18H14N2O4S3): C, 51.66; H, 3.37;
N, 6.69. Found, C, 51.83; H, 3.60; N, 6.45.
4.3.16. 5-Aminosulfonyl-3-(3,4-dimethoxyphenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (12o)
A pale yellow solid in 53% yield. Mp 261 °C. 1H NMR (400 MHz,
acetone-d6) d 8.12 (d, J = 9.6 Hz, 1H; ArH), 7.80 (dd, J = 8.0, 2.0 Hz,
1H; ArH), 7.48 (d, J = 2.0 Hz, 1H; ArH), 7.33 (s, 1H; ArH), 7.29 (s, 1H;
ArH), 6.81 (s, 1H; ArH), 6.71 (s, 2H; SO2NH2), 3.92 (s, 3H; OCH3),
3.81 (s, 3H; OCH3). 13C NMR (100 MHz, acetone-d6) d 152.6, 150.5,
148.4, 139.3, 129.9, 126.8, 125.8, 123.9, 123.0, 121.4, 120.3, 117.6,
56.6, 56.5. MS (EI) m/z = 338 [M-2ꢀMeOH]+. Anal. (C14H14N2O6S3):
C, 41.78; H, 3.51; N, 6.96. Found: C, 41.81; H, 3.45; N, 6.86.
4.3.23. 3-(4-Bromophenyl)-6-methanesulfonylbenzo[1.3.2]
dithiazolium ylide 1,1-dioxide (18a)
A white solid in 59% yield. Mp 251 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.50 (s, 1H; ArH), 8.43 (m, 2H; ArH), 7.94 (d, J = 8.4 Hz,
2H; ArH), 7.82 (d, J = 8.4 Hz, 2H; ArH), 3.35 (s, 3H; SO2CH3). 13C
NMR (100 MHz, acetone-d6) d 147.7, 140.3, 138.1, 138.0, 134.2,
133.3, 130.1, 128.4, 128.1, 123.0, 43.8. MS (EI) m/z = 419 [M]+. Anal.
(C13H10BrNO4S3): C, 37.15; H, 2.40; N, 3.33. Found: C, 37.35; H,
2.62; N, 3.27.
4.3.17. 3-Phenylbenzo[1.3.2]dithiazolium ylide 1,1-dioxide (13a)
A white solid in 64% yield. Mp 196 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.09–8.03 (m, 1H; ArH), 7.97–7.86 (m, 4H; ArH), 7.64–
7.58 (m, 3H; ArH). 13C NMR (100 MHz, acetone-d6) d 139.6,
137.1, 135.6, 134.4, 134.1, 133.7, 130.9, 127.9, 126.3, 123.7. MS
(EI) m/z = 263 [M]+. Anal. (C12H9NO2S2): C, 54.73; H, 3.44; N,
5.32. Found: C, 54.52; H, 3.63; N, 5.33.
4.3.24. 3-(4-Ethylphenyl)-6-methanesulfonylbenzo[1.3.2]
dithiazolium ylide 1,1-dioxide (18b)
A white solid in 63% yield. Mp 221–223 °C. 1H NMR (200 MHz,
acetone-d6) d 8.49 (s, 1H; ArH), 8.38 (s, 2H; ArH), 7.88 (d,
J = 8.4 Hz, 2H; ArH), 7.46 (d, J = 8.4 Hz, 2H; ArH), 3.36 (s, 3H;
SO2CH3), 2.70 (q, J = 7.6 Hz, 2H; CH2), 1.19 (t, J = 7.6 Hz, 3H; CH3).
13C NMR (50 MHz, acetone-d6) d 151.4, 147.4, 140.8, 138.3, 133.0,
130.6, 128.6, 127.9, 124.8, 122.9, 43.7, 28.9, 15.3. MS (FAB)
m/z = 370 [M+H]+. Anal. (C15H15NO4S3): C, 48.76; H, 4.09; N, 3.79.
Found, C, 49.06; H, 3.95; N, 3.52.
4.3.18. 3-(4-Bromophenyl)benzo[1.3.2]dithiazolium ylide 1,1-
dioxide (13b)
A pale yellow solid in 61% yield. Mp 170–173 °C. 1H NMR (400 MHz,
acetone-d6) d 8.13 (d, J = 8.0 Hz, 1H; ArH), 8.04 (d, J = 8.0 Hz, 1H; ArH),
7.95–7.88 (m, 4H; ArH), 7.80–7.77 (m, 2H; ArH). 13C NMR (100 MHz,
acetone-d6) d 137.0, 135.2, 134.5, 134.3, 134.0, 129.8, 127.9, 126.4,
124.8, 123.8. MS (EI) m/z = 341 [M]+. Anal. (C12H8BrNO2S2): C, 42.11;
H, 2.36; N, 4.09. Found: C, 42.32; H, 2.73; N, 4.10.
4.3.25. 6-Aminosulfonyl-3-(4-bromophenyl)-5-chlorobenzo
[1.3.2]-dithiazolium ylide 1,1-dioxide (19)
A white solid in 54% yield. Mp 279 °C. 1H NMR (400 MHz, ace-
tone-d6) d 8.55–8.50 (m, 2H; ArH), 7.95 (d, J = 8.4 Hz,2H; ArH),
7.82 (d, J = 8.4 Hz, 2H; ArH), 7.25 (s, 2H; SO2NH2). 13C NMR
(100 MHz, acetone-d6) d 146.9, 139.9, 137.7, 137.1, 135.9, 134.2,
130.2, 129.7, 128.5, 124.0. MS (EI) m/z = 454 [M]+. Anal.
4.3.19. 6-Aminosulfonyl-3-(4-bromophenyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (17a)
A pale yellow solid in 62% yield. Mp 299 °C. 1H NMR (400 MHz,
acetone-d6) d 8.40 (d, J = 1.2 Hz, 1H; ArH), 8.37–8.32 (m, 2H; ArH),

6326
C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
(C12H8BrClN2O4S3): C, 31.62; H, 1.77; N, 6.15. Found: C, 31.44; H,
2.06; N, 6.11.
solution was neutralized with 10% NaOH(aq), partitioned with
CH2Cl2/MeOH (18 mL/2 mL), and evaporated to give 23a. To 23a
in THF (20 mL) was added a solution of ethylbenzene magnesium
bromide (3.2 equiv) in THF (9.5 mL) dropwise, and the reaction
mixture was stirred at room temperature for 1 h, and then heated
to reflux for 2 h. The resulting mixture was poured into cold water
(28 mL), and the precipitate was washed with ethyl acetate
(10 mL) and then purified by gel chromatography (silica gel, 6 cm
in height, 2 cm in diameter) with hexane/ethyl acetate (1:1) to pro-
vide 24a as a white solid in 45% yield. Mp 297 °C. 1H NMR
4.3.26. 3-(4-Bromophenyl)-6-methylbenzo[1.3.2]dithiazolium
ylide 1,1-dioxide (14a)
This compound was obtained according to the general proce-
dure as a pale pink solid in 64% yield. Mp 128–130 °C. 1H NMR
(400 MHz, acetone-d6) d 7.98 (d, J = 8.0 Hz, 1H; ArH), 7.90–7.87
(m, 2H; ArH), 7.83 (s, 1H; ArH), 7.78 (dd, J = 9.4, 2.4 Hz, 2H; ArH),
7.69–7.68 (m, 1H; ArH), 2.56 (s, 3H; CH3). 13C NMR (100 MHz, ace-
tone-d6) d 146.2, 139.4, 137.5, 135.2, 134.0, 132.2, 129.7, 127.9,
125.9, 123.9, 21.1. MS (EI) m/z = 355 [M]+. Anal. (C13H10BrNO2S2):
C, 43.83; H, 2.83; N, 3.93. Found: C, 43.81; H, 3.08; N, 3.97.
(400 MHz, acetone-d6)
d
8.51–8.49 (m, 1H; ArH), 8.36 (d,
J = 1.0 Hz, 2H; ArH), 8.07 (dd, J = 6.5, 1.8 Hz, 2H; ArH), 7.57 (d,
J = 8.4 Hz, 2H; ArH), 7.08 (s, 2H; ArH), 2.79 (q, J = 7.6 Hz, 2H;
CH2), 1.29 (t, J = 7.6 Hz, 3H; CH3). 13C NMR (100 MHz, acetone-d6)
d 170.6, 151.8, 149.7, 142.5, 133.5, 132.5, 130.8, 129.6, 129.1,
128.5, 120.8, 29.4, 15.4. MS (EI) m/z = 350 [M]+. Anal.
(C15H14N2O4S2): C, 51.41; H, 4.03; N, 7.99. Found: C, 51.56; H,
4.36; N, 7.65.
4.3.27. 3-(4-Bromophenyl)-6-(hydroxycarbonyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (14b)
This compound was obtained according to the general proce-
dure as a white solid in 65% yield. Mp 291 °C. 1H NMR (400 MHz,
acetone-d6) d 8.77 (d, J = 2.0 Hz, 1H; ArH), 8.66 (d, J = 8.0 Hz, 1H;
ArH), 8.48 (dd, J = 8.0, 2.0 Hz, 1H; ArH), 7.95 (dt, J = 9.1, 2.3 Hz,
2H; ArH), 7.82–7.78 (m, 2H; ArH). 13C NMR (100 MHz, acetone-
d6) d 165.0, 143.6, 141.8, 140.6, 136.8, 134.6, 134.6, 132.9, 131.9,
130.9, 129.1. MS (EI) m/z = 368 [MꢁOH]+. Anal. (C13H8BrNO4S2):
C, 40.43; H, 2.09; N, 3.63. Found: C, 40.31; H, 2.49; N, 3.36.
4.3.31. 3-(4-Methylphenyl)benzo[1.2]isothiazole 1,1-dioxide(24c)
To saccharin (0.5 g) in THF (25 mL) was added p-tolyl magne-
sium bromide (1.1 equiv) in THF (10 mL) dropwise, and the reac-
tion was stirred at room temperature for 1 h and then heated to
reflux for 2 h. The resulting mixture was poured into cold water
(30 mL), and the precipitate was washed with ethyl acetate
(15 mL) and then purified by gel chromatography with hexane/
ethyl acetate (3:1) to provide 24c as a pale yellow solid in 70%
yield. Mp 156 °C. 1H NMR (400 MHz, acetone-d6) d 7.80 (d,
J = 2.0 Hz, 1H; ArH), 7.63–7.60 (m, 2H; ArH), 7.37–7.34 (m, 2H;
ArH), 7.28–7.27 (m, 1H; ArH), 7.19 (d, J = 7.8 Hz, 2H; ArH), 2.31
(s, 3H; CH3). 13C NMR (100 MHz, acetone-d6) d 141.3, 138.7,
138.2, 136.4, 133.6, 130.1, 130.0, 128.1, 126.3, 121.2, 20.9. MS
(EI) m/z = 257 [M]+. Anal. (C14H11NO2S): C, 65.35; H, 4.31; N,
5.44. Found: C, 65.07; H, 4.61; N, 5.76.
4.3.28. 3-(4-Bromophenyl)-6-(methoxycarbonyl)benzo[1.3.2]
dithiazolium ylide 1,1-dioxide (14c)
A solution of 14b (3 g) in thionyl chloride (8 mL) was heated at
reflux for 8 h. The resulting mixture was evaporated to a small vol-
ume. To the residue was added methanol (12 mL) at 0 °C, and the
reaction was gradually warmed to room temperature in 3 h. The
resulting mixture was evaporated in reduced pressure and then ex-
tracted with ethyl acetate (5 mL ꢀ 3). The organic layer was evap-
orated in reduced pressure to give 14c as a pale yellow solid in 53%
yield. Mp 142 °C. 1H NMR (400 MHz, acetone-d6) d 8.46 (d,
J = 8.4 Hz, 1H; ArH), 8.17 (dd, J = 8.4, 1.4 Hz, 1H; ArH), 8.02 (d,
J = 1.4 Hz, 1H; ArH), 7.92 (d, J = 8.8 Hz, 2H; ArH), 7.83 (d,
J = 8.8 Hz, 2H; ArH), 3.93 (s, 3H; OCH3). 13C NMR (100 MHz, ace-
tone-d6) d 160.7, 142.4, 139.7, 137.1, 133.24, 133.20, 132.2,
131.2, 129.4, 129.2. MS (EI) m/z = 399 [M]+. Anal. (C14H10BrNO4S2):
C, 42.01; H, 2.52; N, 3.50. Found: C, 42.30; H, 2.57; N, 3.51.
4.3.32. 3-(4-Bromophenyl)benzo[1.2]isothiazole 1,1-dioxide
(24b)
According to the above coupling reaction by p-bromophenyl
magnesium bromide (1.1 equiv), compound 24b was obtained as
a
pale yellow solid in 65% yield. Mp 109–111 °C. 1H NMR
(400 MHz, acetone-d6) d 8.13–8.07 (m, 1H; ArH), 7.99–7.90 (m,
1H; ArH), 7.83–7.81 (m, 1H; ArH), 7.71–7.56 (m, 3H; ArH), 7.45–
7.47 (m, 1H; ArH), 7.35–7.32 (m, 1H; ArH). 13C NMR (100 MHz,
acetone-d6) d 134.6, 133.8, 132.6, 130.7, 130.3, 130.1, 130.0,
128.0, 126.3, 123.4, 121.3. MS (EI) m/z = 321 [M]+. Anal.
(C13H8BrNO2S): C, 48.46; H, 2.50; N, 4.35. Found: C, 48.33; H,
2.62; N, 3.99.
4.3.29. 3-(4-Bromophenyl)-6-carbamoylbenzo[1.3.2]
dithiazolium ylide 1,1-dioxide (14d)
A solution of 14b (3 g) in thionyl chloride (8 mL) was heated at
reflux for 8 h. The resulting mixture was evaporated to a small vol-
ume. To the residue was added 35% NH4OH solution (18 mL) at
0 °C, and the reaction was gradually warmed to room temperature
in 3 h. The resulting mixture was evaporated and then extracted
with ethyl acetate (5 mL ꢀ 3). The organic layer was evaporated
in reduced pressure to give 14d as a pale yellowish solid in 52%
yield. Mp 245–246 °C. 1H NMR (400 MHz, acetone-d6) d 8.64 (d,
J = 2.0 Hz, 1H; ArH), 8.61 (d, J = 8.4 Hz, 1H; ArH), 8.02 (dd, J = 8.4,
2.0 Hz, 1H; ArH), 7.96–7.92 (m, 2H; ArH), 7.81–7.77 (m, 2H;
ArH), 6.79 (s, 2H; CO2NH2). 13C NMR (100 MHz, acetone-d6) d
171.8, 162.6, 140.9, 140.8, 134.5, 132.9, 132.5, 130.9, 130.4,
125.8, 106.5. MS (EI) m/z = 384 [M]+. Anal. (C13H9BrN2O3S2): C,
40.53; H, 2.35; N, 7.27. Found: C, 40.27; H, 2.67; N, 6.97.
4.3.33. 3-(4-Ethylphenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide
1,1-dioxide (30a)
A pale yellow solid in 60% yield. Mp 205 °C. 1H NMR (400 MHz,
acetone-d6) d 8.74 (d, J = 2.0 Hz, 1H; ArH), 8.68 (dd, J = 8.6, 2.0 Hz,
1H; ArH), 8.40 (d, J = 8.6 Hz, 1H; ArH), 7.88 (d, J = 8.4 Hz, 2H;
ArH), 7.47 (d, J = 8.8 Hz, 2H; ArH), 2.70 (q, J = 7.6 Hz, 2H; CH2),
1.18 (t, J = 7.6 Hz, 3H; CH3). 13C NMR (100 MHz, acetone-d6) d
152.3, 151.5, 141.3, 138.9, 135.0, 130.6, 129.2, 128.7, 128.1,
118.9, 29.0, 15.3. MS (EI) m/z = 336 [M]+. Anal. (C14H12N2O4S2): C,
49.99; H, 3.60; N, 8.33. Found: C, 49.74; H, 3.80; N, 8.25.
4.3.30. 6-Aminosulfonyl-3-(4-ethylphenyl)benzo[1.2]
isothiazole 1,1-dioxide (24a)
4.3.34. 3-(4-Isopropylphenyl)-6-nitrobenzo[1.3.2]dithiazolium
ylide 1,1-dioxide (30b)
A solution of 21 (0.2 g) and KMnO4 (0.42 g) in 5% NaOH (7 mL)
was heated to reflux for 30 min. The mixture was then filtered, and
the filtrate was acidified to pH 4 with 10% HCl(aq), and concentrated
to give 22. To 22 was added concd sulfuric acid (4 mL), and the
reaction mixture was stirred at room temperature for 1 h. The
A pale yellow solid in 55% yield. Mp 184 °C. 1H NMR (400 MHz,
acetone-d6) d 8.73 (d, J = 2.0 Hz, 1H; ArH), 8.69–8.65 (m, 1H; ArH),
8.39 (d, J = 8.4 Hz, 1H; ArH), 7.91–7.88 (m, 2H; ArH), 7.50 (d,
J = 8.4 Hz, 2H; ArH), 2.80 (septet, J = 6.9 Hz, 1H; CH), 1.22 (d,
J = 6.9 Hz, 6H; CH3). 13C NMR (100 MHz, acetone-d6) d 156.0,

C.-M. Tan et al. / Bioorg. Med. Chem. 19 (2011) 6316–6328
6327
152.5, 141.4, 139.1, 135.2, 129.3, 129.2, 128.8, 128.2, 119.0, 34.7,
23.6. MS (ESI) m/z = 351 [M+H]+. Anal. (C15H14N2O4S2): C, 51.41;
H, 4.03; N, 7.99. Found: C, 51.74; H, 3.83; N, 8.15.
8.10 (dd, J = 4.8, 1.5 Hz, 2H; ArH). 13C NMR (100 MHz, acetone-d6) d
153.1, 144.5, 144.4, 139.8, 131.2, 130.4, 128.0, 122.6, 119.4. MS (EI)
m/z = 309 [M]+. Anal. (C11H7N3O4S2): C, 42.71; H, 2.28; N, 13.58.
Found: C, 43.06; H, 1.99; N, 13.52.
4.3.35. 3-(4-tert-Butylphenyl)-6-nitrobenzo[1.3.2]dithiazolium
ylide 1,1-dioxide (30c)
4.3.41. 3-(2-(3,5-Dimethoxyphenoxyl)ethyl)-6-nitrobenzo[1.3.2]
dithiazo-lium ylide 1,1-dioxide (30i)
A
yellow-brown solid in 59% yield. Mp 214 °C. 1H NMR
(400 MHz, acetone-d6) d 8.73 (d, J = 2.0 Hz, 1H; ArH), 8.67 (dd,
J = 8.8, 2.0 Hz, 1H; ArH), 8.40 (d, J = 8.8 Hz, 1H; ArH), 7.92–7.88
(m, 2H; ArH), 7.66 (dd, J = 6.8, 2 Hz, 2H; ArH), 12.9 (s, 9H; CH3).
13C NMR (100 MHz, acetone-d6) d 158.1, 152.4, 141.3, 139.0,
134.8, 129.2, 128.5, 128.2, 128.1, 119.0, 35.7, 31.0. MS (ESI)
m/z = 365 [M+H]+. Anal. (C16H16N2O4S2): C, 52.73; H, 4.43; N,
7.69. Found: C, 52.45; H, 4.80; N, 7.55.
A brown solid in 53% yield. Mp 109–110 °C. 1H NMR (400 MHz,
acetone-d6) d 8.70–8.67 (m, 1H; ArH), 8.35–8.29 (m, 1H; ArH),
7.93–7.89 (m, 1H; ArH), 6.09–6.06 (m, 3H; ArH), 4.18–4.12 (m,
2H; CH2), 3.74 (s, 3H; OCH3), 3.73 (s, 3H; OCH3), 3.57–3.49 (m,
2H; CH2). 13C NMR (100 MHz, acetone-d6) d 161.7, 160.6, 132.0,
129.2, 124.0, 122.2, 113.9, 94.1, 93.3, 93.1, 70.1, 68.1, 54.7. MS
(ESI) m/z = 411 [MꢁH]+. Anal. (C16H16N2O7S2): C, 46.59; H, 3.91;
N, 6.79. Found: C, 46.62; H, 3.88; N, 6.53.
4.3.36. 3-(4-Methoxyphenyl)-6-nitrobenzo[1.3.2]dithiazolium
ylide 1,1-dioxide (30d)
4.3.42. 3-(2-(3-Fluoro-5-(4-(4-methoxytetrahydropyranyl))
phenoxy)ethyl)-6-nitro- benzo[1.3.2]dithiazolium ylide 1,1-
dioxide (30j)
A yellow solid in 62% yield. Mp 222–223 °C. 1H NMR (400 MHz,
acetone-d6) d 8.74 (d, J = 2.0 Hz, 1H; ArH), 8.66 (dd, J = 8.4, 2.0 Hz,
1H; ArH), 8.31 (d, J = 8.4 Hz, 1H; ArH), 7.88 (d, J = 6.8 Hz, 2H;
ArH), 7.13 (d, J = 6.8 Hz, 2H; ArH), 3.88 (s, 3H; OCH3). 13C NMR
(100 MHz, acetone-d6) d 164.9, 152.3, 141.7, 139.3, 131.4, 129.1,
128.2, 128.1, 118.9, 116.5, 56.2. MS (ESI) m/z = 339 [M+H]+. Anal.
(C13H10N2O5S2): C, 46.15; H, 2.98; N, 8.28. Found: C, 46.37; H,
3.10; N, 8.26.
A pale yellow-brown solid in 51% yield. Mp 166 °C. 1H NMR
(400 MHz, acetone-d6) d 8.79 (d, J = 2.8 Hz, 1H; ArH), 8.29 (dd,
J = 8.8, 2.8 Hz, 1H; ArH), 8.10 (d, J = 8.8 Hz, 1H; ArH), 6.77–6.44 (m,
3H; ArH), 4.03–3.97 (m, 2H; CH2), 3.71–3.64 (m, 4H; CH2), 3.04–
3.01 (m, 2H; CH2), 2.92 (s, 3H; CH3), 1.92–1.83 (m, 4H; CH2). 13C
NMR (100 MHz, acetone-d6) d 147.5, 144.7, 137.3, 127.9, 127.1,
124.7, 109.6, 109.1, 104.4, 104.2, 102.0, 101.8, 69.0, 63.5, 60.2,
49.7, 49.6, 35.6. MS (ESI) m/z = 485 [M+H]+. Anal. (C20H21FN2O7S2):
C, 49.58; H, 4.37; N, 5.78. Found: C, 49.61; H, 4.19; N, 5.68.
4.3.37. 3-(3,4-Dimethoxyphenyl)-6-nitrobenzo[1.3.2]
dithiazolium ylide 1,1-dioxide (30e)
A pale yellow solid in 60% yield. Mp 238–240 °C. 1H NMR
(400 MHz, methanol-d4) d 8.81 (d, J = 2.1 Hz, 1H; ArH), 8.60 (dd,
J = 8.6, 2.1 Hz, 1H; ArH), 8.36 (d, J = 8.6 Hz, 1H; ArH), 7.48 (s, 1H;
ArH), 7.30 (s, 1H; ArH), 7.17–7.11 (m, 1H; ArH), 3.84 (s, 3H;
OCH3), 3.67 (s, 3H; OCH3). 13C NMR (100 MHz, CD3OD) d 154.9,
151.2, 141.7, 138.5, 129.6, 128.4, 127.7, 127.6, 119.4, 117.2,
113.4, 111.6, 57.0, 56.5. MS (ESI) m/z = 369 [M+H]+. Anal.
(C14H12N2O6S2): C, 45.65; H, 3.28; N, 7.60. Found: C, 45.77; H,
3.50; N, 7.72.
4.4. Biology
4.4.1. Assay of human recombinant COX-2 inhibition
The COX-2 inhibition assay was performed by MDS Pharma Ser-
vices (Taipei, Taiwan) using the test method numbered 118010 for
COX-2 with human recombinant COX-2 (expressed in insect Sf21
cells). Test compounds were preincubated for 15 min at 37 °C with
COX-2 (0.11 U) in Tris–HCl buffer (pH 7.7) containing glutathione
(1 mM), phenol (500
lM), and hematin (1
lM). The enzymatic
4.3.38. 3-(4-Biphenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide
1,1-dioxide (30f)
reaction was initiated by addition of 0.3
l
M arachidonic acid. After
incubation at 37 °C for 5 min, the reaction was terminated by addi-
tion of 1 N HCl. Prostaglandin E2 (PGE2) production was quantified
to measure COX-2 activity using an enzyme immunoassay (EIA) kit
(Amersham).
A pale yellow solid in 53% yield. Mp 277–278 °C. 1H NMR
(400 MHz, acetone-d6) d 8.76 (d, J = 2.0 Hz, 1H; ArH), 8.70 (dd,
J = 8.4, 2.0 Hz, 1H; ArH), 8.47 (d, J = 8.4 Hz, 1H; ArH), 8.08 (d,
J = 8.8 Hz, 2H; ArH), 7.90 (d, J = 8.4 Hz, 2H; ArH), 7.69 (d,
J = 7.2 Hz, 2H; ArH), 7.51–7.41 (m, 3H; ArH). 13C NMR (100 MHz,
acetone-d6) d 146.9, 141.3, 139.5, 139.1, 136.9, 136.5, 129.9,
129.5, 129.3, 129.2, 129.0, 128.3, 128.0, 119.1. MS (ESI) m/z = 385
[M+H]+. Anal. (C18H12N2O4S2): C, 56.24; H, 3.15; N, 7.29. Found:
C, 56.37; H, 3.32; N, 7.15.
4.4.2. Assay of human recombinant 5-LOX inhibition
The 5-LOX inhibition assay was performed by MDS Pharma Ser-
vices (Taipei, Taiwan) with human peripheral blood mononuclear
leukocytes (PBML). Test compounds were preincubated at 37 °C
for 15 min with human PBML (5 ꢀ 106 cells/mL) in HBSS buffer
(pH 7.4). The enzymatic reaction was initiated by addition of the
4.3.39. 3-(4-Trifluoromethylphenyl)-6-nitrobenzo[1.3.2]
dithiazolium ylide 1,1-dioxide (30g)
calcium ionophore A23187 (30 lM). After incubation at 37 °C for
15 min, the reaction was terminated by addition of 1 N HCl. After
neutralization with NaOH and centrifugation, the LTB4 concentra-
tion in the supernatant was measured using an EIA kit.
A pale yellow solid in 53% yield. Mp 153–155 °C. 1H NMR
(400 MHz, acetone-d6) d 8.75 (d, J = 2.0 Hz, 1H; ArH), 8.71 (dd,
J = 8.6, 2.0 Hz, 1H; ArH), 8.58 (d, J = 8.6 Hz, 1H; ArH), 8.27 (d,
J = 8.0 Hz, 2H; ArH), 7.98 (d, J = 8.0 Hz, 2H; ArH). 13C NMR
(100 MHz, acetone-d6) d 152.6, 143.1, 140.5, 138.6, 129.5, 128.8,
128.4, 128.0, 127.9, 127.8, 119.2. MS (ESI) m/z = 377 [M+H]+. Anal.
(C13H7F3N2O4S2): C, 41.49; H, 1.87; N, 7.44. Found: C, 41.56; H,
1.80; N, 7.25.
4.4.3. In vivo inhibition of carrageenan-induced paw swelling
Male Wistar derived rats weighing 160 10 g were provided by
BioLasco Taiwan (under Charles River Laboratories Technology Li-
censee). Space allocation for 5 animals was 45 ꢀ 23 ꢀ 21 cm. All
animals were maintained in a controlled temperature (20–24 °C)
and humidity (50–80%) environment with 12 h light/dark cycles
for at least three days at Ricerca Taiwan, Ltd laboratory prior to
use. Unless animals were fasted for special purpose, free access
to standard lab chow [MF-18 (Oriental Yeast Co., Ltd, Japan)] and
reverse osmosis (RO) water was granted. All aspects of this work
including housing, experimentation and disposal of animals were
4.3.40. 6-Nitro-3-(4-pyridin)benzo[1.3.2]dithiazolium ylide 1,1-
dioxide (30h)
A yellow solid in 51% yield. Mp 185 °C. 1H NMR (400 MHz, ace-
tone-d6) d 9.10 (dd, J = 4.8, 1.5 Hz, 2H; ArH), 8.99 (d, J = 1.9 Hz, 1H;
ArH), 8.82 (dd, J = 8.6, 1.9 Hz, 1H; ArH), 8.59 (d, J = 8.6 Hz, 1H; ArH),

6328
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performed in general accordance with the Guide for the Care and
Use of Laboratory Animals (National Academy Press, Washington,
DC, 1996). Aspirin (Sigma, USA), k-Carrageenan (Fluka, Switzer-
land), Distilled water (Tai-Yu, Taiwan), Pyrogen free saline
(Sintong, Taiwan) and Tween 80 (Sigma, USA). Animal Cage (Allen-
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26G ꢀ 100 (Top Corporation, Japan), Plethysmometer (PV-01 Paw
volume apparatus, SINGA Technology Co. Taiwan), Rat oral needle
(Natsume, Japan) and Rat scale (1–1000 g, TANITA, Japan).
Male Wistar derived rats were fasted overnight prior to use.
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30 min before the right hind paw received intraplantar injection
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aspirin (150 mg/kg) was administered orally 1 h before carra-
geenan injection. Hind paw edema, as a measure of inflammation,
was recorded 3 h after carrageenan administration using a plethys-
mometer. Reduction of hind paw edema by 30% or more relative to
the vehicle group indicates acute anti-inflammatory activity.
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Acknowledgments
This work was supported by the National Science Council of the
Republic of China (Grants NSC95-2320-B002-035 and
NSC96-2320-B002-017).
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