Synthesis and antiviral/antitumor evaluation of 2-amino- and 2-carboxamido-3-arylsulfonylthiophenes and related compounds as a new class of diarylsulfones

Article abstract of DOI:10.1016/S0968-0896(00)00333-3

Based on general SARs previously described for anti-HIV-1 diarylsulfone derivatives, a series of 2-amino- and 2-carboxamido-3-arylsulfonylthiophenes has been prepared and evaluated as potential antiviral and antitumor agents. In cell culture, some of the 2-aminothiophenes exhibited moderate and selective activity against HIV-1, with 2-amino-3-(2-nitrophenylsulfonyl)thiophene (7e) being most attractive (EC₅₀= 3.8 μg/mL, CC₅₀= > 100 μg/mL). In broad-spectrum antiviral assays, the 3-arylsulfonyl-2-(trifluoroacetamido)thiophenes (8c-g) and 2-acetamido-3-arylsulfonyl-5-nitrothiophenes (9f-g) proved considerably active (IC₅₀= 0.1-10 μg/mL) against human cytomegalovirus (CMV) and/or varicella zoster virus (VZV). Based on the activity of the trifluoroacetamides, ring-modified furan, N-(substituted)pyrrole, phenyl, and 3,4-thiophene analogues were prepared, and these compounds were also active against CMV and/or VZV, with the notable exception of the 3,4-thiophene derivative. In contrast to other amines, the 2-aminopyrrole precursors (13a-d) also exhibited potent activity against CMV. Unfortunately, most of these compounds displayed significant cytotoxicity against human fibroblasts, the cells supporting CMV and VZV replication, and thus selectivity indices were low. The most notable exception to this was the naphthyl-substituted aminopyrrole 13d, which exhibited both potent (IC₅₀= 0.3 μg/mL) and selective (CC₅₀= > 50 μg/mL) activity against CMV. Finally, thiophene aryl amides 8i-k displayed moderate in vitro activity against certain leukemia, breast, and colon cancer cell lines.

Full text of DOI:10.1016/S0968-0896(00)00333-3

Bioorganic & Medicinal Chemistry 9 (2001) 1123±1132
Synthesis and Antiviral/Antitumor Evaluation of 2-Amino- and
2-Carboxamido-3-arylsulfonylthiophenes and Related Compounds
as a New Class of Diarylsulfones
Chad E. Stephens,a,y Takita M. Felder,a J. Walter Sowell, Sr.,a,* Graciela Andrei,b
Jan Balzarini,b Robert Snoeckb and Erik De Clercqb
aDivision of Medicinal Chemistry, College of Pharmacy, University of South Carolina, Columbia, SC 29208, USA
bRega Institute of Medical Research, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
Received 3 April 2000; accepted 27 November 2000
AbstractÐBased on general SARs previously described for anti-HIV-1 diarylsulfone derivatives, a series of 2-amino- and
2-carboxamido-3-arylsulfonylthiophenes has been prepared and evaluated as potential antiviral and antitumor agents. In cell
culture, some of the 2-aminothiophenes exhibited moderate and selective activity against HIV-1, with 2-amino-3-(2-nitro-
phenylsulfonyl)thiophene (7e) being most attractive (EC50=3.8 mg/mL, CC50=>100 mg/mL). In broad-spectrum antiviral assays,
the 3-arylsulfonyl-2-(tri¯uoroacetamido)thiophenes (8c±g) and 2-acetamido-3-arylsulfonyl-5-nitrothiophenes (9f±g) proved con-
siderably active (IC50=0.1±10 mg/mL) against human cytomegalovirus (CMV) and/or varicella zoster virus (VZV). Based on the
activity of the tri¯uoroacetamides, ring-modi®ed furan, N-(substituted)pyrrole, phenyl, and 3,4-thiophene analogues were prepared,
and these compounds were also active against CMV and/or VZV, with the notable exception of the 3,4-thiophene derivative. In
contrast to other amines, the 2-aminopyrrole precursors (13a±d) also exhibited potent activity against CMV. Unfortunately, most
of these compounds displayed signi®cant cytotoxicity against human ®broblasts, the cells supporting CMV and VZV replication,
and thus selectivity indices were low. The most notable exception to this was the naphthyl-substituted aminopyrrole 13d, which
exhibited both potent (IC50=0.3 mg/mL) and selective (CC50=>50 mg/mL) activity against CMV. Finally, thiophene aryl amides
8i±k displayed moderate in vitro activity against certain leukemia, breast, and colon cancer cell lines. # 2001 Elsevier Science Ltd.
All rights reserved.
Introduction
to the three NNRTIs currently approved for the treat-
ment of HIV infection,3À6 L-737,126 is more potent
than nevirapine (IC95=50 nM) and delavirdine
(IC95=37 nM) and is essentially equipotent to efavirenz
(IC95=1.7 nM). Subsequent structural modi®cation of
L-737,126 with the aim of improving oral bioavailabilty
resulted in the identi®cation of several highly potent 2-
heterocyclic indole derivatives, with the 2-imidazoyl
derivative 3 being equipotent to the parent carboxamide
while having ``improved physiochemical properties''.7
Later, Artico et al. introduced the pyrrolyl aryl sulfones
as a new group of diarylsulfones, with amino ester 4
being representative of a number of derivatives with
activity at sub-micromolar concentrations.8,9 Finally,
NCI and others have recently detailed the potent and
selective anti-HIV-1 activity of several (N-methyl-
amino)phenyl- and tetrahydroquinoline-substituted
diarylsulfones, with compound 5 being the most potent
NNRTI of the series.10
Appropriately substituted diarylsulfone derivatives have
recently emerged as a new chemical class of HIV-1 non-
nucleoside reverse transcriptase inhibitors (NNRTIs).
The ®rst examples of these compounds were described
in 1993 by the National Cancer Institute (NCI),1 result-
ing in the identi®cation of nitrophenyl phenyl sulfone
(NPPS) (1, Fig. 1) as lead compound with activity
against HIV-1 in the low micromolar range. Shortly
afterwards, Merck Research Laboratories introduced
the indole-based diarylsulfone L-737,126 (2),2 a highly
potent and selective NNRTI with anti-HIV-1 activity in
the low nanomolar range (IC95=3 nM). In comparison
*Corresponding author. Tel.: +1-803-777-2705; fax: +1-803-777-
8356; e-mail: wise@pharm.sc.edu
yPresent address: Department of Chemistry, Georgia State University,
Atlanta, GA 30303, USA.
0968-0896/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(00)00333-3

1124
C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
Figure 1. Chemical structures of HIV-active diarylsulfones.
Based on our continued interest in amino heterocycles,
and in e€orts to expand upon the general SARof the
diarylsulfone class of HIV inhibitors,8,9 we have initi-
ated a research program directed at the synthesis and
anti-HIV evaluation of various heterocyclic-based dia-
rylsulfones containing an amine or amine derivative as
the apparently required H-bonding ortho-substituent.
At the same time, we have also been interested in eval-
uating these compounds in broad-screen antiviral and
antitumor assays, an area of screening that appears to
have been very little explored for diarylsulfones. Our
initial e€orts have focused primarily on 2-amino-3-
(arylsulfonyl)thiophenes, as well as a diverse collection
of the corresponding carboxamides. Based on the
potent antiviral activity exhibited by some of the thio-
phenes (vide infra), ring-modi®ed furan, N-(sub-
stituted)pyrrole, phenyl, and 3,4-thiophene derivatives
have also been investigated. In this paper, we report on
the synthesis and biological evaluation of these new
diarylsulfones, and show that certain compounds in this
series possess signi®cant activity against HIV-1, CMV,
and/or VZV, while others are active against certain
human tumor cell lines.
Scheme 1. Reagents and conditions: (a) DBU or TEA, EtOH or
MeOH, rt; (b) acid chloride or anhydride, pyridine, MeCN, Á; (c) NBS
or NCS, CH2Cl2, Á; (d) I2, AgNO3, MeCN, rt; (e) HNO3, Ac2O, rt.
of aminothiophene 7f with potassium t-butoxide in
re¯uxing methanol (Scheme 2).
Based on the potent activity exhibited by tri-
¯uoroacetamides 8c±g of the above thiophene series
(vide infra), certain ring-modi®ed analogues of the
chloro-substituted derivative 8d were prepared. As
shown in Scheme 3, the 4,5-dimethylfuran (12) and
-pyrrole (14a±c) analogues were prepared by reaction of
the appropriate amino heterocycle (1113 or 13a±d14)
with tri¯uoroacetic anhydride in the presence of pyri-
dine.15 As shown in Scheme 4, phenyl-based tri-
¯uoroacetamide 17 was similarly obtained from aniline
16,16 which, in turn, was prepared by reduction of the
nitro derivative 1516 with iron/acetic acid. Finally, the
3,4-substituted thiophene analogue 18 and the 3-cyano-
methylsulfonyl derivatives 19a±b (Fig. 2) were available
as a result of previous work,17,18 while 5-nitro derivative
19c was prepared by reaction of 19b with acetyl nitrate.
Results and Discussion
Chemistry
The various 2-amino-3-(arylsulfonyl)thiophenes (7a±f)
were prepared by base-catalyzed condensation of an
appropriately substituted (arylsulfonyl)acetonitrile (6a±
f) with the dimer of a-mercaptoacetaldehyde (1,4-
dithiane-2,5-diol) under typical Gewald conditions11
(Scheme 1). While 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU) was employed as catalyst in most instances,
triethylamine was used to prepare ortho-substituted
derivatives 7e±f, as the more basic DBU gave mixtures
in these cases, apparently due to reaction of the pro-
duced amine with the ortho substituent. Subsequent
reaction of the 2-aminothiophenes with a carboxylic
acid chloride or anhydride in acetonitrile solution using
pyridine as base gave the various carboxamides 8a±m.
Compounds containing a halogen or nitro group at the
5-position of the thiophene ring (9a±g) were then pre-
pared by reaction of the appropriate carboxamide with
either N-chlorosuccinimide (NCS), N-bromosuccini-
mide (NBS), iodine/silver nitrate,12 or acetyl nitrate.
Finally, tricyclic sulfone 10 was obtained by cyclization
Scheme 2. Reagents and conditions: (a) t-BuOK, MeOH, Á.

C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
1125
Figure 2. Related follow-up compounds.
signi®cant activity against one or both of these viruses,
with the 4-chlorophenylsulfonyl derivative 8d being the
most active in each case (IC50<1.0 mg/mL). As such,
compound 8d was 4- to 5-fold more potent than ganci-
clovir against CMV, and was either comparable in
activity to or about 25-fold more potent than acyclovir
against VZV, depending on the TK status (TK+ or
TKÀ, respectively) of the virus strain. Unfortunately,
the activity of the tri¯uoroacetamides was only about 5-
to 40-fold lower than the cytotoxicity values, and thus
the selectivity for the two viruses (CMV, VZV) over
host cells was only modest at best. Nevertheless, the
inhibitory values for these compounds generally repre-
sent a speci®c antiviral e€ect.
Scheme 3. Reagents and conditions: (a) tri¯uoroacetic anhydride,
pyridine, MeCN, rt.
Ativiral activity
In addition to being evaluated against human immuno-
de®ciency virus type-1 (HIV-1) and type-2 (HIV-2),
each compound prepared in this study was also eval-
uated against human cytomegalovirus (CMV), varicella
zoster virus (VZV) (both TK+ and TKÀ), herpes sim-
plex virus type-1 (HSV-1) (both TK+ and TKÀ), herpes
simplex virus type-2 (HSV-2), respiratory syncytial virus
(RSV), vaccinia, vesicular stomatitis, Coxsackie B4,
Sinbis, Reo 1, Punta Toro, and parain¯uenza-3 virus.
Other types of carboxamides in the 5-unsubstituted series,
that is acetamides, aryl amides, and so forth, were inactive
against CMV and VZV. The lack of activity of the
acetamides suggests that the acidity of the amide NH
As shown in Table 1, some of the 2-aminothiophenes
(7a±f) exhibited moderate activity against the cytopathic
e€ects of HIV-1 in human T-lymphocyte (CEM/0) cells.
The most potent and selective of these compounds was
the o-nitro derivative 7e, which had an EC50 of 3.83 mg/
mL and CC50 of >100 mg/mL. This same compound
was much less active against HIV-2, a characteristic
which is common to NNRTIs.1 Although the precise
mechanism of action for 7e remains to be determined,
the viral selectivity of 7e, coupled with its structural
similarity to known NNRTIs, suggests that it may also
be acting as an inhibitor of RT. In general, the corre-
sponding carboxamides (8a±9g), including the acet-
amide (8a) of the most potent amine, either exhibited
non-selective toxicity or were inactive alltogether. The
one exception to this was formamide 8m, which showed
both moderate and selective activity. Finally, the tri-
cyclic sulfone 10 was inactive against HIV-1, although
similar tricyclics have been reported to be active in the
literature.19,20
Table 1. Anti-HIV-1 and anti-HIV-2 activity and cytotoxic proper-
ties of compounds in human T-lymphocyte (CEM) cells
Compound
Antiviral activity
EC50 (mg/mL)a
Cytotoxicity
CC50 (mg/mL)b
HIV-1 (IIIB)
HIV-2 (ROD)
7a
7b
7c
7d
7e
7f
8a
8b
8c
8d
8e
8f
8g
8h
8i
8j
8k
8l
23Æ0.35
>20
>8
12.7Æ6.7
3.83Æ2.25
11.0Æ1.4
>1.6
>40
32Æ12
>20
>8
>20
>20
55.0Æ7.1
>1.6
>40
>8
>8
>1.6
>8
>20
>8
>1.6
>40
>40
>8
40Æ0.7
>200
>8
>8
>8
>8
42Æ22
ꢀ100
40Æ6.4
>100
ꢀ100
ND
14Æ5.7
53Æ11
13Æ2.1
6Æ4
>8
>1.6
>1.6
>8
>20
>8
>1.6
>40
>40
3.9Æ0.6
20Æ9.9
ND
8.6Æ6.2
3.2Æ2.9
>200
>200
55Æ2.2
ꢀ 124
>200
6.9Æ1.6
12Æ5.6
>200
5.5Æ1.6
2.1Æ1.2
>1.6
As shown in Table 2, the 2-aminothiophenes showed
only marginal activity against CMV and VZV in human
embryonic lung (HEL) cells. However, among the vari-
ous carboxamides, tri¯uoroacetamides 8c±g displayed
>40
8m
9a
9b
9c
9d
9e
9f
18Æ0.7
>200
>8
>8
>40
>8
>0.32
0.52Æ0.28
>200
>0.32
>0.32
>200
9g
10
>200
aConcentration required to protect CEM cells against the cytopatho-
genicity of HIV by 50%.
Scheme 4. Reagents and conditions: (a) Fe, AcOH, H2O, Á; (b) tri-
¯uoroacetic anhydride, pyridine, MeCN, rt.
bConcentration required to reduce CEM cell viability by 50%.
ND, not determined.

1126
C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
may be an important structural feature of the active
tri¯uoroacetamides. This hypothesis is supported by the
fact that introduction of a nitro group at the 5-position
of the thiophene, thereby considerably increasing the
acidity of the amide proton, led to acetamides (9f±g)
with very potent activity (IC50=0.06±0.35 mg/mL).
Unfortunately, as with the tri¯uoroacetamides, the
activity of these compounds was again not well sepa-
rated from the cytotoxicity values (CC50=2±4.4 mg/
mL). As to other 5-substituted compounds, we noted
that the incorporation of a halogen into lead tri-
¯uoroacetamide 8d led to derivatives (9b, 9e) that were
less active than the parent compound, although the
opposite was the case with formamide 8m (compare to
9c). Finally, the 3-cyanomethylsulfonyl thiophene deri-
vatives (19a±c) did not exhibit any appreciable activity
against CMV or VZV (data not shown), indicating the
importance of the 3-arylsulfonyl moiety in the active
compounds.
With the surprising exception of the 3,4-substituted
thiophene isomer 18, each of the ring-modi®ed tri-
¯uoroacetamides prepared as follow-up compounds
were also active against CMV and/or VZV, although
none were more potent than the lead thiophene 8d. The
most potent of these compounds against CMV were the
N-(substituted)pyrrole derivatives 14a±c, with IC50
values at or below 1.0 mg/mL, followed by furan 12, and
®nally phenyl analogue 17. In contrast to the amino-
thiophenes and -furan, the aminopyrroles 13a±d were
also quite active against CMV, apparently a result of
the pyrrole N-substituent. The most potent of these
amines was the N-(1-naphthylmethyl)-substituted deri-
vative 13d (IC50=0.3 mg/mL). In general, the ring-mod-
Table 2. Antiviral activity and cytotoxicity of compounds against human cytomegalovirus (CMV) and varicella-zoster virus (VZV) in human
embryonic lung (HEL) cells
Compound
Antiviral activity (IC50 (mg/mL)a)
Cytotoxicity (mg/mL)
Cell growth Cell morph.
CMV
TK+VZV
TKÀVZV
b
AD-169
Davis
OKA
YS
07/1
YS
31
>50
22.14
>50
>50
>50
>50
39
CC50
MCCc
7a
7b
7c
7d
7e
7f
8a
8b
8c
8d
8e
8f
8g
8h
8i
8j
8k
8l
8m
9a
9b
9c
9d
9e
9f
9g
11
12
35
>50
>20
>20
20
>50
>5
>50
>20
0.5
32
>50
20
30
20
>50
>5
>50
>20
0.5
>50
>50
30.73
>50
>50
>50
>50
>50
9.58
0.98
3.41
>5
>50
>0.5
>50
>50
>5
>20
>50
>20
>2
11.9
>5
>2
0.07
0.26
32
10.44
9.39
4
4.3
1.6
8.71
>5
>2
>50
>50
32.67
>50
>50
32.09
>50
>50
>50
>50
>50
>50
>50
>50
>50
>50
>50
>50
>50
39
19
36
40
>50
15
>50
>50
>5
>50
>50
>50
34
26
>50
28
>50
>50
>50
>50
>50
>50
41
>50
50
ND
20
ND
>50
2
ND
>50
ND
>50
>50
>50
5
50
20
5
2
2
>50
46
20
>20
20
>20
31
>50
>50
>50
>50
>50
10.0
0.85
3.87
>5
>50
>0.5
>50
>50
>5
>20
>50
>20
>2
22.1
>5
>2
0.09
0.27
34
13.35
8.20
>20
9.22
0.96
3.73
5.83
0.89
2.49
>5
3.5
12
>5
2
11
>5
>5
>50
>0.5
>50
>50
>5
>20
>50
>20
1.20
10.9
>5
>2
0.08
0.27
29
6.60
8.52
>5
>50
>0.5
>50
>50
>5
>20
>50
>20
>2
22.7
>5
>2
0.06
0.27
31
13.77
9.42
>5
>5
>5
6.67
>5
>5
>50
>50
Ð
>0.5
>20
>50
>5
>50
>50
>50
>5
7.5
>20
>2
0.1
0.35
>20
>5
3.1
1.0
0.9
0.3
1.0
0.9
0.5
10
>0.5
>20
>50
>5
>50
>50
>50
>2
7.5
>5
>2
0.1
0.35
>20
10
4.4
2
>50
50
50
15
13
>50
50
18
50
>50
>50
>50
>50
13a
13b
13c
13d
14a
14b
14c
17
3.1
0.8
1.0
0.3
1.0
0.9
0.6
>5
16
8.08
>5
>5
>50
>50
Ð
3.3
1.2
3.62
>5
>2
39.2
>50
Ð
20
20
>50
>50
>50
>50
10
>50
>50
Ð
18
DHPGd
ACVe
>50
2.22
Ð
>50
2.33
Ð
0.66
0.90
25.94
21.90
aConcentration required to reduce virus plaque formation by 50%.
bConcentration required to reduce cell growth by 50%.
cMinimum cytotoxic concentration that causes a microscopically detectable alteration of normal cell morphology.
dDHPG, ganciclovir.
eACV, acyclovir.
ND, not determined.

C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
1127
Table 3. Activity of compounds 8d, 9b and 9e against herpes simplex virus (HSV) and virus in E6SM cells
Compound
Minimum cytotoxic
concentration (mg/mL)a
Minimum inhibitory concentrationb
Herpes simplex
virus-1 (KOS)
Herpes simplex
virus-2 (G)
Herpes simplex
virus-1 TK-VMW1837
Vaccinia
virus
8d
9b
9e
>400
80
80
>400
9.6
9.6
>400
9.6
9.6
>400
16
240
9.6
9.6
9.6
BVDU
ACG
DHPG
>400
>400
>100
0.0256
0.0768
0.0038
>400
0.0768
0.0064
0.64
0.64
0.032
1.92
>400
>100
aConcentration required to cause a microscopically detectable alteration of normal cell morphology.
bConcentration required to reduce virus-induced cytopathogenicity by 50%.
i®ed tri¯uoroacetamides and aminopyrroles were much
less active against VZV. Finally, as with the lead thio-
phene 8d, most of the ring-modi®ed compounds showed
only modest selectivity for CMV or VZV over host cells
(about 5- to 20-fold). The primary exception to this was
the naphthyl-substituted aminopyrrole 13d, which
exhibited selectivity indices for CMV of >67 (MCC)
and >167 (CC50). The positive in¯uence of the naphthyl
substituent on the selectivity index in this case remains to
be explored/con®rmed by additional SARstudies.
toxic activity, with mean panel GI50 values (mM) of
13.2, 51.3, and 72.4, respectively. In general, cytotoxi-
city was greatest against leukemia, breast, and colon
cancer cells, with pyridyl carboxamide 8i consistently
giving low mM inhibition against a variety of these cell
lines (Table 4). Interestingly, compounds 8i±k are
somewhat structurally related to a class of antitumor
sulfonamides which target the G1 phase of the cell
cycle.22
When tested against viruses other than HIV, CMV, or
VZV, the only compounds to show subtoxic activity
were the 5-substituted tri¯uoroacetamides 9b and 9e,
which exhibited slight activity against HSV-1, HSV-2,
and vaccinia virus (Table 3). Interestingly, the parent
tri¯uoroacetamide 8d was inactive against these viruses.
Conclusions
As a result of this work, several lead compounds or
groups of compounds have been identi®ed which exhibit
potent chemotherapeutic activity. Of the thiophene
series, this includes aminothiophene 7e (HIV-1), tri-
¯uoroacetamides 8c±g, nitro acetamides 9f±g (CMV
and/or VZV), and pyridyl amide 8i (leukemia, breast
and colon cancers). While the selectivity/speci®city of
the aminothiophene was satisfactory, the tri¯uoroacet-
amides and nitro acetamides exhibited relatively high
cytotoxicity towards host cells, and thus their selectivity
was low. Of the ring-modi®ed compounds, several tri-
¯uoroacetamides (12, 14a±c and 17) and several N-sub-
stituted aminopyrroles (13a±d) also exhibited potent
activity against CMV and/or VZV, while in most cases
displaying limited selectivity. Most interestingly, the
naphthyl-substituted aminopyrrole 13d showed both
potent and selective activity against CMV. Finally, this
work indicates that the broad-screen antiviral/anti-
tumor evaluation of diarylsulfones should continue to
be explored, with particular focus on CMV and VZV.
Such e€orts, along with mechanism of action studies for
the more potent compounds of this study, are currently
being pursued.
Antitumor activity
Several of the aminoheterocycles (7a, 11 and 13a) and
carboxamides (8a±l) were chosen for evaluation in the
NCI in vitro human tumor cell line screen.21 Of these
compounds, aryl amides 8i±k showed moderate cyto-
Table 4. Activity of aryl amides 8i±k against various cell lines of
leukemia, breast cancer, and colon cancer (GI50, mM)a
Panel/Cell line
8i
8j
8k
Leukemia
K-562
SR5.25
4.37
1.10
1.48
ND
5.62
MOLT-4
5.31
7.50
>100
ND
>100
>100
RPMI-8226
Breast cancer
MDA-N
MDA-MB-435
NCI/ADR-RES
MCF7
MDA-MB-231/ATCC
Colon cancer
COLO 205
KM12
HT29
HCT-15
1.02
1.86
3.94
8.13
3.72
4.37
>100
>100
12.9
3.02
3.39
67.6
>100
4.9
69.2
Experimental
Chemistry
3.89
4.62
5.62
5.13
6.61
5.96
77.6
>100
>100
>100
>100
>100
>100
ND
>100
7.59
>100
>100
Melting points were determined on an Electrothermal
1
HCT-116
SW-620
apparatus (open capillary) and are uncorrected. The H
NMRand mass spectra were obtained using a Brucker
AM-300 or WH-400 spectrometer and VG-70 SQ
instrument, respectively. Infrared (IR) spectra were
determined on a Beckman Acculab 4 spectrophotometer
using KBr pellets unless otherwise indicated. Thin layer
aGI50, concentration required to inhibit growth of cell line by 50%.
Values for 8i represent the average of duplicate assays; those for 8j±k
represent single assays.
ND, not determined.
Data kindly provided by NCI.

1128
C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
chromatography (TLC) was performed on Baker
Si250F silica plates. Column chromatography was con-
ducted on Fisher Selecto 60 (230±400 mesh) silica gel.
Elemental analyses were performed by Atlantic Micro-
lab, Inc., Norcross, GA. Reaction temperatures given
are indicative of the oil bath. Acetonitrile, pyridine, and
triethylamine were distilled from calcium hydride and
stored over molecular sieves (4 A). (Arylsulfonyl)aceto-
nitriles 6b±f were prepared according to a previous
paper,17 and references contained therein. All other
reagents were obtained from Aldrich and used as
received.
52.15; H, 4.38; N, 5.53; S, 25.31. Found: C, 52.04; H,
4.45; N, 5.51; S, 25.43.
2-Amino-3-(2-nitrophenylsulfonyl)thiophene (7e). Pre-
pared using triethylamine in place of DBU; following
silica gel ®ltration, the product was crystallized from
EtOAc as a yellow solid in 81% yield, mp 162±163 ꢁC
(EtOAc, yellow crystals). 1H NMR(CDCl 3) d 5.63 (br s,
2H), 6.29 (d, 1H), 6.79 (d, 1H), 7.69±7.74 (m, 3H), 8.17±
8.19 (m, 1H). IRv 3430 and 3340 (NH ) cmÀ1. Anal.
2
calcd for C10H8N2O4S2: C, 42.24; H, 2.84; N, 9.86; S,
22.55. Found: C, 42.33; H, 2.80; N, 9.86; S, 22.49.
General procedure for the preparation of 2-amino-3-
(arylsulfonyl)thiophenes (7a±f). Example: 2-amino-3-
(phenylsulfonyl)thiophene (7a). To a suspension of
(phenylsulfonyl)-acetonitrile (2.27 g, 12.5 mmol) and
1,4-dithiane-2,5-diol (1.00 g, 6.57 mmol) in absolute
ethanol (15 mL) was added 1,8-diazabicyclo[5.4.0]-
undec-7-ene (DBU) (0.10 g) and the mixture was stirred
overnight (16 h) at room temperature. The resulting
dark solution was concentrated in vacuo, and the
remaining oil was dissolved in a minimum amount of
EtOAc and ®ltered through a short silica plug eluting
with hexanes/EtOAc (2/3). Following evaporation of
the solvent, the oily solid was crystallized from metha-
nol (20 mL) to give tan crystals (1.95 g, 65%), mp 110±
2-Amino-3-[(2-methoxycarbonyl)phenylsulfonyl]thiophene
(7f). Obtained as an amber colored oil in 83% yield
using triethylamine in place of DBU and MeOH as sol-
1
vent. H NMR(CDCl ) d 3.95 (s, 3H), 5.08 (br s, 2H),
3
6.25 (d, 1H), 6.85 (d, 1H), 7.50±7.60 (m, 3H), 7.93±7.96
(m, 1H). IRv 3465 and 3360 (NH ), 1725 (CO) cmÀ1
.
2
Anal. calcd for C12H11NO4S2: C, 48.47; H, 3.73; N,
4.71; S, 21.56. Found: C, 48.30; H, 3.80; N, 4.59; S,
21.38.
2-Acetamido-3-(2-nitrophenylsulfonyl)thiophene (8a). To
an ice-chilled solution of 7e (0.57 g, 2.0 mmol) in aceto-
nitrile (10 mL) was added pyridine (0.174 g, 2.2 mmol)
followed by acetyl chloride (0.24 g, 3.0 mmol) and the
mixture was heated at 90±100 ꢁC for 30 min. The solu-
tion was then poured over ice/water with stirring to give
a solid which was collected, rinsed with water. Recrys-
tallization from methanol (10 mL) gave ®ne olive green
crystals (0.49 g, 75%), mp 147±148 ꢁC. 1H NMR
(CDCl3) d 2.34 (s, 3H), 6.81 (d, 1H), 6.95 (d, 1H), 7.76±
7.82 (m, 3H), 8.26 (d, 1H), 10.04 (br s, 1H). IRv 3355
(NH), 1685 (CO) cmÀ1. Anal. calcd for C12H10N2O5S2:
C, 44.16; H, 3.09; N, 8.59; S, 19.65. Found: C, 44.15; H,
3.05; N, 8.54; S, 19.65.
111 ꢁC. H NMR(CDCl ) d 5.52 (br s, 2H), 6.25 (d,
1
3
1H), 6.79 (d, 1H), 7.45±7.54 (m, 3H), 7.89±7.91 (m, 2H).
IRv 3445 and 3340 (NH 2) cmÀ1. Anal. calcd for
C10H9NO2S2: C, 50.19; H, 3.79; N, 5.85; S, 26.79.
Found: C, 50.11; H, 3.74; N, 5.81; S, 26.68.
The following aminothiophenes were prepared accord-
ingly.
2-Amino-3-(4-chlorophenylsulfonyl)thiophene (7b). This
compound precipitated from the reaction mixture and
was isolated by ®ltration as a tan solid in 82% yield, mp
The following carboxamides were prepared accordingly.
156±157 ꢁC (MeOH, tan crystals). H NMR(CDCl ) d
1
3
5.56 (br s, 2H), 6.27 (d, 1H), 6.77 (d, 1H), 7.44 (d, 2H),
7.82 (d, 2H). IRv 3430 and 3320 (NH ) cmÀ1. Anal.
calcd for C10H8ClNO2S2: C, 43.87; H, 2.95; Cl, 12.95;
N, 5.12; S, 23.42. Found: C, 43.81; H, 2.96; Cl, 13.01; N,
5.08; S, 23.35.
2-Acetamido-3-(4-chloropheꢁnylsulfonyl)thiophene
(8b).
1
Yield 68%; mp 161±161.5 C (EtOH, tan crystals). H
NMR(CDCl 3) d 2.31 (s, 3H), 6.80 (d, 1H), 6.93 (d, 1H),
7.48 (d, 2H), 7.81 (d, 2H), 10.32 (br s, 1H). IRv
2
3325 (NH), 1665 (CO) cmÀ1
. Anal. calcd for
C12H10ClNO3S2: C, 45.64; H, 3.19; Cl, 11.23; N, 4.44; S,
20.31. Found: C, 45.57; H, 3.23; Cl, 11.30; N, 4.50; S,
20.44.
2-Amino-3-(4-¯uorophenylsulfonyl)thiophene (7c). Tri-
turation of the oily residue following silica gel ®ltration
with diethyl ether/hexanes gave a tan solid (58% yield),
mp 104±107 ꢁC. H NMR(CDCl ) d 4.8±5.8 (very br
2-Benzamido-3-(phenylsulfonyl)thiophene (8j). Prepared
usinꢁg benzoyl chloride (1.2 equiv). Yield 53%; mp 161±
1
3
signal, NH2), 6.26 (d, 1H), 6.76 (d, 1H), 7.11±7.19 (m,
1
2H), 7.87±7.94 (m, 2H); the amine gave a very broad
absorption between 4.8 and 5.8. IR(neat ®lm as oil,
NaCl) v 3450 and 3340 (NH2) cmÀ1. Anal. calcd for
C10H8FNO2S2: C, 46.68; H, 3.13; N, 5.44; S, 24.92.
Found: C, 46.75; H, 3.19; N, 5.39; S, 25.01.
163 C (MeOH, tan crystals). H NMR(DMSO- d6) d
7.22±7.26 (dd, 2H), 7.63±7.75 (m, 6H), 7.98 (t, 2H), 8.08
(t, 2H), 11.23 (br s, 1H). IRv 3350 (NH), 1665 (CO)
cmÀ1. Anal. calcd for C17H13NO3S2: C, 59.46; H, 3.81;
N, 4.08; S, 18.67. Found: C, 59.31; H, 3.82; N, 4.03; S,
18.62.
2-Amino-3-(4-methylphenylsulfonyl)thiophene (7d). Obt-
ained as a tan solid in 74% yield following silica gel
®ltration; mp 131±132 ꢁC (MeOH, tan crystals). 1H
NMR(DMSO- d6) d 2.34 (s, 3H), 6.37 (d, 1H), 6.75 (d,
1H), 6.95 (s, 2H), 7.36 (d, 2H), 7.79 (d, 2H). IRv 3440
and 3330 (NH2) cmÀ1. Anal. calcd for C11H11NO2S2: C,
2-Benzamido-3-(4-methylphenylsulfonyl)thiophene (8k).
Prepared using benzoyl chloride (1.2 equiv). Yield
49%; mp 199±200 ꢁC (MeOH, ¯u€y tan needles). H
1
NMR(CDCl 3) d 2.39 (s, 3H), 6.84 (d, 1H), 7.01 (d, 1H),
7.29 (d, 2H), 7.54±7.63 (m, 3H), 7.79 (d, 2H), 8.02 (d,

C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
1129
2H), 11.41 (br s, 1H). IRv 3350 (NH), 1670 (CO) cm À1
Anal. calcd for C18H15NO3S2 0.2H2O: C, 59.88; H,
4.30; N, 3.88; S, 17.76. Found: C, 59.55; H, 4.39; N,
3.89; S, 17.82.
.
2H), 7.52 (d, 2H), 7.83 (d, 2H), 11.29 (br s, 1H). IRv
3280 (NH), 1715 (CO) cmÀ1
Anal. calcd for
C12H7ClF3NO3S2: C, 38.98; H, 1.91; Cl, 9.59; N, 3.79;
S, 17.34. Found: C, 38.86; H, 1.86; Cl, 9.61; N, 3.73; S,
17.26.
ꢂ
.
2 - (Methoxycarbonyl)acetamido - 3 - (phenylsulfonyl)thio-
phene (8l). Prepared using methyl malonyl chloride (1.1
equiv). After diluting with ice/water, the resulting oil
was extracted into EtOAc and washed with sat.
NaHCO3 solution, followed by 1 N HCl, and ®nally
brine. After drying (MgSO4), the organic layer was
concentrated to give an orange oil, which was crystal-
lized from a small amount of methanol as a tan solid.
Recrystallization from methanol gave tan crystals (yield
46%), mp 102±103 ꢁC. 1H NMR(CDCl 3) d 3.63 (s, 2H),
3.87 (s, 3H), 6.82 (d, 1H), 7.05 (d, 1H), 7.49±7.60 (m,
3H), 7.94±7.96 (dd, 2H), 11.55 (br s, 1H). IRv 3340
(NH), 1735 (CO), 1685 (CO) cmÀ1. Anal. calcd for
C14H13NO5S2: C, 49.55; H, 3.86; N, 4.13; S, 18.89.
Found: C, 49.60; H, 3.86; N, 4.10; S, 18.96.
3 - (4 - Fluorophenylsulfonyl) - 2 - (tri¯uoroacetamido)thio-
phene (8e). Yield 90%; mp 92±93 ꢁC (cyclohexane,
1
¯u€y tan needles). H NMR(CDCl ) d 7.00±7.05 (dd,
3
2H), 7.20±7.26 (m, 2H), 7.90±7.95 (m, 2H), 11.31 (br s,
1H). IRv 3280 (NH), 1710 (CO) cm À1. Anal. calcd for
C12H7F4NO3S2: C, 40.79; H, 2.00; N, 3.96; S, 18.15.
Found: C, 40.85; H, 2.00; N, 3.91; S, 18.24.
3-(4 -Methylphenylsulfonyl) -2-(tri¯uoroacetamido)thio-
phene (8f). Yield 76%; mp 118±119 ꢁC (MeOH/water,
1
¯u€y tan needles). H NMR(CDCl ) d 2.42 (s, 3H),
3
6.98 (d, 1H), 7.04 (d, 1H), 7.33 (d, 2H), 7.77 (d, 2H),
À1
11.37 (br s, 1H). IRv 3280 (NH), 1730 (CO) cm
.
Anal. calcd for C13H10F3NO3S2: C, 44.69; H, 2.89; N,
4.01; S, 18.35. Found: C, 44.71; H, 2.92; N, 4.02; S,
18.38.
3 - Phenylsulfonyl - 2 - (3 - pyridylcarboxamido)thiophene
(8i). To a solution of 7a (1.95 g, 8.15 mmol) in acetoni-
trile (17 mL) was added pyridine (1.64 g, 20.7 mmol)
followed by nicotinoyl chloride hydrochloride (1.84 g,
10.3 mmol) and the mixture was stirred overnight (14 h)
at room temperature. The resulting suspension was
concentrated in vacuo to near dryness, diluted with aq
NaHCO3, stirred, and ®ltered to give a tan solid, which
showed two spots on TLC (hexanes/EtOAc, 1/1). The
crude product was stirred in methanol (20 mL) and
recollected to give the near pure compound. Recrys-
tallization from methanol (220 mL) with concentration
to ca. 80 mL after ®ltering gave tan/colorless needles
3-[(2-Methoxycarbonyl)phenylsulfonyl]-2-(tri¯uoroacet-
amido)thiophene (8g). Yield 66%; mp 142±143 ꢁC
1
(MeOH/water, tan needles). H NMR(CDCl ) d 3.91
3
(s, 3H), 6.97 (d, 1H), 7.07 (d, 1H), 7.68±7.71 (m, 3H),
8.20±8.25 (m, 1H), 11.12 (br s, 1H). IRv 3290 (NH),
1740 (ridge), and 1720 (CO) cmÀ1. Anal. calcd for
C14H10F3NO5S2: C, 42.75; H, 2.56; N, 3.56; S, 16.30.
Found: C, 42.70; H, 2.42; N, 3.59; S, 16.46.
3-(4-Chlorophenylsulfonyl) -2-(hepta¯uorobutyramido)-
thiophene (8h). Prepared using hepta¯uorobutyric
anhydride (1.5 equiv). After diluting with ice/water, the
resulting gummy solid was extracted into EtOAc, dried
(MgSO4), and concentrated in vacuo. The residue was
chromatographed on silica eluting with hexanes/EtOAc
(3/1) (Rf 0.54) to give a light-tan solid (yield 60%), mp
105±106 ꢁC (cyclohexane, ¯u€y white needles). 1H
(1.05 g, 37%), mp 180.5±181.5 ꢁC. H NMR(CDCl ) d
1
3
6.89 (d, 1H), 7.04 (d, 1H), 7.47±7.62 (m, 4H), 7.90 (t,
2H), 8.27±8.30 (m, 1H), 8.85 (m, 1H), 9.27 (s, 1H), 11.55
(br s, 1H). IRv 3330 (NH), 1670 (CO) cm À1. Anal.
calcd for C16H12N2O3S2: C, 55.80; H, 3.51; N, 8.14; S,
18.62. Found: C, 55.53; H, 3.57; N, 8.07; S, 18.76.
NMR(CDCl ) d 7.02±7.07 (dd, 2H), 7.52 (d, 2H), 7.81
3
3-Phenylsulfonyl-2-(tri¯uoroacetamido)thiophene
(8c).
(d, 2H), 11.39 (br s, 1H). IRv 3325 (NH), 1715 (CO)
cmÀ1. Anal. calcd for C14H7ClF7NO3S2: C, 35.79; H,
1.50; Cl, 7.55; N, 2.98; S, 13.65. Found: C, 35.85; H,
1.45; Cl, 7.62; N, 3.03; S, 13.73.
To an ice-chilled solution of 7a (0.239 g, 1.0 mmol) in
acetonitrile (5 mL) was added pyridine (0.12 g,
1.5 mmol) followed by tri¯uoroacetic anhydride (0.38 g,
1.8 mmol) and the mixture was stirred overnight at
room temperature (16±18 h). The solution was then
partially concentrated in vacuo and poured over ice/
water to give a tan solid, which was collected, rinsed
with water, and air dried (0.30 g, 89%). Recrystalliza-
tion from ꢁmethanol/water (8/1) gave tan needles, mp
102±102.5 C. 1H NMR(CDCl 3) d 7.01 (d, 1H), 7.06 (d,
1H), 7.52±7.66 (m, 3H), 7.89±7.92 (m, 2H), 11.37 (br s,
1H). IRv 3275 (NH), 1715 (CO) cm À1. Anal. calcd for
C12H8F3NO3S2: C, 42.98; H, 2.40; N, 4.18; S, 19.12.
Found: C, 43.05; H, 2.35; N, 4.15; S, 18.99.
2-Formamido-3-[2-(methoxycarbonyl)phenylsulfonyl]thio-
phene (8m). As in the literature,9 the formic acetic
anhydride reagent was prepared by adding formic acid
(95±97%) (0.16 g) to acetic anhydride (0.30 g) followed
by stirring at room temperature for 1 h. A solution of 7f
(0.297 g, 1.0 mmol) in acetonitrile (5 mL) was then
added to the anhydride and the mixture was stirred
overnight at room temperature. Concentration in vacuo
gave an oily solid, which was triturated with MeOH/
water (1/1, 3±4 mL), collected, and air dried. Recrys-
tallization from MeOH/water (4/1) gave a ¯u€y tan
The
following
tri¯uoracetamides
and
¯uorobutyramide were prepared accordingly.
hepta-
solid (0.225 g, 69%), mp 116±117 ꢁC. 1H NMR(CDCl )
3
d 3.93 (s, 3H), 6.85 (d, 1H), 7.08 (d, 1H), 7.59±7.66 (m,
3H), 8.03±8.06 (m, 1H), 8.56 (s, 1H), 10.41 (br s, 1H).
À1
3 - (4 - Chlorophenylsulfonyl) - 2 - (tri¯uoroacetamido)thio-
phene (8d). Yield 78%; mp 130±130.5 ꢁC (MeOH, long
IRv 3250 (NH), 1725 (CO), 1680 and 1650 (CO) cm
.
Anal. calcd for C13H11NO5S2: C, 47.99; H, 3.41; N,
4.31; S, 19.71. Found: C, 48.08; H, 3.40; N, 4.37; S, 19.64.
1
colorless needles). H NMR(CDCl ) d 7.01±7.06 (dd,
3

1130
C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
2-Acetamido-5-bromo-3-(4-chlorophenylsulfonyl)thio-
phene (9a). To a solution of 8b (0.632 g, 2.0 mmol) in
dichloromethane (15 mL) was added N-bromosuccini-
mide (NBS) (0.356 g, 2.0 mmol) and the mixture was
stirred at gentle re¯ux with TLC monitoring. After 3±
4 h, a small amount of starting material remained, and
thus additional NBS (0.018 g, 0.1 mmol) was added and
stirring was continued overnight at room temperature.
Filtration through silica with EtOAc/hexanes (1/1) fol-
lowed by concentration gave an oily solid. Recrystalli-
zation from ethanol (40 mL) gave light-tan crystals
(0.59 g, 75%). A second recrystallization from methanol
gave o€-white prisms, mp 169±171 ꢁC. 1H NMR
(CDCl3) d 2.32 (s, 3H), 6.88 (s, 1H), 7.48 (d, 2H), 7.79
(d, 2H), 10.31 (br s, 1H). IRv 3325 (NH), 1690 (CO)
cmÀ1. Anal. calcd for C12H9BrClNO3S2: C, 36.52; H,
2.30; N, 3.55; S, 16.25. Found: C, 36.58; H, 2.35; N,
3.48; S, 16.31.
iodine, crystalline silver nitrate (0.041 g, 0.24 mmol) was
added causing the formation of a yellow precipitate.
After stirring for 20 min, the precipitate was ®ltered o€
and the solution was diluted with water to give a tan
solid. Recrystallization of the collected product from
methanol/water (10/1) gave ¯u€y light-tan needles
(0.056 g, 56%), mp 181±182 ꢁC. 1H NMR(CDCl 3) d
7.16 (s, 1H), 7.55 (d, 2H), 7.82 (d, 2H), 11.32 (br s, 1H).
IRv 3290 (NH), 1715 (CO) cm À1. Anal. calcd for
C12H6ClF3INO3S2: C, 29.08; H, 1.22; N, 2.83; S, 12.94.
Found: C, 29.10; H, 1.20; N, 2.79; S, 12.87.
2-Acetamido-3-(4-chlorophenylsulfonyl)-5-nitrothiophene
(9f). A suspension of 8b (0.632 g, 2.0 mmol) in acetic
anhydride (4 mL) was treated in portions with a chilled
mixture of acetyl nitrate (prepared by adding cold
HNO3 (70%) (0.36 g) to cold acetic anhydride (3.0 g))
and stirred at room temperature for 1 h. The resulting
solution was poured over ice and stirred for 15 min to
give a solid, which was collected, washed with water,
and air dried. Recrystallization from methanol (100 mL,
followed by partial concentration) gave ¯u€y peach
colored needles (0.515 g, 71%), mp 190±192 ꢁC. 1H
NMR(CDCl 3) d 2.40 (s, 3H), 7.55 (d, 2H), 7.80 (s, 1H),
7.84 (d, 2H), 10.57 (br s, 1H). IRv 3315 (NH), 1695
(CO) cmÀ1. Anal. calcd for C12H9ClN2O5S2: C, 39.95;
H, 2.51; N, 7.77; S, 17.77. Found: C, 39.94; H, 2.48; N,
7.75; S, 17.70.
Compounds 9b±d were prepared accordingly with the
noted modi®cations.
5 - Bromo - 3 - (4 - chlorophenylsulfonyl) - 2 - (tri¯uoroacet-
amido)thiophene (9b). Reaction of 8d (0.185, 0.5 mmol)
with 1.0 equiv of NBS for 45 min gave the product as a
pale-purple solid (yield 85%) after silica gel ®ltration;
mp 148±148.5 ꢁC (MeOH/water, lavender needles). H
1
NMR(CDCl 3) d 7.00 (s, 1H), 7.55 (d, 2H), 7.82 (d, 2H),
À1
11.30 (br s, 1H). IRv 3280 (NH), 1715 (CO) cm
.
Anal. calcd for C12H6BrClF3NO3S2: C, 32.12; H, 1.35; N,
3.12; S, 14.29. Found: C, 32.16; H, 1.36; N, 3.06; S, 14.20.
2-Acetamido-3-(4-¯uorophenylsulfonyl)-5-nitrothiophene
(9g). Reaction of aminothiophene 7c (0.643 g, 2.5 mmol)
with acetyl chloride/pyridine according to the procedure
described for the synthesis of 8a gave 2-acetamido-3-
(4-¯uorophenylsulfonyl)thiophene as a yellow/brown
solid. Subsequent reaction of this acetamide with acetyl
nitrate as described above gave the title compound as a
yellow/orange solid (0.59 g, 69% overall), mp 187±
5-Bromo-2-formamido-3-[2-(methoxycarbonyl)phenylsulf-
onyl]thiophene (9c). Reaction of 8m (0.108 g, 0.33 mmol)
with 1.0 equiv of NBS for 45 min followed by heating
with another 0.15 equiv of NBS for 15 min gave a ¯u€y
orange/tan solid following recrystallization from
methanol/water. Yield 47%; mp 131±131.5 ꢁC, with
189 ꢁC (MeOH, gold prisms). H NMR(CDCl ) d 2.41
1
3
ꢁ
1
partial melting at 110 C. H NMR(CDCl ) d 3.94 (s,
(s, 3H), 7.25±7.30 (m, 2H), 7.81 (s, 1H), 7.94±7.97 (m,
2H), 10.60 (br s, 1H). IRv 3315 (NH), 1695 (CO) cm À1
.
Anal. calcd for C12H9FN2O5S2: C, 41.85; H, 2.63; N,
8.14; S, 18.62. Found: C, 41.95; H, 2.58; N, 8.07; S, 18.51.
3
3H), 7.06 (s, 1H), 7.64±7.69 (m, 3H), 8.05±8.08 (m, 1H),
8.53 (s, 1H), 10.47 (br s, 1H). IRv 3320 (NH), 1730
(CO), 1680 (ridge), 1665 (CO) cmÀ1. Anal. calcd for
C13H10BrNO5S2: C, 38.62; H, 2.49; N, 3.46; S, 15.86.
Found: C, 38.69; H, 2.46; N, 3.48; S, 15.97.
Thieno[3,2-b][1,4]benzothiazepin-9(10H)-one 4,4-dioxide
(10). To a solution of aminothiophene 7f (0.297 g,
1.0 mmol) in methanol (5 mL) was added potassium t-
butoxide (0.135 g, 1.2 mmol) and the mixture was heated
at 60±65 ꢁC for 1.5 h. After concentration, the residue
was dissolved in a minimum amount of water and
extracted with EtOAc. The aqueous layer was acidi®ed
with concentrated HCl/ice to give a tan solid, which was
collected, rinsed with water, and air dried (0.15 g, 57%).
Recrystallization from methanol (50 mL, with con-
centration by half after ®ltering) gave ¯u€y tan needles,
2-Acetamido-5-chloro-3-(2-nitrophenylsulfonyl)thiophene
(9d). Reaction of 8a (0.16 g, 0.5 mmol) overnight with
1.0 equiv of N-chlorosuccinimide (NCS) at gentle re¯ux
gave a 1/1 mixture of product and starting material
according to TLC. Addition of another 1.0 equiv of
NCS plus a few drops of methanesulfonic acid, followed
by continued heating for 3±4 h led to complete reaction.
Yield 44%; mp 202±204 ꢁC (MeOH/water, ¯u€y pale-
1
orange needles). H NMR(CDCl ) d 2.33 (s, 3H), 6.77
3
mp 313±315 ꢁC. H NMR(DMSO- d6) d 7.20 (d, 1H),
1
(s, 1H), 7.80±7.83 (m, 3H), 8.25 (t, 1H), 10.03 (br s, 1H).
IRv 3315 (NH), 1675 (CO) cm À1. Anal. calcd for
C12H9ClN2O5S2: C, 39.95; H, 2.51; N, 7.77; S, 17.77.
Found: C, 40.12; H, 2.54; N, 7.64; S, 17.71.
7.35 (d, 1H), 7.86±8.00 (m, 4H), 11.99 (br s, 1H). IRv
3180 (NH), 1645 (CO) cmÀ1
. Anal. calcd for
C11H7NO3S2: C, 49.80; H, 2.66; N, 5.28; S, 24.17.
Found: C, 49.88; H, 2.66; N, 5.28; S, 24.08.
3-(4-Chlorophenylsulfonyl)-5-iodo-2-(tri¯uoroacetamido)-
thiophene (9e). To a stirred solution of 8d (0.074 g,
0.2 mmol) in acetonitrile (3 mL) was added crystalline
iodine (0.056 g, 0.22 mmol). After dissolution of the
3-(4-Chlorophenylsulfonyl)-4,5-dimethyl-2-(tri¯uoroacet-
amido)furan (12). Prepared according to the synthesis
of 8c using aminofuran 11 (0.286 g, 1.0 mmol). Yield

C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
1131
60%; mp 118±119 ꢁC (MeOH/water, ¯u€y tan scales).
2-(4-Chlorophenylsulfonyl)aniline (16). A gently re¯ux-
ing solution of 4-chlorophenyl 2-nitrophenyl sulfone
(15)16 (1.49 g, 5.0 mmol) in acetic acid (25 mL) and
water (2 mL) was treated in two portions with iron
powder (1.50 g). After stirring vigorously for 1 h at 100±
110 ꢁC, the solution was poured over ice/water to give a
pale-pink solid, which was collected and rinsed with
water. Recrystallization from methanol (25 mL) gave
o€-white crystals (1.03 g, 81%), mp 134±135 ꢁC, lit15 mp
1H NMR(CDCl ) d 1.86 (s, 3H), 2.19 (s, 3H), 7.52 (d,
3
2H), 7.79 (d, 2H), 10.03 (br s, 1H). IRv 3320 (NH),
1735 (CO) cmÀ1. Anal. calcd for C14H11ClF3NO4S: C,
44.04; H, 2.91; N, 3.67; S, 8.40. Found: C, 44.16; H,
2.88; N, 3.58; S, 8.31.
New compounds 13b±13d were prepared according to a
general literature procedure.14
ꢁ
1
134±135 C. H NMR(CDCl ) d 4.43 (br s, 2H), 6.66
3
2-Amino-3-(4-chlorophenylsulfonyl)-1-(4-methoxybenzyl)-
4,5-dimethylpyrrole (13b). Yield 61%; mp 135±136 ꢁC
(d, 1H), 6.78 (t, 1H), 7.29 (t, 1H), 7.43 (d, 2H), 7.79 (d,
1H), 7.85 (d, 2H). IRv 3450 and 3355 (NH ) cmÀ1
.
2
1
(MeOH, yellow crystals). H NMR(CDCl ) d 1.95 (s,
3
6H), 3.75 (s, 3H), 4.60 (br s, 2H), 4.81 (s, 2H), 6.80±7.80
(m, 8H). IRv 3440 and 3330 (NH ) cmÀ1. Anal. calcd
for C20H21ClN2O3S: C, 59.32; H, 5.23; N, 6.92; S, 7.92.
Found: C, 59.35; H, 5.23; N, 6.87; S, 7.93.
20-(4-Chlorophenylsulfonyl)tri¯uoroacetanilide (17). To
an ice chilled solution of aniline 16 (0.254 g, 1.0 mmol)
and pyridine (0.09 g, 1.14 mmol) in acetonitrile (5 mL)
was added tri¯uoroacetic anhydride (0.25 g, 1.2 mmol)
and the mixture was stirred at room temperature. After
stirring 30 min, the resulting suspension was diluted
with water (5 mL) and the product was collected.
Recrystallization from MeOH/water (10/1, 15±20 mL)
gave white ¯u€y needles (0.23 g, 63%), mp 153±154 ꢁC.
1H NMR(CDCl 3) d 7.36±7.41 (t, 1H), 7.49 (d, 2H),
7.63±7.68 (t, 1H), 7.77 (d, 2H), 8.06 (d, 1H), 8.38 (d,
1H); NH was not observed. IRv 3315 (NH), 1730 (CO)
cmÀ1. Anal. calcd for C14H9ClF3NO3S: C, 46.23; H,
2.49; N, 3.85; S, 8.82. Found: C, 46.22; H, 2.53; N, 3.78;
S, 8.93.
2
2-Amino-1-[2-(4-chlorophenyl)ethyl]-3-(4-chlorophenyl-
sulfonyl)-4,5-dimethylpyrrole (13c). Yield 31%; mp 146±
147 ꢁC (MeOH, tan crystals). H NMR(CDCl ) d 2.00
1
3
(s, 6H), 2.85 (t, 2H), 3.38 (t, 2H), 4.20 (br s, 2H), 6.90±
7.69 (m, 8H). IRv 3440 and 3360 (NH ) cmÀ1. Anal.
2
calcd for C20H20Cl2N2O2S: C, 56.74; H, 4.76; N, 6.62; S,
7.57. Found: C, 56.60; H, 4.71; N, 6.67; S, 7.51.
2-Amino-3-(4-chlorophenylsulfonyl)-4,5-dimethyl-1-(1-
naphthylmethyl)pyrrole (13d). Yield 71%; mp 205±
206 ꢁC dec (MeOH, o€-white ¯u€y solid). 1H NMR
(CDCl3) d 1.95 (s, 3H), 2.00 (s, 3H), 5.15 (s, 2H), 7.39±
2 - Acetamido - 3 - cyanomethylsulfonyl - 5 - nitrothiophene
(19c). This compound was prepared from acetamide
19b (0.244 g) using the nitration procedure described
above for 9f. Yield 48%; mp 225±226 ꢁC (MeOH, ¯u€y
8.00 (m, 11H). IRv 3440 and 3350 (NH ) cmÀ1. Anal.
2
calcd for C23H21ClN2O2S: C, 65.00; H, 4.98; N, 6.59; S,
7.55. Found: C, 65.03; H, 5.00; N, 6.52; S, 7.50.
1
yellow needles). H NMR(DMSO- d6) d 2.38 (s, 3H),
Compounds 14a±c were prepared according to the
synthesis of 8c using the appropriate aminopyrrole.
5.34 (s, 2H), 8.16 (s, 1H), 11.08 (br s, 1H). IRv 3310
(NH), 2250 (CN), 1690 (CO) cmÀ1. Anal. calcd for
C8H7N3O5S2: C, 33.21; H, 2.44; N, 14.53; S, 22.17.
Found: C, 33.28; H, 2.40; N, 14.37; S, 22.34.
1-Benzyl-3-(4-chlorophenylsulfonyl)-4,5-dimethyl-2-(tri-
¯uoroacetamido)pyrrole (14a). Yield 83%; mp 192±
194 ꢁC (MeOH/water, ¯u€y white needles). H NMR
1
Virology
(CDCl3) d 2.02 (s, 3H), 2.07 (s, 3H), 4.94 (s, 2H), 6.89
(d, 2H), 7.27±7.31 (m, 3H), 7.44 (d, 2H), 7.74 (d, 2H),
8.42 (s, 1H). IRv 3235 (NH), 1740 (CO) cm À1. Anal.
calcd for C21H18ClF3N2O3S: C, 53.56; H, 3.85; N, 5.95;
S, 6.81. Found: C, 53.66; H, 3.85; N, 5.94; S, 6.88.
Cells. Human embryonic lung (HEL) ®broblasts and
E6SM cells were grown in minimum essential medium
(MEM) and human lymphoblast (CEM) cells were
grown in RPMI-1640 medium, supplemented with 10%
inactivated fetal calf serum (FCS), 1% l-glutamine and
0.3% sodium bicarbonate.
3-(4-Chlorophenylsulfonyl)-1-(4-methoxybenzyl)-4,5-di-
methyl-2-(tri¯uoroacetamido)pyrrole (14b). Yield 98%;
ꢁ
1
mp 203±204 C (MeOH, ¯u€y white crystals). H NMR
(CDCl3) d 2.00 (s, 3H), 2.05 (s, 3H), 3.75 (s, 3H), 4.87 (s,
2H), 6.80±6.99 (m, 4H), 7.40±7.68 (dd, 4H), 8.46 (s, 1H).
IRv 3240 (NH), 1740 (CO) cm À1. Anal. calcd for
C22H20ClF3N2O4S: C, 52.75; H, 4.02; N, 5.59; S, 6.40.
Found: C, 52.87; H, 4.06; N, 5.57; S, 6.43.
Viruses. The laboratory wild-type VZV strains OKA
and YS, the thymidine kinase-de®cient VZV strains 07-1
and YS-R, HSV-1 (KOS), HSV-2 (G), the thymidine
kinase-de®cient HSV-1 strains B-2006 and VMW 1837,
cytomegalovirus strains Davis and AD-169, and human
immunode®ciency virus type 1 (strain IIIB) and type 2
(strain ROD) were used in the virus inhibition assays.
1-[2-(4-Chlorophenyl)ethyl]-3-(4-chlorophenylsulfonyl)-
4,5-dimethyl-2-(tri¯uoroacetamido)pyrrole (14c). Yield
61%; mp 208±210 ꢁC (MeOH, ¯u€y white solid). 1H
NMR(DMSO- d6) d 1.95 (s, 6H), 2.85 (t, 2H), 3.91 (t,
2H), 7.20±7.90 (m, 8H), 11.45 (s, 1H). IRv 3200 (NH),
1735 (CO) cmÀ1. Anal. calcd for C22H19Cl2F3N2O3S: C,
50.87; H, 3.69; N, 5.40; S, 6.17. Found: C, 51.04; H,
3.61; N, 5.34; S, 6.11.
Antiviral assays. The procedures of the antiviral assays
were as described before.23À26 Con¯uent HEL cells
grown in 96-well microtiter plates were inoculated with
VZV at an input of 20 PFU (plaque forming units) per
well, with CMV at an input of 100 PFU per well, or
with HSV at 100 CCID50 (50% cell culture infective
doses) per well. After a 1 to 2-h incubation period,

1132
C. E. Stephens et al. / Bioorg. Med. Chem. 9 (2001) 1123±1132
residual virus was removed and the infected cells were
further incubated with MEM (supplemented with 2%
inactivated FCS, 1% l-glutamine and 0.3% sodium
bicarbonate) containing varying concentrations of the
compounds. Antiviral activity was expressed as EC50
(50% e€ective concentration), or concentration required
to reduce viral plaque formation after 5 days (VZV) or
virus-induced cytopathicity (CMV after 7 days and
HSV, VV after 3 days) by 50% compared to the
untreated control. For the HIV assays, 4Â105 CEM
cells per mL were infected with HIV-1 or HIV-2 at ꢃ100
CCID50 (50% cell culture infective dose) per mL of cell
suspension. Then 100 mL of the infected cell suspension
was transferred to microtiter plate wells and mixed with
100 mL of the appropriate dilutions of test compounds.
After 4 days, giant cell formation (CEM) was recorded
microscopically in the HIV-infected cell cultures. The
50% e€ective concentration (EC50) and 50% cytotoxic
concentration (CC50) of the test compounds were
de®ned as the compound concentrations required to
inhibit virus-induced cytopathicity (CEM) by 50% or to
reduce by 50% the number of viable cells in mock-
infected cell cultures, respectively. The other viruses
were assayed as described before.
3. (a) Antiviral Agents Bulletin 1998, 11, 289. (b) Cited activity
obtained from: Corbett, J. W.; Ko, S. S.; Rodgers, J. D.;
Gearhart, L. A.; Magnus, N. A.; Bacheler, L. T.; Diamond, S.;
Je€rey, S.; Klabe, R. M.; Cordova, B. C.; Garber, S.; Logue,
K.; Trainor, G. L.; Anderson, P. S.; Erickson-Viitanen, S. K.
J. Med. Chem. 2000, 43, 2019.
4. Richman, D.; Rosenthal, A. S.; Skoog, M.; Eckner, R. J.;
Chou, T.-C.; Sabo, J. P.; Merluzzi, V. J. Antimicrob. Agents
Chemother. 1991, 35, 305.
5. Dueweke, T. J.; Poppe, S. M.; Romero, D. L.; Swaney,
S. M.; So, A. G.; Downey, K. M.; Althaus, I. W.; Reusser, F.;
Busso, M.; Resnick, L.; Mayers, D. L.; Lane, J.; Aristo€, P. A.;
Thomas, R. C.; Tarpley, W. G. Antimicrob. Agents Chemo-
ther. 1993, 37, 1127.
6. Young, S. D.; Britcher, S. F.; Tran, L. E.; Payne, L. S.;
Lumma, W. C.; Lyle, T. A.; Hu€, J. R.; Anderson, P. S.;
Olsen, D. B.; Carroll, S. S.; Pettibone, D. J.; O'Brien, J. A.;
Ball, R. G.; Balani, S. K.; Lin, J. H.; Chen, I.-W.; Schleif,
W. A.; Sardana, V. V.; Long, W. J.; Byrnes, V. W.; Emini,
E. A. Antimicrob. Agents Chemother. 1995, 39, 2602.
7. Young, S. D.; Amblard, M. C.; Britcher, S. F.; Grey, V. E.;
Tran, L. O.; Lumma, W. C.; Hu€, J. R.; Schleif, W. A.; Emini,
E. E.; O'Brien, J. A.; Pettibone, D. J. Bioorg. Med. Chem.
Lett. 1995, 5, 491.
8. Artico, M.; Silvestri, R.; Stefancich, G.; Massa, S.; Pag-
nozzi, E.; Musu, D.; Scintu, F.; Pinna, E.; Tinti, E.; La Colla,
P. Arch. Pharm. (Weinheim) 1995, 328, 223.
9. Artico, M.; Silvestri, R.; Massa, S.; Loi, A. G.; Corrias, S.;
Piras, G.; La Colla, P. J. Med. Chem. 1996, 39, 522.
10. Buckheit, Jr., R. W.; Fliakas-Boltz, V.; Russell, J. D.;
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12. Merkushev, E. B. Synthesis 1988, 923.
13. Ross, J. R.; Sowell, J. W., Sr. J. Heterocycl. Chem. 1987,
24, 757.
Cytotoxicity assays. Con¯uent monolayers of HEL cells
as well as growing HEL cells in 96-well microtiter plates
were treated with di€erent concentrations of the experi-
mental drugs. Cell cultures were incubated for 3 (grow-
ing cells) or 5 (con¯uent cells) days. At the indicated
time, the cells were trypsinized and the cell number was
determined using a Coulter counter. The 50% cytostatic
concentration (CC50) was de®ned as the compound
concentration required to reduce the cell number by 50%.
14. Mattson, R. J.; Wang, L.-C.; Sowell, J. W., Sr. J. Hetero-
cyclic Chem. 1980, 17, 1793.
15. The tri¯uoroacetamide of aminopyrrole 13d was not pre-
pared at this time.
16. Cadogan, J. I. G.; Done, J. N.; Lunn, G.; Lim, P. K. K. J.
Chem. Soc., Perkins Trans 1 1976, 1749
Acknowledgements
The authors are grateful to the Developmental Thera-
peutics Program of the National Cancer Institute, USA,
for evaluating compounds for antitumor activity, and to
Mrs. A. Absillis, A. Camps, F. De Meyer, L. Vanden-
heurck and A. Van Lierde for excellent technical assis-
tance. The research was supported, in part, by the
College of Pharmacy, University of South Carolina, and
by grants from the Fonds voor Geneeskunde Weten-
schappelijk Onderzoek Ð Vlaanderen (G.0104.98), the
Belgian Geconceteerde Onderzoeksacties (GOA 00/12)
and the Biomedical Health Programme of the European
Commission.
17. Stephens, C. E.; Price, M. B.; Sowell, J. W., Sr. J. Het-
erocycl. Chem. 1999, 36, 659.
18. Stephens, C. E.; Sowell, J. W., Sr. J. Heterocycl. Chem.
1998, 35, 927.
19. Artico, M.; Stefancich, G.; Silvestri, R.; Massa, S.; Pag-
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La Colla, P. Bioorg. Med. Chem. 1996, 4, 837.
21. Monks, A.; Scudiero, D.; Skehan, P.; Shoemaker, R.;
Paull, K.; Vistica, D.; Hose, C.; Langley, J.; Cronise, P.; Vai-
gro-Wol€, A.; Gray-Goodrich, M.; Campbell, H.; Mayo, J.;
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Ozawa, Y.; Sugi, N. H.; Nagasu, T.; Koyanagi, N.; Kitoh, K.
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Â
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