A new class of potential anti-tuberculosis agents: Synthesis and preliminary evaluation of novel acrylic acid ethyl ester derivatives

Article abstract of DOI:10.1016/j.bmc.2010.05.016

Novel acrylic acid ethyl ester derivatives were synthesized and evaluated as potential agents against Mycobacterium species. A versatile and efficient copper-catalyzed coupling process was developed and used to prepare a library of substituted acrylic acid ethyl ester analogs. Minimum inhibitory concentration assays indicated that two of these compounds 3 and 4 have greater in vitro activity against Mycobacterium smegmatis than rifampin, one of the current, first-line anti-mycobacterial chemotherapeutic agents. Moreover, members of this new class of compounds appear to exhibit a specific anti-mycobacterial effect and do not inhibit the growth of the other Gram-positive or Gram-negative species tested.

Full text of DOI:10.1016/j.bmc.2010.05.016

Bioorganic & Medicinal Chemistry 18 (2010) 4178–4186
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
A new class of potential anti-tuberculosis agents: Synthesis and
preliminary evaluation of novel acrylic acid ethyl ester derivatives
M. Shahjahan Kabir a, Ojas A. Namjoshi a, Ranjit Verma a, Rebecca Polanowski c, Sarah M. Krueger c,
c,
b,
a,
*
David Sherman d, Marc A. Rott c, , William R. Schwan , Aaron Monte , James M. Cook
*
*
*
a Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
b Department of Chemistry, University of Wisconsin-La Crosse, La Crosse, WI 5460, USA
c Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI 5460, USA
d Department of Pathobiology, Seattle Biomedical Research Institute, Seattle, WA 98109, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Novel acrylic acid ethyl ester derivatives were synthesized and evaluated as potential agents against
Mycobacterium species. A versatile and efficient copper-catalyzed coupling process was developed and
used to prepare a library of substituted acrylic acid ethyl ester analogs. Minimum inhibitory concentra-
tion assays indicated that two of these compounds 3 and 4 have greater in vitro activity against Mycobac-
terium smegmatis than rifampin, one of the current, first-line anti-mycobacterial chemotherapeutic
agents. Moreover, members of this new class of compounds appear to exhibit a specific anti-mycobacte-
rial effect and do not inhibit the growth of the other Gram-positive or Gram-negative species tested.
Ó 2010 Elsevier Ltd. All rights reserved.
Received 5 March 2010
Revised 2 May 2010
Accepted 4 May 2010
Available online 7 May 2010
Keywords:
Anti-tuberculosis
Mycobacterium smegmatis
Mycobacterium tuberculosis
Vinylthioether of acrylic acid ethyl ester
Vinylether of acrylic acid ethyl ester
Vinylamines of acrylic acid ethyl ester
1. Introduction
inhibition of the growth of a range of Gram-positive bacteria, phe-
nothiostyrene 1 (Fig. 1) was found to also exhibit a minimum
Tuberculosis (TB) is an airborne infectious disease caused by
species found in the Mycobacterium tuberculosis complex that in-
cludes M. tuberculosis. The World Health Organization (WHO)
estimates that 9.27 million new cases of TB occurred in 2007.1
The TB epidemic has been further complicated by the rapid spread
of Human Immunodeficiency Virus (HIV) and the emergence of
multidrug resistant (MDR) and extensively drug resistant (XDR)
forms. Tuberculosis has again become a significant threat to global
health.1 Current first-line treatment of drug-sensitive tuberculosis
infections consists of a four-drug regimen that includes rifampin,
isoniazid, pyrazinamide, and ethambutol. When effective, this
treatment requires a minimum of six months to completely eradi-
cate the infection.2 Due to the emergence of drug-resistant strains,
there has been a rise in transmission rates, treatment failures, and
mortality due to TB.3,4 Consequently, the development of alterna-
tive chemotherapeutics for M. tuberculosis infections is needed.
Previously, members of a class of stilbene, phenoxystyrene, and
phenothiostyrene analogs were reported to exhibit promising anti-
bacterial activity against Gram-positive bacteria.5 In addition to
inhibitory concentration (MIC) of 64 lg/mL against Mycobacterium
smegmatis, a safer surrogate of the clinically significant and more
virulent M. tuberculosis.6 In early efforts to increase the molecular
diversity in the study of these antimicrobial structure–activity
relationships (SAR), certain acrylic acid ethyl esters such as 2 were
also synthesized, and this lead compound exhibited a promising
MIC value of 64 l
g/mL against M. smegmatis.6
Hence, a library of vinyl-substituted derivatives of acrylic acid
ethyl esters (Schemes 1 and 2) was designed to evaluate the effect
of structural changes on anti-mycobacterial activity. First, various
thioacrylate analogs 3–12 were synthesized to determine the
effects of electron-rich (3, 9, 10, and 11), electron-deficient (4–7),
and bulky (6, 8, and 9) substituents on the activity relative to 2.
Additional analogs 13–26 contained an oxygen atom in place of
NC
S
O
N
O
S
S
1
2
* Corresponding authors. Tel.: +1 414 229 5856; fax: +1 414 229 5530 (J.M.C.).
E-mail address: capncook@uwm.edu (J.M. Cook).
Figure 1. Lead compounds.
0968-0896/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2010.05.016

M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
4179
10 mol % CuI
that the amine attached to the acrylate system resulted in slightly
truncated molecules. Similar derivatives have been reported to
possess anti-retroviral properties.7 In all cases, use of the commer-
cially available ethyl cis-3-iodo-acrylate 1A enabled rapid
generation of this library of substituted acrylates using a new cop-
per-mediated coupling process.8,9
O
O
20 mol % L
+
R
SH
O
I
O
S R
K3PO4 (1.5 equiv)
DMF, 40-50 ºC, 2-4 h
1A
R = aryl, heteroaryl, alkyl
OH
=
L
OH
O
O
N
N
N
S
O
2. Results and discussion
2.1. Chemistry
O
S
O
S
O
S
3
4
5
O
O
The arylthioacrylate analogs 3–11 and the alkylthioacrylate 12
were synthesized by employing copper-catalyzed coupling pro-
cesses that were developed recently (Scheme 1) with cis-1,2-hex-
anediol serving as the ligand.8 This process involved a cross-
coupling reaction between the ethyl cis-3-iodo-acrylate 1A and
the thiophenol or alkyl mercaptan. As shown in the sequence out-
lined in Scheme 1, this general copper-mediated coupling method
was employed to construct all of the new substituted thioacrylate
ester analogs.
O
O
N
O
O
S
O
S
O
S
6
7
8
O
O
O
S
OH
O
S
9
10
O
O
It was found that the specific protocol used to prepare the thio-
ethers, in which the ligand was cis-cyclohexanediol, did not prove
efficient in the coupling of substituted phenols with vinyl iodides.
Thus, a more efficient copper catalytic system involving the new li-
gand, 2-pyridin-2-yl-1H-benzoimidazole (L3), was developed
(Scheme 2).9–12 This modified approach provided ready access to
the substituted phenoxyacrylates 13–26. In addition, when this
same ligand was used in the cross coupling of various N-heterocy-
cles with cis-3-iodo-acrylate, 1A, this process afforded substituted
vinylamines 27–34, illustrating the versatility and usefulness of
this new catalytic coupling system (Scheme 2).
O
S
O
S
S
11
12
Scheme 1. Synthesis of vinyl thioether derivatives of acrylic acid ethyl ester 1A.
5 mol % CuI
O
H
N
O
5 mol % L3
O
I
Nu
+
NuH
O
L3 =
2.0 equiv Cs3CO3
DMF, rt, 6 h
or 40-80 ºC, 2-4h
N
N
1A
F
O
O
O
O
O
O
O
O
O
F
O
O
2.2. Biology
13
14
15
NO2
O
OMe
OMe
O
O
NH2
Antimicrobial activity determined using standard minimum
inhibitory concentration (MIC) assays indicated measurable anti-
mycobacterial activity in 53% of the compounds tested (Table 1).
Two agents (29 and 31) were insoluble (in DMSO) and were not as-
sayed. Relative to rifampin, six analogs (2, 5, 6, 10, 16, and 22)
showed similaractivity, while twoanalogs (3 and 4) had activitythat
surpassed that of the positive control. Both of these compounds
demonstrated enhanced activity as compared to the other thioacry-
late analogs. Of these two, the agent containing an electron-deficient
group (4) demonstrated twice the potency of rifampin, whereas the
compound with the electron-rich substituent (3) demonstrated a
four-fold increase in potency over rifampin. To further assess the
anti-mycobacterial potential of these two most potent agents, they
also were tested against M. tuberculosis (Table 2). A green fluorescent
protein (GFP)-based assay was used to measure the efficacy of 3 and
4 in the inhibition of the growth of M. tuberculosis.13 In those assays,
both isoniazid and rifampin were employed as the positive controls,
O
O
O
O
O
O
O
16
18
O
O
O
17
Me
O
O
O
O
O
O
O
O
O
19
20
21
O
O
O
O
S
O
O
O
O
O
O
22
23
24
O
N
N
S
O
O
O
O
O
N
26
25
F3C
27
O
N
N
N
O
N
O
N
N
O
O
N
O
N
O
O
N
O
31
N
30
28
29
N
N
O
N
N
N
O
N
N
O
and these had respective MIC values of 0.25
lg/mL and <0.03
lg/mL.
N
O
O
SCH3
The MIC values of 3 and 4 were both found to be 25
lg/mL. Finally, 3
32
33
34
and 4 were each assayed against five additional Mycobacterium
strains: Mycobacterium fortuitum, Mycobacterium kansasii, Mycobac-
terium chelonae, Mycobacterium avium, and Mycobacterium intracel-
lulare. In this series, the respective MIC values for 3 were 4, 16, 8, 64,
Scheme 2. Synthesis of vinyl ether and vinyl amine analogues of acrylic acid ethyl
ester 1A.
and 128
and 16
l
g/mL; and the respective MIC values for 4 were 16, 8, 8, 64,
lg/mL.
the sulfur functionality. This structural change altered the bond an-
gle slightly, from ꢀ105° for the C–S–C bond, to ꢀ120° for the C–O–
C bond, changing the overall conformation of the ethers with
respect to the thioethers. This also permitted alteration of the elec-
tronic character adjacent to the double bond from sulfur to oxygen.
Finally, a series of cyclic vinylamines 27–34 was prepared using
the same methods, and various N-heterocycles were obtained such
Beyond these anti-mycobacterial activities, the entire series of
compounds showed essentially no activity against either the Gram
positive (Staphylococcus aureus, Bacillus cereus) or Gram-negative
(Escherichia coli) bacteria investigated (Table 1). Indeed, only the
nitro compound 16 showed activity beyond the M. smegmatis as-
says, with an MIC of 64 lg/mL against S. aureus.

4180
M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
Table 1
growth of M. smegmatis at concentrations equivalent to, or better
than, the primary anti-mycobacterial agent currently used to treat
clinical TB infections, rifampin. Aryl vinyl thioethers 3 and 4 exhib-
ited the strongest anti-M. smegmatis activity, and these were there-
fore assayed against the more virulent strain, M. tuberculosis,
Minimum inhibitory concentration (MIC) values for acrylic acid ethyl ester analogs
(l
g/mL)
Compd
M.
S. aureus ATCC
29213
B.
cereus
E. coli ATCC
29522
smegmatis
1
2
3
4
5
6
7
8
64
64
16
32
64
64
>128
128
>128
>128
>128
>128
>128
>128
>128
>128
>128
128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
NDb
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
NDb
demonstrating MIC values of 25 lg/mL each, indicating that, in this
assay, these new lead compounds are not as potent as the existing
drugs isoniazid and rifampin. However, these two compounds also
possessed generally good in vitro inhibitory activities against the
five other less common Mycobacterium species tested and did not
effect any other types of cells. This activity may signify a new
mechanism of action for these readily available small molecules.
With respect to these nascent SAR studies, it was clear from
examination of the initial lead structures 1 and 2 that a planar mol-
ecule with lipophilic substituents in ring B likely would be more ac-
tive. In keeping with this hypothesis, the series of thio substituted
acrylate esters 3–12 were prepared and evaluated against M.
smegmatis and found to be much more active than the analogous
oxygen or nitrogen substituted analogs (compare the activities of
2, 3, and 4 with 13, 23, and 25, and also note that none of the nitrogen
based acrylate esters demonstrated activity at the concentrations
tested). Because the electron density of the sulfur atom is similar
to carbon, it is tempting to speculate that the lipophilic character
at that position is important, but moreexampleswill need tobe eval-
uated before a reliable conclusion can be reached. Further, examina-
tion of the aromatic moiety in the most active analogues 2, 3, 4, 5, 6,
and 10 indicates that both lipophilic aromatic rings and more polar
aromatic rings demonstrate activity. Importantly, all of these com-
pounds showed activity only against Mycobacterium species (seven
different strains) and not against other Gram-positive or Gram-neg-
ative bacteria. This suggests a novel, Mycobacterium-selective mech-
anism of action for 2, 3, 4, 5, 6, and 10, which indicates that these
acrylic esters warrant further study.
>128
>128
>128
>128
>128
>128
>128
128
>128
>128
>128
>128
>128
64
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
>128
NDb
128
128
>128
64
128
>128
128
>128
>128
64
>128
128
>128
>128
>128
64
128
>128
128
>128
>128
>128
NDb
>128
NDb
>128
>128
128
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
>128
>128
>128
NDb
NDb
NDb
>128
>128
>128
NDb
>128
>128
>128
NDb
>128
>128
>128
NDb
Rifampina 64
In general, these promising results suggest that small ligands
such as 3 and 4 could potentially be developed into viable alterna-
tives to current front line therapies used in the treatment of TB and
other less common infections caused by Mycobacterium species.
Furthermore, it appears that an appropriately substituted acrylic
acid ethyl ester scaffold could serve as a promising launch point
for the development of new chemotherapeutic agents with utility
in treating Mycobacterium infections. These small molecules are
much easier to synthesize than those agents employed in front-line
therapy including rifampin. Further refinement and a continuation
of these SAR studies are now underway.
a
Positive control.
ND = not determined.
b
Table 2
MIC values for 3 and 4 against Mycobacterium strains (
l
g/mL)
Compd
M.
M.
M.
M.
M.
M.
tuberculosis fortuitum kansasii chelonae avium intracellulare
3
4
25
25
4
16
8
8
64
128
16
16
8
64
Isoniazida 0.25
Rifampina <0.03
NDb
NDb
NDb
NDb
NDb
NDb
NDb
NDb
NDb
NDb
4. Experimental
4.1. Chemistry
a
Positive control.
ND = not determined in our assays.
b
Copper(I) iodide (99.99% purity), 1,2-cyclohexanediol (L, 99%
purity) and DMF (anhydrous, 99.8% purity) were purchased from
Aldrich Chemical Co. and employed as is. Analytically pure ligand
L3 was prepared and characterized as previously reported.9 All sul-
fides, phenols, and amines were used as received from Aldrich or
Alfa Aesar without further purification. Potassium phosphate was
purchased from Alfa Aesar (97% purity). Caesium carbonate (99%
purity) was purchased from Aldrich Chemical Co. Silica gel (Dy-
namic Adsorbents, 230–400 mesh) for flash chromatography was
utilized to purify the analogues. The 1H and 13C NMR data were ob-
tained on a Bruker Spectrospin 300 MHz and GE500 MHz instru-
ments, with chemical shifts reported relative to TMS. Some yields
were determined by HPLC analysis on a Hewlett Packard 1100 Ser-
Furthermore, the cytotoxicities of the two most active analogs to
ward putative host cells were assessed using a tryptan exclusion
assay employing murine J774A.1 cells.14 In this assay, the IC50 values
obtained for 3 and 4 were 150 lg/mL and 200 lg/mL, respectively.
3. Conclusion
A series of acrylic acid ethyl esters with vinyl thioether, ether,
and cyclic amine substituents were prepared using a new cop-
per-mediated coupling process. These compounds were designed
to establish early structure-activity relationships among this class
of compounds, which have shown promising anti-mycobacterial
activity. Of particular importance is these small molecules appear
to be highly selective for the inhibition of the growth of mycobac-
teria while not affecting any of the other types of microorganisms
tested. Of the 33 new compounds prepared, eight inhibited the
ies instrument equipped with a silica column (ISCO, 5 lm packing,
4.6 Â 250 mm). The HRMS and GC/MS spectral data were per-
formed by the Laboratory for Biological Mass Spectrometry, Texas
A&M University, College Station, TX 77843 and by the Laboratory

M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
4181
for Mass Spectrometry, University of Kansas, Lawrence, KS 66045–
7582, USA.
(1.0 equiv), in a minimal amount of dry DMF, was added to the reac-
tion mixture through a rubber septum. The contents of the reaction
flask were heated from rt to 40 °C for 0.5–6 h, depending on the sub-
strate. The reaction mixture was then cooled to rt and filtered
through a pad of silica gel to remove any insoluble residue. The
pad of silica gel was washed with ethyl acetate and hexane (40:60)
(100 mL). The combined filtrates were washed with brine (5 x
50 mL) and dried (Na2SO4), after which it was concentrated in vacuo
on a rotatory evaporator. The concentrated crude oil was purified by
flash column chromatography on silica gel, using the eluent (2–20%)
ethyl acetate and hexane (depending on the substrate) to obtain the
pure target compound (81–98%).
4.1.1. Procedure for the preparation of ligand L3 (2-pyridin-2-
yl-1H-benzoimidazole, L3)9,12
The pyridine-2-carboxaldehyde (2.0 equiv) in dry methanol
(0.5 M) was added dropwise to a suspension of anhydrous Na2SO4
(1.5 equiv) and o-phenylenediamine (1.0 equiv) in dry methanol
(0.5 M) under argon at rt. The reaction mixture that resulted was
stirred at rt for 5 h. The reaction mixture was then filtered through
a sintered glass funnel, and the filtrate was concentrated in vacuo.
The crude material was suspended in hot, dry CH3CN and allowed
to cool to rt to precipitate the ligand, L3. The precipitate was then
recrystallized from CH3OH to afford pure L3 (84% yield). The spectral
data obtained for L3 were in excellent agreement with that reported
in the literature.9,12 1H NMR (300 MHz, DMSO-d6): d 13.1 (1H, s, NH),
d 8.73 (1H, m, HAr) d 8.34 (1H, d, J = 8.1 Hz, HAr), d 7.99 (1H, dt,
J = 7.7, 1.7 Hz, HAr), d 7.70–7.72 (1H, m, HAr), d7.52–7.57 (1H, m,
HAr), d 7.51 (1H, dddd J = 7.5, 4.9, 1.0 Hz, HAr), d 7.18–7.27 (2H, m,
HAr) ppm. 13C NMR (75 MHz, DMSO-d6): d 150.8, 149.4 148.5,
143.9, 137.5, 134.9, 124.7, 123.2, 121.9, 121.4, 119.3, 112.1 ppm.
White solid, mp 222.9 °C (lit.: 224.0 °C)9 CHN: calcd for C12H9N3;
C, 73.82; H, 4.65; N, 21.52. Found: C, 73.46; H, 4.66; N 21.34.
4.1.4. Preparation of (Z)-3-(naphthalen-2-ylthio)-acrylic acid
ethyl ester (2)
General procedure A was followed (2 h). Ethyl cis-3-iodo-acry-
late (90 mg, 0.40 mmol), 2-naphthalenethiol (84.9 mg, 0.53 mmol),
CuI (7.6 mg, 0.040 mmol), cis-1,2-cyclohexanediol
L (8.2 mg,
0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF (2.0 mL) were
stirred at 40–50 °C to obtain the thioether 2 as a pale yellow oil.
Column chromatography (solvent 10% EtOAc in hexane) provided
pure 2 (98 mg, 95% yield): 1H NMR (300 MHz, CDCl3): d 8.00 (1H,
s, HAr), d 7.93–7.81 (3H, m, HAr), d 7.58–7.50 (3H, m, HAr), d
7.41 (1H, d, J = 10.0 Hz, HC(S)=CH), d 5.99–5.96 (1H, d, J = 10 Hz,
HC=CH-S), d 4.35–4.28 (2H, q, J = 7.2 Hz, H2C-CH3), d 1.27 (3H, t,
J = 7.1 Hz, H3C-CH2). 13CNMR:166.6, 149.4, 133.4, 133.2, 132.5,
130.7, 129.3, 127.6, 126.6, 125.4, 113.2, 60.3, 14.2. HRMS (ESI)
(M+H)+, calcd for C15H15O2S 259.0793; found 259.0789.
4.1.2. General procedure (A) for the Cu-catalyzed cross coupling
of vinyl iodides (1A) with thiols
An oven dried round bottom flask which contained a magnetic
stir bar was sealed with a rubber septum. This flask was evacuated
and backfilled with argon and the sequence was repeated three
times while cooling to rt. The round bottom flask was then charged
with anhydrous potassium phosphate (1.5 equiv), copper (I) iodide
4.1.5. Preparation of (Z)-3-(4-tert-butyl-phenylsulfanyl)-acrylic
acid ethyl ester (3)
(10 mol%), cis-1,2-cyclohexanediol
L
(20 mol%) and dry DMF
General procedure (A) was followed (2 h). Ethyl cis-3-iodo-acry-
late 1A (90 mg, 0.40 mmol), 4-tert-butylbenzenethiol (87.8 mg,
0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis-1,2-cyclohexanediol L
(8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF
(2.0 mL) were stirred at 40–50 °C to obtain thioether 3 as a colorless
oil. Column chromatography (solvent 3–5% EtOAc in hexane) pro-
vided pure 3 (103.6 mg, 98% yield): 1H NMR (300 MHz, CDCl3):
d7.46–7.39 (4H, m, HAr), d 7.28 (1H, d, J = 10.1 Hz, HC(S)=CH), d
5.90 (1H, d, J = 10.1 Hz, HC=CH-S), d 4.27 (2H, q, J = 7.1 Hz, H2C-
CH3), d 1.37–1.32 (12H, m, H3C-CH2 & (H3C)3C). 13C NMR (75 MHz,
CDCl3): d 166.5, 151.5, 150.4, 132.7, 131.0, 126.3, 112.9, 60.2, 34.5,
31.1, 14.3. HRMS (ESI) (M+H)+, calcd for C15H21O2S 265.1262; found
265.1259.
(2 mL). The solution that resulted was stirred for 5–10 min at rt.
The reaction mixture took on a light green color within 3–5 min.
The reaction vessel was then evacuated and backfilled with argon
one more time before adding the thiol and the vinyl iodide. The
appropriate thiol (1.2 equiv) was added to the reaction mixture
through a rubber septum, and the mixture was stirred for another
5 min at rt. The vinyl iodide (1.0 equiv) of choice was added to the
resulting reaction mixture through a rubber septum in a minimum
amount of dry DMF. The contents of the reaction mixture were
heated to 30–60 °C for 0.5–4 h, depending on the substrate. The
reaction mixture was then cooled to rt and filtered through a pad
of silica gel to remove any insoluble residue. The pad of silica gel
was washed with ethyl acetate (100 mL). The combined filtrate
was washed with brine (4 x 50 mL) and dried (Na2SO4), after which
it was concentrated in vacuo on a rotatory evaporator. The concen-
trated crude oil was purified by flash column chromatography on
silica gel using the eluent (2–10%) ethyl acetate and hexane
(depending on the substrate) to obtain the analytically pure target
ligand (84–98%).
4.1.6. Preparation of (Z)- 3-(benzothiazol-2-ylsulfanyl)-acrylic
acid ethyl ester (4)
General procedure (A) was followed (4 h). Ethyl cis-3-iodo-acry-
late 1A (90 mg, 0.40 mmol), benzothiazole-2-thiol (88.6 mg,
0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis-1,2-cyclohexanediol L
(8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF
(2.0 mL) were stirred at 40–50 °C to obtain the thioether 4 as a col-
orless oil. Column chromatography (solvent 10% EtOAc in hexane)
provided pure 4 (101 mg, 95% yield): 1H NMR (300 MHz, CDCl3): d
8.38 (1H, d, J = 10.0 Hz, HC(S)=CH), d 7.96 (1H, d, J = 8.2 Hz, HAr), d
7.82 (1H, d, J = 7.8 Hz, HAr), d 7.51 (1H, t, J = 7.6 Hz, HAr), d 7.37
(1H, t, J = 7.5 Hz, HAr), d 6.19 (1H, d, J = 10.0 Hz, HC=CH-S), d 4.30
(2H, q, J = 7.2 Hz, J = 21.4 Hz, H2C-CH3), d 1.36 (3H, t, J = 7.1 Hz,
H3C-CH2). 13C NMR (75 MHz, CDCl3): d 166.4, 164.2, 152.6, 140.6,
135.4, 126.3, 124.9, 122.1, 121.2, 115.6, 60.8, 14.2. HRMS (ESI)
(M+H)+, calcd for C12H12NO2S2 266.0309; found 266.0311.
4.1.3. General procedure (B) for the Cu-catalyzed cross coupling
of vinyl iodides (1A) with phenols and cyclic amines
An oven dried round bottom flask which contained a magnetic
stir bar was sealed with a rubber septum and then evacuated and
backfilled with argon (the sequence was repeated three times) while
cooling to rt. The round bottom flask was then charged with anhy-
drous cesium carbonate (2.0 equiv), copper (I) iodide (5 mol%), L3
(5 mol%) and DMF (2 mL). The resulting solution was stirred for 5–
10 min at rt. The reaction mixture took on a light green color within
3–5 min. The reaction vessel was evacuated and backfilled with ar-
gon one more time before adding the phenol or amine, and the vinyl
iodide. The appropriate phenol or cyclic amine(1.5 equiv)was added
to the reaction mixture through a rubber septum, and the mixture
was allowed to stir for an additional 5 min at rt. Vinyl iodide 1A
4.1.7. Preparation of (Z)-3-(pyrimidin-2-ylsulfanyl)-acrylic acid
ethyl ester (5)
General procedure (A) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (90 mg, 0.40 mmol), 2-pyrimidinethiol (59.4 mg,

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M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis 1,2-cyclohexanediol L
(8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF
(2.0 mL) were stirred at 40–50 °C to obtain the thioether 5 as a col-
orless oil. Column chromatography (solvent, 3–5% EtOAc in hexane)
provided pure 5 (78.2 mg, 93% yield): 1H NMR (300 MHz, CDCl3): d
8.64–8.61 (2H, m, HAr), d 8.53 (1H, d, J = 10.4 Hz, HC(S)=CH), d
7.12 (1H, t, J = 4.8 Hz, HAr), d 6.11 (1H, d, J = 10.4 Hz, HC=CH-S), d
4.28 (2H, q, J = 7.1 Hz, H2C-CH3), d 1.34 (3H, t, J = 7.1 Hz, H3C-CH2).
13C NMR (75 MHz, CDCl3): d 168.1, 166.4, 157.7, 141.4, 117.9,
114.9, 60.5, 14.2. HRMS (ESI) (M+Li)+, calcd for C9H10N2O2SLi
217.0623; found 217.0621.
0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis 1,2-cyclohexanediol, L
(8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF
(2.0 mL) were stirred at 40–50 °C to obtain the thioether 9 as a col-
orless oil. Column chromatography solvent (2–3% EtOAc in hexane)
provided pure 9 (98 mg, 98% yield): 1H NMR (300 MHz, CDCl3): d
7.50 (1H, d, J = 7.6 Hz, HAr), d 7.37–7.35 (2H, m, HAr), d 7.25–
7.21 (1H, m, HAr), d 7.16 (1H, d, J = 10.0 Hz, HC(S)=CH), d 5.91
(1H, d, J = 10.0 Hz, HC=CH-S), d 4.28 (2H, q, J = 7.0 Hz, J = 21.4 Hz,
H2C-CH3),
d
3.63–3.58 (1H, m, HC-(CH3)2), d 1.35 (3H, t,
J = 7.1 Hz, H3C-CH2), d 1.25 (6H, d, J = 6.8 Hz, H3C-CH). 13C NMR
(75 MHz, CDCl3): d 166.5, 150.9, 150.2, 134.4, 133.2, 129.1, 126.7,
125.9, 113.0, 60.1, 30.5, 23.5, 14.3. HRMS (ESI) (M+Li)+, calcd for
C14H18O2SLi 257.1188; found 257.1190.
4.1.8. Preparation of (Z)-2-(2-ethoxycarbonyl-vinylsulfanyl)-
benzoic acid methyl ester (6)
General procedure (A) was followed (2 h). Ethyl cis-3-iodo-acry-
late 1A (90 mg, 0.40 mmol), 2-mercapto-benzoic acid methyl ester
(89.2 mg, 0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis 1,2-cyclohex-
anediol L (8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and
DMF (2.0 mL) were stirred at 40–50 °C to obtain thioether 6 as a
colorless solid. Column chromatography (solvent 2–3% EtOAc in
hexane) provided pure 6 (99 mg, 93% yield): 1H NMR (300 MHz,
CDCl3): d 7.87 (1H, d, J = 7.8 Hz, HAr), d 7.59–7.49 (2H, m, HAr), d
7.38 (1H, t, J = 7.5 Hz, HAr), d 7.26 (1H, d, J = 10.2 Hz, HC(S)=CH),
d 5.97 (1H, d, J = 10.2 Hz, HC=CH-S), d 4.27 (2H, q, J = 7.2 Hz,
4.1.12. Preparation of (Z)-3-(4-hydroxy-phenylsulfanyl)-acrylic
acid ethyl ester (10)
The general procedure (A) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (90 mg, 0.40 mmol), 4-hydroxythiophenol (66.9 mg,
0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis-1,2-cyclohexanediol
(8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF
(2.0 mL) were stirred at 40–50 °C to obtain the thioether 10 as a col-
orless semi-solid. Column chromatography solvent (15% EtOAc in
hexane) provided pure 10 (81 mg, 91% yield): 1H NMR (300 MHz,
CDCl3): d 7.51–7.48 (2H, d, J = 7.7 Hz, HAr), d 7.20–7.17 (1H, d,
J = 10 Hz, HC(S)=CH), d 6.91–6.87 (2H, d, J = 7.7 Hz, HAr),d 5.88–
5.84 (1H, d, J = 10 Hz, HC=CH-S), d 4.30–4.25 (2H, q, J = 7.1 Hz,
H2C-CH3), d 1.33 (3H, t, J = 7.1 Hz, H3C-CH2). 13CNMR: 1665, 155.3,
146.1, 130.9, 130.6, 127.3, 117.2, 116.3, 113.7, 61.4, 14.8. HRMS
(ESI) (MÀ1)À calcd for C11H12O3S 223.0507; found 223.0429.
J = 21.4 Hz, H2C-CH3),
d 3.94 (3H, s, H3C-O), d 1.35 (3H, t,
J = 7.1 Hz, H3C-CH2). 13C NMR (75 MHz, CDCl3): d 166.8, 166.2,
148.5, 137.8, 132.1, 130.5, 127.5, 114.4, 60.3, 52.3, 14.3. HRMS
(ESI) (M+Li)+, calcd for C13H14O4SLi 273.0773; found 273.0769.
4.1.9. Preparation of (Z)-3-(pyridin-2-ylsulfanyl)-acrylic acid
ethyl ester (7)
General procedure (A) was followed (4 h). Ethyl cis-3-iodo-acry-
late (1A) (90 mg, 0.40 mmol), pyridine-2-thiol (58.9 mg, 0.53 mmol),
4.1.13. Preparation of (Z)-3-(thiophen-2-ylthio)-acrylic acid
ethyl ester (11)
The general procedure (A) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (90 mg, 0.40 mmol), cyclohexanethiol (61.6 mg,
0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis 1,2-cyclohexanediol, L
(8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF
(2.0 mL) were stirred at 40–50 °C to obtain thioether 11 as a color-
less oil. Column chromatography solvent (3–5% EtOAc in hexane)
provided pure 11 (81 mg, 94% yield): 1H NMR (300 MHz, CDCl3):
d 7.17 (1H, d, J = 17.6 Hz, HC(S)=CH), d 5.84 (1H, d, J = 10.2 Hz,
HC=CH-S), d 4.21 (2H, q, J = 7.0 Hz, J = 21.4 Hz, H2C-CH3), d 2.88–
2.81 (5H, m, HCy), d 2.06–1.38 (5H, m, HCy), d 1.30 (3H, t,
J = 7.1 Hz, H3C-CH2). 13C NMR (75 MHz, CDCl3): d 166.6, 148.2,
112.5, 59.9, 47.5, 33.5, 25.7, 25.3, 14.3. HRMS (ESI) (M+H)+, calcd
for C9H11O2S2 215.0122; found 215.0127.
CuI (7.6 mg, 0.040 mmol), cis 1,2-cyclohexanediol
L (8.2 mg,
0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF (2.0 mL) were
stirred at 40–50 °C to obtain the thioether 7 as a colorless solid. Col-
umn chromatography (solvent 10% EtOAc in hexane) provided pure
7 (81 mg, 97% yield): 1H NMR (300 MHz, CDCl3): d 8.55 (2H, d,
J = 10.2 Hz, HAr), d 7.60 (1H, t, J = 7.7 Hz, HAr), d 7.34–7.28 (1H, m,
HC(S)=CH), d 7.16–7.12 (1H, m, HAr), d 6.11 (1H, d, J = 10.2 Hz,
HC=CH-S), d 4.27 (2H, q, J = 7.2 Hz, J = 21.4 Hz, H2C-CH3), d 1.34 (3H,
t, J = 7.1 Hz, H3C-CH2). 13C NMR (75 MHz, CDCl3): d 166.7, 155.2,
149.5, 141.8, 136.7, 123.2, 121.2, 113.8, 60.3, 14.2. HRMS (ESI)
(M+H)+, calcd for C10H12NO2S 210.0589; found 210.0591.
4.1.10. Preparation of (Z)-3-(naphthalen-1-ylthio)-acrylic acid
ethyl ester (8)
4.1.14. Preparation of (Z)-3-cyclohexylsulfanyl-acrylic acid ethyl
ester (12)
General procedure (A) was followed (2 h). Ethyl cis-3-iodo-acry-
late 1A (90 mg, 0.40 mmol), 1-naphthalenethiol (84.9 mg, 0.53
mmol), CuI (7.6 mg, 0.040 mmol), cis 1,2-cyclohexanediol (8.2 mg,
0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF (2.0 mL) were
stirred at 40–50 °C to obtain the thioether 8 as a colorless solid.
Column chromatography (solvent 10% EtOAc in hexane) provided
pure 8 (96 mg, 93% yield): 1H NMR (300 MHz, CDCl3): d 8.40 (1H,
d, J = 8 Hz, HAr), d 7.92 (2H, d, J = 8.4 Hz, HAr), d 7.81 (1H, d,
J = 6.9 Hz, HAr), d 7.62–7.54 (2H, m, HAr), d 7.51–7.46 (1H, m,
HAr), d 7.15 (1H, d, J = 10 Hz, HC(S)=CH), d 5.94 (1H, d, J = 10 Hz,
HC=CH-S), d 4.31 (2H, q, J = 7.1 Hz, H2C-CH3), d 1.34 (3H, t,
J = 7.1 Hz, H3C-CH2). 13CNMR:166.6, 150.7, 134.1, 133.3, 132.1,
129.8, 128.5, 127.0, 126.4, 125.5, 113.2, 60.2, 14.3. HRMS (ESI)
(M+H)+, calcd for C15H15O2S 258.0715; found 258.0789.
The general procedure (A) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (90 mg, 0.40 mmol), cyclohexanethiol (61.6 mg,
0.53 mmol), CuI (7.6 mg, 0.040 mmol), cis 1,2-cyclohexanediol, L
(8.2 mg, 0.080 mmol), K3PO4 (127 mg, 0.60 mmol) and DMF
(2.0 mL) were stirred at 40–50 °C to obtain the thioether 12 as a
colorless oil. Column chromatography solvent (3–5% EtOAc in hex-
ane) provided pure 12 (81 mg, 94% yield): 1H NMR (300 MHz,
CDCl3): d 7.17 (1H, d, J = 17.6 Hz, HC(S)=CH), d 5.84 (1H, d,
J = 10.2 Hz, HC=CH-S), d 4.21 (2H, q, J = 7.0 Hz, J = 21.4 Hz, H2C-
CH3), d 2.88–2.81 (5H, m, HCy), d 2.06–1.38 (5H, m, HCy), d 1.30
(3H, t, J = 7.1 Hz, H3C-CH2). 13C NMR (75 MHz, CDCl3): d 166.6,
148.2, 112.5, 59.9, 47.5, 33.5, 25.7, 25.3, 14.3. HRMS (ESI)
(M+H)+, calcd for C11H18O2S 215.1106; found 215.1107.
4.1.11. Preparation of (Z)-3-(2-Isopropyl-phenylsulfanyl)-acrylic
acid ethyl ester (9)
4.1.15. Preparation of (Z)- 3-(4-tert-butyl-phenoxy)-acrylic acid
ethyl ester (13)
General procedure (A) was followed (2 h). Ethyl cis-3-iodo-acry-
late 1A (90 mg, 0.40 mmol), 2-isopropyl-benzenethiol (80.7 mg,
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3

M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
4183
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), 4-tert-butylphenol
(99.1 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 13 as a colorless oil. Column chromatography on sil-
ica gel (5% EtOAc in hexane) provided pure 13 (101.6 mg, 93%
yield): 1H NMR (300 MHz, CDCl3): d 7.81 (1H, d, J = 12.2 Hz,
H(O)C=CH), d 7.43–7.38 (2H, m, HAr), d 7.04–6.99 (2H, m, HAr), d
5.54 (1H, d, J = 12.2 Hz, HC=C(O)H), d 4.21 (2H, q, J = 3.6 Hz,
J = 10.7 Hz, H2C-CH3); d 1.34 (9H, s, H3C-C-), d 1.30 (3H, t,
J = 7.1 Hz, H3C–CH2). 13C NMR (75 MHz, CDCl3): d 166.2, 158.5,
152.6, 147.2, 126.5, 117.4, 101.6, 60.1, 35.3, 32.6, 15.5. HRMS
(ESI) (M+H)+, calcd for C15H21O3 249.1491; found 249.1502.
91% yield): 1H NMR (300 MHz, CDCl3): d 7.90–7.85 (2H, m, HAr), d
7.84 (1H, d, J = 12.2 Hz, HC(O)@CH), d 7.20–7.13 (2H, m, HAr), d
5.70 (1H, d, J = 12.2 Hz, HC@CH(O)), d 4.23 (2H, m, H2CCH3) d
1.31 (3H, m, H3C–CH2). HRMS (ESI) (M+H)+, calcd for C12H14NO4
236.0923; found 236.0926.
4.1.20. (Z)-3-(3,5-Dimethoxy-phenoxy)-acrylic acid ethyl ester
(18)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), 3,5-dimethoxy-
phenol (101.8 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at
40 °C to obtain the ether 18 as a colorless oil. Column chromatog-
raphy on silica gel (5% EtOAc in hexane) provided pure 18
(108.8 mg, 98% yield): 1H NMR (300 MHz, CDCl3): d 7.78 (1H, d,
J = 12.2 Hz, HC(O)@CH), d 6.30 (1H, t, J = 2.2 Hz, HAr), d 6.25–6.24
(2H, m, HAr), d 5.59 (1H, d, J = 12.2 Hz, HC@CH–O), d 4.22 (2H, q,
J = 3.6 Hz, J = 10.7 Hz, H2C–CH3), d 3.80 (6H, s, H3CO), d 1.31 (3H,
t, J = 7.1 Hz, H3C–CH2).13C NMR (75 MHz, CDCl3): d 167.1, 161.6,
158.4, 157.5, 102.3, 96.9, 96.5, 60.0, 55.4, 14.2. HRMS (EI), calcd
for C13H16O5 252.0998; found 252.1007.
4.1.16. Preparation of (Z)-3-(4-fluoro-phenoxy)-acrylic acid
ethyl ester (14)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), 4-fluorophenol
(74.0 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 14 as a colorless oil. Column chromatography on sil-
ica gel (5% EtOAc in hexane) provided pure 14 (77.8 mg, 84% yield):
1H NMR (300 MHz, CDCl3): d 7.75 (1H, d, J = 12.2 Hz, HC(O)@CH), d
7.12–7.02 (4H, m, HAr), d 5.52 (1H, d, J = 12.2 Hz, HC@CH–O), d
4.21 (2H, q, J = 3.6 Hz, J = 10.7 Hz, H2C–CH3),
d
1.30 (3H, t,
4.1.21. Preparation of (Z)-(3)-(o-tolyloxy)-acrylic acid ethyl
ester (19)
J = 7.1 Hz, H3C–CH2). 13C NMR (75 MHz, CDCl3): d 161.3, 159.2,
119.7, 119.6, 116.6, 116.3, 102.1, 60.0, 14.2. HRMS (EI), calcd for
C11H11O3 210.0692; found 210.0690.
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), o-cresol (71.4 mg,
0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to obtain the
ether 19 as a colorless oil. Column chromatography on silica gel
(5% EtOAc in hexane) provided pure 19 (84 mg, 93% yield): 1H
NMR (300 MHz, CDCl3): d 7.81 (1H, d, J = 12 Hz, HC(O)@CH), d
7.25–7.20 (2H, m HAr), d 7.15–7.10 (1H, m HAr), d 7.02 (1H, d,
J = 9 Hz), d 5.40 (1H, d, J = 12 Hz, HC@CH(O)), d 4.23 (2H, q,
J = 6.0 Hz, J = 14.1 Hz, H2CCH3), d 2.26 (1H, s, CH3), d 1.29 (3H, t,
J = 6.9 Hz, H3C-CH2). 13C NMR (75 MHz, CDCl3): d 167.2, 159.9,
153.6, 131.4, 128.8, 127.2, 125.2, 118.4, 100.9, 59.9, 15.7, 14.2.
HRMS (ESI) (M+Li)+, calcd for C12H14O3Li 213.1103; found
213.1106.
4.1.17. Preparation of (Z)-3-(3-fluorophenoxy)-acrylic acid ethyl
ester (15)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), 3-fluorophenol
(74.0 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 15 as a colorless oil. Column chromatography on sil-
ica gel (5% EtOAc in hexane) provided pure 15 (72.1 mg, 78% yield):
1H NMR (300 MHz, CDCl3): 7.79 (1H, d, J = 12 Hz, HC(O)=CH), d
7.37–7.29 (1H, m, HAr), d 6.95–6.80 (3H, m, HAr), d 5.64 (1H, d,
J = 12 Hz, HC@CH(O)),
d 4.23 (2H, q, J = 7.1 Hz, J = 14.2 Hz,
H2CCH3), d 1.28 (3H, t, J = 7.1 Hz, H3C-CH2). 13C NMR (75 MHz,
CDCl3): d 166.8, 165.9, 157.8, 130.8, 113.4, 111.9, 106.1, 103.1,
60.1, 14.2. HRMS (ESI) (M+H)+, calcd for C11H12FO3 211.0770;
found 211.0767.
4.1.22. Preparation of (Z)-3-(2-isopropyl-phenoxy)-acrylic acid
ethyl ester (20)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), 2-isopropylphenol
(89.9 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 20 as a colorless oil. Column chromatography on sil-
ica gel (5% EtOAc in hexane) provided pure 20 (97.9 mg, 95% yield):
1H NMR (300 MHz, CDCl3): d 7.80 (1H, d, J = 12.3 Hz, HC(O)@CH), d
7.34–7.30 (1H, m, HAr), d 7.26–7.16 (2H, m, HAr), d 7.02–6.99 (1H,
m, HAr), d 5.46 (1H, d, J = 12.3 Hz, HC@CH–O), d 4.20 (2H, q,
J = 3.6 Hz, J = 10.7 Hz, H2C–CH3), d 3.22 (1H, hep, HC(CH3)2), d
1.35–1.23 (9H, m, H3C–CH2 and (H3C)2CH). 13C NMR (75 MHz,
CDCl3): d 167.3, 160.3, 152.9, 139.2, 127.0, 125.5, 118.5, 101.2,
59.9, 27.0, 22.8, 14.2. HRMS (ESI) (M+H)+, calcd for C14H19O3
235.1334; found 235.1334.
4.1.18. Preparation of (Z)-3-(3-nitrophenoxy)-acrylic acid ethyl
ester (16)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), 3-nitrophenol
(91.8 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 16 as a colorless oil. Column chromatography on sil-
ica gel (5% EtOAc in hexane) provided pure 16 (67.8 mg, 65% yield):
1H NMR (300 MHz, CDCl3): d 8.10–8.07 (1H, m HAr), 7.96 (1H, t,
J = 2.2 Hz, HAr), 7.82 (1H, d, J = 12 Hz, HC(O)@CH), d 7.59 (1H, t,
J = 8.2 Hz, HAr), d 7.46–7.42 (1H, m HAr), d 5.71 (1H, d, J = 12 Hz,
HC@CH(O)), d 4.28 (2H, q, J = 7.1 Hz, J = 14.2 Hz, H2CCH3), d 1.32
(3H, t, J = 7.1 Hz, H3C–CH2). 13C NMR (75 MHz, CDCl3): d 166.4,
156.8, 156.0, 153.1, 130.7, 123.9, 119.6, 113.0, 104.5, 60.4, 14.2.
4.1.23. Preparation of (Z)-3-(2-methylbenzoate)-acrylic acid
ethyl ester (21)
4.1.19. Preparation of (Z)-3-(4-carbamoylphenoxy)-acrylic acid
ethyl ester (17)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), methyl salicylate
(100.4 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to
obtain the ether 21 as a colorless oil. Column chromatography on
silica gel (5% EtOAc in hexane) provided pure 21 (82.6 mg, 75%
yield): 1H NMR (300 MHz, CDCl3): d 7.93 (1H, dd, J = 1.7 Hz,
J = 7.8 Hz, HAr), 7.76 (1H, d, J = 12 Hz, HC(O)@CH), d 7.57 (1H, dt,
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), 4-hydroxyben-
zamide (90.51 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at
40 °C to obtain the ether 17 as a colorless oil. Column chromatog-
raphy on silica gel (5% EtOAc in hexane) provided pure 17 (94 mg,

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M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
J = 1.7 Hz, J = 7.8 Hz, HAr), d 7.30 (1H, m, HAr), d 7.09 (1H, d,
J = 8 Hz, HAr), d 5.46 (1H, d, J = 12 Hz, HC@CH(O)), d 4.23 (2H, q,
J = 7.1 Hz, J = 14.2 Hz, H2CCH3), d 3.91 (3H, s, OCH3), d 1.31 (3H, t,
J = 6.9 Hz, H3C–CH2). HRMS (ESI) (M+H)+, calcd for C13H15O5
251.0919; found 251.0917.
HC(O)@CH), d 7.48–7.36 (3H, m, HAr), d 7.31–7.26 (1H, m, HAr),
d 6.95 (1H, d, J = 14.3 Hz, HC@CH–O), d 4.30 (2H, q, J = 3.6 Hz,
J = 10.7 Hz, H2C–CH3), d 1.36 (3H, t, J = 7.2 Hz, H3C–CH2). 13C NMR
(75 MHz, CDCl3): d 168.8, 167.1, 134.8, 133.5, 126.8, 124.7, 122.9,
122.0, 111.5, 110.4, 60.7, 14.2. HRMS (ESI) (M+H)+, calcd for
C12H12NO3S 250.0538; Found 250.0540.
4.1.24. Preparation of (Z)-3-(naphtalen-1-yloxy)-acrylic acid
ethyl ester (22)
4.1.28. Preparation of (Z)-3-(pyridin-3-yloxy)-acrylic acid ethyl
ester (26)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), naphthalene-1-ol
(95.2 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 22 as a colorless oil. Column chromatography on sil-
ica gel (5% EtOAc in hexane) provided pure 22 (102.3 mg, 96%
yield): 1H NMR (300 MHz, CDCl3): d 8.12–8.09 (1H, m HAr) d
7.97 (1H, d, J = 12.2 Hz, HC(O)@CH), d 7.92–7.87 (1H, m HAr), d
7.73–7.70 (1H, m HAr, d 7.63–7.56 (2H, m HAr), d 7.46 (1H, t,
The general procedure (B)was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol) CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), pyridine-3-ol
(62.8 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 26 as a colorless oil. Column chromatography solvent
(15% EtOAc in hexane) provided pure 26 (73.0 mg, 86% yield): 1H
NMR (300 MHz, CDCl3): d 8.48 (2H, m, HAr), d 7.78 (1H, d,
J = 12.2 Hz, HC(O)@CH), d 7.46–7.41 (1H, m, HAr), d 7.37–7.33
(1H, m, HAr), d 5.62 (1H, d, J = 12.2 Hz, HC@CH–O), d 4.22 (2H, q,
J = 3.6 Hz, J = 10.7 Hz, H2C–CH3), d 1.30 (3H, t, J = 7.1 Hz, H3C–
CH2) ppm. 13C NMR (75 MHz, CDCl3): d 166.6, 157.8, 152.2,
146.2, 140.7, 125.1, 124.2, 103.6, 60.2, 14.2 ppm. HRMS (ESI)
(M+H)+, calcd for C10H12NO3 194.0817; found 194.0819.
J = 7.8 Hz, HAr),
d
7.17–7.15 (1H,
m HAr), d 5.65 (1H, d,
J = 12.2 Hz, HC@CH(O)),
d
4.25 (2H, q, J = 6.0 Hz, J = 15.4 Hz,
H2CCH3) d 1.31 (3H, t, J = 7.1 Hz, H3C–CH2). 13C NMR (75 MHz,
CDCl3): d 167.1, 159.6, 151.7, 134.6, 127.7, 126.8, 126.4, 125.7,
125.4, 125.0, 121.3, 112.7, 102.4, 60.0, 14.2. HRMS (ESI) (M+H)+,
calcd for C15H15O3 243.1021; found 243.1013.
4.1.29. Preparation of (Z)-3-(1H-indol-1-yl)-acrylic acid ethyl
ester (27)
4.1.25. Preparation of (Z)-3-(naphtalen-2-yloxy)-acrylic acid
ethyl ester (23)
The general procedure (B) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol), indole (77.3 mg,
0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to obtain the
vinyl amine 27 as an off-white solid. Column chromatography on
silica gel (5% EtOAc in hexane) provided pure 27 (71 mg, 75%
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), naphthalene-2-ol
(95.2 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 23 as a colorless oil. Column chromatography on sil-
ica gel (5% EtOAc in hexane) provided pure 23 (99 mg, 93% yield):
1H NMR (300 MHz, CDCl3): d 7.97 (1H, d, J = 12 Hz, HC(O)=CH), d
7.89–7.80 (3H, m HAr), d 7.56–7.45 (3H, m HAr), d 7.28 (1H, d,
J1 = 9 Hz, J2 = 3 Hz, HAr), d 5.67 (1H, d, J = 12 Hz, HC@CH(O)), d
yield): 1H NMR (300 MHz, CDCl3):
d 8.33 (1H, d, J = 14 Hz,
HC(O)@CH), d 7.64 (d, 1H, J = 3.3 Hz, HAr), d 7.61 (1H, m, HAr), d
7.41 (1H, d, J = 3.5 Hz, HAr), d 7.35 (1H, m, HAr), 7.25 (1H, m,
HAr), d 6.75 (1H, d, J = 3.5 Hz, HAr), d 6.00 (1H, d, J = 14 Hz,
HC@CH(O)), d 4.31 (2H, q, J = 7.1 Hz, H2CCH3), d 1.37 (3H, t,
J = 7.1 Hz, H3C–CH2). 13C NMR (75 MHz, CDCl3): d 167.3, 137.0,
136.0, 129.7, 123.8, 123.4, 122.3, 121.4, 109.9, 108.6, 100.5,
103.2, 60.2, 14.3. Elemental Anal. Calcd for C13H13NO2?0.27 H2O:
C, 70.95; H, 6.20; N, 6.36. Found: C, 70.95; H, 6.10; N, 6.32.
4.25 (2H, q, J = 6.0 Hz, J = 14.4 Hz, H2CCH3)
d 1.32 (3H, t,
J = 7.2 Hz, H3C–CH2). 13C NMR (75 MHz, CDCl3): d 167.1, 158.7,
153.4, 133.8, 130.7, 130.1, 127.7, 127.2, 126.8, 125.3, 118.5,
113.5, 102.5, 60.0, 14.2. HRMS (ESI) (M+H)+, calcd for C15H15O3
243.1021; found 243.1025.
4.1.26. Preparation of (Z)-3-(3-methylthiophene-2-carboxylate)-
acrylic acid ethyl ester (24)
4.1.30. Preparation of (Z)-3-(1H-pyrazol-1-yl)-acrylic acid ethyl
ester (28)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), methyl 3-hydroxy-
2-thiophenecarboxylate (104.4 mg, 0.66 mmol) and DMF (2.0 mL)
were stirred at 40 °C to obtain the ether 24 as a colorless oil. Column
chromatography on silica gel (5% EtOAc in hexane) provided pure 24
(92.4 mg, 82% yield): 1H NMR (300 MHz, CDCl3): d 7.76 (1H, d,
J = 12 Hz, HC(O)@CH), d 7.51 (1H, d, J = 5.4 Hz, HAr), d 6.92 (1H, d,
J = 5.4 Hz, HAr), d 5.58 (1H, d, J = 12 Hz, HC@CH(O)), d 4.24 (2H, q,
J = 7.1 Hz, J = 14.2 Hz, H2CCH3), d 3.88 (3H, s, OCH3), d 1.29 (3H, t,
J = 6.9 Hz, H3C-CH2). 13C NMR (75 MHz, CDCl3): d 167.0, 159.2,
158.1, 144.0, 137.4, 130.6, 120.8, 102.3, 60.1, 52.0, 14.2. HRMS
(ESI) (M+H)+, calcd for C11H13O5S 257.0484; found 257.0481.
The general procedure (B) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol), 1H-pyrazole
(45 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the vinyl amine 28 as a white solid. Column chromatography
on silica gel (5% EtOAc in hexane) provided pure 28 (67.3 mg, 92%
yield): 1H NMR (300 MHz, CDCl3): d 8.03 (1H, d, J = 13.9 Hz,
HC(O)@CH), d 7.74 (1H, br, HAr), d 7.68 (1H, d, J = 2.5 Hz, HAr), d
6.46 (1H, m, HAr), d 6.39 (1H, d, J = 13.9 Hz, HC@CH(O)), d 4.29
(2H, q, J = 7.1 Hz, H2CCH3), d 1.32 (3H, t, J = 7.1 Hz, H3C-CH2). 13C
NMR (75 MHz, CDCl3): d 166.4, 143.3, 139.4, 129.8, 108.9, 105.7,
60.5, 14.1. HRMS (EI), calcd for C8H10N2O2 166.0742; found
166.0716.
4.1.27. Preparation of (Z)-3-(benzothiazol-2-yloxy)-acrylic acid
ethyl ester (25)
4.1.31. Preparation of (Z)-3-[3-(trifluoromethyl]-1H-pyrazol-1-
yl)-acrylic acid ethyl ester (29)
The general procedure (B) was followed (2 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (4.2 mg, 0.022 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (4.3 mg, 0.022 mmol), benzothiazol-2-ol
(99.8 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the ether 25 as a colorless oil. Column chromatography on sil-
ica gel (10% EtOAc in hexane) provided pure 25 (100.9 mg, 92%
yield): 1H NMR (300 MHz, CDCl3): d 7.94 (1H, d, J = 14.3 Hz,
The general procedure (B) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol), 3-(trifluoro-
methyl)-1H-pyrazole (89.8 mg, 0.66 mmol) and DMF (2.0 mL) were
stirred at 40 °C to obtain the vinyl amine 29 as a white solid. Col-
umn chromatography on silica gel (5% EtOAc in hexane) provided
pure 29 (99 mg, 96% yield): 1H NMR (300 MHz, CDCl3): d 7.99

M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
4185
(1H, d, J = 14 Hz, HC(O)@CH), d 7.74 (1H, d, J = 1.6 Hz, HAr), d 7.70
(1H, d, J = 2.5 Hz, HAr), d 6.53 (1H, d, J = 14 Hz, HC@CH(O)), d 4.29
(2H, q, J = 7.1 Hz, H2CCH3), d 1.34 (3H, t, J = 7.1 Hz, H3C–CH2). 13C
NMR (75 MHz, CDCl3): d 165.5, 138.5, 131.1, 122.2, 118.5, 109.1,
106.8, 60.8, 14.1. HRMS (EI), calcd for C9H9F3N2O2 234.0616; found
234.0608.
4.32 (2H, q, J = 7.1 Hz, H2CCH3), d 1.37 (3H, t, J = 7.1 Hz, H3C–
CH2).13C NMR (75 MHz, CDCl3): d 167.2, 139.5, 138.9, 136.5,
128.2, 125.5, 123.1, 121.5, 109.5, 103.2, 60.3, 14.1. Elemental Anal.
Calcd for C12H12N2O2: C, 66.65; H, 5.59; N, 12.96. Found: C, 66.51;
H, 5.65; N, 12.85.
4.1.36. Preparation of (Z)-3-(5-(methylthio)-1H-tetrazol-1-yl)-
acrylic acid ethyl ester (34)
4.1.32. Preparation of (Z)-3-(1H-imidazol-1-yl)-acrylic acid ethyl
ester (30)
The general procedure (B) was followed (40–50 °C, 2–4 h). Ethyl
cis-3-iodo-acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011
mmol), Cs2CO3 (67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol),
5-(methylsulfanyl)-1H-tetraazole (76.6 mg, 0.66 mmol) and DMF
(2.0 mL) were employed to obtain the vinyl amine 34 (34 mg,
0.158 mmol, 36% yield) as a yellowishsemisolid. Column chromatog-
raphy on silica gel (5% EtOAc in hexane) provided pure 34 (spectral
data matches that previously reported for compound 349): 1H NMR
(300 MHz, CDCl3): d 7.94 (1H, d, J = 14.1 Hz, HC(O)@CH), d 6.77 (1H,
d, J = 14.1 Hz, HC@CH(O)), d 4.34 (2H, q, J = 7.1 Hz, H2CCH3), d 1.37
(3H, t, J = 7.1 Hz, H3C-CH2). HRMS (EI), calcd for C7H10N4O2S
214.0524; found 214.0515.
The general procedure (B) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol), 1H-imidazole
(45 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the vinyl amine 30 as a colorless oil. Column chromatography
on silica gel (5% EtOAc in hexane) provided pure 30 (29 mg, 40%
yield): 1H NMR (300 MHz, CDCl3): d 7.93 (1H, d, J = 14.2 Hz,
HC(O)@CH), d 7.81 (1H, s, HAr), d 7.26 (1H, s, HAr), d 7.20 (1H, s,
HAr),
d 6.10 (1H, d, J = 14.2 Hz, HC@CH(O)), d 4.30 (2H, q,
J = 7.1 Hz, H2CCH3), d 1.33 (3H, t, J = 7.1 Hz, H3C–CH2). 13C NMR
(75 MHz, CDCl3): d 166.1, 137.7, 136.2, 131.6, 116.1, 107.1, 60.8,
14.1. HRMS (EI), calcd for C8H10N2O2 166.0742; found 166.0769.
4.2. Biology
4.1.33. Preparation of (Z)-3-(1H-1,2,4-triazol-1-yl)-acrylic acid
ethyl ester (31)
All anti-Mycobacterium activity evaluations (except for the anti-
M. tuberculosis assays) were performed using minimum inhibitory
concentration assays in Middlebrook 7H9 broth with 10% OADC.
The Mycobacterium cultures were grown statically for seven days
in Middlebrook 7H9 broth with 10% OADC at 35 °C. Microtiter
plates were incubated for 48 h at 35 °C and scored as either growth
or no growth. Rifampin was used as the positive control. All other
antimicrobial activity evaluations were performed using minimum
inhibitory concentration assays in Cation-adjusted Mueller–Hin-
ton–Broth.15 Cultures were grown statically overnight on tryptic
soy agar medium, incubated at 35 °C. Cultures included S. aureus
ATCC 29213, B. cereus, and E. coli ATCC 29522. Microtiter plates
were incubated for 18–24 h at 35 °C and scored as either growth
or no growth. Tetracycline controls were included that correlated
with established MIC values.15
The anti-M. tuberculosis activity evaluations were performed
using a green fluorescent protein (GFP)-based assay to measure
the efficacy of 3 and 4 against M. tuberculosis. Briefly, a gfp gene
was cloned into the high copy number pHIGH plasmid, creating
pHIGH22.13 The pHIGH22 plasmid was transferred into M. tubercu-
losis H37Rv. Early logarithmic cultures of M. tuberculosis H37Rv/
pHIGH22 were diluted in 96-well microtiter plates to an O.D.600
of 0.025 in Middlebrook 7H9 medium. Test compounds were
The general procedure (B) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol), 1H-1,2,4-triazole
(45.6 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the vinyl amine 31 as a white solid. Column chromatography
on silica gel (5% EtOAc in hexane) provided pure 31 (68.4 mg, 93%
yield): 1H NMR (300 MHz, CDCl3): d 8.35 (s, 1H, HAr), 8.08 (s, 1H,
HAr), 8.03 (1H, d, J = 13.8 Hz, HC(O)@CH),
d 6.63 (1H, d,
J = 13.8 Hz, HC@CH(O)), d 4.31 (2H, q, J = 7.1 Hz, H2CCH3), d 1.35
(3H, t, J = 7.1 Hz, H3C–CH2).13C NMR (75 MHz, CDCl3): d 165.5,
153.5, 144.5, 134.9, 110.4, 61.0, 14.1. HRMS (EI), calcd for
C7H9N3O2 167.0694; found 167.0666.
4.1.34. Preparation of (Z)-3-(1H-benzo[d][1,2,3]triazol-1-yl)-
acrylic acid ethyl ester (32)
The general procedure (B) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol), 1H-1,2,3-benzo-
triazole (78.6 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at
40 °C to obtain the vinyl amine 32 as a white crystalline solid. Col-
umn chromatography on silica gel (5% EtOAc in hexane) provided
pure 32 (90.8 mg, 95% yield): 1H NMR (300 MHz, CDCl3): d 8.55
(1H, d, J = 14.3 Hz, HC(O)@CH), d 8.17 (d, 1H, J = 8.3 Hz, HAr), d
7.77 (1H, d, J = 8.3 Hz, HAr), d 7.66 (1H, t, J = 7.4 Hz, HAr), d 7.50
(1H, t, J = 7.4 Hz, HAr), d 6.79 (1H, d, J = 14.3 Hz, HC@CH(O)), d
4.36 (2H, q, J = 7.1 Hz, H2CCH3), d 1.39 (3H, t, J = 7.1 Hz, H3C–
CH2). 3C NMR (75 MHz, CDCl3): d 165.8, 146.5, 135.0, 131.4,
129.2, 125.3, 120.7, 110.0, 108.1, 60.9, 14.1. HRMS (EI), calcd for
C11H11N3O2 217.0851; found 217.0832.
resuspended in DMSO to concentrations of 20 lg/ml and serially
diluted twofold. Fluorescence was measured in a FLUOstar Omega
microplate reader (BMG Labtech, San Francisco, CA) after seven
days of growth at 37 °C. If the drug killed the bacteria, the fluores-
cence emitted from the plasmid would be extinguished in a man-
ner similar to that described in a previous study using luciferase
rather than GFP.16 Both isoniazid (INH) and rifampin (RIF) were
used as the positive controls.13
4.1.35. Preparation of (Z)-3-(1H-indazol-1-yl)-acrylic acid ethyl
ester (33)
A tryptan exclusion assay employing murine J774A.1 (ATCC)
monocyte cell lines was employed to assess the cytotoxicity of se-
lected compounds. Briefly, monocytes were seeded at 1 Â 106/well
in a 24-well tissue culture plate with RPMI 1640 medium (Invitro-
gen). The next day, twofold dilutions of the test drug in PBS were
added to each well with RPMI 1640 medium. On the following
day, the spent medium was removed by aspiration, and a trypan
blue solution was added to each well. After 10 min elapsed, the try-
pan blue solution was removed by aspiration, and an equal volume
of PBS was added. Three fields of cells were counted per well. The
number of dead (blue) and live (clear) cells was determined. An
IC50 value was calculated for each well with 50% dead cells.
The general procedure (B) was followed (4 h). Ethyl cis-3-iodo-
acrylate 1A (100 mg, 0.44 mmol), CuI (2.1 mg, 0.011 mmol), Cs2CO3
(67.5 mg, 0.80 mmol), L3 (2.15 mg, 0.011 mmol), 1H-indazole
(78 mg, 0.66 mmol) and DMF (2.0 mL) were stirred at 40 °C to ob-
tain the vinyl amine 33 as a white solid. Column chromatography
on silica gel (5% EtOAc in hexane) provided pure 33 (90.4 mg, 95%
yield): 1H NMR (300 MHz, CDCl3): d 8.38 (1H, d, J = 13.7 Hz,
HC(O)@CH), d 8.22 (s, 1H, HAr), d 7.79 (1H, d, J = 8 Hz, HAr), d
7.69 (1H, d, J = 8.4 Hz, HAr), d 7.54 (1H, t, J = 7.5 Hz, HAr), d 7.32
(1H, t, J = 7.5 Hz, HAr), d 6.55 (1H, d, J = 13.7 Hz, HC@CH(O)), d

4186
M. S. Kabir et al. / Bioorg. Med. Chem. 18 (2010) 4178–4186
Monte, M. Bioorg. Med. Chem. Lett. 2008, 18, 5745; (b) Monte, A.; Kabir, M. S.;
Acknowledgments
Cook, J. M.; Rott, M.; Schwan, W. R.; Defoe, L. U.S. Pat. Appl. Publ., 2007, 37 pp.
6. Unpublished results.
We wish to acknowledge financial assistance from the Research
Growth Initiative of the University of Wisconsin-Milwaukee
(J.M.C.) and a UW-System Applied Research Grant (A.M.).
7. Neck, T. V.; Pannecouque, C.; Vanstreels, E.; Stevens, M.; Dehaen, W.;
Daelemans, D. Bioorg. Med. Chem. 2008, 16, 9487.
8. Kabir, M. S.; Linn, M. L. V.; Monte, M.; Cook, J. M. Org. Lett. 2008, 10, 3363.
9. Kabir, M. S.; Lorenz, M.; Namjoshi, O. A.; Cook, J. M. Org. Lett. 2010, 12, 464.
10. Kawashita, Y.; Ueba, C.; Hayashi, M. Tetrahedron Lett. 2006, 47, 4231.
11. Haneda, S.; Zhibin, G.; Eda, K.; Hayashi, M. Organometallics 2007, 26, 6551.
12. Haneda, S.; Adachi, Y.; Hayashi, M. Tetrahedron 2009, 65, 10459.
13. Bourn, W. R.; Jansen, Y.; Stutz, H.; Warren, R. M.; Williamson, A.-L.; van Helden,
P. D. Tuberculosis 2007, 87, 481.
14. Hathaway, W. E.; Newby, L. A.; Githens, J. H. Blood 1964, 23, 517.
15. Wayne, P. A. Methods for dilution antimicrobial susceptibility tests for bacteria
that grow aerobically, 6th ed.; Clinical and Laboratory Standards Institute, 2005.
Approved standard M7–A6.
References and notes
1. World Health Organization, Global Tuberculosis Report 2009, http://
www.who.int/tb/publications/global_report/2009/pdf/fullreport.pdf.
2. Harper, C. Nat. Med. 2007, 13, 309.
3. Lew, W.; Pai, M.; Oxlade, O.; Martin, D.; Menzies, D. Ann. Intern. Med. 2008, 149,
123.
4. Cox, H.; Kebede, Y.; Allamuratova, S.; Ismailov, G.; Davletmuratova, G.; Byrnes,
G.; Stone, C.; Niemann, S.; Rüsch-Gerdes, S.; Blok, L.; Doshetov, D. PLoS Med.
2006, 3, e384.
16. Mdluli, K.; Sherman, D. R.; Hickey, M. J.; Kreiswirth, B. N.; Morris, S.; Stover, C.
K.; Barry, C. E. J. Infect. Dis. 1996, 174, 1085.
5. (a) Kabir, M. S.; Engelbrecht, K.; Polanowski, R.; Krueger, S. M.; Ignasiak, R.;
Rott, M.; Schwan, W. R.; Stemper, M. E.; Reed, K. D.; Sherman, D.; Cook, J. M.;