Anticancer activity of novel hybrid molecules containing 5-benzylidene thiazolidine-2,4-dione

Article abstract of DOI:10.1016/j.ejmech.2013.02.030

Hybridization of two different bioactive molecules with different mechanism of action is one of the methods that are being adopted to treat cancer. Molecules bearing a thiazolidine-2,4-dione scaffold have been recognized as antineoplastic agents with a broad spectrum of activity against many cancer cell lines. In this manuscript we have described the synthesis and biological evaluation of two series of N-3-substituted-5-arylidene thiazolidine-2,4-diones, bearing the α-bromoacryloylamido moiety at the para- or meta-position on the phenyl of the arylidene portion. We have observed that selected compounds 5a, 5c and 5g suppress proliferation of human myeloid leukaemia HL-60 and U937 cells by triggering morphological changes and internucleosomal DNA fragmentation, which are well-known features of apoptosis. Finally, our results indicated that the investigated compounds induced apoptotic cell death through a mechanism that involved activation of multiple caspases and was also associated with the release of cytochrome c from the mitochondria.

Full text of DOI:10.1016/j.ejmech.2013.02.030

Accepted Manuscript
Anticancer Activity of Novel Hybrid Molecules Containing 5-Benzylidene
Thiazolidine-2,4-dione
Romeo Romagnoli, Pier Giovanni Baraldi, Maria Kimatrai Salvador, M. Encarnacion
Camacho, Jan Balzarini, Jaime Bermejo, Francisco Estévez
PII:
S0223-5234(13)00137-2
10.1016/j.ejmech.2013.02.030
EJMECH 6025
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 21 January 2013
Revised Date: 18 February 2013
Accepted Date: 21 February 2013
Please cite this article as: R. Romagnoli, P.G. Baraldi, M.K. Salvador, M.E. Camacho, J.
Balzarini, J. Bermejo, F. Estévez, Anticancer Activity of Novel Hybrid Molecules Containing 5-
Benzylidene Thiazolidine-2,4-dione, European Journal of Medicinal Chemistry (2013), doi: 10.1016/
j.ejmech.2013.02.030.
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*Graphical Abstract (for review)
Click here to download Graphical Abstract (for review): Graphical Abstract EJMECH-D-13-00139.doc
ACCEPTED MANUSCRIPT
Anticancer Activity of Novel Hybrid Molecules Containing 5-
Benzylidene Thiazolidine-2,4-dione
Romeo Romagnolia, Pier Giovanni Baraldi a, Maria Kimatrai Salvadora, M.
R1
N
Encarnacion Camachoa, Jan Balzarinib, Jaime Bermejo,c and Francisco
Estévezd
O
O
S
aDipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara,
Ferrara, Italy; bRega Institute for Medical Research, Leuven, Belgium;
R2
cInstituto de Productos Naturales
y
Agrobiología-C.S.I.C-Instituto
R1=alkyl, phenylethyl or substituted benzyl.
R2=para - or meta -CH2=C(Br)CONH.
Universitario de Bio-Orgánica “Antonio González”, Universidad de La
d
Laguna, Tenerife, Spain; Department of Biochemistry, University of Las
Palmas de Gran Canaria and Instituto Canario de Investigación del Cáncer,
Las Palmas de Gran Canaria, Spain

*Highlights (for review)
ACCEPTED MANUSCRIPT
Highlights
-Bromoacryloylamido 5-benzylidene-thiazolidine-2,4-dione showed anticancer activity.
The presence of the -bromoacryloylamido moiety influenced the activity.
Compounds 5a, 5c and 5g induced apoptosis by activation of multiple caspases.

*Revised Manuscript
Click here to view linked References
ACCEPTED MANUSCRIPT
Anticancer Activity of Novel Hybrid Molecules Containing 5-Benzylidene
Thiazolidine-2,4-dione
Romeo Romagnoli*a, Pier Giovanni Baraldi* a, Maria Kimatrai Salvadora, M. Encarnacion
Camachoa, Jan Balzarinib, Jaime Bermejo,c and Francisco Estévezd
aDipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, 44100 Ferrara,
Italy;
bRega Institute for Medical Research, Laboratory of Virology and Chemotherapy, KU Leuven,
B-3000 Leuven, Belgium;
cInstituto de Productos Naturales y Agrobiología-C.S.I.C-Instituto Universitario de Bio-
Orgánica “Antonio González”, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain
dDepartment of Biochemistry, University of Las Palmas de Gran Canaria and Instituto Canario
de Investigación del Cáncer, Plaza Dr. Pasteur s/n, 35016 Las Palmas de Gran Canaria, Spain
* To whom correspondence should be addressed. Phone: 39-(0)532-455303. Fax: 39-(0)532-
455953. E-mail:rmr@unife.it (R.R.); Phone: 39-(0)532-455293. Fax: 39-(0)532-455953. E-
mail:baraldi@unife.it (P.G.B.).
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Abstract: Hybridization of two different bioactive molecules with different mechanism of
action is one of the methods that are being adopted to treat cancer. Molecules bearing a
thiazolidine-2,4-dione scaffold have been recognized as antineoplastic agents with a broad
spectrum of activity against many cancer cell lines. In this manuscript we have described the
synthesis and biological evaluation of two series of N-3-substituted-5-arylidene thiazolidine-
2,4-diones, bearing the -bromoacryloylamido moiety at the para- or meta-position on the
phenyl of the arylidene portion. We have observed that selected compounds 5a, 5c and 5g
suppress proliferation of human myeloid leukaemia HL-60 and U937 cells by triggering
morphological changes and internucleosomal DNA fragmentation, which are well-known
features of apoptosis. Finally, our results indicated that the investigated compounds induced
apoptotic cell death through a mechanism that involved activation of multiple caspases and
was also associated with the release of cytochrome c from the mitochondria.
Keywords. Apoptosis, structure-activity relationship, thiazolidine-2,4-dione, in vitro
antiproliferative activity, caspases.
1. Introduction
The combination of two pharmacophores into a single molecule is an effective and commonly
used direction in modern medicinal chemistry for the exploration of novel and highly active
compounds. The two pharmacophores are different in the case of heterobivalent ligands.
Therefore, heterobivalent ligands containing phamacophores that bind to different molecular
targets or to two distinct sites on the same molecular target, could be beneficial for the
treatment of cancer [1]. The thiazolidine-2,4-dione (2,4-TZD) ring is a well-known scaffold in
medicinal chemistry and has been used to develop new potential anticancer agents [2a-f], such
as the PI3K inhibitor GSK1059615 and its analogues [2g]. Research into the antitumor
efficacy of molecules which contain the 5-arylidene-thiazolidine-2,4-dione system has
received significant attention over the last years [3-5]. Among them, several congeners with
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general formula 1, based on the 5-benzylidene-thiazolidine-2,4-dione core with electron-
releasing or electron-withdrawing groups at the para- or meta-position of the benzylidene
moiety, were identified by screening to be Pim-1 protein kinase inhibitors and inhibited the
growth of prostate carcinoma PC3 cells with an IC50 value that ranged from 3 to 100 M
(Chart 1) [7]. Goulart et al. reported a series of 5-acridin-9-ylmethylene-3-benzyl-thiazolidine-
2,4-dione analogues with general structure 2, with a moderate antiproliferative activity (IC50:
4.1-58 M) against a wide panel of cancer cell lines [8]. The -unsaturated carbonyl system
of the 5-benzylidene-thiazolidine-2,4-dione could act as a Michael acceptor, suggesting that
the alkylation of the -position of the reactive enone system by biological nucleophiles may
be one mechanism by which antiproliferative activity was exerted in vitro.
The-bromoacrylic acid is an alkylating moiety of low chemical reactivity and devoid of
cytotoxic effects (IC50>120 M on the murine leukemia L1210 cells) [9]. The -
bromoacryloyl moiety was present in a series of potent anticancer distamycin-like minor
groove binders, including PNU-166196 (brostallicin, 3), which was evaluated as a first-line
single agent chemotherapy in patients with advanced or metastatic soft tissue sarcoma [10,
11]. It was hypothesized that the reactivity of the -bromoacryoyl moiety resulted from a first-
step Michael-type nucleophilic attack, followed by a further reaction of the former vinylic
bromo substituent alpha to the carbonyl, leading successively either to a second nucleophilic
substitution or to a beta-elimination [12].
Different anticancer biotargets and mechanism of the 5-arylidene-thiazolidine-2,4-dione
system and the -bromoacryloyl group encourage us to design and evaluate two different
series of synthetic conjugates with general formulae 4a-k and 5a-i, with the -
bromoacryloylamido moiety linked at the para- or meta-position on the phenyl of the
benzylidene fragment, respectively. If the hybridization approach renders synergistic effects,
the -bromoacryloylamido 5-arylidene-thiazolidine-2,4-dione derivatives 4a-k and 5a-i,
characterized by the presence of two different bioactive molecules, should be more active than
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corresponding 5-arylidene-thiazolidine-2,4-diones tested alone.
The substituents at the N-3 position of the 5-arylidene-thiazolidine-2,4-dione system were
alkyl (methyl and ethyl for 4a and 4b, respectively), benzyl (4c, 4e-i, 5a and 5c-i) or
phenylethyl (4d and 5b) groups. The structure-activity relationship (SAR) was also
investigated by the insertion of electron-withdrawing (fluoro, chloro and trifluoromethyl) and
electron-donating (methyl and t-butyl) groups on the benzene portion of the N-3 benzyl
substitution (compounds 4c, 4e-i, 5a and 5c-i).
2. Chemistry
Synthesis of derivatives 4a-k and 5a-i was carried out by the general methodology shown in
Scheme 1. 5-(Nitrobenzylidene)-thiazolidine-2,4-dione derivatives 6 [7] and 7 [13] were
prepared by the Knoevenagel condensation of the 2,4-TZD with 4- or 3-nitrobenzaldehyde,
respectively. The subsequent reaction of 6 and 7 with alkyl, benzyl or phenylethyl halide in
dimethylformamide in presence of sodium hydride, furnished the corresponding N-3
substituted thiazolidine-2,4-dione derivatives 8a-k and 9a-i, respectively. Aminobenzylidenes
10a-k and 11a-i were generated starting from the corresponding nitro analogues 8a-k and 9a-i
by reduction of the nitro group with iron in a refluxing solution mixture of 37% HCl in water
and ethanol (1:2.5 v/v). Finally, the hybrid compounds 4a-k and 5a-i were prepared by the
condensation of -bromoacrylic acid with 5-(aminobenzylidene)-thiazolidine-2,4-diones 10a-
k and 11a-i, respectively. This condensation was performed using an excess (2 equivalents) of
1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDCl) in dry DMF as
solvent at room temperature and with identical reaction times (18 h).
3. Biological results and discussion.
3.1. In vitro antiproliferative activities.
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Table 1 summarizes the antiproliferative effects of -bromoacryloylamido N-3-substituted-5-
arylidene-thiazolidine-2,4-diones 4a-k and 5a-i against the growth of murine leukemia
(L1210), murine mammary carcinoma (FM3A), human T-lymphoblastoid (CEM) and human
cervix carcinoma (HeLa) cells, using the alkylating agent melphalan as reference compound.
Ignoring the derivative 4i, all synthesized compounds possessed significant antiproliferative
activity, comparable to or even higher than that of melphalan against all four tumor cell lines.
In general, there was a trend that the antiproliferative activities of conjugates 4a-k and 5a-i
were somewhat more pronounced against L1210 and CEM as compared with FM3A and
HeLa cells.
Such hybrid compounds 4a-k and 5a-i were from one- to four-order of magnitude more active
than the corresponding amino 5-arylidene-thiazolidine-2,4-diones 10a-k and 11a-i,
respectively, demonstrating that the presence of the -bromoacryloyl moiety significantly
enhanced cell growth inhibitory activity (see Table 1s in Supplementary Data).
The -bromoacryloylamido N-3-methyl-5-arylidene-thiazolidine-2,4-dione derivative 4a, the
meta--bromoacryloylamido analogues 5c (p-F) and compound 5g invariably inhibited all
tumor cell lines in the higher nanomolar range.
Among the benzyl analogues 4c, 4e-k, 5a and 5c-i, the unsubstituted phenyl compounds 4c
and 5a were the most active derivatives, while the p-trifluoromethyl (4i) was the least active
compound. Increasing the alkyl chain by one carbon unit, from benzyl (4c and 5a) to
phenylethyl (4d and 5b) caused a significant (although relatively moderate) loss of activity.
In general, the presence of either electron-withdrawing (F, Cl or CF3) or electron releasing
(Me and t-But) substituents on the phenyl of the benzyl moiety reduced the cytostatic activity
as compared with the unsubstituted benzyl derivatives 4c and 5a, and there was no clear
difference between them. In fact, several compounds characterized by the presence of
substituents with opposite electronic effects showed the same potency. For example,
compound 5h containing the electron-releasing methyl group showed the same
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antiproliferative activity against L1210 and FM3A cells as derivative 5c containing the
electron-withdrawing fluoro group.
The results shown in Table 1 revealed that the position of the -bromoacryloylamido moiety,
as well as the electronic, hydrophobic and steric properties of substituents on the phenyl of the
benzyl group at the N-3 position of thiazolidine-2,4-dione system, influenced the
antiproliferative activity.
In the series of para--bromoacryloylamido N-3-substituted-5-arylidene-thiazolidine-2,4-
dione derivatives 4a-k, the N-3-methyl analogue 4a exhibited the greatest antiproliferative
activity, with IC50 values of 0.19-0.87 M. Increasing the length of the alkyl chain from
methyl to ethyl (4b) caused a 2-3-fold reduction in cytostatic activity. Para-substituted benzyl
derivatives showed variable potencies. Introduction of the weak electron-withdrawing fluorine
atom (4e), caused a 2-4-fold reduction in activity relative to that of 4a. Moving the fluorine
from para- to meta-position (compound 4f) produced a 1.5- and 3-fold reduction in activity
against CEM and HeLa cells, respectively, with only minor differences in IC50 values against
FM3A cells. With the exception of L1210 cells, increasing the size of the halogen from
fluorine (4e) to chlorine (4g) had little overall effect on antiproliferative activities against the
other cancer cell lines. Comparing para- and meta-chloro isomers 4g and 4h, respectively, the
latter was about 4-fold less active than 4g in the HeLa cells, while 4g and 4h were equipotent
against the other cancer cells. Replacement of the electron-withdrawing chlorine (4g) by the
electron-releasing methyl group (4j) caused decreased potency against HeLa cell proliferation.
Increasing the size of the substituent, from methyl to t-butyl (4k) resulted in a 1.5- to 4-fold
increase of activity, while the replacement of methyl by a strong electron-withdrawing
trifluoromethyl (4i) led to a significant loss of antiproliferative potency (2-4-fold).
In the series of meta--bromoacryloylamido analogues 5a-i, both for the para- and meta-
isomeric derivatives, increasing the size of the halogen from fluorine (5c and 5d) to chlorine
(5e and 5f) caused a 1.5- to 3-fold reduction of the antiproliferative activity. Moving the
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chlorine atom from the para- to the meta-position (compounds 5e and 5f, respectively),
maintained the activity. The same effect was observed for the para- and meta-fluoro
derivatives 5c and 5d, respectively, which were equipotent against L1210, FM3A and CEM
cells, while 5c was 3-fold more active than 5d against HeLa cells. Replacement of p-fluoro
(5c) by a weak electron-releasing methyl group (5h) kept the cytostatic activity against L1210
and FM3A cells unchanged, while a 1.5- and 2-fold reduction in potency against HeLa and
CEM cells, respectively, was observed. Potency was also hardly modified replacing the p-
methyl group (5h) by a p-trifluoromethyl moiety (5g), while the substitution of the methyl
with a bulkier t-butyl group (5i) caused a 2- to 4-fold reduction in the antiproliferative
activity.
3.2. Selected compounds 5a, 5c and 5g inhibit cell viability and induce apoptosis on human
leukemia cells.
We examined the effects of selected compounds 5a, 5c and 5g on the growth of the human
myeloid (HL-60 and U937) and lymphoid Molt-3 cells [14]. We found that these three
leukemia cell lines were highly sensitive to the treatment with these molecules, with IC50
values between 0.4 and 0.7 M (see Table 2s in Supplementary Data). Treatment with
molecules 5a, 5c and 5g resulted in a concentration-dependent inhibition of the cell viability
(Fig. 1A) and induced important morphological changes as well as an important reduction in
the number of cells (Fig. 1B).
In order to determine the possible mechanism of action mediating cell growth inhibition, we
have tested the effects of compounds 5a, 5c and 5g to induce apoptosis, using human myeloid
leukaemia HL-60 and U937 cell lines as the experimental system. As shown in Fig. 2A, these
molecules induced morphological changes typical of apoptotic cells [15]. Cells exposed to 1
M of compounds 5a, 5c and 5g for 6 h displayed chromatin condensation and the appearance
of apoptotic bodies by fluorescence microscopy after DNA staining with Hoechst 33258.
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Control non-treated HL-60 and U937 cells exhibited normal features, with the nuclei round
and homogeneous. Degradation of the DNA into a specific fragmentation pattern is a
characteristic feature of the apoptotic pathway [16]. When HL-60 and U937 cells were
incubated with these compounds at a concentration of 1 M for 6 h, the DNA showed the
typical fragmentation patterns formed by internucleosomal hydrolysis of chromatin, which
then led to the appearance of the DNA ladder on agarose gels, thus confirming the apoptosis-
inducing effects (Fig. 2B). However, in Molt-3 cells there was not a clear DNA laddering.
The hypodiploid DNA content (sub-G1 phase region) is characteristic of apoptosis and reflects
fragmented DNA. Measurement of the number of hypodiploid cells by flow cytometry (Fig.
2C and 2D) shows that the percentage of apoptotic cells increased 12-fold (26.7±6.0% vs.
2.31.0%), 12-fold (27.5±7.1% vs. 2.31.0%) and 23-fold (51.95.6% vs. 2.31.0%) in HL-
60 cells after treatment with compounds 5a, 5c and 5g, respectively (3 M, 6 h). In U937
cells, the percentage of apoptotic cells increased 6-fold (7.1±2.2% vs. 1.10.3%), 4-fold
(4.7±0.2% vs. 1.10.3%) and 16-fold (17.1±1.6% vs. 1.10.3%) after treatment with
compounds 5a, 5c and 5g (3 M, 6 h). In both cell lines, compound 5g was the most potent
apoptotic inducer.
The main players in apoptotic pathways are caspases, a family of intracellular cysteine
proteases expressed as inactive zymogens in living cells and sequentially activated by specific
proteolytic cleavage [17]. Caspase-8 and -9 are usually the first to be stimulated in the
apoptotic process, and then, they activate effector caspases, such as caspase-3. To determine
the role of caspases in the mechanism of cell death triggered by compounds 5a, 5c and 5g,
HL-60, U937 and Molt-3 cells were treated with these compounds and lysates were analyzed
by Western blot (Fig. 3). The results indicate that the selected derivatives 5a, 5c and 5g
stimulate the cleavage of pro-caspase-3, -6, -7, -8 and -9. Poly(ADP-ribose) polymerase
protein (PARP) [18], normally involved in DNA repair and a known substrate for caspase-3,
was also hydrolyzed to the 85 kDa fragment, which was in accordance with the pro-caspase-3
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activation [19]. Within the caspase family, caspase-3 has been identified as one of the key
effector caspases that cleaves multiple protein substrates in cells, and leading to irreversible
cell death. Moreover, the selected compounds 5a, 5c and 5g induced cytochrome c release
from mitochondria [20] and stimulated the cleavage of inactive pro-caspase-9 to the active 35-
37 kDa fragments, suggesting that apoptosis induction also occurs via the intrinsic pathway
[21].
As processing does not always correlate with activity, enzymatic activities of caspases were
also investigated in HL-60, U937 and Molt-3 cells treated during 6 h with 1 M of the
selected compounds 5a, 5c and 5g. Cell lysates were assayed for cleavage of the tetrapeptides
DEVD-pNA, IETD-pNA and LEHD-pNA as specific substrates for caspase-3/7, caspase-8
and caspase-9, respectively. As shown in Fig. 4, both initiator caspases (caspase-9 and
caspase-8) and the executioner caspase-3 were markedly activated in all leukemia cell lines.
The results demonstrate a >10-fold increase in caspase-3/7 activity in U937 cells, whereas
there was a >5-fold and a >2-fold increase in caspase-3/7 activity in HL-60 and Molt-3 cells,
respectively. When considered together, these results consistently suggest that these
compounds are able to induce apoptosis by activation of the extrinsic and the intrinsic
pathways of cell death.
4. Conclusions
With the aim to synergize the anti-cancer activity of the -bromoacryloyl unit and the 5-
arylidene thiazolidine-2,4-dione scaffold, we have prepared a series of hybrid compounds 4a-
k and 5a-i, having the features of both these moieties and containing a pair of Michael
acceptors in their structures. In general, all substituents on the phenyl of the benzyl group at
the N-3-position of the 2,4-TDZ ring caused a reduction in antiproliferative activity relative to
4c and 5a, sometimes mild to moderate (5a vs. 5c and 5g) and sometimes profound (4c vs. 4i).
HL-60 and U937 cells treated with compounds 5a, 5c and 5g showed typical morphological
features of apoptosis such as cell shrinkage, chromatin condensation and fragmented nuclei.
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Flow cytometry analysis showed that these molecules resulted in a large proportion of cells
entering in the apoptotic sub-G0-G1 peak. Apoptosis was accompanied by cleavage of the
nuclear protein PARP, a recognized caspase-3 substrate which is involved in DNA repair and
it is important for maintaining cell viability. These results lead us to conclude that derivatives
5a, 5c and 5g induced apoptosis by activation of the extrinsic and the intrinsic pathways of
cell death.
5. Experimental protocols
5.1. Chemistry
5.1.1. Materials and Methods
13
1H and C NMR spectra were recorded on a Bruker AC 200 and Varian 400 Mercury Plus
spectrometer, respectively. Chemical shifts () are given in ppm upfield from
tetramethylsilane as internal standard, and the spectra were recorded in appropriate deuterated
solvents, as indicated. Positive-ion electrospray ionization (ESI) mass spectra were recorded
on a double-focusing Finnigan MAT 95 instrument with BE geometry. Melting points (mp)
were determined on a Buchi-Tottoli apparatus and are uncorrected. All products reported
1
showed H and 13C NMR spectra in agreement with the assigned structures. The purity of
tested compounds was determined by combustion elemental analyses conducted by the
Microanalytical Laboratory of the Chemistry Department of the University of Ferrara with a
Yanagimoto MT-5 CHN recorder elemental analyzer. All tested compounds yielded data
consistent with a purity of at least 95% as compared with the theoretical values. All reactions
were carried out under an inert atmosphere of dry nitrogen, unless otherwise indicated.
Standard syringe techniques were used for transferring dry solvents. Reaction courses and
product mixtures were routinely monitored by TLC on silica gel (precoated F
Merck
254
plates), and compounds were visualized with aqueous KMnO . Flash chromatography was
4
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performed using 230-400 mesh silica gel and the indicated solvent system. Organic solutions
were dried over anhydrous Na2SO4.
5.1.2. General procedure A for the synthesis of compounds (8a-k and 9a-i).
Sodium hydride (60% oil dispersion, 40 mg, 1 mmol, 1 equiv.) was carefully added to a
solution
of
(Z)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione
(6)
or
(Z)-5-(3-
nitrobenzylidene)thiazolidine-2,4-dione 7 (250 mg, 1 mmol) in dry DMF (5 mL) at 0 °C.
After 30 min., the appropriate alkyl or benzyl halide (2 mmol, 2 equiv.) was added and the
reaction mixture was allowed to warm to room temperature and stirred for 2 h. The reaction
mixture was poured into water (5 mL) and extracted with dichloromethane (3 x 10 mL). The
combined organic extracts were washed with water (10 mL), brine, dried and concentrated in
vacuo. Petroleum ether was added to the residue and the resulting precipitate was collected by
filtration, to furnish the title compounds 8a-k and 9a-i.
5.1.2.1. (Z)-5-(4-Nitrobenzylidene)-3-methylthiazolidine-2,4-dione (8a). Following general
1
procedure A, compound 8a was isolated as a yellow solid. Yield 64%, mp 222-224 °C. H-
NMR (CDCl3) : 3.28 (s, 3H), 7.64 (d, J=8.8 Hz, 2H), 7.92 (s, 1H), 8.35 (d, J=8.8 Hz, 2H).
MS (ESI): [M+1]+=265.0.
5.1.2.2. (Z)-5-(4-Nitrobenzylidene)-3-ethylthiazolidine-2,4-dione (8b). Following general
1
procedure A, compound 8b was isolated as an orange solid. Yield 82%, mp 209-211 °C. H-
NMR (CDCl3) : 1.28 (t, J=8.4 Hz, 3H), 3.86 (q, J=8.4 Hz, 2H), 7.64 (d, J=8.6 Hz, 1H), 7.91
(s, 1H), 8.32 (d, J=8.8 Hz, 1H). MS (ESI): [M+1]+=279.1.
5.1.2.3. (Z)-5-(4-Nitrobenzylidene)-3-benzylthiazolidine-2,4-dione (8c). Following general
1
procedure A, compound 8c was isolated as a yellow solid. Yield 75%, mp 170-172 °C. H-
NMR (CDCl3) : 4.92 (s, 2H), 7.34 (m, 5H), 7.64 (d, J=8.6 Hz, 2H), 7.92 (s, 1H), 8.33 (d,
J=8.6 Hz, 2H). MS (ESI): [M+1]+=341.1.
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5.1.2.4. (Z)-5-(4-Nitrobenzylidene)-3-phenethylthiazolidine-2,4-dione (8d). Following general
1
procedure A, compound 8d was isolated as a brown solid. Yield 61%, mp 143-145 °C. H-
NMR (CDCl3) : 2.96 (t, J=8.0 Hz, 2H), 4.01 (t, J=8.0 Hz, 2H), 7.29 (m, 5H), 7.68 (d, J=8.6
Hz, 2H), 7.88 (s, 1H), 8.35 (d, J=8.6 Hz, 2H). MS (ESI): [M+1]+=355.1.
5.1.2.5. (Z)-3-(4-Fluorobenzyl)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione (8e). Following
general procedure A, compound 8e was isolated as a yellow solid. Yield 75%, mp 156-158
1
°C. H-NMR (CDCl3) : 4.88 (s, 2H), 7.02 (m, 2H), 7.44 (m, 2H), 7.64 (d, J=8.8 Hz, 2H),
7.91 (s, 1H), 8.31 (d, J=8.8 Hz, 2H). MS (ESI): [M+1]+=359.1.
5.1.2.6. (Z)-3-(3-Fluorobenzyl)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione (8f). Following
general procedure A, compound 8f was isolated as an orange solid. Yield 76%, mp 178-180
°C. 1H-NMR (CDCl3) : 4.90 (s, 2H), 7.32 (m, 5H), 7.63 (d, J=8.4 Hz, 2H), 7.93 (s, 1H), 8.32
(d, J=8.4 Hz, 2H). MS (ESI): [M+1]+=359.0.
5.1.2.7. (Z)-3-(4-Chlorobenzyl)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione (8g). Following
general procedure A, compound 8g was isolated as a yellow solid. Yield 97%, mp 180-182
°C. 1H-NMR (CDCl3) : 4.88 (s, 2H), 7.32 (m, 4H), 7.82 (d, J=8.8 Hz, 2H), 7.91 (s, 1H), 8.29
(d, J=8.8 Hz, 2H). MS (ESI): [M+1]+=374.9.
5.1.2.8. (Z)-3-(3-Chlorobenzyl)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione (8h). Following
general procedure A, compound 8h was isolated as a yellow solid. Yield 76%, mp 155-157
°C. 1H-NMR (CDCl3) : 4.88 (s, 2H), 7.31 (m, 3H), 7.43 (s, 1H), 7.77 (d, J=8.8 Hz, 2H), 7.93
(s, 1H), 8.32 (d, J=8.8 Hz, 2H). MS (ESI): [M+1]+=375.1.
5.1.2.9. (Z)-3-(4-(Trifluoromethyl)benzyl)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione (8i).
Following general procedure A, compound 8i was isolated as a brown solid. Yield 74%, mp
176-178 °C. 1H-NMR (CDCl3) : 4.91 (s, 2H), 7.57 (m, 4H), 7.67 (d, J=8.8 Hz, 2H), 7.93 (s,
1H), 8.34 (d, J=8.8 Hz, 2H). MS (ESI): [M+1]+=409.1.
12

ACCEPTED MANUSCRIPT
5.1.2.10. (Z)-3-(4-Methylbenzyl)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione (8j). Following
general procedure A, compound 8j was isolated as a yellow solid. Yield 88%, mp 195-197 °C.
1H-NMR (CDCl3) : 2.33 (s, 3H), 4.88 (s, 2H), 7.13 (d, J=8.4 Hz, 2H), 7.32 (d, J=8.4 Hz,
2H), 7.66 (d, J=8.6 Hz, 2H), 7.90 (s, 1H), 8.29 (d, J=8.6 Hz, 2H). MS (ESI): [M+1]+=355.1.
5.1.2.11.
(Z)-3-(4-Tert-butylbenzyl)-5-(4-nitrobenzylidene)thiazolidine-2,4-dione
(8k).
Following general procedure A, compound 8k was isolated as a yellow solid. Yield 78%, mp
181-183 °C. 1H-NMR (CDCl3) : 1.29 (s, 9H), 4.90 (s, 2H), 7.37 (m, 4H), 7.22 (d, J=8.8 Hz,
2H), 7.90 (s, 1H), 8.33 (d, J=8.8 Hz, 2H). MS (ESI): [M+1]+=397.1.
5.1.2.12. (Z)-5-(3-Nitrobenzylidene)-3-benzylthiazolidine-2,4-dione (9a). Following general
1
procedure A, compound 9a was isolated as a yellow solid. Yield 78%, mp 152-154 °C. H-
NMR (CDCl3) : 4.92 (s, 2H), 7.35 (m, 3H), 7.46 (m, 2H), 7.69 (t, J=8.0 Hz, 1H), 7.75 (d,
J=8.0 Hz, 1H), 7.92 (s, 1H), 8.26 (m, 1H), 8.35 (m, 1H). MS (ESI): [M+1]+=341.1.
5.1.2.13. (Z)-5-(3-Nitrobenzylidene)-3-phenethylthiazolidine-2,4-dione (9b). Following
general procedure A, compound 9b was isolated as a yellow solid. Yield 68%, mp 154-156
°C. 1H-NMR (CDCl3) : 2.98 (t, J=8.0 Hz, 2H), 4.00 (t, J=8.0 Hz, 2H), 7.23 (m, 5H), 7.67 (t,
J=8.0 Hz, 1H), 7.77 (d, J=8.0 Hz, 1H), 7.89 (s, 1H), 8.25 (d, J=8.0 Hz, 1H), 8.36 (s, 1H). MS
(ESI): [M+1]+=355.1.
5.1.2.14. (Z)-3-(4-Fluorobenzyl)-5-(3-nitrobenzylidene)thiazolidine-2,4-dione (9c). Following
general procedure A, compound 9c was isolated as a yellow solid. Yield 78%, mp 161-163
°C. 1H-NMR (CDCl3) : 4.89 (s, 2H), 7.02 (m, 2H), 7.43 (m, 2H), 7.66 (t, J=7.8 Hz, 1H), 7.77
(d, J=7.8 Hz, 1H), 7.92 (s, 1H), 8.31 (m , 1H), 8.35 (s, 1H). MS (ESI): [M+1]+=359.1.
5.1.2.15. (Z)-3-(3-Fluorobenzyl)-5-(3-nitrobenzylidene)thiazolidine-2,4-dione (9d). Following
general procedure A, compound 9d was isolated as a yellow solid. Yield 88%, mp 161-163
°C. 1H-NMR (CDCl3) : 4.90 (s, 2H), 6.98 (m, 1H), 7.17 (m, 1H), 7.29 (m, 2H), 7.68 (t, J=8.0
13

ACCEPTED MANUSCRIPT
Hz, 1H), 7.79 (d, J=8.0 Hz, 1H), 7.95 (s, 1H), 8.27 (m, 1H), 8.36 (s, 1H). MS (ESI):
[M+1]+=359.1.
5.1.2.16. (Z)-3-(4-Chlorobenzyl)-5-(3-nitrobenzylidene)thiazolidine-2,4-dione (9e). Following
general procedure A, compound 9e was isolated as a yellow solid. Yield 86%, mp 151-153
1
°C. H-NMR (CDCl3) : 4.88 (s, 2H), 7.32 (m, 3H), 7.70 (d, J=8.8 Hz, 2H), 7.81 (m, 1H),
7.92 (s, 1H), 8.24 (m, 1H), 8.36 (m , 1H). MS (ESI): [M+1]+=374.9.
5.1.2.17. (Z)-3-(3-Chlorobenzyl)-5-(3-nitrobenzylidene)thiazolidine-2,4-dione (9f). Following
general procedure A, compound 9f was isolated as a yellow solid. Yield 77%, mp 125-127 °C.
1H-NMR (CDCl3) : 4.88 (s, 2H), 7.26 (m, 3H), 7.43 (s, 1H), 7.68 (t, J=8.0 Hz, 1H), 7.79 (d,
J=8.0 Hz, 1H), 7.94 (s, 1H), 8.27 (d, J=8.0 Hz, 1H), 8.38 (s, 1H). MS (ESI): [M+1]+=345.1.
5.1.2.18. (Z)-3-(4-(Trifluoromethyl)benzyl)-5-(3-nitrobenzylidene)thiazolidine-2,4-dione (9g).
Following general procedure A, compound 9g was isolated as a yellow solid. Yield 79%, mp
1
158-160 °C. H-NMR (CDCl3) : 4.96 (s, 2H), 7.36 (m, 4H), 7.66 (t, J=8.2 Hz, 1H), 7.78 (d,
J=8.2 Hz, 1H), 7.81 (s, 1H), 8.28 (m, 1H), 8.35 (m, 1H). MS (ESI): [M+1]+=409.1.
5.1.2.19. (Z)-3-(4-Methylbenzyl)-5-(3-nitrobenzylidene)thiazolidine-2,4-dione (9h). Following
general procedure A, compound 9h was isolated as a yellow solid. Yield 78%, mp 162-164
°C. 1H-NMR (CDCl3) : 2.33 (s, 3H), 4.88 (s, 2H), 7.13 (d, J=8.0 Hz, 2H), 7.32 (d, J=8.0 Hz,
2H), 7.66 (t, J=8.2 Hz, 1H), 7.72 (d, J=8.2 Hz, 1H), 7.91 (s, 1H), 8.26 (d, J=8.2 Hz, 1H), 8.35
(s, 1H). MS (ESI): [M+1]+=355.1.
5.1.2.20.
(Z)-3-(4-Tert-butylbenzyl)-5-(3-nitrobenzylidene)thiazolidine-2,4-dione
(9i).
Following general procedure A, compound 9i was isolated as a yellow solid. Yield 82%, mp
179-181 °C. 1H-NMR (CDCl3) : 1.32 (s, 9H), 4.88 (s, 2H), 7.32 (m, 3H), 7.70 (d, J=8.2 Hz,
2H), 7.72 (d, J=8.4 Hz, 1H), 7.91 (s, 1H), 8.24 (m, 1H), 8.38 (m , 1H). MS (ESI):
[M+1]+=397.1.
14

ACCEPTED MANUSCRIPT
5.1.3. General procedure B for the synthesis of compounds (10a-k) and (11a-i).
To stirred suspension of nitro derivative 8a-k or 9a-i (1 mmol) in EtOH (5 mL), iron powder
(168 mg, 3 mmol) and 0.8 mL of aqueous concentrated HCl (37%) were added. The reaction
mixture was heated under reflux for 2 h, cooled to room temperature, basified with NaHCO3
to a pH 8 and filtered through Celite. The filter cake was washed with dichloromethane (15
mL) and the filtrate was concentrated to dryness in vacuo. The residue was dissolved in
dichloromethane (15 mL), washed with water (5 mL), brine (5 mL), dried over Na2SO4 and
the solvent removed under reduced pressure. The crude residue was purified by column
chromatography on silica gel or suspended in ethyl ether, stirred for 15 min and the solid
collected by filtration.
5.1.3.1.
(Z)-3-(4-Methylbenzyl)-5-(4-aminobenzylidene)thiazolidine-2,4-dione
(10a).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 4:6 v/v as eluent, to afford 10a as a
1
yellow solid. Yield 78%, mp 184-186 °C. H-NMR (CDCl3) : 2.32 (s, 3H), .4.09 (bs, 2H),
4.85 (s, 2H), 6.68 (d, J=8.6 Hz, 2H), 7.11 (d, J=8.4 Hz, 2H), 7.36 (m, 4H), 7.80 (s, 1H). MS
(ESI): [M+1]+=325.1.
5.1.3.2. (Z)-5-(4-Aminobenzylidene)-3-ethylthiazolidine-2,4-dione (10b). Following general
procedure B, after work-up the residue was purified by column chromatography, using ethyl
acetate: petroleum ether 3:7 v/v as eluent, to afford 10b as a yellow solid. Yield 76%, mp 166-
1
168 °C. H-NMR (CDCl3) : 1.25 (t, J=8.4 Hz, 3H), 3.78 (q, J=8.4 Hz, 2H), 4.13 (bs, 2H),
6.72 (d, J=8.6 Hz, 2H), 7.32 (d, J=8.6 Hz, 2H), 7.77 (s, 1H). MS (ESI): [M+1]+=249.1.
5.1.3.3. (Z)-5-(4-Aminobenzylidene)-3-benzylthiazolidine-2,4-dione (10c). Following general
procedure B, after work-up the residue was purified by column chromatography, using ethyl
acetate: petroleum ether 4:6 v/v as eluent, to afford 10c as a yellow solid. Yield 65%, mp 180-
15

ACCEPTED MANUSCRIPT
1
182 °C. H-NMR (CDCl3) : 4.04 (bs, 2H), 4.89 (s, 2H), 6.70 (d, J=8.8 Hz, 2H), 7.32 (m,
5H), 7.43 (m, 2H), 7.80 (s, 1H). MS (ESI): [M+1]+=311.1.
5.1.3.4. (Z)-5-(4-Aminobenzylidene)-3-phenethylthiazolidine-2,4-dione (10d). Following
general procedure B, after work-up the solid residue was stirred in ethyl ether. After filtration,
the title compound 10d was isolated as a yellow solid. Yield 67%, mp 196-198 °C. 1H-NMR
(CDCl3) : 2.97 (t, J=8.0 Hz, 2H), 3.97 (t, J=8.0 Hz, 2H), 4.18 (bs, 2H), 6.69 (d, J=8.8 Hz,
2H), 7.23 (m, 5H), 7.31 (d, J=8.8 Hz, 2H), 7.78 (s, 1H). MS (ESI): [M+1]+=325.0.
5.1.3.5.
(Z)-3-(4-Fluorobenzyl)-5-(4-aminobenzylidene)thiazolidine-2,4-dione
(10e).
Following general procedure B, after work-up the solid residue was stirred in ethyl ether.
After filtration, the title compound 10e was isolated as a yellow solid. Yield 82%, mp 194-196
°C. 1H-NMR (d6-DMSO) : 4.79 (s, 2H), 6.19 (bs, 2H), 6.63 (d, J=8.4 Hz, 2H), 7.86 (m, 2H),
7.37 (m, 4H), 7.76 (s, 1H). MS (ESI): [M+1]+=329.1.
5.1.3.6.
(Z)-3-(3-Fluorobenzyl)-5-(4-aminobenzylidene)thiazolidine-2,4-dione
(10f).
Following general procedure B, after work-up the solid residue was stirred in ethyl ether.
After filtration, the title compound 10f was isolated as a yellow solid. Yield 72%, mp 203-205
1
°C. H-NMR (CDCl3) : 3.88 (bs, 2H), 4.86 (s, 2H), 6.72 (m, 1H), 6.82 (d, J=8.8 Hz, 2H),
7.32 (m, 5H), 7.88 (s, 1H). MS (ESI): [M+1]+=329.1.
5.1.3.7.
(Z)-3-(4-Chlorobenzyl)-5-(4-aminobenzylidene)thiazolidine-2,4-dione
(10g).
Following general procedure B, after work-up the solid residue was stirred in ethyl ether.
After filtration, the title compound 10g was isolated as an orange solid. Yield 92%, mp 190-
1
192 °C. H-NMR (CDCl3) : 4.02 (bs, 2H), 4.90 (s, 2H), 6.72 (d, J=8.6 Hz, 2H), 7.32 (m,
6H), 7.80 (s, 1H). MS (ESI): [M+1]+=344.9.
5.1.3.8.
(Z)-3-(3-Chlorobenzyl)-5-(4-aminobenzylidene)thiazolidine-2,4-dione
(10h).
Following general procedure B, after work-up the solid residue was stirred in ethyl ether.
16

ACCEPTED MANUSCRIPT
After filtration, the title compound 10h was isolated as a yellow solid. Yield 84%, mp 184-
1
186 °C. H-NMR (CDCl3) : 4.12 (bs, 2H), 4.85 (s, 2H), 6.70 (d, J=8.4 Hz, 2H), 7.32 (m,
5H), 7.42 (s, 1H), 7.82 (s, 1H). MS (ESI): [M+1]+=345.1.
5.1.3.9. (Z)-3-(4-(Trifluoromethyl)benzyl)-5-(4-aminobenzylidene)thiazolidine-2,4-dione (10i).
Following general procedure B, after work-up the solid residue was stirred in ethyl ether.
After filtration, the title compound 10i was isolated as a yellow solid. Yield 82%, mp 232-234
1
°C. H-NMR (CDCl3) : 4.14 (bs, 2H), 4.93 (s, 2H), 6.69 (d, J=6.8 Hz, 2H), 7.30 (d, J=8.8
Hz, 2H),7.56 (m, 4H), 7.82 (s, 1H). MS (ESI): [M+1]+=379.1.
5.1.3.10. (Z)-5-(4-Aminobenzylidene)-3-methylthiazolidine-2,4-dione (10j). Following general
procedure B, after work-up the residue was purified by column chromatography, using ethyl
acetate: petroleum ether 3:7 v/v as eluent, to afford 10j as a yellow solid. Yield 72%, mp 180-
1
182 °C. H-NMR (CDCl3) : 3.23 (s, 3H), 4.11 (bs, 2H), 6.69 (d, J=8.8 Hz, 2H), 7.32 (d,
J=8.8 Hz, 2H), 7.81 (s, 1H). MS (ESI): [M+1]+=235.1.
5.1.3.11. (Z)-3-(4-Tert-butylbenzyl)-5-(4-aminobenzylidene)thiazolidine-2,4-dione (10k).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 4:6 v/v as eluent, to afford 10k as a
1
yellow solid. Yield 78%, mp 181-182 °C. H-NMR (CDCl3) : 1.30 (s, 9H), 4.12 (bs, 2H),
4.86 (s, 2H), 6.68 (d, J=8.6 Hz, 2H), 7.35 (m, 6H), 7.80 (s, 1H). MS (ESI): [M+1]+=367.2.
5.1.3.12. (Z)-5-(3-Aminobenzylidene)-3-benzylthiazolidine-2,4-dione (11a). Following general
procedure B, after work-up the residue was purified by column chromatography, using ethyl
acetate: petroleum ether 3:7 v/v as eluent, to afford 11a as a yellow solid. Yield 68%, mp 170-
1
172 °C. H-NMR (CDCl3) : 3.86 (bs, 2H), 4.89 (s, 2H), 6.78 (m, 2H), 6.91 (d, J=8.6 Hz,
1H), 7.24 (m, 2H), 7.33 (m, 2H), 7.41 (m, 2H), 7.90 (s, 1H). MS (ESI): [M+1]+=311.1.
17

ACCEPTED MANUSCRIPT
5.1.3.13. (Z)-5-(3-Aminobenzylidene)-3-phenethylthiazolidine-2,4-dione (11b). Following
general procedure B, after work-up the residue was purified by column chromatography, using
ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 11b as a yellow solid. Yield 78%,
mp 146-148 °C. 1H-NMR (CDCl3) : 2.97 (t, J=8.0 Hz, 2H), 3.82 (bs, 2H), 3.98 (t, J=8.0 Hz,
2H), 6.64 (d, J=8.0 Hz, 1H), 6.77 (s, 1H), 6.86 (d, J=8.0 Hz, 1H), 7.31 (m, 6H), 7.76 (s, 1H).
MS (ESI): [M+1]+=325.1.
5.1.3.14.
(Z)-3-(4-Fluorobenzyl)-5-(3-aminobenzylidene)thiazolidine-2,4-dione
(11c).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 11c as a
1
yellow solid. Yield 75%, mp 144-146 °C. H-NMR (CDCl3) : 3.86 (bs, 2H), 4.85 (s, 2H),
6.75 (m, 1H), 6.93 (d, J=7.8 Hz, 1H), 7.05 (m, 2H), 7.24 (m, 2H), 7.42 (m, 2H), 7.80 (s, 1H).
MS (ESI): [M+1]+=329.1.
5.1.3.15.
(Z)-3-(3-Fluorobenzyl)-5-(3-aminobenzylidene)thiazolidine-2,4-dione
(11d).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 4:6 v/v as eluent, to afford 11d as a
1
yellow solid. Yield 82%, mp 163-165 °C. H-NMR (CDCl3) : 3.81 (bs, 2H), 4.88 (s, 2H),
6.73 (d, J=7.6 Hz, 1H), 6.92 (d, J=7.6 Hz, 1H), 7.01 (t, J=7.8 Hz, 1H), 7.29 (m, 5H), 7.82 (s,
1H). MS (ESI): [M+1]+=328.1.
5.1.3.16.
(Z)-3-(4-Chlorobenzyl)-5-(3-aminobenzylidene)thiazolidine-2,4-dione
(11e).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 4:6 v/v as eluent, to afford 11e as a
1
yellow solid. Yield 75%, mp 161-163 °C. H-NMR (CDCl3) : 3.86 (bs, 2H), 4.85 (s, 2H),
6.76 (m, 1H), 6.88 (d, J=8.8 Hz, 2H), 7.36 (m, 5H), 7.90 (s, 1H). MS (ESI): [M+1]+=374.9.
18

ACCEPTED MANUSCRIPT
5.1.3.17.
(Z)-3-(3-Chlorobenzyl)-5-(3-aminobenzylidene)thiazolidine-2,4-dione
(11f).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate:petroleum ether 3:7 v/v as eluent, to afford 11f as a
1
yellow solid. Yield 79%, mp 176-178 °C. H-NMR (CDCl3) : 3.82 (bs, 2H), 4.86 (s, 2H),
6.72 (d, J=7.8 Hz, 1H),6.77 (s, 1H), 6.90 (d, J=7.8 Hz, 1H), 7.26 (m, 5H), 7.82 (s, 1H). MS
(ESI): [M+1]+=328.1.
5.1.3.18.
(Z)-3-(4-(Trifluoromethyl)benzyl)-5-(3-aminobenzylidene)thiazolidine-2,4-dione
(11g). Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 1:1 v/v as eluent, to afford 11g as a
1
yellow solid. Yield 72%, mp 186-188 °C. H-NMR (CDCl3) : 3.78 (bs, 2H), 4.88 (s, 2H),
6.74 (d, J=8.2 Hz, 2H), 6.88 (d, J=8.2 Hz, 1H), 7.20 (m, 2H), 7.38 (m, 3H), 7.82 (s, 1H). MS
(ESI): [M+1]+=379.1.
5.1.3.19.
(Z)-3-(4-Methylbenzyl)-5-(3-aminobenzylidene)thiazolidine-2,4-dione
(11h).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 11h as a
1
yellow solid. Yield 72%, mp 168-170 °C. H-NMR (CDCl3) : 2.32 (s, 3H), 3.80 (bs, 2H),
4.85 (s, 2H), 6.70 (d, J=7.8 Hz, 1H), 6.75 (s, 1H), 6.86 (d, J=7.8 Hz, 1H), 7.07 (t, J=7.8 Hz,
1H), 7.19 (d, J=8.2 Hz, 2H), 7.32 (d, J=8.2 Hz, 2H), 7.79 (s, 1H). MS (ESI): [M+1]+=325.1.
5.1.3.20.
(Z)-3-(4-Tert-butylbenzyl)-5-(3-aminobenzylidene)thiazolidine-2,4-dione
(11i).
Following general procedure B, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 11i as a
1
yellow solid. Yield 78%, mp 190-192 °C. H-NMR (CDCl3) : 1.29 (s, 9H), 3.80 (bs, 2H),
4.86 (s, 2H), 6.73 (d, J=8.2 Hz, 2H), 6.91 (d, J=8.2 Hz, 1H), 7.29 (m, 2H), 7.36 (m, 3H), 7.80
(s, 1H). MS (ESI): [M+1]+=367.2.
19

ACCEPTED MANUSCRIPT
5.1.4. General procedure C for the synthesis of hybrid derivatives (3a-i) and (4a-i).
To an ice-cooled solution of amine 10a-k or 11a-i(1 mmol) in dry DMF (5 mL) was added
EDCI (382 mg, 2 mmol) followed by -bromoacrylic acid (2 mmol, 306 mg). The reaction
mixture was stirred at room temperature for 18 h, and then concentrated under reduced
pressure. The residue was dissolved with a mixture of DCM (15 mL) and water (5 mL), and
the organic phase was washed with brine (5 mL), dried over Na2SO4 and evaporated to
dryness in vacuo. The resulting crude residue was purified by chromatography on silica gel.
5.1.4.1.
2-Bromo-N-(4-((Z)-(3-methyl-2,4-dioxothiazolidin-5-
ylidene)methyl)phenyl)acrylamide (4a). Following general procedure C, after work-up the
residue was purified by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v
1
as eluent, to afford 4a as a yellow solid. Yield 31%, mp 176-178 °C. H-NMR (CDCl3) :
3.25 (s, 3H), 6.18 (d, J=1.6 Hz, 1H), 7.16 (d, J=1.6 Hz, 1H), 7.52 (d, J=8.8 Hz, 2H), 7.73 (d,
13
J=8.8 Hz, 2H), 7.87 (s, 1H), 8.48 (s, 1H). C NMR (100 MHz, CDCl3) δ: 29.8, 120.3 (2C),
120.9, 122.1, 129.6, 130.0, 131.4 (2C), 132.9, 138.9, 158.8, 166.6, 167.9. MS (ESI):
[M+1]+=367.0, [M+3]+=369.0. Anal. calcd for C14H11BrN2O3S: C, 45.79; H, 3.02; N, 7.63;
found: C, 45.59; H, 2.89; N, 7.52.
5.1.4.2. 2-Bromo-N-(4-((Z)-(3-ethyl-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)acrylamide
(4b). Following general procedure C, after work-up the residue was purified by column
chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 4b as a
1
yellow solid. Yield 64%, mp 164-166 °C. H-NMR (CDCl3) : 1.26 (t, J=7.0 Hz, 3H), 3.84
(q, J=7.0 Hz, 2H), 6.18 (d, J=1.6 Hz, 1H), 7.16 (d, J=1.6 Hz, 1H), 7.54 (d, J=8.6 Hz, 2H),
7.74 (d, J=8.6 Hz, 2H), 7.86 (s, 1H), 8.42 (s, 1H). 13C NMR (100 MHz, CDCl3) δ: 13.2, 37.2,
110.3, 120.3 (2C), 121.1, 122.1, 129.5, 131.4 (2C), 132.7, 138.8, 158.9, 166.3, 167.7. MS
(ESI): [M+1]+=381.0, [M+3]+=383.0. Anal. calcd for C15H13BrN2O3S: C, 47.26; H, 3.44; N,
7.35; found: C, 47.02; H, 3.25; N, 7.11.
20

ACCEPTED MANUSCRIPT
5.1.4.3.
N-(4-((Z)-(3-Benzyl-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4c). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 4:6 v/v as eluent, to afford 4c
1
as a yellow solid. Yield 58%, mp 142-143 °C. H-NMR (CDCl3) : 4.90 (s, 2H), 6.17 (d,
J=1.6 Hz, 1H), 7.16 (d, J=1.6 Hz, 1H), 7.31 (m, 4H), 7.41 (m, 1H), 7.48 (d, J=8.8 Hz, 2H),
7.69 (d, J=8.8 Hz, 2H), 7.86 (s, 1H), 8.52 (s, 1H). 13C NMR (100 MHz, CDCl3) δ: 45.4, 120.3
(2C), 120.8, 122.1, 128.4, 128.8, 129.0, 129.5 (2C), 130.0 (2C), 131.4 (2C), 133.2, 135.2,
138.9, 158.9, 166.2, 168.3. MS (ESI): [M+1]+=443.1, [M+3]+=445.2. Anal. calcd for
C20H15BrN2O3S: C, 54.19; H, 3.41; N, 6.32; found: C, 54.02; H, 3.18; N, 6.15.
5.1.4.4.
N-(4-((Z)-(3-Phenylethyl-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4d). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford
4d as a yellow solid. Yield 63%, mp 102-104 °C. 1H-NMR (CDCl3) : 2.99 (t, J=7.8 Hz, 2H),
4.01 (t, J=7.8 Hz, 2H), 6.17 (d, J=1.6 Hz, 1H), 7.14 (d, J=1.6 Hz, 1H), 7.32 (m, 4H), 7.40 (m,
1H), 7.52 (d, J=8.8 Hz, 2H), 7.70 (d, J=8.8 Hz, 2H), 7.88 (s, 1H), 8.54 (s, 1H). 13C NMR (100
MHz, CDCl3) δ: 31.3, 46.4, 119.3, 121.4 (2C), 126.1, 129.2, 131.4 (2C), 132.0, 134.5 (2C),
135.0, 136.2 (2C), 138.2, 140.1, 141.9, 158.4, 166.7, 170.2. MS (ESI): [M+1]+=457.1,
[M+3]+=459.1. Anal. calcd for C21H17BrN2O3S: C, 55.15; H, 3.75; N, 6.13; found: C, 54.92;
H, 3.60; N, 5.95.
5.1.4.5.
N-(4-((Z)-(3-(4-Fluorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4e). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 4e
1
as a yellow solid. Yield 59%, mp 161-163 °C. H-NMR (d6-DMSO) : 4.82 (s, 2H), 6.36 (d,
J=2.0 Hz, 1H), 6.78 (d, J=2.0 Hz, 1H), 7.22 (m, 2H), 7.34 (m, 2H), 7.61 (d, J=8.4 Hz, 2H),
13
7.82 (d, J=8.4 Hz, 2H), 7.91 (s, 1H), 10.6 (s, 1H). C NMR (100 MHz, d6-DMSO) δ: 43.8,
21

ACCEPTED MANUSCRIPT
115.3, 115.5, 119.4, 120.4 (2C), 124.5, 126.4, 128.4, 129.8, 129.9, 131.1 (2C), 131.6, 132.9,
140.4, 160.3 (d, J=252.4 Hz), 161.3, 165.5, 167.3. MS (ESI): [M+1]+=461.1, [M+3]+=463.1.
Anal. calcd for C20H14BrFN2O3S: C, 52.07; H, 3.06; N, 6.07; found: C, 51.89; H, 2.88 N,
5.78.
5.1.4.6.
N-(4-((Z)-(3-(3-Fluorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4f). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 4f
1
as a yellow solid. Yield 61%, mp 193-195 °C. H-NMR (CDCl3) : 4.89 (s, 2H), 6.18 (d,
J=1.6 Hz, 1H), 7.02 (t, J=8.0 Hz, 1H), 7.16 (m, 2H), 7.21 (d, J=7.8 Hz, 1H), 7.29 (m, 1H),
7.51 (d, J=8.8 Hz, 2H), 7.73 (d, J=8.8 Hz, 2H), 7.88 (s, 1H), 8.48 (s, 1H). 13C NMR (100
MHz, CDCl3) δ: 44.6, 115.2, 115.4, 115.7, 115.9, 120.2 (2C), 124.4, 129.5, 129.8, 130.3,
131.4 (2C), 133.4, 137.3, 138.9, 158.3 (d, J=253.2 Hz), 160.2, 166.0, 167.6. MS (ESI):
[M+1]+=461.1, [M+3]+=463.1. Anal. calcd for C20H14BrFN2O3S: C, 52.07; H, 3.06; N, 6.07;
found: C, 51.79; H, 2.81; N, 5.89.
5.1.4.7.
N-(4-((Z)-(3-(4-Chlorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4g). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 4g
1
as a yellow solid. Yield 54%, mp 191-193 °C. H-NMR (d6-DMSO) : 4.81 (s, 2H), 6.36 (d,
J=2.0 Hz, 1H), 6.77 (d, J=2.0 Hz, 1H), 7.34 (d, J=8.6 Hz, 2H), 7.43 (d, J=8.8 Hz, 2H), 7.55
(d, J=8.8 Hz, 2H), 7.80 (d, J=8.8 Hz, 2H), 7.90 (s, 1H), 10.9 (s, 1H). 13C NMR (100 MHz, d6-
DMSO) δ: 43.9, 119.5, 120.5 (2C), 124.6, 126.6, 128.5, 128.6 (2C), 129.6 (2C), 131.2 (2C),
132.4, 133.0, 134.5, 140.6, 161.4, 165.6, 167.4. MS (ESI): [M+1]+=477.1, [M+3]+=479.1.
Anal. calcd for C20H14BrClN2O3S: C, 50.28; H, 2.95; N, 5.86; found: C, 50.04; H, 2.78; N,
5.69.
22

ACCEPTED MANUSCRIPT
5.1.4.8.
N-(4-((Z)-(3-(3-Chlorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4h). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 1:1 v/v as eluent, to afford
1
4h as a yellow solid. Yield 64%, mp 211-213 °C. H-NMR (d6-DMSO) : 4.84 (s, 2H), 6.37
(d, J=2.4 Hz, 1H), 6.78 (d, J=2.4 Hz, 1H), 6.83 (m, 2H), 7.27 (m, 1H), 7.37 (d, J=8.8 Hz, 2H),
7.65 (m, 1H), 7.86 (d, J=8.8 Hz, 2H), 7.92 (s, 1H), 10.6 (s, 1H). 13C NMR (100 MHz, d6-
DMSO) δ: 44.0, 119.7, 120.5 (2C), 126.2, 127.6, 127.8, 130.6, 131.2, 131.5, 133.0 (2C),
133.2, 134.7, 137.9, 138.2, 140.5, 161.4, 165.6, 167.4. MS (ESI): [M+1]+=461.1,
[M+3]+=463.1. Anal. calcd for C20H14BrClN2O3S: C, 50.28; H, 2.95; N, 5.86; found: C,
50.09; H, 2.70; N, 5.69.
5.1.4.9. N-(4-((Z)-(3-(4-Trifluoromethlbenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-
2-bromoacrylamide (4i). Following general procedure C, after work-up the residue was
purified by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to
1
afford 4i as a yellow solid. Yield 52%, mp 213-215 °C. H-NMR (CDCl3) : 4.93 (s, 2H),
6.37 (d, J=1.8 Hz, 1H), 6.79 (d, J=1.8 Hz, 1H), 7.53 (d, J=7.6 Hz, 2H), 7.64 (d, J=8.0 Hz,
2H), 7.74 (d, J=8.0 Hz, 2H), 7.84 (d, J=8.0 Hz, 2H), 7.93 (s, 1H), 8.53 (s, 1H). 13C NMR (100
MHz, CDCl3) δ: 44.1, 119.4, 120.4 (2C), 121.9, 123.2, 124.5 (2C), 125.5, 126.5 (q, J=272.4
Hz), 128.2, 128.3, 131.1 (2C), 133.0 (2C), 140.0, 140.5, 161.3, 165.5, 167.3. MS (ESI):
[M+1]+=511.1, [M+3]+=513.1. Anal. calcd for C21H14BrF3N2O3S: C, 49.33; H, 2.76; N, 5.48;
found: C, 49.11; H, 2.58; N, 5.29.
5.1.4.10.
N-(4-((Z)-(3-(4-Methylbenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4j). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 4j
as a yellow solid. Yield 59%, mp 196-198 °C. 1H-NMR (CDCl3) : 2.32 (s, 3H), 4.86 (s, 2H),
6.18 (d, J=0.8 Hz, 1H), 7.13 (d, J=8.0 Hz, 2H), 7.15 (d, J=0.8 Hz, 1H), 7.32 (d, J=8.0 Hz,
23

ACCEPTED MANUSCRIPT
2H), 7.50 (d, J=8.4 Hz, 2H), 7.72 (d, J=8.4 Hz, 2H), 7.85 (s, 1H), 8.48 (s, 1H). 13C NMR (100
MHz, CDCl3) δ: 21.2, 45.2, 115.8, 120.3 (2C), 120.9, 121.6, 129.0, 129.5 (2C), 130.2, 131.4
(2C), 132.3, 133.0 (2C), 138.2, 138.9, 158.8, 166.3, 170.2. MS (ESI): [M+1]+=457.1,
[M+3]+=459.1. Anal. calcd for C21H17BrN2O3S: C, 55.15; H, 3.75; N, 6.13; found: C, 54.97;
H, 3.58; N, 5.97.
5.1.4.11. N-(4-((Z)-(3-(4-Tert-butylbenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (4k). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford
1
4k as a yellow solid. Yield 72%, mp 208-209 °C. H-NMR (d6-DMSO) : 1.26 (s, 9H), 4.77
(s, 2H), 6.77 (d, J=1.6 Hz, 1H), 6.91 (d, J=1.6 Hz, 1H), 7.23 (d, J=8.2 Hz, 2H), 7.35 (d, J=8.8
13
Hz, 2H), 7.6 (d, J=8.8 Hz, 2H), 7.82 (d, J=8.8 Hz, 2H), 7.91 (s, 1H), 10.6 (s, 1H). C NMR
(100 MHz, d6-DMSO) δ: 30.9 (3C), 34.1, 54.8, 119.4, 120.4 (2C), 124.5, 125.3 (2C), 126.4,
127.4 (2C), 128.4, 131.1 (2C), 132.4, 132.9, 140.4, 150.2, 161.3, 165.5, 167.2. MS (ESI):
[M+1]+=499.1, [M+3]+=501.1. Anal. calcd for C24H23BrN2O3S: C, 57.72; H, 4.64 N, 5.61;
found: C, 57.58; H, 4.44 N, 5.49.
5.1.4.12.
N-(3-((Z)-(3-Benzyl-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5a). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 4:6 v/v as eluent, to afford 5a
as a yellow solid. Yield 61%, mp 80-82 °C. 1H-NMR (CDCl3) : 4.90 (s, 2H), 6.17 (d, J=1.8
Hz, 1H), 7.15 (d, J=1.8 Hz, 1H), 7.26 (m, 4H), 7.45 (m, 4H), 7.88 (s, 1H), 7.94 (s, 1H), 8.42
(s, 1H). 13C NMR (100 MHz, CDCl3) δ: 45.3, 121.1, 121.8, 122.1, 122.6, 126.8, 128.3, 128.8,
128.9, 129.3 (2C), 129.9, 133.2 (2C), 134.2, 135.1, 137.9, 158.9, 166.0, 167.6. MS (ESI):
[M+1]+=442.9, [M+3]+=444.8. Anal. calcd for C20H15BrN2O3S: C, 54.19; H, 3.41; N, 6.32;
found: C, 54.05; H, 3.12; N, 6.18.
24

ACCEPTED MANUSCRIPT
5.1.4.13.
N-(3-((Z)-(3-Phenylethyl-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5b). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford
1
5b as a white solid. Yield 64%, mp 91-93 °C. H-NMR (CDCl3) : 2.97 (t, J=7.6 Hz, 2H),
4.00 (t, J=7.6 Hz, 2H), 6.18 (d, J=1.6 Hz, 1H), 7.17 (d, J=1.6 Hz, 1H), 7.26 (m, 3H), 7.34 (m,
13
3H), 7.51 (m, 2H), 7.86 (s, 1H), 7.96 (s, 1H), 8.43 (s, 1H). C NMR (100 MHz, CDCl3) δ:
33.8, 43.2, 121.2, 121.8, 122.2, 122.7, 126.9, 128.7 (2C), 128.9 (2C), 129.4, 130.0, 133.1,
134.4, 137.4, 137.9, 138.2, 159.0, 166.2, 167.6. MS (ESI): [M+1]+=457.1, [M+3]+=459.1.
Anal. calcd for C21H17BrN2O3S: C, 55.15; H, 3.75; N, 6.13; found: C, 54.81; H, 3.61; N, 5.92.
5.1.4.14.
N-(3-((Z)-(3-(4-Fluorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5c). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 5c
as a white solid. Yield 67%, mp 160-162 °C. 1H-NMR (CDCl3) : 4.86 (s, 2H), 6.36 (d, J=2.0
Hz, 1H), 7.02 (m, 2H), 7.15 (d, J=2.0 Hz, 1H), 7.27 (d, J=8.0 Hz, 1H), 7.42 (m, 3H), 7.88 (s,
1H), 7.96 (s, 1H), 8.43 (s, 1H), 10.6 (s, 1H). 13C NMR (100 MHz, CDCl3) δ: 44.6, 115.6,
115.8, 121.2, 121.9, 122.2, 122.6, 124.3, 126.9, 129.4, 130.0, 130.9, 131.0, 133.5, 134.2,
138.0, 158.9 (d, J=261.4 Hz), 163.9, 166.0, 167.7. MS (ESI): [M+1]+=461.1, [M+3]+=463.1.
Anal. calcd for C20H14BrFN2O3S: C, 52.07; H, 3.06; N, 6.07; found: C, 51.86; H, 2.79; N,
5.80.
5.1.4.15.
N-(3-((Z)-(3-(3-Fluorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5d). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford
1
5d as a white solid. Yield 52%, mp 136-138 °C. H-NMR (CDCl3) : 4.89 (s, 2H), 6.18 (d,
J=1.6 Hz, 1H), 7.21 (d, J=1.8 Hz, 1H), 7.00 (t, J=8.0 Hz, 1H), 7.17 (m, 2H), 7.31 (m, 2H),
13
7.49 (m, 2H), 7.90 (s, 1H), 7.97 (s, 1H), 8.43 (s, 1H). C NMR (100 MHz, CDCl3) δ: 44.8,
25

ACCEPTED MANUSCRIPT
115.3, 115.8, 116.0, 121.2, 122.0, 122.2, 124.5, 126.9, 129.4, 130.0, 130.4, 130.5, 133.7,
134.2, 138.0, 159.0 (d, J=260.2 Hz), 161.2, 165.9, 167.6. MS (ESI): [M+1]+=461.1,
[M+3]+=463.1. Anal. calcd for C20H14BrFN2O3S: C, 52.07; H, 3.06; N, 6.07; found: C, 51.81;
H, 2.84; N, 5.82.
5.1.4.16.
N-(3-((Z)-(3-(4-Chlorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5e). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 5e
1
as a yellow solid. Yield 56%, mp 164-166°C. H-NMR (d6-DMSO) : 4.83 (s, 2H), 6.36 (d,
J=1.8 Hz, 1H), 6.78 (d, J=1.8 Hz, 1H), 7.36 (d, J=8.4 Hz, 2H), 7.41 (d, J=8.4 Hz, 2H), 7.49
(m, 2H), 7.72 (d, J=8.2 Hz, 1H), 7.91 (s, 1H), 8.04 (s, 1H), 10.5 (s, 1H). 13C NMR (100 MHz,
d6-DMSO) δ: 54.8, 120.1, 121.5, 122.3, 124.6, 126.3, 126.9, 128.5 (2C), 129.6 (2C), 129.7,
132.4, 133.0, 133.1, 134.3, 139.1, 161.3, 165.4, 167.3. MS (ESI): [M+1]+=477.1,
[M+3]+=479.1. Anal. calcd for C20H14BrClN2O3S: C, 50.28; H, 2.95; N, 5.86; found: C,
50.11; H, 2.76; N, 5.71.
5.1.4.17.
N-(3-((Z)-(3-(3-Chlorobenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5f). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 3:7 v/v as eluent, to afford 5f
as a white solid. Yield 49%, mp 160-162 °C. 1H-NMR (CDCl3) : 4.86 (s, 2H), 6.18 (d, J=1.6
Hz, 1H), 7.17 (d, J=1.8 Hz, 1H), 7.28 (m, 4H), 7.48 (m, 3H), 7.90 (s, 1H), 7.97 (s, 1H), 8.43
(s, 1H). 13C NMR (100 MHz, CDCl3) δ: 44.7, 121.2, 122.0, 122.2, 122.5, 126.9, 127.1, 128.7,
129.0, 129.4, 130.0, 130.1, 133.7, 134.2, 134.7, 136.9, 137.9, 159.0, 165.9, 173.3. MS (ESI):
[M+1]+=477.0, [M+3]+=479.1. Anal. calcd for C20H14BrClN2O3S: C, 50.28; H, 2.95; N, 5.86;
found: C, 50.07; H, 2.69; N, 5.68.
5.1.4.18.
N-(3-((Z)-(3-(4-Trifluoromethylbenzyl)-2,4-dioxothiazolidin-5-
ylidene)methyl)phenyl)-2-bromoacrylamide (5g). Following general procedure C, after work-
26

ACCEPTED MANUSCRIPT
up the residue was purified by column chromatography, using ethyl acetate: petroleum ether
3:7 v/v as eluent, to afford 5g as a white solid. Yield 58%, mp 143-145 °C. 1H-NMR (CDCl3)
: 4.95 (s, 2H), 6.18 (d, J=1.6 Hz, 1H), 7.17 (d, J=1.8 Hz, 1H), 7.31 (m, 1H), 7.49 (m, 2H),
13
7.55 (d, J=8.0 Hz, 2H), 7.61 (d, J=8.0 Hz, 2H), 7.90 (s, 1H), 7.99 (s, 1H), 8.43 (s, 1H). C
NMR (100 MHz, CDCl3) δ: 44.8, 121.2, 122.0, 122.2, 122.3 (2C), 124.1 (q, J=282.2 Hz),
125.9, 126.9, 129.3 (2C), 129.5, 130.0, 133.9, 134.1, 138.0, 138.9, 141.8, 159.0, 165.9, 167.6.
MS (ESI): [M+1]+=511.1, [M+3]+=513.1. Anal. calcd for C21H14BrF3N2O3S: C, 49.33; H,
2.76; N, 5.48; found: C, 49.09; H, 2.56; N, 5.31.
5.1.4.19.
N-(3-((Z)-(3-(4-Methylbenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5h). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 2:8 v/v as eluent, to afford
1
5h as a white solid. Yield 64%, mp 123-125 °C. H-NMR (CDCl3) : 2.33 (s, 3H), 4.86 (s,
2H), 6.26 (d, J=1.2 Hz, 1H), 7.13 (d, J=7.8 Hz, 1H), 7.17 (d, J=1.2 Hz, 1H), 7.34 (m, 2H),
13
7.45 (d, J=8.2 Hz, 2H), 7.52 (d, J=8.2 Hz, 2H), 7.87 (s, 1H), 7.93 (s, 1H), 8.42 (s, 1H). C
NMR (100 MHz, CDCl3) δ: 21.3, 45.2, 121.2, 121.9, 122.2, 122.8, 126.8, 129.0 (2C), 129.4,
129. 5 (2C), 130.0, 132.2, 133.2, 134.3, 137.9, 138.2, 158.9, 166.1, 167.7. MS (ESI):
[M+1]+=457.1, [M+3]+=459.1. Anal. calcd for C21H17BrN2O3S: C, 55.15; H, 3.75; N, 6.13;
found: C, 54.89; H, 3.52; N, 5.90.
5.1.4.20. N-(3-((Z)-(3-(4-Tert-butylbenzyl)-2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-2-
bromoacrylamide (5i). Following general procedure C, after work-up the residue was purified
by column chromatography, using ethyl acetate: petroleum ether 2:8 v/v as eluent, to afford 5i
1
as a white solid. Yield 56%, mp 138-140 °C. H-NMR (CDCl3) : 1.30 (s, 9H), 4.87 (s, 2H),
6.18 (d, J=1.8 Hz, 1H), 7.17 (d, J=1.8 Hz, 1H), 7.29 (d, J=8.6 Hz, 2H), 7.49 (m, 4H), 7.92 (d,
13
J=8.6 Hz, 2H), 8.42 (s, 1H), 10.8 (s, 1H). C NMR (100 MHz, CDCl3) δ: 31.3 (3C), 34.6,
45.1, 121.2, 121.9, 122.2, 122.8, 125.7 (2C), 126.8, 128.8 (2C), 129.4, 129.9, 132.2, 133.2,
27