N-Acylated and N,N′-diacylated imidazolidine-2-thione derivatives and N,N′-diacylated tetrahydropyrimidine-2(1H)-thione analogues: Synthesis and antiproliferative activity

Article abstract of DOI:10.1016/j.ejmech.2008.06.010

Fifty-one acylthioureas (ATUs) incorporating imidazolidine-2-thione or its upper cyclohomologue were prepared by parallel synthesis and evaluated against a high number of human cancer cell lines for antiproliferative activity. ATUs 1o (3,5-dichlorobenzoyl

Full text of DOI:10.1016/j.ejmech.2008.06.010

Available online at www.sciencedirect.com
European Journal of Medicinal Chemistry 44 (2009) 1106e1118
http://www.elsevier.com/locate/ejmech
Original article
N-Acylated and N,N0-diacylated imidazolidine-2-thione derivatives and
N,N0-diacylated tetrahydropyrimidine-2(1H )-thione analogues:
Synthesis and antiproliferative activity
Sara Cesarini a,*, Andrea Spallarossa a, Angelo Ranise a, Silvia Schenone a, Camillo Rosano b,
Paolo La Colla c,**, Giuseppina Sanna c, Bernardetta Busonera c, Roberta Loddo c
a Dipartimento di Scienze Farmaceutiche, Universita` di Genova, Viale Benedetto XV 3, I-16132 Genova, Italy
b Bioinformatics and Structural Proteomics, National Institute for Cancer Research (IST), Largo R. Benzi 10, I-16132 Genova, Italy
c Dipartimento di Scienze e Tecnologie Biomediche, Universita` di Cagliari, Cittadella Universitaria, S.S. 554, Km 4500, I-09042 Monserrato, Cagliari, Italy
Received 19 May 2008; received in revised form 17 June 2008; accepted 18 June 2008
Available online 24 June 2008
Abstract
Fifty-one acylthioureas (ATUs) incorporating imidazolidine-2-thione or its upper cyclohomologue were prepared by parallel synthesis and
evaluated against a high number of human cancer cell lines for antiproliferative activity. ATUs 1o (3,5-dichlorobenzoyl), 1s (2-furoyl), 3s
(2-furoyl) and 1t (2-thenoyl) displayed activity against leukemia, melanoma LOX IMVI, non-small cell lung NCI-H522, renal 786-0, CAKI-
1, SN12C, UO-31 and breast MCF7, MDA-MB-435, T-47D cancer cell lines in the 0.3e9.7 mM concentration range. Compound 14s exhibited
selectivity for melanoma SK-MEL-5 (GI50 < 5 nM); 1s for leukemia MOLT-4 (GI50: 300 nM); 1q, 3b and 3q for renal cancer UO-31 (GI50: 70e
200 nM); 8s, 9s for non-small cell lung cancer EKVX (GI50: 300, 10 nM) and 3j for HOP-92 (GI50: 700 nM) cell line.
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords: Acylthioureas; Antiproliferative activity; Parallel synthesis
1. Introduction
identified as potent and selective inhibitors of the autophos-
phorylation (tyrosine kinase activity) of platelet-derived
growth factor (PDGF) receptor, involved in cell-proliferation
processes [20].
In the past, the pharmacological potential of this chemical
class had attracted our attention and had led some of us to syn-
thesize a number of ATUs endowed with various biological
activities [11e13]. Recently, the N,N0-bis(4-chlorobenzoyl)
derivatives of imidazolidine-2-thione (1j, Fig. 1) revealed
Acylthioureas (ATUs) have been reported to display
a wide range of biological activities, such as antiviral [1], an-
tibacterial [2], tubercolostatic [3], fungicidal [4e6], herbi-
cidal [7,8], plant growth regulating [7,9], anticonvulsant
[10], antiaggregating [11e13], antiarrythmic [13], analgesic
[13], antihyperlipidemic [13], local anaesthetic [13], thyreo-
static [14], central nervous system (CNS) depressant [15]
and antiproliferative [13,16e19]. In particular, some benzoyl-
phenylthioureas have been recently described as potent anti-
tumor agents inhibiting tubulin polymerization [19] and some
quinoline and quinazoline-acylthiourea derivatives have been
a
significant cytotoxicity in MT-4 cell-based assays
(IC50 ¼ 9.9 mM). In order to investigate the influence of the
acyl portion on the antiproliferative activity, we prepared in
parallel a series of symmetric analogues of 1j (Table 1) in
which the 4-chlorobenzoyl moiety was replaced with an acetyl
(1a), a 1-naphthoyl (1r) or an heteroaroyl (2-furoyl 1s, 2-thie-
noyl 1t). Besides, the substitution on 1j phenyl ring was varied
by shifting the chlorine atom to the meta (1i) and ortho (1h)
position, or by replacing it with a more electron-withdrawing
* Corresponding author. Tel.: þ39 010 353 8361; fax: þ39 010 353 8358.
** Corresponding author. Tel.: þ39 070 675 4147; fax: þ39 070 675 4210.
E-mail addresses: sara.cesarini@unige.it (S. Cesarini), placolla@unica.it
(P. La Colla).
0223-5234/$ - see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.06.010

S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
1107
Table 2
Antiproliferative activity of ATUs 2d, 2f, 2h, 2j, 2meo, 2q, 2s and 2t against
MT-4 cellsa
Cl
O
N
N
1j, IC50 = 9.9 µM
R
N
O
N
O
S
O
S
R
b
IC50 (mM)
Compound
RCO
Cl
2d
2f
Benzoyl
4-Toluoyl
>100
>100
>100
38
Fig. 1. ATU lead compound.
2h
2j
2-Chlorobenzoyl
4-Chlorobenzoyl
(3-nitro 1k) or an electron-donating (2- and 4-methyl 1e, 1f; 4-
methoxy 1l) or a more sterically demanding (4-t-butyl 1g)
substituent. Also the phenyl ring unsubstitution (1d), dichlor-
osubstitution [patterns 2,4 (1m), 3,4 (1n) and 3,5 (1o)] and
polysubstitution (4-chloro-3-nitro 1p; 3,4,5-trimethoxy 1q)
were considered. With the aim to further expand the struc-
tureeactivity relationship (SAR) study, we synthesized the su-
perior cyclohomologues 2 (Table 2) and the asymmetric
analogues 3 (Table 3) in which one of the two acyl moiety
was replaced by a formyl group. Successively, we replaced
one of the benzoyl functions of ATU 1d with the electron-
poor a,b-unsaturated system N-methylene(malononitrile)
(4d: Y ¼ W ¼ cyano, Table 4). The significant antiprolifera-
tive activity of 4d prompted us to explore the influence of
the nature of the two electron-withdrawing groups Y and W
on the activity. Thus, we synthesized a series of analogues
of 4d (ATU 4se14s, Table 4) keeping constant the N-furoyl
portion, which had given the best results in series 1e3, and
varying Y and W (Y ¼ W or Y s W; Y, W: cyano, acetyl,
2m
2n
2o
2q
2s
2t
2,4-Dichlorobenzoyl
3,4-Dichlorobenzoyl
3,5-Dichlorobenzoyl
>100
72
30
3,4,5-Trimethoxybenzoyl
2-Furoyl
2-Thenoyl
>100
36
>100
a
Data mean values for three separate experiments. Variation among tripli-
cate samples was less than 10%.
b
Compound concentration required to reduce MT-4 cell growth by 50% in
comparison with untreated controls, as measured by the MTT method.
pivaloyl, benzoyl, methoxycarbonyl, ethoxycarbonyl, amino-
carbonyl and p-chlorophenylaminocarbonyl). Finally, we pre-
pared three urea-isosters (15se17s, Table 4).
2. Chemistry
The title compounds and three urea-isosters were prepared
(Scheme 1) by reacting (thio)ureas I, II, IVeXVIII (Fig. 2a)
with the suitable acylating reagent [acetic anhydride (a) and
acyl chlorides (bet)] (Fig. 2b). Thioureas I and II and the ac-
ylating reagents were commercially available, while thioureas
IVeXV and ureas XVIeXVIII were prepared according to
one-pot procedures (Scheme 1b) previously described by
Table 1
Antiproliferative activity of ATUs 1a, 1det against MT-4 cellsa
R
O
N
N
O
R
S
Table 3
Antiproliferative activity of ATUs 3aed, 3f, 3j, 3meo, 3q and 3s against
b
IC50 (mM)
Compound
RCO
MT-4 cellsa
1a
1d
1e
1f
Acetyl
>100
94
Benzoyl
2-Toluoyl
4-Toluoyl
R
O
N
N
>100
35
O
H
1g
1h
1i
4-t-Butylbenzoyl
2-Chlorobenzoyl
3-Chlorobenzoyl
4-Chlorobenzoyl
3-Nitrobenzoyl
>100
54
35
S
b
IC50 (mM)
Compound
RCO
1j
9.9
3a
3b
3c
3d
3f
Acetyl
Pivaloyl
>100
43
1k
1l
>100
>100
39
4-Methoxybenzoyl
trans-Cinnamoyl
Benzoyl
4-Toluoyl
>100
12
31
1m
1n
1o
1p
1q
1r
1s
1t
2,4-Dichlorobenzoyl
3,4-Dichlorobenzoyl
3,5-Dichlorobenzoyl
4.6
13
11
3j
4-Chlorobenzoyl
27
4-Chloro-3-nitrobenzoyl
3,4,5-Trimethoxybenzoyl
1-Naphthoyl
3m
3n
3o
3q
3s
a
2,4-Dichlorobenzoyl
3,4-Dichlorobenzoyl
3,5-Dichlorobenzoyl
3,4,5-Trimethoxybenzoyl
2-Furoyl
>100
41
15
7.0
13
2-Furoyl
2-Thenoyl
7.4
13
11
9.0
a
Data mean values for three separate experiments. Variation among tripli-
cate samples was less than 10%.
Data mean values for three separate experiments. Variation among tripli-
cate samples was less than 10%.
b
b
Compound concentration required to reduce MT-4 cell growth by 50% in
comparison with untreated controls, as measured by the MTT method.
Compound concentration required to reduce MT-4 cell growth by 50% in
comparison with untreated controls, as measured by the MTT method.

1108
S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
Table 4
Antiproliferative activity of acyl(thio)ureas 4d and 4se17s against MT-4 cellsa
some of us [21]. Briefly, thiourea I and urea III were con-
verted into the corresponding N-methyleniminium salts A1
and A2 by reaction with the DMFebenzoyl chloride complex.
Then, the one-pot hydrolysis of A1 led to the N-formyl thio-
urea IV, whereas the one-pot condensation of A1 and A2
with active methylene reagents (YeCH2eW) gave the corre-
sponding Knoevenagel-type derivatives VeXVIII as single
geometric isomers. The reactions of (thio)urea acylation
were performed in parallel (except for 3a and 4d) by using or-
dered arrays of reaction vessels (Carousel-6 and e12 Reaction
StationsÔ). A suitable parallel acylation method (Scheme 1a
and b) was set-up for each type of (thio)urea (I and II, IV,
VeXVIII) due to their different reactivities. Thus, all reac-
tions were performed in pyridine, in the presence of a small
excess of acylating reagent, but at different reaction tempera-
tures and times: 90 ꢀC for 30 min for the N,N0-diacylation of I
and II (ATUs 1 and 2, respectively); rt for 12 h for the N-ac-
ylation of IV (ATUs 3); 65 ꢀC for 4 h for the N-acylation of
VeXVIII with 2-furoyl chloride (ATUs 4se14s and acylureas
15se17s). In the last case, the addition of N,N,N0,N0-tetrame-
thylethylenediamine (TMEDA) increased the yields. The
acylation of IV with acetic anhydride (ATU 3a) required higher
temperature than the other acylations of IV, whereas the
benzoylation of V was carried out at rt for 2 h (ATU 4d).
Y
R
N
N
W
O
X
b
IC50 (mM)
Compound RCO
X
Y
W
4d
4s
Benzoyl
S
S
S
S
S
S
S
S
S
S
S
S
O
O
O
CN
CN
CN
CN
CN
CN
CN
CN
CN
11
4.4
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
2-Furoyl
5s
COOCH3
COC6H5
5.0
3.0
6s
7s
COC(CH3)3
CONH2
14.0
4.0
8s
9s
CONH(4-Cl-C6H4)
COCH3
COCH3
6.5
4.0
10s
11s
12s
13s
14s
15s
16s
17s
a
COCH3
COC6H5
5.0
7.0
COOCH3 COCH3
COC6H5
COC6H5
CN
COC6H5
COOCH2CH3
CN
7.0
4.0
>100
>100
43
COC6H5
COC6H5
COCH3
COOCH2CH3
Data mean values for three separate experiments. Variation among tripli-
cate samples was less than 10%.
b
Compound concentration required to reduce MT-4 cell growth by 50% in
comparison with untreated controls, as measured by the MTT method.
a
n
NH
n
N
(i)
O
R
HN
N
R
O
S
S
n = 1: I
n = 2: II
n = 1: 1a, 1d-t
n = 2: 2d, 2f, 2h, 2j,
2m-o, 2q, 2s, 2t
b
(iii)
(iv)
(ii)
N+
Cl-
R
O
O
HN
HN
NH
N
N
HN
N
N
(X = S)
O
H
H
X
X
S
S
I, X = S
A1, X = S
A2, X = O
3a-d, 3f, 3j,
3m-o, 3q, 3s
IV
III, X = O
(v)
Y
Y
(vi)
R
HN
N
N
W
N
W
O
X
X
V-XV, X = S
XVI-XVIII, X = O
4d, 4s-14s, X = S
15s-17s, X = O
Scheme 1. (a) (i) RCOCl [for 1a: acetic anhydride] (2.2 equiv.), pyridine, 90 ꢀC, 30 min. (b) (ii) dry DMF, 80 ꢀC, then PhCOCl (1 equiv.), rt, 15 min; (iii) H2O,
80 ꢀC, 5 min; (iv) RCOCl (1.1 equiv.), pyridine, rt, 12 h [for 3a: acetic anhydride (large excess), pyridine, 100 ꢀC, 3 h]; (v) YeCH2eW (1 equiv.), Et3N
(1.5 equiv.), DMF, 120 ꢀC, 30 min (for V, VII and XVI: without Et3N, 40 min); (vi) RCOCl (1.1 equiv.), TMEDA (1.1 equiv.), pyridine, 65 ꢀC, 4 h [for 4d: rt,
2 h]. For the structure list of (thio)ureas VeXVIII and acyl chlorides RCOCl (bet), see Fig. 2.

S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
1109
Table 5
Anticancer activity of 1meo, 1q, 1s, 1t, 2s, 2t, 3b, 3j, 3me3o, 3q, 3s, 4d, 4se
6s and 8se14sa
a
(Thio)ureas I, II, IV-XVIII
Compound Number (No) of human tumor cell linesb
O
HN
NH
HN
NH
HN
N
Investigated Giving positive GI50, TGI and LC50
GI50 (mM)c
TGI (mM)d
LC50 (mM)e
H
S
S
S
I
No Range
No Range
No Range
IV
II
1m
1n
1o
1q
1s
57
57
59
57
60
60
52
52
58
57
57
56
57
58
58
52
47
50
52
53
53
49
47
49
49
47
57 7.8e41.0 53 28.5e98.9 30 55.5e99.6
57 4.5e34.4 55 5.6e73.5 42 48.4e97.5
59 1.5e31.7 57 3.4e66.8 49 14.1e93.9
57 0.2e27.2 55 12.8e74.5 39 41.1e99.5
60 0.3e28.7 58 4.3e83.3 46 29.5e94.7
60 1.2e19.1 58 3.9e59.3 52 12.7e94.3
X=S
X=O
Y
W
CN
CN
V
XVI
1t
CN
COOCH3
COC6H5
COC(CH3)3
CONH2
VI
2s
12 2.3e82.1
26.2e84.7
40 0.07e92.0
1
1
7
93.3
66.2
e
e
e
e
e
Y
CN
VII
VIII
IX
2t
4
CN
HN
N
3b
3j
52.9e97.6 e
W
CN
57 0.7e49.5 55 11.0e80.0 42 40.2e84.8
26 20.4e85.6 46.8e98.7 e
3m
3n
3o
3q
3s
4
e
X
CN
CONH(4-Cl-C6H4)
COCH3
X
56 2.8e39.6 53 7.7e58.0 48 42.9e95.6
57 2.4e28.9 57 5.6e97.5 47 39.8e89.1
58 0.07e48.5 50 3.4e97.6 26 26.4e97.0
58 1.5e43.8 57 8.3e75.1 39 37.2e95.6
COCH3
COC6H5
COOCH3
COC6H5
COC6H5
XI
V-XVIII
COCH3
XII
XIII
XIV
XV
XVII
COCH3
COC6H5
4d
4s
46 3.5e89.2 22 11.4e98.3 e
47 2.0e79.7 27 6.6e89.4
50 2.1e54.9 42 5.0e79.6 22 9.9e98.5
e
COOC2H5
XVIII
4
67.4e92.2
5s
6s
52 2.2e68.2 28 5.4e93.3
51 0.3e43.6 34 1.0e98.2
7
4
49.6-92.3
65.0-91.6
e
b
8s
Acylating reagents: acetic anhydride (a) and acyl chlorides RCOCl (b-t)
9s
51 0.01e41.2 38 21.3e48.3 e
10s
11s
12s
13s
14s
a
49 1.5e38.4 44 3.4e71.5 25 11.5e96.3
47 1.1e28.0 35 3.6e46.7 13 22.7e47.5
49 1.6e41.7 43 4.0e98.4 25 10.0e91.8
48 1.2e41.8 37 4.1e44.2 19 28.3e48.7
RCO
pivaloyl
RCO
b
c
d
e
f
l
m
n
o
p
q
r
4-methoxybenzoyl
2,4-dichlorobenzoyl
3,4-dichlorobenzoyl
3,5-dichlorobenzoyl
4-chloro-3-nitrobenzoyl
3,4,5-trimethoxybenzoyl
1-naphthoyl
46 <46.0
Data obtained from NCI’s in vitro disease-oriented human tumor cell lines
screen.
23 <48.4
8 14.3e48.2
trans-cinnamoyl
benzoyl
2-toluoyl
b
The table shows the number of cell lines against which each compound
was screened, the number of lines against which it gave a positive GI50, or
4-toluoyl
g
h
i
4-t-butylbenzoyl
2-chlorobenzoyl
3-chlorobenzoyl
4-chlorobenzoyl
3-nitrobenzoyl
TGI or LC50 value (<100 mM) and the corresponding concentration range.
c
Compound concentration that produces 50% growth inhibition.
Compound concentration that produces total growth inhibition.
Compound concentration that produces 50% cytocidal effect.
d
s
2-furoyl
e
j
t
2-thenoyl
k
Fig. 2. Building blocks used (a) (thio)ureas I, II, IVeXVIII (b) acylating
reagents: acetic anhydride (a) and acyl chlorides RCOCl (bet).
screened (47e60), the number of lines against which it gave
a positive GI50, or TGI or LC50 value (inferior to 100 mM)
and the corresponding concentration range. The GI50 values
of the twenty-two most active molecules are reported in Tables
6 and 7.
The work-up procedures simply required quenching with wa-
ter or 2 N HCl solution, followed by filtrations or extractions.
The final products were purified by crystallization. The yields
ranged from 44 to 99% (see Section 5).
Data of Tables 1e3 display that ATUs 1 (Table 1) were
more active than the corresponding more conformationally
flexible six-membered ring homologues (ATUs 2, Table 2)
(1d vs 2d; 1f vs 2f; 1h vs 2h; 1j vs 2j; 1m vs 2m; 1n vs
2n; 1o vs 2o; 1q vs 2q; 1s vs 2s; 1t vs 2t) and in general
more effective than the corresponding N-acyl-N0-formyl con-
geners (series 3, Table 3) (1j vs 3j; 1m vs 3m; 1n vs 3n; 1o
vs 3o; 1q vs 3q; 1s vs 3s). The most active derivatives (1j,
1net, 3d, 3o, 3q and 3s) exhibited an IC50 value range of
4.6e15 mM. Data show evidence that the nature of the acyl
portion greatly influences the antiproliferative properties of
the compounds. Thus, in series 1e3 (with the exception of
compound 2t), the replacement of the benzoyl with the more
encumbering 1-naphthoyl or the heteroaromatic 2-furoyl or
3. Results and discussion
The fifty-four acyl(thio)ureas synthesized were tested for
antiproliferative activity against MT-4 lymphoblastoid T cells.
The results are expressed as IC50 values (Tables 1e4).
Twenty-six ATUs were also evaluated at National Cancer In-
stitute (NCI) (Bethesda, MD, USA) for their in vitro antican-
cer activity against subpanels of nine different types of cell
lines derived from human tumors (Tables 5e7). The results
are expressed as GI50, TGI and LC50 values. Table 5 shows
the number of cell lines against which each compound was

1110
S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
Table 6 (continued)
Table 6
GI50 values of 1meo, 1q, 1s, 1t, 3j, 3n, 3o, 3q and 3s against different cancer
cell lines in culturea
Panel
Compound GI50 (mM)b
Compound GI50 (mM)b
Cell line
1m 1n 1o 1q 1s 1t 3j 3n 3o 3q
3s
Panel
Cell line
1m 1n 1o 1q 1s 1t 3j 3n 3o 3q
3s
Prostate cancer
PC-3
DU-145
Leukemia
CCRFeCEM 19.5 4.5 3.3 12.2 1.2 2.1 12.8 7.1 5.4 18.3 3.6
22.7 16.7 16.9 15.0 3.9 6.1 15.8 14.7 16.6 22.2 5.0
30.6 14.7 10.5 13.6 2.7 3.3 15.7 15.7 16.8 19.6 2.5
HL-60 (TB)
K-562
16.6 12.7 3.3 16.0 4.0 2.2 23.3 24.6 10.3 23.4 2.8
31.4 16.5 4.8 24.9 1.0 3.5 12.9 13.8 14.8 30.8 2.6
20.5 15.7 3.4 23.5 0.3 3.2 19.2 22.8 15.0 29.4 4.6
12.9 1.8 1.5 3.7 2.0 1.2 3.4 2.8 2.4 7.3 1.8
Breast cancer
MCF7
NCI/ADR-RES 24.8 34.4 31.7 26.8 15.6 19.1 36.5 32.9 28.9 36.1 24.5
18.3 5.6 3.1 5.2 3.0 3.2 2.8 4.6 3.5 5.5 2.7
MOLT-4
RPMI-8226
SR
MDA-MB-
231/ATCC
HS 578T
19.1 18.8 16.2 16.7 12.2 9.4 16.4 14.6 15.6 21.5 15.9
n.t.c n.t.c 3.3 n.t.c 1.8 3.4 n.t.c n.t.c n.t.c n.t.c
2.1
Non-small cell lung cancer
41.0 29.1 21.4 24.7 6.8 16.6 49.6 39.6 21.0 27.6 11.0
A549/ATCC
EKVX
HOP-62
20.1 27.8 18.4 19.9 9.8 4.0 14.8 17.8 20.8 33.2 12.5
20.5 20.8 17.6 n.d.d 13.4 15.9 15.5 17.5 18.0 31.8 13.7
23.1 17.6 14.3 15.2 8.7 6.7 19.1 16.1 15.2 20.0 12.0
7.8 20.0 3.2 16.1 12.7 7.2 0.7 n.d.c 17.9 9.3 11.5
40.9 19.0 23.7 19.5 28.7 15.9 43.4 20.7 14.7 35.9 28.5
19.8 22.0 14.8 18.7 19.5 10.6 23.0 20.9 17.2 25.9 16.7
18.1 19.8 16.8 17.4 15.7 15.5 15.8 16.8 19.7 24.8 18.5
35.4 22.0 20.8 27.2 3.3 18.7 21.6 19.2 22.5 34.0 7.3
18.2 6.1 3.7 3.7 3.1 3.8 14.8 4.9 3.5 5.8 4.0
MDA-MB-435 16.4 15.4 9.0 13.1 4.0 2.8 14.8 16.6 14.2 15.5 6.4
MDA-N
BT-549
T-47D
a
20.0 18.3 13.0 15.0 5.0 2.6 16.6 15.6 18.8 17.9 9.1
21.1 23.6 22.4 17.4 4.6 10.0 25.4 18.0 17.3 25.0 2.3
19.5 17.5 6.5 13.1 4.9 4.6 12.8 15.3 10.7 20.7 4.0
HOP-92
NCI-H226
NCI-H23
NCI-H322M
NCI-H460
NCI-H522
Data obtained from NCI’s in vitro disease-oriented human tumor cell lines
screen. Only the values <100 mM are reported.
b
Compound concentration that produces 50% growth inhibition.
Not tested.
Not determined.
c
d
Colon cancer
COLO 205
HCC-2998
HCT-116
HCT-15
21.0 17.7 18.3 19.4 9.4 7.7 20.7 20.0 17.2 20.2 8.7
22.0 19.9 16.7 19.0 12.4 8.0 19.8 18.4 17.6 19.8 13.4
23.5 18.1 16.9 18.2 7.3 11.4 18.0 16.2 18.6 35.6 10.2
22.1 19.6 13.5 20.2 4.1 5.3 21.3 19.3 17.0 25.6 5.6
20.4 24.2 22.2 22.7 5.0 11.9 17.2 19.4 24.3 26.7 7.5
15.3 16.1 10.1 14.2 4.0 3.4 12.7 15.7 14.4 14.4 5.3
28.2 21.3 11.1 20.3 5.5 4.8 18.0 19.4 19.0 26.8 5.5
2-thenoyl led to an activity increase (compare 1ret with 1d,
2s with 2d and 3s with 3d), while the replacement with an al-
kylic acyl moiety (small acetyl or sterically demanding piva-
loyl) caused a drop or loss in activity (1a vs 1d; 3a and 3b
vs 3d). ATU 3d, vinylogue of 3c, turned out to be inactive. Re-
garding the substitution on the the benzoyl moiety phenyl ring,
a chlorine atom at position para led to a remarkable potency
increase in series 1 and 2 (compare 1j with 1d and 2j with
2d) and to the activity halving in series 3 (3j vs 3d). The chlo-
rine-atom shift to the meta and ortho position led to less active
( para 1j > meta 1i > ortho 1h) or inactive (ortho 2h) com-
pounds. The phenyl substitution with a more electron-with-
drawing group (nitro) or an electron-donating function (for
inductive effect: methyl, t-butyl; for mesomeric effect: me-
thoxy) led to a decrease (4-chloro 1j vs 4-methyl 1f; 4-chloro
3j vs 4-methyl 3f) or loss in activity (4-t-butyl 1g, 2-methyl 1e,
3-nitro 1k, 4-methoxy 1l, 4-methyl 2f). At position para, the
chlorine atom and the methyl group were tolerated better
than the more encoumbering t-butyl (compare 1j and 1f with
1g). Regarding the dichlorosubstitution, patterns 3,4 (1ne
3n) and 3,5 (1oe3o) were particularly effective and in some
cases more beneficial than the 4-chlorosubstitution (compare
1n with 1j, 2o with 2j and 3o with 3j). On the contrary, pattern
2,4 was unfavourable (1n, 1o vs 1m; 2n, 2o vs 2m; 3n, 3o vs
3m), thus confirming that the presence of a substituent at ortho
position is detrimental (compare also 1e with 1f; 1h with 1i
and 1j; 2h with 2j). The 3,4-dichlorobenzoyl ATU 1n turned
out to be the most active compound of the three series with
an IC50 of 4.6 mM. The good results obtained in series 1 by
the 4-chloro-3-nitro derivative (1p, IC50: 11 mM) and the
3,4,5-trimethoxy congener (1q, IC50: 7.0 mM) suggest that
the activity would not be affected by the electronic properties
of the substituents. The 3,4,5-trimethoxybenzoyl acyl moiety
was favourable also in series 3 (3q: IC50 ¼ 13 mM), but led
to the inactive six-membered ring ATU 2q. The acyl portions
HT29
KM12
SW-620
CNS cancer
SF-268
SF-295
SF-539
SNB-19
SNB-75
U251
24.5 16.8 14.1 11.5 2.7 8.2 19.2 22.2 16.2 21.4 3.9
22.9 18.5 19.5 19.0 16.9 16.7 26.9 18.0 17.7 29.3 21.4
27.2 15.1 12.8 14.5 3.0 1.8 26.6 20.6 20.2 21.3 2.5
24.9 21.4 19.0 18.5 25.4 14.4 15.6 17.5 20.5 28.5 24.6
22.3 18.9 14.1 7.1 10.4 1.4 20.0 17.5 13.3 10.9 8.6
17.8 16.4 12.9 16.3 9.0 7.9 14.4 12.5 17.0 16.4 14.1
Melanoma
LOX IMVI
MALME-3M 25.4 14.9 9.8 13.4 3.7 10.3 24.5 20.4 3.1 24.3 8.3
17.1 7.6 3.0 15.4 3.4 2.9 11.7 9.3 7.1 16.4 3.4
M14
16.3 19.6 11.9 16.8 7.7 3.6 14.6 16.8 15.6 20.6 10.7
18.4 18.4 16.1 16.3 14.2 12.6 16.3 15.3 16.9 19.9 16.5
18.4 30.6 12.2 17.2 5.5 3.8 19.1 18.2 18.4 29.5 26.2
n.t.c n.t.c 16.1 n.t.c 10.1 4.6 n.t.c n.t.c n.t.c n.t.c 12.7
28.2 17.3 15.5 21.7 4.6 7.5 17.5 17.7 17.4 19.9 11.7
17.3 18.1 15.6 14.9 3.2 12.3 15.9 16.0 15.8 15.8 5.0
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
Ovarian cancer
IGROV1
21.0 19.7 15.3 24.7 6.7 9.6 14.2 15.1 18.5 21.9 7.5
19.7 17.1 10.2 15.2 2.7 3.5 15.4 15.0 14.8 16.9 4.2
25.8 16.8 18.0 16.9 15.6 18.8 17.3 18.2 17.1 24.1 18.6
21.6 24.3 22.9 23.2 17.8 17.1 17.4 16.9 21.9 48.5 18.0
22.1 19.0 15.3 21.9 8.8 5.3 15.6 15.0 19.0 24.0 16.8
22.8 18.2 15.3 20.2 16.0 15.9 25.0 18.9 17.5 21.9 26.6
OVCAR-3
OVCAR-4
OVCAR-5
OVCAR-8
SK-OV-3
Renal cancer
786-0
A498
18.6 7.2 2.9 11.4 3.3 2.4 6.8 4.5 4.7 12.7 3.3
16.1 20.2 15.5 17.7 16.6 15.1 14.8 15.8 15.3 20.5 16.5
21.3 19.2 17.4 17.8 4.7 15.0 17.3 17.3 16.9 20.1 6.5
22.1 14.0 9.7 12.3 5.1 3.4 14.0 14.9 13.3 13.6 5.1
18.5 17.8 12.7 14.3 3.6 2.9 16.8 17.5 16.0 16.1 3.3
18.1 18.3 9.0 17.1 3.5 2.6 14.7 13.6 15.5 20.2 5.3
36.3 18.5 10.7 17.0 6.3 5.4 15.0 16.5 15.3 17.1 14.3
n.t.c n.t.c 2.3 0.2 3.7 2.3 n.t.c n.t.c n.t.c 0.07 4.5
ACHN
CAKI-1
RXF 393
SN12C
TK-10
UO-31

S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
Table 7 (continued)
1111
Table 7
GI50 values of 4d, 4se6s and 8se14s against different cancer cell lines in
Panel
Compound GI50 (mM)b
culturea
Cell line
4d 4s 5s 6s 8s 9s 10s 11s 12s 13s 14s
Panel
Compound GI50 (mM)b
Breast cancer
MCF7
Cell line
4d 4s 5s 6s 8s 9s 10s 11s 12s 13s 14s
16.7 3.5 n.t.c 4.5 1.7 21.0 n.t.c 1.3 n.t.c n.t.c n.t.c
n.t.c 24.0 n.t.c 25.4 28.1 23.2 n.t.c 22.2 9.2 n.t.c
36.1 2.9 4.2 13.7 13.1 18.4 2.6 9.5 9.0 7.4 10.8
Leukemia
CCRF-CEM
HL-60 (TB)
K-562
NCI/ADR-RES
MDA-MB-
231/ATCC
79.7
41.9
22.5
n.t.c n.t.c n.t.c 15.6
33.5 19.8 6.9 31.5 22.0 10.5 5.8 8.2 7.5 9.9 14.9
79.5 6.6 3.7 5.5 9.1 16.1 38.4 6.7 10.2 3.2 17.7
39.2 5.2 7.4 43.7 39.8 17.7 8.2 15.9 20.8 15.2 19.6
35.3 4.5 3.3 5.6 12.4 10.5 2.7 3.8 5.5 8.4 12.4
18.8 2.0 2.1 2.8 3.0 1.6 2.3 2.7 2.1 1.3 2.4
MDA-MB-435 38.8 5.3 6.8 11.0 14.6 15.2 12.6 10.7 4.5 7.2 14.4
MOLT-4
RPMI-8226
SR
BT-549
T-47D
a
22.8 6.9 4.2 7.8 22.5 8.6 14.0 5.6 3.5 10.0 9.0
89.2 21.2 4.6 7.2 9.3 3.7 4.3 6.0 4.1
Data obtained from NCI’s in vitro disease-oriented human tumor cell lines
screen. Only the values <100 mM are reported.
b
Non-small cell lung cancer
Compound concentration that produces 50% growth inhibition.
Not tested.
Not determined.
A549/ATCC
EKVX
HOP-62
37.1 13.5 14.6 22.0 34.5 25.8 11.2 10.8 19.3 11.3 11.6
c
3.5 11.9 10.2 17.8 0.3 0.01 11.2 7.9 2.6 8.1 9.5
n.t.c 22.3 22.0 25.6 25.7 22.0 11.7 20.6 15.9 17.3
56.8 22.4 14.0 26.9 25.5 21.5 11.7 11.1 20.8 27.0 23.0
26.1 5.8 13.2 15.2 21.4 12.3 16.4 n.t.c 12.2 7.0 7.7
33.4 15.5 14.0 23.4 17.6 28.6 4.7 27.9 12.4 2.2 14.2
20.0 3.3 2.5 9.5 4.0 19.9 1.5 7.0 2.3 2.4 4.9
15.9 n.t.c n.t.c 3.7 18.7 16.7 n.t.c n.t.c n.t.c n.t.c n.t.c
d
HOP-92
NCI-H23
NCI-H322M
NCI-H460
NCI-H522
that gave the best results in all the three series 1e3 were the 2-
furoyl (1s: 7.4 mM; 2s: 36 mM; 3s: 9.0 mM) and, to a lesser ex-
tent, the 3,5-dichlorobenzoyl (1o: 13 mM; 2o: 30 mM; 3o:
15 mM).
Colon cancer
COLO 205
HCT-116
HCT-15
n.d.d 16.5 31.7 23.2 24.9 25.6 23.4 16.5 12.6 20.0 19.2
34.0 n.t.c 4.0 9.1 21.2 15.2 4.1 6.4 7.4 7.9 8.9
36.4 5.2 3.0 5.7 3.8 21.3 2.2 4.7 2.2 2.6 6.3
42.0 27.7 12.2 30.5 24.1 21.4 17.1 16.9 15.8 16.9 19.2
32.3 4.1 3.3 6.5 7.5 16.3 2.8 8.4 3.0 2.3 10.1
33.7 5.6 5.2 5.9 22.1 17.3 14.6 6.1 3.9 8.7 7.9
The replacement of one of the two benzoyl moieties in
ATUs 1d and 1s with the electron-poor a,b-unsaturated sys-
tem N-methylene(malononitrile) (4d, 4s: Y ¼ W ¼ cyano, Ta-
ble 4) enhanced the antiproliferative activity 8.5 and 1.7
times, respectively (4d vs 1d, 4s vs 1s). The benzoyl/furoyl
interchange confirmed to be effective, with a 2.5-fold in-
crease in potency (4s vs 4d). Data of Table 4 display that
the replacement of one or both cyano groups with an acetyl
(10se12s), pivaloyl (7s), benzoyl (6s, 11s, 13s, 14s), methox-
ycarbonyl (5s, 12s), ethoxycarbonyl (14s), aminocarbonyl
(8s) or p-chlorophenylaminocarbonyl (9s) did not affect sig-
nificantly the activity (compare 5se14s with 4s), as the
IC50 values remained in the 3.0e7.0 mM range, except for
the encoumbering pivaloyl derivative 7s. Since the isosteric
oxygen/sulphur exchange produced an 11-fold drop (17s vs
14s) or loss (15s vs 4s and 16s vs 11s) in activity and thio-
ureas VeXV resulted to be inactive (data not shown), the im-
portance of the presence of the sulphur atom and of the acyl
moiety for the activity is highlighted.
The data reported in Table 5 show that, among the ATUs
tested at NCI, compounds of series 1 and 3 (with the exception
of 3b and 3m) showed a GI50 value inferior to 50 mM against
all the cell lines investigated (57e60), a TGI (measure of the
cytostatic activity) lower than 100 mM against most of the cell
lines (50e58) and an LC50 (measure of the cytocidal effect)
inferior to 100 mM against still a high number of cell lines
(26e52). In particular, ATUs 1o, 1s, 1t and 3o displayed a sig-
nificant TGI value against 57e58 out of 57e60 cell lines in-
vestigated and a significant LC50 against 46e52 cell lines.
Compounds 2s, 2t, 3b and 3m resulted as the least effective.
Most of the remaining ATUs (4d, 4se6s, 8se14s) showed
antiproliferative activity against all or nearly all the cell lines
investigated (46e52 out of 47e53), but only compounds 5s,
10s, 12s and 13s demonstrated to be cytostatic at micromolar
concentrations in a good number of cell lines (37e44) and cy-
tocidal in 19e25 cell lines.
HT29
KM12
SW-620
CNS cancer
SF-268
SF-295
SF-539
SNB-19
SNB-75
U251
21.3 31.4 4.8 31.2 11.7 17.8 2.6 10.7 5.8 n.d.d 7.2
46.2 31.3 26.0 43.6 32.1 20.2 21.7 19.3 18.6 11.1 16.4
n.t.c 2.5 n.t.c 2.2 n.t.c n.t.c n.t.c 1.1 n.t.c n.t.c n.t.c
38.7 54.9 39.7 36.4 27.6 30.1 16.3 41.7 29.2 35.6
40.6 15.5 68.2 9.0 10.9 21.0 27.4 46.0
38.2 6.6 6.8 17.0 11.5 17.3 4.8 13.4 5.5 2.7 11.5
Melanoma
LOX IMVI
3.3 2.4 17.9 2.5 16.7 2.1 8.9 1.6 1.2 6.5
MALME-3M 10.2 47.8 32.7 30.7 12.5 21.4 20.7 9.3 5.6 3.1 13.3
M14
37.3 n.t.c 6.4 14.9 16.5 14.2 4.0 6.3 10.7 7.0 8.9
18.4 4.3 2.9 3.7 24.4 16.7 3.3 n.t.c 15.2 12.1 n.t.c
45.5 12.5 13.0 28.0 15.8 18.7 3.9 28.0 9.1 17.8 22.2
23.3 2.9 14.8 8.3 16.5 11.2 16.6 8.1 5.3 10.9 <0.005
25.3 n.t.c 5.9 n.t.c 23.3 16.5 2.5 n.t.c 17.2 11.7 n.t.c
50.4 8.8 10.8 12.9 14.0 16.9 5.5 7.3 11.5 6.9 7.6
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
Ovarian cancer
IGROV1
28.2 6.6 6.2 19.4 24.0 25.3 3.6 10.9 10.4 5.6
OVCAR-3
OVCAR-4
OVCAR-8
SK-OV-3
36.4 11.2 4.9 18.2 19.0 15.5 11.4 17.2 2.7 7.3 20.2
59.3 20.1 23.3 29.8 18.5 25.2 10.6 20.1 17.4 16.1 31.0
77.0 14.6 15.5 25.4 43.6 20.6 8.2 8.8 27.8 16.2 11.7
66.7 33.1 28.2 37.4 42.6 41.2 20.0 17.5 31.3 41.8 20.0
Renal cancer
786-0
ACHN
38.9 n.t.c 6.3 16.1 18.0 17.4 5.3 11.2 11.2 8.2 12.9
18.8 9.4 4.8 16.6 11.0 15.3 2.9 6.9 4.1 5.8 8.5
28.7 4.8 3.4 12.5 11.8 13.2 5.2 9.3 2.8 7.0 15.9
22.7 2.6 3.1 4.1 19.2 13.1 1.8 n.t.c 4.4 5.8 n.t.c
24.6 3.1 3.7 8.6 12.0 11.8 2.6 7.7 5.9 6.1 8.1
23.3 4.6 3.6 10.5 12.1 19.4 4.2 10.6 3.5 6.9 12.4
20.4 10.5 5.2 10.2 23.5 12.0 2.9 8.8 13.5 8.7 10.0
CAKI-1
RXF 393
SN12C
TK-10
UO-31
Prostate cancer
PC-3
DU-145
60.0 17.2 6.8 31.7 35.6 18.9 4.8 17.1 18.1 23.6 19.4
24.4 5.5 3.5 5.0 29.8 15.9 n.t.c 11.0 n.t.c 12.4 8.0

1112
S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
Analysis of data of Tables 6 and 7 indicates that the ATUs
4. Conclusion
tested at NCI showed in general a wide spectrum of activity
in the micromolar concentration range (in most cases
GI50 < 25 mM) with a slight higher sensitivity towards leuke-
mia and renal cancer.
The ATUs synthesized exhibited interesting antiprolifera-
tive properties with a wide spectrum of activity at micromolar,
low micromolar and, in some cases, nanomolar concentrations.
The antitumor effect was higher in imidazolidine-2-thione
ATUs than in tetrahydropyrimidine-2(1H )-thione ATUs and
appeared strongly dependent on the nature of the acyl moiety.
The furoyl group led to the most cytotoxic compounds in all
the series. The understanding of the target and mechanism
of action of the title compounds will provide useful informa-
tion to modify the ATU structures in order to improve their an-
ticancer properties.
Among all the cell lines investigated, compounds 1 and 3
(Table 6) exhibited particular sensitivity for leukemia
CCRFeCEM, RPMI-8226 and SR, melanoma LOX IMVI
and non-small cell lung HOP-92 and NCI-H522, colon
KM12, renal 786-0 and UO-31, breast MCF7, MDA-MB-
435 and T-47D cancer cell lines. ATUs 1o, 1s, 1t and 3s
resulted effective against all leukemia cell lines in the
0.3e4.8 mM concentration range. The most prominent com-
pounds 1s, 1t and 3s turned out to be highly active also
against melanoma, colon, renal and prostate cancer cell lines
and many lines of the other subpanels. Some compounds ex-
hibited high sensitivity for a particular tumor cell line: 1s for
leukemia MOLT-4 (GI50: 300 nM), 1q, 3b and 3q for renal
cancer UO-31 [GI50 ¼ 200, 70 and 70 nM, respectively
(GI50 values of 3b not reported in Table 6)]; 3j for non-small
cell lung cancer HOP-92 (GI50: 700 nM).
The data reported in Table 7 show that compounds 4se14s
exhibited particular sensitivity for renal cancer, leukemia
RPMI-8226 and SR, melanoma LOX IMVI and SK-MEL-5,
and non-small cell lung EKVX and NCI-H460, colon
HCT-116, HCT-15, KM-12 and SW-620, breast MCF7,
MDA-MB-231/ATCC, BT-549 and T-47D cancer cell lines.
The 2-furoyl derivative 4s was more active than the corre-
sponding benzoyl analogue 4d against all cell lines (except
for EKVX). The nature of the electron-withdrawing groups
Y and W of the a,b-unsaturated system seems to slightly influ-
ence the antiproliferative activity: the ATUs which turned out
to be in general the most effective (4s, 5s and 10se13s) carried
the cyano, acetyl, benzoyl, methoxy- and ethoxycarbonyl
groups, whereas ATUs 8s and 9s, bearing an amide group,
turned out to be in general the least active, but selective for
non-small cell lung cancer EKVX (8s, GI50: 300 nM; 9s,
GI50: 10 nM). Among the most prominent compounds, 5s
was particularly effective against leukemia (GI50: 2.1e
7.4 mM), renal (GI50: 3.1e6.3 mM) and prostate (GI50: 3.5,
6.8 mM) cancer cell lines, most of the lines of colon and breast
subpanels and various lines of the other panels. ATU 14s
exhibited high selectivity for melanoma SK-MEL-5 cell line
(GI50 < 5 nM).
5. Experimental protocols
5.1. Chemistry
All chemicals were purchased by SigmaeAldrich Chemical
Co. and used without further purification, unless otherwise
stated. Solvents were of00reagent grade. DMF was dried on mo-
˚
lecular sieves (5 A 1/16 inch pellets). Organic solutions were
dried over anhydrous sodium sulphate. Thin layer chromatogra-
phy (TLC) system for routine monitoring the course of reac-
tions and confirming the purity of analytical samples
employed aluminium-backed silica gel plates (Merck DC-Alu-
folien Kieselgel 60 F254): CHCl3 or CHCl3/methanol were used
as developing solvents and detection of spots was made by UV
light and/or by iodine vapours. The reactions of acylation were
performed in parallel (except for 3a and 4d) by using Carousel-
6 and Carousel-12 Reaction StationsÔ (Radleys Discovery
Technologies, Italian distributor: StepBio, Bologna). The evap-
oration of solutions was performed in parallel with an Evapo-
selÔ apparatus (Radleys Discovery Technologies, Italian
distributor: StepBio, Bologna) operating at reduced pressure
of about 15e20 Torr. For the reactions not performed in parallel
fashion, the organic solutions were evaporated using a rotatory
evaporator operating at reduced pressure of about 10e20 Torr.
Yields were not optimized. Melting points were determined on
a Fisher-Johns apparatus and are uncorrected. IR spectra were
recorded on a Perkin Elmer 398 spectrometer as KBr discs or
1
solutions in CHCl3. H and 13C NMR spectra were recorded
in DMSO-d6, CDCl3 or CF3COOD on a Varian Gemini 200 in-
strument. Chemical shifts were reported in ppm units relative to
the internal reference tetramethylsilane, and the splitting pat-
terns were described as follows: s (singlet), d (doublet), dd
(doublet of doublets), t (triplet), quintet and m (multiplet).
The first order values reported for coupling constants J were
given in hertz. Elemental analyses were performed by an
EA1110 Elemental Analyser (Fison-Instruments, Milan) and
were within ꢁ0.4% of the theoretical values. The synthesis of
compounds IVeXVIII was accomplished according to the
published procedure [21].
At the moment, studies are in progress in the attempt to un-
derstand the target and the mechanism of action of the title
compounds. From a mechanistic point of view, it could be
hypothesized that ATUs act as acyl group vectors, able to
inactivate enzymes essential for cell proliferation through
the acylation of particular aminoacids (e.g. lysine amino group
or serine hydroxy function).
All acyl(thio)ureas and starting thioureas VeXV were
also assayed against HIV-1 infected MT-4 cells for their
ability to inhibit the virus-induced cytopathogenicity. How-
ever, none of them was able to prevent the HIV-induced cy-
topathogenicity at non cytotoxic concentrations (data not
shown).
5.1.1. Parallel procedure for the preparation of 1,3-diacyl-
imidazolidine-2-thiones 1a and 1det and 1,3-diacyl-

S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
1113
tetrahydropirimidin-2(1H )-thiones 2d, 2f, 2h, 2j, 2meo,
2q, 2s and 2t
53.84; H, 3.19; N, 7.39; S, 8.45. Found: C, 53.53; H, 3.18;
N, 7.29; S, 8.41.
The suitable acyl chloride (22 mmol) (for 1a: acetic anhy-
dride, 22 mmol, 2.08 mL) was added in one portion to each
numbered round-bottomed flask of a Carousel-6 Reaction Sta-
tionÔ, containing a stirred solution of thiourea I (10 mmol,
1.022 g) or II (10 mmol, 1.162 g) in pyridine (20 mL). The
resulting mixtures were stirred for 30 min at 90 ꢀC. After
cooling to rt, 150 mL of water were added into each round-
bottomed flask. The precipitates obtained were filtered off
in parallel by an in-house device, washed with water and
a mixture of diethyl ether and petroleum ether (1:1), and pu-
rified by crystallization from the suitable solvents or solvent
mixtures.
5.1.1.7. 1,3-Bis(3-chlorobenzoyl)imidazolidine-2-thione (1i).
Yield: 82%; m.p.: 198e200 ꢀC (DCM/diethyl ether); IR
1
(KBr): 1672 cmꢂ1; H NMR (CDCl3) d: 4.22 (s, 4H, 2CH2),
7.25e7.57 (m, 8H, Ar-H). Anal. Calcd for C17H12Cl2N2O2S:
C, 53.84; H, 3.19; N, 7.39; S, 8.45. Found: C, 54.08; H,
3.33; N, 7.52; S, 8.30.
5.1.1.8. 1,3-Bis(4-chlorobenzoyl)imidazolidine-2-thione (1j).
Yield: 93%; m.p.: 168e170 ꢀC (DCM/diethyl ether); IR
;
(KBr): 1671 cmꢂ1 1H NMR (DMSO-d6) d: 4.22 (s, 4H,
2CH2), 7.38e7.87 (m, 8H, Ar-H). Anal. Calcd for
C17H12Cl2N2O2S: C, 53.84; H, 3.19; N, 7.39; S, 8.45. Found:
C, 54.06; H, 3.24; N, 7.48; S, 8.39.
5.1.1.1. 1,3-Diacetylimidazolidine-2-thione (1a). Yield: 76%;
m.p.: 93e95 ꢀC (DCM/diethyl ether); IR (CHCl3):
1
1687 cmꢂ1; H NMR (CDCl3) d: 2.81 (s, 6H, 2CH3), 4.01 (s,
5.1.1.9. 1,3-Bis(3-nitrobenzoyl)imidazolidine-2-thione (1k).
Yield: 90%; m.p.: 258e260 ꢀC (DCM/diethyl ether); IR
;
(KBr): 1683, 1526, 1349 cmꢂ1 1H NMR (DMSO-d6) d:
4H, 2CH2). Anal. Calcd for C7H10N2O2S: C, 45.15; H, 5.41;
N, 15.04; S, 17.22. Found: C, 45.25; H, 5.42; N, 15.11; S, 16.89.
4.33 (s, 4H, 2CH2), 7.60e8.65 (m, 8H, Ar-H). Anal. Calcd
for C17H12N4O6S: C, 51.00; H, 3.02; N, 13.99; S, 8.01. Found:
C, 50.92; H, 3.08; N, 14.11; S, 8.01.
5.1.1.2. 1,3-Dibenzoylimidazolidine-2-thione (1d). Yield:
90%; m.p.: 243e244 ꢀC (acetone/CHCl3) (1it.: m.p. 228e
231 ꢀC, 232e233 ꢀC (methanol) [22]); IR (KBr):
1
1681 cmꢂ1; H NMR (CDCl3) d: 4.22 (s, 4H, 2CH2), 7.28e
5.1.1.10.
(1l). Yield: 97%; m.p.: 205e207 ꢀC (DCM/diethyl ether); IR
(KBr): 1670 cmꢂ1 1H NMR (DMSO-d6) d: 3.84 (s, 6H,
1,3-Bis(4-methoxybenzoyl)imidazolidine-2-thione
7.64 (m, 10H, Ar-H) (consistent with the data reported in
lit. [22]). 13C NMR (CDCl3) d: 44.79 (2CH2), 127.31
(4CH), 128.21 (4CH), 131.39 (2CH), 133.80 (2C), 171.40
(2CO), 178.00 (CS). Anal. Calcd for C17H14N2O2S: C,
65.79; H, 4.55; N, 9.03; S, 10.33. Found: C, 65.85; H, 4.52;
N, 9.09; S, 10.28.
;
2CH3), 4.17 (s, 4H, 2CH2), 6.87e7.16 and 7.65e7.88 (m,
8H, Ar-H). Anal. Calcd for C19H18N2O4S: C, 61.61; H, 4.90;
N, 7.56; S, 8.66. Found: C, 61.86; H, 4.93; N, 7.65; S, 8.78.
5.1.1.11. 1,3-Bis(2,4-dichlorobenzoyl)imidazolidine-2-thione
5.1.1.3. 1,3-Bis(2-methylbenzoyl)imidazolidine-2-thione (1e).
Yield: 97%; m.p.: 154e156 ꢀC (diethyl ether); IR (KBr):
(1m). Yield: 88%; m.p.: 151e153 ꢀC (DCM/diethyl ether);
IR (KBr): 1677 cmꢂ1 1H NMR (CDCl3) d: 4.30 (s, 4H,
;
1683 cmꢂ1
;
1H NMR (DMSO-d6) d: 2.15 (s, 6H, 2CH3),
2CH2), 7.20e7.42 (m, 6H, Ar-H). Anal. Calcd for
C17H10Cl4N2O2S: C, 45.56; H, 2.25; N, 6.25; S, 7.15. Found:
C, 45.36; H, 2.32; N, 6.23; S, 6.95.
4.12 (s, 4H, 2CH2), 7.04e7.27 (m, 8H, Ar-H). Anal. Calcd
for C19H18N2O2S: C, 67.43; H, 5.36; N, 8.28; S, 9.47. Found:
C, 67.45; H, 5.35; N, 8.32; S, 9.20.
5.1.1.12. 1,3-Bis(3,4-dichlorobenzoyl)imidazolidine-2-thione
5.1.1.4. 1,3-Bis(4-methylbenzoyl)imidazolidine-2-thione (1f).
Yield: 92%; m.p.: 174e176 ꢀC (DCM/diethyl ether); IR
(1n). Yield: 78%; m.p.: 178e180 ꢀC (DCM/diethyl ether);
IR (KBr): 1689 cmꢂ1 1H NMR (CDCl3) d: 4.21 (s, 4H,
;
(KBr): 1679 cmꢂ1
;
1H NMR (DMSO-d6) d: 2.34 (s, 6H,
2CH2), 7.36e7.42 (m, 4H, Ar-H), 7.63e7.67 (m, 2H, Ar-H).
13C NMR (CDCl3) d: 44.56 (2CH2N), 127.23 (2CH), 129.45
(2CH), 130.05 (2CH), 131.85 (2C), 133.18 (2C), 135.86
(2C), 168.77 (2CO), 177.66 (CS). Anal. Calcd for
C17H10Cl4N2O2S: C, 45.56; H, 2.25; N, 6.25; S, 7.15. Found:
C, 45.68; H, 2.29; N, 6.28; S, 6.96.
2CH3), 4.18 (s, 4H, 2CH2), 7.13e7.37 and 7.52e7.77 (m,
8H, Ar-H). Anal. Calcd for C19H18N2O2S: C, 67.43; H, 5.36;
N, 8.28; S, 9.47. Found: C, 67.22; H, 5.30; N, 8.19; S, 9.28.
5.1.1.5.
(1g). Yield: 80%; m.p.: 218e219 ꢀC (DCM/petroleum ether);
IR (KBr): 1678 cmꢂ1 1H NMR (CDCl3) d: 1.28 (s, 9H,
1,3-Bis(4-tert-butylbenzoyl)imidazolidine-2-thione
;
5.1.1.13. 1,3-Bis(3,5-dichlorobenzoyl)imidazolidine-2-thione
3CH3), 4.20 (s, 4H, 2CH2), 7.31e7.79 (m, 8H, Ar-H). Anal.
Calcd for C25H30N2O2S: C, 71.05; H, 7.15; N, 6.63; S, 7.59.
Found: C, 71.31; H, 7.18; N, 6.72; S, 7.71.
(1o). Yield: 81%; m.p.: 231e233 ꢀC (DCM/diethyl ether);
IR (KBr): 1675 cmꢂ1 1H NMR (CDCl3) d: 4.25 (s, 4H,
;
2CH2), 7.25e7.57 (m, 6H, Ar-H). Anal. Calcd for
C17H10Cl4N2O2S: C, 45.56; H, 2.25; N, 6.25; S, 7.15. Found:
C, 45.20; H, 2.32; N, 6.26; S, 7.05.
5.1.1.6. 1,3-Bis(2-chlorobenzoyl)imidazolidine-2-thione (1h).
Yield: 87%; m.p.: 156e158 ꢀC (diethyl ether); IR (KBr):
1
1663 cmꢂ1; H NMR (CDCl3) d: 4.29 (s, 4H, 2CH2), 7.18e
7.47 (m, 8H, Ar-H). Anal. Calcd for C17H12Cl2N2O2S: C,
5.1.1.14. 1,3-Bis(4-chloro-3-nitrobenzoyl)imidazolidine-2-thi-
one (1p). Yield: 84%; m.p.: 198e200 ꢀC (DCM/diethyl

1114
S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
ether); IR (KBr): 1674 cmꢂ1; 1H NMR (DMSO-d6) d: 4.25 (s,
4H, 2CH2), 7.45e7.74 (m, 6H, Ar-H). Anal. Calcd for
C17H10Cl2N4O6S: C, 43.51; H, 2.15; N, 11.94; S, 6.83. Found:
C, 43.41; H, 2.27; N, 11.92; S, 6.95.
(quintet, J ¼ 6.8 Hz, 2H, CCH2C), 4.14 (t, J ¼ 6.8 Hz, 4H,
2CH2N), 7.16e7.45 (m, 8H, Ar-H). Anal. Calcd for
C18H14Cl2N2O2S: C, 54.97; H, 3.59; N, 7.12; S, 8.15. Found:
C, 55.16; H, 3.60; N, 7.26; S, 7.90.
5.1.1.15. 1,3-Bis(3,4,5-trimethoxybenzoyl)imidazolidine-2-thi-
5.1.1.22.
1,3-Bis(4-chlorobenzoyl)tetrahydropyrimidine-
one (1q). Yield: 80%; m.p.: 189e191 ꢀC (DCM/diethyl ether);
2(1H )-thione (2j). Yield: 98%; m.p.: 207e209 ꢀC (DCM/di-
IR (KBr): 1671 cmꢂ1
;
1H NMR (CDCl3) d: 3.88 (s, 12H,
ethyl ether); IR (KBr): 1705 cmꢂ1; H NMR (DMSO-d6) d:
1
4CH3), 3.92 (s, 6H, 2CH3), 4.23 (s, 4H, 2CH2), 6.97 (s, 4H,
Ar-H). Anal. Calcd for C23H26N2O8S: C, 56.32; H, 5.34; N,
5.71; S, 6.54. Found: C, 56.60; H, 5.33; N, 5.74; S, 6.39.
2.37 (quintet, J ¼ 6.6 Hz, 2H, CCH2C), 3.90 (t, J ¼ 6.6 Hz,
4H, 2CH2N), 7.44e7.54 and 7.67e7.77 (m, 8H, Ar-H).
Anal. Calcd for C18H14Cl2N2O2S: C, 54.97; H, 3.59; N,
7.12; S, 8.15. Found: C, 55.17; H, 3.81; N, 6.80; S, 7.98.
5.1.1.16.
1,3-Di-1-naphthoylimidazolidine-2-thione
(1r).
Yield: 68%; m.p.: 189e191 ꢀC (DCM/diethyl ether); IR
5.1.1.23. 1,3-Bis(2,4-dichlorobenzoyl)tetrahydropyrimidine-
2(1H )-thione (2m). Yield: 65%; m.p.: 201e203 ꢀC (DCM/di-
(KBr): 1678 cmꢂ1; H NMR (CDCl3) d: 4.39 (s, 4H, 2CH2),
1
1
7.25e8.02 (m, 14H, Ar-H). Anal. Calcd for C25H18N2O2S:
C, 73.15; H, 4.42; N, 6.82; S, 7.81. Found: C, 73.09; H,
4.39; N, 6.82; S, 7.52.
ethyl ether); IR (KBr): 1683 cmꢂ1; H NMR (CDCl3) d: 2.46
(quintet, J ¼ 7.0 Hz, 2H, CCH2C), 4.12 (t, J ¼ 7.0 Hz, 4H,
2CH2N), 7.22e7.43 (m, 6H, Ar-H). Anal. Calcd for
C18H12Cl4N2O2S: C, 46.78; H, 2.62; N, 6.06; S, 6.94. Found:
C, 47.08; H, 2.72; N, 6.25; S, 6.96.
5.1.1.17. 1,3-Di-2-furoylimidazolidine-2-thione (1s). Yield:
86%; m.p.: 145e147 ꢀC (DCM/diethyl ether); IR (KBr):
1675 cmꢂ1
;
1H NMR (DMSO-d6) d: 4.23 (s, 4H, 2CH2),
5.1.1.24. 1,3-Bis(3,4-dichlorobenzoyl)tetrahydropyrimidine-
6.78 (dd, J ¼ 3.7 Hz, J ¼ 1.8 Hz, 2H, 2 fur H-4), 7.45 (d,
J ¼ 3.7 Hz, 2H, 2 fur H-3), 8.06 (d, J ¼ 1.8 Hz, 2H, 2 fur H-
5). Anal. Calcd for C13H10N2O4S: C, 53.79; H, 3.47; N,
9.65; S, 11.05. Found: C, 53.70; H, 3.49; N, 9.57; S, 11.06.
2(1H )-thione (2n). Yield: 73%; m.p.: 158e160 ꢀC (DCM/
diethyl ether); IR (KBr): 1674 cmꢂ1 1H NMR (CDCl3)
;
d: 2.46 (quintet, J ¼ 6.6 Hz, 2H, CCH2C), 4.00 (t,
J ¼ 6.6 Hz, 4H, 2CH2N), 7.40e7.63 and 7.70e7.85 (m,
2H, Ar-H). Anal. Calcd for C18H12Cl4N2O2S: C, 46.78;
H, 2.62; N, 6.06; S, 6.94. Found: C, 46.73; H, 2.76; N,
6.24; S, 7.10.
5.1.1.18.
1,3-Bis(thien-2-ylcarbonyl)imidazolidine-2-thione
(1t). Yield: 84%; m.p.: 131e132 ꢀC (DCM/diethyl ether);
IR (KBr): 1675 cmꢂ1; H NMR (DMSO-d6) d: 4.24 (s, 4H,
1
2CH2), 7.16e7.38 (m, 2H, 2 thioph H-4), 7.793e8.18 (m,
4H, 2 thioph H-3 and 2 thioph H-5). Anal. Calcd for
C13H10N2O2S3: C, 48.43; H, 3.13; N, 8.69; S, 29.83. Found:
C, 48.46; H, 3.05; N, 8.60; S, 29.91.
5.1.1.25. 1,3-Bis(3,5-dichlorobenzoyl)tetrahydropyrimidine-
2(1H )-thione (2o). Yield: 98%; m.p.: 201e203 ꢀC (DCM/di-
1
ethyl ether); IR (KBr): 1719 cmꢂ1; H NMR (DMSO-d6) d:
2.37 (quintet, J ¼ 6.4 Hz, 2H, CCH2C), 3.94 (t, J ¼ 6.4 Hz,
4H, 2CH2N), 7.68e7.77 (m, 6H, Ar-H). Anal. Calcd for
C18H12Cl4N2O2S: C, 46.78; H, 2.62; N, 6.06; S, 6.94. Found:
C, 46.71; H, 3.00; N, 6.28; S, 6.75.
5.1.1.19.
1,3-Dibenzoyltetrahydropyrimidine-2(1H )-thione
(2d). Yield: 91%; m.p.: 228e230 ꢀC (DCM/diethyl ether);
1
IR (KBr): 1701 cmꢂ1; H NMR (DMSO-d6) d: 2.44 (quintet,
J ¼ 6.6 Hz, 2H, CCH2C), 3.98 (t, J ¼ 6.6 Hz, 4H, 2CH2N),
7.40e8.05 (m, 10H, Ar-H). Anal. Calcd for C18H16N2O2S:
C, 66.65; H, 4.97; N, 8.64; S, 9.88. Found: C, 66.54; H,
4.96; N, 8.63; S, 9.92.
5.1.1.26.
dine-2(1H )-thione (2q). Yield: 80%; m.p.: 132e134 ꢀC
(DCM/diethyl ether); IR (KBr): 1683 cmꢂ1 1H NMR
(CDCl3) d: 2.48 (quintet, J ¼ 6.6 Hz, 2H, CCH2C), 3.77e
4.15 (m, 22H, 2CH2N þ 6CH3), 7.06 (s, 4H, Ar-H). 13C
NMR (CDCl3) d: 22.66 (CH2), 43.87 (2CH2N), 55.63
(4CH3), 60.26 (2CH3), 106.43 (4CH), 128.17 (2C), 141.81
(2C), 152.29 (4C), 172.33 (2CO), 182.20 (CS). Anal. Calcd
for C24H28N2O8S: C, 57.13; H, 5.59; N, 5.55; S, 6.35. Found:
C, 56.74; H, 5.50; N, 5.41; S, 6.29.
1,3-Bis(3,4,5-trimethoxybenzoyl)tetrahydropyrimi-
;
5.1.1.20.
1,3-Bis(4-methylbenzoyl)tetrahydropyrimidine-
2(1H )-thione (2f). Yield: 98%; m.p.: 209e211 ꢀC (DCM/di-
ethyl ether); IR (KBr): 1699 cmꢂ1; H NMR (DMSO-d6) d:
1
2.32 (s, 6H, 2CH3), 2.35 (quintet, J ¼ 6.6 Hz, 2H, CCH2C),
3.85 (t, J ¼ 6.6 Hz, 4H, 2CH2N), 7.18e7.28 and 7.59e7.69
(m, 8H, Ar-H); 13C NMR (DMSO-d6) d: 21.07 (2CH3),
22.09 (CH2), 44.88 (2CH2N), 129.09 (4CH), 129.23 (4CH),
131.40 (2C), 142.97 (2C), 173.22 (2CO), 181.10 (CS). Anal.
Calcd for C20H20N2O2S: C, 68.16; H, 5.72; N, 7.95; S, 9.10.
Found: C, 68.24; H, 5.78; N, 8.29; S, 9.20.
5.1.1.27. 1,3-Di-2-furoyltetrahydropyrimidine-2(1H )-thione
(2s). Yield: 97%; m.p.: 199e201 ꢀC (acetone/chloroform);
1
IR (KBr): 1694 cmꢂ1; H NMR (DMSO-d6) d: 2.26 (quintet,
J ¼ 6.4 Hz, 2H, CCH2C), 3.76 (t, J ¼ 6.4 Hz, 4H, 2CH2N),
6.68 (dd, J ¼ 3.6 Hz, J ¼ 1.6 Hz, 2H, 2 fur H-4), 7.36 (d,
J ¼ 3.6 Hz, 2H, 2 fur H-3), 7.96 (d, J ¼ 1.6 Hz, 2H, 2 fur H-
5); 13C NMR (DMSO-d6) d: 22.17 (CH2), 44.84 (2CH2N),
112.96 (2CH), 119.78 (2CH), 147.35 (2C), 147.67 (2CH),
5.1.1.21.
1,3-Bis(2-chlorobenzoyl)tetrahydropyrimidine-
2(1H )-thione (2h). Yield: 68%; m.p.: 196e198 ꢀC (DCM/di-
ethyl ether); IR (KBr): 1700 cmꢂ1; H NMR (CDCl3) d: 2.47
1

S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
1115
162.04 (2CO), 181.10 (CS). Anal. Calcd for C14H12N2O4S: C,
55.26; H, 3.97; N, 9.21; S, 10.54. Found: C, 55.32; H, 4.04; N,
9.48; S, 10.54.
6.59; N, 13.07; S, 14.96. Found: C, 50.26; H, 6.60; N,
13.08; S, 14.88.
5.1.3.2.
3-[(2E )-3-Phenylprop-2-enoyl]-2-thioxoimidazoli-
5.1.1.28.
1,3-Bis(thien-2-ylcarbonyl)tetrahydropyrimidine-
dine-1-carbaldehyde (3c). Yield: 96%; m.p.: 158e160 ꢀC
1
2(1H )-thione (2t). Yield: 97%; m.p.: 223e225 ꢀC (acetone/
(DCM/petroleum ether); IR (CHCl3): 1680 cmꢂ1; H NMR
DCM); IR (KBr): 1681 cmꢂ1; H NMR (DMSO-d6) d: 2.30
(CDCl3) d: 3.89e4.24 (m, 4H, 2CH2), 7.28e7.73 (m, 5H,
Ar-H), 7.78 (d, J ¼ 15.6 Hz, 1H, CH]CPh), 8.36 (d,
J ¼ 15.6 Hz, 1H, C ¼ CHPh), 9.62 (s, 1H, HCO). Anal. Calcd
for C13H12N2O2S: C, 59.98; H, 4.65; N, 10.76; S, 12.32.
Found: C, 60.16; H, 4.84; N, 10.61; S, 12.00.
1
(quintet, J ¼ 6.4 Hz, 2H, CCH2C), 3.79 (t, J ¼ 6.4 Hz, 4H,
2CH2N), 7.18 (dd, J ¼ 5.0 Hz, J ¼ 3.8 Hz, 2H, 2 thioph H-
4), 7.83 (dd, J ¼ 3.8 Hz, J ¼ 1.2 Hz, 2H, 2 thioph H-3),
8.01 (dd, J ¼ 5.0 Hz, J ¼ 1.2 Hz, 2H, 2 thioph H-5); 13C
NMR (DMSO-d6) d: 21.55 (CH2), 45.38 (2CH2N), 128.50
(2CH), 134.96 (2CH), 135.70 (2CH), 138.00 (2C), 166.80
(2CO), 179.01 (CS). Anal. Calcd for C14H12N2O2S3: C,
49.98; H, 3.60; N, 8.33; S, 28.59. Found: C, 50.33; H,
3.62; N, 8.60; S, 28.58.
5.1.3.3. 3-Benzoyl-2-thioxoimidazolidine-1-carbaldehyde (3d).
Yield: 65%; m.p.: 125e127 ꢀC (DCM/petroleum ether); IR
1
(KBr): 1679 cmꢂ1; H NMR (CDCl3) d: 3.92e4.28 (m, 4H,
2CH2), 7.44e7.93 (m, 5H, Ar-H), 9.51 (s, 1H, HCO). Anal.
Calcd for C11H10N2O2S: C, 56.40; H, 4.30; N, 11.96; S,
13.69. Found: C, 56.13; H, 4.30; N, 12.01; S, 13.52.
5.1.2. Preparation of 3-acetyl-2-thioxoimidazolidine-1-
carbaldehyde (3a)
5.1.3.4. 3-(4-Methylbenzoyl)-2-thioxoimidazolidine-1-carbal-
Acetic anhydride (large excess, 8 mL) was added in one
portion to a stirred suspension of 2-thioxo-imidazolidine-1-
carbaldehyde (10 mmol, 1.301 g) in pyridine (8 mL). The re-
sulting mixture was stirred for 3 h at 100 ꢀC. After cooling
to rt, 30 mL of water were added. The precipitate obtained
was filtered off, dried and crystallized from DCM/petroleum
ether. Yield: 55%; m.p.: 99e101 ꢀC; IR (CHCl3):
dehyde (3f). Yield: 88%; m.p.: 178e180 ꢀC (DCM/petroleum
1
ether); IR (CHCl3): 1685 cmꢂ1; H NMR (DMSO-d6) d: 2.43
(s, 3H, CH3), 3.99e4.28 (m, 4H, 2CH2), 7.15e7.39 and 7.54e
7.81 (m, 4H, Ar-H), 9.50 (s, 1H, HCO). Anal. Calcd for
C12H12N2O2S: C, 58.05; H, 4.87; N, 11.28; S, 12.91. Found:
C, 58.13; H, 4.93; N, 11.01; S, 12.73.
1
1708 cmꢂ1; H NMR (CDCl3) d: 2.85 (s, 3H, CH3), 3.84e
5.1.3.5. 3-(4-Chlorophenyl)-2-thioxoimidazolidine-1-carbalde-
4.24 (m, 4H, 2CH2), 9.58 (s, 1H, HCO). Anal. Calcd for
C6H8N2O2S: C, 41.85; H, 4.68; N, 16.27; S, 18.62. Found:
C, 41.86; H, 4.70; N, 16.40; S, 18.83.
hyde (3j). Yield: 73%; m.p.: 158e160 ꢀC (DCM/petroleum
1
ether); IR (CHCl3): 1695 cmꢂ1; H NMR (CDCl3) d: 4.00e
4.31 (m, 4H, 2CH2), 7.30e7.85 (m, 4H, Ar-H), 9.50 (s, 1H,
HCO). Anal. Calcd for C11H9ClN2O2S: C, 49.17; H, 3.38;
N, 10.42; S, 11.93. Found: C, 49.27; H, 3.39; N, 10.30; S,
11.68.
5.1.3. Parallel procedure for the preparation of 3-acyl-2-
thioxoimidazolidine-1-carbaldehydes 3bed, 3f, 3j,
3meo, 3q and 3s
5.1.3.6. 3-(2,4-Dichlorophenyl)-2-thioxoimidazolidine-1-car-
The suitable acyl chloride (11 mmol) was added in one
portion to each numbered round-bottomed flask of a Carou-
sel-6 Reaction StationÔ, containing a stirred solution of 2-
thioxo-imidazolidine-1-carbaldehyde (10 mmol, 1.301 g) in
pyridine (20 mL). The resulting mixtures were stirred for
12 h at rt. Then, 100 mL of water were added into each
round-bottomed flask. The contents of the flasks were trans-
ferred into a set of separating funnels. After parallel extrac-
tion with CH2Cl2, the combined extracts of each reaction
were washed with a saturated NaHCO3 solution, a 2 N
HCl solution and brine, and dried over anhydrous Na2SO4.
Evaporation in parallel under reduced pressure using an
EvaposelÔ apparatus gave residues which were purified by
crystallization from the suitable solvents or solvent
mixtures.
baldehyde (3m). Yield: 58%; m.p.: 103e105 ꢀC (DCM/petro-
1
leum ether); IR (CHCl3): 1688 cmꢂ1; H NMR (CDCl3) d:
3.84e4.47 (m, 4H, 2CH2), 7.24e7.53 (m, 3H, Ar-H), 9.50
(s, 1H, HCO). Anal. Calcd for C11H8Cl2N2O2S: C, 43.58; H,
2.66; N, 9.24; S, 10.58. Found: C, 43.52; H, 2.89; N, 9.21;
S, 10.32.
5.1.3.7. 3-(3,4-Dichlorophenyl)-2-thioxoimidazolidine-1-car-
baldehyde (3n). Yield: 64%; m.p.: 164e166 ꢀC (DCM/petro-
1
leum ether); IR (CHCl3): 1689 cmꢂ1; H NMR (CDCl3) d:
4.00e4.30 (m, 4H, 2CH2), 7.49e7.60 (m, 2H, Ar-H), 7.73e
7.85 (m, 1H, Ar-H), 9.50 (s, 1H, HCO). Anal. Calcd for
C11H8Cl2N2O2S: C, 43.58; H, 2.66; N, 9.24; S, 10.58. Found:
C, 43.72; H, 2.81; N, 9.16; S, 10.27.
5.1.3.8. 3-(3,5-Dichlorophenyl)-2-thioxoimidazolidine-1-car-
5.1.3.1. 3-(2,2-Dimethylpropanoyl)-2-thioxoimidazolidine-1-
baldehyde (3o). Yield: 78%; m.p.: 164e166 ꢀC (DCM/petro-
1
carbaldehyde (3b). Yield: 49%; m.p.: 116e118 ꢀC (DCM/
leum ether); IR (CHCl3): 1695 cmꢂ1; H NMR (CDCl3) d:
petroleum ether); IR (CHCl3): 1691 cmꢂ1
(CDCl3) d: 1.43 (s, 9H, 3CH3), 4.01 (s, 4H, 2CH2), 9.46
;
1H NMR
4.00e4.32 (m, 4H, 2CH2), 7.48e7.66 (m, 3H, Ar-H), 9.50
(s, 1H, HCO). 13C NMR (DMSO-d6) d: 41.17 (CH2N),
46.17 (CH2N), 127.07 (2CH), 130.90 (2C), 133.78 (CH),
(s, 1H, HCO). Anal. Calcd for C9H14N2O2S: C, 50.45; H,

1116
S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
137.93 (C), 161.93 (CHO), 167.95 (CO), 179.95 (CS). Anal.
Calcd for C11H8Cl2N2O2S: C, 43.58; H, 2.66; N, 9.24; S,
10.58. Found: C, 43.33; H, 2.79; N, 9.00; S, 10.54.
solvent mixtures. Work-up (iii) (14s): the mixture was ex-
tracted with CH2Cl2. The organic layer was washed with
brine, filtered through a plug of Florisil (diameter 5 ꢃ 2 cm)
and evaporated in vacuo using an EvaposelÔ apparatus, to
give a residue which was purified by crystallization from
DCM/ethanol.
5.1.3.9. 3-(3,4,5-Trimethoxybenzoyl)-2-thioxoimidazolidine-1-
carbaldehyde (3q). Yield: 78%; m.p.: 229e231 ꢀC (diethyl
1
ether); IR (CHCl3): 1695 cmꢂ1; H NMR (CDCl3) d: 3.90
(s, 6H, 2CH3), 3.95 (s, 3H, CH3), 3.83e4.32 (m, 4H, 2CH2),
7.02 (s, 2H, Ar-H), 9.53 (s, 1H, HCO). Anal. Calcd for
C14H16N2O5S: C, 51.84; H, 4.97; N, 8.64; S, 9.89. Found:
C, 51.97; H, 5.01; N, 8.66; S, 9.70.
5.1.5.1. {[3-(2-Furoyl)-2-thioxoimidazolidin-1-yl]methylene}-
malononitrile (4s). Yield: 44%; m.p.: 205e207 ꢀC (acetone);
1
IR (KBr): 2231, 1695, 1599 cmꢂ1; H NMR (DMSO-d6) d:
4.23e4.60 (m, 4H, 2CH2), 6.81 (dd, J ¼ 4.2 Hz, J ¼ 1.8 Hz,
1H, fur H-4), 7.56 (d, J ¼ 4.2 Hz, 1H, fur H-3), 8.10 (d,
J ¼ 1.8 Hz, 1H, fur H-5), 8.61 (s, 1H, CH]C). Anal. Calcd
for C12H8N4O2S: C, 52.93; H, 2.96; N, 20.58; S, 11.77. Found:
C, 53.20; H, 3.10; N, 20.62; S, 11.54.
5.1.3.10. 3-(2-Furoyl)-2-thioxoimidazolidine-1-carbaldehyde
(3s). Yield: 75%; m.p.: 119e121 ꢀC (diethyl ether); IR
(CHCl3): 1693 cmꢂ1 1H NMR (CDCl3) d: 4.00e4.30 (m,
;
4H, 2CH2), 6.63 (dd, J ¼ 3.8 Hz, J ¼ 1.6 Hz, 1H, fur H-4),
7.35 (d, J ¼ 3.8 Hz, 1H, fur H-3), 7.65 (d, J ¼ 1.6 Hz, 1H,
fur H-5), 9.54 (s, 1H, HCO). Anal. Calcd for C9H8N2O3S:
C, 48.21; H, 3.60; N, 12.49; S, 14.30. Found: C, 48.30; H,
3.69; N, 12.19; S, 14.23.
5.1.5.2. Methyl (2E )-2-cyano-3-[3-(2-furoyl)-2-thioxoimidazo-
lidin-1-yl]acrylate (5s). Yield: 79%; m.p.: 185e187 ꢀC (ace-
tone); IR (KBr): 2216, 1727, 1678, 1604 cmꢂ1 1H NMR
;
(DMSO-d6) d: 3.83 (s, 3H, CH3), 4.30e4.60 (m, 4H, 2CH2),
6.73e6.89 (m, 1H, fur H-4), 7.54 (d, J ¼ 4.2 Hz, 1H, fur H-
3), 8.01e8.12 (m, 1H, fur H-5), 8.98 (s, 1H, CH]C). Anal.
Calcd for C13H11N3O4S: C, 51.14; H, 3.63; N, 13.76; S,
10.50. Found: C, 51.05; H, 3.70; N, 13.95; S, 10.28.
5.1.4. Preparation of [(3-benzoyl-2-thioxoimidazolidin-1-
yl)methylene]malononitrile (4d)
Benzoyl chloride (5.5 mmol, 0.638 mL) was added drop-
wise to a stirred solution of V (5 mmol, 0.891 g) and TMEDA
(5.5 mmol, 0.825 mL) in pyridine (10 mL). The resulting mix-
ture was stirred at rt for 2 h. After dilution with 120 mL of
a 2 N HCl solution, the solid precipitated was filtered off,
dried and crystallized from acetone. Yield: 52ꢂ%1; m.p.: 238e
5.1.5.3. (2E )-2-Benzoyl-3-[3-(2-furoyl)-2-thioxoimidazolidin-
1-yl]acrylonitrile (6s). Yield: 57%; m.p.: 218e220 ꢀC (ace-
tone/DCM); IR (KBr): 2214, 1682, 1640, 1596 cmꢂ1 1H
;
NMR (DMSO-d6) d: 4.34e4.72 (m, 4H, 2CH2), 6.73e6.91
(m, 1H, fur H-4), 7.49e7.90 (m, 6H, 5Ar-H and fur H-3),
8.01e8.17 (m, 1H, fur H-5), 8.90 (s, 1H, CH]C). Anal. Calcd
for C18H13N3O3S: C, 61.53; H, 3.73; N, 11.96; S, 9.12. Found:
C, 61.44; H, 3.83; N, 11.89; S, 9.02.
240 ꢀC; IR (KBr): 2223, 1697, 1596 cm
;
1H NMR
(CF3COOD) d: 4.48e4.86 (m, 4H, 2CH2), 7.40e7.72 (m,
3H, Ar-H), 8.01e8.29 (m, 2H, Ar-H), 8.67 (s, 1H, CH]C).
Anal. Calcd for C14H10N4OS: C, 59.56; H, 3.57; N, 19.85;
S, 11.36. Found: C, 59.46; H, 3.57; N, 20.15; S, 11.16.
5.1.5.4. (2E )-2-(2,2-Dimethylpropanoyl)-3-[3-(2-furoyl)-2-thi-
oxoimidazolidin-1-yl]acrylonitrile (7s). Yield: 63%; m.p.:
160e162 ꢀC (DCM/ethanol); IR (KBr): 2206, 1685,
;
1565 cmꢂ1 1H NMR (CDCl3) d: 1.37 (s, 9H, C(CH3)3),
5.1.5. Parallel procedure for the preparation of N-
acyl(thio)ureas 4se17s
2-Furoyl chloride (5.5 mmol, 0.542 mL) was added drop-
wise to each numbered reaction tube of a Carousel-12 Reac-
tion StationÔ, containing a stirred solution of the suitable
(thio)urea (VeXVIII) (5 mmol) and TMEDA (5.5 mmol,
0.825 mL) in pyridine (20 mL). The resulting mixtures were
stirred for 4 h at 65 ꢀC. After cooling to rt, a 2 N HCl solution
(25 mL) was added into each tube. The contents of the tubes
were then transferred into a set of beakers. More 2 N HCl so-
lution (125 mL) was added into each beaker. Three different
types of work-up were carried out. Work-up (i) (4s, 6se9s,
12s and 13s): the precipitates obtained were filtered off in par-
allel by an in-house device, dried and crystallized from the
suitable solvent or solvent mixture. Work-up (ii) (5s, 10s,
11s and 15se17s): the amorphous precipitates obtained were
filtered off in parallel by an in-house device and dissolved in
CH2Cl2. The solutions were washed with brine, dried over an-
hydrous Na2SO4 and filtered in parallel through pads of Flori-
sil (diameter 5 ꢃ 2 cm) by an in-house device. Parallel
evaporating in vacuo using an EvaposelÔ apparatus gave res-
idues which were purified by crystallization from the suitable
4.25e4.71 (m, 4H, 2CH2), 6.60e6.71 (m, 1H, fur H-4), 7.37
(d, J ¼ 4.2 Hz, 1H, fur H-3), 7.60e7.70 (m, 1H, fur H-5),
9.23 (s, 1H, CH]C). Anal. Calcd for C16H17N3O3S: C,
57.99; H, 5.17; N, 12.68; S, 9.67. Found: C, 58.28; H, 5.32;
N, 12.76; S, 9.89.
5.1.5.5. (2E )-2-Cyano-3-[3-(2-furoyl)-2-thioxoimidazolidin-1-
yl]acrylamide (8s). Yield: 75%; m.p.: 246e248 ꢀC (acetone/
methanol); IR (KBr): 3436, 3187, 2210, 1693, 1649,
;
1590 cmꢂ1 1H NMR (DMSO-d6) d: 4.25e4.61 (m, 4H,
2CH2), 6.73e6.91 (m, 1H, fur H-4), 7.46e7.76 (m, 3H, NH2
and fur H-3), 8.00e8.16 (m, 1H, fur H-5), 8.96 (s, 1H,
CH]C). Anal. Calcd for C12H10N4O3S: C, 49.65; H, 3.47;
N, 19.30; S, 11.04. Found: C, 49.61; H, 3.67; N, 19.14; S,
10.96.
5.1.5.6. (2E )-N-(4-Chlorophenyl)-2-cyano-3-[3-(2-furoyl)-2-
thioxoimidazolidin-1-yl]acrylamide (9s). Yield: 90%; m.p.:
236e238 ꢀC (acetone/DCM); IR (KBr): 3338, 2213, 1683,

S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
1117
1591 cmꢂ1
;
1H NMR (DMSO-d6) d: 4.23e4.67 (m, 4H,
C20H18N2O5S: C, 60.29; H, 4.55; N, 7.03; S, 8.05. Found:
C, 60.20; H, 4.54; N, 6.94; S, 7.97.
2CH2), 6.73e6.94 (m, 1H, fur H-4), 7.36e7.89 (m, 5H,
4Ar-H and fur H-3), 8.03e8.18 (m, 1H, fur H-5), 9.00 (s,
1H, CH]C). Anal. Calcd for C18H13ClN4O3S: C, 53.94; H,
3.27; N, 13.98; S, 8.00. Found: C, 53.80; H, 3.38; N, 13.83;
S, 7.92.
5.1.5.12. {[3-(2-Furoyl)-2-oxoimidazolidin-1-yl]methylene}-
malononitrile (15s). Yield: 87%; m.p.: 233e234 ꢀC (acetone);
IR (KBr): 2223, 1776, 1664, 1594 cmꢂ1; 1H NMR (DMSO-d6)
d: 4.29e4.38 (m, 4H, 2CH2), 6.76 (dd, J ¼ 4.8 Hz, J ¼ 1.2 Hz,
1H, fur H-4), 7.50 (d, J ¼ 4.8 Hz, 1H, fur H-3), 8.0e8.11 (m,
1H, fur H-5), 8.28 (s, 1H, CH]C). Anal. Calcd for
C12H8N4O3: C, 56.25; H, 3.15; N, 21.87. Found: C, 55.26;
H, 3.19; N, 22.09.
5.1.5.7. 3-{[3-(2-Furoyl)-2-thioxoimidazolidin-1-yl]methyle-
ne}pentane-2,4-dione (10s). Yield: 64%; m.p.: 164e166 ꢀC
(DCM); IR (KBr): 1696, 1677, 1648, 1601 cmꢂ1; H NMR
1
(DMSO-d6) d: 2.38 (s, 3H, CH3), 2.45 (s, 3H, CH3), 3.75e
4.01 (m, 2H, CH2), 4.05e4.34 (m, 2H, CH2), 6.72e6.90 (m,
1H, fur H-4), 7.49 (d, J ¼ 4.2 Hz, 1H, fur H-3), 7.99e8.12
(m, 1H, fur H-5), 8.52 (s, 1H, CH]C). 13C NMR (DMSO-
d6) d: 26.18 (CH3), 32.41 (CH3), 46.61 (2CH2N), 112.73
(CH), 120.28 (CH), 126.05 (C), 137.21 (CH), 146.09 (C),
147.41 (]CH), 159.39 (NCO), 179.17 (CS), 196.41 (CO),
202.82 (CO). Anal. Calcd for C14H14N2O4S: C, 54.89; H,
4.61; N, 9.14; S, 10.47. Found: C, 54.92; H, 4.65; N, 9.07;
S, 10.34.
5.1.5.13. (2Z )-1-Phenyl-2-{[3-(2-furoy)-2-oxoimidazolidin-1-
yl]methylene}butane-1,3-dione (16s). Yield: 67%; m.p.: 205e
207 ꢀC (DCM/ethanol); IR (KBr): 1767, 1746, 1675, 1620,
1577 cmꢂ1; 1H NMR (DMSO-d6) d: 2.31 (s, 3H, CH3), 3.25e
3.60 (m, 2H, CH2), 3.69e4.01 (m, 2H, CH2), 6.58e6.76 (m,
1H, fur H-4), 7.35e7.97 (m, 7H, 5Ar-H, fur H-3 and fur H-5),
8.10 (s, 1H, CH]C). Anal. Calcd for C19H16N2O5: C, 64.77;
H, 4.58; N, 7.95. Found: C, 65.01; H, 4.69; N, 7.96.
5.1.5.8. (2Z )-1-Phenyl-2-{[3-(2-furoyl)-2-thioxoimidazolidin-
1-yl]methylene}butane-1,3-dione (11s). Yield: 71%; m.p.:
179e181 ꢀC (acetone/petroleum ether); IR (KBr): 1671,
5.1.5.14. Ethyl (2E )-2-benzoyl-3-[3-(2-furoy)-2-oxoimidazoli-
din-1-yl]acrylate (17s). Yield: 48%; m.p.: 155e157 ꢀC (etha-
nol); IR (KBr): 1757, 1694, 1668, 1611, 1575 cmꢂ1; 1H NMR
(DMSO-d6) d: 1.03 (t, J ¼ 6.6 Hz, 3H, CH3), 3.18e3.52 (m,
2H, NCH2), 3.72e4.19 (m, 4H, NCH2 and OCH2), 6.64e6.84
(m, 1H, fur H-4), 7.40e8.06 (m, 7H, 5Ar-H, fur H-3 and fur
H-5), 8.15 (s, 1H, CH]C). Anal. Calcd for C20H18N2O6: C,
62.82; H, 4.74; N, 7.33. Found: C, 62.97; H, 4.71; N, 7.27.
1618, 1575 cmꢂ1 1H NMR (DMSO-d6) d: 2.37 (s, 3H,
;
CH3), 3.40e3.77 (m, 2H, CH2), 3.85e4.30 (m, 2H, CH2),
6.66e6.88 (m, 1H, fur H-4), 7.35e8.12 (m, 7H, 5Ar-H, fur
H-3 and fur H-5), 8.78 (s, 1H, CH]C). Anal. Calcd for
C19H16N2O4S: C, 61.94; H, 4.38; N, 7.60; S, 8.70. Found:
C, 62.11; H, 4.47; N, 7.56; S, 8.37.
5.2. Pharmacology
5.1.5.9. Methyl (2Z )-2-acetyl-3-[3-(2-furoyl)-2-thioxoimidazo-
lidin-1-yl]acrylate (12s). Yield: 44%; m.p.: 159e160 ꢀC (ace-
tone); IR (KBr): 1716, 1680, 1607 cmꢂ1; 1H NMR (CDCl3) d:
2.38 (s, 3H, CH3); 3.68e4.25 (m, 7H, 2CH2 and OCH3),
6.52e6.72 (m, 1H, fur H-4), 7.24e7.41 (m, 1H, fur H-3),
7.57e7.69 (m, 1H, fur H-5), 8.68 (s, 1H, CH]C). Anal. Calcd
for C14H14N2O5S: C, 52.17; H, 4.38; N, 8.69; S, 9.95. Found:
C, 52.14; H, 4.52; N, 8.75; S, 10.00.
5.2.1. Evaluation of antiproliferative and antiviral activity
in MT-4 cells (MTT method)
Antiproliferative activity of compounds, based on the via-
bility of mock-infected cells as monitored by the MTT
method, was evaluated in parallel with their antiviral activity.
Activity against the HIV-1 multiplication in acutely infected
cells was based on inhibition of virus-induced cytopathogenicity
in MT-4 lymphoblastoid T cells [23] [cells from American
Type Culture Collection (ATCC, USA) grown in RPMI 1640
containing 10% foetal calf serum (FCS), 100 UI/mL penicillin
G and 100 mg/mL streptomycin; cell culture checked periodi-
cally for the absence of mycoplasma contamination with a My-
coTect Kit (Gibco)]. Briefly, 50 mL of RPMI 10% FCS
containing 1 ꢃ 104 cells were added to each well of flat-bot-
tomed microtiter trays containing 50 mL of medium and serial
dilutions of test compounds (test compound initially dissolved
in DMSO at the concentration of 100 mM and then serially
diluted in culture medium). Twenty microlitres of an HIV-1
suspension containing 100 CCID50 were then added. After
a four-day incubation at 37 ꢀC the number of viable cells
was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-di-
phenyl-tetrazolium bromide (MTT) method [24]. The com-
pound concentrations resulting in 50% cell growth inhibition
in comparison with untreated controls and expressed as IC50
values were determined by linear regression analysis.
5.1.5.10. 1,3-Diphenyl-2-{[3-(2-furoyl)-2-thioxoimidazolidin-
1-yl]methylene}propane-1,3-dione (13s). Yield: 80%; m.p.:
199e201 ꢀC (DCM/ethanol); IR (KBr): 1675, 1603,
1
1571 cmꢂ1; H NMR (CDCl3) d: 3.67e3.84 (m, 2H, CH2),
3.99e4.15 (m, 2H, CH2), 6.50e6.60 (m, 1H, fur H-4),
7.25e7.95 (m, 12H, 10Ar-H, fur H-3 and fur H-5), 8.70 (s,
1H, CH]C). Anal. Calcd for C24H18N2O4S: C, 66.96; H,
4.21; N, 6.51; S, 7.45. Found: C, 67.08; H, 4.23; N, 6.26; S,
7.49.
5.1.5.11. Ethyl (2E )-2-benzoyl-3-[3-(2-furoyl)-2-thioxoimida-
zolidin-1-yl]acrylate (14s). Yield: 97%; m.p.: 142e144 ꢀC
1
(DCM/ethanol); IR (KBr): 1698, 1684, 1653, 1607 cmꢂ1; H
NMR (DMSO-d6) d: 1.02 (t, J ¼ 6.6 Hz, 3H, CH3), 3.46e
3.78 (m, 2H, NCH2), 3.90e4.25 (m, 4H, NCH2 and OCH2),
6.64e6.85 (m, 1H, fur H-4), 7.39e8.12 (m, 7H, 5Ar-H, fur
H-3 and fur H-5), 8.81 (s, 1H, CH]C). Anal. Calcd for

1118
S. Cesarini et al. / European Journal of Medicinal Chemistry 44 (2009) 1106e1118
[7] S. Li, Y. Wang, Huaxue Shiji 25 (2003) 89e90.
5.2.2. Evaluation of anticancer activity at NCI
[8] S. Xue, S. Ke, L. Duan, Youji Huaxue 24 (2004) 227e230.
[9] W. Wu, W. Ye, Z. Du, Y. Wang, Hecheng Huaxue 11 (2003) 310e314.
[10] V.S. Misra, R.N. Pandey, P.R. Dua, Pol. J. Pharmacol. Pharm. 31 (1979)
161e167.
[11] A. Ranise, F. Bondavalli, O. Bruno, S. Schenone, C. Losasso,
M. Costantino, M.L. Cenicola, D. Donnoli, E. Marmo, Farmaco 46
(1991) 317e338.
[12] A. Ranise, F. Bondavalli, O. Bruno, S. Schenone, D. Donnoli, C. Parrillo,
M.L. Cenicola, F. Rossi, Farmaco 46 (1991) 1203e1216.
[13] A. Ranise, A. Spallarossa, O. Bruno, S. Schenone, P. Fossa, G. Menozzi,
F. Bondavalli, L. Mosti, A. Capuano, F. Mazzeo, G. Falcone,
W. Filippelli, Farmaco 58 (2003) 765e780.
The NCI high-flux anticancer drug screen [25e27] utilized
a panel of 60 human tumor cell lines in culture derived from
nine cancer types (lung, colon, CNS, ovarian, renal, prostate
and breast cancer, leukemia and melanoma). The compound
were tested at 10-fold dilutions of five concentrations ranging
from 10ꢂ4 to 10ꢂ8 M. According to the NCI protocol, cell
lines were exposed to test agents in 96-well plates for the
last 48 of a 72 h incubation and a sulforhodamine B (SRB)
protein assay was used to estimate cell viability or growth.
For each compound, the drug concentration required to pro-
duce 50% (GI50) and total (TGI) growth inhibition, and 50%
cytocidal effect (LC50) were obtained for 47e60 cell lines.
Values were calculated for each of these parameters if the level
activity was reached; if the effect was not reached or was ex-
ceeded, the value is expressed as greater or lesser than the
maximum or minimum concentration tested.
[14] G. Roy, D. Das, G. Mugesh, Inorg. Chim. Acta 360 (2007) 303e316 and
references therein.
[15] H. Kohn, B.A. Kohn, M.L. Steenberg, J.P. Buckley, J. Med. Chem. 20
(1977) 158e160.
[16] A. Rodger, K.K. Patel, K.J. Sanders, M. Datt, C. Sacht, M. Hannon, J.
Chem. Soc., Dalton Trans. 19 (2002) 3656e3663.
[17] W. Hernandez, E. Spodine, J.C. Munoz, L. Beyer, U. Schroeder,
J. Ferreira, M. Pavani, Bioinorg. Chem. Appl. 1 (2003) 271e284.
[18] W. Hernandez, E. Spodine, L. Beyer, U. Schroeder, R. Richter,
J. Ferreira, M. Pavani, Bioinorg. Chem. Appl. 3 (2005) 299e316.
[19] G. Hallur, A. Jimeno, S. Dalrymple, T. Zhu, M.K. Jung, M. Hidalgo,
J.T. Isaacs, S. Sukumar, E. Hamel, S.R. Khan, J. Med. Chem. 49
(2006) 2357e2360.
Acknowledgements
The authors are very grateful to Dr. V.L. Narayanan, Chief
of Drug Synthesis and Chemistry Branch, National Cancer In-
stitute (Bethesda, MD, USA) for the in vitro evaluation of an-
ticancer activity. This work was supported by MURST
(Cofinanziamento Nazionale), CNR (Rome) and Ministero
[20] T. Furuta, T. Sakai, T. Senga, T. Osawa, K. Kubo, T. Shimizu, R. Suzuki,
T. Yoshino, M. Endo, A. Miwa, J. Med. Chem. 49 (2006) 2186e2192.
[21] A. Ranise, S. Cesarini, A. Spallarossa, F. Sancassan, F. Bondavalli,
O. Bruno, S. Schenone, G. Menozzi, P. Fossa, L. Mosti, Synthesis 16
(2007) 2495e2502.
`
Italiano della Salute e Istituto Superiore di Sanita (grant no.
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