Imidazo[2,1-b]thiazepines: Synthesis, structure and evaluation of benzodiazepine receptor binding

Article abstract of DOI:10.1016/j.ejmech.2003.11.009

As a continuation of our search for new ligands acting on benzodiazepine receptors among the fused 2-thiohydantoin derivatives, a series of 5-substituted imidazo[2,1-b]thiazepines was synthesized and investigated in radioligand binding studies at the benz

Full text of DOI:10.1016/j.ejmech.2003.11.009

European Journal of Medicinal Chemistry 39 (2004) 205–218
www.elsevier.com/locate/ejmech
Original article
Imidazo[2,1-b]thiazepines: synthesis, structure and evaluation
of benzodiazepine receptor binding
Katarzyna Kiec´-Kononowicz a,*, Janina Karolak-Wojciechowska b, Barbara Michalak a,
Elz˙bieta PVkala a, Britta Schumacher c, Christa E. Müller c
a Department of Chemical Technology of Drugs, Jagiellonian University Medical College, ul Medyczna 9, PL 30-688 Kraków, Poland
b
˙
Institute of General and Ecological Chemistry, Technical University, Zwirki 36, PL 90-924 Łódz´, Poland
c Pharmaceutical Institute Poppelsdorf, University of Bonn, Kreuzbergweg 26, 53115 Bonn, Germany
Received 4 July 2001; received in revised form 10 November 2003; accepted 14 November 2003
Abstract
As a continuation of our search for new ligands acting on benzodiazepine receptors among the fused 2-thiohydantoin derivatives, a series
of 5-substituted imidazo[2,1-b]thiazepines was synthesized and investigated in radioligand binding studies at the benzodiazepine binding site
of GABAA receptors in rat brain cortical membranes. Among ortho-substituted 5-arylidene-imidazo[2,1-b]thiazepines compounds could be
identified which exhibit affinity for the benzodiazepine binding site at low micromolar concentrations. X-ray structure analyses for two
compounds (6ae and 6ag) have been performed. In order to analyze the structure–activity relationships, 3D models of all compounds have
been completed (using X-ray data). Physicochemical properties calculated (log P and log D) as well as experimental thin layer chromatogra-
phy data were examined.
© 2003 Elsevier SAS. All rights reserved.
Keywords: Benzodiazepine receptor; GABAA receptor; Imidazo[2,1-b]thiazepines; Structure–activity relationships; X-ray structure analysis
1. Introduction
(anxiogenic, and proconvulsant activities). Antagonists do
not exhibit any direct pharmacological effects but can an-
tagonize the actions of both agonists and inverse agonists
[1–8]. Partial agonists lie within this continuum and may
have reduced benzodiazepine-mediated side effects such as
physical dependence, amnesia, oversedation and muscle re-
laxation [8,9]. Recently the development of partial
agonists/antagonists [10–13] as well as receptor subtype se-
lective ligands [14,15] has been the aim of several research
groups.
In our research program, bicyclic heterocyclic compounds
consisting of condensed 5 + 5, 5 + 6 and 5 + 7 ring systems
were examined (Fig. 1). Derivatives of imidazo[2,1-
b]thiazoles, -thiazines and -thiazepines possessing additional
aromatic substituent(s) in quadrants A, B, C, D (see Fig. 1)
were synthesized and compared [16–19]. The sulfur atom
was bioisosterically exchanged by nitrogen in the
imidazo[2,1-b]imidazole, -pyrimidinone and -diazepinone
series [19]. In the course of our research it was found that
benzylidene derivatives of imidazo[2,1-b]thiazine exhibit af-
finity for benzodiazepine receptors (BzR) [16]. Their activity
was strongly dependent on the substitution pattern of the
c-Aminobutyric acid acts on the GABAA chloride ion
channel; GABA is the principal inhibitory transmitter of
many CNS pathways regulating numerous neurological
functions including convulsions, anxiety and sleep activity as
well as memory and learning processes [1,2]. Present mo-
lecular biology studies have demonstrated that several differ-
ent receptor subunits (a1–6, b1–4, c1–3, d, e, p, q) combine to
form the GABAA receptor complex with a number of native
receptor subtypes identified thus far [3–6]. Numerous struc-
tural classes of chemical compounds bind to the GABAA
chloride ion channel complex including the benzodiazepines,
neurosteroids and barbiturates. Ligands acting at the benzo-
diazepine binding site of the GABAA receptor allosterically
modulate the action of GABA on neuronal chloride ion flux.
They show a wide variety of pharmacological actions rang-
ing in a continuum from full agonists (sedative/hypnotic,
anxiolytic and anticonvulsant activities) to inverse agonists
* Corresponding author.
E-mail address: mfkonono@cyf-kr.edu.pl (K. Kiec´-Kononowicz).
© 2003 Elsevier SAS. All rights reserved.
doi:10.1016/j.ejmech.2003.11.009

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K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
the Knoevenagel condensation of aldehydes or ketones 3
(methods A–C) with 2-thiohydantoin. Aldehydes 3 were re-
acted with 2-thiohydantoin in stoichiometric amounts
(method A) or with 10% excess in water (method B) in the
presence of alanine and sodium carbonate (method A), or in
acetic acid in the presence of sodium acetate (method B) used
as basic reaction catalysts. Condensation with ketones
(method C) was performed in toluene. Cyclization of
2-thiohydantoin derivatives with 1,4-dibromobutane under
phase transfer catalysis conditions (acetone, potassium car-
bonate, benzyl triethylammonium chloride [BTEA] catalyst)
provided the desired imidazo[2,1-b]thiazepines 6–8
(Figs. 3 and 4). In the synthesis of the isomers 8 (Fig. 4)
5,5-diphenyl-2-thiohydantoin was used. [20,21].
Fig. 1. Basic skeleton of the synthesized bicyclic structures [16–19].
benzylidene residue. Their profile of action was character-
ized as partially agonistic at the BzRs on the basis of the
GABA shift [16]. Continuing our research on these classes of
compounds we have now explored imidazo[2,1-b]thiazepine
bicyclic ring system in more detail because enlargement of
the ring annelated to the imidazole ring—thiazole toward
thiazine—had been found to increase the BzR affinity
[16,19].
In order to confirm the structural assignment and to deter-
mine the conformational properties of the imidazo[2,1-
b]thiazepines, X-ray structure analyses for two derivatives
were performed. For this analysis, the ortho-substituted de-
rivatives 6ae and 6ag were selected taking into account their
important biological activity (Table 4) and the degree to
which the conformation is influenced by ortho-substitution.
Generally for the Z-isomers, due to the free rotation of the
phenyl ring attached to the exocyclic methylene bond
(Fig. 5), two planar conformations (syn and anti) should be
taken into consideration and the anti conformation was ex-
pected to be energetically favored. In the case of the ortho-
substituted derivatives, due to steric repulsion, deviation
from planarity is expected and X-ray studies of 6ae and 6ag
confirm this. The respective ORTEP drawings with atom
numbering are shown in Fig. 6. All X-ray details, non-
hydrogen atoms fractional coordinates and selected geo-
metrical data are collected in Tables 1–3. Firstly the
Z-configuration for derivatives 6a–h has been confirmed by
X-ray structure analysis (see Fig. 6 and corresponding tor-
sion angles in Table 3). Moreover, in both derivatives the
ortho-substituents (o-OCH3 6ae; o-CF3 6ag) are anti with
2. Chemistry
The designed imidazo[2,1-b]thiazepine derivatives 6–8
(Figs. 3 and 4) were obtained by methods described in the
literature [16,20,36]. As starting materials for the synthesis
of imidazo[2,1-b]thiazepines 6 and 7 (Fig. 3) appropriate
aldehydes or ketones were used. Non-commercial deriva-
tives of meta- or para-hydroxybenzaldehydes 2 were synthe-
sized as described in Fig. 2. The ethers 2a–d were obtained
by the reactions of the appropriate hydroxybenzaldehydes
with alkylating agents performed in ethanol in the presence
of potassium carbonate. Esters 2e–g resulted from the reac-
tions of benzoyl chlorides with 4-hydroxybenzaldehyde car-
ried out in pyridine at room temperature. A series of
2-thiohydantoin derivatives 5 (Figs. 3 and 4) was prepared by
Fig. 2. Procedure for the preparation of substituted meta- (2a–2c) or para- (2d–2g) hydroxy-benzaldehydes.

K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
207
Fig. 3. Two-step procedure for the preparation of imidazo[2,1-b]thiazepines 6 and 7.
respect to the seven-membered thiazepine ring. The thermo-
3. Biological assays
dynamic stability for the anti-conformation with the C62–
C61–C6–C5 torsion angle close to 180° is confirmed by the
potential energy distribution presented in Fig. 7. In the
crystals phenyl and the imidazolone rings are not exactly
coplanar with dihedral angles between phenyl and the planar
five-membered imidazolone rings equaling 14.7(2)° in com-
pound 6ae and 5.7(3)° in compound 6ag, respectively. As the
torsion angles collected in Table 3 suggest, the thiazepine
rings in both structures possess a half-chair form flattened at
the C2 atom.
Compounds series 6, 7 and 8 were investigated in radioli-
gand binding assays at rat brain cortical membranes for their
affinity to the benzodiazepine binding sites of the GABAA
receptor. All compounds were screened for their ability to
displace [3H]diazepam from its binding site at a single con-
centration (Table 4). Ki values were determined from a dose–
response curve for the most potent compounds of the present
series, 6aa, 6ab, 6ac, 6ad, 6ae, 6ag, 6ah, 6aj, 6bd, 6bh,
6cb, 6cd, 6ce and 8a. The most active compounds 6aa, 6ab,

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K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
Table 1
X-ray structure analysis of 6ag and 6ae
6ae
6ag
(A) Crystal parameters
Formula
C
15H16N2O2S
C15H13F3N2OS
Molecular weight
Crystallization medium
Colour
288.36
326.33
Dioxane
Dioxane
Lemon yellow
0.1 × 0.1 × 0.3
a = 9.343(2) Å
Lemon yellow
0.2 × 0.2 × 0.4
a = 9.734(2) Å
Crystal size, mm
Cell dimensions
b = 12.684(3) Å b = 13.549(3) Å
c = 12.184(2) Å c = 11.313(2) Å
b = 103.81(3)°
P21/n
b = 103.23(3)°
P21/c
Space group
Molecules/unit cell
Density calculated
Linear absorption factor, mm–1
4
4
1.366 Mg/m3
2.078
1.492 Mg/m3
2.333
Fig. 4. Structures of further investigated imidazo[2,1-b]thiazepines; for 8a
and 8b see ref. [20].
(B) Refinement parameters
Number of reflections
Non-zero reflections [I > 4 r(I)]
R-index
1840
3030
6ac and 6cb were evaluated for their profile of action by
means of their GABA shift [22].
1745
2866
0.068
0.067
The highest affinity compounds in vitro, 6aa, 6ab, 6ac,
6ad, 6ah, 6bb,and 6cb, were evaluated in vivo for their
anticonvulsant activity and neurological toxicity according
to the Antiepileptic Drug Development (ADD) Program,
using published testing procedures [23,24]. Phase I of the
evaluation included three tests: maximal electroshock
(MES), subcutaneous pentylenetetrazol (ScMet), and ro-
torod test for neurological toxicity (Tox).
GOF
1.010
1.019
Secondary extinction factor
0.0014 (2)
0.0006 (3)
4. Results and discussion
The in vitro results obtained for the newly synthesized and
screened compounds are presented in the Table 4. Com-
pounds with affinities in low micromolar concentrations
were obtained; based on their GABA shift ratios [22] they
were classified either as weak partial agonists (6aa, 6ac), or
neutral antagonists (6ab, 6cb), respectively.
Lipophilicity parameters are important physicochemical
properties in (Q)SAR studies. Lipophilicity expressed as log
P values was calculated [25], log P values equaled log D
since the analyzed compounds did not possess any acidic or
basic functionalities. Lipophilicities expressed by Rmo values
were determined by reversed phase thin layer chromatogra-
phy (RP-TLC) on the basis of the relationships of the Rm
values and the content of organic modifier in the mobile
Fig. 5. Syn- and anti-conformations of the ortho-substituted derivatives of
imidazo[2,1-b]thiazepines.
Fig. 6. The structures of (a) 6ae and (b) 6ag.

K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
209
Table 2
Table 3
Atomic coordinates (×104) and equivalent isotropic displacement parame-
ters (Å2 × 103)
Selected geometrical data: dihedral and torsion angles (°)
6ae
6ag
x
y
z
U (eq)
Dihedral angle
between
14.7(2)
5.7(3)
Compound 6ae
S
Ph/imidazole rings
C5–C6–C61–C62
C7–S–C2–N3
C2–S–C7–C8
S–C7–C8–C9
C7–C8–C9–C10
C8–C9–C10–N3
C2–N3–C10–C9
S–C2–N3–C10
1961 (2)
1551 (3)
1060 (4)
–219 (3)
–623 (4)
–1707 (3)
545 (4)
8248 (1)
10011 (2)
9060 (3)
8807 (2)
9674 (3)
9733 (2)
10449 (3)
11432 (3)
6973 (3)
6441 (3)
6890 (4)
7929 (3)
12285 (3)
13312 (3)
14139 (3)
13971 (4)
12964 (4)
12138 (3)
13426 (2)
14473 (3)
261 (1)
91 (1)
56 (1)
57 (1)
58 (1)
60 (2)
76 (1)
49 (1)
51 (1)
84 (2)
74 (2)
129 (3)
102 (2)
44 (1)
53 (1)
66 (2)
75 (2)
70 (2)
61 (2)
70 (1)
82 (2)
–164.9 (4)
37.8 (5)
–72.9 (4)
75.8 (5)
–66.8 (7)
72.4 (8)
–65.2 (8)
14.8 (7)
C5–C6–C61–C62
C7–S–C2–N3
–7.3 (6)
N(1)
–933 (3)
–829 (3)
–1629 (3)
–2319 (4)
–3107 (3)
–1855 (3)
–2276 (3)
–332 (4)
–569 (4)
–1598 (5)
–1585 (5)
–1901 (3)
–2267 (3)
–1846 (4)
–1034 (4)
–668 (4)
–1084 (3)
–3070 (2)
–3491 (4)
–45.0 (4)
76.7 (4)
–75.9 (5)
66.6 (6)
–74.3 (6)
65.1 (6)
–8.6 (6)
C(2)
C2–S–C7–C8
N(3)
S–C7–C8–C9
C(4)
C7–C8–C9–C10
C(8)–C9–C10–N3
C2–N3–C10–C9
S–C2–N3–C10
O(4)
C(5)
C(6)
558 (4)
C(7)
1796 (5)
304 (5)
C(8)
C(9)
–780 (6)
–1232 (5)
1596 (4)
1229 (4)
2162 (5)
3451 (5)
3821 (4)
2920 (4)
–55 (3)
pounds were found. Presumably, more spatially voluminous
derivatives fit better into the lipophilic pocket of the BzR
receptor (Fig. 9). The position of the annelated ring is impor-
tant as shows the comparison of the activity of compounds 8a
and 8b: The 1,2-substituted derivative 8b was less potent
than the 2,3-substituted compound (8b). A flat, substituted
aromatic ring connected by an exocyclic double bond was
important for high activity, whereas the folded cycloalky-
lidene derivative 7b was less active. A greater distance of the
aromatic ring from the bicyclic skeleton in 6da caused a
decrease in BzR affinity, as did the introduction of a methyl
substituent into the exocyclic methylene group (compounds
6db and 6dc).
The size and substitution pattern of the arylidene ring has
been shown to greatly influence the receptor affinity of the
investigated compounds [16,19]. Introduction of an addi-
tional aromatic ring in the meta- (6bc, 6bf, 6bg) as well as in
the para-position (6cf, 6cg, 6ch, 6cj, and 6ck) was not
advantageous. The lipophilicity (calculated log P values are
in the range of 4.12–5.81) was very high causing problems
with the determination of the BzR affinity in some cases (e.g.
6bf). The affinity had to be determined at a lower concentra-
tion (2.5 µM) for compounds 6cf, 6cg and 6ck and it was low
to negligible at that concentration. Compounds 6bc, 6bg,
6ch, 6cj also showed low affinity in a concentration of
25 µM. Ortho-substituted arylidene derivatives were among
the most active compounds (e.g. 6ab, 6ac, 6ad, 6ae, 6ah).
The ortho-substituent should have a limited size. Thus, com-
pound 6ab fits better into the small lipophilic pocket of the
Cook and coworkers model of the BzR (Fig. 9) [28] than
compounds 6ae and 6ag with larger substituents. A similar
conclusion can be made by the comparison of the affinity of
the halogen containing derivatives (2-F > 2-Cl > 2-Br) with
Ki values of 0.93, 2.2, and 4.5 µM, respectively.
C(10)
C(61)
C(62)
C(63)
C(64)
C(65)
C(66)
O(62)
C(67)
–464 (5)
Compound 6ag
S(1)
454 (1)
156 (1)
7922 (1)
5983 (3)
6598 (3)
6092 (3)
5007 (3)
4295 (2)
4959 (3)
4070 (3)
8905 (4)
8678 (4)
7589 (5)
6446 (5)
3895 (3)
4786 (3)
4628 (4)
3592 (4)
2701 (4)
2839 (3)
1841 (4)
2182 (2)
1377 (2)
898 (2)
86 (1)
53 (1)
57 (1)
61 (1)
54 (1)
80 (1)
50 (1)
52 (1)
90 (2)
84 (2)
107 (2)
99 (2)
53 (1)
58 (1)
70 (1)
78 (1)
74 (1)
60 (1)
82 (2)
96 (1)
100 (1)
121 (1)
N(1)
–1700 (3)
–672 (4)
–498 (3)
–1502 (3)
–1628 (3)
–2285 (3)
–3424 (3)
658 (5)
243 (2)
C(2)
–280 (2)
–1192 (2)
–1253 (2)
–1930 (2)
–319 (2)
–128 (3)
–881 (3)
–1686 (3)
–2319 (3)
–1880 (3)
720 (2)
N(3)
C(4)
O(4)
C(5)
C(6)
C(7)
C(8)
1632 (5)
976 (6)
C(9)
C(10)
C(61)
C(62)
C(63)
C(64)
C(65)
C(66)
C(67)
F(1)
703 (5)
–4353 (3)
–4233 (3)
–5118 (4)
–6135 (4)
–6293 (4)
–5432 (4)
–5666 (4)
–6022 (3)
–4545 (3)
–6712 (3)
1455 (2)
2276 (3)
2371 (3)
1668 (3)
843 (3)
102 (4)
–783 (2)
–26 (2)
F(2)
F(3)
377 (3)
phase [26]. Corrected log P (c log P) values were determined
on the basis of experimental RP-TLC data [27].
Preliminary analysis of structure–affinity relationships re-
vealed that enlargement of the annelated ring (thiazole and
thiazine toward thiazepine) was beneficial for the receptor
affinity. Dissimilarity between the structures (determined
with semi-empirical calculations) of arylidene bicyclic de-
rivatives 5 + 5, 5 + 6 and 5 + 7 is presented in Fig. 8. Contrary
to the almost flat inactive imidazothiazole structure (5 + 5),
among the more puckered imidazothiazine (5+6) and espe-
cially the thiazepine (5 + 7) derivatives (Fig. 8), active com-
In the meta- and para-position larger substituents, such as
OCH2COOEt (compare 6bh and 6cd) -are better tolerated.
QSAR studies were performed for a number of derivatives
from series 6 with determined Ki values. At a first step
p—constants for substituents in ortho-, meta- and para-
positions [29] were examined (Table 5). For the selection of
further similarity descriptors of the analyzed derivatives, it
was decided to consider quantum chemistry calculation re-

210
K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
Table 4
Physicochemical properties and inhibition of [3H]diazepam binding to rat brain cortical membranes by arylidene (6, 7) and diphenyl (8) imidazo[2,
1-b]thiazepines
Compound
6aa
6ab
6ac
6ad
6ae
6af
6ag
6ah
6ai
Test concentration (µM)
Percent specific inhibition
Ki (µM) (GABA shift)
1.5 0.5 [1.5]
0.93 0.39 [0.8]
2.2 0.5 [1.7]
4.5 1.9
Log P
2.63
2.79
3.35
3.51
2.59
3.07
3.78
2.53
3.90
3.55
3.41
2.61
4.32
3.17
Rmo
c logP
2.98
3.31
3.65
3.84
2.96
2.14
2.83
2.59
3.47
2.94
3.31
3.36
4.44
3.36
n.d.
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
2.5
2.5
25
25
25
2.5
25
25
25
25
25
25
25
81
92
83
71
59
3
3
2
1
3
1.91
2.05
2.19
2.27
1.90
1.55
1.84
1.75
2.11
1.89
2.05
2.07
2.52
2.07
n.d.
11.4 2.1
36 12
53
83
0
6
7
2 a
42.3 13.2 c
2.0 0.3
6aj
51 20
39 23 a
2.8 1.2
6ba
6bb
6bc
6bd
6be
6bf
6bg
6bh
6ca
6cb
6cc
6cd
6ce
6cf
6cg
6ch
6ci
61
0 a
54
4
3
10.6 2.1
48 16
n.d.
5.03
5.81
3.04
3.36
2.59
2.60
2.94
2.60
4.12
4.80
4.67
2.79
4.59
4.30
3.28
3.11
3.75
3.85
2.95
3.25
3.08
3.21
2.83
3.17
2.08
2.24
1.83
1.94
1.30
1.68
2.38
2.87
2.62
1.79
2.51
2.52
1.91
1.73
2.37
2.32
1.35
1.97
3.08
5.17
5.99
3.40
3.78
2.79
3.07
1.54
2.43
4.11
5.28
4.68
2.70
4.42
4.44
2.98
2.55
4.08
7
7 a
6
51
11.9 3.7
47 3.4
74
16
45
53
16
5
7
6
3
5
3
2.5 1.0 [0.9]
6.4 0.83
23.6 10.9
5
3
8
28
3
2
6cj
3
4
6ck
6da
6db
6dc
7a
7b
8a
8b
4
32
22
16
n.d.
27
9
3
4
3.97
b
1
61 10
35 11
n.d.
30.3 6.3
3.12
b
Diazepam
0.025 0.006d [3.4]
n.d., not detected, compound insoluble at test concentrations.
a Inhibition of [3H]diazepam binding may be underestimated due to low solubility of the compound.
b Compounds were not chromatographically congeneric.
c Estimated Ki-value by extrapolation; determination of full inhibition curve was precluded by limited solubility.
d Ref. [16].
sults based on our previous studies [30] on BzR ligands.
Consequently starting from crystallographic data the mol-
ecules from series 6 with determined Ki values were roughly
modelled [PCMODEL] and optimised with the AM1
semiempirical quantum chemistry method in aqueous envi-
ronment [MOPAC.6]. At the same time two compounds 6bh
and 6cd were rejected from the calculations, as their
arylidene substituent OCH2COOEt was too flexible for
simple geometry optimisation without careful conformation
analysis. For that reason only 11 (instead of 13) derivatives
were selected for QSAR studies. After geometry optimiza-
tion electronic similarity parameters (dipole moment µ and
HOMO energies), gathered in Table 5 and tested for QSAR
utility did not allow to obtain good correlations, as well as
considered lipophilicity descriptors (log P calculated with
PALLAS program and experimental values Rmo and c log P).
The investigated compounds tested in vivo according to
the ADD Program of the NIH in Bethesda, MD, USA, were
devoid of anticonvulsant activity (in doses up to 300 mg/kg)
in maximal electroshock seizures and subcutaneous pentyle-
netetrazole (ScMet) tests. This result maybe reasoned by
their pharmacokinetic properties (metabolism, low penetra-
tion into the brain). It could be also taken into the discussion
their more expressed activity through the respective GABAA.
subunits. As it was stated, while GABAA-a1-receptor is more
engaged in anticonvulsant and sedative effects, the
GABAA-a2 is more connected with attenuation of anxiety

K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
211
Table 5
The parameters applied for QSAR analysis for 11 derivatives from series 6
Compound Ki Substituent constans c logP µ (debay) HOMO
(kcal/mol)
–8.87
–8.80
–8.95
–8.99
–8.78
–8.99
–8.68
–8.71
–8.87
–8.72
–8.40
po
0
pp
0
pm
0
6aa
6ab
6ac
6ad
6ae
6ag
6ah
6aj
1.5
2.98
3.31
3.65
3.84
2.96
2.83
2.59
4.53
5.78
5.79
6.08
3.14
8.13
4.26
3.35
4.37
3.17
3.96
0.93 0.14
0
0
2.2
4.5
0.71
0.86
0
0
0
0
11.4 –0.02
42.3 0.88
0
0
0
0
2.0
–0.02 –0.02
0
2.8
0.56
–0.02 0.56 2.94
6bd
6cb
6ce
10.6
2.5
0
0
0
0
0.56 3.36
–0.02
0.18
0
0
2.79
2.43
Fig. 7. The strain energy (as astimated using AM1 Hamiltonian) of 6ae as a
function of phenyl ring rotation round the C61–C6 bond.
23.6
Fig. 8. Molecules of the arylidene bicyclic derivatives: 5 + 5, 5 + 6, and 5 + 7.
solvent systems were: A chloroform/ethyl acetate (1:1); B
toluene/acetone (20:1.5); spots were visualized by UV ab-
sorption at 254 nm. Column chromatography was performed
on Merck silica gel 60 (70–230 mesh) using the solvent
methylene chloride/ethyl acetate (1:1).
Electron impact and electron spray mass spectra were
recorded on an AMD-604, or a Finningan MAT 95S spec-
trometer respectively, with a direct inlet. Infrared spectra
were measured with an FT IR 410 spectrometer (Jasco) in
KBr pellets. The UV spectra were obtained for solutions of
10–4 mol/l concentration in methylene chloride with a UV
Vis V-530 Jasco spectrometer. The 1H-, and 13C-NMR spec-
tra were performed on a Bruker AC-200F, on a Bruker DPX
250 Avance, on a VARIAN MERCURY 300 MHz or on a
Bruker DPX 400 Avance in DMSOd6 (unless otherwise
stated) using tetramethyl silane as an internal standard
(chemical shifts are reported in d units). The elemental analy-
ses (performed at the Department of Pharmaceutical Chem-
istry of the Jagiellonian University, Kraków, Poland) indi-
cated by the symbols of the elements were within 0.4% of
the theoretical values.
Fig. 9. The Cook model of BzR binding [28] applied to compound 6ag.
[32,33].The investigated compounds have not shown neuro-
logical toxicity (in doses up to 300 mg/kg).
5.1.2. Preparation of 2-thiohydantoins
The starting 2-thiohydantoins 5 were obtained as recently
described [18,19] or in analogy to the described procedures
[31,34–36]. The following new derivatives were prepared:
5. Experimental protocols
5.1. Chemistry
5.1.2.1. Z-5-(Pyridin-3-methylene)-2-thiohydantoin (5be).
A mixture of pyridine-3-carboxaldehyde (5.65 g, 0.05 mol),
2-thiohydantoin (5.8 g, 0.05 mol), alanine (4.46 g; 0.05 mol)
and sodium carbonate (2.65 g, 0.025 mol) in 50 ml of water
was refluxed for 3 h. Afterwards it was diluted with water.
The precipitate was collected; cream-colored crystals, m.p.
5.1.1. General remarks
Melting points were measured on Mel-Temp. II (LD Inc.,
USA) and were not corrected. The TLC was performed on
Merck Silica gel GF254 precoated tlc Al Sheets; the used

212
K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
297–298 °C (DMF + H2O); yield 66%; 1H-NMR (300 MHz)
d: 6.51 (s, 1H, ArCH=), 7.42–7.47 (m, 1H, H-4′), 8.18 (d,
J = 8.0 Hz, 1H, H-3′), 8.54 (dd, J = 1.3 Hz, J = 4.7 Hz, 1H,
H-5′), 8.86 (d, J = 1.9 Hz, 1H, H-1′), 12.30 (s, 1H, N1–H),
12.46 (s, 1H, N3–H); IR m: 3169, 3072 (N–H), 2826 (C–H),
1735 (C=O), 1655 (ArCH=), 1532, 1348, 1194, 1089,
963 cm–1; MS: m/z 205 (M+.), 145, 118, 91. Anal.
(C9H7N3OS) C, H, N.
5.1.2.5. Z-5-[4-(Ethoxycarbonylmethoxy)benzylidene]-2-thio-
hydantoin (5cd).
(a) A mixture of 4-hydroxybenzaldehyde (12.2 g,
0.1 mol), ethyl bromoacetate (16.7 g, 0.1 mol) and
potassium carbonate (6.9 g, 0.05 mol) in 100 ml of
ethanol was heated under reflux for 7 h. On cooling the
solid was filtered off, the solvent was evaporated, the
oily residue was dissolved in methylene chloride and
washed with 2% NaOH solution and then with water,
the solvent was dried over Na2SO4 and evaporated to
yield 76% of 2d as an oil.
(b) 5cd was obtained as described in Section 5.1.2.2; yield
50%; yellow crystals, m.p. 205–207 °C (acetic acid);
1H-NMR (200 MHz) d: 1.20 (t, J = 7.1 Hz, 3H,
CH3CH2), 4.16 (q, J = 7.1 Hz, 2H, CH3CH2), 4.85 (s,
2H, CH2O), 6.45 (s, 1H, ArCH=), 6.96 (d, J = 8.8 Hz,
2H, H-3′, H-5′), 7.72 (d, J = 8.8 Hz, 2H, H-2′, H-6′),
12.15 (br s, 2H, N1–H, N3–H). Anal. (C14H14N2O4S)
C, H, N.
5.1.2.2. Z-5-(4-Benzoyloxybenzylidene)-2-thiohydantoin (5cf).
(a) A mixture of 4-hydroxybenzaldehyde (9.76 g,
0.08 mol) and freshly distilled benzoyl chloride
(14.4 g, 0.1 mol) in 200 ml of pyridine was stirred at
room temperature for 24 h. The reaction mixture was
poured on 200 ml of 2 N acetic acid solution cooled
with ice. The precipitate (2e) was collected, washed
thoroughly with water. Yield: 14.9 g (83%); m.p. 78–
79 °C.
(b) A mixture of 4-benzoyloxybenzaldehyde (2e) (4.28 g,
0.018 mol), 2-thiohydantoin (1.97 g, 0.017 mol) and
anhydrous sodium acetate (6.07 g, 0.073 mol) in 25 ml
glacial acetic acid was refluxed for 2 h. On cooling, the
precipitate was collected, washed thoroughly with wa-
ter; yield 64%; yellow crystals, m.p. 251–254 °C (ace-
tic acid). 1H-NMR (200 MHz) d: 6.53 (s, 1H, ArCH=),
7.35 (d, J = 8.5 Hz, 2H, H-3′, H-5′), 7.59 (t, J = 7.3 Hz,
2H, H-3″, H-5″), 7.74 (m, 1H, H-4″), 7.84 (d,
J = 8.6 Hz, 2H, H-2′, H-6′), 8.13 (d, J = 7.3 Hz, 2H,
H-2″, H-6″), 12.20 (br s, 1H, N1–H), 12.32 (br s, 1H,
N3–H). Anal. (C17H12N2O3S) C, H, N.
5.1.2.6. Z-5-[3-(Ethoxycarbonylmethoxy)benzylidene]-2-thio-
hydantoin (5bh).
(a) 3-(Ethoxycarbonylmethoxy)benzaldehyde 2c was ob-
tained as described in Section 5.1.2.5; yield 52%; oil.
(b) 5bh was obtained as described in 5.1.2.2 b; yield 62%;
1
yellow crystals, m.p. 150–152 °C (acetic acid); H-
NMR (200 MHz) d: 1.30 (t, J = 7.5 Hz, 3H, CH3CH2),
4.26 (q, J = 7.5 Hz, 2H, CH3CH2), 4.96 (s, 2H, CH2O),
6.53 (s, 1H, ArCH=), 7.02–7.07 (m, 1H, H-5′), 7.33 (s,
1H, H-4′), 7.39 (d, J = 7.5 Hz, 1H, H-6′), 7.43 (s, 1H,
H-2′), 12.38 (br s, 2H, N1–H, N3–H); IR m: 3220, 3135,
3069 (N–H), 1741, 1722 (C=O), 1654 (ArCH=), 1373,
1216, 1085, 649 cm–1. Anal. (C14H14N2O4S) C, H, N.
5.1.2.3. Z-5-[4-(4-Chlorobenzoyloxy)benzylidene]-2-thio-
hydantoin (5cg).
(a) 4-(4-Chlorobenzoyloxy)benzaldehyde (2f) was ob-
tained as described in 5.1.2.2.a; yield 93%; m.p. 104–
107 °C
5.1.2.7. Z-5-(2-Fluorobenzylidene)-2-thiohydantoin (5ab).
Obtained as described in Section 5.1.2.2(b) (refluxed for 2 h),
cream-colored yellow crystals, m.p. 201–203 °C; analyti-
(b) 5cg was obtained as described in Section 5.1.2.2(b);
yield 76%; yellow crystals, m.p. 243–245 °C (acetic
1
cally pure; yield 85%; H-NMR (300 MHz) d: 6.44 (s, 1H,
1
acid); H-NMR (200 MHz) d: 6.51 (s, 1H, ArCH=),
ArCH=), 7.21–7.29 (m, 2H, H-3′, H-5′), 7.38–7.46 (m, 1H,
H-4′), 7.80–7.85 (m, 1H, H-6′), 12.17 (s, 1H, N1–H), 12.40
(s, 1H, N3–H). Anal. (C10H7N2OSF) C, H, N.
7.35 (d, J = 8.5 Hz, 2H, H-3′, H-5′), 7.62 (d, J = 8.5 Hz,
2H, H-3″, H-5″), 7.82 (d, J = 8.6 Hz, 2H, H-2′, H-6′),
8.09 (d, J = 8.5 Hz, 2H, H-2″, H-6″), 12.28 (br s, 2H,
N1–H, N3–H). Anal. (C17H11N2O3SCl) C, H, N.
5.1.2.8. Z-5-(2-Trifluoromethylbenzylidene)-2-thiohydan-
toin (5ag). Obtained as described in Section 5.1.2.2(b) (re-
fluxed for 1.5 h), cream-colored crystals, m.p. 289–291 °C;
analytically pure; yield 83%; 1H-NMR (300 MHz) d: 6.49 (d,
J = 1.9 Hz, 1H, ArCH=), 7.55 (t, J = 7.7 Hz, 1H, H-5′),
7.68–7.82 (m, 3H, H-3′, H-4′, H-6′), 12.38 (s, 2H, N1–H,
N3–H). Anal. (C11H7N2OSF3) C, H, N.
5.1.2.4. Z-5-[4-(2-Chlorobenzoyloxy)benzylidene]-2-thio-
hydantoin (5ch).
(a) 4-(2-Chlorobenzoyloxy)benzaldehyde (2f) was ob-
tained as described in Section 5.1.2.2(a); yield 79%;
m.p. 91–94 °C.
(b) 5ch was obtained as described in Section 5.1.2.2(b);
yield 80%; yellow crystals, m.p. 233–235 °C (acetic
5.1.2.9. Z-5-(2-Methylbenzylidene)-2-thiohydantoin (5af).
Obtained as described in Section 5.1.2.2(b) (refluxed 2 h),
cream-colored crystals, m.p. 241–243 °C analytically pure
yield 85%; 1H-NMR (300 MHz) d: 2.33 (s, 3H, CH3), 6.54 (s,
1H, ArCH=), 7.19–7.28 (m, 3H, H-3′, H-4′, H-5′), 7.58–7.61
(m, 1H, H-6′), 12.15 (s, 1H, N1–H), 12.27 (s, 1H, N3–H).
Anal C11H10N2OS) C, H, N.
1
acid); H-NMR (200 MHz) d: 6.52 (s, 1H, ArCH=),
7.37 (d, J = 8.5 Hz, 2H, H-3′, H-5′), 7.49–7.59 (m, 1H,
H-4″), 7.65 (def.d, J = 7.8 Hz, 2H, H-3″, H-5″), 7.85
(d, J = 8.5 Hz, 2H, H-6′, H-2′), 8.09 (d, J = 7.3 Hz, 1H,
H-6″), 12.28 (s, 2H, N1–H, N3–H). Anal.
(C17H11N2O3SCl) C, H, N.

K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
213
5.1.3. Preparation of imidazo[2,1-b][1,3]thiazepinones
Compounds 6aa, 6ca [36] 8a and 8b [20] were obtained
as previously described. The following new derivatives were
prepared in analogy to the described procedures [16,36].
30.08 (SCH2CH2), 31.08 (SCH2), 40.52 (NCH2), 55.68
(OCH3), 111.25 (ArCH=), 118.09 (C-12), 120.61 (C-14),
122.10 (C-10), 131.90 C-13), 132.05 (C-8), 138.15 (C-15),
158.41 (C-11), 165.31 (C-7), 168.71 (C-17); EI-MS: m/z
(%): 288(M+., 100), 257 (40), 215 (7), 195 (9), 130 (8), 88
(15). Anal. (C15H16N2O2S) C, H, N.
5.1.3.1. Z-2-(2-Fluorobenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ab). Yield 24%;
cream-colored to yellow crystals, m.p. 149–151 °C (from
dioxane + water); Rf 0.78 (A); 1H-NMR (200 MHz) d: 1.75–
1.84 (m, 2H, SCH2CH2), 1.99–2.10 (m, 2H, NCH2CH2),
3.15–3.20 (m, 2H, SCH2), 3.75 (m, 2H, NCH2), 6.99 (s, 1H,
CH=), 7.24–7.35 (m, 2H, H-4′, H-5′), 7.43–7.54 (m, 1H,
H-3′), 8.69 (dt, J = 1.8 Hz, J = 8.0 Hz, H-6′); UV kmax (log e):
246 (3.57), 292 (4.02), 378 (4.34), 401 (4.13); IR m: 2944,
2915 (C–H), 1708, 1639, 1486, 1357, 1330, 1209, 1149,
761 cm–1. Anal. (C14H13N2OSF) C, H, N.
5.1.3.5. Z-2-(2-Methylbenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6af). Yield 37%;
pale lemon-yellow crystals, m.p. 129–131 °C (from dioxane
+ water); Rf 0.76 (A); 1H-NMR (200 MHz) d: 1.78–1.83 (m,
2H, SCH2CH2), 1.96–2.06 (m, 2H, NCH2CH2), 2.44 (s, 3H,
CH3), 3.11–3.17 (m, 2H, SCH2), 3.74 (def.t, J = 5.0 Hz, 2H,
NCH2), 7.11 (s, 1H, CH=), 7.26–7.32 (m, 3H, H-3′, H-4′,
H-5′), 8.56–8.61 (m, 1H, H-6′); IR m: 3056, 2916 (C–H),
1698 (C=O), 1648 (ArCH=), 1620, 1590, 1488, 1444, 1376,
1352, 1312, 1196, 1180, 768, 756 cm–1.Anal. (C15H17N2OS)
C, H, N.
5.1.3.2. Z-2-(2-Chlorobenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ac). Yield 34%;
cream-colored crystals, m.p. 148–150 °C (from dioxane); Rf
0.71 (A); 1H-NMR (250 MHz) d: 1.83–1.90 (m, 2H,
SCH2CH2), 2.06–2.15 (m, 2H, NCH2CH2), 3.23–3.27 (def.t,
2H, SCH2), 3.80–3.84 (def.t, 2H, NCH2), 7.25 (s, 1H, CH=),
7.48–7.54 (m, 2H, H-4′, H-5′), 7.61–7.67 (m, 1H, H-3′), 8.82
(dd, J = 7.5 Hz, J = 2.5 Hz, 1H, H-6′); UV kmax (log e): 247
(3.79), 288 (3.85), 381 (3.98), 407 (3.65); IR m: 2924, 2845
(C–H), 1733 (C=O), 1627 (ArCH=), 1556, 1478, 1441, 1353,
1324, 1188, 1120, 949, 752, 676 cm–1; EI-MS: m/z (%):
292(M+., 17); 257 (100, M–Cl); 215 (12); 150 (4), 114 (4).
Anal. (C14H13N2OSCl) C, H, N.
5.1.3.6. Z-2-(2-Trifluoromethylbenzylidene)-5,6,7,8-tetra-
hydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ag).
Yield 16%; lemon-yellow crystals, m.p. 144–146 °C (from
dioxane + water); Rf 0.76 (A); 1H-NMR (200 MHz) d: 1.76–
1.86 (m, 2H, SCH2CH2), 1.99–2.07 (m, 2H, NCH2CH2),
3.17–3.23 (m, 2H, SCH2), 3.73–3.78 (m, 2H, NCH2), 7.03
(d, J = 2.0 Hz, 1H, CH=), 7.60 (t, J = 7.6 Hz, 1H, H-5′), 7.80
(def.t, J = 8.0 Hz, 2H, H-3′, H-4′), 8.81 (d, J = 7.8 Hz, 1H,
H-6′); UV kmax (log e): 252 (3,24), 291 (3.44), 376 (3.69); IR
m: 2920 (C–H), 1712 (C=O), 1648 (ArCH=), 1626, 1480,
1376, 1308, 1148, 1120, 1030, 770, 668 cm–1. Anal.
(C15H13N2OSF3) C, H, N.
5.1.3.3. Z-2-(2-Bromobenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ad). Yield 23%;
lemon-yellow crystals, m.p. 153–155 °C (from dioxane); Rf
0.80 (A); Rf 0.28 (B); 1H-NMR (200 MHz) d: 1.70–1.85 (m,
2H, SCH2CH2), 1.98–2.10 (m, 2H, NCH2CH2), 3.15–3.20
(m, 2H, SCH2), 3.73–3.77 (m, 2H, NCH2), 7.15 (s, 1H,
CH=), 7.33 (dt, J = 1.7 Hz, J = 7.8 Hz, 1H, H-5′), 7.49 (def.t,
J = 7.5 Hz, 1H, H-4′), 7.7 (dd, J = 1.1 Hz, J = 7.9 Hz, 1H,
H-3′), 8.73 (dd, J = 1.6 Hz, J = 7.9 Hz, 1H, H-6′); UV kmax
(log e): 241 (4.49), 282 (4.15), 381 (4.24); IR m: 2920 (C–H),
1708 (C=O), 1648 (ArCH=), 1620, 1480, 1352, 1224, 1154,
840, 764, 560 cm–1. Anal. (C14H13N2OSBr) C, H, N.
5.1.3.7.
Z-2-(2,4-Dimethoxybenzylidene)-5,6,7,8-tetra-
hydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ah).
Yield 24%; orange-yellow crystals, m.p. 158–160 °C (from
dioxane + water); Rf 0.70 (A); 1H-NMR (250 MHz) d: 1.79–
1.85 (m, 2H, SCH2CH2), 2.08–2.10 (m, 2H, NCH2CH2),
3.14–3.18 (m, 2H, SCH2), 3.77–3.81 (m, 2H, NCH2), 3.90 (s,
3H, OCH3), 3.95(s, 3H, OCH3), 6.67–6.75 (m, 2H, H-3′,
H-5′), 7.33 (s, 1H, CH=), 8.72 (d, J = 8.8 Hz, 1H, H-6′); UV
kmax (log e): 261 (4.08), 310 (3.83), 399 (4.59), 408 (4.58);
IR m: 3002, 2937, 2842 (C–H), 1702 (C=O), 1689 (ArCH=),
1592, 1274, 1213, 1189, 1025, 835 cm–1. Anal.
(C16H18N2O3S) C, H, N.
5.1.3.4.
Z-2-(2-Methoxybenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ae). Yield 30%;
lemon-yellow crystals, m.p. 183–184 °C (from dioxane); Rf
0.72 (A); H-NMR (300 MHz) d: 1.78 (m, 2H, SCH2CH2),
2.03 (m, 2H, NCH2CH2), 3.14 (m, 2H, SCH2), 3.74 (m, 2H,
NCH2), 3.89 (s, 3H, OCH3), 7.07 (m, 2H, H-5′, H-4′), 7.33 (s,
1H, ArCH=), 7.42 (t, J = 7.0 Hz, 1H, H-3′), 8.66 (d,
J = 7.8 Hz, 1H, H-6′); UV kmax (log e): 250 (3.40), 294
(3.74), 382 (4.18), 407 (3.96); IR m: 2934 (C–H), 2840
(C–H), 1708 (C=O), 1625 (ArCH=), 1484, 1302, 1249, 1223,
1190, 1161, 1021, 758 cm–1; 13C-NMR d: 26.83 (SCH2CH2),
5.1.3.8. Z-2-(2,3-Dichlorobenzylidene)-5,6,7,8-tetrahydro-
5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ai). Yield
28%; lemon-yellow crystals, m.p. 180–182 °C (from aceto-
1
1
nitrile); Rf 0.81 (A); Rf 0.34 (B); H-NMR (200 MHz) d:
1.79–1.86 (m, 2H, SCH2CH2), 2.02–2.07 (m, 2H,
NCH2CH2), 3.17–3.22 (def.t, J = 5.5 Hz, 2H, SCH2), 3.75
(def.t, J = 5.1 Hz, 2H, NCH2), 7.16 (s, 1H, ArCH=), 7.47 (t,
J = 8.0 Hz, 1H, H-5′), 7.67 (dd, J = 8.0 Hz, J = 1.6 Hz, 1H,
H-4′), 8.67 (dd, J = 8.0 Hz, J = 1.5 Hz, 1H, H-6′); UV kmax
(log e): 257 (3.54), 296 (3.69), 384 (3.94); IR m: 2905, 2852

214
K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
(C–H), 1714 (C=O), 1625 (ArCH=), 1478, 1462, 1410, 1354,
1210, 1181, 1151, 1125, 787, 588 cm–1. Anal.
(C14H12N2OSCl2) C, H, N.
5.1.3.13. Z-2-(3-Methylbenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6bd). Yield 14%;
pale lemon-yellow crystals, m.p. 104–105 °C (from dioxane
+ water); Rf 0.73 (A); 1H-NMR (200 MHz) d: 1.70–1.81 (m,
2H, SCH2CH2), 1.97–2.08 (m, 2H, NCH2CH2), 2.33 (s, 3H,
CH3), 3.11–3.16 (m, 2H, SCH2), 3.74 (def.t, J = 5.0 Hz, 2H,
NCH2), 6.94 (s, 1H, ArCH=), 7.23 (d, J = 7.6 Hz, 1H, H-5′),
7.34 (t, J = 7.5 Hz, 1H, H-4′), 7.97 (s, 1H, H-2′), 8.00 (d,
J = 7.8 Hz, 1H, H-6′); UV kmax (log e): 251 (3.61), 295
(3.86), 258 (4.15), 377 (4.25), 401 (4.03); IR m: 2908 (C–H),
1704 (C=O), 1680, 1648 (ArCH=), 1626, 1480, 1348, 1192,
1118, 1040, 928, 836, 784, 696 cm–1. Anal. (C15H17N2OS)
C, H, N.
5.1.3.9.
Z-2-(4-Methoxy-2,5-dimethylbenzylidene)-5,6,
7,8-tetrahydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one
(6aj). Yield 46%; lemon-yellow crystals, m.p. 190–193 °C
(methylene chloride + ethyl acetate); Rf 0.73 (A); 1H-NMR
(250 MHz) d: 1.75–1.79 (m, 2H, SCH2CH2), 1.98–2.03 (m,
2H, NCH2CH2), 2.12 (s, 3H, CH3), 2.40 (s, 3H, CH3), 3.08–
3.13 (m, 2H, SCH2), 3.72–3.76 (m, 2H, NCH2), 3.83 (s, 3H,
OCH3), 6.88 (s, 1H, ArCH=), 7.06 (s, 1H, H-3′), 8.50 (s, 1H,
H-6′); UV kmax (log e): 261 (4.16), 399 (4.71), 423 (4.57); IR
m: 3062, 2938 (C–H), 1685 (C=O), 1625 (ArCH=), 1594,
1504, 1488, 1267, 1220, 1099, 1066, 838 cm–1. Anal.
(C17H20N2O2S) C, H, N.
5.1.3.14. Z-2-(Pyridine-3-methylene)-5,6,7,8-tetrahydro-
5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6be). Yield
28%; lemon-yellow crystals, m.p. 148–150 °C (from aceto-
1
5.1.3.10.
Z-2-(3-Chlorobenzylidene)-5,6,7,8-tetrahydro-
nitrile); Rf 0.81 (A), Rf 0.34 (B); H-NMR (200 MHz) d:
5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ba). Yield
24%; pale lemon-yellow crystals, m.p. 110–112 °C (from
dioxane + water); Rf 0.74 (A); 1H-NMR (250 MHz) d: 1.81–
1.90 (m, 2H, SCH2CH2), 2.06–2.15 (m, 2H, NCH2CH2),
3.22–3.26 (m, 2H, SCH2), 3.81 (def.t, J = 5.3 Hz, 2H,
NCH2), 7.04 (s, 1H, ArCH=), 7.52–7.55 (m, 2H, H-4′, H-5′),
8.14–8.17 (m, 1H, H-6′), 8.39 (s, 1H, H-2′); UV kmax (log e):
247 (4.00), 292 (4.09), 377 (4.42), 399 (4.25); IR m: 2912
(C–H), 1712 (C=O), 1648 (ArCH=), 1632, 1564, 1480, 1346,
1184, 796, 672 cm–1. Anal. (C14H13N2OSCl) C, H, N.
1.79–1.98 (m, 2H, SCH2CH2), 2.01–2.08 (m, 2H,
NCH2CH2), 3.17 (def.t, J = 5.4 Hz, 2H, SCH2), 3.74 (def.t,
J = 5.0 Hz, 2H, NCH2), 7.02 (s, 1H, ArCH=), 7.45–7.51 (m,
1H, H-5′), 8.55 (dd, J = 1.6 Hz, J = 4.8 Hz, 1H, H-4′), 8.65
(dt, J = 1.8 Hz, J = 8.1 Hz, 1H, H-6′), 9.14 (d, J = 1.9 Hz, 1H,
H-2′); UV kmax (log e): 253 (3.14), 296 (3.02), 359 (3.13),
405 (3.39); IR m: 2946, 2907, 2853 (C–H), 1725 (C=O), 1637
(ArCH=), 1551, 1482, 1328, 1203, 1185, 1135, 951, 815,
715, 706 cm–1. Anal. (C13H13N3OS) C, H, N.
5.1.3.15.
Z-2-[3-(4-Chlorobenzyloxy)benzylidene)-5,6,
5.1.3.11. Z-2-(3-Nitrobenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6bb). Yield 26%;
lemon-yellow crystals, m.p. 182–184 °C (from dioxane +
7,8-tetrahydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one
(6bf). Yield 34%; pale lemon-yellow crystals, m.p. 108–
111 °C (from dioxane + water); Rf 0.82 (A); 1H-NMR
(250 MHz) d: 1.81–1.89 (m, 2H, SCH2CH2), 2.06–2.15 (m,
2H, NCH2CH2), 3.20–3.24 (m, 2H, SCH2), 3.81 (def.t,
J = 5.0 Hz, 2H, NCH2), 7.01 (s, 1H, ArCH=), 7.13 (dd,
J = 2.0 Hz, J = 8.0 Hz, 1H, H-4′), 7.43 (t, J = 8.0 Hz, 1H,
H-5′), 7.52 (d, J = 8.5 Hz, 2H, H-3″, H-5″), 7.58 (d,
J = 8.5 Hz, 2H, H-2″, H-6″), 7.80 (d, J = 7.8 Hz, 1H, H-6′),
7.99 (s, 1H, H-2′); UV kmax (log e): 252 (4.10), 292 (4.05),
380 (4.46), 402 (4.33); IR m: 2920 (C–H), 1696 (C=O), 1648
(ArCH=), 1630, 1564, 1488, 1288, 1250, 1152, 1036, 808,
784 cm–1. Anal. (C21H19N2O2SCl) C, H, N.
1
water); Rf 0.72 (A); Rf 0.11 (B); H-NMR (300 MHz) d:
1.78–1.82 (m, 2H, SCH2CH2), 2.03–2.05 (m, 2H,
NCH2CH2), 3.16–3.20 (def.t, 2H, SCH2), 3.27–3.76 (def.t,
J = 4.3 Hz, 2H, NCH2), 7.10 (s, 1H, ArCH=), 7.71 (t,
J = 8.0 Hz, 1H, H-5′), 8.20 (dd, J = 8.2 Hz, J = 2.2 Hz, 1H,
H-4′), 8.48 (d, J = 8.0 Hz, 1H, H-6′), 9.12 (s, 1H, H-2′); UV
kmax (log e): 254 (4.25), 286 (4.29), 378 (4.41), 399 (4.25);
IR m: 3070, 2951, 2934, 2907 (C–H), 1716 (C=O), 1638
(ArCH=), 1520, 1483, 1347, 1193, 1161, 927, 740, 668 cm–1.
Anal. (C14H13N3O3S) C, H, N.
5.1.3.12. Z-2-(3-Phenoxybenzylidene)-5,6,7,8-tetrahydro-
5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6bc). Yield
17%; yellow crystals, m.p. 127–129 °C (from dioxane +
5.1.3.16. Z-2-[3-(2,4-Dichlorobenzyloxy)benzylidene]-5,6,
7,8-tetrahydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one
(6bg). Yield 10%; pale lemon-yellow crystals, m.p. 135–
137 °C (from dioxane + water); Rf 0.88 (A); 1H-NMR
(250 MHz) d: 1.77–1.81 (m, 2H, SCH2CH2), 2.02–2.05 (m,
2H, NCH2CH2), 3.13–3.17 (m, 2H, SCH2), 3.73 (def.t,
J = 5.0 Hz, 2H, NCH2), 6.95 (s, 1H, ArCH=), 7.09 (dd,
J = 2.0 Hz, J = 8.0 Hz, 1H, H-5″), 7.38 (t, J = 8.3 Hz, 1H,
H-5′), 7.47 (dd, J = 2.0 Hz, J = 8.4 Hz, 1H, H-6″), 7.64 (d,
J = 8.3 Hz, 1H, H-4′), 7.69 (d, J = 2.0 Hz, 1H, H-3″), 7.75 (d,
J = 8.0 Hz, 1H, H-6′), 7.94 (d, J = 1.3 Hz, 1H, H-2′); UV kmax
(log e): 249 (4.09), 292 (4.03), 379 (4.43), 401 (4.28); IR m:
2915 (C–H), 1707 (C=O), 1633 (ArCH=), 1573, 1487, 1436,
1
water); Rf 0.76 (A); H-NMR (200 MHz) d: 1.68–1.86 (m,
2H, SCH2CH2), 1.97–2.11 (m, 2H, NCH2CH2), 3.10–3.16
(m, 2H, SCH2), 3.72 (def.t, J = 4.6 Hz, 2H, NCH2), 6.98 (s,
1H, ArCH=), 7.01–7.06 (m, 3H, H-3″, H-4″, H-5″), 7.15 (t,
J = 7.3 Hz, 1H, H-5′), 7.36–7.49 (m, 3H, H-4′, H-2″, H-6″),
7.87 (d, J = 7.8 Hz, 1H, H-6′), 8.01 (s, 1H, H-2′); UV kmax
(log e): 359 (4.30), 378 (4.41), 399 (4.27); IR m: 2944, 2916
(C–H), 1702 (C=O), 1628 (ArCH=), 1584, 1564, 1484, 1428,
1256, 1220, 1192, 1168, 1156, 1116, 760, 694 cm–1. Anal.
(C20H18N2O2S) C, H, N.

K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
215
1345, 1267, 1200, 1166, 1046, 835, 785, 707 cm–1. Anal.
(C21H18N2O2SCl2) C, H, N.
Yield 18%; dark orange crystals, m.p. 177–180 °C (from
dioxane + water); Rf 0.63 (A); 1H-NMR (250 MHz) d: 1.71–
1.76 (m, 2H, SCH2CH2), 2.00–2.03 (m, 2H, NCH2CH2),
3.01 (s, 6H, 2 × CH3), 3.04–3.08 (m, 2H, SCH2), 3.70–3.73
(m, 2H, NCH2), 6.75 (d, J = 7.5 Hz, 2H, H-3′, H-5′), 6.90 (s,
1H, ArCH=), 8.04 (d, J = 7.5 Hz, 2H, H-2′, H-6′); UV
kmax(log e); 263 (4.13), 322 (3.71), 448 (4.74); IR m: 2917
(C–H), 1693 (C=O), 1589 (ArCH=), 1529, 1444, 1380, 1322,
1195, 1184, 1153, 1116, 821 cm–1. Anal. (C16H19N3OS) C,
H, N.
5.1.3.17. Z-2-[3-(Ethoxycarbomethoxy)benzylidene]-5,6,
7,8-tetrahydro-5H-imidazo[2,1-b][1,3]
thiazepin-3(2H)-
one (6bh). Yield 28%; lemon-yellow crystals, m.p. 107–
1
109 °C (from methylene chloride); Rf 0.80 (A); H-NMR
(250 MHz) d: 1.29 (t, J = 7.5 Hz, 3H, CH3), 1.84–1.86 (m,
2H, SCH2CH2), 2.09–2.11 (m, 2H, NCH2CH2), 3.20–3.24 (s,
3H, SCH3), 3.78–3.82 (m, 2H, NCH2), 4.25 (q, J = 7.5 Hz,
2H, OCH2CH3), 4.86 (s, 2H, CH2O), 7.01 (s, 1H, ArCH=),
7.04–7.08 (m, 1H, H-4′), 7.44 (t, J = 5.0 Hz, 1H, H-5′), 7.91
(s, 1H, H-2′), 7.80 (d, J = 5.0 Hz, 1H, H-6′); UV kmax (log e):
251 (3.91), 367 (4.37), 388 (4.51), 410 (3.36); IR m: 2967,
2917 (C–H), 1758 (COOEt), 1712 (C=O), 1627 (ArCH=),
1488, 1203, 1085, 777, 676 cm–1. Anal. (C18H20N2O4S) C,
H, N.
5.1.3.22. Z-8-[(4-Benzoyloxy)-benzylidene]-2,3,4,5-tetrahy-
droimidazo[2,1-b]thiazepin-7-one (6cf). Yield 12%; yellow
crystals, m.p. 157–160 °C (from methylene chloride + ethyl
1
acetate); Rf 0.82 (A); H-NMR (200 MHz) d: 1.79 (m, 2H,
SCH2CH2), 2.03 (m, 2H, NCH2CH2), 3.13–3.18 (m, 2H,
SCH2), 3.75 (def.t, 2H, NCH2), 7.04 (s, 1H,ArCH=), 7.40 (d,
J = 8.7 Hz, 2H, H-3′, H-5′), 7.61 (t, J = 7.7 Hz, 2H, H-3″,
H-5″), 7.73–7.76 (m, 1H, H-4″), 8.14 (def.d, 2H, H-2″,
H-6″), 8.29 (d, J = 8.7 Hz, 2H, H-2′, H-6′); IR m: 1736
(COO), 1704 (C=O), 1631 (ArCH=), 1594 (C=N), 1416,
1384, 1254, 1200, 1167, 1080, 1024, 962, 711 cm–1. Anal.
(C21H18N2O3S) C, H, N.
5.1.3.18. Z-2-(4-Methoxybenzylidene)-5,6,7,8-tetrahydro-
5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6cb). Yield
21%; lemon-yellow crystals, m.p. 125–128 °C (from dioxane
+ water); Rf 0.72 (A); 1H-NMR (200 MHz) d: 1.70–1.85 (m,
2H, SCH2CH2), 1.95–2.10 (m, 2H, NCH2CH2), 3.09–3.14
(m, 2H, SCH2), 3.74 (def.t, J = 4.6 Hz, 2H, NCH2), 3.82 (s,
3H, OCH3), 6.97 (s, 1H, ArCH=), 7.02 (d, J = 8.8 Hz, 2H,
H-3′, H-5′), 8.16 (d, J = 8.8 Hz, 2H, H-2′, H-6′); IR m: 2920
(C–H), 1692 (C=O), 1648 (ArCH=), 1592, 1506, 1480, 1254,
1176, 1156, 1022, 836, 546 cm–1. Anal. (C15H17N2O2S) C,
H, N.
5.1.3.23. Z-2-[4-(4-Chlorobenzoyloxy)-benzylidene]-2,3,4,
5-tetrahydroimidazo-[2,1-b]-thiazepin-7-one (6cg). Yield
11%; lemon-yellow crystals, m.p. 184–187 °C (from meth-
ylene chloride); Rf 0.79 (A); 1H-NMR (200 MHz) d: 1.87 (m,
2H, SCH2CH2), 2.13 (m, 2H, NCH2CH2), 3.23 (def.t, 2H,
SCH2), 3.84 (t, 2H, NCH2), 7.12 (s, 1H, ArCH=), 7.48 (d,
J = 8.7 Hz, 2H, H-3′, H-5′), 7.77 (d, J = 8.5 Hz, 2H, H-3″,
H-5″), 8.22 (d, J = 8.5 Hz, 2H, H-2″, H-6″), 8.37 (d, J =8.8
Hz, 2H, H-2′, H-6′); IR m: 1741 (COO), 1709 (C=O), 1636
(ArCH=), 1590 (C=N), 1482, 1385, 1259, 1208, 1188, 1167,
1086, 1064, 1012, 904, 871, 750, 676, 560. Anal.
(C21H17N2O3SCl) C, H, N.
5.1.3.19. Z-2-(4-Ethoxybenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6cc). Yield 30%;
lemon-yellow crystals, m.p. 170–173 °C (from dioxane +
water); Rf 0.80 (A); 1H-NMR (250 MHz) d: 1.33 (t,
J = 7.0 Hz, 3H, CH3), 1.68–1.80 (m, 2H, SCH2CH2), 1.90–
2.05 (m, 2H, NCH2CH2), 3.08–3.11 (m, 2H, SCH2), 3.70–
3.74 (def.t, J = 4.8 Hz, 2H, NCH2), 4.08 (q, J = 7.0 Hz, 2H,
CH2CH3), 6.95 (s, 1H,ArCH=), 6.99 (d, J = 8.8 Hz, 2H, H-3′,
H-5′), 8.13 (d, J = 8.8 Hz, 2H, H-2′, H-6′); IR m: 2971, 2927
(C–H), 1702 (C=O), 1639 (ArCH=), 1630, 1598, 1251, 1178,
1043 cm–1. Anal. (C16H18N2O2S) C, H, N.
5.1.3.24. Z-2-[4-(2-Chlorobenzoyloxy)benzylidene]-2,3,4,5-
tetrahydroimidazo-[2,1-b]-thiazepin-7-one (6ch). Yield
21%; lemon-yellow crystals, m.p. 152–154 °C (from meth-
1
ylene chloride); Rf 0.84 (A); H-NMR (200 MHz) d: 1.78–
1.82 (m, 2H, SCH2CH2), 2.02–2.05 (m, 2H, NCH2CH2),
3.13–3.18 (m, 2H, SCH2), 3.74 (t, 2H, NCH2), 7.03 (s, 1H,
CH=), 7.37 (d, J = 8.5 Hz, 2H, H-3′, H-5′), 7.53–7.58 (m, 1H,
H-4″), 7.66–7.69 (m, 2H, H-3″, H-5″), 8.1 (d, J = 7.2 Hz, 1H,
H-6″), 8.29 (d, J =8.8 Hz, 2H, H-2′, H-6′); IR m: 2941 (C–H),
1731, 1698 (C=O), 1633 (ArCH=), 1593 (C=N), 1493, 1433,
1381 (COO), 1279, 1213, 1186, 1166, 1119, 962, 869, 824,
777, 751, 715, 686, 648 cm–1. Anal. (C21H18N2O3S) C, H, N.
5.1.3.20. Z-2-[4-(Ethoxycarbomethoxy)benzylidene)]-5,6,
7,8-tetrahydro-5H-imidazo[2,1-b][1,3]
thiazepin-3(2H)-
one (6cd). Yield 31%; lemon-yellow crystals, m.p. 117–
120 °C (from dioxane + water); Rf 0.84 (A); 1H-NMR
(250 MHz) d: 1.28 (t, J = 5.0 Hz, 3H, CH3), 1.83–1.86 (m,
2H, SCH2CH2), 2.09 (m, 2H, NCH2CH2), 3.16–3.21 (m, 2H,
SCH3), 3.78–3.82 (m, 2H, NCH2), 4.23 (q, J = 7.5 Hz, 2H,
OCH2CH3), 4.92 (s, 2H, OCH2CO), 7.03 (s, 1H, ArCH=),
7.08 (d, J = 10.0 Hz, 2H, H-3′, H-5′), 8.22 (d, J = 10.0 Hz,
2H, H-2′, H-6′); IR m: 2911(C–H), 1766 (COOEt), 1704
(C=O), 1629 (ArCH=), 1598, 1492, 1205, 1176, 1085,
838 cm–1. Anal. (C18H20N2O4S) C, H, N.
5.1.3.25. Z-2-(4-Carbomethoxybenzylidene)-5,6,7,8-tetra-
hydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ci).
Yield 32%; lemon-yellow crystals, m.p. 213–215 °C (from
1
methylene chloride + ethyl acetate); Rf 0.77 (A); H-NMR
(200 MHz) d: 1.75–1.84 (m, 2H, SCH2CH2), 1.99–2.07 (m,
2H, NCH2CH2), 3.16–3.21 (m, 2H, SCH2), 3.76 (def.t,
5.1.3.21. Z-2-(4-Dimethylaminobenzylidene)-5,6,7,8-tetra-
hydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ce).

216
K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
J = 5.1 Hz, 2H, NCH2), 7.01 (s, 1H, ArCH=), 8.00 (d,
J = 8.2 Hz, 2H, H-3′, H-5′), 8.28 (d, J = 8.5 Hz, 2H, H-6′,
H-2′); IR m: 2946 (C–H), 1718 (COOMe, C=O), 1627
(ArCH=), 1477, 1274, 1108, 840, 711, 698 cm–1. Anal.
(C16H16N2O3S) C, H, N.
5.1.3.30.
Z-2-[Methyl-(4-chlorophenyl)methylene]-5,6,
7,8-tetrahydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one
(6dc). Yield 5%; cream-rose-colored crystals, m.p. 119–
122 °C (from ethyl acetate); Rf 0.77 (A); 1H-NMR
(250 MHz) d: 1.78–1.83 (m, 2H, SCH2CH2), 2.02–2.09 (m,
2H, NCH2CH2), 2.72 (s, 3H, CH3), 3.08–3.12 (m, 2H,
SCH2), 3.77–3.81 (m, 2H, NCH2), 7.55 (d, J = 10.0 Hz, 2H,
H-3′, H-5′), 7.85 (d, J = 10.0 Hz, 2H, H-2′, H-6′); IR m: 2944,
2908 (C–H), 1697 (C=O), 1619 (ArC=), 1500, 1220, 1199,
1164, 1091, 1074, 954 cm–1.Anal. (C15H15N2OSCl) C, H, N.
5.1.3.26. Z-2-(4-Phenylbenzylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6cj). Yield 34%;
lemon-yellow crystals, m.p. 140–143 °C (from dioxane +
1
water); Rf 0.75 (A); H-NMR (250 MHz) d: 1.70–1.80 (m,
2H, SCH2CH2), 1.90–2.10 (m, 2H, NCH2CH2), 3.12–3.16
(m, 2H, SCH2), 3.74 (def.t, J = 5.0 Hz, 2H, NCH2), 7.03 (s,
1H, ArCH=), 7.38–7.48 (m, 3H, H-3″, H-4″, H-5″), 7.71–
7.78 (m, 4H, H-3′, H-5′, H-2′, H-6″), 8.26 (d, J = 8.5 Hz, 2H,
H-2′, H-6′); IR m: 3027, 2935, 2850 (C–H), 1712 (C=O),
1631 (ArCH=), 1598, 1475, 1357, 1321, 1193, 1128, 836,
763, 692 cm–1. Anal. (C20H18N2OS) C, H, N.
5.1.3.31. Z-2-(2-Naphtylmethylene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (7a). Yield 35%;
yellow crystals, m.p. 166–168 °C (from dioxane); Rf 0.79
(A); 1H-NMR (250 MHz) d: 1.75–1.82 (m, 2H, SCH2CH2),
1.99–2.07 (m, 2H, NCH2CH2), 3.14–3.18 (m, 2H, SCH2),
3.74–3.78 (m, 2H, NCH2), 7.13 (s, 1H, ArCH=), 7.51–7.58
(m, 2H, H-6′, H-7′), 7.90–7.97 (m, 3H, H-4′, H-5′, H-8′),
8.48–8.55 (m, 2H, H-3′, H-1′); UV kmax (log e): 252 (4.21),
391 (4.43), 413 (4.32); IR m: 2924 (C–H), 1692 (C=O), 1614
(ArCH=), 1488, 1330, 1152, 1116, 928, 828, 748 cm–1.Anal.
(C18H16N2OS) C, H, N.
5.1.3.27. Z-2-(4-Benzyloxybenzylidene)-5,6,7,8-tetrahydro-
5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6ck). Yield
25%; lemon-yellow crystals, m.p. 158–160 °C (from meth-
ylene chloride + ethyl acetate); Rf 0.80 (A); 1H-NMR
(200 MHz) d: 1.76–1.80 (m, 2H, SCH2CH2), 1.98–2.08 (m,
2H, NCH2CH2), 3.08–3.14 (m, 2H, SCH2), 3.71–3.75 (m,
2H, NCH2), 5.17 (s, 2H, OCH2), 6.97 (s, 1H, ArCH=), 7.10
(d, J = 8.8 Hz, 2H, H-3′, H-5′), 7.36–7.45 (m, 5H, C6H5),
8.16 (d, J = 8.9 Hz, 2H, H-2′, H-6′); IR m: 2931 (C–H), 1698
(C=O), 1633 (ArCH=), 1594, 1490, 1247, 1174, 998, 833,
746, 698. Anal. (C21H20N2O2S) C, H, N.
5.1.3.32. 2-Cyclohexylidene-5,6,7,8-tetrahydro-5H-imidazo
[2,1-b][1,3]thiazepin-3(2H)-one (7b). Yield 22%; cream-
colored crystals, m.p. 152–154 °C (from ethanol); Rf 0.72
(A); 1H-NMR (CDCl3, 250 MHz) d: 1.59–1.82 (m, 8H, 3 ×
CH2, cyclohexyl, SCH2CH2), 2.05–2.17 (m, 2H, NCH2CH2),
2.75 (t, J = 5.8 Hz, 2H, H-2′), 2.90–2.95 (m, 2H, SCH2), 3.07
(t, J = 5.5 Hz, 2H, H-6′), 3.82 (def.t, J = 5.0 Hz, 2H, NCH2);
IR m: 2927, 2850 (C–H), 1691 (C=O), 1635 (C=), 1508,
1444, 1336, 1191, 1159, 964, 925 cm–1.Anal. (C13H18N2OS)
C, H, N.
5.1.3.28.
Z-2-(Cinnamylidene)-5,6,7,8-tetrahydro-5H-
imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6da). Yield 28%;
yellow crystals, m.p. 124–126 °C (from dioxane + water); Rf
0.75 (A); 1H-NMR (400 MHz) d: 1.75–1.78 (m, 2H,
SCH2CH2), 1.98–2.04 (m, 2H, NCH2CH2), 3.10–3.13 (m,
2H, SCH2), 3.65–3.73 (m, 2H, NCH2), 6.91 (d, J = 11.4 Hz,
1H, Ha), 7.27 (d, J = 15.8 Hz, 1H, Hb), 7.34–7.45 (m, 1H,
H-4′), 7.40 (d, J = 7.6 Hz, 2H, H-3′, H-5′), 7.49 (d,
J = 11.5 Hz, 1H, Hc), 7.62 (d, J = 7.2 Hz, 2H, H-2′, H-6′); UV
kmax (log e): 259 (3.38), 295 (3.50), 349 (3.63), 382 (3.85),
4.16 (4.00); IR m: 2927 (C–H), 1706 (C=O), 1620 (ArCH=),
1485, 1328, 1190, 1156, 975, 755; EI-MS: m/z (%): 284
(M+., 100); 255 (31); 229 (7); 185 (5); 155 (23); 142 (19);
115 (43); 72 (59); 55 (78). Anal. (C16H16N2OS) C, H, N.
5.2. Benzodiazepine binding assays
Frozen rat brains were obtained from Pel-Freez®, Rogers,
AR, USA. The cortex was dissected and inhibition of binding
of [3H]diazepam to rat brain cortical membranes was deter-
mined as previously described [18]. The compounds were
dissolved in dimethyl sulfoxide (DMSO), and the final
DMSO concentration in the assays was 1%. In a final volume
of 1 ml, each test tube contained 790 µl of Tris–HCl (tris(hy-
droxymethyl)aminomethane hydrochloride) buffer (50 mM,
pH 7.4), 10 µl of compound solution in DMSO, 100 µl of rat
cerebral cortical membrane preparation with a protein con-
centration of ca. 100 µg per tube, and 100 µl of [3H]diazepam
solution, to give a final concentration of 1 nM. DMSO was
necessary since the compounds possessed low water solubil-
ity.
Incubations were performed on an ice-bath for 1 h and
were terminated by rapid filtration through GF/B glass fiber
filters (Whatman, USA) using a Brandel 48-channel cell
harvester (Brandel, Gaithersburg, MD, USA). Three 5 ml
washes with ice-cold Tris–HCl buffer 50 mM, pH 7.4 were
performed. Unlabelled diazepam (5 µM) was used to define
5.1.3.29. Z-2-(Methylphenylmethylene)-5,6,7,8-tetrahydro-
5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-one (6db). Yield
12%; cream-rose-colored crystals, m.p. 90–94 °C (from di-
1
oxane + water then ethyl acetate); Rf 0.77 (A); H-NMR
(250 MHz) d: 1.73 (qui, J = 5.0 Hz, 2H, SCH2CH2), 1.95–
2.04 (m, 2H, NCH2CH2), 2.66 (s, 3H, CH3), 2.99–3.04 (m,
2H, SCH2), 3.70–3.74 (m, 2H, NCH2), 7.36–7.45 (m, 3H,
H-3′, H-4′, H-5′), 7.69–7.76 (m, 2H, H-2′, H-6′); IR m: 3054,
2944, 2915 (C–H), 1693 (C=O), 1610 (ArC=), 1492, 1232,
1213, 993, 850, 823, 676 cm–1.Anal. (C15H16N2OS) C, H, N.

K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
217
non-specific binding. All compounds were initially tested in
a single concentration of 25 µM (or 2.5 µM) in at least three
independent experiments each in triplicate. For selected
compounds, a full inhibition curve was determined in
4–5 separate experiments in triplicate. Ki values were calcu-
lated from IC50 values, determined by the non-linear regres-
sion program Prism version 3.0 (Graphpad, San Diego, CA,
USA), using the Cheng-Prusoff equation and a KD value of
4 nM for diazepam [19].
temperature factors for their parent-atoms. The refinement
for 6ae was finished at R = 0.0676, wR2 = 0.1496 (with
2
2
2
w = 1/[r2(Fo )+(0.0835P)2] where P = (Fo + 2Fc )/3 and
empirical extinction correction coefficient g = 0.0014(2),
S = 1.01 (182 parameters); Drqmin = –0.29 e A–3,
Dqmax = 0.37 e A–3. Corresponding data for 6ag were
2
R = 0.0672, wR2 = 0.1971 (with w = 1/[r2(Fo )+
0.1454P)2+1.1313P] where P = (Fo2 + 2Fc )/3 and empirical
2
extinction correction coefficient g = 0.0006(3), S = 1.02
(200 parameters); Dqmin = –0.51 e A–3, Dqmax = 0.98 e A–3.
The atomic scattering factors were taken from SHELXL-93
[38].
5.3. In vivo tests
Evaluation for anticonvulsant activity was performed in
male Carworth Farms no. 1 (CF 1) mice. Phase I of the
evaluation was qualitative assay which used small groups of
animals (1–8) and included three tests: maximal electroshock
(MES), subcutaneous pentylenetetrazole (ScMet) and ro-
torod test for neurological toxicity (Tox). Compounds were
suspended in 30% polyethylene glycol 400 and were admin-
istered by intraperitoneal injection at three dosage levels (30,
100 and 300 mg/kg) with anticonvulsant activity and neuro-
toxicity noted 30 min and 4 h after administration (according
to published procedure [23,24]).
5.5. Analytical chromatographic measurements
Analytical TLC was performed on 20 × 20 cm pre-coated
RP-TLC Al sheets of RP-18, F254S (E. Merck); samples of
2.5 µl of the solutes (0.1 mg/ml in acetonitrile) were spotted
with a Hamilton microliter syringe. The chromatograms
were developed over a distance of 9.5 cm. The chambers
were saturated with organic solvent vapour for 20 min. In the
performed studies the water–acetonitrile mixtures were used
as mobile phases. The concentration of the organic modifier
in a mobile phase ranged from 65% to 90%. All TLC mea-
surements were performed at 21 °C. Spots were visualised
under UV light at 254 nm.
5.4. X-ray diffraction analysis of Z-2-(2-methoxybenzylide-
ne)-5,6,7,8-tetrahydro-5H-imidazo[2,1-b][1,3]thiazepin-3
(2H)-one (6ae) and Z-2-(2-trifluoromethylbenzylidene)-
5,6,7,8-tetrahydro-5H-imidazo[2,1-b][1,3]thiazepin-3(2H)-
one (6ag)
5.6. Computational procedures
Crystals of 6ae and 6ag were obtained by slow evapora-
tion of dioxane solutions of the compounds. Preliminary
crystallographic data were obtained using a KM4 four-cycle
diffractometer; the accurate cell dimensions were deter-
mined by the least-squares refinement from the angular set-
tings of 25 reflections located within 10 < H < 40°.All crystal
data are collected in Table 1. The crystals (dimensions of
0.10 × 0.10 × 0.30 mm for 6ae and 0.2 × 0.2 × 0.4 mm for
6ag) were used to collect diffraction data on a KM4 diffrac-
tometer by the x/2H scan technique using graphite mono-
chromated CuKa radiation at room temperature. The data
were collected for 6ae in the range of H < 55° [h: -9/9, k:
0/13, l: 0/12] while for 6ag in the range of H < 80o [h: -12/12,
k: 0/17, l: 0/14]; an absorption correction was not applied; the
intensity of three standard reflections, monitored every
100 reflections, showed no significant fluctuations. For 6ae
1840 reflections were measured, 1745 reflections were con-
sidered to be observed using the criterion Fo > 4r(Fo), while
for 6ag these values were 3030 and 2866 reflections, respec-
tively. The structures were solved using a direct method
(SHELXTL-PC) [37]. E-map provided positions for all non-
H-atoms. The full-matrix least-squares refinement was car-
ried out on F2’s using anisotropic temperature factors for all
non-H-atoms. The H-atoms were located geometrically, then
the positions of H-atoms were refined in the riding model
with isotropic thermal parameters taken as 1.5 times the
The conformation analyses of 6ae (starting with the crys-
tallographically obtained geometry) were performed by mo-
lecular mechanics methods using the PCMOD.6 program
[39]. The energy was minimized after each 10° clockwise
rotation of one torsional angle in the 360° range. The geom-
etry of the molecules were optimized with MOPAC 6.0 using
AM1 Hamiltonians in an aqueous environment (dielectric
constants equals 78.4) [40]. The values of log P for the
compounds investigated were calculated by means of the
PALLAS (version 1.2) program [25]. Multiple Linear Re-
gression Equations were computed by means of the QSAR-
PC:PAR program written by R.C. Coburn [41].
Acknowledgements
This work was financially supported by a grant from the
Polish State Committee for Scientific Research, grant No
4 P05F 007 13. The authors wish to thank Professor James
Stables for providing pharmacological data through theAnti-
epileptic Drug Development Program, National Institutes of
Health in Bethesda, Maryland, USA. We thank Mrs. Maria
Kaleta for excellent technical assistance. C. E. Müller was
supported by the Fonds der Chemischen Industrie.

218
K. Kiec´-Kononowicz et al. / European Journal of Medicinal Chemistry 39 (2004) 205–218
[20] K. Kiec´-Kononowicz, A. Zatorski, J. Karolak-Wojciechowska, Phos-
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