Synthesis and biological evaluation of a novel series of 1,5-benzothiazepine derivatives as potential antimicrobial agents

Article abstract of DOI:10.1016/j.ejmech.2008.12.021

Two series of novel 1,5-benzothiazepine derivatives (23 compounds) were efficiently synthesized and evaluated for antibacterial and antifungal activities. The results indicated that the compounds possessed a broad spectrum of activity against the tested microorganisms and showed higher activity against fungi than bacteria. Compound 2e exhibited the greatest antimicrobial activity. Preliminary study of the structure-activity relationship revealed that substituents in phenyl rings had a great effect on the antimicrobial activity of these compounds.

Full text of DOI:10.1016/j.ejmech.2008.12.021

European Journal of Medicinal Chemistry 44 (2009) 2815–2821
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and biological evaluation of a novel series of 1,5-benzothiazepine
derivatives as potential antimicrobial agents
,
b,
**
Lanzhi Wang a, Ping Zhang a, Xuemei Zhang a, Yonghong Zhang b, Yuan Li a , Yongxiang Wang
*
a The College of Chemistry & Material Science, Hebei Normal University, Shijiazhuang 050016, PR China
b Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang 050017, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Two series of novel 1,5-benzothiazepine derivatives (23 compounds) were efficiently synthesized and
evaluated for antibacterial and antifungal activities. The results indicated that the compounds possessed
a broad spectrum of activity against the tested microorganisms and showed higher activity against fungi
than bacteria. Compound 2e exhibited the greatest antimicrobial activity. Preliminary study of the
structure–activity relationship revealed that substituents in phenyl rings had a great effect on the
antimicrobial activity of these compounds.
Received 31 August 2008
Received in revised form
11 November 2008
Accepted 15 December 2008
Available online 25 December 2008
Ó 2008 Published by Elsevier Masson SAS.
Keywords:
1,5-Benzothiazepine
Synthesis
Biological evaluation
Antimicrobial agent
1. Introduction
2. Results and discussion
Benzothiazepines play a unique role in drug discovery programs,
as they display a wide spectrum of biological activities such as
antibacterial [1], antifeedant [2], analgesic [3], anticonvulsant [4],
and calcium antagonism [5]. Therefore, their beneficial properties
have prompted several groups to study these compounds. We have
been interested in 1,5-benzothiazepine derivatives for a few years
and have prepared several series of 1,5-benzothiazepines. The
synthetic method has been developed and the spectroscopic prop-
erties of these compounds have been investigated. Recently, bio-
logical screening has shown that some compounds display excellent
antimicrobial activity. Encouraged by the results, two series of 1,5-
benzothiazepine derivatives (23 compounds) have been designed
and studied as potential antimicrobial agents. Here, we report the
synthesis, biological evaluation and preliminary structure–activity
relationships (SAR) of these new compounds whose structures are
shown in Fig. 1. The experimental results showed that most of the
compounds had good antimicrobial activity against Candida albi-
cans, Staphylococcus aureus and Staphylococcus epidermidis.
2.1. Chemistry
One of the most widely employed methods for the preparation
of 1,5-benzothiazepines involves the reaction of o-amino-
thiophenol with chalcones under acidic or basic conditions [6]. The
synthesis of compounds 1a–r was accomplished in three steps as
shown in Scheme 1. Knoevenagel condensation of aromatic alde-
hydes with 2,4-pentandione in dry benzene catalyzed by piperidine
gave compound 3. Then Michael addition of o-aminothiophenol to
compound 3 yielded the corresponding pentandione derivatives 4.
Finally, the intramolecular cyclisation of 4, followed by dehydration
in acetic acid/methanol provided compounds 1, which were puri-
fied by crystallization from dry methanol. To the best of our
knowledge, this is the first report of the synthesis of compounds 1.
The target compounds 2 (2,5-dihydro-2-aryl-3-ethoxycarbonyl-
4-methyl-1,5-benzothiazepines) were prepared by the same reac-
tion sequence as previously described (Scheme 2) [7]. It is worth
noting that when 4-hydroxybenzaldehyde was used as the starting
material, compound 2e was obtained as the final product, whose
structure had an unusual imine (–N]C–C–) rather than enamine
(–N–C]C–), as demonstrated by its 1H NMR spectrum. The 1H NMR
spectra of 2a–d showed the enamine methyl (–N–C]C–Me) group
at 2.60–2.65 ppm, the NH group at 6.19–6.23 ppm and S–CH group
at the C-2 position as a singlet at 5.89–6.14 ppm. However, in 1H
NMR spectra of 2e, the imine methyl (–N]C–Me) group went up
Abbreviations: SAR, structure–activity relationships; TLC, thin-layer chroma-
tography; rt, room temperature.
* Corresponding author. Tel.: þ86 311 86268321; fax: þ86 311 86269217.
** Corresponding author.
E-mail address: yuanli@mail.hebtu.edu.cn (Y. Li).
0223-5234/$ – see front matter Ó 2008 Published by Elsevier Masson SAS.
doi:10.1016/j.ejmech.2008.12.021

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L. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 2815–2821
Monitoring the cyclization progress of compounds 4 and 6 by 1H
R
NMR spectroscopy, it was revealed that imines were initially
formed and gradually transformed to enamines, except for the
formation of 2e. However, we have no detailed knowledge of these
reactions, and ongoing work in our laboratory is attempting to
selectively prepare enamines or imines by optimizing reaction
conditions, and to reveal whether the tautomeric equilibrium was
involved in the present study.
1
S
9
2
8
3
Y
4
CH3
X
7
N
H
5
6
2.2. Biological activity
1a-r
2a-d
In the present study, all the synthesized compounds 1 and 2
were tested against microbial strains such as C. albicans (ATCC
10231), S. aureus (ATCC 25923), S. epidermidis (ATCC 26069) and
Escherichia coli (ATCC 44752) using disk diffusion methods. Fluco-
nazole was used as a standard drug against fungi and vancomycin
against bacteria. For the purpose of easier visualization, the zone
date from these assays indicates the average diameter (from 3
trails) of the growth inhibition zones. The margin of error of these
measurements is ꢀ1 mm. The antibacterial activity was classified
as highly active (>14 mm), moderately active (10–14 mm), slightly
active (6–10 mm) and less than 6 mm was regarded as inactive. The
results of our antibacterial and antifungal studies of all the
synthesized compounds are depicted in Tables 1 and 2. From Tables
1 and 2, it can be observed that compounds 1 exhibited better
activity than compounds 2, with the exception of 2e. These results
indicated that the acetyl group at C-3 was required for enhancing
antimicrobial activity. Compounds 1 and 2e exhibited higher anti-
fungal activity against C. albicans than antibacterial activity against
S. aureus, S. epidermidis and E. coli. The results indicated that the
compounds seemed to have higher sensitivity for fungi than
bacteria. It was also found that none of the compounds tested
inhibited the growth of E. coli, even at highest tested dose of
1a-j: X=H, Y=COCH
2a-d: X=H, Y=COOCH CH
2 3
3
1a :R= p-N O
1b: R= o-N O
1c :R= p-Cl
1d: R= o-Cl
2a: R=p-C H
2
2
3
2b: R=p-F
2c: R= p-NO
2d: R= o-C l
2
R
1e:R= p-C H
1f: R= p-OH
1g: R=H
3
1
S
9
8
2
1h: R= p-OCH
3
3
Y
1i: R= p-F
4
X
7
N
5
1j: R=2,4-dichloro
6
CH3
1k-r: X=Cl,Y=COCH
3
1k: R=p-NO
1l: R= o-N O
1m: R=p-C l
1n: R=o-C l
1o: R= H
2
2
2e: X=H , Y=COOCH2CH3 , R= p-OH
1p: R= p-F
1q: R= p-Br
1r: R= 2,4-dichloro
200
mg/disc. Among the tested compounds, compounds 1c, 1e and
2e showed significant activity, and the others showed moderate
activity.
Fig. 1. Structures of compounds 1 and 2.
Table 2 gives the inhibition zone data for compounds 2.
Although most of the compounds did not show antifungal and
antibacterial activity, compound 2e showed good biological activity
against bacteria S. aureus (inhibition zone 18 mm) and S. epi-
dermidis (inhibition zone 20 mm) and fungus C. albicans (inhibition
field at 2.29 ppm, the NH signal disappeared, the S–CH group at the
C-2 position appeared as doublets at 5.20–5.23 (J ¼ 9.2 Hz) and the
CH group at the C-3 position in the seven-membered ring of ben-
zothiazepine appeared as doublets at 3.70–3.72 ppm (J ¼ 9.2 Hz),
owing to their vicinal coupling.
zone 30 mm) at 200 mg/disc. This suggests that compound 2e is the
most potent compound among all those synthesized in the present
O
O
R
R
C
CH3
CH3
piperidine
C
H
C
C
CH3
CH3
CHO
C
H2C
+
C6H6, 2.0h, reflux
C
O
O
3
R
R
O
H2N
S
HS
X
O
C
S
CH
C
CH3
CH3
HOAc
CH3
CH
C
CH3OH, 1h, rt
X
pH=3-4
NH2
N
H
X
CH3
O
4
1
Scheme 1. Synthesis of benzothiazepines 1a–r.

L. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 2815–2821
2817
O
O
R
R
C
OC2H5
CH3
C
OC2H5
CH3
piperidine
C
C
CHO
H2C
H
C
+
C
C6H6, 2.0h, reflux
O
O
R
R
O
5
H2N
S
O
C
HS
X
X
HOAc
S
CH
C
OC2H5
CH3
OC2H5
CH
pH=3-4
C
CH3 OH, 1h, rt
X
NH2
N
H
CH3
O
2a-d
OH
6
+
S
O
C
OC2H5
N
CH3
2e
Scheme 2. Synthesis of benzothiazepines 2a–e.
study, and the imine structure (–N]C–C–) seems to play an
important role in the antimicrobial activity. Another reason for
stronger antimicrobial activity of 2e may be the improved solubility
of the compound in agar, mediated by the hydroxyl group in the
molecule. A similar result was reported by Seefeld and co-workers
[8].
Substitution at the C-2 position of compounds 1a–r showed that
the antimicrobial activity changed with the position of the
substituents on the phenyl ring at the C-2 position and with the
variety of peripheral substituents on the phenyl ring in the same
pattern of benzothiazepines. For example, compounds 1a and 1c,
with para-substituents (p-NO2, p-Cl), exhibited higher
antimicrobial activity than compounds 1b and 1d, with the same
ortho-substituents (o-NO2, o-Cl). The results indicated that para-
substituents on the C-2 aryl ring increased the inhibitory effect of
the compounds. Analysis of the SAR in compounds 1a–i also
revealed that replacement of H by R on the C-2 aryl ring enhanced
antimicrobial activity with the exception of compound 1h. The
introduction of p-Cl groups to the C-2 aryl ring caused a marked
increase in antimicrobial activity. Comparison of biological activity
showed that compounds 1c and d exhibited higher antifungal
activity against C. albicans than 1j, which suggested that the multi-
chlorine substituents on the C-2 aryl ring of compounds 1 were
unfavorable for enhancing antifungal activity.
Table 1
Antimicrobial activity of compounds 1.
Compd
X
R
Dose (
m
g/disc)
100
200
50
200
100
50
200
100
50
200
100
50
Zone of inhibitiona (mm)
C. albicans
S. aureus
S. epidermidis
E. coli
1a
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n
1o
1p
1q
1r
H
H
H
H
H
H
H
H
H
H
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
p-NO2
o-NO2
p-Cl
20
16
24
15
23
17
10
11
20
14
14
–
13
15
13
10
15
–
18
13
21
15
16
17
7
16
11
18
12
16
15
–
8
18
9
9
–
10
10
7
13
12
15
9
10
10
11
10
10
10
11
8
10
11
10
9
11
10
12
11
14
8
9
9.5
8
7
9
7
7
7
7.5
8
7
9
10
8
12
8
7
7
6.5
6.5
7
7
7
7
7
7
7
8
9
–
13
10
19
9
12
9
17
10
7
17
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
o-Cl
7.5
7.5
p-CH3
p-OH
H
p-OCH3
p-F
2,4-Dichlo-rine
p-NO2
o-NO2
p-Cl
o-Cl
H
p-F
p-Br
7
7
11
7
7
11
8
11
8
7.5
7
8
8
7
11
–
–
10
7
10
7
7
7
7
12
10
10
11
11
11
8
10
10
11
8
9
20
10
11
–
11
12
9
9
11
–
8
10
–
7
9
–
10
7
11
–
10
–
2,4-Dichlorine
a
The values indicate the average diameters in mm (of three trials) for the zone of growth inhibition observed after 24 h of incubation at 37 ꢁC. Inhibition zones of standard
drugs: Fluconazole, 23 mm against C. albicans at 25
within ꢀ1 mm.
mg/disc, vancomycin: 18, 18, and 8 mm against S. aureus, S. epidermidis and E. coli at 30 mg/disc, respectively. Error values are

2818
L. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 2815–2821
Table 2
Antimicrobial activity of compounds 2.
Compd
X
R
Dose (
m
g/disc)
100
200
50
200
100
50
200
100
50
200
100
50
Zone of inhibitiona (mm)
C. albicans
S. aureus
S. epidermidis
E. coli
2a
2b
2c
2d
2e
H
H
H
H
H
p-CH3
p-F
p-NO2
o-Cl
–
–
7.0
–
30
–
–
6.5
–
24
–
–
–
–
–
–
7.0
–
18
–
–
6.5
–
15
–
–
–
–
7
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
p-OH
14
20
16
10
a
The values indicate the average diameters in mm (of three trials) for the zone of growth inhibition observed after 24 h of incubation at 37 ꢁC. Inhibition zones of standard
drugs: Fluconazole, 23 mm against C. albicans at 25
within ꢀ1 mm.
mg/disc, vancomycin: 18, 18, and 8 mm against S. aureus, S. epidermidis and E. coli at 30 mg/disc, respectively. Error values are
Finally, we noted that the substitution at the C-7 position of
compounds 1 also had an effect on the biological activity. The C-7
chloro-substituted analogues 1k–r were less active than
compounds 1a–j, respectively. The result showed that the chlorine
substituent at the C-7 position on the benzothiazepine ring was
unfavorable for improving antimicrobial activity.
In order to explore the biological activity of 1,5-benzothiaze-
pines and identify promising lead compounds, 1c and 2e, with
remarkable activity in the present study, were selected to investi-
gate the effect of dose levels on antimicrobial activity. Figs. 2 and 3
show the relationship between compound activity and dose level.
The zones of inhibition values suggested the antimicrobial activities
of compounds (benzothiazepine) 1c and 2e at a broad range from
results showed that most of the compounds exhibited moderate to
good activity against C. albicans, S. epidermidis and S. aureus and
displayed their antimicrobial capacity in the order C. albicans > S.
epidermidis > S. aureus > E. coli. Three compounds, 1c, 1e and 2e,
have significant antimicrobial properties. Thus, the promising
activities and easy access of benzothiazepine derivatives render
them as very attractive antimicrobial leads. The extensive study of
the SAR of this series of compounds will provide information for the
design and development of new antimicrobial drugs based on 1,5-
benzothiazepine derivatives. Further detailed SAR studies are the
subject of future studies and will be reported in due course.
4. Experimental
12.5 to 200 mg/disc against C. albicans, S. aureus and S. epidermidis.
It was also observed that the antimicrobial activity was dose-
related and declined with decreasing dose level. The compound
exhibited inactivity at doses <12.5 mg/disc. From Figs. 2 and 3, it
was also found that the antimicrobial capacity for the above
microorganisms was in the order C. albicans > S. epidermidis > S
aureus > E. coli. The same tendency was also observed for most of
the compounds in our present study.
Melting points (ꢁC) were determined in a PXT-4 digital melting
point apparatus and elemental analysis was performed on a Vario
ELIII Elemental Analyzer. The IR spectra (in KBr pellets) were
recorded on a PE-M-1730 IR spectrophotometer. 1H NMR spectra
were recorded on a Bruker ARX spectrometer; chemical shifts (d)
are reported in ppm using SiMe4 as the internal standard when
measured in CDCl3 or DMSO-d6. Signal multiplicities are repre-
sented by s (singlet), d (doublet), t (triplet), m (multiplet), and q
(quartet). Low-resolution mass spectra were recorded on a Micro-
mass ZAC-HS mass spectrometer. The substituted benzaldehyde
and o-aminothiophenol were purchased from Sigma–Aldrich, and
the other chemicals were used as commercial products of analytical
3. Conclusion
In conclusion, two series of novel 1,5-benzothiazepine deriva-
tives were synthesized and their biological activities evaluated. The
32
30
28
26
24
22
20
18
16
14
12
10
8
26
C. albicans
C. albicans
24
22
20
18
16
14
12
10
8
S. epidermidis
S aureus
S. epidermidis
S aureus
6
6
4
2
0
4
2
0
-2
-2
0
50
compound dose levels (µg/disc)
100
150
200
0
50
compound dose levels (µg/disc)
100
150
200
Fig. 2. Inhibition zones at different dose levels for compound 1c.
Fig. 3. Inhibition zones at different dose levels for compound 2e.

L. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 2815–2821
2819
grade. Solvents were dried and purified according to the literature
when necessary. Reactions were monitored by thin-layer chroma-
tography (TLC) on pre-coated silica gel GF254 plates.
(400 MHz, CDCl3), d (ppm): 6.51–7.30 (8H, m, –C6H4), 6.39 (1H, s,
NH), 5.86 (1H, s, SCH), 2.57 (3H, s, –CO–CH3), 2.14 (3H, s, –CH3).
4.1.3.5. 2,5-Dihydro-4-methyl-2-(4-methylphenyl)-3-acetyl-1,5-be-
nzothiazepine (1e). Yield 47%; mp 139 ꢁC; MS [M þ Hþ]: 310;
C19H19NOS: found: C, 73.62; H, 6.31; N, 4.39; Calcd: C, 73.75; H,
4.1. General method for the synthesis of 2,5-dihydro-4-methyl-2-
aryl-3-acetyl-1,5-benzothiazepine (1a–r)
6.19; N, 4.4.53; IR KBr (
(400 MHz, CDCl3), (ppm): 6.69–7.49 (8H, m, –C6H4), 6.51 (1H, s,
n
cmꢂ1) 1724 (C]O), 1635 (C]C); 1H NMR
d
4.1.1. Synthesis of 3-benzylidene-2,4-pentandione (3)
NH), 5.62 (1H, s, SCH), 2.55 (3H, s, –CO–CH3), 2.17 (3H, s, –CH3), 2.01
(3H, s, PhCH3–).
2,4-Pentandione (15.3 mL, 0.15 mol) and piperidine (0.9 mL)
were dissolved in 150 mL dry benzene. Then substituted benzal-
dehyde (0.15 mol) was added dropwise at room temperature over
20 min. The reaction mixture was slowly brought to boil and
refluxed for 2 h with stirring (TLC monitoring). After cooling, the
organic layer was washed with cold aqueous 10% sodium
carbonate, water and aqueous 5% acetic acid. Then, the organic
layer was dried and evaporated under reduced pressure and the
crude product was purified by crystallization from ether.
4.1.3.6. 2,5-Dihydro-4-methyl-2-(4-hydroxylphenyl)-3-acetyl-1,5-be-
nzothiazepine (1f). Yield 31%; mp 177 ꢁC; MS [M þ Hþ]: 312;
C18H17NO2S: found: C, 69.31; H, 5.62; N, 4.36; Calcd: C, 69.43; H,
5.50; N, 4.50; IR KBr (
(400 MHz, CDCl3), (ppm): 6.64–7.53 (8H, m, –C6H4), 6.39 (1H, s,
n
cmꢂ1) 1697 (C]O), 1635 (C]C); 1H NMR
d
NH), 5.69 (1H, s, SCH), 5.36 (1H, s, OH), 2.29 (3H, s, –COCH3), 1.87
(3H, s, –CH3).
4.1.2. Synthesis of 3-(1-aryl-1-o-aminophenylthio methyl)-2,4-
pentandione (4)
4.1.3.7. 2,5-Dihydro-4-methyl-2-phenyl-3-acetyl-1,5-benzothiaze-
pine (1g). Yield 49%; mp 167 ꢁC; MS [M þ Hþ]: 295; C18H17NOS:
found: C, 73.31; H, 5.70; N, 4.82; Calcd: C, 73.22; H, 5.76; N, 4.75; IR
A mixture of 3-benzylidene-2,4-pentandione (3) (25 mmol) and
o-aminothiophenol (3.1 g, 25 mmol) in dry methanol (50 mL) was
stirred at room temperature for 1 h. The reaction mixture
was concentrated under reduced pressure, cooled, and the solid
was collected by filtration, washed with water and cold methanol.
The crude products were purified by crystallization from the
appropriate solvent.
KBr (
(ppm): 6.70–7.28 (9H, m, –C6H4,–C6H5), 6.41 (1H, s, NH), 5.69
n
cmꢂ1) 1708 (C]O), 1636 (C]C); 1H NMR (400 MHz, CDCl3),
d
(1H, s, SCH), 2.59 (3H, s, –COCH3), 2.20 (3H, s, –CH3).
4.1.3.8. 2,5-Dihydro-4-methyl-2-(4-methoxylphenyl)-3-acetyþl-1,5-be-
nzothiazepine (1h). Yield 44%; mp 107 ꢁC; MS [M þ H ]: 326;
C19H19NO2S: found: C, 70.31; H, 5.70; N, 4.42; Calcd: C, 70.15; H,
4.1.3. Synthesis of 2,5-dihydro-4-methyl-2-aryl-3-acetyl-1,5-ben-
zothiazepine (1a–r)
5.85; N, 4.31; IR KBr (
(400 MHz, CDCl3), (ppm): 6.49–7.28 (8H, m, –C6H4), 5.63 (1H, s,
n
cmꢂ1) 1713 (C]O), 1634 (C]C); 1H NMR
d
To a solution of 3-(1-aryl-1-o-aminophenylthio methyl)-2,4-
pentandione (4) (20 mol) in dry methanol (30 mL), acetic acid was
added until it reached pH 4, and the mixture was stirred at room
temperature for 12 h. The precipitate was collected by filtration,
washed well with cold methanol, and crystallized from methanol.
The overall yield and characterization (Mp, IR, NMR, MS and
elementary analysis data) of 2,5-dihydro-4-methyl-2-aryl-3-
acetyl-1,5-benzothiazepine (1a–r) were as follows:
NH), 3.67 (3H, s, –OCH3), 3.48 (1H, s, SCH), 2.56 (3H, s, –COCH3),
2.19 (3H, s, –CH3).
4.1.3.9. 2,5-Dihydro-4-methyl-2-(4-flurorophenyl)-3-acetylþ-1,5-be-
nzothiazepine (1i). Yield 39%; mp 117 ꢁC; MS [M þ H ]: 314;
C18H16FNOS: found: C, 69.12; H, 5.05; N, 4.52; Calcd: C, 69.01;
H, 5.11; N, 4.47; IR KBr (
NMR (400 MHz, CDCl3),
n
cmꢂ1) 1710 (C]O), 1635 (C]C); 1H
(ppm): 6.74–7.07 (8H, m, –C6H4), 6.25
d
(1H, s, NH), 5.65 (1H, s, SCH), 2.56 (3H, s, –CO–CH3), 2.18 (3H, s,
–CH3).
4.1.3.1. 2,5-Dihydro-4-methyl-2-(4-nitrophenyl)-3-acetyl-1,5-be-
nzothiazepine (1a). Yield 32%; mp 161 ꢁC; MS [M þ Hþ]: 341;
C18H16N2O3S, found: C, 63.40; H, 4.87; N, 8.10; Calcd: C, 63.51; H,
4.1.3.10. 2,5-Dihydro-4-methyl-2-(2,4-dichlorophenyl)-3-acetyl-1,
5-benzothiazepine (1j). Yield 37%; mp 145 ꢁC; MS [M þ Hþ]: 364;
C18H15Cl2NOS: found: C, 59.31; H, 4.02; N, 3.90; Calcd: C, 59.34; H,
4.74; N, 8.23; IR KBr (
(400 MHz, CDCl3), (ppm): 7.13–8.36 (8H, m, –C6H4), 6.33 (1H, s,
n
cmꢂ1) 1712 (C]O), 1635 (C]C); 1H NMR
d
NH), 5.60 (1H, s, SCH), 2.29 (3H, s, –CO–CH3), 1.93 (3H, s, –CH3).
4.12; N, 3.85; IR KBr (
(400 MHz, CDCl3), (ppm): 6.41–7.31 (7H, m, –C6H4, –C6H3), 5.79
n
cmꢂ1) 1712 (C]O), 1600 (C]C); 1H NMR
d
4.1.3.2. 2,5-Dihydro-4-methyl-2-(2-nitrophenyl)-3-acetyl-1,5-ben-
zothiazepine (1b). Yield 31%; mp 127 ꢁC; MS [M þ Hþ]: 341;
C18H16N2O3S: found: C, 63.40; H, 4.87; N, 8.10; Calcd: C, 63.51; H,
(1H, s, NH), 3.48 (1H, s, SCH), 2.57 (3H, s, –CO–CH3), 2.12 (3H, s,
–CH3).
4.74; N, 8.23; IR KBr (
n
cmꢂ1) 1718 (C]O), 1635 (C]C); 1H NMR
4.1.3.11. 7-Chloro-2,5-dihydro-4-methyl-2-(4-nitrophenyl)-3-aceþ-
tyl-1,5-benzothiazepine (1k). Yield 30%; mp 161 ꢁC; MS [M þ H ]:
376; C18H15N2ClO3S: found: C, 57.52; H, 4.07; N, 5.70; Calcd: C,
(400 MHz, CDCl3), (ppm): 7.13–8.36 (8H, m, –C6H4), 6.20 (1H, s,
d
NH), 5.81 (1H, s, SCH), 2.32 (3H, s, –CO–CH3), 2.00 (3H, s,–CH3).
57.60; H, 4.00; N, 5.76; IR KBr (
NMR (400 MHz, CDCl3), (ppm): 7.13–8.36 (7H, m, –C6H4, –C6H3),
n
cmꢂ1) 1715 (C]O), 1643 (C]C); 1H
4.1.3.3. 2,5-Dihydro-4-methyl-2-(4-chlorophenyl)-3-acetylþ-1,5-be-
nzothiazepine (1c). Yield 42%; mp 117 ꢁC; MS [M þ H ]: 330;
C18H16ClNOS: found: C, 65.42; H, 5.01; N, 4.14; Calcd: C, 65.54; H,
d
6.25 (1H, s, NH), 5.60 (1H, s, SCH), 2.29 (3H, s, –CO–CH3), 1.93 (3H, s,
–CH3).
4.89; N, 4.25; IR KBr (
(400 MHz, CDCl3), (ppm): 6.74–7.07 (8H, m, –C6H4), 6.29 (1H, s,
n
cmꢂ1) 1708 (C]O), 1635 (C]C); 1H NMR
d
4.1.3.12. 7-Chloro-2,5-dihydro-4-methyl-2-(2-nitrophenyl)-3-aceþ-
tyl-1,5-benzothiazepine (1l). Yield 30%; mp 167 ꢁC; MS [M þ H ]:
376; C18H15N2ClO3S: found: C, 57.52; H, 4.07; N, 5.70; Calcd: C,
NH), 5.63 (1H, s, SCH), 2.56 (3H, s, –CO–CH3), 2.18 (3H, s, –CH3).
4.1.3.4. 2,5-Dihydro-4-methyl-2-(2-chlorophenyl)-3-acetyl-þ1,5-be-
nzothiazepine (1d). Yield 40%; mp 149 ꢁC; MS [M þ H ]: 330;
C18H16ClNOS: found: C, 65.42; H, 5.01; N, 4.14; Calcd: C, 65.54; H,
57.60; H, 4.00; N, 5.76; IR KBr (
NMR (400 MHz, CDCl3), (ppm): 6.67–7.74 (7H, m, –C6H4, –C6H3),
n
cmꢂ1) 1662 (C]O), 1624 (C]C); 1H
d
6.57 (1H, s, NH), 6.22 (1H, s, SCH), 2.57 (3H, s, –CO–CH3), 2.27 (3H, s,
–CH3).
4.89; N, 4.25; IR KBr (n
cmꢂ1) 1701 (C]O), 1637 (C]C); 1H NMR

2820
L. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 2815–2821
4.1.3.13. 7-Chloro-2,5-dihydro-4-methyl-2-(4-chlorophenyl)-3-aceþ-
tyl-1,5-benzothiazepine (1m). Yield 29%; mp 139 ꢁC; MS [M þ H ]:
364; C18H15Cl2NOS: found: C, 59.31; H, 4.02; N, 3.90; Calcd: C,
4.2.2. 2,5-Dihydro-4-methyl-2-(4-flurorophenyl)-3-
ethoxycarbonyl-1,5-benzothiazepine (2b)
Yield 23%; mp 136 ꢁC; MS [M þ Hþ]: 430; C19H18FNO2S: found:
59.34; H, 4.12; N, 3.85; IR KBr (
NMR (400 MHz, CDCl3), (ppm): 6.72–7.26 (7H, m, –C6H4, –C6H3),
n
cmꢂ1) 1716 (C]O), 1553 (C]C); 1H
C, 66.32; H, 5.40; N, 3.97; Calcd: C, 66.45; H, 5.28; N, 3.4.08; IR KBr
d
(n
cmꢂ1) 1735 (C]O), 1620 (C]C); 1H NMR (400 MHz, CDCl3),
6.17 (1H, s, NH), 5.59 (1H, s, SCH), 2.52 (3H, s, –CO–CH3), 2.18 (3H, s,
–CH3).
d
(ppm): 6.68–7.05 (8H, m, –C6H4,), 6.25 (1H, s, NH), 5.89 (1H, s,
SCH), 4.01–4.13 (2H, q, J ¼ 5.8 Hz, –COOCH2), 2.60 (3H, s, –C]C–
CH3), 1.16–1.19 (3H, t, J ¼ 5.8 Hz, –CH2CH3).
4.1.3.14. 7-Chloro-2,5-dihydro-4-methyl-2-(2-chlorophenyl)-3-aceþ-
tyl-1,5-benzothiazepine (1n). Yield 29%; mp 134 ꢁC; MS [M þ H ]:
364; C18H15Cl2NOS: found: C, 59.31; H, 4.02; N, 3.90; Calcd: C,
4.2.3. 2,5-Dihydro-4-methyl-2-(4-nitrophenyl)-3-ethoxycarbonyl-
1,5-benzothiazepine (2c)
59.34; H, 4.12; N, 3.85; IR KBr (
n
cmꢂ1) 1716 (C]O), 1553 (C]C); 1H
Yield 20%; mp 152 ꢁC; MS [M þ Hþ]: 371; C19H18N2O4S: found: C,
NMR (400 MHz, CDCl3), (ppm): 6.53–7.32 (7H, m, –C6H4, –C6H3),
d
61.48; H, 4.79; N, 7.53; Calcd: C, 61.62; H, 4.87; N, 7.57; IR KBr (n
6.47 (1H, s, NH), 5.82 (1H, s, SCH), 2.54 (3H, s, –CO–CH3), 2.14 (3H, s,
–CH3).
cmꢂ1) 1715 (C]O), 1635 (C]C); 1H NMR (400 MHz, CDCl3),
(ppm): 6.72–7.89 (8H, m, –C6H4), 6.33 (1H, s, NH), 5.96 (1H, s,
d
SCH) , 4.04–4.12 (2H, q, J ¼ 5.6 Hz, –COOCH2), 2.65 (3H, s, –C]C–
4.1.3.15. 7-Chloro-2,5-dihydro-4-methyl-2-phenyl-3-acetylþ-1,5-be-
nzothiazepine (1o). Yield 32%; mp 171 ꢁC; MS [M þ H ]: 330;
C18H16ClNOS: found: C, 73.31; H, 5.70; N, 4.82; Calcd: C, 73.22; H,
CH3), 1.16–1.19 (3H, t, J ¼ 5.6 Hz, –CH2CH3).
4.2.4. 2,5-Dihydro-4-methyl-2-(2-chlorophenyl)-ethoxycarbonyl-
1,5-benzothiazepine (2d)
5.76; N, 4.75; IR KBr (
(400 MHz, CDCl3), (ppm): 6.53–7.32 (8H, m, –C6H5, –C6H3), 6.38
n
cmꢂ1) 1708 (C]O), 1543 (C]C); 1H NMR
d
Yield 23%; mp 135 ꢁC; MS [M þ Hþ]: 361; C19H18ClNO2S:
found: C, 63.24; H, 5.06; N, 3.82; Calcd: C, 63.33; H, 5.00; N,
(1H, s, NH), 5.82 (1H, s, SCH), 2.54 (3H, s, –COCH3), 2.14 (3H, s,
–CH3).
3.89; IR KBr
(400 MHz, CDCl3),
(n )
cmꢂ1 1715 (C]O), 1635 (C]C); 1H NMR
d
(ppm): 6.50–7.28 (8H, m, –C6H4), 6.29 (1H,
4.1.3.16. 7-Chloro-2,5-dihydro-4-methyl-2-(4-flurorophenyl)-3-aceþ-
tyl-1,5-benzothiazepine (1p). Yield 35%; mp 158 ꢁC; MS [M þ H ]:
349; C18H15ClFNOS: found: C, 62.12; H, 4.29; N, 4.07; Calcd: C, 62.07;
s, NH), 6.14 (1H, s, SCH), 3.96–4.08 (2H, q, J ¼ 5.6 Hz,
–COOCH2), 2.63 (3H, s, –C]C–CH3), 1.13–1.16 (3H, t, J ¼ 5.6 Hz,
–CH2CH3).
H, 4.31; N, 4.02; IR KBr (
(400 MHz, CDCl3), (ppm): 6.71–7.06 (7H, m, –C6H4, –C6H3),
n
cmꢂ1) 1695 (C]O), 1639 (C]C); 1H NMR
d
4.2.5. 2,3-Dihydro-4-methyl-2-(4-hydroxylpheny)-3-
ethoxycarbonyl-1,5-benzothiazepine (þ2e)
6.15 (1H, s, NH), 5.61 (1H, s, SCH), 2.53 (3H, s, –CO–CH3), 2.19
(3H, s, –CH3).
Yield 20%; mp 161 ꢁC; MS [M þ H ]: 342; C19H19NO3S: found: C,
66.72; H, 5.75; N, 3.98; Calcd: C, 66.86; H, 5.57; N, 4.10; IR KBr (
n
4.1.3.17. 7-Chloro-2,5-dihydro-4-methyl-2-(4-bromophenyl)-3-ace-
tyl-1,5-benzothiazepine (1q). Yield 33%; mp 156 ꢁC; MS [M þ Hþ]:
410; C18H15ClBrNOS: found: C, 52.78; H, 3.60; N, 3.38; Calcd: C,
cmꢂ1) 1718 (C]O), 1637 (C]N); 1H NMR (400 MHz, DMSO-d6),
d
(ppm): 6.63–7.52 (8H, m, –C6H4), 5.20–5.23 (1H, d, J ¼ 9.2 Hz
SCH), 4.04 (1H, s, –OH), 3.90–3.92 (2H, q, J ¼ 5.8 Hz, –COOCH2),
3.70–3.72 (1H, d, J ¼ 9.2 Hz, CH–COO), 2.29 (3H, s, –N]C–CH3),
0.96–0.99 (3H, t, J ¼ 5.8 Hz, –CH2CH3).
52.81; H, 3.67; N, 3.42; IR KBr (
NMR (400 MHz, CDCl3), (ppm): 6.74–7.07 (7H, m, –C6H4, –C6H3),
n
cmꢂ1) 1718 (C]O), 1639 (C]C); 1H
d
6.29 (1H, s, NH), 5.63 (1H, s, SCH), 2.56 (3H, s, –CO–CH3), 2.18
(3H, s, –CH3).
4.3. Biological evaluation
4.1.3.18. 7-Chloro-2,5-dihydro-4-methyl-2-(2,4-dichlorophenyl)-3-
acetyl-1,5-benzothiazepine (1r). Yield 27%; mp 152 ꢁC; MS
[M þ Hþ]: 398; C18H14Cl3NOS: found: C, 54.31; H, 3.56; N, 3.40;
Assay of antimicrobial activity in vitro. The synthesized
compounds were tested for their antimicrobial (antibacterial and
antifungal) activities by standardized disk diffusion methods. The
assayed collection included the following microorganisms: C. albi-
cans (ATCC 10231), S. aureus (ATCC 25923), S. epidermidis (ATCC
26069) and E. coli. (ATCC 44752).
Calcd: C, 54.20; H, 3.51; N, 3.51; IR KBr (n
cmꢂ1) 1715 (C]O), 1543
(C]C); 1H NMR (400 MHz, CDCl3),
d (ppm): 6.47–7.33 (6H, m,
–C6H3), 6.17 (1H, s, NH), 5.76 (1H, s, SCH), 2.53 (3H, s, –CO–CH3),
2.13 (3H, s, –CH3).
In the disc-diffusion method, sterile paper discs (
impregnated with compounds dissolved in DMSO at concentra-
tions of 12.5, 50, 100 and 200 g/disc were used. Discs containing
F 6 mm)
4.2. Synthesis of 2,5/2,3-dihydro-4-methyl-2-aryl-3-
ethoxycarbonyl-1,5-benzothiazepine (2a–e)
m
DMSO were used as controls. Paper discs impregnated with
a solution of the compound tested were placed on the surface of the
media inoculated with the microorganisms. The plates were incu-
bated at 37 ꢁC for 24 h for culture of microorganisms. After incu-
bation, the growth inhibition zones around the discs were
observed, which indicated that the examined compound inhibited
the growth of microorganisms. Each assay in this experiment was
repeated three times.
The procedure for the synthesis of 2 was repeated in Section 4.1.
Compounds 2 were obtained in a similar manner to that used for
compounds 1, by replacing reactant 2,4-pentandione with ethyl
acetoacetate. The products were crystallized from methanol.
4.2.1. 2,5-Dihydro-4-methyl-2-(4-methylphenyl)-3-
ethoxycarbonyl-1,5-benzothiazepine (2a)
Yield 33%; mp 155 ꢁC; MS [M þ Hþ]: 340; C20H21NO2S:
found: C, 63.28; H, 5.16; N, 3.76; Calcd: C, 63.41; H, 5.04; N,
Acknowledgments
3.89; IR KBr
(400 MHz, CDCl3),
(n )
cmꢂ1 1730 (C]O), 1632 (C]C); 1H NMR
d
(ppm): 6.71–7.26 (8H, m, –C6H4,), 6.19 (1H,
We are indebted to the National Natural Science Foundation of
China (No. 20772021) and the Natural Science Foundation of Hebei
Province, China (No. 2007000239) for financial support of this
work.
s, NH), 5.89 (1H, s, SCH), 4.01–4.13 (2H, q, J ¼ 5.8 Hz, –COOCH2),
2.61 (3H, s, –C]C–CH3), 2.16 (3H, s, –PhCH3), 1.17–1.23 (3H, t,
J ¼ 5.8 Hz, –CH2CH3).

L. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 2815–2821
2821
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I. Alkortac, J. Elguero, Tetrahedron 61 (2005) 6642–6651.
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