Synthesis and antimicrobial evaluation of some new 1,2-bis-(2-(N-arylimino) -1,3-thiazolidin-3-yl)ethane derivatives

Article abstract of DOI:10.1248/cpb.c14-00031

N, N′-Diarylethylene-bis-thiourea derivatives 1 and 8 were synthesized and their reactions with hydrazonoyl chlorides yielded the corresponding bis-(2-(N-arylimino)-1,3-thiazolidine derivatives 5a-d and 11a-c. The reaction of compound 1 with several α-hal

Full text of DOI:10.1248/cpb.c14-00031

May 2014
Regular Article
Chem. Pharm. Bull. 62(5) 439–445 (2014)
439
Synthesis and Antimicrobial Evaluation of Some New 1,2-Bis-
(2-(N-arylimino)-1,3-thiazolidin-3-yl)ethane Derivatives
Kamal Mohamed Dawood* and Hussein Khalaf-Allah Abu-Deif
Department of Chemistry, Faculty of Science, University of Cairo; Giza 12613, Egypt.
Received January 12, 2014; accepted February 23, 2014
N,Nꢀ-Diarylethylene-bis-thiourea derivatives 1 and 8 were synthesized and their reactions with hydra-
zonoyl chlorides yielded the corresponding bis-(2-(N-arylimino)-1,3-thiazolidine derivatives 5a–d and 11a–c.
The reaction of compound 1 with several α-haloketones afforded the bis-(5-methyl-2-(N-phenylimino)-1,3-
thiazolidine derivatives 15a–c and 19a,b. The newly synthesized compounds were tested for their antimi-
crobial activity against four fungi, two Gram-positive and two Gram-negative bacteria and showed high
antibacterial and antifungal activities against all the test microorganisms except Pseudomonas aeruginosa
and Candida albicans. Compounds 5b, 15b and 19a exhibited the highest activities against the test microor-
ganisms. The MIC evaluation showed that compound 15b has higher activity than Amphotericin B and Am-
picillin against all tested fungi and Gram-positive bacteria (Staphylococcus pneumonia) and showed similar
activity like Ampicillin against Gram-negative bacteria (Escherichia coli).
Key words bis-thiourea; hydrazonoyl chloride; 1,3-thiazolidine; antibacterial; antifungal activity
Thiourea derivatives are important building blocks in the by elimination of two aniline molecules to give the bis-1,3,4-
synthesis of various heterocycles such as 2-aminothiazoles,1) thiadiazolidine structure 7. Elemental and spectral analyses
iminothiazolines,2) thiohydantoins,3) 1,3,5-triazines,4) and were consistent with the bis-1,3-thiazolidine structures 5a–d.
1
2-amino-oxazolidines.5) Thiourea derivatives have also re- The H-NMR spectrum of 5d displayed three singlet signals
cently proved to be useful substances in drug research.6–10) resonating at δ 2.91, 3.88, 4.93 due to -Me, -OMe and -NCH2
They are reported to have anti-human immunodeficiency protons, respectively, in addition to the aromatic multiplets in
virus (HIV),11) antiviral,12) vanilloid receptor antagonism,13) the region δ 7.0–7.8. In addition, the 13C-NMR spectrum of 5d
antibacterial,14) anticancer,15) and anti-allergic16) activities. showed 14 peaks. The IR spectrum was free of any carbonyl
In addition, bis-thiourea derivatives are used as powerful absorption and its mass spectrum exhibited, among other
organocatalysts in asymmetric organic reactions.17–21) Fur- fragments, two ion peaks at m/z 674 (M+) and 337 (M+/2). Ap-
thermore, thiazolidine derivatives are known to have anti- pearance of only 14 peaks (half number of expected carbons)
microbial,22) antitubercular,23) anticancer,24,25) anti-inflam- in the 13C-NMR spectrum of 5d in addition to the M+/2 value
mtory,26) anticonvulsant27) and antiviral/anti-HIV28,29) activ- at m/z 337, in its MS, supported the structure elucidation.
ities. Bis-thiazolidin-4-one derivatives also demonstrated anti-
Next, N,N′-dibenzylethylene-bis-thiourea (8) was prepared
inflammatory/analgesic activities together with better gastro- following the reported procedure in literature.41) Reaction of
intestinal safety profile than known non-steroidal anti-inflam- N,N′-dibenzylethylene-bis-thiourea 8 with 2eq of the hydra-
matory drugs (NSAIDs)30) and antioxidant31) as well as anti- zonoyl chlorides 2a–c under the same reaction conditions as
proliferative32) activities. In continuation of our research work above afforded the corresponding 1,2-bis-(5-arylazo-2-(N-
directed towards synthesis of heterocycles with broad biologi- benzylimino)-4-methyl-1,3-thiazolidin-3-yl)ethane derivatives
cal activities,33–39) we report here the synthesis of several new 11a–c as shown in Chart 2 via a mechanism similar to that
bis-thiazolidine derivatives to evaluate their antibacterial and in Chart 1. Elemental analysis and spectral data of the reac-
antifungal activities.
tion product were in agreement with the assigned structures.
For example, the mass spectrum of compound 11c showed,
beside further fragments, two characteristic fragments at m/z
Results and Discussion
Chemistry N,N′-Diphenylethylene-bis-thiourea (1) was 670 and 335 corresponding to its (M+) and (M+/2), respec-
prepared following the reported procedure.40) Then, treatment tively. In addition, the IR spectrum of compound 11c showed
of the bis-thiourea 1 with two equivalents of hydrazonoyl ha- the absence of any NH or carbonyl absorptions. Furthermore,
lides 2 in refluxing ethanol in the presence of triethylamine the H- and 13C-NMR spectra showed the presence of four
1
yielded only one isolable product for which the bis-1,3-thia- sp3 protonated-carbons at δ 2.34, 2.59, 4.24 and 4.41 (in the
zolidine 5 or the bis-1,3,4-thiadiazolidine 7 derivatives can be 1H-NMR) and their corresponding carbon peaks at δ 12.09,
assigned (Chart 1). Mechanistically, the reaction proceeds as 20.64, 43.3, 58.0 (in the 13C-NMR).
depicted in Chart 1, where the appropriate hydrazonoyl chlo-
Next, when N,N′-diphenylethylene-bis-thiourea 1 was al-
ride reacts with the thiol tautomer 1A losing HCl. After that, lowed to react with phenacyl bromide (12a) (in 1:2 molar
two possible routes for ring closing nucleophilic reaction; (i) ratio) in refluxing ethanol in the presence of triethylamine, it
attack of aniline-NH to the acetyl-C=O to give the intermedi- resulted in the formation of a compound that was confirmed
ate 4 followed by elimination of two water molecules to give as 1,2-bis-(2-phenylimino-4-phenyl-1,3-thiazolidin-3-yl)ethane
the bis-1,3-thiazolidine structure 5, (ii) attack of hydrazone- (15a) (Chart 3) on the basis of its elemental and spectral
1
NH to the imine-C=N to give the intermediate 6 followed analyses. The H-NMR spectrum of compound 15a revealed
two singlets resonating at δ 4.1 and 6.04 corresponding to
NCH2 and thiazole-5-CH protons, respectively. Its mass
The authors declare no conflict of interest.
© 2014 The Pharmaceutical Society of Japan
*To whom correspondence should be addressed. e-mail: dr_dawood@yahoo.com

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Vol. 62, No. 5
Chart 1. Synthesis of Bis-1,3-thiazolidine Derivatives 5a–d
Chart 2. Synthesis of Bis-(2-(N-benzylimino)-1,3-thiazolidine Derivatives 11a–c
spectrum showed ion peaks at m/z 530 and 265 assignable ing ethanol in the presence of triethylamine afforded a single
to (M+) and (M+/2), respectively. Similarly, reaction of the product that was elucidated, from the spectral data of the
bis-thiourea 1 with 3-(bromoacetyl)coumarin-2-one 12b and pure product, as 1,2-bis-[5-acetyl-4-methyl-2-(phenylimino)-
1
with 3-(bromoacetyl)benzofuran 12c under the same experi- thiazolidin-3-yl]ethane (19a) (Chart 4). The H-NMR spectrum
mental conditions above gave the corresponding 1,2-bis-(2- of 19a displayed three singlet signals resonating at δ 2.04,
phenylimino-1,3-thiazolidin-3-yl)ethane derivatives 15b and 3.29, 4.19 due to 4-Me, 5-COMe and NCH2 protons, respec-
15c, respectively, in high yields as shown in Chart 3.
tively, in addition to the aromatic multiplets signals. Its mass
In a similar manner, treatment of N,N′-diphenylethylene- spectrum exhibited the molecular ion peak at m/z 490 (M+).
bis-thiourea 1 with 3-chloropentane-2,4-dione (16a) in reflux- Formation of 19a proceeded via intramolecular cyclization

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441
Chart 3. Synthesis of Bis-(5-aryl-2-(N-phenylimino)-1,3-thiazolidine Derivatives 15a–c
Chart 4. Synthesis of Bis-(5-methyl-2-(N-phenylimino)-1,3-thiazolidine Derivatives 19a,b
with loss of water from the intermediate 18a. The bis-thiourea The inhibition zones of compounds 5a–d, 11a–c, 15a–c
1 reacted similarly with ethyl 2-chloro-3-oxobutanoate (16b) and 19a,b ranged from 10.6–26.1mm against A. fumigatus,
to give only one isolable product via elimination of water S. racemosum, G. candidum, compared with Amphotericin
from the intermediate 18b. All spectral data (IR, MS and B. Compounds 5d, 15b and 19a showed the highest inhibi-
1H-NMR) were in complete accordance with structure 19b tion zones 20.3, 25.9 and 22.3mm, respectively against A.
(see Experimental section).
fumigates compared with 23.7mm of Amphotericin B. In-
Antimicrobial Activity All synthesized compounds were terestingly, compounds 5b, 15b and 19a were more potent
tested for their antifungal and antibacterial activities. The an- antifungal than the reference drug, showing higher inhibi-
timicrobial activities were compared with the reference drugs: tion zones 21.6, 26.1 and 20.3mm, respectively against S.
Amphotericin B, Ampicillin and Gentamicin and the results racemosum than Amphotericin B (19.7mm). Furthermore,
are outlined in Tables 1 and 2. The obtained results showed compounds 5b, 5d, 15b and 19a were very potent antifungal
that the synthesized compounds exhibited variable degrees of against G. candidum with inhibition zones 21.3, 24.6, 29.2 and
inhibition against the tested microorganisms. Susceptibilities 25.8mm, respectively comparing with 28.7mm of Amphoteri-
of the fungal and bacterial isolates to the synthesized thiazoli- cin B. However, all the tested compounds 5a–d, 11a–c, 15a–c
dine derivatives were examined by measuring their inhibitory and 19a,b were completely inactive against C. albicans. It is
effect on the growth of microorganisms compared to the sol- noteworthy to mention that, compound 15b proved to be the
vent used.
most potent inhibitor against the three fungi (A. fumigatus,
Antifungal Activity The results of antifungal testing of S. racemosum, G. candidum) and in all cases it was superior
1,2-bis-(2-(arylimino)-1,3-thiazolidin-3-yl)ethane derivatives over Amphotericin B as shown in Table 1. It is interesting also
5a–d, 11a–c, 15a–c and 19a,b against the fungi (Aspergillus to point out that among the 5-arylazo derivatives 5a–d and
fumigatus, Syncephalastrum racemosum, Geotricum can- 11a–c, the 4-chloro-and 4-methoxy-substituted compounds 5b
didum, Candida albicans) are reported in Table 1, in com- and 5d are mostly endowed with higher activity with respect
parison with those of the reference drug; Amphotericin B. to unsubstituted phenyl derivative 5a, against all tested micro-

442
Vol. 62, No. 5
organisms. In addition, the inhibitory activity N-phenylimino- when compared with Gentamicin). However, all the tested
derivatives 5 are in general more active than their N-benzyl- compounds 5a–d, 11a–c, 15b,c and 19b (except 15a and 19a)
imino-analogs 11. Further, the presence of coumarinyl moiety were inactive against the Gram-negative bacteria; P. aerugi-
in the bi-thiazolidine derivative 15b extraordinarily promoted nosa (Table 2). Thus, only compounds 15a and 19a showed
the inhibitory activity against all active fungi when compared inhibitory activity against the four tested Gram-negative and
with its bi-thiazolidine analogs bearing phenyl or benzofura- Gram-positive bacteria (S. pneumonia, B. subtilis, P. aerugi-
nyl moieties 15a and 15c, respectively. Similarly, the presence nosa, E. coli) as shown in Table 2. Compounds 5b, 5d, 15a,
of acetyl group in compound 19a greatly increased its antifun- 15b and 19a showed the most potent effects against the Gram-
gal activity comparing with the ester analog 19b against all positive (S. pneumonia and B. subtilis) bacteria when com-
the tested microorganisms.
pared with Ampicillin (Table 2). Interestingly, compounds 15b
Antibacterial Activity Similarly, the antibacterial activity and 19a were more active than Ampicillin drug against the
of 1,2-bis-(2-(arylimino)-1,3-thiazolidin-3-yl)ethane derivatives Gram-positive bacteria S. pneumonia. Also, compound 15b
5a–d, 11a–c, 15a–c and 19a,b against Gram-positive (Strep- showed effects close to Ampicillin against the Gram-positive
tococcus pneumonia, Bacillis subtilis) and Gram-negative bacteria B. subtilis. Furthermore, compound 15b was found
(Pseudomonas aeruginosa, Escherichia coli) bacteria were to be more active than Gentamicin against the Gram-negative
evaluated as outlined in Table 2. The results were compared bacteria E. coli.
with antibacterial activity of two reference drugs; Ampicillin
Minimum Inhibitory Concentration (MIC) The MIC
and Gentamicin. All the tested compounds 5a–d, 11a–c, 15a– of the synthesized compounds 5a,b,d, 15a,b and 19a
c and 19a,b demonstrated high inhibition against the tested against the highly inhibited organisms is reported in Table
Gram-positive microorganisms (S. pneumonia and B. subtilis) 3. Most of the tested compounds for MIC demonstrated an
(inhibition zones varied from 11.0–30.2mm when compared excellent antimicrobial activity against A. fumigates (MICs
with Ampicillin), and against the Gram-negative P. aerugi- 0.03–31.25µg/mL), S. racemosum (MICs 0.03–3.9µg/mL), G.
nosa bacteria (inhibition zones varied from 10.2–20.3mm candidum (MICs 0.007–1.95µg/mL), S. pneumonia (MICs
Table 1. In Vitro Antifungal Activity of 1,2-Bis-(2-(arylimino)-1,3-thia- Table 2. In Vitro Anti-bacterial Activity of 1,2-Bis-(2-(arylimino)-1,3-
zolidin-3-yl)ethane Derivatives 5a–d, 11a–c, 15a–c and 19a,b
thiazolidin-3-yl)ethane Derivatives 5a–d, 11a–c, 15a–c and 19a,b
Inhibition zone [mm]a)
Inhibition zone [mm]a)
Compound
Compound
Aspergillus Syncephalastrum Geotricum Candida
S. pneumoniae B. subtilis P. aeruginosa
E. coli
fumigatus
racemosum
candidum albicans
5a
5b
17.3 0.63
20.0 0.43
14.6 0.43
20.3 0.44
16.4 0.58
11.0 0.58
13.6 0.58
20.6 0.63
25.9 0.25
16.2 0.15
25.1 0.44
18.9 0.44
23.8 0.2
—
20.2 0.44
21.4 0.53
16.2 0.53
25.6 0.63
18.2 0.63
12.2 0.44
14.0 0.25
22.4 0.44
30.3 0.63
19.8 0.42
29.8 0.58
20.3 0.58
32.4 0.3
—
NA
NA
15.9 0.37
16.3 0.33
13.7 0.25
16.9 0.25
12.4 0.44
NA
5a
5b
16.3 0.44
18.3 0.34
12.6 0.58
20.3 0.39
15.3 0.58
12.4 0.37
13.9 0.58
17.8 0.63
25.9 0.25
15.7 0.33
22.3 0.25
16.3 0.44
18.6 0.58
21.1 0.25
13.6 0.25
21.6 0.16
13.2 0.63
10.6 0.58
12.0 0.44
18.9 0.44
26.1 0.44
15.9 0.25
20.3 0.25
18.4 0.58
19.7 0.2
19.8 0.25
21.3 0.38
15.2 0.38
24.6 0.58
16.1 0.25
11.3 0.44
14.0 0.37
20.3 0.25
29.2 0.63
16.8 0.34
25.8 0.58
19.1 0.37
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
5c
NA
5c
5d
NA
5d
11a
NA
11a
11b
11c
15a
15b
15c
19a
19b
11b
NA
11c
NA
10.2 0.36
16.9 0.58
20.3 0.44
15.3 0.53
19.6 0.19
18.9 0.63
—
15a
NA
15b
12.6 0.44
NA
15c
19a
11.2 0.58
NA
19b
Ampicillin
Gentamicin
—
Amphotericin B 23.7 0.1
28.7 0.2 25.4 0.1
17.3 0.1
19.9 0.3
a) NA: No activity, data are expressed in the form of mean S.D.
a) NA: No activity, data are expressed in the form of mean S.D.
Table 3. Minimum Inhibitory Concentrations (MIC) of Compounds 5a,b,d, 15a,b and 19a
MIC (µg/mL)
Microorganism
Standard
5a
5b
5d
15a
15b
19a
Fungi
Amphotericin B
0.12
A. fumigatus
31.25
3.9
3.9
1.95
0.49
0.06
7.8
0.03
0.03
0.007
0.49
3.9
S. racemosum
G. candidum
Gram-positive bacteria
S. pneumoniae
B. subtilis
0.98
0.98
3.9
1.95
1.95
1.95
0.03
0.015
Ampicillin
0.12
15.63
1.95
1.95
0.98
1.95
0.06
0.98
0.49
0.03
0.12
0.003
0.007
0.003
Gram-negative bacteria
P. aeruginosa
E. coli
Gentamicin
15.63
—
—
—
—
250
1.95
500
1.95
31.25
31.25
15.63
15.63
1.95

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443
0.03–15.63µg/mL), B. subtilis (MICs 0.003–1.95µg/mL) and (DMF) to afford the corresponding 1,2-bis-(1,3-thiazolidin-3-
E. coli (MICs 1.95–31.25 µg/mL) as shown in Table 3. For- yl)ethane derivatives 5a–d. The physical properties and spec-
tunately, the novel 1,2-bis-(2-arylimino-1,3-thiazolidin-3-yl)- tral data of the obtained products are listed below.
ethane derivative 15b exhibited higher activity (MIC’s 0.03,
1,2-Bis-(5-phenylazo-2-(N-phenylimino)-4-methyl-1,3-
0.03, 0.007µg/mL, respectively) than Amphotericin B (MIC’s thiazolidin-3-yl)ethane (5a): Orange-red solid; Yield=(0.44g,
1
0.12, 1.95, 0.015µg/mL, respectively) against all tested fungi; 72%); mp: 246–248°C; H-NMR (DMSO-d6) δ: 3.01 (6H, s),
A. fumigatus, S. racemosum and G. candidum, respectively, 4.97 (4H, s), 6.97–7.05 (4H, m), 7.27–7.57 (16H, m); IR (KBr)
as shown in Table 3. Similarly, compound 15b demonstrated cm−1: 3055, 2946, 1613, 1582; MS (m/z (%)): 614 (M+, 14.3),
also higher activity (MIC 0.03µg/mL) than Ampicillin (MIC 613 (M+−1, 43), 268 (43), 135 (50), 129 (36), 103 (64), 77
0.12 µg/mL) against Gram-positive bacteria S. pneumonia. (100), 59 (79). Anal. Calcd for C34H30N8S2: C, 66.42; H, 4.92;
Also, compound 19a showed similar activity (MIC 0.003µg/ N, 18.32; S, 10.43. Found: C, 66.23; H, 4.88; N, 18.05; S, 10.39.
mL) like Ampicillin (MIC 0.003µg/mL) against Gram-positive
1,2-Bis-(5-(4-chlorophenylazo)-2-(N-phenylimino)-4-
bacteria B. subtilis. In addition, compounds 15b and 19a methyl-1,3-thiazolidin-3-yl)ethane (5b): Orange-red solid;
1
showed similar activities (MICs 1.95µg/mL) like Ampicillin Yield=(0.51g, 75%); mp 240–242°C; H-NMR (DMSO-d6) δ:
(MIC 1.95µg/mL) against Gram negative bacteria E. coli as 2.95 (6H, s), 4.95 (4H, s), 7.05 (4H, d, J=8.03Hz), 7.26–7.34
shown in Table 3.
(10H, m), 7.53 (4H, d, J=8.03Hz); IR (KBr) cm−1: 3059,
3005, 2944, 2829, 1582; MS (m/z (%)): 685 (M++2, 2.1), 684
(M++1, 4), 683 (M+, 16), 355 (27), 342 (M+/2, 2.9), 328 (23),
Conclusion
In summary, the newly synthesized symmetrical 1,2-bis- 230 (19), 127 (100), 77 (98), 68 (87), 51 (44). Anal. Calcd for
(2-(arylimino)-1,3-thiazolidin-3-yl)ethane derivatives were C34H28Cl2N8S2: C, 59.73; H, 4.13; N, 16.39; S, 9.38. Found: C,
characterized by spectral data and then tested for their anti- 59.55; H, 4.11; N, 16.58; S, 9.27.
microbial activity against four fungi (A. fumigatus, S. race-
1,2-Bis-(5-(4-tolylazo)-2-(N-phenylimino)-4-methyl-1,3-
mosum, G. candidum, C. albicans) and two Gram-positive thiazolidin-3-yl)ethane (5c): Red solid; Yield=(0.5g, 78%); mp
1
(S. pneumonia, B. subtilis) as well as two Gram-negative (P. 254–256°C; H-NMR (DMSO-d6) δ: 2.33 (6H, s), 2.77 (6H,
aeruginosa, E. coli) bacteria. All the synthesized compounds s), 4.59 (4H, s), 6.86 (4H, d, J=8.1Hz), 6.99–7.01 (2H, m),
5a–d, 11a–c, 15a–c and 19a,b showed high antibacterial and 7.17–7.26 (8H, m), 7.51 (4H, d, J=8.1Hz); 13C-NMR (DMSO-
antifungal activities against all the test microorganisms ex- d6) δ: 17.9, 21.5, 45.8, 77.5, 112.5, 122.5, 124.4, 125.5, 128.8,
cept P. aeruginosa and C. albicans. Compounds 5b, 15b and 129.9, 130.3, 133.3, 148.5, 167.1; IR (KBr) cm−1: 3019, 2946,
19a showed the highest antifungal and antibacterial activities 2912, 1608, 1580; MS (m/z (%)): 644 (M++2, 4.3), 643 (M++1,
against the test microorganisms. In addition, the MIC of the 9.5), 642 (M+, 21.3), 334 (49.2), 321 (M+/2, 3.3), 309 (10.3),
highly active compounds was also evaluated. It was found that 106 (80), 77 (68.7), 68 (100). Anal. Calcd for C36H34N8S2: C,
compound 15b showed higher activity than Amphotericin B 67.26; H, 5.33; N, 17.43; S, 9.98. Found: C, 67.41; H, 5.31; N,
and Ampicillin against all tested fungi and Gram-positive bac- 17.22; S, 9.88.
teria (S. pneumonia) and showed similar activity like Ampicil-
lin against Gram-negative bacteria (E. coli).
1,2-Bis-(5-(4-anisylazo)-2-(N-phenylimino)-4-methyl-1,3-
thiazolidin-3-yl)ethane (5d): Orange-red solid; Yield=(0.55g,
1
82%); mp 249–251°C; H-NMR (DMSO-d6) δ: 2.91 (6H, s),
3.88 (6H, s), 4.93 (4H, s), 6.98–7.07 (8H, m), 7.28–7.31 (6H,
Experimental
Chemistry General: All melting points were measured on m), 7.65 (4H, d, J=9.12Hz); 13C-NMR (DMSO-d6) δ: 10.7,
a Gallenkamp electrothermal melting point apparatus. The in- 53.4, 54.5, 76.4, 114.0, 114.9, 120.9, 123.4, 124.5, 125.2, 129.9,
frared (IR) spectra were recorded for potassium bromide pel- 134.7, 148.5, 167.6; IR (KBr) cm−1: 3053, 2948, 1613, 1582;
lets on a Pye Unicam SP 3–300 and FT IR 8101 PC Shimadzu MS (m/z (%)): 674 (M+, 8.7), 673 (16.4), 552 (16.4), 350 (27.4),
infrared spectrophotometers. The H- and 13C-NMR spectra 337 (M+/2, 4.6), 230 (31.5), 135 (45.2), 122 (77.2), 108 (65.3),
1
were recorded in dimethylsulfoxide-d6 (DMSO-d6) as the 80 (45.7), 77 (100). Anal. Calcd for C36H34N8O2S2: C, 64.07; H,
solvent at 300MHz on Varian Mercury NMR spectrometer. 5.08; N, 16.60; S, 9.50. Found: C, 63.84; H, 5.00; N, 16.34; S,
Mass spectra were recorded at 70eV on a GCMS–QP 1000 9.45.
EX Shimadzu mass spectrometer. Elemental analyses were
Synthesis of 1,2-Bis-(5-arylazo-2-(N-benzylimino)-4-meth-
carried out at the Microanalytical Center of Cairo Univer- yl-1,3-thiazolidin-3-yl)ethane Derivatives 11a–c General
sity. The antimicrobial activity was performed at the Regional Procedure: To a mixture of bis-thiourea derivative 8 (1mmol,
Center for Mycology and Biotechnology (Al-Azhar University, 0.358g) and the appropriate acetyl hydrazonoyl chlorides 2a–c
Nasr City, Cairo, Egypt). Hydrazonoyl chlorides 242,43) and (2mmol) in absolute ethanol (10mL), triethylamine (0.1mL) was
α-bromoketones 12a,44) 12b,45) and 12c46) were prepared ac- added and the resulting mixture was refluxed for 6–8h, then left
cording to procedures reported in the literature.
to cool to room temperature. The solid product so formed was
Synthesis of 1,2-Bis-(5-arylazo-2-(N-phenylimino)-4- collected by filtration, washed with ethanol, dried and finally
methyl-1,3-thiazolidin-3-yl)ethane Derivatives 5a–d Gen- recrystallized from DMF to afford the corresponding 1,2-bis-(2-
eral Procedure: To a mixture of bis-thiourea derivative 1 (N-benzylimino)-1,3-thiazolidin-3-yl)ethane derivatives 11a–c.
(1mmol, 0.33g), and the appropriate hydrazonoyl chlorides The physical properties and spectral data of the obtained prod-
2a–d (2mmol) in absolute ethanol (10mL), triethylamine ucts are listed below.
(0.1mL) was added and the resulting mixture was refluxed for
1,2-Bis-(5-phenylazo-2-(N-benzylimino)-4-methyl-1,3-
6–8h, then left to cool to room temperature. The solid product thiazolidin-3-yl)ethane (11a): Reddish brown powder; Yield=
1
so formed was collected by filtration, washed with ethanol, (0.44g, 68%); mp 229–221°C; H-NMR (DMSO-d6) δ: 2.62
dried and finally recrystallized from N,N-dimethylsulfoxide (6H, s), 4.24 (4H, s), 4.43 (4H, s), 7.22–7.45 (16H, m), 7.61–7.64

444
Vol. 62, No. 5
(4H, m); 13C-NMR (DMSO-d6) δ: 12.1, 30.8, 35.8, 121.6, 126.4,
1,2-Bis-[4-(benzofuran-3-yl)-2-(phenylimino)-1,3-
127.4, 128.1, 129.2, 129.6, 139.5, 147.9, 151.5, 154.9, 162.2; IR thiazolidin-3-yl]ethane (15c): Pale yellow solid; Yield=(0.35g,
1
(KBr) cm−1: 3016, 2949, 2841, 1618, 1572 (C=C); MS (m/z 58%); mp 289–291°C; H-NMR (DMSO-d6) δ: 4.54 (4H, s),
(%)): 643 (M++1, 1.2), 642 (M+, 2.5), 441 (3.0), 334 (5.8), 321 6.65 (2H, s), 6.67–6.71 (4H, m), 6.95–7.06 (2H, m), 7.20–7.33
(M+/2, 0.5), 308 (5.1), 244 (5.1), 180 (14.1), 148 (5.8), 118 (5.1), (14H, m); IR (KBr) cm−1: 3063, 2938, 1610, 1576; MS (m/z
93 (59.8), 91 (100), 77 (42.6), 66 (29.4), 51 (23). Anal. Calcd (%)): 610 (M+, 5.8), 319 (71.6), 318 (64.2), 317 (100), 305
for C36H34N8S2: C, 67.26; H, 5.33; N, 17.43; S, 9.98. Found: C, (M+/2, 5.3), 292 (22.6), 183 (14.8), 174 (13.6), 142 (13.6), 102
67.42; H, 5.26; N, 17.19; S, 9.77.
(14.8), 77 (28), 51 (15.6). Anal. Calcd for C36H26N4O2S2: C,
1,2-Bis-(5-(4-chlorophenylazo)-2-(N-benzylimino)-4- 70.80; H, 4.29; N, 9.17; S, 10.50. Found: C, 70.67; H, 4.25; N,
methyl-1,3-thiazolidin-3-yl)ethane (11b): Orange red solid; 9.06; S, 10.42.
Yield=(0.46g, 65%); mp 237–239°C; 1H-NMR (DMSO-d6)
1,2-Bis-[5-acetyl- 4-methyl-2-(phenylimino)-1,3-
δ: 2.62 (6H, s), 4.21 (4H, s), 4.44 (4H, s), 7.17–7.31 (10H, thiazolidin-3-yl]ethane (19a): Reddish-yellow solid; Yield=
1
m), 7.47–7.50 (4H, d, J=8.7Hz), 7.6–7.63 (4H, d, J=8.7Hz); (0.31g, 64%); mp 175–176°C; H-NMR (DMSO-d6) δ: 2.04
MS (m/z (%)): 713 (M++2, 0.4), 712 (M++1, 0.6), 711 (M+, (6H, s), 3.29 (6H, s), 4.19 (4H, s), 6.95–7.01 (5H, m), 7.27–7.33
0.4), 214 (14.4), 152 (4.7), 127 (67.1), 113 (7.1), 92 (24.1), 91 (5H, m); IR (KBr) cm−1: 3106, 2910, 1637, 1615, 1572; MS
(100), 77 (13.2), 75 (15), 65 (39.6), 50 (13.9). Anal. Calcd for (m/z (%)): 490 (M+, 12.4), 448 (2.7), 405 (1.6), 257 (20.2), 217
C36H32Cl2N8S2: C, 60.75; H, 4.53; N, 15.74; S, 9.01. Found: C, (40.5), 216 (65.1), 215 (100), 114 (10.2), 77 (27.1), 68 (27.2),
60.45; H, 4.51; N, 15.66; S, 8.89.
1,2-Bis-(5-(4-tolylazo)-2-(N-benzylimino)-4-methyl-1,3- 11.42; S, 13.07. Found: C, 63.34; H, 5.24; N, 11.17; S, 13.23.
thiazolidin-3-yl)ethane (11c): Orange red solid; Yield=(0.42g, 1,2-Bis-[5-ethoxycarbonyl-4-methyl-2-(phenylimino)-1,3-
51 (9.2). Anal. Calcd for C26H26N4O2S2: C, 63.65; H, 5.34; N,
1
62%); mp 230–231°C; H-NMR (DMSO-d6) δ: 2.34 (6H, s), thiazolidin-3-yl]ethane (19b): Pale yellow solid; Yield=(0.42g,
2.59 (6H, s), 4.24 (4H, s), 4.41 (4H, s), 7.19–7.34 (14H, m), 77%); mp 214–216°C; 1H-NMR (DMSO-d6) δ: 1.6 (6H, t,
7.54 (4H, d, J=8.1Hz); 13C-NMR (DMSO-d6) δ: 12.09, 20.64, J=7.2Hz), 2.60 (6H, s), 4.06–4.13 (4H, q, J=6Hz), 4.39 (4H,
43.3, 58.0, 121.3, 123.7, 128.8, 129.1, 131.1, 134.5, 146.6, 148.7, s), 6.85–6.88 (4H, m), 7.01–7.04 (2H, m), 7.26–7.31 (4H, m);
152.1, 161.3, 165.6; IR (KBr) cm−1: 3022, 2911, 1616; MS (m/z IR (KBr) cm−1: 3054, 2990, 2956, 2900, 1702, 1613, 1584; MS
(%)): 670 (M+, 2.0), 453 (1.0), 349 (3.4), 335 (M+/2, 0.8), 322 (m/z (%)): 550 (M+, 4.5), 505 (2.4), 458 (1.9), 288 (77.8), 287
(10.6), 258 (3.2), 149 (4.4), 106 (69.4), 91 (100), 77 (19.1), 65 (100), 275 (M+/2, 0.5), 259 (19.6), 77 (16.1), 68 (29.9). Anal.
(21.8), 51 (14.9). Anal. Calcd for C38H38N8S2: C, 68.03; H, 5.71; Calcd for C28H30N4O4S2: C, 61.07; H, 5.49; N, 10.17; S, 11.65.
N, 16.70; S, 9.56. Found: C, 68.03; H, 5.71; N, 16.70; S, 9.56.
Found: C, 60.85; H, 5.40; N, 10.03; S, 11.54.
Synthesis of 1,2-Bis-[4-aryl-2-(phenylimino)-1,3-thia-
Biological Activity. Antimicrobial Activity Antimi-
zolidin-3-yl]ethane 15a–c General Procedure: To a mixture crobial activity was determined using the agar well diffusion
of bis-thiourea derivative 1 (1mmol, 0.33g), and the appro- assay method as described by Holder and Boyce.47) The tested
priate α-halo ketone derivative (2mmol) in absolute ethanol organisms were sub-cultured on nutrient agar medium (Oxoid
(10mL), triethylamine (0.1mL) was added and the resulting Laboratories, U.K.) for bacteria and Saboroud dextrose agar
mixture was refluxed for 4–6h, then left to cool to room (Oxoid Laboratories, U.K.) for fungi. Penicillin G and Strep-
temperature. The solid product so formed was collected by tomycin were used as a positive control for bacterial strains.
filtration, washed with ethanol, dried and finally recrystal- Amphotericin B was used as a positive control for fungi. The
lized from DMF to afford the corresponding 1,2-bis-[4-aryl-2- plates were done in triplicate. Bacterial cultures were incu-
(phenylimino)-1,3-thiazolidin-3-yl]ethane derivatives 15a–c. bated at 37°C for 24h while the other fungal cultures were
The physical properties and spectral data of the obtained prod- incubated at (25–30°C) for 3–7d. Antimicrobial activity was
ucts are listed below.
determined by measurement zone of inhibition.48)
1,2-Bis-[4-phenyl-2-(phenylimino)-1,3-thiazolidin-3-yl]-
Determination of MIC The MIC of the synthesized sam-
ethane (15a): Off-white solid; Yield=(0.42g, 80%); mp ples was estimated for each of the tested organisms in tripli-
1
234–236°C; H-NMR (DMSO-d6) δ: 4.10 (4H, s), 6.04 (2H, cates. Varying concentrations of the samples (1000–0.007µg/
s), 6.71–6.74 (4H, m), 6.96–6.99 (4H, m), 7.23–7.46 (12H, m); mL), nutrient broth were added and then a loopful of the test
IR (KBr) cm−1: 3097, 3052, 3020, 2955, 1616, 1579; MS (m/z organism previously diluted to 0.5 McFarland turbidity stan-
(%)): 531 (M++1, 1.5), 530 (M+, 3), 278 (64.8), 277 (100), dard was introduced to the tubes. A tube containing broth
276 (58), 265 (M+/2, 3.1), 252 (11.2), 176 (5.9), 104 (34.8), 91 media only was seeded with the test organisms to serve as
(41.8), 89 (13.6), 77 (60.9), 76 (15.9), 51 (23.2). Anal. Calcd for control. Tubes containing tested organisms cultures were then
C32H26N4S2: C, 72.42; H, 4.49; N, 10.56; S, 12.08. Found: C, incubated at 37°C for 24h while the other fungal cultures
72.22; H, 4.43; N, 10.28; S, 11.89.
1,2-Bis-[4-(2H-coumarin-3-yl)-2-(phenylimino)-1,3- examined for growth by observing for turbidity.49)
Media Used Sabouraud’s Glucose Agar with Antibiotic:
were incubated at (25–30°C) for 3–7d. The tubes were then
thiazolidin-3-yl]ethane (15b): Yellow solid; Yield=(0.57g,
85%); mp >300°C; 1H-NMR (DMSO-d6) δ: 4.08 (4H, s), The medium used for isolation of pathogenic yeasts has the
6.36–6.38 (6H, m), 6.87–7.06 (6H, m), 7.41–7.43 (4H, m), following composition (g/L): glucose, 20; peptone, 10; agar, 25
7.72–7.75 (4H, m), 8.19 (2H, s); IR (KBr) cm−1: 3093, 3050, and distilled water, 1L—pH was adjusted at 5.4. The medium
1713, 1596, 1579; MS (m/z (%)): 666 (M+, 1.7), 345 (100), was autoclaved at 115°C for 15min then 0.5g/L. Chloram-
347 (63.9), 333 (M+/2, 3.1), 320 (9.4), 203 (4.3), 183 (5.5), 172 phenicol was added to avoid bacterial growth.50)
(13.2), 115 (17), 102 (11.5), 77 (22.6), 51 (8.3). Anal. Calcd for
C38H26N4O4S2: C, 68.45; H, 3.93; N, 8.40; S, 9.62. Found: C, tested bacteria. It contains (g/L) beef extract, 3; peptone, 5
68.33; H, 3.91; N, 8.59; S, 9.54.
and distilled water 1L.51)
Nutrient Agar (NA): The medium was used to cultivate

May 2014
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