Tổng hợp, nghiên cứu cấu trúc và tính chất của một số dị vòng imidazol 5 one, thiazolidin 2,4 dione và 1,3,4 oxadiazoline tt tieng anh

MINISTRY OF EDUCATION AND TRAINING
VINH UNIVERSITY

NGUYEN VAN THIN

SYNTHESIS, STRUCTURE,
AND PROPERTIES OF SOME IMIDAZOLE-5-ONE,
THIAZOLIDINE-2,4-DIONE OR 1,3,4-OXADIAZOLINE
HETEROCYCLES

Specialization: Organic Chemistry
Code: 9440114

SUMMARY OF DOCTORAL THESIS IN CHEMISTRY

NGHE AN, 2020


The thesis was completed at Vinh University

Scientific supervisors:
1. Assoc Prof. Dr. Nguyen Tien Cong
2. Assoc. Prof. Dr. Le Duc Giang

Reviewer 1.…………………………………………
Reviewer 2. …………………………………………
Reviewer 3…………………………………………..

The thesis is defended before the Ph.D. Thesis Evaluation Council at the University level
Location: Vinh University
Time: At time

, date

month year 2020

The thesis can be found at:
- National Library
- Information Center - Library Nguyen Thuc Hao, Vinh University


INTRODUCTION
1. Reasons for the topic choice
In recent years, the chemistry of heterocyclic compounds has developed
dramatically. The number of detected heterocyclic compounds as natural or synthetic
compounds is increasing more and more, their properties and methods of synthesis
have also been researched more and more fully and systematically. Along with that,
the biological activity of heterocyclic compounds also have been interested in
research, so they have been increasingly applied.
Five-membered heterocycles with nitrogen heteroatom (azoles) such as pyrrole,
imidazole, 1,3,4-oxadiazole, thiazolidine have received a lot of researchers’ interest
because of their applications in different fields of life, especially in pharmaceutical
chemistry. Some aromatic heterocycles such as imidazole, thiazole, 1,3,4-oxadiazole
are known to be biological active centers and they also are mediators in the
preparation of bioactive compounds. Many chemists have been interested in research
and have discovered a relatively large number of compounds containing one of the
above heterocycles with biological activities such as antibacterial, antiviral, antiinflammatory, anti-cancer, anti-diabetes, anticonvulsant, anti-oxidant. A lot of
compounds containing imidazole-5-one ring (a derivative of imidazole), thiazolidine2,4-dione ring (a derivative of thiazole) or 1,3,4-oxadiazoline ring (a derivative of
1,3,4-oxadiazole) were also detected as bioactive and pharmacological centers. That
has opened up new directions in research to synthesize, convert and apply these
compounds in life fields, especially in the production of medicines.

Currently, in Vietnam, the number of studies on heterocyclic compounds
containing imidazole-5-one; thiazolidine-2,4-dione or 1,3,4-oxadiazoline nucleus are
modestly published compared to the abundance of directions for the synthesis of
these compounds in the World. According to our research, there is a small amount of
research on 2-thiazolidine-4-one, thiazolidine-2,4-dione heterocycles from Vietnam
and the number of published studies for 2-thiazolidine-4-one and 1,3,4-oxadiazoline
heterocycles has been not much.
Today, in the World, many studies on azoles as imidazole, thiazolidine, and
1,3,4-oxadiazole have been published. But the research on new derivatives of
imidazoline-5-one; thiazolidine-2,4-dione and 1,3,4-oxadiazoline heterocycles with a
few substituents are not much. Recently published studies showed that the
compounds containing these heterocycles also have biological activities such as
antibacterial, antipruritic, anticancer, hypoglycemic, etc. So they have attracted
researchers’ interest, especially in the field of pharmaceutical chemistry
Therefore the PhD student choose the topic: “Synthesis, structure, and
properties of some imidazole-5-one, thiazolidine-2,4-dione or 1,3,4-oxadiazoline
heterocycles”
2. Goals and main research contents of the thesis
2.1. Goals of the study
Synthesis of new organic compounds (target) containing imidazole-5-one
heterocycle; thiazolidine-2,4-dione heterocycle or 1,3,4-oxadiazoline heterocycle
1


with different substituents in experimental conditions of Vietnam. Study on the
properties, structures and biological activities of these compounds to contribute to the
studies of both theory and application of heterocyclic compounds.
2.2. Contents of the study
* Synthesize 3 series of new target compounds containing five-membered
heterocycle: A-series consists of 14 compounds with imidazole-5-one nuclear of type

1-arylideneamino-4-(4-methoxybenzylidene)-2-methyl-1H-imidazolin-5 (4H)-one (8
substances) and 1-arylideneamino-4- (4-chlorobenzylidene)-2-methyl-1H-imidazolin5 (4H)-one (6 substances); B-series consists of 10 diesters which are derivatives of 5(2/3/4-hydroxybenzylidene)thiazolidine-2,4-dione; C-series consists of 12
compounds containing 1,3,4-oxadiazoline heterocycle of type 2- (4-acetyl-5-aryl-5methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl -4-bromophenyl acetate (3 substances) and
2-(4-acetyl-5-methyl-5-aryl-4,5-dihydro-1,3,4-oxadiazol-2-yl) -4-iodophenyl acetate
(9 substances).
* Study the structures and properties of the synthesized compounds based on
the methods of determining the melting point, determining the crystalization solvent;
Infrared (IR) spectrum, high resolution mass spectrometry (HR-MS), nuclear
magnetic resonance spectrum (NMR). Especially, some compounds belong to Cseries are determined by real structure by using X-ray monocrystalline diffraction.
* Test the biological activities: antibacterial activity against Escherichia coli,
Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus; antifungal
against Aspergillus niger, Fusarium oxysporum, Saccharomyces cerevisiae, Candida
albicans; cytotoxicity with breast cancer MCF-7, carcinoma (KB), liver cancer
(HepG2) cell lines of the synthesized target compounds.
3. Scientific significance, practicality and new contributions
* Has studied, launched appropriate synthesis procedures and successfully
synthesized 36 new heterocyclic compounds belong to 3 series of compounds
containing imidazole-5-one ring (A-series), thiazolidine-2,4-dione ring (B-series) and
1,3,4-oxadiazoline ring (C-series). Besides that, 32 intermediate compounds also
were synthesized.
* Has provided scientific information and data on the structure (especially
molecular crystal structure of 3 compounds C5b3, C5b4 and C5b5), as well as
properties, crystallization solvents and biological activities of 36 new target
compounds (antibacterial and fungal activities of A4b1-6 compounds, anti-breast
cancer MCF-7 of A4b1-6, B3a-e and B4a-e compounds, anticancer liver HepG2 and
KB carcinoma of C5b1-9 compounds).
4. Layout thesis
The layout of thesis includes 154 pages, in which, introduction 3 pages;
overview 27 pages; experimental 32 pages; results and discussion 76 pages;
conclusion 2 pages. The thesis has 56 diagrams, 49 figures and 27 tables; 12 pages of

references with 139 Vietnamese and English documents. In addition, there is also
Appendix part consisting of 211 spectra and tables.

2


CHAPTER 1.
OVERVIEW
The thesis has reviewed the literature on the synthesis and biological activities
of heterocyclic compounds containing 1H-imidazol-5(4H)-one ring; thiazolidine-2,4dione ring or 1,3,4-oxadiazoline ring. The kinds of literature were published both
inside and outside of Vietnam. The results of the review have shown the synthetic
methods of the above heterocycles, as well as their biological activities such as
antibacterial,
antifungal,
anti-tuberculosis,
anticancer,
anti-inflammatory,
hypoglycemic, etc. At the same time, it also pointed out that research on these
heterocycles is a new trend with being of great interest and it is growing rapidly with
a plentiful number of publications in the world, but not many in Vietnam.

3


CHAPTER 2.
EXPERIMENTS AND METHODS
2.1. Methods of studying the structure and properties
The melting points were determined in open capillaries and are uncorrected.
The IR spectra were recorded on an FT-IR Shimadzu 8400-S. NMR spectra were
measured on a Bruker Avance 500 MHz in dimethyl sulfoxide (DMSO-d6) using

tetramethylsilane (TMS) as an internal reference. Mass spectra were recorded on a
Bruker micrOTOF-Q 10187 mass spectrometer.
2.2. Synthesis of compounds
New organic compounds containing five-membered heterocycle with
heteroatom of nitrogen are synthesized according to 3 diagrams illustrated in Figures
2.1, 2.2, and 2.3. All chemicals were obtained from commercial sources and used
without further purification.
O
X

(CH3CO)2O

(A1a,b)

N

X

X = Cl(a), CH3O(b)

O

O

CH3CONHCH2COOH
(A2a,b)

NH2NH2

O

CH3

N NH2

N

X

CH3

(A3a,b) X = Cl(a), CH3O(b)

X = Cl(a), CH3O(b)

R - C6H4-CHO

(A4a1-8): X = Cl; R= 4-OCH3 (a1), 4-CH3 (a2), 2-F (a3), 4-F (a4), H (a5),
2-NO2 (a6), 3-NO2 (a7), 4-NO2 (a8)

O
N

X

(A4b1-6): X= OCH3 ; R= 4-Cl(b1), 2-NO2(b2), 3-NO2(b3), 4-NO2(b4),

N N

R

CH3

3-CH3-4-OH (b5), 3,4-(-OCH2O-) (b6)

(A4a1-8) & (A4b1-6)

Figure 2.1: Synthetic pathway of targeted compounds (A4a1-8) and (A4b1-6)
Cl

O
H2N

HCl

O

NH2

R

S
O

S

OH
R

H
(B1a-e)

O

NH
O

O

O

OH

OH
R

O
S

H
(B2a-e)

N H

S

O
N
O

H

O
O
(B3a-e)

2-OCO2Et, R = H (3a); 2-OCO2Et, R = 5-Br (3b)
3-OCO2Et, R = H (3c); 4-OCO2Et, R = H (3b)
4-OCO2Et, R = 3-OMe (3e)
O

O

O

2-OH, R = H (a); 2-OH, R = 5-Br (b);
3-OH, R = H (c); 4-OH, R = H (d);
4-OH, R = 3-OMe (e)

R

O
S

H

O
N
O O

O

(B4a-e)

2-OCH2CO2Et, R = H (4a); 2-OCH2CO2Et, R = 5-Br (4b)
3-OCH2CO2Et, R = H (4c); 4-OCH2CO2Et, R = H (4d);
4-OCH2CO2Et, R = 3-OMe (4e)

Figure 2.2: Synthetic pathway of targeted compounds (B3a-e) and (B4a-e)
4


O

O
OH

OH

C4a/C5a

OCH3 a) Br2/CCl4

CH3OH
H2SO4

(C1)

OH

b) NaOCl, KI

OCH3

N 2H 4

OH
(C2a-b): X = Br (a), I (b)
O

X = Br

O
O

O

X

NHNH2
OH
(C3a-b) X = Br (a), I (b)
R-C6H4COCH3

CH3
N N CH3

R = 3-Br (a1), 3-OCH3 (a2),3-NO2 (a3)

X
X=I

R = 3-NO2 (b1), 4-NO2 (b2), H(b3), 4-F (b4),

C4b/C5b

O

X

(CH3CO)2O X
R

4-Cl (b5), 3-Br (b6), 4-Br (b7), 4-CH3 (b8),
O
CH3
4-NH2 (C4b9); 4-NH-CO-CH3 (C5b9)
(C5a1-3) & (C5b1-9)

O
N
OHH

N
CH3

(C4a1-3) &(C4b1-9)

R

Figure 2.3: Synthetic pathway of targeted compounds (C5a1-3) and (C5b1-9).
2.3. Biological activities

2.3.1. Antifungal and antibacterial activities
Antimicrobial activity of tested samples was assayed using micro broth dilution
methods of McKane, L., and Kandel for test microorganisms including Escherichia
coli, Pseudomonas aureus, Bacillus subtilis, Staphylococcus aureus, Aspergillus
niger, Fusarium oxysporum, Saccharomyces cerevisiae, and Candida albicans. The
positive controls were Ampicillin for Gram positive strains; Tetracycline for Gram
negative strains and Nystatin for mycelium and yeast.
2.3.2. Cytotoxic activity
Tests for cytotoxic activity were conducted at the Biological Laboratory,
Institute of Biotechnology, Vietnam Academy of Science and Technology. The
(A4b1-6) and (B3a-e, B4a-e) compounds were investigated for cytotoxic activity
against the breast cancer cell line (MCF-7) by the Sulforhodamine B method (in vitro)
with the positive control in the experiment is Camptothecin. The (C5b1-9)
compounds were tested for in vitro cytotoxic activity against carcinoma (KB) cell
line, and hepatocellular cell line (HepG2) with Ellipticine as the positive control.

5


CHAPTER 3.
RESULTS AND DISCUSSION
3.1. The synthesis, structure and properties of the compounds belonging to
A-series
3.1.1. Synthesis
The (A4a1-8) and (A4b1-6) compounds were prepared from acetyl glycine and
4-chlorobenzaldehyde (A1a) or 4-methoxybenzaldehyde (A1b) according to the
synthetic pathway illustrated in Figure 2.1.
3.1.1.1. Synthetic procedures
* The procedures to synthesize (A2a), (A2b), (A3a) and (A3b) compounds are
presented in Section 2.2.1.2 and Section 2.2.1.3 of the thesis.

* The procedures to synthesize (A4a1-8) and (A4b1-6) compounds are
presented in Section 2.2.1.4 of the thesis.
3.1.1.2. Results
* Synthetic results; IR, 1H-NMR spectral data of (A2a) and (A2b) compounds
were mentioned in Section 2.2.1.2 of the thesis.
* Synthetic results; IR, MS, 1H-NMR, 13C-NMR spectral data of (A3a) and
(A3b) compounds were mentioned in Section 2.2.1.3 of the thesis.
* Compounds (A4a1-8) and (A4b1-6): The (A3a) or (A3b) compound reacted
with aromatic aldehydes in absolute ethanol to form azomethine derivatives (A4a1-8)
and (A4b1-6), respectively. The reactions occur according to the mechanism of a
condensation reaction between an amine and a carbonyl compound. Yields, physical
properties, and IR, HR-MS spectral data of resulted azomethines (Schiff's bases) were
shown in Table 3.1.
Table 3.1: Physical properties and IR, MS spectral data of the Schiff's bases
(A4a1-8) and (A4b1-6)
Yiel
IR (, cm-1)
(M+H)+
Melting
No Compound
d
C=C
NO
2
[Calc.]
point (oC)
C-H
C=O
(%)
C=N

1678,
354.1051
3060
4-CH3O
1717
176-178 80
1
1605, 1561
[354.0931]
2930
(A4a1)
- 360.0867 *
4-CH3
2924
1705 1651, 1589
2
182-184 66
2855
[360.0982]
(A4a2)
342.0824
3 2-F (A4a3) 196-197 78
1717 1651, 1591
[342.0731]
342.0818
4 4-F (A4a4) 184-185 74
1713 1651, 1589
[342.0731]
6

5
6
7
8
9

H (A4a5)

173-174

68

2960

1713 1651, 1589

175-177

77

2847

1705 1643, 1582

181-182

81

3079

213-214

84

2924

4-Cl (A4b1) 192-193

64

2945

2-NO2
(A4a6)
3-NO2
(A4a7)
4-NO2
(A4a8)

-

1520
1342
1536
1713
1589
1350
1538
1705 1643, 1582

1342
1708 1649, 1599

324.0928
[324.0825]
369.0751
[369.0676]
369.0746
[369.0676]
369.0783
[369.0676]
354.1002
[354.1009]
387.1077*
[387.1069]
365.1235
[365.1250]
365.1245
[365.1250]
366.1452
[366.1454]
364.1264
[364.1297]

2-NO2
1544
234-235 74
1713 1643, 1597
1320
(A4b2)

3-NO2
1536
219-220 43
3018 1697 1643, 1597
11
1350
(A4b3)
1512
3001
4-NO2
245-246 58
1698 1667, 1597
12
1342
(A4b4)
2855
3-CH3O-42970
13
235-236 61
1688 1645, 1601
**
OH(A4b5)
2924
3,4-(CH2O2)
14
179-180 56
2918 1688 1649. 1603
(A4b6)
Note: * (A4a2), (A4b2): [M+Na]+; (A4b5)**: OH = 3441cm-1
3.1.2. The structures

* The structure of (A3a) and (A3b) was confirmed by their IR, HR-MS, 1HNMR, 13C-NMR spectral data (see Section 2.2.1.3 of the thesis).
* The structure of Schiff's bases (A4a1-8), (A4b1-6) was confirmed by their IR,
HR-MS, 1H-NMR, 13C-NMR, HSQC, HMBC spectral data. 1H-NMR and 13C-NMR
were shown in Table 3.2, Table 3.3, Table 3.4, and Table 3.5 of the thesis. 1H-NMR
and 13C-NMR of the (A4a7) and (A4b3) compounds were chosen as representatives
* (4Z)-1-(3-nitrobenzylideneamino)-4-(4-chlorobenzylidene) -2-methyl-1H-imidazol5(4H)-one (A4a7): 1H-NMR (δ, ppm và J, Hz): 2.48 (3H,
9 8
10
7 6
singlet, H-2a, s); 7.06 (1H, singlet, H-6); 8.20 (2H, doublet,
O
Cl
4 5
11 17 16
3
1
J=8.5, H-8); 7,47 (2H, doublet, 3J=8.5, H-9); 9.70 (1H,
N N 12
3N
15
2
14
13
2a CH3
singlet, H-11); 8.57 (1H, singlet, H-13); 8.29 (1H, doublet,
(A4a7)
NO2
3
J =8.0, H-15); 7,77 (1H, doublet-doublet, 3J 1=3J 2 =8.0, H16); 8.23 (1H, doublet,3J =8.0, H-17). 13C-NMR (δ, ppm): 162.6 (C-2); 14.5 (C-2a);
136.6 (C-4); 165.4 (C-5); 125.0 (C-6); 132.1 (C-7); 133.3 (C-8); 128.3 (C-9); 134.8

(C-C-10); 151.1 (C-11); 135.2 (C-12); 121.3 (C-13); 148.1 (C-14); 124.9 (C-15);
130.1 (C-16); 133.2 (C-17)
10

7


Figure 3.1. The 1H-NMR spectrum of
Hình 3.2. The 13C-NMR spectrum of
(A4a7)
(A4a7)
1-Amino-4-(4-chlorobenzylidene)-2-methyl-1H-imidazoline-5(4H)-one
compound (A3a) reacted with 3-nitrobenzaldehyde in absolute ethanol to form
azomethine derivative (A4a7). The IR spectrum of Schiff's base (A4a7) obtained
from amine (A3a) showed not only a lack of stretching band at 3209 cm-1 (νNH2) but
also an appearance of the absorption band of imine group (C=N) at 1589 cm-1; in
addition, strong absorptions at 1536 cm-1 and 1350 cm-1 characterizing NO2 group
also appeared in the spectrum.
The 1H-NMR spectrum of (A4a7) compound showed a new signal at 9.70 ppm
assigned to the proton H-11 of the azomethine group (CH=N). Besides, one singlet
signal with integral strength of 3H in the upfield (2.48 ppm) is attributed to protons
H-2a of the 2-methyl group in the heterocycle. In the aromatic region, there are 2
singlet signals with an integral intensity of 1H at 7.06 ppm and 8.57 ppm are
attributed to H-6 and H-13. Two doublet signals (3J = 8.5 Hz) with integral strength
of 2H appear at 7.47 ppm and 8.20 ppm are attributed to the protons H-9, H-8. Proton
H-9 is closer to the electron withdrawn group (Cl), so its resonance signal will appear
at lower field. Proton H-16 has spin-spin coupling with H-15 and H-17 so the
doublet-doublet signal at 7.77ppm (3J1 = 3J2 = 8.0) corresponds to H-16. Two doublet
signals (1H) at 8.23 ppm and 8.29 ppm correspond to protons H-17, H-15. Since H15 is in the ortho position of the -NO2 group, the local magnetic shielding must be
reduced more than H-17 in the para position, so H-15 must give the resonance signal

in the down field. The 13C-NMR spectrum of (A4a7) showed enough 16 signals being
accordant with the molecular structure. In which, the signal of the aliphatic carbon C2a appears in the upfield (14.5 ppm); but the signal of carbon atoms such C-5 (C=O),
C-2 (C=N in imidazoline heterocyclic), and C11 (-N=CH-) have to appear in the
downfield that were at 165.4, 151.1 and 162.6 ppm respectively. Besides, 12 signals
of carbon on the benzene rings appear in the range of 121.3-148 ppm. The HSQC
spectrum shows that the signals of C-6, C-8, C-9, C-11, C-13, C-15, C-16, C-17
atoms make cross peaks with signals of the corresponding protons. In the HMBC
8


spectrum, the singlet signal of H-11 at 9.70 ppm in the 1H-NMR spectra makes a
cross peak with signals of the C-12 atom in the benzene ring of benzylidene moiety
bonded to nitrogen at 135.2 ppm. The other intersection peaks of protons / carbons
such as H-2a / C-2, H-6 / C-5; H-8 / C-10 and C-7, H-9 / C-7; H-6 / C-5 or C-4, H-11
/ C-13; H-15 / C-14 are also seen in the spectrum.
Analyze the spectra of (A4a7) compound help to assign all of the signals in
both its 1H-NMR and 13C-NMR spectra and help to conclude that the (A4a7)
compound was successfully synthesized. On that basis, the structure of compounds
(A4a1-8) in the A-series also was determined.
* (4Z)-1-(3-nitrobenzylideneamino)-4-(4-methoxybenzylidene) -2-methyl-1H-imidazol5(4H)-one (A4b3): 1H-NMR (δ, ppm và J, Hz): 2.48
9 8
(3H, singlet, H-2a, s); 7.14 (1H, singlet, H-6); 8.28 (2H,
10
7 6
O
10a O
4 5
17 16
doublet, 3J=8.5, H-8); 7.08 (2H, doublet, 3J=8.5, H-9);
11

H3C
1
3
N 2 N N 12
3.84 (3H, singlet, H-10a); 9.83 (1H, singlet, H-11); 8.69
15
(A4b3)
14
2a
13
(1H, singlet, H-13); 8.37 (1H, doublet, 3J =8.0, H-15);
CH3
NO2
7,82 (1H, doublet-doublet, 3J 1=3J 2 =8.0, H-16); 8.34
(1H, doublet, 3J =8.0, H-17). 13C-NMR (δ, ppm): 161.1 (C-2); 15.1 (C-2a); 133.7 (C4); 165.9 (C-5); 127.3 (C-6); 126.4 (C-7); 134.3 (C-8); 114.5 (C-9); 161.3(C-10);
55.4 (C-10a); 151.1 (C-11); 135.6 (C-12); 121.8 (C-13); 148.3 (C-14); 1246.0 (C-15);
130.6 (C-16); 134.4 (C-17). The spectra of (A4b3) compound were analyzed and
attributed similarly to compound (A4a7). The results allow confirming the structure
of (A4b3) compound as well as the structure of (A4b1-6) compounds in the A-series.
3.1.3. Biological activities of (A4a1-8) and (A4b1-6)
3.1.3.1. The antibacterial and antifungal activity of (A4a1-8) compounds
Table 3.2: The minimum inhibitory concentrations (MIC) of (A4a1-8) against
bacteria and fungi
MICa (g/mL)
Bacteria Gram- Bacteria GramNo Sample
Mold
Yeast
(-)
(+)
E.C

P.A
B.S
S.A
A.N
F.O
S.C
C.A
b
1 (A4a1) (-)
(-)
(-)
(-)
(-)
(-)
(-)
100
2 (A4a2)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
100
3 (A4a3)
(-)
(-)
(-)
(-)

(-)
(-)
(-)
(-)
4 (A4a4)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
5 (A4a5)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
6 (A4a6)
(-)
(-)
(-)
(-)
(-)
(-)
(-)

(-)
7 (A4a7)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
8 (A4a8)
(-)
(-)
(-)
(-)
(-)
(-)
(-)
100
9


E.C - Escherichia coli, P.A - Pseudomonas aeruginosa, B.S - Bacillus subtilis,
S.A - Staphylococcus aureus, A.N -Aspergillus niger, F.O - Fusarium oxysporum,
S.C - Saccharomyces cerevisiae and C.A - Candida albicans. bMIC > 100 μg/mL and
not determined
The results (Table 3.2) showed that only (A4a1), (A4a2), and (A4a8) exhibited
significant inhibition against Staphylococcus aureus with MIC values of 100 μg/mL.
Comparing the structure of compounds (A4a1), (A4a2), and (A4a8) with the rest, it
is possible to predict that some substituents such as −CH3, −OCH3, −NO2 at the para

position of the benzene ring make increase the biological activity of the substrate.
3.1.3.2. Cytotoxic activity of (A4b1-6) compounds
Table 3.3. Selective cytotoxicity on breast cancer cells of (A4b1-6) compounds
Percentage of cytotoxicity (%)
Sample
No
st
1
2nd
3rd
Avg ± SD
1
4.53
1.22
2.28
1.86 ± 2.62
(A4b1)
2
6.23
5.76
3.12
5.04 ± 4.42
(A4b2)
3
(A4b3)
4
(A4b4)
5
24.15
10.35

7.40
13.97 ± 8.94
(A4b5)
6
8.44
3.70
-2.24
3.30 ± 5.35
(A4b6)
7
52.98±3.81
Camptothecine
The toxicity against breast cancer cells MCF-7 of (A4b1-6) compounds was
negligible. However, the (A4b5) compound showed higher activity than the others.
Comparing the structure of the compound (A4b5) with the other could identify
initially that the substituents as −CH3 and −OH at meta, para positions on the
benzene ring make increase the cytotoxic activity of the substrate.
3.2. The synthesis, structure and properties of the compounds belonging to
B-series
3.2.1. The synthesis
Knoevenagel condensation of thiazolidine-2,4-dione (TZD), which were
prepared from chloroacetic acid and thiourea by 1,3 dipolar cycloaddition reaction,
with some hydroxybenzaldehydes (B1a-e) gave five corresponding 5(hydroxybenzylidene)thiazolidine-2,4-dione compounds (B2a-e). The reaction of 5(hydroxybenzylidene)thiazolidine-2,4-diones and ethyl chloroformate or ethyl
chloroacetate occurred at both NH and OH centers and gave ten corresponding
diesters (B3a-e) and (B4a-e) (Figure 2.2).
3.2.1.1. The synthetic procedures
* The procedure to synthesize TZD compound was presented in Section 2.2.2.1
of the thesis.
a

10


* The procedure to synthesize (B2a-e) compounds based on the reaction of
hydroxybenzaldehydes with thiazolidine-2,4-dione using weakly basic amine
(piperidine) as a catalyst and toluene as a solvent. The procedure was presented in
Section 2.2.2.2 of the thesis.
* The procedures to synthesize (B3a-e) and (B4a-e) compounds were presented
in Section 2.2.2.3 of the thesis, where the mixture of the definite (B2a-e) compounds
with ethyl chloroformate or ethyl chloroacetate (molar ratio of 1: 2) in acetone in the
presence of K2CO3 was refluxed for about 10 hours.
3.2.1.2. Results
* Synthetic results and physical properties, IR spectral data of (B2a-e)
compounds were summarized in Table 3.4.
Table 3.4: Physical properties and IR spectral data of (B2a-e) compounds
Comp.

IR (cm-1)

Melting point
(oC)

Yield
(%)

O-H
N-H
C-H
C=C
C=O

(B2a)
278 - 280
3426
3032
2810
1589 1728 1667
58.0
(B2b)
256 - 258
3449
3094
2905
1589 1728 1636
57.0
(B2c)
290 - 293
3302
3163
3063
1589 1751 1690
51.0
(B2d)
318 - 320
3403
3133
2903
1574 1728 1682
56.0
(B2e)
242-245

3464
3186
1574 1728 1682
54.0
* The reaction of (B2a-e) compounds with ethyl chloroformate follows the
mechanism of SN2(CO) to form (B3a-e) compounds, while the reaction with ethyl
chloroacetate follows the mechanism of SN2 to form (B4a-e) compounds. In the conditions
of the reactions, both OH and NH centers of the 5- (hydroxybenzylidene)
thiazolidine-2,4-dione compounds reacted contemporaneously to afford the
corresponding diesters. Yields, physical properties, and IR, HR-MS spectral data
of compounds (B3a-e), and (B4a-e) compounds were shown in Table 3.5.
Table 3.5: Physical properties and IR, MS spectral data of (B3a-e) and (B4a-e)
compounds
No

Melting Yieds
point (0C) (%)

C-H

IR (, cm-1)
C=C
C=O

C-O

(B3a)

122- 123

63.0

2986 3032

1759, 1705 1319, 1249

(B3b)

126-127

73.0

2924 2986

1489

1759, 1705 1489, 1319

(B3c)

131-132

62.0

2986 3063

1613

1780, 1759 1312, 1235

(B3d)

139-140

66.0

2986 3090

1697

1751, 1705 1304, 1234

(B3e)

127-128

70.0

2986 3180

1605

1751, 1705 1312, 1257

11

[M+Na]+/
[Cacl.]
388.0426/
[388.046]

465.9566/
[465.957]
388.0448/
[388.046]
388.0451/
[388.046]
418.1560/


[418.057]
(B4a)

111-112

50.0

2986, 2890

1597

1750, 1797

1372,1220

(B4b)

118-119

51.0

2986, 2924

1597

1736, 1690 1381, 1219

(B4c)

96-97

57.0

2986, 2916

1605

1744, 1697 1373, 1211

(B4d)

125-126

62.0

2978

1589

1744, 1690 1381, 1211

(B4e)

95-96

54.0

2986, 2909

1589

1728, 1690 1373, 1211

416.0757/
[416.078]
472.0065*/
[472.006]
416.0745/
[416.078]
416.0762/
[416.078]
446.0867/
[446.088]

* (B4b): [M + H]+
3.2.2. Structures
* The structures of the (B2a-e) compounds were confirmed by IR spectroscopy,
1
H-NMR as well as compared with the properties described in the references. 1HNMR spectral data of compounds are shown in Table 3.10 of the thesis. Compound
(B2b) is a new compound with spectral features: IR (ν, cm-1): 3449 (O-H), 3094 (NH), 1728 (C=O), 1636 (C=O), 1589 (C=C), 1498, 1281, 602 (C-Br); 1H-NMR (δ,
ppm và J, Hz): 12.63 (1H, singlet, H-3), 10.89 (1H, singlet, -OH), 7.89 (1H, singlet,

H-6), 7.49 (1H, doublet-doublet, 3J = 8.5, 4J = 2.5, H-10), 7.41 (1H,
doublet, 4J = 2.5, H-12), 6.95 (1H, doublet, 3J = 8.5, H-9).
(B2b)
* The molecular structures of the (B3a-e) and (B4a-e)
compounds were confirmed by their IR, HR-MS, 1H-NMR and 13C-NMR spectral
data. The results of analysing and attributing the 1H-NMR and 13C-NMR of the (B3ae), and (B4a-e) compounds were shown in Table 3.11, Table 3.12, Table 3.13, and
Table 3.14 in the thesis. The following are spectral data of (B3d) and (B4d)
compounds that were selected as representative of the compounds belonging to the Bt
series.
O
H3C
Oy
O
c
O
z
* Ethyl 5-(4-((ethoxycarbonyl)oxy)benzylidene)-2,4x 3 4
a b O
d
N
9
7
CH
O
3
8
dioxothiazolidine-3-carboxylate (B3d): 1H-NMR (δ,
5 6
(B4d)
O 2 S

1
ppm và J, Hz): 8.0 (1H, singlet, H-6); 7.72 (2H,
doublet, 3J = 8.5, H-8), 7.45 (2H, doublet, 3J = 8.5, H-9); 4.46 (2H, quartet, 3J = 7.0,
H-10b); 4.29 (2H, quartet, 3J = 7.0, H-3y); 1.33 (3H, triplet, 3J = 7.0, H-10c); 1.31
(3H, triplet, 3J = 7.0, H-3z); 13C-NMR (δ, ppm): 163.9 (C-2); 162.2 (C4); 120.2 (C-5);
133.3 (C-6); 130.6 (C-7); 131.8 (C-8); 122.4 (C-9); 147.2 (C-10); 122.4 (C-11); 131.8
(C-12); 152.2 (C-10a); 65.6 (C-10b); 13.9 (C-10c); 152.5 (C-3x); 65.0 (C-3y); 13.7
(C-3z).
3
HN

Br

4 O

O 2 S
1

5

12

6

7

11

8

10
9

OH

12

11

10

12


Figure 3.5: A part of 1H-NMR
spectrum of (B3d)

Figure 3.6: The 13C-NMR spectrum of
(B3d)

* Ethyl 2-(5-(4-(2-ethoxy-2-oxoethoxy)benzylidene)-2,4dioxothiazolidin-3yl)acetate (B4d): 1H-NMR (δ, ppm và J, Hz): 7.88 (1H, singlet, H-6), 7.49 (2H,
O
doublet, 3J = 9.0, H-8); 7,00 (2H, doublet, 3J =9.0, H-9),
H3C
O
O
O
O
CH3 4.67 (2H, singlet, H-10a), 4.46 (2H, singlet, H-3x), 4.28
N

O
O 2 S
(2H, quartet, 3J = 7,0, H-3z), 4.23 (2H, quartet, 3J = 7.0,
(B3d)
H-10c), 1.31 (6H, multiplet, H-3t, H-10d); 13C-NMR (δ, ppm): 168.2 (C-2); 165.7
(C-4); 118.8 (C-5); 134.1 (C-6); 132.3 (C-7); 126.8 (C-8); 115.4 (C-9); 159.7 (C-10);
115.4 (C-11); 126.8 (C-12); 65.2 (C-10a); 166.3 (C-10b); 62.2 (C-10c); 14.2 (C-10d);
42.1 (C-3x); 67.5 (C-3y); 61.6 (C-3z); 14.1 (C-3t)
z

y

x

3

12

4

11

10

7

1

5

6

8

9

c

a

b

Figure 3.7: The 1H-NMR spectrum of Figure 3.8: The 13C-NMR spectrum of
(B4d)
(B4d)
The IR spectra of (B3d) and (B4d) were disappeared in some bands at 3403
-1
cm (OH) and 3133 cm-1(NH) and the presence of the carbonyl groups was
recognized easily by the intense absorption bands at 1705, 1751, 1790 cm-1 (for B3d)
or at 1744, 1690 cm-1(for B4d).
13


Comparing with the 1H-NMR spectrum of (B2d) compound, the 1H-NMR
spectra of (B3d) and (B4d) did not appear any broad signal in the range of 9.80-12.70
ppm that characterized protons in the N-H and O-H groups. The formation of the
diesters (B3d) and (B4d) also was confirmed by the appearance of the signals of
protons in two ethyl groups, which were assigned as two quartets (with the intensity
of 2H for each signal, J=7.0Hz) around 4.29 - 4.47 ppm and two triplets (with the
intensity of 3H for each signal, J=7.0Hz) around 1.20-1.40 ppm. For (B3d)

compound, these signals appeared at 4.46 ppm (2H, quartet, 3J = 7.0, H-10b), 4.29
(2H, quartet, 3J = 7.0, H-3y) and 1.33 (3H, triplet, 3J = 7.0, H-10c), 1.31 (3H, triplet,
3
J = 7.0, H-3z) while for (B4d) compound, these signals appeared at 4.28 (2H, quartet,
3
J = 7.0, H-3z), 4.23 (2H, quartet, 3J = 7.0, H-10c) and 1.31 ppm (6H, multiplet, H-3t,
H-10d). The singlet signals for methylene groups between the heteroatom and
carbonyl group of the (B4d) compounds appeared at 4.67 ppm (2H, singlet, H-10a)
and 4.46 ppm (2H, singlet, H-3x). In the 13C-NMR spectra, 4 signals appearing
between 165.7- 168.2 ppm were assigned to 4 carbonyl carbons including 2 carbonyl
carbons in the thiazolidine-2,4-dione ring and 2 carbonyl carbons in the functional
groups of diester; 4 signals appearing in the aliphatic region of the spectrum of (B3d)
compound were attributed to 4 carbons of two ethyl groups while the spectrum of the
(B4d) compound appeared more than 2 signals in this region due to the presence of 2
methylene groups, each of them was between heteroatom and carbonyl group. The
MS spectra of (B3d) and (B4d) compounds also showed molecular ion peaks being
according to the assumed structures.
3.2.3. The selective cytotoxicity on breast cancer cells (MCF-7)
The synthesized compounds were tested for their selective cytotoxicity on breast
cancer cells (MCF-7 cells) via SRB (sulforhodamine B) assay. The selective cytotoxicity
result on breast cancer cells of the diesters containing TZD ring (B3a-e, B4a-e) at a
concentration of 100 µg/mL was shown in Table 3.6 (The B3d compound did not dissolve
well in DMSO, so it was not tested the selective cytotoxicity on breast cancer cells)
Table 3.6. Selective cytotoxicity on breast cancer cells of (B3a-e) and (B4a-e)
compounds
Percentage of cytotoxicity (%)
No
Comp.
1st
2nd

3rd
Avg ± SD
1
(B3a)
24.43
10.58
16.77
17,26 ± 6,94
2
(B3b)
27.58
27.25
25.63
26,82 ± 1,04
3
(B3c)
18.39
13.36
14.57
15,44 ± 2,63
4
(B3d)*
5
(B3e)
27.71
24.34
24.93
25,66 ± 1,80
6
(B4a)

7.18
1.98
-1.40
2,59 ± 4,32
7
(B4b)
5.54
5.69
-2.52
2,90 ± 4,70
8
(B4c)
2.90
5.16
-0.28
2,59 ± 2,73
9
(B4d)
4.03
5.16
-1.12
2,69 ± 3,35
10
(B4e)
1.13
-1.72
2.52
0,64 ± 2,16
53,84
50.64

54.46
52.98 ± 3.81
Camptothecin
14


(Note: Avg: average, SD: standard deviation)
Although all tested compounds have not shown good cytotoxic activity on
MCF-7 cells but ethyl 5-(((ethoxycarbonyl)oxy)benzylidene)-2,4-dioxothiazolidine3-carboxylate compounds (B3a-c, B3e) exhibit higher cytotoxic than ethyl 2-(5-(4(2-ethoxy-2-oxoethoxy)benzylidene)-2,4-dioxothiazolidin-3-yl)acetate
compounds
(B4a-c).
3.3. Synthesis, structure and properties of the compounds belonging to C-series
3.3.1.The synthesis
3.3.1.1. Synthetic procedures
12 new compounds (C5a1-3 and C5b1-9) that are derivatives of 5-bromo/iodo2-hydroxybenzoate were synthesized starting from methyl salicylate. The synthesis
pathway was described in Figure 2.3.
* The procedures to synthesize methyl 5-bromo-2-hydroxy-5-iodobenzoate
(C2a) and methyl 2-hydroxy-5-iodobenzoate (C2b) were presented in Section 2.2.3.1
of the thesis.
* The procedures to synthesize 5-bromo-2-hydroxybenzohydrazide (C3a) and 2hydroxy-5-iodobenzohydrazide (C3b) were presented in Section 2.2.3.2 of the thesis.
* The procedures to synthesize N’-(1-arylethylidene)-2-hydroxy-5-halobenzohydrazide
compounds (C4a1-3 and 4b1-9) were presented in Section 2.2.3.3 of the thesis.
* Synthesis of 2-(4-acetyl-5-aryl-5-methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)-4halophenyl acetate compounds (C5a1-3 and C5b1-9): A mixture of an appropriate Nsubstituted hydrazide (C4a1-3, C4b1-9) (5 mmol) and acetic anhydride (10 ml) was
taken into a 100 ml round-bottomed flask. The mixture was refluxed for 4 hs. After
cooling to room temperature, the reaction mixture was poured into ice-cold water.
The precipitate obtained was filtered off and crystallized from a mixture of ethanol
and water to give the corresponding products (C5a1-3 and C5b1-9). The crystals of 3
compounds (C5b3, C5b4, and C5b5) were suitable for X-ray diffraction.
3.3.1.2. Results
* The synthetic results and physical characteristics of (C2a) and (C2b) were

presented in Section 2.2.3.1.
* The synthetic results, physical characteristics and IR, 1H-NMR spectra data
of (C3a) and (C3b) were mentioned in Section 2.2.3.2 of the thesis.
* The synthetic results, physical properties and IR, HR-MS spectral data of
compounds (C4a1-3) and (C4b1-9) were summarized in Table 3.7.
Table 3.7: Yield, physical properties and IR, HR-MS spectral data
of (C4a1-3) and (C4b1-9) compounds
crystalliza
Melting
IR (, cm-1)
Yield
(M+H)+
tion
point
Comp.
O-H
C=O
(%)
[Cacl.]
NO2
solvent
(oC)
N-H
C=N
DMF:
3271
1641
434.9154*
(C4a1)
247

64
H2O
3059
1599
[434.9163]
DMF:
387.0176
3354
1622
(C4a2)
222.5
73
H2O
3256
1597
[387.0164]
(C4a3)
258.3
69
dioxane
3283
1636 1520
399.9939*
15


3092
1599 1354
399.9909
3217

1636 1520
425.9924
(C4b1) 235-236
88
dioxane
3217
1599 1350
[425.9951]
3094
1643 1535
447.9718*
(C4b2) 259-260
82
dioxane
3094
1600 1342
[447.9770]
DMF:
3295
1643
380.9992
(C4b3) 179-180
84
H2O
3040
1566
381.0100
399.0007
3295
1643

DMF:
(C4b4) 234-235
77
[399.0006]
3102
1605
H2O
DMF:
414.9674
3287
1643
(C4b5) 269-270
85
H2O
[414.9710]
3088
1550
480.9023*
3412
1644
DMF:
(C4b6) 272-273
82
3034
1556
[480.9127]
H2O
458.8999
3285
1647

DMF:
(C4b7) 282-283
86
[458.9205]
3034
1593
H2O
DMF:
3279
1645
395.0247
(C4b8) 228-229
76
H2O
3035
1606
[395.0256]
3440
396.0069
1634
(C4b9) 242-243
78
dioxane
3928
[396.0209]
1577
3201
* [M+Na]+
* The reaction mechanism to form the 1,3,4-oxadiazoline compounds (C5a1-3,
C5b1-9) was described in Scheme 3.1

H
X

N N
O
OH

R
C

-H+

R

N N
X

O

CH3

N N
X

CH3

OH

(CH3CO)2O

X

O

CH3

OCOCH3

O
N N

O

+H+

CH3
R

CH3

(CH3CO)2O
SN(CO)

OCOCH3

N N
X

O

H
R

CH3

OCOCH3

Scheme 3.1: Reaction mechanism to form 1,3,4-oxadiazoline ring
Synthetic results, physical properties and IR, HR-MS spectral data of (C5a1-3)
and (C5b1-9) compounds were summarized in Table 3.8.
Table 3.8: Yield, physical properties and IR, HR-MS spectral data
of (C5a1-3) and (C5b1-9) compounds
Melting Yiel
MS
IR ( cm-1)
2
d
point
[M+Na]+
Comp.
C=N
Csp -H
NO2
C=O
(%) Csp3-H
(OC)
[Cacl.]
C=C
3078
1626

518.9360
(C5a1) 148-149
52
1765
2984
1568
[518.9375]
140.53072
1659
469.0379
(C5a2)
61
1765
141.5
2985
1580
[469.0375]
16


1661
1528
484.0123
3076
1765
1528
1347
[484.1120]
2950
3079

1659
1527
532.0008
(C5b1) 188-189
56
1751
2986
1589
1357
[531.9991]
3055
1667
1528
531.9991
(C5b2) 204-205
58
1759
2940
1605
1358
[531.9981]
3075
1667
487.0126*
(C5b3) 153-154
53
1767
2950
1604
[487.0131]

3094
1659
505.0044
(C5b4) 158-160
54
1759
2940
1605
[505.0036]
3094
1667
520.9743
(C5b5) 198-199
58
1767
2930
1597
[520.9741]
3071
1651
564.9230
(C5b6) 202-203
53
1767
2932
1598
[564.9236]
3094
1620
564.9244

(C5b7) 201-202
55
1767
2928
1589
[564.9236]
3009
1667
501.0261
(C5b8) 199-200
62
1767
2924
1620
[501.0267]
544.0173
1655
3070
(C5b9)
1763
200-201
56
[544.0345]
1601
2934
**
+
-1
Note: * (M+H) và ** νNH = 3320 cm
3.3.2. Structures

* The structure of the C4a1-3 and C4b1-9 compounds belonging to the Cseries was confirmed by their IR, HR-MS, 1H-NMR, and 13C-NMR spectra. 1H-NMR
and 13C-NMR spectral data of C4a1-3 and C4b1-9 compounds were presented in
Table 3.18, Table 3.19, and Table 3.20 in the thesis.
* The structure of the (C5a1-3) and C5b1-9) compounds was confirmed by
their IR, HR-MS, 1H-NMR, and 13C-NMR spectral data. The results of analyzing and
attributing 1H-NMR and 13C-NMR spectra of (C5a1-3) and (C5b1-9) compounds
were showed in Table 3.21; Table 3.22 and Table 3.23 in the thesis. The following is
the spectral data of the two compounds (C5a3) and (C5b3) that was selected to
represent the C-series.
*
2-(4-acetyl-5-methyl-5-(3-nitrophenyl)-4,5O
CH
dihydro-1,3,4-oxadiazol-2-yl)-4-bromophenyl
acetate
N N
CH
1
Br
(C5a3): H-NMR (δ ppm and J, Hz): 8.32 (2H, multiplet,
O
H-12, H-10), 8.02 (1H, doublet, 3J=8.0 Hz, H-14), 7,96
O
11a
ON
(1H, doublet, 4J=2.5 Hz, H-2), 7.87 (1H, doublet-doublet,
HC
O
3
(C5a3)
J=8.5 Hz, 4J=2.0 Hz, H-6), 7.77 (1H, doublet-doublet,

(C5a3)

121-122

51

19

18

3

17

1

2

3

4

6

5

16
3

3

8

14

9

7

13

10

15

11

12

2

17


J1=3J2=8.0 Hz, H-13), 7.32 (1H, doublet, 3J=8.5 Hz, H-5), 2.28 (3H, singlet, H-16),
2.27 (3H, singlet, H-19), 2.26 (3H, singlet, H-17); 13C-NMR δ ppm): 169.2 (C-15);
166.9 (C-18); 149.5 (C-7); 148.4 (C-4); 148.2 (C-11); 141.0 (C-9); 136.2 (C-3); 132.9
(C-6); 131.6 (C-2); 130.9 (C-12); 127.0 (C-13); 124.8 (C-5); 121.1 (C-10); 120.0 (C1); 119.2 (C-14); 99.5 (C-8); 22.7 (C-17); 22.6 (C-19); 21.1 (C-16).
3

Figure 3.9: The 1H-NMR of (C5a3)
Figure 3.10: The 13C-NMR of (C5a3
The 1H-NMR spectrum of (C5a3) compound (Fig 3.9) has enough signals
corresponding to 16 protons. In which, 3 singlet signals with integral 3H of each at δ
2.28; δ 2.27 and δ 2.26 are assigned to three methyl groups at the positions of 16, 17
and 19. Four proton signals in the benzene ring (from number 9 to number 14)
appeared in the region 7.77-8.32 ppm and were attributed to H-13 (δ 7.77, 1H,
doublet-doublet, 3J1 = 3J2 = 8.0 Hz), H-14 (δ 8.02, 1H, doublet, 3J = 8.0), H-10 (δ
8.32, 1H, 4J = 2.0 Hz) and H-12 (δ 8.31, 1H, doublet-doublet, 3J = 8.0 Hz, 4J = 2.0
Hz). Shape characteristics of the signals indicate that the benzene (C9-C14) ring
contains two substituents at positions of 1 and 3. The 13C-NMR spectrum (Fig 3.10)
of (C5a3) has all the signals of 19 carbon atoms. The three signals in the alkane
region correspond to the three-carbon of the three methyl groups at 22.7 ppm (C-17),
22.6 ppm (C-19), and 21.1 ppm (C-16), respectively. Besides, the appearance of two
signals of carbon in the C=O group at 169.2 ppm (C-15) and 166.9 ppm (C-18) is
completely consistent with its structural characteristics. The signals of C-7 (Csp2) and
C-8 (Csp3) of the 1,3,4-oxadiazoline appear at 149.5 ppm and 99.5 ppm, respectively.
Since C-4 links to the oxygen atom while and C-11 links to the nitro group, their
signals are shifted downfield and appear at 148.4 ppm and 148.2 ppm, respectively.
The signals of the other aromatic carbon atoms appear in the range 141.0 - 119.2 ppm.

18


*
2-(4-Acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4oxadiazol-2-yl)-4-iodophenyl acetate (C5b3): 1H-NMR (δ
N N
CH3
8
14

9
I 1 2 3 7
O
ppm và J Hz) : 8.05 (1H, doublet, 4J = 2.0, H-2); 7.98
13
4
10
6
(1H, doublet-doublet, 3J = 8.5, 4J = 2.0, H-6); 7.51 (2H,
O
12
5
11
15
16
doublet, 3J = 7.0, H-11, H-13), 7.44 (3H, multiplet, HH 3C
O
(C5b3)
10, H-12, H-14), 7.13 (1H, doublet, 3J = 8.5, H-5), 2.25
(3H, singlet, H-16), 2.24 (3H, singlet, H-19), 2.20 (3H, singlet, H-17); 13C-NMR (δ
ppm): 169.2 (C-15); 166.5 (C-18); 149.3 (C-7); 148.7 (C-4); 141.9 (C-9); 139.1 (C-6);
137.2 (C-2); 129.8 (C-3); 129.0 (C-11,C-13); 126,9 (C-10, C-14); 126,1 (C-5); 120,3
(C-12); 100.4 (C-1); 91.7 (C-8); 22.8 (C-17); 22.7 (C-19); 21.1 (C-16). The spectra of
(C5b3) compound were analyzed and attributed similarly to the compound (C5a3),
thereby allowing confirmation of its molecular structure as well as the molecular
structure of (C5b1-9) compounds in the C-series.
3.3.3. Crystal structures of some compounds containing 1,3,4-oxadiazoline
heterocycle (C5b3), (C5b4) and (C5b5)
The crystals of (C5b3), (C5b4), and (C5b5) compounds are suitable for X-ray
diffraction that belongs to the monoclinic space group P21/c. Crystal data, data

collection and structure refinement details for (C5b3), (C5b4), and (C5b5) were
summarized in Table 3.9.
Table 3.9: Crystal data and Data collection of
Crystal data
(C5b3)
(C5b4)
(C5b5)
Chemycal formula
C19H17IN2O4
C19H16FIN2O4
C19H16ClN2O4
Mr
464.24
482.24
498.69
Crystal system
Monoclinic
Monoclinic
Monoclinic
space group
P21/c
P21/c
P21/c
8.8370 (1)
9.1241 (4)
11.703 (2)
a (Å)
b (Å)
20.0560 (1)
20.0980 (9)

22.037 (4)
Crystalline
c (Å)
11.0150 (1)
10.7456
7.4073 (12)
cell
0
β()
110.18 (1)
110.224 (2)
92.888 (8)
parameters
0
α=γ ( )
90.0
90.0
90.0
3
V (Å )
1832.4 (3)
1849.00 (15)
1907.9 (5)
Radiation type
Mo K
Mo K
Mo K
-1
µ (mm )
1.77

1.77
1.85
Crystal size (mm
0.42×0.20×0.16 0.60×0.37×0.29 0.22×0.12×0.12
Diffractometer
Bruker APEXII Bruker APEXII Bruker APEXII
CCD
CCD
CCD
O

18

19

CH3

17

19


The fractional atomic coordinates and isotropic or equivalent isotropic
displacement parameters (Å2); Atomic displacement parameters (Å2); Geometric
parameters (Å, º) were shown in the tables in the Appendix of the thesis
* Crystal structures of (C5b3) compound
The central 1,3,4-oxadiazoline ring in (C5b3) displays an envelope
conformation (Fig.3.11) with the C8 atom as the flap [puckering parameters: Q =
0.1310 (14) Å and φ = 322.2(6)0]. The best plane through the 1,3,4-oxadiazoline ring
makes angles of 7.84(8)0 and 78.48(8)0 with the 4-iodophenyl ring (atoms C1-C6)

and the phenyl ring (atoms C9-C14), respectively. Both aromatic rings are inclined to
each other by 82.11(8)0.
In the crystal, molecules of (C5b3) are linked by C-H…O and C-H…π
interactions, forming chains propagating along the b-axis direction (Fig. 3.12 and
Table 3.10). Molecules in parallel chains form inversion dimers by I…π interactions
[Fig. 3.12; I…Cg2iv = 3.7888 (8) Å; Cg2 is the centroid of the C1-C6 ring; symmetry
code: (iv) x + 2, y + 1, z + 1]

Figure 3.11: The molecular structure
Figure 3.12: Packing diagram for
of (C5b3)
(C5b3)
Cg2 is the centroid of the C1-C6 ring and Cg3 is the centroid of the C9-C14
ring. [Symmetry codes: (i) -x + 1, y - 1/2, z + 1/2; (ii) -x + 2, y + 1, z + 1; (iii) x, - y +
3/2, z + 1/2.]
Table 3.10: Hydrogen-bond geometry (Å, 0) for (C5b3)
Hydrogen-bond
Length (Å)
Angle (0)
D-H…A
D-H
H…A
D…A
D-H…A
i
C5-H5…O4
0.95
2.51
3.2828 (19) 139
ii

C16-H16B…O4
0.98
2.55
3.529 (2)
177
iii
C17-H17C…Cg3
0.98
2.70
3.5766 (17) 150
Note: Cg3 is the centroid of the C9-C14 ring; [Symmetry codes: (i) -x +1; y1/2; -z +1/2; (ii) x; -y+3/2; z-1/2; (iii) x; -y + 3 2; z + 1/2]
20


* Crystal structures of (C5b4) compound
The crystal structures of (C5b3) and (C5b4) (Fig. 3.13) are isomorphous; the
r.m.s. overlay fit is 0.0438 Å for the non-H atoms. The puckering parameters of the
1,3,4-oxadiazoline ring of (C5b4) are Q = 0.1159(17) Å and φ = 325.4(8). The
crystal packing is built up by C-H…O, C-H…π and C-I… π interactions, as for
(C5b3) [Table 3.11: I…Cg2i = 3.7807 (8) Å ; Cg2 is the centroid of the C1-C6 ring;
symmetry code: (i) x + 2, y + 1, z + 1]. In addition, a C14- H14…O2 ii interaction
(Table 3.11) is observed, which together with the C16-H16A…O4iii interaction,
results in the formation of a dimer, generating an R22 loop (Fig. 3.14)
Table 3.11: Hydrogen-bond geometry (Å, 0) for (C5b4)
Hydrogen-bond
Length (Å)
Angle (0)
D-H…A
D-H
H…A

D…A
D-H…A
i
C5-H5…O4
0.95
2.53
3.331(2)
142
ii
C14-H14…O2
0.95
2.51
3.335(2)
145
iii
C16-H16A…O4
0.98
2.54
3.513(2)
174
ii
C17-H17C…Cg3
0.98
2.50
3.407(2)
154
* Symmetry codes (i) -x + 1, y - 1/2, -z + 1/2; (ii) x, -y + 3/2, z + 1/2; (iii) x, -y
+ 3/2, z - 1/2. Cg3 is the centroid of the C9 - C14 ring.

Figure 3.13: The molecular

structure of (C5b4)

Figure 3.14 Partial packing diagram for
(C5b4)

[Symmetry code: (i) x, - y + 3 2, z + 1/2.]
* Crystal structure of (C5b5) compound
Compound (C5b5) is not isomorphous with analogues (C5b3) and (C5b4). The
1,3,4-oxadiazoline ring is almost planar (r.m.s. deviation = 0.024 Å ) and is inclined
to the planes of the aromatic rings by 11.95(8) (ring C1-C6) and 78.28(8) (ring C9C14) (Fig. 3.15). The orientation of the acetate group in (C5b5) is different compared
to compounds (C5b3) and (C5b4), as illustrated by the torsion angle C3-C4-O1-C15
[83.55(18)0 in (C5b5), 81.17(17)0 in (C5b3) and 81.5(2)0 in (C5b4)]. As a result, in
structures (C5b3) and (C5b4), the acetate group and the C8-aryl substituent are syn
21


with respect to one another, while in (C5b5) they are anti. In all three cases, the
carbonyl O atom (O-4) of acetate is close to being eclipsed with respect to atom C-4
of the aromatic ring, which may indicate a favourable interaction between a
nonbonded pair of electrons on O4 and the π* orbital of the aromatic C1-C6 ring.
In the crystal, inversion dimers are formed by C11- H11…O1ii interactions
(Table 3.12 and Fig. 3.16). These dimers interact further by C6-H6…O2i and C19H19B…πiii interactions with the iodo-substituted phenyl ring (Table 3.12 and Fig.
3.16), resulting in chains of molecules running in the c direction. Parallel chains
interact further by Cl…π contacts, again with the iodo-substituted phenyl ring (Table
3.12 and Fig. 3.16). In contrast to the crystal packings of the two previous analogues,
the packing of (C5b5) does not show I…π interactions. The closest neighbour for
atom I1 is H17B (I1…H17Bi = 3.13 Å). The shortest I…Cl distance in the crystal
packing is I1…Cl1iv = 3.850(2) Å [symmetry code: (iv) x + 1, y + 1/2, z + 1/2].

Figure 3.15: The molecular structure Figure 3.16: Partial packing diagram

of (C5b5)
for (C5b5)
Table 3.12: Hydrogen-bond geometry (Å, 0) for (C5b5)
Hydrogen-bond
D-H…A
C6-H6…O2i
C11-H11…O1ii
C19-H19B…Cg2iii

Length (Å)
D-H
0.95
0.95
0.98

H…A
2.47
2.55
2.75

D…A
3.258 (2)
3.435 (2)
3.649 (2)

Angle (0)
D-H…A
140
155
153

The crystal packings of compounds (C5b3), (C5b4) and (C5b5) contain no
voids.
In summary, single-crystal X-ray diffraction studies were also carried out for
(C5b3), (C5b4), and (C5b5). Compounds (C5b3), (C5b4) are isomorphous, with the
1,3,4-oxadiazoline ring having an envelope conformation, where the disubstituted C
atom is the flap. The packing is determined by C-H…O, C-H…π, and I…π
interactions. For (C5b5), the 1,3,4-oxadiazoline ring is almost planar. In the packing,
Cl…π interactions are observed, while the I atom is not involved in short interactions
22


3.3.4. In vitro cytotoxicity of (C5b1-9) compounds
Table 3. 13. Cytotoxic effects of the examined compounds (C5b1-9) (IC50 in µM)
No
1
2
3
4
5
6
7
8
9

Comp.
R
KB (IC50 µM)
HepG2 (IC50 µM)
3-NO2

C5b1
3.733  0.472
12.574  0.766
4-NO2
C5b2
9.214  0.884
14.735  0.727
H
C5b3
5.280  0.819
12.284  0.625
C5b4
4-F
1.867  0.568
4.564  0.539
C5b5
4-Cl
4.012  0.622
3.811  0.822
C5b6
3-Br
0.921  0.360
3.315  0.552
4-Br
C5b7
6.262  0.645
13.260  0.866
C5b8
4-CH3
3.166  0.398

3.983  0.482
4-NH-CO-CH3
C5b9
12.476  0.979
11.900  1.036
Ellipticine
1.260  0.528
2.358  0.407
The tested results in Table 3.13 indicate that most of the examined compounds
possess at least moderate cytotoxic activity, and some compounds even display a
promising activity profile. Compounds (C5b4), (C5b5), (C5b6) and (C5b8) (IC50
values between 0.9 and 4.5 µM), showing a reasonable activity against two human
cancer cell lines. In particular, compound (C5b6) exhibits a strong anticancer effect
against KB cells, with an IC50 value (0.9 µM) lower than Ellipticine (1.2 µM).
Initially, it is possible to predict that the R substituent group in the meta
position on the phenyl ring (from C-9 to C-14) increases the cytotoxic activity of the
compound more than the para position. Especially, compound (C5b6) with the Br
substituent at the meta position on the benzene ring has the strongest activity and is
capable of developing into cancer treatment drugs.

23