Synthetic approach for novel fluorine substituted thiadiazaphosphole fused 1,2,4-triazinopyridiazine moieties as bactericidal agents

Article abstract of DOI:10.14233/ajchem.2016.19555

Novel fluorine substituted thiadiazaphosphole fused 1,2,4-triazino pyridiazines (7 and 8) were synthesized by refluxing of 4-amino-6-styryl-3-mercapto-1,2,4-triazin-5-one (2) with triethylphosphite and/or triethylphospate in dry ethyl benzene followed by cycloaddition with hydrazine in warm ethanol-piperidine and finally boil with trifluoroacetic anhydride in dioxane. Structure of the products was elucidated with the help of elemental analysis and spectral data. All the target compounds evaluated as bactericidal agents against Escherichia coli compared with chloromycetin as standard antibiotic.

Full text of DOI:10.14233/ajchem.2016.19555

Asian Journal of Chemistry; Vol. 28, No. 4 (2016), 917-920
A
SIAN
J
OURNAL OF HEMISTRY
C
http://dx.doi.org/10.14233/ajchem.2016.19555
Synthetic Approach for Novel Fluorine Substituted Thiadiazaphosphole
Fused 1,2,4-Triazinopyridiazine Moieties as Bactericidal Agents
*
MOHAMMED SALEH TAWFEK MAKKI, REDA MOHAMMADY ABDEL RAHMAN and OLA AHMAD ABU ALI
Chemistry Department, Faculty of Science, King Abdul Aziz University, Jeddah 80203, Kingdom of Saudi Arabia
*Corresponding author: E-mail: lolo_aa4@hotmail.com
Received: 10 August 2015;
Accepted: 13 October 2015;
Published online: 30 December 2015;
AJC-17716
Novel fluorine substituted thiadiazaphosphole fused 1,2,4-triazino pyridiazines (7 and 8) were synthesized by refluxing of 4-amino-6-
styryl-3-mercapto-1,2,4-triazin-5-one (2) with triethylphosphite and/or triethylphospate in dry ethyl benzene followed by cycloaddition
with hydrazine in warm ethanol-piperidine and finally boil with trifluoroacetic anhydride in dioxane. Structure of the products was
elucidated with the help of elemental analysis and spectral data.All the target compounds evaluated as bactericidal agents against Escherichia
coli compared with chloromycetin as standard antibiotic.
Keywords: Synthetic, Thiadiazaphospholo-1,2,4-triazine, Bactericidal.
Compound 1 was prepared [13] by stirring sodium pyru-
vate with p-chlorobenzaldehyde in 10 % aqueous NaOH at
0-5 °C.
INTRODUCTION
The introduction of phosphorus atom to heterocyclic
systems, often enhance their biological properties [1,2]. The
presence of phosphorus tends to more physical and chemical
activities [3]. Abdel-Rahman et al. [4,5] reported the incorpo-
ration of phosphorus-atom within a 1,2,4-triazinnes and pyrazoles
enhance that activity. 1,3,4-Thiadiazolo-1,2,4-triazinone showed
an anti HIV and anticancer activities. On the other hand, fluorine
substituted heterocyclic nitrogen molecules use as biocidal
probes [6-12]. Based on these observations, the present work
reports the synthesis of fluorine substituted thiadiazaphosphole
fused with 1,2,4-triazinopyridiazine moieties in view of their
bactericidal activity.
4-Amino-6-(4'-chlorophenyl)ethenyl-3-mercapto-1,2,4-
triazin-5-one (2): A mixture of 1 (0.01 mol) and thiocarbo-
hydrazide (0.01 mol) in absoluted ethanol (100 mL) containing
a few drops of conc. HCl, then refluxed for 4 h, cooled. The
solid obtained was filtered off and crystallized from ethanol
to 2 as orange crystals, yield 70 %, m.p.: 284-285 °C. UV
(λmax) 280 nm. IR (νmax, cm-1): 1700 (C=O), 1630 (NH2), 1480
(deformation CH=CH) 820, 780 (p-substituted phenyl), 710
(C-Cl). 1H NMR (DMSO-d6) δ (ppm): 8.7 (α-CH=), 7.8 (β-
CH=), 5.1 (CH=CH- coupling), 3.8 (NH2). 13C NMR (DMSO-
d6) δ(ppm): 179 (C=S), 160 (C=O), 132-128 (aromatic carbons),
120 (C=N), 77-75 (aliphatic carbons). CHNSCl analysis for
C11H9N4OClS (280). Calcd: C, 47.14; H, 3.21; N, 20.0; Cl,
12.5; S, 11.42 %. Found: C, 46.86; H, 3.11; N, 19.70; Cl,
12.31; S, 11.23 %.
6-(4'-Chlorophenyl)ethenyl-2,4,5-thiadiazaphospholo-
[2,3-c][1,2,4]triazin-5-one (3) and/or 6-(4'-chlorophenyl)-
ethenyl-2,4,5-thiadiazaphospholo[2,3-c][1,2,4]triazin-2,5-
dione (4): Equimolar mixture of 2 and triethylphosphite or
triethylphosphate in dry ethyl benzene (100 mL) was refluxed
for 6 h and cooled. The solid produced filtered off and crysta-
llized from benzene to give 3 and/or 4 respectively. 3: yield
65 %; m.p.: 274-275 °C. 4: yield 68 %; m.p.: 268-269 °C. 3:
UV (λmax): 310 nm. IR (νmax, cm-1): 1680 (C=O), 1200 (P=N),
1480 (deformation CH=CH), 880 (p-substituted phenyl). 4:
EXPERIMENTAL
Melting points of the products were determined on Stuart
SMP3 (UK) and uncorrected. UV absorption spectra (λmax, nm)
were recorded in DMF on Shimadzu UV and visable 310 IPC-
spectrophotometer.A Perkins Elmer Model RXI-FT IR system
55529 was used for recording IR spectra of the prepared
compounds γ cm-1.A Brucker advanced D P X 400 MHz model
using TMS as internal standard was used for recording the 1H
NMR and 13C NMR spectra of the compounds on deuterated
(CDCl3, d6, δ ppm). Mass spectrum was measured on GCMS
Q 1000 Ex at 70 eV. Elemental microanalysis was performed
by the microanalytical at Cairo- University, Egypt. Compounds
1 [4] and 10 [6] were prepared according the published methods.

918 Makki et al.
Asian J. Chem.
UV (λmax): 420. IR (νmax, cm-1): 1685 (C=O), 1445 (deformation
ring closure reaction of (E) trans-4-(4'-chlorophenyl-2-oxo-
3-buteneoic acid (1) [13] with thiocarbohydrazide in ethanol-
HCl [6] (Fig. 1). Reflux of compound 2 with triethylphosphite
in dry ethyl benzene [14] to give 2,4,5,1-thiadiazaphospholo[2,3-
c]1,2,4-triazine-5-one (3), while that reaction in use triethyl-
phosphate yielded 2,5-dioxo-6-(4'-chlorophenyl)ethylenic-
1,4,5,2-thiadiazaphosphole (4) (Scheme-I). The spectral data
are in good agreement with the proposed structure. IR spectrum
of 2 showed absorption bands at 1700, 1630 and 1480 cm-1
for C=O, NH2 and aliphatic CH=CH groups, while that of 3
recorded mainly bands at 3050 and 2880 cm-1 for aromatic
and aliphatic functional groups. IR spectrum of 4 showed a
characteristic band at 1230 and 1050 cm-1 attribute to presence
of P=O and P-O groups [15]. IR spectra of 3 and 4 recorded a
lack’s both NH2 and SH groups.
1
CH=CH), 1230 (P=O), 1050 (P-O). H NMR (DMSO-d6) δ
(ppm): 8.55 (α-CH=), 7.7 (B-CH=), 5.5 (Coupling CH=CH),
7.4-7.2 (m, 4H, aromatic). 31P NMR (DMSO-d6) δ (ppm): 18.9.
3: CHNClSP analysis for C11H6N4OClSP (308). Calcd: C,
42.83; H, 1.94; N, 18.18; Cl, 11.36; S, 10.38 %. Found C,
42.55; H, 1.80; N, 17.89; Cl, 11.15; S, 10.13 %. 4: CHNClSP
analysis for C11H6N4ClSPO2 (324). Calcd: C, 40.74; H, 1.85;
N, 17.28; Cl, 10.80; S, 9.87 %. Found C, 40.33; H, 1.55; N,
17.11; Cl, 10.72; S, 9.70 %.
7-(4'-Chlorophenyl)-6H-2,4,5-thiadiazaphospholo[2,3-
c][1,2,4]triazino[5,6-c]pyridiazine (5) and/or 7-[4'-chloro-
phenyl]-6H-2,4,5-thiadiazaphospholo[2,3-c][1,2,4]-
triazino[5,6-c]pyridiazin-2-one (6): Equimolar mixture of 3
and/or 4 with hydrazine hydrate in absolute ethanol (100 mL)
with a few drops of piperidine, was refluxed for 6 h, cooled
then added drops of glacial acetic acid-ice. The produced solid
was filtered off and crystallized from dioxane to give 5 and/or
6 respectively. 5: yield 55 %; m.p.: 280-282 °C. 6: yield 60 %;
m.p.: 242-244 °C. 5: IR (νmax, cm-1): 3150 (NH), 2900, 1488
H
N
H
C
N
Ar
C
H
C
Ar
C
H
OEt
N
N
O
P
O
S
O
S
N
N
N
N
H
2
EtO
OEt
1
(aliphatic CH), 1210 (P=N), H NMR (DMSO-d6) δ (ppm):
H
H
H
H
8.0 (s, 1H, NH), 7.8, 4.9 (-CH=CH-), 7.6 (s, 1H, CH of pyridia-
zine). CHNClSP analysis for C13H8N6ClSP (346). Calcd: C,
45.08; H, 2.31; N, 24.27; Cl, 10.11; S, 9.24 %. Found: C,
44.88; H, 2.25; N, 24.03; Cl, 9.85; S, 8.91 %. 6: IR (νmax, cm-1):
3130 (NH), 2890, 1440 (aliphatic CH), 1230 (P=O), 1055 (P-O),
860 (p-substituted phenyl), 690 (C-Cl). 1H NMR (DMSO-d6)
δ (ppm): 8.9 (s, 1H, NH), 7.9 (s, 1H, CH of pyridiazine), 7.7-7.5
(m, 4H, aromatic CH). CHNClSP analysis for C13H8N6ClSPO
(362). Calcd: C, 43.09; H, 2.20; N,23.20; Cl, 9.66; S, 8.83 %.
Found: C, 42.81; H, 2.11; N, 22.91; Cl, 9.55; S, 8.55 %.
7-(4'-Chlorophenyl)-6-trifluoroacetyl-2,4,5-thiadi-
azaphospholo[2,3-c][1,2,4]triazino[5,6-c]pyridiazine (7)
and/or 7-[4'-chlorophenyl]-6-trifluoroacety-2,4,5-thiadi-
azaphospholo[2,3-c][1,2,4]triazino[5,6-c]pyridiazin-2-one
(8): Equimolar amounts of 5 and/or 6 with triethyl acetic
anhydride in dioxane (100 mL) was refluxed for 4 h, cooled.
The resulted solid was filtered and crystallized from THF to
give 7 and/or 8 respectively. 7, yield 45 %; m.p.: 248-250 °C.
8, yield 58 %; m.p.: 232-234 °C.7: IR (νmax, cm-1): 1700 (C=O),
1600 (C=N), 1250 (C-F), 1220 (N=P), 810 (p-substituted
phenyl), 720 (C-F), 700 (C-Cl). CHNClSP analysis for
C15H7N6OClSPF3 (442). Calcd: C, 40.72; H, 1.58; N, 19.00;
Cl, 7.91; F, 12.89; S, 7.23 %. Found: C, 40.44; H, 1.38; N, 18.55;
Cl, 7.70; F, 12.63; S, 7.01 %. 8: IR (νmax, cm-1): 1698 (C=O),
1610 (C=N), 1240 (C-F), 1210 (P=O), 1060 (P-O), 795 (p-
substituted phenyl). 1H NMR (DMSO-d6) δ (ppm): 8.2 (s, 1H,
CH= of pyridazine), 7.8-7.5 (m, 4H, aromatic protons). 13C NMR
(DMSO-d6) δ (ppm): 165 (C=O), 130-128 (aromatic carbons),
118, 116 (C=N). 31P NMR: 19.1. M/s: (Int. %) 460 (M+2,
5 %) 93 (100). CHNClFPS analysis for C15H7N6O2ClF3SP
(458). Calcd: C, 39.30; H, 1.52; N, 18.34; Cl, 7.64; F, 12.44;
S, 6.98 %. Found: C, 38.91; H, 1.33; N, 18.12; Cl, 7.50; F,
12.31; S, 6.55 %.
-EtOH
H
N
Ar
C
H
C
Cl
C
CH
O
N
N
H
N
-2 EtOH
O
SH
P
N
N
N
H
O
S
H
4
EtO
OEt
N
P
O
Fig. 1. Formation of 4 from 2
H2N
NH
C
O
S
Cl
C
CH
C
C
+
H
NH
OH
H N
2
O
trans
1
2h
EtOH / HCl
H
N
N
Cl
C
H
C
N
O
SH
trans
2
NH2
(OEt)3P=O
(OEt)3P/
6h
-3EtOH
C6H5Et
H
C
CH
O
Cl
N
N
Cl
C
CH
O
N
H
N
N
N
N
S
S
RESULTS AND DISCUSSION
4
3
N
P
P
The key intermediate in these study is the 4-amino-6-
O
stryle-3-mercapto-1,2,4-triazin-5-one (2) was obtained from
Scheme-I

Vol. 28, No. 4 (2016) Synthetic Approach for Novel Fluorine Substituted Thiadiazaphosphole Fused 1,2,4-Triazinopyridiazine Moieties 919
1H NMR spectra of compounds 2-4 showed a resonated
signals at δ 8.8, 7-8 and 6.2 ppm for α-H, β-H and coupling of
-CH=CH- (stryl protons). Furthermore, 31P NMR spectrum of
4 recorded a singlet at δ 18.9 ppm for cyclic P=O.
Due the higher nucleophilicity of S– atoms, formation of
compound 4 was deduced from a nucleophilic attack of S– to
a more electrophilic P-atom followed by other nucleophilic
attack of NH2 to that P-atom and loss three mole of EtOH
(Fig. 1).
7.4 ppm. These spectral data, is confirm that cycloaddition
reaction tack’s place followed by oxidation reaction (Scheme-
II).
Fluorination of both compounds 5 and/or 6 by using
trifluoroacetic anhydride in reflux dioxane furnished 6-
(trifluoroacetyl)-7-(4'-chlorophenyl)-2,4,5,1-thiadiazaphos-
pholo[2,3-c][1,2,4]triazino[5,6-c]pyridiazine (7 and 8),
respectively (Scheme-II). IR spectra of compounds 7 and 8
showed the lack’s of NH groups with presence of a new bands
at 1710 and 1250 cm-1 for acetyl C=O and C-F functional groups.
Also, 1H NMR spectra give us a good indication about lack’s
of NH proton of 7 and 8.
UV absorption spectra of compounds 2-4 give us a good
indication about heterocyclization of 2 to 3 and/or 4. Were
λ
λ
max of 4 was higher than compound 3 and the start 2.A higher
max of 4 is may be due to the extension of hetero-conjugation
13C NMR spectra of these compounds recorded a resonated
signals at δ 160 and 140 ppm for C=O and C-F carbons present.
Mass fragmentation pattern of compound 8 showed [16] a
molecular ion peak which under fragmentation process give a
base peak at m/z 93 as cyclic NSPO (Fig. 2).
formed.
Compounds 3 and 4 use as cyclic α,β-unsaturated ketone
system. Thus, cycloaddition of 3 and/or 4 with hydrazine
hydrate in boiling absolute ethanol drops piperidine afforded
the 2,4,5,1-thiadiazaphospholo[2,3-c][1,2,4]triazino[5',6',-
c]pyridiazines (5 and 6) respectively (Scheme-II). IR spectra
of compounds 5 and 6 showed a bands at 3150, 2900 and
1488-1 cm attribute to NH and CH= groups with lack’s of C=O
group. 1H NMR spectra of both 5 and 6 showed a new resonated
signals at 8.9 and 7.9 ppm for NH and CH= protons of new
formed pyridiazine, in addition the aromatic protons at δ 7.7-
Cl
Cl
N
N
N
N
N
N
N
N
N
N
S
S
OC
F3C
N
N
O
O
P
P
335 (18)
8, M+ 460(M+2, 5)
H
H
Cl
C
CH
N
Cl
C
CH
O
N
N
N
N
N
N
O
N
N
N
N
N
S
S
105(87)
N
-N2
N
4
3
P
N
N
P
S
O
EtOH-Piperdine
NH -NH H O
2
2.
2
S
N
224
O
P
93 (100)
P
O
N
6h
-H O
Fig. 2. Mass Fragmentation pattern of compound 8
2
H
H
Bactericidal activity: Literature survey reveals that cyclic
N
N
R
N
R
N
nitrogen-phosphorus as phospholes have attracted considerable
attention as they are endowed with wide spectrum of activities
[17,18]. Also 1,2,4-triazines are well known and important
heterocyclic nitrogen systems [19,20]. Escherichia coli is one
of the important bacteria widely occurring in green plants.
Thus the present investigation, tends to synthesis of fused
polyheterocyclic systems containing both nitrogen, sulfur and
phosphorus elements (compounds 3-8) in view of their bacteri-
cidal activity against E. coli, all the synthesized compounds
were evaluated in vitro for antibacterial (E. coli) via the disc
diffusion method [21], was applied against Escherichia coli.
The filter paper discs were soaked in the solutions of synthesized
compounds at different concentrations (150, 100 and 50 ppm)
in 10 % ethanol and placed at the center of the bacteria seeded
agar plates (petri-dishes). These petri dishes were incubated
at 28-30 °C for 24 h. The strength is reported by measuring
the diameter of zone of inhibition of mm. and the results are
standardized against chloromycetin (Table-1).
H
N
H
N
H
N
H
HN
HN
S
N
S
N
P
N
O
P
oxidn
(piperdn)
oxidn
(piperdn)
- H
- H
N
N
R
R
N
N
HN
HN
N
N
N
N
S
S
6
N
N
5
P
O
P
F C-COOET
- EtOH
3
4h
5
C H Et
6
N
N
R
R
N
N
O
C
O
C
F C
3
N
F C
N
3
N
N
N
N
S
From the results obtained (Table-1), it is concluded that:
compound 2 is highly effective and more than 4 > 6 > 8. The
higher inhibitory of 2 in action on E. coli is due to presence of
both NH2 and SH groups which is agreement with biodynamic
systems. On the other hand, inhibition zone of compound
S
8
7
N
N
P
O
P
H
R=
C
Cl
HC
Scheme-II

920 Makki et al.
Asian J. Chem.
TABLE-1
REFERENCES
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COMPOUNDS 2-8 (ZONE OF INHIBITION, mm)
E. coli
Compounds
Conc. 50
50
100
50
28
35
20
31
19
35
150
50
30
48
25
47
21
46
2
3
4
5
6
7
8
25
25
20
22
15
23
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Conclusion
From the present investigation, it can be concluded that
the novel synthesized of fluorine bearing a condensed poly-
heterocyclic systems containing both sulfur and phosphorus
were designed to act as bactericidal probe. These systems were
found to be active towards E. coli which may plays an impor-
tant role for antimicrobial activity, were help to control on
cellobiace phenomena.
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ACKNOWLEDGEMENTS
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21. C.H. Collins, Microbiological Methods, Butterworths, London, p. 364
(1967).
The authors are grateful to Dr. I.N. Ismail, Biochemistry
Department, Faculty of Sciences, Ain Shams University, for
antibacterial activity screening studies of the newly synthesized
compounds.