Tandem reactions using nitrile imines: Synthesis of some novel heterocyclic compounds with expected biological activity

Article abstract of DOI:10.13005/ojc/320115

New functionalized 7,9-dimethylpyrimido[4,5-d][1,2,4]triazolo[4,3-a]pyrimidine-5,6,8(1H,7H,9H)-trione derivatives were synthesized via reaction of the hydrazonoyl halides with 7,8-dihydro-1,3-dimethyl-7-thioxopyrimido[4,5-d]pyrimidine-2,4,5(1H,3H,6H)trione. The biological activity of the products has been evaluated. The mechanism and the regioselectivity of the studied reactions have been discussed.

Full text of DOI:10.13005/ojc/320115

ISSN: 0970-020 X
CODEN: OJCHEG
016, Vol. 32, No. (1):
Pg. 149-158
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Free Access, Peer Reviewed Research Journal
2
www.orientjchem.org
Tandem Reactions Using Nitrile Imines:
Synthesis of Some Novel Heterocyclic Compounds with
Expected Biological Activity
AꢀIL A. H. GOBOURI1,
MOSSELHI A.N. M. MOHAMEꢀ*1,2 and MAHMOUꢀ A. AMIN1,3
1
Department of Chemistry, Faculty of Science, Taif University, 21974-Taif/haweiah, Saudi Arabia.
2
Department of Chemistry, Faculty of Science, Cairo University, 12613-Giza, Egypt.
3
Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia, Egypt.
*Corresponding author E-mail: mosselhimohamed@yahoo.com
http://dx.doi.org/10.13005/ojc/320115
(Received: January 29, 2016; Accepted: March 01, 2016)
ABSTRACT
New functionalized 7,9-dimethylpyrimido[4,5-d][1,2,4]triazolo[4,3-a]pyrimidine-
,6,8(1H,7H,9H)-trione derivatives were synthesized via reaction of the hydrazonoyl halides with
,8-dihydro-1,3-dimethyl-7-thioxopyrimido[4,5-d]pyrimidine-2,4,5(1H,3H,6H)trione. The biological
5
7
activity of the products has been evaluated. The mechanism and the regioselectivity of the studied
reactions have been discussed.
Key words: Tandem reaction, hydrazonoyl halides, nitrile imines,
l,3-dipolar cycloaddition, heterocycles, biological activity.
INTROꢀUCTION
commonly referred to under the nebulous phrase
1
“multistep one-pot reactions”. On cost and amounts
Chemistsareconstantlyworkingtodiscover
of reagents, solvents, and reduce the amount of
waste that is generated. So, our aim is to use such
idea of tandem reactions of organic compounds
to synthesize new heterocycles with expected
biological activity in short steps by using nitrile imines
via 1,3-dipolar cycloaddition.
new and improved reactions. One of the primary
motivating goals of this research is the development
of cleaner, more efficient transformations to shorten
syntheses and save money on chemicals. The
strategy of using reactions in tandem is also aimed
at shortening syntheses. Tandem reactions are

150
GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
ꢀasically a nitrile imine 1 is a flexible system were recorded in potassium bromide discs on a
of three atoms over which four pi-electrons are Pye-Unicam, SP300 and Shimadzu, FT IR 8101
distributed. Although one can write seven possible PC infrared spectrophotometers. ꢀiological activity
resonance structures for such a system, the 1,3- was carried out at the Microanalytical Center of
dipolar sextet structure 1A with its complementary Cairo University, Cairo, Egypt. Mass spectra were
nucleophilic and electrophilic centers will be recorded on a Shimadzu GC MS-QP 1000 EX mass
used throughout this article, although theoretical spectrometer at 70 e.V. Elemental analyses were
calculations have indicated that all the octet carried out at the Microanalytical Center of Cairo
zwitterionic structure 1B is the most stable contributor University, Giza, Egypt.
2
to the resonance hybrid.
MATERIALS
R - C = N - N-R'
R - C= N - N-R'
1B
Synthesis of 7,8-dihydro-1,3-dimethyl-7-
thioxopyrimido[4,5-d]pyrimidine-2,4,5(1H,3H,6H)
trione (4)
1A
As very authorative review of the chemistry
A mixture of ethyl 6-amino-1,3-dimethyl-5-
12
of the precursors of nitriliminesas well as generation (ethoxycarbonyl)uracil (3) (11.35 g, 0.05 mole) and
2
of nitrile imines was reported in 2010 by Shawali.
Pyridopyrimidines have good biological importance.
potassium thiocyanate (6.8 g, 0.07 mol) was stirred
under reflux in dioxane (40 ml) containing 10% HCl
3
Recently some fused heterocyclic compounds (40 ml) for 20 hours. After cooling, the mixture was
containing nitrogen atom show a wide range of poured into 300 ml water, the solid precipitated was
pharmacological activities. Pyrimidopyrimidines are filtered off and crystallized from dioxane to give 4 as
annelated to uracils that have considerable interest yellow powder.
4,5
in recent years. Derivatives of pyrimidopyrimidine
display potent inhibitory properties regarding tyrosine
kinase domain of epidermalgrowth factor receptor.
%
Yield:7.5 g, 62.5%; m.p.> 300 C;IR í 3150
6
”1 1
(NH), 1705, 1680, 1630 (CO) cm ; H NMR(DMSO-
Pyrimido[4,5-d]pyrimidine fused system represent d6) d 3.2 (s, 3H, CH ), 3.45 (s, 3H, CH ), 13.75 (s,
3
3
1
3
attractive pharmacological applications such as 2H, NH); C NMR(DMSO-d6, 75 Mz) d 29.0 (CH ),
antitumor, antiviral, antioxidant, antifungal and 30.5 (CH ), 85.0 (C4a), 150.5 (C2), 161.0 (C8a),
hepatoprotective activities. Pyrimidopyrimidines 162.0 (C4), 163.5 (C5), 173.0 (C=S); MS, m/z (%)
have a ring system that can be found marine derived 240 (M , 40); Anal. Calcd for C H N O S (240.2): C,
3
7
8
9
10
3
1
1
+
8
8
4
3
natural products such as crambescidin 23 alkaloid. 40.00; H, 3.36; N, 23.32 ; S, 13.35. Found: C, 39.7;
Keeping this importance in mind herein the reactions H, 3.2; N, 22.9; S, 13.0%.
of 7-thioxopyrimdo[4,5-d]pyrimidin-2,4,5-trione with
hydrazonoyl halides will be reported.
Reactions of 4 with active chloromethylene
compounds (10b,d,f)
EꢁꢂERIMENTAL
To a solution of 4 (2.4 g, 0.01 mol) in
chloroform was added triethylamine (1.4 ml, 0.01
mol) and the mixture was stirred for 10 min at room
General
All evaporations were carried out under temperature. To the resulting clear solution was
reduced pressure at 60°C. TLC was carried out on added active chloromethylene derivative (10) (0.01
aluminum sheet silica gel 60 (Fluka) and detected mol) dropwise while stirring the reaction mixture.
by UV light. All melting points were measured on After complete addition, the reaction mixture was
an electrothermal melting point apparatus and are stirred for further 24 h at room temperature. The
1
13
uncorrected. The H and C NMR spectra were solid that precipitated was filtered off, washed with
recorded in deuterated dimethyl sulphoxide (DMSO- water, dried and finally crystallized from dioxane to
d6) at 300 MHz on a Varian Mercury VXR-300 NMR give pure 11. The compounds 11b,d,fprepared are
spectrometer (Cairo University).Chemical shifts were listed below together with their physical constants.
related to that of the solvent. The infrared spectra

GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
, 3 - ꢀ i m e t h y l - 2 , 4 , 5 ( 1 H , 3 H , 6 H ) -
Synthesis of the thiohydrazonates (7)
151
1
trioxopyrimido[4,5-d]pyrimidin-7-yl] thio-2,4-
To a solution of each of 11b,11d and 11f (10
mmol) in ethanol (40 ml) was added sodium acetate
trihydrate (1.38 g, 10 mmol) and the mixture was
cooled to 0–5 %C in an ice bath.To the resulting cold
solution was added portionwise a cold solution of
benzenediazonium chloride, prepared by diazotizing
aniline (10 mmol) dissolved in hydrochloric acid (6
M, 6 ml) with a solution of sodium nitrite (0.7 g, 10
mmol) in water (10 ml). After complete addition of
the diazonium salt, the reaction mixture was stirred
for further 12 h at room temperature. The solid
precipitated was filtered off, washed with water, dried
and crystallized from dimethyformamide/EtOH (1:1
v:v) to give the respective pure 7b, 7d and 7f.
dioxopentane (11b)
%
Yellow solid (2.0 g, 59%), m.p. 235 C; IR
O
”1
(
Kꢀr) í 3400 (NH), 1712, 1702, 1651, 1632 (C ) cm ;
1
H NMR (DMSO-d6) d 2.0 (s, 6H, 2 COCH ), 3.20
3
(
1
2
s, 3H, N-CH ), 3.4 (s, 3H, N-CH ), 4.7 (s, 1H, CH),
3
3
13
1.45 (s, 1H, NH); C NMR(DMSO-d6, 75 Mz) d
0.2 (2CH ), 27.6 (CH ), 29.5 (CH ), 69.5 (CH), 95.8
3
3
3
(C4a), 144.5 (C8a), 145.78 (C2), 154.5 (C7-S), 161.5
(
(
C4), 168.76 (C5), 172.13 (CH CO);MS m/z (%) 338
3
+
M , 17); Anal. Calcd for C H N O S (338.34): C,
13
14
4
5
4
3
6.15; H, 4.17; N, 16.56; S, 9.48. Found C, 46.1; H,
.9; N, 16.3; S, 9.5%.
E t hy l 1 , 3 - d i m e t hy l - 2 , 4 , 5 ( 1 H , 3 H , 6 H )
trioxopyrimido[4,5-d]-pyrimidin-7-yl] thio-3-
oxobutanoate (11d).
3 - ꢀ i m e t h y l - 2 , 4 , 5 ( 1 H , 3 H , 6 H ) -
trioxopyrimido[4,5-d]pyrimidin-7-yl]-N-phenyl-
2-oxopropanethiohydrazonate (7b).
0
Yellow solid (2.4 g, 65.0%), m.p. 244 C ;
%
IR (Kꢀr) í 3410 (NH), 1715, 1705, 1650, 1625 (CO)
Yellow solid (3.0 g, 75.0%), m.p. 298 C;
”
1 1
cm ; H NMR (DMSO-d6) d 1.31 (t, J = 7 Hz, 3H,
(Kꢀr) í 3350, 3235 (2NH), 1710, 1660, 1630, 1590
”
1 1
CH ),2.6 (s, 3H, CH ), 3.26 (s, 3H, N-CH ), 3.45 (s,
(CO) cm ; H NMR (DMSO-d6) d 2.50 (s, 3H, CH ),
3
3
3
3
3
H, N-CH ), 4.30 (q, J = 7 Hz, 2H, CH ), 4.80 (s, 1H,
3.26 (s, 3H, N-CH ), 3.45 (s, 3H, N-CH ), 7.27-7.40
3
2
3
3
13
CH), 12.8 (s, 1H, NH); C NMR(DMSO-d6, 75 Mz)
d16.0 (CH ), 29.0 (CH ), 31.0 (CH ), 59.0 (CH ), 70.5
(m, 5H, ArH), 9.45 (s, 1H, NH), 10.2 (s, 1H, NH);MS
+
m/z (%) 400 (M , 20); Anal. Calcd for C H N O S
3
3
3
2
17 16
6
4
(
(
1
CH), 95.0 (C4a), 148.0 (C8a), 153.8 (C2), 159.8
(400.41): C, 50.99; H, 4.03; N, 20.99; S, 8.01. Found
C, 50.6; H, 3.9; N, 20.7; S, 8.0%.
C7-S), 161.0 (C4), 163.5 (C5), 179.0 (CH CO),
3
+
89.5 (COOEt); MS m/z (%) 368 (M , 35); Anal.
Calcd for C H N O S (338.37): C, 45.65; H, 4.38;
3-ꢀimethyl-2,4,5(1H,3H,6H)-trioxopyrimido[4,5-d]
pyrimidin-7-yl]-N-phenyl-2-ethoxy-3-oxo-
ethanethiohydrazonate (7d).
1
4
16
4
6
N, 15.21; S, 8.70. Found C, 45.5; H, 4.2; N, 15.0; S,
.5%.
8
0
Yellow solid (3.2 g, 74.4%), m.p. > 300 C;
N-ꢂhenyl 1,3-dimethyl-2,4,5(1H,3H,6H)-
trioxopyrimido[4,5-d-pyrimidin-7-yl] thio-3-
oxobutanamide (11f).
(Kꢀr) í 3390, 3255 (2NH), 1705, 1680, 1640, 1585
(CO) cm ; H NMR (DMSO-d6) d 1.33 (t, J = 7 Hz,
”
1 1
3H), 3.25 (s, 3H, N-CH ), 3.45 (s, 3H, N-CH ), 4.49
3
3
%
Yellow solid (3.0 g, 72.30%), m.p. 229 C;
(q, J = 7 Hz, 2H), 7.2-7.70 (m, 5H, ArH), 10.2 (s,
+
(
(
Kꢀr) í 3400, 3250 (2NH), 1725, 1672, 1652, 1630
1H, NH), 11.0 (s, 1H, NH); MS m/z (%) 430 (M , 33);
”
1 1
CO) cm ; H NMR (DMSO-d6) d 2.53 (s, 3H, CH ),
Anal. Calcd for C H N O S (430.44): C, 50.23; H,
3
18 18
6
5
3
1
1
2
.25 (s, 3H, N-CH ), 3.42 (s, 3H, N-CH ), 4.6 (s,
4.21; N, 19.52; S, 7.45. Found C, 50.1; H, 3.89; N,
19.3; S, 7.2%.
3
3
H, CH), 7.27-7.50 (m, 5H, ArH), 9.0 (s, 1H, NH),
1
3
0.1 (s, 1H, NH); C NMR(DMSO-d6, 75 Mz) d
0.0 (CH ), 28.0 (CH ), 29.7 (CH ), 68.5 (CH), 94.5
3-ꢀimethyl-2,4,5(1H,3H,6H)-trioxopyrimido[4,5-d]
pyrimidin-7-yl]-N-phenyl-2-(phenylamino)-2-oxo-
ethanethiohydrazonate (7f).
3
3
3
(
(
(
C4a), (120.0, 126.5, 128.5, 130.0 C-Ar.), 148.0
C8a), 152.0 (C2), 161.0 (C7-S), 161.5 (C4), 164.0
C5), 165.8 (NHCO), 179.5 (COCH ). MS m/z (%)
0
Yellow solid (3.5 g, 73.3%), m.p. > 300 C;
3
+
415 (M , 40); Anal.Calcd for C H N O S (415.42):
(Kꢀr) í 3350, 3245 (2NH), 1707, 1670, 1645, 1595
18
17
5
5
”1 1
C, 52.04; H, 4.12; N, 16.86; S, 7.72. Found C, 52.0;
H, 3.9; N, 16.5; S, 7.5%.
(CO) cm ; H NMR (DMSO-d6) d 3.26 (s, 3H, N-CH ),
3
3.45 (s, 3H, N-CH ), 7.3-7.5 (m, 10H, ArH), 9.0 (s,
3

1
1
52
GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
H, NH), 9.35 (s, 1H, NH), 9.9 (s, 1H, NH); MS m/z 3-Acetyl-7,9-dimethyl-1-phenylpyrimido[4,5-d]
+
(
%) 477 (M , 48);Anal.Calcd for C H N O S (477.5): [1,2,4]triazolo[4,3-a]pyrimidine-5,6,8(1H,7H,9H)-
22
19
7
4
C, 55.34; H, 4.01; N, 20.53; S, 6.72. Found C, 55.1; trione (5b)
H, 3.7; N, 20.2; S, 6.5%.
Pale yellow solid (2.2 g, 60.1%), m.p.> 300
C; (Kꢀr) í 1710, 1690, 1640 (CO) cm ; H NMR
%
”1
1
Synthesis of 7,9-dimethylpyrimido[4,5-d][1,2,4] (DMSO-d6) d 2.5 (s, 3H, CH ), 3.1 (s, 3H, N-CH ),
3
3
13
triazolo[4,3-a]pyrimidine-5,6,8(1H,7H,9H)-trione 3.4 (s, 3H, N-CH ), 7.25-7.85 (m, 5H, ArH); C NMR
3
(
5a-g).
(DMSO-d6, 75 MHz) ä 21.0 (CH ), 33.49 (CH ), 34.28
3
3
Method A
(CH ), 90.9 (C5a), 117.0, 119.0, 123.0, 125.5, 127.5,
3
To a mixture of 7,8-dihydro-1,3-dimethyl- 132.0, (C-Ar), 138.5 (N1-C), 150.0 (C9a), 155.2 (C8),
7
-thioxopyrimido[4,5-d]pyrimidine-2,4,5(1H,3H,6H) 161.5 (C3), 162.5 (C5), 163.6 (C6), 172.0 (COCH );
3
+
trione (4) (2.4 g, 0.01 mol) and appropriate MS m/z (%) 366 (M , 35);Anal. Calcd for C H N O
17
14
6
4
hydrazonoyl halide 1 (0.01 mol) in dioxane (40 ml), (366.33): C, 55.74; H, 3.85; N, 22.94. Found C, 55.5;
trimethylamine (1.4 ml, 0.01 mol) was added. The H, 3.6; N, 22.65%.
reaction mixture was refluxed under stirring till
hydrogen sulfide ceased to evolve (6-10 h). The 3-Acetyl-7,9-dimethyl-1-(4-methylphenyl)
solvent was evaporated and the residue was treated pyrimido[4,5-d][1,2,4]-triazolo[4,3-a]pyrimidine-
with ice/HCl mixture.The solid product was collected, 5,6,8(1H,7H,9H)-trione (5c)
washed with water and crystallized from proper
solvent to give the respective 5 in 50–60% yield.
Pale yellow solid (2.3 g, 60.5%), m.p.> 300
0
”1
1
C; (Kꢀr) í 1710, 1685, 1635 (CO) cm ; H NMR
DMSO-d6) d 2.5 (s, 3H, CH ), 2.6 (s, 3H, CH ) ,
(
3
3
Method B (for 5b, 5d and 5f)
3.27 (s, 3H, N-CH ), 3.40 (s, 3H, N-CH ), 7.4-7.6 (d,
3
3
To a stirred ethanolic sodium ethoxide J = 8 Hz, 2H, ArH), 7.7-8.09 (d, J = 8 Hz, 2H, ArH);
+
solution, prepared from sodium metal (0.23 g, 10 MS m/z (%) 380 (M , 30);Anal. Calcd for C H N O
18
16
6
4
mg atom) and absolute ethanol (20 ml), was added (380.36): C, 56.84; H, 4.24; N, 22.10. Found C, 56.8;
each of the compound 7b, 7d and 7f (10 mmol) and H, 4.0; N, 22.0%.
the reaction mixture was stirred at room temperature
for 15 h, during which the starting reactants 7 9 - ꢀ i m e t h y l - 3 - e t h o x y c a r b o n y l - 1 -
dissolved and the crude product preciptated. The phenylpyrimido[4,5-d][1,2,4]-triazolo[4,3-a]
latter was filtered, washed with water, dried and pyrimidine-5,6,8(1H,7H,9H)-trione (5d)
0
finally crystallized from the proper solvent to give a
Pale yellow solid (2.2 g, 55.5%), m.p.299 C;
”1 1
product identified as 5b, 5d and 5f, respectively.The (Kꢀr) í 1730, 1695, 1650 (CO) cm ; H NMR (DMSO-
latter products proved to be identical in all respects d6) d 1.3 (t, J = 7 Hz, 3H), 3.32 (s, 3H, N-CH ), 3.55
3
(
mp, mixed mp, IR) with that obtained from 4 and the (s, 3H, N-CH ), 4.35 (q, J = 7 Hz, 2H), 7.25-7.80
respective hydrazonoyl halides 1. Their yields were (m, 5H, ArH); C NMR (DMSO-d6, 75 MHz) d 28.1
3
13
60–70%.
(CH ), 29.88 (CH ), 31.5 (CH ), 59 (CH ), 92.9 (C5a),
3 3 3 2
1
16.5, 119.0, 123.6, 125.8, 126.3, 127.6, 131.0,
9
-ꢀimethyl-1,3-diphenylpyrimido[4,5-d][1,2,4] 132.5, (C-Ar), 144.0 (N1-C), 151.0 (C9a), 154.5 (C8),
triazolo[4,3-a]pyrimidine-5,6,8(1H,7H,9H)-trione 161.0 (C3), 162.2 (C5), 163.3 (C6), 174.0 (COOEt);
+
(
5a)
MS m/z (%) 396 (M , 15);Anal. Calcd for C H N O
18
16
6
5
Pale yellow solid (2.3 g, 57.5%), m.p.> 300 (396.36): C, 54.54; H, 4.07; N, 21.2. Found C, 54.3;
0
”1 1
C;(Kꢀr) í 1695, 1630 (CO) cm ; H NMR (DMSO-d6) H, 3.7; N, 21.0%.
d 3.28 (s, 3H, N-CH ), 3.40 (s, 3H, N-CH ), 7.27-8.0
3
3
1
3
(
m, 10H, ArH); C NMR (DMSO-d6, 75 MHz) d 9-ꢀimethyl-3-ethoxycarbonyl-1-(4-methylphenyl)
2
1
7.2 (CH ), 29.3.0 (CH ), 94.2 (C5a), 127.2, 127.3, pyrimido[4,5-d][1,2,4]-triazolo[4,3-a]pyrimidine-
28.38, 130.49, 131.85, 132.42, 136.73 (C-Ar), 144.0 5,6,8(1H,7H,9H)-trione (5e)
3
3
(
(
N1-C), 148.0 (C9a), 150.0 (C8), 160.0 (C3), 161.5
C5), 163.0 (C6); MS m/z (%) 400 (M , 19); Anal.
Pale yellow solid (2.1 g, 51.0%), m.p. 267
C; (Kꢀr) í 1735, 1700, 1645 (CO) cm ; H NMR
+
0
”1
1
Calcd for C H N O (400.39): C, 62.99; H, 4.03; N, (DMSO-d6) d 1.3 (t, J = 7 Hz, 3H), 2.6 (s, 3H, CH ),
2
1
16
6
3
3
20.99. Found C, 62.75; H, 3.9; N, 20.7%.
3.27 (s, 3H, N-CH ), 3.45 (s, 3H, N-CH ), 4.4 (q, J =
3
3

GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
153
7
Hz, 2H), 7.20-7.45 (d, J = 8 Hz, 2H, ArH), 7.6-7.8
namely Staphylococcus aureus SA, Pseudomonas
aeruginosa ꢂA, Bacillus subtilis BS and Escherichia
coli EC were used to investigate the antimicrobial
activity of the compounds 5a-g. The antimicrobial
activity was assayed biologically using the diffusion
plate technique.The latter technique was carried out
by pouring a spore suspension of the fungal species
(one ml of sterile water contains approximately 108
conidia) or spreading bacterial suspension over a
solidified malt agar medium. The layer is allowed
to set for 30 min. A solution of the test compound
5a-g (1.0ug/ml) in dimethylformamide was placed
onto sterile 5mm filter paper discs and allowed to
dry, then the discs were placed on the centre of the
malt agar plate and incubated at optimum incubation
+
(
d, J = 8 Hz, 2H, ArH); MS m/z (%) 410 (M , 25);
Anal. Calcd for C H N O (410.38): C, 55.61; H,
1
8
16
6
5
4.42; N, 20.48. Found C, 55.5; H, 4.1; N, 20.3%.
9
-ꢀimethyl-3- phenylaminocarbonyl-1-
phenylpyrimido[4,5-d][1,2,4]-triazolo[4,3-a]
pyrimidine-5,6,8(1H,7H,9H)-trione (5f)
0
Yellow solid (2.2 g, 50.0%), m.p. > 300 C;
”
1 1
(
Kꢀr) í 3255 (NH), 1705, 1675, 1630 (CO) cm ; H
NMR (DMSO-d6)d 3.25 (s, 3H, N-CH ), 3.40 (s,
3
NH); C NMR (DMSO-d6, 75 MHz) d 33.0 (CH ),
3
3
H, N-CH ), 7.25-7.80 (m, 10H, ArH), 10.6 (s, 1H,
3
1
3
3
9.0 (CH ), 91.0 (C5a), 127.5, 130.0, 132.5, 138.0
3
(C-Ar), 144.0 (N1-C), 150.5 (C9a), 154.0 (C8), 161.5
+
0
(
C3), 162.5 (C5), 163.9 (C6); MS m/z (%) 443 (M ,
temperature 28 ± 2 C.Test organism growth may be
2
7); Anal. Calcd for C H N O (443.41): C, 59.59;
affected by the inhibitory action of the test compound,
so a clear zone around the disc appears as an
indication of the inhibition of test organism growth.
The size of the clearing zone is proportional to the
inhibitory action of the compound. The fungicide
Terbinafin and the bactericide Chloramphenicol
were used as standards under the same conditions.
Measurements were considered after 72 h for fungi
and 24 h for bacteria. The results are summarized
in table 1.
22
17
7
4
H, 3.86; N, 22.11. Found C, 59.3; H, 3.5; N, 21.8%.
7
1
,9-ꢀimethyl-3- phenylaminocarbonyl-
-(4-methylphenyl)-pyrimido[4,5-d][1,2,4]-
triazolo[4,3-a]pyrimidine-5,6,8(1H,7H,9H)-trione
(
5g)
0
Yellow solid (2.5 g, 54.7%), m.p. > 300 C;
”
1 1
(
Kꢀr) í 3250 (NH), 1705, 1665, 1615 (CO) cm ; H
NMR (DMSO-d6) d 3.26 (s, 3H, N-CH ), 3.45 (s, 3H,
3
N-CH ), 7.25-8.0 (m, 9H, ArH), 10.31 (s, 1H, NH);
3
+
MS m/z (%) 457 (M , 30);Anal.Calcd for C H N O
RESULTS ANꢀ ꢀISCUSSION
23
19
7
4
(
457.44):C, 60.39;H, 4.19;N, 21.43.Found C, 60.0;
H, 4.0; N, 21.1%.
The starting 7,8-dihydro-1,3-dimethyl-7-
thioxopyrimido[4,5-d]pyrimidine-2,4,5(1H,3H,6H)
trione(4) which has not been reported hither to was
prepared by heating of 6-amino-1,3-dimethyluracil
(2)with ethyl chloroformate in pyridine to get ethyl
Antimicrobial assay
Cultures of four fungal species namely
Aspergillusfumigatus AF, Penicilliumitalicum
ꢂI,Syncephalastrumracemosum SR and Candida
albicans. CA as well as four bacterial species
12
6-amino-1,3-dimethyl-5-(ethoxycarbonyl) uracil (3),
followed by reaction with potassium thiocyanate in
1
62 -163
1
70 - 175
161 - 164
O
N
O
R'
X
O
O
N
R
N
N
N
H C
3
N
N
N
R
X
O
N
R
N
Ar
CH3
R'
I
5
II
Chart 1: 13C comparison between different triazole derivatives

1
1
54
GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
1
3
,4-dioxane containing 10% HCl. The structure (see Experimental), the isolated products were
of compound 4 was confirmed by spectral and assigned the structure of 7,9-dimethylpyrimido[4,5-d]
elemental analysis data (see Experimental). The [1,2,4]triazolo[4,3-a]pyrimidine-5,6,8(1H,7H,9H)-
1
4-16
hydrazonoyl halides 1a–g
were prepared by trione (5) rather than the isomeric structure of
literature methods.Reaction of 4 with each of the 1,3-dimethylpyrimido[5,4-e][1,2,4]triazolo[4,3-a]
hydrazonoyl halides 1a–g was carried out in 1,4- pyrimidine-2,4,5(1H,3H,7H)-trione (6) (scheme 1).
dioxane in the presence of triethylamine while For example, the d value (163.0) for the carbonyl
13
heating the reaction mixture under reflux till in carbon signal in the C nmr spectrum of 5a, takenas
allcases, hydrogen sulfide evolved during the course an example of the series prepared is similar to that of
of the reaction and so stirring of the reactionmixture I (d161–164) and different fromits isomeric structure
14
was continued till hydrogen sulfide ceased to evolve II (d170–175) (chart 1). This finding ruled out the
6-10 h). Work up of the reaction mixture afforded, acylimino typestructure 5 for the isolated products.
(
in each case, one isolable product as evidenced
by tlc analysis of the crude product. On the basis
of elemental analyses and IR, H and CNMR thione 2 and hydrazonoyl halides 1 couldbeaccounted
The formation of compounds 5 from the
1
13
spectra which showed all the expected signals for by one of the two pathways indicated in scheme
O
O
COOEt
3
H C
N
H
3
C
N
ClCOOEt
Pyridine
R-C(Cl)=NNHAr
1
NH
2
NH
2
O
N
O
N
CH
3
CH
3
3
3
Et N
2
O
O
KSCN
Dioxane, 10% HCl
H
3
C
N
N H
S
+
R-C
N-NAr
O
N
N
H
1
A
CH
3
4
Dioxane/
Et
3
N
O
O
N
O
O
R
3
H C
N
N
H
3
C
N
N
Ph
N
N
N
N
O
N
O
N
N
5
CH
3
CH
3
Ar
Ar
6
1,5,6
R
Ar
a
Ph
Ph
Ph
b
COCH3
c
COCH
3
6 5 3
C H -CH -4
d
e
COOEt
COOEt
Ph
C
6
H
5
3
-CH -4
f
CONHPh
CONHPh
Ph
g
6 5 3
C H -CH -4
Scheme 1: Synthesis of 7,8-dihydro-1,3-dimethyl-7-thioxopyrimido[4,5-d]pyrimidine-
,4,5(1H,3H,6H)trione (4) and its reaction with hydrazonoyl chloride (1)
2

GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
155
2
.As depicted in this scheme,it is suggested that the
suggested route a and the involvement of 7 and 8
as intermediates in the formation of 4 by this route
were evidenced by alternate synthesis of 5b, 5d and
5f (Scheme 3).
studied reactions started with the hydrazonoylation
of 2 to give therespective thiohydrazonate esters 7.
17,18
This is followed by Smiles type rearrangement
to form the respective thiohydrazides 8, which in
turn underwent cyclization to give 5 as end products
route a, Scheme 2).
It seems that both intermediates 7 and 8 are
of
7
Thus, treatment of 2 with each of 3-chloro-
2,4-pentanedione (10b), ethyl a-chloroacetoacetate
(10d) and á-chloroacetoacetanilide(10f)inchloroform
inthepresenceoftriethylamineaffordedtherespective
substituted products 11b, 11d and 11f. Coupling of
each of these compounds with benzenediazonium
chloride in ethanol in thepresence of sodium
acetate yielded the thiohydrazonates 7b, 7d and
7f, respectively (Scheme 2) via Japp-Klingemann
(
consumed,under the employed reaction conditions
as soon as they are formed since all attempts to
isolate them failed. Alternatively, reaction of the
thione 2 with hydrazonoyl halides 1 starts with
the formation of the amidrazone intermediates 9
which cyclize to give 5 (route b, Scheme 1). This
alternative pathway has been ruled out, however, on
the basis that alkylation and acylation of 2-thiouracil
derivatives have been known to give S-alkyl and
2
2
cleavage of the acetyl group. Treatment of the
products 7 with sodium ethoxide in ethanol afforded
the respective compounds 5b, 5d and 5f identical
in all respects with those obtained from reactions
19-22
S-acyl derivatives, respectively. Furthermore the
O
O
route b
H C
route a
Cl
3
N
N H
S
+
R-C=N-NH-Ar
O
N
N
H
-HCl
-HCl
CH3
1
4
O
O
N
O
O
R
C
H
3
C
H
H C
N
N
3
N
N
N
N
N
Ar
O
N
S
C
H
O
N
N
H
S
HN
Ar
CH3
CH3
R
7
9
O
N
O
R
O
O
N
C
H C
H C
H
3
N
N
3
N
N
H
N
-H2S
N
S
O
N
5
O
N
N
C
R
N
-H2S
CH3
CH3
Ar
Ar
8
O
O
-H2S
H C
3
N
N
Ar
O
N
N
N
CH3
C
N
R
6
Scheme 2: Mechanistic routes of reaction of 7,8-dihydro-1,3-dimethyl-7-thioxopyrimido[4,5-d]pyrimidine-
,4,5(1H,3H,6H)trione (4) with hydrazonoyl chloride (1)
2

GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
of 2 with each of 1b, 1d and 1f, respectively. This
Antimicrobial activity
156
finding indicates that 7 and 8 are intermediates in the
studied reactionsof 1 with 3 and they are consumed
as soon as they are formed under the employed
reaction conditions. Finally, the suggestion that the
site of cyclization of the thiohydrazide intermediates
The compounds 5a-g were tested for
their antimicrobial activities against four fungal
speciesnamely Aspergillusfumigatus AF,
Penicilliumitalicum ꢂI, Syncephalastrumracemosum
SR and Candida albicans CA as well as four
bacteria species namely Staphylococcus aureus SA,
Pseudomonas aeruginosa ꢂA, Bacillus subtilis BS
and Escherichia coli EC.The organisms were tested
against the activity of solutions of concentration of
1.0mg/ml of each compoundand using inhibition
zone diameter in cm (IZD) as criterion for the
antimicrobial activity. Terbinafin as an antifungal
agent and Chloramphenicol as an antibacterial
agent were used asreferences to evaluate the
potency of the tested compounds under the same
8
involves N-3 rather than N-1 to give 5is consistent
with literature reports. For example, ithas been
reported that cyclization of 2-substituted-uracil
derivatives having no substituenton N-3 proceeds
regioselectively to give the respective 1,2,4-
23-25
triazolo[4,3-a]pyrimidin-5(1H)-ones.
In conclusion, the studied reactions of
hydrazonoyl halides 1 with the thione 2 are both site
and regioselective and lead to the title ring system.
O
O
CHCl / Et3N
H C
3
3
N
N H
S
+
RCO-CH(Cl)COCH3
10
O
N
N
H
CH3
-HCl
4
O
O
O
O
N
H C
H
H
3
N
N
H C
3
N
PhN Cl
N
2
COCH3
CH
N
N
Ph
O
N
N
S
C
H
O
N
S
EtOH/ NaOAc
CH3
CH3
R
R
7
11
EtOH/ NaOEt
O
O
R
O
N
O
C
H C
3
H
H C
3
N
N
N
N
H
N
N
S
O
N
N
5
O
N
N
C
R
-H
2
S
N
CH3
CH3
Ph
Ph
8
R , b = CH CO, d= EtOCO, f = PhNHCO
3
Scheme 3: Alternative method of synthesis of 7,9-dimethylpyrimido[4,5-d][1,2,4]triazolo[4,3-a]pyrimidine-
,6,8(1H,7H,9H)-trione (5)
5

GOꢀOURI et al., Orient. J. Chem., Vol. 32(1), 149-158 (2016)
157
Table 1: Antimicrobial activity of the products 5a-g
f
Micro-Organism/IZD(cm)
Compd AF
No.
PI
SR
CA
SA
PA
ꢀS
EC
5
5
5
5
5
5
5
a
b
c
d
e
f
++
+
+
+
+
+
0
0
0
+
0
0
0
+
0
0
0
0
0
+
0
0
0
0
+
+
++
++
+
++
+
+
+
++
0
0
0
+
+
+
0
0
+
+
0
0
0
+
++
0
0
0
0
+
0
0
+
++
g
a
CA
TE
++
++
b
++
++
++
++
f50 ml of solution in DMF whose concentration 1.0m g/ml was tested.
a Chloramphenicol as standard antibacterial agent, bTerbinfin as standard
antifungal agent, ++ inhibition value 0.6-1.0 cm; +, inhibition value 0.1-0.5 cm
beyond control; 0, no inhibition detected.
conditions. Theresults are depicted in table 1. The
results reveal that compounds 5a, 5b, 5d and 5g
exhibited thehighest degree of inhibition against
the tested organisms AF and SA, respectively, their
activity is similarto that of the standard antifungal
and antibacterial agents used. All other compounds
eitherexhibit no activity or being less active against
the tested species.
convenient methodology for synthesis of numerous
1,2,4-triazole derivatives, namely functionalized
7,9-dimethylpyrimido[4,5-d][1,2,4]triazolo[4,3-a]
pyrimidine-5,6,8(1H,7H,9H)-trione derivatives.Some
compounds prepared showed moderate, whereas
other compounds showed weak antimicrobial
activity.
ACKNOꢃLEꢀGEMENT
CONCLUSION
The author thanksTaif University, Taif, Saudi Arabia
for the financial support under project number 3674-
435-1.
The present project has outlined the
importance of tandem in situ generation and 1,5-
electrocyclization of N-hetarylnitrilimines as a
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