Scientific paper
A Convenient Methods for Synthetic Isomeric Structures of Pyrimido-1,2,4-triazine Derivatives as Biocidal Agents
Kamelia M. El-Mahdy1* and Reda M. Abdel-Rahman2
1 Chemistry Department, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt
2 Chemistry Department, Faculty of Science, King Abdul-Aziz University, P.O. Box 80203, Jeddah, 21589,
Kingdom of Saudi Arabia
* Corresponding author: E-mail: kmelmahdy@gmail.com
Received: 30-10-2010
Abstract
Some new isomeric structures of pyrimido[2,1-c][1,2,4]triazines 4-8 and 10-14 have been synthesized via the ring closure reactions of 2-hydrazinyl-1-methylpyrimidine 3 and/or 2-hydrazinopyrimidine 9 with acyclic and cyclic oxygen compounds under various conditions. Structures of the targets have been established from their elemental analyses and spectral data (UV, IR, 1H/13C NMR and mass spectrometry). Most of the obtained compounds were evaluated as antimicrobial agents and compared with pipericillin and mycostatine as standard antibiotics. Only compound 7 had highly biocidal effects.
Keywords: Synthesis, isomeric structures, pyrimidotriazines, biocidal effects.
1. Introduction
Polyfunctional pyrimidines are highly reactive intermediates for building various heterobicyclic nitrogen systems which exhibit a broad spectrum of biological and pharmacological properties.1-3 Diverse pharmacological properties of pyrimidine derivatives, such as anticancer,4-6 antiinflammatory,7 8 antimalarial,9 antiviral,10 and antidepressant,11 and fused pyrimidines as antimicrobial,12-14 antibacterial,15 antifungal,16 and antihypertensive17 support the importance of their synthesis. On the other hand, 1,2,4-triazines have been proved to be very useful in the synthetic chemistry, especially in various one-step hete-rocyclization reactions proceeding by insertion of two carbon atoms bearing bifunctional groups.18-20 The structural diversity and biological significance of 1,2,4-triazi-nes have aroused much attention due to the wide range of applications.21-25 In view of all these facts and as the continuation of our work on the synthesis of new heterocyclic derivatives,26 the main aim of the present work is the study of the reactivity of polyfunctional pyrimidines with the aim of constructing fused heterobicyclic nitrogen systems containing 1,2,4-triazine moiety starting from 2-hydrazi-nopyrimidine via two routes (A and B), in view of the bio-cidal effects of the final products.
a) O	b) o
The isomeric structure targets
2. Results and Discussion
The original objective of this work is the formation of isomeric fused pyrimidotriazines via nitrogen atoms. Thus, starting with methylation of 4-(2-hydroxy-1-naph-thyl)-2-mercapto-6-oxo-1,6-dihydropyrimidine-5-carbo-nitrile (1),27 using methyl iodide in stirring with aqueous KOH for one day, yielded 4-(2-hydroxy-1-naphthyl)-1-methyl-2-(methylthio)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile (2) which on hydrazinolysis by refluxing with hydrazine hydrate in ethanol produced the corresponding 2-hydrazinyl-1-methylpyrimidine 3 (Scheme 1). Compound 3 was used as starting material for building of pyri-mido[2,1-c][1,2,4]triazine via route B. UV absorption
spectrum of 2 showed Àmax 434 nm, while that of 3 exhibited Àmax 477 nm. The presence of hydrazino group in compound 3 shifted Àmax to longer wave length more than methylthio group in compound 2.
When 2-hydrazinyl-1-methylpyrimidine 3 was subjected to react with monochloroacetic acid and/or chloroa-cetyl chloride in warm DMF the isomeric structures 4,8-dioxo-pyrimido[2,1-c][1,2,4]triazine 4 and 3,8-dioxopyri-mido[2,1-c][1,2,4]triazine 5, respectively, were formed (Scheme 1).
Structures of 4 and 5 were elucidated from their spectral measurements. IR spectrum of 4 showed the characteristic bands of NH, CH2, C=O, C=N with bending of CH2 at v 3250, 2927, 1710, 1670, 1592 and 1468 cm-1, while that of 5 showed bands attributed to NH, CH2, C=O, C=N with bending of CH2 at 3300, 2949, 1704, 1690, 1597 and 1472 cm-1 which confirm the postulated structure. 1H NMR spectrum of 4 showed signals at 5 9.92, 4.28 and 3.22 ppm for the NH, CH2 and CH3 protons, in addition to aromatic protons at 5 7.83-7.47 ppm, while that of 5 exhibited signals at 5 9.91, 4.31 and 3.23 ppm for NH, CH2 and CH3 protons with aromatic protons at 5 7.787.39 ppm.
Heterocyclization of 2-hydrazinyl-1-methylpyrimi-dine 3 via refluxing with diethyl oxalate in dry THF resulted28 in 6-(2-hydroxy-1-naphthyl)-9-methyl-3,4,8-trioxo-3,4,8,9-tetrahydro-2H- pyrimido[2,1-c][1,2,4]triazine-7-carbonitrile (6) (Scheme 1).
IR spectrum of 6 showed bands at 3150 cm1 for NH, 1710, 1680 and 1650 cm1 attributed to three C=O groups, in addition to 2920, 1480 cm1 for stretching and bending of CH3 functional group.
Behavior of isatin towards bi-nucleophilic reagents was studied to afford the heteropolycyclic systems 7 and 8, the outcome of the reaction mainly depends on the type of the solvent used and the pH of the medium. Thus, compound 3 was refluxed with 1H-indole-2,3-dione in DMF affording 1-(2-hydroxy-1-naphthyl)-4-methyl-3-oxo-3,4-dihydropyrimido[2',1':3,4][1,2,4]triazino[5,6-fc]indole-2-carbonitrile (7), while when the reaction was carried out in boiling aqueous sodium hydroxide produced 3-(2-ami-nophenyl)-6-(2-hydroxy-1-naphthyl)-9-methyl-4,8-dio-xo-8,9-dihydro-4H-pyrimido[2,1-c][1,2,4]triazine-7-car-bonitrile (8) (Scheme 2).
The structural assignment of targets 7 and 8 was deduced from spectral data. IR spectrum of 7 showed only ab-
Scheme 1
XQ
Ar N NHNH,
HO
Ar a II
aq.NaOH
Scheme 2
sorption band at 1690 cm-1 for C=O with lack of NH2 or NH groups, while that of 8 exhibited bands at 3300, 1700, 1690 cm-1 attributed to NH2, two C=O functional groups. The structure of 7 was supported by its mass spectrum which showed signal at m/z 358 [M+-60(-HC0NHMe)], while its molecular ion peak was not observed, and the base peak at m/z 169 (1,2,4-triazinoindole radical, 100%) (Fig. 1).
MS spectrum of 8 recorded signal at m/z [M+-137, (C7H11N3)] with a base peak at m/z 58 (Fig. 2).
The IR spectra of all the new compounds in the solution (CHCl3 used as solvent) showed the disappearance of the carbonyl functional groups between 1700-1600 cm-1. This is due to a type of H-bonding and/or electrostatic attraction between the different functional groups in both the compounds and the solvent. These electronic factors confirmed the inhibition behavior of the functional groups in the new compounds obtained towards the functional groups in the tested microorganisms, resulted in the asymmetric distribution of electronic charge on the complexes-system (Fig. 3).
169 (100)
I
[170 (50)]' +
Fig. 1: Fragmentation Pattern of Compound 7
116(115,74,50)
O MP	8- M 436 (M-137,2%)
11 i! —C—N
58 (100)
70 (62)
HO
134 (5)
126 (18)
NC^-C—CH HO
194(1)
-CN
CH=C HO
169 (2)
nh2
H2N„
- 137(1) -1 0
J-
N-Me
N=i
112(10) -1
(3)
NH„
93 (5)
,Me
HM'
N^NH 126(18)
170 (5)
Fig. 2: Fragmentation Pattern of Compound 8
It is well know that the greater nucleophilicity of hydrazino group,19 at the position 2 of the pyrimidine nucleus makes position 1 and/or 3 susceptible for heterocycli-zation via attack of various electrophilic reagents. The product of this reaction has two possible structures (A) and (C), but structure (A) is favorable; it can be seen that the aryl group in structure (C) must be twisted out of plane of the pyrimidine ring because of steric interference. This aryl group would be expected to give a compact signal in the NMR spectrum. However, the aryl group in structure (A) should be coplanar with the pyrimidine ring. This indicates that structure (A) is the correct one for the reaction product. This is in agreement with the reported NMR spectrum for other similar compounds.29-31
a)
O
c)
Ar N NHNH, At N NHNH
Removal of SH group from the compound 1 with hydrazine hydrate led to the formation of 4-aryl-2-hydrazi-no-6-oxo-1,6-dihydropyrimidin-5-carbonitrile (9).27 Thus, the isomeric structures 3,6-dioxopyrimido[2,1-c][1,2,4] triazine 10 and 4-hydroxy-6-oxopyrimido[2,1-c][ 1,2,4] triazine 11 were isolated after treating 2-hydrazinopyrimi-dine 9 with chloroacetyl chloride and/or monochloroacetic acid in warm DMF. Further, reaction of 2-hydrazinopyrimi-dine 9 with 1,2-dichloroethane in a basic medium furnished 8-(1H-indol-3-yl)-6-oxo-1,3,4,6-tetrahydro-2H-pyrimi-do[2,1-c][ 1,2,4]triazine-7-carbonitrile (12) (Scheme 3).
Structures of both 10 and 11 can be deduced from their spectral data. UV absorption spectrum of 10 exhibited ^max 405 nm, while that of 11 is 387 nm, which indicate that compound 10 contains two carbonyl groups but compound 11 contains only one carbonyl group and one hydroxyl group. IR spectrum of 10 showed two characteristic bands for C=O at 1743 and 1693 cm-1, with bands at 3403 and 2911, 1449 cm-1 attributed to NH, stretching and bending of CH2 groups. IR spectrum of 11 showed only characteristic band for C=O at 1673 cm-1, with a band at 3602 cm-1 for the OH group. This confirms the stronger presence of tautomerism in the compound 11 than compound 10. The IR pyrimidine carbonyl frequency of compound 11 is lower than that of compound 10 indicating hydrogen bonding as expected for compound 11 where the C=O and the OH groups may interact intramo-lecularly.
1H NMR spectrum of 11 showed signals at 5 11.12 and 8.98 ppm attributed to OH and NH protons. The mass spectrometry of 10 did not exhibit a molecular ion peak but it showed a peak at m/z 278 attributed to [M-CO, 2%], and the base peak at m/z 182 (C11H8N3 radical, 100%). IR spectrum of 12 displayed absorption bands at 3203, 1672 and 1496 cm-1 due to NH, C=O and bending of CH2
groups. UV absorption spectrum of 12 showed ^max at 395 nm. The mass spectrometry of 12 did not show a molecular ion peak but it exhibited a peak at m/z 264 attributed to [M-C2H4, 4%], and the base peak at m/z 182 (C11H8N3 radical, 100%).
Perhydropyrimido[2,1-c][1,2,4]triazine 13 was obtained from reaction of 2-hydrazinopyrimidine 9 with active alkylating agent such as p-bromophenacyl bromide in boiling alkaline medium (Scheme 4). Structure of 13 was elucidated from its spectral data. UV absorption spectrum of 13 showed ^max at 415 nm. IR spectrum of 13 showed the absorption bands at 3433, 1743 and 1445 cm1 attributed to NH, C=O and bending of CH2 groups. The mass spectrometry of 13 recorded a peak at m/z 468 (M+2, 25%) and the base peak at m/z 159 (p-bromophenyl radical, 100%).
Polyfunctional pyrimidotriazines, such as 8-(3,4-di-methoxyphenyl)-3-methyl-4,6-dioxo-1,6-dihydro-4H-pyrimido[2,1-c][1,2,4]triazine-7-carbonitrile (14) was also isolated from cyclocondensation of 2-hydrazinopyrimi-dine 9 with sodium pyruvate under reflux with sodium hydroxide solution (Scheme 4).
Gram positive bacteria, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus (recorded on nutrient and Maclonky agar) and also against two fungi, Candida albicans and Aspergillus fumigatus which was isolated on Sabouraud Dextrose agar (oxide) using the agar diffusion disk method.32,33
The antimicrobial properties of the tested compounds were established by placing presterilized filter paper disks (11 mm diameter) impregnated with 50 mg/disk using DMSO as a solvent which showed no inhibition zones (IZ) of the tested compounds. IZ were measured after 24 h incubation at 37 °C for bacteria and after 5 days incubation at 28 °C for fungi. The minimal inhibition concentrations (MIC) were estimated and recorded (Table 1). Reference antibiotics disks (11 mm in diameter) supplied by (BBL) pipericillin (PIP) and fungicide mycostatine were used for comparison.
Quantitative Structure Activity Relationship (QSAR) study for the obtained results showed that compound 7 only exhibited a higher biocidal activity by increasing of concentrations, increasing the biocidal ef-
OMe
Scheme 4
IR spectrum of 14 showed peaks at 3289 (NH), 1732, 1662 (two C=O groups) and 1472 cm1 (deformation of CH3).
3. Biological Activities
Most of the synthesized compounds have been evaluated in vitro against Gram negative bacteria and
fects (Table 2), which is due to the presence of a large number of n electrons in the conjugation with o electrons in the fused heteropolycyclic nitrogen system. This extension of electronic conjugation decreases the electron energetic barrier from the donor to acceptor centers, which increases the electron delocalization ion through all aromatic positions leading to a higher biocidal activity. These data agree with other similar investiga-tions.34,35
Table 1: The antimicrobial activities of some synthesized compounds
Tested			Inhibition Zones (at 50 mg/disk)			
Compounds	E. coli	K. pneumoniae	P. aeruginosa	S. aureus	C. albicans	A. fumigatus
and Standards						
3	14	14	14	11	14	14
7	18	18	16	22	14	14
8	14	14	14	11	14	14
P	17	17	20	27	11	11
M	11	11	11	12	34	40
P: pipericillin, M: mycostatine Highly active: IZ > 19 mm; moderately active: IZ 15-19 mm; slightly active: IZ = 11-14 mm
Table 2: Minimal Inhibitory Concentration (MIC) at the highly bi-oactive compound 7
Compd. 7		Inhibition Zones (mm)		
Conc.	E. coli	K. pneumoniae	P. aeruginosa	S. aureus
mg/disk				
50	18	18	16	22
40	14	12	12	20
30	11	11	11	16
20	-	-	11	12
4. Experimental Section
Synthesis of 2-hydrazinyl-4-(2-hydroxy-1-naphthyl)-1-methyl-6-oxo-1,6-dihydropyrimidine-5-carbonitrile (3)
A mixture of compound 2 (3.23 g, 0.01 mol) and hydrazine hydrate (1 mL, 0.02 mol) in ethanol (100 mL) was refluxed for 4 h, cooled, then added a few drops of dil. acetic acid. The solid thus obtained was filtered off and recrystallized from EtOH-H2O to give 3. Yield 60%, mp 304-305 °C. IR (KBr) v 3350 (OH), 3130 (NH), 2965 (CH), 2223 (CN), 1660 (CO) cm-1. 1H NMR (DMSO-d6) 5 3.12 (s, 3H, NCH3), 4.45 (bs, 2H, NH2), 5.57 (s, 1H, OH), 7.48-7.79 (m, 6H, Ar-H), 8.93 (s, 1H, NH). MS m/z 307 (M+, 25%). Anal. Calcd for C16H13N5O2: C, 62.53; H, 4.26; N, 22.79. Found: C, 63.00; H, 4.28; N, 22.23.
All melting points are uncorrected and measured using an open capillary tube by Stuart Scientific melting point SMPI (U.K). The IR spectra were recorded in the solid state as KBr discs or in CHCl3 solution on a Per-kin-Elmer spectrometer RXIFT-IR system No. 55529. 1H and 13C NMR were determined in solutions in DMSO-dfi with a Bruker Avance DPX 400 MHz using TMS as an internal standard. Mass spectra were measured on GCMS-Q 100-EX spectrometer. Electronic absorption spectra were recorded on Shimadzu UV and visible 3101 PC spectrometer. Microanalyses were performed by the micro analytical laboratory of the Department of Chemistry, Faculty of Science, King Abdul-Aziz University, Jeddah.
Compounds 1 and 9 were prepared according to the reported methods.27
Synthesis of 4-(2-hydroxy-1-naphthyl)-1-methyl-2-(methylthio)-6-oxo-1,6-dihydro-pyrimidine-5-carboni-trile (2)
A mixture of compound 1 (2.95 g, 0.01 mol) and methyl iodide (1.24 mL, 0.02 mol) in aqueous KOH (1%, 100 mL) was stirred for 24 h, then filtered off, washed with EtOH and recrystallized from ethanol to give 2. Yield 65%, mp 258-259 °C. IR (KBr) v 3400 (OH), 3290 (NH), 2978 (CH), 2220 (CN), 1668 (CO) cm-1. 1H NMR (DMSO-dfi) 5 2.70 (s, 3H, SCH3), 3.34 (s, 3H, NCH3), 5.67 (s, 1H, OH), 7.49-7.83 (m, 6H, Ar-H). MS m/z 323 (M+, 30%). Anal. Calcd for C17H13N3O2S: C, 63.14; H, 4.05; N, 12.99; S, 9.92. Found: C, (53.28; H, 4.00; N, 12.71, S, 9.97.
Synthesis of 6-(2-hydroxy-1-naphthyl)-9-methyl-4,8-dioxo-3,4,8,9-tetrahydro-2H-pyrimido[2,1-c][1,2,4]tri-azine-7-carbonitrile (4)
A mixture of compound 3 (3.07 g, 0.01 mol) and monochloroacetic acid (0.945 g, 0.01 mol) in DMF (50 mL) was refluxed for 2 h, cooled, then poured onto ice. The obtained solid was filtered off and recrystallized from DMF-H2O to give 4. Yield 70%, mp 278-280 °C. IR (KBr) v 23440 (OH), 3250 (NH), 2927 (CH), 2222 (CN), 1710, 1670 (CO) cm-1. 1H NMR (DMSO-d6) 5 3.22 (s, 3H, NCH3), 4.28 (s, 2H, CH2), 5.29 (s, 1H, OH), 7.47-7.83 (m, 6H, Ar-H), 9.92 (s, 1H, NH). Anal. Calcd for C18H13N5O3: C, 62.24; H, 3.77; N, 20.16. Found: C, 62.20; H, 3.774; N, 20.11.
Synthesis of 6-(2-hydroxy-1-naphthyl)-9-methyl-3,8-dioxo-3,4,8,9-tetrahydro-2H-pyrimido[2,1-c][1,2,4] triazine-7-carbonitrile (5)
To a solution of compound 3 (3.07 g, 0.01 mol) in DMF (50 mL), chloroacetyl chloride (0.79 mL, 0.01 mol) was added drop wise. The solid thus obtained was filtered off and recrystallized from DMF-H2O to give 5. Yield 65%, mp 298-300 °C. IR (KBr) v 3410 (OH), 3300 (NH), 2949 (CH), 2225 (CN), 1704, 1690 (CO) cm-1. 1H NMR (DMSO-d6) 5 3.23 (s, 3H, NCH3), 4.31 (s, 2H, CH2), 5.28 (s, 1H, OH), 7.39-7.78 (m, 6H, Ar-H), 9.91 (s, 1H, NH). MS m/z 347 (M+, 5%). Anal. Calcd for C18H13N5O3: C, 62.24; H, 3.77; N, 20.16. Found: C, 62.28; H, 3.76; N, 19.98.
Synthesis of 6-(2-hydroxy-1-naphthyl)-9-methyl-3,4,8-trioxo-3,4,8,9-tetrahydro-2_ff-pyrimido[2,1-c][1,2,4] triazine-7-carbonitrile (6)
Equimolar amounts of compound 3 (3.07 g, 0.01 mol) and diethyl oxalate (1.35 mL, 0.01 mol) in THF (50 mL) were refluxed for 12 h and then cooled. The solid so obtained was filtered off and recrystallized from dioxane to give 6. Yield 65%, mp 316-317 °C. IR (KBr) v 3450 (OH), 3150 (NH), 2920 (CH), 2216 (CN), 1710, 1680, 1650 (CO) cm-1. 1H NMR (DMSO-d6) 5 3.18 (s, 3H, NCH3), 5.19 (s, 1H, OH), 7.38-7.85 (m, 6H, Ar-H), 9.53 (s, 1H, NH). 13C NMR (DMSO-d6) 5 167.1, 163.1, 162.5, 161.4, 155.3, 153.7, 131.8, 130.0, 128.4, 126.5, 123.4, 122.1, 119.7, 116.7, 115.5, 76.5, 24.8. MS m/z 361 (M+, 12%). Anal. Calcd for C18H11N5O4: C, 59.84; H, 3.07; N, 19.38. Found: C, 59.78; H, 3.04; N, 19.15.
Synthesis of 1-(2-hydroxy-1-naphthyl)-4-methyl-3-oxo -3,4-dihydropyrimido[2',1':3,4][1,2,4]triazino[5,6-£] indole-2-carbonitrile (7)
A mixture of compound 3 (3.07 g, 0.01 mol) and isatin (1.47 g, 0.01 mol) in DMF (50 mL) was refluxed for 4 h, cooled, then poured onto crushed ice. The produced solid was filtered off and recrystallized from DMF to give 7. Yield 71%, mp 306-308 °C. IR (KBr) v 3420 (OH), 2950 (CH), 2230 (CN), 1690 (CO) cm-1. 1H NMR (DMSO-d6) 5 3.23 (s, 3H, NCH3), 5.54 (s, 1H, OH), 7.18-7.99 (m, 10H, Ar-H). Anal. Calcd for C24H14N6O2: C, 68.89; H, 3.37; N, 20.09. Found: C, 68.88; H, 3.34; N, 19.66.
Synthesis of 3-(2-aminophenyl)-6-(2-hydroxy-1-naph-thyl)-9-methyl-4,8-dioxo-8,9-dihydro-4_ff-pyrimido[2, 1-c][1,2,4]triazine-7-carbonitrile (8)
To a solution of isatin (1.47 g, 0.01 mol) in aqueous NaOH (5%, 100 mL), warmed for 5 min, compound 3 (3.07 g, 0.01 mol) was added and refluxed for 2 h, cooled, then poured onto ice with HCl (36%, 5 mL) for neutralization. The resulting solid was filtered off and recrystallized from EtOH to give 8. Yield 80%, mp 310-312 °C. IR (KBr) v 3450 (OH), 3300, 3230 (NH2), 2930 (CH), 2205 (CN), 1700, 1690 (CO) cm-1. 1H NMR (DMSO-d6) 5 3.18 (s, 3H, NCH3), 4.27 (bs, 2H, NH2), 5.36 (s, 1H, OH), 7.29-7.87 (m, 10H, Ar-H). Anal. Calcd for C24H16N6O3: C, 66.05; H, 3.70; N, 19.26. Found: C, 66.20; H, 3.68; N, 19.06.
Synthesis of 8-(1_ff-indol-3-yl)-3,6-dioxo-1,3,4,6-tetrah-ydro-2_ff-pyrimido[2,1-c][1,2,4]triazine-7-carbonitrile (10)
To a solution of compound 9 (2.66 g, 0.01 mol) in DMF (30 mL), chloroacetyl chloride (0.79 mL, 0.01 mol) was added drop wise at room temperature. The mixture was refluxed for 2 h, cooled, then poured onto ice. The precipitate was filtered off and recrystallized from THF to give 10. Yield 85%, mp 240-241 °C. IR (KBr) v 3403
(NH), 2911 (CH), 2218 (CN), 1743, 1693 (CO) cm-1. 1H NMR (DMSO-d6) 5 4.42 (s, 2H, CH ), 7.38-8.57 (m, 5H, Ar-H), 9.24 (s, 2H, 2NH), 10.90 (bs2, 1H, NH of indole). Anal. Calcd for C15H10N6O2: C, 58.82; H, 3.29; N, 27.44. Found: C, 58.80; H, 3.30; NT, 27.17.
Synthesis of 4-hydroxy-8-(1_ff-indol-3-yl)-6-oxo-1,6-di-hydro-2_ff-pyrimido[2,1-c][1,2,4]triazine-7-carbonitri-le (11)
Equimolar amounts of compound 9 (2.66 g, 0.01 mol) and monochloroacetic acid (0.945 g, 0.01 mol) in DMF (30 mL) were refluxed for 4 h, then poured onto ice. The separated solid was filtered off and recrystallized from dioxane to give 11. Yield 73%, mp 268-270 °C. IR (KBr) v 3602 (OH), 2215 (CN), 1673 (CO) cm-1. 1H NMR (DMSO-d6) 5 7.29-8.38 (m, 6H, Ar-H), 8.98 (s, 2H, 2NH), 10.36 (bs, 1H, NH of indole), 11.12 (s, 1H, OH). Anal. Calcd for C15H10N6O2: C, 58.82; H, 3.29; N, 27.44. Found: C, 58.78; H, 3.28; N, 26.90.
Synthesis of 8-(1_ff-indol-3-yl)-6-oxo-1,3,4,6-tetrahyd-ro-2_ff-pyrimido[2,1-c][1,2,4]triazine-7-carbonitrile
(12)
A mixture of compound 9 (2.66 g, 0.01 mol) and 1,2-dichloroethane (0.78 mL, 0.01 mol) in DMF (30 mL) was refluxed for 2 h, then poured onto crushed ice. The solid which separated was filtered off and dried, then recrystallized from THF to give 12. Yield 65%, mp 300-301 °C. IR (KBr) v 3203 (NH), 2920 (CH), 2220 (CN), 1672 (CO) cm-1. 1H NMR (DMSO-d6) 5 4.58 (s, 4H, CH2CH2), 7.29-8.48 (m, 5H, Ar-H), 96.56 (s, 2H, 2NH), 10.70 (bs, 1H, NH of indole). Anal. Calcd for C15H12N6O: C, 61.64; H, 4.14; N, 28.75. Found: C, 61.58; H, 4.18; N, 28.32.
Synthesis of 3-(4-bromophenyl)-8-(3,4-dimethoxyphe-nyl)-6-oxo-1,6-dihydro-4_ff-pyrimido[2,1-c][1,2,4]tria-zine-7-carbonitrile (13)
A mixture of compound 9 (2.66 g, 0.01 mol) and p-bromophenacyl bromide (2.77 g, 0.01 mol) in ethanolic KOH (5%, 50 mL) was heated under reflux for 4 h, cooled, then added dil. HCl. The solid thus formed was filtered off and washed with K2CO3 (1%, 100 mL) then recrystallized from EtOH to give 13. Yield 80%, mp 200-202 °C. IR (KBr) v 3433 (NH), 2211 (CN), 1743 (CO) cm-1. 1H NMR (DMSO-d6) 5 3.82 (s, 6H, OCH3), 4.15 (s, 2H, CH2), 6.98-8.72 (m, 7H, Ar-H), 9.16 (s, 1H, NH). Anal. Calcd for C21H16BrN5O3: C, 54.09; H, 3.46; N, 15.02. Found: C, 53.88; H, 3.40; N, 14.86.
Synthesis of 8-(3,4-dimethoxyphenyl)-3-methyl-4,6-di-oxo-1,6-dihydro-4_ff-pyrimido[2,1-c][1,2,4]triazine-7-carbonitrile (14)
Equimolar amounts of compound 9 (2.66 g, 0.01 mol) and sodium pyruvate (1.10 g, 0.01 mol) in ethanolic NaOH (5%, 50 mL) were refluxed for 2 h, cooled, then
poured onto ice with HCl (36%, 10 mL). The resulting solid was filtered off, washed with cold water, dried and recrystallized from AcOH to give 14. Yield 75%, mp 168-170 °C. IR (KBr) v 3289 (NH), 2209 (CN), 1732, 1662 (CO) cm-1. 1H NMR (DMSO-d6) 5 2.87 (s, 3H, CH3), 3.98 (s, 6H, OCH3), 7.49-8.76 (m, 3H, Ar-H), 8.84 (s, 1H, NH). 13C NMR (DMSO-d6) 5 169.5, 160.0, 165.5, 162.3, 154.8, 149.4, 130.1, 119.6, 115.3, 111.5, 92.9, 55.7, 15.3. MS m/z 339 (M+, 3%). Anal. Calcd for C16H13N5O4: C, 56.64; H, 3.86; N, 20.64. Found: C, 56.70; H, 3.84; N, 20.22.
5.	Conclusions
2-Hydrazinyl-1-methylpyrimidine 3 and 2-hydrazi-nopyrimidine 9 were found to be good intermediates for the synthesis of various pyrimido-1,2,4-triazine derivatives. Some of them were tested for their biocidal effects.
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Povzetek
S pomočjo ciklizacijskih reakcij 1-metil-2-hidrazinopirimidina 3 in/ali 2-hidrazinopirimidina 9 z acikličnimi oz. cikličnimi kisikovimi spojinami smo pod različnimi pogoji pripravili nekatere nove izomerne strukture pirimido[2,1-c][1,2,4]triazinov 4-8 in 10-14. Strukture pripravljenih spojin smo potrdili z elementno analizo in s pomočjo spektroskopskih podatkov (UV, IR, 1H/13C NMR in masna spektrometrija). Večini pripravljenih spojin smo tudi določili morebitno antimikrobno aktivnost in jo primerjali s standardnima antibiotikoma pipericilinom in mikostatinom. Le spojina 7 je kazala biocidni učinek.