Antimicrobial activity of new 4, 6-disubstituted pyrimidine, pyrazoline, and pyran derivatives

Article abstract of DOI:10.1007/s12272-010-0501-1

A number of new 2, 6-didisubstituted pyrimidine, pyrazoline, and pyran derivatives were synthesized starting from their chalcone derivative. The synthesized compounds displayed different degrees of antimicrobial activity against Bscillus subtilis (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Streptomyces species (Actinomycetes).

Full text of DOI:10.1007/s12272-010-0501-1

Arch Pharm Res Vol 33, No 5, 647-654, 2010
DOI 10.1007/s12272-010-0501-1
Antimicrobial Activity of New 4,6-Disubstituted Pyrimidine, Pyrazoline,
and Pyran Derivatives
Mahmoud M. M. Ramiz1, Wael A. El-Sayed2, Asmaa I. El-Tantawy1, and Adel A.-H. Abdel-Rahman3
1Department of Physics and Mathematical Engineering, Faculty of Electronic Engineering, Menoufia University, Menouf,
2
3
Egypt, Department of Photochemistry, National Research Centre, Cairo, Egypt, and Department of Chemistry, Faculty
of Science, Menoufia University, Shebin El-Koam, Egypt
(Received October 13, 2009/Revised January 28, 2010/Accepted February 2, 2010)
A number of new 2,6-didisubstituted pyrimidine, pyrazoline, and pyran derivatives were syn-
thesized starting from their chalcone derivative. The synthesized compounds displayed differ-
ent degrees of antimicrobial activity against Bscillus subtilis (Gram-positive), Pseudomonas
aeruginosa (Gram-negative), and Streptomyces species (Actinomycetes).
Key words: Pyrimidines, Pyrazolines, Pyrans, Antimicrobial activity
anti-inflammatory (Nasr and Said, 2003), and anti-
hypertensive (Turan-Zitouni et al., 2000) activities.
INTRODUCTION
The rapid development of resistance to existing Introducing a pyrazolidinone ring (Jungheim et al.,
antimicrobial drugs poses a major threat to public 1987a, 1987b) in place of the -lactam ring (in peni-
β
health. Consequently, there is a pressing need to cillins and cephalosporins; Boyd, 1982) enhances acti-
develop new antimicrobial agents with potent activity vity. A second nitrogen in the five-membered ring also
against the resistant micro-organisms. Electron-rich influences the antibacterial or pharmacokinetic proper-
nitrogen heterocycles play an important role in di- ties (Jungheim et al., 1988a, 1988b; Ternansky and
verse biological activities. Pyrimidines are an impor- Draheim, 1990). Pyran derivatives have attracted a
tant class of compounds and have widespread appli- great deal of interest because of their antimicrobial
cations from pharmaceuticals to materials (Brown, activity (Bedair et al., 2000; El-Agrody et al., 2000,
1996), with activities such as Tie-2 kinase inhibitors 2001), inhibition of influenza, virus sialidases (Taylor
(Matloobi and Kappe, 2007), HIV-1 inhibitor (Gadha- et al., 1998), mutagenic activity (Hirmoto et al., 1997),
chanda et al., 2007), antimalarial (Agarwal et al., 2005), activity as antiviral (Martinez and Marco, 1997) and
adenosine A1 receptor antagonism (Chang et al., antiproliferation agents (Dell and Smith, 1993), sex-
2004), anticancer (Capdeville et al., 2002), analgesic pheromones (Bianchi and Tava, 1987), as well as anti-
(Zaki et al., 2006), cardiovascular (Atwal, 1987), and tumor (Eiden and Denk, 1991) and anti-inflammatory
antiallergic (Ozeki et al., 1989) activities. A number of agents (Shishoo et al., 1981). As part of the continu-
synthetic pharmacophores with antibacterial (Hegab ation of our program of identifying new, potent, selec-
et al., 2007), antifungal (Gholap et al., 2008), and anti- tive, and less toxic antimicrobial agents (Abdel-Rahman
mycotic activities (Keutzberger and Gillessen, 1985) et al., 2008; El-Sayed et al., 2008, 2009) we report here
are based on the pyrimidyl motif. 2-pyrazoline deriva- the synthesis and antimicrobial activity of new disub-
tives have antimicrobial (Nauduri and Reddy, 1998; stituted pyrimidine, pyrazoline, and pyran derivatives.
Grant et al., 1998; Turan-Zitouni et al., 2005a, 2005b),
MATERIALS AND METHODS
Correspondence to: Wael A. El-Sayed, Department of Photohem-
istry, National Research Center, El-Tahrir St., El-Dokki, Cairo,
paratus. IR spectra (KBr) were recorded with a Bruker-
Egypt
Melting points were determined using a Büchi ap-
Vector22 instrument (Bruker). 1H NMR spectra were
Tel: 2016-66448003
E-mail: waelshendy@gmail.com
recorded with a Varian Gemini spectrometer at 300
647

648
M. M. M. Ramiz et al.
MHz and 200 MHz with TMS as the internal stand- dried, and recrystallized from dioxane to afford 3a,b
ard. Chemical shifts were reported on a scale (ppm) in 73-78% yields.
relative to TMS as a standard, and the coupling con-
stants ( values) are given in Hz. The progress of the
δ
J
4-(4-Chlorophenyl)-6-(thiophen-2-yl)pyrimidin-
2-amine (3a)
reactions was monitored by TLC using aluminum
silica gel plates 60 F245. EI-mass spectra were recorded
with a HP D5988 A 1000 MHz instrument (Hewlett-
Yellow solid (2.03 g, 73%), m.p. 276-278oC; IR (KBr)
ν
3389 (NH2), 1608 cm-1 (C=N); 1H NMR (DMSO-d6)
δ
Packard). Elemental analyses were performed at the 6.56 (brs, 2H, NH2), 7.23 (d, 2H,
Microanalytical Data Centre at the Faculty of Science, 7.57 (d, 2H, = 8.5 Hz, Ar-H), 7.65 (s, 1H, Ar-H), 7.96
Cairo University, Egypt. Antimicrobial activity was (m, 2H, Ar-H), 8.33 (d, 1H, = 7.8 Hz, Ar-H); MS m/
(%) 287 (M+, 14). Anal. Calcd. for C14H10ClN3S: C,
J = 8.5 Hz, Ar-H),
J
J
tested at the botany department, Faculty of Science,
Menoufia University, Egypt.
z
58.43; H, 3.50; N, 14.60. Found: C, 58.12; H, 3.32; N,
14.50%.
3-(4-Substitutedphenylphenyl)-1-(thiophen-2-yl)
prop-2-en-1-one (2a,b)
4-(4-Bromophenyl)-6-(thiophen-2-yl)pyrimidin-
2-amine (3b)
To a solution of 2-acetylthiophene (1.26 g, 10 mmol)
in ethanol (50 mL) and potassium hydroxide (0.25 g),
water (5 mL) was added over a period of 30 min at
Yellow solid (2.57 g, 78%), m.p. 280-281oC; IR (KBr)
ν
3389 (NH2), 1608 cm-1 (C=N); 1H NMR (DMSO-d6)
δ
0oC. Then the corresponding aldehyde (10 mmol) was 6.59 (brs, 2H, NH2), 7.23 (d, 2H,
J
= 8.5 Hz, Ar-H),
= 8.5 Hz, Ar-H), 7.65 (s, 1H, Ar-H), 7.96
room temperature for 12 h. Then the reaction mixture (m, 2H, Ar-H), 8.34 (d, 1H, = 7.8 Hz, Ar-H); MS m/
was cooled and poured into water. The solid that
(%) 330 (M+, 18). Anal. Calcd. for C14H10ClN3S: C,
formed was filtered, dried, and recrystallized from 50.61; H, 3.03; N, 12.65. Found: C, 50.31; H, 3.10; N,
slowly added to the reaction mixture with stirring at 7.57 (d, 2H,
J
J
z
ethanol to afford compound
2
in 90% yield.
12.51%.
3-(4-Chlorophenyl)-1-(thiophen-2-yl)prop-2-en-
1-one (2a)
5-(4-chlorophenyl)-1-phenyl-3-(thiophen-2-yl)-
4,5-dihydro-1H-pyrazole (4a,b)
Yellow solid (2.23 g, 90%), m.p. 225-227oC; IR (KBr)
A mixture of 2a,b (10 mmol) and phenylhydrazine
ν
1708 cm-1 (C=O); 1H NMR (DMSO-d6)
= 8.5 Hz, Ar-H), 7.55 (d, 2H, J
δ
7.20 (d, 2H, (1.08 g, 10 mmol) was heated under reflux for 10 h in
= 8.2 Hz, Ar-H), 7.68 ethanol (20 mL). Then the reaction mixture was
= 8.5 Hz, Ar-H), 7.82 (d, 1H, = 8.2 Hz, Ar- cooled, filtered, dried, and recrystallized from ethanol
J
(d, 1H,
J
J
H), 7.95 (m, 2H, Ar-H), 8.37 (d, 1H,
J = 7.8 Hz, Ar-H); to give 4a,b in 77-80% yields.
MS m/z (%) 248 (M+, 8). Anal. Calcd. for C13H9ClOS: C,
62.78; H, 3.65. Found: C, 62.50; H, 3.40%.
5-(4-Chlorophenyl)-1-phenyl-3-(thiophen-2-yl)-
4,5-dihydro-1 -pyrazole (4a)
Yellow solid (2.60 g, 77%), m.p. 269-270oC; IR (KBr)
1605 cm-1 (C=N); 1H NMR (DMSO-d6)
3.42 (s, 2H,
= 8.5 Hz, Ar-H),
= 8.5 Hz, Ar-H),
= 7.8 Hz, Ar-H); MS
J
= 8.2 Hz, Ar- m/z (%) 338 (M+, 10). Anal. Calcd. for C19H15ClN2S: C,
H
3-(4-Bromophenyl)-1-(thiophen-2-yl)prop-2-en-
1-one (2b)
ν
δ
Yellow solid (2.69 g, 92%), m.p. 233-234oC; IR (KBr) CH2), 4.42 (s, 1H, CH), 6.76 (d, 2H,
J
ν
1710 cm-1 (C=O); 1H NMR (DMSO-d6)
= 8.5 Hz, Ar-H), 7.55 (d, 2H, = 8.2 Hz, Ar-H), 7.69 7.96 (m, 4H, Ar-H), 8.29 (d, 1H,
= 8.5 Hz, Ar-H), 7.84 (d, 1H,
δ 7.21 (d, 2H, 7.42 (m, 3H, Ar-H), 7.87 (d, 2H, J
J
J
J
(d, 1H,
J
H), 7.95 (m, 2H, Ar-H), 8.39 (d, 1H,
J = 7.8 Hz, Ar-H); 67.35; H, 4.46; N, 8.27. Found: C, 67.10; H, 4.31; N,
MS m/z (%) 293 (M+, 12). Anal. Calcd. for C13H9BrOS: 8.30%.
C, 53.26; H, 3.09. Found: C, 53.10; H, 3.01%.
5-(4-Bromophenyl)-1-phenyl-3-(thiophen-2-yl)-
4,5-dihydro-1 -pyrazole (4b)
Yellow solid (3.07 g, 80%), m.p. 266-267oC; IR (KBr)
1605 cm-1 (C=N); 1H NMR (DMSO-d6)
3.44 (s, 2H,
= 8.5 Hz, Ar-H),
4-(4-Substitutedphenyl)-6-(thiophen-2-yl)pyri-
midin-2-amine (3a,b)
To a solution of guanidine hydrochloride (10 mmol)
in ethanol (50 mL), sodium metal (0.6 g) was added. CH2), 4.44 (s, 1H, CH), 6.76 (d, 2H,
The reaction mixture was refluxed for 2 h and then 7.42 (m, 3H, Ar-H), 7.87 (d, 2H,
H
ν
δ
J
J
= 8.5 Hz, Ar-H),
compound 2a,b (10 mmol) was added to it and re- 7.96 (m, 4H, Ar-H), 8.29 (d, 1H,
J
= 7.8 Hz, Ar-H); MS
fluxed for 8 h. The reaction mixture was cooled and m/z (%) 384 (M+, 15). Anal. Calcd. for C19H15BrN2S: C,
poured into water. The solid that formed was filtered, 59.54; H, 3.94; N, 7.31. Found: C, 59.31; H, 4.10; N,

Antimicrobial Activity of Disubstituted Pyrimidines
649
7.30%.
5-(4-Bromophenyl)-3-(thiophen-2-yl)-4,5-dihy-
droisoxazole (6b)
Yellow solid (2.43 g, 79%), m.p. 269-270oC; IR (KBr)
2-Amino-4-(4-substitutedphenyl)-6-(thiophen-2-
ν
1610 cm-1 (C=N); 1H NMR (DMSO-d6)
δ
3.47 (s, 2H,
= 8.5 Hz, Ar-H),
yl)-4
A solution of 2a,b (10 mmol) and malononitrile (0.66 CH2), 4.46 (s, 1H, CH), 6.98 (d, 2H,
g, 10 mmol) in dry pyridine (15 mL) was refluxed for 7.43 (m, 1H, Ar-H), 7.88 (d, 2H,
H-pyran-3-carbonitrile (5a,b)
J
J
= 8.5 Hz, Ar-H),
10 h. The solution was cooled and poured onto ice/HCl 7.96 (m, 1H, Ar-H), 8.21 (d, 1H,
J
= 7.8 Hz, Ar-H); MS
and the solid that formed was filtered, washed several m/z (%) 308 (M+, 10). Anal. Calcd. for C13H10BrNOS:
times with water, dried, and recrystallized from etha- C, 50.66; H, 3.27; N, 4.53. Found: C, 50.50; H, 3.10; N,
nol to give 5a,b in 72-74% yields.
4.31%.
2-Amino-4-(4-chlorophenyl)-6-(thiophen-2-yl)- 6-(4-Substitutedphenyl)-4-(thiophen-2-yl)-5,6-
-pyran-3-carbonitrile (5a) dihydropyrimidin-2(1 )-ones and thiopyrimi-
Yellow solid (2.26 g, 72%), m.p. 255-256oC; IR (KBr)
4
H
H
ν
6.72
dinones (7a,b and 8a,b)
General procedure: A mixture of 2a,b (10 mmol),
= 8.5 Hz, Ar-H), 7.69 (d, urea or thiourea (10 mmol), and NaOH (1.12 g, 25
3430 (NH2), 2215 cm-1 (CN); 1H NMR (DMSO-d6)
(brs, 2H, NH2), 7.15 (d, 2H,
2H, = 8.5 Hz, Ar-H), 7.83 (s, 1H, Ar-H), 7.97 (m, 2H, mmol) in ethanol (30 mL) was refluxed for 6 h. The
Ar-H), 8.20 (d, 1H, = 7.8 Hz, Ar-H); MS m/z (%) 314 reaction mixture was concentrated, cooled, and filter-
(M+, 5). Anal. Calcd. for C16H11ClN2OS: C, 61.05; H, ed. The precipitate was recrystallized from ethanol to
3.52; N, 8.90. Found: C, 60.90; H, 3.30; N, 8.70%. give 7a,b and 8a,b in 75-82% yields.
δ
J
J
J
2-Amino-4-(4-bromophenyl)-6-(thiophen-2-yl)- 6-(4-Chlorophenyl)-4-(thiophen-2-yl)-5,6-dihy-
4
H
-pyran-3-carbonitrile (5b)
dropyrimidin-2(1H)-ones (7a)
Yellow solid (2.64 g, 74%), m.p. 259-260oC; IR (KBr)
White solid (2.17 g, 75%), m.p. 277-278oC; IR (KBr)
1
1
ν
3438 (NH2), 2225 cm-1 (CN); H NMR (DMSO-d6)
δ
ν
3321 (NH), 1670 (C=O), 1612 cm-1 (C=N); H NMR
6.75 (brs, 2H, NH2), 7.18 (d, 2H,
J
= 8.5 Hz, Ar-H), (DMSO-d6)
= 8.5 Hz, Ar-H), 7.85 (s, 1H, Ar-H), 7.94 (d, 2H, = 8.5 Hz, Ar-H), 7.43 (m, 1H, Ar-H), 7.87 (d,
(m, 2H, Ar-H), 8.22 (d, 1H, = 7.8 Hz, Ar-H); MS m/ 2H, = 8.5 Hz, Ar-H), 7.92 (m, 1H, Ar-H), 8.04 (d, 1H,
(%) 359 (M+, 15). Anal. Calcd. for C16H11BrN2OS: C,
= 7.8 Hz, Ar-H), 8.30 (brs, 1H, NH); MS m/z (%) 290
53.49; H, 3.09; N, 7.80. Found: C, 53.31; H, 3.00; N, (M+, 4). Anal. Calcd. for C14H11ClN2OS: C, 57.83; H,
δ 3.41 (s, 2H, CH2), 4.47 (s, 1H, CH), 7.24
7.70 (d, 2H,
J
J
J
J
z
J
7.60%.
3.81; N, 9.63. Found: C, 57.70; H, 3.60; N, 9.50%.
5-(4-Substitutedphenyl)-3-(thiophen-2-yl)-4,5-
dihydroisoxazole (6a,b)
A solution of 2a,b (10 mmol) and hydroxylamine
hydrochloride (0.69 g, 10 mmol) in ethanol (15 mL)
containing 0.4 g sodium hydroxide was refluxed for 8 (DMSO-d6)
h. The reaction mixture was evaporated under re- (d, 2H, = 8.5 Hz, Ar-H), 7.44 (m, 1H, Ar-H), 7.87 (d,
duced pressure and the residue was recrystallized 2H, = 8.5 Hz, Ar-H), 7.93 (m, 1H, Ar-H), 8.06 (d, 1H,
6-(4-Bromophenyl)-4-(thiophen-2-yl)-5,6-dihy-
dropyrimidin-2(1H)-ones (7b)
White solid (2.60 g, 78%), m.p. 282-283oC; IR (KBr)
1
ν
3331 (NH), 1672 (C=O), 1610 cm-1 (C=N); H NMR
δ 3.43 (s, 2H, CH2), 4.47 (s, 1H, CH), 7.24
J
J
from ethanol to give compounds 6a,b in 76-79% yield.
J = 7.8 Hz, Ar-H), 8.36 (brs, 1H, NH); MS m/z (%) 334
(M+, 12). Anal. Calcd. for C14H11BrN2OS: C, 50.16; H,
3.31; N, 8.36. Found: C, 50.21; H, 3.21; N, 8.30%.
5-(4-Chlorophenyl)-3-(thiophen-2-yl)-4,5-dihy-
droisoxazole (6a)
Yellow solid (1.99 g, 76%), m.p. 260-261oC; IR (KBr)
6-(4-Chlorophenyl)-4-(thiophen-2-yl)-5,6-dihy-
ν
1605 cm-1 (C=N); 1H NMR (DMSO-d6)
δ
3.44 (s, 2H,
= 8.5 Hz, Ar-H),
= 8.5 Hz, Ar-H),
dropyrimidin-2(1H)-thione (8a)
CH2), 4.43 (s, 1H, CH), 6.96 (d, 2H,
7.43 (m, 1H, Ar-H), 7.88 (d, 2H,
7.95 (m, 1H, Ar-H), 8.20 (d, 1H,
m/z (%) 263 (M+, 10). Anal. Calcd. for C13H10ClNOS: Hz, Ar-H), 7.43 (m, 1H, Ar-H), 7.88 (d, 2H,
J
J
White solid (2.45 g, 80%), m.p. 230-231oC; IR (KBr)
1
ν
3335 (NH), 1608 cm-1 (C=N); H NMR (DMSO-d6)
δ
J
= 7.8 Hz, Ar-H); MS 3.42 (s, 2H, CH2), 4.48 (s, 1H, CH), 7.25 (d, 2H,
J
= 8.5
J
= 8.5 Hz,
C, 59.20; H, 3.82; N, 5.31. Found: C, 59.01; H, 3.60; N, Ar-H), 7.92 (m, 1H, Ar-H), 8.10 (d, 1H,
5.20%.
J = 7.8 Hz, Ar-
H), 12.15 (brs, 1H, NH); MS m/z (%) 306 (M+, 4).
Anal. Calcd. for C14H11ClN2OS: C, 54.80; H, 3.61; N,
9.13. Found: C, 54.71; H, 3.60; N, 8.90%.

650
M. M. M. Ramiz et al.
Scheme 1. Synthesis of substituted pyrimidine, pyrazole, and pyran derivatives
6-(4-Bromophenyl)-4-(thiophen-2-yl)-5,6-dihy-
dropyrimidin-2(1 )-thione (8b)
White solid (2.89 g, 82%), m.p. 225-226oC; IR (KBr)
3331 (NH), 1610 cm-1 (C=N); 1H NMR (DMSO-d6)
4-(4-Substitutedphenyl)-2-(ethylthio)-6-(thio-
phen-2-yl)-4,5-dihydropyrimidine (9a,b)
To a well stirred solution of 8a,b (10 mmol) and
KOH (1.12 g, 10 mmol) in ethanol (8 mL), water (16
H
ν
δ
3.44 (s, 2H, CH2), 4.50 (s, 1H, CH), 7.24 (d, 2H,
J
= 8.5 mL) was added ethyl iodide (1.56 g, 10 mmol), and the
Hz, Ar-H), 7.45 (m, 1H, Ar-H), 7.88 (d, 2H,
J
= 8.5 Hz, resulting mixture was stirred at 60oC for 2 h. The
Ar-H), 7.93 (m, 1H, Ar-H), 8.11 (d, 1H,
J = 7.8 Hz, Ar- reaction mixture was allowed to cool at room temper-
H), 11.98 (brs, 1H, NH); MS m/z (%) 352 (M+, 8). ature and the precipitated solid was filtered, washed
Anal. Calcd. for C14H11BrN2S2: C, 47.87; H, 3.16; N, with water, and recrystallized from ethanol to afford
7.97. Found: C, 47.61; H, 3.10; N, 7.81%.
9a,b in 80-82% yields.

Antimicrobial Activity of Disubstituted Pyrimidines
651
1H, NH); MS m/z (%) 350 (M+, 5). Anal. Calcd. for
4-(4-Clorophenyl)-2-(ethylthio)-6-(thiophen-2-yl)-
4,5-dihydro-pyrimidine (9a)
C14H13BrN4S: C, 48.15; H, 3.75; N, 16.04. Found: C,
Yellow solid (2.67 g, 80%), m.p. 160-161oC; IR (KBr) 48.10; H, 3.61; N, 15.80%.
1
ν
3332 (NH), 1612 cm-1 (C=N); H NMR (DMSO-d6)
δ
1.11 (t, 3H,
2H, = 5.2 Hz, CH2), 4.49 (s, 1H, CH), 7.22 (d, 2H,
= 8.5 Hz, Ar-H), 7.44 (m, 1H, Ar-H), 7.87 (d, 2H,
8.5 Hz, Ar-H), 7.92 (m, 1H, Ar-H), 8.12 (d, 1H,
J = 5.2 Hz, CH3), 3.45 (s, 2H, CH2), 3.90 (q,
Antimicrobial activity
The synthesized compounds were tested for their
antimicrobial activity against three microorganisms,
J
J
J
=
J
= 7.8 and the minimal inhibitory concentrations (MICs) of
Hz, Ar-H); MS m/z (%) 334 (M+, 5). Anal. Calcd. for the tested compounds were determined by the dilution
C16H15ClN2S2: C, 57.38; H, 4.51; N, 8.37. Found: C, method.
57.10; H, 4.41; N, 8.20%.
Sample preparation
Each of the test compounds and standards were
dissolved in 12.5% DMSO at concentrations of 500 g/
4-(4-Bromophenyl)-2-(ethylthio)-6-(thiophen-2-
yl)-4,5-dihydro-pyrimidine (9b)
µ
Yellow solid (3.12 g, 82%), m.p. 165-166oC; IR (KBr) mL. Further dilutions of the compounds and stand-
ν
3328 (NH), 1614 cm-1 (C=N); 1H NMR (DMSO-d6)
1.18 (t, 3H, = 5.2 Hz, CH3), 3.46 (s, 2H, CH2), 3.98 (q,
2H, = 5.2 Hz, CH2), 4.48 (s, 1H, CH), 7.24 (d, 2H,
= 8.5 Hz, Ar-H), 7.45 (m, 1H, Ar-H), 7.88 (d, 2H,
δ
ards were made in test medium.
J
J
J
Culture of microorganisms
Bacterial strains were supplied from the Botany
J
=
8.5 Hz, Ar-H), 7.90 (m, 1H, Ar-H), 8.11 (d, 1H,
J = 7.8 Department, Faculty of Science, Menoufia University,
Hz, Ar-H); MS m/z (%) 380 (M+, 5). Anal. Calcd. for Egypt, namely Bacillus subtilis (ATCC 6633) (Gram-
C16H15BrN2S2: C, 50.66; H, 3.99; N, 7.38. Found: C, positive), Pseudomonas aeruginosa (ATCC 27853)
50.50; H, 3.81; N, 7.21%.
(Gram-negative) and Streptomyces species (Actinomy-
cetes). The bacterial strains were maintained on MHA
(Mueller - Hinton agar) medium (Oxoid, Chemical Co.)
for 24 h at 37°C. The medium was molten on a water
4-(4-Substitutedphenyl)-2-hydrazinyl-6-(thio-
phen-2-yl)-4,5-dihydropyrimidine (10a,b)
A solution of 9a,b (10 mmol) and NH2NH2.H2O (0.5 bath, inoculated with 0.5 mL of the culture of the
g, 10 mmol) in ethanol (10 mL) was heated under reflux specific microorganism, and poured into sterile Petri
with stirring for 4 h. It was allowed to cool at room dishes to form a layer of about 3-4 mm. The layer was
temperature and the precipitated solid was filtered, allowed to cool and harden. With the aid of cork-borer,
washed with water, and recrystallized from ethanol to cups of about 10 mm diameter were produced
afford 10a,b in 85-87% yields.
(Jorgensen et al., 1999).
4-(4-Clorophenyl)-2-hydrazinyl-6-(thiophen-2-yl)-
4,5-dihydro-pyrimidine (10a)
Agar diffusion technique
Antibacterial activities were tested against Bacillus
White solid (2.58 g, 85%), m.p. 221-222oC; IR (KBr) subtilis (Gram-positive), Pseudomonas aeruginosa
1
ν
3432 (NH2), 3330 (NH), 1612 cm-1 (C=N); H NMR (Gram-negative) and Streptomyces species (Actinomy-
(DMSO-d6)
(s, 2H, NH2), 7.10 (d, 2H,
1H, Ar-H), 7.70 (d, 2H, = 8.5 Hz, Ar-H), 7.89 (m, 1H, solution of each synthesized compound (500
Ar-H), 8.08 (d, 1H,
δ
3.45 (s, 2H, CH2), 4.49 (s, 1H, CH), 5.12 cetes) using MH medium (17.5 g casein hydrolysate,
= 8.5 Hz, Ar-H), 7.32 (m, 1.5 g soluble starch, 1000 mL beef extract). A stock
g/mL) in
J
J
µ
J
= 7.8 Hz, Ar-H), 9.22 (brs, 1H, DMSO was prepared and incorporated in sterilized
NH); MS m/z (%) 304 (M+, 5). Anal. Calcd. for liquid MH medium. Different concentrations of the
C14H13ClN4S: C, 55.17; H, 4.30; N, 18.38. Found: C, test compounds in DMF were placed separately in
55.10; H, 4.21; N, 18.20%.
cups in the agar medium. All plates were incubated at
37oC overnight. The inhibition zones were measured
after 24 h. The minimum inhibitory concentration
(MIC) was defined as the intercept of the grave of lo-
4-(4-Clorophenyl)-2-hydrazinyl-6-(thiophen-2-
yl)-4,5-dihydro-pyrimidine (10b)
White solid (3.04 g, 87%), m.p. 224-225oC; IR (KBr) garithm concentrations versus diameter of the inhi-
1
ν
3435 (NH2), 3325 (NH), 1612 cm-1 (C=N); H NMR bition zones (Janssen et al
., 1987; Greenwood, 2000).
(DMSO-d6)
(brs, 2H, NH2), 7.12 (d, 2H,
(m, 1H, Ar-H), 7.70 (d, 2H,
1H, Ar-H), 8.11 (d, 1H,
δ
3.41 (s, 2H, CH2), 4.47 (s, 1H, CH), 5.18
= 8.5 Hz, Ar-H), 7.33
= 8.5 Hz, Ar-H), 7.89 (m,
= 7.8 Hz, Ar-H), 9.31 (brs,
J
RESULTS AND DISCUSSION
J
J
2-acetylthiophen (1) was reacted with 4-chlor or 4-

652
M. M. M. Ramiz et al.
bromobanzladehyde in ethanol in the presence potas- at reflux temperature afforded the substituted pyran
sium hydroxide to afford the corresponding 3-(4- derivatives 5a,b in 72-74% yields. The IR spectra of
substitutedaryl)-1-(thiophen-2-yl)prop-2-en-1-one deri- 5a,b showed characteristic absorption bands at 3430-
1
vatives 2a,b. The H NMR spectra of 2a,b showed 3438 and 2215-2225 cm-1, corresponding to the NH2
1
aromatic protons at
mass spectra showed signals of the molecular ion showed an NH2 signal at
peaks corresponding to the molecular formulas of to the aromatic protons signals at
2a,b The reaction of 2a,b with hydroxylamine hydrochlo-
δ
7.20-8.39 ppm. In addition, the and CN groups, respectively. The H NMR spectra
δ
6.72-6.75 ppm in addition
7.15-8.22 ppm.
δ
.
The reaction of 2a,b with guanidine hydrochloride ride in ethanol at reflux temperature gave the corres-
in ethanol in and sodium hydroxide afforded the ponding oxazole derivatives 6a,b in 76-79% yields.
corresponding 4-(4-substitutedaryl)-6-(thiophen-2-yl) The 1H NMR spectra of 6a,b showed a CH2 signal at
δ
pyrimidin-2-amine 3a,b in 77-80% yields. The IR 3.44-3.47 ppm, H-5 at
δ 4.43-4.46 ppm, and the aro-
spectra of 3a,b showed a characteristic absorption matic protons at
δ 6.96-8.21 ppm. When the enone
band at 3489 cm-1 corresponding to the NH2 but no derivatives 2a,b were allowed to react with urea or
absorption band of a carbonyl group. 1H NMR spectra thiourea in the presence of potassium hydroxide in
showed an NH2 group signal as a singlet at
ppm in addition to the signals of the aromatic protons pyrimidine and thiopyrimidine derivatives, 7a,b and
at 7.23-8.34 ppm. 8a,b, respectively, were obtained in 80-84% yields.
δ 6.56-6.59 ethanol at reflux temperature, the corresponding
δ
When 2a,b were allowed to react with phenyl hy- The structures of 6a, b and 8a,b were confirmed by
drazine in ethanol at reflux temperature, the corres- IR, 1H NMR and mass spectra. The 1H NMR spectrum
ponding 1,3,5-trisubstituted pyrazoline derivatives of 7b showed the CH2 at
δ
3.43 ppm and H-6 at
4a,b were obtained in 80-84% yields. The H NMR ppm, in addition to the aromatic protons at 7.24-8.06
spectra of 4a,b showed a CH2 signal at 3.42-3.44 ppm and NH at 8.36 pm.
ppm, H-5 as a triplet at 4.42-4.44 ppm, and aromatic
protons at 6.76-8.30 ppm.
δ 3.47
1
δ
δ
δ
δ
Alkylation of 8a,b with ethyl iodide in the presence
δ
of potassium hydroxide in a mixture of ethanol and
The reaction of 2a,b with malononitrile in pyridine water (1:2) at 60°C afforded the corresponding S-ethyl
derivatives 9a,b in 78-80% yields. Hydrazinolysis of
9a,b by hydrazine hydrate in ethanol at reflux tem-
perature gave the corresponding hydrazine derivati-
ves 10a,b, respectively, in 80-83% yields. The IR
spectra of 10a,b showed absorption bands at 3319-
3327 cm-1 corresponding to the NH2. In addition, the
mass spectra of 10a,b showed a molecular ion peak
corresponding to their molecular formulas and the 1H
NMR spectra agreed with the assigned structures.
Table I. Minimum inhibitory concentration (MIC in
mL)
µg/
Bacillus
subtilis
Pseudomonas
aeruginosa
Streptomyces
species
Com-
pound
(Gram-positive) (Gram-negative) (Actinomycetes)
2a
2b
3a
3b
4a
4b
5a
5b
6a
6b
7a
7b
8a
8b
9a
9b
250
500
100
250
125
250
75
500
250
500
100
125
75
100
125
125
75
125
31
500
-
500
-
a
a
125
500
250
500
75
125
250
125
250
250
Antimicrobial activity
The antimicrobial activity of the synthesized com-
pounds was evaluated against three microorganisms:
Bacillus subtilis (Gram-positive), Pseudomonas aeru-
ginosa (Gram-negative), and Streptomyces species
a
500
250
-
500
500
75
100
75
100
250
500
100
100
33
a
-
(Actinomycetes). 5a
activity against B. subtilis, with MIC values of 75
mL, followed by compounds 3a 7a, and 8b (Table I).
,
8a, and 10a showed the highest
125
250
100
100
125
250
75
µg/
,
Compounds 5a and 10a showed the highest inhibition
of P. aeruginosa, whereas 7a and 8a were the most
active against Streptomyces species, with MIC values
of 75
µg/mL. Some compounds showed little or no
10a
10b
Penicillin
activity against the microorganisms (Table I).
100
46
The 2,6-disubstituted pyrimidine derivatives with a
free thiol-thione group showed the highest activity
against both B. subtilis and Streptomyces species. In
addition, the pyran derivative with the amino and
The negative control, DMSO, showed no activity.
aTotally inactive (MIC > 500
g/mL).
µ

Antimicrobial Activity of Disubstituted Pyrimidines
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We also tested the influence of functionality such as
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