Synthesis and potent antibacterial activity against MRSA of some novel 1,2-disubstituted-1H-benzimidazole-N-alkylated-5-carboxamidines

Article abstract of DOI:10.1016/j.ejmech.2005.05.002

A series of 28 novel 1,2-disubstituted-1H-benzimidazole-N-alkylated-5- carboxamidine derivatives were synthesized and evaluated for in vitro antibacterial activities against Staphylococcus aureus and methicillin resistant S. aureus (MRSA) by the tube dilution method. The results showed that compounds 45-46 and 55-57, having 3,4-dichloro substituted phenyl at the position C-2, of N-bulky alkyl substituted benzimidazolecarboxamidines exhibited the greatest activity with MIC values of 1.56-0.39 μg/ml.

Full text of DOI:10.1016/j.ejmech.2005.05.002

European Journal of Medicinal Chemistry 40 (2005) 1062–1069
www.elsevier.com/locate/ejmech
Preliminary communication
Synthesis and potent antibacterial activity against MRSA of some novel
1,2-disubstituted-1H-benzimidazole-N-alkylated-5-carboxamidines
Hakan Göker a,*, Seçkin Özden a, SulhiyeYıldız b, David W. Boykin c
a Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, 06100 Tandogan, Ankara, Turkey
b Department of Microbiology, Faculty of Pharmacy, Ankara University, 06100 Tandogan, Ankara, Turkey
c Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
Received 13 August 2004; received in revised form 9 March 2005; accepted 18 May 2005
Available online 29 June 2005
Abstract
A series of 28 novel 1,2-disubstituted-1H-benzimidazole-N-alkylated-5-carboxamidine derivatives were synthesized and evaluated for in
vitro antibacterial activities against Staphylococcus aureus and methicillin resistant S. aureus (MRSA) by the tube dilution method. The
results showed that compounds 45–46 and 55–57, having 3,4-dichloro substituted phenyl at the position C-2, of N-bulky alkyl substituted
benzimidazolecarboxamidines exhibited the greatest activity with MIC values of 1.56–0.39 µg/ml.
© 2005 Elsevier SAS. All rights reserved.
Keywords: 1H-benzimidazole-carboxamidines; Methicilline resistant S. aureus; Antibacterial activity
1. Introduction
Japan [4] and the USA [5] of the isolation of an intermediate
vancomycin-resistant strain of S. aureus have appeared which
increases the urgency for development of new classes of anti-
bacterial agents. Recently, some novel amidinobenzimi-
dazoles [6] (Formula 1) have been identified as inhibitors of
the bacterial KinA/SpoOF two-component system TCS
(which include a histidine protein kinase HPK and a response
regulator RR) which are responsible for adaption of bacteria
to the environmental changes and survival within the host.
These amidino inhibitors display good in vitro antibacterial
activity in particular, against Gram-positive bacteria (i.e. S.
aureus, MRSA, VRE vancomycin-resistant Enterococcus).
Based on these considerations, we have done some modifi-
cations on the benzimidazole ring and a series of N-alkylated
carboxamidines were prepared which show promising activ-
ity against MRSA.
There has been an alarming increase in the incidence of
Gram-positive infections. Among them Staphylococcus
aureus is one of the most common human pathogens. It is the
primary bacteria in many skin and mucous membrane infec-
tions and easily transmitted to uninfected areas of the body.
Moreover, methicillin resistant S. aureus (MRSA) represents
a therapeutic problem of increasing importance, especially in
hospital patients [1,2]. MRSA attracted attention in the late
1960s in Europe and the first report on its importance was
published in USA. Thereafter, MRSA infection became a large
issue in the 1980s [3]. At the moment most of the known
commercial antibiotics are inactive against the MRSA. Van-
comycin, the most effective antibiotic against MRSA infec-
tion, was not available for use in Japan until 1992 and there-
fore it was difficult to treat MRSA due to the lack of effective
drugs [3]. In addition, with the recent increased use of van-
comycin in methicilline resistance S. aureus infections, resis-
tance to vancomycin has been spreading. Recent reports from
* Corresponding author. Tel.: +90 312 222 0471; fax: +90 312 213 1081.
E-mail address: goker@pharmacy.ankara.edu.tr (H. Göker).
Formula 1.
0223-5234/$ - see front matter © 2005 Elsevier SAS. All rights reserved.
doi:10.1016/j.ejmech.2005.05.002

H. Göker et al. / European Journal of Medicinal Chemistry 40 (2005) 1062–1069
1063
2. Chemistry
nitrobenzonitrile by the reaction with several amines in DMF
gave 1–5. The nitrile group of these compounds were con-
verted into the imidate ester, using Pinner method [7], and
the imidate esters was used directly without characterization
to make the amidines 6–20. Their reduction with H2, Pd/C
The synthetic pathways for preparation of the benzimida-
zoles listed in Tables 1 and 2 is shown in Scheme 1. Nucleo-
philic displacement of the chloro group of 4-chloro-3-
Table 1
Formulas and in vitro antibacterial activities as MIC (µg/ml) for 36–64
Numbers
X
R′
R″
R2
R3
R4
R5
R6
S. aureus
ATTC
25923
MRSA
ATCC
43300
MRSA
clinical
isolate from isolate from
MRSA
clinical
blood
6.25
12.5
12.5
1.56
3.12
1.56
0.78
3.12
1.56
0.39
0.39
12.5
NT
wound
3.12
6.25
12.5
1.56
6.25
1.56
0.78
3.12
0.78
1.56
0.78
12.5
NT
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
63
64
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Cl
H
H
H
H
H
H
H
H
H
H
H
Cl
H
Cl
Cl
H
H
H
H
H
H
H
H
H
H
H
H
Cl
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Cl
H
H
H
H
H
H
H
H
H
H
H
6.25
12.5
12.5
12.5
6.25
3.12
1.56
3.12
1.56
0.78
0.39
12.5
> 100
50
6.25
100
50
isopropyl
isopropyl
isopropyl
cyclopropyl
n-butyl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
H
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
H
12.5
12.5
12.5
6.25
6.25
1.56
0.78
0.78
12.5
NT
isopentyl
cyclohexyl
CH2Ph
2.4-dichlorobenzyl
CH2-1-naphtyl
isopropyl
isopropyl
isopropyl
isopropyl
isopropyl
isopropyl
isopropyl
isopropyl
H
F
F
NT
NT
NT
OCH3 OCH3
> 100
100
NT
NT
NT
H
CN
Cl
Cl
Cl
Cl
Cl
Cl
F
NT
NT
NT
NH methyl
NH n-butyl
NH CH2Ph
Cl
Cl
Cl
Cl
Cl
Cl
F
> 100
6.25
6.25
0.78
0.78
0.78
> 100
> 100
0.78
0.78
0.39
NT
NT
NT
12.5
12.5
3.12
1.56
1.56
NT
6.25
3.12
0.39
0.39
0.78
NT
6.25
3.12
3.12
3.12
3.12
NT
NH CH2-1-naphtyl isopropyl
NH CH2-1-naphtyl isopentyl
NH CH2-1-naphtyl CH2Ph
O
O
H
H
isopropyl
n-butyl
Cl
Cl
NT
NT
NT
Formula 1
Ampicillin
Sultamicillin
0.78
50
0.39
50
0.78
50
25
25
25
Scheme 1
.

Table 2
Physical and spectral data for compounds 36–64
Numbers
M.p.
(°C)
Yield Formula
1H-NMR (d ppm)
(DMSO-d6)
Mass (ESI+)
M + 1
Isolation
(%)
Anal. (C,H,N)
14H10Cl2N4
2HCl·1.5HOH
17H17ClN4
2HCl
36
37
305–309
57.3
C
7.84(m,3H), 8.28(m,2H), 8.6(m,1H),
9.18 and 9.47(s,2H)
305(100), 307(70), 309(12)
Cryst. 2 N HCl
Cryst. Ethanolic HCl
340–345
62
C
1.29(d,6H), 4.14(m,1H), 7.66(d, J = 8.8,1H), 7.73 (d, J
= 8.4,2H), 7.87(d, J = 8.4,1H), 8.1(s,1H), 8.41 (d, J = 8.4,2H),
9.13(s,1H), 9.52(s,1H), 9.67(d,1H)
313(100), 315(31)
38
39
40
41
42
43
44
45
46
47
48
49
50
316–320
317–318
324–327
326–329
322–328
65
C
17H17ClN4
1.29(d,6H), 4.1(m,1H), 7.64–8.45(aromat.7H), 9.1(s,1H),
9.49(s,1H), 9.63(d,1H)
313(100), 315(31)
Cryst. Ethanolic HCl
2HCl·0.75HOH
49
C17H16Cl2N4
1.31(d,6H), 4.11(m), 7.61–8.61(aromat. 6H), 9.08(s,1H),
9.46(s,1H), 9.61(d,1H)
347(100), 349(65), 351(11)
345(100), 347(67), 349(12),
361(100), 363(70), 365(14)
375(100), 377(65), 379(12)
387(100), 389(66), 391(13)
395(100), 397(66), 399(13)
CHCl3/isopropanol/NH3
(100:50:2.5) cc
2HCl·0.25HOH
29
C
17H14Cl2N4
0.86 & 0.95(m,4H), 2.8(m,1H), 7.62–8.6(aromat. 6H),
9.16(s,1H), 9.71(s,1H), 10.2(d,1H)
CHCl3/isopropanol/isopropylamine
(100:50:2.5) cc
2HCl·HOH
66
C
18H18Cl2N4
0.93(t,3H), 1.39(m,2H), 1.65(m,2H), 3.44(q,2H),
7.64–8.6(aromat. 6H), 9.09(s,1H), 9.53(s,1H), 9.85(d,1H)
CHCl3/isopropanol/NH3
(100:50:2.5) cc
2HCl
51
C
19H20Cl2N4
0.95(d,6H), 1.59(m,2H), 1.69(m,1H), 3.45 (q,2H),
7.63–8.61(aromat. 6H), 9.08(s,1H), 9.52(s,1H), 9.78(d,1H)
CHCl3/isopropanol/isopropylamine
(100:50:2.5) cc
2HCl
310–320
bubb.
81
C
20H20Cl2N4
1.01–1.97(m,9H), 3.4(m,1H), 7.55–8.56 (aromat. 6H),
9.18(s,1H), 9.44(s,1H), 9.53(d,1H)
Cryst. Ethanolic HCl
2HCl·5HOH
110–120
bubb.
39
C
21H16Cl2N4
4.6(s,2H), 7.28–8.41(aromat. 11H)
4.53(s,2H), 7.28–8.41(aromat. 9H)
4.98(s,2H), 7.52–8.41(aromat. 13H)
CHCl3/isopropanol/NH3
(100:50:2) cc
0.5EtOH·0.75HOH
140–150
bubb.
54.5
25
C
21H14Cl4N4
463(70), 465(100), 467(50),
469(10)
CHCl3/isopropanol/NH3
(100:50:1) cc
0.5EtOH·0.5HOH
125 bub
218–220
C
25H18Cl2N4
445(100), 447(70), 449(12)
347(100), 349(63), 351(11)
347(100), 349(61), 351(12)
315(100)
CHCl3/isopropanol/NH3
(100:50:1) cc
0.5C3H8O·HOH
306–308
285–290
323–326
304–309
53
C
17H16Cl2N4
1.3(d,6H), 4.13(m,1H), 7.63–8.44(m,6H),
9.15(s,1H), 9.51(s,1H), 9.66(d,1H)
Cryst. Ethanolic HCl
2HCl
22
C17H16Cl2N4
1.29(d,6H), 4.16(m,1H), 7.64–8.15(m,6H),
9.26(s,1H), 9.52(s,1H), 9.63(d,1H)
CHCl3/isopropanol/NH3
(100:50:4) cc
2HCl·0.5EtOH·HOH
32
C
17H16F2N4
1.3(d,6H), 4.11(m,1H), 7.63–8.53(m,6H),
9.11(s,1H), 9.5(s,1H), 9.64(d,1H)
CHCl3/isopropanol/NH3
(100:50:2) cc
2HCl·0.5EtOH·HOH
40.5
C
19H22N4O2
1.312(d,6H), 3.88(s,3H), 3.92(s,3H), 4.11(m,1H), 7.27(d,1H),
7.69(d,1H), 7.87(d,1H), 8.11(m, 2H), 8.18(s,1H), 9.14(s,1H),
9.56(s,1H), 9.71(d,1H)
339(100)
CHCl3/isopropanol/NH3
(100:50:3) cc
2HCl·3HOH
51
325–327
71
C
18H17N5
1.32(d,6H), 4.11 (m,1H), 7.66(d,1H), 7.69(d,1H), 8.11(m,3H),
8.57(m,2H), 9.16(s,1H), 9.53(s,1H), 9.66(d,1H)
304(100)
Cryst. Ethanolic HCl
2HCl·HOH
(continued on next page)

Table 2
(continued)
Numbers
M.p.
(°C)
Yield Formula
1H-NMR (d ppm)
(DMSO-d6)
Mass (ESI+)
M + 1
Isolation
(%)
Anal. (C,H,N)
52
53
298–300
44
C
18H18Cl2N4
1.29(d,6H), 3.99(s,3H), 4.16(m,1H), 7.75–8.19 (aromat.6H),
361(100), 363(66), 365(12)
CHCl3/isopropanol/isopropylamine
(100:50:3) cc
2HCl·0.25C3H8O·0.5HOH 9.21(s,1H), 9.56(s,1H), 9.68(d,1H)
125 bub
300–303
42
C
21H24Cl2N4
0.75(t,3H), 1.1(m,2H), 1.31(d,6H), 1.63(m,2H), 4.15(m,1H),
4.42(t,2H), 7.72–8.18(m,6H), 9.21(s,1H), 9.54(s,1H),
9.64(d,1H)
403(100), 405(70), 407(14)
CHCl3/isopropanol/isopropylamine
(100:50:3) cc
2HCl·0.1EtOH·HOH
54
55
56
100 bub
290–293
30
C
24H22Cl2N4
1.28(d,6H), 4.12(m,1H), 5.72(s,2H), 6.97–8.2 (m,11H),
9.17(s,1H), 9.49(s,1H), 9.6(d,1H)
437(100), 439(62), 441(11)
487(100), 490(71), 492(13)
515(100), 517(55), 519(10)
CHCl3/isopropanol/isopropylamine
(100:50:2) cc
2HCl·0.25EtOH·1.5HOH
150 bub
290–293
25.5
17
C
28H24Cl2N4
1.28(d,6H), 4.1(m,1H), 6.2(s,2H), 6.54 (d,1H), 7.3–8.25(other
aromat. 12H), 9.11(s,1H), 9.46(s,1H), 9.57(d,1H)
CHCl3/isopropanol/NH3
(100:50:2) cc
2HCl·HOH
180 bub
293–298
C
30H28Cl2N4
0.9(d,6H), 1.56(q,2H), 1.66(m,1H), 3.42(q,2H), 6.18(s,2H),
6.5(d,1H), 7.29–8.23(aromat. 12H), 9.02(s,1H), 9.44(s,1H),
9.68(s,2H)
CHCl3/isopropanol/NH3
(100:50:1) cc
2HCl·HOH
57
59
60
61
62
63
64
125 bub
250–255
22.5
88
C
32H24Cl2N4
4.74(s,2H), 6.2(s,2H), 6.54(d,1H), 7.3–8.35 (m,17H),
9.3(s,1H), 9.63(s,1H), 10.36(s,1H)
535(100), 537(65), 539(12)
303(100)
CHCl3/isopropanol/NH3
(100: 50: 1) cc
1.5HCl·0.25C3H8O
233–235
246–248
> 300
C
C
C
C
C
C
16H12F2N2O2
1.34(d,6H), 4.33(q,2H), 7.66–8.2(aromat. 6H)
1.34(d,6H), 4.33(q,2H), 7.68–8.39(aromat. 6H), 13.4(s,1H)
7.63–8.25(6H)
Crys. DMF/EtOH
(5:95)
85
16H12Cl2N2O2
14H8F2N2O2
335(100), 337(62), 338(11)
275(100)
Crys. DMF/EtOH
(15:85)
90
Crys. DMF/EtOH
(5:95)
> 300
91
14H8Cl2N2O2
7.68(d, J = 8,1H), 7.85(d,2H), 8.16(m,2H), 8.41(d, J = 2,1H)
1.19(d,6H), 4.12(m,1H), 7.60–8.23 (aromat. 6H), 13(br.s,1H)
307(100), 309(69), 311(12)
316(100)
Crys. DMF/EtOH
(15:85)
243–244
253–256
56
17H15F2N3O·0.3HOH
18H17Cl2N3O
EtOAc: n-Hexane
50% cc
51
0.91(t,3H), 1.35(m,2H), 1.52(m,2H), 3.33 (t,2H), 7.62–8.47
(m,6H), 13.3(br.s,1H)
362(100), 364(65), 366(13)
EtOAc: n-Hexane
50% cc

1066
H. Göker et al. / European Journal of Medicinal Chemistry 40 (2005) 1062–1069
Scheme 2
.
produced 21–35. Condensation of these derivatives with the
Na2S2O5 adduct of appropriate benzaldehydes [8] gave the
targeted benzimidazoles 36–57. Since these amidines exhib-
ited very potent antibacterial activity against S. aureus, it was
deemed important to prepare the corresponding amide deriva-
tives (Scheme 2) to study the role of the amidino center. So,
compound 59 and 60 were obtained by the condensation of
58 with the Na2S2O5 adduct of 3,4-di-(fluoro/chloro)-
benzaldehydes [8] in DMF. Saponification of ester gave
61–62. The carboxyl group was converted to the acid chlo-
ride using SOCl2, then reaction with isopropyl or butylamine
gave desired amide derivatives 63, 64.
on the benzimidazole N-atom does lead to quite active com-
pounds (55–57). Replacement of the cationic amidine unit
by the neutral amide group results in the loss of activity (63,
64).
4. Conclusion
This work demonstrates that monoamidines in the benz-
imidazole series can show very good activity profiles versus
Gram-positive bacteria S. aureus. Compounds 45–46 and
55–57, having N-bulky alkyl substituted amidino groups at
position C-5 and 3,4-dichloro substituted phenyl at the posi-
tion C-2 of benzimidazole exhibited the greatest activity
against S. aureus, MRSA with MIC values of 1.56–
0.39 µg/ml. More extensive study is needed to confirm these
preliminary results and in vivo and mode of action studies
are required to be able to optimize the effectiveness of this
series of compounds.
3. Results and discussion
The benzimidazoles 36–64 were tested in vitro for anti-
bacterial activity against Gram-positive S. aureus (ATCC
25923), MRSA (ATCC 43300 and clinical isolates from
wound and blood), for antibacterial activity by the macro-
broth dilution [9] assay and the MICs values are listed in
Table 1. The synthesized compounds and reference drugs were
dissolved in water or DMSO–water (40%) at a concentration
of 400 µg/ml. The concentration was adjusted to 100 µg/ml
by fourfold dilution with media culture and bacteria solution
at the first tube. Data were not taken for the initial solution
because of the high DMSO concentration (10%). The parent
amidine (36) and compounds with relatively small alkyl
groups on the amidino group (37–40) are only moderately
effective against the bacteria studied. Introduction of more
lipophilic substituents on the amidine group (41–46) increases
the antibacterial activity significantly yielding very promis-
ing compounds such as 45 and 46. It seems that 3,4-dichloro
substitution on the 2-phenyl yields the most active com-
pounds since the MIC value of 39 is superior to that of 48–51,
the latter include other chloro isomers and fluoro, methoxy
and cyano substituted analogues. The combination of mod-
erate sized N-substitution on the benzimidazole N-atom with
the N-isopropylamidino group does not enhance the antibac-
terial effect (52–54). However, more lipophilic substitution
5. Experimental
Uncorrected melting points were measured on a Electro-
1
thermal 9100 capillary melting point apparatus. H-NMR
spectra were recorded employing VARIAN Mercury 400 FT
spectrometer, chemical shifts (d) are in ppm relative to TMS,
and coupling constants (J) are reported in hertz. Mass spectra
were taken on Waters Micromass ZQ by using ESI(+) method.
Microanalyses were performed by Leco CHNS-932 (TUBI-
TAK Ins. Anal. Lab., Ankara) and were within 0.4% of cal-
culated values. All chemicals and solvents were purchased
from Aldrich Chemical Co. or Fischer Scientific. Com-
pounds 2 [10], 3 [11], 4 [11] and Formula 1 [6] were pre-
pared according to the literature method.
5.1. 4-[(Naphtalen-1-ylmethyl)-amino]-3-nitrobenzonitrile
(5)
To a solution of 4-chloro-3-nitrobenzonitrile (7 mmol,
1.28 g) in DMF (3 ml), 1-naphthalenemethylamine (10 mmol,

H. Göker et al. / European Journal of Medicinal Chemistry 40 (2005) 1062–1069
1067
1.57 g) was added and the mixture was heated for 5 h at
110 °C. The hot reaction mixture was allowed to recrystalli-
zation from EtOH. A second recrystallization of the product
from EtOH gave pure 5, yield 77.8%, 1.65 g, m.p. 147–8 °C,
yellow in color, 1H-NMR (CDCl3) d: 5.01(d,2H), 6.94(d,1H),
7.43–7.6(m,5H), 7.87(dd,1H), 7.92(d,2H), 8.54(s,1H),
8.75(s,1H), 13C-NMR (CDCl3) d: 45.37, 98.8, 115.2, 117.8,
122.4, 125.4, 125.5, 126.3, 126.9, 129.1, 129.2, 130.6, 130.9,
evaporated, and diluted with ether, the precipitate filtered,
washed with ether, then dried (Table 3). For compound 13
and 14, the dark orange colored precipitate which first
appeared was removed by filtration, and the mother liquor
yielded a second crop of pure yellow colored product.
5.3. General procedure for synthesis of (21–35)
1
Compounds 6–20 (3.5 mmol) in EtOH (75 ml) was sub-
jected to hydrogenation using 40 psi of H2 and 10% Pd–C
(40 mg) until of H2 uptake ceased. The catalyst was filtered
on a bed of Celite, washed with EtOH, and the filtrate was
concentrated in vacuo. The crude o-phenylenediamines (gray–
purple–black in color) were used for the further steps with-
out crystallization (Table 4). In order to prevent halogen reduc-
tion of compound 28, 15 psi of H2 pressure was employed.
131.8, 132.1, 134.03, 137.8, 146.9 Ref. [12]: H-NMR
(CDCl3) d: 5.01(d,2H), 6.92(d,1H), 7.4–7.6(m,6H),
7.87(dd,1H), 8.55(s,1H), 8.74(s,1H), 13C-NMR (CDCl3) d:
45.5, 98.3, 115.4, 118.0, 122.5, 125.62, 125.64, 126.5, 127.1,
129.3, 129.4, 130.8, 131.0, 132.0, 132.3, 134.2, 138.0, 147.1,
C18H13N3O2. 13C-NMR is in agreement with the data given
in Ref. [12]. However in their NMR spectra, the peak at
7.92 ppm was not reported.
5.4. General procedure for synthesis of (36–57)
and (59–60)
5.2. General procedure for synthesis of (6–20)
1–5 (4.5 mmol) were suspended in absolute EtOH, cooled
in a ice-salt bath, and dry HCl gas was then passed through
the solution for 40 min. The stoppered flask was stirred at
room temperature for 3 days. The solution was diluted with
dry ether. The imidate esters were precipitated as yellow sol-
ids, washed with ether, then dried under vacuum at room tem-
perature. All imidate esters were used directly without char-
acterization. A suspension of imidate ester HCl in absolute
EtOH was stirred with corresponding amines (1.5–2-fold
excess) overnight at 25–30 °C. The reaction mixture was
The corresponding benzaldehydes (15 mmol) were dis-
solved in 50 ml EtOH and sodium metabisulfite (1.6 g) in
10 ml H2O was added in portions. The reaction mixture was
stirred vigorously and more EtOH was added. The mixture
was kept in a refrigerator for a several hours. The precipitate
was filtered and dried (yield over 93%). The mixture of these
salts (2 mmol) and 21–35 and 58 in DMF (5 ml) were heated
at 120 °C for 4 h. The reaction mixture was cooled, poured
into H2O, made alkaline with dilute Na2CO3 solution and the
solid was filtered. Purification methods are given in Table 2.
Table 3
Formulas, m.p., yields and mass spectra of 6–20
Numbers
R′
R″
Formula
M.p.
(°C)
Yield MS ESI(+)
Ref.
(%)
M + H
(100%)
181
6
7
8
9
10
11
12
13
–H
–H
–H
–H
–H
–H
–H
–H
–H
C7H8N4O2
> 300 Ref. [13] > 300
274–276 Ref. [14] > 300
259–262
71
68
51
69
67
60
61
44
[13]
Isopropyl
cyclopropyl
n-butyl
C10H14N4O2
C10H12N4O2
C11H16N4O2
C12H18N4O2
C13H18N4O2
C14H14N4O2
C14H12Cl2N4O2
223
[14]
221
[15]
265–268 Ref. [16] 265
270–275
237
[16,17]
Isopentyl
cyclohexyl
–CH2Ph
251
> 300
263
[15,16]
[16]
285–288
271
2,4-dichlorobenzyl
155 bubb. 280–282
339(100),
341(63),
343(11)
321
14
15
16
17
18
19
20
–H
–CH2-1-naphtyl
Isopropyl
Isopropyl
Isopropyl
Isopropyl
Isopentyl
C18H16N4O2
C11H16N4O2
C14H22N4O2
C17H20N4O2
C21H22N4O2
C23H26N4O2
C25H22N4O2
235–240
260–261
202–206
239–241
225–231
288–290
250–255
32
76
59
51
64
63
66
–methyl
237
–n-butyl
279
–CH2Ph
313
–CH2-1-naphtyl
–CH2-1-naphtyl
–CH2-1-naphtyl
363
391
–CH2Ph
411

1068
H. Göker et al. / European Journal of Medicinal Chemistry 40 (2005) 1062–1069
Table 4
Formulas, m.p., yields and mass spectra of 21–35
Numbers
R′
R″
Formula
C7H10N4
M.p.
(°C)
Yield
(%)
MS ESI(+)
M + H
(100%)
151
Ref.
21
22
–H
–H
–H
238–239
Ref. [13] 237–9
228
94
93
[13]
[14]
isopropyl
C
10H16N4
193
Ref. [14] 227–31
105–110
23
24
–H
–H
cyclopropyl
n-butyl
C
10H14N4
11H18N4
91
95
191
207
[15]
C
167–170
[16,17]
Ref. [16] 170
Ref. [17] 150.4
115–120
25
26
27
–H
–H
–H
isopentyl
cyclohexyl
–CH2Ph
C12H20N4
C13H20N4
C14H16N4
93
92
91
221
233
241
110(Bubb.)
80(Bubb)
[15,16]
[16]
125–127
a
28
–H
2,4-dichlorobenzyl
C
14H14Cl2N4
76
309(100)
311(68)
313(11)
291
a
29
30
31
32
33
34
35
–H
–CH2-1-naphtyl
isopropyl
isopropyl
isopropyl
isopropyl
isopentyl
C
C
C
C
C
C
C
18H18N4
11H18N4
14H24N4
17H22N4
21H24N4
23H28N4
25H24N4
94
91
90
89
95
94
92
–methyl
117–120
128–130
106–110
waxy
207
–n-butyl
249
–CH2Ph
283
–CH2-1-naphtyl
–CH2-1-naphtyl
–CH2-1-naphtyl
333
waxy
361
–CH2Ph
semi-solid
381
a No sharp melting points.
5.5. General procedure for synthesis of (61–62)
suspension was diluted 1:100 (106 CFU/ml) with MHB. One
milliliter of this dilution was added to each tube containing
1 ml of the compound diluted in MHB.
Compounds 59 and 60 (1 mmol) were dissolved in 3%
NaOH in % 50 EtOH–HOH (10 ml) and heated under reflux
for 1 h, cooled, water was added and acetic acid was added to
obtain the carboxylic acids. Purification methods are given in
Table 2.
Acknowledgments
This work was supported by Ankara University Research
Fund (Project No.: 0000018-2003). Central Laboratory of
Pharmacy, Faculty ofAnkara University provided support for
acquisition of the NMR and Mass spectrometer used in this
work.
5.6. General procedure for synthesis of (63–64)
61 and 62 (0.75 mmol) were heated at reflux in benzene
(4 ml) with SOCl2 (3 ml) for 2 h at 80 °C. Then solvent and
excess of SOCl2 were evaporated and the residue was dis-
solved in chloroform (10 ml). Excess of the corresponding
amine derivatives (0.5 ml) was added and the mixture was
stirred and heated for 30 min at 50 °C. Chloroform was added,
washed with Na2CO3 (5%), H2O and evaporated. Purifica-
tion methods are given in Table 2.
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