Synthesis and 'in vitro' antimicrobial properties of N-oxide derivatives based on tricyclic indeno[2,1-c]pyridazine and benzo[f]cinnoline systems

Article abstract of DOI:10.1002/1521-4184(200010)333:10<341::AID-ARDP341>3.0.CO;2-U

A number of 9H-indeno[2,1-c]pyridazine N-oxides (3a-c) and benzo[f]cinnoline N-oxides (4,5a-c) have been synthesized and tested for antimicrobial activity. All new products were inactive against Gram negative bacteria and fungi. In contrast, among the compounds synthesized, 3b, 4b and 5b showed a moderate activity against Gram positive Staphylococcus aureus and Staphylococcus epidermidis. Of the present series, the 9-nitro-benzo[f]cinnoline N-oxide 5b possessed the highest activity especially against Trichomonas vaginalis (MIC = 3.9 μg/ml).

Full text of DOI:10.1002/1521-4184(200010)333:10<341::AID-ARDP341>3.0.CO;2-U

Pyridazine N-Oxides
341
Pyridazine N-Oxides. III
Synthesis and “in Vitro” Antimicrobial Properties of N-Oxide
Derivatives Based on Tricyclic Indeno[2,1-c]pyridazine and
Benzo[f]cinnoline Systems
a)
a)
a)
a)
a)
b)
Elisabetta Gavini , Claudia Juliano , Antonio Mulè , Gerolamo Pirisino* , Gabriele Murineddu , and Gérard A. Pinna
a) Dipartimento di Scienze del Farmaco, Università di Sassari, via F. Muroni 23/A, 07100 Sassari, Italy
b) Dipartimento Farmaco Chimico Tossicologico, Università di Sassari, via F. Muroni 23/A, 07100 Sassari, Italy
Key Words: Pyridazine N-oxides; antimicrobial activity; indeno[2,1-c]pyridazine; benzo[f]cinnoline
C-4position had been confined to arylcarbamoyl groups, and
Summary
compounds 2a,b exhibited a good level of antitrichomonas
[3]
activity
.
A number of 9H-indeno[2,1-c]pyridazine N-oxides (3a–c) and
benzo[f]cinnoline N-oxides (4,5a–c) have been synthesized and
tested for antimicrobial activity. All new products were inactive
against Gram negative bacteria and fungi. In contrast, among the
compounds synthesized, 3b, 4b and 5b showed a moderate activity
against Gram positive Staphylococcus aureus and Staphylococcus
epidermidis. Of the present series, the 9-nitro-benzo[f]cinnoline
N-oxide 5b possessed the highest activity especially against
Trichomonas vaginalis (MIC = 3.9 µg/ml).
As a continuation of our research project directed towards
structure-activity relationships (SAR) studies, we investigate,
in the present work, the synthesis and the antimicrobial activ-
ity of new analogues in which prototype 1 was conformation-
ally constrained into tricyclic indeno[2,1-c]pyridazine and
benzo[f]cinnoline templates to give novel compounds of gen-
eral structure 3–5.
Introduction
The spread of antibiotic resistance among pathogenic mi-
croorganisms has become a serious problem for the clinical
management of infectious diseases and has resulted in a clear
need for the discovery of new antimicrobials other than
[1]
analogues of existing ones . In an effort to identify such
novel agents, our antimicrobial program focused mainly on
arylpyridazine N-oxides as azoxybacilin-pyridazomycin hy-
brids.
Results and Discussion
Chemistry
According to preliminary screening compounds 1a,b have
The tricyclic N-oxides designed 3,4,5a–c were prepared
following the route depicted in Scheme 1.
very moderate antibacterial activity against the Gram positive
[2]
Staphylococcus aureus and Staphylococcus epidermidis
.
The synthesis of the 9H-indeno[2,1-c]pyridazin-3(2H)-one
6a and 5,6-dihydro-benzo[f]cinnolin-2(3H)-ones 7a were
[4,5]
prepared according to literature procedures
.
Nitration of 6a with potassium nitrate in sulfuric acid at
0–5 °C afforded a sole regioisomer 6b in moderate yield. The
structure elucidation of the regioisomer 6b was proved by
NOE difference spectroscopy. Irradiation of the resonance
frequency of the protons 9-H led to the enhancement of the
Subsequently, in oureffort to improve the observedactivity, signal of the proton 8-H while the irradiation of 5-H produced
several 3-chloro-4-carbamoyl-5-aryl-6-methyl-pyridazine an enhancement of the signal of the sole 4-H demonstrating
N -oxides 2 were prepared and biotested. Substitution at the that carbon six position was occupied by the nitro group
1
Arch. Pharm. Pharm. Med. Chem.
© WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000
0365-6233/00/1010/0341 $17.50 +.50/0

342
Gavini, Juliano, Mulè, Pirisino, Murineddu, and Pinna
(Figure 1). In the same manner 7a afforded 7b whose struc-
ture was confirmed by mixed melting point and spectral data
[5]
obtained from a sample synthesized as reported elsewhere
.
Heteroaromatic chlorination of the lactam group of 6 and 7
[4]
with phosphorus oxychloride produced 8 and 9 in low to
good yield.
Oxidation of 8 and 9 with 35% H O and formic acid at
2
2
50–60 °C led to N-oxide derivatives 3a,b and 4a,b. Further-
more, it is possible to obtain 3,4c by nitration of 3a and 4a to
Scheme 2. Reagents: = (i) glyoxylic acid, Microwave irradiation (MWI); (ii)
NH2NH2 H2O.
[6]
3b and 4b followed by catalytic reduction
.
[7]
5,6-Dehydrogenation of 4a–c with DDQ in dioxane gave
21–27% of 5a–c; alternatively 5a,b were better isolated by
N-oxidation of 10a,b in turn obtained from 9a,b with DDQ.
Biological Activity
The results of the antimicrobial screening of compounds
3–5a–c are shown in Table 1.
In general most compounds tested demonstrated no activity
against bacteria and fungi with the exception of 3a, 3b, 4b,
[4]
The educt 9H-indeno[2,1-c]pyridazin-3(2H)-one 6a was
alternatively synthesized (Scheme 2) by reaction of 2-in-
danone 11 with glyoxylic acid using Microwave irradiation
(MWI) for 8 min, followed by cyclization of the hydroxyacid and 5b which showed a low level of antibacterial activity
against Gram positive strains (especially S. epidermidis, MIC
= 15.2–62.5 µg/ml).
obtained 12 with hydrazine hydrate.
Conversely, derivatives 4b and 5b were found to possess a
better activity against T. vaginalis (MIC = 31.3 and 3.9 µg/ml
s
respectively) with respect to the metronidazole (MIC =
25 µg/ml) used as reference drug.
In conclusion we have demonstrated that the structure of
benzo[f]cinnoline N-oxide bearing a C-6-nitro group, is im-
portant for the antitrichomonas activity, 5b being about six
times more active than metronidazole.
Acknowledgement
This work was supported by a grant of M.U.R.S.T. (ex 40%).
Experimental Part
Chemistry
Melting points were determined on a Kofler apparatus and are uncorrected.
Elemental analyses are within 0.4% of the theoretical values. 1H-NMR
spectra were obtained from CDCl3 solutions unless otherwise noted, using a
Varian XL-200 spectrometer. Proton chemical shifts are given in δ (ppm)
relative to Me4Si. Multiplicities are recorded as s (singlet), br s (broad
singlet), d (doublet), t (triplet), q (quartet), dd (doublet of doublets), m
(multiplet). Infrared spectra were recorded as KBr tablets on a Perkin Elmer
781 spectrometer and are expressed in ν cm–1. Column chromatography was
performed on a ICN silica gel 32–63µm, 60Å or on a Merck aluminium oxide
90, 0.063–0.2 mm (70–230 mesh ASTM). Analytical thin layer chromatog-
raphy (TLC) was performed on Merck precoated silica-gel 60 F254 or on
aluminium oxide 60 F254 neutral (type E). For micro wave irradiation (MWI)
a Whirlpool MWO 155 domestic microwave oven Model easytronic (250
Watt) was used.
Scheme 1. Reagents: = (i) KNO3, H2SO4; (ii) POCl3; (iii) 35 % H2O2,
HCOOH; (iv) H2, PtO2.H2O; (v) DDQ, dioxane.
Elemental analyses were performed by Laboratorio di Microanalisi, Di-
partimento di Scienze Farmaceutiche Università di Padova, Italy and are
within ±0.4% of the calculated values.
The chemical, physical and spectroscopic data of new compounds are
reported in Tables 2–4.
General Chlorination Procedure for Compounds
3-Chloro-6-nitro-9H-indeno[2,1-c] pyridazine 8b,
2-Chloro-5,6-dihydrobenzo[f]cinnoline 9a,
2-Chloro-9-nitro-5,6-dihydrobenzo[f]cinnoline 9b
A solution of the appropriate pyridazinone 6 or 7 (1 mmol) in 2 ml (22
mmol) of phosphorus oxychloride was refluxed (1 h for 6a, 0.5 h for 6b and
2 h for 7b). After removal of the solvent under reduced pressure, the residue
Figure 1
Arch. Pharm. Pharm. Med. Chem. 333, 341–346 (2000)

Pyridazine N-Oxides
343
Table 1. In vitro antimicrobial activity (µg/ml) of 3,4,5a–c.
——————————————————————————————————————————————————————————
Microorganisms
3a
3b
3c
4a
4b
4c
5a
5b
5c
——————————————————————————————————————————————————————————
S.aureus (ATCC 6538)
250
125
62.5
15.6
>250
250
>250
>250
>250
>250
>250
>250
>62.5
>250
>250
>250
>250
>250
>250
>250
>62.5
250
125
>250
>250
250
>250
>250
>250
>250
>250
>250
>250
>62.5
62.5
62.5
15.2
>250
250
S.aureus (ATCC 25923) 125
S.epidermidis
E.coli
62.5
62.5
125
125
250
250
>250
>250
>250
>250
>62.5
>250
>250
>250
>250
>250
>62.5
P.aeruginosa>
C.albicans
A.niger
250
>250
250
>250
>250
>250
125
>250
>250
125
250
T.vaginalis
>62.5
>62.5
31.3
3.9
——————————————————————————————————————————————————————————
Table 2. Chemical and physical data of the compounds 3–5a–c.
———————————————————————————————————————————————————————
Compd
n
R
Yield
(%)
Mp °C b
Formula
(MW)
Analyses
———————————————————————————————————————————————————————
3a
3b
3c
4a
4b
4c
5a
5b
5c
CH2
H
58.0
265–70
C11H7ClN2O
(218.64)
C11H6ClN3O3
(263.65)
C11H9ClN3O
(234.66)
C12H9ClN2O
(232.66)
C12H8ClN3O3
(277.67)
C12H10ClN3O
(247.69)
C12H7ClN2O
(230.03)
C12H6ClN3O3
(275.66)
C,H,Cl.N,O
C,H,Cl.N,O
C,H,Cl.N,O
C,H,Cl.N,O
C,H,Cl.N,O
C,H,Cl.N,O
C,H,Cl.N,O
C,H,Cl.N,O
C,H,Cl.N,O
CH2
NO2
NH2
H
92.0
>315
CH2
12.5
>315
CH2-CH2
CH2-CH2
CH2-CH2
CH=CH
CH=CH
CH=CH
95.0
178–180
212–215
241–243
243–246
247–250
254–256
NO2
NH2
H
76.0
64.5
62.8 (16.6) a
60.0 (25.0) a
20.5
NO2
NH2
C12H8ClN3O
(245.68)
———————————————————————————————————————————————————————
a Reaction with DDQ; bRecrystallized from ethanol-water for 3a, from acetic acid for 3b and from ethanol for all the other compounds.
was triturated with ice. The resulting solid was filtered off, washedwithwater
and air-dried to give either a crude product (8b) which was purified by flash
column chromatography eluting with petroleum ether 50–70 °C/ ethyl ace-
tate 7/3, or a pure solid (9a,b).
ethyl acetate in petroleum ether 50–70 °C for 5a and 20% ethyl acetate in
dichloromethane for 5b.
Derivative 4a was purified by crystallization with ethanol.
General Nitration Procedure for Compounds
General N-Oxidation Procedure for Compounds
3-Chloro-9H-indeno[2,1-c] pyridazine-N-oxide 3a,
2-Chloro-5,6-dihydrobenzo[f]cinnoline-N-oxide 4a,
2-Chloro-benzo[f]cinnoline-N-oxide 5a,
3-Chloro-6-nitro-9H-indeno[2,1-c]pyridazine-N-oxide 3b,
3-Chloro-6-nitro-9H-indeno[2,1-c] pyridazin–3(2H)-one 6b,
2-Chloro-9-nitro-5,6-dihydrobenzo[f]cinnoline-N-oxide 4b,
9-Nitro-5,6-dihydrobenzo[f]cinnolin-2(3H)-one 7b
2-Chloro 9-nitro-benzo[f]cinnoline-N-oxide 5b
To a stirred solution of the appropriate precursor 3,4,6,7 (0.96 mmol) in
96% sulfuric acid (0.9ml) cooled at 0–5 °C, powdered potassium nitrate
(0.12 g; 1.2 mmol) was added portionwise. After stirring at 0–5 °C (3 h for
3a , 2 h for 4,7a and 1h for 6a) the mixture was poured onto ice to give crude
solids which were purified by flash column chromatography using petroleum
ether 50–70 °C/ ethyl acetate 4/6 for 3b, and dichloromethane/ethyl acetate
7/3 for 4,7,b; 6b was purified by crystallization with acetic acid.
A solution of the appropriate precursor 8–10 (0.92 mmol) in 3 ml of formic
acid was added of 35 % hydrogen peroxide (28 mmol) and heated at 50–60 °C
(1 h for 8a, 4 h for 9a, 6 h for 10a and 2 h for 10b).
The reaction solution was poured into ice and the resulting solid was
filtered off, washed with water and after drying, purified by flash column
chromatography using 30% ethyl acetate in dichloromethane for 3a, 30%
Arch. Pharm. Pharm. Med. Chem. 333, 341–346 (2000)

344
Gavini, Juliano, Mulè, Pirisino, Murineddu, and Pinna
Table 3. Chemical and physical data of the compounds 6–10,12.
—————————————————————————————————————————————————————————————
Compd
n
R
Yield
(%)
Mp °C a
Formula
(MW)
Analyses
—————————————————————————————————————————————————————————————
6a
6b
7b
CH2
H
21.4
68.0
93.0
298–302
C11H8N2O
(184.20)
C11H7N3O3
(229.19)
C12H9N3O3
(243.22)
C,H,N,O
C,H,N,O
C,H,N,O
(Ref.[4] 298–302)
>315
CH2
NO2
NO2
CH2-CH2
290–292
(Ref.[5] 290–292)
—————————————————————————————————————————————————————————————
a Recrystallized from acetic acid for 6b, and from ethanol for 7b.
—————————————————————————————————————————————————————————————
Compd
n
R
Yield
(%)
Mp °C a
Formula
(MW)
Analyses
—————————————————————————————————————————————————————————————
8b
CH2
NO2
22.6
88.0
93.0
73.0
91.0
>350
C11H6ClN3O2
(247.64)
C12H9ClN2
(216.67)
C12H8ClN3O2
(261.67)
C12H7ClN2
(214.65)
C,H,Cl.N,O
9a
CH2-CH2
CH2-CH2
CH=CH
CH=CH
H
140–141
195–197
215–218
260–261
C,H,Cl.N
9b
NO2
H
C,H,Cl.N,O
C,H,Cl.N
10a
10b
NO2
C12H6ClN3O2
(259.65)
C,H,Cl.N,O
————————————————————————————————————————————————————————————
a Recrystallized from ethanol.
———————————————————————————————————————————
Compd
Yield
(%)
Mp °C a
Formula
(MW)
Analyses
———————————————————————————————————————————
12
88.5
>300
C11H10O4 C,H,O
(206.20)
———————————————————————————————————————————
a Triturated with ether
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Pyridazine N-Oxides
345
Table 4. IR, UV and 1H-NMR spectroscopic data of compounds 3–6, 8–10, 12.
—————————————————————————————————————————————————————————————–
Compd
IRa
(cm–1), ν
UV (ethanol)
1H-NMR
λmax nm (log ε)
δ (ppm)
—————————————————————————————————————————————————————————————–
3a
3b
1340 (N=N→O)
341.8 (2.80), 261.4 (3.54)
273.2 (5.20)
4.15 (s, 2H), 7.40–7.90 (m, 5H)d
1525 and 1330 (NO2)
4.28 (s, 2H), 7.95 (d, 1H, J = 8.4 Hz), 8.29 (s, 1H),
8.46 (dd, 1H, J = 8.4 Hz and 2.2 Hz), 9.10 (s, 1H)d
1340 (N=N→O)
3c
4a
3400 and 3310 (NH2)
295.6 (4.37), 271.4 (4.34),
235.2 (4.47)
3.98 (br s, 2H), 4.06 (s, 2H), 6.88 (d, 2H, J = 8.4 Hz), 7.05
(s, 1H), 7.16 (d, 1H, J = 8.4 Hz), 7.31 (s, 1H)d
1310 (N=N→O)
1330 (N=N→O)
350.0 (3.79), 290.0 (4.50),
265.2 (4.68), 203.6 (4.47)
3.16 (t, 2H, J = 6.8 Hz), 3.25 (t, 2H, J = 6.8 Hz),
7.25–7.80 (m, 5H) b
4b
4c
1520 and 1350 (NO2),
352.0 (3.77), 266.0 (3.76),
201.4 (3.37)
3.17–3.55 (m, 4H), 7.45–7.75 (m, 2H), 8.33 (dd, 1H,
J = 8.4 Hz and 1.8 Hz), 8.61 (d, 1H, J = 8.4 Hz)b
1275 (N=N→O)
3450 and 3340 (NH2),
349.6 (4.12), 297.8 (4.34),
266.0 (4.72)
2.92 (t, 2H, J = 7.6 Hz), 3.20 (t, 2H, J = 7.6 Hz), 3.75
(br s, 2H), 6.80 (dd, 2H, J = 8.2 Hz and 2.2 Hz), 7.01
(d, 1H, J = 2.2 Hz), 7.13 (d, 1H, J = 8.2 Hz), 7.36 (s, 1H)d
1290 (N=N→O)
5a
1335 (N=N→O)
400.0 (3.61), 376.0 (3.54),
360.0 (3.27), 340.0 (3.79),
324.0 (3.77), 273.9 (4.29),
236.0 (3.83), 216.1 (4.30),
200.0 (4.19)
8.03–8.21 (m, 3H), 8.42 (d, 1H, J = 9.8 Hz), 8.49 (d, 1H,
J = 9.8 Hz), 8.77–8.82 (m, 1H), 9.09 (s, 1H)c
5b
5c
1520 and 1340 (NO2),
400.0 (3.84), 378.0 (3.94),
357.9 (3.97), 320.0 (3.82),
268.0 (4.41), 257.3 (4.41),
200.7 (4.37)
8.10 (d, 1H, J = 9.4 Hz), 8.20 (d, 1H, J = 8.8 Hz), 8.27 (
s, 1H), 8.61–8.77 (m, 2H), 9.44 (d, 1H)b
1270 (N=N→O)
3390 and 3320 (NH2),
340.2 (4.22), 277.2 (4.44),
253.6 (4.35)
5.20 (br s, 2H), 7.24 (dd, 1H, J = 8.6 Hz and 2.8 Hz), 7.47
(s, 1H), 7.72 (dd, 1H, J = 8.6 Hz and 2.8 Hz), 7.86
(d, 2H, J = 9.4 Hz), 8.06 (d, 1H, J = 9.4 Hz), 8.13 (s, 1H)e
1335 (N=N→O)
6b
8b
1660 (CO), 1510
and 1385 (NO2)
273.2 (2.20)
3.98 (s, 2H), 7.46 (s, 1H), 7.75 (d, 1H, J = 8.8 Hz), 8.25
(d, 1H, J = 8.8 Hz), 8.85 (s, 1H), 12.83 (br s, 1H)e
1550 and 1330 (NO2)
344.8 (4.32), 305.6 (4.43),
286.0 (4.54), 263.6 (4.65),
218.4 (4.43)
4.42 (s, 2H), 7.97 (d, 1H, J = 6.6 Hz), 8.44 (dd, 1H,
J = 6.6 Hz and 1.8 Hz), 8.57 (s, 1H), 9.13 (d, 1H, J = 1.8 Hz)e
9a
9b
1570 (C=N)
311.5 (3.81), 285.5 (4.09),
277.0 (4.14), 205.5 (4.35)
3.09 (t, 2H, J = 6.4 Hz), 3.29 (t, 2H, J = 6.4 Hz),
7.31–7.80 (m, 5H)b
1520 and 1350 (NO2)
370.0 (3.78), 350.0 (3.81),
322.0 (4.07), 254.8 (4.62),
204.9 (4.51)
3.21 (t, 2H, J = 5.8 Hz), 3.38 (t, 2H, J = 5.8 Hz), 7.57
(d, 1H, J = 8.2 Hz), 7.84 (s, 1H), 8.28 (dd, 1H,
J = 8.2 Hz and 1.6 Hz), 8.65 (d, 1H, J = 1.6 Hz)b
10a
10b
12
1550 (C=N)
376.0 (3.35), 356.0 (3.35),
296.0 (3.79), 265.1 (4.46),
240.0 (4.22), 218.1 (4.49)
7.76–8.00 (m, 4H), 8.05 (d, 1H, J = 9.2 Hz), 8.22
(d, 1H, J = 9.2 Hz), 8.65 (s, 1H)b
1520 and 1350 (NO2)
372.0 (3.73), 352.0 (3.76),
324.0 (3.97), 308.0 (4.02),
254.5 (4.52), 206.0 (3.96)
8.12–8.30 (m, 2H), 8.47 (d, 1H, J = 8.8 Hz), 8.62
(dd, 1H, J = 8.8 Hz and 1.4 Hz), 9.03 (s, 1H), 9.68
(d, 1H, J = 1.4 Hz)d
3440 (OH), 1700 (CO),
1690 (CO)
274.0 (4.12)
3.57 (s, 2H), 4.73 (d, 1H, J = 3.0 Hz), 4.83 (d, 1H,
J = 3.0 Hz), 5.35 (br s, 2H), 7.38–7.50 (m, 4H)d
—————————————————————————————————————————————————————————————–
aKBr; bCDCl3; cCF3COOD; dCDCl3 + [D6]DMSO; e[D6]DMSO.
Arch. Pharm. Pharm. Med. Chem. 333, 341–346 (2000)

346
Gavini, Juliano, Mulè, Pirisino, Murineddu, and Pinna
General Catalytic Reduction Procedure for Compounds
6-Amino-3-chloro-9H-indeno[2,1-c] pyridazine-N-oxide 3c
9-Amino-2-chloro-5,6-dihydrobenzo[f]cinnoline-N-oxide 4c
Antibacterial activity was assessed by an agar dilution susceptibility test [8]
using the following strains: Escherichia coli ATCC 25922; Pseudomonas
aeruginosa ATCC 27853; Staphylococcus aureus ATCC 6538 and ATCC
25923; clinical isolated Staphylococcus epidermidis. Briefly, increasing
concentrations (from 32.25 µg/ml to 250 µg/ml) of the study compounds
were incorporated into melted Mueller-Hinton agar (Difco) at 45 °C, which
was then mixed, poured into petri plates and allow to harden. Then each agar
plate was inoculated with 1 µl of a standardized cell suspension containing
1×107 viable bacteria/ml. The inoculated plates were incubated at 35 °C for
18–20 hours. All compounds were dissolved in dimethyl sulfoxide. The
lowest concentration of each drug which prevented bacterial growth after this
time was defined as minimum inhibitory concentration (MIC).
A mixture of the appropriate nitroderivative 3,4b (0.51 mmol), 17 ml of
.
ethanol and 10% PtO2 H2O was subject to hydrogenation in a Parr apparatus
until the calculated hydrogen volume had been absorbed. The catalyst was
filtered off and ethanol was evaporated under reduce pressure. The resulting
crude solids were purified by flash column chromatography eluting with
chloroform/methanol 9/1 for 3c, 20% ethyl acetate in petroleum ether for 4c
to yield the desired products.
General Oxidation with DDQ Procedure for Compounds
2-Chloro-benzo[f]cinnoline-N-oxide 5a,
2-Chloro-9-nitro-benzo[f]cinnoline-N-oxide 5b,
9-Amino-2-chloro-benzo[f]cinnoline-N-oxide 5c,
2-Chloro-benzo[f]cinnoline 10a,
Antifungal activity was determined by an agar dilution technique[9], using
strains of Candida albicans ATCC 10231, Aspergillus niger ATCC 16404
and Sabouraud Dexstrose Agar as culture medium.
Antitrichomonas activity was evaluated in microtiter 96-well plates as
described by Meingassner and Thurner[10], by using axenic as strain of
Trichomonas vaginalis isolated from case of vaginal trichomoniasis.
2-Chloro-9-nitro-benzo[f]cinnoline 10b
To a refluxing solution of the appropriate dihydrobenzoderivative 4,9 (1
mmol) in 4 ml of dioxane, was added dropwise a solution of DDQ (1 mmol)
in 2 ml of dioxane and refluxed (22 h for 4a, 20 h for 4b, 10 h for 4c, 2 h for
9a and 9b). The solvent was evaporated under reduced pressure and the solid
obtained was purified by flash column chromatography using petroleum
ether 50–70 °C/ ethyl acetate 8/2 for 5a, dichlomethane/ethyl acetate 8/2 for
both 5b and 5c and, dichloromethane/acetone 9/1 and 7/3 for 10a and 10b
respectively.
References
[1] E.L. Setti, L. Quattrocchio, R.G. Micetich, Drugs Future 1997, 22,
271–284.
[2] E. Gavini, C. Juliano, A. Mulè, G. Pirisino, G.A. Pinna, M.M. Curzu,
Farmaco 1996, 51, 683–688.
2-Oxo-indan-1-yl-2-hydroxyacetic acid oppure 2-hydroxy-2(2-oxo-indan-
1yl)acetic acid 12
[3] E. Gavini, C. Juliano, A. Mulè, G. Pirisino, G.A. Pinna, Farmaco 1997,
52, 67–69.
0.5 g (3.78 mmol) of 2-indanone and 0.38 g (4.13 mmol) of glyoxylic acid
monohydrate were mixed in a mortar and condensed into a microwave oven
for 8 min at 250 Watt to give the desired product 12 which was employed
for the next step without any purification.
[4] G.A. Pinna, M.M. Curzu, M. Loriga, G. Cignarella, D. Barlocco, S.
Malandrino, Farmaco 1985, 12, 979–986.
[5] G.A. Pinna, M.M. Curzu, P. Fraghì, E. Gavini, M. D’Amico, Farmaco
1996, 51, 653–658.
9H-Indeno[2,1-c]-3(2H)-pyridazinone[4] 6a
[6] M. Hudlicky, The reduction of specific types of organic compounds.In:
Reduction in Organic Chemistry, Ellis Horwood Limited, John Wiley
& Sons Limited, Chichester, West Sussex, England, 1984, 72.
A solution of 12 (4.85 mmol) in 0.94 ml of hydrazine monohydrate (19.4
mmol) was refluxed for 5 h. After cooling, the mixture was poured into ice
and extracted with dichloromethane. The organic layer was dried (Na2SO4)
to yield after evaporation a dark gummy product which was purified by flash
column chromatography eluting with dichloromethane/aceton 6/4 to give 6a
as a brown solid.
[7] W. Remes, M.J. Weiss, J. Org. Chem. 1971, 36, 1241–1247.
[8] A.L. Barry, Procedure for testing antimicrobial agents in agar media:
theoretical considerations. In: Antibiotics in Laboratory Medicine, 2nd
Edition, V.Lorian Ed., Williams & Wilkins, Baltimore, 1986, Chap. 1.
Microbiology
[9] M.R. McGinnis, M.G. Rinaldi, Antifungal drugs: Mechanisms of ac-
tion, drug resistance, susceptibility testing, and assays of activity in
biological fluids. In: Antibiotics in Laboratory Medicine, 2nd Edition,
V.Lorian Ed.,Williams & Wilkins, Baltimore, 1986, Chap.8.
In Vitro Antibacterial, Antifungal and Antitrichomonas Activities
All new compounds used in this study were tested in vitro for their activity
against representative Gram positive and Gram negative bacteria, Candida
albicans, Aspergillus niger, and Trichomonas vaginalis. The in vitro antimi-
crobial activity is reported as the Minimum Inhibitory Concentrations
(MICs).
[10] J.G. Meingassner, J. Thurner, Antimicrob. Agents Chemother. 1979, 15,
254–259.
Received: April 14, 2000 [FP480]
Arch. Pharm. Pharm. Med. Chem. 333, 341–346 (2000)