Products of reaction between hetereno [a]-2,3-dihydro-2,3-pyrrolediones and aryl- or heterylamines and their pharmacological activity

Full text of DOI:10.1023/A:1010443516455

Pharmaceutical Chemistry Journal
Vol. 34, No. 12, 2000
PRODUCTS OF REACTION BETWEEN HETERENO[a]-2,3-
DIHYDRO-2,3-PYRROLEDIONES AND ARYL- OR HETERYLAMINES
AND THEIR PHARMACOLOGICAL ACTIVITY
I. V. Mashevskaya1, R. R. Makhmudov1, G. A. Aleksandrova2, O. S. Kudinova2,
S. V. Kol’tsova2, A. F. Goleneva3, and A. N. Maslivets3
Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 34, No. 12, pp. 13 – 16, December, 2000.
Original article submitted November 25, 1999.
We established earlier that 3-aroyl-1,2,4,5-tetrahydropyr-
rolo[1,2-a]quinoxaline- and 3-aroyl-1,2-dihydro-4H-pyrrolo-
[5,1-c][1, 4]benzoxazine-1,2,4-triones exhibit antimicrobial
and analgesic activity [1]. It seemed of interest to modify
their structure by introducing various heterocycles into the
molecule for the above-indicated compounds and to study
the chemical behavior of the products obtained and their
properties, by investigating the effect of the structure of the
compounds on their biological activity.
position of the dihydropyrroledione ring (atom 3a of com-
pounds I – VI) usually are unstable [2, 3] due to the
reversibility of the initial addition and the tendency toward
further conversions. So although according to TLC data the
addition products are present in the reaction mixture in prac-
tically all the studied cases, it is only in a certain number of
cases that they were isolated in pure form. The isolated com-
pounds VII – IX are colorless, while compound X is a yellow
crystalline material. Compounds VII – X are difficultly solu-
ble in conventional organic solvents and give a positive test
(cherry red color) for the presence of enol hydroxyl with an
alcoholic solution of ferric chloride. The solutions of com-
pounds VII – X in acetone or chloroform are violet or rasp-
berry-colored, and the intensity of the color increases upon
heating. This supports [2] the reversibility of addition of the
starting amines. In the IR spectra of compounds VII – X,
there are broad bands for stretching vibrations of the OH
groups in the 3000 – 3150 cm – 1 region, stretching vibration
bands for the lactone C4=O carbonyl in the
1775 – 1780 cm – 1 region, the lactam C1=O and aroyl carbo-
nyls in the 1700 – 1710 cm – 1 and 1600 – 1610 cm – 1 region
respectively. The spectral characteristics of compounds
VII – X correspond to the proposed structure and are similar
to the characteristics of the products of addition of alcohols
and dialkylamines to compounds I – VI [2]. The spectral
properties suggest that they exist in enolized form with an
intramolecular hydrogen bond of the H-chelate type between
the C2–OH groups and the carbonyl of the aroyl substituent
in the 3 position. Furthermore, in order to theoretically ex-
plain the direction of primary nucleophilic attack on compounds
I – VI, we calculated the electron density distribution in the
3-benzoyl-1,2,4,5-tetrahydropyrrolo[1,2-a]quinoxaline-1,2,4-
trione (III) molecule by the semi-empirical MNDO method using
the program GAUSSIAN-94W [4] with full optimization of its
geometry. According to the calculation results, the C1, C2, C4,
and C3a atoms are the most electron-deficient (the charges on
With this objective, we obtained the reaction products for
reaction of 3-aroyl-1,2-dihydro-4H-pyrrolo[5,1-c][1,4]ben-
zoxazine-1,2,4-triones (I – II) and 3-aroyl-1,2,4,5-tetrahyd-
ropyrrolo[1,2-a]quinoxaline-1,2,4-triones (III – VI) with
2-aminopyridine, 5-aminoisoquinoline, N-phenyl-o-phenyl-
enediamine, and 2,5-dichloroaniline.
Compounds I – VI [1] react easily with amines for a 1 : 1
mole ratio of the reagents. They react with most amines at
room temperature, but react with N-phenyl-o-phenylenedia-
mine with brief (1 – 3 min) heating. Two series of products
are formed as a result: N-substituted 3a-amino(heterylami-
no)-3-aroyl-2-hydroxy-1,3a-dihydro-4H-pyrrolo[2,1-c][1,4]
benzoxazine-1,4-diones (VII – X) (direction a) and substi-
tuted amides of 4-aryl-2,4-dioxo(Z)-3-(2-oxo-3,4-dihydro-
2H-1,4-benzoxazin-3-ylidene)butanoic acids (XI – XXIV)
(direction b), which is quite consistent with our data on the
reaction products for reaction of 3-aroylpyrrolobenzoxazin-
etriones with dialkylamines and arylamines [2].
The composition of compounds VII – XXIV was con-
firmed by elemental analysis data; the structure was con-
firmed by IR and PMR, spectroscopy.
The compounds formed via “direction a” as a result of
nucleophilic addition of amines to the carbon atom in the 5
1
Perm State University.
Natural Science Institute at Perm State University.
2
3
Institute of Technical Chemistry, Urals Branch, Russian Academy of Sci-
ences, Perm.
640
0091-150X/00/3412-0640$25.00 © 2001 Plenum Publishing Corporation

Products of Reaction Between Hetereno[a]-2,3-dihydro-2,3-pyrrolediones and Aryl- or Heterylamines
641
the atoms are respectively equal to: + 0.394, + 0.325,
+ 0.467, + 0.408) but the greatest contribution to the lowest
unoccupied molecular orbital comes from the 2pz orbital of
the C3a atom (coefficient 0.551). Earlier [3] we carried out a
MNDO calculation for the 3-benzoyl-1,2-dihydro-4H-pyrro-
lo[5,1-c][1,4]oxazine-1,2,4-trione (I) molecule with partial
optimization of the geometry. Comparing the calculations for
both structures shows that they are similar with respect to the
nature of the electron distribution and differ only in the abso-
lute values of the atomic orbital coefficients, i.e., if the reac-
tion is orbitally-controlled then it is specifically the C3a atom
which should be the target for nucleophilic attack, as is ob-
served in the result of the reaction for direction a.
should note that the values of the positive charges on the C3a
and C4 atoms of the molecule of compound III are higher
than on the C1 atom, so that the reason for attack at the C1
carbon atom probably involves thermodynamic factors: the
high stability of compounds XI – XXIV compared with the
products of nucleophilic attack at the C3a and C4 atoms of
compounds I – VI. Compounds XI – XXIV are formed (like
the products for reaction of pyrrolobenzoxazinetriones with
arylamines [2]) as a result of nucleophilic attack by the NH
group of aryl- and heterylamines on the C1 carbonyl carbon
atom of compounds I – VI and cleavage of the
dihydropyrroledione ring along the C1–N10 bond.
Compounds XI – XXIV are more stable than compounds
VII – X, although they easily undergo hydrolysis and
aminolysis. They are orange crystalline compounds, diffi-
cultly soluble in conventional organic solvents, and do not
give a positive test for the presence of enol hydroxyl with an
alcoholic solution of ferric chloride. In the IR spectra of
these compounds, there are stretching vibration bands for the
NH amide group of the side chain in the form of a narrow
peak in the 3150 – 3200 cm – 1 region, for the N4H group of
the heterocycle involved in the intramolecular hydrogen
bond of the H-chelate type in the 2965 – 3100 cm – 1 region,
for the C2=O carbonyl of the benzoxazine ring (compounds
XI, XII, XVII, XXII) in the 1730 – 1750 cm – 1 region, for
the amide C1=O and aroyl C4=O carbonyls in the
1610 – 1710 cm – 1 region, for the carbonyl group in the 2
X
O
X
O
(COCl)2
1-n
COC6H4R
1-n
CHCOC6H4R
N
N
H
XXV – XXXI
O
O
I – VI
direction b
direction à
R2NH2
X
O
X
O
NR2
1
COC6H4R1-n
COC6H4R-n
N
N
H
O
CONHR2
H2O, H+
O
OH
VII – X
XI – XXIV
position in the form of
a
broad band in the
1580 – 1610 cm – 1 region, and the “Amide II” band in the
1510 – 1540 cm – 1 region.
X = O (I, II); R1 = H (I), CH3 (II).
X = NH (III – VI); R1 = H (III), CH3 (IV), Br (V), NO2 (VI).
In the PMR spectra of the compounds (XIII, XIX, XX,
XXIV), in addition to signals from protons of the aromatic
substituents and the groups bonded to them, we see a singlet
from the amide NH group of the side chain in the 7.95 – 8.89
ppm region, a singlet from the amide N1H group of the
heterocycle in the 9.3 – 10.75 ppm region, and a singlet from
the N4H group of the heterocycle involved in the
intramolecular hydrogen bond of the H-chelate type in the
12.02 – 12.76 ppm region.
Cl
, X = O (VII, XI), NH (VIII);
R1 = H: R2 =
Cl
, X = O (IX). R1 = CH3: R2 =
R2 =
,
N
N
X = O (X); R2 =
R2 =
, X = O (XII).
,
N
N
Hydrolysis of compounds VII – XXIV when boiled in a
dioxane – 10% HCl mixture for 1 – 5 min leads to cleavage
of the pyrroledione ring and formation of benzoxazin-2-ones
(XXV, XXVI) and 2-quinoxalones (XXVII – XXXI).
X = NH: R1 = H(XIII), CH3 (XIV), Br (XV), NO2 (XVI).
R2 =
R2 =
, X = O: R1 = H(XVII), CH3 (XVIII).
N
EXPERIMENTAL CHEMICAL PART
, X = NH: R1 = H(XIX), CH3 (XX),
The IR spectra of the compounds obtained were taken in
vaseline oil on a UR-20 spectrophotometer. The PMR spec-
tra were recorded on an RYa-2310 spectrometer in DMSO-d6
solution, internal standard HMDS.
N
PhNH
Br (XXI). R1 = CH3, X = O, R2 =
PhNH
(XXII).
3a-(2,5-Dichlorophenylamino)-2-hydroxy-3-benzoyl-
3a,4-dihydro-1H-pyrrolo[2,1-c][1, 4]benzoxazine-1,4-dio-
ne (VII). A solution of 3.19 g (10 mmoles) of compound I in
50 ml anhydrous dioxane was added with stirring to a solu-
tion of 1.48 g (10 mmoles) of 2,5-dichloroaniline in 30 mL
X = NH, R2 =
: R1 = H (XXIII), CH3 (XXIV)
In the case of a charge-controlled reaction (direction b),
the C1 carbon undergoes nucleophilic attack. Moreover, we

642
I. V. Mashevskaya et al.
Compounds VIII – IX were obtained similarly.
Pyridylamide of 4-phenyl-2,4-dioxo-Z-3-(2-oxo-
1,2,3,4-tetrahydro-3-quinoxalinylindene)butanoic acid
TABLE 1. Characteristics of the Synthesized Compounds
Compound Yield, %
VI
m.p., °C
Empirical formula
57
75
70
62
35
73
82
84
72
79
76
83
89
81
84
91
87
79
163 – 165 (d.)
183 – 185 (d.)
176 – 178 (d.)
120 – 122 (d.)
260 – 262
230 – 232
222 – 224
215 – 217
250 – 252
237 – 239
147 – 149
187 – 189
212 – 214
227 – 230
257 – 259
217 – 219
292 – 293
223 – 226
C24H14Cl2N2O5
C24H15Cl2N3O4
C28H19N3O5
C23H15N3O5
C23H15N3O5
C24H17N3O5
C23H16N4O4
C24H18N4O4
C23H15BrN4O4
C23H15N5O6
C27H17N3O5
C28H19N3O5
C27H18N4O4
C28H20N4O4
C27H17BrN4O4
C31H23N3O5
C30H22N4O4
C31H24N4O4
(XIII). A solution of 3.32 g (10 mmoles) of compound III in
50 ml of anhydrous dioxane was added with stirring to a so-
lution of 0.94 g (10 mmoles) 2-aminopyridine in anhydrous
dioxane. The precipitate was filtered off and recrystallized
from a 1 : 1 mixture of acetonitrile and dioxane.
Compounds XI, XII, XIV – XXIV were obtained simi-
larly.
VIII
IX
X
XI
XII
XIII
XIV
XV
EXPERIMENTAL BIOLOGICAL PART
XVI
XVII
XVIII
XIX
XX
Procedure
We studied the analgesic and antimicrobial activity and
the acute toxicity of compounds VII – XXIV.
The acute toxicity (LD50) of the compounds when ad-
ministered orally was determined in outbred mice weighing
18 – 22 g [5]. Each dose of the compounds was studied using
10 animals. The compounds were administered as a 2%
starch mucilage suspension (dosage based on 0.1 ml per 10
g), after which the animals were observed for 10 days.
The analgesic activity was studied on outbred mice
weighing 18 – 22 g using the thermal stimulation (“hot
plate”) method [6]. The test compounds were injected
intraperitoneally in a dose of 50 mg/kg 30 min before plac-
XXI
XXII
XXIII
XXIV
anhydrous dioxane. After 24 h, a pale yellow precipitate of
compound VII fell out of solution. This was recrystallized
from acetonitrile.
TABLE 2. Toxicity and Biological Activity of the Synthesized Compounds
Antimicrobial activity (MIC), mg/ml, mini-
mum bacteriostatic concentration
Analgesic activity (la-
tency period of reflex
in seconds)
Rough acute toxicity
Compound
Dose, mg/kg
LD50, mg/kg
minimum bactericidal concentration
E. coli
St. aureus
1000
VII
50
> 1500
-“-
1000
20.2 ± 2.36*
19.6 ± 2.69*
VIII
IX
250/1000
250/1000
-“-
1000
1000
XII
1000/2000
250/500
2000
500/2000
250/500
125/500
XIII
XIV
XV
-“-
-“-
-“-
-“-
23.3 ± 1.44*
21.1 ± 4.12*
> 2000
> 2000
XVI
XVII
XVIII
XIX
XX
-“-
-“-
-“-
-“-
-“-
-“-
-“-
-“-
500/1000
500
500/1000
250
21.2 ± 2.12*
20.8 ± 2.66*
22.8 ± 1.74*
20.1 ± 2.04*
125/500
500/1000
1000
62.5/125
500/1000
1000
XXI
XXII
XXIII
XXIV
> 2000
> 2000
> 2000
> 2000
1000
> 2000
> 2000
1000
-“-
-“-
-“-
-“-
–
22.0 ± 1.72*
21.0 ± 1.26*
11.9 ± 2.3
Control (2% starch mucilage)
Voltaren
10
380
26.2 ± 0.84*
* p < 0.05 compared with control

Products of Reaction Between Hetereno[a]-2,3-dihydro-2,3-pyrrolediones and Aryl- or Heterylamines
643
ing the animals on a metal plate heated up to 53.5°C. The in-
dex of the change in pain sensitivity was the time the animal
remained on the “hot plate” before licking its hind paws,
measured in seconds. For untreated animals, the latency pe-
riod for the defensive reflex is no longer than 15 sec.
products of opening of the dihydropyrroledione ring (com-
pounds VIII, IX, XVI – XIX, XXIII, XXIV), the analgesic
activity is somewhat higher than for the addition products
(compounds VII and IX).
The antimicrobial tests show that the tested compounds
(except for compounds XV, XXI – XXIII) display different
degrees of antimicrobial activity and this activity: increases
when pyridylamide and quinolineamide moieties are present
in the molecule of the compound; is practically nonexistent
when the N-phenyl-o-phenyleneamine moiety is introduced;
and increases when a benzoxazin-2-one ring is present in the
molecule of the tested compound, compared with the
quinoxalone ring.
The antimicrobial action was determined by the two-fold
serial dilution method using cultures of two pathogenic refer-
ence strains of microorganisms (Escherichia coli, strain 675;
Staphylococcus aureus, strain 209-P) obtained from the
A. N. Tarasevich State Institute for Standardization and Con-
trol [5]. We prepared the starting dilutions of the microbe
bodies from a 24-hour agar culture using an optical standard.
The microbial load in determination of the minimum
bacteriostatic concentration (MBSC) corresponded to
2.5 ´ 105 microbe bodies per ml, while in determination of
the minimum bactericidal concentration (MBC) the micro-
bial load was 5.0 ´ 105 microbe bodies per ml. The microbial
suspension was added to the prepared dilutions of the drugs
in a nutrient medium. The results were counted after
thermostatting at 37°C for 20 h (MBSC) and 7 h (MBC).
Thus the results obtained indicate that the synthesized
compounds have low toxicity and exhibit analgesic and
antimicrobial action.
REFERENCES
1. A. N. Maslivets, I. V. Mashevskaya, L. I. Smirnova, et al., USSR
Inventor’s Certificate 1768603. IPC4 C 07D 498/04, A 61 K
31/535.
2. A. N. Maslivets, I. V. Mashevskaya, and Yu. S. Andreichikov,
Zh. Org. Khim., 29(10), 2056 – 2064 (1993).
RESULTS AND DISCUSSION
3. A. N. Maslivets, I. V. Mashevskaya, O. P. Krasnykh, et al., Zh.
Org. Khim., 28(12), 2545 – 2553 (1992).
All the tested compounds have an analgesic effect. The
most pronounced effect is exhibited by compounds XIII,
XVIII, and XXIII. The analgesic action does not change
much when we vary the aryl and heteryl substituents at the
nitrogen atom of the side chain for compounds VII – XXIV,
and is greatest in the case of the pyridylamide of
quinoxalinylidenebutanoic acid (compound XIII). For the
4. M. J. Frisch, G. W. Trucks, H. B. Schlegel, et al., Gaussian 94,
Revision E.3, Gaussian, Inc., Pittsburgh (1995).
5. G. N. Pershin, Methods in Experimental Chemotherapy [in Rus-
sian], Meditsina, Moscow (1971), pp. 113 – 115.
6. G. Wolfe and A. D. McDonald, J. Pharmacol. Exp. Ther., 80(3),
300 – 307 (1944).