Synthesis and investigation of some 1,4-disubstituted 2-pyrrolidinones

Article abstract of DOI:10.1007/s10593-006-0220-1

A series of condensation products of 1-aryl-4-hydrazinecarbonyl-2- pyrrolidinones with acetone, 2,4-pentanedione, and aromatic aldehydes was obtained and identified by the combination of IR, mass and ¹H, ¹³C NMR spectroscopy. The results of their structural studies by NMR spectroscopy are provided. It was ascertained that the presence of the NH group determines the existence of the mixtures of the Z/E-isomers of compounds under study. The availability of Z-isomer as a sterically favorable one was also verified by computer molecular modeling. Springer Science+Business Media, Inc. 2006.

Full text of DOI:10.1007/s10593-006-0220-1

Chemistry of Heterocyclic Compounds, Vol. 42, No. 9, 2006
SYNTHESIS AND INVESTIGATION OF SOME
1,4-DISUBSTITUTED 2-PYRROLIDINONES
K. Brokaite1, V. Mickevicius1, and G. Mikulskiene2
A series of condensation products of 1-aryl-4-hydrazinecarbonyl-2-pyrrolidinones with acetone,
2,4-pentanedione, and aromatic aldehydes was obtained and identified by the combination of IR, mass
1
and H, 13C NMR spectroscopy. The results of their structural studies by NMR spectroscopy are
provided. It was ascertained that the presence of the NH group determines the existence of the mixtures
of the Z/E-isomers of compounds under study. The availability of Z-isomer as a sterically favorable one
was also verified by computer molecular modeling.
Keywords: 1-aryl-4-hydrazinecarbonyl-2-pyrrolidinones, hydrazones, Z/E-isomers, pyrazoles,
condensation, spectroscopy.
The products of condensation of carbohydrazides with carbonylic compounds – hydrazones – and its
ring-closure reactions are well known and have been thoroughly studied. Compounds of these types are
important for both chemical and pharmacological purposes and show analgetic, antidepressive, and bactericidal
activities [1]. 1-Aryl-substituted 4-carboxy-2-pyrrolidinones and their salts, esters, amides, and nitriles are plant
growth stimulators [2]. The first nucleophilic reaction used in this work was hydrazinolysis of the ester function.
Acid hydrazides 2a-c were prepared from the corresponding esters 1a-c and hydrazine monohydrate in refluxing
2-propanol (Scheme 1).
Condensation of compounds 2a-c with acetone gave the corresponding isopropylidenehydrazine-
carbonyl-2-pyrrolidinones 3a-c, and the one – 2b with aromatic aldehydes – 1-aryl-4-arylidenehydrazine-
carbonyl-2-pyrrolidinones 5-9. 1-Aryl-4-[(3,5-dimethylpyrazol-1-yl)carbonyl]-2-pyrrolidinones 4a-c were
synthesized by condensation of hydrazides 2a-c with 2,4-pentanedione in 2-propanol in the presence of a
catalytic amount of hydrochloric acid.
N-Substituted hydrazones 10-12 were obtained in good yields by alkylation of 1-aryl-4-
arylidenehydrazinecarbonyl-1-pyrrolidinones 5, 6 and 8 with ethyl iodide in the presence of potassium
hydroxide and potassium carbonate with excess of ethyl iodide without solvent.
1
The structure of the studied compounds 3-12 was elucidated by the methods of IR, mass and H,
13C NMR spectroscopy. Because of the different nature of fragments of the molecules of the tentative
1
13
compounds their structural features were mostly unfolded by H, C NMR spectroscopy. Investigation of such
structural fragments revealed information concerning the relation between the effects of substituents, their steric
arrangement, and the possibility to participate in hydrogen bonding and conjugation. The signals in the NMR
spectra were assigned [3, 4] on the basis of chemical shift theory, multiplicities, signal intensities, and
comparison with suitable model compounds. The assignment was confirmed by 13C NMR APT spectra. The
results obtained are given in Tables 2-5. The identification of aromatic carbons in the 13C NMR spectra
__________________________________________________________________________________________
1
Kaunas University of Technology, Kaunas 50254, Lithuania; e-mail: Vytautas.Mickevicius@ktu.lt.
2 Institute of Biochemistry, Vilnius 08662, Lithuania. Published in Khimiya Geterotsiklicheskikh Soedinenii,
No. 9, pp. 1336-1345, September, 2006. Original article submitted May 21, 2004.
1158
0009-3122/06/4209-1158©2006 Springer Science+Business Media, Inc.

presented some difficulties due to the unknown pyrrolidinone ring influence. Therefore, the model compound (4-
isopropylidenehydrazinecarbonyl-1-phenyl-2-pyrrolidinone) was synthesized, and the increments of the
pyrrolidinone ring for benzene carbons were calculated (∆δ: Ci = 10.72, Co = -9.07, Cm = 0.11, Cp = -4.52 ppm)
and proved to be useful for the prediction of the chemical shifts of benzene carbons in other compounds under
study. Probably due to the hindered rotation around the C(1')–N(1) bond, in compounds 3c and 4c with
3,5-Me2C6H3 substitution the C-5 atom in pyrrolidinone ring is deshielded about 2 ppm, the C-2 atom shielded
about 0.5 ppm, and the C-4 atom in compound 4c – shielded about 1.5 ppm compared with suitable effects in
compounds 3a,b, 4a,b with 3-Me and 4-Me substituents in the benzene ring.
O
N
O
N
R
R
Me
Me
COOMe
CONHN=C
1a–c
3a–c
MeCOMe
N2H4 . H2O
O
N
O
MeCOCH2COMe, H+
R
R
N
CON
Me
N
CONHNH2
2a–c
Me
4a–c
R1CHO
O
(for 2b)
O
N
EtI
R
N
R
CONHN=CHR1
(for 5,6,8)
CONN=CHR1
Et
10–12
5–9
1-4 a R = 3-MeC6H4, b R = 4-MeC6H4, c R = 2,5-MeC6H3; 5-12 R = 4-MeC6H4;
5, 11 R1 = 4-BrC6H4, 6, 10 R1 = 4-O2NC6H4, 7 R1 = 4-HOC6H4,
8, 12 R1 = 4-Me2NC6H4, 9 R1 = 9-ethyl-3-carbazolyl
The tentative compounds 3a-c, 5-9 exhibit characteristic structural features due to the presence of the
azomethine fragment (C=N) [5-7], on the one hand, and the amide group (CO–NHR) [4, 5] on the other hand.
Due to the possibility of a different arrangement of the substituents with respect to the C=N fragment or carbonyl
oxygen in the amide group, the existence of two isomers is possible. Such steric structural changes are well
reflected in the NMR spectra.
There are many works published on the structure and spectroscopic properties of hydrazones and amides
[8-12]. In this paper we describe compounds 3a-c, 5-9 which have shown two sets of some resonances.
Numerous attempts have been made to analyze compounds 3a-c which possess two Me substituents in the N=C
fragment. Thus, a double set of resonances in this case is observed due to the features of the amide group.
Fragment N=C(CH3)2 may be displaced as Z or E with respect to carbonyl oxygen atom [4, 5, 10-12]. When the
mentioned fragment is located as E, H of the hydrazide group is turned as Z. Such a situation is favorable for
1159

formation of internal hydrogen bonding [13, 14]. The resonances of carbon atoms sensitive to such structural
changes are shifted downfield. As a result of hydrogen bond formation, the carbonyl group carbon is more
positively charged as its deshielding is observered (found at ~173 ppm). Otherwise, when fragment N=C(CH3)2
is in the Z-position, there is no possibility for internal hydrogen bonding between CO and NH groups. In this
case the geometrical isomer, which resonance signals are shifted upfield, is obtained. The carbonyl group carbon
atoms in these isomers resonate at 168 ppm. The studied compounds 5-9 exhibit a double set of resonances,
which may be due to the presence of the amide group as well as different arrangement of substituents with
respect to the N=C group (Z/E-forms), because the mentioned compounds possess dissimilar substitution in the
N=C group. Differences in the chemical shifts of compounds 3a-c are observed for CO (about 5.1) and N=C
(about 5.0), for C-4 (1.4), C-3 (0.9), C-5 (0.6), C-2 (0.1), CH3 (0.3 ppm). The differences in the chemical shifts
of compounds 5-9 are the following: for CO (about 4.9) and N=C (about 3.3), for C-4 (2), C-3 (0.7), C-5 (0.4),
C-2 (0.2 ppm).
TABLE 1. Data of Compounds 2-4 and 5-12
Found, %
——————
Calculated, %
Com-
pound
Empirical
formula
mp, °C*
Yield, %
C
H
N
2a
2b
2c
3a
3b
3c
4a
4b
4c
5
C12H15N3O2
C12H15N3O2
C13H17N3O2
C15H19N3O2
C15H19N3O2
C16H21N3O2
C17H19N3O2
C17H19N3O2
C18H21N3O2
C19H18BrN3O2
C19H18N4O4
C19H19N3O3
C21H24N4O2
C27H26N4O2
C21H22N4O4
C21H22BrN3O2
C23H28N4O2
61.05
61.79
61.77
61.79
63.09
63.14
65.91
65.91
66.09
65.91
66.53
66.88
69.01
68.67
68.53
68.67
69.98
69.43
57.06
57.01
62.04
62.29
67.34
67.64
69.37
69.21
73.58
73.95
63.83
63.95
58.42
58.89
6.77
6.48
5.8
6.48
6.63
6.93
6.4
7.01
6.80
7.01
7.15
7.37
6.21
6.44
6.23
6.44
6.80
6.68
4.85
4.53
5.10
4.95
5.32
5.68
18.29
18.01
18.36
18.01
16.27
16.99
15.47
15.37
15.55
15.37
14.73
14.62
13.41
14.13
13.95
14.13
13.49
13.28
10.36
10.50
15.42
15.29
12.23
12.45
15.37
15.37
12.53
12.78
13.99
14.20
9.76
9.81
216-217
181-182
140-141
167-168
100-101
132-133
115-116
124-125
125-126
246-247
228-229
205-206
210-211
224-225
216-217
175-176
152-153
85
79.4
40.2
71
40.5
35.2
52.4
78.5
40
91.5
91.5
69.6
92.1
88.6
65
6
7
8
6.52
6.64
7.66
5.98
5.40
5.62
5.55
5.18
9
10
11
12
53
70.82
70.38
7.43
7.19
14.30
14.27
66.7
_______
* Solvent for crystallization: 2-propanol (compounds 2a-c, 3a-c, 4b, 9-12),
ethanol (compounds 5-8), acetone (compound 3b), toluene
(compounds 4a,c).
1160

TABLE 2. 13C NMR Spectral Data of Compounds 3a-c, 4a-c
R2
R1
O
2'
R2
R1
3'
O
1'
3
e'
R3
N
2
2'
3'
Me
N
4
1'
3
4
R3
N
e
f
4'
2
5
N
g
CO
5'
6'
4'
R4
5
6'
CONHN=CMe2
5'
R4
Me
g'
3a-c
4a-c
a R1 = R3 = R4 = H, R2 = Me; b R1 = R2 = R4 = H, R3 = Me; c R1 = R4 = Me; R2 = R4 = H
δ, ppm (DMSO-d6)
Carbon
atoms
3a
3b
3c
4a
4b
4c
E
Z
E
Z
E
Z
C-1'
C-2'
C-3'
C-4'
C-5'
C-6'
C-2
139.18
136.78
137.29
130.54
132.15
128.18
135.71
138.98
120.10
137.92
124.68
128.44
136.58
119.54
129.03
133.21
129.03
119.54
171.20
35.35
137.04
130.42
132.14
128.14
135.74
126.99
170.85
36.50
120.01 119.94 119.44 119.33
137.90
124.68
128.46
129.04
133.02
129.04
116.69 116.57 119.44 119.33 127.06 126.99 116.78
172.03 171.92 171.84 171.74 171.53 171.45 171.39
C-3
35.86 34.99 35.78 34.90
34.31 32.91 34.30 32.90
50.87 50.24 50.83 50.21
35.54
34.06
52.64
34.37
33.38
52.12
35.36
35.09
50.21
C-4
35.04
33.65
C-5
50.15
51.95
C=O
N=C
CH3
173.63 168.52 173.64 168.56 173.81 168.73 172.57
156.17 151.19 156.15 151.18 156.05 151.07
173.33
172.79
17.59 17.19 17.59 17.08
25.23 24.92 24.92 25.22
25.18
17.98
17.54
24.91
2'-CH3
3'-CH3
4'-CH3
5'-CH3
C-e
15.12
17.02
21.16
21.37
21.12
20.37
20.28
20.26
152.01
111.50
143.79
152.09
111.53
143.83
152.08
111.53
143.83
C-f
C-g
C-e'
13.99 or 13.99 or 14.02 or
13.53 13.53 13.48
13.99 or 13.99 or 14.02 or
13.53 13.53 13.48
C-g'
Direct comparison of the data obtained from these examinations shows remarkably similar changes in the
chemical shifts. The most significant differences are for the same carbons, which are mostly affected due to the steric
perturbations. The differences in the chemical shifts become smaller or disappear completely for carbons that are
more distant from the center of the exchanges.
Only one set of resonances is present in the spectra of compounds 10-12. These compounds are the
corresponding alkylated derivatives of 6, 5, 8, and the NH group with mobile H is absent in their molecules.
Apparently, the presence of the NH group in compounds 3a-c and 5-9 causes the stabilization of some steric
structures, which are reflected in the NMR spectra.
13
It has been noted that the C NMR spectra of compounds 4a-c do not show splitting of the resonances.
Such spectral data are assigned in detail – the signals are resolved sufficiently to permit individual identification
1161

1162

1163

TABLE 4. 1H NMR Spectra of Compounds 3-12
Com-
pound
Chemical shifts, coupling constants, δ, ppm (J, Hz)
3a
1.87, 1.88, 1.93, 1.93 (6H, 4s, Z/E N(CH3)2); 2.30 (3H, s, 3'-CH3); 2.60-2.79 (2H, m,
2JHCH = 16.9, 3JHCCH = 7.2, 3JHCCH = 9.2, CH2CO); 3.36-3.47 (0.5H, m, CH); 3.83-4.07
(2H, m, CH2N and 0.5 H, m, CH); 6.94-7.46 (4H, m, Ar); 10.20, 10.30 (1H, 2s, Z/E NH)
3b
3c
4a
4b
4c
1.87, 1.88, 1.93, 1.93 (6H, 4s, Z/E N(CH3)2); 2.27 (3H, s, 4'-CH3); 2.59-2.78 (2H, m,
2JHCH = 16.9; 3JHCCH = 7.2, 3JHCCH = 9.2, CH2CO); 3.36-3.47 (0.4H, m, CH);
3.81-4.08 (2H, m, CH2N and 0.6H, m, CH); 7.16 (2H, d, J = 7.6, H-2',6');
7.52 (2H, d, J = 7.6, m, H-3',5'); 10.20, 10.29 (1H, 2s, Z/E NH)
1.88, 1.89, 1.93, 1.95 (6H, 4s, Z/E N(CH3)2); 2.10, 2.12 (3H, 2s, 3'-CH3); 2.28 (3H, s,
5'-CH3); 2.55-2.73 (2H, m, 2JHCH = 16.9, 3JHCCH = 7.2, 3JHCCH = 9.2, CH2CO);
3.30-3.55 (0.4H, m, CH); 3.65-4.05 (2H, m, CH2N and 0.6H, m, CH);
7.04-7.21 (4H, m, Ar); 10.19, 10.28 (1H, 2s, Z/E NH)
2.21, 2.30 (6H, 2s, e'-, g'-CH3); 2.48 (3H, s, 3'-CH3); 2.77-2.94 (2H, m, 2JHCH = 10.2,
3JHCCH = 6. 9; 3JHCCH = 9.1, CH2CO); 3.98-4.22 (2H, m, 2JHCH = 10.2, 3JHCCH = 5.3,
3JHCCH = 8.8, CH2N); 4.42-4.52 (1H, m, CH2CHCH2); 6.22 (1H, s, CH=);
6.94-7.46 (4H, m, Ar)
2.20, 2.27 (6H, 2s, e'-, g'-CH3); 2.48 (3H, s, 4'-CH3); 2.76-2.84 (2H, m, 2JHCH = 17.2;
3JHCCH = 6.9, 3JHCCH = 9.1, CH2CO); 3.97-4.22 (2H, m, 2JHCH = 17.2, 3JHCCH = 5.6;
3JHCCH = 8.9, CH2N); 4.45-4.52 (1H, m, CH2CHCH2); 6.23 (1H, s, CH=); 7.16 (2H, d,
J = 8.4, H-2',6'); 7.52 (2H, d, J = 8.4, H-3',5')
2.09, 2.18 (6H, 2s, e'-, g'-CH3); 2.26 (3H, s, 3'-CH3); 2.47 (3H, s, 5'-CH3);
2.70-2.89 (2H, m, 2JHCH = 17.2, 3JHCCH = 8.6, 3JHCCH = 9.2, CH2CO); 3.79-4.08 (2H, m,
2JHCH = 9.9, 3JHCCH = 5.3; 3JHCCH = 9.5, CH2N); 4.47-4.57 (1H, m, CH2CHCH2);
6.22 (1H, s, CH=); 7.02-7.16 (3H, m, Ar)
2.28 (3H, s, 4'-CH3); 2.65-2.91 (2H, m, 2JHCH = 16.9, 3JHCCH = 7.4, 3JHCCH = 9.8,
CH2CO); 3.29-3.43 (1H, m, CH2CHCH2); 3.90-4.17 (2H, m, CH2N);
7.15-7.69 (4H, m, Ar); 8.01, 8.20 (1H, 2s, Z/E CH=); 11.64, 11.70 (1H, 2s, Z/E NH)
2.28 (3H, s, 4'-CH3); 2.69-2.90 (2H, m, 2JHCH = 17.0, 3JHCCH = 7.3, 3JHCCH = 9.8,
CH2CO); 3.26-3.44 (1H, m, CH2CHCH2); 3.94-4.20 (2H, m, CH2N);
5
6
7
8
7.54-8.30 (4H, m, Ar); 7.80, 8.14 (1H, 2s, Z/E CH=); 11.86, 11.93 (1H, 2s, Z/E NH)
2.28 (3H, s, 4'-CH3); 2.66-2.86 (2H, m, 2JHCH = 16.9, 3JHCCH = 7.6, 3JHCCH = 9.4,
CH2CO); 3.26-3.42 (1H, m, CH2CHCH2); 3.90-4.14 (2H, m, CH2N); 6.80-7.56 (4H, m,
Ar); 7.94, 8.11 (1H, 2s, Z/E CH=); 9.89 (1H, s, OH); 11.36, 11.42 (1H, 2s, Z/E NH)
2.28 (3H, s, 4'-CH3); 2.95, 2.96 (6H, 2s, N(CH3)2); 2.66-2.82 (2H, m, 2JHCH = 16.9,
3JHCCH = 7.6; 3JHCCH = 9.8, CH2CO); 3.25-3.39 (1H, m, CH2CHCH2); 3.90-4.10 (2H, m,
CH2N); 6.71-7.56 (4H, m, Ar); 7.91, 8.08 (1H, 2s, Z/E CH=);
11.28, 11.33 (1H, 2s, Z/E NH)
9
1.32 (3H, t, J = 6.9, NCH2CH3); 2.28 (3H, s, 4'-CH3); 2.71-2.94 (2H, m, 2JHCH = 17.0,
3JHCCH = 7.7, 3JHCCH = 8.9, CH2CO); 3.27-3.49 (1H, m, CH2CHCH2);
3.94-4.23 (2H, m, CH2N); 4.43 (2H, q, J = 6.9, NCH2CH3); 7.16-8.46 (4H, m, Ar); 7.87,
7.90 (1H, 2s, Z/E CH=); 11.51, 11.57 (1H, 2s, Z/E NH)
10
11
12
1.14 (3H, t, J = 7.0, NCH2CH3); 2.28 (3H, s, 4'-CH3); 2.76-2.92 (2H, m, 2JHCH = 9.8,
3JHCCH = 6.0, 3JHCCH = 9.6, CH2CO); 3.90-4.19 (2H, m, 2JHCH = 9.8, 3JHCCH = 7.6,
3JHCCH = 9.2, CH2N); 4.08 (2H, q, J = 7.0, NCH2CH3); 4.30-4.41 (1H, m, CH2CHCH2);
7.13-8.33 (4H, m, Ar); 8.26 (H, s, CH=)
1.12 (3H, t, J = 7.0, NCH2CH3); 2.28 (3H, s, 4'-CH3); 2.74-2.89 (2H, m, 2JHCH = 17.3,
3JHCCH = 7.8, 3JHCCH = 8.9, CH2CO); 3.92-4.16 (2H, m, 2JHCH = 9.8, 3JHCCH = 6.1,
3JHCCH = 9.0, CH2N); 4.05 (2H, q, J = 7.0, NCH2CH3); 4.26-4.37 (1H, m, CH2CHCH2);
7.17-7.80 (4H, m, Ar); 8.11 (1H, s, CH=)
1.08 (3H, t, J = 7.1, NCH2CH3); 2.29 (3H, s, 4'-CH3); 2.97 (6H, s, N(CH3)2); 2.80,
2.83 (2H, d, 3JHCCH = 8.4, CH2CO); 3.91-4.16 (2H, m, 2JHCH = 9.6, 3JHCCH = 6.1,
3JHCCH = 9.0, CH2N); 4.03 (2H, q, J = 7.1, NCH2CH3); 4.20-4.31 (1H, m, CH2CHCH2);
6.75-7.65 (4H, m, Ar); 7.98 (1H, s, CH=)
of each carbon [15-17]. The characteristic resonances found at 152, 143 and 111 ppm are assigned to suitable
carbons of the pyrrazole ring.
1
Considerable attention has been paid to the H NMR spectra of the compounds under study [4, 5]. The
1H NMR spectra of compounds 4a-c demonstrate the presence of a characteristic signal at 6.22 ppm, which
confirms the existence of the pyrrazole ring. The spectra of compounds 3a-c possess two signals of the NH
1164

group of equal intensity, indicating the same possibility for two different isomers to exist. Two resonances of the
NH group appear in compounds 5-9, and their intensity relationships can be expressed quantitatively: 30%:70%.
These observations indicate the existence of E- and Z-isomers, and meanwhile show that the Z-isomer is
predominant against the E-isomer. Computer molecular modeling applied to the structural studies of these
compounds has shown the same trend.
1
The H NMR multiplets of the pyrrolidinone ring of compounds 3a-c, 5-9 are complex and difficult to
resolve [18]. The integral intensity is not distributed evenly in accordance with the number of protons of the
COCH2, CH, NCH2 fragments. Their chemical shifts, multiplicity, and integral intensity change significantly due
to the sensitivity of the influence of substituents, formation of extended π-system between the benzene fragment
and the N(1)–C(2) bond, and formation of the different isomers in the side chain of the ring.
EXPERIMENTAL
1
The H and 13C NMR spectra were recorded on a Varian Unity Inova 300 (300 MHz) spectrometer
operating in Fourier transform mode with TMS as an internal standard. Melting points were determined on an
automatic melting point apparatus APA1 and are uncorrected. The IR spectra were determined in potassium
bromide pellets on a Perkin-Elmer FT-IR system spectrum GX spectrometer. Mass spectral data were obtained
by a Waters (Micromas) ZQ 200 Spectrometer.
The molecular formulas of the studied compounds, data of elemental analysis, and magnitudes of the melting
points and yields are presented in Table 1.
1-Aryl-4-hydrazinecarbonyl-2-pyrrolidinones 2a-c. A solution of the corresponding esters 1a-c
(0.2 mol), hydrazine hydrate, (30.04 g, 0.6 mol) and 2-propanol (30 ml) was refluxed for 1 h. The reaction
mixture was cooled and the precipitate was filtered and washed with 2-propanol and diethyl ether.
Compound 2a. IR spectrum, ν, cm-1: 3313.76 (NH2); 3282.02 (NH); 1683.50 (C=O); 1637.47 (C=O);
782.69-649.15 (Ar). Mass-spectrum, m/z: 234.4 [M]+.
Compound 2b. IR spectrum, ν, cm-1: 3311.28 (NH2); 3281.56 (NH); 1681.07 (C=O); 1637.08 (C=O);
822.36-650.77 (Ar). Mass-spectrum, m/z: 234.4 [M]+.
Compound 2c. IR spectrum, ν, cm-1: 3325.58 (NH2, NH); 1678.09 (C=O); 1630.80 (C=O);
808.68-647.92 (Ar). Mass-spectrum, m/z: 248.4 [M]+.
1-Aryl-4-isopropylidenhydrazinecarbonyl-2-pyrrolidinones 3a-c. A solution of the corresponding
hydrazides 2a-c (4.3 mmol) and acetone (30 ml) was refluxed for 3 h. The reaction mixture was cooled and the
precipitate was filtered and washed with diethyl ether.
Compound 3a. IR spectrum, ν, cm-1: 3213.18 (NH); 1698.54 (C=O); 1682.95 (C=O); 784.57-664.58
(Ar). Mass-spectrum, m/z: 274.4 [M]+.
Compound 3b. IR spectrum, ν, cm-1: 3190.66 (NH); 1701.57 (C=O); 1674.91 (C=O); 825.91-658.3
(Ar). Mass-spectrum, m/z: 274.4 [M]+.
Compound 3c. IR spectrum, ν, cm-1: 3205.12 (NH), 1705.36 (C=O); 1680.45 (C=O); 865.96-684.97
(Ar). Mass-spectrum, m/z: 288.4 [M]+.
1-Aryl-4-[(3,5-dimethylpyrazol-1-yl)carbonyl]-2-pyrrolidinones 4a-c.
A
solution of the
corresponding hydrazides 2a-c (13 mmol) and 2,4-pentandione (3.86 g, 39 mmol) and 2-propanol (50 ml) in the
presence of catalytic amount of hydrochloric acid was refluxed for 2 h. The solvent was evaporated. The product
precipitated from water. The precipitate was filtered and washed with water.
Compound 4a. IR spectrum, ν, cm-1: 1727.13 (C=O); 1698.67 (C=O); 845.65-687.93 (Ar).
Mass-spectrum, m/z: 298.4 [M]+.
Compound 4b. IR spectrum, ν, cm-1: 1731.92 (C=O); 1701.47 (C=O); 822.56-708.64 (Ar).
Mass-spectrum, m/z: 298.4 [M]+.
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Compound 4c. IR spectrum, ν, cm-1: 1721.54 (C=O); 1698.73 (C=O); 843.18-698.69 (Ar).
Mass-spectrum, m/z: 312.4 [M]+.
1-Aryl-4-arylidenhydrazinecarbonyl-2-pyrrolidinones 5-9. A solution of hydrazide 2b (3.02 g,
13 mmol), the corresponding aldehyde (19 mmol), in ethanol (30 ml) was refluxed for 2 h. The reaction mixture
was cooled and the precipitate was filtered and washed with ethanol and diethyl ether.
Compound 5. IR spectrum, ν, cm-1: 3263.13 (NH); 1663.86 (C=O, C=O); 852.96-670.52 (Ar).
Mass-spectrum, m/z: 400 [M]+.
Compound 6. IR spectrum, ν, cm-1: 3124.4 (NH); 1691.03 (C=O); 1656.09 (C=O); 1530.49 (NO2);
856.12-687.90 (Ar). Mass-spectrum, m/z: 367.3 [M]+.
Compound 7. IR spectrum, ν, cm-1: 3292.14 (NH, OH); 1677.32 (C=O); 1635.72 (C=O); 836.53-683.36
(Ar). Mass-spectrum, m/z: 338.3 [M]+.
Compound 8. IR spectrum, ν, cm-1: 3226.82 (NH); 1673.81 (C=O); 1611.93 (C=O); 845.37-689.05
(Ar). Mass-spectrum, m/z: 365.4 [M]+.
Compound 9. IR spectrum, ν, cm-1: 3013.71 (NH); 1686.65 (C=O); 1665.50 (C=O); 805.77-683.19
(Ar). Mass-spectrum, m/z: 439.3 [M]+, 365.4.
1-Aryl-4-[(2-arylidene-1-ethylhydrazine)carbonyl]-2-pyrrolidinones 10-12. A solution of the
corresponding hydrazide 5, 6, 8 (27 mmol) and ethyl iodide (50 ml) in the presence of KOH (81 mmol) and
K2CO3 (81 mmol) was stirred at 50°C for 4 h. The reaction mixture was diluted with acetone (50 ml), and the
inorganic compounds were filtered off. The solvent was evaporated under reduced pressure. The product
precipitated from water, and the precipitate was filtered and washed with water.
Compound 10. IR spectrum, ν, cm-1: 1693.22 (C=O); 1673.49 (C=O); 1613.25 (NO2); 846.62-679.03
(Ar). Mass-spectrum, m/z: 395.3 [M]+.
Compound 11. IR spectrum, ν, cm-1: 1673.44 (C=O, C=O); 816.25-671.31 (Ar). Mass-spectrum, m/z:
428 [M]+.
Compound 12. IR spectrum, ν, cm-1: 1698.10 (C=O); 1663.18 (C=O); 833.01-674.37 (Ar).
Mass-spectrum, m/z: 393.4 [M]+.
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