Approaches to the construction of substituted 4-amino-1 H -pyrrol-2(5 H)-ones

Article abstract of DOI:10.1021/jo3004309

Fully substituted 4-aminopyrrolones are easily accessed via simple routes starting from imines, ketones, or α-bromophenyl acetonitriles. Imines were reacted with KCN/NH₄Cl in aqueous ethanol to produce α-arylamino benzyl cyanides. On the other hand, ketones were transformed to the desired α-amino nitriles using a modified Strecker reaction. Then, α-amino nitrile precursors were allowed to react with a suitable acyl halide to produce the corresponding amides. Further treatment of these amides with ethanolic KOH converted them to highly substituted 4-amino-1H-pyrrol-2(5H)- one derivatives in moderate to excellent yields.

Full text of DOI:10.1021/jo3004309

Note
pubs.acs.org/joc
Approaches to the Construction of Substituted 4-Amino-1H-pyrrol-
2(5H)-ones
Hassan Zali-Boeini,* Mehdi Mobin, Khadijeh Hajibabaei, and Maryam Ghani
Department of Chemistry, University of Isfahan, 81746-73441, Isfahan, Iran
S
* Supporting Information
ABSTRACT: Fully substituted 4-aminopyrrolones are easily
accessed via simple routes starting from imines, ketones, or α-
bromophenyl acetonitriles. Imines were reacted with KCN/
NH4Cl in aqueous ethanol to produce α-arylamino benzyl
cyanides. On the other hand, ketones were transformed to the
desired α-amino nitriles using a modified Strecker reaction.
Then, α-amino nitrile precursors were allowed to react with a
suitable acyl halide to produce the corresponding amides.
Further treatment of these amides with ethanolic KOH
converted them to highly substituted 4-amino-1H-pyrrol-
2(5H)-one derivatives in moderate to excellent yields.
yrrolones are well-known compounds because of their
existence in natural products,1−3 vast number of biological
methylene compounds such as β-keto esters and suffer from the
use of corrosive reagents, harsh reaction conditions, expensive
catalysts or reagents, and environmentally pollutant organic
solvents. Therefore, developing a simple and versatile method
for the preparation of 4-aminopyrrolones can be an important
goal in synthetic organic chemistry. Herein, we report simple
and efficient routes for the synthesis of highly substituted 4-
aminopyrrolones from readily available starting materials.
All imines used in this study were prepared by direct
condensation of the benzaldehyde derivatives and anilines in
ethanol. At the outset of one of approaches, a solution of
aldimines 1 in EtOH was reacted with aqueous solution of
KCN in the presence of equimolar amounts of NH4Cl and
catalytic amount of hexadecyltrimethylammonium bromide
(HTAB) to produce α-arylamino derivatives of the correspond-
ing aryl acetonitrile 2a−j (Scheme 1). Secondary amines 2a−j
also could be available directly by means of the three-
component reaction between aldehydes, amines, and trime-
thylsilyl cyanide TMS-CN (modified Strecker reaction).21
TMS-CN works better in cyanoamination reactions, but
KCN is a cheap and industrial reagent; however, its toxicity
does not make it an environmentally friendly reagent. The
secondary amines 2a−j were treated with phenyl acetyl chloride
in refluxing dioxane to give the corresponding amides 3a−j
which, after treatment with ethanolic KOH, transformed to the
desired 4-amino-1,3,5-triaryl-1H-pyrrol-2(5H)-ones 4a−j in
rather good to excellent yields (64−91%).
P
activities,4−6 and potential for applications in drug develop-
ment7−10 and the agricultural industry.11,12 In one approach to
synthesize pyrrolone derivatives, α,β-diketones react smoothly
in aqueous solutions at room temperature with a variety of
acetamides possessing a strong electron-withdrawing group in
the α-position to give 3-substituted 5-hydroxy-1H-pyrrol-
2(5H)-ones.13 Another approach utilizes cycloisomerization
reaction of alkylidenecarbene derivative of amides intermediate
to the corresponding pyrrolones.14 In a similar route,
substituted cyclohepta[b]pyrrol-2-ones have been prepared
via the base-promoted reaction between diethyl diazomethy1
phosphonates and 2-oxopropanamide derivatives.15 In addition,
it has been shown that benzoylformanilide undergoes a
condensation reaction with acetophenones to yield aldol-type
products which after subsequent treatment with HCl convert to
the desired pyrrolones.16 Another method benefits from
ruthenium-catalyzed reaction of α,β-unsaturated imines with
carbon monoxide and ethylene for synthesizing 1,3-dihydro-
pyrrol-2-one ring systems.17
More recently, a super acid-catalyzed aza-Nazarov-type
cyclization has been reported for the synthesis of a fused
multiring pyrrolone system.18 In addition, flash vacuum
pyrolysis at 600 °C of methylaminomethylene derivatives of
Meldrum’s acid provides N-unsubstituted 3-hydroxypyrroles
and/or 1H-pyrrol-3(2H)-ones in good yields.19
Despite simple pyrrolones having no functional groups, 4-
aminopyrrolone derivatives are little known compounds, and
there are few reports about their synthesis in the literature. The
only reported examples of 4-amino-substituted pyrrolone have
been prepared by the reaction of pyrrolidin-2,4-diones with
primary amine derivatives.20
In another approach, α-bromobenzyl cyanides 5 were chosen
and reacted with aromatic amines 6 to produce the desired
substrate 2 and then by the same route converted to the
corresponding 4-aminopyrrolones 4. In order to evaluate the
Although the aforesaid protocols provide rather efficient
access to some pyrrolones, they work only with more acidic
Received: March 5, 2012
© XXXX American Chemical Society
A
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The Journal of Organic Chemistry
Note
Scheme 1
scope and the versatility of the method, other types of imines
were also investigated in the reaction course. Hence, ketimines
formed as intermediates in the modified Strecker reaction of
ketones 7 were directly transformed to primary amines 2k−r
with a mixture of KCN/NH4Cl/NH4OH/HTAB in one step,
and after treatment with an acetyl chloride derivative, amides
3k−r were produced in nearly quantitative yields. Further
treatment of the amides 3k−r with KOH/EtOH converted
them to the corresponding 3,5,5-trisubstituted 4-amino-1H-
pyrrol-2(5H)-ones 4k−r in moderate to good yields (55−
85%).
Using the optimized conditions, we next showed the
generality of the reaction by successful synthesis of eighteen
new 4-amino-1H-pyrrol-2(5H)-ones in moderate to excellent
yields (55−91%, Table 2).
Feasibility of the method for the preparative synthesis of the
pyrrolone product was also investigated. Hence, starting from
compound 1a on a 25 mmol scale, compound 4a was obtained
in 72% overall yield in three steps.
In summary, efficient and novel approaches for the synthesis
of highly substituted 4-amino-1H-pyrrol-2(5H)-one derivatives
from readily available starting materials have been developed. In
addition to the simplicity of the methods, high yields, and easy
workup, the salient futures of the methodologies lie in the fact
that the reactions are carried out using cheap starting materials
and in aqueous alcohols as safe and rather green solvent.
Additionally, purification of the products achieves with a simple
recrystallization in EtOH (95%). Moreover, the method is
compatible with a wide range of substituents such as halogen,
alkoxy, alkylthio, bulky aryl groups, etc. in the substrates.
To obtain the best results, influencing factors such as the
solvent and the base type were changed, and the screening
results are summarized in Table 1.
Table 1. Solvent and Base Screening in the Synthesis of
Pyrrolone 4a
entry
solvent
DMF
base
yield (%)
1
2
3
4
5
6
7
8
K2CO3
Et3N
37
41
59
67
68
31
EXPERIMENTAL SECTION
DMF
■
DMF
DBU
Caution! Potssium cyanide is highly toxic. Care should be taken to
avoid direct contact of the chemical or its solutions with the skin, and
impervious gloves should be worn to handle the reagent. All discarded
aqueous extracts should be neutralized with bleach before disposal.
General procedure for the preparation of amines 2a−j: A solution of
KCN (4M, 5.2 mL, 20.8 mmol) and HTAB (40 mg) was added with
vigorous stirring to a solution of aldimines 1a−j (20 mmol) in EtOH
(30 mL) at ambient temperature. Thereafter, the reaction mixture was
heated at 60 °C, and a solution of NH4Cl (4 M, 6 mL, 24 mmol) was
added dropwise during 2 min. After heating and stirring for a further
two hours, the reaction mixture was poured in a mixture of ice−water
and the crude product was filtered. Final purification was achieved by
crystallization from EtOH (95%) to afford amines 2a−j as white or off-
white materials.
DMF
KOH
KOH
MeONa
KOH
KOH
NMP
MeOH
EtOH
solvent-free
a
91
b
34
a
amide 3a (1 mmol), KOH (1.2 mmol, 0.2 mL, 6 M), EtOH (4 mL),
b
45 min. At 100 °C or at the melting point of the mixture, 60 min.
It is notable that increasing the reaction time and
temperature higher does not increase the yield of pyrrolones,
and our examinations demonstrated that in these situations the
reaction mixture was contaminated with some colored or tarry
materials. We were also surprised to find that MeONa/MeOH
showed little conversion to the desired product 4a and mainly
the formation of decomposition products were observed. This
is probably attributed to the higher basicity of MeONa/MeOH
compared to KOH, favoring the elimination of HCN from
cyanomethylamides.
General procedure for the preparation of amines1 2k−n: To a
solution of KCN (50 mmol, 3.25 g) in water (5 mL), NH4Cl (3.24 g,
60 mmol) in warm water (45 °C, 6 mL), and HTAB2 (70 mg) were
added. The solution was smoothly stirred and a solution of
acetophenone derivatives (49 mmol) in EtOH (16 mL) was added.
Then, the reaction mixture was stirred at 60 °C for a further 8 h. After
cooling to 5 °C a semisolid or an oily crude product was obtained.
B
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Note
Table 2. Construction of Highly Substituted 4-Amino-1H-pyrrol-2(5H)-ones
a
b
entry
R1
R2
R3
R4
product
yield (%)
1
2
4-MePh
Ph
Ph
H
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Cl
4a
4b
4c
4d
4e
4f
91
81
83
87
89
79
80
82
77
64
78
76
85
70
68
66
58
55
4-MePh
4-MePh
4-ClPh
4-ClPh
4-MeSPh
3,4-di-MeOPh
3,4-di-MeOPh
2-thienyl
9-anthracenyl
Me
H
3
4-MePh
Ph
H
4
H
5
4-MePh
4-MePh
Ph
H
6
H
7
H
4g
4h
4i
8
4-MePh
4-MePh
4-MePh
H
H
9
H
10
11
12
13
14
15
16
17
18
H
4j
Ph
4-MePh
4-ClPh
Ph
Et
4k
4l
H
Me
H
Me
4m
4n
4o
4p
4q
4r
H
CN
H
Et
Ph
Ph
Ph
Ph
H
Et
Me
Bn
H
Bn
H
−CH2(CH2)3CH2−
a
b
All products were characterized by IR, H NMR, 13C NMR, and elemental analysis. All yields refer to pure isolated products.
1
Further purification was achieved with flash chromatography on silica
gel using a mixture of EtOAc−hexane (1:4) as eluent.
MHz, DMSO-d6) δ 7.58 (d, J = 7.6 Hz, 2 H), 7.41 (d, J = 8.4 Hz, 2 H),
7.35 (t, J = 7.2 Hz, 2 H), 7.24 (d, J = 7.6 Hz, 2 H), 7.19 (t, J = 6.4 Hz,
1 H), 7.10 (d, J = 6.4 Hz, 2 H), 6.98 (d, J = 7.6 Hz, 2 H), 6.46 (s, 2 H),
5.66 (s, 1 H), 2.22 (s, 3 H), 2.15 (s, 3 H); 13CNMR (100 MHz,
DMSO-d6) δ 170.6, 160.4, 137.8, 136.4, 135.1, 133.4, 131.6, 129.7,
129.3, 128.5, 128.3, 127.9, 125.7, 121.0, 98.1, 62.7, 21.2, 20.8. Anal.
Calcd for C24H22N2O: C, 81.33; H, 6.26; N, 7.90. Found: C, 81.35; H,
6.30; N, 7.85.
General procedure for the preparation of amides 3a−n in dioxane:
In a round-bottomed flask, an acetyl chloride derivative (11 mmol)
was added dropwise at ambient temperature to a solution of amines
2a−n (10 mmol) in dioxane (10 mL) with good stirring. The reaction
mixture was heated at reflux conditions for further 3 h. Then, the
reaction mixture was cooled and poured into a mixture of ice−water.
The precipitated crude product was filtered and recrystallized in EtOH
(95%) to afford the corresponding amides as white solids.
4-Amino-5-(4-chlorophenyl)-1,3-diphenyl-1H-pyrrol-2(5H)-one
1
(compound 4d): white solid (628 mg, 87%); mp 254−257 °C; H
General procedure for the conversion of amides 3a−n to 4-amino-
1H-pyrrol-2(5H)-ones 4a−n: In a round-bottom flask, amide 3 (2
mmol) was dissolved in EtOH (95%, 5 mL) by heating the mixture at
75 °C. Then KOH solution (5 M, 0.5 mL) was added, and the reaction
mixture was vigorously stirred and heated at the same temperature for
further 45 min. After the reaction mixture was cooled to room
temperature, water (10 mL) was added and the crude precipitated
product filtered. Thereafter, the crude off-white solid compound was
recrystallized from EtOH (95%) to afford pure 4-amino-1H-pyrrol-
2(5H)-one 4 as a white and odorless solid.
NMR (400 MHz, DMSO-d6) δ 7.54−7.59 (m, 4 H), 7.35−7.43 (m, 6
H), 7.18−7.21 (m, 3 H), 6.91 (t, J = 7.2 Hz, 1 H), 6.63 (s, 2 H), 5.81
(s, 1 H); 13CNMR (100 MHz, DMSO-d6) δ 170.7, 160.2, 138.7, 137.2,
133.2, 133.1, 130.0, 129.2, 128.9, 128.5, 128.3, 125.8, 122.9, 120.8,
98.3, 62.0. Anal. Calcd for C22H17ClN2O: C, 73.23; H, 4.75; Cl, 9.83;
N, 7.76. Found: C, 73.18; H, 4.72; Cl, 9.80; N, 7.79.
4-Amino-5-(4-chlorophenyl)-3-phenyl-1-p-tolyl-1H-pyrrol-2(5H)-
one (compound 4e): white solid (667 mg, 89%); mp 256−257 °C; 1H
NMR (400 MHz, DMSO-d6) δ 7.57 (d, J = 7.6 Hz, 2 H), 7.34−7.42
(m, 8 H), 7.18 (t, J = 8 Hz, 1 H), 6.99 (d, J = 8 Hz, 2 H), 6.57 (s, 2
H), 5.76 (s, 1 H), 2.16 (s, 3 H); 13CNMR (100 MHz, DMSO-d6) δ
170.5, 160.0, 137.2, 136.2, 133.2, 133.1, 131.9, 130.0, 129.3, 129.1,
128.5, 128.3, 125.8, 121.0, 98.2, 62.1, 20.8. Anal. Calcd for
C23H19ClN2O: C, 73.69; H, 5.11; Cl, 9.46; N, 7.47. Found: C,
73.65; H, 5.15; Cl, 9.40; N, 7.50.
4-Amino-3,5-diphenyl-1-p-tolyl-1H-pyrrol-2(5H)-one (compound
1
4a): white solid (619 mg, 91%); mp 219−220 °C; H NMR (400
MHz, DMSO-d6) δ 7.18−7.58 (m, 12 H), 6.98 (d, J = 5.6 Hz, 2 H),
6.51 (s, 2 H), 5.72 (s, 1 H), 2.15 (s, 3H); 13CNMR (100 MHz,
DMSO-d6) δ 170.7, 160.3, 138.1, 136.3, 133.3, 131.9, 129.3, 129.1,
128.6, 128.3, 128.1, 128.0, 125.8, 121.0, 98.3, 62.9, 21.0. Anal. Calcd
for C23H20N2O: C, 81.15; H, 5.92; N, 8.27. Found: C, 81.20; H, 5.95;
N, 8.24.
4-Amino-5-(4-(methylthio)phenyl)-3-phenyl-1-p-tolyl-1H-pyrrol-
2(5H)-one (compound 4f): white solid (610 mg, 79%); mp 228−229
1
°C; H NMR (400 MHz, DMSO-d6) δ 7.59 (d, d, J = 8.2 Hz, J = 1.2
4-Amino-1,3-diphenyl-5-p-tolyl-1H-pyrrol-2(5H)-one (compound
Hz, 2 H), 7.43 (d, J = 8.4 Hz, 2 H), 7.37 (t, J = 7.6 Hz, 2 H), 7.31 (d, J
= 8.4 Hz, 2 H), 7.17−7.21 (m, 3 H), 7.00 (d, J = 8.4 Hz, 2 H), 6.50 (s,
2 H), 5.70 (s, 1 H), 2.42 (s, 3 H), 2.18 (s, 3 H); 13C NMR (100 MHz,
DMSO-d6): δ 170.1, 159.7, 138.0, 135.8, 134.1, 132.8, 131.2, 128.8,
128.1, 128.0, 127.7, 125.8, 125.2, 120.5, 97.7, 61.9, 20.3, 14.3. Anal.
Calcd for C24H22N2OS: C, 74.58; H, 5.74; N, 7.25; S, 8.30. Found: C,
74.60; H, 5.71; N, 7.30; S, 8.28.
1
4b): white solid (551 mg, 81%); mp 226−227 °C; H NMR (400
MHz, DMSO-d6) δ 7.54−7.59 (m, 4 H), 7.36 (t, J = 7.6 Hz, 2 H), 7.27
(d, J = 7.6 Hz, 2 H), 7.18−7.20 (m, 3 H), 7.11 (d, J = 7.6 Hz, 2 H),
6.89 (t, J = 7.2 Hz, 1 H), 6.52 (s, 2 H), 5.71 (s, 1 H), 2.23 (s, 3 H);
13CNMR (100 MHz, DMSO-d6) δ 170.8, 160.6, 139.0, 137.8, 135.1,
133.3, 129.7, 128.8, 128.5, 128.3, 127.8, 125.7, 122.6, 120.6, 98.0, 62.5,
21.2. Anal. Calcd for C23H20N2O: C, 81.15; H, 5.92; N, 8.23. Found:
C, 81.12; H, 5.96; N, 8.25.
4-Amino-5-(3,4-dimethoxyphenyl)-1,3-diphenyl-1H-pyrrol-2(5H)-
one (compound 4g): white solid (618 mg, 80%); mp 192−195 °C; 1H
NMR (400 MHz, DMSO-d6) δ 7.56−7.58 (m, 4 H), 7.36 (t, J = 7.6
Hz, 2 H), 7.17−7.21 (m, 3 H), 7.02 (s, 1 H), 6.82−6.92 (m, 3 H), 6.52
4-Amino-3-phenyl-1,5-di-p-tolyl-1H-pyrrol-2(5H)-one (compound
1
4c): white solid (588 mg, 83%); mp 224−228 °C, H NMR (400
C
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Note
(s, 2 H), 5.67 (s, 1 H), 3.73 (s, 3 H), 3.68 (s, 3 H); 13CNMR (100
MHz, DMSO-d6) δ 170.7, 160.7, 149.1, 148.9, 139.1, 133.4, 130.1,
128.8, 128.5, 128.3, 125.7, 122.7, 120.7, 119.6, 112.3, 111.9, 97.8, 62.6,
55.9, 55.9. Anal. Calcd for C24H22N2O3: C, 74.59; H, 5.74; N, 7.25.
Found: C, 74.64; H, 5.70; N, 7.28.
4-Amino-5-(3,4-dimethoxyphenyl)-3-phenyl-1-p-tolyl-1H-pyrrol-
2(5H)-one (compound 4h): yellow solid (656 mg, 82%); mp 155−
160 °C; 1H NMR (400 MHz, DMSO-d6) δ 7.59 (d, J = 7.2 Hz, 2 H),
7.44 (d, J = 8 Hz, 2 H), 7.36 (t, J = 7.2 Hz, 2 H), 7.18 (t, J = 7.2 Hz,
1H), 6.99−7.00 (m, 3H), 6.81−6.88 (m, 2 H), 6.48 (s, 2 H), 5.63 (s, 1
H), 3.72 (s, 3 H), 3.68 (s, 3 H), 2.17 (s, 3 H); 13CNMR (100 MHz,
DMSO-d6) 170.6, 160.5,149.1, 148.9, 136.5, 133.5, 130.2, 129.3, 128.9,
128.5, 128.3, 125.6, 121.0, 119.7, 112.3, 111.8, 97.8, 62.7, 55.9, 55.8,
20.8. Anal. Calcd for C25H24N2O3: C, 74.98; H, 6.04; N, 7.00. Found:
C, 74.95; H, 6.08; N, 7.04.
8.4 Hz, 2H), 7.10 (t, J = 7.2 Hz, 2H), 6.36 (s, 2H), 1.50−1.74 (m,
4H), 0.68−0.70 (m, 6H); 13C NMR (100 MHz, DMSO-d6) δ 173.2,
161.5, 129.0, 128.1, 127.2, 124.3, 99.2, 62.5, 29.5, 7.3. Anal. Calcd for
C14H18N2O: C, 73.01; H, 7.88; N, 12.16. Found: C, 73.11; H, 7.82; N,
12.23.
4-Amino-5-ethyl-5-methyl-3-phenyl-1H-pyrrol-2(5H)-one (com-
1
pound 4p): white solid (285 mg, 66%); mp 105−106 °C; H NMR
(400 MHz, DMSO-d6) δ 7.95 (s, 1H), 7.53 (d, J = 8.0 Hz, 2H), 7.27
(t, J = 8.0 Hz, 2H), 7.10 (t, J = 7.2 Hz, 2H), 6.41 (s, 2H), 1.51−1.75
(m, 2H), 1.06 (t, J = 6.8 Hz, 3H), 0.70 (t, J = 6.8 Hz, 3H); 13C NMR
(100 MHz, DMSO-d6) δ 172.4, 163.7, 136.4, 129.0, 127.8, 126.2,
124.3, 59.0, 30.2, 25.2, 7.6. Anal. Calcd for C13H16N2O: C, 72.19; H,
7.46; N, 12.95. Found: C, 72.06; H, 7.53; N, 12.23.
4-Amino-5,5-dibenzyl-3-phenyl-1H-pyrrol-2(5H)-one (compound
1
4q): white solid (411 mg, 58%); mp 125−127 °C; H NMR (400
MHz, DMSO-d6) δ 8.00 (s, 1H), 6.97−7.52 (m, 15H), 6.61 (s, 2H),
3.18−3.25 (m, 2H), 2.88−2.91 (m, 2H); 13C NMR (100 MHz,
DMSO-d6) δ 172.2, 159.6, 131.2, 130.3, 129.0, 128.2, 127.8, 127.4,
127.2, 126.2, 100.8, 63.4, 41.8. Anal. Calcd for C24H22N2O: C, 81.33;
H, 6.26; N, 7.90. Found: C, 81.46; H, 6.53; N, 7.83.
4-Amino-3-phenyl-5-(thiophen-2-yl)-1-p-tolyl-1H-pyrrol-2(5H)-
one (compound 4i): white solid (533 mg, 77%); mp 223−224 °C; 1H
NMR (400 MHz, DMSO-d6) δ 7.57 (d, J = 8.0 Hz, 2 H), 7.41−7.43
(m, 3 H), 7.36 (m, 3 H), 7.18 (t, J = 7.6 Hz, 1 H), 7.03 (d, J = 8.0 Hz,
2H), 6.94 (t, J = 4.4 Hz, 1 H), 6.64 (s, 2 H), 6.11 (s, 1 H), 2.19 (s, 3
H); 13C NMR (100 MHz, DMSO-d6) δ 170.0, 159.8, 136.1, 133.2,
129.7, 129.3,129.1, 128.5, 128.2, 128.0, 127.1, 126.7, 125.7, 121.5, 97.5,
59.1, 20.8. Anal. Calcd for C21H18N2OS: C, 72.80; H, 5.24; N, 8.09; S,
9.26. Found: C, 72.75; H, 5.30; N, 8.05; S, 9.32.
4-Amino-3-phenyl-1-azaspiro[4.5]dec-3-en-2-one (compound 4r):
1
white solid (267 mg, 55%); mp 85−87 °C; H NMR (400 MHz,
DMSO-d6) δ 7.74 (s, 1H), 7.53 (t, J = 7.2 Hz, 2H), 6.89−7.32 (m,
3H), 6.42 (s, 2H), 1.06−1.91 (m, 10 H); 13C NMR (100 MHz,
DMSO-d6) δ 172.3, 165.4, 133.9, 129.0, 128.1, 127.3, 124.3, 59.1, 34.5,
24.4, 21.8. Anal. Calcd for C15H18N2O: C, 74.35; H, 7.49; N, 11.56.
Found: C, 74.41; H, 7.33; N, 11.49.
4-Amino-5-(anthracen-10-yl)-3-phenyl-1-p-tolyl-1H-pyrrol-2(5H)-
1
one (compound 4j): white solid (564 mg, 64%); mp 296 °C dec; H
NMR (400 MHz, DMSO-d6) δ 8.98 (d, J = 8 Hz, 1 H), 8.60 (s, 1 H),
8.31 (d, J = 8 Hz, 1 H), 8.09, (d, J = 8 Hz, 1 H), 8.02 (d, J = 8 Hz, 1
H), 7.65−7.71 (m, 3 H), 7.52−7.56 (t, J = 8 Hz, 1 H), 7.40−7.47 (m,
5 H), 7.21 (t, J = 8 Hz, 1 H), 7.13 (d, J = 8 Hz, 2 H), 6.74 (d, J = 8 Hz,
2 H), 6.35 (s, 2 H), 1.98 (s, 3 H); 13C NMR (100 MHz, DMSO-d6) δ
170.6,161.9, 136.0, 133.7, 129.9, 129.8, 129.7, 128.9, 128.6, 128.3,
127.7, 126.7, 125.7, 125.5, 125.5, 124.2, 123.8, 123.3, 98.0, 62.5, 20.6.
Anal. Calcd For C31H24N2O: C, 84.52; H, 5.49; N, 6.36 Found: C,
84.43; H, 5.56; N, 6.21.
ASSOCIATED CONTENT
■
S
* Supporting Information
1
Complete copies of H NMR and 13C NMR spectra for all
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: h.zali@chem.ui.ac.ir.
4-Amino-5-methyl-3,5-diphenyl-1H-pyrrol-2(5H)-one (compound
■
1
4k): white solid (412 mg, 78%); mp 113−114 °C; H NMR (400
MHz, DMSO-d6) δ 7.71 (s, 1 H), 7.58 (d, J = 7.2 Hz, 2 H), 7.45 (d, J
= 7.6 Hz, 2 H), 7.27−7.38 (m, 5 H), 7.12 (t, J = 7.2 Hz, 1 H), 6.32 (s,
2 H), 1.75 (s, 3 H); 13C NMR (100 MHz, DMSO-d6): δ 172.6, 164.6,
142.8, 133.7, 128.1, 127.8, 127.4, 127.1, 126.0, 124.6, 96.5, 60.7, 23.6.
Anal. Calcd for C17H16N2O: C, 77.25; H, 6.10; N, 10.60 Found: C,
77.30; H, 6.13; N, 10.58.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
We are thankful to the University of Isfahan Research Council
for financial support of this work.
■
4-Amino-5-methyl-3-phenyl-5-p-tolyl-1H-pyrrol-2(5H)-one (com-
1
pound 4l): white solid (423 mg, 76%); mp 182−184 °C; H NMR
(400 MHz, DMSO-d6) δ 7.66 (s, 1 H), 7.57 (d, J = 7.2 Hz, 2 H),
7.33−7.29 (m, 4 H), 7.10−7.17 (m, 3 H), 6.27 (s, 2 H), 2.29 (s, 3 H),
1.72 (s, 3 H); 13C NMR (100 MHz, DMSO-d6) δ 172.6, 164.7, 139.8,
136.2, 133.7, 128.7, 127.8, 127.4, 125.9, 124.5, 96.4, 60.5, 23.7, 20.5.
Anal. Calcd for C18H18N2O: C, 77.67; H, 6.52; N, 10.06 Found: C,
77.70; H, 6.55; N, 9.98.
REFERENCES
■
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1
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