Synthesis of 3-pyrroline-2-ones from amino acids and an aryl amine

Article abstract of DOI:10.3906/kim-1202-26

The conversion of the amino group of amino dicarboxylicacid esters and an aryl amine into N-substituted pyrrolinone derivatives with dimethoxydihydrofurane is described. The conversion also occurs with serine methylester but it decomposes very quickly. TU

Full text of DOI:10.3906/kim-1202-26

Turk J Chem
36 (2012) , 860 – 866.
¨
˙
c
ꢀ TUBITAK
doi:10.3906/kim-1202-26
Synthesis of 3-pyrroline-2-ones from amino acids and an
aryl amine
∗
˘
Nezire SAYGILI , Cemil AYDOGAN
Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Hacettepe University,
Sıhhiye, 06100 Ankara-TURKEY
e-mail: nezires@hacettepe.edu.tr
Received: 15.02.2012
The conversion of the amino group of amino dicarboxylicacid esters and an aryl amine into N -substituted
pyrrolinone derivatives with dimethoxydihydrofurane is described. The conversion also occurs with serine
methylester but it decomposes very quickly.
Key Words: Pyrrolinone, synthesis, amino acids
Introduction
More than 55% of organic chemistry publications are about heterocyclic compounds and dedicated to the field of
heterocyclic chemistry. Heterocyclic compounds have a wide range of applications. They are predominant among
the types of compounds used as pharmaceuticals, as agrochemicals, and as veterinary products.1,2 Nitrogen-
containing 5-membered heterocycles have a vital role in life because of their wide presence in biologically
important compounds.3 One of those heterocyclic systems is α,β-unsaturated-γ-amide heterocycles, which
are called pyrrolinones. Some pyrrolinone-containing natural products such as Jatropham (1) show antitumor
activity4 and some others are used as platelet aggregation inhibitors.5 Piracetam (2), which is medically used
as a nootropic drug, has a pyrrolidinone scaffold similar to that of pyrrolinones.
Pyrrolinones have also been used as precursors for other biologically important compounds6,7 and a
limited number of methods have been published for their synthesis.8−15 Recently, pyrrolinone-based pep-
tidomimetic compounds have been created and their inhibitory activity demonstrated in vitro.16,17 Aryl sub-
stituted pyrrolinones and pyrrolidinones are pharmaceutically important compounds. Some N -aryl substituted
∗Corresponding author
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Synthesis of 3-pyrroline-2-ones from amino..., N. SAYGILI, C. AYDOGAN
pyrrolidinones were synthesized newly and considered as anti-HIV-1 agents.18 In addition, 1-aryl-3-pyrrolin-2-
one derivatives were prepared from the corresponding γ-bromoacetoacetanilides.19
The synthesis of 5-membered heterocyclic frameworks was studied by our group before.21,22 One of
these includes the synthesis of pyrrolinone derivatives of some amino acids and we have reported a simple
one-pot method for the construction of the pyrrolinone ring system. As part of our ongoing research on N -
functionalization of pyrrolinone heterocycle21 we hereby studied the formation of a pyrrolinone ring with amino
dicarboxylicacids and also with an aryl amine.
Experimental
All reagents were of commercial quality and reagent quality solvents were used without further purification.
1 H- and 13 C-NMR spectra were determined on a Bruker DPX 400 MHz FT spectrometer. Mass spectra
were obtained on an Agilent 5973 Network Mass Selective Detector via HPP7-M Direct Insertion Probe. IR
spectra (KBr) were recorded on a Shimadzu FT-IR DR-8001 FT infrared spectrophotometer. The purity of
the compounds was assessed by thin layer chromatography on silica gel 60 F254. Column chromatography was
conducted on silica gel 60 (mesh size 0.063-0.200 mm). Melting points were measured on a Thomas Hoover
Capillary Melting Point Apparatus in an open capillary. Amino dicarboxylic acid methyl esters (4a-b) were
synthesized according to the literature20 and other amino dicarboxylic acid ethyl esters (4c-d) were purchased
from Aldrich.
General procedure for amino dicarboxylic acid esters21
2,5-Dimethoxy-2,5-dihydrofuran (3) (1 mmol) was stirred in water (10 mL) adjusted to pH 1 at room tempera-
ture over 12 h. Then amino dicarboxylic acid ester (4a-d) (1 mmol) was added and the mixture was stirred at
this temperature with monitoring by TLC. After the reaction was complete the mixture was neutralized with
solid NaHCO3 and extracted with dichloromethane (3 × 10 mL). The combined organic layers were dried over
MgSO4 and the solvent was removed under reduced pressure. The residue was purified by flash chromatography
to give the product (5a-d) as a reddish oil.
Dimethyl 2-(2-oxo-2,5-dihydro-1H-pyrrol-1-yl)pentanedioate (5a): Obtained according to the
general procedure, by using 4a (2.00 g, 8.28 mmol), as a reddish oil (0.58 g, 29%); Rf 0.48 (8:1 EtOAc-hexane);
1 H-NMR (400 MHz, CDCl3) δH 7.16 (1H, d, J = 6.0 Hz, 4ꢀ -CH), 6.13 (1H, d, J = 6.0 Hz, 3ꢀ -CH), 4.80 (1H,
dd, J = 4.4 & 10.7 Hz, 2-CH), 4.06 (2H, ABq , J = 20.1 Hz, 5ꢀ -CH2), 3.64 (3H, s, OCH3), 3.57 (3H, s, OCH3),
2.27 (2H, m, 4-CH2), 2.01 (2H, m, 3-CH2); 13 C-NMR (400 MHz, CDCl3)δC 172.79, 172.29 (1-C, 5-C), 171.18
(2ꢀ -C), 144.61 (4ꢀ -C), 126.92 (3ꢀ -C), 53.04 (2-C), 52.56, 51.82 (2 × OCH3), 50.06 (5ꢀ -C), 30.39 (4-C), 25.33
(3-C); MS (EI) m/z 241 (M+), 209 (M+ -OCH3), 182 (M+ -COOCH3), 122 (M+ - 2 × COOCH3 100%),
94 (M+ -pyrrolinone-2 × OCH3); IR (KBr) νmax (neat/cm−1) 3420.16, 3045.43, 2956.70, 1740.33, 1689.78,
1439.07, 1245.67, 1050.52. HRMS (EI) calcd for C11 H16 O5 N (M+H+) 242.1023, found 242.1020.
Dimethyl 2-(2-oxo-2,5-dihydro-1H-pyrrol-1-yl)succinate (5b): Obtained according to the general
procedure, by using 4b (1.00 g, 6.02 mmol), as a reddish oil (0.39 g, 29%); Rf 0.51 (8:1 EtOAc-hexane); 1 H-
NMR (400 MHz, CDCl3) δH 7.17 (1H, d, J = 6.0 Hz, 4ꢀ -CH), 6.18 (1H, d, J = 6.0 Hz, 3ꢀ -CH), 5.15 (1H, m,
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Synthesis of 3-pyrroline-2-ones from amino..., N. SAYGILI, C. AYDOGAN
2-CH), 4.14 (2H, ABq , J = 20.0 Hz, 5ꢀ -CH), 3.74 (3H, s, OCH3), 3.70 (3H, s, OCH3), 3.01 (2H, m, 3-CH2);
13 C-NMR (400 MHz, CDCl3)δC 169.93, 169.08 (1-C, 4-C), 168.61 (2ꢀ -C), 142.66 (4ꢀ -C), 125.45 (3ꢀ -C), 51.00
(5ꢀ -C), 50.43, 49.68 (2 × OCH3), 49.18 (2-C), 33.19 (3-C); MS (EI) m/z 227 (M+), 195 (M+ -OCH3), 168
(M+ -COOCH3), 136 (M+ -COOCH3 -OCH3), 108 (M+ -2 × COOCH3), 81 (pyrrolinone); IR (KBr) νmax
(neat/cm−1) 3462.10, 3048.23, 2955.63, 2852.61, 1740.22, 1690.79, 1438.76, 1240.43, 1005.17. HRMS (EI) calcd
for C10 H14 O5 N (M+H+) 228.0866, found 228.0900.
Dimethyl 2-(2-oxo-2,5-dihydro-1H-pyrrol-1-yl)malonate (5c): Obtained according to the general
procedure, by using 4c (2.00 g, 9.40 mmol), as a reddish oil (0.75 g, 33%); Rf 0.76 (8:1 EtOAc-hexane); 1 H-
NMR (400 MHz, CDCl3) δH 7.25 (1H, d, J = 6.0 Hz, 4ꢀ -CH), 6.21 (1H, d, J = 6.2 Hz, 3ꢀ -CH), 5.70 (1H, s,
2-CH), 4.39 (2H, s, 5ꢀ -CH2), 4.22 (4H, m, 2 × OCH2), 1.30 (6H, t, J = 7.15 Hz, 2 × CH3); 13 C-NMR (400
MHz, CDCl3)δC 171.54, 171.56 (1-C, 3-C), 168.23 (2ꢀ -C), 145.40 (4ꢀ -C), 126.13 (3ꢀ -C), 62.24 (5ꢀ -C), 57.40
(2-C), 51.03, 13.92 (2 × OCH2 CH3); MS (EI) m/z 213 (M+), 168 (M+ -OEt, 100%), 140 (M+ -COOEt), 96
(M+ -COOEt-OEt), 68 (M+ -2 × COOEt); IR (KBr) νmax (neat/cm−1) 3473.10, 3043.78, 2984.96, 2939.71,
2875.12, 1747.12, 1694.22, 1446.20, 1238.76, 1025.14. HRMS (EI) calcd for C11 H16 O5 N (M+H+) 242.1023,
found 242.1033.
Diethyl 2-(2-oxo-2,5-dihydro-1H-pyrrol-1-yl)pentanedioate (5d): Obtained according to the
general procedure, by using 4d (1.06 g, 6.06 mmol), as a reddish oil (0.53 g, 32%); Rf 0.45 (8:1 EtOAc-
hexane); 1 H-NMR (400 MHz, CDCl3) δH 7.20 (1H, d, J = 6.0 Hz, 4ꢀ -CH), 6.19 (1H, d, J = 6.0 Hz, 3ꢀ -CH),
4.87 (1H, dd, J = 4.4 Hz & 10.8 Hz, 2-CH), 4.19 (2H, q, J = 7.2 Hz, OCH2), 4.14 (2H, ABq , J = 20.0 Hz,
5ꢀ -CH2), 4.11 (2H, q, J = 7.2 Hz OCH2), 1.28 (3H, t, J = 7.2 Hz, CH3), 1.24 (3H, t, J = 7.2 Hz, CH3);
13 C-NMR (400 MHz, CDCl3)δC 175.1, 174.3 (1-C, 5-C), 169.51 (2ꢀ -C), 142.00 (4ꢀ -C), 128.00 (3ꢀ -C), 60.39
& 59.45 (2 × OCH2), 58.20 (5ꢀ -C), 52.10 (2-C), 49.20 (3-C), 27.88 (4-C), 23.37, 15.03 (2 × CH3); MS (EI)
m/z 269 (M+), 223 (M+ -OCH2 CH3), 196 (M+ -COOCH2 CH3), 181 (M+ -COOCH2 CH3 -CH3), 150 (M+ -
CO2 Et-OEt), 122 (M+ -2 × CO2 Et, 100%); IR (KBr) νmax (neat/cm−1) 3356.91, 3042.27, 2983.21, 1720.00,
1694.37, 1244.54, 1193.47, 1024.30. HRMS (EI) calcd for C13 H20 O5 N (M+H+) 270.1336, found 270.1296.
Methyl 3-hydroxy-2-(2-oxo-2,5-dihydro-1H-pyrrol-1-yl)propanoate (7): Obtained according to
the general procedure, by using 6 (3.92 g, 24.7 mmol), as a yellow oil (1.00 g, 22%); Rf 0.34 (8:1 EtOAc-
hexane); 1 H-NMR (400 MHz, CDCl3) δH 7.06 (1H, d, J = 6.0 Hz, 4ꢀ -CH), 6.01 (1H, d, J = 6.0 Hz, 3ꢀ -CH),
4.72 (1H, m, 2-CH), 4.11 (2H, ABq , J = 20.0 Hz, 5ꢀ -CH2), 3.90 (2H, dd, J = 5.5 Hz & 10.2 Hz, 3-CH2), 3.53
(3H, s, OCH3).
1-(2-hydroxyphenyl)-1H-pyrrol-2(5H)-one (9): Obtained according to the general procedure, by
using 8 (4.02 g, 36.5 mmol), as a brown oil (1.9 g, 30%); Rf 0.45 (3:2 EtOAc-hexane); 1 H-NMR (400 MHz,
CDCl3) δH 8.87 (1H, br-s, OH), 7.26 (1H, d, J = 6.0 Hz, 4ꢀ -CH), 7.15 (1H, t, J = 8.1 Hz, 4-CH), 7.08 (1H, d,
J = 8.1 Hz, 6-CH), 7.04 (1H, d, J = 8.1 Hz, 3-CH), 6.90 (1H, t, J = 8.1 Hz, 5-CH), 6.23 (1H, d, J = 6.0 Hz,
3ꢀ -CH), 4.46 (2H, s, 5ꢀ -CH2); 13 C-NMR (400 MHz, CDCl3) δC 171.9 (2ꢀ -C), 150.5 (2-C), 146.2 (4ꢀ -C), 128.1
(4-C), 127.3 (3ꢀ -C), 126.6 (1-C), 123.2 (5-C), 120.9 (6-C), 120.2 (3-C), 55.3 (5ꢀ -C); MS (EI) m/z 175 (M+ ,
100%), 158, 94, 82; IR (KBr) νmax (neat/cm−1) 3239.0, 1668.6, 1595.3, 1514.3, 1498.9, 1460.3, 1415.9, 1288.6,
1236.5, 754.3. HRMS (EI) calcd for C10 H10 O2 N (M+H+) 176.0706 found 176.0695.
862

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Synthesis of 3-pyrroline-2-ones from amino..., N. SAYGILI, C. AYDOGAN
Results and discussion
As shown in Figure 1, the condensation reaction of amino dicarboxylicacid esters with dimethoxydihydrofurane
gave the corresponding pyrrolinones (5a-d) in reasonable yields.
O
O
NH2
O
N
5M HCl
H2O, r.t.
OR
OR
RO
(CH2)n
(4a-d)
MeO
OMe
O
RO
(CH2)n
(5a-d)
(3)
O
O
4a: n = 2, R = CH3-
4b: n = 1, R = CH3-
4c: n = 0, R = CH3CH2-
4d: n = 2, R = CH3CH2-
Figure 1. The synthesis of pyrrolinones (5a-d).
As a complementary study to the above syntheses, the reaction of serine methylester (6) with 2,5-
dimethoxy-2,5-dihydrofuran (3) was carried out (Figure 2). The expected compound (7) was formed as a crude
product, which was decomposed quickly to an unresolved compound.
NH2.HCl
O
5M HCl
H2O, r.t.
HO
OCH3
N
MeO
OMe
O
HO
OCH3
O
(3)
(6)
O
(7)
Figure 2. Serine methylester derived pyrrolinone synthesis.
On the other hand, aromatic amines can also be used for the construction of pyrrolinone heterocycle.
However, aromatic amines such as aniline, p-anisidine, or p-toluidine are much weaker bases and nucleophiles
than the corresponding nonaromatic amines. For this reason they are seldom used as nucleophiles since the delo-
calization of the unshared electron pair of the nitrogen into the ring makes them poor nucleophiles. Nevertheless,
reacting aromatic amines with 2,5-dimethoxy-2,5-dihydrofuran to form N -aryl substituted pyrrolinones offers
a convenient route to the synthesis of some pharmaceutically important compounds. Therefore, we also tried
some primary aromatic amines and reported here the synthesis of N -(o-hydroxyphenyl) substituted pyrrolinone,
which was formed from the reaction of 2,5-dimethoxy-2,5-dihydrofuran with o-aminophenol (Figure 3).
The 1 H-NMR spectra of the pyrrolinone ring showed a doublet at 7.06-7.26 ppm for 4ꢀ -CH with a
coupling constant of 6.0 Hz, a doublet at 6.01-6.23 ppm for 3ꢀ -CH with a coupling constant of 6.0-6.2 Hz, and
an AB system at 4.06-4.14 ppm with a geminal coupling constant of 20.0-20.1 Hz for 5a, 5b, 5d, and 7 but a
singlet at 4.39-4.46 ppm for 5c and 9 (Table). Other protons appeared in the expected region. The 13 C-NMR
spectra of the pyrrolinone ring showed cyclic amide carbon at 168.2-171.9 ppm and the peaks at 142.0-146.2,
863

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Synthesis of 3-pyrroline-2-ones from amino..., N. SAYGILI, C. AYDOGAN
NH2
OH
O
N
5M HCl
H2O, r.t.
OH
MeO
OMe
O
(3)
(8)
(9)
Figure 3. The synthesis of o-hydroxyphenyl substituted pyrrolinone.
Table. 1 H-NMR data of 5a-d, 7, and 9.
4'
3'
2'
4'
3'
2'
4'
3'
2'
5'
5'
O
O
5'
O
N
N
1'
1'
O
N
1'
OH
HO
OCH3
OR
RO
(CH2)n
O
O
7
5
9
1H-NMR (CDCl3); δ (ppm); J (Hz)
5a 7.16 (1H, d, J = 6.0 Hz, 4ꢀ-CH), 6.13 (1H, d, J = 6.0 Hz, 3ꢀ-CH), 4.80 (1H, dd, J = 4.4
& 10.7 Hz, 2-CH), 4.06 (2H, ABq, J = 20.1 Hz, 5ꢀ-CH2), 3.64 (3H, s, OCH3), 3.57 (3H, s,
OCH3), 2.27 (2H, m, 4-CH2), 2.01 (2H, m, 3-CH2)
5b 7.17 (1H, d, J = 6.0 Hz, 4ꢀ-CH), 6.18 (1H, d, J = 6.0 Hz, 3ꢀ-CH), 5.15 (1H, m, 2-CH),
4.14 (2H, ABq, J = 20.0 Hz, 5ꢀ-CH), 3.74 (3H, s, OCH3), 3.70 (3H, s, OCH3), 3.01 (2H, m,
3-CH2)
5c 7.25 (1H, d, J = 6.0 Hz, 4ꢀ-CH), 6.21 (1H, d, J = 6.2 Hz, 3ꢀ-CH), 5.70 (1H, s, 2-CH), 4.39
(2H, s, 5ꢀ-CH2), 4.22 (4H, m, 2 × OCH2), 1.30 (6H, t, J = 7.15 Hz, 2 × CH3)
5d 7.20 (1H, d, J = 6.0 Hz, 4ꢀ-CH), 6.19 (1H, d, J = 6.0 Hz, 3ꢀ-CH), 4.87 (1H, dd, J = 4.4 Hz
& 10.8 Hz, 2-CH), 4.19 (2H, q, J = 7.2 Hz, OCH2), 4.14 (2H, ABq, J = 20.0 Hz, 5ꢀ-CH2),
4.11 (2H, q, J = 7.2 Hz OCH2), 1.28 (3H, t, J = 7.2 Hz, CH3), 1.24 (3H, t, J = 7.2 Hz,
CH3)
7
7.06 (1H, d, J = 6.0 Hz, 4ꢀ-CH), 6.01 (1H, d, J = 6.0 Hz, 3ꢀ-CH), 4.72 (1H, m, 2-CH), 4.11
(2H, ABq, J = 20.0 Hz, 5ꢀ-CH2), 3.90 (2H, dd, J = 5.5 Hz & 10.2 Hz, 3-CH2), 3.53 (3H, s,
OCH3)
9
8.87 (1H, br-s, OH), 7.26 (1H, d, J = 6.0 Hz, 4ꢀ-CH), 7.15 (1H, t, J = 8.1 Hz, 4-CH), 7.08
(1H, d, J = 8.1 Hz, 6-CH), 7.04 (1H, d, J = 8.1 Hz, 3-CH), 6.90 (1H, t, J = 8.1 Hz, 5-CH),
6.23 (1H, d, J = 6.0 Hz, 3ꢀ-CH), 4.46 (2H, s, 5ꢀ-CH2)
864

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Synthesis of 3-pyrroline-2-ones from amino..., N. SAYGILI, C. AYDOGAN
125.5-128.0, and 50.1-62.2 ppm correspond to 4ꢀ -CH, 3ꢀ -CH, and 5ꢀ -CH2 , respectively. In the IR spectra, ester
and amide carbonyl absorptions were observed at 1740 and 1690 cm−1 , and olefinic stretching at 1440 cm−1
.
Mass spectra (EI) confirmed the protonated molecular ion [M+H+ ] for the products 5a-d and 9 with 5%-100%
abundance. The high resolution mass spectrum gave good values for M+H, which corresponded well to the
calculated value for this molecular formula for all pyrrolinones (5a-d and 9).
Conclusion
2,5-Dimethoxy-2,5-dihydrofuran is the masked equivalent of 1,4-dicarbonyl compounds and it was used in this
work for the construction of the carbon chain of pyrrolinone heterocycle. The condensation reaction of amino
dicarboxylicacid esters (4a-d) with 2,5-dimethoxy-2,5-dihydrofuran (3) gave the corresponding 3-pyrroline-2-
ones (5a-d) in 29%-33% yields. The amino group of serine methylester also reacted with 2,5-dimethoxy-2,5-
dihydrofuran but the product (7) was unstable. Moreover, the amino group of o-aminophenol reacted readily
with 2,5-dimethoxy-2,5-dihydrofuran to form 9.
Acknowledgement
This research was supported by Hacettepe University (BAB-2009, 08 D05 301 002).
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