Admicellar catalysis in multicomponent synthesis of polysubstituted pyrrolidinones

Article abstract of DOI:10.1016/j.tetlet.2013.05.017

A multicomponent green methodology was developed to synthesize 3-hydroxy-2-pyrrolidinones under admicellar catalysis by TiO₂ nano-particles at room temperature (30 C). TiO₂ nano-particles in aqueous CTAB solution promote the formation of admicelles and the reaction occurs in admicellar environment. The methodology was successfully applied to synthesize a variety of 3-hydroxy-2-pyrrolidinones and 3′-hydroxyspiro- 2′-pyrrolidinone derivatives.

Full text of DOI:10.1016/j.tetlet.2013.05.017

Accepted Manuscript
Admicellar catalysis in multicomponent synthesis of polysubstituted pyrrolidi‐
nones
Rajib Sarkar, Chhanda Mukhopadhyay
PII:
S0040-4039(13)00765-X
DOI:
http://dx.doi.org/10.1016/j.tetlet.2013.05.017
TETL 42917
Reference:
To appear in:
Tetrahedron Letters
Received Date:
Revised Date:
Accepted Date:
19 February 2013
2 May 2013
5 May 2013
Please cite this article as: Sarkar, R., Mukhopadhyay, C., Admicellar catalysis in multicomponent synthesis of
polysubstituted pyrrolidinones, Tetrahedron Letters (2013), doi: http://dx.doi.org/10.1016/j.tetlet.2013.05.017
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2
Graphical Abstract
Admicellar catalysis in multicomponent
synthesis of polysubstituted pyrrolidinones
Rajib Sarkar, Chhanda Mukhopadhyay*
Leave this area blank for abstract info.
O
O
CO2R
+
RO2C
OH
RO2C
Ar
OH
N
ArCHO
H
Ar1NH2
CTAB, H2O
TiO2-np (10 mol%)
18 hrs, rt (30 oC)
O
O
N
CTAB, H2O
N
CO2R
Ar1
Ar1
N
O
TiO2-np (10 mol%)
18 hrs, rt (30 oC)
H

1
Tetrahedron Letters
journal homepage: www.elsevier.com
Admicellar catalysis in multicomponent synthesis of polysubstituted
pyrrolidinones
Rajib Sarkar, Chhanda Mukhopadhyay*
Department of Chemistry, University of Calcutta, 92 APC Road, Kolkata-700009, India, E-mail: cmukhop@yahoo.co.in, Phone: 91-33-23371104
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A multicomponent green methodology was developed to synthesize 3-hydroxy-2-pyrrolidinones
under admicellar catalysis by TiO2 nano-particles at room temperature (30 ˚C). TiO2 nano-
particles in aqueous CTAB solution promote the formation of admicelles and the reaction occurs
in admicellar environment. The methodology was successfully applied to synthesize a variety of
3-hydroxy-2-pyrrolidinones and 3'-hydroxyspiro-2'-pyrrolidinone derivatives.
Available online
2009 Elsevier Ltd. All rights reserved.
Keywords:
Pyrrolidinones
TiO2 nano-particle
Admicellar catalysis
Multicomponent reaction
Green methodology
Due to increasing concern over volatile organic solvents and
their toxic effects on human body, till date, a large number of
reactions have been successfully investigated in aqueous
medium.1 In some cases, owing to the limited solubility of the
organic compounds in water, surfactants were efficiently used to
promote the organic reactions to give the desired product in high
yields through the formation of micelles.2
anti microbial activity,11 antibacterial 12 and anti inflammatory13
activities. In our study, we have investigated the catalytic activity
of the admicelles formed by the adsorption of
cetyltrimethylammonium bromide (CTAB) on the surface of
TiO2 nano-particles (TiO2-np) at lower surfactant concentration
(below critical micellar concentration, CMC) for the
multicomponent14 green synthesis of the polysubstituted 3-
hydroxy-2-pyrrorolidinones and its spiro derivatives also.
Another very important reaction template in aqueous medium
called “admicelle” is a relatively new investigated phenomenon
in science. At lower surfactant concentration, admicelles are
formed in aqueous medium by the adsorption of surfactant on
solid-liquid interfaces of nano particles.3 Due to high surface area
and small size, nano particles have very unique properties and
they efficiently catalyze many reactions.4 However, in aqueous
medium, nano heterogeneous particles are self aggregated to
form larger particles having low catalytic activity and in such
cases, use of a surfactant leads to the formation of admicelles.5
Presence of the hydrophobic core within admicelles furnishes a
region which is able to solubilize the water-insoluble organic
compounds. This process is termed as “adsolubilization” or
“surface solubilization”.6 A reaction template is therefore formed
on the surface of the nano particles where the organic reactions
can be catalyzed by the nano catalyst under admicellar
environment. Formation of admicelles plays an important role in
many practical applications, including ore flotation, petroleum
recovery, food science, agriculture etc.7 and can significantly
improve the outcome of many reactions through conventional
admicellar catalysis.8
Initially the reaction was carried out with 4-methyl
benzaldehyde,
4-chloro
aniline
and
diethyl
acetylenedicarboxylate ester in aqueous medium at room
temperature (30 ˚C) (Scheme 1) using commercially available
TiO2 powder as a heterogeneous catalyst in the absence of
CTAB. The reaction mixture was stirred around 18 h at room
temperature (30 °C), but a gummy mass was obtained. This
problem arises due to the limited solubility of the reactants in
water. To overcome this problem, we focused our attention to
utilize TiO2 admicellar system as a reaction template. Therefore,
further study was done with the aqueous admicellar system
formed by commercially available TiO2 powder in aqueous
solution of CTAB (CTAB: CMC value 0.92 mM).15 At first, we
carried out the reaction in 0.1 mM aqueous CTAB solution but
the reaction did not take place. By using 0.8 mM aqueous
solution of CTAB in the reaction medium we got polysubstituted
3-hydroxy-2-pyrrolidinone as the product, although in very low
yields. Interestingly it was found that in comparison with
commercially available TiO2 powder, the maximum yield of the
polysubstituted 3-hydroxy-2-pyrrolidinone has been achieved by
employing TiO2 nano-particles. At 0.8 mM aqueous solution of
CTAB, formation of the admicelles by TiO2 nano-particles
efficiently catalyzed the synthesis of polysubstituted 3-hydroxy-
2-pyrrolidinone in high yields. In aqueous medium at low
Five
membered
nitrogen-containing
heterocyclic
polysubstituted 3-hydroxy-2-pyrrolidinones are one of the most
investigated class of compounds and have significant biological
activities like HIV-1 integrase inhibitors,9 anti cancer agents,10

2
concentration of CTAB (below CMC), adsorption of positively
charged cetyltrimethylammonium ions on negatively charged
sites of TiO2 surface (coulombic force) give hemimicelles where
the hydrophobic tails are exposed towards polar water medium,
then surfactant chain–chain interactions (non-coulombic force)
results to the formation of another layer where the head groups of
the surfactants are exposed towards water, thus a surfactant
bilayer was formed on the surface of TiO2-np, these assemblies
termed as admicelle, illustrated in Figure 1.3e,7b,16
Table 1. Effect of different surfactants on the yield of
pyrrolidinone 8a, in presence of 10 mol% TiO2-np
Entry
Surfactant
none
Concentration (mM)
Yield (%)
1
2
-
No reaction
CTAB
CTAB
CTAB
CTAB
CTAB
CTAB
CTAB
TTAB
SDS
0.1
0.6
0.8
0.9
1.0
8.0
10
No reaction
3
50
82
82
80
40
40
15
20
4
5
6
7
8
9
3.0
7.0
Figure 1. Surfactant bilayer of TiO2 admicelle.
10
Organic substrates come closer to each other in the
hydrophobic region of admicelles and reaction between them is
catalyzed by TiO2. At higher concentration of CTAB (just above
CMC), we noticed no increase in the yield of the product. But, at
very high concentration of CTAB yield of the reaction decreases
to a large extent. This is due to the reason that, at high CTAB
concentration (>>CMC), formation of micelles2 solubilize the
organic compounds within its hydrophobic core and the reaction
cannot undergo through admicellar catalysis. Use of TiO2 nano-
particles facilitated the formation of admicelles in aqueous
reaction medium and improved the reaction methodology
through its higher surface area, reusability and high catalytic
activity. Formation of admicelles in aqueous medium was
justified from analyzing the DLS data. In the absence of CTAB
in aqueous medium, TiO2 nano-particles aggregated themselves
to form larger particles and DLS study shows that the sizes of
these larger particles vary in a wide range from 3335.3 nm to
6539.5 nm. However, in 0.8 mM aqueous solution of CTAB,
TiO2 nano-particles formed admicelles and from DLS study we
found that sizes of the maximum number of admicelles is around
162.8 nm. These two DLS results are given in the supplementary
section.
Table 2. Effect of different catalysts on the yield of
pyrrolidinone 8a, in 0.8 mM aqueous solution of CTAB.
Entry
Catalyst
Amount
Time
(h)
18
Yield
(%)a
40
(mol %)
10
5
1
2
TiO2
nano TiO2
nano TiO2
nano TiO2
nano TiO2
SiO2
18
50
3
8
18
70
4
10
18
82
5
15
18
82
6
10
18
10
7
Alumina (acidic)
InCl3
10
10
18
20
8
18
18
18
18
10
9
MgSO4
10
10
10
5
10
11
P-TsOH
AcOH
30
35
a Isolated yield
After the successful application of admicellar reaction
template formed by TiO2-np in aqueous CTAB solution, we
investigated the action of other surfactants in the reaction
medium like TTAB (TTAB: CMC value 3.8 mM)15 and SDS
(SDS: CMC value 8.1 mM)18 below their CMC but we found that
0.8 mM CTAB is the best for the conversion to the product
mentioned. The effects of surfactants at different concentration
are summarized in Table-1. Catalytic activity of many other
catalysts were also investigated and from our study we found that
10 mol% TiO2 in 0.8 mM aqueous CTAB solution efficiently
catalyzed the reaction (Scheme 1) to produce the maximum yield,
the detailed results of using different catalysts are summarized in
Table-2.
Analyzing the results of our study, we were finally able to
optimize the reaction condition17 using 10 mol% nano-TiO2
catalysts in 0.8 mM aqueous CTAB solution and this optimized
reaction condition was adapted for future study. After
optimization of the reaction condition and in order to access a
range of polysubstituted 3-hydroxy-2-pyrrolidinone, we
investigated the scope of the reaction by varying electron-
withdrawing and electron-donating arylamines and aromatic
aldehydes with both the ester dimethyl acetylenedicarboxylate
and diethyl acetylenedicarboxylate (Scheme 2, Table 3, entries 1-
14). In all the reactions, the yields were highly satisfactory.
CO2R
RO2C
OH
4
3
O
OEt
EtO2C
OH
CHO
NH2
TiO2-np (10 mol%)
ArCHO
+
R1NH2
+
TiO2-np (10 mol%)
2
5
+
+
O
N
CTAB, H2O
18 hrs, rt (30 oC)
CTAB, H2O
18 hrs, rt (30 oC)
1.2 equiv.
1.2 equiv.
Ar
O
N
1
H3C
CH3
Cl
O
OEt
1.2 equiv.
CO2R
8a
1.2 equiv.
R1
1.2 equiv.
1.2 equiv.
Cl
Scheme 2. General synthesis of poly substituted 3-hydroxy-
Scheme 1. Synthesis of polysubstituted 3-hydroxy-2-
pyrrolidinone 8a.
2-pyrrolidinone (8a-8r).

3
Table 3. Synthesis of poly substituted pyrrolidinones 8a-8rb.
EtO2C
OH
O
Entry
Ar
R1
R
Product
Yield
13
14
m-O2NC6H4
C6H4
Et
759c
(%)a
N
EtO2C
OH
O
NO2
8m
1
p-CH3C6H4
p-ClC6H4
Et
82
80
N
MeO2C
OH
H3C
8a
p-CH3C6H4
p-BrC6H4
Me
O
85
N
Cl
N
MeO2C
OH
O
H3C
8n
2
3
4
p-MeOC6H4
p-ClC6H4
p-CH3C6H4
Me
Me
Et
Br
N
MeO
EtO2C
OH
O
8b
CH3
OH
15
16
17
18
p-CH3C6H4
p-ClC6H4
n-butyl
benzyl
benzyl
benzyl
Et
Me
Et
83
759c
78
MeO2C
H3C
8o
O
N
p-ClC6H4
859c
MeO2C
OH
Cl
8c
O
N
N
Cl
Cl
8p
EtO2C
OH
O
EtO2C
OH
O
p-MeOC6H4
p-CH3C6H4
N
82
MeO
p-BrC6H4
8d
Br
8q
CH3
OH
MeO2C
MeO2C
OH
759c
m-O2NC6H4
Me
709c
5
6
C6H4
C6H4
Me
Me
O
N
O
N
NO2
8e
MeO2C
8r
OH
a Isolated yield; b Reaction conditions: amine (1.2 mmol),
dialkyl acetylenedicarboxylate (1.2 mmol), aldehyde (1.2
O
N
p-ClC6H4
p-BrC6H4
80
Cl
8f
mmol) in 10 ml 0.8 mM aqueous CTAB solution at rt (30 ˚C)
Br
for 18 h
MeO2C
OH
O
7
8
9
m-O2NC6H4
C6H4
Me
Me
Me
729c
After successful application of the methodology for aryl
amine and aromatic aldehyde, we improved the reaction scope
by using isatin as a reactant (Scheme 3). Reaction of isatin
with various aryl amines gave 3'-hydroxyspiro [indoline-3,5'-
pyrroline]-2,2'-diones (Table 4, products 9a-9e).
N
NO2
8g
MeO2C
OH
O
N
p-BrC6H4
p-BrC6H4
p-ClC6H4
83
O
CO2R
RO2C
OH
Br
8h
TiO2-np (10 mol%)
Br
N
Ar1NH2
+
+
O
CTAB, H2O
O
MeO2C
OH
O
N
18 hrs, rt (30 oC)
N
1.2 equiv.
N
CO2R
Ar1
H
H
p-CH3C6H4
78
O
1.2 equiv.
1.2 equiv.
H3C
8i
Cl
Scheme 3. General synthesis of 3'-hydroxyspiro-2'-
pyrrolidinone (9a-9e).
EtO2C
OH
O
10
11
p-MeOC6H4
p-BrC6H4
C6H4
Et
759c
N
Table 4. Synthesis of 3'-hydroxyspiro-2'-pyrrolidinone 9a-
9eb.
MeO
8j
Entry
Ar1
R
Product
Yield
MeO2C
OH
O
(%)a
p-
Me
80
N
MeO2C
OH
MeOC6H4
Br
8k
1
p-CH3C6H4
Me
78
O
N
OMe
OH
N
EtO2C
H
O
12
C6H4
C6H4
Et
729c
9a
O
N
CH3
8l

4
MeO2C
OH
2
3
p-BrC6H4
Me
Me
73
O
N
N
O
H
9b
Br
N
MeO2C
OH
p-MeOC6H4
759d
O
N
H
O
9c
OMe
OH
EtO2C
4
5
3,4-dimethyl
C6H3
Et
Et
70
82
O
N
N
H
O
9d
CH3
CH3
EtO2C
OH
p-CH3C6H4
O
N
N
H
O
9e
CH3
a Isolated yield; b Reaction conditions: amine (1.2 mmol),
dialkyl acetylenedicarboxylate (1.2 mmol), isatin (1.2 mmol)
in 10 ml 0.8 mM aqueous CTAB solution at rt (30 ˚C) for 18
hours;
Scheme 4. Formation mechanism of poly substituted 3-
hydroxy-2-pyrrolidinone.
All the synthesized compounds were characterized by NMR,
IR, HRMS, CHN analysis and melting points. Finally we
confirmed the structure of polysubstituted 3-hydroxy-2-
pyrrolidinone and 3'-hydroxyspiro-2'-pyrrolidinone by a single-
crystal X-ray diffraction study of the compound 8b and
compound 9a. ORTEP structure of these two representative
compounds 8b (CCDC 918014) and 9a (CCDC 918013) are
given in the supplementary section. The spectral and analytical
data of these two representative compounds have been cited in
this manuscript18 while those for the remaining compounds are
given in the supplementary section also.
TiO2-np was prepared by the previously reported gel
combustion method20 and successfully reused with the standard
reaction for up to five cycles with a slight decrease in the yield of
the reaction (Table 5).
Table 5. Recycling of TiO2 nano-particles for the
multicomponent coupling reaction between 4-methyl
benzaldehyde,
4-chloro
aniline
and
diethyl
acetylenedicarboxylate ester in aqueous medium (product 8a)
Run
Time (h)
Yield (%)a
82
1
18
Based on previously reported reactions19 a plausible reaction
mechanism involving CTAB and TiO2-np in aqueous admicellar
environment was proposed for the formation of polysubstituted
3-hydroxy-2-pyrrolidinone (product 8a-8r), which is illustrated
in Scheme 4. In admicellar environment, lewis acidic character of
Ti4+ promotes the reaction between aldehyde and amine, which is
also facilitated by CTAB to produce the corresponding imine
(A). At the same time, Ti4+ from TiO2-np and CTAB catalyzed
the addition of water molecule to dialkyl acetylenedicarboxylate
to form the intermediate (B). After that in admicellar
environment, the Michael addition of intermediate (B) to imine
(A) catalyzed by Ti4+ and CTAB, gave the intermediate (C).
Next, the ring cyclization occurs by the intramolecular reaction
of arylamine group to the ester carbonyl activated by TiO2-np
and the intermediate (D) was formed. Finally, elimination of
corresponding alcohol from D gave the poly substituted 3-
hydroxy-2-pyrrolidinone (E). In each step of the reaction course
Ti4+ from admicelle formed by TiO2-np actively participated to
catalyze the reaction and the reaction occurs in admicellar
environment. Hence the role of admicelles formed by TiO2-np in
the formation of poly substituted 3-hydroxy-2-pyrrolidinones is
very significant and essential. Formation of 3'-hydroxyspiro-2'-
pyrrolidinone (product 9a-9e) follow the similar reaction
mechanism under admicellar environment.
2
3
4
5
6
18
18
18
18
18
82
82
82
80
76
a Isolated yield
In conclusion, we have successfully developed an
inexpensive, green and expeditious multicomponent reaction
methodology for the synthesis of polysubstituted 3-hydroxy-2-
pyrrolidinones using an admicellar system as a reaction template.
Water as a reaction medium improves the scope of the reaction
methodology to a large extent and the use of many hazardous
organic solvents can be avoided by using this methodology.
Formation of admicelles and catalytic activity of TiO2-np in this
multicomponent reaction protocol were very significant and are
extremely advantageous over many other heterogeneous and
organo catalysts. Finally, in our study, we illustrated the ability
of TiO2 admicellar system to subsidize the formation of poly
substituted 3-hydroxy-2-pyrrolidinones through multicomponent

5
11. Gein, V. L.; Armisheva, M. N.; Rassudikhina, N. A.; Vakhrin,
reaction between dialkyl acetylenedicarboxylate and a variety of
amines and aldehydes or isatin in aqueous medium at room
temperature (30 ˚C). To the best of our knowledge, using
admicellar system as a reaction template based on TiO2-np in
aqueous medium for the multicomponent synthesis of poly
substituted 3-hydroxy-2-pyrrolidinones at room temperature (30
˚C), have never been investigated so far.
M. I.; Voronina, E. V. Pharm. Chem. J. 2011, 45, 162-164.
12. Gein, V. L.; Mihalev, V. A.; Kasimova, N. N.; Voronina, E. V.;
Vakhrin, M. I.; Babushkina, E. B. Pharm. Chem. J. 2007, 41, 208-
210.
13. Gein, V. L.; Yushkov, V. V.; Kasimova, N. N.; Shuklina, N. S.;
Vasil’eva, Y. M.; Gubanova, M. V. Pharm. Chem. J. 2005, 39,
484-487.
14. (a) Ryabukhin, S. V.; Panov, D. M.; Plaskon, A. S.; Grygorenko,
O. O. ACS Comb. Sci. 2012, 14, 631-635. (b) Metten, B.;
Kostermans, M.; Baelen, G. V.; Smet, M.; Dehaen, W.
Tetrahedron 2006, 62, 6018-6028. (c) Sun, J.; Wu, Q.; Xia, E. Y.;
Yan, C. G. Eur. J. Org. Chem. 2011, 17, 2981-2986. (d) Han, Y.;
Wu, Q.; Sun, J.; Yan, C. G. Tetrahedron 2012, 68, 8539-8544.
15. Srivastava, M.; Singh, J.; Singh, S. B.; Tiwari, K.; Pathak, V. K.;
Singh, J. Green Chem. 2012, 14, 901-905. and the references cited
therein.
Acknowledgement
One of the authors (RS) thanks the Council of Scientific and
Industrial Research, New Delhi, for his fellowship (JRF). We
acknowledge grant received from UGC funded Major project, F.
No. 37-398 / 2009 (RS) dated 11-01-2010.
Supplementary Information
16. (a) Gangula, S.; Suen, S. Y.; Conte, E. D. Microchem. J. 2010, 95,
2-4. (b) Li, H.; Tripp, C. P. Langmuir 2004, 20, 10526-10533. (c)
Favoriti, P.; Treiner, C. Langmuir 1998, 14, 7493-7502.
Spectral and analytical data of all the compounds in Table 3
and Table 4 along with characterization data of TiO2-np are given
in the Supplementary Section. Crystallographic data of
compound 8b (CCDC 918014) and compound 9a (CCDC
918013) also been deposited at the Cambridge Crystallographic
Database Centre and these data can be obtained free of charge via
www.ccdc.ac.ck./data_request/cif.
17. General
synthesis
of
polysubstituted-3-hydroxy-2-
pyrrolidinones (8a-8r): Amine (1.2 mmol), dialkyl
acetylenedicarboxylate (1.2 mmol), aromatic aldehyde (1.2 mmol)
and TiO2-np (10 mol %) were sequentially added to a 10 ml of 0.8
mM aqueous CTAB solution in a 50 ml round bottomed flask and
stirred the mixture for next 18 h at room temperature (30 ˚C).
Reaction progress was monitored by TLC. After completion of the
reaction, the reaction mixture was diluted with 10 ml ethyl acetate
and the catalyst was separated from the mixture by filtering
through a sintered funnel. Recovered TiO2-np was washed with
DCM (2 ml × 4) to remove any adhering organic compound and
finally by water (2 ml). It was next vacuum dried and reused for
upto five cycles. After that the organic layer was separated out and
washed with brine solution (7 mL × 2) and evaporated under
vacuum to result in a crude product. The crude product was
purified by column chromatography over silica gel [ethyl acetate/
petroleum ether (60-80˚C)]. No further purification was needed.
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(c) Zhao, Q.; Philpott, R. T.; Oakes, T. D.; Conte, E. D. Analyst
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8. (a) Marquez, M.; Kim, S.; Jung, J.; Truong, N.; Teeters, D.;
Grady, B. P. Langmuir 2007, 23, 10008-10019. (b) Yuan, W. L.;
O’Rear, E. A.; Grady, B. P.; Glatzhofer, D. T. Langmuir 2002, 18,
3343-3351. (c) Glatzhofer, D. T.; Cho, G.; Lai, C. L.; O’Rear, E.
J.; Fung, B. M. Langmuir 1993, 9, 2949-2954.
18. (a)
4-Hydroxy-2-(4-methoxy-phenyl)-5-oxo-1-p-tolyl-2,5-
dihydro-1H-pyrrole-3-carboxylic acid methyl ester (8b) (Table
3, entry 2): White solid, 80%, m. p. 152-154 ˚C (EtOAc); Rf [30 %
1
EtOAc / petroleum ether (60-80 °C)]: 0.29; H NMR (300 MHz,
DMSO-d6) δ:7.42 (d, J = 8.4Hz, 2H, ArH), 7.16-7.07 (m, 4H,
ArH), 6.76(d, J = 8.4Hz, 2H, ArH), 5.97 (s, 1H, CH), 3.65 (s, 3H,
OCH3), 3.58 (s, 3H, OCH3), 2.20 (s, 3H, CH3); 13C NMR (75
MHz, DMSO-d6) δ: 163.8, 162.6, 158.8, 152.6, 134.6, 133.8,
129.1, 128.8, 128.2, 122.6, 113.7, 111.9, 60.2, 54.9, 51.1, 20.4; IR
(KBr) υ: 3186, 2955, 1720, 1669, 1513, 1424, 1383, 1306, 1230,
1172, 1112, 1037, 1009, 928, 835, 765 cm-1; HRMS (ESI-TOF):
m/z calcd. for C20H19NO5 [M+H]+: 354.1341. found: 354.1324;
Anal. calcd. for C20H19NO5; C: 67.98; H: 5.42; N: 3.96%. Found:
C: 67.91; H: 5.41; N: 3.89%. (b) 3'-Hydroxy-4'-
methoxycarbonyl-1'-4-methylphenylspiro[indoline-3,5'-
pyrroline]-2,2'-dione (9a) (Table 4, entry 1): Yellow solid, 78%,
m.p. 230-232 ˚C (MeOH); Rf [75 % EtOAc / petroleum ether (60-
80°C)]: 0.28; 1H NMR (300 MHz, DMSO-d6) δ: 10.76 (s, 1H,
NH), 7.27 (d, J = 7.2Hz, 1H, ArH), 7.18 (t, J = 7.2Hz, 1H, ArH),
7.08 (d, J = 8.1Hz, 2H, ArH), 6.92 (t, J = 7.8Hz, 1H, ArH), 6.84
(d, J = 8.1, 2H, ArH), 6.74 (d, J = 7.8Hz, 1H, ArH), 3.55 (s, 3H,
OCH3), 2.21(s, 3H, CH3); 13C NMR (75 MHz, DMSO-d6) δ:
173.6, 165.4, 161.8, 155.2, 143.3, 137.6, 132.2, 130.1, 129.6,
126.8, 125.0, 124.4, 122.2, 110.2, 109.2, 69.8, 51.2, 20.6; IR
(KBr) υ: 3262, 2952, 1722, 1688, 1620, 1515, 1466, 1419, 1364,
1284, 1204, 1162, 1131, 1093, 1025, 944, 924, 803, 760 cm-1;
HRMS (ESI-TOF): m/z calcd. for C20H16N2O5 [M+H]+: 365.1137.
found: 365.1123; Anal. calcd. for C20H16N2O5; C: 65.93; H: 4.43;
N: 7.69%. Found: C: 65.81; H: 4.52; N: 7.78%.
9. (a) Ma, K.; Wang, P.; Fu, W.; Wan, X.; Zhou, L.; Chu, Y.; Ye, D.
Bioorg. Med. Chem. Lett. 2011, 21, 6724-6727. (b) Pendri, A.;
Troyer, T. L.; Sofia, M. J.; Walker, M. A.; Naidu, B. N.; Banville,
J.; Meanwell, N. A.; Dicker, I.; Lin, Z.; Krystal, M.; Gerritz, S. W.
J. Comb. Chem. 2010, 12, 84-90.
10. (a) Michael, T.; Michael, A.; Andreas, T.; Ulrich, H.; Mirko, B.;
Johannes, N. A. Patent WO2008055945 (A1), 2008. (b)
Koz’minykh, V. O.; Igidov, N. M.; Zykova, S. S.; Kolla, V. E.;
Shuklina, N. S.; Odegova, T. Pharm. Chem. J., Khim.-Farm. Zh.
2002, 36, 188-191.
19. (a) Han, Y.; Wu, Q.; Sun, J.; Yan, C. G. Tetrahedron 2012, 68,
8539-8544. (b) Pandit, P.; Gayen, K. S.; Khamarui, S.; Chatterjee,
N.; Maiti, D. K. Chem. Commun. 2011, 47, 6933-6935. (c)
Khamarui, S.; Sarkar, D.; Pandit, P.; Maiti, D. K. Chem. Commun.
2011, 47, 12667-12669.
20. Sedghi, A.; Baghshahi, S.; Riahinouri, N.; Barkhordari, M. Dig. J.
Nanomater. Bios 2011, 6, 1457-1462.
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