FeCl3 catalysed multicomponent divergent synthesis of a library of indeno-fused heterocycles

Article abstract of DOI:10.1039/c2ra23332k

A simple, straightforward and versatile multicomponent synthetic protocol for indeno-fused heterocycles, namely diindeno[1,2-b:2′,1′-e] pyridine, indeno[1,2-b]quinoline and indeno[1,2-b]cyclopenta[e]pyridine derivatives, has been developed. The strategy involves the one pot three component reaction of enaminone, dialkyl but-2-ynedioate and 1,3-indanedione catalysed by FeCl₃ in acetonitrile under reflux. The presence of rotamers in the products with 2- and 3-substituted anilines as the amine component adds some interesting features to this expeditious domino reaction. In the course of the reaction, four new bonds (two C-C and two C-N bonds) and one stereocenter are formed in one operation. Mild reaction conditions, operational simplicity, wide substrate scope, product diversity and overall good yield make this reaction highly efficient for the library synthesis of indeno-fused heterocycles.

Full text of DOI:10.1039/c2ra23332k

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FeCl3 catalysed multicomponent divergent synthesis of
a library of indeno-fused heterocycles3
Cite this: RSC Advances, 2013, 3,
3291
Sunil Rana,a Mike Brownb and Chhanda Mukhopadhyay*a
A simple, straightforward and versatile multicomponent synthetic protocol for indeno-fused heterocycles,
namely diindeno[1,2-b:29,19-e]pyridine, indeno[1,2-b]quinoline and indeno[1,2-b]cyclopenta[e]pyridine
derivatives, has been developed. The strategy involves the one pot three component reaction of
enaminone, dialkyl but-2-ynedioate and 1,3-indanedione catalysed by FeCl3 in acetonitrile under reflux.
The presence of rotamers in the products with 2- and 3-substituted anilines as the amine component adds
some interesting features to this expeditious domino reaction. In the course of the reaction, four new
bonds (two C–C and two C–N bonds) and one stereocenter are formed in one operation. Mild reaction
conditions, operational simplicity, wide substrate scope, product diversity and overall good yield make this
reaction highly efficient for the library synthesis of indeno-fused heterocycles.
Received 9th November 2012,
Accepted 18th December 2012
DOI: 10.1039/c2ra23332k
www.rsc.org/advances
indenoquinoline derivatives show a wide variety of biological
activities such as antitumor,13 anti-inflammatory,14 antimalar-
Introduction
ial15 and 5-HT-receptor binding activity.16 Moreover, they also
act as inhibitors for steroid reductase17 and acetylcholinester-
ase inhibitors for the treatment of Alzheimer’s disease.18
Apart from the Hantzsch-type synthesis,19 there are only a
few other methods available in the literature for the synthesis
of indenopyridines.20 Indenoquinoline compounds can be
synthesized from Baylis–Hillman adducts,21 by the imino
Diels–Alder reaction,22 the aza-Bergman cyclization,23 and few
other methods.24 The paucity of efficient and general synthetic
strategies for these heterocycles presents a challenge to
modern organic chemists. In our approach, we have synthe-
sized these two important heterocyclic cores by the coupling of
enaminone, dialkyl acetylenedicarboxylate and 1,3-indane-
dione catalysed by FeCl3. Over the past few years iron salts
have been efficiently used as a catalyst for C–H functionalisa-
tion,25 and C–C,26 C–N,27 C–O,28 and C–S29 bond formation in
many organic syntheses. Several intra- and intermolecular
cyclisation reactions are also facilitated by iron salts.26a,30
These remarkable features of iron salts and our previous work
on FeCl3-catalysed double aminomethylation at the a-position
of 1,3-dicarbonyl compounds31 encouraged us to investigate
these versatile transition metal salts as catalysts for the
synthesis of various heterocyclic compounds.
The search for new multicomponent reactions (MCRs) invol-
ving domino processes leading to the formation of structurally
important frameworks and drug molecules by pot, atom and
step economic (PASE) methods is an active area of research in
modern organic synthesis.1 The remarkable features of MCRs
that make them special are their ability to generate structurally
diverse and complex compounds from simple starting
materials without the isolation of intermediates, avoiding
the tedious protection and deprotection of functional groups,
thus minimizing both waste production and expenditure of
human labor.2 Consequently, these reactions are environmen-
tally friendly, and often proceed with excellent stereoselectiv-
ities.3 Therefore, the development of new MCRs is
continuous challenge to modern synthetic chemists.
a
The indenopyridine nucleus is the building block of the
4-azafluorenone group of alkaloids, represented by its smallest
member, onychine.4 Indenopyridine derivatives, having strong
antispermatogenic activity are regularly designed for the
development of male contraceptives.5 Due to their antiproli-
ferative activity, they are also potent anticancer agents.6 These
compounds are also used for the treatment of arteriosclerosis
and hyperlipoproteinemia.7 Besides these, many indenopyr-
idine-containing compounds exhibit antihistamine,8 adeno-
sine A2a receptor antagonistic,9 calcium modulating,10 anti-
inflammatory11 and herbicidal activity.12 On the other hand,
Results and discussion
aDepartment of Chemistry, University of Calcutta, 92 APC Road, Kolkata-700009,
India. E-mail: cmukhop@yahoo.co.in; Tel: 91-33-23371104
As a part of our continuing research into attaining high pot,
atom and step economic reactions, we initially investigated the
multicomponent reaction of diethyl acetylenedicarboxylate (1
eq.), aniline (1 eq.) and 1,3-indanedione (2 eq.) catalysed by
bBruker BioSpin, 2700 Technology Forest Drive, Woodlands, Texas 77381, USA
Electronic supplementary information (ESI) available: all 1H and 13C NMR
3
spectra. CCDC reference numbers 905874–905877. For ESI and crystallographic
data in CIF or other electronic format see DOI: 10.1039/c2ra23332k
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Scheme 3 Three component reaction between enaminone (7a), 1,3-indane-
dione (1) and diethyl acetylenedicarboxylate (3a).
Scheme 1 Pseudo four component reaction of 1,3-indanedione (2 mmol),
diethyl acetylenedicarboxylate (1 mmol) and aniline (1 mmol).
was sufficient to obtain the maximum yield of the product in
six hours, and further increasing the amount of catalyst and
time did not improve the yields. A solvent screening experi-
ment was also done and the result revealed that protonated
solvents like ethanol and methanol decreased the yield of the
product due to the formation of 6 in significant amounts.
Among different non protic solvents like THF, ACN, toluene,
DCM, DMF, DMSO and DCE, acetonitrile under reflux gave the
maximum yield of 4a. A stoichiometric ratio of enaminone :
diethyl acetylenedicarboxylate : 1,3-indanedione (1 : 1.1 : 1.1)
in the presence of 10 mol% FeCl3 in refluxing acetonitrile was
found to be the optimum conditions for the maximum yield of
the desired product.
The initial observations showed us several options to
synthesize a variety of indeno-fused compounds by simply
varying the type of enaminone, formed from various cyclic-1,3-
diketones and amines (Scheme 4, Table 2). Enaminones
formed from six membered cyclic-1,3-diketones like 1,3-
cyclohexanedione, 5-phenyl-1,3-cyclohexanedione and 3,3-
dimethylcyclohexanedione gave access to indeno[1,2-b]quino-
line derivatives, and the enaminone formed from 1,3-
FeCl3 in acetonitrile under reflux. We obtained 4a (41% yield)
as the major product, along with 5 and 6 as side products in
significant quantities (isolated yields of 12% and 25%,
respectively) (Scheme 1). Compound 6 is known and the
characterization data are comparable with the literature
values.32 Compound 5 is unknown its structure was unequi-
vocally confirmed by single crystal X-ray diffraction experi-
ments (see Supplementary Information ) along with 1H and
3
13C NMR data.
The methodology required specific modification to avoid
unwanted side products (5 and 6) and to increase the yield of
the target molecule 4a. After searching the literature we found
that Shu-Jiang Tu and his group synthesised a similar type of
indeno-fused heterocycle by the three component reaction of
enaminone, 1,3-indanedione and aldehyde (Scheme 2).24a
Inspired by their work, we modified our methodology and
used enaminone 7a (formed from aniline and 1,3-indane-
dione)33 (1 eqv.), diethyl acetylenedicarboxylate (1 eqv.) and
1,3-indanedione (1 eqv.), maintaining the other reaction
conditions the same as before (Scheme 3).
To our delight, after this modification, we obtained 4a in
75% isolated yield; the side products 5 and 6 disappeared.
This reaction differs from that of the previous group in terms
of the use of dialkyl acetylenedicarboxylate in place of an
aldehyde, which expands the scope of the synthesis of indeno-
fused heterocycles. Another interesting feature is that here the
cyclisation reaction occurs through the same carbon of the
triple bond, which is a promising phenomenon for the further
development of new cyclisation reactions. We then took the
combination of reactants in Scheme 3 as model reaction to
optimize the reaction conditions and attempted the reaction
with various Lewis acids, but FeCl3 (anhydrous) was found to
be the best catalyst and was superior to ZnCl2, AlCl3, FeBr3
(anhydrous forms) and other Lewis acids, as indicated by the
results shown in Table 1. Only 10 mol% of FeCl3 (anhydrous)
Table 1 Choice of catalyst for the synthesis of ethyl-5,11-dihydro-10,12-dioxo-
11-(ethoxycarbonyl)methyl-5-phenyl diindeno[1,2-b:,29,19-e]pyridine-11-car-
boxylate (4a)a
Entry
Catalyst (mol%)
Reaction time (h)
Isolated yield (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
AcOH (10)
H3PW12O40 (10)
SnO2 (10)
24
24
24
24
24
24
24
24
24
6
24
24
24
24
24
24
24
25
29
21
10
13
22
60
59
75
75
74
55
60
41
62
46
trace
4N HCl (1 ml)
4N H2SO4 (1 ml)
4N H3PO4 (1 ml)
TSOH (10)
anhyd. FeCl3 (5)
anhyd. FeCl3 (10)
anhyd. FeCl3 (10)
anhyd. FeCl3 (20)
Fe(NO3)2 (10)
anhyd. FeBr3 (10)
anhyd. AlCl3 (10)
InCl3 (10)
anhyd. ZnCl2 (10)
none
a
The reaction was performed using enaminone 1 (1mmol), diethyl
acetylenedicarboxylate (1.1 mmol) and 1,3-indanedione (1.1 mmol)
in 5 mL acetonitrile under reflux (80–82 uC).
Scheme 2 Synthesis of a similar type of indeno-quinoline derivatives.
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(25–27 uC). In case of diindeno[1,2-b:,29,19-e]pyridines, a
rotameric mixture was obtained only with 2-methyl aniline.
Diastereoisomeric mixtures were obtained when 5-phenyl-
1,3-cyclohexanedione was used as the enaminone part (entries
4m and 4n, Table 2) and the diastereomeric ratios were
1
determined from the crude H NMR spectra of the products.
After a number of interesting observations, we tried to
increase the scope of the reaction by introducing the
enaminone formed from 1,3-cyclopentanedione in this three
component reaction under the same standardized reaction
conditions. The expected product 9 was not obtained. Instead,
we obtained 10 (Scheme 5) which was formed by the hydrolysis
of the CO2R3 of the alkoxycarbonylmethyl moiety of 9, followed
by decarboxylation (shown in the mechanism).
Scheme 4 Versatile synthesis of diindeno[1,2-b:,29,19-e]pyridines and
indeno[1,2-b]quinolines.
indanedione produced diindeno[1,2-b:29,19-e]pyridine deriva-
tives.
We attempted the reaction with six different enaminones
(formed from six different amines) of 1,3-cyclopentanedione,
but in all the cases the product 10 was obtained and we did not
find traces of product 9. Similarly, when 2- and 3-methyl
anilines were used in the enaminone part, rotameric mixtures
were obtained (entries 10f and 10d, Table 3) as before.
Incorporating a number of aromatic and aliphatic amines
in the enaminone part increased the versatility of the reaction.
Aniline and substituted anilines with both electron with-
drawing (Cl, Br, etc.) and donating groups (Me and OMe) at
different positions of the phenyl ring gave good results for the
yields of the products. The use of benzyl amine, n-butyl amine
and 1-aminomethyl naphthalene further increased the scope
of the reaction. Dimethyl acetylenedicarboxylate and diethyl
acetylenedicarboxylate were used as the dialkylbut-2-ynedioate
part. In all the cases the yields of the reactions were moderate
to good. With nitro-anilines the yields of the reaction were very
low and we could not purify the products.
All the prepared compounds depicted in Table 2 were fully
characterized by IR, 1H NMR, 13C NMR and CHN analyses.
Finally, the structures of two representative compounds, one
each from the diindeno[1,2-b:,29,19-e]pyridines and the
indeno[1,2-b]quinolines, were unambiguously confirmed by
single crystal X-ray diffraction experiments (entries 4c and 4t,
Table 2), and their ORTEP diagrams are shown in Fig. 1 and
Fig. 2 respectively.
Interestingly, in the case of the indeno[1,2-b]quinoline
compounds, when 2- and 3-substituted anilines were used in
the enaminone part, the 1H NMR of the products showed a
mixture of rotamers (rotational isomers), or more specifically
atropisomers arising due to restricted rotation around a C–N
bond (Fig. 1), and this phenomenon may have been over-
looked by the previous group in the formation of similar types
of heterocycles.24a Atropisomerism is common for biphenyl
type systems.34 The marked hydrogen (shown in a ring in
Fig. 3) of the indane part generally appears as a doublet (J #
7.5 Hz) at d 5.00–5.50 ppm for the products formed with
aniline or 4-substituted anilines. In the case of 2- and
3-substituted anilines, we obtain two closely spaced doublets
for the marked hydrogen in the 1H NMR spectrum (Fig. 4).
Again, the methyl group of the aromatic amine appears as two
singlets in both the 1H and 13C NMR spectra. This clearly
indicates the presence of rotamers for products obtained from
2- and 3-substituted anilines. We were not able to separate the
rotamers, which may be due to the fact that the interconver-
sion between the rotamers occurs even at room temperature
1
All six compounds prepared were fully characterized by H
NMR, 13C NMR, IR and CHN analyses, and the structure of 10
was unequivocally confirmed by the single crystal X-ray
diffraction experiment for one of the entries (10a) of Table 3,
and the ORTEP plot is shown in Fig. 5.
A mechanistic rationale exhibiting a probable sequence of
events for the indeno-fused heterocycles is given in Scheme 6.
First, 1,3-indanedione in its enol form reacts with dialkyl
acetylenedicarboxylate to form an intermediate (A). A then
undergoes Michael addition with the enaminone followed by a
condensation reaction, leading to cyclisation by the elimina-
tion of water to give the final product 4. FeCl3 may activate the
triple bond by coordinating with it in the formation of the
intermediate A. It also facilitates the Michael addition step,
which is supported by the available literature.26a,35 The
formation of 10 may be visualized by the elimination of
–OR3 from the previously formed 4 to form the lactone B,
which is then attacked by water to form C. Finally, a
decarboxylation step occurs by the elimination of CO2 to form
the product 10. We were not able to isolate the intermediates
A, B or C, but these sequences of steps give a clear view of the
mechanism of the reaction. In the formation of 10, the
generation of the intermediate B is crucial, and in case of the
enaminone formed from 1,3-cyclopentanedione, B may be
more stable than that formed from a six membered 1,3-
diketone, which may be the reason for the formation of 10 only
in the case of the enaminone formed from 1,3-cyclopentane-
dione. Similarly, the formation of the side product 5 in
Scheme 1 may be visualized by the hydrolysis mechanism.
This new multicomponent reaction also suffers from
limitations regarding the use of 1,3-indanedione, which is a
specific component for this reaction. When other cyclic 1,3-
diketones were used to substitute for indane-1,3-dione, the
desired product was not obtained. Instead, a complex product
mixture was obtained, from which no characteristic product
could be separated. Nevertheless, this reaction is very
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Table 2 Library synthesis of diindeno[1,2-b:,29,19-e]pyridines and indeno[1,2-b]quinolinesa
a
Compound numberings and percentage yields are shown in the table along with the structures.
promising as the coupling occurs through only one of the
carbons of the triple bond, which is a significant phenomenon
Conclusion
In summary, we have developed a simple and divergent
multicomponent domino synthesis of diindeno[1,2-
for the further development of new heterocycle libraries.
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Fig. 3 Interconversion between rotamers.
Experimental section
General information
1H and 13C spectra were obtained on a Bruker 300 MHz
instrument at 300 MHz and 75 MHz respectively. DEPTQ-135
experiments were performed on a Bruker 300 MHz instrument
at 75 MHz. Chemical shifts are reported in parts per million
(ppm) downfield from an internal TMS (trimethylsilane)
reference. Coupling constants (J) are reported in hertz (Hz),
and spin multiplicities are represented by the symbols s
(singlet), brs (broad singlet), d (doublet), t (triplet), q (quartet),
dt (doublet of triplet) and m (multiplet). IR spectra were
recorded on a Perkin Elmer Spectrophotometer RX/FT-IR
system. Band positions are reported in reciprocal centimeters
(cm21). The CHN analyses were carried out on a 2400 Series II
CHNS Analyzer, Perkin Elmer USA. X-ray diffraction was done
on a Bruker SMART diffractometer equipped with a graphite
monochromator and Mo Ka (l = 0.71073 Å) radiation. Melting
points were determined on an electrical melting point
apparatus with an open capillary. The progress of the reaction
was checked by TLC using 300–400 mesh silica gel. Column
chromatography was performed using 60–120 mesh silica gel.
All the available reagents were purchased from commercial
Fig. 1 ORTEP plot of a single crystal of the diindeno[1,2-b:,29,19-e]pyridine 4c
(Table 2) (CCDC 9058763) showing the crystallographic numbering.
b:29,19-e]pyridine, indeno[1,2-b]quinoline and indeno[1,2-
b]cyclopenta[e]pyridine derivatives by the reaction of enam-
inone, dialkyl acetylenedicarboxylate and 1,3-indanedione
catalyzed by FeCl3 in acetonitrile under reflux in good yields.
It is worth mentioning that in the course of these reactions,
four new bonds (two C–C and two C–N) and one stereocenter
are formed in one operation. Furthermore, the scope and
limitations of this reaction were established, which enables
further modifications leading to molecular diversity.
Importantly, this method is suitable for library generation,
which makes the methodology more attractive for organic
synthesis.
Fig. 2 ORTEP plot of a single crystal of the indeno[1,2-b]quinoline 4t (Table 2)
(CCDC 9058753) showing the crystallographic numbering.
Fig. 4 Presence of rotamers in the 1H NMR spectrum of 4j.
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Ethyl-5,11-dihydro-10,12-dioxo-11-(ethoxycarbonyl)methyl-5-
phenyl diindeno[1,2-b:29,19-e]pyridine-11-carboxylate (4a)
(Table 2, entry 1): Yield 75% (389 mg); red solid; m.p.: 202–204
uC (EtOAc); vmax (KBr) (cm21) 2984, 1728, 1687, 1623, 1455,
1383, 1194, 1021, 848, 761, 714; 1H NMR (300 MHz, CDCl3) dH:
7.80–7.62 (5H, m, ArH), 7.41 (2H, d, J = 6.9 Hz, ArH), 7.16 (2H,
t, J = 7.5 Hz, ArH), 6.93 (2H, t, J = 7.5 Hz, ArH), 5.48 (2H, d, J =
7.5 Hz, ArH), 4.28 (2H, q, J = 7.2 Hz, OCH2), 3.98 (2H, q, J = 7.2
Hz, OCH2), 3.46 (2H, s, CH2), 1.29 (3H, t, J = 7.2 Hz, CH3), 1.00
(3H, t, J = 7.2 Hz, CH3); 13C NMR (75 MHz, CDCl3) dC: 190.9,
171.6, 171.2, 156.4, 138.7, 136.6, 133.3, 131.8, 131.2, 130.1,
129.7, 121.9, 121.3, 112.0, 62.1, 59.9, 42.8, 38.2, 14.1, 14.0;
Anal. calcd. for C32H25NO6; C: 73.98; H: 4.85; N: 2.70. Found:
C: 74.23; H: 4.76; N: 2.71%.
Scheme 5 Three component reaction of enaminone (formed from 1,3-
pentanedione and aromatic amine), dialkyl acetylenedicarboxylate and 1,3-
indanedione.
Ethyl-5,11-dihydro-10,12-dioxo-11-(ethoxycarbonyl)methyl-5-
(4-methylphenyl) diindeno[1,2-b:29,19-e]pyridine-11-
carboxylate (4b)
sources and were used without purification. Enaminones were
prepared according to the standard literature procedures. All
the solvents used during the reactions were distilled for purity.
(Table 2, entry 2): Yield 74% (394 mg); red solid; m.p.: 164–166
uC (EtOAc); vmax (KBr) (cm21) 2980, 1738, 1727, 1692, 1582,
1385, 1354, 1207, 1011, 852; 1H NMR (300 MHz, CDCl3) dH:
7.65 (2H, d, J = 7.5 Hz, ArH), 7.55–7.47 (4H, m, ArH), 7.25 (2H,
t, J = 7.5 Hz, ArH), 7.03 (2H, t, J = 7.5 Hz, ArH), 5.62 (2H, d, J =
7.5 Hz, ArH), 4.36 (2H, q, J = 7.2 Hz, OCH2), 4.05 (2H, q, J = 7.2
Hz, OCH2), 3.54 (2H, s, CH2), 2.68 (3H, s, CH3), 1.38 (3H, t, J =
7.2 Hz, CH3), 1.08 (3H, t, J = 7.2 Hz, CH3); 13C NMR (75 MHz,
CDCl3) dC: 190.9, 171.7, 171.2, 156.5, 141.5, 136.6, 136.0, 133.4,
131.7, 130.6, 129.6, 121.8, 121.4, 111.9, 62.1, 59.9, 42.8, 38.2,
21.6, 14.1, 14.0; Anal. calcd. for C33H27NO6; C: 74.28; H: 5.10;
N: 2.63. Found: C: 74.52; H: 5.03; N: 2.70%.
General procedure for the synthesis of indeno-pyridine,
indeno-quinoline and indeno-cyclopenta-pyridine derivatives
Enaminone (1 mmol), dialkyl acetylenedicarboxylate (1.1
mmol), 1,3-indanedione (1.1 mmol), anhyd. FeCl3 (0.1 mmol)
and acetonitrile (5 ml) were added to a 25 ml round bottomed
flask fitted with a refluxing condenser with a calcium chloride
guard tube, and the resulting mixture was refluxed for 6 h in
an oil bath. After the completion of the reaction as indicated
by TLC, acetonitrile was removed by rotary evaporation under
vacuum. To the crude mixture 20 ml water was added and
product was extracted with 20 ml dichloromethane to remove
FeCl3. Dichloromethane was removed by rotary evaporation
under reduced pressure. The crude product was then purified
by column chromatography using silica gel (60–120 mesh)
with 15% ethyl acetate in petroleum ether (60u–80 uC) as the
eluent.
Table 3 Synthesis of indeno[1,2-b]cyclopenta[e]pyridine derivativesa
a
Fig. 5 ORTEP plot of a single crystal of the indeno[1,2-b]cyclopenta[e]pyridine
10a (Table 3) (CCDC 9058743) showing the crystallographic numbering.
Compound numberings and percentage yields are shown in the
table along with the structures.
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Scheme 6 Plausible mechanism for the formation of indeno-fused heterocycles.
7.10 (2H, t, J = 7.5 Hz, ArH), 6.87 (2H, t, J = 7.5 Hz, ArH), 5.45
(2H, d, J = 7.5 Hz, ArH), 4.21 (2H, q, J = 7.2 Hz, OCH2), 3.91 (2H,
q, J = 7.2 Hz, OCH2), 3.40 (2H, s, CH2), 2.43 (3H, s, CH3), 1.22
(3H, t, J = 7.2 Hz, CH3), 0.95 (3H, t, J = 7.2 Hz, CH3); 13C NMR
(75 MHz, CDCl3) dC: 190.9, 171.6, 171.2, 156.4, 141.5, 138.5,
136.6, 133.4, 131.8, 131.7, 129.6, 127.0, 121.8, 121.4, 111.9,
62.1, 59.9, 42.8, 38.1, 21.3, 14.1, 14.0; Anal. calcd. for
Ethyl-5,11-dihydro-10,12-dioxo-11-(ethoxycarbonyl)methyl-5-
(3-methylphenyl) diindeno[1,2-b:29,19-e]pyridine-11-
carboxylate (4c)
(Table 2, entry 3): Yield 72% (384 mg); red solid; m.p.: 196–198
uC (EtOAc); vmax (KBr) (cm21) 2985, 1738, 1689, 1581, 1452,
1
1385, 1219, 1030, 925, 849, 764, 717, 520; H NMR (300 MHz,
CDCl3) dH: 7.52–7.43 (4H, m, ArH), 7.34 (2H, d, J = 7.2 Hz, ArH),
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C33H27NO6; C: 74.28; H: 5.10; N: 2.63. Found: C: 74.48; H: 5.02;
N: 2.56%.
CDCl3) dH: 8.08 (2H, d, J = 7.8 Hz, ArH), 7.98–7.82 (4H, m, ArH),
7.59 (2H, t, J = 7.5 Hz, ArH), 7.35 (2H, t, J = 7.5 Hz, ArH), 5.88
(2H, d, J = 7.5 Hz, ArH), 4.66 (2H, q, J = 7.2 Hz, OCH2), 4.40 (2H,
q, J = 7.2 Hz, OCH2), 3.94 (2H, s, CH2), 2.74 (3H, s, CH3), 1.67
(3H, t, J = 7.2 Hz, CH3), 1.44 (3H, t, J = 7.2 Hz, CH3); 13C NMR
(75 MHz, CDCl3) dC: 190.9, 171.2, 156.1, 138.6, 137.6, 136.4,
133.4, 132.0, 131.4, 131.3, 130.1, 129.8, 127.7, 121.9, 120.6,
112.2, 62.0, 59.9, 43.0, 37.7, 17.4, 14.1, 14.0; Anal. calcd. for
Ethyl-11-hydro-10,12-dioxo-11-(ethoxycarbonyl)methyl-5-(3-
methoxyphenyl)-5H-diindeno[1,2-b:29,19-e]pyridine-11-
carboxylate (4d)
(Table 2, entry 4): Yield 67% (368 mg); red solid; m.p.: 178–180
uC (EtOAc); vmax (KBr) (cm21) 2978, 1732, 1698, 1627, 1601,
1583, 1488, 1384, 1353, 1231, 1035, 849, 766; 1H NMR (300
MHz, CDCl3) dH: 7.51 (1H, t, J = 8.1 Hz, ArH), 7.39 (2H, d, J =
7.2 Hz, ArH), 7.30–7.12 (5H, m, ArH), 6.94 (2H, t, J = 7.5 Hz,
ArH), 5.59 (2H, d, J = 6.0 Hz, ArH), 4.26 (2H, q, J = 7.2 Hz,
OCH2), 3.94 (2H, q, J = 7.2 Hz, OCH2), 3.85 (3H, s, OMe), 3.38
(2H, s, CH2), 1.27 (3H, t, J = 7.2 Hz, CH3), 0.98 (3H, t, J = 7.2 Hz,
CH3); 13C NMR (75 MHz, CDCl3) dC: 190.9, 171.2, 156.3, 139.5,
136.5, 133.3, 131.8, 129.7, 122.2, 121.8, 121.4, 115.2, 111.9,
62.1, 59.9, 55.8, 42.9, 38.2, 14.1, 14.0; Anal. calcd. for
C33H27NO7; C: 72.12; H: 4.95; N: 2.55. Found: C: 72.25; H:
4.86; N: 2.48%.
C
33H27NO6; C: 74.28; H: 5.10; N: 2.63. Found: C: 74.51; H: 5.00;
N: 2.56%.
Methyl-10-[(methoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-
9,11-dioxo-5-phenyl-5H-indeno[1,2-b]quinoline-10-carboxylate
(4h)
(Table 2, entry 8): Yield 76% (348 mg); red solid; m.p.: 204–206
uC (EtOAc); vmax (KBr) (cm21) 2943, 1723, 1688, 1655, 1634,
1588, 1557, 1513, 1398, 1239, 1176, 1078, 908, 794; 1H NMR
(300 MHz, CDCl3) dH: 7.70–7.50 (5H, m, ArH), 7.37 (1H, d, J =
6.9 Hz, ArH), 7.13 (1H, t, J = 7.5 Hz, ArH), 6.87 (1H, t, J = 7.5 Hz,
ArH), 5.18 (1H, d, J = 7.5 Hz, ArH), 3.80 (3H, s, CO2Me), 3.57
(3H, s, CO2Me), 3.38 (1H, d, J = 15.9 Hz, CHaHb), 3.27 (1H, d, J
= 15.9 Hz, CHbHa), 2.45–1.80 (6H, m, CH2); 13C NMR (75 MHz,
CDCl3) dC: 196.2, 191.1, 173.5, 172.1, 155.5, 154.5, 138.7, 136.6,
133.3, 131.4, 130.2, 129.9, 129.6, 121.5, 121.0, 115.8, 109.6,
52.7, 51.1, 43.8, 38.9, 36.8, 27.8, 21.0; Anal. calcd. for
Ethyl-5-(4-bromophenyl)-11-hydro-10,12-dioxo-11-
(ethoxycarbonyl)methyl-5H-diindeno[1,2-b:29,19-e]pyridine-11-
carboxylate (4e)
(Table 2, entry 5): Yield 62% (371 mg); red solid; m.p.: 182–184
uC (EtOAc); vmax (KBr) (cm21) 2970, 1726, 1693, 1611, 1580,
1490, 1385, 1361, 1222, 1018, 838, 706; 1H NMR (300 MHz,
CDCl3) dH: 7.79 (2H, d, J = 8.4 Hz, ArH), 7.62 (2H, d, J = 8.4 Hz,
ArH), 7.42 (2H, d, J = 7.5 Hz, ArH), 7.19 (2H, t, J = 7.5 Hz, ArH),
7.00 (2H, t, J = 7.5 Hz, ArH), 5.57 (2H, d, J = 7.5 Hz, ArH), 4.27
(2H, q, J = 7.2 Hz, OCH2), 3.96 (2H, q, J = 7.2 Hz, OCH2), 3.45
(2H, s, CH2), 1.29 (3H, t, J = 7.2 Hz, CH3), 1.00 (3H, t, J = 7.2 Hz,
CH3); 13C NMR (75 MHz, CDCl3) dC: 190.8, 171.2, 156.3, 137.8,
136.5, 133.4, 133.2, 131.9, 131.8, 129.9, 125.4, 122.1, 121.2,
62.2, 60.0, 42.7, 38.1, 14.2, 14.0; Anal. calcd. for C32H24BrNO6;
C: 64.22; H: 4.04; N: 2.34. Found: C: 64.49; H: 4.00; N: 2.26%.
C
27H23NO6; C: 70.89; H: 5.07; N: 3.06. Found: C: 71.01 H:
4.99; N: 3.00%.
Methyl-10-[(methoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-
9,11-dioxo-5-p-tolyl-5H-indeno[1,2-b]quinoline-10-carboxylate
(4i)
(Table 2, entry 9): Yield 77% (363 mg); red solid; m.p.: 216–218
uC (EtOAc); nmax (KBr) (cm21) 2943, 1723, 1688, 1655, 1634,
1588, 1557, 1398, 1239, 1176, 1078, 908, 794; 1H NMR (300
MHz, CDCl3) dH: 7.50–7.30 (5H, m, ArH), 7.10 (1H, t, J = 7.5 Hz,
ArH), 6.86 (1H, t, J = 7.5 Hz, ArH), 5.25 (1H, d, J = 7.5 Hz, ArH),
3.76 (3H, s, CO2Me), 3.53 (3H, s, CO2Me), 3.34 (1H, d, J = 15.6
Hz, CHaHb), 3.23 (1H, d, J = 15.9 Hz, CHbHa), 2.50 (3H, s, Me),
2.45–2.15 (4H, m, CH2), 2.10–1.80 (2H, m, CH2); 13C NMR (75
MHz, CDCl3) dC: 196.2, 191.1, 173.5, 172.1, 155.7, 154.8, 140.5,
136.6, 135.9, 133.3, 131.5, 130.8, 130.2, 129.6, 129.5, 129.3,
121.4, 121.2, 115.8, 109.5, 52.6, 51.1, 43.8, 39.0, 36.8, 27.8,
21.4, 21.0; Anal. calcd. for C28H25NO6; C: 71.33; H: 5.34; N:
2.97. Found: C: 71.53 H: 5.27; N: 2.93%.
Ethyl-11-hydro-10,12-dioxo-11-(ethoxycarbonyl)methyl-5-(4-
methoxyphenyl)-5H- diindeno[1,2-b:29,19-e]pyridine-11-
carboxylate (4f)
(Table 2, entry 6): Yield 73% (401 mg); red solid; m.p.: 160–162
uC (EtOAc); vmax (KBr) (cm21) 2970, 1738, 1692, 1645, 1607,
1577, 1480, 1375, 1333, 1253, 1027, 840; 1H NMR (300 MHz,
CDCl3) dH: 7.59 (2H, d, J = 7.8 Hz, ArH), 7.42 (2H, d, J = 6.9 Hz,
ArH), 7.18 (2H, t, J = 7.5 Hz, ArH), 7.11 (2H, d, J = 7.8 Hz, ArH),
6.97 (2H, dt, J = 7.2 Hz and 1.2 Hz, ArH), 5.60 (2H, d, J = 7.5 Hz,
ArH), 4.28 (2H, q, J = 7.2 Hz, OCH2), 4.00–3.92 (5H, m, OCH2
and OMe), 3.45 (2H, s, CH2), 1.29 (3H, t, J = 7.2 Hz, CH3), 1.00
(3H, t, J = 7.2 Hz, CH3); 13C NMR (75 MHz, CDCl3) dC: 191.0,
171.2, 161.3, 157.0, 136.7, 133.4, 131.8, 131.2, 131.0, 129.7,
123.1, 121.9, 121.5, 115.1, 112.0, 62.1, 60.0, 55.8, 42.8, 38.2,
14.2, 14.0; Anal. calcd. for C33H27NO7; C: 72.12; H: 4.95; N:
2.55. Found: C: 72.37; H: 4.88; N: 2.49%.
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-
9,11-dioxo-5-o-tolyl-5H-indeno[1,2-b]quinoline-10-carboxylate
(4j)
(Table 2, entry 10): Yield 63% (315 mg); red viscous liquid; vmax
(KBr) (cm21) 2930, 1747, 1728, 1689, 1652, 1456, 1397, 1353,
1232, 1081, 719; 1H NMR (300 MHz, CDCl3) dH: 7.50–7.43 (1H,
m, ArH), 7.40–7.29 (4H, m, ArH), 7.06 (1H, t, J = 7.5 Hz, ArH),
6.85–6.75 (1H, m, ArH), 5.09 (0.68H, d, J = 7.5 Hz, ArH), 5.00
(0.32H, d, J = 7.5 Hz, ArH), 4.25–4.13 (2H, m, OCH2), 3.45–3.25
(2H, m, CH2), 3.95–3.85 (2H, m, OCH2), 2.45–2.15 (6H, m, Me
and CH2), 2.00–1.80 (3H, m, CH2), 1.30–1.20 (3H, m, CH3), 1.01
(3H, t, J = 6.9 Hz, CH3); 13C NMR (75 MHz, CDCl3) dC: 196.0,
191.0, 173.1, 172.8, 171.8, 171.6, 155.0, 153.9, 153.8, 138.2,
137.9, 137.6, 137.4, 136.2, 133.3, 131.6, 131.4, 130.5, 130.0,
Ethyl-11-hydro-10,12-dioxo-11-(ethoxycarbonyl)methyl-5-(2-
methylphenyl)-5H- diindeno[1,2-b:29,19-e]pyridine-11-
carboxylate (4g)
(Table 2, entry 7): Yield 69% (368 mg); red solid; m.p.: 176–178
uC (EtOAc); vmax (KBr) (cm21) 2986, 1731, 1690, 1627, 1583,
1455, 1387, 1192, 1022, 907, 850, 756, 714; 1H NMR (300 MHz,
3298 | RSC Adv., 2013, 3, 3291–3303
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129.8, 129.7, 129.6, 129.4, 127.6, 127.5, 121.38, 121.31, 120.2,
120.1, 116.4, 116.3, 109.6, 61.5, 61.4, 59.7, 59.6, 44.7, 44.3,
38.4, 36.94, 36.86, 26.8, 21.2, 21.1, 21.0, 17.5, 17.3, 14.1, 14.0;
Anal. calcd. for C30H29NO6; C: 72.13; H: 5.85; N: 2.80. Found:
C: 72.31 H: 5.77; N: 2.75%.
Methyl-10-[(methoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-
5-(4-methoxyphenyl)-9,11-dioxo-7-phenyl-5H-indeno[1,2-
b]quinoline-10-carboxylate (4n) (crude product)
1
(Table 2, entry 14): dr = 57 : 43; red sticky mass; H NMR (300
MHz, CDCl3) dH: 7.40–6.90 (12H, m, ArH), 5.29 (0.43H, d, J =
7.2 Hz, ArH), 5.21 (0.57H, d, J = 7.2 Hz, ArH), 3.90–3.70 (6H, m,
2 6 CO2Me), 3.52 (1.59H, s, OMe), 3.45 (1.41H, s, OMe), 3.40–
3.10 (2H, m, CH2), 2.65–2.30 (2H, m, CH2); 13C NMR (75 MHz,
CDCl3) dC: 195.5, 195.3, 191.0, 173.3, 172.0, 160.6, 156.0, 154.4,
154.1, 142.3, 136.6, 136.5, 133.2, 131.5, 130.8, 130.7, 130.6,
130.3, 129.6, 129.5, 128.9, 128.7, 128.6, 127.1, 127.0, 126.7,
126.6, 126.5, 121.4, 121.2, 116.0, 115.5, 115.3, 114.8, 114.7,
55.6, 52.7, 52.6, 51.1, 43.8, 43.7, 43.6, 39.3, 39.1, 39.0, 38.0,
35.2, 34.6.
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-5-
(4-methoxyphenyl)-9,11-dioxo-5H-indeno[1,2-b]quinoline-10-
carboxylate (4k)
(Table 2, entry 11): Yield 76% (392 mg); red solid; m.p.: 150–
152 uC (EtOAc); vmax (KBr) (cm21) 2973, 1739, 1681, 1654, 1634,
1
1557, 1508, 1400, 1356, 1302, 1228, 1211, 1084, 858; H NMR
(300 MHz, CDCl3) dH: 7.20–7.04 (3H, m, ArH), 6.90–6.75 (3H,
m, ArH), 6.70–6.60 (1H, m, ArH), 5.07 (1H, d, J = 7.2 Hz, ArH),
4.10–3.90 (2H, m, OCH2), 3.80–3.64 (5H, m, OCH2 and OCH3),
3.08 (1H, d, J = 15.0 Hz, CHaHb), 2.93 (1H, d, J = 15.0 Hz,
CHbHa), 2.25–1.85 (4H, m, CH2), 1.80–1.50 (2H, m, CH2), 1.02
(3H, t, J = 7.2 Hz, CH3), 0.82 (3H, t, J = 7.2 Hz, CH3); 13C NMR
(75 MHz, CDCl3) dC: 195.9, 190.8, 172.7, 171.5, 160.4, 155.6,
154.7, 136.5, 133.1, 131.3, 130.9, 130.5, 130.4, 129.3, 121.1,
115.7, 115.0, 114.5, 109.4, 61.1, 59.6, 55.5, 43.8, 38.9, 36.6,
27.5, 20.7, 13.93, 13.87; Anal. calcd. for C30H29NO7; C: 69.89;
H: 5.67; N: 2.72;. Found: C: 70.01; H: 5.59; N: 2.66%.
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-7,7-
dimethyl-9,11-dioxo-5-phenyl-5H-indeno[1,2-b]quinoline-10-
carboxylate (4o)
(Table 2, entry 15): Yield 78% (401 mg); red solid; m.p.: 128–
130 uC (EtOAc); vmax (KBr) (cm21) 2964, 1737, 1687, 1642, 1586,
1457, 1400, 1359, 1216, 1083, 1025, 893, 715; 1H NMR (300
MHz, CDCl3) dH: 7.65–7.40 (5H, m, ArH), 7.33 (1H, d, J = 6.9
Hz, ArH), 7.08 (1H, t, J = 7.2 Hz, ArH), 6.82 (1H, t, J = 7.2 Hz,
ArH), 5.12 (1H, d, J = 7.2 Hz, ArH), 4.30–4.15 (2H, m, OCH2),
3.98–3.90 (2H, m, OCH2), 3.42 (1H, d, J = 15.9 Hz, CHaHb), 3.23
(1H, d, J = 15.9 Hz, CHbHa), 2.30–2.13 (3H, m, CH2), 1.96 (1H,
d, J = 17.4 Hz, CH2), 1.28 (3H, t, J = 7.2 Hz, CH3), 1.10–0.90 (9H,
m, 3 6 CH3); 13C NMR (75 MHz, CDCl3) dC: 196.1, 191.0, 172.9,
171.8, 155.6, 152.6, 138.8, 136.6, 133.3, 131.3, 130.3, 130.2,
130.0, 129.9, 129.6, 129.5, 121.3, 120.9, 115.1, 61.5, 59.8, 50.4,
44.0, 41.2, 38.7, 32.2, 28.8, 27.2, 14.1; Anal. calcd. for
C31H31NO6; C: 72.50; H: 6.08; N: 2.73. Found: C: 72.71 H:
6.11; N: 2.86%.
Ethyl-10-[(ethoxycarbonyl)methyl]-5-benzyl-6,7,8,9,10,11-
hexahydro-9,11-dioxo-5H-indeno[1,2-b]quinoline-10-
carboxylate (4l)
(Table 2, entry 12): Yield 64% (320 mg); red solid; m.p.: 186–
188 uC (EtOAc); vmax (KBr) (cm21) 2978, 1731, 1717, 1684, 1647,
1587, 1450, 1412, 1360, 1324, 1033, 924, 721; 1H NMR (300
MHz, CDCl3) dH: 7.45–7.25 (6H, m, ArH), 7.12 (1H, t, J = 7.5 Hz,
ArH), 6.99 (1H, t, J = 7.5 Hz, ArH), 6.79 (1H, d, J = 7.2 Hz, ArH),
5.15 (2H, s, benzylic CH2), 4.21–4.11 (2H, m, OCH2), 3.95–3.84
(2H, m, OCH2), 3.32 (1H, d, J = 15.0 Hz, CHaHb), 3.14 (1H, d, J =
15.0 Hz, CHbHa), 2.55–2.25 (4H, m, CH2), 1.95–1.80 (2H, m,
CH2), 1.24 (3H, t, J = 7.2 Hz, CH3), 0.96 (3H, t, J = 7.2 Hz, CH3);
13C NMR (75 MHz, CDCl3) dC: 195.7, 190.7, 173.1, 171.8, 157.0,
155.1, 136.4, 136.1, 133.6, 131.8, 129.9, 129.5, 128.1, 125.3,
121.9, 121.2, 117.2, 110.8, 61.5, 59.7, 50.9, 44.3, 38.8, 36.6,
26.2, 21.2, 14.1, 14.0; Anal. calcd. for C30H29NO6; C: 72.13; H:
5.85; N: 2.80. Found: C: 72.37 H: 5.79; N: 2.73%.
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-7,7-
dimethyl-9,11-dioxo-5-p-tolyl-5H-indeno[1,2-b]quinoline-10-
carboxylate (4p)
(Table 2, entry 16): Yield 77% (406 mg); red solid; m.p.: 172–
174 uC (EtOAc); vmax (KBr) (cm21) 2960, 1734, 1725, 1680, 1638,
1
1589, 1558, 1514, 1403, 1362, 1304, 1237, 1173, 1032, 896; H
NMR (300 MHz, CDCl3) dH: 7.40–7.25 (5H, m, ArH), 7.07 (1H, t,
J = 7.5 Hz, ArH), 6.83 (1H, t, J = 7.5 Hz, ArH), 5.20 (1H, d, J = 7.5
Hz, ArH), 4.30–4.13 (2H, m, OCH2), 3.98–3.88 (2H, m, OCH2),
3.41 (1H, d, J = 15.6 Hz, CHaHb), 3.21 (1H, d, J = 15.6 Hz,
CHbHa), 2.49 (3H, s, CH3), 2.30–2.10 (3H, m, CH2), 1.96 (1H, d,
J = 17.4 Hz, CH2), 1.26 (3H, t, J = 7.2 Hz, CH3), 1.05–0.92 (9H,
m, 3 6 CH3); 13C NMR (75 MHz, CDCl3) dC: 196.2, 191.0, 172.9,
171.8, 155.8, 153.0, 140.5, 136.7, 136.1, 133.4, 131.4, 130.9,
130.3, 129.5, 121.3, 121.1, 115.1, 109.5, 61.4, 59.8, 50.4, 44.0,
41.2, 38.7, 32.2, 28.8, 27.3, 21.4, 14.1, 14.0; Anal. calcd. for
C32H33NO6; C: 72.85; H: 6.30; N: 2.65. Found: C: 72.99 H: 6.21;
N: 2.58%.
Methyl-10-[(methoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-
9,11-dioxo-7-phenyl-5-p-tolyl-5H-indeno[1,2-b]quinoline-10-
carboxylate (4m) (crude product)
1
(Table 2, entry 13): dr = 66 : 34; red sticky mass; H NMR (300
MHz, CDCl3) dH: 7.35–7.00 (11H, m, ArH), 6.80 (1H, t, J = 7.5
Hz, ArH), 5.22 (0.33H, d, J = 8.1 Hz, ArH), 5.12 (0.67H, d, J = 8.1
Hz, ArH), 3.90–3.10 (9H, m, CH, CH2 and 2 6 CO2Me), 2.70–
2.20 (7H, m, 2 6 CH2 and CH3); 13C NMR (75 MHz, CDCl3) dC:
195.3, 191.0, 173.4, 172.0, 154.1, 142.4, 140.6, 136.6, 135.7,
133.2, 131.5, 131.4, 130.9, 130.7, 130.4, 130.2, 129.6, 129.4,
129.3, 129.0, 128.9, 128.7, 127.5, 127.0, 126.7, 126.6, 121.4,
121.2, 117.5, 115.5, 52.9, 52.7, 52.6, 51.1, 43.9, 43.8, 43.6, 43.4,
39.2, 39.1, 38.0, 35.2, 34.6, 21.3, 21.1.
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-5-
(4-methoxyphenyl)-7,7-dimethyl-9,11-dioxo-5H-indeno[1,2-
b]quinoline-10-carboxylate (4q)
(Table 2, entry 17): Yield 77% (419 mg); red solid; m.p.: 124–
126 uC (EtOAc); vmax (KBr) (cm21) 2958, 1745, 1734, 1683, 1648,
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1634, 1559, 1555, 1510, 1409, 1361, 1247, 898, 724; 1H NMR
(300 MHz, CDCl3) dH: 7.35–7.25 (3H, m, ArH), 7.10–6.95 (3H,
m, ArH), 6.82 (1H, t, J = 7.5 Hz, ArH), 5.24 (1H, d, J = 7.2 Hz,
ArH), 4.28–4.10 (2H, m, OCH2), 3.94–3.82 (5H, m, OCH2 and
OCH3), 3.36 (1H, d, J = 15.6 Hz, CHaHb), 3.17 (1H, d, J = 15.6
Hz, CHbHa), 2.24–2.07 (3H, m, CH2), 1.93 (1H, d, J = 17.7 Hz,
CH2), 1.23 (3H, t, J = 7.2 Hz, CH3), 1.00–0.85 (9H, m, 3 6 CH3);
13C NMR (75 MHz, CDCl3) dC: 196.2, 191.0, 172.9, 171.8, 160.4,
156.1, 153.3, 136.6, 133.3, 131.4, 131.1, 130.9, 130.8, 129.5,
121.1, 115.1, 115.0, 114.7, 109.4, 61.4, 59.8, 50.3, 43.8, 41.1,
38.6, 32.1, 28.8, 27.2, 14.0; Anal. calcd. for C32H33NO7; C:
70.70; H: 6.12; N: 2.58. Found: C: 70.95 H: 6.07; N: 2.50%.
dH: 7.50–7.40 (2H, m, ArH), 7.32 (1H, d, J = 6.9 Hz, ArH), 7.26–
7.22 (2H, m, ArH), 7.08 (1H, t, J = 7.2 Hz, ArH), 6.83 (1H, t, J =
7.5 Hz, ArH), 5.16–5.12 (1H, m, ArH), 4.28–4.14 (2H, m, OCH2),
4.00–3.91 (2H, m, OCH2), 3.42 (1H, d, J = 15.9 Hz, CHaHb), 3.23
(1H, dd, J = 15.6 Hz and 4.2 Hz, CHbHa), 2.50–2.41 (3H, m, Me),
2.30–2.10 (3H, m, CH2), 1.99 (1H, d, J = 17.4 Hz, CH2), 1.27 (3H,
t, J = 6.9 Hz, CH3), 1.10–0.94 (9H, m, 3 6 CH3); 13C NMR (75
MHz, CDCl3) dC: 196.1, 191.0, 172.9, 171.8, 155.7, 152.7, 140.7,
140.0, 138.6, 136.7, 133.4, 131.4, 131.0, 130.3, 130.0, 129.5,
129.4, 126.9, 121.3, 121.1, 115.0, 109.5, 61.4, 59.8, 50.4, 44.0,
41.2, 38.7, 32.3, 28.9, 28.6, 27.4, 27.2, 21.4, 14.1; Anal. calcd.
for C32H33NO6; C: 72.85; H: 6.30; N: 2.65. Found: C: 73.08 H:
6.22; N: 2.56%.
Ethyl-10-[(ethoxycarbonyl)methyl]-5-(4-bromophenyl)-
6,7,8,9,10,11-hexahydro-7,7-dimethyl-9,11-dioxo-
5H-indeno[1,2-b]quinoline-10-carboxylate (4r)
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-7,7-
dimethyl-5-(3,4-dimethylphenyl)-9,11-dioxo-5H-indeno[1,2-
b]quinoline-10-carboxylate (4u)
(Table 2, entry 18): Yield 71% (421 mg); red solid; m.p.: 198–
200 uC (EtOAc); vmax (KBr) (cm21) 2957, 1726, 1684, 1727, 1648,
(Table 2, entry 21): Yield 70% (379 mg); red viscous liquid; vmax
(KBr) (cm21) 2958, 1725, 1708, 1681, 1634, 1589, 1499, 1360,
1215, 718; 1H NMR (300 MHz, CDCl3) dH: 7.29–7.21 (2H, m,
ArH), 7.18–7.00 (3H, m, ArH), 6.80 (1H, t, J = 7.5 Hz, ArH), 5.20–
5.10 (1H, m, ArH), 4.22–4.10 (2H, m, OCH2), 3.95–3.85 (2H, m,
OCH2), 3.38 (1H, d, J = 15.6 Hz, CHaHb), 3.15 (1H, d, J = 15.6
Hz, CHbHa), 2.38–1.90 (10H, m, 2 6 CH3 and 2 6 CH2), 1.26–
1.15 (3H, m, CH3), 1.00–0.85 (9H, m, 3 6 CH3); 13C NMR (75
MHz, CDCl3) dC: 196.1, 195.8, 190.9, 174.1, 172.8, 171.7, 155.8,
153.0, 150.6, 139.0, 138.9, 138.3, 136.7, 136.6, 136.0, 133.4,
133.3, 131.3, 131.1, 130.5, 130.3, 129.4, 129.3, 126.9, 121.1,
121.0, 114.9, 109.2, 61.3, 60.9, 59.7, 50.5, 50.3, 43.9, 41.5, 41.0,
40.9, 38.6, 32.2, 32.1, 28.7, 28.5, 27.4, 27.1, 24.4, 19.8, 19.6,
14.0, 13.9; Anal. calcd. for C33H35NO6; C: 73.18; H: 6.51; N:
2.59. Found: C: 73.29 H: 6.44; N: 2.51%.
1
1638, 1560, 1489, 1363, 1228, 820; H NMR (300 MHz, CDCl3)
dH: 7.70–7.61 (2H, m, ArH), 7.36 (1H, d, J = 7.2 Hz, ArH), 7.28
(2H, d, J = 7.2 Hz, ArH), 7.06 (1H, t, J = 7.5 Hz, ArH), 6.85 (1H, t,
J = 7.5 Hz, ArH), 5.23 (1H, d, J = 7.5 Hz, ArH), 4.27–4.09 (2H, m,
OCH2), 3.93–3.82 (2H, m, OCH2), 3.35 (1H, d, J = 16.2 Hz,
CHaHb), 3.18 (1H, d, J = 16.2 Hz, CHbHa), 2.22 (1H, d, J = 15.9
Hz, CH2), 2.13 (1H, d, J = 15.9 Hz, CH2), 2.09 (1H, d, J = 17.4 Hz,
CH2), 1.87 (1H, d, J = 17.4 Hz, CH2), 1.22 (3H, t, J = 7.2 Hz,
CH3), 1.00–0.85 (9H, m, 3 6 CH3); 13C NMR (75 MHz, CDCl3)
dC: 196.0, 190.9, 172.8, 171.8, 155.3, 152.3, 137.8, 136.5, 133.6,
133.2, 132.9, 131.7, 131.5, 129.7, 124.3, 121.6, 120.8, 115.3,
110.0, 61.5, 59.8, 50.3, 43.8, 41.3, 38.6, 32.2, 28.9, 27.1, 14.1,
14.0; Anal. calcd. for C31H30BrNO6; C: 62.84; H: 5.10; N: 2.36.
Found: C: 63.03 H: 5.05; N: 2.29%.
Ethyl-10-[(ethoxycarbonyl)methyl]-5-(4-chlorophenyl)-
6,7,8,9,10,11-hexahydro-7,7-dimethyl-9,11-dioxo-
5H-indeno[1,2-b]quinoline-10-carboxylate (4s)
Ethyl-10-[(ethoxycarbonyl)methyl]-5-benzyl-6,7,8,9,10,11-
hexahydro-7,7-dimethyl-9,11-dioxo-5H-indeno[1,2-b]quinoline-
10-carboxylate (4v)
(Table 2, entry 19): Yield 70% (384 mg); red solid; m.p.: 208–
210 uC (EtOAc); vmax (KBr) (cm21) 2958, 1738, 1721, 1687, 1644,
1589, 1493, 1589, 1493, 1399, 1362, 1226, 1157, 1085, 1017,
854; 1H NMR (300 MHz, CDCl3) dH: 7.55–7.40 (3H, m, ArH),
7.34 (1H, d, J = 7.8 Hz, ArH), 7.28 (1H, d, J = 6.9 Hz, ArH), 7.06
(1H, t, J = 7.5 Hz, ArH), 6.84 (1H, t, J = 7.5 Hz, ArH), 5.23 (1H, d,
J = 7.5 Hz, ArH), 4.25–4.10 (2H, m, OCH2), 3.93–3.84 (2H, m,
OCH2), 3.35 (1H, d, J = 16.2 Hz, CHaHb), 3.17 (1H, d, J = 16.2
Hz, CHbHa), 2.21 (1H, d, J = 16.2 Hz, CH2), 2.13 (1H, d, J = 16.2
Hz, CH2), 2.09 (1H, d, J = 17.4 Hz, CH2), 1.88 (1H, d, J = 17.4 Hz,
CH2), 1.21 (3H, t, J = 7.2 Hz, CH3), 1.00–0.85 (9H, m, 3 6 CH3);
13C NMR (75 MHz, CDCl3) dC: 196.0, 190.9, 172.8, 171.8, 155.4,
152.4, 137.3, 136.5, 136.4, 133.2, 131.5, 131.4, 131.2, 130.7,
129.9, 129.7, 121.6, 120.8, 115.3, 110.0, 61.5, 59.8, 50.3, 43.8,
41.3, 38.6, 32.2, 28.9, 27.1, 14.1; Anal. calcd. for C31H30ClNO6;
C: 67.94; H: 5.52; N: 2.56. Found: C: 68.20 H: 5.46; N: 2.48%.
(Table 2, entry 22): Yield 65% (343 mg); red solid; m.p.: 180–
182 uC (EtOAc); nmax (KBr) (cm21) 2953, 1739, 1715, 1680, 1644,
1
1589, 1552, 1453, 1411, 1374, 1028, 720; H NMR (300 MHz,
CDCl3) dH: 7.45–7.30 (6H, m, ArH), 7.13 (1H, t, J = 7.5 Hz, ArH),
7.00 (1H, t, J = 7.5 Hz, ArH), 6.78 (1H, d, J = 7.5 Hz, ArH), 5.30–
5.10 (2H, m, CH2), 4.25–4.09 (2H, m, OCH2), 3.95–3.85 (2H, m,
OCH2), 3.41 (1H, d, J = 15.6 Hz, CHaHb), 3.19 (1H, d, J = 15.6
Hz, CHaHb), 2.40–2.25 (2H, m, CH2), 1.97 (2H, s, CH2), 1.23
(3H, t, J = 6.9 Hz, CH3), 1.00–0.88 (9H, m, 3 6 CH3); 13C NMR
(75 MHz, CDCl3) dC: 195.8, 190.7, 172.8, 171.9, 157.2, 153.4,
136.5, 136.1, 133.6, 131.8, 129.9, 129.5, 128.1, 125.3, 125.2,
121.9, 121.3, 116.2, 110.7, 61.5, 59.8, 50.7, 50.2, 44.2, 39.6,
38.4, 32.4, 27.8, 14.1; Anal. calcd. for C32H33NO6; C: 72.85; H:
6.30; N: 2.65. Found: C: 73.04 H: 6.22; N: 2.59%.
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-7,7-
dimethyl-5-[(naphthalen-1-yl)methyl]-9,11-dioxo-
5H-indeno[1,2-b]quinoline-10-carboxylate (4w)
Ethyl-10-[(ethoxycarbonyl)methyl]-6,7,8,9,10,11-hexahydro-7,7-
dimethyl-9,11-dioxo-5-m-tolyl-5H-indeno[1,2-b]quinoline-10-
carboxylate (4t)
(Table 2, entry 23): Yield 67% (387 mg); red solid; m.p.: 220–
222 uC (EtOAc); vmax (KBr) (cm21) 2960, 1732, 1684, 1654, 1634,
1
(Table 2, entry 20): Yield 75% (396 mg); red solid; m.p.: 148–
1590, 1557, 1414, 1368, 1326, 1024, 794; H NMR (300 MHz,
150 uC (EtOAc); vmax (KBr) (cm21) 2950, 1729, 1644, 1588, 1458,
CDCl3) dH: 7.95 (1H, d, J = 7.2 Hz, ArH), 7.87 (1H, d, J = 8.1 Hz,
ArH), 7.82 (1H, d, J = 8.1 Hz, ArH), 7.61 (2H, t, J = 7.2 Hz, ArH),
1
1360, 1238, 1081, 1028, 901, 722; H NMR (300 MHz, CDCl3)
3300 | RSC Adv., 2013, 3, 3291–3303
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7.55–7.40 (2H, m, ArH), 7.31 (1H, d, J = 6.9 Hz, ArH), 7.03 (1H,
t, J = 7.5 Hz, ArH), 6.77 (1H, t, J = 7.5 Hz, ArH), 6.49 (1H, d, J =
7.5 Hz, ArH), 5.65–5.50 (2H, m, NCH2), 4.30–4.10 (2H, m,
OCH2), 4.00–3.90 (2H, m, OCH2), 3.46 (1H, d, J = 15.9 Hz,
CHaHb), 3.25 (1H, d, J = 15.9 Hz, CHbHa), 2.45–2.35 (2H, m,
CH2), 2.19 (2H, s, CH2), 1.24 (3H, t, J = 7.2 Hz, CH3), 0.99 (3H, t,
J = 7.2 Hz, CH3), 0.95–0.85 (6H, m, 2 6 CH3); 13C NMR (75
MHz, CDCl3) dC: 195.8, 190.7, 172.8, 172.0, 157.2, 153.3, 135.9,
133.8, 133.5, 131.8, 131.4, 129.7, 129.4, 129.1, 128.9, 128.8,
127.2, 126.6, 125.9, 123.6, 121.7, 121.3, 121.1, 116.3, 110.7,
61.4, 59.7, 50.2, 49.1, 44.2, 39.2, 38.3, 32.4, 29.6, 21.7, 14.0;
Anal. calcd. for C36H35NO6; C: 74.85; H: 6.11; N: 2.42. Found:
C: 75.02 H: 6.07; N: 2.35%.
calcd. for C25H21NO4; C: 75.17; H: 5.30; N: 3.51. Found: C:
75.31; H: 5.26; N: 3.45%.
Methyl-10-methyl-6,7,8,9,10-pentahydro-8,10-dioxo-5-(4-
bromophenyl)-5H-indeno[1,2-b]cyclopenta[e]pyridine-10-
carboxylate (10c)
(Table 3, entry 3): Yield 73% (339 mg); red solid; m.p.: 236–238
uC (EtOAc); vmax (KBr) (cm21) 1752, 1688, 1645, 1591, 1553,
1
1492, 1393, 1371, 1097, 1067, 825; H NMR (300 MHz, CDCl3)
dH: 7.75 (2H, d, J = 9.0 Hz, ArH), 7.45–7.35 (3H, m, ArH), 7.21
(1H, t, J = 7.5 Hz, ArH), 7.01 (1H, t, J = 7.5 Hz, ArH), 5.59 (1H, d,
J = 7.5 Hz, ArH), 3.79 (3H, s, CO2Me), 2.50–2.42 (2H, m, CH2),
2.39–2.34 (2H, m, CH2), 1.77 (3H, s, Me); 13C NMR (75 MHz,
CDCl3) dC: 190.8, 173.3, 165.0, 154.5, 136.7, 136.0, 133.4, 133.3,
131.7, 130.6, 130.5, 129.9, 124.6, 122.7, 121.9, 120.9, 114.9,
52.8, 41.0, 34.0, 25.0, 23.0; Anal. calcd. for C24H18BrNO4; C:
62.08; H: 3.91; N: 3.02. Found: C: 62.22; H: 3.87; N: 2.96%.
Ethyl-10-[(ethoxycarbonyl)methyl]-5-butyl-6,7,8,9,10,11-
hexahydro-7,7-dimethyl-9,11-dioxo-5H-indeno[1,2-b]quinoline-
10-carboxylate (4x)
(Table 2, entry 24): Yield 62% (306 mg); red viscous liquid; vmax
(KBr) (cm21) 2960, 1716, 1677, 1657, 1626, 1455, 1403, 1324,
1157, 1068, 895; 1H NMR (300 MHz, CDCl3) dH: 7.41–7.37 (6H,
m, ArH), 7.26–7.17 (3H, m, ArH), 4.17–4.11 (2H, m, OCH2),
3.91–3.80 (4H, m, OCH2 and NCH2), 3.31 (1H, d, J = 15.3 Hz,
CHaHb), 3.10 (1H, d, J = 15.3 Hz, CHbHa), 2.55–2.40 (2H, m,
CH2), 2.21 (2H, s, CH2), 1.85–1.70 (2H, m, CH2), 1.50–1.35 (2H,
m, CH2), 1.18 (3H, t, J = 7.2 Hz, CH3), 1.08 (6H, s, 2 6 CH3),
0.99–0.90 (6H, m, 2 6 CH3); 13C NMR (75 MHz, CDCl3) dC:
195.8, 190.6, 172.8, 171.7, 156.5, 152.6, 136.6, 133.8, 131.8,
129.9, 121.9, 121.0, 116.0, 110.7, 61.3, 59.7, 49.9, 46.6, 44.0,
40.1, 38.4, 33.3, 32.4, 28.5, 28.0, 19.7, 14.0, 13.7; Anal. calcd.
for C29H35NO6; C: 70.57; H: 7.15; N: 2.84. Found: C: 70.74 H:
7.08; N: 2.77%.
Methyl-10-methyl-6,7,8,9,10-pentahydro-8,10-dioxo-5-(3-
methylphenyl)-5H-indeno[1,2-b]cyclopenta[e]pyridine-10-
carboxylate (10d)
(Table 3, entry 4): Yield 74% (296 mg); red solid; m.p.: 242–244
uC (EtOAc); vmax (KBr) (cm21) 2931, 1748, 1692, 1644, 1592,
1
1557, 1392, 1372, 1309, 1232, 884; H NMR (300 MHz, CDCl3)
dH: 7.55–7.25 (5H, m, ArH), 7.16 (1H, t, J = 7.5 Hz, ArH), 6.94
(1H, t, J = 7.5 Hz, ArH), 5.49 (1H, d, J = 7.2 Hz, ArH), 3.77 (3H, s,
CO2Me), 2.55–2.35 (7H, m, 2 6 CH2 and CH3), 1.85–1.75 (3H,
m, CH3); 13C NMR (75 MHz, CDCl3) dC: 190.9, 173.3, 165.7,
155.0, 140.4, 137.4, 136.1, 133.4, 131.5, 131.1, 129.7, 129.6,
129.4, 129.3, 125.9, 125.7, 122.3, 121.6, 121.1, 114.4, 52.6, 40.9,
34.0, 24.9, 23.1, 22.9, 21.2; Anal. calcd. for C25H21NO4; C:
75.17; H: 5.30; N: 3.51. Found: C: 75.34; H: 5.26; N: 3.47%.
Methyl-10-methyl-6,7,8,9,10-pentahydro-8,10-dioxo-5-phenyl-
5H-indeno[1,2-b]cyclopenta[e]pyridine-10-carboxylate (10a)
Ethyl-10-methyl-6,7,8,9,10-pentahydro-8,10-dioxo-5-(4-
methoxyphenyl)-5H-indeno[1,2-b]cyclopenta[e]pyridine-10-
carboxylate (10e)
(Table 3, entry 1): Yield 80% (308 mg); red solid; m.p.: 218–220
uC (EtOAc); vmax (KBr) (cm21) 1728, 1694, 1683, 1589, 1557,
(Table 3, entry 5): Yield 79% (339 mg); red solid; m.p.: 202–204
uC (EtOAc); nmax (KBr) (cm21) 1727, 1683, 1640, 1592, 1552,
1374, 1305, 1252, 1104, 895; 1H NMR (300 MHz, CDCl3) dH:
7.40–7.30 (3H, m, ArH), 7.15 (1H, t, J = 7.5 Hz, ArH), 7.10–7.02
(2H, m, ArH), 6.95 (1H, dt, J = 7.5 Hz and 0.9 Hz, ArH), 5.56
(1H, d, J = 7.5 Hz, ArH), 4.23 (2H, q, J = 7.2 Hz, OCH2), 3.93 (3H,
s, OMe), 2.45–2.34 (4H, m, CH2), 1.73 (3H, s, Me), 1.26 (3H, t, J
= 7.2 Hz, CH3); 13C NMR (75 MHz, CDCl3) dC: 190.9, 172.8,
166.0, 160.6, 155.3, 136.2, 133.4, 131.5, 130.0, 129.9, 129.8,
129.5, 122.4, 121.4, 121.1, 114.9, 114.4, 61.3, 55.6, 41.0, 34.0,
24.9, 22.8, 14.0; Anal. calcd. for C26H23NO5; C: 72.71; H: 5.40;
N: 3.26. Found: C: 72.88; H: 5.36; N: 3.19%.
1
1455, 1361, 1309, 1263, 1099, 898; H NMR (300 MHz, CDCl3)
dH: 7.70–7.45 (5H, m, ArH), 7.39 (1H, d, J = 6.9 Hz, ArH), 7.16
(1H, t, J = 7.5 Hz, ArH), 6.92 (1H, dt, J = 7.5 Hz and 0.9 Hz,
ArH), 5.45 (1H, d, J = 7.5 Hz, ArH), 3.78 (3H, s, CO2Me), 2.50–
2.30 (4H, m, ArH), 1.77 (3H, s, Me); 13C NMR (75 MHz, CDCl3)
dC: 190.9, 173.3, 165.6, 154.9, 137.6, 136.1, 133.4, 131.5, 130.4,
130.0, 129.7, 129.0, 128.9, 122.4, 121.6, 121.1, 114.5, 52.7, 40.9,
34.1, 25.0, 23.0; Anal. calcd. for C24H19NO4; C: 74.79; H: 4.97;
N: 3.63. Found: C: 74.98; H: 4.90; N: 3.56%.
Methyl-10-methyl-6,7,8,9,10-pentahydro-8,10-dioxo-5-(4-
methylphenyl)-5H-indeno[1,2-b]cyclopenta[e]pyridine-10-
carboxylate (10b)
Ethyl-10-methyl-6,7,8,9,10-pentahydro-8,10-dioxo-5-(2-
methylphenyl)-5H-indeno[1,2-b]cyclopenta[e]pyridine-10-
carboxylate (10f)
(Table 3, entry 2): Yield 78% (312 mg); red solid; m.p.: 210–212
uC (EtOAc); vmax (KBr) (cm21) 1727, 1688, 1642, 1591, 1557,
1
1395, 1372, 1262, 1140; H NMR (300 MHz, CDCl3) dH: 7.40–
(Table 3, entry 6): Yield 72% (298 mg); red solid; m.p.: 174–176
uC (EtOAc); vmax (KBr) (cm21) 1721, 1687, 1645, 1591, 1552,
7.25 (5H, m, ArH), 7.09 (1H, t, J = 7.5 Hz, ArH), 6.87 (1H, t, J =
7.5 Hz, ArH), 5.45 (1H, J = 7.5 Hz, ArH), 3.70 (3H, s, CO2Me),
2.45 (3H, s, Me), 2.40–2.20 (4H, m, CH2), 1.69 (3H, s, Me); 13C
NMR (75 MHz, CDCl3) dC: 190.9, 173.4, 165.8, 155.1, 140.7,
136.2, 134.9, 133.4, 131.5, 130.6, 129.6, 128.6, 128.5, 122.3,
121.6, 121.1, 114.4, 52.6, 40.9, 34.0, 24.9, 23.0, 21.3; Anal.
1
1454, 1393, 1368, 1240, 1098, 891; H NMR (300 MHz, CDCl3)
dH: 7.60–7.50 (1H, m, ArH), 7.49–7.40 (4H, m, ArH), 7.18 (1H, t,
J = 7.5 Hz, ArH), 6.93 (1H, t, J = 7.5 Hz, ArH), 5.45 (1H, d, J = 7.5
Hz, ArH), 4.24 (2H, q, J = 7.2 Hz, OCH2), 2.50–2.40 (3H, m,
CH2), 2.28 (3H, s, Me), 2.25–2.10 (1H, m, CH2), 1.77 (3H, s,
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CH3), 1.26 (3H, t, J = 7.2 Hz, CH3); 13C NMR (75 MHz, CDCl3)
dC: 190.9, 172.7, 165.4, 155.1, 137.7, 136.6, 136.1, 133.4, 131.8,
131.7, 130.7, 129.8, 129.0, 127.6, 122.7, 121.7, 120.1, 114.4,
61.5, 41.3, 34.1, 24.7, 22.1, 17.2, 14.1; Anal. calcd. for
C26H23NO4; C: 75.53; H: 5.61; N: 3.39. Found: C: 75.75; H:
5.57; N: 3.35%.
3 (a) C. Mukhopadhyay, S. Rana, R. J. Butcher and A.
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V. P. Mehta, S. G. Modha, E. Ruijter, K. V. Hecke, L.
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I. Colao, A. Venuti, M. T. Sciortino, P. Primerano and
G. Grassi, Mol. Diversity, 2012, 16, 325; (e) S. Muthusamy,
J. Krishnamurthi and E. Suresh, Chem. Commun., 2007,
861; (f) M. Paravidino, R. S. Bon, R. Scheffelaar, D. J. Vugts,
A. Znabet, R. F. Schmitz, F. J. J. de Kanter, M. Lutz, A.
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5369.
5,6,7,12-tetrahydro-6-methyl-7,12-dioxo-5-
phenylindeno[1,2,3,2-bcd]pyridine-6-carboxylate (6)
Yield 12% (54 mg); black solid; m.p.: 186–188 uC (EtOAc); vmax
(KBr) (cm21) 1728, 1681, 1638, 1589, 1556, 1421, 1370, 1352,
1242, 1007, 879; 1H NMR (300 MHz, CDCl3) dH: 8.57 (1H, d, J =
6.9 Hz, ArH), 7.60–7.18 (10H, m, ArH), 6.95 (1H, t, J = 7.2 Hz,
ArH), 5.33 (1H, d, J = 7.5 Hz, ArH), 4.15–4.05 (2H, m, OCH2),
1.83 (3H, s, CH3), 1.12 (3H, t, J = 7.2 Hz, CH3); 13C NMR (75
MHz, CDCl3) dC: 191.6, 186.3, 170.1, 167.1, 150.6, 139.1, 138.6,
138.2, 135.3, 133.7, 132.9, 132.4, 131.7, 130.5, 130.12, 130.08,
129.8, 129.7, 128.9, 126.2, 123.3, 121.9, 121.2, 114.2, 103.3,
70.4, 62.4, 21.6, 14.0; Anal. calcd. for C29H21NO4; C: 77.84; H:
4.73; N: 3.13. Found: C: 78.03; H: 4.68; N: 3.07%.
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2-[3-(phenylamino)-1H-inden-1-ylidene]-2H-indene-1,3-dione
(7)31
Yield 25% (87 mg); deep blue solid; m.p.: 214–216 uC (EtOAc);
vmax (KBr) (cm21) 3042, 1700.8, 1634, 1587, 1481, 1449, 1351,
1326, 1092, 1001, 746; 1H NMR (300 MHz, DMSO-d6) dH: 10.72
(1H, brs, NH), 9.20–9.15 (1H, m, ArH), 7.95–7.30 (13H, m,
ArH); Anal. calcd. for C24H15NO2; C: 82.50; H: 4.33; N: 4.01.
Found: C: 82.74; H: 4.26; N: 3.94%. We were not able to take
the 13C NMR spectrum of compound 6 due to its poor
solubility in the NMR solvent.
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Acknowledgements
One of the authors (SR) thanks the Council of Scientific and
Industrial Research, New Delhi, for his fellowship (SRF). We
acknowledge the grant received from UGC funded Major
project, F. No. 37-398/2009 (SR) dated 11-01-2010.
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