DABCO-Promoted three-component regioselective synthesis of functionalized chromen-5-ones and pyrano[3,2-c]chromen-5-ones via direct annulation of α-oxoketene-N,S-arylaminoacetals under solvent-free conditions

Article abstract of DOI:10.1039/c1gc16129f

An efficient and convergent route to 3-aroyl-4-aryl-2-arylamino-4,6,7,8- tetrahydrochromen-5-ones and hitherto unreported 3-aroyl-4-aryl-2-arylamino-4H- pyrano[3,2-c]chromen-5-ones has been developed by an one-pot three-component domino coupling of α-oxok

Full text of DOI:10.1039/c1gc16129f

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PAPER
DABCO-Promoted three-component regioselective synthesis of
functionalized chromen-5-ones and pyrano[3,2-c]chromen-5-ones via direct
annulation of a-oxoketene-N,S-arylaminoacetals under solvent-free
conditions†
Maya Shankar Singh,* Ganesh Chandra Nandi and Subhasis Samai
Received 9th September 2011, Accepted 11th November 2011
DOI: 10.1039/c1gc16129f
An efficient and convergent route to 3-aroyl-4-aryl-2-arylamino-4,6,7,8-tetrahydrochromen-5-ones
and hitherto unreported 3-aroyl-4-aryl-2-arylamino-4H-pyrano[3,2-c]chromen-5-ones has been
developed by an one-pot three-component domino coupling of a-oxoketene-N,S-arylamino-
acetals, aromatic aldehydes, and dimedone/4-hydroxycoumarin in the presence of DABCO under
solvent-free conditions in high yields. Further, suitably substituted pyrano[3,2-c]chromen-5-ones
undergo intramolecular aromatic nucleophilic substitution (SNAr) to give pentacyclic
pyrano[3,2-c]chromenoquinolines in excellent yields. The merit of this cascade Knoevenagel
condensation/Michael addition/cyclization sequence is highlighted by its high atom-economy,
good yields, efficiency of producing three new bonds (two C–C and one C–O), and one
stereocenter in a single operation. The protocol avoids the use of expensive catalysts, toxic organic
reagents/solvents, and anhydrous condition. In particular the attractive feature of this approach is
the synthesis of three important bioactive heterocyclic frameworks from the same
a-oxoketene-N,S-arylaminoacetal under the similar reaction conditions making this new strategy
highly useful in diversity oriented synthesis (DOS).
due to its straightforward reaction design, convergent, and atom-
Introduction
efficient nature resulting in substantial minimization of waste,
The development of chemical methodologies that provide
labor, time, and cost.5–7 As a consequence, multicomponent
maximum structural complexity and diversity with a minimum
as well as domino or related reactions are witnessing a new
number of synthetic steps to assemble compounds with inter-
spring.8 Because of the increasing public concern for the
esting properties is a key facet of modern drug discovery.1 The
harmful effects of organic solvents on the environment and
synthetic strategies regarding how to construct and cleave the
human body, solvent-free reactions9 have gained the attention
carbon–carbon (C–C) and carbon–heteroatom (C–X) bond(s)
of organic chemists due to their more efficient and less labour-
represent the central theme in organic synthesis. Due to grow-
intense methodologies. Furthermore, solvent-free multicompo-
ing environmental concerns, a pressing challenge to organic
nent reactions have encompassed wide areas of the chemical
chemists is to develop new methods that are not only efficient,
enterprise and are attractive, because they incorporate many
selective, and high yielding but also eco-compatible. For reasons
green chemistry principles.
of economy and pollution prevention, one approach to address
Chromene and it’s benzo-/hetero-fused analogues represent a
this challenge involves the development of multicomponent
class of important heterocycles due to their presence in a broad
procedures in organic synthesis. Multicomponent reactions2–4
spectrum of synthetic and natural products such as alkaloids,
(MCRs) have emerged as a highly valuable tools for the
flavonoids, tocopherols, and anthocyanins with diverse biologi-
rapid generation of molecular complexity and diversity with
cal properties.10 Chromene systems are of particular importance
predefined functionality in chemical biology and drug discovery,
as they belong to privileged medicinal scaffolds with highly pro-
nounced spasmolytic, diuretic, anticoagulant, anticancer, and
antianaphylactic activities.11 Moreover, these moieties have the
Department of chemistry, Faculty of Science, Banaras Hindu university,
Varanasi, 221005, India. E-mail: mssinghbhu@yahoo.co.in;
Fax: +91-542-2368127; Tel: +91-542-6702502
† Electronic supplementary information (ESI) available: Detailed exper-
imental procedure, spectral, analytical data of all the compounds and
their 1H and 13C spectra. See DOI: 10.1039/c1gc16129f
potential application in the treatment of human inflammatory
TNFa-mediated diseases such as rheumatoid, psoriatic arthritis,
apoptosis inducer, and as an inhibitor of excitatory amino acid
transporter.12 Further, these compounds also find applications
as pigments and as potential biodegradable agrochemicals.13
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The pyranochromenes have been used as cognitive enhancers
for the treatment of neurodegenerative diseases, including
Alzheimer’s disease, amyotrophic lateral sclerosis, Parkinson’s
disease, Huntington’s disease, AIDS associated dementia and
Down’s syndrome as well as for the treatment of schizophre-
nia and myoclonus.14 In addition, aminochromene derivatives
exhibit a wide spectrum of biological activities including anti-
hypertensive and anti-ischemic behavior.15 Suitably substituted
chromenes are particularly versatile compounds that bind to
the Bcl-2 protein (B-cell lymphoma 2) and induce apoptosis
in tumor cells.16 Bcl-2 protein binding compounds provide a
promising lead for the development of potential anticancer
agents and direct methods for their synthesis are highly desirable.
As a part of our continuous efforts toward the develop-
ment of new synthetic methods for important heterocyclic
compounds,20,21 in this paper, we wish to disclose a facile
chemo- and regioselective synthesis of chromen-5-ones and
4H-pyrano[3,2-c]chromen-5-ones by one-pot three-component
coupling of a-oxoketene-N,S-arylaminoacetals, aromatic alde-
hydes, and dimedone/4-hydroxycoumarin under solvent-free
conditions at 100 ◦C in the presence of DABCO (Scheme 1). The
reactions were completed within 40–50 min and the pure prod-
ucts were isolated in high yields simply by addition of ethanol to
the reaction mixture. We also represent two interesting examples
of fused pentacyclic heterocycles, which have been synthesized
by an intramolecular aromatic nucleophilic substitution reaction
(Scheme 2). The synthetic route is facile, convergent, and allows
easy placement of a variety of substituents around the periphery
of the heterocyclic ring system.
As
a result, numerous synthetic routes to chromene
derivatives have been reported.17 Recently, synthesis of 2-
arylaminochromene derivatives has been developed via a mul-
ticomponent approach,18 which required a long reaction time
(20–25 h). Albeit the reported approaches are useful tools for
the synthesis of chromene derivatives, most of them suffer
from significant limitations such as harsh reaction conditions,
expensive catalysts/reagents, prolonged reaction times, and
multistep synthesis. Therefore, exploration of more general,
efficient, rapid, and viable routes are very desirable, and would
be of great relevance to both synthetic and medicinal chemists
due to their broad array of applications in the areas of biology,
material science, and medicinal chemistry.
Scheme 1 Synthesis of chromen-5-ones 6 and pyrano[3,2-c]chromen-
5-ones 7.
Results and discussion
The vast biological importance of chromene derivatives inspired
us to develop a novel protocol for their efficient synthesis.
Synthons containing both electrophilic and nucleophilic sites
(ambiphilic synthons) have great potential in developing new
reaction pathways. One such synthon is a-oxoketene-N,S-
arylaminoacetal, and its utility as versatile intermediates in
organic synthesis has been well recognized.19 It has four active
sites as shown in the Fig. 1. Two nucleophilic centres are
localised on the nitrogen and a-carbon atoms, whereas two
electrophilic centres are associated with the carbonyl and
thiomethyl carbon atoms. Thus, the reaction of a-oxoketene-
N,S-arylaminoacetal with dielectrophilic reagents may lead to
the formation of various important heterocyclic compounds,
depending on the structure of the dielectrophile and the reaction
conditions.
Scheme 2 Synthesis of pyrano[3,2-c]chromenoquinolines.
The precursor a-oxoketene-N,S-arylaminoacetals were not
commercially sourced and were synthesized in good yields (70–
75%) by the reaction of active methylene ketones with phenyl
isothiocyanate in the presence of NaH in DMF followed by the
addition of methyl iodide according to a reported procedure22
(Table 1).
Our careful literature survey at this stage revealed that there
is no report on the use of DABCO as a catalyst in the syn-
thesis of chromen-5-one and pyranochromen-5-one derivatives
utilizing a-oxoketene-N,S-arylaminoacetals under solvent-free
conditions. Thus, coupling of 2 with aromatic aldehydes 3
and active methylene compounds 4 or 5 in the presence of
DABCO under solvent-free conditions provided chromen-5-
ones 6 and pyrano[3,2-c]chromen-5-ones 7, respectively in high
yields (Scheme 1).
The synthesis of 3-aroyl/heteroaroyl-4-aryl-2-arylamino-
4,6,7,8-tetrahydrochromen-5-ones 6 was first undertaken. a-
Oxoketene-N,S-acetal 2c (1.0 mmol), 4-nitrobenzaldehyde
(1.0 mmol), and dimedone (1.0 mmol) were selected as test
Fig. 1 The reaction profile of N,S-acetal.
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Table 1 Synthesis of a-oxoketene-N,S-arylaminoacetals 2
the yield drastically (Table 2, entry 11). The reaction efficiency
was also assessed with varying reaction temperatures. The results
demonstrated that 100 ◦C was found to be the optimum temper-
ature. Lowering the temperature (80 ◦C) became detrimental to
the reaction, while increasing the temperature (120 ◦C) had no
significant effect on the reaction (Table 2, entries 13, 14). Thus,
the best yield, cleanest reaction, and most facile workup were
achieved employing 1.0 equiv. of DABCO under solvent-free
conditions at 100 ◦C.
With the optimized conditions in hand, to delineate this
approach, the scope and generality of this protocol was next
examined by employing various a-oxoketene-N,S-acetals and
aromatic aldehydes. Notably, a wide range of Ar1 groups (aro-
matic and heteroaromatic) were well tolerated and incorporated
providing a functional handle for further manipulation. No
obvious electronic effects of the aldehyde were observed, and
the products were obtained in high yields (Table 3).
After successful coupling of a-oxoketene-N,S-acetals, aro-
matic aldehydes and dimedone under solvent-free conditions, 4-
hydroxycoumarin was also utilized in place of dimedone in order
to gain further insight about this transformation, and to show
versatility of this protocol. Thus, coupling of 2, 3, and 5 provided
easy access to pyrano[3,2-c]chromen-5-ones 7 in good yields
(Table 4). The capacity of the reaction was fruitfully proved for
a wide range of Ar1 and Ar2.
It is important to highlight that, recently, an intramolecular
nucleophilic aryl substitution reaction (SNAr) of the ortho-
halo group into the aryl ring of 2-benzoylthioacetanilides was
reported by Li and coworkers.18 Interestingly, the SNAr may
occur in our pyrano[3,2-c]chromen-5-ones 7, if there is a halogen
group present at the ortho-position of the Ar1 ring. Pyrano[3,2-
c]chromen-5-ones 7h and 7i containing ortho-chlorine, when
heated to 100 ◦C in DMF in the presence of K2CO3 for
40 min underwent SNAr reaction to give pentacyclic pyrano[3,2-
c]chromenoquinolines 8a and 8b as exclusive products in 92 and
94% yields, respectively (Scheme 2).
The main advantage of this procedure is the simple work
up, and the product was obtained in high purity simply by
addition of ethanol to the reaction mixture, which makes this
methodology facile, practical, and rapid to execute. The purity
of the product was high enough for spectroscopic analysis
without any further purification, but all the compounds were
nevertheless crystallized from ethanol. The structures of all the
newly synthesized compounds 6, 7 and 8 were well characterized
from their satisfactory elemental and spectral (IR, 1H, 13C
NMR, and MS) studies. The mass spectra of these compounds
displayed molecular ion peaks at the appropriate m/z values.
Taking into consideration the entire outcome, a plausible
mechanistic pathway for the domino coupling is depicted in
Scheme 3. The first step is the Knoevenagel condensation
between aldehyde 3 and active methylene compound 4 to give the
Knoevenangel adduct A, which acts as a Michael acceptor. The
adduct A immediately undergoes Michael-type addition with a-
oxoketene-N,S-acetal 2 to generate the open chain intermediate
B. The intermediate B undergoes intramolecular O-cyclization
via route I to give compound 6 with elimination of MeSH. The
intermediate B may exist in its two rotameric forms B1 and B2,
which could probably undergo N- or O-cyclizations via routes
II or III to give compounds 9 and 10, respectively. During
Entry
Ar1
Ar
Product
Yielda (%)
1
2
3
4
5
6
C6H5
4-MeOC6H4
2-Furyl
2-Thienyl
2-ClC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
C6H5
C6H5
C6H5
2a
2b
2c
2d
2e
2f
72
70
73
72
75
74
C6H5
a Isolated pure yields.
Table 2 Optimization of the reaction conditionsa for the synthesis of
chromen-5-ones 6
Product 6
Entry Reaction conditions
yieldb (%)
1
2
3
4
5
6
7
8
No catalyst, EtOH, reflux, 24 h
TEA (1.0 eq.), EtOH, reflux, 10 h
DABCO (1.0 eq.), EtOH, reflux, 7 h
DMAP (1.0 eq.), EtOH, reflux, 24 h
15
67
74
55
58
65
78
83
65
63
51
75
66
81
L-proline (1.0 eq.), EtOH, reflux, 20 h
No catalyst, solvent-free, 100 ◦C, 7 h
TEA (1.0 eq.), solvent-free, 100 ◦C, 1.5 h
DABCO (1.0 eq.), solvent-free, 100 ◦C, 40 min
DMAP (1.0 eqv.), solvent-free, 100 ◦C, 3 h
L-proline (1.0 eqv.), solvent-free, 100 ◦C, 2.5 h
DABCO (0.5 eq.), solvent-free, 100 ◦C, 2.5 h
DABCO (1.5 eq.), solvent-free, 100 ◦C, 45 min
DABCO (1.0 eq.), solvent-free, 80 ◦C, 2.5 h
DABCO (1.0 eq.), solvent-free, 120 ◦C, 40 min
9
10
11
12
13
14
a The reaction of 4-nitrobenzaldehyde (1.0 mmol), a-oxoketene-N,S-
acetal 2c (1.0 mmol), and dimedone (1.0 mmol). b Isolated pure yields.
substrates to optimize the reaction conditions. Initially, the
above three-component coupling has been carried out in EtOH
under reflux without any catalyst to establish the real effective-
ness of the catalyst. Only 15% conversion to the product was
observed even after 24 h of reflux. Next, the above test reaction
was investigated in the presence of various catalysts such
as triethylamine (TEA), DABCO, 4-dimethylaminopyridine
(DMAP), and L-proline separately in refluxing EtOH and the
results are summarized in Table 2. All the catalysts did catalyze
the reaction, albeit in low efficiency. In recent years, solvent-free
reactions have been much utilized and have become a powerful
tool in organic synthesis. As a consequence, to get better reaction
conditions, the above test reaction was used to screened through
the above catalysts separately under solvent-free conditions. To
our delight, the reaction was completed quickly providing good
yield of the desired product. The main notable observation of
this reaction is that the product was obtained in 65% yield,
even in the absence of catalyst (Table 2, entry 6). Though the
catalytic activity of all the catalysts increased under solvent-free
conditions, DABCO was found to be the catalyst of choice for
this transformation (Table 2, entry 8).
With DABCO base as a good promoter in hand, we next
intended to optimize its loading, and it was found that the use
of 1.0 equiv. of DABCO provided the best result. Reducing the
equivalent of DABCO increased the reaction time and lowered
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Table 3 Scope exploration: variation of Ar1 and Ar2
Entry
Ar1
Ar
Ar2
R
Time (min)
Yielda (%)
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
6r
C6H5
C6H5
C6H5
4-OMeC6H4
4-OMeC6H4
4-OMeC6H4
2-Furyl
2-Furyl
2-Furyl
4-OMeC6H4
4-OMeC6H4
4-OMeC6H4
4-OMeC6H4
4-OMeC6H4
4-OMeC6H4
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
4-NO2C6H4
4-OMeC6H4
C6H5
4-NO2C6H4
3-NO2C6H4
4-BrC6H4
4-NO2C6H4
3-NO2C6H4
2-NO2C6H4
4-ClC6H4
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
H
Me
Me
Me
Me
Me
H
40
50
45
50
45
45
40
45
50
40
45
45
55
40
50
60
55
65
78
73
76
82
84
80
80
83
76
78
76
82
72
81
70
82
84
74
2-Furyl
2-Furyl
C6H5
2-Thienyl
2-Thienyl
2-Thienyl
2-Thienyl
2-ClC6H4
2-ClC6H4
2-ClC6H4
3-NO2C6H4
2,4-Cl2C6H3
4-BrC6H4
4-OMeC6H4
4-BrC6H4
3-NO2C6H4
4-OMeC6H4
H
a Isolated pure yields.
Table 4 The synthesis of pyrano[3,2-c]chromen-5-ones 7
Entry
Ar1
Ar2
Time (min)
Yielda (%)
7a
7b
7c
7d
7e
7f
7g
7h
7i
2-Furyl
2-Furyl
4-ClC6H4
C6H5
3-NO2C6H4
4-FC6H4
4-MeC6H4
3-NO2C6H4
3-F-4-ClC6H4
4-BrC6H4
4-NO2C6H4
55
60
55
60
65
55
70
70
65
69
76
68
82
72
80
80
83
76
2-Thienyl
2-Thienyl
4-OMeC6H4
4-OMeC6H4
4-OMeC6H4
2-ClC6H4
2-ClC6H4
a Isolated yield.
our investigation, we did not observe even a trace of 9 or 10,
and only 6 was obtained exclusively, suggesting O-cyclization
through route I, making the protocol highly chemo- and
regioselective.
Scheme 3 Plausible reaction scenario for the formation of 6.
substitution (SNAr). In this experimentally simple process three
new bonds (two C–C and one C–O), and one stereocenter are
generated in a single operation with all reactants efficiently
utilized. Moreover, the arylamine and aroyl substituents in the
2- and 3-positions of the chromene ring are quite reactive;
this makes these compounds good candidates as precursors
for further synthetic transformations to meet the need for
various useful purposes. The short reaction time, excellent
yield, low-cost, operational simplicity, and more importantly the
purification of compounds by a non-chromatographic method
make this process very significant for academic research and
practical applications. Further studies on the extension of
Conclusions
In summary, we have developed a convenient, efficient, chemose-
lective, and regioselective synthesis of tetrahydrochromen-5-one
and pyrano[3,2-c]chromen-5-one frameworks by the reaction of
a-oxoketene-N,S-acetals, aromatic aldehydes, and dimedone/4-
hydroxycoumarin in the presence of DABCO under solvent-free
conditions. In addition, the suitably synthesized pyrano[3,2-
c]chromen-5-ones could be efficiently converted into pyrano[3,2-
c]chromenoquinoline by intramolecular aromatic nucleophilic
450 | Green Chem., 2012, 14, 447–455
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the scope of the use of a-oxoketene-N,S-arylaminoacetals in
synthetic applications are currently under way in our laboratory.
50.5, 40.3, 35.5, 32.2, 29.1, 27.1. IR (KBr, cm-1): 3055, 2954,
1683, 1666, 1631, 1590, 1562, 1373; MS: m/z = 547 (M++Na).
Elemental analysis for C31H28N2O6: calc. C, 70.98; H, 5.38; N,
5.34. Found: C, 70.74; H, 5.53; N, 5.47.
Experimental Section
General
3-Benzoyl-4-(4-methoxyphenyl)-2-(4-methoxyphenylamino)-7,7-
dimethyl-4,6,7,8-tetrahydrochromen-5-one (6b)
The starting materials were commercially available and used
as received without further purification. a-oxoketene-N,S-
arylaminoacetal 2 were prepared following the known proce-
dure. Thin-layer chromatography (TLC) was performed using
silica gel 60 F254 precoated plates. Infrared (IR) spectra are
measured in KBr, and wavelengths (n) are reported in cm-1. 1H
and 13C NMR spectra were recorded on NMR spectrometers
operating at 300 and 75.5 MHz, respectively. Chemical shifts
(d) are given in parts per million (ppm) using the residue solvent
peaks as reference relative to TMS. J values aregiveninHz. Mass
spectra were recorded using electrospray ionization (ESI) mass
spectrometry. The C, H, and N analyses were performed from
microanalytical laboratory. The melting points are uncorrected.
◦
1
White solid; mp 160–161 C. H NMR (300 MHz, CDCl3):
d 13.1 (s, 1H), 7.37–7.28 (m, 5H), 7.10 (d, J = 7.2 Hz, 2H),
6.92 (d, J = 8.7 Hz, 2H), 6.71 (d, J = 8.7 Hz, 2H), 6.60 (d,
J = 8.4 Hz, 2H), 4.74 (s, 1H), 3.84 (s, 3H), 3.71 (s, 3H), 2.52–
2.39 (m, 2H), 2.24 (d, J = 16.2 Hz, 1H), 2.15 (d, J = 16.2 Hz,
1H), 1.10 (s, 3H), 0.91 (s, 3H). 13C NMR (75 MHz, CDCl3):
d 196.1, 194.9, 160.5, 158.1, 157.7, 156.9, 140.8, 137.7, 129.8,
129.0, 128.6, 128.0, 126.3, 124.1, 118.0, 114.3, 113.3, 90.1, 55.4,
55.0, 50.7, 40.3, 34.2, 32.2, 29.2, 27.1. IR (KBr, cm-1): 3057, 2975,
1683, 1667, 1625, 1581, 1559, 1401; MS: m/z = 532 (M++Na).
Elemental analysis for C32H31NO5: calc. C, 75.42; H, 6.13; N,
2.75. Found: C, 75.58; H, 5.98; N, 2.63.
General procedure for synthesis of tetrahydrochromen-5-one
(6a-r) and pyrano[3,2-c]chromen-5-one (7a–i)
3-Benzoyl-2-(4-methoxyphenylamino)-7,7-dimethyl-
4-phenyl-4,6,7,8-tetrahydrochromen-5-one (6c)
◦
1
An oven-dried 10 ml round bottom flask was charged with
the appropriate aldehyde (1.0 mmol), cyclic 1,3-dicarbonyl
compound (1.0 mmol), a-oxoketene-N,S-arylaminoacetal
(1.0 mmol), and DABCO (1.0 mmol), and the reaction mixture
was heated in an oil bath at 100 ◦C for the stipulated period
of time till the completion of the reaction (monitored by
TLC). Ethanol (2 mL) was added to the reaction mixture.
The product appeared as a solid, which was filtered out and
washed with another 2 mL of EtOH to remove the DABCO and
other impurities. Finally, the products were recrystallized from
ethanol.
White solid; mp 182–183 C. H NMR (300 MHz, CDCl3): d
13.13 (s, 1H), 7.37–7.25 (m, 6H), 7.11–7.05 (m, 4H), 6.92 (d, J =
8.7 Hz, 2H), 6.79 (d, J = 5.7 Hz, 2H), 4.81 (s, 1H), 3.84 (s, 3H),
2.53–2.40 (m, 2H), 2.25 (d, J = 15 Hz, 1H), 2.16 (d, J = 15 Hz,
1H), 1.10 (s, 3H), 0.91 (s, 3H). 13C NMR (125 MHz, CDCl3):
d 196.1, 195.0, 160.8, 158.3, 157.0, 145.4, 140.9, 129.9, 129.2,
128.2, 128.1, 127.7, 126.4, 126.2, 124.3, 118.0, 114.4, 90.1, 55.6,
50.8, 40.5, 35.1, 32.4, 29.3, 27.2. IR (KBr, cm-1): 3041, 2929,
1675, 1670, 1624, 1571, 1558, 1385; MS: m/z = 502 (M++Na).
Elemental analysis for C31H29NO4: calc. C, 77.64; H, 6.10; N,
2.92. Found: C, 77.82; H, 6.01; N, 2.83.
General procedure for the synthesis of
pyrano[3,2-c]chromenoquinolines (8a–b)
3-(4-Methoxybenzoyl)-2-(4-methoxyphenylamino)-7,7-dimethyl-
4-(4-nitrophenyl)-4,6,7,8-tetrahydrochromen-5-one (6d)
◦
1
To a 5 ml dimethylformamide solution of 3-(2-halobenzoyl)-
pyrano[3,2-c]chromen-5-one (7h or 7i, 1.0 mmol), K2CO3 (0.138
g, 1.0 mmol) was added and the reaction mixture was heated to
White solid; mp 209–210 C. H NMR (300 MHz, CDCl3): d
13.05 (s, 1H), 7.93 (d, J = 8.7 Hz, 2H), 7.27 (d, J = 9.3 Hz, 2H),
7.10 (d, J = 8.7 Hz, 2H), 6.97–6.92 (m, 4H), 6.84 (d, J = 8.4 Hz,
2H), 5.05 (s, 1H), 3.85 (s, 3H), 3.84 (s, 3H), 2.53 (d, J = 17.7 Hz,
1H), 2.45 (d, J = 17.7 Hz, 1H), 2.28 (d, J = 16.2 Hz, 1H), 2.17 (d,
J = 16.2 Hz, 1H), 1.13 (s, 3H), 0.92 (s, 3H). 13C NMR (75 MHz,
CDCl3): d 195.9, 194.2, 161.5, 160.6, 157.7, 157.1, 152.7, 146.2,
133.0, 129.4, 128.5, 128.2, 124.2, 123.3, 116.4, 114.4, 113.6, 88.6,
55.5, 55.3, 50.5, 40.3, 35.6, 32.3, 29.2, 27.1. IR (KBr, cm-1):
3056, 2978, 1688, 1661, 1628, 1589, 1559, 1368; MS: m/z = 577
(M++Na). Elemental analysis for C32H30N2O7: calc. C, 69.30; H,
5.45; N, 5.05. Found: C, 69.13; H, 5.60; N, 5.12.
◦
100 C. After completion of the reaction as indicated by TLC
(about 40 min), the mixture was cooled to room temperature
and cold water was added to precipitate the product, which was
then collected by filtration and washed with cold water to afford
the pure compound 8.
The spectral and analytical data of all the compounds are
given as follows.
3-Benzoyl-2-(4-methoxyphenylamino)-7,7-dimethyl-4-(4-
nitrophenyl)-4,6,7,8-tetrahydrochromen-5-one (6a)
3-(4-Methoxybenzoyl)-2-(4-methoxyphenylamino)-7,7-dimethyl-
4-(3-nitrophenyl)-4,6,7,8-tetrahydrochromen-5-one (6e)
◦
1
White solid; mp 256–257 C. H NMR (300 MHz, CDCl3): d
13.14 (s, 1H), 7.91 (d, J = 8.7 Hz, 2H), 7.38 (d, J = 7.5 Hz, 1H),
7.34–7.25 (m, 4H), 7.06 (d, J = 7.2 Hz, 2H), 6.96–6.88 (m, 4H),
4.94 (s, 1H), 3.85 (s, 3H), 2.54 (d, J = 18.0 Hz, 1H), 2.44 (d, J =
18.0 Hz, 1H), 2.27 (d, J = 16.2 Hz, 1H), 2.15 (d, J = 16.2 Hz,
1H), 1.12 (s, 3H), 0.91 (s, 3H). 13C NMR (75 MHz, CDCl3):
d 195.8, 194.7, 161.3, 157.9, 157.2, 152.6, 146.1, 140.5, 129.4,
129.2, 128.6, 128.3, 126.0, 124.3, 123.2, 116.3, 114.4, 88.6, 55.5,
◦
1
White solid; mp 199–200 C. H NMR (300 MHz, CDCl3): d
13.02 (s, 1H), 7.89 (d, J = 7.8 Hz, 1H), 7.58 (s, 1H), 7.29–7.18
(m, 3H), 7.10–7.05 (m, 3H), 6.93 (d, J = 8.7 Hz, 2H), 6.84
(d, J = 8.4 Hz, 2H), 5.03 (s, 1H), 3.85 (s, 3H), 3.84 (s, 3H),
2.51 (s, 2H), 2.27 (d, J = 16.2 Hz, 1H), 2.16 (d, J = 16.2 Hz,
1H), 1.13 (s, 3H), 0.94 (s, 3H); 13 C NMR (75 MHz, CDCl3):
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Green Chem., 2012, 14, 447–455 | 451
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d 196.0, 193.3, 166.3, 165.4, 164.7, 163.8, 155.3, 149.1, 139.5,
135.9, 134.0, 132.4, 128.0, 124.4, 118.3, 116.4, 116.3, 114.4,
113.7, 110.2, 91.7, 55.5, 55.3, 50.6, 40.3, 35,5, 32.3, 29.6, 27.2.
IR (KBr, cm-1): 3072, 2925, 1685, 1664, 1629, 1593, 1561, 1362;
MS: m/z = 577 (M++Na). Elemental analysis for C32H30N2O7:
calc. C, 69.30; H, 5.45; N, 5.05. Found: C, 69.09; H, 5.38; N,
5.13.
d 195.3, 180.6, 164.6, 160.6, 158.4, 157.4, 146.4, 144.5, 136.9,
136.6, 129.6, 125.2, 125.1, 121.2, 120.8, 118.9, 118.3, 115.0,
112.7, 95.6, 49.3, 42.6, 36.8, 36.5, 33.8, 30.3. IR (KBr, cm-1):
3061, 2931, 1682, 1666, 1621, 1576, 1554, 1375; MS: m/z = 507
(M++Na). Elemental analysis for C28H24N2O6: calc. C, 69.41; H,
4.99; N, 5.78. Found: C, 69.63; H, 4.84; N, 5.64.
4-(4-Chlorophenyl)-3-(2-furoyl)-7,7-dimethyl-2-phenylamino-
4,6,7,8-tetrahydrochromen-5-one (6j)
4-(4-Bromophenyl)-3-(4-methoxybenzoyl)-2-(4-methoxypheny-
lamino)-7,7-dimethyl-4,6,7,8-tetrahydrochromen-5-one (6f)
◦
1
White solid; mp 199–200 C. H NMR (300 MHz, CDCl3): d
13.72 (s, 1H), 7.54 (s, 1H), 7.42–7.35 (m, 5H), 7.25–7.13 (m,
4H), 6.98 (d, J = 3.3 Hz, 1H), 6.44 (q, J = 1.5 Hz, 1H), 5.71
(s, 1H), 2.54–2.41 (m, 2H), 2.31 (d, J = 16.2 Hz, 1H), 2.23 (d,
J = 16.2 Hz, 1H), 1.12 (s, 3H), 0.92 (s, 3H). 13C NMR (75 MHz,
CDCl3): d 196.1, 178.2, 161.0, 159.1, 153.2, 144.4, 144.0, 136.8,
131.9, 129.2, 128.9, 128.4, 124.9, 122.4, 117.7, 116.6, 111.8,
89.3, 50.7, 40.3, 32.3, 29.1, 27.1. IR (KBr, cm-1): 3065, 2926,
1679, 1656, 1618, 1574, 1558, 1370; MS: m/z = 496 (M++Na).
Elemental analysis for C28H24ClNO4: calc. C, 70.96; H, 5.10; N,
2.96. Found: C, 71.14; H, 4.98; N, 2.85.
◦
1
White solid; mp 205–206 C. H NMR (300 MHz, CDCl3): d
13.03 (s, 1H), 7.60 (s, 1H), 7.13 (d, J = 8.7 Hz, 2H), 6.93–6.82
(m, 6H), 6.73–6.70 (m, 3H), 4.89 (s, 1H), 3.83 (s, 6H), 2.53–2.42
(m, 2H), 2.29–2.17 (m, 2H), 1.11 (s, 3H), 0.92 (s, 3H). 13C NMR
(125 MHz, CDCl3): 196.1, 195.0, 161.3, 133.3, 131.2, 129.4,
128.4, 124.2, 117.4, 114.4, 113.6, 90.1, 55.6, 55.4, 50.7, 40.5, 32.4,
31.0, 29.3, 27.2. IR (KBr, cm-1): 3052, 2974, 1691, 1656, 1620,
1579, 1552, 1357; MS: m/z = 610 (M++Na). Elemental analysis
for C32H30BrNO5: calc. C, 65.31; H, 5.14; N, 2.38. Found: C,
65.53; H, 5.01; N, 2.19.
3-(2-Furoyl)-7,7-dimethyl-4-(4-nitrophenyl)-2-phenylamino-
4,6,7,8-tetrahydrochromen-5-one (6g)
3-(2-Furoyl)-4-phenyl-2-phenylamino-4,6,7,8-
tetrahydrochromen-5-one (6k)
◦
◦
1
1
White solid; mp 210–211 C. H NMR (300 MHz, CDCl3):
d 13.74 (s, 1H), 8.04 (d, J = 8.7 Hz, 2H), 7.54–7.35 (m, 7H),
7.21 (t, J = 6.9 Hz, 1H), 7.01 (d, J = 3.6 Hz, 1H), 6.45 (d,
J = 1.5 Hz, 1H), 5.88 (s, 1H), 2.54 (d, J = 17.7 Hz, 1H), 2.46
(d, J = 17.7 Hz, 1H), 2.32 (d, J = 16.2 Hz, 1H), 2.23 (d, J =
16.2 Hz, 1H), 1.13 (s, 3H), 0.91 (s, 3H). 13C NMR (75 MHz,
CDCl3): d 195.9, 178.0, 161.5, 159.0, 153.4, 153.0, 146.3, 144.4,
136.6, 129.3, 128.5, 125.2, 123.5, 122.6, 116.9, 116.8, 112.0, 88.5,
50.6, 40.4, 33.1, 32.3, 29.1, 27.1. IR (KBr, cm-1): 3054, 2925,
1688, 1665, 1619, 1572, 1556, 1383; MS: m/z = 507 (M++Na).
Elemental analysis for C28H24N2O6: calc. C, 69.41; H, 4.99; N,
5.78. Found: C, 69.25; H, 5.10; N, 5.88.
White solid; mp 187–188 C. H NMR (300 MHz, CDCl3):
d 13.7 (s, 1H), 7.54 (s, 1H), 7.38–7.10 (m, 10H), 6.96 (d, J =
3.3 Hz, 1H), 6.42 (s, 1H), 5.73 (s, 1H), 2.63–2.61 (m, 2H), 2.43–
2.38 (m, 2H), 2.05–2.01 (m, 2H). 13C NMR (125 MHz, CDCl3):
d 196.4, 178.4, 162.7, 159.3, 153.2, 145.6, 144.5, 137.1, 129.3,
128.4, 127.6, 126.4, 124.9, 122.5, 119.6, 116.6, 111.8, 89.8, 36.9,
32.8, 26.8, 20.1. IR (KBr, cm-1): 3071, 2923, 1672, 1654, 1620,
1581, 1556, 1361; MS: m/z = 434 (M++Na). Elemental analysis
for C26H21NO4: calc. C, 75.90; H, 5.14; N, 3.40. Found: C, 75.75;
H, 5.28; N, 3.48.
7,7-Dimethyl-4-(3-nitrophenyl)-2-phenylamino-3-(2-thienoyl)-
4,6,7,8-tetrahydrochromen-5-one (6l)
3-(2-Furoyl)-7,7-dimethyl-4-(3-nitrophenyl)-2-phenylamino-
4,6,7,8-tetrahydrochromen-5-one (6h)
◦
1
White solid; mp 217–218 C. H NMR (300 MHz, CDCl3): d
13.43 (s, 1H), 7.99–7.96 (m, 2H), 7.53–7.32 (m, 8H), 7.21 (t, J =
6.6 Hz, 1H), 7.03 (t, J = 4.2 Hz, 1H), 5.54 (s, 1H), 2.55 (d, J =
18.6 Hz, 1H), 2.48 (d, J = 18.6 Hz, 1H), 2.33 (d, J = 16.5 Hz, 1H),
2.24 (d, J = 16.5 Hz, 1H), 1.13 (s, 3H), 0.92 (s, 3H). 13C NMR
(75 MHz, CDCl3): d 195.9, 184.3, 161.8, 158.8, 148.3, 146.9,
143.5, 136.4, 133.9, 130.0, 129.2, 128.8, 127.3, 125.2, 122.6,
122.3, 121.7, 116.8, 88.8, 50.5, 40.3, 34.3, 32.3, 29.1, 27.1. IR
(KBr, cm-1): 3073, 2952, 1689, 1670, 1619, 1591, 1564, 1381;
MS: m/z = 523 (M++Na). Elemental analysis for C28H24N2O5S:
calc. C, 67.18; H, 4.83; N, 5.60. Found: C, 67.26; H, 4.63; N,
5.39.
◦
1
White solid; mp 201–202 C. H NMR (300 MHz, CDCl3): d
13.71 (s, 1H), 8.14 (s, 1H), 7.94 (d, J = 7.5 Hz, 1H), 7.65–7.58
(m, 2H), 7.43–7.31 (m, 5H), 7.21 (t, J = 6.9 Hz, 1H), 7.02 (d,
J = 3.6 Hz, 1H), 6.45 (s, 1H), 5.89 (s, 1H), 2.52 (s, 2H), 2.32 (d,
J = 16.2 Hz, 1H), 2.23 (d, J = 16.2 Hz, 1H), 1.13 (s, 3H), 0.92
(s, 3H). 13C NMR (75 MHz, CDCl3): d 196.0, 178.1, 161.3,
158.9, 153.5, 148.1, 147.8, 144.4, 136.6, 134.0, 129.2, 128.9,
125.2, 122.7, 122.7, 121.5, 116.9, 112.0, 88.7, 50.6, 40.3, 33.0,
32.3, 29.1, 27.1. IR (KBr, cm-1): 3054, 2976, 1686, 1666, 1624,
1583, 1551, 1388; MS: m/z = 507 (M++Na). Elemental analysis
for C28H24N2O6: calc. C, 69.41; H, 4.99; N, 5.78. Found: C, 69.19;
H, 5.10; N, 5.87.
4-(2,4-Dichlorophenyl)-7,7-dimethyl-2-phenylamino-3-(2-
thienoyl)-4,6,7,8-tetrahydrochromen-5-one (6m)
3-(2-Furoyl)-7,7-dimethyl-4-(2-nitrophenyl)-2-phenylamino-
4,6,7,8-tetrahydrochromen-5-one (6i)
◦
1
White solid; mp 155–156 C. H NMR (300 MHz, CDCl3): d
13.02 (s, 1H), 7.41–7.31 (m, 6H), 7.21–7.16 (m, 2H), 7.04 (t, J =
4.2 Hz, 1H), 6.87 (m, 1H), 6.74 (d, J = 8.7 Hz, 1H), 5.50 (s, 1H),
2.55 (d, J = 17.4 Hz, 1H), 2.47 (d, J = 17.4 Hz, 1H), 2.28 (d, J =
16.5 Hz, 1H), 2.19 (d, J = 16.5 Hz, 1H), 1.14 (s, 3H), 1.01 (s,
3H). 13C NMR (75 MHz, CDCl3): d 196.2, 186.1, 161.4, 157.9,
◦
1
White solid; mp 159–160 C. H NMR (300 MHz, CDCl3): d
13.25 (s, 1H), 7.52–7.30 (m, 8H), 7.20–7.15 (m, 2H), 6.91 (d,
J = 3.3 Hz, 1H), 6.40 (s, 1H), 6.18 (s, 1H), 2.49 (br, 2H), 2.26
(br, 2H), 1.11 (s, 3H), 0.98 (s, 3H). 13C NMR (75 MHz, CDCl3):
452 | Green Chem., 2012, 14, 447–455
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142.7, 138.7, 136.6, 133.7, 133.3, 132.6, 130.1, 129.2, 128.7,
127.9, 126.8, 126.2, 125.0, 122.6, 114.0, 88.4, 50.6, 40.3, 35.1,
32.1, 29.2, 27.3. IR (KBr, cm-1): 3056, 2943, 1684, 1671, 1621,
1586, 1561, 1380; MS: m/z = 546 (M++Na). Elemental analysis
for C28H23Cl2NO3S: calc. C, 64.12; H, 4.42; N, 2.67. Found: C,
64.29; H, 4.27; N, 2.59.
(M++Na). Elemental analysis for C28H21ClN2O5: calc. C, 67.14;
H, 4.23; N, 5.59. Found: C, 67.02; H, 4.45; N, 5.50.
3-(2-Chlorobenzoyl)-4-(4-methoxyphenyl)-2-phenylamino-
4,6,7,8-tetrahydrochromen-5-one (6r)
◦
1
White solid; mp 190–192 C. H NMR (300 MHz, CDCl3): d
13.05 (s, 1H), 7.40–7.25 (m, 7H), 6.68–6.58 (m, 6H), 4.43 (s, 1H),
4-(4-Bromophenyl)-7,7-dimethyl-2-phenylamino-3-(2-thienoyl)-
4,6,7,8-tetrahydrochromen-5-one (6n)
3.72 (s, 3H), 2.64 (br, 2H), 2.33 (br, 2H), 2.06–1.90 (m, 2H). 13
C
NMR (75 MHz, CDCl3): d 193.9, 186.4, 161.5, 157.9, 136.8,
129.6, 129.2, 126.4, 124.9, 122.4, 119.2, 113.2, 86.6, 55.1, 36.8,
29.6, 26.7, 20.1. IR (KBr, cm-1): 3067, 2935, 1685, 1671, 1620,
1595, 1557; MS: m/z = 508 (M++Na). Elemental analysis for
C29H24ClNO4: calc. C, 71.67; H, 4.98; N, 2.88. Found: C, 71.85;
H, 4.89; N, 2.78.
◦
1
White solid; mp 207–208 C. H NMR (300 MHz, CDCl3):
d 13.55 (s, 1H), 7.45 (d, J = 1.5 Hz, 1H), 7.39–7.32 (m, 7H),
7.21–7.12 (m, 3H), 7.00 (t, J = 4.2 Hz, 1H), 5.40 (s, 1H), 2.53–
2.39 (m, 2H), 2.34–2.22 (m, 2H), 1.11 (s, 3H), 0.91 (s, 3H). 13
C
NMR (75 MHz, CDCl3): d 196.1, 183.8, 161.5, 159.2, 144.1,
143.7, 136.7, 131.6, 130.1, 129.2, 129.1, 127.4, 125.0, 122.4,
120.4, 117.8, 89.2, 50.7, 40.3, 33.5, 32.3, 29.2, 27.0. IR (KBr,
cm-1): 3035, 2942, 1687, 1670, 1629, 1592, 1563; MS: m/z = 556
(M++Na). Elemental analysis for C28H24BrNO3S: calc. C, 62.92;
H, 4.53; N, 2.62. Found: C, 63.13; H, 4.42; N, 2.51.
4-(4-Chlorophenyl)-3-(2-furoyl)-2-phenylamino-4H-pyrano[3,2-
c]chromen-5-one (7a)
◦
1
White solid; mp 232–233 C. H NMR (300 MHz, CDCl3): d
13.62 (s, 1H), 7.57–7.17 (m, 14H), 7.07 (d, J = 3.0 Hz, 1H), 6.47
(d, J = 1.8 Hz, 1H), 5.96 (s, 1H). 13C NMR (75 MHz, CDCl3):
d 178.2, 159.1, 158.4, 153.2, 152.8, 152.6, 144.6, 142.7, 141.5,
136.2, 132.7, 132.4, 129.3, 129.2, 128.6, 125.9, 124.5, 123.9,
122.3, 117.2, 116.9, 112.0, 108.5, 88.5, 34.2. IR (KBr, cm-1):
3056, 2976, 1751, 1739, 1690, 1606, MS: m/z = 518 (M++Na).
Elemental analysis for C29H18ClNO5: calc. C, 70.24; H, 3.66; N,
2.82. Found: C, 70.43; H, 3.49; N, 2.72.
7,7-dimethyl-4-(4-Methoxyphenyl)-2-phenylamino-3-(2-
thienoyl)-4,6,7,8-tetrahydrochromen-5-one (6o)
◦
1
White solid; mp 175–176 C. H NMR (300 MHz, CDCl3): d
13.59 (s, 1H), 7.44 (d, J = 5.1 Hz, 1H), 7.38–7.35 (m, 5H), 7.20–
7.17 (m, 3H), 6.98 (t, J = 4.2 Hz, 1H), 6.77–6.74 (m, 2H), 5.37 (s,
1H), 3.73 (s, 3H), 2.51–2.39 (m, 2H), 2.33–2.22 (m, 2H), 1.10 (s,
3H), 0.90 (s, 3H). 13C NMR (75 MHz, CDCl3): d 196.3, 183.8,
161.1, 159.4, 158.0, 144.4, 136.9, 130.0, 129.5, 129.2, 128.3,
127.5, 124.8, 122.4, 118.7, 113.9, 89.9, 55.1, 50.8, 40.3, 33.0,
32.3, 29.2, 27.0. IR (KBr, cm-1): 3059, 2927, 1685, 1673, 1620,
1581, 1562, 1383; MS: m/z = 508 (M++Na). Elemental analysis
for C29H27NO4S: calc. C, 71.73; H, 5.60; N, 2.88. Found: C,
71.56; H, 5.81; N, 3.01.
3-(2-Furoyl)-4-phenyl-2-phenylamino-4H-pyrano[3,2-c]chromen-
5-one (7b)
◦
1
White solid; mp 215–216 C. H NMR (300 MHz, CDCl3): d
13.64 (s, 1H), 7.58–7.43 (m, 9H), 7.33–7.21 (m, 5H), 7.16–7.05
(m, 2H), 6.45 (t, J = 1.8 Hz, 1H), 5.97 (s, 1H). 13C NMR (75 MHz,
CDCl3): d 178.3, 160.7, 158.6, 153.2, 152.8, 152.5, 144.6, 144.1,
136.3, 132.2, 129.3, 128.5, 127.7, 127.0, 125.8, 124.4, 123.9,
122.2, 117.0, 116.8, 113.5, 111.8, 109.1, 88.9, 34.7. IR (KBr,
cm-1): 3076, 2939, 1755, 1742, 1686, 1609, 1571; MS: m/z = 484
(M++Na). Elemental analysis for C29H19NO5: calc. C, 75.48; H,
4.15; N, 3.04. Found: C, 75.31; H, 4.33; N, 2.91.
4-(4-Bromophenyl)-3-(2-chlorobenzoyl)-7,7-dimethyl-2-
phenylamino-4,6,7,8-tetrahydrochromen-5-one (6p)
◦
1
White solid; mp 235–236 C. H NMR (300 MHz, CDCl3): d
13.08 (s, 1H), 7.41–7.01 (m, 10H), 6.62–6.44 (m, 3H), 4.44 (s,
1H), 2.56 (d, J = 18.0 Hz, 1H), 2.46 (d, J = 18.0 Hz, 1H), 2.26 (d,
J = 16.5 Hz, 1H), 2.14 (d, J = 18.0 Hz, 1H), 1.15 (s, 3H), 0.90 (s,
3H). 13C NMR (75 MHz, CDCl3): d 195.7, 192.4, 160.3, 157.9,
136.5, 130.8, 129.8, 129.2, 126.6, 125.1, 122.5, 120.1, 117.1,
90.8, 50.5, 40.3, 34.7, 32.2, 29.2, 27.0. IR (KBr, cm-1): 3053,
2941, 1684, 1670, 1627, 1593, 1561; MS: m/z = 584 (M++Na).
Elemental analysis for C30H25BrClNO3: calc. C, 64.01; H, 4.48;
N, 2.49. Found: C, 64.12; H, 4.29; N, 2.57.
4-(3-Nitrophenyl)-2-phenylamino-3-(2-thienoyl)-4H-pyrano[3,2-
c]chromen-5-one (7c)
◦
1
White solid; mp 203–204 C. H NMR (300 MHz, CDCl3): d
13.33 (s, 1H), 8.12 (s, 1H), 8.02 (d, J = 8.1 Hz, 1H), 7.68 (d, J =
7.8 Hz, 1H), 7.57–7.29 (m, 12H), 7.06 (t, J = 4.2 Hz, 1H), 5.74
(s, 1H). 13C NMR (75 MHz, CDCl3): d 184.5, 160.5, 158.2,
153.5, 152.6, 148.4, 145.5, 143.0, 135.8, 134.1, 132.8, 130.3,
129.4, 129.3, 129.0, 127.4, 126.2, 124.7, 124.1, 122.6, 122.5,
122.2, 116.9, 113.0, 107.4, 88.1, 36.3. IR (KBr, cm-1): 3075,
2924, 1752, 1741, 1681, 1601, 1582; MS: m/z = 545 (M++Na).
Elemental analysis for C29H18N2O6S: calc. C, 66.66; H, 3.47; N,
5.36. Found: C, 66.78; H, 3.61; N, 5.19.
3-(2-Chlorobenzoyl)-4-(3-nitrophenyl)-2-phenylamino-4,6,7,8-
tetrahydrochromen-5-one (6q)
◦
1
White solid; mp 240–241 C. H NMR (300 MHz, CDCl3): d
13.09 (s, 1H), 7.93 (d, J = 7.2 Hz, 1H), 7.58–6.91 (m, 12H), 4.66
(s, 1H), 2.70–2.66 (m, 2H), 2.34–2.32 (m, 2H), 2.10–1.97 (m,
2H). 13C NMR (75 MHz, CDCl3): d 195.8, 192.3, 162.4, 157.6,
147.8, 136.2, 134.6, 130.1, 129.2, 128.5, 126.6, 125.4, 123.1,
122.7, 121.4, 117.5, 90.2, 36.6, 35.3, 26.7, 20.0. IR (KBr, cm-1):
3060, 2931, 1684, 1673, 1621, 1593, 1555, 1376; MS: m/z = 523
4-(4-Fluorophenyl)-2-phenylamino-3-(2-thienoyl)-4H-
pyrano[3,2-c]chromen-5-one (7d)
◦
1
White solid; mp 203–204 C. H NMR (300 MHz, CDCl3): d
13.45 (s, 1H), 7.56–7.23 (m, 13H), 7.04–6.92 (m, 3H), 5.61 (s,
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1H). 13C NMR (75 MHz, CDCl3): d 184.2, 160.7, 158.6, 153.1,
152.5, 143.7, 139.2, 136.1, 132.4, 130.4, 129.4, 129.3, 129.1,
127.5, 125.9, 124.6, 123.9, 122.3, 116.9, 115.8, 115.5, 113.3,
108.8, 88.8, 35.4. IR (KBr, cm-1): 3054, 2971, 1750, 1734, 1684,
1610, 1591; MS: m/z = 518 (M++Na). Elemental analysis for
C29H18FN4S: calc. C, 70.29; H, 3.66; N, 2.83. Found: C, 70.10;
H, 3.54; N, 3.04.
calc. C, 63.66; H, 3.27; N, 2.39. Found: C, 63.75; H, 3.04; N,
2.50.
3-(2-Chlorobenzoyl)-4-(4-nitrophenyl)-2-phenylamino-4H-
pyrano[3,2-c]chromen-5-one (7i)
◦
1
White solid; mp 265–266 C. H NMR (300 MHz, CDCl3): d
13.04 (s, 1H), 7.95 (d, J = 8.4 Hz, 2H), 7.61–7.25 (m, 12H), 7.04
(m, 2H), 6.41 (s, 1H), 4.86 (s, 1H). 13C NMR (75 MHz, CDCl3):
192.4, 160.0, 157.2, 152.8, 152.7, 146.7, 135.5, 132.9, 130.3,
129.4, 126.8, 126.4, 124.7, 124.1, 123.2, 122.5, 117.0, 112.9,
107.0, 89.2, 36.9. IR (KBr, cm-1): 2967, 1746, 1725, 1683, 1599;
MS: m/z = 573 (M++Na). Elemental analysis for C31H19ClN2O6:
calc. C, 67.58; H, 3.48; N, 5.08. Found: C, 67.77; H, 3.24; N, 5.21.
3-(4-Methoxybenzoyl)-2-phenylamino-4-p-tolyl-4H-pyrano[3,2-
c]chromen-5-one (7e)
◦
1
White solid; mp 187–188 C. H NMR (300 MHz, CDCl3):
d 12.99 (s, 1H), 7.60–7.47 (m, 6H), 7.32–7.21 (m, 5H), 6.98–
6.85 (m, 6H), 5.11 (s, 1H), 3.86 (s, 3H), 2.24 (s, 3H). 13C
NMR (75 MHz, CDCl3): d 194.8, 160.8, 157.3, 152.9, 152.5,
140.9, 136.6, 136.5, 132.8, 132.1, 131.3, 129.2, 129.1, 128.5,
127.6, 125.5, 124.4, 123.6, 122.3, 116.8, 113.6, 113.5, 109.1, 89.8,
55.3, 36.6, 21.0. IR (KBr, cm-1): 3065, 2936, 1753, 1738, 1680,
1608, 1578; MS: m/z = 538 (M++Na). Elemental analysis for
C33H25NO5: calc. C, 76.88; H, 4.89; N, 2.72. Found: C, 77.05; H,
4.75; N, 2.63.
7-(4-Bromophenyl)-13-phenyl-7,13-dihydro-5,14-dioxa-13-
azabenzo[a]naphthacene-6,8-dione (8a)
White solid; mp >300 ◦C. 1H NMR (300 MHz, CDCl3): 8.26 (d,
J = 7.5 Hz, 1H), 8.17 (d, J = 7.5 Hz, 1H), 7.67–7.35 (m, 13H),
7.17 (d, J = 7.5 Hz, 1H), 6.74 (d, J = 8.4 Hz, 1H), 5.27 (s, 1H).
13C NMR (75 MHz, CDCl3): 174.4, 160.4, 156.8, 156.7, 154.2,
152.6, 144.8, 131.4, 131.2, 130.8, 130.2. 129.1, 128.8, 124.5,
122.7, 122.5, 122.2, 116.3, 110.8, 105.9, 34.8. IR (KBr, cm-1):
3091, 2926, 1743, 1668, 1618, 1591, 1541, 1366; MS: m/z = 570
(M++Na). Elemental analysis for C31H18BrNO4: calc. C, 67.90;
H, 3.31; N, 2.55. Found: C, 68.11; H, 3.21; N, 2.40.
3-(4-Methoxybenzoyl)-4-(3-nitrophenyl)-2-phenylamino-4H-
pyrano[3,2-c]chromen-5-one (7f)
◦
1
White solid; mp 210–212 C. H NMR (300 MHz, CDCl3): d
12.97 (s, 1H), 7.95 (d, J = 7.2 Hz, 1H), 7.71 (s, 1H), 7.62–7.47
(m, 7H), 7.34–7.24 (m, 5H), 7.14 (d, J = 8.4 Hz, 1H), 6.87 (d,
J = 8.4 Hz, 2H), 5.27 (s, 1H), 3.87 (s, 3H). 13C NMR (75 MHz,
CDCl3 + DMSO-d6): d 193.6, 160.0, 159.2, 155.6, 152.3, 151.6,
146.7, 145.0, 135.1, 133.3, 132.0, 131.6, 128.4, 128.3, 127.1,
124.9, 123.9, 122.7, 122.0, 121.6, 120.8, 115.9, 112.7, 112.0,
105.7, 87.8, 54.4, 28.5. IR (KBr, cm-1): 3067, 2934, 1757, 1738,
1681, 1601, 1582; MS: m/z = 569 (M++Na). Elemental analysis
for C32H22N2O7: calc. C, 70.32; H, 4.06; N, 5.13. Found: C, 70.14;
H, 4.19; N, 5.26.
7-(4-Nitrophenyl)-13-phenyl-7,13-dihydro-5,14-dioxa-13-aza-
benzo[a]naphthacene-6,8-dione (8b)
White solid; mp >300 ◦C. 1H NMR (300 MHz, CDCl3): d 8.28
(d, J = 7.5 Hz, 1H), 8.19 (d, J = 7.5 Hz, 1H), 8.12–8.09 (m, 2H),
7.67–7.41 (m, 11H), 7.14 (d, J = 6.9 Hz, 1H), 6.76 (d, J = 8.4 Hz,
1H), 5.40 (s, 1H). 13C NMR (75 MHz, CDCl3): d 173.9, 169.1,
159.4, 150.8, 147.6, 146.2, 139.5, 137.4, 135.4, 134.4, 129.4,
125.7, 124.1, 123.3, 122.2, 118.4, 117.8, 116.0, 115.8, 108.6, 36.9.
IR (KBr, cm-1): 3063, 2954, 1749, 1663, 1610, 1581, 1550, 1363;
MS: m/z = 537 (M++23). Elemental analysis for C31H18N2O6:
calc. C, 72.37; H, 3.53; N, 5.44. Found: C, 72.42; H, 3.31; N,
5.63.
4-(4-Chloro-3-fluorophenyl)-3-(4-methoxybenzoyl)-2-
phenylamino-4H-pyrano[3,2-c]chromen-5-one (7g)
◦
1
White solid; mp 226–227 C. H NMR (300 MHz, CDCl3): d
12.95 (s, 1H), 7.59–7.43 (m, 6H), 7.34–7.12 (m, 6H), 6.88 (d, J =
8.1 Hz, 2H), 6.78–6.70 (m, 2H), 5.14 (s, 1H), 3.87 (s, 3H). 13C
NMR (75 MHz, CDCl3): d 194.8, 161.0, 160.4, 157.1, 153.2,
152.6, 144.8, 144.7, 136.2, 132.6, 130.2, 129.3, 128.3, 125.8,
124.6, 124.2, 123.8, 122.4, 117.0, 116.2, 115.9, 113.7, 113.2,
111.2, 107.6, 88.7, 55.4, 36.7. IR (KBr, cm-1): 3089, 2954, 1743,
1745, 1689, 1603, 1582; MS: m/z = 576 (M++Na). Elemental
analysis for C32H21ClFNO5: calc. C, 69.38; H, 3.82; N, 2.53.
Found: C, 69.20; H, 3.98; N, 2.61.
Acknowledgements
We gratefully acknowledge the generous financial support from
the Council of Scientific and Industrial Research (CSIR) and
the Department of Science and Technology (DST), New Delhi.
G. C. N. and S. S. are thankful to CSIR, New Delhi for senior
research fellowship.
Notes and references
4-(4-Bromophenyl)-3-(2-chlorobenzoyl)-2-phenylamino-4H-
pyrano[3,2-c]chromen-5-one (7h)
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White solid; mp 202–204 C. H NMR (300 MHz, CDCl3): d
13.0 (s, 1H), 7.59–7.51 (m, 6H), 7.31–7.03 (m, 8H), 6.76–6.46
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160.1, 157.3, 152.5, 152.4, 135.8, 132.5, 131.1, 130.1, 129.3,
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454 | Green Chem., 2012, 14, 447–455
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