Catalyst-free microwave-assisted arylglyoxal-based multicomponent reactions for the synthesis of fused pyrans

Article abstract of DOI:10.1039/c5ra25536h

A series of functionalized pyrans fused with quinolones, naphthoquinones, coumarins and pyrones have been synthesized using three component reactions of arylglyoxal monohydrate, malononitrile, and a wide range of cyclic 1,3-dicarbonyls under microwave irr

Full text of DOI:10.1039/c5ra25536h

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Catalyst-free microwave-assisted arylglyoxal-
based multicomponent reactions for the synthesis
Cite this: RSC Adv., 2016, 6, 24464
of fused pyrans†
*
Richa Mishra and Lokman H. Choudhury
A series of functionalized pyrans fused with quinolones, naphthoquinones, coumarins and pyrones have
been synthesized using three component reactions of arylglyoxal monohydrate, malononitrile, and
a wide range of cyclic 1,3-dicarbonyls under microwave irradiation. This method is a simple and
straightforward method for the easy access of fused and functionalized pyrans tethered with an aroyl
group without involving any catalyst and column chromatographic purifications.
Received 1st December 2015
Accepted 14th February 2016
DOI: 10.1039/c5ra25536h
www.rsc.org/advances
Fig. 1. Considering their widespread applications there is
a continuing effort to synthesize either new fused pyrans or to
develop new methodology for their synthesis.11 In the literature,
Introduction
Microwave-assisted multicomponent reactions are one of the
preferred reaction strategies in organic synthesis.1 Due to the
short reaction time and low energy consumption in microwave
heating as compared to the conventional heating process,
microwave heating has gained tremendous popularity among
organic, medicinal and material chemists.2 In addition to these,
performing reactions under catalyst-free conditions, provide
additional benets, such as no toxicity and cost for the catalyst.
Considering these virtues, in recent times microwave-assisted
catalyst-free MCRs have gained considerable interest in
organic synthesis.3
Pyrans fused with other cyclic molecules are abundant in
various natural and bioactive synthetic products.4 Pyr-
anoquinoline (pyran fused with quinoline) core is found in
many alkaloids such as indersine, oricine, veprisine, and
(+)-orixalone D.5 These bioactive alkaloids and their derivatives
exhibit wide range of pharmacological activities such as anti-
allergic, anti inammatory, psychotropic, and estrogenic activ-
ities.6 Similarly, pyrans fused with naphthoquinone derivatives
such as kalafungin and lapachone show anticancer, anti-
inammatory and antibacterial, activities.7 Likewise, pyrans
fused with coumarins (pyranocoumarins) possess broad phar-
macological activities such as anticancer, anti-hepatitis B virus,
anti HIV-1, anti-inammatory, antimicrobial, and anti-
proliferative activity etc.8 In addition, they are used as photo-
active drugs for skin disorders.9 Pyranocoumarins are also used
as anti-hyperglycemic and anti-dyslipidemic agents.10 Struc-
tures of a few representative bioactive fused pyrans are shown in
a few methods are known for the synthesis of coumarin fused
pyrans having benzoyl substituent using multicomponent
approach using various catalysts such as NH4H2PO4,12 graphene
oxide13 etc. Although these methods are useful for the synthesis
of coumarin fused pyrans still these methods are limited only
towards the synthesis of pyranocoumarins whereas we were
looking for a versatile and greener methodology for the
construction of diverse functionalized pyrans fused with qui-
nolone, naphthoquinone, pyrone as well as coumarins.
In continuation of our work on arylglyoxal-based MCRs, so
far we have shown the three component reactions of arylglyoxal
with cyclic 1,3 dicarbonyls and various 1,3-binucleophiles to
access a verity of functionalized ve membered heterocycles.3a,14
In this paper we are reporting a three component reaction
involving arylglyoxal monohydrate, malononitrile, and cyclic
1,3-dicarbonyls such as 4-hydroxy-1-methyl-2(1H)-quinolone, 2-
hydroxy naphthoquinone, and 4-hydroxyl coumarins as shown
in Scheme 1.
Results and discussion
For our initial study, the reaction of phenylglyoxal monohydrate
(1.0 mmol), malononitrile (1.0 mmol) and 4-hydroxy-1-methyl-
2(1H)-quinolone (1.0 mmol) was chosen as model reaction. This
Department of Chemistry, Indian Institute of Technology Patna, Patna-801103, India.
E-mail: lokman@iitp.ac.in; lokman.iitp@gmail.com; Tel: +91-6123028038
† Electronic supplementary information (ESI) available. CCDC 1450244. For ESI
and crystallographic data in CIF or other electronic format see DOI:
10.1039/c5ra25536h
Fig. 1 Structures of some biologically active pyrans fused with quin-
oline, naphthoquinone, and coumarins.
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Table 1 MW-assisted three component synthesis of quinolone fused
pyrans
Scheme 1 Synthesis of fused and functionalized pyrans using three
component reactions.
Entry
1
Product
Yield
90
Melting point
combination in water as reaction medium provided only trace
amount of the desired three component product 1a aer 14
hours of stirring at room temperature. Interestingly, when the
same reaction was tested in 2 ml ethanol–water (1 : 1 v/v) mix
solvent at room temperature for the same duration, 15% yield
was observed. Aer having this encouraging result, compound
1a was initially characterized by IR, 1H and 13C NMR and by
elemental analysis. Next, we tried to optimize the reaction
conditions by varying the solvents and reaction temperatures.
Interestingly, under the reux conditions and ethanol as
solvent, the model reaction provided 60% yield of the desired
quinolone fused pyran within 12 hours. To our surprise, when
we tried the reaction under microwave irradiation using the
same solvent ethanol for 10 minutes the desired product
2-amino-4-benzoyl-6-methyl-5-oxo-5,6-dihydro-4H-pyrano[3,2c]
quinoline-3-carbonitrile was obtained in very good yield (90%).
Increasing reaction time under the same MW heating condi-
tions did not provide any advantage in terms of yield obtained.
Thus ethanol as solvent, and 10 minutes MW heating at 110 ꢀC
of the reaction mixture was considered as the optimized
conditions. With this optimised conditions in hand,15 we
turned our attention to investigate the scope and general
applicability of this procedure by varying the scope of phenyl-
glyoxal monohydrate. Phenylglyoxals tethered with both elec-
tron donating and electron withdrawing groups provided the
corresponding fused pyrans (1b–1e) in very good yields under
the optimized conditions and the results are summarized in
Table 1. Similar, to phenylglyoxals 6-methoxy naphthylglyoxal
also provided corresponding fused pyran (1f) in good yield. All
these compounds were fully characterized by IR, 1H, & 13C NMR
as well as by elemental analysis. For unambiguous determina-
tion of the structure of these products single crystal XRD for one
of the quinolone fused pyran (1c) was recorded as shown in
Fig. 2.
264–266
2
3
4
88
85
79
282–284
264–266
263–265
5
6
93
92
277–280
258–260
In order to explore the versatility and scope of this meth-?
?odology, next we wanted to explore 2-hydroxy-1,4-naphtho-?
?quinone for the preparation of naphthoquinone-fused pyrans
using similar reaction strategy. When phenylglyoxal mono-
hydrate was reacted with malononitrile and 2-hydroxy-1,4-
naphthoquinone under the microwave irradiation, the corre-
sponding fused pyran 2a was obtained in very good yield. Next,
variability of arylglyoxal was tested and in this case also it was
observed that arylglyoxals tethered with electron donating or
withdrawing groups as well as 6-methoxy naphthylglyoxal
monohydrate provided the corresponding naphthoquinone
fused pyran in good yield and the results are summarized in
Table 2.
Fig. 2 Crystal structure of 1c (CCDC 1450244†).
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Table 2 MW-assisted three component synthesis of naphthoquinone Table 3 MW-assisted three component synthesis of coumarin and
fused pyrans
pyrone fused pyrans
Entry
1
Product
Yield
79
Melting point
Entry
1
Product
Yield
91
Melting point
266–268
233–245
2
3
75
77
262–264
251–253
2
3
88
79
234–236
254–256
4
5
70
85
248–250
268–270
4
5
87
91
246–248
238–240
Next, this methodology was extended to other cyclic 1,3-
dicarbonyls such as 4-hydroxy coumarin and 4-hydroxy-6-
methyl-2H-pyran-2-one. Interestingly, in these cases also the
corresponding fused pyrans were obtained in good yields and
the results are summarized in Table 3.
It is noteworthy to mention that this methodology works for
a diverse cyclic 1,3-dicarbonyls and arylglyoxals and corre-
sponding fused pyrans tethered with benzoyl group can be
accessed in good yields within short time without using any
catalyst. All the products were fully characterized by IR, 1H
NMR, 13C NMR and by elemental analysis.
Scheme 2 Plausible mechanism for the synthesis of fused pyrans.
undergoes tautomerization and nally desired fused pyran D is
formed (Scheme 2).
Mechanistically we believe that this reaction goes via
a Knoevenagel condensation of arylglyoxal monohydrate with
malononitrile to provide the corresponding electron decient
alkene A. Then 1,4-addition of cyclic 1,3-dicarbonyls to this
alkene takes place to provide intermediate B and followed by
intramolecular cyclization to provide intermediate C which
Conclusions
In conclusion, we have developed a straight forward one-pot
three component reaction for the easy access of diverse fused
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pyrans tethered with amino, nitrile and benzoyl group. Due to CDCl3): d ¼ 8.12 (d, J ¼ 7.2 Hz, 2H, ArH), 7.99 (dd, J ¼ 8.0, 1.4
the presence of these reactive functional groups on the Hz, 1H, ArH), 7.75 (t, J ¼ 7.75 Hz, 1H, ArH), 7.62 (d, J ¼ 8.5 Hz,
synthesized fused pyrans, it is expected that further cyclization/ 1H, ArH), 7.44 (bs, 2H, –NH2), 7.43 (t, 1H, ArH), 7.11 (d, J ¼ 7.08
modication of these molecules will be possible to synthesize Hz, 2H, ArH), 5.34 (s, 1H, CH), 3.89 (s, 3H, OCH3), 3.56 (s, 3H,
new polycyclic heterocycles. The salient features of this meth- NCH3) ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3): d ¼ 179.1,
odology are: short reaction time, avoids column chromato- 163.6, 160.1, 160.1, 151.2, 138.6, 131.8, 131.4, 128.7, 122.4,
graphic purication and applicable to a wide range of 121.9, 119.2, 115.1, 113.9, 112.6, 107.1, 55.6, 52.2, 37.2, 29.2
substrates.
ppm; anal. calcd for C22H17N3O4 (387.39): C, 68.21; H, 4.42; N,
10.85; found: C, 68.23; H, 4.43; N, 10.89.
2-Amino-4-(4-uoro-benzoyl)-6-methyl-5-oxo-5,6-dihydro-4H-
pyrano[3,2-c]quinoline-3-carbonitrile (1c). White solid; mp 264–
266 ꢀC; IR (ATR) 3779, 3435, 3259, 2188, 1825, 1654, 1590, 1418,
Experimental
General information
1
1367, 1268, 1217, 1201, 1173, 1043, cmꢁ1; H NMR (400 MHz,
All starting materials were purchased from either Sigma Aldrich
or Alfa Aesar and used without further purication. Microwave
irradiation was carried out with Initiator 2.5 Microwave
Synthesizers from Biotage, Uppsala, Sweden. NMR spectra were
recorded on Bruker 400 or 500 MHz for 1H and 100 or 125 MHz
for 13C in CDCl3/DMSO-d6, chemical shi values were reported
in d values ppm downeld from tetra methyl silane. Infrared
spectra were recorded on a Shimadzu FTIR spectrometer. CHN
analyses were carried out using Elementar, Vario micro cube
elemental analyzer and melting points were recorded using SRS
EZ-Melt automated melting point apparatus by capillary
methods and uncorrected.
Typical experimental procedure for the synthesis of (1a).
Typical experimental procedure for the preparation of 1a:
a mixture of phenylglyoxal monohydrate (1.0 mmol) and
malononitrile (1.0 mmol) in ethanol (2 ml) was stirred at room
temperature for 5 minutes. To this mixture 4-hydroxy-1-methyl-
2(1H)-quinolone (1 mmol) was added and the resultant mixture
was kept under microwave under sealed and stirring conditions
for 10 minutes, keeping the temperature at 110 ꢀC. Aer
completion of the reaction, the reaction mixture was cooled to
room temperature and solid product was separated by just
ltration and puried by recrystallization from mixture of
ethanol and THF. Using similar procedure all other products
were prepared.
DMSO-d6 + CDCl3): d ¼ 8.25–8.22 (m, 2H, ArH), 7.98 (dd, J ¼
7.96, 1.36 Hz, 1H, ArH), 7.74 (t, J ¼ 7.16 Hz, 1H, ArH), 7.62 (d, J ¼
8.52 Hz, 1H, ArH), 7.51 (bs, 2H, NH2), 7.4 (t, J ¼ 8.76 Hz, 3H,
ArH), 5.40 (s, 1H, CH), 3.56 (s, 3H, NCH3) ppm; 13C NMR (100
MHz, DMSO-d6 + CDCl3): d ¼ 197.7, 166.6, 164.1, 160.1, 151.2,
138.1, 132.8, 132.7, 132.1, 132.0, 131.9, 122.4, 121.8, 119.1,
115.9, 115.2, 112.5, 106.0, 51.7, 40.1, 37.6, 29.3 ppm; anal. calcd
for C21H14FN3O3 (375.35): C, 67.20; H, 3.76; N, 11.19; found: C,
67.19; H, 3.74; N, 11.22.
2-Amino-6-methyl-4-(4-nitro-benzoyl)-5-oxo-5,6-dihydro-4H-
pyrano[3,2-c]quinoline-3-carbonitrile (1d). Brown solid; mp
263–265 ꢀC; IR (ATR) 3075, 2748, 2330, 1947, 1883, 1644, 1593,
1
1540, 1454, 1335, 1238, 1113, 1039, cmꢁ1; H NMR (400 MHz,
DMSO-d6 + CDCl3): d ¼ 8.41–8.35 (m, 4H, ArH), 8.01 (dd, J ¼
8.00, 1.36 Hz, 1H, ArH), 7.73–7.71 (m, 1H, ArH), 7.59 (d, J ¼ 8.52
Hz, 1H, ArH), 7.52 (s, 2H, NH2), 7.40 (t, J ¼ 7.92 Hz, 1H, ArH),
5.42 (s, 1H, CH), 3.5 (s, 3H, NCH3) ppm; 13C (100 MHz, DMSO-d6
+ CDCl3): d ¼ 98.5, 160.2, 160.0, 151.3, 150.1, 140.9, 138.6, 131.8,
130.1, 123.6, 122.3, 122.1, 118.8, 114.9, 112.6, 106.3, 51.2, 38.5,
29.3 ppm; anal. calcd for C21H14N4O5 (402.36): C, 62.69; H, 3.51;
N, 13.92; found: C, 62.71; H, 3.54; N, 13.95.
2-Amino-4-(benzo[1,3]dioxole-5-carbonyl)-6-methyl-5-oxo-
5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile
(1e).
ꢀ
White solid; mp 277–280 C; IR (ATR) 3472, 3302, 3164, 2913,
2208, 2188, 1672, 1619, 1505, 1439, 1383, 1355, 1255, 1159,
1128, 1100, 1032 cmꢁ1; 1H NMR (400 MHz, DMSO-d6 + CDCl3):
d ¼ 7.98 (dd, J ¼ 8.0 Hz, 1H, ArH), 7.82 (dd, J ¼ 8.32, 1.72 Hz, 1H,
Spectral data
2-Amino-4-benzoyl-6-methyl-5-oxo-5,6-dihydro-4H-pyrano ArH), 7.75–7.72 (t, J ¼ 8.64, 1H, ArH), 7.59 (d, J ¼ 8.48, 1H, ArH),
[3,2-c]quinoline-3-carbonitrile (1a). Light yellow solid; mp 7.55 (s, 1H, ArH), 7.43–7.39 (m, 3H, NH2 + ArH), 7.09 (d, 1H,
264–266 ꢀC; IR (ATR) 3449, 3319, 2192, 1673, 1622, 1593, 1447, ArH), 6.17 (s, 2H, OCH2O), 5.31 (s, 1H, CH), 3.57 (s, 3H, N–CH3)
1
1377, 1332, 1260, 1218, 1154, 1034 cmꢁ1; H NMR (400 MHz, ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3): d ¼ 196.8, 160.1,
DMSO-d6 + CDCl3): d ¼ 8.13 (d, J ¼ 7.5 Hz, 2H, ArH), 8.0 (dd, J ¼ 151.9, 151.2, 147.8, 138.6, 131.7, 130.5, 125.7, 122.3, 121.9,
8.0 Hz, 1.3 Hz, 1H, ArH), 7.75–7.68 (m, 2H, ArH), 7.58 (d, J ¼ 8.1 119.0, 114.9, 112.6, 108.1, 107.9, 106.9, 102.1, 52.2, 37.4, 29.2;
Hz, 2H, ArH), 7.57 (d, J ¼ 7.5 Hz, 1H, ArH), 7.44 (bs, 2H, –NH2), anal. calcd for C22H15N3O5 (401.37): C, 65.83; H, 3.77; N, 10.47;
7.40 (t, J ¼ 7.8 Hz, 1H, ArH), 5.36 (s, 1H, CH), 3.57 (s, 3H, –NCH3) found: C, 65.81; H, 3.75; N, 10.52.
ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3): d ¼ 198.8, 160.1,
2-Amino-4-(6-methoxy-nepthalene-2-carbonyl)-6-methyl-5-
151.3, 138.6, 135.9, 133.5, 131.7, 128.8, 128.6, 122.3, 121.9, oxo-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbontrile (1f).
119.1, 114.9, 112.6, 106.8, 51.8, 37.7, 29.3 ppm; anal. calcd for Grey solid; mp 258–260 ꢀC; IR (ATR) 3455, 3304, 2193, 1673,
C
21H15N3O3 (357.36): C, 70.58; H, 4.23; N, 11.76; found: C, 70.61; 1620, 1593, 1478, 1464, 1379, 1262, 1191, 1151, 1124, 1030
H, 4.25; N, 11.82.
cmꢁ1; 1H NMR (400 MHz, DMSO-d6 + CDCl3): d ¼ 8.11 (d, J ¼ 9.0
2-Amino-4-(4-methoxy-benzoyl)-6-methyl-5-oxo-5,6-dihydro- Hz, 1H, ArH), 8.02 (t, J ¼ 8.84 Hz, 2H, ArH), 7.94 (d, J ¼ 8.72 Hz,
4H-pyrano[3,2-c]quinoline-3-carbonitrile (1b). White solid; mp 1H, ArH), 7.75 (t, J ¼ 5.8 Hz, 1H, ArH), 7.63 (d, J ¼ 8.52 Hz, 1H,
282–284 ꢀC; IR (ATR) 3779, 3319, 2203, 1674, 1592, 1416, 1365, ArH), 7.48–7.45 (m, 4H, ArH), 7.32–7.29 (dd, J ¼ 8.96, 2.52 Hz,
1329, 1199, 1172, 1013 cmꢁ1; H NMR (400 MHz, DMSO-d6 + 2H, ArH), 5.57 (s, 1H, CH), 3.9 (s, 3H, OCH3), 3.57 (s, 3H, N–CH3)
1
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ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3): d ¼ 198.3, 160.13, cmꢁ1; H NMR (400 MHz, DMSO-d6 + CDCl3): d ¼ 8.89 (s, 1H,
159.6, 151.3, 138.6, 137.2, 131.8, 131.5, 131.4, 131.0, 127.4, ArH), 8.12–8.02 (m, 3H, ArH), 7.96–7.86 (m, 4H, ArH), 7.57 (bs,
127.1, 124.8, 122.4, 121.9, 119.5, 119.2, 119.15, 115.1, 112.6, 2H, NH2), 7.45 (s, 1H, ArH), 7.31 (dd, J ¼ 8.92, 2.52 Hz, 1H, ArH),
107.0, 106.1, 55.1, 52.2, 37.3, 29.3 ppm; anal. calcd for 5.6 (s, 1H, CH), 3.95 (s, 3H, OCH3) ppm; 13C NMR (100 MHz,
C
26H19N3O4 (437.14): C, 71.39; H, 4.38; N, 9.61; found: C, 71.41, DMSO-d6 + CDCl3): d ¼ 197.0, 182.5, 176.5, 159.9, 159.8, 150.0,
H, 4.35, N, 9.64. 137.4, 134.8, 134.4, 131.8, 131.4, 130.6, 130.4, 130.2, 127.4,
2-Amino-4-benzoyl-5,10-dioxo-5,10-dihydro-4H-benzo[g]chro- 127.2, 126.3, 125.9, 124.8, 121.2, 119.6, 118.7, 106.1, 55.4, 51.8,
mene-3-carbonitrile (2a). Red solid; mp 233–235 ꢀC; IR (ATR) 36.9 ppm; anal. calcd for C26H16N2O5 (436.42): C, 71.56; H, 3.70;
3779, 3341, 2194, 1685, 1662, 1589, 1408, 1363, 1246, 1206, 1046 N, 6.42; found: C, 71.57; H, 3.72; N, 6.45.
1
cmꢁ1; H NMR (400 MHz, DMSO-d6 + CDCl3): d ¼ 8.16 (d, J ¼
2-Amino-4-benzoyl-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-
7.28 Hz, 2H, ArH), 8.12–8.01 (m, 1H, ArH), 7.95–7.89 (m, 3H, carbonitrile (3a). White solid; mp 266–268 ꢀC, IR (ATR) 3400,
ArH), 7.75 (t, J ¼ 7.48 Hz, 1H, ArH), 7.63 (t, J ¼ 7.9 Hz, 2H, ArH), 2814, 1831, 1708, 1672, 1600, 1579, 1458, 1372, 1221, 1112, 1063
7.62 (bs, 2H, NH2), 5.5 (s, 1H, CH); 13C NMR (100 MHz, DMSO- cmꢁ1; 1H NMR (400 MHz, DMSO-d6 + CDCl3): d ¼ 8.13 (d, J ¼ 8.6
d6 + CDCl3): d ¼ 197.8, 182.5, 176.5, 159.8, 149.9, 135.1, 134.8, Hz, 2H, ArH); 7.90 (dd, J ¼ 7.92, 1.48 Hz, 1H, ArH), 7.75–7.69 (m,
134.6, 134.1, 130.5, 130.4, 129.2, 128.9, 126.4, 125.9, 121.1, 2H, ArH), 7.59 (t, J ¼ 7.68 Hz, 2H, ArH), 7.59 (bs, 2H, NH2), 7.51–
118.6, 51.4, 37.2 ppm; anal. calcd for C21H12N2O4 (356.33): C, 7.46 (m, 2H, ArH), 5.34 (s, 1H, CH) ppm; 13C NMR (100 MHz,
70.78; H, 3.39; N, 7.86; found: C, 70.75; H, 3.41; N, 7.89.
DMSO-d6 + CDCl3): d ¼ 197.8, 160.0, 159.6, 154.8, 152.1, 135.4,
2-Amino-4-(4-methoxy-benzoyl)-5,10-dioxo-5,10-dihydro-4H- 133.8, 133.1, 129.0, 128.7, 124.7, 122.2, 118.5, 116.6, 112.6,
benzo[g]chromene-3-carbonitrile (2b). Brown solid; mp 234–236 101.8, 51.90, 37.2 ppm; anal. calcd for C20H12N2O4 (344.32): C,
ꢀC; IR (ATR) 3776, 3319, 2203, 1719, 1655, 1592, 1416, 1365, 69.76; H, 3.51; N, 8.14; found: C, 69.78; H, 3.53; N, 8.16.
1
1245, 1199, 1172, 1042 cmꢁ1; H NMR (400 MHz, DMSO-d6 +
2-Amino-4-(4-methoxy-benzoyl)-5-oxo-4H,5H-pyrano[3,2-c]
CDCl3): d ¼ 8.14 (d, J ¼ 7.0 Hz, 2H, ArH), 8.11–8.10 (m, 1H, ArH), chromene-3-carbonitrile (3b). White solid; mp 262–264 ꢀC; IR
7.95–7.88 (m, 3H, ArH), 7.57 (s, 2H, NH2), 7.14 (d, J ¼ 9.84 Hz, (ATR) 3456, 3311, 2192, 1668, 1594, 1379, 1258, 1158, 1025, 945,
2H, ArH), 5.45 (s, 1H, CH), 3.90 (s, 3H, OCH3); 13C NMR (100 802, 782 cmꢁ1; 1H NMR (400 MHz, DMSO-d6 + CDCl3) d ¼ 8.12
MHz, DMSO-d6 + CDCl3): d ¼ 195.9, 182.5, 176.5, 163.9, 159.8, (d, J ¼ 8.92, 2H, ArH), 7.88 (d, J ¼ 7.72 Hz, 1H, ArH), 7.73–7.69
149.9, 134.8, 134.5, 131.7, 130.5, 130.4, 127.8, 126.3, 125.9, (m, 1H, ArH), 7.57 (bs, 2H, NH2), 7.47 (t, J ¼ 8.8 Hz, 2H, ArH),
121.2, 118.7, 114.2, 55.7, 51.8, 36.8 ppm; anal. calcd for 7.09 (d, J ¼ 8.8 Hz, 2H, ArH), 5.29 (s, 1H, CH), 3.88 (s, 3H, OCH3)
C
22H14N2O5 (386.36): C, 68.39; H, 3.65; N, 7.25; found: C, 68.37; ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3); d ¼ 196.0, 163.8,
H, 3.66; N, 7.27.
159.9, 159.5, 154.7, 152.1, 133.0, 131.5, 128.1, 124.7, 122.1,
2-Amino-4-(4-uoro-benzoyl)-5,10-dioxo-5,10-dihydro-4H-benzo- 118.5, 116.6, 113.9, 112.6, 102.0, 55.5, 52.2, 36.7 ppm; anal.
ꢀ
[g]chromene-3-carbonitrile (2c). Red solid; mp 254–256 C; IR calcd for C21H14N2O5 (374.35): C, 67.38; H, 3.77; N, 7.48; found:
(ATR) 3779, 3338, 2188, 1654, 1590, 1417, 1367, 1268, 1246, C 67.36; H, 3.78; N, 7.51.
1
1156, 1043 cmꢁ1; H NMR (400 MHz, DMSO-d6 + CDCl3): d ¼
2-Amino-4-(4-uoro-benzoyl)-5-oxo-4H,5H-pyrano[3,2-c]chro-
8.28–8.25 (m, 2H, ArH), 8.11–8.09 (m, 1H, ArH), 7.95–7.89 (m, mene-3-carbonitrile (3c). White solid, mp 251–253 ꢀC; IR (ATR)
3H, ArH), 7.62 (bs, 2H, NH2), 7.46 (t, J ¼ 8.8 Hz, 2H, ArH), 5.5 (s, 3473, 3329, 2186, 1719, 1677, 1589, 1509, 1386, 1329, 1222,
1H, CH) ppm; 13C NMR (400 MHz, DMSO-d6 + CDCl3) d ¼ 196.5, 1072, 946, 866, 753 cmꢁ1
, +
1H NMR (400 MHz, DMSO-d6
182.5, 176.5, 159.8, 149.9, 134.9, 134.6, 132.4, 132.3, 130.5, CDCl3): d ¼ 8.31–8.27 (m, 2H, ArH), 7.92 (dd, J ¼ 8.2, 1.44 Hz,
130.4, 126.4, 126.0, 120.9, 118.6, 116.2, 115.9, 51.3, 37.2, anal. 1H, ArH), 7.80 (t, J ¼ 8.4 Hz, 1H, ArH), 7.73 (bs, 2H, NH2), 7.59–
calcd for C21H11FN2O4 (374.32): C, 67.38; H, 2.96; N, 7.48; found: 7.55 (m, 2H, ArH), 7.49 (t, J ¼ 8.84 Hz, 2H, ArH), 5.47 (s, 1H, CH);
C, 67.36; H, 2.98; N, 7.51.
13C NMR (100 MHz, DMSO-d6 + CDCl3): d ¼ 196.2, 166.8, 164.3,
2-Amino-4-(benzo[1,3]-dioxole-5-carbonyl)-5,10-dioxo-5,10- 160.1, 159.6, 154.8, 152.2, 132.8, 132.02, 132.00, 131.9, 124.6,
dihydro-4H-benzo[g]chromene-3-carbonitrile (2d). Orange 122.3, 118.5, 116.5, 115.8, 115.5, 112.6, 101.5, 51.8, 37.2, ppm;
solid; mp 246–248 ꢀC; IR (ATR) 3470, 3335, 3088, 2195, 1677, anal. calcd for C20H11FN2O4 (362.31): C, 66.30; H, 3.06; N, 7.73;
1647, 1062, 1589, 1503, 1438, 1353, 1268, 1249, 1209, 1100, found C, 66.32; H, 3.08; N, 7.75.
1
1038, 949, 869, 797, 726 cmꢁ1; H NMR (400 MHz, DMSO-d6 +
2-Amino-4-(4-nitro-benzoyl)-5-oxo-4H,5H-pyrano[3,2-c]chro-
CDCl3): d ¼ 8.09–8.07 (m, 1H, ArH), 7.94–7.91 (m, 1H, ArH), mene-3-carbonitrile (3d). Yellow solid; mp 248–250 ꢀC; IR (ATR)
7.89–7.83 (m, 3H, ArH), 7.58–7.57 (m, 1H, ArH), 7.54 (bs, 2H, 3456, 3332, 2192, 1717, 1699, 1679, 1588, 1515, 1381, 1325,
NH2), 7.11 (d, J ¼ 8.56, 1H, ArH), 6.19 (s, 2H, CH2), 5.4 (s, 1H, 1217, 1172, 1068 cmꢁ1; 1H NMR (400 MHz, DMSO-d6 + CDCl3):
CH) ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3): d ¼ 195.5, d ¼ 8.46 (q, J ¼ 14.4 Hz, 4H, ArH), 7.94 (d, J ¼ 8.16 Hz, 1H, ArH),
182.4, 176.5, 159.8, 152.3, 149.8, 148.1, 134.7, 134.4, 130.5, 7.85–7.81 (m, 2H, NH2 + 1H, ArH), 7.62–7.58 (m, 2H, ArH), 5.54
130.3, 129.6, 126.3, 126.2, 125.9, 121.2, 118.6, 108.2, 108.1, (s, 1H, CH) ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3): d ¼
102.2, 51.8, 36.9 ppm; anal. calcd for C22H12N2O6 (400.34): C, 197.2, 160.1, 159.6, 154.9, 152.1, 150.2, 140.3, 133.1, 130.2,
66.00; H, 3.02; N, 7.00; found: C, 66.02; H, 3.05; N, 7.08.
124.7, 123.6, 122.3, 118.3, 116.6, 112.5, 101.1, 51.1, 37.9 ppm;
2-Amino-4-(6-methoxy-naphthalene-2-carbonyl)-5,10-dioxo- anal. calcd for C20H11N3O6 (389.32): C, 61.70; H, 2.85; N, 10.79;
5,10-dihydro-4H-benzo[g]cꢀhromene-3-carbonitrile (2e). Pale found: C, 61.73; H, 2.87; N, 10.83.
yellow solid; mp 238–240 C; IR (ATR) 3303, 3189, 2200, 1962,
2-Amino-4-benzoyl-7-methyl-5-oxo-4H,5H-pyrano[4,3-b]pyran-
1677, 1623, 1480, 1367, 1298, 1242, 1197, 1170, 1045, 1016 3-carbonitrile (3e). Brown solid; mp 168–170 ꢀC, IR (ATR) 3779,
24468 | RSC Adv., 2016, 6, 24464–24469
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3145, 2197, 1709, 1673, 1611, 1390, 1263, 1223, 1142, 1047
cmꢁ1; 1H NMR (400 MHz, DMSO-d6 + CDCl3): d ¼ 8.07 (d, J ¼ 8.6
Hz, 2H, ArH), 7.67 (t, J ¼ 7.4 Hz, 1H, ArH), 7.55 (t, J ¼ 7.5 Hz, 2H,
ArH), 7.35 (bs, 2H, NH2), 6.25 (s, 1H, ]CH), 5.14 (s, 1H, CH),
2.25 (s, 3H, CH3) ppm; 13C NMR (100 MHz, DMSO-d6 + CDCl3):
d ¼ 198.1, 162.9, 161.7, 159.6, 159.5, 135.5, 133.6, 128.8, 128.6,
118.6, 98.6, 97.9, 51.9, 36.6, 19.3 ppm; anal. calcd for
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17H12N2O4 (308.29) C, 66.23; H, 3.92; N, 9.09; found: C, 66.25;
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H, 3.95; N, 9.14.
Acknowledgements
We are thankful to IIT Patna for providing basic research
facilities and fellowship to R. M. The authors are grateful to
Achintya Jana, Dr Neeladri Das, and SAIF-IIT Patna for
providing us XRD data of compound 1c. We are also thankful to
SAIF, Panjab University, for providing NMR facilities for char-
acterization of compounds.
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