Microwave-assisted Multi-component Domino Reaction for the Green Synthesis of Novel Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines Using H3PW12O40 as Efficient, Cost-effective and Recyclable Catalyst

Full text of DOI:10.1080/00304948.2019.1653128

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
ISSN: 0030-4948 (Print) 1945-5453 (Online) Journal homepage: https://www.tandfonline.com/loi/uopp20
Microwave-assisted Multi-component Domino
Reaction for the Green Synthesis of Novel
Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines
Using H3PW12O40 as Efficient, Cost-effective and
Recyclable Catalyst
Maryam Mohammadrezaei, Razieh Mohebat & Masoumeh Tabatabaee
To cite this article: Maryam Mohammadrezaei, Razieh Mohebat & Masoumeh Tabatabaee
(2019): Microwave-assisted Multi-component Domino Reaction for the Green Synthesis of
Novel Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines Using H3PW12O40 as Efficient, Cost-
effective and Recyclable Catalyst, Organic Preparations and Procedures International, DOI:
10.1080/00304948.2019.1653128
To link to this article: https://doi.org/10.1080/00304948.2019.1653128
Published online: 22 Aug 2019.
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Organic Preparations and Procedures International, 0:1–9, 2019
# 2019 Taylor & Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2019.1653128
Microwave-assisted Multi-component Domino
Reaction for the Green Synthesis of Novel
Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines
Using H3PW12O40 as Efficient, Cost-effective and
Recyclable Catalyst
Maryam Mohammadrezaei, Razieh Mohebat, and
Masoumeh Tabatabaee
Department of Chemistry, Yazd Branch, Islamic Azad University, Yazd, Iran
In recent years, green chemistry techniques have attracted considerable attention in the
chemical industry and academic research laboratories due to environmental, health, and
economic benefits.1–5 In this context, multi-component domino reactions (MDRs) have
considerable ecological interest. They represent a very influential and efficient bond-
forming strategy for medicinal, organic, and combinatorial chemistry.6–10 In this regard,
microwave-assisted organic synthesis (MAOS) has developed into a highly-valued field
for the preparation of complex heterocyclic molecules.11 MAOS permits enhanced reac-
tion rates, formation of purer products in higher yields and easier manipulation.
Consequently, the design of novel MDRs using microwave irradiation for the synthesis
of simple and complex bioactive heterocycles has become a notable topic in the drug
discovery process and for the analysis of drugs.12–15 Among these drugs, we may note
the importance of the pyran16–23 and phenazine24–32 moieties, particularly where these
units may be clubbed together.
Some important pharmaceutically active pyrano-fused benzophenazine deriva-
tives33–35 are shown in Figure 1.
In continuation of our research in the synthesis of complex organic compounds uti-
lizing green chemistry tools,36–40 we report here our results on the efficient domino syn-
thesis of novel benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines 6a-j in a one-pot,
four-component condensation reaction between 2-hydroxy-1,4-naphthoquinone 1,
o-phenylenediamine 2, benzaldehydes 4 and 4-hydroxy-6-methyl-2H-pyran-2-one 5.
The reaction is catalyzed by phosphotungstic acid (H3PW12O40). We have found the lat-
ter to be a highly efficient, eco-friendly and recyclable solid heteropolyacid catalyst
when used under microwave irradiation (180 W, max. 70 ꢀC) in EtOH/H2O (1:1)
(Scheme 1).
Received February 10, 2018; in final form May 15, 2019.
Address correspondence to Razieh Mohebat, Department of Chemistry, Yazd Branch, Islamic
Azad University, Yazd, Iran. E-mail: mohebat@iauyazd.ac.ir
Color versions of one or more of the figures in the article can be found online at www.tandfon-
line.com/uopp.
1

2
Mohebat et al.
Figure 1. Biologically active pyrano-fused benzophenazine derivatives.
Scheme 1. H3PW12O40-catalyzed domino synthesis of 3-methyl-16-arylbenzo[a]pyrano[3',4':5,6]-
pyrano[2,3-c]phenazin-1(16H)-ones (6a-j) under microwave irradiation in EtOH/H2O (1:1).
To optimize the catalytic system, the reaction of 1 (1 mmol), 2 (1 mmol), 4- nitro-
benzaldehyde 4 (1 mmol), and 5 (1 mmol) in EtOH was used as a model reaction for
the synthesis of compound 6a. We studied the type of catalyst, catalyst amount, solvent,
and the influence of microwave irradiation. The results are summarized in Table 1. The
reaction gave the highest yield using 10 mol% of H3PW12O40 in EtOH/H2O (1:1) under
microwave irradiation (180 W, max. 70 ꢀC) (Table 1, entry 9).
To generate a small library of functionalized compounds 6, we tested a variety of
aromatic aldehydes, including those with electron withdrawing and electron donating
groups under the optimal conditions. In all cases the products were obtained in good to
high yields (Table 2). Under the same conditions, however, this reaction did not occur
when aliphatic aldehydes were used. The compounds in Table 2 are novel and were
rigorously characterized (see Experimental Section).
Since the recovery of the catalyst is important in green organic synthesis, we also
used our optimized reaction conditions to evaluate the reusability of the catalyst
H3PW12O40. After completion of the reaction, the reaction mixture was cooled to room
temperature. Then, water was added to the mixture and the crude solid product was fil-
tered and washed repeatedly with water. Since the catalyst is soluble in water, the cata-
lyst was recovered by evaporation of the water and washed with diethyl ether and
reused for further trials. We found that the catalyst could be used at least four times
with only a very slight reduction in activity; after four runs, for example, the yield (6a)
typically declined from 88% to 85%.

Novel Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines
3
Table 1
Optimization of Reaction Conditions for Compound 6aa
Entry
Catalyst
No catalyst
PTSA (10 mol%)
H2SO4 (10 mol%)
HCl (10 mol%)
H3PMo12O40 (10 mol%) EtOH, 180 W
H3PW12O40 (10 mol%) EtOH, 180 W
H3PW12O40 (10 mol%) H2O, 180 W
H3PW12O40 (10 mol%) PEG-400, 180 W
H3PW12O40 (10 mol%) EtOH/H2O (1:1), 180 W
H3PW12O40 (20 mol%) EtOH/H2O (1:1), 180 W
Reaction conditions
Time (min) Yield (%)b
1
2
3
4
5
6
7
8
EtOH, 180 W
EtOH, 180 W
EtOH, 180 W
EtOH, 180 W
60
30
30
30
30
30
30
30
20
20
20
60
20
120
Trace
81
64
60
78
84
57
80
88
87
76
54
85
9
10
11
12
13
14
H3PW12O40 (5 mol%)
EtOH/H2O (1:1), 180 W
H3PW12O40 (10 mol%) EtOH/H2O (1:1), 100 W
H3PW12O40 (10 mol%) EtOH/H2O (1:1), 300 W
H3PW12O40 (10 mol%) EtOH/H2O (1:1), rt
Trace
aReaction conditions: 2-hydroxynaphthalene-1,4-dione (1 mmol), o-phenylenediamine (1 mmol),
4- nitrobenzaldehyde (1 mmol) and 4-hydroxy-6-methyl-2H-pyran-2-one (1 mmol) in the pres-
ence of different catalytic systems under various conditions.
bIsolated yields.
In summary, we have reported a highly efficient and green protocol for the synthe-
sis of functionalized pyranophenazines 6 via a one-pot condensation reaction using
H3PW12O40 as catalyst. This preparation has the advantages of the commercial avail-
ability of the catalyst, a simple procedure, short reaction times, high yields and excel-
lent chemoselectivity. The reusability of the catalyst and the non-toxic nature of the
solvent are in keeping with green methodology. We hope that the convenience of this
procedure will spur the investigation of the useful activities of compounds 6.
Experimental Section
The chemicals used in this work were purchased from Merck and Aldrich and used without
further purification. All melting points were determined on an Electrothermal 9100 appar-
atus and are uncorrected. IR spectra were recorded on a Shimadzu IR-470 spectrometer.
Elemental analyses for C, H, and N were performed using a Costech ECS 4010 CHNS-O
analyzer at the analytical laboratory of Islamic Azad University Yazd Branch. Mass spectra
were recorded on an Agilent Technology (HP) spectrometer operating at an ionization
potential of 70 eV. NMR spectra were obtained on a Bruker DRX-400 Avance spectrom-
eter (1H NMR at 400 Hz, 13C NMR at 100 Hz) in CDCl3 using TMS as an internal

4
Mohebat et al.
Table 2
Domino One-pot Four-component Synthesis of
Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazine Derivativesa
Entry
R
Product
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
9
4-NO2
4-Br
2-NO2
2-Cl
6a
6b
6c
6d
6e
6f
6g
6h
6i
20
30
30
20
20
20
20
30
30
30
88
81
83
83
85
82
86
85
83
79
3-NO2
4-Cl-3-NO2
2,4-(Cl)2
H
4-OMe
3,4-(OMe)2
10
6j
aReaction conditions: 2-hydroxynaphthalene-1,4-dione (1 mmol), o-phenylenediamine (1 mmol),
aromatic aldehyde (1 mmol), 4-hydroxy-6-methyl-2H-pyran-2-one (1 mmol) and H3PW12O40
(10 mol%) under microwave irradiation (180 W, max. 70 C) in EtOH/H2O (1:1, 10 mL).
bIsolated yields.
standard. Chemical shifts (d) are given in ppm and coupling constants (J) are given in Hz.
All reactions were carried out using a laboratory microwave oven (MicroSYNTH,
Milestone Company, Italy). Thin-layer chromatography (TLC) was performed on silica-gel
Polygram SILG/UV254 plates and the solvent for TLC was n-hexane/ethyl acetate, 2:1.
General Procedure for the Synthesis of Novel
Benzo[a]pyrano[3',4':5,6]pyrano[2,3- c]phenazine Derivatives (6a-j)
H3PW12O40 (10 mol%) was added to a mixture of 2-hydroxynaphthalene-1,4-dione 1
(1 mmol) and o-phenylenediamine 2 (1 mmol) in EtOH/H2O (1:1, v/v) (10 mL) and this
mixture was irradiated in a microwave oven at 180 W until in less than 5 minutes an
orange solid of benzo[a]phenazin-5-ol 3 was formed. The microwave was programmed
to give a maximum internal temperature of 70 ꢀC. Then, aryl aldehydes 4 (1 mmol) and
4-hydroxy-6-methyl-2H- pyran-2-one (1 mmol) 5 were added to the above reaction mix-
ture which was irradiated further at the same temperature (180 W, max. 70 ꢀC) for an
appropriate time as shown in Table 2. Upon completion of the reaction, monitored by
TLC, the reaction mixture was allowed to cool to room temperature. Then, 5 mL of
water was added to the mixture and filtration allowed separation of the crude product.
The separated product was washed twice with water (2 ꢁ 5 mL). The solid crude prod-
uct subsequently recrystallized from hot ethanol to give the pure product 6.

Novel Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines
5
3-Methyl-16-(4-nitrophenyl)benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-1(16H)-
one (6a)
Red powder; yield 0.429 g (88%), m.p. 194-195 ꢀC; IR (KBr): ꢀmax ¼ 2895, 1695,
1651, 1622, 1583, 1504, 1446, 1401, 1335, 1284, 1154, 1059, 755 cm–1; 1H NMR
(400 MHz, CDCl3): d 2.34 (s, 3H, CH3), 6.06 (s, 1H, CH), 6.57 (s, 1H, CH), 7.14 (d,
1H, J ¼ 8.0 Hz, Ar-H), 7.34 (d, 1H, J ¼ 8.8 Hz, Ar-H), 7.42-7.45 (m, 1H, Ar-H), 7.87-
7.97 (m, 5H, Ar- H), 8.15-8.19 (m, 1H, Ar-H), 8.31-8.39 (m, 2H, Ar-H), 9.10-9.13 (m,
1H, Ar-H) ppm; 13C NMR (100 MHz, CDCl3): d 19.7 (CH3), 37.0 (CH), 98.6, 104.2,
117.2, 123.3, 123.6, 124.9, 125.0, 126.1, 127.5, 128.0, 128.2, 129.0, 129.4, 129.8,
130.6, 131.5, 132.4, 141.8, 142.4, 145.5, 146.1, 146.8, 154.9, 157.1, 160.8, 161.9
(Colefinic and Carom), 166.3 (C ¼ O) ppm; MS (m/z, %): 487 (Mþ, 3).
Anal. Calcd for C29H17N3O5: C, 71.45; H, 3.52; N, 8.62. Found: C, 71.68; H, 3.36;
N, 8.85.
16-(4-Bromophenyl)-3-methylbenzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-
1(16H)-one (6b)
Red powder; yield 0.422 g (81%), m.p. 189-191 ꢀC; IR (KBr): ꢀmax ¼ 2895, 1705,
1650, 1624, 1547, 1479, 1448, 1409, 1345, 1248, 1143, 1041, 754 cm–1; 1H NMR
(400 MHz, CDCl3): d 2.33 (s, 3H, CH3), 6.08 (s, 1H, CH), 6.48 (s, 1H, CH), 6.90 (d,
1H, J ¼ 8.0 Hz, Ar-H), 7.05-7.21 (m, 2H, Ar-H), 7.40-7.45 (m, 1H, Ar-H), 7.75-7.99
(m, 5H, Ar-H), 8.18-8.34 (m, 2H, Ar-H), 9.35-9.36 (m, 1H, Ar-H) ppm; 13C NMR
(100 MHz, CDCl3): d 19.7 (CH3), 36.3 (CH), 96.5, 104.0, 117.2, 119.9, 124.4, 124.8,
125.0, 125.9, 126.2, 128.3, 128.9, 129.1, 129.3, 129.5, 129.7, 131.1, 131.4, 131.5,
132.2, 139.4, 145.8, 146.7, 147.2, 157.3, 160.5, 162.1 (Colefinic and Carom), 167.1
(C ¼ O) ppm; MS (m/z, %): 521 (Mþ, 7).
Anal. Calcd for C29H17BrN2O3: C, 66.81; H, 3.29; N, 5.37. Found: C, 67.06;
H,3.36; N, 5.62.
3-Methyl-16-(2-nitrophenyl)benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-1(16H)-
one (6c)
Brown powder; yield 0.404 g (83%), m.p. 198-200 ꢀC; IR (KBr): ꢀmax ¼ 2892, 1702,
1650, 1616, 1586, 1517, 1490, 1458, 1397, 1336, 1240, 1147, 1120, 752 cm–1; 1H NMR
(400 MHz, CDCl3): d 2.32 (s, 3H, CH3), 6.05 (s, 1H, CH), 6.33 (s, 1H, CH), 7.15-8.42
(m, 11H, Ar-H), 9.32-9.35 (m, 1H, Ar-H) ppm; 13C NMR (100 MHz, CDCl3): d 20.1
(CH3), 36.8 (CH), 97.4, 102.1, 117.4, 124.9, 125.2, 126.1, 127.3, 128.3, 128.7, 129.0,
129.5, 129.9, 131.1, 131.5, 131.7, 132.1, 140.2, 146.1, 146.7, 147.5, 157.5, 160.4, 162.8
(Colefinic and Carom), 167.2 (C ¼ O) ppm; MS (m/z, %): 487 (Mþ, 6).
Anal. Calcd for C29H17N3O5: C, 71.45; H, 3.52; N, 8.62. Found: C, 71.62; H, 3.64;
N, 8.51.
16-(2-Chlorophenyl)-3-methylbenzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-
1(16H)-one (6d)
Red powder; yield 0.395 g (83%), m.p. 251-254 ꢀC; IR (KBr): ꢀmax ¼ 2910, 1705,
1650, 1621, 1582, 1523, 1489, 1455, 1401, 1337, 1245, 1148, 1042, 749 cm–1; 1H
NMR (400 MHz, CDCl3): d 2.31 (s, 3H, CH3), 6.06 (s, 1H, CH), 6.56 (s, 1H, CH),

6
Mohebat et al.
7.17-7.96 (m, 8H, Ar- H), 8.21 (d, 1H, J ¼ 8.4 Hz, Ar-H), 8.33-8.39 (m, 2H, Ar-H),
9.06 (d, 1H, J ¼ 7.6 Hz, Ar-H) ppm; 13C NMR (100 MHz, CDCl3): d 19.6 (CH3), 36.1
(CH), 98.2, 101.5, 118.1, 124.7, 125.7, 127.9, 128.3, 128.6, 129.1, 129.3, 129.5, 129.9,
130.3, 130.7, 131.1, 131.5, 132.1, 140.4, 141.3, 146.2, 146.7, 150.3, 158.2, 159.9, 161.8
(Colefinic and Carom), 167.0 (C ¼ O) ppm; MS (m/z, %): 476 (Mþ, 2).
Anal. Calcd for C29H17ClN2O3: C, 73.03; H, 3.59; N, 5.87. Found: C, 72.85; H,
3.77; N, 6.08.
3-Methyl-16-(3-nitrophenyl)benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-1(16H)-
one (6e)
Red powder; yield 0.414 g (85%), m.p. 180-182 ꢀC; IR (KBr): ꢀmax ¼ 2895, 1695,
1650, 1623, 1566, 1515, 1489, 1444, 1400, 1336, 1250, 1147, 1026, 758 cm–1; 1H
NMR (400 MHz, CDCl3): d 2.34 (s, 3H, CH3), 6.15 (s, 1H, CH), 6.58 (s, 1H, CH),
7.20 (d, 1H, J ¼ 8.0 Hz, Ar-H), 7.48-7.79 (m, 3H, Ar-H), 7.83 (d, 1H, J ¼ 8.0 Hz, Ar-
H), 7.86-8.49 (m, 6H, Ar- H), 9.32-9.35 (m, 1H, Ar-H) ppm; 13C NMR (100 MHz,
CDCl3): d 19.7 (CH3), 34.7 (CH), 96.4, 103.1, 119.8, 121.0, 122.8, 124.7, 125.1, 126.2,
128.6, 129.0, 129.4, 129.6, 130.1, 131.2, 132.8, 133.3, 138.4, 139.9, 141.4, 146.2,
147.5, 148.6, 152.4, 158.1, 159.4, 162.8 (Colefinic and Carom), 166.7 (C ¼ O) ppm;
MS (m/z, %): 487 (Mþ, 11).
Anal. Calcd for C29H17N3O5: C, 71.45; H, 3.52; N, 8.62. Found: C, 71.62; H, 3.73;
N, 8.54.
16-(4-Chloro-3-nitrophenyl)-3-methylbenzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-
1(16H)-one (6f)
Red powder; yield 0.427 g (82%), m.p. 225-227 ꢀC; IR (KBr): ꢀmax ¼ 2900, 1700,
1
1645, 1623, 1559, 1519, 1446, 1398, 1339, 1248, 1148, 1039, 756 cm–1; H NMR
(400 MHz, CDCl3): d 2.34 (s, 3H, CH3), 6.15 (s, 1H, CH), 6.58 (s, 1H, CH), 7.32-7.95
(m, 7H, Ar-H), 8.23 (d, 1H, J ¼ 8.0 Hz, Ar-H), 8.37-8.39 (m, 2H, Ar-H), 9.09 (d, 1H,
J ¼ 7.6 Hz, Ar-H) ppm; 13C NMR (100 MHz, CDCl3): d 20.0 (CH3), 34.4 (CH), 97.1,
102.5, 118.2, 122.5, 123.4, 124.6, 126.4, 127.2, 127.9, 129.1, 129.4, 129.7, 130.0,
130.7, 131.2, 132.4, 133.8, 135.4, 141.7, 142.4, 146.1, 146.8, 151.3, 157.8, 159.6, 162.3
(Colefinic and Carom), 167.1 (C ¼ O) ppm; MS (m/z, %): 521 (Mþ, 8).
Anal. Calcd for C29H16ClN3O5: C, 66.74; H, 3.09; N, 8.05. Found: C, 66.98; H,
3.17; N, 7.89.
16-(2,4-Dichlorophenyl)-3-methylbenzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-
1(16H)-one (6g)
Red powder; yield 0.439 g (86%), m.p. 170-171 ꢀC; IR (KBr): ꢀmax ¼ 2820, 1715,
1688, 1656, 1636, 1578, 1454, 1400, 1370, 1332, 1279, 1167, 1042, 750 cm–1; 1H
NMR (400 MHz, CDCl3): d 2.36 (s, 3H, CH3), 6.07 (s, 1H, CH), 6.53 (s, 1H, CH),
7.16 (d, 1H, J ¼ 8.0 Hz, Ar-H), 7.39-7.52 (m, 7H, Ar-H), 7.78 (d, 1H, J ¼ 8.0 Hz, Ar-
H), 7.90 (d, 1H, J ¼ 8.4 Hz, Ar-H), 9.14 (d, 1H, J ¼ 7.6 Hz, Ar-H) ppm; 13C NMR
(100 MHz, CDCl3): d 21.3 (CH3), 40.5 (CH), 98.4, 100.7, 117.3, 123.6, 125.4, 126.1,
127.9, 128.9, 129.2, 129.4, 129.7, 130.3, 130.4, 130.9, 131.2, 132.5, 138.5, 141.1,

Novel Benzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazines
7
142.2, 146.4, 147.0, 150.1, 157.5, 159.8, 161.8 (Colefinic and Carom), 166.5 (C ¼ O)
ppm; MS (m/z, %): 511 (Mþ, 5).
Anal. Calcd for C29H16Cl2N2O3: C, 68.12; H, 3.15; N, 5.48. Found: C, 68.24; H,
3.38; N, 5.24.
3-Methyl-16-phenylbenzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-1(16H)-one (6h)
Red powder; yield 0.376 g (85%), m.p. 184-186 ꢀC; IR (KBr): ꢀmax ¼ 2965, 1702,
1685, 1636, 1580, 1520, 1489, 1447, 1396, 1333, 1270, 1155, 1041, 742 cm–1; 1H
NMR (400 MHz, CDCl3): d 2.37 (s, 3H, CH3), 6.40 (s, 1H, CH), 6.18 (s, 1H, CH),
7.06-7.38 (m, 5H, Ar-H), 7.58-7.62 (m, 1H, Ar-H), 7.85-7.97 (m, 4H, Ar-H), 8.24-8.50
(m, 2H, Ar-H), 9.41 (d, 1H, J ¼ 7.6 Hz, Ar-H) ppm; 13C NMR (100 MHz, CDCl3): d
21.3 (CH3), 37.2 (CH), 98.8, 102.1, 118.1, 122.5, 124.8, 126.1, 127.3, 128.4, 128.8,
129.1, 129.3, 129.5, 130.3, 130.6, 142.1, 142.8, 145.8, 146.3, 148.5, 158.2, 159.7, 162.8
(Colefinic and Carom), 167.2 (C ¼ O) ppm; MS (m/z, %): 442 (Mþ, 7).
Anal. Calcd for C29H18N2O3: C, 78.72; H, 4.10; N, 6.33. Found: C, 78.98; H, 4.01;
N, 6.54.
16-(4-Methoxyphenyl)-3-methylbenzo[a]pyrano[3',4':5,6]pyrano[2,3-c]phenazin-
1(16H)-one (6i)
Red powder; yield 0.392 g (83%), m.p. 203-206 ꢀC; IR (KBr): ꢀmax ¼ 2895, 1693,
1655, 1618, 1582, 1520, 1447, 1397, 1334, 1237, 1149, 1043, 750 cm–1; 1H NMR
(400 MHz, CDCl3): d 2.32 (s, 3H, CH3), 3.80 (s, 3H, OCH3), 6.03 (s, 1H, CH), 6.52
(s, 1H, CH), 6.81-7.03 (m, 2H, Ar-H), 7.16 (d, 1H, J ¼ 8.4 Hz, Ar-H), 7.20 (d, 2H,
J ¼ 8.0 Hz, Ar-H), 7.75-7.91 (m, 2H, Ar-H), 7.92 (d, 2H, J ¼ 8.0 Hz, Ar-H), 7.95-8.46
(m, 2H, Ar-H), 9.34-9.37 (m, 1H, Ar-H) ppm; 13C NMR (100 MHz, CDCl3): d 21.4
(CH3), 35.3 (CH), 55.7 (OCH3), 98.4, 102.1, 115.4, 117.8, 122.6, 124.7, 128.6, 129.1,
129.3, 129.6, 129.9, 130.2, 130.6, 131.6, 140.2, 141.8, 142.6, 146.2, 146.7, 157.2,
158.4, 160.3, 162.1 (Colefinic and Carom), 166.8 (C ¼ O) ppm; MS (m/z, %): 472
(Mþ, 12).
Anal. Calcd for C30H20N2O4: C, 76.26; H, 4.27; N, 5.93. Found: C, 76.52; H, 4.18;
N, 6.14.
16-(3,4-Dimethoxyphenyl)-3-methylbenzo[a]pyrano[3',4':5,6]pyrano[2,3- c]phenazin-
1(16H)-one (6j)
Red powder; yield 0.397 g (79%), m.p. 222-225 ꢀC; IR (KBr): ꢀmax ¼ 2905, 1696,
1649, 1623, 1582, 1504, 1447, 1398, 1341, 1228, 1137, 1023, 757 cm–1; 1H NMR
(400 MHz, CDCl3): d 2.32 (s, 3H, CH3), 3.81 (s, 3H, OCH3), 3.89 (s, 3H, OCH3), 6.07
(s, 1H, CH), 6.55 (s, 1H, CH), 6.67-8.49 (m, 10H, Ar-H), 9.21 (dd, 1H, J1 ¼ 8.0 Hz,
J2 ¼ 1.2 Hz, Ar-H) ppm; 13C NMR (100 MHz, CDCl3): d 19.7 (CH3), 34.3 (CH), 55.8
and 56.2 (2OCH3), 96.5, 101.8, 110.4, 111.1, 118.8, 124.7, 126.2, 128.9, 129.3, 129.8,
130.1, 130.5, 131.2, 137.7, 140.6, 142.1, 145.4, 146.3, 147.7, 149.0, 158.6, 160.2, 162.4
(Colefinic and Carom), 166.9 (C ¼ O) ppm; MS (m/z, %): 502 (Mþ, 9).
Anal. Calcd for C31H22N2O5: C, 74.09; H, 4.41; N, 5.57. Found: C, 74.31; H, 4.69;
N, 5.44.

8
Mohebat et al.
Acknowledgment
We gratefully acknowledge financial support from the Research Council of the Islamic
Azad University of Yazd.
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