Microwave-Assisted and L-proline catalysed domino cyclisation in an aqueous medium: A rapid, highly efficient and green synthesis of benzo[a]phenazine annulated heterocycles

Article abstract of DOI:10.3184/174751916X14787124908891

A highly efficient one-pot, two-step microwave-Assisted procedure was applied for the rapid and green synthesis of benzo[a]phenazine annulated heterocyclic ring systems from the three- or four-component condensation reactions of 2-hydroxynaphthalene-1,4-d

Full text of DOI:10.3184/174751916X14787124908891

722 RESEARCH PAPER
VOL. 40 DECEMBER, 722–726
JOURNAL OF CHEMICAL RESEARCH 2016
Microwave-assisted and L-proline catalysed domino cyclisation in an aqueous
medium: a rapid, highly efficient and green synthesis of benzo[a]phenazine
annulated heterocycles
Afshin Yazdani-Elah-Abadia*, Razieh Mohebatb and Mehrnoosh Kanganic
aYoung Researchers and Elite Club, Yazd Branch, Islamic Azad University, Yazd, Iran
bDepartment of Chemistry, Yazd Branch, Islamic Azad University, Yazd, Iran
cYoung Researchers and Elite Club, Zahedan Branch, Islamic Azad University, Zahedan, Iran
A highly efficient one-pot, two-step microwave-assisted procedure was applied for the rapid and green synthesis of benzo[a]phenazine
annulated heterocyclic ring systems from the three- or four-component condensation reactions of 2-hydroxynaphthalene-1,4-dione,
o-phenylenediamine, aromatic aldehydes and 1,3-indandione using L-proline as a bifunctional organocatalyst in water. This new
procedure has a number of advantages such as high yields, very short reaction times, operational simplicity, simple work-up procedures
and avoidance of hazardous or toxic catalysts and organic solvents. Moreover, the catalyst can be recovered and reused several times
without much loss of its performance.
Keywords: multi-component domino reactions, microwave irradiation, benzo[a]phenazine derivatives, L-proline, green chemistry
Organocatalysis has emerged as a powerful methodology
in organic synthesis for the synthesis of simple and complex
bioactive heterocycles1–6 due to the catalysts’ stability, lack
of sensitivity to moisture and oxygen, ready availability, low
cost, lesser toxicity and metal-free reaction conditions. Among
organocatalysts, L-proline is a readily obtainable naturally
occurring amino acid and is easy to obtain in high enantiomeric
purity. It has been reported as an eco-friendly catalyst for the
synthesis of several heterocycles.7–12
In recent years, use of natural materials as promising catalysts
in organic reactions has received considerable attention due to
their green credentials.13,14 Also, the replacement of hazardous
solvents with environmentally benign solvents15–17 is one of the
major focus areas of green chemistry. Organic solvents have
destructive effects on the environment.18 Thus, aqueous phase
organic synthesis has attracted the attention of chemists as it
overcomes the harmful effects associated with organic solvents
and is environmentally benign. Moreover, using water as the
medium, surfactants can be used to build micelles and provide
better chemical yields and shorter reaction times due to water’s
strong hydrogen bonding ability, hydrophobic effects and
water’s high polarity.19–21
biologically important organic frameworks. These processes
avoid the isolation and purification of intermediates, give
higher productivity, minimise solvent waste and enhance
the greenness of the transformations.22–25 Also, microwave-
assisted organic synthesis has become a very valuable tool,
improving the outcome of multi-component reactions26 because
microwave heating is able to minimise side reactions, increase
yields, reduce reaction times, improve reproducibility and even
enable reactions inaccessible by conventional heating and it is
particularly useful for the preparation of various biologically
active heterocyclic compounds.27
Therefore, the design of novel MDRs for the synthesis of
diverse heterocycles has remained as an important topic for
medicinal and organic chemists. Functionalised nitrogen- and
oxygen-containing heterocyclic molecules play key roles in
medicinal chemistry.28,29 Among them, phenazine systems are
an important class of aza-polycyclic compounds that exist in
natural and synthetic products showing a variety of biological
functions, including antibiotic, antimicrobial, antimalarial and
antiparasitic activities.30–33 By virtue of their DNA-intercalating
ability, they exhibit antitumour activity in leukaemia and
towards solid tumours. For example, pyridophenazinediones
and pyridazinophenazinedione derivatives are known for their
antitumour activities.34,35
To make economic savings and prevent pollution multi-
component domino reactions (MDRs), in which more than
two components are combined in a single synthetic operation,
have considerable interest for the synthesis of chemically and
With our continued interest in multi-component reactionsand
our ongoing programme for the synthesis of heterocyclic systems
R
One-Pot
No separation and purification
O
N
O
N
O
5
O
H
O
OH
O
N
O
6a-l
4
O
N
1
L-Proline
R
R
+
O
O
H2O, MW
H2O, MW
NH2
NH2
H
O
3
H
N
O
O
N
1
2
O
7a-m
Scheme 1 Synthesis of benzo[a]pyrano[2,3-c]phenazine and benzo[a]chromeno[2,3-c]phenazine derivatives39,40 in the presence of L-proline as a
bifunctional organocatalyst in H2O under MW.
* Correspondent. E-mail: afi_yazdani@yahoo.com

JOURNAL OF CHEMICAL RESEARCH 2016 723
using green chemistry36–40 and considering the significance
of phenazine, pyran and chromene derivatives, here we report
an efficient and green synthesis of benzo[a]pyrano[2,3-c]
phenazines39 and benzo[a]chromeno[2,3-c]phenazines40 in the
presence of L-proline as a bifunctional organocatalyst under
microwave irradiation (MW) with a power of 180 W and a
maximum temperature of 70 °C in H2O (Scheme 1).
indeno[2’,1’:5,6]pyrano[2,3-c]phenazin-16-yl)benzonitrile
(6a) or 4-(11,16-dioxo-16,17-dihydro-11H-benzo[a]benzo[6,7]
chromeno[2,3-c]phenazin-17-yl)benzonitrile (7a) in 10 min in
91% and 94% yields respectively (Table 1, entry 10). Increasing
the amount of L-proline to more than 30 mol% showed
no substantial improvement in the yield, whereas the yield
decreased on decreasing the amount of the catalyst to 10 mol%.
Moreover, the reaction did not proceed efficiently in the absence
of L-proline even after 20 min under MW. In this experiment
no other solvents were tested because of the green chemistry
concept.
With these optimised conditions we tested the method for
a variety of aromatic aldehydes having electron-withdrawing
and electron-donating groups. In all cases the products were
obtained in good to high yields (Table 2). Also, the reactions
were examined with aliphatic aldehydes such as n-heptanal and
n-octanal but the related products were not obtained in these
reaction conditions even after 20 min (Table 2, entries 13, 14,
28 and 29).
Results and discussion
In this paper, our initial efforts focused on the search to find
optimised conditions for the one-pot domino synthesis of
benzo[a]phenazine annulated heterocycles. For this purpose,
the condensation reaction between 2-hydroxynaphthalene-
1,4-dione (1) (1 mmol), o-phenylenediamine (2) (1 mmol),
4-cyanobenzaldehyde (4) (1 mmol) and 1,3-indandione (5) or
2-hydroxynaphthalene-1,4-dione (1) (1 mmol) was selected as
a model reaction in the presence of different catalytic systems
under both conventional heating and MW (Scheme 2) and the
results are summarised in Table 1. After extensive screening,
we found that the optimised best yields and time profiles
were obtained when the reaction was carried out in the
presence of 20 mol% of L-proline under MW with a power of
180 W and a maximum temperature of 70 °C in H2O, which
afforded the corresponding 4-(15-oxo-15,16-dihydrobenzo[a]
We also investigated the recycling of the catalyst
under the reaction conditions using a model reaction of
2-hydroxynaphthalene-1,4-dione,
o-phenylenediamine,
4-cyanobenzaldehyde and 1,3-indandione. After completion
of the reaction, the crude solid product was filtered off and
CN
O
N
O
H
O
N
O
O
5
O
H
O
O
4
N
O
6a
N
CN
1
H2O
CN
H O, or MW
+
O
O
or MW
∆
∆
2
NH2
NH2
H
O
3
H
N
O
O
N
1
2
O
7a
Scheme 2 The model reaction for optimising conditions for the synthesis of benzo[a]phenazine annulated heterocycles.
Table 1 Optimisation of the reaction conditions for the synthesis of 6a and 7a
Conventional heatinga
Microwave irradiationb
Entry
Catalyst/mol%
Yieldc/%
Yieldc/%
T/°C
Time /min
Powerd /W
Time /min
6a
7a
71
43
51
32
Nil
6a
7a
78
65
64
60
Trace
25
58
47
93
1
2
3
4
5
6
7
8
Glycine (20)
100
100
100
100
100
100
100
100
100
70
120
120
120
120
120
120
120
120
120
180
240
120
120
300
67
54
50
53
Nil
Trace
48
23
72
65
300
300
300
300
300
300
300
300
300
180
100
180
180
180
7
7
80
71
L-Histidine (20)
L-Serine (20)
L-Threonine (20)
L-Leucine (20)
L-Methionine (20)
L-Cysteine (20)
L-Alanine (20)
L-Proline (20)
L-Proline (20)
L-Proline (20)
L-Proline (30)
L-Proline (10)
No catalyst
7
50
7
62
7
7
7
Trace
Trace
55
28
56
44
77
73
64
78
7
40
9
7
91
10
11
12
13
14
10
15
10
10
20
91
76
90
78
94
84
92
83
40
57
70
51
Trace
100
100
100
45
Trace
Trace
Trace
aThe reaction was carried out under thermal conditions (Δ) in H2O.
bThe reaction was carried out under MW conditions in H2O.
cIsolated yields.
dThe reaction was tested at different microwave powers between 100 and 300 W and temperatures between 40 and 100 °C.

724 JOURNAL OF CHEMICAL RESEARCH 2016
Table 2 Preparation of benzo[a]phenazine annulated heterocycles in the presence of L-proline (20 mol%) as catalyst under MW conditions with a power
of 180 W and a maximum temperature of 70 °C in H2O
Entry
1
2
3
4
5
6
7
8
Aldehyde
4-CNC6H4
4-ClC6H4
2-ClC6H4
4-NO2C6H4
3-NO2C6H4
3-CNC6H3
4-Cl-3-NO2C6H3
4-CH3OC6H4
3-CH3OC6H4
3,4-(CH3O)2C6H3
2-OH-5-NO2C6H3
2-OH-3-CH3OC6H3
n-Heptanal
n-Octanal
4-CNC6H4
4-ClC6H4
2-ClC6H4
2,4-Cl2C6H3
4-NO2C6H4
3-NO2C6H4
2-NO2C6H4
3-CNC6H3
4-CH3C6H4
4-CH3OC6H4
2-OH-3-CH3OC6H3
2-OH-5-NO2C6H3
5-Br-2-OHC6H3
n-Heptanal
n-Octanal
CH acid
Product
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
–
–
7a
7b
7c
7d
7e
7f
7g
7h
7i
7j
7k
7l
7m
–
–
Time/min
10
10
10
10
10
12
Yield/%a
91
M.p. (Obs)/°C
240
M.p. (Lit)/°C
Present work
261–26339
296–29839
250–25239
234–23539
230–23239
243–24539
Present work
290–29239
246–24739
227–22939
248–25039
–
5
5
5
5
5
5
5
5
5
5
5
5
5
5
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
94
93
93
91
90
92
88
86
85
87
83
NR
NR
94
95
92
93
94
91
90
90
90
85
85
88
85
NR
NR
262–263
295–297
248–249
234–235
234–235
242–244
273–275
291–292
247
12
12
12
12
15
15
20
20
10
10
10
10
10
10
10
10
12
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
225–227
250–252
–
–
–
315–317
324
335–338
330–332
270–271
370
291–292
289–291
336–338
339–341
319–320
365–367
357–259
–
Present work
324–32640
336–33840
330–33240
273–27540
368–37040
293–29540
289–29140
333–33540
341–34240
Present work
364–36640
359–36140
–
12
15
15
15
20
20
–
–
aIsolated yields.
washed with H2O (2 × 5 mL). The L-proline was removed from
the reaction media by washing with H2O, since the catalyst is
soluble in water. The catalyst was recovered by evaporation
of the water and washed with diethyl ether and reused for the
subsequent catalytic runs. The catalytic system worked well up
to five catalytic runs (Fig. 1).
Inordertoassesstheefficiencyandgeneralityofthismethodology,
the result obtained from the reaction of 2-hydroxynaphthalene-
1,4-dione, o-phenylenediamine and 4-chlorobenzaldehyde with
1,3-indandione or 2-hydroxynaphthalene-1,4-dione by this method
has been compared with those of the previously reported methods
(Table 3). It was found that the present method is convincingly
superior to the reported methods with respect to reaction time and
exhibits broad applicability in terms of yields.
92
90
88
86
84
82
80
78
76
Run 1
91
Run 2
89
Run 3
88
Run 4
85
Run 5
82
The probable mechanism for the domino synthesis of benzo[a]
phenazine annulated heterocyclic compounds 6 and 7 using
L-proline is given in Scheme 3 and is similar to the literature.39,40
On the basis of this mechanism, the primary condensation of
Product/%
Fig. 1 Investigation of the recycling of L-proline.
Table 3 Comparison of the efficiency of L-proline with other reported catalysts in the literature
Entry
Product
Catalyst/Condition
Time/min
120 min
10 min
Yield/%a
89
Ref.
1
2
4
5
6b
6b
7b
7b
Oxalic acid/EtOH/H2O (1:1), Reflux
L-Proline/H2O, 180 W, max. 70 °C (MW)b
PTSA/PEG-400, 80 °C
Previous work39
Present work
Previous work40
Present work
94
120 min
10 min
91
L-Proline/H2O, 180 W, max. 70 °C (MW)b
95
aIsolated yields.
bThe reaction was carried out under MW conditions.

JOURNAL OF CHEMICAL RESEARCH 2016 725
O
COO
N
O
Ar
Ar
H
Ar
4
H
5, 1
Ar
O
O
H
O
H
N
N
O
C
O
N
O
H
N
H
N
COOH
N
O
COOH
N
H
Ar
COOH
N
H
O
H
O
O
8
N
Ar
N
Ar
Ar
H
N
N
N
1
O
+
O
O
H
O
O
C
H2N
H2N
N
N
H
O
9
6, 7
H
2
OH
3
Scheme 3 Proposed mechanism for the synthesis of benzo[a]phenazine annulated heterocyclic ring systems.
UV 254 plates. All reagents and solvents were purchased from Merck
or Aldrich and used without further purification.
2-hydroxynaphthalene-1,4-dione (1) with o-phenylenediamine
(2) in the presence of L-proline gives benzo[a]phenazin-5-ol
(3). Knoevenagel condensation of aromatic aldehyde 4 with
C–H acids 5 or 1 affords an intermediate 8, which undergoes
Michael addition with 3 to form intermediate 9. The enolate
O-atom of the formed intermediate 9 attacks the C=O group
and a subsequent H-atom shift leads to compounds 6 or 7. In
this mechanism, L-proline plays a dual role; activation of the
C=O group occurs by H-bond formation between one H-atom
of L-proline and the O-atom of the C=O group. Furthermore,
the C–H acids 5 and 1 are activated through deprotonation by
L-proline resulting in a strong nucleophile.
Synthesis of benzo[a]pyrano[2,3-c]phenazine and benzo[a]
chromeno[2,3-c]phenazine derivatives; general procedure
L-Proline (20 mol%) was added to a mixture of 2-hydroxynaphthalene-
1,4-dione (1) (1 mmol) and o-phenylenediamine (2) (1 mmol) in H2O
(10 mL) and this mixture was irradiated in a microwave oven at 180
W until, in less than 3 min, an orange solid of benzo[a]phenazine-5-ol
(3) was formed. The microwave was programmed to give a maximum
internal temperature of 70 °C. Then, an aryl aldehyde 4 (1 mmol) and
1,3-indandione (5) (1 mmol) or 2-hydroxynaphthalene-1,4-dione
(1) (1 mmol) were added to the above reaction mixture which was
irradiated further at the same temperature (with a power of 180 W
and a maximum temperature 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, the
crude solid product was filtered for separation of product and washed
with H2O (2 × 5 mL) to remove the catalyst. The resulting product was
subsequently recrystallised from hot ethanol to give the pure solid 6 or
7. The analytical and spectroscopic data for the unknown compounds
are as follows.
Conclusion
In conclusion, L-proline is a convenient, efficient and
bifunctional organocatalyst for the three- and four-
component assembling of 2-hydroxynaphthalene-1,4-dione,
o-phenylenediamine, aromatic aldehydes and 1,3-indandione
under MW in H2O. The procedure utilises simple equipment,
is easily carried out and is valuable from the viewpoint of
diversity-oriented large-scale processes. The results obtained
demonstrate a combination of the synthetic virtues of MDR
processes with ecological benefits. The catalyst shows an
environmentally friendly character: it is inexpensive, clean,
safe, non-toxic and easily obtained and reused. Moreover, the
procedure offers several advantages including high yields,
operational simplicity, clean reaction conditions and the
minimum pollution of the environment, which make it a useful
and attractive process for the synthesis of these compounds.
4-(15-Oxo-15,16-dihydrobenzo[a]indeno[2’,1’:5,6]pyrano[2,3-c]
phenazin-16-yl)benzonitrile (6a): Brown solid; yield 91% (0.443 g);
m.p. 240 °C; IR (KBr) (νmax, cm–1): 2990, 2205, 1691, 1616, 1594,
1
1528, 1452, 1401, 1337, 1233, 1123, 973, 755; H NMR (400 MHz,
DMSO-d6): δH 5.97 (s, 1H, CH), 7.56 (d, 2H, J = 6.0 Hz, ArH), 7.74 (d,
2H, J = 8.4 Hz, ArH), 7.80–7.94 (m, 6H, ArH), 8.14 (d, 1H, J = 8.4 Hz,
ArH), 8.21–8.27 (m, 2H, ArH), 8.30 (d, 1H, J = 8.0 Hz, ArH), 8.54 (d,
1H, J = 8.0 Hz, ArH), 9.16 (dd, 1H, J1 = 8.0 Hz, J2 = 1.2 Hz, ArH);
13C NMR (100 MHz, DMSO-d6): δC 35.8, 109.2, 113.9, 118.8, 122.0,
122.2, 122.9, 123.6, 124.7, 124.8, 127.4, 128.4, 128.7, 129.0, 129.1,
129.2, 129.7, 130.1, 130.2, 130.4, 130.7, 130.8, 132.2, 133.6, 136.5,
139.3, 139.9, 141.5, 141.7, 148.4, 150.3, 152.3, 199.7. Anal. calcd for
C33H17N3O2: C, 81.30; H, 3.51; N, 8.62; found: C, 81.52; H, 3.44; N,
8.80%. MS (m/z, %): 487 (M+, 12).
16-(4-Methoxyphenyl)benzo[a]indeno[2’,1’:5,6]pyrano[2,3-c]
phenazin-15(16H)-one (6h): Yellow solid; yield 88% (0.433 g); m.p.
273–275 °C; IR (KBr) (νmax, cm–1): 3025, 1671, 1613, 1587, 1528, 1446,
1400, 1337, 1239, 1177, 954, 752; 1H NMR (400 MHz, DMSO-d6): δH
3.64 (s, 3H, OCH3), 5.90 (s, 1H, CH), 6.98 (d, 2H, J = 8.0 Hz, ArH),
7.11-7–14 (m, 2H, ArH), 7.39–7.42 (m, 1H, ArH), 7.79–7.94 (m,
6H, ArH), 8.17 (d, 1H, J = 8.0 Hz, ArH), 8.26–8.32 (m, 2H, ArH),
8.58–8.61 (m, 1H, ArH), 9.18 (d, 1H, J = 6.8 Hz, ArH); 13C NMR (100
MHz, DMSO-d6): δC 35.5, 55.7, 110.1, 113.3, 114.4, 122.1, 122.7, 122.8,
Experimental
All melting points were determined on an Electrothermal 9100
apparatus and are uncorrected. IR spectra were recorded on a
Shimadzu IR-470 spectrometer. Elemental analyses for C, H, and
N were performed using a Heraeus CHN-O-Rapid analyser at the
Iranian Central Research of Petroleum Company. Mass spectra were
recorded on an Agilent Technology (HP) spectrometer operating at
1
an ionisation potential of 70 eV. The H nuclear magnetic resonance
(NMR) and 13C NMR spectra were recorded on Bruker DRX-400
Avance instruments with deuterated dimethyl sulfoxide (DMSO-d6) as
solvent. 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/

726 JOURNAL OF CHEMICAL RESEARCH 2016
7
8
9
H. Mecadon, Md. Rumum, I. Kharbangar, B.M. Laloo, I. Kharkongor, M.
Rajbangshi and B. Myrboh, Tetrahedron Lett., 2011, 52, 3228.
C. Mukhopadhyay, P.K. Tapaswi and R.J. Butcher, Tetrahedron Lett., 2010,
51, 1797.
J.G. Hernández, V. García-López and E. Juaristi, Tetrahedron, 2012, 68,
92.
123.0, 124.5, 124.7, 126.9, 127.8, 128.1, 128.4, 128.7, 129.2, 129.5,
129.7, 130.0, 130.2, 130.7, 130.8, 130.9, 131.7, 135.5, 135.6, 136.9,
138.7, 139.4, 141.0, 141.6, 145.7, 150.5, 151.9, 196.1. Anal. calcd for
C33H20N2O3: C, 80.47; H, 4.09; N, 5.69; found: C, 80.57; H, 3.95; N,
5.78%. MS (m/z, %): 492 (M+, 9).
4- (11,16-Dioxo-16,17-dihydro-11H-benzo[a]benzo[6,7]
chromeno[2,3-c]phenazin-17-yl)benzonitrile (7a): Yellow solid; yield
94% (0.484 g); m.p. 315–317 °C; IR (KBr) (νmax, cm–1): 3035, 2200,
10 J. Pandey, N. Anand and R.P. Tripathi, Tetrahedron, 2009, 65, 9350.
11 C. Shi, H. Chen and D. Shi, J. Heterocycl. Chem., 2012, 49, 125.
12 D.S. Raghuvanshi and K.N. Singh, J. Heterocycl. Chem., 2010, 47, 1323.
13 N. Hazeri, M.T. Maghsoodlou, F. Mir, M. Kangani, H. Saravani and E.
Molashahi, Chin. J. Catal., 2014, 35, 391.
1
1689, 1660, 1637, 1590, 1495, 1356, 1286, 1164, 1048, 759; H NMR
(400 MHz, DMSO-d6): δH 5.87 (s, 1H, CH), 7.58 (d, 2H, J = 8.4 Hz,
ArH), 7.69 (d, 2H, J = 8.4 Hz, ArH), 7.76 (t, 1H, J = 7.6 Hz, ArH),
7.85–7.89 (m, 3H, ArH), 7.95 (t, 2H, J = 7.6 Hz, ArH), 8.04 (dd, 1H,
J1 = 7.6 Hz, J2 = 1.2 Hz, ArH), 8.12–8.16 (m, 2H, ArH), 8.38 (d, 1H,
J = 7.6 Hz, ArH), 8.58 (d, 1H, J = 8.0 Hz, ArH), 9.09 (d, 1H, J = 8.0 Hz,
ArH); 13C NMR (100 MHz, DMSO-d6): δC 34.2, 109.1, 113.5, 114.6,
118.5, 122.3, 124.8, 125.3, 128.6, 129.0, 129.3, 129.6, 130.0, 130.2,
130.4, 130.5, 130.8, 130.9, 131.7, 134.6, 135.1, 139.9, 140.1, 140.7, 141.4,
144.5, 146.0, 148.7, 156.1, 176.9, 177.7. Anal. calcd for C34H17N3O3: C,
79.21; H, 3.32; N, 8.15; found: C, 79.44; H, 3.50; N, 8.21%. MS (m/z,
%): 515 (M+, 5).
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17- (2-Hydroxy-3-methoxyphenyl)-11H-benzo[a]benzo[6,7]
chromeno[2,3-c]phenazine-11,16(17H)-dione (7k): Brown solid;
yield 85% (0.456 g); m.p. 319–320 °C; IR (KBr) (νmax, cm–1): 3040,
1
1686, 1658, 1638, 1589, 1509, 1360, 1274, 1161, 1049, 749; H NMR
(400 MHz, DMSO-d6): δH 3.71 (s, 3H, OCH3), 5.80 (s, 1H, CH), 6.45
(d, 1H, J = 8.4 Hz, ArH), 6.63 (dd, 1H, J1 = 8.4 Hz, J2 = 2.0 Hz, ArH),
7.27 (d, 1H, J = 1.6 Hz, ArH), 7.72 (t, 1H, J = 7.2 Hz, ArH), 7.80 (t, 1H,
J = 7.6 Hz, ArH), 7.83–7.94 (m, 5H, ArH, OH), 8.02 (d, 1H, J = 7.6 Hz,
ArH), 8.14 (d, 1H, J = 8.4 Hz, ArH), 8.20 (d, 1H, J = 8.0 Hz, ArH),
8.33 (d, 1H, J = 7.6 Hz, ArH), 8.50 (d, 1H, J = 7.6 Hz, ArH), 9.05 (d,
1H, J = 8.0 Hz, ArH); 13C NMR (100 MHz, DMSO-d6): δC 32.8, 55.5,
113.9, 114.9, 115.3, 116.0, 120.3, 122.1, 124.5, 124.7, 125.5, 128.6, 128.7,
128.9, 129.0, 129.7, 129.9, 130.1, 130.3, 130.6, 130.8, 131.4, 134.4,
135.3, 139.9, 140.1, 140.5, 141.4, 144.9, 145.4, 146.5, 155.9, 177.2, 178.0.
Anal. calcd for C34H20N2O5: C, 76.11; H, 3.76; N, 5.22; found: C, 76.27;
H, 3.99; N, 5.50%. MS (m/z, %): 536 (M+, 11).
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Acknowledgements
33 D.V. Mavrodi, T.L. Peever, O.V. Mavrodi, J.A. Parejko, J.M. Raaijmakers,
P. Lemanceau, S. Mazurier, L. Heide, W. Blankenfeldt, D.M. Weller and
L.S. Thomashow, Appl. Environ. Microbiol., 2010, 76, 866.
34 H.J. Lee, J.S. Kim, S.Y. Park, M.E. Suh, H.J. Kim, E.K. Seo and C.O. Lee,
Bioorg. Med. Chem., 2004, 12, 1623.
We gratefully acknowledge financial support from the Research
Council of Young Researchers and Elite Club, Yazd Branch,
Islamic Azad University, Yazd, Iran.
Received 23 August 2016; accepted 20 October 2016
Paper 1604276 doi: 10.3184/174751916X14787124908891
Published online: 14 November 2016
35 J.S. Kim, H.-K. Rhee, H.J. Park, I.-K. Lee, S.K. Lee, M.-E. Suh, H.J. Lee,
C.-K. Ryu and H.-Y. Park Choo, Bioorg. Med. Chem., 2007, 15, 451.
36 R. Mohebat, A. Yazdani-Elah-Abadi, A. Soltani and M. Saghafi,
ARKIVOC, 2016, iv, 1.
37 R. Mohebat, A. Yazdani-Elah-Abadi and M.-T. Maghsoodlou, Res. Chem.
Intermed., 2016, 42, 6039.
38 A. Yazdani-Elah-Abadi, M.-T. Maghsoodlou, R. Heydari and R. Mohebat,
Res. Chem. Intermed., 2016, 42, 1227.
39 R. Mohebat, A. Yazdani-Elah-Abadi, M.-T. Maghsoodlou, M. Mohammadi
and R. Heydari, Res. Chem. Intermed., 2016, 42, 7121.
40 R. Mohebat, A. Yazdani-Elah-Abadi, M.-T. Maghsoodlou and M.
Mohammadi, Res. Chem. Intermed., 2016, 42, 5915.
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