Synthesis of 2,4,5-triaryl-5H-chromeno[4,3-b]pyridines in ionic liquid

Article abstract of DOI:10.3987/COM-08-11500

The synthesis of 2,4,5-triaryl-5H-chromeno[4,3-b]pyridines via a three-component one-pot cascade reaction of 2-hydroxyacetophenone, aromatic aldehyde and ammonium acetate in ionic liquid [BMIM][BF₄] was reported.

Full text of DOI:10.3987/COM-08-11500

HETEROCYCLES, Vol. 78, No. 2, 2009
357
HETEROCYCLES, Vol. 78, No. 2, 2009, pp. 357 - 367. © The Japan Institute of Heterocyclic Chemistry
Received, 21st July, 2008, Accepted, 14th October, 2008, Published online, 16th October, 2008.
DOI: 10.3987/COM-08-11500
SYNTHESIS OF 2,4,5-TRIARYL-5H-CHROMENO[4,3-b]PYRIDINES IN
IONIC LIQUID
Hui Wu,a,b,* Yu Wan,a,b Xiu-mei Chen,a Lei-lei Lu,c Yang Shen,a Cai-fa Chen,b
Hai-qiang Xin,a Hua-hong Xu,a Li-ling Pang,a Rui Ma,a and Cai-hui Yuea
a
School of Chemistry and Chemical Engineering, Xuzhou Normal University,
Xuzhou, 221116, P. R. China; b Key Laboratory of Biotechnology on Medical Plant
of Jiangsu Province, Xuzhou, 221116, P. R. China; c Department of Chemical and
Textile Engineering, Jiangyin Polytechnic College, Jiangyin, Jiangsu, 214405, P. R.
China. E-mail: wuhui72@yahoo.com.cn
Abstract – The synthesis of 2,4,5-triaryl-5H-chromeno[4,3-b]pyridines via a
three-component one-pot cascade reaction of 2-hydroxyacetophenone, aromatic
aldehyde and ammonium acetate in ionic liquid [BMIM][BF4] was reported.
INTRODUCTION
5H-chromeno[4,3-b]pyridines have some important biological activities such as analgesic,
anti-inflammation and antibacterial.1,2 Accordingly, the development of efficient synthetic strategies for the
construction of this molecular architecture is of considerable importance from the standpoint of the material
and organic chemistry. By far, for its complex structure, few approaches for obtaining
5H-chromeno[4,3-b]pyridines have been reported. The usually used one was mainly based on the
multi-step intramolecular oxaza- or diaza-Diels-Alder cycloadditions1 with some shortcomings such as
low yields, high reaction temperature (180-200 ˚C), long reaction time (48h2) and requirement of toxic
solvents. Moreover, unavailable starting material such as 3-benzylidenechroman-4-one, or neutral
2-azadienes or 2-[2-(prop-2-ynyloxy)phenyl]pyridine2 was required. In other approaches,3 it is the product
of the primary 1,4-addition followed by the pyrone ring-opening, attack of the NH2 group to the carbonyl
bound with the aromatic cycle, and ring-closure involving the phenolic hydroxyl and aldehyde group.
During the past decade, ionic liquids have gained increasing attention for performing all types of reaction
with sometimes remarkable results.4,5

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The reaction of aromatic aldehyde (1) and 2-hydroxyacetophenone (2) under different reaction conditions
can give interesting different products (Scheme 1). In our previous work,6 1 and 2 (mol ratio = 1:2)
reacted at 80 ˚C catalyzed by morpholine (pKb=5.51) in ionic liquid [BMIM][BF4] afford
1,3,5-triaryl-1,5-diketones (A, 58-80%). But when morpholine was replaced with ammonium acetate (pKb
[OAc]-= 9.25), which can not catalyze the same reaction and so act as reagent, we could obtain
2,4,6-triaryl-1,4-dihydropyridines (C, 44-78%) selectively under the same conditions.7 Moreover, when
acetic acid (HOAc) was used as catalyst, 2,4,6-triarylpyridine (4) could be given at 80oC in ionic liquid
[BMIM][BF4]8 (Scheme 1).
R
R
OH
OH
OH
OH
4
CHO
O O
N
H
A
O
C
OH
R
R
1
R
R
4
[BMIM][BF4]
2
O
OH
OH
N
N
OH
3
4
Scheme 1
In the present work, the one-pot three-component cascade reaction of equivalent of 1 and 2 with 5 equiv.
of ammonium acetate (1:1:5) in ionic liquid [BMIM][BF4] at 120 ˚C without any catalyst afforded
2,4,5-triaryl-5H-chromeno[4,3-b]pyridines (Scheme 2). Up to nine new bonds and two new rings were
formed in one-pot with water as the only one by-product in this reaction. Bogner and co-workers9 have
ever synthesized 3a (R=H) with troublesome procedure, but their work can obtain only one compound of
this series.
R
R
OH
O
CHO
[BMIM][BF4] (2 mL)
NH4OAc (5 equiv.)
4H2O
+
O
+
2
2
120 oC, 12h
N
R
OH
1
2
3
Scheme 2. Synthesis of triaryl-5H-chromeno[4,3-b]pyridines

HETEROCYCLES, Vol. 78, No. 2, 2009
359
RESULTS AND DISCUSSION
Initially, we screened various reaction conditions for the reaction of 4-cyanobenzaldehyde (2.0 mmol),
2-hydroxyacetophenone (2.0 mmol) and ammonium acetate and the results were summarized in Table 1.
It was shown that when common organic solvents and water were used as solvent, no desired product was
checked (Table 1, entries 1-5). It may be because those classical organic solvents, such as acetone which
has no catalysis on this reaction, could only give some cross aldol condensations products, and
meanwhile water derived the equilibrium toward reactants. And these low-boiling solvents can not offer
enough energy to afford desired product which may be a thermodynamic controlled ones. However, when
using ionic liquid [BMIM][Br]10 as reaction medium (Table 1, entry 6), the desired product
triaryl-5H-chromeno[4,3-b]pyridines 3 was isolated in 32% yield, which indicated the significant role in
controlling this multi-component reaction as solvent and catalyst of ionic liquids. The best result was
Table 1. Optimization of the reaction of 4-cyanobenzaldehyde, 2-hydroxyacetophenone and ammonium
acetate.a
Isolated yield
Entry
Temp. (oC)
Solvent
Time (h)
(%)
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
9
1
2
120
neat
no reaction
refluxing temp.
acetone
no product 3
3
refluxing temp.
EtOH
no product 3
4
120
DMF
no product 3
5
refluxing temp.
H2O
no reaction
6
120
120
120
120
120
120
80
[BMIM][Br]
[BMIM][BF4]
[BMIM][ClO4]
[BPY][Br]b
[BPY][BF4]
[BPY][ClO4]
[BMIM][BF4]
[BMIM][BF4]
[BMIM][BF4]
[BMIM][BF4]
[BMIM][BF4]
[BMIM][BF4]
[BMIM][BF4]
[BMIM][BF4]
32
59
43
34
29
28
35
45
54
52
33
45
55
54
7
8
9
10
11
12
13
14
15
16
17
18
19
100
140
160
120
120
120
120
10
11
13
aAll reactions were carried out on a 2.0 mmol of aromatic aldehyde, 2.0 mmol of 2-hydroxyacetophenone,
5 equiv. of ammonium acetate in 2 mL of ionic liquid. b[BPY]=1-n-butylpridinum.

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obtained in [BMIM][BF4], which may be attribute to its strongest basicity among these six kinds of ionic
liquid (pKa[ClO4]-= -11, pKa[Br]- = -9, pKa[BF4]- = 0.5). It was also realized that the process was
o
o
efficiently facilitated at 120 C. When reaction temperature was 80 C, the yield of desired
2,4,5-triaryl-5H-chromeno[4,3-b]pyridine decreased (35%).
We applied this condition to other substrates and the results were summaried in Table 2. It showed the
electronic nature and steric effect of substituted group in aromatic aldehyde had some influenced on the
yield, electron donating substituents could enhance the yields, which implied the nucleophilic procedure
of the reaction.
Table 2. Synthesis of triaryl-5H-chromeno[4,3-b]pyridines.a
Isolated yield
Entry
R
Time (h)
Product
(%)
1
2
H
4-Me
12
10
10
13
12
15
14
13
12
13
14
11
13
11
3a
3b
3c
3d
3e
3f
75
78
81
52
68
59
62
70
73
60
63
66
64
64
3
4-MeO
4-Br
4
5
2,3-(MeO)2
4-CN
6
7
4-Cl
3g
3h
3i
8
2-MeO
3,4,5-(MeO)3
2-Cl
9
10
11
12
13
14
3j
3-Br
3k
3l
3,4-OCH2O
3-NO2
4-F
3m
3n
aAll reactions were carried out on a 2.0 mmol of aromatic aldehyde, 2.0 mmol of 2-hydroxyacetophenone,
5 equiv. of ammonium acetate in 2 mL of ionic liquid.
The X-ray structure of 3e was shown in Figure 1.11
On the basis of our previous works, 6-8 a reasonable mechanism for the formation of the products 3 were
outlined in Scheme 3. The reaction resembles to the synthesis of dihydropyridines or pyridines according
to Hantzsch.12 Firstly, 2-hydroxyacetophenones react with arylaldehyde to generate A, which further
undergoes nucleophilic addition-elimination (Adn-E) reaction of ammonia (deriving from ammonium
acetate) to give B then to C, which subsequently convert to D via Adn-E reaction of the second
arylaldehyde, D was easily etherified and dehydrogenated to the final product 3.

HETEROCYCLES, Vol. 78, No. 2, 2009
361
Figure 1. Molecular structure (X-ray diffraction data) of 3e.
R
R
R
O
-H2O
NH3,
OH
-H2O
OH
OH
Adn-E
Adn-E
N
O O
HO
NH2
OH
H
OH
A
B
C
H
C
R
O
-H2O
Adn-E
R
R
R
R
etherification
dehydrogenation
O
N
N
OH
HO
OH
3
D
Scheme 3. A possible mechanism for the formation of 3.
In summary, we have developed a novel simple, effective and catalysis free process for the preparation of
2,4,5-triaryl-5H-chromeno[4,3-b]pyridines in [BMIM][BF4]. Besides the advantages that all the reagents
were added at the beginning and the same reaction conditions were maintained throughout, the features of
this process include: (1) the starting materials are available; (2) the reaction has good atom-economy and
environmental friendliness: nine new bonds (three C-N bonds, one C-O bond, three C-C single bonds,
two C-C double bonds) and two new rings were formed in one-pot with water as the only one by-product
during the whole process. Indeed, the present protocol provides a straightforward and effective pathway
to afford triaryl-5H-chromeno[4,3-b]pyridines.
EXPERIMENTAL
1
Infrared spectra were obtained on a Bruker FT-IR spectrometer. H NMR spectra were recorded at 400

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13
MHz on a Bruker DPX 400 or AV 400 spectrometer. C NMR spectra were recorded at 100.6 MHz.
Mass spectra was determined by using a TOF-MS high resolution mass spectrometer. Thin layer
chromatography analysis was carried out on aluminium sheets of silica gel GF254. All reagents were
obtained from commercial suppliers and used without further purification unless otherwise stated.
Organic solvents were dried and/or distilled prior to use. The X-ray structure determination for complex
3e was given by Smartapex Bruke diffractometer.
Typical procedure for the preparation of triaryl-5H-chromeno[4,3-b]pyridines
A mixture of aromatic aldehyde 1 (2.0 mmol), 2-hydroxyacetophenone 2 (0.27 g, 2.0 mmol), ammonium
acetate (0.77 g, 10 mmol, 5 equiv.), and ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate
([BMIM][BF4]) (2.0 mL) was placed in a 25 mL flask and then heated at 120 °C with stirring for 10-15 h.
After completion of the reaction, as indicated by thin layer chromatography (TLC). The reaction mixture
was then quenched with water and the product 3 was isolated by filtration followed by purification through
simple recrystallization with DMF. Ionic liquids were prepared according to the literature.10
Spectra data of products:
2-(4,5-Diphenyl-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3a).
Yellow crystals, mp. 194.1-195.3 ˚C, (75%). 1H NMR (400 MHz, DMSO-d6): δ 13.80 (1H, s), 8.20 (1H,
d, J=8.4 Hz), 8.14 (1H, s), 8.01 (1H, d, J=8.0 Hz), 7.46 (3H, m), 7.36 (4H, m), 7.24 (3H, m), 7.11 (1H, t),
7.04 (2H, t), 7.02 (1H, d, J=9.6 Hz), 6.97 (2H, t), 6.50 (1H, s). 13C NMR (100 MHz, DMSO-d6): δ 161.50,
159.20, 156.51, 153.21, 148.00, 141.20, 139.20, 135.02, 134.50, 131.50, 131.39, 131.35, 131.24, 131.05,
130.80, 130.33, 126.40, 125.50, 125.31, 124.50, 123.40, 122.91, 122.82, 120.90, 120.50. IR (cm-1): 3310
(w), 3030 (s), 1600 (s), 1580 (m), 1031 (m). HRMS (ESI): m/z calcd. for C30H21NO2, 427.4932; found,
427.1554.
2-(4,5-Bis(4-methylphenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3b).
Yellow crystals, mp. 207.7-208.7 ˚C, (78%). 1H NMR (400 MHz, DMSO-d6): δ 14.70 (1H, s), 8.11 (1H,
dd, J1=1.6 Hz, J2=7.6 Hz ), 7.85 (1H, dd, J1=1.6 Hz, J2=7.6 Hz), 7.80 (1H, s), 7.33-7.37 (1H, t), 7.24-7.28
(1H, t), 7.18 (2H, d, J=7.6 Hz), 7.11-7.04 (4H, m), 7.02 (4H, s), 6.91-6.95 (1H, t), 6.88-6.85 (1H, dd,
J1=1.6 Hz, J2=7.6 Hz), 6.38 (1H, s,), 2.39 (3H, s,), 2.25 (3H, s,). 13C NMR (100 MHz, DMSO-d6): δ
159.98, 156.91, 154.25, 149.80, 145.99, 138.72, 138.24, 136.17, 134.16, 131.98, 131.64, 129.27, 129.10,
128.26, 127.92, 126.38, 124.28, 123.34, 122.29, 122.12, 119.25, 118.92, 118.81, 118.50, 118.10, 21.19,
21.07. IR (cm-1): 3310 (w), 3030 (s), 2985 (s), 1600 (s), 1550 (m), 1030 (m). HRMS (ESI): m/z calcd. for
C32H25NO2, 455.5464; found, 455.1871.

HETEROCYCLES, Vol. 78, No. 2, 2009
363
2-(4,5-Bis(4-methoxyphenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3c).
1
Brown crystals, mp. 191.2-192.4 ˚C, (81%). H NMR (400 MHz, DMSO-d6): δ 13.91 (1H, s), 8.18 (1H,
dd, J1=1.6 Hz, J2=7.6 Hz), 8.09 (1H, s), 8.00 (1H, dd, J1=1.6 Hz, J2=7.6 Hz), 7.39-7.32 (2H, m), 7.26 (2H,
d, J=7.6 Hz), 7.12-7.17 (1H, t), 6.90-7.07 (7H, m), 6.79-6.81 (2H, d, J=7.6 Hz), 6.45 (1H, s), 3.78 (3H, s),
3.65 (3H, s). 13C NMR (100 MHz, DMSO-d6): δ 159.99, 159.57, 156.92, 154.16, 149.44, 145.97, 132.00,
131.67, 131.35, 129.72, 129.47, 129.32, 126.39, 124.29, 123.53, 122.32, 122.16, 119.33, 118.95, 118.83,
118.54, 118.14, 114.02, 113.80, 55.34, 55.12. IR (cm-1): 3310 (w), 3030 (s), 2985 (s), 1610 (s), 1540 (m),
1020 (m). HRMS (ESI): m/z calcd. for C32H25NO4, 487.5452; found, 487.1771.
2-(4,5-Bis(4-bromophenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3d).
Yellow crystals, mp. 221.5-222.5 ˚C, (52%). 1H NMR (400 MHz, DMSO-d6): δ 13.65 (1H, s), 8.21 (1H,
d, J=9.6 Hz ), 8.15 (1H, s), 8.06 (1H, d, J=9.6 Hz), 7.67 (2H, d, J=8.0 Hz), 7.44 (2H, d, J=9.6 Hz),
13
7.33-7.41 (2H, m), 7.29 (2H, d, J=8.0 Hz), 7.14-7.21 (1H, t), 6.94-7.09 (5H, m), 6.47 (1H, s). C NMR
(100 MHz, DMSO-d6): δ 155.27, 152.83, 149.14, 143.88, 141.46, 138.00, 135.09, 133.12, 131.01, 127.71,
127.33, 127.27, 127.07, 125.13, 124.90, 121.74, 119.68, 118.72, 118.30, 118.05, 117.63, 117.00, 114.40,
114.29, 113.93, 113.80, 113.44. IR (cm-1): 3310 (w), 3030 (s), 2980 (s), 1600 (s), 1550 (m), 1010 (m).
HRMS (ESI): m/z calcd. for C30H19Br2NO2, 585.2854; found, 584.9760.
2-(4,5-Bis(2,3-dimethoxyphenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3e).
Yellow crystals, mp. 223.7-225.2 ˚C, (68%). 1H NMR (400 MHz, DMSO-d6): δ 13.95 (1H, s), 8.23 (1H,
d, J=8.0 Hz ), 8.15 (1H, s), 8.00 (1H, d, J =8.0 Hz), 7.33-7.41 (2H, m ), 7.13-7.18 (1H, t), 6.10-7.08 (6H,
m), 6.84 (1H, s), 6.77 (1H, d, J=8.0 Hz), 6.46 (1H, d, J=8.0 Hz), 6.44 (1H, s), 3.79 (3H, s), 3.67 (3H, s),
13
3.65 (3H, s), 3.52 (3H, s). C NMR (100 MHz, DMSO-d6): δ 159.00, 155.37, 154.30, 153.00, 152.90,
147.00, 145.50, 145.00, 132.80, 132.35, 131.80, 131.00, 128.30, 124.80, 123.90, 122.90, 121.90, 121.60,
120.90, 119.90, 119.50, 118.54, 118.00, 61.00, 60.50, 56.50, 56.00. IR (cm-1): 3310 (w), 3030 (s), 2986
(s), 1600 (s), 1560 (m), 1030 (m). HRMS (ESI): m/z calcd. for C34H35NO6, 547.5972; found, 547.1975.
2-(4,5-Bis(4-cyanophenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3f).
1
Yellow crystals, mp. >300 ˚C, (59%). H NMR (400 MHz, DMSO-d6): δ 13.50 (1H, s), 8.21 (1H, d,
J=8.0 Hz), 8.19 (1H, s), 8.03 (1H, d, J=7.6 Hz), 7.94 (2H, d, J=8.0 Hz), 7.71 (2H, d, J=8.0 Hz), 7.54 (2H,
d, J=8.0 Hz), 7.37-7.41 (2H, t), 7.30 (2H, d, J=8.0 Hz), 7.17-7.21 (1H, t), 6.96-7.04 (3H, t), 6.57 (1H, s).
13C NMR (100 MHz, DMSO-d6): δ 159.20, 156.85, 154.05, 149.55, 148.32, 148.05, 147.95, 147.90,
145.75, 133.05, 132.90, 132.30, 130.30, 128.50, 124.00, 123.30, 123.00, 122.90, 122.20, 122.10, 121.90,
119.90, 119.80, 118.80, 118.20, 109.40, 109.00, 108.40, 101.90. IR (cm-1): 3320 (w), 3030 (s), 2980(s),

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2250 (s), 1600 (s), 1560 (m), 1030 (m). HRMS (ESI): m/z calcd. for C32H19N3O2, 477.5122; found,
477.1455.
2-(4,5-Bis(4-chlorophenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3g).
Yellow crystals, mp. 208.3-209.4 ˚C, (62%). 1H NMR (400 MHz, DMSO-d6): δ 13.62 (1H, s), 8.20 (1H,
d, J=8.0 Hz), 8.13 (1H, s), 8.01 (1H, d, J=8.0 Hz), 7.52 (2H, d, J=8.0 Hz), 7.29-7.35 (6H, m), 7.11-7.20
13
(3H, m), 6.94-7.04 (3H, m), 6.48 (1H, s). C NMR (100 MHz, DMSO-d6): δ 159.10, 157.00, 153.90,
148.90, 145.92, 137.90, 135.80, 134.20, 134.00, 133.00, 132.80, 130.90, 130.00, 129.50, 129.00, 128.60,
124.00, 123.20, 123.00, 121.90, 121.00, 119.00, 118.90, 118.30. IR (cm-1): 3350 (w), 3030 (s), 2980 (s),
1640 (s), 1580 (m), 1050 (m). HRMS (ESI): m/z calcd. for C30H19Cl2NO2, 496.3834; found, 495.0775.
2-(4,5-Bis(2-methoxyphenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3h).
Yellow crystals, mp. 244.5-245.5 ˚C, (70%). 1H NMR (400 MHz, DMSO-d6): δ 14.70 (1H, s), 8.11 (1H,
dd, J1=1.2 Hz, J2=1.6 Hz), 7.81 (1H, dd, J1=1.6 Hz, J2=1.6 Hz), 7.81 (1H, s), 7.56 (1H, t), 7.31-7.33 (1H,
13
t), 7.08-7.18 (6H, m), 6.78-6.98 (4H, m), 6.75-6.79 (2H, m), 6.39 (1H, s), 3.88 (3H, s), 3.74 (3H, s). C
NMR (100 MHz, DMSO-d6): δ 160.19, 159.72, 159.32, 156.98, 154.10, 149.80, 145.90, 132.90, 132.15,
131.12, 130.30, 129.69, 129.10, 128.05, 124.10, 123.60, 123.00, 122.53, 121.00, 119.93, 119.90, 118.85,
118.82, 114.80, 114.70. IR (cm-1): 3310 (w), 3030 (s), 2985 (s), 1600 (s), 1550 (m), 1050 (m). HRMS
(ESI): m/z calcd. for C32H25NO4, 487.5452; found, 487.1768.
2-(4,5-Bis(3,4,5-trimethoxyphenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3i).
Brown crystals, mp. 236.1-237.9 ˚C, (73%). 1H NMR (400 MHz, DMSO-d6): δ 13.95 (1H, s), 8.22 (1H, d,
J=8.0 Hz), 8.17 (1H, s), 8.02 (1H, d, J=8.0 Hz), 7.53-7.59 (1H, t), 7.34-7.44 (1H, m), 6.94-7.22 (4H, m),
13
6.60 (2H, s), 6.46 (3H, d, J=11.2 Hz), 3.56-3.61 (18H, m). C NMR (100 MHz, DMSO-d6): δ 159.40,
156.96, 154.46, 153.96, 150.10, 147.68, 145.67, 138.23, 135.21, 132.82, 132.38, 131.62, 128.49, 127.76,
123.57, 123.60, 122.33, 121.09, 120.00, 119.66, 119.61, 118.61, 118.25, 106.62, 106.560,106.15, 60.69,
60.51, 60.39, 56.97, 56.42, 56.05. IR (cm-1): 3300 (w), 3030 (s), 2980 (s), 1600 (s), 1550 (m), 1050 (m).
HRMS (ESI): m/z calcd. for C36H33NO4, 607.6491; found, 607.2217.
2-(4,5-Bis(2-chlorophenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3j).
Yellow crystals, mp. 196.9-197.7 ˚C, (60%). 1H NMR (400 MHz, DMSO-d6): δ 13.62 (1H, s), 8.16-8.21
(1H, t), 8.13 (1H, s), 8.09 (1H, d, J=8.0 Hz), 7.67-7.75 (1H, m), 6.81-7.49 (12H, m), 6.60 (1H, d, J=9.6
13
Hz), 6.58 (1H, s). C NMR (100 MHz, DMSO-d6): δ 159.21, 157.72, 153.82, 153.73, 147.20, 145.65,
135.21, 135.16, 133.45, 133.11, 132.42, 131.35, 131.20, 131.18, 131.10, 130.78, 130.35, 130.29, 130.07,

HETEROCYCLES, Vol. 78, No. 2, 2009
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128.65, 127.93, 123.59, 119.77, 118.27. IR (cm-1): 3350 (w), 3010 (s), 2990 (s), 1630 (s), 1580 (m), 1010
(m). HRMS (ESI): m/z calcd. for C30H19Cl2NO2, 496.3834; found, 495.0769.
2-(4,5-Bis(3-bromophenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3k).
1
Brown crystals, mp. 187.1-188.6 ˚C, (63%). H NMR (400 MHz, DMSO-d6): δ 14.70 (1H, s), 8.10 (1H,
dd, J1=1.6 Hz, J2=7.6 Hz), 7.85 (1H, dd, J1=1.6 Hz, J2=7.6 Hz), 7.79 (1H, s), 7.33-7.37 (1H, t), 7.23-7.27
(1H, t), 7.18 (2H, d, J=7.6 Hz), 7.01-7.11 (8H, m), 6.90-6.94 (1H, t), 6.82 (1H, dd, J1=1.6 Hz, J2=7.6 Hz),
6.38 (1H, t). 13C NMR (100 MHz, DMSO-d6): δ 159.25, 157.00, 154.21, 149.98, 145.78, 139.03, 137.00,
132.21, 129.70, 129.35, 129.18, 129.09, 129.03, 128.84, 128.53, 128.12, 124.10, 123.28, 123.07, 122.17,
121.17, 121.16, 119.81, 119.71, 118.66, 118.23. IR (cm-1): 3320 (w), 3020 (s), 2980 (s), 1620 (s), 1580
(m), 1020 (m). HRMS (ESI): m/z calcd. for C30H19Br2NO2, 585.2854; found, 584.9753.
2-(4-(Benzo[d][1,3]dioxol-5-yl)-5-(benzo[d][1,3]dioxol-6-yl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol
(3l).
Yellow crystals, mp. 234.1-235.0 ˚C, (66%). 1H NMR (400 MHz, DMSO-d6): δ 13.85 (1H, s), 8.19 (1H,
d, J=8.0 Hz), 8.09 (1H, s), 7.81 (1H, d, J=8.0 Hz), 7.37 (2H, t), 7.17 (1H, t), 6.95-7.02 (5H, m), 6.73-6.81
(3H, m), 6.46 (1H, d, J=8.0 Hz), 6.43 (1H, s), 6.09 (2H, s), 5.97 (2H, s). 13C NMR (100 MHz, DMSO-d6):
δ 159.20, 156.92, 154.00, 152.93, 149.30, 148.25, 148.00, 147.90, 133.95, 123.61, 122.12, 120.00, 118.90,
109.3, 109.00, 108.00. IR (cm-1): 3320 (w), 3020 (s), 2995 (s), 1600 (s), 1500 (m), 1010 (m). HRMS
(ESI): m/z calcd. for C30H17Cl4NO2, 515.5122; found, 515.1360.
2-(4,5-Bis(3-nitrophenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3m).
Yellow crystals, mp. 186.2-197.7 ˚C, (64%). 1H NMR (400 MHz, DMSO-d6): δ 14.35 (1H, s), 8.50 (1H,
m), 8.25-8.35 (3H, m), 8.17 (1H, s), 8.00 (1H, dd, J1=1.6 Hz, J2=7.6 Hz), 7.50-7.67 (2H, m), 7.10-7.49
(9H, m), 6.55 (1H, s). 13C NMR (100 MHz, DMSO-d6): δ 155.31, 153.66, 148.82, 141.79, 135.89, 133.57,
129.33, 128.70, 128.19, 127.77, 125.55, 125.17, 121.86, 119.92, 119.31, 119.23, 118.55, 117.98, 116.72,
116.62, 114.59, 114.36, 114.06, 113.50. IR (cm-1): 3350 (w), 3010 (s), 2995 (s), 1600 (s), 1530 (m), 1040
(m). HRMS (ESI): m/z calcd. for C30H19N3O6, 517.4884; found, 517.1360.
2-(4,5-Bis(4-fluorophenyl)-5H-chromeno[4,3-b]pyridin-2-yl)phenol (3n).
Yellow crystals, mp. 197.6-198.1 ˚C, (64%). 1H NMR (400 MHz, DMSO-d6): δ 13.70 (1H, s), 8.19 (1H,
d, J=8.0 Hz), 8.13 (1H, s), 7.43 (1H, s), 8.02 (1H, d, J=8.0 Hz), 7.27-7.38 (7H, m), 7.13-7.19 (3H, m),
13
6.94-7.10 (4H, m), 6.49 (1H, s). C NMR (100 MHz, DMSO-d6): δ 158.3, 156. 7, 152.8, 147.7, 147.6,
146.5, 145.8, 139.9, 137.6, 133.3, 132.7, 132.2, 127.8, 125.6, 125.2, 121.9, 119.9, 119.32 119.2, 118.6,

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HETEROCYCLES, Vol. 78, No. 2, 2009
118.0, 116.7, 116.6, 114.6, 114.4, 114.1, 113.5, 70.6. IR (cm-1): 3350 (w), 3010 (s), 2995 (s), 1600 (s),
1530 (m), 1040 (m). HRMS (ESI): m/z calcd. for C30H19F2NO2, 463.4742; found,463.1228.
ACKNOWLEDGEMENTS
We are grateful to the foundation of the "National Natural Sciences Foundation of China (No.
20772103)", "Natural Sciences Foundation of Jiangsu Province (No. BK2007028)", "Surpassing Project
in Jiangsu Province (No. QL200607)", "Post-graduate creative project in Jiangsu Province
(No.CX07S-016z)" for financial support.
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11. The single crystal growth was carried out in DMF at room temperature. Crystal data for 3e:
Empirical formula C32H25NO6, yellow, crystal dimension 0.28 × 0.26 × 0.20 mm, monoclinic, space
group P 2(1)/c, a=12.2594(18) Å, b=16.619(2) Å, c=14.727(2) Å, α=90.00º, β=113.610(2)º,
γ=90.00º, V=2749.3(7) Å3, Mr=547.58, Z=4, Dc=1.323 Mg/m3, λ=0.71073 Å, µ (MoKα)=0.091
mm-1, F(000)=1152, S=1.017, R1=0.0418, wR2=0.1013. Crystallographic data for the structures of 3e
reported in this letter have been deposited with the Cambridge Crystallographic Date Centre as
supplementary publication No. CCDC-655834.
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