Reactions of 2-amino-4H-1-benzopyran-4-one with 4-Oxo-4H-1-benzopyran-3- carbaldehydes

Article abstract of DOI:10.1002/jhet.5570430603

The title aldehyde 1 reacts smoothly with the enamine moiety of 2-aminochromone 2 to produce hitherto unreported 3-(2-hydroxybenzoyl)-5H-1- benzopyrano[2,3-b]pyridin-5-one (azaxanthone) 5. This reaction has been extended for the synthesis of bisazaxanthon

Full text of DOI:10.1002/jhet.5570430603

Nov-Dec 2006
1431
Reactions of 2-Amino-4H-1-benzopyran-4-one with 4-Oxo-4H-1-
benzopyran-3-carbaldehydes
Tarun Ghosh and Chandrakanta Bandyopadhyay*
Department of Chemistry, R. K. Mission Vivekananda Centenary College,
Rahara, Kolkata 700 118, West Bengal, India
E-mail: kantachandra@rediffmail.com
Received October 1, 2005
O
R1
CHO
NH2
OH
O
N
O
O
O
O
+
R2
R1
R2
O
The title aldehyde 1 reacts smoothly with the enamine moiety of 2-aminochromone 2 to produce hitherto
unreported 3-(2-hydroxybenzoyl)-5H-1-benzopyrano[2,3-b]pyridin-5-one (azaxanthone) 5. This reaction
has been extended for the synthesis of bisazaxanthone 9.
J. Heterocyclic Chem., 43, 1431 (2006).
Reactions of enamines with 4-oxo-4H-1-benzopyran-3-
pyrimidinone [7] and 5-aminopyrazole [7,8] have been
reported to react with 1 to produce pyridinopyrimidine
and pyrazinopyrimidine, respectively. Our recent interest
in the field of 2-aminochromones [9,10], which possess
enamine moiety prompted us to study the reaction of 2-
carbaldehydes 1 draw attention for their wide variety of
reaction possibilities depending on the nature of the
enamine. 3-Aminocrotononitrile or 4-amino-pent-3-ene-2-
one [1] or ethyl ꢀ-aminocrotonate [2] reacts with 1 to give
1-benzopyrano[4,3-b]pyridines. Ethyl or methyl ꢀ-
aminocrotonate, produced in situ from corresponding
acetoacetate and NH3, reacts with 1 to produce similar
benzopyranopyridines [2]. This contradicts an earlier
report [3], where formation of dihydropyridines from the
reaction of 1 and methyl acetoacetate in presence of liquor
NH3 has been reported. Surprisingly, the same
dihydropyridine along with some other products has been
obtained from the reaction of ethyl ꢀ-aminocrotonate on
the knoevenagel condensate of aldehyde 1 and ethyl
acetoacetate [4]. Some heterocyclic enamines react with 1
to give 3-(2-hydroxybenzoyl)pyridine [5], while 2H,5H-3-
methyl-1-phenylpyrazol-5-one forms a condensate by
reacting only on the formyl function of 1 [6]. 6-Amino-
aminochromones
2 with 3-formylchromones 1 and
bischromone-3,3'-dicarbaldehyde 8.
On heating an equimolar mixture of aldehyde 1 and 2-
aminochromone 2 in ethanol under reflux for 12-15 h
produced 3-(2-hydroxybenzoyl)-5H-1-benzopyrano[2,3-
b]pyridin-5-one (azaxanthone) 5 in 25–40% yield (Table
1, entries 1-3). The reaction can be rationalized by
considering the initial attack of the carbon end of the
enamine moiety of 2 at the 2-position of 1 with
concomitant opening of pyran ring. Subsequent cycli-
sation of 4 produces 5 (Scheme 1). 5-Oxo-5H-1-benzo-
pyrano[2,3-b]pyridine derivatives having a carboxylic
acid group at 3-position exhibits antiinflamatory activity
[11], 4,5-dihydro-4,5-dioxo-1-benzopyrano[2,3-b]pyri-
dine-3-carboxylic acid (0.9 mg/kg) gives 100% inhibition
in the passive cutaneous anaphylaxis screen [12], 5-oxo-
5H-1-benzopyrano[2,3-b]pyridine-9-acetic acid exhibits
antitumor activity [13]. Encouraged by this information,
attempts were made to improve the yield of 5 and to
reduce the reaction time. When the reaction of 1 with 2
was carried out in CH3CN (Table 1, entry 4), no better
result was observed. On heating in dry xylene for 32 h, a
poor yield of 5 was obtained (entry 5). But the reaction
was completed within 3 h when catalytic amount of p-
toluenesulfonic acid was added in the reaction mixture in
xylene and the yield was found to increase sharply
(entries 6-9). Use of acetic acid in place of xylene/TsOH
also gave good result (entries 10, 11). The presence of
Table 1
3-(2-hydroxybenzoyl)-5H-1-benzopyrano[2, 3-b]pyridin-5-one (5)
Entry Compound
No.
R1
R2
Reaction
medium
EtOH
EtOH
EtOH
CH3CN
Xylene
Xylene/TsOH
Xylene/TsOH
Time
(h)
12
15
15
15
32
3
3
3
3
3
Yield
%
1
2
5a
5b
5c
5c
5c
5c
5a
5b
5d
5c
5d
H
Me
H
H
H
40
25
30
25
10
72
75
78
93
75
80
H
H
3
4
5
6
7
8
Me
Me
Me
Me
H
H
H
H
Me Xylene/TsOH
Cl
H
9
10
11
Me
Me
Me
Xylene/TsOH
AcOH
AcOH
Cl
3

1432
T. Ghosh and C. Bandyopadhyay
Vol 43
acid facilitates the condensation reaction by initial
protonation of 1 to form 3, which eases the attack of
enamine 2 at the C-2 position of 3. The pyran ring
subsequently opens up to form 4. The condensation of
amine and aldehyde functionalities in 4 to form 5 is also
fovoured by the acid catalyst (Scheme 1). In summary,
compound 5 was synthesised in good yield by heating an
equimolar mixture of 1 and 2 in dry xylene under reflux
for 3 h containing catalytic amount of p-toluenesulfonic
acid or by heating under reflux in acetic acid.
by an alkyl chain through ethereal linkage by heating a
mixture of 6, appropriate dibromoalkane, NaI, anhydrous
K2CO3 in dry acetone under reflux for 72 h to produce 7
(Scheme 2). Compound 8 was obtained by Vilsmeier-
Haack reaction of 7 [15].
Bisaldehyde 8 was then utilized for the synthesis of
bisazaxanthone 9. Poor solubility of 8 in EtOH or xylene
caused problem in performing this reaction. But on
heating a mixture of 8 and 2 in 1:2 molar ratio in acetic
acid under reflux for 3 h produced 9 in moderate to good
Scheme 1
O
NH2
O
O
R2
O
O
Xylene/TsOH
or
+
AcOH
R2
R1
O
:NH2
R1
CHO
CHO
O
+OH
2
1
3
O
O
O
H
R2
O
R2
OH
R1
R1
O
H2N
CHO
H2+N
CHO
O
O
4
H
For 1-5
1
9
6
3'
a:R1 = R2 = H
OH
N
O
O
b:R1 = H; R2 = Me
c:R1 = Me; R2 = H
d:R1 = Me; R2 = Cl
R2
R1
6'
4
O
5
Scheme 2
1
N
3''
9
OH
O
OH
O
1''
5''
O
CH3
R2
R2
O
O
CHO
+2
AcOH
CHO
6
6''
4
O
O
O
O
O
O
O
O
POCl3
DMF
CH3
[CH2]n
[CH2]n
[CH2]n
6'
6'''
4'
O
5'''
O
O
1'''
OH
N
O
OH
O
3'''
9'
1'
7
8
9a: n = 3; R2 = Me
9b: n = 4; R2 = Me
9c: n = 5; R2 = H
9d: n = 3; R2 = Cl
(CH2)nBr2
NaI, K2CO3
Acetone, 72 h
OH
For 7 and 8
a: n = 3
b: n = 4
CH3
O
c: n = 5
HO
6
Pharmaceutical activity of various bischromones are the
incentive to synthesize majority of bischromones [14]. In
order to apply this methodology on bischromones 8,
synthesis of [(ꢀ,ꢁ-alkanediol)bisoxy]bis[4-oxo-4H-1-
yields. As reported earlier [10], the methylene protons in
compounds 8b and 9b appear as singlet although those in
compounds 8a,c, 9a,c,d they appear with their usual
multiplicities. The unusual spin multiplicity for the
methylene protons in compounds 8b and 9b could not be
explained.
benzopyran-3-carbaldehyde]
8 was undertaken. Two
molecules of 2, 5-dihydroxyacetophenone 6 were tethered

Nov-Dec 2006
2-Amino-4H-1-benzopyran-4-one with 4-Oxo-4H-1-benzopyran-3-carbaldehydes
1433
7.68 (dd, 1 H, 9-H, J = 8.0, 1.1 Hz), 7.82-7.88 (m, 1 H, 8-H), 8.35
(dd, 1 H, 6-H, J = 7.9, 1.5 Hz), 9.01 (d, 1 H, 4-H, J = 2.5 Hz),
9.08 (d, 1 H, 2-H, J = 2.5 Hz), 11.56 (s, exchangeable, 1 H, OH).
Anal. Calcd. for C20H13NO4: C, 72.50; H, 3.95; N, 4.23.
Found: C, 72.73; H, 4.10; N, 4.15.
In conclusion, we have synthesized hitherto unreported
3-salicyloylazaxanthones 5 and 9 in good yields using the
enamino function of 2-aminochromone 2 in one pot from
3-formylchromones 1 and 8, respectively.
7-Chloro-3-(2-hydroxy-5-methylbenzoyl)-5H-1-benzopyrano-
[2,3-b]pyridin-5-one (5d).
EXPERIMENTAL
This compound was obtained in 93% yield as yellow fine
crystals, mp 256-258 °C; ir: 3400, 3062, 2922, 1673, 1635,
The recorded melting points are uncorrected. Ir spectra were
recorded in KBr on a Beckman IR 20A and nmr spectra on a
Bruker 300 MHz spectrometer.
1
1602, 1472 cm-1; H nmr (deuteriochloroform): ꢀ 2.36 (s, 3 H,
CH3), 7.12 (d, 1 H, 3'-H, J = 8.7 Hz), 7.37 (d, 1 H, 6'-H, J = 1.8
Hz), 7.48 (dd, 1 H, 4'-H, J = 8.7, 1.8 Hz), 7.73 (d, 1 H, 9-H, J =
9.0 Hz), 7.87 (dd, 1 H, 8-H, J = 9.0, 2.4 Hz), 8.39 (d, 1 H, 6-H, J
= 2.4 Hz), 9.08 (d, 1 H, 4-H, J = 2.5 Hz), 9.17 (d, 1 H, 2-H, J =
2.5 Hz), 11.61 (s, exchangeable, 1 H, OH).
General Procedure for the Synthesis of 3-(2-Hydroxybenzoyl)-
5H-1-benzopyrano[2,3-b]pyridin-5-ones (5).
A mixture of 3-formylchromone 1 (0.25 mmol) and 2-amino-
chromone 2 (0.25 mmol) in dry xylene (10 ml) was heated under
reflux to make a clear solution. Catalytic amount of p-toluene
sulphonic acid (ca 2 mg) was then added and heated under
reflux for 3 h. Completion of the reaction was determined by
TLC analysis. Xylene was removed under reduced pressure. The
resultant solid was dissolved in benzene, washed with water,
dried over Na2SO4. The benzene solution on concentration
produced 5 in good yield.
Anal. Calcd. for C20H12NClO4: C, 65.67 H, 3.31; N, 3.83.
Found: C, 65.31; H, 3.52; N, 4.08.
General Procedure for the Synthesis of 6,6'-[(ꢁ,ꢂ-Alkanediol)-
bisoxy]bis[4-oxo-4H-1-benzopyran-3-carbaldehydes] (8).
POCl3 (2 ml, 22 mmol) was injected into dry DMF (2 ml, 26
mmol) under argon atmosphere at 0-5 °C temperatures and
allowed to stir under this condition for 5 minutes. A solution of
7 (1 mmol) in dry DMF (8-10 ml) was injected slowly at this
temperature. After complete addition, the resultant mixture was
stirred under cold condition for 10 minutes and then allowed to
come at room temperature and stirred under this condition for 6
h. The resultant thick reddish reaction mixture was poured into
crushed ice (100 gm), a yellow coloured solid appeared. It was
filtered, washed with water, dried in air and crystallised from
dichloromethane to produce 8.
3-(2-Hydroxybenzoyl)-5H-1-benzopyrano[2,3-b]pyridin-5-one
(5a).
This compound was obtained in 75% yield as yellow fine
crystals, mp 150-152 °C; ir: 3421, 3073, 2935, 1671, 1626,
1
1596, 1465 cm-1; H nmr (deuteriochloroform): ꢀ 6.94-6.99 (m,
1 H, 5'-H), 7.13 (dd, 1 H, 3'-H, J = 8.2, 0.9 Hz), 7.48-7.63 (m, 3
H, 7-, 4'- and 6'-H), 7.69 (dd, 1 H, 9-H, J = 8.1, 1.0 Hz), 7.83-
7.86 (m, 1 H, 8-H), 8.35 (dd, 1 H, 6-H, J = 7.9, 1.5 Hz), 9.01 (d,
1 H, 4-H, J = 2.4 Hz), 9.10 (d, 1 H, 2-H, J = 2.4 Hz), 11.75 (s,
exchangeable, 1 H, OH); 13C nmr (deuteriodimethylsulfoxide) ꢀ
115.43 (1'-C), 116.90 (3'-C), 118.58 (9-C), 119.55 (5'-C), 120.99
(4a-C), 124.06 (5a-C), 125.37 (7-C), 126.02 (6-C), 130.65 (6'-
C), 130.73 (3-C), 134.14 (8-C), 136.41 (4'-C), 137.69 (4-C),
154.67 (2-C), 155.09 (9a-C), 156.71 (2'-C), 161.37 (10a-C),
176.60 (pyran CO), 193.5 (salicyloyl CO).
6,6'-[(1,3-Propanediol)bisoxy]bis[4-oxo-4H-1-benzopyran-3-
carbaldehyde] (8a).
This compound was obtained in 71% yield as faint yellow
solid, mp 192-194 °C; ir: 3065, 1689, 1661, 1602, 1485, 1464,
1
1313 cm-1; H nmr (deuteriochloroform): ꢀ 2.38 (quintet, 2 H,
CH2, J = 6.0 Hz), 4.31 (t, 4 H, 2 x OCH2, J = 6.0 Hz), 7.35 (dd, 2
H, 2 x 7-H, J = 9.1, 3.0 Hz), 7.49 (d, 2 H, 2 x 8-H, J = 9.1 Hz),
7.67 (d, 2 H, 2 x 5-H, J = 3.0 Hz), 8.54 (s, 2 H, 2 x 2-H), 10.40
(s, 2 H, 2 x CHO).
Anal. Calcd. for C19H11NO4: C, 71.92; H, 3.49; N, 4.41.
Found: C, 72.12; H, 3.55; N, 4.30.
Anal. Calcd. for C23H16O8: C, 65.71; H, 3.84. Found: C, 65.94;
H, 3.95.
3-(2-Hydroxybenzoyl)-7-methyl-5H-1-benzopyrano[2,3-b]-
pyridin-5-one (5b).
6,6'-[(1,4-Butanediol)bisoxy]bis[4-oxo-4H-1-benzopyran-3-
carbaldehyde] (8b).
This compound was obtained in 78% yield as yellow fine
crystals, mp 188-190 °C; ir: 3457, 3052, 2919, 1673, 1624,
1
1590, 1474 cm-1; H nmr (deuteriochloroform): ꢀ 2.51 (s, 3 H,
This compound was obtained in 81% yield as faint yellow
solid, mp 258-260 °C; ir: 3070, 1666, 1591, 1468, 1219 cm-1 1H
CH3), 6.94-6.99 (m, 1 H, 5'-H), 7.14 (dd, 1 H, 3'-H, J = 8.2, 0.9
Hz), 7.56-7.68 (m, 4 H, 4'-, 6'-, 8- and 9-H), 8.12 (d, 1 H, 6-H, J
= 0.9 Hz), 9.01 (d, 1 H, 4-H, J = 2.5 Hz), 9.09 (d, 1 H, 2-H, J =
2.5 Hz), 11.75 (s, exchangeable, 1 H, OH).
Anal. Calcd. for C20H13NO4: C, 72.50; H, 3.95; N, 4.23.
Found: C, 72.65; H, 4.12; N, 4.10.
;
nmr (deuteriochloroform): ꢀ 2.07 (s, 4 H, 2 x CH2), 4.18 (s, 4 H,
2 x OCH2), 7.34 (dd, 2 H, 2 x 7-H, J = 9.0, 2.9 Hz), 7.48 (d, 2 H,
2 x 8-H, J = 9.0 Hz), 7.65 (d, 2 H, 2 x 5-H, J = 2.9 Hz,), 8.53 (s,
2 H, 2 x 2-H), 10.40 (s, 2 H, 2 x CHO).
Anal. Calcd. for C24H18O8: C, 66.36; H, 4.18. Found: C, 66.61;
H, 4.30.
3-(2-Hydroxy-5-methylbenzoyl)-5H-1-benzopyrano[2,3-b]-
pyridin-5-one (5c).
6,6'-[(1,5-Pentanediol)bisoxy]bis[4-oxo-4H-1-benzopyran-3-
carbaldehyde] (8c).
This compound was obtained in 72% yield as yellow fine
crystals, mp 218-220 °C; ir: 3450, 3043, 2920, 1672, 1631, 1593,
This compound was obtained in 69% yield as faint yellow
solid mp 200 °C; ir: 3050, 1672, 1610, 1454, 1312 cm-1; 1H nmr
(deuteriochloroform): ꢀ 1.69-1.76 (m, 2 H, CH2), 1.89-1.98 (m,
4 H, 2 x CH2), 4.13 (t, 4 H, 2 x OCH2, J = 6.2 Hz), 7.32 (dd, 2 H,
1
1464 cm-1; H nmr (deuteriochloroform): ꢀ 2.28 (s, 3 H, CH3),
7.04 (d, 1 H, 3'-H, J = 8.5 Hz), 7.30 (d, 1 H, 6'-H, J = 1.9 Hz),
7.40 (dd, 1 H, 4'-H, J = 8.5, 1.9 Hz), 7.48-7.52 (m, 1 H, 7-H),

1434
T. Ghosh and C. Bandyopadhyay
Vol 43
2 x 7-H, J = 9.1, 2.9 Hz), 7.48 (d, 2 H, 2 x 8-H, J = 9.1 Hz), 7.64
(d, 2 H, 2 x 5-H, J = 2.9 Hz), 8.53 (s, 2 H, 2 x 2-H), 10.40 (s, 2
H, 2 x CHO).
Anal. Calcd. for C25H20O8: C, 66.96; H, 4.50. Found: C,
67.21; H, 4.38.
(9-C), 125.82 (7-C), 126.77 (6-C), 131.06 (3-C), 136.20 (8-C),
138.39 (4-C), 151.28 (5'-C), 154.42 (2-C), 155.50 (2'-C), 157.57
(9a-C), 161.54 (10a-C), 176.78 (pyran CO), 196.60 (salicyloyl
CO); ms(positive ion electrospray): m/z 734 (M+).
Anal. Calcd. for C43H30N2O10: C, 70.29; H, 4.12; N, 3.81.
Found: C, 70.08; H, 3.93; N, 3.55.
General Procedure for the Synthesis of 5",5"'-[(ꢀ,ꢁ-Alkanediol)-
bisoxy]bis[3-(2-hydroxybenzoyl)-5H-1-benzopyrano[2,3-b]-
pyridin-5-ones] (9).
7,7'-Dichloro-5",5"'-[(1,3-propanediol)bisoxy]bis[3-(2-hydroxy-
benzoyl)-5H-1-benzopyrano[2,3-b]pyridin-5-one] (9d).
A mixture of bisaldehyde 8 (0.2 mmol) and 2-aminochromone
2 (0.4 mmol) in glacial acetic acid (10 ml) was heated under
reflux for 3 h. On keeping the reaction mixture overnight in
refrigerator (10 °C), a yellow solid was separated. The separated
solid was collected by filtration, washed with methanol, dried in
air and recrystallised from CHCl3-MeOH (1:1) to afford 9.
This compound was obtained in 84% yield as yellow solid,
mp 252-256 °C; ir: 3419, 3078, 2922, 1671, 1594, 1463, 1311
cm-1; 1H nmr (deuteriochloroform): ꢂ 2.11 (quintet, 2 H, CH2, J =
6.0 Hz), 3.94 (t, 4 H, 2 x OCH2, J = 6.0 Hz), 6.84 (d, 2 H, 2 x 6"-
H, J = 2.7 Hz), 6.94 (d, 2 H, 2 x 3"-H, J = 9.0 Hz), 7.04 (dd, 2 H,
2 x 4"-H, J = 9.0, 2.7 Hz), 7.53 (d, 2 H, 2 x 9-H, J = 8.7 Hz),
7.70 (dd, 2 H, 2 x 8-H, J = 8.7, 2.7 Hz), 8.14 (d, 2 H, 2 x 6-H, J
= 2.7 Hz), 8.90 (d, 2 H, 2 x 4-H, J = 2.4 Hz), 9.02 (d, 2 H, 2 x 2-
H, J = 2.4 Hz), 11.18 (s, exchangeable, 2 H, 2 x OH).
7,7'-Dimethyl-5",5"'-[(1,3-propanediol)bisoxy]bis[3-(2-hydroxy-
benzoyl)-5H-1-benzopyrano[2,3-b]pyridin-5-one] (9a).
This compound was obtained in 68% yield as yellow solid,
mp 275-277 °C; ir: 3400, 3057, 2872, 1697, 1643, 1485, 1472,
Anal. Calcd. for C41H24N2Cl2O10: C, 63.50; H, 3.12; N, 3.61.
Found: C, 63.22; H, 3.28; N, 3.35.
1
1311 cm-1; H nmr (deuteriodimethylsulfoxide): ꢂ 2.14 (quintet,
Acknowledgements.
2 H, CH2, J = 5.9 Hz), 2.46 (s, 6 H, 2 x 7-CH3), 4.11 (t, 4 H, 2 x
OCH2, J = 5.9 Hz), 6.94 (d, 2 H, 2 x 3"-H, J = 8.9 Hz), 7.02 (d, 2
H, 2 x 6"-H, J = 2.9 Hz), 7.14 (dd, 2 H, 2 x 4"-H, J = 8.9, 2.9
Hz), 7.67(d, 2 H, 2 x 9-H, J = 8.5 Hz), 7.76 (dd, 2 H, 2 x 8-H, J
= 8.5, 1.9 Hz), 7.95 (d, 2 H, 2 x 6-H, J = 1.9 Hz), 8.72 (d, 2 H, 2
x 4-H, J = 2.4 Hz), 9.04 (d, 2 H, 2 x 2-H, J = 2.4 Hz), 9.92 (s,
exchangeable, 2 H, 2 x OH).
We gratefully acknowledge U. G. C., New Delhi for financial
assistance; IICB and IACS, Jadavpur for spectral analysis and
finally the college authority for providing research facilities.
REFERENCES AND NOTES
Anal. Calcd. for C43H30N2O10: C, 70.29; H, 4.12; N, 3.81.
Found: C, 70.42; H, 3.95; N, 3.62.
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1
1319 cm-1; H nmr (deuteriochloroform): ꢂ 1.88 (s, 4 H, 2 x
CH2), 2.49 (s, 6 H, 2 x 7-CH3), 3.91 (s, 4 H, 2 x OCH2), 6.97 (d,
2 H, 2 x 6"-H, J = 2.9 Hz), 7.04 (d, 2 H, 2 x 3"-H, J = 9.1 Hz),
7.18 (dd, 2 H, 2 x 4"-H, J = 9.1, 2.9 Hz), 7.51(d, 2 H, 2 x 9-H, J
= 8.5 Hz), 7.63 (dd, 2 H, 2 x 8-H, J = 8.5, 1.7 Hz), 7.98 (d, 2 H,
2 x 6-H, J = 1.7 Hz), 8.98 (d, 2 H, 2 x 4-H, J = 2.4 Hz), 9.06 (d,
2 H, 2 x 2-H, J = 2.4 Hz), 11.32 (s, exchangeable, 2 H, 2 x OH);
ms(positive ion electrospray): m/z 748 (M+).
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[10] T. Ghosh, S. Saha and C. Bandyopadhyay, Synthesis, 1845
(2005).
[11] A. Nohara and S. Kuzuna, Eur. Patent 102175 (1983); Chem.
Abstr., 101, 7137n (1984).
[12] D. T. Conor and M. von Strandtmann, US Patent 4117134
(1978); Chem. Abstr., 90, 87428a (1979).
[13] L. M. Ching, W. R. Joseph, Z. Li, G. J. Atwell, G. W.
Rewcastle, N. A. Denny and B. C. Baguley, Eur. J. Cancer, 27, 79
(1991); Chem. Abstract., 115, 41427f (1991).
Anal. Calcd. for C44H32N2O10: C, 70.58; H, 4.31; N, 3.74.
Found: C, 70.21; H, 4.43; N, 3.75.
5",5"'-[(1,5-Pentanediol)bisoxy]bis[3-(2-hydroxybenzoyl)-5H-1-
benzopyrano[2,3-b]pyridin-5-one] (9c).
This compound was obtained in 65% yield as yellow solid, mp
196-198 °C; ir: 3416, 2924, 1668, 1599, 1467, 1227 cm-1; 1H nmr
(deuteriochloroform): ꢂ 1.54-1.62 (m, 2 H, CH2), 1.72-1.81 (m, 4
H, 2 x CH2), 3.85 (t, 4 H, 2 x OCH2, J = 6.1 Hz), 6.95 (d, 2 H, 2 x
6"-H, J = 2.9 Hz), 7.04 (d, 2 H, 2 x 3"-H, J = 9.0 Hz), 7.18 (dd, 2
H, 2 x 4"-H, J = 9.0, 2.9 Hz), 7.45-7.50 (m, 2 H, 2 x 7-H), 7.65(dd,
2 H, 2 x 9-H, J = 8.2, 1.0 Hz), 7.81-7.87 (m, 2 H, 2 x 8-H), 8.28
(dd, 2 H, 2 x 6-H, J = 7.9, 1.4 Hz), 8.99 (d, 2 H, 2 x 4-H, J = 2.4
Hz), 9.07 (d, 2 H, 2 x 2-H, J = 2.4 Hz), 11.29 (s, exchangeable, 2
H, 2 x OH); 13C nmr (deuteriochloroform): ꢂ 22.58 (OCH2CH2-C),
28.83 (OCH2-C), 68.58 (O-C), 115.67 (6'-C), 115.75 (1'-C),
118.20 (4a-C), 118.64 (3'-C), 119.76 (4'-C), 121.44 (5a-C), 125.38
[14] G. P. Ellis, Heterocyclic Compounds, vol. 31; Ed. A.
Weissberger; Interscience, New York, chap. XXI, 1043 (1977) and
references therein.
[15] H. Harnish, Ann. Chem., 765, 8 (1972); A. Nohara, T. Umetani
and Y. Sanno, Tetrahedron Lett., 14, 1995 (1973).