Synthesis of new iminocoumarins bearing parabanic moieties

Article abstract of DOI:10.1080/00397911003710562

(Chemical Equation Presented) The synthesis of novel substituted 3-p-nitro-phenyliminocoumarins and corresponding N-ureaiminocoumarins is described. The condensation of these materials with oxalyl chloride leads to the corresponding N-parabanic iminocouma

Full text of DOI:10.1080/00397911003710562

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Synthesis of New Iminocoumarins
Bearing Parabanic Moieties
Leila Benmaktouf a , Houcine Ammar a , Yves Le Bigot b & Souhir
Abid a
a Laboratoire de Chimie Appliquée: Hétérocycles, Corps Gras et
Polymères, Faculté des Sciences , Université de Sfax , Sfax , Tunisia
b Laboratoire de Génie Chimique, ENSIACET , Toulouse , France
Published online: 03 Mar 2011.
To cite this article: Leila Benmaktouf , Houcine Ammar , Yves Le Bigot & Souhir Abid (2011)
Synthesis of New Iminocoumarins Bearing Parabanic Moieties, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 41:7, 1017-1026, DOI:
10.1080/00397911003710562
To link to this article: http://dx.doi.org/10.1080/00397911003710562
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Synthetic Communications1, 41: 1017–1026, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911003710562
SYNTHESIS OF NEW IMINOCOUMARINS BEARING
PARABANIC MOIETIES
Leila Benmaktouf,1 Houcine Ammar,1 Yves Le Bigot,2 and
Souhir Abid1
1
´
Laboratoire de Chimie Appliquee: Heterocycles, Corps Gras et Polymeres,
Faculte des Sciences, Universite de Sfax, Sfax, Tunisia
´ ´
`
´
´
2
´
Laboratoire de Genie Chimique, ENSIACET, Toulouse, France
GRAPHICAL ABSTRACT
Abstract The synthesis of novel substituted 3-p-nitro-phenyliminocoumarins and
corresponding N-ureaiminocoumarins is described. The condensation of these materials
with oxalyl chloride leads to the corresponding N-parabanic iminocoumarins, which have
not previously been described, in moderate or good yields and high selectivity. The struc-
tures were characterized by Fourier transform infrared, 1H and 13C NMR, and elemental
analysis.
Keywords N-Hydrazonochromene; iminocoumarin; Knoevenagel condensation; Schmidt
reaction
INTRODUCTION
In the past decade, the synthesis, characterization, and properties of
2-iminocoumarin derivatives have been studied intensively. This considerable atten-
tion of investigators to these products is connected on the one hand to their high
reactivity toward both electrophiles and nucleophiles and on the other hand to their
many applications in agricultural and pharmacological industries. For example,
some 3-hetaryl coumarins and iminocoumarins have been proposed as anticancer,[1]
anti-asthmatic,[2] antibacterial,[3] and antiallergic[4] agents. Iminocoumarins can be
Received January 4, 2010.
Address correspondence to Souhir Abid, Laboratoire de Chimie Appliquee: Heterocycles, Corps
´ ´ ´
Gras et Polymeres, Faculte des Sciences de Sfax, 3000 Sfax, Tunisia. E-mail: abidsouhir@yahoo.fr
`
´
1017

1018
L. BENMAKTOUF ET AL.
also used as fluorescent dyes, and their optical properties depend strongly on the
nature and the position of substituents.[5–9]
This wide range of applications has stimulated great research on the prep-
aration, reactivity, and properties of iminocoumarins. It was reported that 2-imino-
coumarins are highly versatile precursors used for the synthesis of several polycyclic
compounds. Bilokin et al. have described the use of 2-iminocoumarin-3-carbox-
amides as starting reagents in the synthesis of 3-hetaryl coumarins.[10,11] Gorobets
et al. have studied the reaction of 3-thiazolyl-2-iminocoumarins with amine and
hydrazide derivatives under acid catalysis conditions to obtain the corresponding
N-substituted iminocoumarins.[12] Using aromatic aldehydes as electrophilic reagents,
benzopyranopyrimidines or imidazolyl coumarins were obtained depending on the
structure of starting materials.[13] Volmajer et al. have developed the synthesis of
N-hydrazonochromenes via condensation of 2-iminocoumarin-3-carbonitriles with
hydrazine derivatives such as phenylhydrazine, 2-hydrazinopyridine, or N-phenyl-
hydrazinecarboxamide.[14] In our previous work, we showed that 3-cyano-2-imini-
coumarins reacted with electrophiles such as ethylchloroformate, isocyanates,
acylchlorides, and thioisocyanates, leading to the corresponding N-substituted
iminicoumarins.[7,15,16] Reaction of N-ethoxycarbonyl derivatives with amines or
hydrazides as N-nucleophiles led to benzopyranopyrimidines,[15,17] whereas hydra-
zine reagents gave 3-hetaryl coumarins.[18] Bis-iminocoumarins can be obtained by
the Schmidt reaction using diamines as reagents.[19]
In view of these findings, it appears that a satisfactory combination of coumari-
nic or iminocoumarinic moieties and nitrogen-containing heterocycle constitutes an
original way to develop organic materials of special interest. It seems that the struc-
ture of the heterocycle and its position in iminocoumarin substrate might present a
decisive role in both biological and optical properties. Given the potential impor-
tance of this family of compounds and the extensive experience of our laboratories
in the field of heterocyclic-based coumarins and iminocoumarins, we decided to
study the synthesis of a novel class of organic functional materials bearing iminocou-
marin and parabanic groups. To the best of our knowledge, no reports on this family
of iminocoumarin derivatives have appeared in the literature. In the present paper,
we describe the synthesis of several 3-p-nitro-phenyliminocoumarins followed by
their transformation into N-parabanic derivatives.
RESULTS AND DISCUSSION
The synthetic procedure leading to N-parabanic iminocoumarins included, as
shown in Scheme 1, three steps: (i) condensation of p-nitrobenzyl cyanide with
substituted salicylaldehydes to obtain the corresponding iminocoumarins 1a–5a
followed by (ii) introduction of urea function in the N-position in acidic medium
and then (iii) its conversion to parabanic heterocycle by treatment with oxalyl
chloride.
When the first step was carried out with homogenous catalyst such as piperi-
dine according to our previous procedure,[15] iminocoumarins 1a–5a were obtained
in moderate yields (10–20%). The use of resin Amberlite IRA 900 proved more suit-
able for the synthesis of these iminocoumarins. This catalyst was not only of interest
because of its advantage in term of yields (Table 1) but also because it offered

SYNTHESIS OF NEW IMINOCOUMARINS
1019
Scheme 1. General pathway for synthesis of the 2-N-parabanic iminocoumarins.
considerable advantages essential to preventing undesirable side reactions such as
hydrolysis from converting iminocoumarins to the corresponding coumarins in hom-
1
ogenous medium.[15,16] Fourier transform infrared (FTIR), H and 13C NMR, and
elemental analysis confirmed the expected structures.
The coupling, by Schmidt reaction, of 1a–5a compounds with 4-phenylsemicar-
bazide b, carried out at room temperature in a mixture of chloroform and glacial
acetic acid, led in the second step to N-ureaiminocoumarins 1b–5b following the
N-nucleophilic attack of imidic carbon center (Table 1). The substituents in the start-
ing iminocoumarins 1a–5a proved to have a significant effect on the reaction course.
Table 1. Synthesis of compounds 1a–5a, 1b–5b, and 1c–5c
Compounds
R1
R2
Yields (%)
Times (h)
1a
2a
3a
4a
5a
H
H
H
Br
58 (13a)
50 (10a)
73 (16a)
82 (16a)
75 (20a)
8
8
6
6
6
N(Et)2
H
MeO
H
MeO
H
1b
2b
3b
4b
5b
H
H
H
Br
66
92
38
90
30
2
0.5
4
N(Et)2
H
MeO
H
MeO
H
2
4
1c
2c
3c
4c
5c
H
H
H
Br
88
95
46
78
65
12
12
12
12
12
N(Et)2
H
MeO
H
MeO
H
aYields obtained with piperidine as catalyst.

1020
L. BENMAKTOUF ET AL.
Hence, in the case of the 2-iminocoumarins bearing a bromo or methoxy group in
the 6-position, the reaction occurred in almost quantitative yields (compounds 2b,
4b). However, the presence of a donor substituent in position 7 led to a dramatic
decrease in yield (compounds 3b, 5b), which can be attributed to the low electrophilic
reactivity of imidic carbon.
The expected structures 1b–5b were clearly confirmed by the spectroscopic
analyses showing the presence of urea function (n C O: 1706 cmꢀ1; d NH: 8.41
=
and 10.19 ppm; d CO: 152 ppm in compound 1b).
The cyclocondensations of 1b–5b with oxalyl chloride c, carried out in the pres-
ence of pyridine, started in a heterogeneous system because of their insolubility in
1,2-dichloroethane (DCE). The mixture became homogeneous with the progress of
the reaction because of the increased solubility of the parabanic ring once it was
formed. In this case, the use of pyridine was important because it acts both as cata-
lyst activating chloroformyl functions and at the same time as acid acceptor. The
progress of the reaction was followed by the changes in the FTIR spectra of samples
withdrawn at regular intervals from the reaction media, which showed a decrease of
the absorption bands characteristic of the urea group and the appearance of an
absorption band in the region of 1770 cmꢀ1 assigned to the parabanic ring resulting
from the intermolecular cyclisation. Moreover, all N-parabanic iminocoumarins
1
1c–5c exhibit H NMR spectra in good agreement with their expected structures.
Particularly, the absence of original peaks arising from the NHCONH group is a
clear indication that the cyclocondensation reaction had gone to completion.
Table 1 shows the yields of isolated N-parabanic iminocoumarins 1c–5c.
CONCLUSION
We have presented a facile route for the formation of novel iminocoumarins
bearing parabanic rings by the reaction of N-ureaiminocoumarins derivatives with
oxalyl chloride in the presence of pyridine and ethylene chloride as solvent. The
N-ureaiminocoumarins derivatives were obtained by reaction of iminocoumarins
derivatives with N-nucleophiles under acid catalysis. The method developed in this
work is particularly interesting for the simplicity of providing this family of imino-
coumarin compouds in good yield with high selectivity.
EXPERIMENTAL
Aldehydes 1–5, p-nitrobenzyl cyanide a, 4-phenylsemicarbazide b, and oxalyl
chloride c are commercial products. Solvents (toluene, chloroform) were purified
by standard technique and redistilled prior to their use. Catalyst IRA 900 was con-
ditioned and then used. The melting points were determined on an Electrothermal
9100 apparatus. IR spectra were obtained on a Jasco FTIR 420 instrument using
1
KBr pellets. H and 13C NMR spectra were recorded on a Bruker WP 200 spec-
trometer at 300 MHz and 75.0 MHz respectively, in CDCl3 or dimethylsulfoxide
(DMSO-d6), with tetramethylsilane (TMS) as internal standard (chemical shifts in
ppm). Elemental microanalysis were performed on a EA 1112 analyser from CE
Instruments.

SYNTHESIS OF NEW IMINOCOUMARINS
1021
General Procedure for the Synthesis of Iminocoumarins (1a–5a)
A mixture of aldehydes 1–5 (20 mmol), IRA 900 resin (2 g, 20 mmol OH-), and
toluene (25 mL) were introduced in a 250-mL, three-necked flask equipped with a
condenser and stirred for 3 h at 85 ꢁC under a nitrogen atmosphere. After that,
the p-nitrobenzyl cyanide a (20 mmol) was added and the mixture was refluxed for
an appropriate time (Table 1). After completion of the reaction, the organic phase
was separated from the solid catalyst and concentrated under reduced pressure.
The solid phase was recrystallized from toluene (compound 1a, 3a) or from ethyl
acetate (compounds 2a, 4a–5a).
Data
3-(p-Nitrophenyl)iminocoumarin (1a). IR (KBr) (cmꢀ1): n ¼ 1651 (C N),
=
1
3297 (NH). H NMR (DMSO-d6) (ppm): d ¼ 6.91–7.58 (m, 4H, Ar), 7.93 (d, 2H,
H12, J3 ¼ 8.7 Hz), 8.23 (s, 1H, H4), 8.32 (d, 2H, H13, J3 ¼ 8.7 Hz), 8.58 (br, 1H,
NH). 13C NMR (DMSO-d6) (ppm): d ¼ 108.0, 116.6, 119.7, 120.8, 124.8, 127.2,
128.4, 130.5, 133.7, 140.8, 147.6, 153.5, 157.7. Mp (ꢁC) ¼ 182. Calculated for
C15H10N2O3: C, 67.67%; H, 3.76; N, 10.53. Found: C, 67.73%; H, 3.81; N, 10.49.
6-Bromo-3-(p-nitrophenyl)iminocoumarin (2a). IR (KBr) (cmꢀ1):
1
=
n ¼ 1653 (C N), 3288 (NH). H NMR (DMSO-d6) (ppm): d ¼ 6.93 (d, 1H, H8,
J3 ¼ 8.7 Hz), 7.50 (dd, 1H, H7, J3 ¼ 8.7 Hz, J4 ¼ 2.4 Hz), 7.66 (d, 1H, H5, J4 ¼
2.4 Hz), 7.94 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.13 (s, 1H, H4), 8.30 (d, 2H, H13,
J3 ¼ 8.7 Hz), 8.76 (br, 1H, NH). 13C NMR (DMSO-d6) (ppm): d ¼ 109.4, 110.3,
117.4, 118.6, 122.8, 124.7, 127.2, 130.4, 135.6, 140.2, 140.4, 147.6, 156.9. Mp
(ꢁC) ¼ 222. Calculated for C15H9BrN2O3: C, 52.17%; H, 2.60; N, 8.11. Found: C,
52.28; H, 2.64; N, 7.95.
7-Diethylamino-3-(p-nitrophenyl)iminocoumarin (3a). IR (KBr) (cmꢀ1):
n ¼ 1650 (C N), 3291 (NH). 1H NMR (CDCl3) (ppm): d ¼ 1.21 (t, 6H, CH3,
=
J3 ¼ 7.2), 3.41 (q, 4H, CH2, J3 ¼ 7.2), 6.35 (d, 1H, H8, J4 ¼ 2.4 Hz), 6.46 (dd, 1H,
H6, J3 ¼ 8.7 Hz, J4 ¼ 2.4 Hz), 7.18 (d, 1H, H5, J3 ¼ 8.7 Hz), 7.54 (s, 1H, H4), 7.83
(d, 2H, H12, J3 ¼ 8.7 Hz), 8.24 (d, 2H, H13, J3 ¼ 8.7 Hz), 8.28 (s, 1H, NH). 13C
NMR (CDCl3) (ppm): d ¼ 12.5, 44.8, 96.7, 107.6, 108.4, 121.2, 123.6, 128.9, 129.0,
136.1, 144.1, 150.5, 155.7, 159.6, 164.0. Mp (ꢁC) ¼ 120. Calculated for
C19H19N3O3: C, 67.65%; H, 5.63; N, 12.46. Found: C, 68.02%, H, 5.64; N, 12.55.
6-Methoxy-3-(p-nitrophenyl)iminocoumarin (4a). IR (KBr) (cmꢀ1):
n ¼ 1647 (C N), 3293 (NH). 1H NMR (DMSO-d6) (ppm): d ¼ 3.75 (s, 3H,
=
CH3O), 6.92 (d, 1H, H8, J3 ¼ 9 Hz), 7.01 (dd, 1H, H7, J3 ¼ 9 Hz, J4 ¼ 3 Hz), 7.59

1022
L. BENMAKTOUF ET AL.
(d, 1H, H5, J4 ¼ 3 Hz), 7.93 (d, 2H, H12, J3 ¼ 9 Hz), 8.20 (s, 1H, H4), 8.31 (d, 2H, H13,
J3 ¼ 9 Hz), 8.48 (br, 1H, NH). 13C NMR (DMSO-d6) (ppm): d ¼ 56.1, 112.1, 116.2,
118.4, 120.3, 123.5, 124.9, 127.2, 128.6, 143.5, 147.4, 147.8, 155.4, 162.3. Mp
(ꢁC) ¼ 210. Calculated for C16H12N2O4: C, 64.86%; H, 4.05, N, 9.46. Found: C,
65.03%; H, 4.04; N, 9.22.
7-Methoxy-3-(p-nitrophenyl)iminocoumarin (5a). IR (KBr) (cmꢀ1):
n ¼ 1648 (C N), 3276 (NH). 1H NMR (DMSO-d6) (ppm): d ¼ 3.77 (s, 3H,
=
CH3O), 6.51 (d, 1H, H8, J4 ¼ 2.1 Hz), 6.59 (dd, 1H, H6, J3 ¼ 8.7 Hz, J4 ¼ 2.1 Hz),
7.89 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.06 (d, 1H, H5, J3 ¼ 8.7 Hz), 8.16 (s, 1H, H4), 8.29
(d, 2H, H13, J3 ¼ 8.7 Hz), 8.45 (s, 1H, NH). 13C NMR (DMSO-d6) (ppm):
d ¼ 55.8, 101.4, 104.0, 106.9, 114.0, 118.7, 124.9, 126.7, 129.4, 130.3, 141.1, 147.1,
160.1, 164.1 Mp (ꢁC) ¼ 208. Calculated for C16H12N2O4: C, 64.86%; H, 4.05; N,
9.46. Found: C, 65.02%; H, 4.03; N, 9.24.
General Procedure for the Synthesis of N-Ureaiminocoumarins
(1b–5b)
4-phenylsemicarbazide (3 mmol) was added with 5 ml of acetic acid to a stirred
mixture of iminocoumarins (3 mmol) and chloroform (25 ml). The mixture was stir-
red for an appropriate time (Table 1) at room temperature. A red or orange solid was
precipitated from the reaction mixture and was collected by filtration. It was recrys-
tallized from an appropriate solvent.
Data
1-[3-(p-Nitrophenyl)-2H-chromen-2-ylidene]-4-phenylsemicarbazide (1b).
IR (KBr) (cmꢀ1): n ¼ 1710 (C O), 3378 (NH). 1H NMR (DMSO-d6) (ppm):
=
d ¼ 6.94–7.54 (m, 9H, Ar), 7.47 (s, 1H, H4), 8.03 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.32 (d,
2H, H13, J3 ¼ 8.7 Hz), 8.41 (br, 1H, NH) 10.11 (br, 1H, NH). 13C NMR (DMSO-
d6) (ppm): d ¼ 109.3, 115.1, 117.9, 119.6, 121.4, 122.2, 124.1, 126.8, 128.3, 128.6,
131.1, 133.6, 139.9, 141.4, 147.3, 152.9, 157.6, 157.9. Mp (ꢁC) ꢂ 260. Calculated
for C22H16N4O4: C, 66%; H, 4; N, 14. Found: C, 65.62%; H, 4.03; N, 14.08.
1-[3-(p-Nitrophenyl)-6-bromo-2H-chromen-2-ylidene]-4-phenylsemicar-
1
bazide (2b). IR (KBr) (cmꢀ1): n ¼ 1706 (C O), 3378 (NH). H NMR (DMSO-d6)
=
(ppm): d ¼ 6.98–7.42 (m, 5H, Ar), 7.28 (d, 1H, H8, J3 ¼ 8.7 Hz), 7.4 (s, 1H, H4),
7.61 (dd, 1H, H7, J3 ¼ 8.7 Hz, J4 ¼ 2.4 Hz), 7.74 (d, 1H, H5, J4 ¼ 2.4 Hz), 8.01 (d,
2H, H12, J3 ¼ 9 Hz), 8.31 (d, 2H, H13, J3 ¼ 9 Hz), 8.41 (br, 1H, NH), 10.19 (br,
1H, NH). 13C NMR (DMSO-d6) (ppm): d ¼ 116.1, 117.7, 119.0, 122.7, 122.8,
123.8, 129.0, 129.3, 130.0, 130.3, 130.6, 130.7, 133.7, 139.3, 142.1, 147.8, 151.4,

SYNTHESIS OF NEW IMINOCOUMARINS
1023
152.7. Mp (ꢁC) ¼ 222. Calculated for C22H15BrN4O4: C, 55.11%; H, 3.13%; N, 11.69.
Found: C, 55.32%; H, 3.08; N, 11.73.
1-[3-(p-Nitrophenyl)-7-(diethylamino)-2H-chromen-2-ylidene]-4-phenyl-
semicarbazide (3b). IR (KBr) (cmꢀ1): n ¼ 1715 (C O), 3378 (NH). 1H NMR
=
(CDCl3) (ppm): d ¼ 1.25 (t, 6H, CH3, J3 ¼ 6.9), 3.43 (q, 4H, CH2, J3 ¼ 6.9), 6.45
(d, 1H, H8, J4 ¼ 2.1 Hz), 6.48 (dd, 1H, H6, J3 ¼ 8.4 Hz, J4 ¼ 2.1 Hz), 7.03–7.41 (m,
5H, Ar), 7.15 (d, 1H, H5, J3 ¼ 8.4 Hz), 7.03 (s, 1H, H4), 7.81 (br, 1H, NH), 7.83
(d, 2H, H12, J3 ¼ 9 Hz), 8.23 (br, 1H, NH), 8.30 (d, 2H, H13, J3 ¼ 9 Hz), 13C NMR
(CDCl3) (ppm): d ¼ 12.9, 45.2, 97.3, 108.3, 108.5, 119.5, 121.2, 123.7, 123.8, 129.4,
129.6, 132.5, 138.3, 142.7, 143.5, 147.5, 150.6, 153.2, 153.4, 154.3 Mp (ꢁC) ꢂ 260.
Calculated for C26H25N5O4: C, 66.24%; H, 5.30; N, 14.85. Found: C, 66.17%; H,
5.22; N, 14.95.
1-[3-(p-Nitrophenyl)-6-methoxy-2H-chromen-2-ylidene]-4-phenylsemi-
=
1
carbazide (4b). IR (KBr) (cmꢀ1): n ¼ 1676 (C O), 3372 (NH). H NMR (DMSO-
d6) (ppm): d ¼ 3.76 (s, 3H, CH3O), 6.96–7.43 (m, 5H, Ar), 7.03 (dd, 1H, H7,
J3 ¼ 9.6 Hz, J4 ¼ 3 Hz), 7.06 (d, 1H, H8, J3 ¼ 9.6 Hz), 7.28 (d, 1H, H5, J4 ¼ 3 Hz),
7.40 (s, 1H, H4), 8.00 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.30 (d, 2H, H13, J3 ¼ 8.7 Hz), 8.38
(br, 1H, NH), 10.04 (br, 1H, NH). 13C NMR (DMSO-d6) (ppm): d ¼ 55.9, 112.1,
116.3, 117.3, 118.8, 120.8, 122.5, 123.6, 128.0, 129.1, 130.4, 131.3, 139.3, 141.5,
142.3, 146.3, 147.5, 152.6, 155.8. Mp (ꢁC) ꢂ 260. Calculated for C23H18N4O5: C,
64.18%; H, 4.18; N, 13.02. Found: C, 64.27%; H, 4.11; N, 12.96.
1-[3-(p-Nitrophenyl)-7-methoxy-2H-chromen-2-ylidene]-4-phenylsemi-
1
carbazide (5b). IR (KBr) (cmꢀ1): n ¼ 1711, 3359. H NMR (DMSO-d6) (ppm):
d ¼ 3.83 (s, 3H, CH3O), 6.83 (dd, 1H, H6, J3 ¼ 8.4 Hz, J4 ¼ 2.4 Hz), 6.95 (d, 1H,
H5, J3 ¼ 8.4 Hz), 7.00 (d, 1H, H8, J4 ¼ 2.4 Hz), 7.24–7.47 (m, 5H, Ar), 7.46 (s, 1H,
H4), 8.02 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.31 (d, 2H, H13, J3 ¼ 8.7 Hz), 8.43 (br, 1H,
NH), 10.09 (br, 1H, NH). 13C NMR (DMSO-d6) (ppm): d ¼ 55.3, 101.1, 105.7,
115.7, 119.0, 124.1, 125.2, 126.8, 127.9, 128.8, 129.5, 130.2, 138.6, 145.3, 146.1,
154.0, 158.0, 161.2, 172.5. Mp (ꢁC) ¼ 150. Calculated for C23H18N4O5: C, 64.18%;
H, 4.18; N, 13.02. Found: C, 64.22%; H, 4.22; N, 13.06.
General Procedure for the Synthesis of N-Parabanic Iminocoumarins
1c–5c
To a stirred mixture of N-ureaiminocoumarins (1.5 mmol) in 25 ml of ethylene
chloride containing 0.5 ml of pyridine, 2.25 g of oxalyl chloride were added dropwise
for 0.5 h at room temperature. The reaction mixture was then stirred for 12 h at
60 ꢁC. A yellow solid was precipitated from the reaction mixture and collected by
filtration. It was recrystallized from an appropriate solvent.

1024
L. BENMAKTOUF ET AL.
Data
N-(3’-Phenylparabanic acid)-3-(p-nitrophenyl)iminocoumarin (1c). IR
1
(KBr) (cmꢀ1): n ¼ 1739, 1773. H NMR (DMSO-d6) (ppm): d ¼ 7.37–7.77 (m, 9H,
Ar), 8.02 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.09 (s, 1H, H4), 8.33 (d, 2H, H13, J3 ¼ 8.7 Hz),
13C NMR (DMSO-d6) (ppm): d ¼ 116.2, 119.6, 121.2, 123.6, 124.8, 125.5, 125.8,
127.2, 129.5, 130.7, 130.8, 132.7, 138.6, 141.5, 147.6, 151.4, 153.1, 155.4, 156.9,
158.6. Mp (ꢁC) ꢂ 260. Calculated for C24H14N4O6: C, 63.43%; H, 3.08; N, 12.33.
Found: C, 63.77%; H, 2.95, N, 12.13.
N-(3’-Phenylparabanic acid)-6-bromo-3-(p-nitrophenyl)iminocoumarin
(2c). IR (KBr) (cmꢀ1): n ¼ 1721, 1742, 1772. 1H NMR (DMSO-d6) (ppm):
d ¼ 7.42–8.86 (m, 13H, Ar). 13C NMR (DMSO-d6) (ppm): d ¼ 117.2, 118.4, 121.7,
123.6, 126.8, 127.1, 129.1, 129.4, 130.8, 131.3, 134.9, 137.2, 141.1, 143.9, 144.2,
147.8, 150.5, 153.0, 155.8, 158.1. Mp (ꢁC) ꢂ 260. Calculated for C24H13BrN4O6: C,
54.03%; H, 2.44; N, 10.50. Found: C, 54.11%; H, 2.41; N, 10.41.
N-(3’-Phenylparabanic acid)-7-(diethylamino)-3-(p-nitrophenyl)imino-
1
coumarin (3c). IR (KBr) (cmꢀ1): n ¼ 1723, 1744, 1790. H NMR (CDCl3) (ppm):
d ¼ 1.18 (t, 6H, CH3, J3 ¼ 7.2), 3.40 (q, 4H, CH2, J3 ¼ 7.2), 6.48 (d, 1H, H8,
J4 ¼ 2.4 Hz), 6.58 (dd, 1H, H6, J3 ¼ 9 Hz, J4 ¼ 2.4 Hz), 7.30 (d, 1H, H5, J3 ¼ 9 Hz),
7.36–8.77 (m, 5H, Ar), 7.76 (s, 1H, H4), 7.86 (d, 2H, H12, J3 ¼ 6.9 Hz), 8.23 (d,
2H, H13, J3 ¼ 6.9 Hz), 13C NMR (CDCl3) (ppm): d ¼ 12.4, 44.6, 98.1, 106.2, 110.3,
121.8, 123.9, 124.3, 125.9, 128.1, 128.3, 129.2, 133.0, 137.1, 143.6, 148.2, 149.1,
150.3, 152.4, 155.8, 156.3, 159.9. Mp (ꢁC) ¼ 174. Calculated for C28H23N5O6: C,
64%; H, 4.38; N, 13.33. Found: C, 63.78%; H, 4.29; N, 13.52.
N-(3’-Phenylparabanic
acid)-6-methoxy-3-(p-nitrophenyl)iminocou-
marin (4c). IR (KBr) (cmꢀ1): n ¼ 1735, 1761, 1772. H NMR (DMSO-d6) (ppm):
d ¼ 3.80 (s, 3H, CH3O), 7.20 (dd, 1H, H7, J3 ¼ 9 Hz, J4 ¼ 3 Hz), 7.31 (d, 1H, H5,
J4 ¼ 3 Hz), 7.40 (d, 1H, H8, J3 ¼ 9 Hz), 7.46–7.57 (m, 5H, Ar), 8.03 (s, 1H, H4),
8.01 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.33 (d, 2H, H13, J3 ¼ 8.7 Hz), 13C NMR (DMSO-
d6) (ppm): d ¼ 56.1, 112.0, 117.3, 119.5, 120.2, 123.6, 125.8, 127.2, 129.1, 129.4,
130.80, 130.86, 138.6, 141.5, 145.8, 147.6, 150.7, 153.2, 156.0, 156.5, 158.8. Mp
(ꢁC) ꢂ 260. Calculated for C25H16N4O7: C, 61.98%; H, 3.30; N, 11.57. Found: C,
62.09%; H, 3.36; N, 11.48.
1
N-(3’-Phenylparabanic
acid)-7-methoxy-3-(p-nitrophenyl)iminocou-
marin (5c). IR (KBr) (cmꢀ1): n ¼ 1733, 1759, 1771. H NMR (DMSO-d6) (ppm):
d ¼ 3.81 (s, 3H, CH3O), 6.95 (dd, 1H, H6, J3 ¼ 8.3 Hz, J4 ¼ 2.1 Hz), 7.15 (d, 1H,
H5, J3 ¼ 8.3 Hz), 7.25 (d, 1H, H8, J4 ¼ 2.1 Hz), 7.42–7.63 (m, 5H, Ar), 7.56 (s, 1H,
H4), 8.12 (d, 2H, H12, J3 ¼ 8.7 Hz), 8.30 (d, 2H, H13, J3 ¼ 8.7 Hz). 13C NMR
(DMSO-d6) (ppm): d ¼ 56.2, 104.5, 109.3, 116.1, 120.5, 123.8, 124.7, 125.9, 127.9,
128.6, 129.1, 132.0, 138.4, 142.0, 146.9, 149.1, 151.3, 154.6, 159.4, 160.1, 161.2.
Mp (ꢁC) ꢂ 260. Calculated for C25H16N4O7: C, 61.98%; H, 3.30, N, 11.57. Found:
C, 62.07%; H, 3.34; N, 11.46.
1

SYNTHESIS OF NEW IMINOCOUMARINS
1025
ACKNOWLEDGMENTS
The authors acknowledge the Ministry of Higher Education, Scientific
Research, and Technology in Tunisia for their financial support. They also thank
Pr. Rachid El Gharbi for his useful discussions about this work.
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