Chemistry of iminofurans. Unusual reaction of 3-(4-bromophenylimino)-5- phenyl-2,3-dihydrofuran-2-one with malononitrile and ethyl cyanoacetate

Full text of DOI:10.1134/S107042801006028X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 6, pp. 933–935. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.E. Rubtsov, Z.G. Aliev, O.A. Maiorova, 2010, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 6, pp. 932–934.
SHORT
COMMUNICATIONS
Chemistry of Iminofurans. Unusual Reaction
of 3-(4-Bromophenylimino)-5-phenyl-2,3-dihydrofuran-2-one
with Malononitrile and Ethyl Cyanoacetate
A. E. Rubtsova, Z. G. Alievb, and O. A. Maiorovac
a Perm State University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: rubtsov@psu.ru
b Institute of Chemical Physics Problems, Russian Academy of Sciences,
Chernogolovka, Moscow oblast, Russia
c Institute of Technical Chemistry, Ural Division, Russian Academy of Sciences, Perm, Russia
Received December 15, 2009
DOI: 10.1134/S107042801006028X
from the viewpoint of studying chemical properties of
3-imino-2,3-dihydrofuran-2-ones that are reactive
compounds and intermediate products in the synthesis
of acyclic and heterocyclic compounds possessing bio-
logical activity [2].
3-(4-Bromophenylimino)-5-phenyl-2,3-dihydro-
furan-2-one (I) reacted with malononitrile (IIa) in an-
hydrous dioxane in the presence of triethylamine on
heating for a short time to give (5E)-2-amino-1-(4-
bromophenyl)-4-oxo-5-(2-oxo-2-phenylethylidene)-
4,5-dihydro-1H-pyrrole-3-carbonitrile (IIIa) whose
structure was proved by X-ray analysis. The reaction
of compound I with ethyl cyanoacetate (IIb) followed
analogous pattern and afforded pyrrole derivative IIIb.
Condensation of 5-aryl-2,3-dihydrofuran-2,3-di-
ones with malononitrile and ethyl cyanoacetate in
dioxane in the presence of triethylamine leads to the
formation of 6-aryl-3,4-dihydroxy-6-oxohexa-2,4-di-
enoic acid amides having a cyano or ethoxycarbonyl
group, respectively, on C2 [1]. The reaction involves
initial attack by the activated methylene group in
malononitrile or ethyl cyanoacetate on the lactone
carbonyl group of furandione with formation of acyclic
intermediate which undergoes hydrolysis of the cyano
group to amide. In the present work, instead of 5-aryl-
2,3-dihydrofuran-2,3-dione, we examined the trans-
formation of its 3-arylimino derivative under analo-
gous conditions. This transformation was interesting
N
Br
+
N
Et3N
Br
R
CN
OH
CN
Ph
O
Ph
O
O
R
I
IIa, IIb
A
R
O
H2N
Ph
R
O
N
O
O
NH
N
Ph
Br
Br
B
IIIa, IIIb
R = CN (a), EtOCO (b).
933

RUBTSOV et al.
(0.01 mol) of ethyl cyanoacetate (IIb). Yield 3.79 g
934
N3
C5
(86%), mp 264–266°C (from acetonitrile). IR spec-
trum, ν, cm–1: 3441, 3281 (NH); 1711 (C=O, ester);
1
1665, 1645 (C=O). H NMR spectrum, δ, ppm: 1.14 t
C3
C1
N2
C4
N1
C6
C2
(3H, Me), 4.07 q (2H, OCH2), 5.55 s (1H, CH), 7.60 m
(9H, Harom), 8.15 s and 8.30 s (1H each, NH2).
13C NMR spectrum, δC, ppm: 14.52 (CH3), 58.36
(CH2), 85.88 (C3), 108.53 (=CH), 123.32 (C), 128.44
(CH), 128.50 (CH), 131.36 (CH), 132.05 (C), 132.98
(CH), 133.48 (CH), 137.23 (C), 141.79 (C2), 164.48
(C5), 166.08 (CO), 174.68 (C4), 193.62 (CO). Found,
%: C 57.12; H 3.85; Br 18.15; N 6.32. C21H17BrN2O4.
Calculated, %: C 57.16; H 3.88; Br 18.11; N 6.35.
O2
O1
C13
C7
C12
C8
C14
C19
C18
C9
Br1
C15
C11
C10
C16
C17
X-Ray analysis of compound IIIa. Single crystals
of compound IIIa suitable for X-ray analysis were
obtained by crystallization from dioxane–acetonitrile
(1:9). Compound IIIa crystallized as a solvate with di-
oxane at a ratio of 2:1. C19H12N3O2·0.5C4H8O2. Mono-
clinic crystal system; unit cell parameters: a =
8.420(2), b = 19.909(4), c = 11.835(2) Å; β =
Structure of the molecule of (5E)-2-amino-1-(4-bromo-
phenyl)-4-oxo-5-(2-oxo-2-phenylethylidene)-4,5-dihydro-
1H-pyrrole-3-carbonitrile (IIIa) according to the X-ray dif-
fraction data.
Presumably, initial nucleophilic attack on the C2
atom in the furan ring by the activated methylene
group or carbanion generated by the action of triethyl-
amine gives intermediate A. The subsequent opening
of the furan ring via cleavage of the C2–O bond
produces intermediate B, and the latter undergoes
intramolecular nucleophilic attack by the NH group on
the cyano carbon atom with formation of substituted
pyrrole III.
98.90(3)°; V = 1960.1(7) Å3; M 438.28; dcalc
=
1.485 g/ cm3; Z = 4; space group P2(1)/n. The unit cell
parameters and experimental reflection intensities were
measured on a KM-4 (Kuma Diffraction) automatic
four-circle diffractometer with χ-geometry (monochro-
matized MoKα irradiation; ω–2θ scanning in the range
2.05 < 2θ < 25.01°). Total of 3976 reflections were
measured, 3067 of which were independent (Rint
=
0.0329). No correction for absorption was introduced
(μ = 2.124 mm–1). The structure was solved by the
direct statistical method using SIR92 program [3],
followed by a series of calculations of electron density
maps. The positions of hydrogen atoms were set on the
basis of geometry considerations. The structure was
refined by the least-squares procedure in full-matrix
anisotropic approximation using SHELXL-97 software
[4]; the final divergence factors were R1 = 0.0608,
wR2 = 0.1632 for 1799 reflections with I ≥ 2σ(I)
(262 refined parameters); goodness of fit 0.969.
(5E)-2-Amino-1-(4-bromophenyl)-4-oxo-5-(2-
oxo-2-phenylethylidene)-4,5-dihydro-1H-pyrrole-3-
carbonitrile (IIIa). A solution of 3.56 g (0.01 mol) of
furan-2-one I, 0.66 g (0.01 mol) of malononitrile (IIa),
and 1 g (0.01 mol) of triethylamine in 30 ml of anhy-
drous dioxane was heated for 1 min and cooled, and
the precipitate was filtered off and recrystallized from
acetonitrile. Yield 3.51 g (89%), mp 242–243°C (from
acetonitrile). IR spectrum, ν, cm–1: 3458, 3280 (NH);
2208 (C≡N); 1687, 1659 (C=O). 1H NMR spectrum, δ,
ppm: 5.57 s (1H, CH), 7.60 m (9H, Harom), 8.16 s and
8.9 s (1H each, NH2). 13C NMR spectrum, δC, ppm:
66.44 (C3), 109.75 (=CH), 114.63 (CN), 123.32 (C),
128,52 (CH), 128.66 (CH), 131.57 (CH), 131.81 (C),
133.24 (CH), 133.54 (CH), 136.98 (C), 141.41 (C2),
164.71 (C5), 177.16 (C4), 193.0 (CO). Found, %:
C 57.92; H 3.06; Br 20.31; N 10.64. C19H12BrN3O2.
Calculated, %: C 57.89; H 3.07; Br 20.27; N 10.66.
The examined crystals consist of molecules IIIa
and dioxane molecule located in the crystallographic
symmety center, so that a half of dioxane molecule fits
one molecule IIIa. The structure of molecule IIIa is
shown in figure. All bond lengths and bond angles do
not differ from the corresponding standard values. The
plane of the para-substituted phenyl ring with the pyr-
role ring plane forms a dihedral angle of 79.0°. The
orientation of the 2-oxo-2-phenylethylidene substituent
is characterized by the torsion angles N1C1C12C13
172.9° and C1C12C13C14 107.5°, and the carbonyl
group lies in the plane of the benzene ring which is
Ethyl (5E)-2-amino-1-(4-bromophenyl)-4-oxo-5-
(2-oxo-2-phenylethylidene)-4,5-dihydro-1H-pyrrole-
3-carboxylate (IIIb) was synthesized in a similar way
from 3.56 g (0.01 mol) of furanone I and 1.13 g
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 6 2010

CHEMISTRY OF IMINOFURANS.
935
turned through a dihedral angle of 75.4° with respect
to the pyrrole ring plane. Molecules IIIa in crystal are
related to each other through a glide-reflection plane n
and are linked by intermolecular hydrogen bonds
N2–H2A···O2 2.77 Å to form infinite chains. The chains
are linked by dioxane molecules into layers via hydro-
gen bonds N2–H2B···O3 2.89 Å.
plates using diethyl ether–benzene–acetone (10:9:1)
as eluent.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 08-03-00448).
REFERENCES
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 6 2010