Unusual synthesis of 2-(2-aryl-2-oxo-ethylidene)-3-oxo-1,2,3,4-tetrahydro- quinoxalin-1-yl(N-cyano-O-phenyl)-carboximidates

Full text of DOI:10.1007/s10593-009-0308-5

Chemistry of Heterocyclic Compounds, Vol. 45, No. 2, 2009
UNUSUAL SYNTHESIS OF 2-(2-ARYL-2-OXO-
ETHYLIDENE)-3-OXO-1,2,3,4-TETRAHYDRO-
QUINOXALIN-1-YL(N-CYANO-O-PHENYL)-
CARBOXIMIDATES
D. D. Nekrasov1*, S. S. Namitova1, and N. Yu. Lisovenko1
Keywords: N-(2-aminophenyl)-N'-cyano-O-phenylisourea, 5-aryl-2,3-dihydrofuran-2,3-diones, 2-(2-aryl-
2-oxoethylidene)-3-oxo-1,2,3,4-tetrahydroquinoxalin-1-yl(N-cyano-O-phenyl)carboximidates,
recyclization.
We have previously reported that heating 5-aryl-2,3-dihydrofuran-2,3-diones (1) with N-cyano-N'-phenyl-
S-methylisothiourea in anhydrous toluene gave 6-aryl-2-[(methylthio)(phenylamino)methylene]amino-
4H-1,3-oxazin-4-ones [1]. When this reaction was carried out in the case of the N-(2-aminophenyl)-N'-cyano-
O-phenylisourea (2) the 2-(2-aryl-2-oxoethylidene)-3-oxo-1,2,3,4-tetrahydroquinoxalin-1-yl(N-cyano-O-phenyl)-
carboximidates 3 were unexpectedly separated from the reaction mixture.
OPh
N
CN
H
N
HN
O
NH2
O
N
CH
2
O
p-RH4C6
O
NC
O
OPh
N
C6H4R-p
– H2O
1, 3 a R = H, b R = Me
1a,b
3a,b
Evidently in the first stage of the reaction opening of the furan ring at the O–C(1) bond by the NH2
group of the isourea 2 occurs with intermediate formation of the N-[[(2-cyanoimino)(phenoxy)-
methyl]amino]phenyl-2,4-dioxo-4-arylbutanamide (4a) existing in solution in the tautomeric form 4b [2]. This is
1
confirmed by the initial observation in the H NMR spectrum of the reaction mass at room temperature of a
methine group proton signal at 6.90, a multiplet for 14 benzene rings protons in the range 7.05-8.10, and signals
for the corresponding amino groups protons at 10.48 and 12.28 ppm. In the IR spectra the absorption for the
stretching band of the cyano group in the isourea fragment is preserved at 2200 and a characteristic strong
absorption band at 1675 cm-1 is observed corresponding to the amide carbonyl.
_______
* To whom correspondence should be addressed, e-mail: kpibas@psu.ru.
1Perm State University, Perm 614990, Russia.
__________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 778-780, May, 2009. Original
article submitted December 5, 2008.
0009-3122/09/4505-0617©2009 Springer Science+Business Media, Inc.
617

Subsequent raising of the temperature to 50-60ºC leads to a spontaneous intramolecular cyclization
involving the enolic hydroxyl and the secondary amino group in the intermediate 4 to form the final compounds 3.
O
O
HO
HC
O
H2C
N
N
H
H
C
C
Ph
HN
CN
Ph
HN
CN
O
O
N
N
PhO
PhO
4b
1
4a
IR spectra were recorded on a UR-20 instrument in vaseline oil. H NMR spectra were taken on a
Mercury Plus 300 instrument (300 MHz) using CDCl3 with TMS as internal standard.
3-Oxo-2-(2-oxo-2-phenylethylidene)-1,2,3,4-tetrahydroquinoxalin-1-yl(N-cyano-O-phenyl)carbox-
imidate (3a). A solution of the N-(2-aminophenyl)-N'-cyano-O-phenylisourea (2) (1.26 g, 5 mmol) and
5-phenyl-2,3-dihydrofuran-2,3-dione (1a) (0.9 g, 5 mmol) in dioxane (30 ml) was stirred for 40 min at 50-60ºC
to give a yellow precipitate of compound 3a with mp 180-181ºC (2-propanol) in 63% yield. IR spectrum, ν,
cm-1: 1675 (C=O), 1665 (C=O), 2200 (C≡N), 3386 (NH). 1H NMR spectrum, δ, ppm: 7.05-8.10 (14H, m, C6H5);
6.90 (1H, s, =CH−); 12.28 (1H, s, NH). The spectroscopic data was closely similar to that for previously
obtained quinoxalines [3]. Found, %: C 70.9; H 4.0; N 13.6. C24H16N4O3. Calculated, %: C 70.6; H 3.9; N 13.7.
3-Oxo-2-(2-oxo-2-p-tolylethylidene)-1,2,3,4-tetrahydroquinoxalin-1-yl(N-cyano-O-phenyl)carbox-
imidate (3b) was prepared similarly from compounds 1b and 2. Yield 75%, mp 195-197ºC (2-propanol). IR
spectrum, ν, cm-1: 1670 (C=O), 1660 (C=O), 2195 (C≡N), 3380 (NH). 1H NMR spectrum, δ, ppm: 2.36 (3H, s,
CH3); 7.05-8.10 (13H, m, Ar); 6.90 (1H, s, =CH−); 12.28 (1H, s, NH). Found, %: C 71.2; H 4.1; N 13.4.
C25H18N4O3. Calculated, %: C 71.1; H 4.3; N 13.3.
This work was carried out with the support of the Russian Fund for Basic Research (project No. 08-03-
00488-a).
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