Ethyl Ester of 2-Chloro-3-methylaminoacrylic Acid (3a). A mixture of enolate 1 (17.25 g, 0.1 mol)
and methylamine hydrochloride 2a (0.1 mol) in chloroform (100 ml) was stirred at room temperature for 8 h.
The NaCl precipitate was filtered off and the solvent was removed from the filtrate. Distillation of the residue
1
gave enamine 3a in 80% yield; bp 63-65°C (0.09 mm Hg). H NMR spectrum (CDCl
3
, 100 MHz), δ, ppm: 1.15
(
3H, t, Me); 2.88 (3H, d, Me); 4.05 (2H, q, OCH ); 6.68 (1H, br. d, NH); 8.05 (1H, d, N=CH). IR spectrum,
2
-1
ν, cm : 1710 (C=O), 3260 (NH). Found, %: Cl 21.65; N 8.54. C
6
H
10ClNO . Calculated, %: Cl 21.71; N 8.56.
2
Ethyl Ester of 2-Chloro-3-phenylaminoacrylic Acid (3b) was obtained analogously in 87% yield;
1
mp 91°C (acetonitrile). H NMR spectrum (CDCl
3
, 100 MHz), δ, ppm: 1.32 (3H, t, Me); 4.30 (2H, q, OCH
2
);
7
.10 (5H, m, Ph); 8.15 (1H, d, N=CH). Found, %: Cl 15.70; N 6.19. C11
2
H12ClNO . Calculated, %: Cl 15.74;
N 6.21.
Ethyl Ester of 2-Chloro-3-morpholinoacrylic Acid (3c) was obtained analogously in 85% yield;
1
mp 86°C. H NMR spectrum (CDCl
3
), δ, ppm: 1.18 (3H, t, Me); 3.60 (8H, d, –(CH
2
CH
2
) O–); 4.05 (2H, q,
2
OCH
2
); 7.00 (1H, s, N=CH). Found, %: Cl 14.08; N 5.54. C10
H
14ClNO
2
. Calculated, %: Cl 14.12; N 5.57.
5
,6,13,14-Tetrahydroquinoxalino[1,2,4,5]pyrazino[1,2-a]quinoxaline-6,14-dione (4). A mixture of
corresponding enamine 3a-c (0.005 mol) and o-phenylenediamine (0.5 g, 0.005 mol) in propan-2-ol (30 ml) was
heated at reflux for 48 h. The resultant red precipitate was filtered off, washed with acetone, and dried in
1
vacuum. H NMR spectrum, δ, ppm: 6.91 (2H, s, =CH–N); 7.23 (4H, m, Ar); 7.72 (4H, m, Ar); 11.93 (2H, s,
1
3
NH). C NMR spectrum, δ, ppm: 88.25 (d, =CHN), 115.10, 120.81, 123.01, 124.91, 128.29 (Ar); 14.78
-1
(
C
=C–N), 155.45 (C=O). IR spectrum, ν, cm : 1630 (C=N), 1690 (C=O). Found, %: C 68.01; H 3.75; N 17.56.
H N
18 12 4
O . Calculated, %: C 68.35; H 3.79; N 17.72. After removal of the solvent, an additional amount of
2
benzimidazole was obtained in 40% yield; mp 169°C (170.5°C [4]).
REFERENCES
1
2
.
.
F. I. Guseinov, N. A. Yudina, and G. J. Klimentova, in: Abstracts of the 36-th IUPAC Congress, Geneva
(
1997), p. 476.
F. I. Guseinov and N. A. Judina, in: Abstracts of the 7-th International Kyoto Conference in New
Aspects of Organic Chemistry, Kyoto, Japan (1997), p. 287.
F. I. Guseinov, Chemical Sciences Doctoral Dissertation, Moscow (1999).
A. A. Potekhin (editor), Properties of Organic Compounds [in Russian], Khimiya, Leningrad (1984),
p. 44.
3
4
.
.
4
97