Substituent effects on the regioselectivity of maleamic acid..., Y. FATURACI, N. COS¸KUN
injection temperature. The retention times of the peaks in the chromatograms and the corresponding mass
spectra were identical with those of the corresponding 4g-l.
Synthesis of (Z)-2-methyl-4-oxo-4-(arylamino)but-2-enoic acid 3a-f. General procedure: To
a solution of 3-methylmaleic anhydride (20 mmol, 2.2872 g) in THF (60 mL) was added aniline derivative (20
mmol) and the mixture heated at reflux for 2 h. The solvent was partly evaporated and the mixture left to
crystallize at room temperature. The formed crystals were collected by filtration and dried under vacuum.
(Z)-2-methyl-4-oxo-4-(phenylamino)but-2-enoic acid 3a. Yield, 3.283 g, 80%. White crystals, mp
;
175-176 ◦ C. Lit2 mp 172 ◦ C. IR (KBr) νOH 3449, νNH 3287, νC=O 1709, νC=C 1631 cm−1 1 H-NMR (400
MHz, DMSO-d6): δ 1.96 (3H, s), 6.08 (1H, s), 7.03 (1H, t, J = 7.0 Hz), 7.28 (2H, t, J = 7.6 Hz), 7.59 (2H,
d, J = 8.8 Hz), 10.14 (1H, s), 12.9 (1H, brs). 13 C-NMR (100 MHz, DMSO-d6): δ 21.0; 119.6; 123.6; 123.9;
129.2; 139.4; 143.1; 163.1; 170.7. Anal calcd for C11 H11 NO3 (205.21) C, 64.38; H, 5.40; N, 6.83; Found C,
64.50; H, 5.25; N, 6.90.
(Z)-4-(p-toluidino)-2-methyl-4-oxobut-2-enoic acid 3b. Yield, 3.771 g, 86%. Yellowish crystals,
;
mp 179-180 ◦ C. IR (KBr) νOH 3477, νNH 3289, νC=O 1700, νC=C 1632 cm−1 1 H-NMR (400 MHz, DMSO-
d6): δ 1.96 (3H, s), 2.23 (3H, s), 6.06 (1H, s), 7.09 (2H, d, J = 8.0 Hz) 7.47 (2H, d, J = 8.0 Hz), 10.07 (1H,
s), 12.9 (1H, s). 13 C-NMR (100 MHz, DMSO-d6): δ 20.9, 21.0; 119.6; 123.6; 129.6; 132.9, 136.8, 143.0; 162.9;
170.6. Anal calcd for C12 H13 NO3 (219.24) C, 65.74; H, 5.98; N, 6.39; Found C, 66.00; H, 6.04; N, 6.59.
(Z)-4-(4-methoxyphenylamino)-2-methyl-4-oxobut-2-enoic acid 3c. Yield, 4.328 g, 92%. Green
;
powder, mp 181-182 ◦ C. IR (KBr) νOH 3500, νNH 3279, νC=O 1690, νC=C 1627 cm−1 1 H-NMR (400 MHz,
DMSO-d6): δ 1.96 (3H, s), 3.70 (3H, s), 6.06 (1H, s), 6.87 (2H, d, J = 7.6 Hz) 7.51 (2H, d, J = 7.6 Hz), 10.06
(1H, s), 13.0 (1H, s). 13C-NMR (100 MHz, DMSO-d6): δ 21.1; 55.6; 114.3; 121.2; 123.7; 132.4; 142.8; 155.8;
162.7; 170.5. Anal calcd for C12 H13 NO4 (235.24) C, 61.27; H, 5.57; N, 5.95; Found C, 61.13; H, 5.60; N, 6.00.
(Z)-2-methyl-4-(4-nitrophenylamino)-4-oxobut-2-enoic acid 3d.12 Yield, 1.5 g, 30%. Yellow
needles, mp 166-167 ◦ C. IR (KBr) νOH 3473 cm−1 , νNH 3279, νC=O 1702, νC=C 1633 cm−1
;
1 H-NMR
(400 MHz, DMSO-d6): δ 1.98 (3H, s), 6.11 (1H, s), 7.83 (2H, d, J = 9.2 Hz) 8.2 (2H, d, J = 9.2 Hz), 10.71
(1H, s), 12.9 (1H, s). 13C-NMR (100 MHz, DMSO-d6): δ 20.8; 119.3; 123.2; 125.5; 142.7; 144.2; 145.7; 163.9;
170.5. Anal calcd for C11 H10 N2 O5 (250.21) C, 52.80; H, 4.03; N, 11.20; Found C, 53.00; H, 3.91; N, 11.30.
(Z)-4-(4-chlorophenylamino)-2-methyl-4-oxobut-2-enoic acid 3e. Yield 3.834 g, 80%. Cream
;
powder, mp 188-189 ◦ C. IR(KBr) νOH 3464, νNH 3280, νC=O 1707, νC=C 1631 cm−1 1 H-NMR(400 MHz,
DMSO) : δ 1.96 (3 H, s), 6.06 (1H, s), 7.34 (2H, d, J = 8.8 Hz), 7.62 (2H, d, J = 8.8 Hz), 10.26 (1H, s), 12.86
(1H, s). 13 C-NMR (100 MHz, DMSO-d6): δ 20.9; 121.2; 123.4; 127.4; 129.1; 138.4; 143.3; 163.2; 170.6. Anal
calcd for C11 H10 ClNO3 (239.65) C, 55.13; H, 4.21; N, 5.84; Found C, 55.30; H, 3.97; N, 6.01.
(Z)-4-(4-bromophenylamino)-2-methyl-4-oxobut-2-enoic acid 3f. Yield 4.546 g, 80%. Yellow
;
powder, mp 185-186 ◦ C. IR (KBr) νOH 3456, νNH 3282, νC=O 1710, νC=C 1634 cm−1 1 H-NMR (400 MHz,
DMSO): δ 1.96 (3 H, s), 6.06 (1H, s), 7.47 (2H, d, J = 9.2 Hz), 7.57 (2H, d, J = 9.2 Hz), 10.26 (1H, s), 12.86
(1H, s). 13 C-NMR (100 MHz, DMSO-d6): δ 20.9; 115.4; 121.5; 123.4; 132.0; 138.8; 143.3; 163.2; 170.6. Anal
calcd for C11 H10 BrNO3 (284.11) C, 46.50; H, 3.55; N, 4.93; Found C, 46.55; H, 3.38; N, 5.10.
Synthesis of N-aryl maleimides 4a-f. General procedure: To a solution of maleic anhydride 2a
(20 mmol, 2.2872 g) in THF (60 mL) was added aniline derivative (20 mmol) and the reaction mixture stirred
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