1H, JAB = 6.0 Hz, benzyl-CH2), 3.24 (AB-system, 1H, JAB = 6.0 Hz, benzyl-CH2), 2.46 (s, 3H, CH3); 13C-
NMR (CDCl3): δ 189.6, 169.3, 162.4, 134.2, 129.1, 129.0, 128.3, 127.8, 124.7, 61.5, 53.0, 37.8, 24.9;
Anal. Calcd for C16H16N2O5S: C, 55.16; H, 4.63; N, 8.04. Found: C, 55.01; H, 4.52; N, 7.91.
Methyl 2-(5-acetyl-3-nitro-2-thienyl)-2-[(5-acetyl-3-nitro-2-thienyl)amino]propionate (4)
The mixture of 1 (0.512 g, 2.5 mmol) and L-alanine methyl ester hydrochloride (1.117 g, 8 mmol) was
stirred in dry DMF (5 mL) at rt for 16 h. After purification on a silica gel column eluting with toluene/
ethyl acetate ( 8 + 2) 4 (66 mg, 6 %) was obtained; mp 230-2320C (ethanol); MS: m/z (rel. int.) 441 (M+,
31), 382 (100); 1H-NMR (CDCl3, 300 MHz): δ 10.28 (s, 1H, NH), 8.12 (s, 1H, thiophene-H), 7.88 (s, 1H,
thiophene-H), 3.88 (s, 3H, CH3), 2.63 (s, 3H, CH3), 2.40 (s, 3H, CH3), 2.26 (s, 3H, CH3); 13C-NMR
(CDCl3): δ 189.6, 189.1, 169.3, 157.2, 148.0, 144.1, 142.3, 128.4, 128.3, 128.0, 125.2, 62.2, 54.7, 26.2,
25.1, 23.4; Anal. Calcd for C16H15N3O8S2: C, 43.53; H, 3.43; N, 9.52. Found: C, 43.59; H, 3.41; N, 9.30.
Methyl 2-(5-acetyl-3-nitro-2-thienyl)-2-[(5-acetyl-3-nitro-2-thienyl)amino]-2-phenylpropionate (5)
The mixture of 1 (0.512 g, 2.5 mmol) and L-phenylalanine methyl ester hydrochloride (1.726 g, 8 mmol)
was stirred in dry DMF (5 mL) at rt for 24 h. After purification on a silica gel column eluting with
toluene/ ethyl acetate ( 8 + 2) 5 (78 mg, 6 %) was obtained; mp 2290C (ethanol); MS: m/z (rel. int.) 518
(M+, 4), 427 (98), 198 (100), 91 (68); 1H-NMR (CDCl3, 300 MHz): δ 9.97 (br s, 1H, NH), 8.12 (s, 1H,
thiophene-H), 7.96 (s, 1H, thiophene-H), 7.34-7.23 (m, 3H, phenyl-H), 6.95-6.87 (m, 2H, phenyl-H), 4.21
(AB-system, 1H, JAB = 13.1 Hz, benzyl-CH2), 3.72 (AB-system, 1H, JAB = 13.1 Hz, benzyl-CH2), 3.78 (s,
3H, CH3), 2.66 (s, 3H, CH3), 2.46 (s, 3H, CH3); 13C-NMR (CDCl3): δ 189.6, 189.1, 166.9, 157.1, 147.0,
144.7, 142.7, 131.8, 129.6, 128.9, 128.7, 128.3, 128.2, 128.1, 125.6, 66.8, 54.2, 40.8, 26.3, 25.2; Anal.
Calcd for C22H19N3O8S2: C, 51.06; H, 3.70; N, 8.12. Found: C, 50.86; H, 3.74; N, 7.91.
(2S)-Ethyl 2-[(5-acetyl-3-nitro-2-thienyl)amino]-3-phenylpropionate (7)
The mixture of 1 (0.512 g, 2.5 mmol) and L-phenylalanine ethyl ester hydrochloride (1.837 g, 8 mmol)
was stirred at 400C for 48 h. After crystallization from ethanol 6 (842 mg, 93 %) was obtained; mp 930C;
[α]D –46.0 0 ( c 1.0, toluene); MS: m/z (rel. int.) 362 (M+, 45), 289 (31), 271 (42), 91 (100); 1H-NMR
(CDCl3, 300 MHz): δ 8.85 (d, 1H, J = 7.9 Hz, NH), 7.89 (s, 1H, thiophene-H), 7.38–7.11 (m, 5H, phenyl-
H), 4.38-4.29 (m, 1H, CH), 4.24 (q, 2H, J = 6.2 Hz, CH3), 3.35 (AB-system, 1H, JAB = 6.2 Hz, benzyl-
CH2), 3.24 (AB-system, 1H, JAB = 6.2 Hz, benzyl-CH2), 2.45 (s, 3H, CH3), 1.26 (t, 3H, J = 7.1 Hz, CH3);
13C-NMR (CDCl3): δ 189.5, 168.8, 162.3, 134.2, 129.1, 128.9, 127.7, 126.8, 124.5, 62.4, 61.5, 37.8, 24.9,
13.9; Anal. Calcd for C17H18N2O5S: C, 56.34; H, 5.01; N, 7.73. Found: C, 56.21; H, 5.00; N, 7.65.