(Z)-Methyl 

2-(2-(2-amino-1-cyano-2-oxoethylidene)-3-(4-chlorophenyl)-4-oxothiazolidin-5-ylidene) acetate (4c)

yellow solid; Mp: 265-267 oC; IR (KBr): 3473, 3331, 3285, 3209, 3072, 2203, 1744, 1674, 1526, 1476, 1392, 1330, 1224, 1195, 1014, 875 cm-1; 1H NMR (400 MHz, DMSO-d6) (δ, ppm): 7.778 (s, 1H), 7.647-7.579 (m, 4H), 7.382 (s, 1H), 6.814 (s, 1H), 3.826 (s, 3H); 13C NMR (100 MHz, DMSO-d6) (δ, ppm): 165.88, 164.56, 164.55, 161.77, 141.36, 135.56, 133.47, 131.48, 129.52, 117.01, 113.00, 81.22, 52.63. HRMS (ESI): m/z calcd for C15H10ClN3NaO4S, 385.9978 [M+Na]+; found: 385.9984.