Ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate

• thienopyrimidine derivatives
• azo dyes
• N-(3-ethoxycarbonyl-4,5,6,7-tetrahydrobenzo[b]thien-2-yl)-2-aryl hydrazono-3-oxobutanamide derivatives
• tetrahydrobenzo[b]thiophene dyes

108-94-1

105-56-6

4506-71-2

GENERAL METHOD: Cyclohexanone (1 mmol), ethyl cyanoacetate (1 eq.), morpholine (1 eq.), and elemental sulfur (1 eq.) were dissolved in 5 mL of ethanol at 0°C and the reaction was stirred overnight. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was extracted three times with ethyl acetate, the organic layers were combined and dried over anhydrous sodium sulfate. After drying, the solvent was again evaporated under reduced pressure. The final product was obtained as purified ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate by recrystallization from a mixed methanol/water solvent as a yellow crystalline solid. Yield: 98%, melting point 134-135 °C. 1H NMR (400 MHz, DMSO-d6) δ 1.20 (3H, t, J = 7.1 Hz, CH3), 1.60-1.65 (4H, m, CH2), 2.35-2.37 (2H, m, CH2), 2.55-2.56 (2H, m, CH2), 4.11 (2H , q, J = 7.3 Hz, OCH2CH3), 7.14 (2H, br s, NH2).13C NMR (100 MHz, DMSO-d6) δ 14.18 (CH3), 22.34 (CH2), 22.76 (CH2), 23.88 (CH2), 26.49 (CH2), 58.71 (OCH2), 103.16 (Cq), 115.96 (Cq), 131.50 (Cq), 163.19 (Cq), 165.32 (C=O).