Synthesis
General procedure for the synthesis of methyl 5-amino-2-thiophenecarboxylate from methyl 5-nitro-2-thiophenecarboxylate: Methyl 5-nitro-2-thiophenecarboxylate (11.55 mmol) was dissolved in ethanol (20 mL), and 10% palladium carbon catalyst (1 g) was added. The reaction mixture was hydrogenated overnight with stirring under hydrogen atmosphere. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was subsequently concentrated to afford the target product methyl 5-amino-2-thiophenecarboxylate (1.67 g, 92% yield). The product was detected by LCMS (ESI) and showed a molecular ion peak of 157 [M+H]+.
References
[1] Patent: WO2006/65788, 2006, A2. Location in patent: Page/Page column 10
[2] Patent: US2007/43045, 2007, A1. Location in patent: Page/Page column 59
[3] Bioorganic and Medicinal Chemistry Letters, 2002, vol. 12, # 10, p. 1379 - 1382
[4] Patent: WO2004/108683, 2004, A1. Location in patent: Page 564-565
[5] Patent: WO2004/18480, 2004, A1. Location in patent: Page 156
