Synthesis
GENERAL METHOD: Cyclohexanone (1.06 mL, 10 mmol), ethyl cyanoacetate (1.15 mL, 10 mmol), morpholine (0.90 mL, 10 mmol), and sulfur powder (0.32 g, 10 mmol) were dissolved in ethanol (10 mL), and the reaction was stirred and refluxed overnight. After completion of the reaction, the mixture was cooled to room temperature and the solvent was removed by distillation under reduced pressure. The resulting crude product was washed with cold ethanol, filtered through a sintered funnel and dried under vacuum. The dried crude product was dissolved in dichloromethane and washed with saturated saline. The organic layer was separated and concentrated under reduced pressure to afford the target compound ethyl 2-amino-4-methylthiophene-3-carboxylate (2a) in 73% yield (1.83 g).
References
[1] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 13, p. 4418 - 4427
[2] European Journal of Medicinal Chemistry, 2014, vol. 86, p. 270 - 278
[3] Patent: CN107151251, 2017, A. Location in patent: Paragraph 0006; 0010
[4] Organic and Biomolecular Chemistry, 2014, vol. 12, # 24, p. 4233 - 4242
[5] Journal of Molecular Catalysis B: Enzymatic, 2013, vol. 95, p. 29 - 35
