1: methyl 3-aminothiophene-2-carboxylate With sodium hydroxide; water T=120°C; 0.5 h; Heating / reflux; 2: With hydrogenchloride in water T=0°C; pH=5.0; 3: di-tert-butyl dicarbonate With ammonia; oxalic acid; triethylamine more than 3 stages;
Xie, Hui; Ng, Danny; Savinov, Sergey N.; Dey, Barna; Kwong, Peter D.; Wyatt, Richard; Smith III, Amos B.; Hendrickson, Wayne A.
Journal of Medicinal Chemistry, 2007 , vol. 50, # 20 p. 4898 - 4908