Synthesis
2-Acetylthiophene (128 g, 1.00 mol), dimethylamine hydrochloride (90 g, 1.10 mol), paraformaldehyde (41 g, 1.40 mol), concentrated hydrochloric acid (5 mL), and isopropanol (500 mL) were mixed and heated and refluxed for 6 hours according to the method reported by Robertson [1]. Upon completion of the reaction, the reaction solution was cooled to 0 °C and stirring was continued for 1 hour. Subsequently, the reaction mixture was filtered, the solid product was washed with cold isopropanol and finally dried at 50 °C for 16 h to give 3-dimethylamino-1-(thiophen-2-yl)-propan-1-one hydrochloride (2a).
References
[1] Bioorganic Chemistry, 2016, vol. 65, p. 82 - 89
[2] Patent: CN104829587, 2017, B. Location in patent: Paragraph 0050-0052
[3] Tetrahedron Letters, 1990, vol. 31, # 45, p. 7101 - 7104
[4] Patent: EP2305669, 2011, A1. Location in patent: Page/Page column 1.1
[5] Organic Process Research and Development, 2006, vol. 10, # 5, p. 905 - 913
