Synthesis
General procedure for the synthesis of 2-phenylthiazole-5-carboxylic acid from ethyl 2-phenylthiazole-5-carboxylate: to a solution of ethyl 2-phenylthiazole-5-carboxylate (3.2 g, 13.8 mmol) in methanol (50 mL) was added a sodium hydroxide solution (130 mL, 4 M). The reaction mixture was stirred at room temperature for 2 hours and subsequently concentrated under reduced pressure to remove methanol. The aqueous phase was acidified to pH=3 with aqueous hydrochloric acid (1 M) and subsequently extracted with ethyl acetate. The organic phase was dried with anhydrous sodium sulfate, filtered and concentrated to give the crude product. The crude product was purified by silica gel column chromatography, eluting to give 2-phenylthiazole-5-carboxylic acid (2.3 g, 81.8% yield).MS m/z [ESI]: 206.0 [M+H]+.
References
[1] Patent: US2018/271846, 2018, A1. Location in patent: Paragraph 0121; 0126; 0127
[2] Patent: WO2018/160878, 2018, A1. Location in patent: Page/Page column 288
[3] Journal of the American Chemical Society, 1943, vol. 65, p. 2167
[4] Helvetica Chimica Acta, 1944, vol. 27, p. 1432,1433
[5] Journal of Chemical Research, 2011, vol. 35, # 5, p. 313 - 316
