85614-89-7

172095-72-6

623-47-2

85614-89-7

ii) A solution of propionyl chloride (1.55 mL, 17.4 mmol) dissolved in 3.5 mL of toluene was slowly added dropwise to a 10 mL solution of toluene containing N-tert-butyldimethylsilyl isopropylcarboximide (3.51 g, 17.4 mmol) and triethylamine (12.2 mL, 87 mmol) at room temperature. The reaction mixture was stirred at room temperature for 2 hours before 10 mL of hexane was added. The precipitate was removed by filtration and the filter cake was washed with hexane (3 x 5 mL). The filtrate was concentrated under reduced pressure to give a clarified oil. The oily substance was dissolved in 15 mL of toluene, followed by the addition of ethyl propargylate (1.2 mL, 11.6 mmol). The reaction mixture was stirred at 85 °C for 70 hours. After completion of the reaction, the mixture was concentrated under reduced pressure and then diluted with 2N hydrochloric acid. The aqueous phase was extracted with dichloromethane (DCM). The organic phases were combined, dried with anhydrous sodium sulfate and concentrated under reduced pressure to give the crude product as a yellow paste (3.5 g). The crude product was purified by silica gel fast column chromatography using hexane/ethyl acetate (75/25 to 0/100) as elution gradient, and finally ethyl 6-hydroxy-5-methylnicotinate (1.65 g, 78.5% yield) was obtained as yellow powder. The product was confirmed by electrospray mass spectrometry (ES-MS): m/z 182.1 [M + H]+ and retention time (tR) 3.28 min (System 2).