Synthesis
General procedure for the synthesis of 2-(1H-pyrazol-4-yl)ethanol from 3-(diethoxymethyl)-2-ethoxytetrahydrofuran: To intermediate 47A (30.00 g, 137.00 mmol) was slowly added hydrazine dihydrochloride (18.75 g, 179.00 mmol) dissolved in a mixture of water (50 mL) and ethanol (25 mL) at 0 °C. solution. The reaction mixture was stirred at 0°C for 1 hour and then continued to stir at room temperature for 1 hour. Sodium carbonate (30.00 g) was added to the reaction mixture and then evaporated to dryness under reduced pressure. The residue was washed with ethanol (10 mL) and evaporated again to give Intermediate 47B (15.00 g, 92% yield) as a brown oil. The product was analyzed by 'HNMR (400 MHz, CDCI3) with chemical shifts of 6 ppm 2.78 (t, J=6.38 Hz, 2H), 3.72 (d, J=7.25 Hz, 1H), 3.77-3.88 (m, 2H), 7.49 (s, 2H), and 9.52-10.74 (m, 1H).The LCMS analysis (Method-i) showed a retention time of 0.40 min and [M-H]- peak of 113.0.
References
[1] Patent: WO2018/93569, 2018, A1. Location in patent: Page/Page column 134
[2] Journal of the American Chemical Society, 1953, vol. 75, p. 4048,4050
