Sodium hydroxide (1.0 g, 25 mmol) was added to a suspension of estrone (1.35 g, 5.0 mmol) and pyridine-3-carbaldehyde (595 mg, 5.0 mmol) in ethanol (40 mL) at room temperature. The resulting dark orange solution was stirred at room temperature for 4 hours. Then glacial acetic (ca. 10 mL) acid was added with stirring. The colour changed to light yellow and a light yellow solid precipitated. The solid was filtered off and washed with water (50 mL), ethanol (20 mL), diethyl ether (50 mL) and hexane (50 mL) and dried under high vacuum. Yield: 1.6313 g (90%) yellow powder. 1H-NMR (DMSO-d6, 400 MHz), δ: 0.90 (s, 3H, —CH3), 1.26-1.66 (m, 5H), 1.82-1.90 (m, 1H), 1.95-2.02 (m, 1H), 2.14-2.22 (m, 1H), 2.30-2.38 (m, 1H), 2.57-2.66 (m, 1H), 2.70-2.81 (m, 2H), 2.83-2.92 (m, 1H), 6.45 (d, J=2.3 Hz, 1H), 6.51 (dd, J=8.2, 2.3 Hz, 1H), 7.04 (d, J=8.2 Hz, 1H), 7.34 (s, 1H), 7.47 (dd, J=8.2, 5.1 Hz, 1H), 8.06 (d, J=8.2 Hz, 1H), 8.56 (dd, J=4.7, 1.2 Hz, 1H), 8.82 (d, J=1.6 Hz, 1H), 9,03 (s, 1H, —OH). LRMS (FAB+): 360.2 (100, [M+H]+). LRMS (FAB−): 276.1 (100), 358.2 (90, [M−H]−). HRMS (FAB+): 360.196434 C24H26NO2 requires 360.196354
