Isopropenyl acetate → 2-Methoxy-3,17-diacetoxyestra-1,3,5(10),14,16-pentaene

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Reaction Steps

Under nitrogen, toluenesulfonic acid monohydrate (0.1 g, 0.53 mmol) was added to a solution of 2-Methoxyestra-1,3,5(10),15-tetraen-3-ol-17-one prepared in Example 3 (0.25 g, 0.84 mmol), isopropenyl acetate (5 mL, 45.15 mmol) and acetic anhydride (5 mL, 53 mmol) and the mixture was heated to reflux for 6 h. At the end of that time, analysis by tlc (2% acetone in CH2Cl2) indicated a complete reaction. The reaction was cooled to room temperature, poured into ice water (˜100 mL) and stirred for 1 h. The mixture was extracted with methylene chloride (3x). The organic fractions were washed with water (1x), saturated sodium bicarbonate solution (1x) and water (1x), filtered through anhydrous sodium sulfate, combined and concentrated in vacuo. The residue was crystallized from methanol to give the pure diacetate (17) (0.259 g, 80.8%).

Provenance & Evidence