Pyridine → Estra-1,3,5(10),7,16-pentaen-3-yl acetate

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Reaction Steps

A solution of estra-1,3,5(10),7,16-pentaen-3-ol (5, 192.1 mg, 0.7612 mmol) in anh. pyridine (2.6 mL, 32 mmol) and acetic anhydride (0.36 mL, 3.8 mmol) was stirred 6 h, after which 30 mL of ethyl acetate were added. The mixture was washed with three 10 mL portions of 1 N hydrochloric acid+10 mL of saturated sodium bicarbonate+10 mL of brine, dried over magnesium sulfate, and filtered through diatomaceous earth. See Example 15. The residue was washed with 10 mL of ethyl acetate and the combined filtrates were concentrated under reduced pressure. Preparative TLC (5% ethyl acetate/hexanes on silica gel GF, 1000μ thickness) and recrystallization from aqueous ethanol gave fine white needles (78.6 mg, 0.267 mmol, 35%), m.p. 77-80° C. TLC (4% ethyl acetate/hexanes on silica gel) showed 2 spots at Rf 0.21 and 0.24.

Provenance & Evidence