Ammonium Chloride → 7beta-Ethyl-estr-4-ene-3,17-dione

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To a mixture of CuI(Bu3P)4 (15.7 g, 40 mmol) in THF (50 mL) was added a 1.0 M solution of EtMgBr in THF (40 mL, 40 mmol) at −30° C., and stirred for 20 min. The reaction mixture was cooled to −78° C. and dione 54 (3.5 g, 12.94 mmol) was added. The reaction mixture was warmed to −30° C. for 0.5 h, and poured into saturated aqueous NH4Cl. The mixture was extracted with EtOAc. The combined organic layers were dried over anhydrous MgSO4, filtered, and then concentrated to afford a solid. Chromatography (20% EtOAc/hexane) yielded dione 55 as a yellow solid (1.5 g, 39%). The major 7α-ethyl isomer of 55: 1H NMR (300 MHz, CDCl3) δ0.89 (t, J=7.0 Hz, 3, CH2CH3), 0.93 (s, 3, CH3), 2.60 (dd, J=2.4, 14.3 Hz, 1), 5.85 (s, 1).

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