“…This was used in the next step without further purification but can also be purified by chromatography on silica gel (heptane/EtOAc, 40:60) to afford pure alcohol 22a as an oil: IR (film) ν max 3446, 2973, 2921, 1774, 1677, 1464, 1420, 1374, 1170, 1043, 1015, 975, 908, 839, 796, 690 cm −1 ; 1 H NMR (300 MHz, CDCl 3 ) δ 5.75 (1H, dd, J = 1.0, 15.5 Hz, H-6), 5.59 (1H, dd, J = 8.0, 15.5 Hz, H-7), 4.41 (1H, dd, J = 8.0, 10.0 Hz, H-5a), 3.97 (1H, t, J = 8.5 Hz, H-5b), 3.19 (1H, sext, J = 8.5, H-4), 2.65 (1H, dd, J = 8.5, 17.5 Hz, H-3a), 2.34 (1H, dd, J = 9.5, 17.5 Hz, H-3b), 1.30 (6H, s, H-9 and H-10); 13 Preparation of Cyclopropylmagnesium Bromide. 75 To a stirred suspension of magnesium turnings (300 mg, 12.30 mmol) in dry THF (2.0 mL) under argon was added commercially available cyclopropyl bromide (0.800 mL, 9.99 mmol) in dry THF (12.2 mL) dropwise at room temperature for 30 min. During this operation, the reaction continued refluxing without heating.…”