To diethyl ether (300 mL) at −78° C. was slowly added EtMgBr (3.0 M, 16.6 mL) and then dropwise the compound from Step B of Example 62 (4.80 g, 10.0 mmol) in anhydrous Et2O (100 mL). The reaction mixture was stirred at −78° C. for 15 min, allowed to warm to −15° C. and stirred for another 2 h, and then poured into a stirred mixture of water (300 mL) and Et2O (600 mL). The organic phase was separated, dried (MgSO4), and evaporated in vacuo. The crude product was purified on silica gel using ethyl acetate/hexane (1:2) as eluent. Fractions containing the product were pooled and evaporated in vacuo to give the desired product (3.87 g) as a colorless oil.
