[CH:1](NC(C)C)([CH3:3])[CH3:2].C([Li])CCC.CCCCCC.[CH:19]1([C:25]([O:27][CH3:28])=[O:26])[CH2:24][CH2:23][CH2:22][CH2:21][CH2:20]1.C(Br)C#C>O1CCCC1.CN(C)P(N(C)C)(N(C)C)=O>[CH2:3]([C:19]1([C:25]([O:27][CH3:28])=[O:26])[CH2:24][CH2:23][CH2:22][CH2:21][CH2:20]1)[C:1]#[CH:2]To a solution of diisopropylamine (879 μL, 6.22 mmol) in anhydrous tetrahydrofuran (12 mL) at −40° C. under nitrogen was added 1.6 M n-butyl lithium in hexane (3.9 mL, 6.22 mmol), followed by hexamethylphosphoramide (4 mL). The mixture was cooled down to −78° C. and added a solution of methyl cyclohexanecarboxylate (80 7 μL, 5.65 mmol) in tetrahydrofuran (4 mL) with the temperature maintained below −70° C. throughout the addition. After 15 min, propargyl bromide (80% w/w in xylene, 2.5 mL, 22.6 mmol) was added, and the reaction mixture was allowed to warm to room temperature. After 30 min, it was quenched with saturated ammonium chloride, and extracted with ethyl acetate. The organic phase was washed with water (×4), dried over MgSO4, filtered and concentrated to get 900 mg the title intermediate as a pale brown oil.
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