[CH:1](NC(C)C)(C)C.C([Li])CCC.[CH2:13]([O:15][C:16](=[O:30])[CH:17]1[CH2:22][CH2:21][N:20]([C:23]([O:25][C:26]([CH3:29])([CH3:28])[CH3:27])=[O:24])[CH2:19][CH2:18]1)[CH3:14].CI>C1COCC1.C(OCC)(=O)C>[CH2:13]([O:15][C:16](=[O:30])[C:17]1([CH3:1])[CH2:18][CH2:19][N:20]([C:23]([O:25][C:26]([CH3:29])([CH3:28])[CH3:27])=[O:24])[CH2:21][CH2:22]1)[CH3:14]To a stirring solution of diisopropylamine (20.0 mmol, 2.02 g) in THF (50 mL) cooled to -78° C. was added n-butyllithium (21.7 mmol, 8.68 mL of a 2.5M solution in hexanes). N-tert-butoxycarbonyl isonipecotic acid ethyl ester (16.7 mmol, 4.5 g) was then added dropwise followed by methyl iodide (16.7 mmol, 2.37 g)and the reaction allowed to warm to room temperature. The mixture was then diluted with ethyl acetate (500 mL) and washed with water (1×200 mL), 10% KHSO4 (200 mL) and brine, dried over anhydrous sodium sulfate and evaporated under reduced pressure to give 4.76 g of the title compound as a pale yellow oil.
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