To a −78° C. solution of benzyl 4-(2-ethoxy-2-oxoethyl)piperidine-1-carboxylate (5.02 g, 16.4 mmol) in tetrahydrofuran (90 mL) was added lithium hexamethyldisilazide (1.0 M in THF, 18.1 mL, 18.1 mmol). After 1 h, allyl bromide (2.19 g, 18.1 mmol) was added, the reaction stirred at this temperature for 0.5 h, then warmed to 25° C. After 3 h, the reaction was quenched with saturated aqueous ammonium chloride and extracted with ethyl acetate (2×). The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated. Purification by silica gel chromatography (100% hexanes→40% hexanes/ethyl acetate) to give the title compound (4.08 g). MS 346.1 (M+1).
