To a solution of (R)—N-naphthalene-2-sulfonyl (3-methanesulfonyloxy-cycloheptyl)glycine ethyl ester (0.60 g, 1.24 mmol) in N,N-dimethylformamide (5 mL) is added cesium carbonate (1.21 g, 3.71 mmol) followed by lithium iodide (0.249 g, 1.86 mmol), and the reaction is heated to 80° C. for 3 hours. The reaction is cooled to ambient temperature, diluted with water, and extracted three times with ethyl acetate. The combined organic extracts are washed with brine, dried over magnesium sulfate, and concentrated in vacuo. The crude product is purified by column chromatography (20% hexanes-ethyl acetate) to afford the title compound as a white solid (0.37 g, 77% yield). LCMS (m/z): 388.10 (M+1).
