tert-Butyl 2-(4-acetylphenyl)morpholine-4-carboxylate (210 mg, 0.69 mmol) was dissolved in THF (3.5 ml). Lithium-bis-(trimethylsilyl)-amide solution (2.05 ml, 2.05 mmol, 1.0 M solution in THF) was added dropwise and the yellow reaction mixture was stirred at −78° C. for 1 hour. 4-Chlorobenzoyl chloride (120 mg, 0.69 mmol) was added and the reaction mixture was stirred for 90 min and was quenched by addition of 1M aqueous hydrochloric acid. Ethyl acetate was added and the organic layer was dried over MgSO4 and evaporated. The crude material was purified by flash chromatography (10 g silica gel, 10 to 50% ethyl acetate in heptane) to yield an off-white solid (215 mg, 70%). MS (ISP): 388.2 ([{35Cl}M-tBu+H]+), 390.3 ([{37Cl}M-tBu+H]+).
