To a solution of EXAMPLE 6C (300 mg) in tetrahydrofuran (2 mL) and N,N′-dimethylformamide (2 mL) was added tert-butyl 4-aminopiperidine-1-carboxylate (320 mg,) in N,N′-dimethylformamide (2 mL) and tetrahydrofuran (2 mL) at −40° C. The solution was warmed to ambient temperature over 2 hours, and stirred for 16 hours. The solvent was removed, and the concentrate was partitioned between ethyl acetate and water. The extract was washed with brine and concentrated, and the concentrate was purified by flash chromatography on silica gel with 80% ethyl acetate in hexanes.
