A mixture of EXAMPLE 307B (1.24 g), tert-butyl piperazine-1-carboxylate (0.768 g), and potassium carbonate (0.570) in N,N-dimethylformamide (20 mL) was stirred at room temperature for 2 hours. The reaction mixture was partitioned between ethyl acetate and water. The organic layer was separated, and the aqueous layer was extracted with additional ethyl acetate three times. The combined organic layers were washed with brine, dried over MgSO4, filtered, and concentrated. The residue was purified with flash column chromatography on silica gel using 10% ethyl acetate in hexanes to give the title compound.
