To a solution of tert-butyl 3-formyl-5-methylphenylcarbamate (200 mg, 0.85 mmol) and acetylpiperazine (131 mg, 1.02 mmol) in 0.1 mL HOAc and 4 mL dichloroethane was added NaBH(OAc)3 (216 mg, 1.02 mmol) at room temperature. After 2 hours additional acetylpiperazine (131 mg, 1.02 mmol) and NaBH(OAc)3 (216 mg, 1.02 mmol) were added. After 2 hours the mixture was diluted with saturated NaHCO3. The layers were separated and the aqueous extracted with CH2Cl2 (3×). The combined organic layers were dried (MgSO4), filtered, and concentrated. Flash column chromatography (5% MeOH/CH2Cl2) gave tert-butyl 3-[(4-acetylpiperazin-1-yl)methyl]-5-methylphenylcarbamate as a white foam:
