A mixture of 1-formyl-3,4-dihydro-1H-isochromene-5-carbonitrile (65 mg, 0.35 mmol), 5-(2-piperazin-1-ylethyl)-2-benzofuran-1(3H)-one hydrochloride (100 mg, 0.35 mmol), DIEA (45 mg, 0.35 mmol), AcOH (21 mg, 0.35 mmol) in 3 mL of DCM was stirred 30 min at room temperature and then NaBH(OAc)3 (440 mg, 2.1 mmol) was added. The mixture was stirred over night at room temperature. Water was added and the mixture was extracted with DCM. The combined organic layers were washed with brine, dried over anhydrous Na2SO4, concentrated and the residue was purified by prep-HPLC to give 1-({4-[2-(1-oxo-1,3-dihydro-2-benzofuran-5-yl)ethyl]piperazin-1-yl}methyl)-3,4-dihydro-1H-isochromene-5-carbonitrile.
