To a solution of 3-(3-(3,4-dihydroisoquinolin-2(1H)-yl)-2-hydroxypropoxy)benzaldehyde (200 mg, 0.64 mmol) in DCM (15 mL) was added tetrahydro-2H-pyran-4-amine (97 mg, 0.96 mmol). The solution was heated at 60° C. for 0.5 h. Then, NaBH(OAc)3 (204 mg, 0.96 mmol) was added into the reaction mixture and heated at 60° C. for another 1 h. The reaction mixture was quenched by adding 1N HCl aqueous solution and diluted with DCM then washed with NaHCO3 aqueous solution. The separated organic layer was concentrated and the crude product was purified by preparative HPLC purification. (40 mg, yield 17%) MS (ESI+) e/z: 397.2 [M+1]+. 1H NMR (MeOD, 400 MHz), δ ppm: 7.36 (t, J=8.0 Hz, 1H), 7.19-7.15 (m, 3H), 7.11-7.02 (m, 4H), 4.39-4.33 (m, 1H), 4.16 (s, 2H), 4.08-4.00 (m, 6H), 3.49-3.40 (m, 3H), 3.25-3.20 (m, 2H), 3.15-3.03 (m, 4H), 2.12-2.02 (m, 2H), 1.71-1.60 (m, 2H).
