To a solution of N-PMB diamine (300 mg, 1.0 mmol) in absolute MeOH (15 mL) was added 10% Pd/C (212 mg, 0.2 mmol, 0.2 eq.) at room temperature under N2. Then the N2 was replaced by H2. The reaction mixture was stirring at room temperature for 16 hours. The solid was filtered and washed with MeOH (20 mL). The filtrate was evaporated under reduced pressure. The residue was purified by flash column chromatography on neutral alumina using MeOH/DCM (1-3%) to give the product as a colorless oil (171 mg, 88%).