To a solution of 3.1 g of 4-(benzyloxycarbonyl-methyl-amino)-butyric acid in 80 mL DCM were added 6.5 mL of DIPEA, 1.8 g of HOBt, 2.6 g of EDC and 154 mg of DMAP. After stirring for 10 min, 2.1 g of 3,6-dimethoxy-benzene-1,2-diamine, dissolved in 20 mL DCM, were added and the mixture was stirred at rt overnight. The reaction was quenched with sat. aq. NaHCO3, the phases were separated and the organic phase was washed with brine, dried over MgSO4 and concentrated in vacuo to yield the crude title compound as black oil.
