2-Methyl-4-bromo-aniline (1.68 g, 9.05 mmol, 1 eq) was dissolved in 1,2-dichloroethane (95 mL). A solution of 4-(3-Oxo-propyl)-piperidine-1,4-dicarboxylic acid 1-tert-butyl ester 4-ethyl ester (2.8 g, 9.05 mmol, 1 eq) in 95 mL of 1,2-dichloroethane was added to the previous solution followed by glacial acetic anhydride (1.74 g, 28.05 mol, 3.1 eq) and NaBH(OAc)3 (5.76 g, 27.15 mmol, 3 eq). The reaction mixture was stirred for 48 h, quenched with 200 mL of water, transferred to a separatory funnel and extracted with dichloromethane (2×100 mL). The combined organics were dried over Na2SO4 and purified by column chromatography on silica gel (200 g column, 25% EtOAc in heptanes; 50 mL/min). This gave 3.78 g (86%) of the title compound as a beige gum.
