1032903-63-1

1032903-52-8

1032903-63-1

Tert-butyl 4-(5-isopropyl-2-methyl-4-nitrophenyl)-3,6-dihydropyridine-1-carboxylate (22.6 g, 0.06 mol) was used as a raw material, which was added to methanol (226 mL) with carbon-loaded palladium hydroxide (20% w/w, 2.26 g). The reaction mixture was stirred at 30-40 °C for 5 h in hydrogen pressure (1 MPa). The completion of the reaction was monitored by TLC. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated. To the concentrate n-heptane was added and stirred at 0-10 °C for 2 h to crystallize. The crystals were collected by filtration and the filter cake was dried under vacuum at 40-50 °C to afford tert-butyl 4-(4-amino-5-isopropoxy-2-methylphenyl)piperidine-1-carboxylate as a white solid powder (19.9 g, yield: 95.0%).