小中大这个是先通过羧酸做重排到异氰酸酯再水解到伯胺步骤：
To a mixture of (3RS,4SR)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-3-carboxylic acid (2.281 g, 7.0 mmol) and Et3N (1.2 ml, 8.61 mmol) in toluene (30 ml) was added DPPA (1.8 ml, 8.37 mmol) at room temperature. After the mixture was stirred at room temperature for 30 min, the temperature was gradually warmed to 80 °C, and the mixture was stirred at 80 °C for 1 h. After cooling, the mixture was poured into 8N NaOH (30 ml, 240 mmol) with vigorously stirring. To this was added 2N HCl (100 ml), and the mixture was extracted with EtOAc(x2). The organic layer was washed with brine(x2), dried over Na2SO4 and concentrated in vacuo. The residue was purified by column chromatography (silica gel, eluted with 0% - 40% MeOH in EtOAc) to give (3RS,4SR)-tert-butyl 3-amino-4-(3-chlorophenyl)pyrrolidine-1-carboxylate (1.728 g, 5.82 mmol, 83 %) as a colorless solid.
