General procedure for the synthesis of tert-butyl 3-(4-aminophenyl)azetidine-1-carboxylate from tert-butyl 3-(4-nitrophenyl)azetidine-1-carboxylate: 10% Pd/C (0.320 g) and 3-(4-nitrophenyl)tert-butyl 3-(4-nitrophenyl)azetidine-1-carboxylate (16) (2.14 g, 7.68 mmol) were mixed in a EtOAc (16 mL) solution was suspended under hydrogen atmosphere and the reaction was stirred for 18 hours. Subsequently, 10% Pd/C (1.00 g) was added supplementally and stirring was continued for 20 hours. Upon completion of the reaction, the mixture was filtered through a Celite pad, the filter cake was washed with EtOAc, and the filtrates were combined and concentrated in vacuo to afford the title compound 17 as a light yellow to cream solid (1.80 g, 94% yield). The product was identified by 1H NMR (300 MHz, CDCl3): δ 7.12 (d, J = 8.3 Hz, 2H), 6.69 (dd, J = 6.5, 1.9 Hz, 2H), 4.29 (t, J = 8.7 Hz, 2H), 3.93 (dd, J = 8.4, 6.1 Hz, 2H), 3.65 (brs, 2H), 1.55- 1.68 (m, 1H), 1.48 (s, 9H).LCMS analysis: retention time 4.964 min; m/z 249 [M + H]+.
