General Steps:
Step 1: Synthesis of 4-(tert-butoxycarbonylamino)butyric acid: 4-aminobutyric acid (25 g, 242 mmol) was dissolved in H2O (500 mL) at room temperature, Na2CO3 (75 g, 726 mmol) was added, followed by dropwise addition of a THF (200 mL) solution of Boc2O (95 g, 435 mmol). The reaction mixture was stirred at room temperature for 12 h and then concentrated under reduced pressure. The aqueous phase was extracted with Et2O, followed by adjusting the pH to 4-5 with citric acid and extracting with EtOAc. The organic layers were combined, dried over Na2SO4 and concentrated to give 4-(tert-butoxycarbonylamino)butyric acid (45 g, 90%) as a colorless oil.ESI-MS (EI+, m/z): 226 [M + Na]+.
Step 2: Synthesis of methyl 4-(tert-butoxycarbonylamino)butyrate: 4-(tert-butoxycarbonylamino)butyric acid (7.0 g, 34.5 mmol) and K2CO3 (9.5 g, 68.9 mmol) were dissolved in acetone (70 mL) and MeI (7.5 g, 51.8 mmol) was added at room temperature. The reaction solution was stirred at 45 °C for 12 hours. Upon completion of the reaction, the mixture was washed with water and saturated NaCl solution, dried over Na2SO4 and concentrated to give methyl 4-(tert-butoxycarbonylamino)butyrate (6.2 g, 83%) as a yellow oil.ESI-MS (EI+, m/z): 240 [M + Na]+.
![4-[[(1,1-dimethylethoxy)carbonyl]amino]Butanoic acid methyl ester](/CAS/20180703/GIF/85909-04-2.gif)