Under stirring, add 1-aminocyclobutylcarboxylic acid (500mg, 4.34mmol) to 10mL of 0.5M sodium hydroxide solution, and add 10mL of 1,4-dioxane and di-tert-butyl dicarbonate (1.42g, 6.51 mmol), react for 15 hours. Extract with diethyl ether (20 mL × 2), add hydrochloric acid dropwise until the pH of the aqueous phase is 4, and extract with ethyl acetate (30 mL × 3). The organic phases were then combined, washed with saturated sodium chloride solution (20mL×2), dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain the product N-Boc-1-aminocyclobutanecarboxylic acid (750mg, white solid), yield:80.6%.
