24424-99-5

16636-51-4

334932-13-7

Step 1: Synthesis of 3-(tert-butoxycarbonylamino)-1-cyclohexanecarboxylic acid; 1 N NaOH (41.9 mL, 105 mmol) was added to a suspension of cis-3-aminocyclohexanecarboxylic acid (10 g, 69.8 mmol) in 1,3-dioxane (100.0 mL). After stirring for 10 min, the mixture became a clarified solution followed by the addition of di-tert-butyl dicarbonate (21.08 mL, 91 mmol). The reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the resulting solid was collected by vacuum filtration and then dissolved in water (150 mL). The aqueous phase was acidified to pH 4 with 3 N HCl and then extracted with dichloromethane (DCM, 2 × 100 mL). The organic phases were combined and dried over anhydrous sodium sulfate (Na2SO4) and subsequently concentrated under reduced pressure to afford 3-(tert-butoxycarbonylamino)-1-cyclohexanecarboxylic acid as a white powder (17.0 g, 100% yield).