1211526-53-2

1374658-94-2

1211526-53-2

General procedure for the synthesis of 2-BOC-2-azaspiro[3.3]heptane-6-carboxylic acid from tert-butyl 6-cyano-2-azaspiro[3.3]heptane-2-carboxylate: 6-cyano-2-azaspiro[3.3]heptane-2-carboxylic acid tert-butyl ester (2.0 g, 9.0 mmol) was dissolved in a mixed solvent of ethanol (40 mL) and water (40 mL), followed by addition of potassium hydroxide (2.0 g, 36.0 mmol). The reaction mixture was stirred at room temperature overnight. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding agent was petroleum ether/ethyl acetate, v/v=1/1, Rf=0.0) and after confirming the completion of the reaction, most of the ethanol was removed by concentration under reduced pressure. The pH of the remaining solution was adjusted to 3-4 with 1N hydrochloric acid and the aqueous phase was extracted with dichloromethane. The organic phase was dried over anhydrous sodium sulfate and subsequently concentrated to dryness under reduced pressure to afford 2-BOC-2-azaspiro[3.3]heptane-6-carboxylic acid (1.3 g, 62% yield).