Sodium Hydroxide → 2-[(Benzyloxy)carbonyl]-2-azaspiro[4.5]decane-4-carboxylic acid

To a solution of (6) (300 mg; 0.9 mmol) in a mixture dioxane/water (6 mL; 9:1) was added a 2 M solution of NaOH (0.90 mL; 1.8 mmol). The reaction mixture was stirred at 35° C. for 6 hours. Solvents were removed in vacuo. The residue was diluted in water (15 mL) and was washed with diethyl ether (3×10 mL). The aqueous phase was acidified with 2N HCl and was extracted with ethyl acetate (3×15 mL). The ethyl acetate extracts were combined, dried over MgSO4, and concentrated to give 254 mg (0.8 mmol, 89%) of (7) as a colorless gum.