2. Synthesis of [1α,5α,6α]-3-benzyloxycarbonyl-6-(hydroxymethyl)-3-azabicyclo[3.1.0]hexanes
Benzyl ester of rel-(1R,5S,6r)-6-(hydroxymethyl)-3-azabicyclo[3.1.0]hexane-3-carboxylate (1.0 g, 8.8 mmol) was dissolved in a mixed solvent of dioxane (40 mL) and water (40 mL). Sodium bicarbonate (3 g, 36 mmol) and benzyl chloroformate (1.3 mL, 9.1 mmol) were added sequentially. After 30 min of reaction, the reaction mixture was extracted with ethyl acetate. The organic layers were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give the title compound as an oil (2.15 g, 8.7 mmol, 99% yield).
1H NMR (CDCl3) δ: 7.32 (br s, 5H), 5.08 (s, 2H), 3.65 (m, 2H), 3.46 (m, 4H), 1.45 (m, 2H), 0.91 (m, 1H).