The general procedure for the synthesis of tert-butyl rel-(1R,5S,6r)-6-(hydroxymethyl)-3-azabicyclo[3.1.0]hexane-3-carboxylate from di-tert-butyl dicarbonate and exo-3-azabicyclo[3.1.0]hexan-6-ylmethanol was as follows: (1R,5S,6R)-3-azabicyclo[3.1.0]hexan-6-ylmethanol (10 g. 88.4 mmol) was dissolved in a solvent mixture of dioxane and water (3:2, v/v), followed by addition of sodium hydroxide (4.2 g, 106 mmol) and di-tert-butyl dicarbonate (28.9 g, 132.6 mmol). After the reaction was carried out for 10 h, 50 mL of water was added to the reaction mixture. The reaction mixture was extracted with ethyl acetate (150 mL each time, 3 times). The organic phases were combined, washed with saturated sodium chloride solution (50 mL each time, 2 times), then dried with anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the resulting residue was purified by silica gel column chromatography using elution system C. The target product (1R,5S,6R)-tert-butyl 6-(hydroxymethyl)-3-azabicyclo[3.1.0]hexane-3-carboxylate (16.9 g, 89.9% yield) was obtained as a pale yellow liquid.