General procedure for the synthesis of (1R,2R)-N-Boc-1,2-cyclohexanediamine from di-tert-butyl dicarbonate and lev-trans-1,2-cyclohexanediamine: (R,R)-cyclohexanediamine (5.70 g, 50.0 mmol) was dissolved in 1,4-dioxane (110.0 mL). A solution of Boc-anhydride (1.09 g, 5.0 mmol) in 1,4-dioxane (35.0 mL) was slowly added dropwise with stirring at room temperature. After the dropwise addition, the reaction was continued with stirring for 5 hours. Upon completion of the reaction, the solvent was removed by rotary evaporation and the resulting residue was dissolved in water (55 mL). The insoluble material was removed by filtration and the filtrate was extracted with dichloromethane (3 x 55 mL). The organic phases were combined, washed with water, the organic layer was separated, dried with anhydrous magnesium sulfate, filtered and concentrated by rotary evaporation. Finally, purification by silica gel column chromatography afforded the yellow solid product (1R,2R)-N-Boc-1,2-cyclohexanediamine (1.00 g, 94% yield).
