361440-67-7

197142-36-2

361440-67-7

At -15°C, (1S,3S,5S)-2-(tert-butoxycarbonyl)-2-azabicyclo[3.1.0]hexane-3-carboxylic acid (1.2 g) was dissolved in THF (20 ml) and 4-methylmorpholine (710 μl) was added. Subsequently, isobutyl chloroformate (780 μl) was added slowly over a period of 5 min and stirring was continued at this temperature for 30 min. The reaction system was cooled to -30°C and aqueous ammonia solution (25 ml, 0.5 M) dissolved in dioxane was slowly added. The reaction mixture was stirred at -30 °C for 30 min and then gradually warmed to room temperature and continued stirring overnight. After completion of the reaction, the pH was adjusted to 4.5 with 10% aqueous citric acid solution and extracted with ether (3 x 50 ml). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. Finally, purification by silica gel column chromatography (eluent: cyclohexane/ethyl acetate, 1:10) afforded the target product (1S,3S,5S)-tert-butyl (1.0 g, 84% yield, MNa+ = 248) of (1S,3S,5S)-3-(aminocarbonyl)-2-azabicyclo[3.1.0]hexane-2-carboxylate.