General procedure for the synthesis of benzyl (1,3-dihydroxypropan-2-yl) carbamate from benzyl chloroformate: to a stirred slurry of 1.00 g (4.24 mmol) of N-benzyloxycarbonyl-1,3-dihydroxy-2-aminopropane and 0.65 mL (4.7 mmol) of triethylamine in 10 mL of THF at 0°C under argon gas protection over a 10-minute period 0.6 mL (4.2 mmol) of benzyl chloroformate (Aldrich) was slowly added dropwise. The reaction mixture was gradually warmed to room temperature and stirred continuously for 14 hours. After completion of the reaction, the mixture was diluted with ether and filtered. The filtrate was concentrated by evaporation and the residue was dissolved in 25 mL of methanol, 2 drops of dioxane solution with 4N HCl were added and the solution was heated to 40°C and maintained for 30 minutes. The solvent was subsequently evaporated and the residue was ground with a hexane/ether solvent mixture to give benzyl (1,3-dihydroxypropan-2-yl)carbamate as a white solid in 92% yield (880 mg) with a melting point of 104-106 °C. The mass spectrum (electrospray, positive ion mode) showed a m/z of 226.
