Trityl chloride → HCID 178498696, compound

200 g of D-serine methyl ester hydrochloride was added to 1.8 L of chloroform, and the reaction solution was cooled to 0° C., to which 448 mL of triethylamine was then slowly added. 358.4 g of trityl chloride was slowly added to the reaction mixture which was then stirred for 1 hour. The reaction mixture was warmed to room temperature, and 1 L of chloroform was added thereto, followed by washing with 2.5 L of water. The organic layer was dried over magnesium sulfate and cooled to 0° C., to which 484 mL of triethylamine and 15.7 g of 4-methylaminopyridine were then sequentially and slowly added. The reaction mixture was stirred for 5 min and 139 mL of methane sulfonyl chloride was slowly added thereto. The reaction mixture was warmed to room temperature, stirred for another 4 hours and then refluxed for 12 hours. The reaction mixture was cooled to room temperature, and washed with 4 L of water and then 3 L of brine. The organic layer was dried over magnesium sulfate and concentrated to dryness under reduced pressure. 3 L of ethanol was added to the resulting residue which was then stirred. The resulting solids were filtered to afford 329 g of the title compound.