Methanesulfonyl chloride → N,N'-di-Boc-2-methanesulfonyloxy-1,3-diaminopropane

To a solution of tert-butyl N-(3-{[(tert-butoxy)carbonyl]amino}-2-hydroxypropyl)carbamate XXVI (1.83 g, 6.3 mmol) in DCM was added TEA (1.38 mL, 10 mmol) was added. The mixture was cooled to 10° C. before adding mesyl chloride (0.77 mL, 10 mmol) dropwise. The reaction mixture was stirred for 30 min and then the solvent was removed under reduced pressure. The residue was dissolved in DCM, washed 1 M HCl (3×), 5% aq. NaHCO3 and dried over MgSO4. The solvent was again removed under vacuum to give tert-butyl N-(3-{[(tert-butoxy)carbonyl]amino}-2-(methanesulfonyloxy)propyl)carbamate XXVII (2.31 g, 6.3 mmol, 99% yield). ESIMS found for C14H28N2O7S m/z 369 (M+H).