[OH:1][C@H:2]([CH3:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4].[CH3:9][S:10](Cl)(=[O:12])=[O:11]>C1COCC1>[CH3:9][S:10]([O:1][C@H:2]([CH3:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4])(=[O:12])=[O:11](R)-ethyl 2-hydroxypropanoate (15 g, 0.127 mol) and TEA (15.4 g, 0.15 mol) were added to THF and then cooled to 10-15° C. Then MsCl (15 g, 0.13 mol) was added to the solution dropwise with cooling while maintaining the temperature in the range of 10-15° C. at about 2 hours. The mixture was allowed to warm to about 20° C. and the solid was filtered off. The solution was washed with water and dried, concentrated to afford (R)-ethyl 2-(methylsulfonyloxy)propanoate (15 g, 60%). 1H NMR (400 MHz, CDCl3) δ ppm, 5.11-5.14 (q, 1H), 4.24-4.29 (m, 2H), 2.81-3.17 (q, 3H, J=7.2 Hz), 1.61-1.43 (d, 3H, J=7.6 Hz), 1.30-1.32 (m, 3H).
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