Methanesulfonyl chloride (0.550 g; 0.0048 mol) at 0° C. was added drop-wise to a solution of (7-benzenesulfonyl-2,3-dihydro-benzo[1,4]dioxin-2(R)-yl)-methanol (0.73 g; 0.00238 mol) and triethyl amine (0.48 g; 0.0048 mol) in dichloromethane (10 mL). The mixture was stirred at 0° C. for 45 minutes, and then diluted with dichloromethane (20 mL), washed with water, dried (Na2SO4) and concentrated in vacuo. The crude material was purified by flash chromatography on silica gel (hexane-ethyl acetate; 1:1) to give methansulfonic acid 7-benzenesulfonyl-2,3-dihydro-benzo[1,4]dioxin-2(S)-yl-methyl ester as a foam (0.67 g; 73%): MS (M+H)+ 385.
