Trifluoromethanesulfonic anhydride → 2-Methyl-2,3-bis-trifluoromethanesulfonyloxy-propionic acid methyl ester

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Reaction Steps

Add Tf2O (80 mL) dropwise to a cool solution (−78° C.) of 3-hydroxy-2-hydroxymethyl-2-methyl-propionic acid methyl ester (Preparation 5, 32.5 g) in dichloromethane (400 mL) and 2,6-lutidine (80 mL). Allow the reaction to reach room temperature. and stir for about 2 hours. Dilute with dichloromethane (400 mL) and wash with HCl (3% aqueous solution). Dry the organic layer over MgSO4, filter and concentrate. Subject residue to silica gel chromatography eluting with hexanes/ethyl acetate 5%, to give 2-methyl-2,3-bis-trifluoromethanesulfonyloxy-propionic acid methyl ester as a colorless oil. 1H NMR (CDCl3, 300 MHz): δ ppm 4.7 (d, 2H, J=10.3 Hz), 4.5 (d, 2H, J=10.3 Hz), 3.8 (s, 3H), 1.4 (s, 3H).

Provenance & Evidence