Trifluoroacetic anhydride → (3S)-3-Hydroxy-4-methoxy-4-oxobutanoic acid

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Reaction Steps

L-malic acid (10 g., 74.6 mmole) was placed in a 100 ml. round-bottom flask and cooled in an ice bath. Trifluoroacetic anhydride, TFAA, (25 ml.) was added to the flask and the suspension was stirred in the cold. Within 15 minutes a homogeneous solution was obtained. After stirring for 2 hours at a temperature of about 0° C., the TFAA and trifluoroacetic acid were removed by vacuum distillation at 0° C. The solid residue of L-malic anhydride trifluoroacetate represented by the formula ##STR84## was dissolved in 50 ml. of anhydrous methyl alcohol and the solution stirred at room temperature for 3.5 hours. The solvent was removed by evaporation to provide in 100% yield L-malic acid monomethyl ester melting at about 75° to about 79° C. After recrystallization from ethyl acetate-hexane the product melted at about 79° to about 80° C. [α]D20 =5.8±1° (C=9.5, methanol).

Provenance & Evidence