Patent ID: 8759582

Claim:
Improved process for the preparation of lacosamide of formula-I, which comprises: (i) reaction of D-serine with Boc anhydride in the presence of a base in aqueous medium at −10 to 30° C. to get N-Boc derivative of formula-XVI, (ii) reaction of N-Boc derivative of formula-XVI with dimethyl sulphate in the presence of a base in aqueous medium at 0-30° C. to get the compound of formula-XVII, (iii) reaction of compound of formula-XVII with trifluoroacetic acid at 0-60° C. to get the novel trifluoroacetate salt of O-methyl-D-serine of formula-XXXII, (iv) acetylation of compound of formula-XXXII with acetic anhydride or acetyl chloride to get the compound of formula-XIII, (v) amidation of compound of formula-XIII with benzylamine via a carbamate intermediate at −100 to 35° C. to get crude lacosamide of formula-I, (vi) recrystallization of crude lacosamide from a solvent to get pharmaceutically acceptable grade lacosamide.