Patent ID: 8178712

Claim:
A process for the synthesis of Ibandronate sodium of formula (I) comprising: (i) N-alkylating N-benzyl methylamine with 1-bromopentane or methyl-3-halopropionate to form an N-alkylated intermediate; (ii) Debenzylating the N-alkylated intermediate to form a secondary amine; (iii) N-alkylating the secondary amine with 1-bromopentane or methyl-3-halopropionate to obtain methyl 3-[N-(methylpentyl)amino]propionate of formula (IV) (iv) Hydrolysing 3-[N-(methylpentyl)amino]propionate of formula (IV) to obtain methyl 3-[N-(methylpentyl)amino]propionic acid of formula III; (v) Reaction of 3-[N-(methylpentyl)amino]propionic acid (III) with phosphorus acid, halophosphorus compound in an organic solvent selected from toluene, chlorobenzene, xylene, methane sulphonic acid benzene sulphonic acid, ethylene dichloride, tetrahydrofuran, tetrachloro ethane, dioxane, at a temperature of 50° C. to 100° C.; (vi) Solvent removal followed by reflux in water and addition of sodium hydroxide; and (vii) Precipitation of ibandronate sodium of formula (I) in an organic solvent without the isolation of ibandronic acid