Ibandronate and Alendronate/Alendronic acid were prepared by the reaction of the corresponding amino acids (N-methyl-Npentylalanine
and γ-aminobutyric acid) with 3.2 equivalents of phosphorus trichloride, in the absence of any phosphorous acid, in
methanesulfonic acid at 75 °C for 12 h followed by hydrolysis, pH adjustment and purification. The first intermediate of the reaction sequence
is the corresponding chloride (>N(CH2)nC(O)Cl) or mixed ester (>N(CH2)nC(O)OS(O)2Me).
Keywords: Ibandronate, Alendronate, Synthesis, Optimization, Intermediate.
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