PROCESS FOR THE SYNTHESIS OF 2-SUBSTITUTED 1-(HYDROXY-ETHYLIDENE)-1,1-BISPHOSFONIC ACID AND SALT THEREOF OR HYDRATE

摘要

Process for the synthesis of high purity 2-substituted-l-(hydroxy-ethylidene)-1,1-bisphosphonic acid of formula (I), the salts and hydrates thereof - wherein the meaning of R is 3'-pyridyl or 2'-amino-ethylidene group - from compounds of formula (II) - wherein the meaning of R is as described above -or salts and hydrates thereof with phosphorous acid in the presence of methanesulfonic acid using phosphorus pentoxide as reagent and in given case the obtained acid is converted into a salt with base.