Preparation method of Minodronic acid hydrate

The present invention discloses a method for preparing minodronic acid hydrate, which is: firstly be protected keto compound (VII), to give the compound (Ⅵ), then compound (Ⅵ) and 2-aminopyridine nucleophilic substitution reaction, to give the compound (ⅴ), cyclization reaction of the compound (ⅴ) occurs stripped keto group is protected, the obtained compound (Ⅳ); compound (Ⅳ) hydrolysis to give compound (ⅲ), compound (ⅲ) by bis-phosphorylated after the compound (ⅱ), rear (ⅱ) compound was recrystallized minodronic acid hydrate (ⅰ); synthetic route starting material source of the present invention sufficient, low cost, the reagents used in the reaction environment-friendly, and industrial production safety, and mild reaction conditions, easy to operate, less side effects, the treatment is simple, no special reaction apparatus or complicated, easy industrial production.