Unusual impurity formation during the process development of Olsalazine sodium leads to a new efficient and economical synthesis of tricaine mesylate

Abstract

An impurity formation during the nitro group reduction for the synthesis of Olsalazine Sodium API, which was later explored for the development of a short and efficient manufacturing process for tricaine mesylate is reported here. The highlight of the synthesis is, during the nitro group reduction, the deoxygenation occurs forming the core of tricaine and the leaving mesyloxy group serves as a counter anion furnishing the tricaine mesylate in one step. The reported process here circumvents the need for isolation of the free base and a separate salt formation step, thus it is more economical and efficient.