Process for production of optically active mirtazapine

Abstract

The invention provides a process for efficiently producing optically active mirtazapine. Specifically, a process for production of optically active mirtazapine wherein an RS mixture of mirtazapine is optically resolved with optically active tartaric acid in the presence of a solvent. More specifically, a process for production of optically active mirtazapine, characterized by making an RS mixture of mirtazapine contact with optically active tartaric acid in the presence of a solvent, and preferentially crystallizing the optically active mirtazapine salt. The solvent is preferably a mixed solvent consisting of a water-soluble organic solvent and water, and more preferably a mixed solvent consisting of a C1-3 alcohol and water.

1 . A process for production of optically active mirtazapine wherein an RS mixture of mirtazapine is optically resolved with optically active tartaric acid in the presence of a solvent. 
   
   
       2 . A process for production of optically active mirtazapine, characterized by making an RS mixture of mirtazapine contact with optically active tartaric acid in the presence of a solvent, and preferentially crystallizing the optically active mirtazapine salt. 
   
   
       3 . The process according to  claim 2 , wherein the obtained optically active mirtazapine salt is further made to contact with a base. 
   
   
       4 . The process according to  claim 2 , wherein the solvent is a mixed solvent consisting of a water-soluble organic solvent and water. 
   
   
       5 . The process according to  claim 4 , wherein the water-soluble organic solvent is a C1-3 alcohol solvent. 
   
   
       6 . The process according to  claim 2 , wherein the optically active tartaric acid is L-tartaric acid and the obtained optically active mirtazapine is S-mirtazapine. 
   
   
       7 . A salt consisting of optically active tartaric acid and optically active mirtazapine. 
   
   
       8 . A salt consisting of L-tartaric acid and S-mirtazapine. 
   
   
       9 . A salt consisting of D-tartaric acid and R-mirtazapine. 
   
   
       10 . The process according to  claim 5 , wherein the optically active tartaric acid is L-tartaric acid and the obtained optically active mirtazapine is S-mirtazapine.