A METHOD FOR THE PREPARATION OF MIRTAZAPINE

摘要

The present invention relates to a method for the preparation of mirtazapine and tetracyclic analogous compounds having substantial enantiomeric excess of the R or S form. The invention further relates to a novel intermediate and its use for the preparation of mirtazapine having a substantial enantiomeric excess of the R or S form. The method comprising the steps of a: providing a carboxylic acid compound according to Formula (I) having a substantial enantiomeric excess of the R or S form, b: converting the carboxylic acid group of compound I into a ketone group, producing a ketone compound of Formula (II), c: optionally reducing ketone compound II with a mild reduction agent to form the intermediate hydroxy compound of Formula (III) and d: forming the mirtazapine of Formula (IV) by reduction of the ketone compound II or of the hydroxy compound III using a strong reduction agent.