Process for producing optically active piperazine compound

Abstract

A process for producing optically active 1-methyl-3-phenylpiperazine, which is represented by the formula (11), or a salt thereof. It comprises the following steps (1) to (4) or comprises the following steps (5) to (7) and the step (4). Also provided is a process for producing optically active mirtazapine via that process.

Description

technical field The present invention relates to a novel optically active 1-methyl-3-phenylpiperazine and its salt, its production method and its intermediate, which are useful for the manufacture of optically active mirtazapine and other drugs, and also relate to Process for producing optically active 1-(3-hydroxymethyl-2-pyridyl)-4-methyl-2-phenylpiperazine and salts thereof, and intermediates thereof. Background technique Mirtazapine is a drug useful as an antidepressant. Recently, optically active mirtazapine is being developed as a drug for the treatment of insomnia, etc., and WO2005 / 005410 discloses -Phenylpiperazine is prepared by the production method. In WO2005 / 005410, although it is disclosed that 1-(3-hydroxymethyl-2-pyridyl)-4-methyl-2-phenylpiperazine can be synthesized by asymmetric synthesis, racemic chiral acid However, there is no disclosure about its specific manufacturing method. Known racemic 1-(3-hydroxymethyl-2-pyridyl)-4-methyl-2-phenylpiperazine...

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Problems solved by technology

On the other hand, the present inventors tried to produce optically active 1-(3-hydroxymethyl) from optically active 1-methyl-3-phenylpiperazine using the same method as those described in US4062848 and US6852855. -2-pyridyl)-4-methyl-2-phenylpiperazine, but it was found that its stereo configuration cannot be maintained and isomerization will occur

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