Method for synthesizing mirtazapine

The invention discloses a method for synthesizing mirtazapine. According to the method, 2-halogenated nicotinonitrile is used as an initial compound, and 2-chloronicotinamide, 2-(4-methyl-2phenyl-1-piperazinyl)nicotinamide, 2-(4-methyl-2phenyl-1-piperazinyl)nicotinic acid, 1-(3-hydroxymethylpyridyl-2-)-4-methyl-2-phenylpiperazine and other intermediate products are sequentially synthesized to prepare the mirtazapine. Against the defects in a current mirtazapine synthesizing method, the process is improved, a new synthesizing route is designed, and a preparation method which is economical and is easy for practical operation is provided to mirtazapine synthesis. The method is suitable for large-scale industrial production.