Preparation method for 1-benzyl-3-piperidone hydrochloride

The invention discloses a preparation method for N-benzyl glycine ethyl ester. The method comprises the following steps: dissolving benzylamine in an organic solvent I, then adding 2-halogenated ethyl acetate, alkali and quaternary ammonium salt, and performing reaction to obtain the N-benzyl glycine ethyl ester. The invention also discloses a preparation method for 1-benzyl-3-piperidone hydrochloride. The method comprises the following specific steps: (1) preparing an intermediate IV (N-benzyl glycine ethyl ester); (2) dissolving the intermediate IV in an organic solvent II, then adding 4-halogenated ethyl acetate and alkali, and performing reaction to obtain an intermediate III; (3) performing reaction between the intermediate III and the alkali, reversely regulating a pH value to 6-8, performing concentration under reduced pressure, extracting by using ethyl acetate, performing washing and drying, and then performing concentration under reduced pressure to obtain an intermediate II; (4) performing reaction on the intermediate II and acid, performing rotary evaporation concentration, and adding a crystal solvent for crystallization to obtain a product. The route synthesis steps are short, the process is novel, the intermediates are high in purity, the product yield is high, and the cost is low.