4-BENZYL-1-PHENETHYL-PIPERAZINE-2,6-DIONE PREPARATION METHOD, AND INTERMEDIATE AND PREPARATION METHOD THEREOF

The present invention provides a key new intermediate (a compound of formula III) of 4-benzyl-1-phenethyl-piperazine-2,6-dione (formula IV compound), a pharmaceutically acceptable salt thereof and a preparation method thereof. The present invention additionally discloses a method for preparing 4-benzyl-1-phenethyl-piperazine-2,6-dione (formula IV compound) from the formula III compound, said method overcoming the shortcomings of current formula IV compound preparation methods, such as low production volumes, low purity, high energy consumption, high costs, and inability to achieve industrialized production, and provides a formula IV compound preparation method which is simple, economical, environmentally-friendly and easy to produce industrially; the reaction solvent of the method is easily recycled and the method can produce the formula IV compound at high production rates and with high purity.