Teneligliptin key intermediate preparation method

The present invention discloses a preparation method of a teneligliptin key intermediate 1-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazine (compound I), and belongs to the technical field of medicine preparation. According to the method of the present invention, a compound IV is adopted as a raw material, and reacts with iodobenzene to obtain a compound III, the compound III reacts with N-Boc-piperazine to obtain a compound II, and the compound II reacts with a suitable acid to remove the Boc protection to obtain the compound I.