Preparation method of LCZ696 midbody

The invention relates to the technical field of drug midbody synthesis, and particularly discloses a preparation method of the LCZ696 midbody. The method takes N-[(1R)-2-[1, 1'-biphenyl]-4-radical-1-(iodomethyl) ethyl] tert-butyl carbamate as a raw material, and the raw material is reacted with dimethyl methylmalonate; through hydrolytic decarboxylation and chiral resolution, the (2R, 4S)-5-(biphenyl-4-radical)-4-[(t-butyloxycarboryl) amio]-2-methylpentanoic acid. The method is simple in synthetic mode and short in steps; the chiral amine and other low-price resolving agent can be used for replacing the chiral noble metal catalyst; the method is stable in activity, gentle in condition, and low in equipment requirement; moreover, the operation condition of the method is easy to control, and free from pollution, low in energy consumption, and small in risk; therefore, the method is applicable to the industrial production.