Preparation method of rivaroxaban intermediate

The invention discloses a preparation method of a rivaroxaban intermediate, (S)-2-((3-(4-morpholinophenyl)-2-oxazolidin-5-yl) methyl) isoindoline-1, 3-dione (II) is taken as a starting material, sodium chlorite is taken as an oxidizing agent, the rivaroxaban intermediate (I) is obtained through oxidation reaction, and the reaction route is shown in the specification. The preparation method specifically comprises the following steps: S1, carrying out addition reaction on a compound (II) and a compound (III) to obtain a corresponding amino alcohol compound, and carrying out cyclization reaction on the amino alcohol compound and a carbonylation reagent to obtain a compound (IV); s2, dissolving the compound (IV) in a polar aprotic solvent, and adding an oxidizing agent and an auxiliary reagent for reaction to obtain a reaction solution; and S3, concentrating, washing and drying the reaction liquid to obtain a crude product, and purifying the crude product through column chromatography or recrystallization to obta