Preparation method of apremilast with high optical purity, obtained product and application thereof

The invention discloses a preparation method of apremilast which has the high optical purity and is shown in a formula I, an obtained product and application thereof. The preparation method of the apremilast comprises the steps that in a condensation reaction which takes a compound IV and a compound V as reaction raw materials and takes glacial acetic acid as a reaction menstruum, a catalyst selected from anhydrous magnesium sulfate or anhydrous sodium sulfate or anhydrous calcium chloride or anhydrous cupric sulfate or anhydrous molecular sieve or the like is used, so that the preparation method of the apremilast has the advantages of being efficient, high in yield and high in optical purity and is more suitable for industrial production; the apremilast product is high in optical purity and has a better curative effect by serving as a bulk pharmaceutical chemical to be prepared into drugs, and therefore treatment compliance of patients is improved. Please see the formula in the description.