Preparation method of high-purity empagliflozin impurity

The invention relates to the field of medicinal chemistry, and discloses a preparation method of a high-purity empagliflozin impurity. (S)-3-(4-(5-iodine-2-chlorobenzyl) phenoxy) tetrahydrofuran is used as a raw material, firstly, compound carbon chain growth is performed through a Grignard reaction, then methyl is introduced, and a high-purity target substance compound I, namely the empagliflozin impurity, is finally obtained through purification means extraction, reduced pressure distillation, concentration and chromatography. 本发明涉及药物化学领域，公开了一种高纯度恩格列净杂质的制备方法。本发明以(S)-3-(4-(5-碘-2-氯苄基)苯氧基)四氢呋喃为原料，首先通过Grignard反应进行化合物碳链增长，然后引进甲基，其中配以纯化手段萃取、减压蒸馏、浓缩、层析，使最终得到高纯度的目标物质化合物Ⅰ，即所述恩格列净杂质。