Preparation method of Roxadustat intermediate

The invention provides a preparation method of a Roxadustat intermediate, and particularly relates to a preparation method of a Roxadustat intermediate 4-hydroxy-1-methyl-7-phenoxy-3-isoquinoline carboxylate. The preparation method comprises the following steps: carrying out a halogenation reaction on 4-hydroxy-1-hydrogen-7-phenoxy-3-isoquinoline carboxylate and a halogenating agent in the presence of a solvent to prepare 4-hydroxy-1-chloro/bromo/iodine-7-phenoxy-3-isoquinoline carboxylate, and further carrying out a methylation reaction in the presence of a catalyst, an alkali and a solvent to prepare 4-hydroxy-1-methyl-7-phenoxy-3-isoquinoline carboxylate. The preparation method provided by the invention has the advantages of easily available raw materials, mature and controllable process route and high reaction yield so as to be beneficial to industrial production of bulk drugs. 本发明提供了罗沙司他(Roxadustat)中间体的制备方法。具体地说，本发明提供了罗沙司他中间体4-羟基-1-甲基-7-苯氧基-3-异喹啉羧酸酯的制备方法，其包括在溶剂存在下，将4-羟基-1-氢-7-苯氧基-3-异喹啉羧酸酯与卤化剂进行卤化反应，制备得到4