Method for preparing empagliflozin by one-pot method

The invention belongs to the technical field of medicine synthesis, and particularly relates to a method for preparing empagliflozin through a one-pot method. The preparation method comprises the following steps: taking 4-(5-bromo-2-chlorobenzyl) phenol as an initial raw material, and carrying out nucleophilic addition on the 4-(5-bromo-2-chlorobenzyl) phenol and sugar under the action of a Grignard reagent; adding a hydrogen chloride methanol solution to perform methylation; then, carrying out nucleophilic substitution reaction with (R)-3-p-toluenesulfonic acid tetrahydrofuran ester, and finally, adding Et3SiH/AlCl3 to carry out reduction reaction, so as to obtain an Engralicin crude product. According to the method for preparing the empagliflozin crude product through the one-pot method, an intermediate does not need to be taken out in the reaction process, centrifugation and drying operation is avoided, and the production period is greatly shortened. The preparation method is simple and convenient to opera