Method for synthesizing S-beflubutamid from (R)-2-sulfonyl butyric acid alkyl ester

The invention discloses a method for synthesizing S-beflubutamid from (R)-2-sulfonyl butyric acid alkyl ester, and belongs to the field of organic chemical synthesis. S-beflubutamid is prepared from a compound R-1; wherein the compound R-1 is obtained by treating a compound R-2 with a compound 1; wherein R1 is C1-C6 alkyl, and R is selected from C1-C6 alkyl, C1-C6 halogenated alkyl, phenyl or phenyl substituted by 1 to 3 independently selected from C1-C6 alkyl or halogen. (R)-2-hydroxybutyric acid produced through large-scale fermentation of microorganisms is used as a raw material, a compound R-2 is prepared through an esterification reaction and a sulfonylation reaction, a key chiral intermediate R-1 is obtained through a classical SN2 substitution reaction in which the intermediate 1 and the compound R-2 are subjected to configuration inversion, S-beflubutamid is prepared after R-1 preparation is completed, cost is low, pollution is small, safety is good, and the method is suitable for industrial productio