The invention relates to a method for synthesizing a
repaglinide key intermediate, namely 4-ethoxycarbonyl-3-ethyoxy
phenylacetic acid. The method comprises the following steps: by taking 3-ethyoxy-4-ethoxycarbonyl-
benzyl cyanide as an initial
raw material, performing
hydrolysis, esterification, selective
hydrolysis and the like, thereby obtaining the important intermediate 4-ethoxycarbonyl-3-ethyoxy
phenylacetic acid of
repaglinide. According to the key intermediate, the impurities of the product is less, the purity of the product is high and can reach over 99.7%, so that the quality of the subsequently synthesized
repaglinide product is improved, the 100 percent first-pass yield of the subsequently synthesized repaglinide product can be basically reached, a refining step is avoided, and the synthetic yield is effectively improved. The process is easy and convenient to operate, the yield is high, the
molar yield is 69.1 percent, the production cost is low, and the method is suitable for industrial production.