Preparation method of antibiotic cephalosporin mother nucleus

The invention relates to the technical field of drug synthesis, and discloses a preparation method of an antibiotic cephalosporin mother nucleus, which comprises the following steps: by taking 7-phenylacetamide-3-hydroxy-3-cephem-4-carboxylic acid diphenyl methyl ester as a raw material, sequentially carrying out reduction reaction, sulfonyl esterification reaction and elimination reaction to obtain the antibiotic cephalosporin mother nucleus. The preparation method comprises the following steps: preparing 7-phenylacetamide-3-nor-3-cephem-4-carboxylic acid diphenyl methyl ester; the method comprises the following steps: by taking phenol as a deprotection agent, carrying out a benzhydrol protecting group removal reaction on 7-phenylacetamide-3-non-3-cephem-4-carboxylic acid diphenyl methyl ester, so as to prepare 7-phenylacetamide-3-non-3-cephem-4-carboxylic acid; according to the method, acylase is used as a deprotection agent, and a phenylacetyl protecting group removal reaction of 7-phenylacetamido-3-nor-3-