Studies On Synthetic Technics Of 7-ADCA As An Intermediate Of Cephalosporin Antibiotics

7-Amino-3-Desacetoxy Cephalosporanic Acid (7-ADCA) is one of the three important parent nucleuses(6-APA,7-ACA,7-ADCA)in the industrial chain of β-lactam antibiotics. It can be used for manufacture of dozens of cephalosporin antibiotics. The synthesis of 7-ADCA through ring expansion rearrangement from cheap penicillin G is the most prevalent technic at present. However, there exist many problems in the production of 7-ADCA in our country, including low yield, poor quality and insufficient output. In this paper, penicillin G potassium was employed as the starting material. Oxidation with acetic hydroperoxide afforded penicillin G sulfoxide in above 85%(w) yield. N,N'-bistrimethylsilyl urea was taken as carboxyl protective agent, the ring expansion rearrangement proceeded effectively in presence of hydrobromic-pyridine. Thus 7-phenylacetamido desacetoxycephalosporanic acid was obtained in crude yield of about 90%(w) with three steps in one pot. The final product 7-ADCA was odtained through the side-chain hydrolysis of 7-phenylacetamido desacetoxycephalosporanic acid with the existence of immobilized penicillin G acylase. The total yield was up to 40%(w) on the basis of penicillin G potassium.