Processes for the preparation of cephem derivatives

Abstract

Provided is a process for preparing a compound of formula 1 or its salt, which includes reacting a compound of formula 2 with a compound of formula 3 in the presence of a base.

1 . A process for stereospecifically preparing a compound represented by the following formula 3a, which comprises a compound represented by the following formula 5 with acetaldehyde in a mixed solvent comprising water, isopropanol, and methylenechloride in a volume ratio of 1:3-6:11-14 in the presence of a base: 
     
       
         
         
             
             
         
       
       wherein R 3  is a hydrogen or a carboxyl protecting group, and R 5  is a hydrogen or an amino protecting group. 
     
   
   
       2 . The process of  claim 1 , wherein in the mixed solvent, water, isopropanol, and methylenechloride have a volume ratio of 1:4:12.