Process for the preparation of 7 alpha-alkoxycephem derivatives

摘要

There is provided a process for preparing a compound of the formula (I): <IMAGE> (I) wherein R1 is an organic residue, R2 is a hydrogen or a chlorine atom, a methoxy, ethoxy or an acetoxy group, and n represents 0, 1 or 2. The process comprises reacting a compound of the formula (II): <IMAGE> (II) wherein R2 and n are as defined above, with an inorganic or organic nitrite, in an alcohol R1OH, wherein R1 is as defined above, or in a mixture R1OH-organic solvent in the presence of an inorganic or organic acid. The compounds of the formula (I) are known intermediates in the synthesis of human leucocyte elastase inhibitors (HLE).