Prepn of cephalexin - from 7-amino (desoxy) cephalosporanic acid and a mixed anhydride then hydrogenation

摘要

Cephalexin is prepd. by treatment of 7-amino desoxycephalosporanic acid or 7-amino cephalosporanic acid with a mixed anhydride (IV): (where R = NO2- or N3-) followed by hydrogenation in the presence of catalyst. The first stage of the reaction is preferably carried out at -10 degrees C to ambient temp. and is effected in an inert solvent in the presence of just sufficient of a tert. base to neutralise the liberated acid. The preferred hydrogenation catalysts for the second stage are palladium (derivs.) and platinum derivs.