beta -Lactam hydroxycarboxylic acid esters, process for their preparation, and their use

摘要

beta -Lactam hydroxycarboxylic acid esters of the general formula (I) <IMAGE> in which R<1> - stands for hydrogen or - a hydroxy protective group, R<2> - stands for hydrogen or - for a hydroxyl protective group or - for C1-C6-alkyl or C2-C7-acyl, R<3> - stands for an amino protective group and R<4> - stands for hydrogen or - stands for C1-C6-alkyl in the form of their isomers, isomer mixtures, racemates or optical antipodes and their salts, their preparation and their use as intermediates for the preparation of carbapenem antibiotics.