Neue β-Lactam-Antibiotika. Über Derivate der 3-Hydroxy-7-amino-ceph-3-em-4-carbonsäure. Modifikationen von Antibiotika, 10. Mitteilung [1]

3-Hydroxy-ceph-3-em-esters 5 a – c , versatile intermediates for the preparation of new β-lactam antibiotics, were obtained by ozonolysis of the corresponding 3-methylidene-esters 3 a – c . Reduction and elimination gave the 3-unsubstituted ester 13 ; derivatives 16 a – c and 20 – 22 resulted from O-alkylation. The 3-methoxy-esters 16 a – c were converted into the corresponding acids 23 a – d . Several other transformations of the β-ketoester system are described.