Studies on the stability of Δ2 and Δ3 cephem esters. II. Comparative stability studies of Δ2 and Δ3 cephems at various pHs and the degradation process of Δ2 cephem esters

Article abstract of DOI:10.1248/cpb.43.1866

The instability of Δ² cephem prodrug-type ester (5a) under acidic conditions prompted us to investigate the comparative stability of Δ³ and δ² cephems at various pHs. The Δ² cephem ester 5a was found to show marked instability under neutral (pH 7) and acidic conditions (1 M HCl) compared with the Δ³ cephem ester (4a). A comparative study between Δ³ (4c) and Δ² cephem acid (5c) at pH 7 and in 1 M HCl solution showed that the Δ² acid 5c was as stable as the Δ³ acid 4c at pH 7, while 5c was less stable than 4c in 1 M HCl. Isolation of the degraded compounds demonstrated that the C-4 ester moiety was hydrolyzed in the initial stage to afford 5c, which was further degraded to more polar substances. This instability was observed in other types of Δ² cephem esters (5d-f). Here we report comparative stability studies and elucidation of the degradation products.

Full text of DOI:10.1248/cpb.43.1866

NII-Electronic Library Service

NII-Electronic Library Service

NII-Electronic Library Service

NII-Electronic Library Service

NII-Electronic Library Service

NII-Electronic Library Service