Are the known Δ²‐cephems inactive as antibiotics because of an unfavourable steric orientation of their 4α‐carboxylic group? Synthesis and biology of two Δ²‐cephem‐4β‐carboxylic acids

Abstract

Abstract Two representatives of the yet unknown type of Δ 2 ‐cephem‐4β‐carboxylic acids were prepared. Contrarily to the prediction based on the activity model of Cohen , both acids proved inactive as antibiotics. Possible reasons for this discrepancy are briefly discussed.