Compounds of formula II
with R being hydrogen or an esterifying group; R1 being unsubstituted or substituted phenyl, naphthyl or thienyl; and Ra-Re being H or Cl-C4-alkyl are valuable intermediates for the production of penems which exhibit antibacterial activity.
式 II 中 R 为氢或酯化基;R1 为未取代或取代的苯基、
萘基或
噻吩基;Ra-Re 为 H 或 Cl-C4- 烷基的化合物是生产具有抗菌活性的青霉烯类化合物的重要中间体。