title: Structural studies on penicillin derivatives. 8. A possible model biosynthetic route to penams and cephems.
mesh_terms: D002511:Cephalosporins; D055598:Chemical Phenomena; D002621:Chemistry; D003500:Cyclization; D006571:Heterocyclic Compounds; D008722:Methods; D008956:Models, Chemical; D010406:Penicillins
chemical_list: D002511:Cephalosporins; D006571:Heterocyclic Compounds; D010406:Penicillins