Heterocyclic compounds containing in the condensed system at least one hetero ring

Official title: Heterocyclic compounds containing in the condensed system at least one hetero ring having nitrogen and oxygen atoms as the only ring hetero atoms (4-oxa-1-azabicyclo [3.2.0] heptanes, e.g. oxapenicillins C07D503/00; 5-oxa-1-azabicyclo [4.2.0] octanes, e.g. oxacephalosporins C07D505/00; analogues thereof having ring oxygen atoms in other position C07D507/00)

C07D498/00 (Heterocyclic compounds containing in the condensed system at least one hetero ring) appears on 5,791 US grants and 7,797 published applications in this corpus.