C07D 519/06

Heterocyclic compounds containing more than one system of two or more relevant hetero rings condensed among themselves or condensed with a common carbocyclic ring system not provided for in groups [CPC: C07D453/00] or [CPC: C07D455/00] containing at least one condensed beta-lactam ring system, provided for by groups [CPC: C07D463/00], [CPC: C07D477/00] or [CPC: C07D499/00] - [CPC: C07D507/00], e.g. a penem or a cepham system