the condensed system containing two rings with oxygen as ring hetero atom and one ring with nitrogen as ring hetero atom

Full Title

Heterocyclic compounds containing in the condensed ring system both one or more rings having oxygen atoms as the only ring hetero atoms and one or more rings having nitrogen atoms as the only ring hetero atoms, not provided for by groups C07D451/00 - C07D459/00, C07D463/00, C07D477/00 or C07D489/00 > in which the condensed system contains three hetero rings > Ortho-condensed systems > the condensed system containing two rings with oxygen as ring hetero atom and one ring with nitrogen as ring hetero atom