Full Title

Compounds containing elements of Groups 5 or 15 of the Periodic Table > Phosphorus compounds (sugar phosphates C07H11/04; nucleotides C07H19/00, C07H21/00; nucleic acids C07H21/00) > Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom > having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms > having phosphorus and oxygen atoms as the only ring hetero atoms