Heterocyclic Compounds [Chemical/Ingredient] Heterocyclic Compounds, 2-Ring [Chemical/Ingredient] C26884 A class of organic compounds containing two ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic. Heterocyclic Compounds, 2-Ring D006574 5285 N0000008260 M0010293 C0019400 Heterocyclic Compounds, 2-Ring