Azole

is a class of five-membered nitrogen heterocyclic ring compounds containing at least one other noncarbon atom, nitrogen, sulfur or oxygen. The parent compounds are aromatic and have two double bonds; there are successively reduced analogs (azolines and azolidines) with less. Names of azoles maintain the prefix upon reduction (such as pyrazoline, pyrazolidine), except for pyrrole, which has no -azole suffix and is reduced to pyrroline and pyrrolidine.