SEARCH Articles Figures Tables 5-Membered rings heteroatoms Five Heteroatoms Five-membered ring Five-membered rings heteroatoms Heteroatomic Rings More Than One Heteroatom in the Five-Membered Ring Of heterocycles: five-membered rings with one heteroatom Reactions with Five-Membered Ring Systems Containing One Heteroatom Reactivity of Five-membered Rings with One Heteroatom Structure of Five-membered Rings with One Heteroatom