SEARCH Articles Figures Tables 5-Membered rings heteroatoms Five Heteroatoms Five-Membered Ring Systems with Two or More Heteroatoms Five-Membered Rings with More Than Two Heteroatoms Five-membered ring Five-membered rings heteroatoms Heteroatomic Rings Of heterocycles: five-membered rings with two or more heteroatoms Reactivity of Five-membered Rings with Two or More Heteroatoms Structure of Five-membered Rings with Two or More Heteroatoms Synthesis of Five-Membered Rings with Two Heteroatoms