11. Heterocyclic compounds may be also present.12. The compound is classified as benzene derivative and a heterocyclic compound containing the methylenedioxy functional group. 13. The compound is used as a precursor to heterocyclic compounds by reaction with ketones and aldehydes. 14. He conducted studies on the condensation of aldehydes with ammonia as well as research of heterocyclic compounds . 15. "' Benzofuran "'is the heterocyclic compound consisting of fused benzene and furan rings. 16. Nucleotides are heterocyclic compounds , that is, they contain at least two different chemical elements as members of its rings. 17. "' Cinnoline "'is an aromatic heterocyclic compound with the formula C 8 H 6 N 2. 18. "' Isonipecotic acid "'is a heterocyclic compound which acts as a GABA A receptor partial agonist. 19. A "'thienodiazepine "'is a heterocyclic compound containing a diazepine ring fused to a thiophene ring. 20. "' Dihydrothiophene "'is a heterocyclic compound and an organosulfur compound with the formula SC 4 H 6.
