Heterocyclic compounds are widely distributed in nature, accounting for nearly one-third of known organic compounds, and are widely used. Many important substances, such as chlorophyll, heme, nucleic acids, and some natural and synthetic drugs with remarkable efficacy in clinical applications, contain structures of heterocyclic compounds. Alkaloids are the main active components of Chinese herbal medicine, and most of them are nitrogen-containing heterocyclic compounds.
“In cyclic organic compounds, the atoms that make up the ring are called heterocyclic compounds when there are other non-carbon atoms in addition to carbon atoms.” These non-carbon atoms are called heteroatoms. Common heteroatoms are nitrogen, oxygen, and sulfur.
According to the above definition, heterocyclic compounds appear to include lactone, lactide, and cyclic anhydride, etc., but are not included in heterocyclic compounds because they are similar in nature to the corresponding open-chain compounds and are prone to opening rings to become open-chain compounds. This paper focuses on heterocyclic compounds with relatively stable ring systems and varying degrees of aromaticity. The so-called aromatic heterocyclic compounds are heterocycles that retain aromatic structure, that is, 6π electron closed conjugate system. These compounds are relatively stable, not easy to open the ring, and their structure and reactivity are similar to benzene, that is, they have different degrees of aromaticity, so they are called aromatic heterocyclic compounds.
Heterocyclic compounds can be classified as single heterocycles or thick heterocycles according to their heterocyclic skeletons. Single heterocycles can be divided into five-membered heterocycles and six-membered heterocycles according to their size. The fused heterocycles can be divided into benzene-fused heterocycles and fused heterocycles according to their form of fused ring. As shown in the figure.
The nomenclature of heterocyclic compounds is mainly based on transliteration in foreign languages. The Chinese transliteration of the English name of the heterocyclic compound was added next to the character “kou”. For example:
Post time: Jul-05-2023