A heterocycle is an organic compound whose carbon ring contains one or more heteroatoms ($ O $, $ S $, $ N $ ...)
Nicotine
The body of the name refers to (in order of precedence!) the heteroatoms:
The suffix denotes the ring size:
Oxetane
Thiepine
The order $ O \gt S \gt N $ is for the body of the name and the numbering!
1,2,4-Triazine
1,2,4-Oxathiazinane
If the cycle contains the maximum possible double bonds (completely unsaturated), hydrogen attached to an atom bound by two single bonds should be indicated with the prefix H
1- H -azirine
2- H -azirine
If the cycle does not contain the maximum possible double bonds, the hydrogen atoms attached to two ring atoms bound by single bonds are indicated by the prefixes dihydro , trihydro ... The rest of the name is the name of the cycle with the maximum possible double bonds.
2,3-Dihydroazete
2,3,4-Trihydrothiine
In the case of simple molecules the traditional names are preferred:
See → here:
→ Bicyclic compounds → Bicycloalkanes: exercises → Spiranes: exercises → Current heterocycles → Current nitrogen heterocycles → Common oxygenated and sulphurized heterocycles → Systematic nomenclature (Hantzsch-Widman) of simple heterocycles → Systematic nomenclature (Hantzsch-Widman) of condensed heterocycles → Nomenclature of substituted simple heterocycles → Nomenclature of substituted condensed heterocycles