1.2 Cyclic Systems
57
1.2.2.4
Fused Heterocyclic Systems
Provided that no retained trivial name is applicable, fused heterocyclic
systems are given Hantzsch-Widman names. Fusion of components follows the same pattern as established for corresponding hydrocarbons
and an intricate series of seniority rules must be run through for selecting
the parent component. Traditional abbreviated terms are retained for
the following fusion components: furo, imidazo, (iso )quino, pyrimido,
thieno.
a) In determining the base component, any heterocyclic system takes
precedence over any carbocyclic entity, however large the latter
maybe.
~--3
Cyclopenta[7,8] phenanthro [2,3-b ]
azirine
2H-Naphtho[2,3-b]thiete
This rule is sometimes disregarded by Chern. Abstr. and the Ring Index for
oxygen -containing three-membered rings!
Correct: 8aH-Fluoreno [1 ,2-b] oxirene
C.A.: 1,2-Epoxy-8aH-fluorene
R.I.: 8aH-Oxireno[a]fluorene
Related thia derivatives are named as epithio ... compounds by both handbooks.
57
1.2.2.4
Fused Heterocyclic Systems
Provided that no retained trivial name is applicable, fused heterocyclic
systems are given Hantzsch-Widman names. Fusion of components follows the same pattern as established for corresponding hydrocarbons
and an intricate series of seniority rules must be run through for selecting
the parent component. Traditional abbreviated terms are retained for
the following fusion components: furo, imidazo, (iso )quino, pyrimido,
thieno.
a) In determining the base component, any heterocyclic system takes
precedence over any carbocyclic entity, however large the latter
maybe.
~--3
Cyclopenta[7,8] phenanthro [2,3-b ]
azirine
2H-Naphtho[2,3-b]thiete
This rule is sometimes disregarded by Chern. Abstr. and the Ring Index for
oxygen -containing three-membered rings!
Correct: 8aH-Fluoreno [1 ,2-b] oxirene
C.A.: 1,2-Epoxy-8aH-fluorene
R.I.: 8aH-Oxireno[a]fluorene
Related thia derivatives are named as epithio ... compounds by both handbooks.