1.2 Cyclic Systems
53
This treatment is consistently applied only for heteromonocyclic systems with more than 10 ring members, for simple (not fused) bridged, and
for simple (not fused) spiro heterocycles. In the domain of smaller heterocyclic systems generally the Hantsch-Widman nomenclature system (see
next chapter) is used, even in the case of fully saturated compounds. It is
only for silicon containing compounds that Chern. Abstr. inexplicably uses
exclusively replacement names! If there are more than one hetero atoms
present, priority for numbering is first given to an atom of a higher group,
within the group of a lower row of the periodic table; only then are all the
other hetero elements assigned lowest locants as a set.
H2~i\
HN
NH
LsiH2
Silacyclopropene
Silacyclopentadiene
1,4-Diaza-2,5-disilacyclohexane
BH9-NC) I I
70-C~ 5
H N
H
7-0xa-l,5-diaza8-mercura-bicyclo
[4.2.0] octane
1,8-Dioxa-4,II-diazacyclotetradecane
thiatetracyclo14
15
s-s
HNUS>G NH
7,14,15-Trithia-3,II-diazadispiro [5.1.5.2] pentadecane
Spiro [cyclohexane-l,4' -[3,7]dioxabicyclo [4.1.0 ]heptane]
[ 6.3.0.04.11.0S.9]undecane
O Spiro[3-azabicyclo[3.1.0]hexane6, I' -cyclobutane]
H 6
4NeO
C ~~:0J
o gN
1
H2
1,6-Dioxa -4-aza-9-azonia-5-borataspiro [4.4]nonane