Extension and Revision of the Nomenclature for Spiro Compounds
(IUPAC Recommendations 1999)

SP-1 Compounds with only Monocyclic Rings (Continued)

Continued from SP-1.5

Contents of Section

SP-1 Compounds with only monocyclic ring components (Continued)

SP-1.6 Three rings with one spiro atom
SP-1.7 Polyspiro systems with a spiro atom connected to three rings
SP-1.8 Choice of numbering

References for this section

SP-1.6 Ring systems composed of three monocyclic rings with only one spiro atom (i.e. a hexavalent spiro atom) are named by placing the prefix spiro- before the von Baeyer descriptor followed by the name corresponding to the hydrocarbon with the total number of skeletal atoms present in the ring system. Heteroatoms are indicated by replacement terms (SP-1.3) and non-standard valency by the lambda symbol (ref 11) (see SP-7 for further details). The locant of the spiro atom is used as a superscript number to the corresponding number of the von Baeyer descriptor to indicate each time the spiro atom is revisited (ref 9).

Example:


1,4,6,9,10,13-hexaoxa-5λ6-thiaspiro[4.45.45]tridecane

SP-1.6.1 If there is a choice a smaller ring is numbered before a larger ring.

Example:


3λ6-thiaspiro[2.43.53]dodecane

SP-1.7 Polyspiro systems which include three rings with a single spiro atom and are composed of only monocyclic rings are named using a combination of sections SP-1.4, SP-1.5 and SP-1.6. If there is a choice of numbering the following criteria are considered in order.

SP-1.7.1 Low numbers are selected for spiro atoms.

Example:


7λ6-thiatrispiro[2.0.2.27.37.24.33]heptadecane

SP-1.7.2 Low numbers are selected for spiro atoms connecting three rings.

Examples:


3λ6-thiatrispiro[2.2.26.2.211.23.23]heptadecane
not 11λ6-thiatrispiro[2.2.26.2.211.21.23]heptadecane (3 is lower than 11)
nor 3λ6-thiatrispiro[2.23.2.28.2.213.23]heptadecane (3,6,11 is lower than 3,8,13, see SP-1.7.1)


3λ6-thiadispiro[2.4.28.43.33]heptadecane error details
not 8λ6-thiadispiro[2.4.28.38.43]heptadecane (3 is lower than 8)
nor 3λ6-thiadispiro[2.33.4.211.43]heptadecane (3,8 is lower than 3,11, see SP-1.7.1)

SP-1.7.3 Low numbers are selected for the von Baeyer descriptor in the order of citation.

Example:


5λ6-thiatrispiro[2.1.1.27.15.25.23]tetradecane
not 5λ6-thiatrispiro[2.1.1.27.25.25.13]tetradecane
(2.1.1.27.15.25.23 is lower than 2.1.1.27.25.25.13)

SP-1.8 If there is a choice of names or numbering due to heteroatoms, functional groups or substituents the following criteria are considered in order until a decision is made:

SP-1.8.1 Low locants are allocated for heteroatoms indicated by replacement terms as a set.

Examples:


1-oxaspiro[4.5]decane
not 4-oxaspiro[4.5]decane


9-oxa-6-azaspiro[4.5]decane
not 7-oxa-10-azaspiro[4.5]decane (6,9 is lower than 7,10)

SP-1.8.2 Low locants are allocated for heteroatoms in the order of B-1.1 (ref 5), RB-1.4 (ref 12), R-2.3.3.1 and R-9.3 (ref 6).

Example:


6-oxa-10-azaspiro[4.5]decane
not 10-oxa-6-azaspiro[4.5]decane (6-oxa is lower than 10-oxa)

SP-1.8.3 Low locants are allocated for non-standard valency indicated by the λ symbol (ref 11), if necessary in order of decreasing numerical value of the bonding number, i.e. the lower number is assigned to λ5 rather than λ3. (See also SP-7.)

Example:


6λ5,10-diphosphaspiro[4.5]decane

SP-1.8.4 Low locants are allocated for radical positions, or, if the ring system is a substituent, its point of attachment.

Examples:


spiro[4.5]decan-2-yl
not spiro[4.5]decan-3-yl


3,9-diazaspiro[5.5]undecan-9-ium-3-yl
not 3,9-diazaspiro[5.5]undecan-3-ium-9-yl


However 1-oxaspiro[4.4]nonan-7-yl
not 6-oxaspiro[4.4]nonan-2-yl (see SP-1.8.1)

SP-1.8.5 Low locants are allocated for cationic sites. (See SP-8 for compounds with ionic spiro atoms.)

Example:


6,6-dimethyl-6,10-diazaspiro[4.5]decan-6-ium (preferred name)
Alternative name 6,6-dimethyl-10-aza-6-azoniaspiro[4.5]decane
not 10,10-dimethyl-6,10-diazaspiro[4.5]decan-10-ium (6-ium is lower than 10-ium)

SP-1.8.6 Low locants are allocated for the principal functional group.

Example:


spiro[5.5]undecan-3-one
not spiro[5.5]undecan-9-one (3 is lower than 9)

SP-1.8.7 Low locants are allocated for double bonds.

Examples:


spiro[4.5]deca-1,6-diene
not spiro[4.5]deca-1,9-diene (1,6 is lower than 1,9)


However spiro[4.5]deca-1,9-dien-6-one
not spiro[4.5]deca-1,6-dien-10-one (6-one is lower than 10-one, SP-1.8.6)

SP-1.8.8 Low locants are allocated for substituents cited as prefixes regardless of kind.

Example:


1,1,8,8,12,12-hexamethyldispiro[4.1.4.2]tridecane
not 1,1,8,8,13,13-hexamethyldispiro[4.1.4.2]tridecane

SP-1.8.9 Low locants are allocated for substituents cited as prefixes in the order of citation.

Example:


6,6-diethyl-9,9-dimethyl-1-oxaspiro[4.4]nonane

SP-1.8.10 Low locants are allocated for chirality centres that have the configuration R. (See also SP-9.)

Example:


(5R,7S)-1,8-dioxadispiro[4.1.4.2]tridecane
not (5S,7R)-1,8-dioxadispiro[4.1.4.2]tridecane (5R is lower than 5S)

References for this Section

5. IUPAC, Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F and H, 1979 edition, Pergamon Press, Oxford, 1979.

6. IUPAC, A Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993, Blackwell Scientific Publications, Oxford, 1993.

9. Based on a proposal by Andrey Yerin, ACD, Moscow.

11. IUPAC, Treatment of variable valence in organic nomenclature (Lambda convention), recommendations 1983, Pure Appl. Chem. 56, 769-778 (1984).

12. IUPAC, Revision of the extended Hantzsch-Widman system of nomenclature for heteromonocycles (recommendations 1982), Pure Appl. Chem. 55, 409-416 (1983).

Continued with SP-2
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