spiro compounds.pptx organic chemistry stiro

Spiro compounds

1. 1. Nomenclature of Spiro compounds Monospiro hydrocarbons with two monocyclic rings are numbered consecutively starting in the smaller ring at an atom next to the spiro atom, proceeding around the smaller ring back to the spiro atom and then round the second ring. Example: spiro[4.5] decane not spiro[5.4] decane

2. 2. Heteroatoms are indicated by replacement prefixes and unsaturation is indicated in the usual way by the endings ene , diene,  etc . 8-azaspiro[4.5]dec-2-ene Examples: spiro[4.4]nona-2,7-diene 3,9-diazaspiro[5.5]undecane 1-bromo-3-chlorospiro[3.6]decan-7-ol

3. 3. Unbranched polyspiro hydrocarbons composed of only monocyclic rings are named using dispiro -, trispiro -,  etc . indicating the total number of spiro atoms present and the name of the parent hydrocarbon corresponding to the total number of carbon atoms present. Between the prefix and hydrocarbon name there is placed the von Baeyer descriptor which indicates the number of carbon atoms linked to the spiro atom or linking spiro atoms. The numbers are cited in order starting with a terminal ring and proceeding to the other terminal ring and back to the first via the other linking units. The numbers are separated by full stops and placed in square brackets. The compound is numbered in the order in which the numbers of its von Baeyer descriptor are cited. For trispiro and higher spiro systems each time a spiro atom is reached for the second time its locant is cited as a superscript number to the corresponding number of linking atoms.  

4. Examples: dispiro [4.2.4.2]tetradecane trispiro [2.2.2.2 9 .2 6 .2 3 ]pentadecane Note:   In previous rules superscript numbers were not used but with the extension of this system to branched spiro systems where superscript numbers are essential it is clearer to use them for all polyspiro systems with three or more spiro atoms using a von Baeyer descriptor.

5. 4. If there is a choice of number the name that gives the lower locants for spiro atoms is selected. Example: dispiro [4.1.5.2]tetradecane not dispiro [5.1.4.2]tetradecane not dispiro [4.2.5.1]tetradecane not dispiro [5.2.4.1]tetradecane (5,7 is lower than 6,8 or 5,8 or 6,9)

6. 5. If there is still a choice of numbering the numbers of the von Baeyer descriptor are considered in the order of citation. The name is selected with lower numbers at the first point of difference. Example: trispiro [2.2.2.2 9 .2 6 .3 3 ]hexadecane not trispiro [2.2.2.2 9 .3 6 .2 3 ]hexadecane (2.2.2.2 9 . 2 6 .3 3  is lower than 2.2.2.2 9 . 3 6 .2 3 )

7. 6. Branched polyspiro hydrocarbons composed of only monocyclic rings are named using trispiro -, tetraspiro -,  etc . indicating the total number of spiro atoms present and the name of the parent hydrocarbon corresponding to the total number of carbon atoms present. Between the prefix and hydrocarbon name there is placed the von Baeyer descriptor which indicates the number of carbon atoms linked to the spiro atom or linking spiro atoms. The numbers are cited in order starting with a terminal ring and proceeding to the next terminal ring and so on to the first spiro atom. The numbers are separated by full stops and placed in square brackets. The compound is numbered in the order in which its von Baeyer descriptor is cited. Each time a spiro atom is reached for the second time its locant is cited as a superscript number to the corresponding number of linking atoms.

8. Examples: trispiro [2.2.2 6 .2.2 11 .2 3 ]pentadecane Note:  Without the superscript numbers this name would be the same as the name of the second example without superscript numbers.

9. 7.  If there is a choice of numbering the name which gives the lowest locants for spiro atoms is selected. Examples: trispiro [2.0.2 4 .1.2 8 .1 3 ]undecane not trispiro [2.1.2 5 .0.2 8 .1 3 ]undecane not trispiro [2.1.2 5 .1.2 9 .0 3 ]undecane  (3, 4 ,8 is lower than 3, 5 ,8 or 3, 5 ,9)

10. tetraspiro [2.2.2.2 9 .2.2 14 .2 6 .2 3 ] icosane not tetraspiro [2.2.2.2 9 .2 6 .2.2 16 .2 3 ] icosane nor tetraspiro [2.2.2 6 .2.2.2 14 .2 11 .2 3 ] icosane (3,6, 9 , 14  is lower than 3,6,9, 16  or 3,6, 11 ,14)

11. 8. If there is still a choice of numbering the numbers of the von Baeyer descriptor are considered in the order of citation. The name is select with lower numbers at the first point of difference. Example : pentaspiro [2.0.2 4 .1.1.2 10 .0.2 13 .1 8 .2 3 ]octadecane not pentaspiro [2.0.2 4 .1.1.2 10 .0.2 13 .2 8 .1sup>3]octadecane (2.0.2 4 .1.1.2 10 .0.2 13 . 1 8 .2 3  is lower than 2.0.2 4 .1.1.2 10 .0.2 13 . 2 8 .1<sup3< sup="">)</sup3<>

12. decaspiro [4.1.0.1.5 10 .2 8 .2.1.0.2.4 26 .2 23 .0.2.4 36 .2 33 .2 22 .1 20 .1 7 .3 5 ] nonatetracontane   name decaspiro [4.1.0(1.5).2)2.1.0(2.4).2)0.2.4).2.2.1.1.3] nonatetracontane Let’s wrap up by briefly covering “spiro” fused compounds. Since both “bridgehead” positions are on the same carbon, we won’t be able to use the same “ bicyclo ” nomenclature as before- but the process is very similar.  We simply substitute “spiro” for “ bicyclo ”, insert the two bridge lengths, and place the suffix as before. So, the molecule below is  spiro[5.4] decane . Included next door are two other examples of spiro compounds, spiro[4.3]octane and spiro[5.2]octane.

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