Spiro compound

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Any chemical compound having one atom as the only common member of two rings

title: "Spiro compound" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["spiro-compounds"] description: "Any chemical compound having one atom as the only common member of two rings" topic_path: "general/spiro-compounds" source: "https://en.wikipedia.org/wiki/Spiro_compound" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Any chemical compound having one atom as the only common member of two rings ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/1/12/CSD_CIF_VOPHAJ.png" caption="pmid=11596945 }}"] ::

In organic chemistry, spiro compounds are compounds that have at least two molecular rings sharing one common atom. Simple spiro compounds are bicyclic (having just two rings). The presence of only one common atom connecting the two rings distinguishes spiro compounds from other bicyclics. Spiro compounds may be fully carbocyclic (all carbon) or heterocyclic (having one or more non-carbon atom). One common type of spiro compound encountered in educational settings is a heterocyclic one— the acetal formed by reaction of a diol with a cyclic ketone.

The common atom that connects the two (or sometimes three) rings is called the spiro atom. The two rings sharing the spiro atom are most often different, although they can be identical [e.g., spiro[5.5]undecane and spiropentadiene, at right].

Selected spiro compounds

Elatol.png | Elatol, isolated from Laurencia dendroidea (red algae) Spironolacton.svg | Spironolactone, a commercial diuretic medication Spiro-C5H4.png | Spiropentadiene, which is highly strained. Spiroverbindung Nomenklatur.svg | (A) 1-Bromo-3-chlorospiro[4.5]decan-7-ol, and (B) '1-bromo-3-chlorospiro[3.6]decan-7-ol.

Carbocyclic spiro compounds

Bicyclic ring structures in organic chemistry that have two fully carbocyclic (all carbon) rings connected through a carbon atom are the usual focus of the topic of spirocycles. Simple parent spirocycles include spiropentane, spirohexane, etc. up to spiroundecane. Several exist as isomers. Lower members of the class are strained. The symmetric isomer of spiroundecane is not.

Some spirocyclic compounds occur as natural products.

Preparation

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/0f/FechtEster.svg" caption="Synthesis route to Fecht's ester, illustrating a dialkylation route to a [[spiroheptane]]."] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/1/18/SpiroC11.svg" caption="pages=2094–2097 }}"] ::

The spirocyclic core is usually prepared by dialkylation of an activated carbon center. The dialkylating group is often a 1,3-, 1,4-, etc. dihalide. In some cases the dialkylating group is a dilithio reagent, such as 1,5-dilithiopentane.{{cite journal |doi=10.15227/orgsyn.070.0204 |title=Spiroannelation Via Organobis(Cuprates): 9,9-Dimethylspiro[4.5]Decan-7-One |journal=Organic Syntheses |date=1992 |volume=70 |page=204| first1=Paul A. |last1=Wender |first2=Alan W. |last2=White |first3=Frank E. |last3=McDonald

Spiro compounds are often prepared by diverse rearrangement reactions. For example, the pinacol-pinacolone rearrangement is illustrated below.]. ::figure[src="https://upload.wikimedia.org/wikipedia/commons/7/7d/The_synthesis_of_a_spiro-keto_compound_form_a_symmetrical_diol.png" caption="The synthesis of a spiro-keto compound form a symmetrical diol"] ::

Heterocyclic spiro compounds

::figure[src="https://upload.wikimedia.org/wikipedia/commons/6/69/Ketal_Synthesis_V.1.svg" caption="access-date=3 February 2016}}"] ::

Spiro compounds are considered heterocyclic if the spiro atom or any atom in either ring are not carbon atoms. Cases with a spiro heteroatom such as boron, silicon, and nitrogen (but also other Group IVA [14] are often trivial to prepare. Many borate esters derived from glycols illustrate this case. Likewise, a tetravalent neutral silicon and quaternary nitrogen atom (ammonium cation) can be the spiro center. Many such compounds have been described.

Particularly common spiro compounds are ketal (acetal) formed by condensation of cyclic ketones and diols and dithiols. A simple case is the acetal 1,4-dioxaspiro[4.5]decane from cyclohexanone and glycol. Cases of such ketals and dithioketals are common.

Chirality

::figure[src="https://upload.wikimedia.org/wikipedia/commons/4/49/Spiroverbindung_Chiralität.svg" caption="Two enantiomers of a spiro diketone."] ::

Spiranes can be chiral, in various ways. First, while nevertheless appearing to be twisted, they yet may have a chiral center making them analogous to any simple chiral compound, and second, while again appearing twisted, the specific location of substituents, as with alkylidenecycloalkanes, may make a spiro compound display central chirality (rather than axial chirality resulting from the twist); third, the substituents of the rings of the spiro compound may be such that the only reason they are chiral arises solely from the twist of their rings, e.g., in the simplest bicyclic case, where two structurally identical rings are attached via their spiro atom, resulting in a twisted presentation of the two rings. Hence, in the third case, the lack of planarity described above gives rise to what is termed axial chirality in otherwise identical isomeric pair of spiro compounds, because they differ only in the right- versus left-handed "twist" of structurally identical rings (as seen in allenes, sterically hindered biaryls, and alkylidenecycloalkanes as well). Assignment of absolute configuration of spiro compounds has been challenging, but a number of each type have been unequivocally assigned.

Some spiro compounds exhibit axial chirality. Spiroatoms can be the origin of chirality even when they lack the required four different substituents normally observed in chirality. When two rings are identical the priority is determined by a slight modification of the CIP system assigning a higher priority to one ring extension and a lower priority to an extension in the other ring. When rings are dissimilar the regular rules apply.

Nomenclature and etymology

Nomenclature for spiro compounds was first discussed by Adolf von Baeyer in 1900. IUPAC provides advice on naming of spiro compounds.

The prefix spiro denotes two rings with a spiro junction. The main method of systematic nomenclature is to follow with square brackets containing the number of atoms in the smaller ring then the number of atoms in the larger ring, separated by a period, in each case excluding the spiroatom (the atom by which the two rings are bonded) itself. Position-numbering starts with an atom of the smaller ring adjacent to the spiroatom around the atoms of that ring, then the spiroatom itself, then around the atoms of the larger ring. For example, compound A in Image #4 above (Selected Spiro Compounds) is called 1-bromo-3-chlorospiro[4.5]decan-7-ol, and compound B is called 1-bromo-3-chlorospiro[3.6]decan-7-ol.

References

References

  1. (2001). "Spirocyclopropanated Bicyclopropylidenes: Straightforward Preparation, Physical Properties, and Chemical Transformations". Chemistry - A European Journal.
  2. Moss, G.P.. (18 October 2002). "Extension and Revision of the Nomenclature for Spiro Compounds". Queen Mary University of London.
  3. (2012). "Organic Chemistry". Oxford University Press.
  4. Reusch, William. (1999). "Virtual Text of Organic Chemistry". Michigan State University, Department of Chemistry.
  5. (1994). "Stereochemistry of Organic Compounds". Wiley & Sons.
  6. (2015). "Total Syntheses of Natural Products Containing Spirocarbocycles". Org. Biomol. Chem..
  7. (13 July 1991). "Elusive bowtie pinned down".
  8. (1960). "Syntheses of Four Spiro Hydrocarbons". The Journal of Organic Chemistry.
  9. (2003). "Synthesis and [3+2] Cycloaddition of a 2,2-Dialkoxy-1-methylenecyclopropane: 6,6-Dimethyl-1-methylene-4,8-Dioxaspiro[2.5]octane and cis-5-(5,5-Dimethyl-1,3-dioxan-2-ylidene)hexahydro-1(2H)-pentalen-2-one". Organic Syntheses.
  10. (2024). "Preparation of a Radical Clocks Bearing Carbonyl Groups: Synthesis of N-Methoxy-N-methylspiro[cyclopropane-1,9'-fluorene]-2-carboxamide". Organic Syntheses.
  11. Pubchem. "1,1'-Bicyclopentyl-1,1'-diol". nih.gov.
  12. "1,4-Dioxaspiro[4.5]decane". chemspider.com.
  13. Viatcheslav Stepanenko, Kun Huang, Margarita Ortiz-Marciales. (2010). "Synthesis of Spiroborate Esters from 1,2-Aminoalcohols, Ethylene Glycol and Triisopropyl Borate: Preparation of (S)-1-(1,3,2-Dioxaborolan-2-Yloxy)-3-Methyl-1,1-Diphenylbutan-2-Amine". Organic Syntheses.
  14. (2016). "Preparation of 1,5-Dioxaspiro[5.5]undecan-3-one". Organic Syntheses.
  15. (1993). "Stereocontrolled Preparation of 3-Acyltetrahydrofurans from Acid-Promoted Rearrangements of Allylic Ketals: (2S,3S)-3-Acetyl-8-Carboethoxy-2,3-Dimethyl-1-Oxa-8-Azaspiro[4.5]Decane". Organic Syntheses.
  16. (1986). "Dichlorovinylation of an Enolate: 8-Ethynyl-8-Methyl-1,4-Dioxaspiro[4.5]Dec-6-Ene". Organic Syntheses.
  17. Rios, Ramon. (2012). "Enantioselective Methodologies for the Synthesis of Spiro Compounds". [[Chemical Society Reviews]].
  18. von Baeyer, Adolf. (1900). "Systematik und Nomenclatur Bicyclischer Kohlenwasserstoffe". Berichte der Deutschen Chemischen Gesellschaft.
  19. Moss, G.P.. (1999). "Extension and Revision of the Nomenclature for Spiro Compounds". Queen Mary University of London.
  20. "Spiro Hydrocarbons. Rule A-41. Compounds: Method 1".

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