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[[File:Heterocycle compounds.jpg|thumb|right|280px|Structures and names of common heterocyclic compounds]]
A '''heterocyclic compound''' or '''ring structure''' is a [[cyclic compound]] that has atoms of at least two different [[chemical element|elements]] as members of its ring(s).<ref>[[IUPAC Gold Book]] [http://goldbook.iupac.org/H02798.html ''heterocyclic compounds'']</ref> '''Heterocyclic chemistry''' is the branch of [[organic chemistry]] dealing with the synthesis, properties, and applications of these '''heterocycles'''.<ref name=Gilchrist/>
[[Image:Pyridine.svg|thumb|right|125px|[[Pyridine]], a heterocyclic compound]]


A '''heterocyclic compound''' or '''ring structure''' is a [[cyclic compound]] that has atoms of at least two different [[chemical element|elements]] as members of its ring(s).<ref>[[IUPAC Gold Book]] [http://goldbook.iupac.org/H02798.html ''heterocyclic compounds'']</ref> '''Heterocyclic organic chemistry''' is the branch of [[organic chemistry]] dealing with the synthesis, properties, and applications of '''organic heterocycles'''.<ref name=Gilchrist/>
Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass (cellulose and related materials), and many natural and synthetic dyes. More than half of known compounds are heterocycles.<ref name=Rees>{{cite journal |doi=10.1002/jhet.5570290306|title=Polysulfur-Nitrogen Heterocyclic Chemistry|year=1992|last1=Rees|first1=Charles W.|journal=Journal of Heterocyclic Chemistry|volume=29|issue=3|pages=639–651}}</ref> 59% of US FDA-approved drugs contain nitrogen heterocycles.<ref>{{cite journal|author=Edon Vitaku, David T. Smith, Jon T. Njardarson|title=Analysis of the Structural Diversity, Substitution Patterns, and Frequency of Nitrogen Heterocycles among U.S. FDA Approved Pharmaceuticals|journal=J. Med. Chem.|volume=57|year=2014|issue=24|pages=10257–10274|doi=10.1021/jm501100b|pmid=25255204}}</ref>

Examples of heterocyclic compounds include all of the [[nucleic acids]], the majority of drugs, most [[biomass]] ([[cellulose]] and related materials), and many natural and synthetic dyes. More than half of known compounds are heterocycles.<ref name=Rees>{{cite journal |doi=10.1002/jhet.5570290306|title=Polysulfur-Nitrogen Heterocyclic Chemistry|year=1992|last1=Rees|first1=Charles W.|journal=Journal of Heterocyclic Chemistry|volume=29|issue=3|pages=639–651}}</ref> 59% of US [[FDA]]-approved drugs contain [[nitrogen]] heterocycles.<ref>{{cite journal|author=Edon Vitaku, David T. Smith, Jon T. Njardarson|title=Analysis of the Structural Diversity, Substitution Patterns, and Frequency of Nitrogen Heterocycles among U.S. FDA Approved Pharmaceuticals|journal=J. Med. Chem.|volume=57|year=2014|issue=24|pages=10257–10274|doi=10.1021/jm501100b|pmid=25255204}}</ref>


== Classification ==
== Classification ==
The study of heterocyclic chemistry focuses especially on unsaturated derivatives, and the preponderance of work and applications involves unstrained 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and furan are quinoline, benzothiophene, indole, and benzofuran, respectively. The fusion of two benzene rings gives rise to a third large family of compounds. Analogs of the previously mentioned heterocycles for this third family of compounds are acridine, dibenzothiophene, carbazole, and dibenzofuran, respectively.
The study of organic heterocyclic chemistry focuses especially on organic unsaturated derivatives, and the preponderance of work and applications involves unstrained organic 5- and 6-membered rings. Included are [[pyridine]], [[thiophene]], [[pyrrole]], and [[furan]]. Another large class of organic heterocycles refers to those fused to [[benzene ring]]s. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and furan are [[quinoline]], [[benzothiophene]], [[indole]], and [[benzofuran]], respectively. The fusion of two benzene rings gives rise to a third large family of organic compounds. Analogs of the previously mentioned heterocycles for this third family of compounds are [[acridine]], [[dibenzothiophene]], [[carbazole]], and [[dibenzofuran]], respectively.


Heterocyclic compounds can be usefully classified based on their electronic structure. The saturated heterocycles behave like the acyclic derivatives. Thus, [[piperidine]] and [[tetrahydrofuran]] are conventional amines and ethers, with modified steric profiles. Therefore, the study of heterocyclic chemistry focuses on unsaturated rings.
Heterocyclic organic compounds can be usefully classified based on their electronic structure. The saturated organic heterocycles behave like the acyclic derivatives. Thus, [[piperidine]] and [[tetrahydrofuran]] are conventional [[amines]] and [[ethers]], with modified steric profiles. Therefore, the study of organic heterocyclic chemistry focuses on organic unsaturated rings.


===Inorganic rings===
===Inorganic rings===
Some heterocycles contain no carbon. Examples are [[borazine]] (B<sub>3</sub>N<sub>3</sub> ring), [[hexachlorophosphazene]]s (P<sub>3</sub>N<sub>3</sub> rings), and S<sub>4</sub>N<sub>4</sub>. In comparison with organic heterocycles, which have numerous commercial applications, inorganic ring systems are mainly of theoretical interest. [[International Union of Pure and Applied Chemistry|IUPAC]] recommends the [[Hantzsch-Widman nomenclature]] for naming heterocyclic compounds.<ref>{{GoldBookRef|title=Hantzsch–Widman name|file=H02737}}</ref>
Some heterocycles contain no carbon. Examples are [[borazine]] (B<sub>3</sub>N<sub>3</sub> ring), [[hexachlorophosphazene]]s (P<sub>3</sub>N<sub>3</sub> rings), and [[tetrasulfur tetranitride]] S<sub>4</sub>N<sub>4</sub>. In comparison with organic heterocycles, which have numerous commercial applications, inorganic ring systems are mainly of theoretical interest. [[International Union of Pure and Applied Chemistry|IUPAC]] recommends the [[Hantzsch-Widman nomenclature]] for naming heterocyclic compounds.<ref>{{GoldBookRef|title=Hantzsch–Widman name|file=H02737}}</ref>


==Notes on lists==
==Notes on lists==
* "Heteroatoms" are atoms in the ring other than carbon atoms.
* "Heteroatoms" are atoms in the ring other than [[carbon]] atoms.
* Names in italics are retained by [[IUPAC]] and do not follow the [[Hantzsch-Widman nomenclature]]
* Some of the names refer to classes of compounds rather than individual compounds.
* Some of the names refer to classes of compounds rather than individual compounds.
* Also no attempt is made to list isomers.
* Also no attempt is made to list [[isomers]].


== 3-membered rings ==
== 3-membered rings ==
Although subject to [[ring strain]], 3-membered heterocyclic rings are well characterized.<ref>{{March6th}}</ref>
Although subject to [[ring strain]], 3-membered heterocyclic rings are well characterized.<ref>{{March6th}}</ref>


{{div col begin}}
===Three-membered rings with one heteroatom===
{| class="wikitable"
{| class="wikitable"
|+ Three-membered rings; ''one'' heteroatom
!Heteroatom
!Heteroatom
!Saturated
!Saturated
Line 31: Line 36:
| Boron
| Boron
| [[Borirane]]
| [[Borirane]]
| [[Borirene]]
| Borirene
|-
|-
| Nitrogen
| Nitrogen
Line 43: Line 48:
| Phosphorus
| Phosphorus
| [[Phosphirane]]
| [[Phosphirane]]
| [[Phosphirene]]
| That Why
|-
|-
| Sulfur
| Sulfur
Line 49: Line 54:
| [[Thiirene]]
| [[Thiirene]]
|}
|}

===Three-membered rings with two heteroatoms===


{| class="wikitable"
{| class="wikitable"
|+ Three-membered rings; ''two'' heteroatoms
!Heteroatoms
!Heteroatoms
!Saturated
!Saturated
Line 63: Line 67:
| Nitrogen + oxygen
| Nitrogen + oxygen
| [[Oxaziridine]]
| [[Oxaziridine]]
| Oxazirine
|
|-
|-
| 2× Oxygen
| 2× Oxygen
Line 69: Line 73:
|
|
|}
|}
{{div col end}}


== 4-membered rings ==
== 4-membered rings ==
{{div col begin}}
===Four-membered rings with ''one'' heteroatom===

{| class="wikitable"
{| class="wikitable"
|+Four-membered rings; ''one'' heteroatom
|-
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 95: Line 99:
| [[Thiete]]
| [[Thiete]]
|}
|}

===Four-membered rings with ''two'' heteroatoms===


{| class="wikitable"
{| class="wikitable"
|+Four-membered rings; ''two'' heteroatoms
! Heteroatoms
! Heteroatoms
! Saturated
! Saturated
Line 115: Line 118:
| [[Dithiete]]
| [[Dithiete]]
|}
|}
{{div col end}}


== 5-membered rings ==
== 5-membered rings ==
The 5-membered ring compounds containing ''two'' heteroatoms, at least one of which is nitrogen, are collectively called the [[azoles]]. [[Thiazoles]] and [[isothiazoles]] contain a [[sulfur]] and a nitrogen atom in the ring. [[Dithiolanes]] have two sulfur atoms.
===Five-membered rings with ''one'' heteroatom===


A large group of 5-membered ring compounds with ''three'' or more heteroatoms also exists. One example is the class of [[dithiazole]]s, which contain two sulfur atoms and one nitrogen atom.

{{div col begin}}
{| class="wikitable"
{| class="wikitable"
|+ Five-membered rings; ''one'' heteroatom
|-
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 142: Line 149:
|-
|-
! [[Nitrogen]]
! [[Nitrogen]]
| ''[[Pyrrolidine]]'' ("Azolidine" is not used)
| ''[[Pyrrolidine]]'' ("Azolidine" not used)
| ''[[Pyrrole]]'' ("Azole" is not used)
| ''[[Pyrrole]]'' ("Azole" not used)
|-
|-
! [[Oxygen]]
! [[Oxygen]]
Line 173: Line 180:
| [[Stannole]]
| [[Stannole]]
|}
|}

===Five-membered rings with ''two'' heteroatoms===
The 5-membered ring compounds containing ''two'' heteroatoms, at least one of which is nitrogen, are collectively called the [[azoles]]. [[Thiazoles]] and [[isothiazoles]] contain a sulfur and a nitrogen atom in the ring. [[Dithiolanes]] have two sulfur atoms.


{| class="wikitable"
{| class="wikitable"
|+ Five-membered rings; ''two'' heteroatoms
! Heteroatoms
! Heteroatoms
! Saturated
! Saturated
Line 187: Line 192:
|- valign=top
|- valign=top
! Oxygen + sulfur
! Oxygen + sulfur
| [[Oxazolidine|Oxathiolidine]]<br>[[Isoxazolidine|Isoxthiolidine]]
| [[1,3-Oxathiolane]]<br>[[1,2-Oxathiolane]]
| [[Oxazole|Oxathiole]] ([[Oxazoline|Oxathioline]])<br>[[Isoxazole|Isoxathiole]]
| [[Oxathiole]] ([[Oxathioline]])<br>[[Isoxathiole]]
|- valign=top
|- valign=top
! Nitrogen + Oxygen
! Nitrogen + Oxygen
Line 204: Line 209:
! 2× sulfur
! 2× sulfur
| [[Dithiolane]]
| [[Dithiolane]]
| [[Dithiole]]
|}
|}

===Five-membered rings with at least ''three'' heteroatoms===
A large group of 5-membered ring compounds with ''three'' or more heteroatoms also exists. One example is the class of [[dithiazole]]s, which contain two sulfur atoms and one nitrogen atom.


{| class="wikitable"
{| class="wikitable"
|+ Five-membered rings; at least ''three'' heteroatoms
|-
! Heteroatoms
! Heteroatoms
! Saturated
! Saturated
Line 251: Line 254:
| [[Pentazole]]
| [[Pentazole]]
|}
|}
{{div col end}}


== 6-membered rings ==
== 6-membered rings ==
{{div col begin}}
===Six-membered rings with ''one'' heteroatom===

{| class="wikitable"
{| class="wikitable"
|+ Six-membered rings; ''one'' heteroatom
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 283: Line 287:
|-
|-
| Nitrogen
| Nitrogen
| ''[[Piperidine]]''<br>(Azinane is not used)
| ''[[Piperidine]]''<br>(Azinane not used)
| ''[[Pyridine]]''<br>([[Azine (heterocycle)|Azine]] is not used)
| ''[[Pyridine]]''<br>([[Azine (heterocycle)|Azine]] not used)
| [[Pyridinium]] cation
| [[Pyridinium]] cation
|-
|-
| Oxygen
| Oxygen
| [[Oxane]]
| [[Oxane]]
| ''[[Pyran]]''<br>(2''H''-[[Oxine]] is not used)
| ''[[Pyran]]''<br>(2''H''-[[Oxine]] not used)
| [[Pyrylium]] cation
| [[Pyrylium]] cation
|-
|-
Line 307: Line 311:
| Sulfur
| Sulfur
| [[Thiane]]
| [[Thiane]]
| ''[[Thiopyran]]''<br>(2''H''-Thiine is not used)
| ''[[Thiopyran]]''<br>(2''H''-Thiine not used)
| [[Thiopyrylium]] cation
| [[Thiopyrylium]] cation
|-
|-
Line 320: Line 324:
|}
|}


{| class="wikitable"
===Six-membered rings with ''two'' heteroatoms===
|+ Six-membered rings; ''two'' heteroatoms

{| class="wikitable" width=400px
|-
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 357: Line 359:
|}
|}


{| class="wikitable"
===Six-membered rings with ''three'' heteroatoms===
|+ Six-membered rings; ''three'' heteroatoms

{| class="wikitable" width=400px
|-
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 378: Line 378:
|}
|}


{| class="wikitable"
===Six-membered rings with ''four'' heteroatoms===
|+ Six-membered rings; ''four'' heteroatoms

{| class="wikitable" width=400px
|-
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 389: Line 387:
|
|
| [[Tetrazine]]
| [[Tetrazine]]
|-
| 2 nitrogen, 2 [[boron]] || || [[Carborazine]]
|}
|}


{| class="wikitable"
[[Carborazine]] is a six-membered ring with two nitrogen heteroatoms and two boron heteroatom.
|+ Six-membered rings; ''five'' heteroatoms

===Six-membered rings with five heteroatoms===

{| class="wikitable" width=400px
|-
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 405: Line 401:
| [[Pentazine]]
| [[Pentazine]]
|}
|}
{{div col end}}


===Six-membered rings with six heteroatoms===
===Six-membered rings with six heteroatoms===
The [[hypothetical chemical compound]] with six nitrogen heteroatoms would be [[hexazine]]. [[Borazine]] is a six-membered ring with three nitrogen heteroatoms and three boron heteroatoms.


The hypothetical compound with six nitrogen heteroatoms would be [[hexazine]].

[[Borazine]] is a six-membered ring with three nitrogen heteroatoms and three boron heteroatoms.


== 7-membered rings ==
== 7-membered rings ==
In a 7-membered ring, the heteroatom must be able to provide an empty π-orbital (e.g. boron) for "normal" aromatic stabilization to be available; otherwise, [[homoaromaticity]] may be possible. Compounds with one heteroatom include:


In a 7-membered ring, the heteroatom must be able to provide an empty π-orbital (e.g. boron) for "normal" aromatic stabilization to be available; otherwise, [[homoaromaticity]] may be possible.

{{div col begin}}
{| class="wikitable"
{| class="wikitable"
|+ Seven-membered rings; ''one'' heteroatom
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 436: Line 434:
| [[Thiepine]]
| [[Thiepine]]
|}
|}

Those with two heteroatoms include:


{| class="wikitable"
{| class="wikitable"
|+ Seven-membered rings; ''two'' heteroatoms
|-
! Heteroatom
! Heteroatom
! Saturated
! Saturated
Line 453: Line 449:
| [[Thiazepine]]
| [[Thiazepine]]
|}
|}
{{div col end}}

== 8-membered rings ==
== 8-membered rings ==
{{div col begin}}
{| class="wikitable"
{| class="wikitable"
|-
|-
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| [[Thiocane]]
| [[Thiocane]]
| [[Thiocine]]
| [[Thiocine]]
|-
| 4 nitrogen, 4 boron || || [[Borazocine]]
|}
|}
{{div col end}}

[[Borazocine]] is an eight-membered ring with four nitrogen heteroatoms and four boron heteroatoms.

== 9-membered rings ==
== 9-membered rings ==

{| class="wikitable"
{| class="wikitable"
|-
|-
Line 498: Line 496:


== Images of rings with one heteroatom==
== Images of rings with one heteroatom==
:''Names in italics are retained by [[IUPAC]] and they do not follow the [[Hantzsch-Widman nomenclature]]''
{| class="wikitable"
{| class="wikitable"
|-
|-
Line 505: Line 502:
! align="left" | Heteroatom !![[Nitrogen]] !![[Oxygen]] !![[Sulfur]] !!Nitrogen !!Oxygen !!Sulfur
! align="left" | Heteroatom !![[Nitrogen]] !![[Oxygen]] !![[Sulfur]] !!Nitrogen !!Oxygen !!Sulfur
|-
|-
! rowspan="2" | 3-Atom Ring
! rowspan="2" | 3-atom ring
| [[Aziridine]] || [[Oxirane]] || [[Thiirane]] || [[Azirine]] || [[Oxirene]] || [[Thiirene]]
| [[Aziridine]] || [[Oxirane]] || [[Thiirane]] || [[Azirine]] || [[Oxirene]] || [[Thiirene]]
|-
|-
| [[File:Aziridin.svg|60px|Structure of Aziridine]] || [[File:Ethylene-oxide-2D-skeletal.svg|60px|Structure of Oxirane]] || [[File:Thiiran.svg|60px|Structure of Thiirane]] || [[File:Azirin.svg|60px|Structure of Azirine]] || [[File:Oxiren.svg|60px|Structure of Oxirene]] || [[File:Thiiren.svg|60px|Structure of Thiirene]]
| [[File:Aziridin.svg|60px|Structure of aziridine]] || [[File:Ethylene oxide.svg|60px|Structure of oxirane]] || [[File:Thiiran.svg|60px|Structure of thiirane]] || [[File:Azirin.svg|60px|Structure of azirine]] || [[File:Oxiren.svg|60px|Structure of oxirene]] || [[File:Thiiren.svg|60px|Structure of thiirene]]
|-
|-
! rowspan="2" | 4-Atom Ring
! rowspan="2" | 4-atom ring
| [[Azetidine]] || [[Oxetane]] || [[Thietane]] || [[Azete]] || [[Oxete]]|| [[Thiete]]
| [[Azetidine]] || [[Oxetane]] || [[Thietane]] || [[Azete]] || [[Oxete]]|| [[Thiete]]
|-
|-


| [[File:Azetidine structure.svg|70px|Structure of Acetidine]] || [[File:Oxetan.png|60px|Structure of Oxetane]] || [[File:Thietan.png|60px|Structure of Thietane]] || [[File:Azete structure.svg|60px|Structure of Azete]] || [[File:Oxet.png|64px|Structure of Oxete]] || [[File:Thietene.png|74px|Structure of Thiete]]
| [[File:Azetidine structure.svg|70px|Structure of acetidine]] || [[File:Oxetan.png|60px|Structure of oxetane]] || [[File:Thietan.png|60px|Structure of thietane]] || [[File:Azete structure.svg|60px|Structure of azete]] || [[File:Oxetene.svg|64px|Structure of oxete]] || [[File:Thietene.png|74px|Structure of thiete]]
|-
|-
! rowspan="2" | 5-Atom Ring
! rowspan="2" | 5-atom ring
| ''[[Pyrrolidine]]'' || [[Oxolane]] || [[Thiolane]] || ''[[Pyrrole]]'' || ''[[Furan]]'' || ''[[Thiophene]]''
| ''[[Pyrrolidine]]'' || [[Oxolane]] || [[Thiolane]] || ''[[Pyrrole]]'' || ''[[Furan]]'' || ''[[Thiophene]]''
|- valign="top"
|- valign="top"


|| [[File:Pyrrolidine-Structural Formula V.1.svg|60px|Structure of Pyrrolidine]] || [[File:Tetrahydrofuran acsv.svg|70px|Structure of Oxolane]] || [[File:Tetrahydrothiophen.png|70px|Structure of Thiolane]]
|| [[File:Pyrrolidine-Structural Formula V.1.svg|60px|Structure of pyrrolidine]] || [[File:Tetrahydrofuran acsv.svg|70px|Structure of oxolane]] || [[File:Tetrahydrothiophen.png|70px|Structure of thiolane]]
|| [[File:Pyrrol2.svg|70px|Structure of Pyrrole]] || [[File:Furan.svg|70px|Structure of Furan]] || [[File:Thiophen.svg|70px|Structure of Thiophene]]
|| [[File:Pyrrol2.svg|70px|Structure of pyrrole]] || [[File:Furan.svg|70px|Structure of furan]] || [[File:Thiophen.svg|70px|Structure of thiophene]]
|-
|-
! rowspan="2" | 6-Atom Ring
! rowspan="2" | 6-atom ring
| ''[[Piperidine]]'' || [[Oxane]] || [[Thiane]] || ''[[Pyridine]]'' || ''[[Pyran]]'' || ''[[Thiopyran]]''
| ''[[Piperidine]]'' || [[Oxane]] || [[Thiane]] || ''[[Pyridine]]'' || ''[[Pyran]]'' || ''[[Thiopyran]]''
|- valign="top"
|- valign="top"


|| [[File:Piperidin.svg|70px|Structure of Piperidine]] || [[File:Tetrahydropyran (vzorec).svg|70px|Structure of Oxane]] || [[File:Thiane3.svg|70px|Structure of Thiane]]
|| [[File:Piperidin.svg|70px|Structure of piperidine]] || [[File:Tetrahydropyran (vzorec).svg|70px|Structure of oxane]] || [[File:Thiane3.svg|70px|Structure of thiane]]
|| [[File:Pyridin.svg|70px|Structure of Pyridine]] || [[File:2H-Pyran.svg|70px|Structure of Pyran]] || [[File:1,2-Thiapyran.svg|70px|Structure of Thiopyran]]
|| [[File:Pyridin.svg|70px|Structure of pyridine]] || [[File:2H-Pyran.svg|70px|Structure of pyran]] || [[File:1,2-Thiapyran.svg|70px|Structure of thiopyran]]
|-
|-
! rowspan="2" | 7-Atom Ring
! rowspan="2" | 7-atom ring
| [[Azepane]] || [[Oxepane]] || [[Thiepane]] || [[Azepine]] || [[Oxepine]] || [[Thiepine]]
| [[Azepane]] || [[Oxepane]] || [[Thiepane]] || [[Azepine]] || [[Oxepine]] || [[Thiepine]]
|- valign="bottom"
|- valign="bottom"


| [[File:Azepane.svg|70px|Structure of Azepane]] || [[File:Oxepan.png|70px|Structure of Oxepane]] || [[File:Thiepan.svg|70px|Structure of Thiepane]] || [[File:Azepine-2D-skeletal.png|70px|Structure of Azepine]] || [[File:Oxepine.svg|70px|Structure of Oxepine]] || [[File:Thiepin2.png|70px|Structure of Thiepine]]
| [[File:Azepane.svg|70px|Structure of azepane]] || [[File:Oxepan.png|70px|Structure of oxepane]] || [[File:Thiepan.svg|70px|Structure of thiepane]] || [[File:Azepine-2D-skeletal.png|70px|Structure of azepine]] || [[File:Oxepine.svg|70px|Structure of oxepine]] || [[File:Thiepine.png|70px|Structure of thiepine]]
|-
|-
! rowspan="2" | 8-Atom Ring
! rowspan="2" | 8-atom ring
| [[Azocane]] || [[Oxocane]] || [[Thiocane]] || [[Azocine]] || [[Oxocine]] || [[Thiocine]]
| [[Azocane]] || [[Oxocane]] || [[Thiocane]] || [[Azocine]] || [[Oxocine]] || [[Thiocine]]
|- valign="bottom"
|- valign="bottom"


| [[File:Azocane.png|70px|Structure of Azocane]] || [[File:Oxocano.png|70px|Structure of Oxocane]] || [[File:Tiocano.png|70px|Structure of Thiocane]] || [[File:Azocine.png|70px|Structure of Azocine]] || [[File:Oxocinio.png|70px|Structure of Oxocine]] || [[File:Tiocinio.png|70px|Structure of Thiocine]]
| [[File:Azocane.png|70px|Structure of azocane]] || [[File:Oxocano.png|70px|Structure of oxocane]] || [[File:Tiocano.png|70px|Structure of thiocane]] || [[File:Azocine.png|70px|Structure of azocine]] || [[File:Oxocinio.png|70px|Structure of oxocine]] || [[File:Tiocinio.png|70px|Structure of thiocine]]
|-
|-
! rowspan="2" | 9-Atom Ring
! rowspan="2" | 9-atom ring
| [[Azonane]] || [[Oxonane]] || [[Thionane]] || [[Azonine]] || [[Oxonine]] || [[(2Z,4Z,6Z,8Z)-Thionine|Thionine]]
| [[Azonane]] || [[Oxonane]] || [[Thionane]] || [[Azonine]] || [[Oxonine]] || [[(2Z,4Z,6Z,8Z)-Thionine|Thionine]]
|- valign="bottom"
|- valign="bottom"


| [[File:Azonano.png|66px|Structure of Azonane]] || [[File:Oxonano.png|70px|Structure of Oxonane]] || [[File:Tionano.png|70px|Structure of Thionane]] || [[File:Azonina.png|70px|Structure of Azonine]] || [[File:Oxonina.png|70px|Structure of Oxonine]] || [[File:Tionina.png|70px|Structure of Thionine]]
| [[File:Azonano.png|66px|Structure of azonane]] || [[File:Oxonano.png|70px|Structure of oxonane]] || [[File:Tionano.png|70px|Structure of thionane]] || [[File:Azonina.png|70px|Structure of azonine]] || [[File:Oxonina.png|70px|Structure of oxonine]] || [[File:Tionina.png|70px|Structure of thionine]]
|}
|}


Line 554: Line 551:


== History of heterocyclic chemistry ==
== History of heterocyclic chemistry ==
The history of heterocyclic chemistry began in the 1800s, in step with the development of [[organic chemistry]]. Some noteworthy developments:<ref>{{Cite journal |doi=10.1021/ed063p860|title=Adrien Albert and the rationalization of heterocyclic chemistry|journal=Journal of Chemical Education|volume=63|issue=10|pages=860|year=1986|last1=Campaigne|first1=E.|bibcode=1986JChEd..63..860C}}</ref><br />
The history of heterocyclic chemistry began in the 1800s, in step with the development of [[organic chemistry]]. Some noteworthy developments:<ref>{{Cite journal |doi=10.1021/ed063p860|title=Adrien Albert and the rationalization of heterocyclic chemistry|journal=Journal of Chemical Education|volume=63|issue=10|pages=860|year=1986|last1=Campaigne|first1=E.|bibcode=1986JChEd..63..860C}}</ref>
1818: Brugnatelli isolates [[alloxan]] from [[uric acid]]<br />
* 1818: Brugnatelli makes [[alloxan]] from [[uric acid]]
1832: Dobereiner produces [[furfural]] (a furan) by treating [[starch]] with [[sulfuric acid]]<br />
* 1832: Dobereiner produces [[furfural]] (a furan) by treating [[starch]] with [[sulfuric acid]]
1834: Runge obtains [[pyrrole]] ("fiery oil") by dry distillation of bones<br />
* 1834: Runge obtains [[pyrrole]] ("fiery oil") by dry distillation of bones
1906: Friedlander synthesizes [[indigo dye]], allowing synthetic chemistry to displace a large agricultural industry<br />
* 1906: Friedlander synthesizes [[indigo dye]], allowing synthetic chemistry to displace a large agricultural industry
1936: [[Alfred E. Treibs|Treibs]] isolates chlorophyl derivatives from crude oil, explaining the biological origin of petroleum.<br />
* 1936: [[Alfred E. Treibs|Treibs]] isolates chlorophyll derivatives from crude oil, explaining the biological origin of petroleum.
1951: [[Chargaff's rules]] are described, highlighting the role of heterocyclic compounds ([[purine]]s and [[pyrimidine]]s) in the genetic code.
* 1951: [[Chargaff's rules]] are described, highlighting the role of heterocyclic compounds ([[purine]]s and [[pyrimidine]]s) in the genetic code.


== Uses ==
== Uses ==
Heterocyclic compounds are pervasive in many areas of life sciences and technology.<ref name=Gilchrist>Thomas L. Gilchrist "Heterocyclic Chemistry" 3rd ed. Addison Wesley: Essex, England,
Heterocyclic compounds are pervasive in many areas of life sciences and technology.<ref name=Gilchrist>Thomas L. Gilchrist "Heterocyclic Chemistry" 3rd ed. Addison Wesley: Essex, England,
1997. 414 pp. {{ISBN|0-582-27843-0}}.</ref> Many drugs are heterocyclic compounds.<ref>{{Cite web|url=http://www.ipexl.com/share/f593e64bc3679cb669d02c007efdca17|title=IPEXL.com Multilingual Patent Search, Patent Ranking|website=www.ipexl.com}}</ref>
1997. 414 pp. {{ISBN|0-582-27843-0}}.</ref> Many drugs are heterocyclic compounds.<ref>{{Cite web|url=http://www.ipexl.com/share/f593e64bc3679cb669d02c007efdca17|title=IPEXL.com Multilingual Patent Search, Patent Ranking|website=www.ipexl.com|access-date=8 September 2010|archive-date=24 September 2015|archive-url=https://web.archive.org/web/20150924035914/http://www.ipexl.com/share/f593e64bc3679cb669d02c007efdca17|url-status=dead}}</ref>
==See also==
*[[Spiroketals]]


== References ==
== References ==
Line 574: Line 573:
* [http://www.chem.qmul.ac.uk/iupac/hetero/HW.html Hantzsch-Widman nomenclature, IUPAC]
* [http://www.chem.qmul.ac.uk/iupac/hetero/HW.html Hantzsch-Widman nomenclature, IUPAC]
* [http://www.cancer.gov/cancertopics/factsheet/Risk/heterocyclic-amines Heterocyclic amines in cooked meat, US CDC]
* [http://www.cancer.gov/cancertopics/factsheet/Risk/heterocyclic-amines Heterocyclic amines in cooked meat, US CDC]
* [http://www.cancer.org/docroot/PED/content/PED_1_3x_Known_and_Probable_Carcinogens.asp List of known and probable carcinogens, American Cancer Society]
* [http://www.cancer.org/docroot/PED/content/PED_1_3x_Known_and_Probable_Carcinogens.asp List of known and probable carcinogens, American Cancer Society] {{Webarchive|url=https://web.archive.org/web/20031213030702/http://www.cancer.org/docroot/PED/content/PED_1_3x_Known_and_Probable_Carcinogens.asp |date=13 December 2003 }}
* [http://www.scorecard.org/chemical-groups/one-list.tcl?short_list_name=p65 List of known carcinogens by the State of California], [[Proposition 65]] (more comprehensive)
* [http://www.scorecard.org/chemical-groups/one-list.tcl?short_list_name=p65 List of known carcinogens by the State of California], [[Proposition 65]] (more comprehensive)


Latest revision as of 15:52, 25 June 2024

For other uses of "ring structure", see Ring structure.

Structures and names of common heterocyclic compounds
Pyridine, a heterocyclic compound

A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s).[1] Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of organic heterocycles.[2]

Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass (cellulose and related materials), and many natural and synthetic dyes. More than half of known compounds are heterocycles.[3] 59% of US FDA-approved drugs contain nitrogen heterocycles.[4]

Classification

[edit]

The study of organic heterocyclic chemistry focuses especially on organic unsaturated derivatives, and the preponderance of work and applications involves unstrained organic 5- and 6-membered rings. Included are pyridine, thiophene, pyrrole, and furan. Another large class of organic heterocycles refers to those fused to benzene rings. For example, the fused benzene derivatives of pyridine, thiophene, pyrrole, and furan are quinoline, benzothiophene, indole, and benzofuran, respectively. The fusion of two benzene rings gives rise to a third large family of organic compounds. Analogs of the previously mentioned heterocycles for this third family of compounds are acridine, dibenzothiophene, carbazole, and dibenzofuran, respectively.

Heterocyclic organic compounds can be usefully classified based on their electronic structure. The saturated organic heterocycles behave like the acyclic derivatives. Thus, piperidine and tetrahydrofuran are conventional amines and ethers, with modified steric profiles. Therefore, the study of organic heterocyclic chemistry focuses on organic unsaturated rings.

Inorganic rings

[edit]

Some heterocycles contain no carbon. Examples are borazine (B3N3 ring), hexachlorophosphazenes (P3N3 rings), and tetrasulfur tetranitride S4N4. In comparison with organic heterocycles, which have numerous commercial applications, inorganic ring systems are mainly of theoretical interest. IUPAC recommends the Hantzsch-Widman nomenclature for naming heterocyclic compounds.[5]

Notes on lists

[edit]
  • "Heteroatoms" are atoms in the ring other than carbon atoms.
  • Names in italics are retained by IUPAC and do not follow the Hantzsch-Widman nomenclature
  • Some of the names refer to classes of compounds rather than individual compounds.
  • Also no attempt is made to list isomers.

3-membered rings

[edit]

Although subject to ring strain, 3-membered heterocyclic rings are well characterized.[6]

Three-membered rings; one heteroatom
Heteroatom Saturated Unsaturated
Boron Borirane Borirene
Nitrogen Aziridine Azirine
Oxygen Oxirane (ethylene oxide, epoxides) Oxirene
Phosphorus Phosphirane Phosphirene
Sulfur Thiirane (episulfides) Thiirene
Three-membered rings; two heteroatoms
Heteroatoms Saturated Unsaturated
2× Nitrogen Diaziridine Diazirine
Nitrogen + oxygen Oxaziridine Oxazirine
2× Oxygen Dioxirane
(highly unstable)

4-membered rings

[edit]
Four-membered rings; one heteroatom
Heteroatom Saturated Unsaturated
Nitrogen Azetidine Azete
Oxygen Oxetane Oxete
Phosphorus Phosphetane Phosphete
Sulfur Thietane Thiete
Four-membered rings; two heteroatoms
Heteroatoms Saturated Unsaturated
2× Nitrogen Diazetidine Diazete
2× Oxygen Dioxetane Dioxete
2× Sulfur Dithietane Dithiete

5-membered rings

[edit]

The 5-membered ring compounds containing two heteroatoms, at least one of which is nitrogen, are collectively called the azoles. Thiazoles and isothiazoles contain a sulfur and a nitrogen atom in the ring. Dithiolanes have two sulfur atoms.

A large group of 5-membered ring compounds with three or more heteroatoms also exists. One example is the class of dithiazoles, which contain two sulfur atoms and one nitrogen atom.

Five-membered rings; one heteroatom
Heteroatom Saturated Unsaturated
Antimony Stibolane Stibole
Arsenic Arsolane Arsole
Bismuth Bismolane Bismole
Boron Borolane Borole
Nitrogen Pyrrolidine ("Azolidine" not used) Pyrrole ("Azole" not used)
Oxygen Tetrahydrofuran Furan
Phosphorus Phospholane Phosphole
Selenium Selenolane Selenophene
Silicon Silacyclopentane Silole
Sulfur Tetrahydrothiophene Thiophene
Tellurium Tellurophene
Tin Stannolane Stannole
Five-membered rings; two heteroatoms
Heteroatoms Saturated Unsaturated (and partially unsaturated)
2× nitrogen Imidazolidine
Pyrazolidine 		Imidazole (Imidazoline)
Pyrazole (Pyrazoline)
Oxygen + sulfur 1,3-Oxathiolane
1,2-Oxathiolane 		Oxathiole (Oxathioline)
Isoxathiole
Nitrogen + Oxygen Oxazolidine
Isoxazolidine 		Oxazole (Oxazoline)
Isoxazole
Nitrogen + sulfur Thiazolidine
Isothiazolidine 		Thiazole (Thiazoline)
Isothiazole
2× oxygen Dioxolane
2× sulfur Dithiolane Dithiole
Five-membered rings; at least three heteroatoms
Heteroatoms Saturated Unsaturated
N N N Triazoles
N N O Furazan
Oxadiazole
N N S Thiadiazole
N O O Dioxazole
N S S Dithiazole
N N N N Tetrazole
N N N N O Oxatetrazole
N N N N S Thiatetrazole
N N N N N Pentazole

6-membered rings

[edit]
Six-membered rings; one heteroatom
Heteroatom Saturated Unsaturated Ions
Antimony Stibinin[7]
Arsenic Arsinane Arsinine
Bismuth Bismin[8]
Boron Borinane Borinine Boratabenzene anion
Germanium Germinane Germine
Nitrogen Piperidine
(Azinane not used) 		Pyridine
(Azine not used) 		Pyridinium cation
Oxygen Oxane Pyran
(2H-Oxine not used) 		Pyrylium cation
Phosphorus Phosphinane Phosphinine
Selenium Selenane Selenopyran[9] Selenopyrylium cation
Silicon Silinane Siline
Sulfur Thiane Thiopyran
(2H-Thiine not used) 		Thiopyrylium cation
Tellurium Tellurane Telluropyran Telluropyrylium cation
Tin Stanninane Stannine
Six-membered rings; two heteroatoms
Heteroatom Saturated Unsaturated
Nitrogen / nitrogen Diazinane Diazine
Oxygen / nitrogen Morpholine Oxazine
Sulfur / nitrogen Thiomorpholine Thiazine
Oxygen / Sulfur Oxathiane Oxathiin
Oxygen / oxygen Dioxane Dioxine
Sulfur / sulfur Dithiane Dithiin
Boron / nitrogen 1,2-Dihydro-1,2-azaborine
Six-membered rings; three heteroatoms
Heteroatom Saturated Unsaturated
Nitrogen Triazinane Triazine
Oxygen Trioxane
Sulfur Trithiane
Six-membered rings; four heteroatoms
Heteroatom Saturated Unsaturated
Nitrogen Tetrazine
2 nitrogen, 2 boron Carborazine
Six-membered rings; five heteroatoms
Heteroatom Saturated Unsaturated
Nitrogen Pentazine

Six-membered rings with six heteroatoms

[edit]

The hypothetical chemical compound with six nitrogen heteroatoms would be hexazine. Borazine is a six-membered ring with three nitrogen heteroatoms and three boron heteroatoms.


7-membered rings

[edit]

In a 7-membered ring, the heteroatom must be able to provide an empty π-orbital (e.g. boron) for "normal" aromatic stabilization to be available; otherwise, homoaromaticity may be possible.

Seven-membered rings; one heteroatom
Heteroatom Saturated Unsaturated
Boron Borepin
Nitrogen Azepane Azepine
Oxygen Oxepane Oxepine
Sulfur Thiepane Thiepine
Seven-membered rings; two heteroatoms
Heteroatom Saturated Unsaturated
Nitrogen Diazepane Diazepine
Nitrogen/sulfur Thiazepine

8-membered rings

[edit]
Heteroatom Saturated Unsaturated
Nitrogen Azocane Azocine
Oxygen Oxocane Oxocine
Sulfur Thiocane Thiocine
4 nitrogen, 4 boron Borazocine

9-membered rings

[edit]
Heteroatom Saturated Unsaturated
Nitrogen Azonane Azonine
Oxygen Oxonane Oxonine
Sulfur Thionane Thionine

Images of rings with one heteroatom

[edit]
Saturated Unsaturated
Heteroatom Nitrogen Oxygen Sulfur Nitrogen Oxygen Sulfur
3-atom ring Aziridine Oxirane Thiirane Azirine Oxirene Thiirene
Structure of aziridine Structure of oxirane Structure of thiirane Structure of azirine Structure of oxirene Structure of thiirene
4-atom ring Azetidine Oxetane Thietane Azete Oxete Thiete
Structure of acetidine Structure of oxetane Structure of thietane Structure of azete Structure of oxete Structure of thiete
5-atom ring Pyrrolidine Oxolane Thiolane Pyrrole Furan Thiophene
Structure of pyrrolidine Structure of oxolane Structure of thiolane Structure of pyrrole Structure of furan Structure of thiophene
6-atom ring Piperidine Oxane Thiane Pyridine Pyran Thiopyran
Structure of piperidine Structure of oxane Structure of thiane Structure of pyridine Structure of pyran Structure of thiopyran
7-atom ring Azepane Oxepane Thiepane Azepine Oxepine Thiepine
Structure of azepane Structure of oxepane Structure of thiepane Structure of azepine Structure of oxepine Structure of thiepine
8-atom ring Azocane Oxocane Thiocane Azocine Oxocine Thiocine
Structure of azocane Structure of oxocane Structure of thiocane Structure of azocine Structure of oxocine Structure of thiocine
9-atom ring Azonane Oxonane Thionane Azonine Oxonine Thionine
Structure of azonane Structure of oxonane Structure of thionane Structure of azonine Structure of oxonine Structure of thionine

Fused/condensed rings

[edit]

Heterocyclic rings systems that are formally derived by fusion with other rings, either carbocyclic or heterocyclic, have a variety of common and systematic names. For example, with the benzo-fused unsaturated nitrogen heterocycles, pyrrole provides indole or isoindole depending on the orientation. The pyridine analog is quinoline or isoquinoline. For azepine, benzazepine is the preferred name. Likewise, the compounds with two benzene rings fused to the central heterocycle are carbazole, acridine, and dibenzoazepine. Thienothiophene are the fusion of two thiophene rings. Phosphaphenalenes are a tricyclic phosphorus-containing heterocyclic system derived from the carbocycle phenalene.

History of heterocyclic chemistry

[edit]

The history of heterocyclic chemistry began in the 1800s, in step with the development of organic chemistry. Some noteworthy developments:[10]

  • 1818: Brugnatelli makes alloxan from uric acid
  • 1832: Dobereiner produces furfural (a furan) by treating starch with sulfuric acid
  • 1834: Runge obtains pyrrole ("fiery oil") by dry distillation of bones
  • 1906: Friedlander synthesizes indigo dye, allowing synthetic chemistry to displace a large agricultural industry
  • 1936: Treibs isolates chlorophyll derivatives from crude oil, explaining the biological origin of petroleum.
  • 1951: Chargaff's rules are described, highlighting the role of heterocyclic compounds (purines and pyrimidines) in the genetic code.

Uses

[edit]

Heterocyclic compounds are pervasive in many areas of life sciences and technology.[2] Many drugs are heterocyclic compounds.[11]

See also

[edit]

References

[edit]
  1. ^ IUPAC Gold Book heterocyclic compounds
  2. ^ a b Thomas L. Gilchrist "Heterocyclic Chemistry" 3rd ed. Addison Wesley: Essex, England, 1997. 414 pp. ISBN 0-582-27843-0.
  3. ^ Rees, Charles W. (1992). "Polysulfur-Nitrogen Heterocyclic Chemistry". Journal of Heterocyclic Chemistry. 29 (3): 639–651. doi:10.1002/jhet.5570290306.
  4. ^ Edon Vitaku, David T. Smith, Jon T. Njardarson (2014). "Analysis of the Structural Diversity, Substitution Patterns, and Frequency of Nitrogen Heterocycles among U.S. FDA Approved Pharmaceuticals". J. Med. Chem. 57 (24): 10257–10274. doi:10.1021/jm501100b. PMID 25255204.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Hantzsch–Widman name". doi:10.1351/goldbook.H02737
  6. ^ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, ISBN 978-0-471-72091-1
  7. ^ "Stibinin". chemspider. Royal Society of Chemistry. Retrieved 11 June 2018.
  8. ^ "Bismin". ChemSpider. Royal Society of Chemistry. Retrieved 11 June 2018.
  9. ^ "Selenopyranium". ChemSpider. Royal Society of Chemistry. Retrieved 11 June 2018.
  10. ^ Campaigne, E. (1986). "Adrien Albert and the rationalization of heterocyclic chemistry". Journal of Chemical Education. 63 (10): 860. Bibcode:1986JChEd..63..860C. doi:10.1021/ed063p860.
  11. ^ "IPEXL.com Multilingual Patent Search, Patent Ranking". www.ipexl.com. Archived from the original on 24 September 2015. Retrieved 8 September 2010.
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