Isoindole: Difference between revisions

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| ImageFile1 = Isoindole-3D-balls-2.png

| PIN=2''H''-Isoindole<ref>{{cite book |author=[[International Union of Pure and Applied Chemistry]] |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=[[Royal Society of Chemistry|The Royal Society of Chemistry]] |pages=213 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}</ref>

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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

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| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = PR6T8TL5NT

| PubChem=3013853

| ChEBI_Ref = {{ebicite|correct|EBI}}

| SMILES = c1cccc2c1c[nH]c2

|Section2={{Chembox Properties

| Formula=C₈H₇N

| MolarMass=117.15 g/mol

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In [[organic chemistry]] and [[heterocyclic chemistry]], '''isoindole''' consists of a [[benzene]] ring fused with [[pyrrole]].<ref>{{ cite book | author = Gilchrist, T. L. | title = Heterocyclic Chemistry | year = 1987 | publisher = Longman | isbn = 0-582-01422-0 }}</ref> The compound is an [[isomer]] of [[indole]]. Its [[organic reduction|reduced]] form is [[isoindoline]]. The parent isoindole is a rarely encountered in the technical literature, but substituted derivatives are useful commercially and occur naturally. Isoindoles units occur in [[phthalocyanine]]s, an important family of dyes. Some [[alkaloid]]s containing isoindole have been isolated and characterized.<ref name= Heugebaert>Heugebaert, Thomas S. A.; Roman, Bart I.; Stevens, Christian V. "Synthesis of isoindoles and related iso-condensed heteroaromatic pyrroles" Chemical Society Reviews 2012, volume 41, pp. 5626-5640. {{doi|10.1039/c2cs35093a}}</ref><ref>See for example: {{Cite journal

| last1 = Zhang | first1 = X.

| last2 = Ye | first2 = W.

| last3 = Zhao | first3 = S.

| last4 = Che | first4 = C. T.

| title = Isoquinoline and isoindole alkaloids from Menispermum dauricum

| doi = 10.1016/j.phytochem.2003.12.004

| journal = Phytochemistry

| volume = 65

| issue = 7

| pages = 929–932

| year = 2004

| pmid = 15081297

| pmc =

}}</ref>

==Synthesis==

The parent isoindole was prepared by [[flash vacuum pyrolysis]] of an N-substituted isoindoline.<ref>R. Bonnett and R. F. C. Brown "Isoindole" J. Chem. Soc., Chem. Commun., 1972, 393-395. {{doi|10.1039/C39720000393}}</ref> N-Substituted isoindoles, which are easier to handle, can be prepared by dehydration of isoindoline-N-oxides. They also arise by myriad other methods, e.g., starting from xylylene dibromide (C₆H₄(CH₂Br)₂).

==Structure and tautomerism of 2-H-isoindoles ==

Unlike indole, isoindoles exhibit noticeable alternation in the C-C bond lengths, which is consistent with their description as pyrrole derivatives fused to a butadiene.

In solution, the 2''H''-isoindole [[tautomer]] predominates. It resembles a [[pyrrole]] more than a simple [[imine]].<ref>{{cite book | title = Handbook of Heterocyclic Chemistry |author1=Alan R. Katritzky |author2=Christopher A. Ramsden |author3=J. Joule |author4=Viktor V. Zhdankin | page = 133 | publisher = Elsevier | year = 2010}}</ref> The degree to which the 2''H'' predominates depends on the solvent, and can vary with the substituent in substituted isoindoles.<ref>{{cite book | title = Heterocyclic Chemistry |author1=John A. Joule |author2=Keith Mills | publisher = John Wiley & Sons | year = 2010 | page = 447}}</ref>

:[[File:Isoindoletautomerism.svg|thumb|left|400px|2''H''-Isoindole (right) is the predominant tautomer relative to 1''H''-isoindole (left)]]{{clear left}}

N-Substituted isoindoles do not engage is tautomerism and are therefore simpler to study.

== Isoindole-1,3-diones and related derivatives==

The commercially important [[phthalimide]] is an ''isoindole-1,3-dione'' with two [[carbonyl]] groups attached to the heterocyclic ring.

<gallery caption="Illustrative Isoindoline Derivatives" widths="130px" heights="120px" >

File:PY139.svg|[[Pigment yellow 139]], a common high performance pigment.

File:PY185.svg|[[Pigment yellow 185]], a common high performance pigment.

File:Copper phthalocyanine.svg|[[Copper phthalocyanine]], one of the most pervasive synthetic pigments.

</gallery>

* [[1,3-Disubstituted Isoindolines]].

* [[Isoindene]] with nitrogen replaced by a [[methylene group]].

{{Simple aromatic rings}}

[[Category:Isoindoles| ]]

[[Category:Simple aromatic rings]]