Benzopyran

Benzopyran
Identifiers
CAS Number	2H-chromene: 254-04-6 [PubChem];
3D model (JSmol)	2H-chromene: Interactive image;
Beilstein Reference	109871
ChEBI	2H-chromene: CHEBI:35601;
ChemSpider	2H-chromene: 8856 ;
PubChem CID	2H-chromene: 9211;
UNII	2H-chromene: 7U3W6XRV5U;
CompTox Dashboard (EPA)	2H-chromene: DTXSID80180051 ;
	InChI InChI=1S/C9H8O/c1-2-6-9-8(4-1)5-3-7-10-9/h1-6H,7H2 Key: KYNSBQPICQTCGU-UHFFFAOYSA-N ;
	SMILES 2H-chromene: C1=Cc2ccccc2OC1;
Properties
Chemical formula	C9H8O
Molar mass	132.162 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Benzopyran is a polycyclic organic compound that results from the fusion of a benzene ring to a heterocyclic pyran ring.

According to current IUPAC nomenclature, the name chromene used in previous recommendations is retained; however, systematic ‘benzo’ names, for example 2H-1-benzopyran, are preferred IUPAC names for chromene, isochromene, chromane, isochromane, and their chalcogen analogues.^[1] There are two isomers of benzopyran that vary by the orientation of the fusion of the two rings compared to the oxygen, resulting in 1-benzopyran (chromene) and 2-benzopyran (isochromene)—the number denotes where the oxygen atom is located by standard naphthalene-like nomenclature.

Some benzopyrans have shown anticancerous activity in vitro.^[2]

The radical form of benzopyran is paramagnetic. The unpaired electron is delocalized over the whole benzopyran molecule, rendering it less reactive than one would expect otherwise. A similar example is the cyclopentadienyl radical. Commonly, benzopyran is encountered in the reduced state, in which it is partially saturated with one hydrogen atom, introducing a tetrahedral CH₂ group in the pyran ring. Therefore, there are many structural isomers owing to the multiple possible positions of the oxygen atom and the tetrahedral carbon atom:

Structural isomers of chromene
2H-chromene (2H-1-benzopyran)	4H-chromene (4H-1-benzopyran)
5H-chromene	7H-chromene
8aH-chromene

Structural isomers of isochromene
1H-isochromene (1H-2-benzopyran)	3H-isochromene (3H-2-benzopyran)

References

^ "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. P001–P004. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
^ Stevenson, Alexander J; Ager, Eleanor I; Proctor, Martina A; Škalamera, Dubravka; Heaton, Andrew; Brown, David; Gabrielli, Brian G (2018). "Mechanism of action of the third generation benzopyrans and evaluation of their broad anti-cancer activity in vitro and in vivo". Scientific Reports. 8 (1): 5144. Bibcode:2018NatSR...8.5144S. doi:10.1038/s41598-018-22882-w. PMC 5865165. PMID 29572477.

[IUPAC2013-1] "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. P001–P004. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.

[2] Stevenson, Alexander J; Ager, Eleanor I; Proctor, Martina A; Škalamera, Dubravka; Heaton, Andrew; Brown, David; Gabrielli, Brian G (2018). "Mechanism of action of the third generation benzopyrans and evaluation of their broad anti-cancer activity in vitro and in vivo". Scientific Reports. 8 (1): 5144. Bibcode:2018NatSR...8.5144S. doi:10.1038/s41598-018-22882-w. PMC 5865165. PMID 29572477.

[1]

[2]

See also

References