4H-1-Benzopyran

4H-1-Benzopyran
Names
Preferred IUPAC name
4H-1-Benzopyran
Identifiers
3D model (JSmol)
111589
ChEBI
ChemSpider
  • InChI=1S/C9H8O/c1-2-6-9-8(4-1)5-3-7-10-9/h1-4,6-7H,5H2
    Key: JCIDEANDDNSHQC-UHFFFAOYSA-N
  • C1C=COC2=CC=CC=C21
Properties
C9H8O
Molar mass 132.162 g·mol−1
Appearance colorless
Density 1.0732 g/cm3
Boiling point 80 °C (176 °F; 353 K) 13 Torr
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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4H-1-Benzopyran is an organic compound with the formula C6H4C3H4O. It is one of two isomers of benzopyran, the other being 2H-1-benzopyran, which is more prevalent. It can be viewed as the fusion of a benzene ring to a heterocyclic pyran ring.

Some benzopyrans have shown anticancerous activity in vitro.

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)

Nomenclature

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. 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.

See also

References

  1. ↑ Pratap, Ramendra; Ram, Vishnu Ji (2014). "Natural and Synthetic Chromenes, Fused Chromenes, and Versatility of Dihydrobenzo[ h ]chromenes in Organic Synthesis". Chemical Reviews. 114 (20): 10476–10526. doi:10.1021/cr500075s.
  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.
  3. ↑ "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.