4H-1-Benzopyran
Script error: No such module "Unsubst".
Template:Chembox Script error: No such module "redirect hatnote".
4H-1-Benzopyran is an organic compound with the formula Template:Chem2. 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.[1]
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:
| File:2H-Chromen.svg 2H-chromene (2H-1-benzopyran) |
File:4H-Chromen.svg 4H-chromene (4H-1-benzopyran) |
| 5H-chromene | 7H-chromene |
| 8aH-chromene |
| File:1H-Isochromen.svg 1H-isochromene (1H-2-benzopyran) |
File:3H-Isochromen.svg 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.[3] 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
<templatestyles src="Reflist/styles.css" />
Script error: No such module "Check for unknown parameters".