Chromene

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Chromene
Surname 2 H- chromene 4 H- chromene
other names 2-benzopyran 4-benzopyran
Structural formula Structure of 2H-chromene Structure of 4H-chromene
CAS number 254-04-6 254-03-5
? (Mixture of isomers)
PubChem 9211 136068
Molecular formula C 9 H 8 O
Molar mass 132.16 g mol −1
Physical state liquid
Brief description
Melting point <25 ° C ? ° C
boiling point 92 ° C (13 mbar) 77 ° C (10 mbar)
density 1.10 g cm −3 ? g cm −3
solubility insoluble in water
GHS
labeling
no classification available
H and P phrases see above
see above
see above
Toxicological data 250 mg kg −1 ( LD 50 ,  mouse ,  ip )

The two organic chemical compounds 2 H chromene and 4 H chromene are referred to as chromenes (also: benzopyrans ) . These belong to the aromatic compounds and the heterocycles , since the ring system contains the heteroatom oxygen . Both substances are isomers that differ only in the position of the double bond in the heterocyclic six-membered ring.

Occurrence, derivatives and uses

2 H- Chromene occurs in the myrtle family Calyptranthes tricona . Derivatives of 2 H chromium act as potent potassium channel openers and are used as medicinal substances ( Cromakalim , Lemakalim ); Carbocromen is used for heart therapy. From 2 H -chromen guided coumarin and umbelliferone from from 4 H -chromen the chromone , the anthocyanidins and flavones . By hydrogenation of the pyran ring one obtains the chroman , which z. B. represents the basic building block of the tocopherols , the Rotenoids and some cannabinoids . Many alkaloids also contain a chromene structure as a chromophore .

Isochromes

Positional isomers of the two chromenes are the 1 H -isochromes and the 3 H -isochromes, in which the oxygen atom is in position 2.

  • 1 H isochromes

  • 3 H isochromes

presentation

A simple one-step synthesis of 2 H- chromene according to Yoshiyuki Kawase is possible by direct cyclization of salicylaldehyde with propene carboxylic acid esters in DMF . The synthesis of 2 H chromene is also carried out by a Wittig reaction and subsequent ring closure starting from the sodium salt of salicylaldehyde and vinyl triphenylphosphonium bromide.

literature

Individual evidence

  1. ↑ a b Entry for 1,2-benzopyran in the ChemIDplus database of the United States National Library of Medicine (NLM), accessed on July 31, 2018 or earlier.
  2. ↑ a b Scheweizer, EE: Reactions of Phosphorus Compounds. III. A New General Ring Synthesis from Vinyltriphenylphosphonium Bromide in J. Am. Chem. Soc. 86 (1964) 2744. doi : 10.1021 / ja01067a061
  3. ↑ DR Lide, GWA Milne: Handbook of Data on Organic Compounds. 3rd edition, CRC Press, 1994, ISBN 9780849304453 , p. 1548.
  4. ^ A b D. R. Lide, GWA Milne: Handbook of Data on Common Organic Compounds. CRC Press, 1995, ISBN 9780849304040 , p. 568.
  5. ↑ With regard to its dangerousness, the substance has not yet been classified by the EU, a reliable and citable source has not yet been found.
  6. ↑ European Journal of Medicinal Chemistry . Vol. 11, p. 81, 1976.
  7. ↑ a b Sabine Plücker: Investigations on the representation of radioligands from the series of potassium channel openers of the benzopyran type (PDF; 2.0 MB) , dissertation at Heinrich Heine University Düsseldorf , 2004.
  8. ^ IW Southon, GA Cordell, J. Buckingham: Dictionary of alkaloids. CRC Press, 1989, ISBN 9780412249105 .
  9. ↑ Kawase, Y., Yamaguchi, S., Horita, H., Takeno, J., Kameyama, H .: Bull. Chem. Soc. Jpn. , 1982, 55, 1153-1155.