A new synthesis of flavones

  • N. Narasimhachari
  • T. R. Seshadri


Iodine, in the presence of hot alcoholic sodium acetate, is shown to be a convenient reagent for the conversion of hydroxy flavanones into flavones. Naringenin, its 4′ and 4′: 7-dimethyl ethers, hesperetin and its dimethyl ether are thus oxidised smoothly into apigenin and its ethers and diosmetin respectively. The method is also suitable for glycosides; examples chosen are naringin, its monomethyl ether and hesperidin. The constitution of apiin is discussed and confirmed by correlation with that of naringin.

The method works smoothly in all cases where a free hydroxyl is present in the 5-position. In its absence a mixture is formed; by working in the cold the flavones can be obtained, whereas in the hot benzalcoumaranones could be isolated. In such cases the suitability of the phosphorus pentachloride method has been tested using 7-methoxy flavanone.

The reaction is considered to involve (1) iodination of the 3-position and (2) elimination of hydriodic acid and these are brought about smoothly with the help of the active and unstable acetate ions. If the second stage involves iodinated flavanone, flavone is obtained; on the other hand if the corresponding iodinated chalkone is present, benzal-coumaranone results.


Flavone Apigenin Naringenin Flavanone Naringin 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    RobinsonNature, 1936,137, 172. Robinson,et al. Phil. Trans. Roy. Soc., 1939,230 B, 149.CrossRefGoogle Scholar
  2. 2.
    Feuerstein and KostaneckiBer., 1898,31, 1757.Google Scholar
  3. 3.
    Kostanecki and TamborIbid.,, 1899,32, 2263. Cullinane and PhilpottJ.C.S., 1929, 1761. WheelerProc. Nat. Inst. Sci. (India), 1939,5, 267.Google Scholar
  4. 4.
    Mahal, Rai and VenkataramanJ.C.S., 1935, 866.Google Scholar
  5. 5.
    Kostanecki, Levi and TamborBer., 1899,32, 326.Google Scholar
  6. 6.
    Zemplen and BognarIbid.,, 1943,76, 452.Google Scholar
  7. 7.
    HattoriActa. Phyto. Chim., 1925,2, 99.Google Scholar
  8. 8.
    ButenandtAnn., 1928,464, 270. LaForge and SmithJ.A.C.S., 1930,52, 109.Google Scholar
  9. 9.
    Von GerichtenBer., 1900,33, 2908.Google Scholar
  10. 10.
    Perkin and HorsfallJ.C.S., 1900,77, 1315.Google Scholar
  11. 11.
    Rangaswami, Seshadri and VeeraraghaviahProc. Ind. Acad. Sci., A, 1939,9, 328. Narasimhachari and SeshadriIbid., Proc. Ind. Acad. Sci., A, 1948,27, 223.Google Scholar
  12. 12.
    PerkinJ.C.S., 1897,71, 805.Google Scholar
  13. 13.
    Chakravarti and GhoshJ.I.C.S., 1944, 171.Google Scholar
  14. 14.
    Czajnowski, Kostanecki and TamborBer., 1900,33, 1996.Google Scholar
  15. 15.
    Robinson and VenkataramanJ.C.S., 1926, 2344. Rao, Seshadri and ViswanadhamProc. Ind. Acad. Sci. A, 1949,29, 72.Google Scholar
  16. 16.
    Oestrele and WanderHelv. Chim. Acta., 1925,8, 519.CrossRefGoogle Scholar
  17. 17.
    Shinoda and SatoJ. Pharm. Soc. Japan, 1929,49, 71.Google Scholar
  18. 18.
    NakaokiIbid.,, 1938,58, 639.Google Scholar
  19. 19.
    Kostanecki, Lampe and TamborBer., 1904,37, 1402.Google Scholar
  20. 20.
    Geissman and FukushimaJ.A.C.S., 1948,70, 1686.CrossRefGoogle Scholar
  21. 21.
    Freudenberg and KammulerAnn., 1927,451, 209.Google Scholar

Copyright information

© Indian Academy of Sciences 1949

Authors and Affiliations

  • N. Narasimhachari
    • 1
  • T. R. Seshadri
    • 1
  1. 1.Department of ChemistryAndhra UniversityWaltair

Personalised recommendations