Chemistry:Algar–Flynn–Oyamada reaction
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The Algar–Flynn–Oyamada reaction is a chemical reaction whereby a chalcone undergoes an oxidative cyclization to form a flavonol.[1][2]
Reaction mechanism
There are several possible mechanisms to explain this reaction; however, these reaction mechanisms have not been elucidated. What is known is that a two-stage mechanism exists. First, dihydroflavonol is formed, which then subsequently oxidizes to form a flavonol.
Proposed mechanisms involving epoxidation of the alkene have been disproven.[3]
The probable mechanisms are thus two possibilities:
- The phenoxide attacks the enone at the beta position, and the alkene directly attacks hydrogen peroxide from the alpha position, forming the dihydroflavonol.
- The phenoxide attacks the enone at the beta position, closing the six-membered ring and forming an enolate intermediate. The enolate then attacks hydrogen peroxide, forming the dihydroflavonol.
See also
References
- ↑ Algar, J.; Flynn, J. P. (1934). "none". Proceedings of the Royal Irish Academy 42B: 1.
- ↑ Oyamada, B. (1935). "A New General Method for the Synthesis of the Derivatives of Flavonol". Bulletin of the Chemical Society of Japan 10 (5): 182–186. doi:10.1246/bcsj.10.182.
- ↑ Gormley, T.R.; O'Sullivan, W.I. (1973). "Flavanoid epoxides—XIII". Tetrahedron 29 (2): 369–373. doi:10.1016/S0040-4020(01)93304-6. ISSN 0040-4020.
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