Cargando…

A simple and effective preparation of quercetin pentamethyl ether from quercetin

Among the five hydroxy (OH) groups of quercetin (3,5,7,3',4'-pentahydroxyflavone), the OH group at 5 position is the most resistant to methylation due to its strong intramolecular hydrogen bonding with the carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pent...

Descripción completa

Detalles Bibliográficos
Autores principales: Tatsuzaki, Jin, Ohwada, Tomohiko, Otani, Yuko, Inagi, Reiko, Ishikawa, Tsutomu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Beilstein-Institut 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317434/
https://www.ncbi.nlm.nih.gov/pubmed/30643589
http://dx.doi.org/10.3762/bjoc.14.291
Descripción
Sumario:Among the five hydroxy (OH) groups of quercetin (3,5,7,3',4'-pentahydroxyflavone), the OH group at 5 position is the most resistant to methylation due to its strong intramolecular hydrogen bonding with the carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pentamethyl ether efficiently by conventional methylation. Here, we describe a simple and effective per-O-methylation of quercetin with dimethyl sulfate in potassium (or sodium) hydroxide/dimethyl sulfoxide at room temperature for about 2 hours, affording quercetin pentamethyl ether (QPE) quantitatively as a single product. When methyl iodide was used in place of dimethyl sulfate, the C-methylation product 6-methylquercetin pentamethyl ether was also formed. A computational study provided a rationale for the experimental results.