A simple and effective preparation of quercetin pentamethyl ether from quercetin.
Beilstein J Org Chem
; 14: 3112-3121, 2018.
Article
em En
| MEDLINE
| ID: mdl-30643589
ABSTRACT
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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Beilstein J Org Chem
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Japão