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Darzens reaction of 2‐bromo‐4,6‐dimethoxy‐3(2 H )‐benzofuranone with aromatic aldehydes to form flavonoids
Author(s) -
Ottersbach Philipp A.,
Bolek David,
Lepičová Eva,
Gütschow Michael,
Nieger Martin
Publication year - 2008
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570450432
Subject(s) - chemistry , flavonols , adduct , ring (chemistry) , derivative (finance) , medicinal chemistry , stereochemistry , organic chemistry , flavonoid , antioxidant , financial economics , economics
The applicability of 2‐bromo‐4,6‐dimethoxy‐3(2 H )‐benzofuranone ( 1 ) to produce flavonoid‐derived epoxides in the course of the Darzens reaction with aldehydes was investigated. However, instead of the epoxides, flavonols 3 and, in certain cases, benzofuranyl‐substituted flavonols 4 were isolated. The generation of 3 is assumed due to a ring expansion of the initially formed epoxides. These flavonols can react with 1 to produce the unexpected 1:2 adducts 4 as minor products. The structure of the hexamethoxy derivative 4b (R 1 = H, R 2 = R 3 = OMe) was confirmed by X‐ray crystallographic analysis.