Synthesis of 3-alkenyl-2-arylchromones and 2,3-dialkenylchromones via acid-catalysed retro-Michael ring opening of 3-acylchroman-4-ones

[Display omitted] 3-Acylchromones and 3-acylflavones, readily available by acylation of 2′-hydroxydibenzoylmethane with acid anhydrides in the presence of base, undergo efficient conjugate reduction with NaBH 4 in pyridine to give the corresponding chroman-4-ones/flavanones in high yields. The reduc...

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Bibliographic Details
Published in:Tetrahedron letters 2005-08, Vol.46 (33), p.5515-5519
Main Authors: Clarke, David S., Gabbutt, Christopher D., Hepworth, John D., Heron, B. Mark
Format: Article
Language:English
Subjects:
Chroman-4-ones
Chromones
Conjugate reduction
Flavones
Rearrangement
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Summary:[Display omitted] 3-Acylchromones and 3-acylflavones, readily available by acylation of 2′-hydroxydibenzoylmethane with acid anhydrides in the presence of base, undergo efficient conjugate reduction with NaBH 4 in pyridine to give the corresponding chroman-4-ones/flavanones in high yields. The reduction is both regio- and chemoselective. Treatment of the chroman-4-ones with MeSO 3H generates the 3-alkenyl-2-arylchromones by a dehydrative rearrangement initiated by retro-Michael cleavage of the pyranone ring. This reduction–rearrangement sequence can be extended to 2-alkyl-3-alkenoylchromones to generate 3-alkenyl-2-styrylchromones, the first examples of 2,3-dialkenylchromones.
ISSN:0040-4039
1873-3581
DOI:10.1016/j.tetlet.2005.06.058