Synthesis of 3-alkenyl-2-arylchromones and 2,3-dialkenylchromones via acid-catalysed retro-Michael ring opening of 3-acylchroman-4-ones
摘要:
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 NaBH4 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 MeSO3H 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. (c) 2005 Elsevier Ltd. All rights reserved.
Conjugate addition to chromones: Synthesis of substituted 4-chromanones
作者:Timothy W. Wallace
DOI:10.1016/s0040-4039(01)81422-2
日期:1984.1
Chromones activated by carbonyl substituents at C-3 are transformed into the corresponding 2-methyl 4-chromanones by treating with lithium dimethylcuprate
Conjugate addition of cuprate reagents to chromones: A route to 2-substituted chroman-4-ones
作者:Suthiweth T. Saengchantara、Timothy W. Wallace
DOI:10.1016/s0040-4020(01)88394-0
日期:1990.1
Chromones (4-oxo-4H-1-benzopyrans) activated by electron-withdrawing groups attached to C-3 undergo efficient 1,4-additon of cuprate reagents, producing 2,3-disubstituted chroman-4-ones. The addition products from methyl chromone-3-carboxylates can be converted into 2-substitutedchroman-4-ones by treatment with sodium chloride in wet dimethylsulphoxide.