Heterocyclic synthesis with β‐ketosulfoxides IV. Synthesis of 3‐substituted chromones

Abstract

A novel synthesis of 3‐(hydroxymethyl)chromones from o‐hydroxy‐ω‐(methylsulfinyl)acetophenones has been developed. These have been utilized in the synthesis of 3‐formyl, 3‐cyano, 3‐carboxy, 3‐carboxamido, 3‐chloromethyl, 3‐aminomethyl and 3‐methoxymethylchromones.

ChemInform Abstract: Reactions of 3‐Substituted Chromones with ortho‐Phenylenediamine.

“…Column chromatography was performed on Merck silica gel 70-270 mesh. The starting materials 1 were prepared according to literature methods [18].…”

3-Formylchromones as diverse building blocks in heterocycles synthesis

“…Interaction of equimolar amount of 3-formyl-6-chlorochromone (1c) with 4-acetyl-5,6-diphenylpyridazin-3(2H)-one (6) in sodium ethoxide afforded 4-[3-(6-chloro-4-oxochromen-3-yl)prop-2-enoyl]-5,6-diphenylpyridazin-3(2H)-one (7) in 87% yield. When this reaction was carried out in ethanol containing few drops of piperidine, 7-(6-chloro-4-oxochromen-3-yl)-3,4-diphenyl-6,7-dihydropyrano[2,3-c]-pyraidazin-5-one (8) was obtained in 55% yield, via intramolecular cycloaddition reaction in compound 7 (Scheme 4) [24].…”

“…Under acidic conditions, p-cresol underwent 1,2-addition through C-2 atom to thealdehyde function of 3-formyl chromone (1a) to produce intermediate 150 which, converted to 2,14-dimethyl-10aH,15aH-tribenzo[b,e,i] [1,6,7] trioxaphenalene (151) (Scheme 74) [97].…”

“…3-Formylchromones are also known as 4-oxo-4H-1-benzopyran-3-carboxaldehydes, 4-oxo-4H-chromene-3-carboxaldehydes and chromone-3-carboxaldehydes. Although many methods are known for the synthesis of 3-formylchromones, Vilsmeier-Haack reaction on substituted 2-hydroxyacetophenones is the most suitable among them [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In Vilsmeier-Haack reaction, the reaction takes place via double formylation of o-hydroxyacetophenones followed by cycloaddition with concomitant dehydration (Scheme 1).…”

Chemistry of 4-oxo-4H-1-benzopyran-3-carbonitrile

“…3-Formylchromone 5 when refluxed with hydroxylamine hydrochloride in ethanol containing hydrochloric acid gives via the aldoxime 6 a mixture of the nitrile 1 (76%) and the isoxazole 8 (8%), the latter being converted to the former by heating in dimethyl sulphoxide [2,3]. Heating a mixture of 5, hydroxylamine hydrochloride and sodium formate in formic acid under reflux produces 1 in 51% yield [4]. Sulphuric acid catalyzed conversion of the oxime ether 7 (R = Me) [5a] and zirconium tetrachloride mediated conversion of 7 (R = Ar) [5b] to the nitrile 1 are also known.…”