2-Phenylchromone

The structures of the isoxazoles (393) were all consistent with their mass spectral fragmentation patterns. The reaction of hydroxylamine with 3-phenylchromone (394) gave exclusively 5-(o-hydroxyphenyl)isoxazole (395) (78ACH(97)69). 

Chromones (14) and flavones (phenylchromones, 15) are pyranones when they have a hydroxyl group substituted in such a position that they can act as bidentate 0,0-donors then they and their complexes are relevant to the present review. Fig. 3 shows formulae for chromone, flavone, and the polyhydroxyflavones (16-20) which appear in this review. 

Flavone or 2-Phenylchromone, C15H10°2> and other flavones are the parents of a > number of yel natural dyes found in plants, leaves, fruits and flowers. The natural materials contain OH groups and occur un combined or as glucosides. Nitration occurs in 2-phenyl group giving a mixture of 2y- ... 

An interesting conversion of 2,6-dimethylpyran -4-one (408) into 7-methyl-5-phenylchromone (410) is achieved by reaction with the anion of acetophenone and cycliz-ation of the 2-hydroxyacetophenone (409) (77AP744). 

Trihydroxy-2-methylanthraquinone. See Aloeemodine A140-R 4 ,5,7-Trihydroxy-2-phenylchromone. See Apigenin A473-R... 

The parent nucleus of the flavonoids is flavone ((58), 2-phenylchromone or 2-phenylbenzopyran-4-one). Flavone and isoflavone ((59), 3-phenylchromone, the parent nucleus of the isoflavonoids) are the simplest oxygen-containing naturally occurring compounds that possess the 2-phenylnaphthalene -type structure. The chalcones, represented by the nucleus (60), may be regarded as open-chain flavonoids and are usually hydroxylated. The interconversion of chalcone and flavonone catalyzed by chalcone isomerase is well known [326, 327, 331], Chalcones can be precursors of both the flavonoids and the isoflavonoids [326-332]. 

Flavonoids, low-molecular-weight substances found in all vascular plants, are phenylbenzo-pyrones (phenylchromones) with an assortment of structures based on a common three-ring nucleus. They are usually subdivided according to their substituents into flavanols, anthocyanidins, flavones, flavanones, and chalcones. 

Flavone (2-phenylchromone) (68) is more labile to hydrogenolysis at the ether linkage than are 2-alkylchromones because it may be considered to be a benzyl-phenyl-type ether. Hydrogenation of flavone over copper-chromium oxide at 140-150°C gave 4-flavanol in a maximum yield of 65% in a very rapid reaction (8 min), while the flavanol was obtained in a yield of 85% in rapid hydrogenation of flavanone (69) at 135-145°C or in a yield of 93% in the hydrogenation in a dilute ethanol solution at 120-135°C (eq. 12.123).233... 

Apigenin 4, 5,7-Trihydroxyflavone or 4, 5,7-Trihydroxy-2-phenylchromone, called in Ger 5.7.4 -Trioxy-flavon or 5.7-Dioxy-2-[4 -oxy-phenyl]-chromon. 0-i- CsH, OH... 

Substituted chromones are formed by heating terminal acetylenes with o-iodophenols under carbon monoxide pressure in the presence of palladium[bis(diphenylphosphino-ferrocene)] dichloride e.g. o-iodophenol and phenylacetylene afford 2-phenylchromone (equation 61) ". Acetylenic aldiminium salts undergo cyclization to six-membered nitrogen heterocycles in polar aprotic solvents. Thus heating solutions of 5-(butylamino) pent-1-yne (607), an aldehyde RCHO (R = Me, Et, Ph or C02Et) and tetrabutylammonium iodide in acetonitrile yields the piperidine derivatives 608 and similar reactions of 4-(benzylamino)but-l-yne lead to tetrahydropyridines 609. ... 

Takeda s acrylic acid (LXXXIV) (5fl), Carlo Erba s 2-phenylchromone-6-carboxyiic acid (LXXXV) (57), and Miles CPTC chromone tetrazole (LXXXVI) (52) appear to be orally active in the PCA procedure. However, precise ED50 values have not been reported and clinical reports have not yet appeared. 

Isoflavonot. A group of mostly yellow plant pigments, sometimes also designated as isoflavonoids, belonging to the flavonoids and derived from isofla-vone (3-phenylchromone) however, the I. are of less importance than their isomers, the flavones. The parent compound of the isoflavones, isoflavone (3-phenyIchromone, 3-phenyl-4ff-1 -benzopyran-4-one) occurs in clover species. 

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